Luminescence characteristics of C5+ ions and 60Co irradiated Li2BaP2O7:Dy3+ phosphor

NASA Astrophysics Data System (ADS)

Wani, J. A.; Dhoble, N. S.; Lochab, S. P.; Dhoble, S. J.

2015-04-01

In this work a study on some thermoluminescence characteristics of Li2BaP2O7:Dy phosphor is presented. The phosphor was synthesized by solid state diffusion method and characterized for its phase purity by X-ray diffraction (XRD). FT-IR spectrum was also carried out to confirm the presence of phosphate family and vibrations corresponding to P-O-P group. Spectroscopic investigation was approached through photoluminescence (PL) and thermoluminescence (TL). PL emission spectrum of Dy3+ ions corresponding to 4F9/2 → 6H13/2 (483 nm) and 4F9/2 → 6H15/2 (574 nm) transitions is revealed under 351 nm excitation wavelength. This characteristic emission confirms the presence of Dy3+ ions in the Li2BaP2O7 host matrix. To induce TL properties in Li2BaP2O7:Dy phosphor was irradiated with C5+ ion beams and gamma rays (60Co). A nearly simple glow curve was observed for Li2BaP2O7:Dy under two different excitation sources. TL response is almost linear over a wide range. Average absorbed dose (D bar) and mean linear energy transfer (LET ‾) of C5+ ion beams in Li2BaP2O7:Dy have also been calculated. Values of parameters like E and S known as trap depth and frequency factor respectively were obtained by using TLanal computer program. Also SRIM based calculations were performed to study the effect of C5+ ion beams on the samples of Li2BaP2O7:Dy. SRIM calculations show that Ba2+ vacancies are highest in number. Till date no such luminescence information on Li2BaP2O7:Dy phosphor is available.

Effect of Ligand Field Tuning on the SMM Behavior for Three Related Alkoxide-Bridged Dysprosium Dimers.

PubMed

Peng, Yan; Mereacre, Valeriu; Baniodeh, Amer; Lan, Yanhua; Schlageter, Martin; Kostakis, George E; Powell, Annie K

2016-01-04

The synthesis and characterization of three Dy2 compounds, [Dy2(HL1)2(NO3)4] (1), [Dy2(L2)2(NO3)4] (2), and [Dy2(HL3)2(NO3)4] (3), formed using related tripodal ligands with a central tertiary amine bearing picolyl and alkoxy arms, 2-[(2-hydroxy-ethyl)-pyridin-2-ylmethylamino]-ethanol (H2L1), 2-(bis-pyridin-2-ylmethylamino)-ethanol (HL2), and 2-(bis-pyridin-2-ylmethylamino)-propane-1,3-diol (H2L3), are reported. The compounds are rare examples of alkoxide-bridged {Dy2} complexes and display capped square antiprism coordination geometry around each Dy(III) ion. Changes in the ligand field environment around the Dy(III) ions brought about through variations in the ligand donors can be gauged from the magnetic properties, with compounds 1 and 2 showing antiparallel coupling between the Dy(III) ions and 3 showing parallel coupling. Furthermore, slow relaxation of the magnetization typical of SMM behavior could be observed for compounds 2 and 3, suggesting that small variations in the ligand field can have a significant influence on the slow relaxation processes responsible for SMM behavior of Dy(III)-based systems.

Effect of Ligand Substitution around the Dy(III) on the SMM Properties of Dual-Luminescent Zn-Dy and Zn-Dy-Zn Complexes with Large Anisotropy Energy Barriers: A Combined Theoretical and Experimental Magnetostructural Study.

PubMed

Costes, Jean Pierre; Titos-Padilla, Silvia; Oyarzabal, Itziar; Gupta, Tulika; Duhayon, Carine; Rajaraman, Gopalan; Colacio, Enrique

2016-05-02

The new dinuclear Zn(II)-Dy(III) and trinuclear Zn(II)-Dy(III)-Zn(II) complexes of formula [(LZnBrDy(ovan) (NO3)(H2O)](H2O)·0.5(MeOH) (1) and [(L(1)ZnBr)2Dy(MeOH)2](ClO4) (3) (L and L(1) are the dideprotonated forms of the N,N'-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato and 2-{(E)-[(3-{[(2E,3E)-3-(hydroxyimino)butan-2-ylidene ]amino}-2,2-dimethylpropyl)imino]methyl}-6-methoxyphenol Schiff base compartmental ligands, respectively) have been prepared and magnetostructurally characterized. The X-ray structure of 1 indicates that the Dy(III) ion exhibits a DyO9 coordination sphere, which is made from four O atoms coming from the compartmental ligand (two methoxy terminal groups and two phenoxido bridging groups connecting Zn(II) and Dy(III) ions), other four atoms belonging to the chelating nitrato and ovanillin ligands, and the last one coming to the coordinated water molecule. The structure of 3 shows the central Dy(III) ion surrounded by two L(1)Zn units, so that the Dy(III) and Zn(II) ions are linked by phenoxido/oximato bridging groups. The Dy ion is eight-coordinated by the six O atoms afforded by two L(1) ligands and two O atoms coming from two methanol molecules. Alternating current (AC) dynamic magnetic measurements of 1, 3, and the previously reported dinuclear [LZnClDy(thd)2] (2) complex (where thd = 2,2,6,6-tetramethyl-3,5-heptanedionato ligand) indicate single molecule magnet (SMM) behavior for all these complexes with large thermal energy barriers for the reversal of the magnetization and butterfly-shaped hysteresis loops at 2 K. Ab initio calculations on 1-3 show a pure Ising ground state for all of them, which induces almost completely suppressed quantum tunnelling magnetization (QTM), and thermally assisted quantum tunnelling magnetization (TA-QTM) relaxations via the first excited Kramers doublet, leading to large energy barriers, thus supporting the observation of SMM behavior. The comparison between the experimental and theoretical magnetostructural data for 1-3 has allowed us to draw some conclusions about the influence of ligand substitution around the Dy(III) on the SMM properties. Finally, these SMMs exhibit metal- and ligand-centered dual emissions in the visible region, and, therefore, they can be considered as magnetoluminescent bifunctional molecular materials.

Determination of crystal-field energy levels and temperature dependence of magnetic susceptibility for Dy3+ in [Dy2Pd] heterometallic complex.

PubMed

Karbowiak, Mirosław; Rudowicz, Czesław; Ishida, Takayuki

2013-11-18

This study is the first in a series of experimental and theoretical investigations of the crystal-field (CF) energy levels obtained from optical electronic spectra for selected heterometallic 4f-3d compounds intensively studied for the development of novel single-molecule magnets (SMMs). An intriguing question is why the [{Dy(III)(hfac)3}2Cu(II)(dpk)2] (abbreviated as [Dy2Cu]; Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, Hdpk = di-2-pyridyl ketoxime) has antiferromagnetic coupling, whereas [Gd2Cu] and heavy [Ln2Cu] systems usually show ferromagnetic coupling. As the first step to explain this peculiarity, the recently synthesized complex, [Dy2Pd], is investigated. This complex is isostructural with [Dy2Cu] yet contains the diamagnetic Pd ion instead of the magnetic Cu(II) ion. Experimental energy levels of Dy(3+) ions in the powder [Dy2Pd] sample were determined from the 4.2 K absorption spectra. CF analysis was performed yielding the fitted free ion and CF parameters. The number of freely varied parameters was restricted using the superposition model. The fittings yield very satisfactory agreement between the experimental and the calculated energy levels (rms = 12.0 cm(-1)). The energies and exact composition of the state vector for the ground multiplet (6)H(15/2) of Dy(3+) are determined. These results are used for the simulation of the temperature dependence of the magnetic susceptibility, which enables the theoretical interpretation of the experimentally measured magnetic susceptibility in the range 1.8-300 K for the [Dy2Pd] complex. This study provides background for the subsequent investigation of the magnetic exchange interactions in the pertinent heterometallic complexes.

Single-molecule magnetism in a family of {Co(III)2Dy(III)2} butterfly complexes: effects of ligand replacement on the dynamics of magnetic relaxation.

PubMed

Langley, Stuart K; Ungur, Liviu; Chilton, Nicholas F; Moubaraki, Boujemaa; Chibotaru, Liviu F; Murray, Keith S

2014-05-05

The synthesis and structural characterization of four related heterometallic complexes of formulas [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)4](NO3)2·MeOH·H2O (1a) and [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·H2O (1b), [Dy(III)2Co(III)2(OMe)2(dea)2(O2CPh)4(MeOH)4](NO3)2 (2), [Dy(III)2Co(III)2(OMe)2(mdea)2(O2CPh)4(NO3)2] (3), and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)4](NO3)2·0.5MeOH·H2O (4a) and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·1.5H2O (4b) are reported (teaH3 = triethanolamine, deaH2 = diethanolamine, mdeaH2 = N-methyldiethanolamine, and bdeaH2 = N-n-butyldiethanolamine). Compounds 1 (≡ 1a and 1b) and 4 (≡ 4a and 4b) both display two unique molecules within the same crystal and all compounds display a butterfly type core, with the Dy(III) ions occupying the central body positions and the diamagnetic Co(III) ions the outer wing-tip sites. Compounds 1-4 were investigated via direct current and alternating current magnetic susceptibility measurements, and it was found that each complex displayed single-molecule magnet (SMM) behavior. All four compounds display unique coordination and geometric environments around the Dy(III) ions and it was found that each displays a different anisotropy barrier. Ab initio calculations were performed on 1-4 and these determined the low lying electronic structure of each Dy(III) ion and the magnetic interactions for each cluster. It was found that there was a strong correlation between the calculated energy gap between the ground and first excited states of the single-ion ligand-field split Dy(III) levels and the experimentally observed anisotropy barrier. Furthermore, the transverse g factors found for the Dy(III) ions, defining the tunnelling rates within the ground Kramers doublets, are largest for 1, which agrees with the experimental observation of the shortest relaxation time in the high-temperature domain for this complex. The magnetic exchange between the Dy(III) ions revealed overall antiferromagnetic interactions for each compound, derived from the dominant dipolar exchange resulting in nonmagnetic ground states for 1-4. The diamagnetic ground states coupled with small tunneling gaps resulted in quantum tunneling time scales at zero field of between 0.1 and >1.5 s.

Modulating the single-molecule magnet behaviour in phenoxo-O bridged Dy2 systems via subtle structural variations

NASA Astrophysics Data System (ADS)

Wang, Wen-Min; Zhao, Xiao-Yu; Qiao, Hui; Bai, Li; Han, Hong-Fei; Fang, Ming; Wu, Zhi-Lei; Zou, Ji-Yong

2017-09-01

In search of simple approaches to rationally modulate the single-molecule magnet behaviour in polynuclear lanthanide compound, a new system containing two structurally closely related dinuclear dysprosium complexes, namely [Dy2(hfac)4L2] (1) and [Dy2(hfac)4L‧2] (2) (hfac = hexafluoroacetylacetonate, HL = 2-[4-methylaniline-imino]methyl]-8-hydroxyquinoline and HL' = 2-[(3,4-dimethylaniline)-imino]methyl]-8-hydroxyquinoline), are successfully synthesized and the structure-dependent magnetic properties are investigated. The two Dy2 compounds display only slight variations in the coordination geometries of the center Dy(III) ion but display remarkably different single-molecule magnet behaviors with the anisotropic barriers (ΔE/kB) of 9.91 K for 1 and 20.57 K for 2. The different magnetic relaxation behaviors of the two Dy2 complexes mainly originate from the different chemical environments of the central DyIII ions.

Concentration dependence of luminescence efficiency of Dy3+ ions in strontium zinc phosphate glasses mixed with Pb3 O4.

PubMed

Kumar, Valluri Ravi; Giridhar, G; Veeraiah, N

2017-02-01

In this work we synthesized SrO-ZnO-P 2 O 5 glasses mixed with Pb 3 O 4 (heavy metal oxide) and doped with different amounts of Dy 2 O 3 (0.1 to 1.0 mol%). Subsequently their emission and decay characteristics were investigated as a function of Dy 2 O 3 concentration. The emission spectra exhibited three principal emission bands in the visible region corresponding to 4 F 9 /2  →  6 H 15 /2 (482 nm), 6 H 13 /2 (574 nm) and 6 H 11 /2 (663 nm) transitions. With increase in the concentration of Dy 2 O 3 (upto 0.8 mol%) a considerable increase in the intensity of these bands was observed and, for further increase, quenching of photoluminescence (PL) output was observed. Using emission spectra, various radiative parameters were evaluated and all these parameters were found to increase with increase in Dy 2 O 3 concentration. The Y/B integral emission intensity ratio of Dy 3 + ions evaluated from these spectra exhibited a decreasing trend with increase in the Dy 2 O 3 concentration up to 0.8 mol%. Quenching of luminescence observed in the case of the glasses doped with 1.0 mol% is attributed to clustering of Dy 3 + ions. The quantitative analysis of these results together with infra-red (IR) spectral studies indicated that 0.8 mol% is the optimum concentration of Dy 3 + ions needed to achieve maximum luminescence efficiency. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Spectroscopic studies of Dy3 + ion doped tellurite glasses for solid state lasers and white LEDs

NASA Astrophysics Data System (ADS)

Himamaheswara Rao, V.; Syam Prasad, P.; Mohan Babu, M.; Venkateswara Rao, P.; Satyanarayana, T.; Luís F., Santos; Veeraiah, N.

2018-01-01

Rare earth ion Dy3 +-doped tellurite glasses were synthesised in the system of (75-x)TeO2-15Sb2O3-10WO3-xDy2O3 (TSWD glasses). XRD and FTIR characterizations were used to find the crystalline and structural properties. The intensities of the electronic transitions and the ligand environment around the Dy3 + ion were determined using the Judd-Ofelt (J-O) theory on the absorption spectra of the glasses. The measured luminescence spectra exhibit intense emissions at 574 and 484 nm along with less intense emissions around 662 and 751 nm. Various radiative properties of the 4F9/2 excited level of Dy3 + ion were calculated for the glasses. Decay profiles were measured to find the life times and quantum efficiencies. Yellow to blue intensity ratio (Y/B), CIE chromaticity coordinates and correlated color temperature (CCT) values are calculated using the emission spectra to evaluate the emitted light. The obtained results suggest the utility of the glasses for potential yellow laser and white LED's applications.

Spin canting in a Dy-based single-chain magnet with dominant next-nearest-neighbor antiferromagnetic interactions

NASA Astrophysics Data System (ADS)

Bernot, K.; Luzon, J.; Caneschi, A.; Gatteschi, D.; Sessoli, R.; Bogani, L.; Vindigni, A.; Rettori, A.; Pini, M. G.

2009-04-01

We investigate theoretically and experimentally the static magnetic properties of single crystals of the molecular-based single-chain magnet of formula [Dy(hfac)3NIT(C6H4OPh)]∞ comprising alternating Dy3+ and organic radicals. The magnetic molar susceptibility χM displays a strong angular variation for sample rotations around two directions perpendicular to the chain axis. A peculiar inversion between maxima and minima in the angular dependence of χM occurs on increasing temperature. Using information regarding the monomeric building block as well as an ab initio estimation of the magnetic anisotropy of the Dy3+ ion, this “anisotropy-inversion” phenomenon can be assigned to weak one-dimensional ferromagnetism along the chain axis. This indicates that antiferromagnetic next-nearest-neighbor interactions between Dy3+ ions dominate, despite the large Dy-Dy separation, over the nearest-neighbor interactions between the radicals and the Dy3+ ions. Measurements of the field dependence of the magnetization, both along and perpendicularly to the chain, and of the angular dependence of χM in a strong magnetic field confirm such an interpretation. Transfer-matrix simulations of the experimental measurements are performed using a classical one-dimensional spin model with antiferromagnetic Heisenberg exchange interaction and noncollinear uniaxial single-ion anisotropies favoring a canted antiferromagnetic spin arrangement, with a net magnetic moment along the chain axis. The fine agreement obtained with experimental data provides estimates of the Hamiltonian parameters, essential for further study of the dynamics of rare-earth-based molecular chains.

Calculations of the magnetic entropy change in amorphous through a microscopic anisotropic model: Applications to Dy{sub 70}Zr{sub 30} and DyCo{sub 3.4} alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ranke, P. J. von, E-mail: von.ranke@uol.com.br; Nóbrega, E. P.; Ribeiro, P. O.

We report theoretical investigations on the magnetocaloric effect, described by the magnetic entropy change in rare earth—transition metal amorphous systems. The model includes the local anisotropy on the rare earth ions in Harris-Plischke-Zuckermann assumptions. The transition metals ions are treated in terms of itinerant electron ferromagnetism and the magnetic moment of rare earth ions is coupled to the polarized d-band by a local exchange interaction. The magnetocaloric effect was calculated in DyCo{sub 3.4} system, which presents amorphous sperimagnetic configuration. The calculations predict higher refrigerant capacity in the amorphous DyCo{sub 3.4} than in DyCo{sub 2} crystal, highlighting the importance of amorphousmore » magnetocaloric materials. Our calculation of the magnetocaloric effect in Dy{sub 70}Zr{sub 30}, which presents amorphous asperomagnetic configuration, is in good agreement with the experimental result. Furthermore, magnetic entropy changes associated with crystal-amorphous configurations change are estimated.« less

Difference in the luminescence properties of orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}:Ln (Ln = Tb{sup 3+} and Dy{sup 3+})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tyagi, Adish; Shah, Alpa; Sudarsan, V., E-mail: vsudar@barc.gov.in

2015-04-15

Highlights: • Improved emission colour purity with orthorhombic form of Y{sub 2}GeO{sub 5}. • Non-stationary quenching exists in orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}:Tb. • Ion pair formation and cross relaxation quenching operating for Y{sub 2}GeO{sub 5}:Dy samples. - Abstract: The luminescence properties of Tb{sup 3+} and Dy{sup 3+} doped orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5} are significantly different. Orthorhombic Y{sub 2}GeO{sub 5} doped with Tb{sup 3+} and Dy{sup 3+} ions gives bright green and blue emission upon UV light excitation with CIE coordinates (0.25, 0.46) and (0.25, 0.24), respectively. The monoclinic Y{sub 2}GeO{sub 5} dopedmore » with these ions exhibits light green and yellowish white emissions, respectively. This has been attributed to the differences in crystallographic environments around Y{sup 3+} ions in orthorhombic and monoclinic forms of Y{sub 2}GeO{sub 5}. Quantum yield of emission for orthorhombic Y{sub 2}GeO{sub 5}:Tb (∼29%) is significantly higher than that of the monoclinic Y{sub 2}GeO{sub 5}:Tb (∼14%). Lifetime values corresponding to {sup 4}F{sub 9/2} level of Dy{sup 3+} ions in both monoclinic and orthorhombic forms of Y{sub 2}GeO{sub 5} follow an opposite trend with respect to {sup 5}D{sub 4} level of Tb{sup 3+} ions. This is attributed to difference in the concentration quenching mechanism operating for Tb{sup 3+} and Dy{sup 3+} ions.« less

Broadening emission band of Ba2B2O5: Dy3+ by codoping Ce3+ as sensitizer and its application to white LEDs

NASA Astrophysics Data System (ADS)

Xu, Shuchao; Wang, Zhijun; Li, Panlai; Li, Ting; Bai, Qiongyu; Yang, Zhiping

2018-06-01

In order to achieve broad-band white emitting phosphor, Ce3+/Dy3+ codoped Ba2B2O5 were synthesized by a solid-state method, and the luminescence property and energy transfer were discussed in detail. Dy3+ doped Ba2B2O5 shows white emission, and the two narrow peaks which are assigned to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. When codoped Ce3+ as sensitizer, the broad-band white emission can be obtained by the energy transfer from Ce3+ to Dy3+ ions in Ba2B2O5, and the mechanism is the dipole-dipole interaction. And the CIE coordinates can be tuned from (0.2501, 0.2323) to (0.3422, 0.3799) by increase Dy3+ content. The emission peak blue-shift of Ce3+ ions in Ba2B2O5:Ce3+, Dy3+ was observed from the thermal spectra, and the mechanism was analyzed. A white light emitting diodes (LEDs) can be fabricated Ba2B2O5:Ce3+, Dy3+ with 380 nm chip, and the results show that the phosphor may be a potential application in this field.

Luminomagnetic Eu3+- and Dy3+-doped hydroxyapatite for multimodal imaging.

PubMed

Tesch, Annemarie; Wenisch, Christoph; Herrmann, Karl-Heinz; Reichenbach, Jürgen R; Warncke, Paul; Fischer, Dagmar; Müller, Frank A

2017-12-01

Multimodal imaging has recently attracted much attention due to the advantageous combination of different imaging modalities, like photoluminescence (PL) and magnetic resonance imaging (MRI). In the present study, luminescent and magnetic hydroxyapatites (HAp) were prepared via doping with europium (Eu 3+ ) and dysprosium (Dy 3+ ), respectively. Co-doping of Eu 3+ and Dy 3+ was used to combine the desired physical properties. Both lanthanide ions were successfully incorporated in the HAp crystal lattice, where they preferentially occupied calcium(I) sites. While Eu-doped HAp (Eu:HAp) exhibits dopant concentration dependent persistent PL properties, Dy-doped HAp (Dy:HAp) shows paramagnetic behavior due to the high magnetic moment of Dy 3+ . Co-doped HAp (Eu:Dy:HAp) nanoparticles combine both properties in one single crystal. Remarkably, multimodal co-doped HAp features enhanced PL properties due to an energy transfer from Dy 3+ sensitizer to Eu 3+ activator ions. Eu:Dy:HAp exhibits strong transverse relaxation effects with a maximum transverse relaxivity of 83.3L/(mmol·s). Due to their tunable PL, magnetic properties and cytocompatibility Eu:-, Dy:- and Eu:Dy:HAp represent promising biocompatible ceramic materials for luminescence imaging that simultaneously may serve as a contrast agent for MRI in permanent implants or functional coatings. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectroscopic studies of Dy3+ ion doped tellurite glasses for solid state lasers and white LEDs.

PubMed

V, Himamaheswara Rao; P, Syam Prasad; M, Mohan Babu; P, Venkateswara Rao; T, Satyanarayana; Luís F, Santos; N, Veeraiah

2018-01-05

Rare earth ion Dy 3+ -doped tellurite glasses were synthesised in the system of (75-x)TeO 2 -15Sb 2 O 3 -10WO 3 -xDy 2 O 3 (TSWD glasses). XRD and FTIR characterizations were used to find the crystalline and structural properties. The intensities of the electronic transitions and the ligand environment around the Dy 3+ ion were determined using the Judd-Ofelt (J-O) theory on the absorption spectra of the glasses. The measured luminescence spectra exhibit intense emissions at 574 and 484nm along with less intense emissions around 662 and 751nm. Various radiative properties of the 4 F 9/2 excited level of Dy 3+ ion were calculated for the glasses. Decay profiles were measured to find the life times and quantum efficiencies. Yellow to blue intensity ratio (Y/B), CIE chromaticity coordinates and correlated color temperature (CCT) values are calculated using the emission spectra to evaluate the emitted light. The obtained results suggest the utility of the glasses for potential yellow laser and white LED's applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Strong exchange and magnetic blocking in N₂³⁻-radical-bridged lanthanide complexes.

PubMed

Rinehart, Jeffrey D; Fang, Ming; Evans, William J; Long, Jeffrey R

2011-05-22

Single-molecule magnets approach the ultimate size limit for spin-based devices. These complexes can retain spin information over long periods of time at low temperature, suggesting possible applications in high-density information storage, quantum computing and spintronics. Notably, the success of most such applications hinges upon raising the inherent molecular spin-inversion barrier. Although recent advances have shown the viability of lanthanide-containing complexes in generating large barriers, weak or non-existent magnetic exchange coupling allows fast relaxation pathways that mitigate the full potential of these species. Here, we show that the diffuse spin of an N(2)(3-) radical bridge can lead to exceptionally strong magnetic exchange in dinuclear Ln(III) (Ln = Gd, Dy) complexes. The Gd(III) congener exhibits the strongest magnetic coupling yet observed for that ion, while incorporation of the high-anisotropy Dy(III) ion gives rise to a molecule with a record magnetic blocking temperature of 8.3 K at a sweep rate of 0.08 T s(-1).

Investigations on the spectroscopic properties of Dy3 + ions doped Zinc calcium tellurofluoroborate glasses

NASA Astrophysics Data System (ADS)

Karthikeyan, P.; Arunkumar, S.; Annapoorani, K.; Marimuthu, K.

2018-03-01

A new series of Dy3 + doped (30-x)B2O3 + 30TeO2 + 20CaCO3 + 10ZnO + 10ZnF2 + xDy2O3 (x = 0.01, 0.1, 0.5, 1, 2 and 3 in wt%) Zinc calcium tellurofluoroborate glasses were prepared and their structural, luminescence and excited state dynamics have been studied and reported. The structural properties have been characterized through XRD and FTIR studies to confirm the amorphous nature and to explore the presence of fundamental stretching vibrations. The bonding parameters (δ and β), optical band gap, Urbach's energy, oscillator strengths and Judd-Ofelt (JO) intensity parameters were calculated from the absorption spectra. The JO intensity parameters and the Y/B intensity ratio values have been used to explore the nature of the bonding and asymmetry around the Dy-ligand field environment. The luminescence properties of the present Dy3 + doped glasses have been analyzed through luminescence excited state dynamics and radiative properties such as transition probability (A), stimulated emission cross-section (σPE) branching ratio (β) and radiative lifetime (τR) values. The combination of dominant blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emissions generates white light emission in the CIE chromaticity diagram thus suggests that the present Dy3 + doped glasses are suitable for white light applications. The lifetime of the 4F9/2 excited state is found to decrease with the increase in Dy3 + ion content and the concentration quenching of the Dy3 + ions emission could be ascribed due to the resonant energy transfer and cross-relaxation processes. The non-exponential behavior of the decay curves has been analyzed with Inokuti-Hirayama model and the interaction between the Dy3 + ions is of electric dipole-dipole in nature.

Extraction of Dysprosium Ions with DTPA Functionalized Superparamagnetic Nanoparticles Probed by Energy Dispersive X-ray Fluorescence and TEM/High-Angle Annular Dark Field Imaging.

PubMed

Melo, Fernando Menegatti de; Almeida, Sabrina da Nobrega; Uezu, Noemi Saori; Ramirez, Carlos Alberto Ospina; Santos, Antonio Domingues Dos; Toma, Henrique Eisi

2018-06-01

The extraction of dysprosium (Dy3+) ions from aqueous solution was carried out successfully, using magnetite (Fe3O4) nanoparticles functionalized with diethylenetriaminepentaacetic acid (MagNP@DTPA). The process was monitored by energy dispersive X-ray fluorescence spectroscopy, as a function of concentration, proceeding according to a Langmuir isotherm with an equilibrium constant of 2.57 × 10-3 g(MagNP) L-1 and a saturation limit of 63.2 mgDy/gMagNP. The presence of paramagnetic Dy3+ ions attached to the superparamagnetic nanoparticles led to an overall decrease of magnetization. By imaging the nanoparticles surface using scanning transmission electron microscopy equipped with high resolution elemental analysis, it was possible to probe the binding of the Dy3+ ions to DTPA, and to show their distribution in a region of negative magnetic field gradients. This finding is coherent with the observed decrease of magnetization, associated with the antiferromagnetic coupling between the lanthanide ions and the Fe3O4 core.

Mid-infrared emission and Judd-Ofelt analysis of Dy3+-doped infrared Ga-Sb-S and Ga-Sb-S-PbI2 chalcohalide glasses

NASA Astrophysics Data System (ADS)

Guo, Jixiao; Jiao, Qing; He, Xiaolong; Guo, Hansong; Tong, Jianghao; Zhang, Zhihang; Jiang, Fuchao; Wang, Guoxiang

2018-03-01

Dy3+-doped Ga-Sb-S and Ga-Sb-S-PbI2 chalcohalide glasses were prepared by traditional melt quenching method. The effect of halide PbI2 on the physical and optical properties of Dy3+ ions was investigated. The density and ionic concentration of the host sample increased with the introduction of PbI2 halides, whereas the refractive index at 1.55 μm decreased. The Judd-Ofelt parameters showed that Ω2 increased in PbI2-modified glass, whereas the Ω6 value showed the opposite tendency. Infrared emission spectrum also showed that the intensity increased with PbI2 addition, and considerable enhancement at 2.8 μm was observed in the mid-infrared region. The halide PbI2 promoted the reduction of phonon energy of the host and the improvement of the laser pump efficiency, which led to the construction of optimized infrared glass materials for optical applications.

Enhancing the effective energy barrier of a Dy(III) SMM using a bridged diamagnetic Zn(II) ion.

PubMed

Upadhyay, Apoorva; Singh, Saurabh Kumar; Das, Chinmoy; Mondol, Ranajit; Langley, Stuart K; Murray, Keith S; Rajaraman, Gopalan; Shanmugam, Maheswaran

2014-08-18

Field induced single-molecule-magnet behaviour is observed for both a heterodinuclear [ZnDy(L(-))2](3+) complex (1) and a mononuclear [Dy(HL)2](3+) complex (2), with effective energy barriers of 83 cm(-1) and 16 cm(-1), respectively. Insights into the relaxation mechanism(s) and barrier heights are provided via ab initio and DFT calculations. Our findings reveal an interesting observation that the U(eff) of SMMs can be enhanced by incorporating diamagnetic metal ions.

Fluid-kinetic simulations of the passage of Storm Enhanced Density (SED) plasma flux tubes through the dayside cleft auroral processes region

NASA Astrophysics Data System (ADS)

Zeng, W.; Horwitz, J. L.

2007-12-01

Foster et al. [2002] and others have reported on elevated ionospheric density regions being convected from the subauroral plasmaspheric region toward noon, in association with convection of plasmaspheric tails in the dayside magnetosphere. It has been suggested that these so-called Storm Enhanced Density (SED) regions could serve as ionospheric plasma source populations for cleft ion fountain outflows. To investigate this scenario, we have used our Dynamic Fluid Kinetic (DyFK) model to simulate the entry of a high-density "plasmasphere-like" flux tube entering the cleft region and subjected to an episode of wave-driven transverse ion heating. We find that the O+ ion density at higher altitudes increases and the density at lower altitudes decreases, following this heating episode, indicating increased numbers of O+ ions from the ionospheric source gain sufficient energy to reach higher altitudes after the effects of transverse wave heating. We also find that O+- H+ crossing point in topside ionosphere moves upward as the wave heating continues. Foster, J. C., P. J. Erickson, A. J. Coster, J. Goldstein, and F. J. Rich, Ionospheric signatures of plasmaspheric tails, Geophys. Res. Lett., 29(13), 1623, doi:10.1029/2002GL015067, 2002.

Targeted replacement: systematic studies of dodecanuclear {MLn} coordination clusters (M = Cr, Co; Ln = Dy, Y).

PubMed

Chen, Sihuai; Mereacre, Valeriu; Zhao, Zhiying; Zhang, Wanwan; Zhang, Mengsi; He, Zhangzhen

2018-06-05

Three dodecanuclear 3d-4f coordination clusters, [CrIII6LnIII6(μ3-OH)8(tbdea)6(C6H5COO)16]·2H2O (Ln = Dy (1), Y (2)) and [CoIII6DyIII6(μ3-OH)8(nbdea)6(m-CH3C6H4COO)16]·2H2O·2CH3CN (3), have been synthesized under solvothermal conditions and characterized. Single-crystal X-ray diffraction analysis revealed that all three compounds possess an analogous {MIII6LnIII6} core (M = Cr, Co; Ln = Dy, Y) and dc magnetic susceptibility studies indicated that the magnetic exchange couplings between DyIII ions are dominant antiferromagnetic, while the CrIII-DyIII interactions are weakly ferromagnetic. Furthermore, the ac magnetic susceptibility measurements showed that both CrIII6DyIII6 compound 1 and CoIIi6DyIII6 compound 3 containing highly anisotropic DyIII ions displayed single-molecule magnetic (SMM) behavior with the energy barrier Ueff increasing from 12.8 K (for 1) to 20.8 K (for 3), indicating that weak 3d-4f exchange couplings enhance the QTM and reduce the energy barrier.

Exploration of dysprosium: the most critical element for Japan

NASA Astrophysics Data System (ADS)

Watanabe, Y.

2012-04-01

Dysprosium (Dy), one of the heavy rare earth elements, is used mainly as an additive for NdFeB permanent magnets which are installed in various modern industrial products such as voice coil motors in computers, factory automation machinery, hybrid and electric vehicles, home electronics, and wind turbine, to improve heat resistance of the magnets. Dy has been produced about 2,000t per year from the ores from ion adsorption type deposits in southern China. However, the produced amount of Dy was significantly reduced in 2011 in China due to reservation of heavy rare earth resources and protection of natural environment, resulting in soaring of Dy price in the world. In order to respond the increasing demand of Dy, unconventional supply sources are inevitably developed, in addition to heavy rare earth enriched ion adsorption type deposits outside China. Heavy rare earth elements including Dy are dominantly hosted in xenotime, fergusonite, zircon, eudialyte, keiviite, kainosite, iimoriite, etc. Concentration of xenotime is found in placer deposits in Malaysia and India, hydrothermal deposits associated with unconformity-type uranium mineralization (Athabasca basin in Canada, Western Australia), iron-oxide fluorite mineralization (South Africa) and Sn-bearing alkaline granite (Brazil). Zircon and fergusontie concentration is found as igneous and hydrothermal products in peralkaline syenite, alkaline granite and pegmatite (e.g., Nechalacho in Canada). Eudialyte concentration is found in some peralkaline syenite bodies in Greenland, Canada, Sweden and Russia. Among these sources, large Dy resources are estimated in the deposits hosted in peralkaline rocks (Nechalacho: 79,000t, Kvanefjeld: 49,000t, Norra Karr: 15,700t, etc.) compared to the present demand of Dy. Thus, Dy will be supplied from the deposits associated with peralkaline and alkaline deposits in future instead of ion adsorption type deposits in southern China.

Effect of rare-earth ion size on local electron structure in RBa 2Cu 3O 7- δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors: A positron study

NASA Astrophysics Data System (ADS)

Chen, Zhenping; Zhang, Jincang; Su, Yuling; Xue, Yuncai; Cao, Shixun

2006-02-01

The effects of rare-earth ionic size on the local electron structure, lattice parameters and superconductivity have been investigated by positron annihilation technique (PAT) and related experiments for RBa 2Cu 3O 7- δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors. The local electron density ne is evaluated as a function of the rare-earth radius. The results show that both the bulk-lifetime τB and the defect lifetime τ2 increase with increasing rare-earth ionic radius, while the local electron density ne decrease with increasing rare-earth ionic radius. These results prove that the changes of ne, the degree of orthorhombic distortion and the coupling between the Cu-O chains and the CuO 2 planes all have an effect on the superconductivity of RBa 2Cu 3O 7- δ systems.

Comparisons of lanthanide/actinide +2 ions in a tris(aryloxide)arene coordination environment† †Electronic supplementary information (ESI) available: Additional computational details, spectroscopic information, crystallographic data collection, structure solution, and refinement (PDF), X-ray diffraction details of compounds 1-Ln (Ln = Nd, Gd, Dy, and Er), 2-Nd, 2-Ln/3-Ln (Ln = Gd, Dy, Er), 2-Dy/4-Dy, and 5-Dy/6-Dy. CCDC (CIF, 1538987–1538995 and 1566075 for 2-Dy/3-Dy), and DFT-optimized structural coordinates for 2-Nd and 2-Gd. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc02337e Click here for additional data file. Click here for additional data file. Click here for additional data file.

PubMed Central

Fieser, Megan E.; Palumbo, Chad T.; La Pierre, Henry S.; Halter, Dominik P.; Voora, Vamsee K.; Ziller, Joseph W.

2017-01-01

A new series of Ln3+ and Ln2+ complexes has been synthesized using the tris(aryloxide)arene ligand system, ((Ad,MeArO)3mes)3–, recently used to isolate a complex of U2+. The triphenol precursor, (Ad,MeArOH)3mes, reacts with the Ln3+ amides, Ln(NR2)3 (R = SiMe3), to form a series of [((Ad,MeArO)3mes)Ln] complexes, 1-Ln. Crystallographic characterization was achieved for Ln = Nd, Gd, Dy, and Er. The complexes 1-Ln can be reduced with potassium graphite in the presence of 2.2.2-cryptand (crypt) to form highly absorbing solutions with properties consistent with Ln2+ complexes, [K(crypt)][((Ad,MeArO)3mes)Ln], 2-Ln. The synthesis of the Nd2+ complex [K(crypt)][((Ad,MeArO)3mes)Nd], 2-Nd, was unambiguously confirmed by X-ray crystallography. In the case of the other lanthanides, crystals were found to contain mixtures of 2-Ln co-crystallized with either a Ln3+ hydride complex, [K(crypt)][((Ad,MeArO)3mes)LnH], 3-Ln, for Ln = Gd, Dy, and Er, or a hydroxide complex, [K(crypt)][((Ad,MeArO)3mes)Ln(OH)], 4-Ln, for Ln = Dy. A Dy2+ complex with 18-crown-6 as the potassium chelator, [K(18-crown-6)(THF)2][((Ad,MeArO)3mes)Dy], 5-Dy, was isolated as a co-crystallized mixture with the Dy3+ hydride complex, [K(18-crown-6)(THF)2][((Ad,MeArO)3mes)DyH], 6-Dy. Structural comparisons of 1-Ln and 2-Ln are presented with respect to their uranium analogs and correlated with density functional theory calculations on their electronic structures. PMID:29163894

Investigation of luminescence and laser transition of Dy3+ ion in P2O5sbnd PbOsbnd Bi2O3sbnd R2O3 (R = Al, Ga, In) glasses

NASA Astrophysics Data System (ADS)

Ram, G. Chinna; Narendrudu, T.; Suresh, S.; Kumar, A. Suneel; Rao, M. V. Sambasiva; Kumar, V. Ravi; Rao, D. Krishna

2017-04-01

P2O5sbnd PbOsbnd Bi2O3sbnd R2O3 (R = Al, Ga, In) glasses doped with Dy2O3 were prepared by melt quenching technique. The prepared glasses were characterized by XRD, optical absorption, FTIR, luminescence studies. Judd-Ofelt parameters have been evaluated for three glass systems from optical absorption spectra and in turn radiative parameters for excited luminescent levels of Dy3+ ion are also calculated. Emission cross section and branching ratio values are observed to high for 6H13/2 level for Dy3+ ion. The yellow to blue intensity ratios and CIE chromaticity coordinates were calculated. Decay curves exhibit non exponential behavior. Quantum efficiency of prepared glasses was measured by using radiative and calculated life times. IR studies, J-O parameters and Y/B ratio values indicate that more asymmetry around Dy3+ ions in Ga2O3 mixed glass was observed. Chromaticity coordinates lie near ideal white light region. These coordinates and CCT values have revealed that all the prepared glasses emit quality white light especially the glasses mixed with Ga2O3 are suitable for development of white LEDs.

Preparation and Luminescence Properties of Ca9NaZn(PO4)7:Dy3+ Single-Phase White Light-Emitting Phosphor

NASA Astrophysics Data System (ADS)

Zhu, Daoyun; Liao, Min; Mu, Zhongfei; Wu, Fugen

2018-05-01

Dy3+-doped Ca9NaZn(PO4)7 has been synthesized by high-temperature solid-state reaction. X-ray diffraction analysis revealed that the obtained phosphors existed as single phase. Doping with Dy3+ at low concentration had no obvious effect on the crystal structure of the host. Dy3+-doped samples showed strong emission at approximately 480 nm and 571 nm under excitation at 350 nm. The blue and yellow emissions showed almost the peak intensity. The combination of blue and yellow light formed white light. The color coordinates (0.323, 0.372) of the composite light are located in the white light region. The optimum doping concentration of Dy3+ ions was experimentally determined to be 10 mol.%. The concentration quenching mechanism was ascertained to be electric dipole-dipole interaction among Dy3+ ions. The obtained phosphors exhibited good thermal stability. These results indicate potential applications as single-phase white light-emitting phosphors.

Tuning the Origin of Magnetic Relaxation by Substituting the 3d or Rare-Earth Ions into Three Isostructural Cyano-Bridged 3d-4f Heterodinuclear Compounds.

PubMed

Zhang, Yan; Guo, Zhen; Xie, Shuang; Li, Hui-Li; Zhu, Wen-Hua; Liu, Li; Dong, Xun-Qing; He, Wei-Xun; Ren, Jin-Chao; Liu, Ling-Zhi; Powell, Annie K

2015-11-02

Three isostructural cyano-bridged 3d-4f compounds, [YFe(CN)6(hep)2(H2O)4] (1), [DyFe(CN)6(hep)2(H2O)4] (2), and [DyCo(CN)6(hep)2(H2O)4] (3), were successfully assembled by site-targeted substitution of the 3d or rare-earth ions. All compounds have been structurally characterized to display slightly distorted pentagonal-bipyramidal local coordination geometry around the rare-earth ions. Magnetic analyses revealed negligible magnetic coupling in compound 1, antiferromagnetic intradimer interaction in 2, and weak ferromagnetic coupling through dipolar-dipolar interaction in 3. Under an applied direct-current (dc) field, 1 (Hdc = 2.5 kOe, τ0 = 1.3 × 10(-7) s, and Ueff/kB = 23 K) and 3 (Hdc = 2.0 kOe, τ0 = 7.1 × 10(-11) s, and Ueff/kB = 63 K) respectively indicated magnetic relaxation behavior based on a single [Fe(III)]LS ion and a Dy(III) ion; nevertheless, 2 (Hdc = 2.0 kOe, τ0 = 9.7 × 10(-8) s, and Ueff/kB = 23 K) appeared to be a single-molecule magnet based on a cyano-bridged DyFe dimer. Compound 1, which can be regarded as a single-ion magnet of the [Fe(III)]LS ion linked to a diamagnetic Y(III) ion in a cyano-bridged heterodimer, represents one of the rarely investigated examples based on a single Fe(III) ion explored in magnetic relaxation behavior. It demonstrated that the introduction of intradimer magnetic interaction of 2 through a cyano bridge between Dy(III) and [Fe(III)]LS ions negatively affects the energy barrier and χ″(T) peak temperature compared to 3.

Corrosion study of single crystal Ni-Mn-Ga alloy and Tb0.27Dy0.73Fe1.95 alloy for the design of new medical microdevices.

PubMed

Pouponneau, Pierre; Savadogo, Oumarou; Napporn, Teko; Yahia, L'Hocine; Martel, Sylvain

2011-02-01

Once placed in a magnetic field, smart magnetic materials (SMM) change their shape, which could be use for the development of smaller minimally invasive surgery devices activated by magnetic field. However, the potential degradation and release of cytotoxic ions by SMM corrosion has to be determined. This paper evaluates the corrosion resistance of two SMM: a single crystal Ni-Mn-Ga alloy and Tb(0.27)Dy(0.73)Fe(1.95) alloy. Ni-Mn-Ga alloy displayed a corrosion potential (E (corr)) of -0.58 V/SCE and a corrosion current density (i (corr)) of 0.43 μA/cm(2). During the corrosion assay, Ni-Mn-Ga sample surface was partially protected; local pits were formed on 20% of the surface and nickel ions were mainly found in the electrolyte. Tb(0.27)Dy(0.73)Fe(1.95) alloy exhibited poor corrosion properties such as E (corr) of -0.87 V/SCE and i (corr) of 5.90 μA/cm(2). During the corrosion test, this alloy was continuously degraded, its surface was impaired by pits and cracks extensively and a high amount of iron ions was measured in the electrolyte. These alloys exhibited low corrosion parameters and a selective degradation in the electrolyte. They could only be used for medical applications if they are coated with high strain biocompatible materials or embedded in composites to prevent direct contact with physiological fluids.

Synthesis, characterization and optical properties of NH{sub 4}Dy(PO{sub 3}){sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chemingui, S.; Ferhi, M., E-mail: ferhi.mounir@gmail.com; Horchani-Naifer, K.

2014-09-15

Polycrystalline powders of NH{sub 4}Dy(PO{sub 3}){sub 4} polyphosphate have been grown by the flux method. This compound was found to be isotopic with NH{sub 4}Ce(PO{sub 3}){sub 4} and RbHo(PO{sub 3}){sub 4}. It crystallizes in the monoclinic space group P2{sub 1/n} with unit cell parameters a=10.474(6) Å, b=9.011(4) Å, c=10.947(7) Å and β=106.64(3)°. The title compound has been transformed to triphosphate Dy(PO{sub 3}){sub 3} after calcination at 800 °C. Powder X-ray diffraction, infrared and Raman spectroscopies and the differential thermal analysis have been used to identify these materials. The spectroscopic properties have been investigated through absorption, excitation, emission spectra and decaymore » curves of Dy{sup 3+} ion in both compounds at room temperature. The emission spectra show the characteristic emission bands of Dy{sup 3+} in the two compounds, before and after calcination. The integrated emission intensity ratios of the yellow to blue (I{sub Y}/I{sub B}) transitions and the chromaticity properties have been determined from emission spectra. The decay curves are found to be double-exponential. The non-exponential behavior of the decay rates was related to the resonant energy transfer as well as cross-relaxation between the donor and acceptor Dy{sup 3+} ions. The determined properties have been discussed as function of crystal structure of both compounds. They reveal that NH{sub 4}Dy(PO{sub 3}){sub 4} is promising for white light generation but Dy(PO{sub 3}){sub 3} is potential candidates in field emission display (FED) and plasma display panel (PDP) devices. - Graphical abstract: The CIE color coordinate diagrams showing the chromatic coordinates of Dy{sup 3+} luminescence in NH{sub 4}Dy(PO{sub 3}){sub 4} and Dy(PO{sub 3}){sub 3}. - Highlights: • The polycrystalline powders of NH{sub 4}Dy(PO{sub 3}){sub 4} and Dy(PO{sub 3}){sub 3} are synthesized. • The obtained powders are characterized. • The spectroscopic properties of Dy{sup 3+} ion are investigated. • Results are discussed as function of crystal structure and chemical composition. • The usefulness of NH{sub 4}Dy(PO{sub 3}){sub 4} and Dy(PO{sub 3}){sub 3} in optical devices is revealed.« less

Photoluminescence properties and energy transfer in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8) phosphors for potential application in ultraviolet white light-emitting diodes.

PubMed

Yu, Hong; Zi, Wenwen; Lan, Shi; Gan, Shucai; Zou, Haifeng; Xu, Xuechun; Hong, Guangyan

2013-01-01

Sr(3) MgSi(2) O(8) :Ce(3+) , Dy(3+) phosphors were prepared by a solid-state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce(3+) ions (403 nm) but also as a band due to Dy(3+) ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8)phosphors, and the co-doping of Ce(3+) could enhance the emission intensity of Dy(3+) to a certain extent by transferring its energy to Dy(3+) . The Ce(3+) /Dy(3+) energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94 MgSi2 O8 :0.01Ce(3+) , 0.05Dy(3+) phosphors, the fluorescence lifetime of Dy(3+) (from 3.35 to 27.59 ns) is increased whereas that of Ce(3+) is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce(3+) to Dy(3+) energy transfer. The varied emitted color of Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) phosphors from blue to white were achieved by altering the concentration ratio of Ce(3+) and Dy(3+) . These results indicate Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) may be as a candidate phosphor for white light-emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd.

Exploring the Influence of Diamagnetic Ions on the Mechanism of Magnetization Relaxation in {CoIII2LnIII2} (Ln = Dy, Tb, Ho) "Butterfly" Complexes.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Murray, Keith S; Rajaraman, Gopalan

2017-03-06

The synthesis and magnetic and theoretical studies of three isostructural heterometallic [Co III 2 Ln III 2 (μ 3 -OH) 2 (o-tol) 4 (mdea) 2 (NO 3 ) 2 ] (Ln = Dy (1), Tb (2), Ho (3)) "butterfly" complexes are reported (o-tol = o-toluate, (mdea) 2- = doubly deprotonated N-methyldiethanolamine). The Co III ions are diamagnetic in these complexes. Analysis of the dc magnetic susceptibility measurements reveal antiferromagnetic exchange coupling between the two Ln III ions for all three complexes. ac magnetic susceptibility measurements reveal single-molecule magnet (SMM) behavior for complex 1, in the absence of an external magnetic field, with an anisotropy barrier U eff of 81.2 cm -1 , while complexes 2 and 3 exhibit field induced SMM behavior, with a U eff value of 34.2 cm -1 for 2. The barrier height for 3 could not be quantified. To understand the experimental observations, we performed DFT and ab initio CASSCF+RASSI-SO calculations to probe the single-ion properties and the nature and magnitude of the Ln III -Ln III magnetic coupling and to develop an understanding of the role the diamagnetic Co III ion plays in the magnetization relaxation. The calculations were able to rationalize the experimental relaxation data for all complexes and strongly suggest that the Co III ion is integral to the observation of SMM behavior in these systems. Thus, we explored further the effect that the diamagnetic Co III ions have on the magnetization blocking of 1. We did this by modeling a dinuclear {Dy III 2 } complex (1a), with the removal of the diamagnetic ions, and three complexes of the types {K I 2 Dy III 2 } (1b), {Zn II 2 Dy III 2 } (1c), and {Ti IV 2 Dy III 2 } (1d), each containing a different diamagnetic ion. We found that the presence of the diamagnetic ions results in larger negative charges on the bridging hydroxides (1b > 1c > 1 > 1d), in comparison to 1a (no diamagnetic ion), which reduces quantum tunneling of magnetization effects, allowing for more desirable SMM characteristics. The results indicate very strong dependence of diamagnetic ions in the magnetization blocking and the magnitude of the energy barriers. Here we propose a synthetic strategy to enhance the energy barrier in lanthanide-based SMMs by incorporating s- and d-block diamagnetic ions. The presented strategy is likely to have implications beyond the single-molecule magnets studied here.

Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide.

PubMed

Halimah, M K; Ami Hazlin, M N; Muhammad, F D

2018-04-15

A series of glass samples with chemical formula {[(TeO 2 ) 0.7 (B 2 O 3 ) 0.3 ] 0.7 (ZnO) 0.3 } 1-x (Dy 2 O 3 ) x where x=0.01, 0.02, 0.03, 0.04 and 0.05M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO 4 , BO 3, TeO 4 and TeO 3 vibrational groups. The density of the glass systems is increased with the addition of Dy 2 O 3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy 2 O 3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Copyright © 2017 Elsevier B.V. All rights reserved.

Relieving geometrical frustration through doping in the Dy1-x Ca x BaCo4O7 swedenborgites.

PubMed

Nath Panja, Soumendra; Kumar, Jitender; Dengre, Shanu; Nair, Sunil

2016-12-07

The geometrically frustrated antiferromagnet DyBaCo 4 O 7 is investigated through a combination of x-ray diffraction, magnetization and dielectric measurements. Systematic doping in the series Dy 1-x Ca x BaCo 4 O 7 causes a lifting of the geometrical frustration resulting in a structural transition from a trigonal P31c to an orthorhombic Pbn2 1 symmetry at x  =  0.4. This structural transition can also be accessed as a function of temperature, and all our orthorhombic specimens exhibit this transition at elevated temperatures. The temperature at which this structural transition occurs is observed to scale linearly with the mean ionic radius of the R site ion. However, CaBaCo 4 O 7 which has an equal number of Co 2+  and Co 3+ ions clearly violates this quasilinear relationship, indicating that charge ordering could also play a critical role in stabilizing the orthorhombic distortion in this system. Using thermoremanent magnetization measurements to circumvent the problem of the large paramagnetic background arising from Dy 3+ ions, we chart out the phase diagram of the Dy 1-x Ca x BaCo 4 O 7 series.

Spectroscopy and energy transfer in lead borate glasses doubly doped with Tm3+ and Dy3+ ions

NASA Astrophysics Data System (ADS)

Górny, Agata; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

2018-03-01

Lead borate glasses singly and doubly doped with Tm3+ and Dy3+ were prepared by traditional melt-quenching technique. The emission spectra of rare earths in studied glass systems were registered under different excitation wavelengths. The observed emission bands are located in the visible spectral region. They correspond to 1D2 → 3F4 (blue) and 1G4 → 3H6 (blue) transitions of Tm3+ as well as 4F9/2 → 6H15/2 (blue), 4F9/2 → 6H13/2 (yellow) and 4F9/2 → 6H11/2 (red) transitions of Dy3+. Moreover, the energy transfer process from Tm3+ to Dy3+ was observed. The luminescence bands originating to characteristic transitions of thulium and dysprosium ions are present on emission spectra under direct excitation of Tm3+. Luminescence lifetimes for the excited states of Tm3+ and Dy3+ ions in lead borate glass were also determined based on decay measurements. The luminescence intensities and lifetimes depend significantly on the relative concentrations of the optically active dopants.

Magnetic structure of DyFe3

NASA Astrophysics Data System (ADS)

Jin, Long-huan; W, J. James; J, Rhyne; R, Lemaire

1985-06-01

Powder neutron diffraction measurements have been carried out on the intermetallic compound DyFe3 at 4 and 295K. The magnetic structure of the compound at 4 and 295K are noncollinear but coplanar in the a-c plane, and the moments of the Dy and Fe ions lie closer to the basal plane.

Lanthanide Triangles Supported by Radical Bridging Ligands.

PubMed

Dolinar, Brian S; Alexandropoulos, Dimitris I; Vignesh, Kuduva R; James, Tia'Asia; Dunbar, Kim R

2018-01-24

The first examples of metallacycles containing rare earth ions bridged by radicals are reported. The molecular triangles [Ln 3 (hfac) 6 (bptz •- ) 3 ] (Ln = Dy III , Y III ; hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) consist of lanthanide ions bridged by bptz radical anion (bptz •- ) ligands. Magnetic susceptibility measurements and CASSCF calculations performed on [Dy 3 (hfac) 6 (bptz •- ) 3 ] reveal the presence of antiferromagnetic coupling between the Dy III centers and the bptz •- ligands, with J = -6.62 cm -1 .

Dopant occupancy and UV-VIS-NIR spectroscopy of Mg (0, 4, 5 and 6 mol.%):Dy:LiNbO3 crystal

NASA Astrophysics Data System (ADS)

Dai, Li; Liu, Chunrui; Han, Xianbo; Wang, Luping; Tan, Chao; Yan, Zhehua; Xu, Yuheng

2017-09-01

A series of Dy:LiNbO3 crystals with x mol.% Mg2+ ions (x =0, 4, 5 and 6 mol.%) were grown by the Czochralski method. The effective segregation coefficient of Mg2+ and Dy3+ ions was studied by the inductively coupled plasma-atomic emission spectrometry (ICP-AES). UV-VIS-NIR absorption spectra and Judd-Ofelt theory were used to investigate their spectroscopic properties. J-O intensity parameters (Ω2 = 7.53 × 10-20cm2, Ω4 = 6.98 × 10-20cm2, and Ω6 = 3.09 × 10-20cm2) and larger spectroscopic quality factor (X = 2.26) for Mg:(6 mol.%)Dy:LiNbO3 crystals were obtained.

Spectroscopic and energy transfer behavior of Dy3+ ions in B2O3sbnd TeO2sbnd PbOsbnd PbF2sbnd Bi2O3sbnd CdO glasses for laser and WLED applications

NASA Astrophysics Data System (ADS)

Arunkumar, S.; Venkataiah, G.; Marimuthu, K.

2015-02-01

A new series of white light emitting Dy3+ doped Lead tellurofluoroborate glasses have been prepared and their spectroscopic and energy transfer behavior were explored through analyzing XRD, FTIR, Raman, SEM, EDAX, optical absorption, photoluminescence and lifetime measurements. The fundamental stretching of the various borate and tellurite networks were identified using FTIR and Raman spectral analysis. The bonding parameter studies reveal the ionic nature of the Dysbnd O bond in the present glasses. The Judd-Ofelt (JO) intensity parameters determined from the absorption spectra have been used to investigate the nature of bonding and symmetry orientation of the Dy-ligand field environment. The luminescence intensity increases with increasing Dy3+ ion concentration up to 0.5 wt%, beyond that luminescence quenching is observed. The JO parameters have been used to determine the transition probability (A), stimulated emission cross-section (σPE), radiative lifetime (τR) and branching ratios (βR) for the different emission transitions from the 4F9/2 excited level. The higher σPE and βR values of the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions suggest the possible laser action in the visible region. The Y/B ratio, CIE chromaticity color coordinates (x, y) and Color correlated temperature (CCT) were also estimated from the luminescence spectra for different concentration as well as pumping wavelengths. The x, y chromaticity color coordinates fall within the white light region and the white light can be tuned by varying the excitation wavelengths. The lifetime of the 4F9/2 excited state were measured and is found to decrease with increasing Dy3+ ion content. The non-exponential behavior is predominant in higher Dy3+ ion content glasses and is due to the efficient energy transfer between Dy3+sbnd Dy3+ ions. The decay curves were fitted to the Inokuti-Hirayama (IH) model to understand the nature of energy transfer. Among the prepared glasses, 0.5DPTFB glass possesses higher A,βR, σPE, η values and is suggested for lasers and WLED applications.

Selective recognition of dysprosium(III) ions by enhanced chemiluminescence CdSe quantum dots

NASA Astrophysics Data System (ADS)

Hosseini, Morteza; Ganjali, Mohammad R.; Vaezi, Zahra; Faridbod, Farnoush; Arabsorkhi, Batool; Sheikhha, Mohammad H.

2014-03-01

The intensity of emitted light from CdSe quantum dots (QDs)-H2O2 is described as a novel chemiluminescence (CL) reaction for determination of dysprosium. This reaction is based on the catalytic effect of Dy3+ ions, causing a significant increase in the light emission, as a result of the reaction of quantum dots (QDs) with hydrogen peroxide. In the optimum conditions, this method was satisfactorily described by linear calibration curve in the range of 8.3 × 10-7-5.0 × 10-6 M, the detection limit of 6.0 × 10-8 M, and the relative standard deviation for five determinations of 2.5 × 10-6 M Dy3+ 3.2%. The main experimental advantage of the proposed method is its selective to Dy3+ ions compared with common coexisting cations, therefore, it was successfully applied for the determination of dysprosium ions in water samples.

Visible luminescence of dysprosium ions in oxyhalide lead borate glasses.

PubMed

Pisarska, Joanna; Żur, Lidia; Pisarski, Wojciech A

2011-08-15

Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions. Copyright © 2010 Elsevier B.V. All rights reserved.

Tunable color and energy transfer in single-phase white-emitting Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+},Dy{sup 3+} phosphors for UV white light-emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, Bo; Song, Yanhua; Sheng, Ye

Ce{sup 3+} and/or Dy{sup 3+} activated Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68} phosphors were synthesized by high temperature solid state reaction and their luminescent properties were studied. There are two emissions peaking at 407 and 577 nm in the emission spectra of Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+}, Dy{sup 3+}, which are due to the transitions of Ce{sup 3+} and Dy{sup 3+} ions, respectively. More importantly, the effective energy transfer from Ce{sup 3+} to Dy{sup 3+} ions has been confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and mechanism of energy transfermore » were investigated and it was demonstrated to be resonant type via dipole–dipole reaction. Under the excitation of 345 nm, the emitting color can change from blue to white by adjusting the relative doping concentration of Ce{sup 3+} and Dy{sup 3+} ions, indicating that the phosphors Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+}, Dy{sup 3+} are promising single-phase white-emitting phosphors for application in pc-white LEDs. - Highlights: • The Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+},Dy{sup 3+} are novel luminescent materials that have not been reported before. • The crystal structure of Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68} and energy transfer from Ce{sup 3+} to Dy{sup 3+} were investigated. • The emission color of Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+},Dy{sup 3+} can be adjusted from blue to white. • The phosphors have great application value in WLEDs as a kind of blue-to-white emitting phosphors.« less

Large Hexadecametallic {Mn(III) -Ln(III) } Wheels: Synthesis, Structural, Magnetic, and Theoretical Characterization.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S; Rajaraman, Gopalan

2015-11-09

The synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {Mn(III) 8 Ln(III) 8 } (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH2 , in the presence of ortho-toluic or benzoic acid are reported. From the seven wheels studied the {Mn8 Dy8 } and {Mn8 Y8 } analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn8 Y8 } complex due to weak ferromagnetic Mn(III) -Mn(III) interactions. Ab initio CASSCF+RASSI-SO calculations on the {Mn8 Dy8 } wheel estimated the Mn(III) -Dy(III) exchange interaction as -0.1 cm(-1) . This weak exchange along with unfavorable single-ion anisotropy of Dy(III) /Mn(III) ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g-anisotropy of the Dy(III) ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn8 Ln8 } clusters reported here are the largest heterometallic Mn(III) Ln(III) wheels and the largest {3d-4f} wheels to exhibit SMM behavior reported to date. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luminescence properties of Na3SrB5O10:Dy3+ plate-like microstructures for solid state lighting applications

NASA Astrophysics Data System (ADS)

Dillip, G. R.; Dhoble, S. J.; Raju, B. Deva Prasad

2013-10-01

A series of novel plate-like microstructure Na3SrB5O10 doped with various Dy3+ ions concentration have been synthesized for the first time by solid-state reaction (SSR) method. X-ray diffraction (XRD) results demonstrated that the prepared Na3SrB5O10:Dy3+ phosphors are single-phase pentaborates with triclinic structure. The plate-like morphology of the phosphor is examined by Field emission scanning electron microscopy (FE-SEM). The existence of both BO3 and BO4 groups in Na3SrB5O10:Dy3+ phosphors are identified by Fourier transform infrared (FT-IR) spectroscopy. Upon excitation at 385 nm, the PL spectra mainly comprising of two broad bands: one is a blue light emission (˜486 nm) and another is a yellow light emission (˜581 nm), originating from the transitions of 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 in 4f9 configuration of Dy3+ ions, respectively and the optimized dopant concentration is determined to be 3 at.%. Interestingly, the yellow-to-blue (Y/B) emission integrated intensity ratio is close to unity (0.99) for 3 at.% Dy3+ ions, suggesting that the phosphors are favor for white illumination. Moreover, the calculated Commission International de l'Eclairage (CIE) chromaticity coordinates of Na3SrB5O10:Dy3+ phosphors shows the values lie in white light region and the estimated CCT values are located in cool/day white light region.

Magnetic Nature of the CrIII–LnIII Interactions in [CrIII 2LnIII 3] Clusters with Slow Magnetic Relaxation

PubMed Central

Xiang, Shuo; Wang, Jin; Bao, Dong‐Xu; Li, Yun‐Chun

2018-01-01

Abstract Two 3d‐4f hetero‐metal pentanuclear complexes with the formula {[CrIII 2LnIII 3L10(OH)6(H2O)2]Et3NH} [Ln=Tb (1), Dy (2); HL=pivalic acid, Et3N=triethylamine] have been produced. The metal core of each cluster is made up of a trigonal bipyramid with three LnIII ions (plane) and two CrIII ions (above and below) held together by six μ 3‐OH bridges. Also reported with this series is the diamagnetic CrIII–YIII analogue (3). Fortunately, we successfully prepared AlIII–LnIII analogues with the formula {[AlIII 2LnIII 3L10(OH)6(H2O)2]Et3NH⋅H2O} [Ln=Tb (4), Dy (5)], containing diamagnetic AlIII ions, which can be used to evaluate the CrIII–LnIII magnetic nature through a diamagnetic substitution method. Subsequently, static (dc) magnetic susceptibility studies reveal dominant ferromagnetic interactions between CrIII and LnIII ions. Dynamic (ac) magnetic susceptibility studies show frequency‐dependent out‐of‐phase (χ′′) signals for [CrIII 2TbIII 3] (1), [CrIII 2DyIII 3] (2), and [AlIII 2DyIII 3] (5), which are derived from the single‐ion behavior of LnIII ions and/or the CrIII–LnIII ferromagnetic interactions. PMID:29435404

Magnetic Nature of the CrIII-LnIII Interactions in [CrIII2LnIII3] Clusters with Slow Magnetic Relaxation.

PubMed

Zhao, Xiao-Qing; Xiang, Shuo; Wang, Jin; Bao, Dong-Xu; Li, Yun-Chun

2018-02-01

Two 3 d -4 f hetero-metal pentanuclear complexes with the formula {[Cr III 2 Ln III 3 L 10 (OH) 6 (H 2 O) 2 ]Et 3 NH} [Ln=Tb ( 1 ), Dy ( 2 ); HL=pivalic acid, Et 3 N=triethylamine] have been produced. The metal core of each cluster is made up of a trigonal bipyramid with three Ln III ions (plane) and two Cr III ions (above and below) held together by six μ 3 -OH bridges. Also reported with this series is the diamagnetic Cr III -Y III analogue ( 3 ). Fortunately, we successfully prepared Al III -Ln III analogues with the formula {[Al III 2 Ln III 3 L 10 (OH) 6 (H 2 O) 2 ]Et 3 NH⋅H 2 O} [Ln=Tb ( 4 ), Dy ( 5 )], containing diamagnetic Al III ions, which can be used to evaluate the Cr III -Ln III magnetic nature through a diamagnetic substitution method. Subsequently, static (dc) magnetic susceptibility studies reveal dominant ferromagnetic interactions between Cr III and Ln III ions. Dynamic (ac) magnetic susceptibility studies show frequency-dependent out-of-phase ( χ '') signals for [Cr III 2 Tb III 3 ] ( 1 ), [Cr III 2 Dy III 3 ] ( 2 ), and [Al III 2 Dy III 3 ] ( 5 ), which are derived from the single-ion behavior of Ln III ions and/or the Cr III -Ln III ferromagnetic interactions.

Tunable photoluminescence and magnetic properties of Dy(3+) and Eu(3+) doped GdVO4 multifunctional phosphors.

PubMed

Liu, Yanxia; Liu, Guixia; Dong, Xiangting; Wang, Jinxian; Yu, Wensheng

2015-10-28

A series of Dy(3+) or/and Eu(3+) doped GdVO4 phosphors were successfully prepared by a simple hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrometry (EDS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The results indicate that the as-prepared samples are pure tetragonal phase GdVO4, taking on nanoparticles with an average size of 45 nm. Under ultraviolet (UV) light excitation, the individual Dy(3+) or Eu(3+) ion activated GdVO4 phosphors exhibit excellent emission properties in their respective regions. The mechanism of energy transfer from the VO4(3-) group and the charge transfer band (CTB) to Dy(3+) and Eu(3+) ions is proposed. Color-tunable emissions in GdVO4:Dy(3+),Eu(3+) phosphors are realized through adopting different excitation wavelengths or adjusting the appropriate concentration of Dy(3+) and Eu(3+) when excited by a single excitation wavelength. In addition, the as-prepared samples show paramagnetic properties at room temperature. This kind of multifunctional color-tunable phosphor has great potential applications in the fields of photoelectronic devices and biomedical sciences.

Optical and luminescence properties of Dy3+ ions in phosphate based glasses

NASA Astrophysics Data System (ADS)

Rasool, Sk. Nayab; Rama Moorthy, L.; Jayasankar, C. K.

2013-08-01

Phosphate glasses with compositions of 44P2O5 + 17K2O + 9Al2O3 + (30 - x)CaF2 + xDy2O3 (x = 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 4.0 mol %) were prepared and characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier transform infrared (FTIR), optical absorption, emission and decay measurements. The observed absorption bands were analyzed by using the free-ion Hamiltonian (HFI) model. The Judd-Ofelt (JO) analysis has been performed and the intensity parameters (Ωλ, λ = 2, 4, 6) were evaluated in order to predict the radiative properties of the excited states. From the emission spectra, the effective band widths (Δλeff), stimulated emission cross-sections (σ(λp)), yellow to blue (Y/B) intensity ratios and chromaticity color coordinates (x, y) have been determined. The fluorescence decays from the 4F9/2 level of Dy3+ ions were measured by monitoring the intense 4F9/2 → 6H15/2 transition (486 nm). The experimental lifetimes (τexp) are found to decrease with the increase of Dy3+ ions concentration due to the quenching process. The decay curves are perfectly single exponential at lower concentrations and gradually changes to non-exponential for higher concentrations. The non-exponential decay curves are well fitted to the Inokuti-Hirayama (IH) model for S = 6, which indicates that the energy transfer between the donor and acceptor is of dipole-dipole type. The systematic analysis of revealed that the energy transfer mechanism strongly depends on Dy3+ ions concentration and the host glass composition.

Solvent directed morphologies and enhanced luminescent properties of BaWO4:Tm3+,Dy3+ for white light emitting diodes

NASA Astrophysics Data System (ADS)

Wu, Hongyue; Yang, Junfeng; Wang, Xiaoxue; Gan, Shucai; Li, Linlin

2018-05-01

A series of Tm3+ and Dy3+ codoped BaWO4 phosphors with tunable shapes were controllably synthesized by a facile solvothermal method. The effects of ratio of ethylene glycol (EG) and water on the morphologies of BaWO4 structures are systematically studied. It was discovered that the reason for these morphological changes is based on the reaction speed of the kinetic control, which relates to the strong chelating abilities of ethylene glycol. And when the solvent is pure ethylene glycol, the peanut-like BaWO4:Dy3+ has the strongest emission intensity. Moreover, the emission color of the phosphors varied from blue (0.232, 0.180) to white (0.268, 0.250) by controlling Dy3+ ions content with a fixed Tm3+ concentration. The energy transfer mechanism was investigated in detail. With increasing the doped concentration of Dy3+ ions, the energy transfer efficiency of BaWO4:0.005Tm3+,yDy3+ increased gradually and reached as high as 63% when the Dy3+ doped concentration is 0.03. The critical distance RC calculated by the spectral overlap method is about 19.93 Å, and it is in good agreement with that obtained using the concentration quenching method (19.70 Å), indicating that the electric dipole-dipole interaction is the main energy transfer mechanism for BaWO4:Tm3+,Dy3+ phosphors.

Characterization of Natural Dyes and Traditional Korean Silk Fabric by Surface Analytical Techniques.

PubMed

Lee, Jihye; Kang, Min Hwa; Lee, Kang-Bong; Lee, Yeonhee

2013-05-15

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) are well established surface techniques that provide both elemental and organic information from several monolayers of a sample surface, while also allowing depth profiling or image mapping to be carried out. The static TOF-SIMS with improved performances has expanded the application of TOF-SIMS to the study of a variety of organic, polymeric and biological materials. In this work, TOF-SIMS, XPS and Fourier Transform Infrared (FTIR) measurements were used to characterize commercial natural dyes and traditional silk fabric dyed with plant extracts dyes avoiding the time-consuming and destructive extraction procedures necessary for the spectrophotometric and chromatographic methods previously used. Silk textiles dyed with plant extracts were then analyzed for chemical and functional group identification of their dye components and mordants. TOF-SIMS spectra for the dyed silk fabric showed element ions from metallic mordants, specific fragment ions and molecular ions from plant-extracted dyes. The results of TOF-SIMS, XPS and FTIR are very useful as a reference database for comparison with data about traditional Korean silk fabric and to provide an understanding of traditional dyeing materials. Therefore, this study shows that surface techniques are useful for micro-destructive analysis of plant-extracted dyes and Korean dyed silk fabric.

Visible luminescence of Dy3+ doped PbF2-Li2O-SrO-ZnO-B2O3 glasses for yellow light applications

NASA Astrophysics Data System (ADS)

Anjaiah, G.; Sasikala, T.; Kistaiah, P.

2018-05-01

The present studies on various concentrations of Dy3+ ions doped PLSrZFB glasses were carried out through optical absorption, photoluminescence and decay time measurements. The Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2,4,6) can be utilized to evaluate the emission properties. The decay curves for the 4F9/2 levels have been measured and these turns to non-exponential nature at higher concentrations (> 0.1 mol%) is due to energy transfer between the Dy3+-Dy3+ ions dipole -dipole type through cross relaxation channels. The CIE chromaticity color coordinates were calculated and they were all located within the vicinity of white region of the color coordination diagram. The Inokuti-Hirayama model is used to analyze the energy transfer process and also energy transfer parameters have been calculated and discussed.

Structural and Mössbauer analysis of pure and Ce-Dy doped cobalt ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Hashim, Mohd.; Meena, Sher Singh; Kumar, Shalendra; Ahmed, Ateeq; Bhatt, Pramod

2018-05-01

Ce and Dy doped Cobalt ferrites with the chemical composition CoCexDyxFe2-2xO4 (x = 0.00 and 0.04) were synthesized via the chemical route using citrate-gel auto-combustion method. The structural analysis has been carried out with the help of x-ray diffraction (XRD). Formation of spinel cubic structure of the ferrites was confirmed by XRD analysis. Mössbauer spectra were recorded for both samples at room temperature. Presence of the well resolved sextet spectra corresponding to A and B sub-lattice clearly shows that both the samples have ferrimagnetic ordering at room temperature. Isomer shift observed from fitting of the Mössbauer spectra infers that Fe3+ ions are in high valence state. The decrease in the hyperfine field due to the doping of Ce and Dy clearly showed that magnetic interactions diluted due to the doping of Ce and Dy ions.

Manufacturing of Dysprosium-Iron Alloys by Electrolysis in Fluoride-Based Electrolytes. Electrolysis in a Laboratory-Scale Cell

NASA Astrophysics Data System (ADS)

Martinez, Ana Maria; Osen, Karen Sende; Støre, Anne; Gudbrandsen, Henrik; Kjos, Ole Sigmund; Solheim, Asbjørn; Wang, Zhaohui; Oury, Alexandre; Namy, Patrick

2018-04-01

Electrolytic production of light rare earth elements and rare earth alloys with transition elements takes place in a fluoride-based electrolyte using rare earth oxides as raw material. The optimization of this method, mainly in terms of the energy efficiency and environmental impact control, is rather challenging. Anode effects, evolution of fluorine-containing compounds and side cathode reactions could largely be minimized by good control of the amount of rare earth oxide species dissolved in the fluoride-based electrolyte and their dissolution rate. The Dy2O3 feed rate needed for stable cell operation was studied by following up the anode voltage and gas analysis. On-line analysis of the cell off-gases by FTIR showed that the electrochemical reaction for the formation of Dy-Fe alloy gives mainly CO gas and that CF4 is starting to evolve gradually at anode voltages of ca. 3.25 V. The limiting current density for the discharge of the oxide ions at the graphite anode was in the range of 0.1 to 0.18 A cm-2 at dissolved Dy2O3 contents of ca. 1 wt pct. Modeling of the laboratory cell reactor was also carried out by implementing two models, i.e., an electrical model simulating the current density distribution at the electrodes and a laminal bubbly flow model that explains the electrolyte velocity induced by gas bubble production at the anode.

Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide

NASA Astrophysics Data System (ADS)

Halimah, M. K.; Ami Hazlin, M. N.; Muhammad, F. D.

2018-04-01

A series of glass samples with chemical formula {[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}1 - x(Dy2O3)x where x = 0.01, 0.02, 0.03, 0.04 and 0.05 M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO4, BO3, TeO4 and TeO3 vibrational groups. The density of the glass systems is increased with the addition of Dy2O3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy2O3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3 + ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Generation of white light The generation of the white light can be achieved by using two emission bands which comprise of the yellow and blue emission. The white light emission of the glass systems is confirmed by using the Commission International de I'Eclairage 1931 (CIE 1931) chromaticity diagram. The colour coordinate of the zinc borotellurite glass systems doped Dy2O3 is tabulated in Table 3 while Fig. 10 represents the colour chromaticity diagram of Dy2O3 doped zinc borotellurite glass systems. Based on the result obtained, the CIE coordinate for the zinc borotellurite glass doped with dysprosium oxide lies closed to the standard white light point which located at x = 0.333 and y = 0.333 [63,64]. This suggests that the zinc borotellurite glass doped with Dy2O3 may be useful for the solid state lighting application.

Tunable color emission via energy transfer in co-doped Ce3+/Dy3+: Li2O-LiF-B2O3-ZnO glasses for photonic applications

NASA Astrophysics Data System (ADS)

Vijayalakshmi, L.; Naveen Kumar, K.; Srinivasa Rao, K.; Hwang, Pyung

2017-10-01

A set of co-doped (Ce3+/Dy3+): LBZ glasses were prepared by standard melt quenching technique. The pertinent absorption bands were observed in the optical absorption spectrum of co-doped Ce3+/Dy3+: LBZ glasses. We have been observed a prominent blue and yellow emission pertaining to Dy3+ ions at 0.5 mol % under the excitation of 385 nm doped glasses. However, the photoluminescence intensities were remarkably enhanced by co-doping with Ce3+ ions to Dy3+: LBZ glasses due to energy transfer from Ce3+ to Dy3+. The emission spectra of co-doped (Ce3+/Dy3+): LBZ glass exhibits three strong emissions at 440 nm, 480 nm and 574 nm which are assigned with corresponding electronic transitions of 4I15/2 → 6H15/2, 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 respectively. The Commission International de E'clairage coordinates were calculated from their emission spectra of single doped Dy3+ and co-doped (Ce3+/Dy3+): LBZ glasses. The obtained CIE chromaticity coordinates for optimized co-doped glass are found to be very close to the standard white region. Based on the concentration of Ce3+, the emitting color of the co-doped glass can be changed from blue to white color. The transformation of the color from blue to white region due to energy transfer from Ce3+ to Dy3+. The energy transfer mechanism was substantiated by various fluorescence dynamics such as overlapped spectral profiles, photoluminescence, lifetime decay and CIE color coordinate analysis. These results could be suggested that the obtained co-doped (Ce3+/Dy3+): LBZ glasses are promising candidates for commercial white light applications.

Magnetic anisotropy of dysprosium(III) in a low-symmetry environment: a theoretical and experimental investigation.

PubMed

Bernot, Kevin; Luzon, Javier; Bogani, Lapo; Etienne, Mael; Sangregorio, Claudio; Shanmugam, Muralidharan; Caneschi, Andrea; Sessoli, Roberta; Gatteschi, Dante

2009-04-22

A mixed theoretical and experimental approach was used to determine the local magnetic anisotropy of the dysprosium(III) ion in a low-symmetry environment. The susceptibility tensor of the monomeric species having the formula [Dy(hfac)(3)(NIT-C(6)H(4)-OEt)(2)], which contains nitronyl nitroxide (NIT-R) radicals, was determined at various temperatures through angle-resolved magnetometry. These results are in agreement with ab initio calculations performed using the complete active space self-consistent field (CASSCF) method, validating the predictive power of this theoretical approach for complex systems containing rare-earth ions, even in low-symmetry environments. Susceptibility measurements performed with the applied field along the easy axis eventually permitted a detailed analysis of the temperature and field dependence of the magnetization, providing evidence that the Dy ion transmits an antiferromagnetic interaction between radicals but that the Dy-radical interaction is ferromagnetic.

Effect of 100 MeV swift Si8+ ions on structural and thermoluminescence properties of Y2O3:Dy3+nanophosphor

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Lakshminarasappa, B. N.; Nagabhushana, K. R.; Singh, Fouran

2016-05-01

Nanoparticles of Y2O3:Dy3+ were prepared by the solution combustion method. The X-ray diffraction pattern of the 900°C annealed sample shows a cubic structure and the average crystallite size was found to be 31.49 nm. The field emission scanning electron microscopy image of the 900°C annealed sample shows well-separated spherical shape particles and the average particle size is found to be in a range 40 nm. Pellets of Y2O3:Dy3+ were irradiated with 100 MeV swift Si8+ ions for the fluence range of 3 × 1011_3 × 1013 ions cm-2. Pristine Y2O3:Dy3+ shows seven Raman modes with peaks at 129, 160, 330, 376, 434, 467 and 590 cm-1. The intensity of these modes decreases with an increase in ion fluence. A well-resolved thermoluminescence glow with peaks at ∼414 K (Tm1) and ∼614 K (Tm2) were observed in Si8+ ion-irradiated samples. It is found that glow peak intensity at 414 K increases with an increase in the dopant concentration up to 0.6 mol% and then decreases with an increase in dopant concentration. The high-temperature glow peak (614 K) intensity linearly increases with an increase in ion fluence. The broad TL glow curves were deconvoluted using the glow curve deconvoluted method and kinetic parameters were calculated using the general order kinetic equation.

Enhancement of white light emission from novel Ca3Y2Si3O12:Dy3+ phosphors with Ce3+ ion codoping

NASA Astrophysics Data System (ADS)

Bandi, Vengala Rao; Nien, Yung-Tang; Chen, In-Gann

2010-07-01

The luminescent properties of the Ce3+ or Dy3+ singly doped and Ce3+/Dy3+ codoped in Ca3Y2Si3O12 novel phosphors were investigated, which are prepared by a sol-gel method. Ce3+ doped phosphor showed a brighter and broader violet-blue color emission band with a maximum peak centered at 389 nm, which is attributed to the parity and spin allowed 5d-4f transition. Photoluminescence spectra reveals that the white color emission is originated from the mixtures of two characteristic emission bands of Dy3+ ion, viz., the 473 nm blue emission (F49/2-H615/2) and the 580 nm yellow emission (F49/2-H613/2). codoping of Ce3+ has enhanced the luminescence of Dy3+ quite significantly upon the UV excitation wavelength (242 nm) and the optimized codopant concentration of Ce3+ is found to be 3 mol %. The mechanism involved in the energy transfer between Ce3+ and Dy3+ has been elucidated by an energy level diagram. The structure and morphology of the prepared samples have been analyzed by x-ray diffraction and transmission electron microscope.

Competing Structural Instabilities in the Ruddlesden–Popper Derivatives HRTiO 4 (R = Rare Earths): Oxygen Octahedral Rotations Inducing Noncentrosymmetricity and Layer Sliding Retaining Centrosymmetricity

DOE PAGES

Sen Gupta, Arnab; Akamatsu, Hirofumi; Brown, Forrest G.; ...

2016-12-06

We report the discovery of noncentrosymmetry in the family of HRTiO 4 (R = Eu, Gd, Dy) layered oxides possessing a Ruddlesden-Popper derivative structure, by second harmonic generation and synchrotron x-ray diffraction with the support of density functional theory calculations. These oxides were previously thought to possess inversion symmetry. Here, inversion symmetry is broken by oxygen octahedral rotations, a mechanism that is not active in simple perovskites. We discover a competition between oxygen octahedral rotations and sliding of the octahedral perovskite blocks at the OH layers. For the smaller rare earth ions, R = Eu, Gd, Dy, which favor themore » octahedral rotations, noncentrosymmetry is present but the sliding at the OH layer is absent. For the larger rare earth ions, R = Nd and Sm, the octahe-dral rotations are absent, but sliding of the octahedral blocks at the OH layer is present, likely to optimize the hydrogen bond length arising from the directional nature of these bonds in the crystal structure. The study reveals a new mechanism for inducing noncentrosymmetry in layered oxides, and chemical-structural effects related to rare earth ion size and hydrogen bonding that can turn this mechanism on and off. In conclusion, we construct a complete phase diagram of temperature versus rare earth ionic radius for the HRTiO 4 family.« less

Competing Structural Instabilities in the Ruddlesden–Popper Derivatives HRTiO 4 (R = Rare Earths): Oxygen Octahedral Rotations Inducing Noncentrosymmetricity and Layer Sliding Retaining Centrosymmetricity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sen Gupta, Arnab; Akamatsu, Hirofumi; Brown, Forrest G.

We report the discovery of noncentrosymmetry in the family of HRTiO 4 (R = Eu, Gd, Dy) layered oxides possessing a Ruddlesden-Popper derivative structure, by second harmonic generation and synchrotron x-ray diffraction with the support of density functional theory calculations. These oxides were previously thought to possess inversion symmetry. Here, inversion symmetry is broken by oxygen octahedral rotations, a mechanism that is not active in simple perovskites. We discover a competition between oxygen octahedral rotations and sliding of the octahedral perovskite blocks at the OH layers. For the smaller rare earth ions, R = Eu, Gd, Dy, which favor themore » octahedral rotations, noncentrosymmetry is present but the sliding at the OH layer is absent. For the larger rare earth ions, R = Nd and Sm, the octahe-dral rotations are absent, but sliding of the octahedral blocks at the OH layer is present, likely to optimize the hydrogen bond length arising from the directional nature of these bonds in the crystal structure. The study reveals a new mechanism for inducing noncentrosymmetry in layered oxides, and chemical-structural effects related to rare earth ion size and hydrogen bonding that can turn this mechanism on and off. In conclusion, we construct a complete phase diagram of temperature versus rare earth ionic radius for the HRTiO 4 family.« less

Synthesis, characterization and optical properties of NH4Dy(PO3)4

NASA Astrophysics Data System (ADS)

Chemingui, S.; Ferhi, M.; Horchani-Naifer, K.; Férid, M.

2014-09-01

Polycrystalline powders of NH4Dy(PO3)4 polyphosphate have been grown by the flux method. This compound was found to be isotopic with NH4Ce(PO3)4 and RbHo(PO3)4. It crystallizes in the monoclinic space group P21/n with unit cell parameters a=10.474(6) Å, b=9.011(4) Å, c=10.947(7) Å and β=106.64(3)°. The title compound has been transformed to triphosphate Dy(PO3)3 after calcination at 800 °C. Powder X-ray diffraction, infrared and Raman spectroscopies and the differential thermal analysis have been used to identify these materials. The spectroscopic properties have been investigated through absorption, excitation, emission spectra and decay curves of Dy3+ ion in both compounds at room temperature. The emission spectra show the characteristic emission bands of Dy3+ in the two compounds, before and after calcination. The integrated emission intensity ratios of the yellow to blue (IY/IB) transitions and the chromaticity properties have been determined from emission spectra. The decay curves are found to be double-exponential. The non-exponential behavior of the decay rates was related to the resonant energy transfer as well as cross-relaxation between the donor and acceptor Dy3+ ions. The determined properties have been discussed as function of crystal structure of both compounds. They reveal that NH4Dy(PO3)4 is promising for white light generation but Dy(PO3)3 is potential candidates in field emission display (FED) and plasma display panel (PDP) devices.

Magnetomigration of rare-earth ions in inhomogeneous magnetic fields.

PubMed

Franczak, Agnieszka; Binnemans, Koen; Jan Fransaer

2016-10-05

The effects of external inhomogenous (gradient) magnetic fields on the movement of the rare-earth ions: Dy 3+ , Gd 3+ and Y 3+ , in initially homogeneous aqueous solutions have been investigated. Differences in the migration of rare-earth ions in gradient magnetic fields were observed, depending on the magnetic character of the ions: paramagnetic ions of Dy 3+ and Gd 3+ move towards regions of the sample where the magnetic field gradient is the strongest, while diamagnetic ions of Y 3+ move in the opposite direction. It has been showed that the low magnetic field gradients, such the ones generated by permanent magnets, are sufficient to observe the magnetomigration effects of the ions in solution. The present work clearly establishes the behavior of magnetically different ions in initially homogeneous aqueous solutions exposed to magnetic field gradients. To this avail, a methodology for measuring the local concentration differences of metal ions in liquid samples was developed.

Tunable emission in Ln3+ (Ce3+/Dy3+, Ce3+/Tb3+) doped KNa3Al4Si4O16 phosphor synthesized by combustion method

NASA Astrophysics Data System (ADS)

Kolte, M. M.; Pawade, V. B.; Bhattacharya, A. B.; Dhoble, S. J.

2018-05-01

Ln3+ (Ln = Ce3+/Dy3+, Ce3+/Tb3+) doped KNa3Al4Si4O16 phosphor has been synthesized by Combustion method (CS) at 550° C successfully. Ln3+ (Ln = Ce3+, Dy3+, Tb3+) ions when doped in KNa3Al4Si4O16 host lattice, it shows blue and green emission band under the near Ultraviolet (NUV) excitation wavelength. The Photoluminescence excitation (PLE) and emission spectra are observed due to f-f and d-f transition of rare earth ions. Also, an effective energy transfer (ET) study from Ce3+ → Dy3+ and Ce3+ → Tb3+ ions has been studied and confirmed on the basis of Dexter-Foster theory. Further synthesized phosphor is well characterized by XRD, SEM, TEM and decay time measurement. However, the analysis of crystallite size, lattice strain has been studied by using theoretical as well as experimental techniques. Hence, the observed tunable emission in Ln3+ doped KNa3Al4Si4O16 phosphor may be applicable for solid state lighting technology.

Evolution of the orbitals Dy-4f in the DyB2 compound using the LDA, PBE approximations, and the PBE0 hybrid functional

NASA Astrophysics Data System (ADS)

Rasero Causil, Diego; Ortega López, César; Espitia Rico, Miguel

2018-04-01

Computational calculations of total energy based on density functional theory were used to investigate the structural, electronic, and magnetic properties of the DyB2 compounds in the hexagonal structure. The calculations were carried out by means of the full-potential linearized augmented plane wave (FP-LAPW) method, employing the computational Wien2k package. The local density approximation (LDA) and the generalized gradient approximation (GGA) were used for the electron-electron interactions. Additionally, we used the functional hybrid PBE0 for a better description the electronic and magnetic properties, because the DyB2 compound is a strongly-correlated system. We found that the calculated lattice constant agrees well with the values reported theoretically and experimentally. The density of states (DOS) calculation shows that the compound exhibits a metallic behavior and has magnetic properties, with a total magnetic moment of 5.47 μ0/cell determined mainly by the 4f states of the rare earth elements. The functional PBE0 shows a strong localization of the Dy-4f orbitals.

Structure and luminescence properties of Dy 2O 3 doped bismuth-borate glasses

DOE PAGES

Mugoni, Consuelo; Gatto, C.; Pla-Dalmau, A.; ...

2017-07-05

In this study heavy bismuth-borate glasses were studied as host matrices of Dy 2O 3 rare earth, for potential application as scintillator materials in high energy physics experiments and in general radiation detection systems. Glass matrices were prepared from 20BaO-xBi 2O 3-(80-x)B 2O 3 (x = 20, 30, 40 mol%) ternary systems and synthesized by the melt-quenching method at different temperatures in order to obtain high density and high transparency in the UV/Vis range. Particularly, the glass manifesting the higher transparency and with sufficiently high density was doped with Dy 2O 3 (2.5 and 5 mol%) in order to inducemore » the luminescence characteristics. The effects of Bi 2O 3 and Dy 2O 3 on density, thermal behaviour, transmission as well as luminescence properties under UV excitation, were investigated. The experimental results show that the synthesized glasses can be considered promising candidate materials as dense scintillators, due to the Dy 3 + centres emission.« less

O+ trough zones in the polar cap ionosphere-magnetosphere coupling region

NASA Astrophysics Data System (ADS)

Horwitz, James; Zeng, Wen; Jaafari, Fajer

Regions of low-density troughs in O+ have been observed at 1 RE altitude in the polar cap ionosphere-magnetosphere region by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft. In this presentation, the UT Arlington Dynamic Fluid-Kinetic (DyFK) code is employed to investigate the formation of such O+ density troughs. We utilize convection paths of flux tubes in the high-latitude region as prescribed by an empirical convection model with solar wind inputs to track the evolution of ionospheric plasma transport and in particular O+ densities along these tubes with time/space. The flux tubes are subjected to auroral processes of precipitation and wave-driven ion heating when they pass through the auroral oval, which tends to elevate the plasma densities in these tubes. When the F-regions of such tubes traverse locations where the F-region is in darkness, recombination there causes the higher-altitude regions to drain and the densities to decline throughout. Owing to the varying effects of these processes, significant and low trough-like densities at higher altitudes developed along these flux tubes. The modeled densities near 6000 km altitudes will be compared with multiple POLAR passes featuring POLAR/TIDE-measured O+ densities for inside and outside of such trough regions.

Characterization of Natural Dyes and Traditional Korean Silk Fabric by Surface Analytical Techniques

PubMed Central

Lee, Jihye; Kang, Min Hwa; Lee, Kang-Bong; Lee, Yeonhee

2013-01-01

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) are well established surface techniques that provide both elemental and organic information from several monolayers of a sample surface, while also allowing depth profiling or image mapping to be carried out. The static TOF-SIMS with improved performances has expanded the application of TOF-SIMS to the study of a variety of organic, polymeric and biological materials. In this work, TOF-SIMS, XPS and Fourier Transform Infrared (FTIR) measurements were used to characterize commercial natural dyes and traditional silk fabric dyed with plant extracts dyes avoiding the time-consuming and destructive extraction procedures necessary for the spectrophotometric and chromatographic methods previously used. Silk textiles dyed with plant extracts were then analyzed for chemical and functional group identification of their dye components and mordants. TOF-SIMS spectra for the dyed silk fabric showed element ions from metallic mordants, specific fragment ions and molecular ions from plant-extracted dyes. The results of TOF-SIMS, XPS and FTIR are very useful as a reference database for comparison with data about traditional Korean silk fabric and to provide an understanding of traditional dyeing materials. Therefore, this study shows that surface techniques are useful for micro-destructive analysis of plant-extracted dyes and Korean dyed silk fabric. PMID:28809257

Effect of copper on the properties of Pr-Dy-Fe-Co-B sintered magnets

NASA Astrophysics Data System (ADS)

Kablov, E. N.; Piskorskii, V. P.; Valeev, R. A.; Volkov, N. V.; Davydova, E. A.; Shaikhutdinov, K. A.; Balaev, D. A.; Semenov, S. V.

2014-01-01

The effect of copper on the properties of magnets (Pr0.52Dy0.48)13(Fe65Co0.35)80.3 - x Cu x B6.7 ( x = 0-10) has been studied. Alloying with copper is shown to decrease the sintering temperature and to increase the content of the principal (Pr,Dy)2(Fe,Co)14B magnetic phase. For compositions with x = 1.3-3.3, copper is found to affect the value and sign of the temperature induction coefficient (TIC). It is shown that the effect of copper on the TIC is determined by the substitution of copper ions for iron ions in lattice sites, which are coupled via an antiferromagnetic exchange interaction.

Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

NASA Astrophysics Data System (ADS)

Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

2018-05-01

Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

Photodissociation spectroscopy of the dysprosium monochloride molecular ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunning, Alexander, E-mail: alexander.dunning@gmail.com; Schowalter, Steven J.; Puri, Prateek

2015-09-28

We have performed a combined experimental and theoretical study of the photodissociation cross section of the molecular ion DyCl{sup +}. The photodissociation cross section for the photon energy range 35 500 cm{sup −1} to 47 500 cm{sup −1} is measured using an integrated ion trap and time-of-flight mass spectrometer; we observe a broad, asymmetric profile that is peaked near 43 000 cm{sup −1}. The theoretical cross section is determined from electronic potentials and transition dipole moments calculated using the relativistic configuration-interaction valence-bond and coupled-cluster methods. The electronic structure of DyCl{sup +} is extremely complex due to the presence of multiple open electronic shells,more » including the 4f{sup 10} configuration. The molecule has nine attractive potentials with ionically bonded electrons and 99 repulsive potentials dissociating to a ground state Dy{sup +} ion and Cl atom. We explain the lack of symmetry in the cross section as due to multiple contributions from one-electron-dominated transitions between the vibrational ground state and several resolved repulsive excited states.« less

Effect of charge compensator ions (R+ = Li+, Na+ and K+) on Sr2MgSi2O7:Dy3+ phosphors by solid-state reaction method

NASA Astrophysics Data System (ADS)

Sahu, Ishwar Prasad

2016-09-01

The Sr2MgSi2O7:Dy3+ and Sr2MgSi2O7:Dy3+, R+ (R+ = Li+, Na+ and K+) phosphors were prepared by solid-state reaction method. The crystal structures of sintered phosphors were an akermanite-type structure which belongs to the tetragonal crystallography. The prepared phosphors were excited at 350 nm, and their corresponding emission spectrum were recorded at blue (482 nm) and yellow (575 nm) region due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively, of Dy3+ ions. Commission Internationale de L'Eclairage coordinates have been calculated for each sample and its value exhibited that overall emission is near white light. The possible mechanisms of discussed white light emitting phosphors were also investigated. In order to investigate the suitability of the samples as white color light sources for industrial uses, color purity, correlated color temperature (CCT) and color rendering index (CRI) were calculated. Values of color purity, CCT and CRI were found well within the defined acceptable range. With incorporating (R+ = Li+, Na+ and K+) as charge compensator ions, the emission intensity of Sr2MgSi2O7:Dy3+ can be obviously enhanced. The results indicate that prepared phosphors may be a potential application in display devices.

Luminescence properties of Dy3+ doped lithium zinc borosilicate glasses for photonic applications.

PubMed

Jaidass, N; Krishna Moorthi, C; Mohan Babu, A; Reddi Babu, M

2018-03-01

Different concentrations of Dy 3+ ions doped lithium zinc borosilicate glasses of chemical composition (30-x) B 2 O 3 - 25 SiO 2 -10 Al 2 O 3 -30 LiF - 5 ZnO - x Dy 2 O 3 (x = 0, 0.1, 0.5, 1.0 and 2.0 mol%) were prepared by the melt quenching technique. The prepared glasses were investigated through X-ray diffraction, optical absorption, photoluminescence and decay measurements. Intensities of absorption bands expressed in terms of oscillator strengths (f) were used to determine the Judd-Ofelt (J-O) intensity parameters Ω λ (λ = 2, 4 and 6). The evaluated J-O parameters were used to determine the radiative parameters such as transition probabilities (A R ), total transition probability rate (A T ), radiative lifetime (τ R ) and branching ratios (β R ) for the excited 4 F 9/2 level of Dy 3+ ions. The chromaticity coordinates determined from the emission spectra were found to be located in the white light region of CIE chromaticity diagram.

On the photo-luminescence properties of sol–gel derived undoped and Dy{sup 3+} ion doped nanocrystalline Scheelite type AMoO{sub 4} (A = Ca, Sr and Ba)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jena, Paramananda; Gupta, Santosh K., E-mail: santufrnd@gmail.com; Natarajan, V.

2015-04-15

Nanocrystalline Scheelite type Dy doped AMoO{sub 4} [where A = Ba, Sr and Ca] samples were prepared by acrylamide assisted sol–gel process and characterized by XRD, FT-Raman, FTIR, SEM and photoluminescence (PL). PL of undoped sample shows blue/green emission in CaMoO{sub 4} and SrMoO{sub 4} but multicolour visible emission leading to near white light in BaMoO{sub 4} nanoparticles; the origin of which is explained. It was observed that on doping 0.5 mol% of Dy{sup 3+} in molybdate samples complete energy transfer takes place in case of SrMoO{sub 4} and BaMoO{sub 4}, but host contributed substantially in Dy doped BaMoO{sub 4}more » sample, resulting in biexponential decay. It was also observed that symmetry around Dy{sup 3+} decreases as the size of alkaline earth ion increases. Due to combined blue, yellow and red colour emission in dysprosium doped sample; all samples showed near white light emission under UV and near UV excitation.« less

Wheel-like Ln18 Cluster Organic Frameworks for Magnetic Refrigeration and Conversion of CO2.

PubMed

Song, Tian-Qun; Dong, Jie; Yang, An-Fei; Che, Xue-Jing; Gao, Hong-Ling; Cui, Jian-Zhong; Zhao, Bin

2018-03-19

Two isostructural 2D MOFs ([Ln 7 (CDA) 6 (HCOO) 3 (μ 3 -OH) 6 (H 2 O) 8 ] n , abbreviated as 1-Gd and 2-Dy) were successfully synthesized under solvothermal conditions. The self-assembly of lanthanide(III) nitrate and 1,1'-cyclopropane-dicarboxylic acid (H 2 CDA) resulted in wheel-like Ln 18 cluster second building units (SBU), which are further linked to six neighboring wheels to generate a 2D ordered honeycomb array. Both 1-Gd and 2-Dy exhibit high thermal stability and decompose above 330 °C. Moreover, they have good solvent stability in ten common solvents and pH stability with pH values from 1 to 13. Magnetic studies reveal that 1-Gd exhibits weak antiferromagnetic coupling between adjacent Gd 3+ ions and has a large magnetocaloric effect of 47.30 J kg -1 K -1 (Δ H = 7.0 T at 2 K), while 2-Dy shows ferromagnetic interaction between adjacent Dy 3+ ions. Interestingly, 1-Gd and 2-Dy can catalyze the cycloaddition of CO 2 to epoxides under mild conditions and can be reused at least five rounds with negligible loss of catalytic performance.

Investigations on surface chemical analysis using X-ray photoelectron spectroscopy and optical properties of Dy3+-doped LiNa3P2O7 phosphor

NASA Astrophysics Data System (ADS)

Munirathnam, K.; Dillip, G. R.; Chaurasia, Shivanand; Joo, S. W.; Deva Prasad Raju, B.; John Sushma, N.

2016-08-01

Near white-light emitting LiNa3P2O7:Dy3+ phosphors were prepared by a conventional solid-state reaction method. The orthorhombic crystal structure of the phosphors was confirmed using X-ray diffraction (XRD), and the valence states of the surface elements were determined from the binding energies of Li 1s, O 1s, Na 1s, P 2p, and Dy 3d by X-ray photoelectron spectroscopy (XPS). Attenuated total reflectance (ATR) - Fourier transform infrared (FT-IR) spectroscopy was employed to identify the pyrophosphate groups in the phosphors. Diffuse reflectance spectra (DRS) show the absorption bands of the Dy3+ ions in the host material. Intense blue (481 nm) and yellow (575 nm) emissions were obtained at an excitation wavelength of 351 nm and are attributed to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. The combination of these two intense bands generates light emission in the near-white region of the chromaticity diagram.

Surface Thermometry of Energetic Materials by Laser-Induced Fluorescence

DTIC Science & Technology

1989-09-01

at 34 yttrium- aluminum -garnet (Dy:YAG). The simplified energy diagram of Dy:YAG is shown in Fig. 1. Absorbed laser light (at 355 nrm) can 5 excite the...the thermometric technique on a surface similar to that of an energetic material, a thermal-setting plastic supplied by Buehler, Ltd., was employed...temperature over the temperature range of interest. The rare-earth ion dysprosium (Dy) doped into a yttrium- aluminum -garnet (YAG) crystal was I determined

Analysis of the Role of Peripheral Ligands Coordinated to Zn(II) in Enhancing the Energy Barrier in Luminescent Linear Trinuclear Zn-Dy-Zn Single-Molecule Magnets.

PubMed

Costes, Jean Pierre; Titos-Padilla, Silvia; Oyarzabal, Itziar; Gupta, Tulika; Duhayon, Carine; Rajaraman, Gopalan; Colacio, Enrique

2015-10-26

Three new Dy complexes have been prepared according to a complex-as-ligand strategy. Structural determinations indicate that the central Dy ion is surrounded by two LZn units (L(2-) is the di-deprotonated form of the N2 O2 compartmental N,N'-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato) Schiff base. The Dy ions are nonacoordinate to eight oxygen atoms from the two L ligands and to a water molecule. The Zn ions are pentacoordinate in all cases, linked to the N2 O2 atoms from L, and the apical position of the Zn coordination sphere is occupied by a water molecule or bromide or chloride ions. These resulting complexes, formulated (LZnX)-Dy-(LZnX), are tricationic with X=H2 O and monocationic with X=Br or Cl. They behave as field-free single-molecule magnets (SMMs) with effective energy barriers (Ueff ) for the reversal of the magnetization of 96.9(6) K with τ0 =2.4×10(-7)  s, 146.8(5) K with τ0 =9.2×10(-8)  s, and 146.1(10) K with τ0 =9.9×10(-8)  s for compounds with ZnOH2 , ZnBr, and ZnCl motifs, respectively. The Cole-Cole plots exhibit semicircular shapes with α parameters in the range of 0.19 to 0.29, which suggests multiple relaxation processes. Under a dc applied magnetic field of 1000 Oe, the quantum tunneling of magnetization (QTM) is partly or fully suppressed and the energy barriers increase to Ueff =128.6(5) K and τ0 =1.8×10(-8)  s for 1, Ueff =214.7 K and τ0 =9.8×10(-9)  s for 2, and Ueff =202.4 K and τ0 =1.5×10(-8)  s for 3. The two pairs of largely negatively charged phenoxido oxygen atoms with short DyO bonds are positioned at opposite sides of the Dy(3+) ion, which thus creates a strong crystal field that stabilizes the axial MJ =±15/2 doublet as the ground Kramers doublet. Although the compound with the ZnOH2 motifs possesses the larger negative charges on the phenolate oxygen atoms, as confirmed by using DFT calculations, it exhibits the larger distortions of the DyO9 coordination polyhedron from ideal geometries and a smaller Ueff value. Ab initio calculations support the easy-axis anisotropy of the ground Kramers doublet and predict zero-field SMM behavior through Orbach and TA-QTM relaxations via the first excited Kramers doublet, which leads to large energy barriers. In accordance with the experimental results, ab initio calculations have also shown that, compared with water, the peripheral halide ligands coordinated to the Zn(2+) ions increase the barrier height when the distortions of the DyO9 have a negative effect. All the complexes exhibit metal-centered luminescence after excitation into the UV π-π* absorption band of ligand L(2-) at λ=335 nm, which results in the appearance of the characteristic Dy(III) ((4) F9/2 →(6) HJ/2 ; J=15/2, 13/2) emission bands in the visible region. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]·solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].

PubMed

Sakamoto, Soichiro; Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Re, Nazzareno

2013-06-17

Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]·2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-μ-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (μ4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius plot to be 12.2(7) and 6.1(3) K for 1Tb and 2Tb, respectively, and 18.1(6) and 14.5(4) K for 1Dy and 2Dy, respectively, under a dc bias field of 1000 Oe. Compound 1Dy showed relatively slow relaxation of magnetization reorientation even at zero dc applied field with Δ/kB = 6.6(4) K.

Extended X-ray Absorption Fine Structure (EXAFS) Analysis of Vitreous Rare Earth Sodium Phosphates

NASA Astrophysics Data System (ADS)

Yoo, Changhyeon; Marasinghe, Kanishka; Segre, Carlo; Shibata, Tomohiro

2015-03-01

The local structure around rare-earth ions (RE3+) in rare-earth ultraphosphate (REUP) glasses has been studied using RE LIII edge (RE = Nd, Er, Dy, and Eu) and K edge (RE = Nd, Pr, Dy, and Eu) extended X-ray absorption fine structure (EXAFS) spectroscopy. (RE2O3)x (Na2O)y(P2O5) 1 - x - y glasses in the compositional range 0 <= x <= 0.14 and x + y = 0.3 and 0.4 were studied. RE-oxygen (RE-O) coordination number decreases from ~ 10 to ~ 7.5 with increasing RE-content for Nd, Pr, Eu, and Dy. For Er, RE-O coordination number increases from ~ 8.7 to ~ 10 with increasing RE-content. For the first oxygen shell, the RE-O distance ranges between 2.41-2.43 Å, 2.44-2.46 Å, 2.24-2.26 Å, 2.28-2.32 Å, and 2.32-2.36 Å for Nd, Pr, Er, Dy, and EU glasses, respectively. Second shell around RE ions consists of phosphorus atoms, with RE-P distance about 3.0-3.5 Å and coordination number ranging from 1 to 3. The third shell primarily contains oxygen and is at a distance about 4.0-4.1 Å from RE ions.

Ion-irradiation resistance of the orthorhombic Ln2TiO5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) series

NASA Astrophysics Data System (ADS)

Aughterson, Robert D.; Lumpkin, Gregory R.; Ionescu, Mihail; Reyes, Massey de los; Gault, Baptiste; Whittle, Karl R.; Smith, Katherine L.; Cairney, Julie M.

2015-12-01

The response of Ln2TiO5 (where Ln is a lanthanide) compounds exposed to high-energy ions was used to test their suitability for nuclear-based applications, under two different but complementary conditions. Eight samples with nominal stoichiometry Ln2TiO5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy), of orthorhombic (Pnma) structure were irradiated, at various temperatures, with 1 MeV Kr2+ ions in-situ within a transmission electron microscope. In each case, the fluence was increased until a phase transition from crystalline to amorphous was observed, termed critical dose Dc. At certain elevated temperatures, the crystallinity was maintained irrespective of fluence. The critical temperature for maintaining crystallinity, Tc, varied non-uniformly across the series. The Tc was consistently high for La, Pr, Nd and Sm2TiO5 before sequential improvement from Eu to Dy2TiO5 with Tc's dropping from 974 K to 712 K. In addition, bulk Dy2TiO5 was irradiated with 12 MeV Au+ ions at 300 K, 723 K and 823 K and monitored via grazing-incidence X-ray diffraction (GIXRD). At 300 K, only amorphisation is observed, with no transition to other structures, whilst at higher temperatures, specimens retained their original structure. The improved radiation tolerance of compounds containing smaller lanthanides has previously been attributed to their ability to form radiation-induced phase transitions. No such transitions were observed here.

Desolvation-Driven 100-Fold Slow-down of Tunneling Relaxation Rate in Co(II)-Dy(III) Single-Molecule Magnets through a Single-Crystal-to-Single-Crystal Process

NASA Astrophysics Data System (ADS)

Liu, Jun-Liang; Wu, Jie-Yi; Huang, Guo-Zhang; Chen, Yan-Cong; Jia, Jian-Hua; Ungur, Liviu; Chibotaru, Liviu F.; Chen, Xiao-Ming; Tong, Ming-Liang

2015-11-01

Single-molecule magnets (SMMs) are regarded as a class of promising materials for spintronic and ultrahigh-density storage devices. Tuning the magnetic dynamics of single-molecule magnets is a crucial challenge for chemists. Lanthanide ions are not only highly magnetically anisotropic but also highly sensitive to the changes in the coordination environments. We developed a feasible approach to understand parts of the magneto-structure correlations and propose to regulate the relaxation behaviors via rational design. A series of Co(II)-Dy(III)-Co(II) complexes were obtained using in situ synthesis; in this system of complexes, the relaxation dynamics can be greatly improved, accompanied with desolvation, via single-crystal to single-crystal transformation. The effective energy barrier can be increased from 293 cm-1 (422 K) to 416 cm-1 (600 K), and the tunneling relaxation time can be grown from 8.5 × 10-4 s to 7.4 × 10-2 s. These remarkable improvements are due to the change in the coordination environments of Dy(III) and Co(II). Ab initio calculations were performed to better understand the magnetic dynamics.

Manipulation of Dy-Mn coupling and ferrielectric phase diagram of DyMn2O5: The effect of Y substitution of Dy

NASA Astrophysics Data System (ADS)

Zhao, Z. Y.; Wang, Y. L.; Lin, L.; Liu, M. F.; Li, X.; Yan, Z. B.; Liu, J.-M.

2015-11-01

DyMn2O5 is an extraordinary example in the family of multiferroic manganites and it accommodates both the 4f and 3d magnetic ions with strong Dy-Mn (4f-3d) coupling. The electric polarization origin is believed to arise not only from the Mn spin interactions but also from the Dy-Mn coupling. Starting from proposed scenario on ferrielectricity in DyMn2O5 where the exchange-strictions associated with the Mn3+-Mn4+-Mn3+ blocks and Dy3+-Mn4+-Dy3+ blocks generate the two ferroelectric sublattices, we perform a set of characterizations on the structure, magnetism, and electric polarization of Dy1-xYxMn2O5 in order to investigate the roles of Dy-Mn coupling in manipulating the ferrielectricity. It is revealed that the non-magnetic Y substitution of Dy suppresses gradually the Dy3+ spin ordering and the Dy-Mn coupling. Consequently, the ferroelectric sublattice generated by the exchange striction associated with the Dy3+-Mn4+-Dy3+ blocks is destabilized, but the ferroelectric sublattice generated by the exchange striction associated with the Mn3+-Mn4+-Mn3+ blocks remains less perturbed, enabling the ferrielectricity-ferroelectricity transitions with the Y substitution. A phenomenological ferrielectric domain model is suggested to explain the polarization reversal induced by the Y substitution. The present work presents a possible scenario of the multiferroic mechanism in not only DyMn2O5 but probably also other RMn2O5 members with strong 4f-3d coupling.

Increasing the effective energy barrier promoted by the change of a counteranion in a Zn-Dy-Zn SMM: slow relaxation via the second excited state.

PubMed

Oyarzabal, I; Ruiz, J; Ruiz, E; Aravena, D; Seco, J M; Colacio, E

2015-08-11

The trinuclear complex [ZnCl(μ-L)Dy(μ-L)ClZn]PF6 exhibits a single-molecule magnetic behaviour under zero field with a relatively large effective energy barrier of 186 cm(-1). Ab initio calculations reveal that the relaxation of the magnetization is symmetry-driven (the Dy(III) ion possesses a C2 symmetry) and occurs via the second excited state.

Room-temperature ferromagnetism in Dy films doped with Ni

NASA Astrophysics Data System (ADS)

Edelman, I.; Ovchinnikov, S.; Markov, V.; Kosyrev, N.; Seredkin, V.; Khudjakov, A.; Bondarenko, G.; Kesler, V.

2008-09-01

Temperature, magnetic field and spectral dependences of magneto-optical effects (MOEs) in bi-layer films Dy (1-x)Ni x-Ni and Dy (1-x)(NiFe) x-NiFe were investigated, x changes from 0 to 0.06. Peculiar behavior of the MOEs was revealed at temperatures essentially exceeding the Curie temperature of bulk Dy which is explained by the magnetic ordering of the Dy layer containing Ni under the action of two factors: Ni impurities distributed homogeneously over the whole Dy layer and atomic contact of this layer with continues Ni layer. The mechanism of the magnetic ordering is suggested to be associated with the change of the density of states of the alloy Dy (1-x)Ni x owing to hybridization with narrow peaks near the Fermi level character for Ni.

Simultaneous occurrence of multiferroism and short-range magnetic order in DyFeO 3

DOE PAGES

Wang, Jinchen; Liu, Juanjuan; Sheng, Jieming; ...

2016-04-06

In this paper, we present a combined neutron scattering and magnetization study on the multiferroic DyFeO 3, which shows a very strong magnetoelectric effect. Applying magnetic field along the c axis, the weak ferromagnetic order of the Fe ions is quickly recovered from a spin reorientation transition, and the long-range antiferromagnetic order of Dy becomes a short-range one. We found that the short-range order concurs with the multiferroic phase and is responsible for its sizable hysteresis. In conclusion, our H-T phase diagram suggests that the strong magnetoelectric effect in DyFeO 3 has to be understood with not only the weakmore » ferromagnetism of Fe but also the short-range antiferromagnetic order of Dy.« less

Synthesis and photoluminescence properties of Dy{sup 3+} doped white light emitting CdTa{sub 2}O{sub 6} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

İlhan, Mustafa, E-mail: mustafa.ilhan@marmara.edu.tr; Ekmekçi, Mete Kaan

2015-03-15

The undoped and CdTa{sub 2}O{sub 6}:Dy{sup 3+} (0.2≤x≤2.0 mol%) phosphors were synthesized at 1100 °C for 12 h by the conventional solid state reaction method. The synthesized CdTa{sub 2}O{sub 6}:Dy{sup 3+} phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Photoluminescence (PL) analyses. The PL spectra showed the presence of excitation peaks between 310 and 440 nm due to the 4f–4f transitions of Dy{sup 3+}. The emission of Dy{sup 3+} ions at 353.0 nm excitation was observed at 487.1 nm (blue) and 577.8 nm (yellow) due to the {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2}more » transitions and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} transitions, respectively. The PL analysis results also showed that the emissions increase with the increasing Dy{sup 3+} ion content. The emissions increased with the doping concentration of up to 1 mol%, and above this level decreased due to concentration quenching effect. The CIE chromaticity color coordinates (x,y) of the CdTa{sub 2}O{sub 6}:Dy{sup 3+} phosphors were found to be in the white light region of the chromaticity diagram. - Graphical abstract: Emission spectra at λ{sub ex}=353.0 nm and CIE chromaticity coordinate diagram of CdTa{sub 2}O{sub 6}:Dy{sup 3+} phosphors. - Highlights: • Pure and CdTa{sub 2}O{sub 6}:Dy{sup 3+} was produced by solid state reaction method. • CdTa{sub 2}O{sub 6}:Dy{sup 3+} phosphor exhibited blue and yellow emissions due to the {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} transitions. • The CCT value for 1.0 mol% CdTa{sub 2}O{sub 6}:Dy{sup 3+} was 5133 K which was located in the cool white daylight region. • Dy{sup 3+} doped CdTa{sub 2}O{sub 6} phosphor has potential in the production of white LEDs.« less

Bulk properties of the medium produced in relativistic heavy-ion collisions from the beam energy scan program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.

We present measurements of bulk properties of the matter produced in Au+Au collisions atmore » $$\\sqrt{s}$$$_ {NN}$$= 7.7, 11.5, 19.6, 27, and 39 GeV using identified hadrons (π ±, K ±, p, and $$\\bar{p}$$) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (| y | < 0.1) results for multiplicity densities dN / dy, average transverse momenta $$\\langle$$pT$$\\rangle$$, and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic measurements of bulk properties of matter formed in heavy-ion collisions over a broad range of energy (or baryon chemical potential) at RHIC.« less

Bulk properties of the medium produced in relativistic heavy-ion collisions from the beam energy scan program

DOE PAGES

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

2017-10-13

We present measurements of bulk properties of the matter produced in Au+Au collisions atmore » $$\\sqrt{s}$$$_ {NN}$$= 7.7, 11.5, 19.6, 27, and 39 GeV using identified hadrons (π ±, K ±, p, and $$\\bar{p}$$) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (| y | < 0.1) results for multiplicity densities dN / dy, average transverse momenta $$\\langle$$pT$$\\rangle$$, and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic measurements of bulk properties of matter formed in heavy-ion collisions over a broad range of energy (or baryon chemical potential) at RHIC.« less

Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy₂Ti₂O₇.

PubMed

Anand, V K; Tennant, D A; Lake, B

2015-11-04

Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility χ(ac)(T), dc magnetic susceptibility χ(T), isothermal magnetization M(H) and heat capacity C(p)(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent χ(ac)(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca(2+) substitution for magnetic Dy(3+) is similar to the previous study on nonmagnetic isovalent Y(3+) substituted Dy(2-x)Y(x) Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca(2+) substitution for Dy(3+) ions.

Facile synthesis, structural characterization, and photoluminescence mechanism of Dy3+ doped YVO4 and Ca2+ co-doped YVO4:Dy3+ nano-lattices

NASA Astrophysics Data System (ADS)

Dhiren Meetei, Sanoujam; Deben Singh, Mutum; Dorendrajit Singh, Shougaijam

2014-05-01

Light plays a vital role in the evolution of life. From sunlight to candle-light and then to other form of lighting devices, human beings are utilizing light since time immemorial. Lighting devices such as conventional incandescent lamp and fluorescent lamp have been replaced by Light Emitting Diodes (LEDs) for the later is cheap, durable, etc. Now-a-days, phosphor converted LEDs have been burning issues in the fabrication of lighting devices. Especially, lanthanide ion(s) doped phosphors are of great interest for the same. However, doped phosphors have a limitation of luminescence quenching, i.e., instead of increasing luminescence on increasing dopant concentration, the luminescence decreases. Therefore, it must be rectified by one or other means so as to get maximum desirable intensity for uses in display or lighting devices. In the present work, YVO4:Dy3+ and YVO4:Dy3+/Ca2+ nano-lattices are synthesized by a facile technique. Structural characterizations such as x-ray diffraction, SEM, TEM, HRTEM, and Selected Area Electron Diffraction (SAED) of the samples are reported. Photoluminescence (PL) excitation and emission, enhanced mechanism, and lifetime are thoroughly discussed. PL intensity of the quenched YVO4:Dy3+ is made increased up to 432.63% by Ca2+ co-doping. Role of the Ca2+ on the luminescence enhanced mechanism of YVO4:Dy3+/Ca2+ is elucidated.

By-product identification and phytotoxicity of biodegraded Direct Yellow 4 dye.

PubMed

Nouren, Shazia; Bhatti, Haq Nawaz; Iqbal, Munawar; Bibi, Ismat; Kamal, Shagufta; Sadaf, Sana; Sultan, Misbah; Kausar, Abida; Safa, Yusra

2017-02-01

Citrus limon peroxidase mediated decolourization of Direct Yellow 4 (DY4) was investigated. The process variables (pH, temperature, incubation time, enzyme dose, H 2 O 2 amount, dye concentration, co-metal ions and surfactants) were optimized for maximum degradation of dye. Maximum dye decolourization of 89.47% was achieved at pH 5.0, temperature 50 °C, enzyme dose 24 U/mL, H 2 O 2 concentration 0.25 mM and DY4 concentration 18.75 mg/L and incubation time 10 min. The co-metal ions and surfactants did not affect the dye decolourization significantly. Response surface analysis revealed that predicted values were in agreement with experimentally determined responses. The degradation products were identified by UPLC/MS analysis and degradation pathway was proposed. Besides, phytotoxicity assay revealed a considerable detoxification in response of biodegradation of DY4 dye. C. limon showed promising efficiency for DY4 degradation and could possibly be used for the remediation of textile effluents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhancement of lanthanide evaporation by complexation: dysprosium tri-iodide mixed with indium iodide and thulium tri-iodide mixed with thallium iodide.

PubMed

Curry, J J; Estupiñán, E G; Henins, A; Lapatovich, W P; Shastri, S D; Hardis, J E

2013-09-28

The vapors in equilibrium with condensates of DyI3, DyI3/InI, TmI3, and TmI3/TlI were observed over the temperature range from 900 K to 1400 K using x-ray induced fluorescence. The total densities of each element (Dy, Tm, In, Tl, and I) in the vapor, summed over all atomic and molecular species, were determined. Dramatic enhancements in the total vapor densities of Dy and Tm were observed in the vapors over DyI3/InI and TmI3/TlI as compared to the vapors over pure DyI3 and pure TmI3, respectively. An enhancement factor exceeding 10 was observed for Dy at T ≈ 1020 K, decreasing to 0 at T ≈ 1250 K. An enhancement factor exceeding 20 was observed for Tm at T ≈ 1040 K, decreasing to 0 at T ≈ 1300 K. Such enhancements are expected from the formation of the vapor-phase hetero-complexes DyInI4 and TmTlI4. Numerical simulations of the thermo-chemical equilibrium suggest the importance of additional complexes in liquid phases. A description of the measurement technique is given. Improvements in the absolute calibration lead to an approximately 40% correction to previously reported preliminary results [J. J. Curry et al., Chem. Phys. Lett. 507, 52 (2011); Appl. Phys. Lett. 100, 083505 (2012)].

Yellow to greenish-blue colour-tunable photoluminescence and 4f-centered slow magnetic relaxation in a cyanido-bridged Dy(III)(4-hydroxypyridine)-Co(III) layered material.

PubMed

Chorazy, Szymon; Wang, Junhao; Ohkoshi, Shin-Ichi

2016-09-14

A cyanido-bridged layered {[Dy(III)(4-OHpy)2(H2O)3][Co(III)(CN)6]}·0.5H2O (1) (4-OHpy = 4-hydroxypyridine) framework with dual photo-luminescence and magnetic properties was prepared. 1 exhibits visible emission whose color, yellow to greenish-blue, is switchable by selected wavelengths of UV excitation light. Magnetic data revealed that 1 shows not only the slow magnetic relaxation of a typical Dy(III) single-ion origin but also the relaxation process caused by the magnetic dipole-magnetic dipole interactions between the neighbouring Dy(III) centers.

Quenching the Quantum Tunneling of Magnetization in Heterometallic Octanuclear {TMIII4 DyIII4 } (TM=Co and Cr) Single-Molecule Magnets by Modification of the Bridging Ligands and Enhancing the Magnetic Exchange Coupling.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Murray, Keith S; Rajaraman, Gopalan

2017-01-31

We report the synthesis, structural characterisation, magnetic properties and provide an ab initio analysis of the magnetic behaviour of two new heterometallic octanuclear coordination complexes containing Co III and Dy III ions. Single-crystal X-ray diffraction studies revealed molecular formulae of [Co III 4 Dy III 4 (μ-OH) 4 (μ 3 -OMe) 4 {O 2 CC(CH 3 ) 3 } 4 (tea) 4 (H 2 O) 4 ]⋅4 H 2 O (1) and [Co III 4 Dy III 4 (μ-F) 4 (μ 3 -OH) 4 (o-tol) 8 (mdea) 4 ]⋅ 3 H 2 O⋅EtOH⋅MeOH (2; tea 3- =triply deprotonated triethanolamine; mdea 2- =doubly deprotonated N-methyldiethanolamine; o-tol=o-toluate), and both complexes display an identical metallic core topology. Furthermore, the theoretical, magnetic and SMM properties of the isostructural complex, [Cr III 4 Dy III 4 (μ-F 4 )(μ 3 -OMe) 1.25 (μ 3 -OH) 2.75 (O 2 CPh) 8 (mdea) 4 ] (3), are discussed and compared with a structurally similar complex, [Cr III 4 Dy III 4 (μ 3 -OH) 4 (μ-N 3 ) 4 (mdea) 4 (O 2 CC(CH 3 ) 3 ) 4 ] (4). DC and AC magnetic susceptibility data revealed single-molecule magnet (SMM) behaviour for 1-4. Each complex displays dynamic behaviour, highlighting the effect of ligand and transition metal ion replacement on SMM properties. Complexes 2, 3 and 4 exhibited slow magnetic relaxation with barrier heights (U eff ) of 39.0, 55.0 and 10.4 cm -1 respectively. Complex 1, conversely, did not exhibit slow relaxation of magnetisation above 2 K. To probe the variance in the observed U eff  values, calculations by using CASSCF, RASSI-SO and POLY_ANISO routine were performed on these complexes to estimate the nature of the magnetic coupling and elucidate the mechanism of magnetic relaxation. Calculations gave values of J Dy-Dy as -1.6, 1.6 and 2.8 cm -1 for complexes 1, 2 and 3, respectively, whereas the J Dy-Cr interaction was estimated to be -1.8 cm -1 for complex 3. The developed mechanism for magnetic relaxation revealed that replacement of the hydroxide ion by fluoride quenched the quantum tunnelling of magnetisation (QTM) significantly, and led to improved SMM properties for complex 2 compared with 1. However, the tunnelling of magnetisation at low-lying excited states was still operational for 2, which led to low-temperature QTM relaxation. Replacement of the diamagnetic Co III ions with paramagnetic Cr III led to Cr III ⋅⋅⋅Dy III coupling, which resulted in quenching of QTM at low temperatures for complexes 3 and 4. The best example was found if both Cr III and fluoride were present, as seen for complex 3, for which both factors additively quenched QTM and led to the observation of highly coercive magnetic hysteresis loops above 2 K. Herein, we propose a synthetic strategy to quench the QTM effects in lanthanide-based SMMs. Our strategy differs from existing methods, in which parameters such as magnetic coupling are difficult to control, and it is likely to have implications beyond the Dy III SMMs studied herein. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic interactions in rhenium-containing rare earth double perovskites Sr{sub 2}LnReO{sub 6} (Ln=rare earths)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishiyama, Atsuhide; Doi, Yoshihiro; Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp

The perovskite-type compounds containing both rare earth and rhenium Sr{sub 2}LnReO{sub 6} (Ln=Y, Tb-Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Re{sup 5+} ions are structurally ordered at the B site of the perovskite SrBO{sub 3}. Magnetic anomalies are found in their magnetic susceptibility and specific heat measurements at 2.6–20 K for Ln=Y, Tb, Dy, Yb, Lu compounds. They are due to magnetic interactions between Re{sup 5+} ions. The results of the magnetic hysteresis and remnant magnetization measurements for Sr{sub 2}YReO{sub 6} and Sr{sub 2}LuReO{sub 6} indicate that the antiferromagnetic interactions betweenmore » Re{sup 5+} ions below transition temperatures have a weak ferromagnetic component. The analysis of the magnetic specific heat data for Sr{sub 2}YbReO{sub 6} shows that both the Yb{sup 3+} and Re{sup 5+} ions magnetically order at 20 K. For the case of Sr{sub 2}DyReO{sub 6}, magnetic ordering of the Re{sup 5+} moments occurs at 93 K, and with decreasing temperature, the moments of Dy{sup 3+} ferromagnetically order at 5 K from the measurements of magnetic susceptibility and specific heat. - Graphical abstract: Crystal structure of double perovskite Sr{sub 2}LnReO{sub 6}. Red and black lines show cubic and monoclinic unit cells, respectively. - Highlights: • Double perovskites Sr{sub 2}LnReO{sub 6} (Ln=rare earths) were prepared. • They show an antiferromagnetic transition at 2.6–20 K. • In Sr{sub 2}DyReO{sub 6}, Dy and Re moments magnetically order at 5 and 93 K, respectively.« less

Improving the SMM and luminescence properties of lanthanide complexes with LnO9 cores in the presence of ZnII: an emissive Zn2Dy single ion magnet.

PubMed

Fondo, Matilde; Corredoira-Vázquez, Julio; Herrera-Lanzós, Antía; García-Deibe, Ana M; Sanmartín-Matalobos, Jesús; Herrera, Juan Manuel; Colacio, Enrique; Nuñez, Cristina

2017-12-12

Mononuclear complexes of stoichiometry [Ln(H 3 L)(H 2 O)(NO 3 )](NO 3 ) 2 (Ln = Tb, 1; Dy, 2, Er, 3), which crystallise with different solvates, and the heterotrinuclear compound [Zn 2 Dy(L)(NO 3 ) 3 (OH)] (4) can be obtained with the same H 3 L compartmental ligand. The single X-ray crystal structure of the mononuclear complexes shows a LnO 9 core with a muffin-like disposition while the geometry of the DyO 9 core in 4 seems to be closer to spherical capped square antiprism. The analysis of the magnetic properties of all the complexes demonstrates that the mononuclear lanthanide compounds do not show slow relaxation of the magnetization, even when the samples are diluted with a diamagnetic matrix and subjected to a dc applied field of 1000 Oe. Nevertheless, the heterotrinuclear dysprosium complex 4·3H 2 O is a field-induced single ion magnet, with an estimated U eff barrier of 59 K. The luminescence characterisation of all the metal complexes in methanol solution at 298 K also shows a notable increase in the fluorescence emission of the heterotrinuclear complex with respect to the mononuclear ones, in such a way that 4 can be defined as a fluorescent single ion magnet.

White emission materials from glass doped with rare Earth ions: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasaka, P.; Kaewkhao, J., E-mail: mink110@hotmail.com; Physics Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, 73000

2016-03-11

Solid State Lighting (SSL) based devices are predicted to play a crucial role in the coming years. Development of W-LED, which have an edge over traditional lighting sources due to their compact size, higher reliability, shock resistance, interesting design possibilities, higher transparency and an extremely long lifetime. Over the fifteen trivalent lanthanide ions, Dy{sup 3+} ions doped glasses are most appropriate for white light generation because of the fact that it exhibits two intense emission bands corresponds to the {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} (magnetic dipole) and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} (electric dipole) transitions at around 480-500 nm and 580-600 nmmore » pertaining to blue and yellow regions respectively. In this work, the developments of Dy3+ doped in several glass structures for white emitting materials application have reviewed. Properties of Dy{sup 3+} doped in glasses were discussed for use as a solid state lighting materials application.« less

Judd-Ofelt analysis and spectral properties of Dy3+ ions doped niobium containing tellurium calcium zinc borate glasses

NASA Astrophysics Data System (ADS)

Ravi, O.; Reddy, C. Madhukar; Reddy, B. Sudhakar; Deva Prasad Raju, B.

2014-02-01

Niobium containing tellurium calcium zinc borate (TCZNB) glasses doped with different concentrations of Dy3+ ions were prepared by the melt quenching method and their optical properties have been studied. The Judd-Ofelt (J-O) intensity parameters Ωt (t=2, 4 and 6) were calculated using the least square fit method. Based on the magnitude of Ω2 parameter the hypersensitivity of 6H15/2→6F11/2 has also been discussed. From the evaluated J-O intensity parameters as well as from the emission and lifetime measurements, radiative transition properties such as radiative transition probability rates and branching ratios were calculated for 4F9/2 excited level. It is found that for Dy3+ ion, the transition 4F9/2→6H13/2 shows highest emission cross-section at 1.0 mol% TCZNB glass matrix. From the visible luminescence spectra, yellow to blue (Y/B) intensity ratios and chromaticity color coordinates were also estimated. The TCZNB glasses exhibit good luminescence properties and are suitable for generation of white light.

Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

NASA Astrophysics Data System (ADS)

Ami Hazlin, M. N.; Halimah, M. K.; Muhammad, F. D.; Faznny, M. F.

2017-04-01

The zinc borotellurite doped with dysprosium oxide glass samples with chemical formula {[(TeO2) 0 . 7(B2O3) 0 . 3 ] 0 . 7(ZnO) 0 . 3 } 1 - x(Dy2O3)x (where x=0.01, 0.02, 0.03, 0.04 and 0.05 M fraction) were prepared by using conventional melt quenching technique. The structural and optical properties of the proposed glass systems were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and UV-VIS spectroscopy. The amorphous nature of the glass systems is confirmed by using XRD technique. The infrared spectra of the glass systems indicate three obvious absorption bands which are assigned to BO3 and TeO4 vibrational groups. Based on the absorption spectra obtained, the direct and indirect optical band gaps, as well as the Urbach energy were calculated. It is observed that both the direct and indirect optical band gaps increase with the concentration of Dy3+ ions. On the other hand, the Urbach energy is observed to decrease as the concentration of Dy3+ ions increases.

Improved alumina scale adhesion of electron beam physical vapor deposited Dy/Hf-doped β-NiAl coatings

NASA Astrophysics Data System (ADS)

Li, Dongqing; Guo, Hongbo; Peng, Hui; Gong, Shengkai; Xu, Huibin

2013-10-01

The cyclic oxidation behavior of Dy/Hf-doped β-NiAl coatings produced by electron beam physical vapor deposition (EB-PVD) was investigated. For the undoped NiAl coating, numerous voids were formed at the alumina scale/coating interface and large rumpling developed in the scale, leading to premature oxide spallation. The addition of Dy and Hf both improved scale adhesion and the alumina scale grown on the NiAl-Hf coating showed better adhesion than that on the NiAl-Dy coating, although the suppressing effect on interfacial void formation and the scale rumpling resistance were stronger in the NiAl-Dy coating. It is proposed that the segregation of Dy and Hf ions at the scale/coating interfaces not only prevent interfacial sulfur segregation but also may directly enhance interfacial adhesion by participating in bonding across the interfaces, and this strengthening effect is relatively stronger for Hf ionic segregation.

Transfer of Magnetic Order and Anisotropy through Epitaxial Integration of 3d and 4f Spin Systems.

PubMed

Bluschke, M; Frano, A; Schierle, E; Minola, M; Hepting, M; Christiani, G; Logvenov, G; Weschke, E; Benckiser, E; Keimer, B

2017-05-19

Resonant x-ray scattering at the Dy M_{5} and Ni L_{3} absorption edges was used to probe the temperature and magnetic field dependence of magnetic order in epitaxial LaNiO_{3}-DyScO_{3} superlattices. For superlattices with 2 unit cell thick LaNiO_{3} layers, a commensurate spiral state develops in the Ni spin system below 100 K. Upon cooling below T_{ind}=18  K, Dy-Ni exchange interactions across the LaNiO_{3}-DyScO_{3} interfaces induce collinear magnetic order of interfacial Dy moments as well as a reorientation of the Ni spins to a direction dictated by the strong magnetocrystalline anisotropy of Dy. This transition is reversible by an external magnetic field of 3 T. Tailored exchange interactions between rare-earth and transition-metal ions thus open up new perspectives for the manipulation of spin structures in metal-oxide heterostructures and devices.

Slow magnetic relaxation in carbonato-bridged dinuclear lanthanide(III) complexes with 2,3-quinoxalinediolate ligands.

PubMed

Vallejo, Julia; Cano, Joan; Castro, Isabel; Julve, Miguel; Lloret, Francesc; Fabelo, Oscar; Cañadillas-Delgado, Laura; Pardo, Emilio

2012-08-11

The coordination chemistry of the 2,3-quinoxalinediolate ligand with different lanthanide(III) ions in basic media in air affords a new family of carbonato-bridged M(2)(III) compounds (M = Pr, Gd and Dy), the Dy(2)(III) analogue exhibiting slow magnetic relaxation behaviour typical of single-molecule magnets.

Study of absorption and IR-emission of Er3+, Dy3+, Tm3+ doped high-purity tellurite glasses

NASA Astrophysics Data System (ADS)

Motorin, S. E.; Dorofeev, V. V.; Galagan, B. I.; Sverchkov, S. E.; Koltashev, V. V.; Denker, B. I.

2018-04-01

A study of high-purity TeO2-ZnO based tellurite glasses doped with Er3+, Dy3+ or Tm3+ that could be used as laser media in the 2-3 μm spectral range is presented. The glasses are prepared by melting the oxides mixture inside a silica glass reactor in an atmosphere of purified oxygen. The low level of hydroxyl groups absorption allowed to measure correctly the luminescence decay characteristics of the dopants. The rare-earth ions absorption bands, the luminescence spectra and kinetic characteristics of emission from the levels 4I11/2, 4I13/2 of Er3+, 6H13/2 of Dy3+ and 3H4, 3H5, 3F4 of Tm3+ ions are investigated. The results confirm the high potential of tellurite glasses as an active media for bulk, planar waveguide and fiber lasers.

Sol-gel synthesis and luminescence property of Sr4 Al2 O7 :Re3+ ,R+ (Re = Eu and Dy; R = Li, Na and K) phosphors for white LEDs.

PubMed

Zhang, Wentao; Yu, Meng; Dai, Siyi; Chen, Xianfei; Long, Jianping

2017-09-01

Sr 4 Al 2 O 7 :Eu 3+ and Sr 4 Al 2 O 7 :Dy 3+ phosphors with alkali metal substitution were prepared using a sol-gel method. The effects of a charge compensator R on the structure and luminescence of Sr 4 Al 2 O 7 :Re 3+ ,R + (Re = Eu and Dy; R = Li, Na and K) phosphors were investigated in detail. Upon heating to 1400°C, the structure of the prepared samples was that of the standard phase of Sr 4 Al 2 O 7 . Under ultraviolet excitation, all Sr 4 Al 2 O 7 :Eu 3+ ,R + samples exhibited several narrow emission peaks ranging from 550 to 700 nm due to the 4f → 4f transition of Eu 3+ ions. All Sr 4 Al 2 O 7 :Dy 3+ ,R + phosphors showed two emission peaks at 492 and 582 nm, due to the 4 F 9/2  →  6 H 15/2 and 4 F 9/2  →  6 H 13/2 transitions of Dy 3+ ions, respectively. The luminescence intensity of Sr 4 Al 2 O 7 :Re 3+ ,R + (Re = Eu and Dy; R = Li, Na and K) phosphors improved markedly upon the addition of charge compensators, promoting their application in white light-emitting diodes with a near-ultraviolet chip. Copyright © 2017 John Wiley & Sons, Ltd.

Facile synthesis, structural characterization, and photoluminescence mechanism of Dy{sup 3+} doped YVO{sub 4} and Ca{sup 2+} co-doped YVO{sub 4}:Dy{sup 3+} nano-lattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhiren Meetei, Sanoujam, E-mail: sdmdhiren@gmail.com; Dorendrajit Singh, Shougaijam, E-mail: dorendrajit@yahoo.co.in, E-mail: mdebensingh@gmail.com; Deben Singh, Mutum, E-mail: dorendrajit@yahoo.co.in, E-mail: mdebensingh@gmail.com

2014-05-28

Light plays a vital role in the evolution of life. From sunlight to candle-light and then to other form of lighting devices, human beings are utilizing light since time immemorial. Lighting devices such as conventional incandescent lamp and fluorescent lamp have been replaced by Light Emitting Diodes (LEDs) for the later is cheap, durable, etc. Now-a-days, phosphor converted LEDs have been burning issues in the fabrication of lighting devices. Especially, lanthanide ion(s) doped phosphors are of great interest for the same. However, doped phosphors have a limitation of luminescence quenching, i.e., instead of increasing luminescence on increasing dopant concentration, themore » luminescence decreases. Therefore, it must be rectified by one or other means so as to get maximum desirable intensity for uses in display or lighting devices. In the present work, YVO{sub 4}:Dy{sup 3+} and YVO{sub 4}:Dy{sup 3+}/Ca{sup 2+} nano-lattices are synthesized by a facile technique. Structural characterizations such as x-ray diffraction, SEM, TEM, HRTEM, and Selected Area Electron Diffraction (SAED) of the samples are reported. Photoluminescence (PL) excitation and emission, enhanced mechanism, and lifetime are thoroughly discussed. PL intensity of the quenched YVO{sub 4}:Dy{sup 3+} is made increased up to 432.63% by Ca{sup 2+} co-doping. Role of the Ca{sup 2+} on the luminescence enhanced mechanism of YVO{sub 4}:Dy{sup 3+}/Ca{sup 2+} is elucidated.« less

Judd-Ofelt Analysis of Dy3+-Activated Aluminosilicate Glasses Prepared by Sol-Gel Method

NASA Astrophysics Data System (ADS)

Sengthong, Buonyavong; Van Tuyen, Ho; An, Nguyen Thi Thai; Van Do, Phan; Hai, Nguyen Thi Quy; Chau, Pham Thi Minh; Quang, Vu Xuan

2018-04-01

Aluminosilicate (AS) glasses doped with different Dy3+ concentrations were synthesized via sol-gel method. Absorption, photoluminescence spectra and lifetime of this material have been studied. From analytical results of absorption spectra, the Judd-Ofelt (JO) parameters of prepared samples have been determined. These JO parameters combined with photoluminescence spectra have been used to evaluate transition probabilities ( A R), branching ratios ( β) and the calculated oscillator strengths of AS:Dy3+ glasses. The radiative branching ratio of 4F9/2 → 6H13/2 transition has a minimum value at 62.2% for β R which predicts that this transition in AS:Dy3+ glasses can give rise to lasing action. JO parameters show that the Ω2 increases with the increasing of Dy3+ ion concentration due to the increased polarizability of the average coordination medium and decreased average symmetry.

Photoluminescence properties of NaPbB{sub 5}O{sub 9}:Dy{sup 3+} new material for white light applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajesh, D., E-mail: ratnakaramsvu@gmail.com; Ratnakaram, Y. C., E-mail: ratnakaramsvu@gmail.com

2014-04-24

Keeping in view of the recent increased interest towards phosphor materials and its applications, an attempt has been made in the present paper to analyze the new NaPbB{sub 5}O{sub 9}:Dy{sub 3+} phosphor with different Dy{sub 3+} concentrations. Special attention is paid to investigate their crystal structure, morphology and luminescence properties. X-ray diffraction (XRD) results confirm the formation of NaPbB{sub 5}O{sub 9}:Dy{sub 3+} phosphor powder. The scanning electron microscope (SEM) images show that the grains are in micrometer range. Photoluminescence spectra are recorded with different excitation wavelengths for the investigated phosphor and analyzed the variation of intensity of emission bands withmore » Dy{sub 3+} ion concentration. Color co-ordinates are calculated and are used to characterize the color of the phosphor.« less

Crystal Structure of the Caged Magnetic Compound DyFe2Zn20 at Low Temperature Magnetic Ordering State

NASA Astrophysics Data System (ADS)

Kishii, Nobuya; Tateno, Shota; Ohashi, Masashi; Isikawa, Yosikazu

We have carried out X-ray powder diffraction and thermal expansion measurements of the caged magnetic compound DyFe2Zn20. Even though a strong magnetic anisotropy exists in the magnetization and magnetic susceptibility due to strong exchange interaction between Fe and Dy, almost all X-ray powder diffraction peaks at 14 K correspond to Bragg reflections of the cubic structural models not only at room temperature paramagnetic state but also at low temperature magnetic ordering state. Although the temperature change of the lattice constant is isotropic, an anomalous behavior was observed in the thermal expansion coefficient around 15 K, while the anomaly around TC = 53 K is not clear. The results indicate that the volume change is not caused by the ferromagnetic interaction between Fe and Dy but by the exchange interaction between two Dy ions.

Synthesis, characterization and properties of Dy3+-activated single host borosilicate phosphors

NASA Astrophysics Data System (ADS)

Yu, Hong; Chen, Shanyong; Chen, Jinlei

2017-12-01

New phosphors Sr3B2SiO8: Dy3+ have been successfully synthesized via solid-state reaction process. Emission/excitation spectra, photoluminescence decay behaviors were investigated in detail. Under the excitation of 351 nm, the emission spectrum consisting of the characteristic transitions of Dy3+ which mainly peaking at 480, 487 nm and 574 nm corresponding to the4F9/2→6H15/2 and4F9/2→6H13/2, respectively, the intensity of the blue emission stronger than the yellow one which indicated that Dy3+ ions take the site without inversion symmetry. The chromaticity coordinates of Sr3-xB2SiO8: x Dy3+ fixed in the white region. The results showed the kind of phosphor may be act potential applications in the fields of UV-excited white LEDs.

Paramagnetic dysprosium-doped zinc oxide thin films grown by pulsed-laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lo, Fang-Yuh, E-mail: fangyuhlo@ntnu.edu.tw; Ting, Yi-Chieh; Chou, Kai-Chieh

2015-06-07

Dysprosium(Dy)-doped zinc oxide (Dy:ZnO) thin films were fabricated on c-oriented sapphire substrate by pulsed-laser deposition with doping concentration ranging from 1 to 10 at. %. X-ray diffraction (XRD), Raman-scattering, optical transmission spectroscopy, and spectroscopic ellipsometry revealed incorporation of Dy into ZnO host matrix without secondary phase. Solubility limit of Dy in ZnO under our deposition condition was between 5 and 10 at. % according to XRD and Raman-scattering characteristics. Optical transmission spectroscopy and spectroscopic ellipsometry also showed increase in both transmittance in ultraviolet regime and band gap of Dy:ZnO with increasing Dy density. Zinc vacancies and zinc interstitials were identified by photoluminescencemore » spectroscopy as the defects accompanied with Dy incorporation. Magnetic investigations with a superconducting quantum interference device showed paramagnetism without long-range order for all Dy:ZnO thin films, and a hint of antiferromagnetic alignment of Dy impurities was observed at highest doping concentration—indicating the overall contribution of zinc vacancies and zinc interstitials to magnetic interaction was either neutral or toward antiferromagnetic. From our investigations, Dy:ZnO thin films could be useful for spin alignment and magneto-optical applications.« less

Understanding the Mechanism of Magnetic Relaxation in Pentanuclear {MnIVMnIII2LnIII2} Single-Molecule Magnets.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S; Rajaraman, Gopalan

2018-02-05

A new family of heterometallic pentanuclear complexes of formulas [Mn IV Mn III 2 Ln III 2 O 2 (benz) 4 (mdea) 3 (NO 3 ) 2 (MeOH)] (Ln = Dy (1-Dy), Tb (2-Tb), Gd (3-Gd), Eu (4-Eu), Sm (5-Sm), Nd (6-Nd), Pr (7-Pr); benz(H) = benzoic acid; mdeaH 2 = N-methyldiethanolamine) and [Mn IV Mn III 2 Ln III 2 O 2 (o-tol) 4 (mdea) 3 (NO 3 ) 2 (MeOH)] (Ln = Gd (8-Gd), Eu (9-Eu); o-tol(H) = o-toluic acid) have been isolated and structurally, magnetically, and theoretically characterized. dc magnetic susceptibility measurements reveal dominant antiferromagnetic magnetic interactions for each complex, except for 2-Tb and 3-Gd, which reveal an upturn in the χ M T product at low temperatures. The magnetic interactions between the spin centers in the Gd derivatives, 3-Gd and 8-Gd, which display markedly different χ M T vs T profiles, were found to be due to the interactions of the Gd III -Gd III ions which change from ferromagnetic (3-Gd) to antiferromagnetic (8-Gd) due to structural differences. ac magnetic susceptibility measurements reveal a nonzero out-of-phase component for 1-Dy and 7-Pr, but no maxima were observed above 2 K (H dc = 0 Oe), which suggests single-molecule magnet (SMM) behavior. Out-of-phase signals were observed for complexes 2-Tb, 4-Eu, 8-Gd, and 9-Eu, in the presence of a static dc field (H dc = 2000, 3000 Oe). The anisotropic nature of the lanthanide ions in the benzoate series (1-Dy, 2-Tb, 5-Sm, 6-Nd, and 7-Pr) were thoroughly investigated using ab initio methods. CASSCF calculations predict that the origin of SMM behavior in 1-Dy and 7-Pr and the applied field SMM behavior in 2-Tb does not solely originate from the single-ion anisotropy of the lanthanide ions. To fully understand the relaxation mechanism, we have employed the Lines model to fit the susceptibility data using the POLY_ANISO program, which suggests that the zero-field SMM behavior observed in complexes 1-Dy and 7-Pr is due to weak Mn III/IV -Ln III and Ln III -Ln III couplings and an unfavorable Ln III /Mn III /Mn IV anisotropy. In complexes 4-Eu, 8-Gd, and 9-Eu ab initio calculations indicate that the anisotropy of the Mn III ions solely gives rise to the possibility of SMM behavior. Complex 7-Pr is a Pr(III)-containing complex that displays zero-field SMM behavior, which is rare, and our study suggests the possibility of coupling weak SOC lanthanide metal ions to anisotropic transition-metal ions to derive SMM characteristics; however, enhancing the exchange coupling in {3d-4f} complexes is still a stubborn hurdle in harnessing new generation {3d-4f} SMMs.

Effect of dilution in the cobalt subsystem on phase transitions in rare-earth cobaltites RBaCo4- x M x O7 (R = Dy-Er, Yb, Y; M = Al, Zn)

NASA Astrophysics Data System (ADS)

Kazei, Z. A.; Snegirev, V. V.; Kozeeva, L. P.; Kameneva, M. Yu.

2016-01-01

We have experimentally studied the structural and elastic characteristics of rare-earth cobaltites RBaCo4- x M x O7 (R = Dy-Er, Yb, Y), in which cobalt ions are partly substituted by diamagnetic Al or Zn ions. It was found that small substitution of Co3+ ions by Al3+ ions in the YbRBaCo4- x M x O7 system ( x = 0.1, 0.2, 0.5) leads to a rapid decrease and smearing of Δ E( T) /E 0 anomalies of the Young's modulus in the region of the structural phase transition, which is accompanied by increasing hysteresis. Pure rare-earth cobaltites RBaCo4O7 (R = Dy-Er, Y) exhibit a correlation between the room-temperature structure distortion and hysteresis on the Δ E( T)/ E 0 curve in a temperature interval of 80-280 K. In Zn-substituted cobaltites RBaCoZn3O7, both the hysteresis and Δ E( T)/ E 0 anomalies disappear, as do low-temperature sound absorption maxima. This behavior is evidence of the suppression of structural and magnetic phase transitions and the retention of only short-range correlations of the order parameter in Zn-substituted samples.

Tunable luminescence mediated by energy transfer in Tm3+/Dy3+ co-doped phosphate glasses under UV excitation

NASA Astrophysics Data System (ADS)

Chen, Yong; Chen, Guohua; Liu, Xiangyu; Yuan, Changlai; Zhou, Changrong

2017-11-01

Tm3+/Dy3+ co-doped phosphate glasses for white light-emitting diodes were synthesized by a conventional melting-quenching method. A spectroscopic research based on optical, photoluminescence spectrum and decay time curves in Tm3+/Dy3+ co-doped phosphate glasses was carried out. The color of luminescence could be tuned by altering the concentrations of Tm3+ ions. Under UV light excitation, the CIE chromaticity coordinates (0.3471, 0.3374) and color correlate temperature (CCT = 4866.21 K) close to the standard white-light illumination (0.333, 0.333 and CCT = 5454.12 K) could be achieved in 0.4 Tm3+/0.6 Dy3+ (mol %) co-doped glass sample. The decrease of the Dy3+ emission decay time in existence of Tm3+ ascertained that non-radiative energy transfer from Dy3+ to Tm3+ occurred. Moreover, the research of energy transfers between Dy3+ and Tm3+ based on the Inokuti-Hirayama model revealed that an electric quadrupole-quadrupole interaction might be the predominant mechanism participated in the energy transfer. This finding suggests that the as-prepared Tm3+/Dy3+ co-doped phosphate glasses may be promising candidate for white LEDs and other display devices.

Enhancement of luminescence in white emitting strontium fluoride core @ calcium fluoride shell nanoparticles

NASA Astrophysics Data System (ADS)

Kumam, Nandini; Singh, Ningthoujam Premananda; Singh, Laishram Priyobarta; Srivastava, Sri Krishna

2015-09-01

Synthesis of lanthanide-doped fluoride SrF2:3Dy and SrF2:3Dy@CaF2 nanoparticles with different ratios of core to shell (1:0.5, 1:1 and 1:2) has been carried out by employing ethylene glycol route. X-ray diffraction (XRD) patterns reveal that the structure of the prepared nanoparticles was of cubical shape, which is also evident in TEM images. The size of the nanoparticles for core (SrF2:3Dy) is found to increase when core is covered by shell (CaF2). It is also evident from Fourier transform infrared spectroscopy (FTIR) that ethylene glycol successfully controls the growth and acts as a shape modifier by regulating growth rate. In the photoluminescence investigation, emission spectra of SrF2:3Dy is found to be highly enhanced when SrF2:3Dy is covered by CaF2 due to the decrease of cross relaxation amongst the Dy3+-Dy3+ ions. Such type of enhancement of luminescence in homonanostructure SrF2:3Dy@CaF2 (core@shell) has not been studied so far, to the best of the authors' knowledge. This luminescent material exhibits prominently white light emitting properties as shown by the Commission Internationale d'Eclairage (CIE) chromaticity diagram. The calculated correlate colour temperature (CCT) values for SrF2:3Dy, SrF2:3Dy@CaF2 (1:0.05), SrF2:3Dy@CaF2 (1:1) and SrF2:3Dy@CaF2 (1:2) are 5475, 5476, 5384 and 5525 K, respectively, which lie in the cold white region.

Blue–green afterglow of BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Bao-gai; Ma, Qing-lan; School of Electronics and Information, Nantong University, Jiangsu 226019

Highlights: • Afterglow can be achieved when Eu{sup 2+} is absent in the DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • The afterglow of DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors is discernible to naked eyes for minutes. • Dy{sup 3+} introduced trap centers are believed to be responsible for the afterglow. - Abstract: Dy{sup 3+} doped barium aluminate (BaAl{sub 2}O{sub 4}:Dy{sup 3+}) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of themore » absence of Eu{sup 2+} luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl{sub 2}O{sub 4}:Dy{sup 3+} in the absence of Eu{sup 2+} provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors are discussed in terms of the Dy{sup 3+} ions introduced trap centers as well as luminescent centers in the crystal lattice.« less

Magnetic ground state of the Ising-like antiferromagnet DyScO 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, L. S.; Nikitin, Stanislav E.; Frontzek, Matthias D.

2017-10-05

Here, we report on the low-temperature magnetic properties of the DyScO3 perovskite, which were characterized by means of single crystal and powder neutron scattering, and by magnetization measurements. Below T N = 3.15 K, Dy 3+ moments form an antiferromagnetic structure with an easy axis of magnetization lying in the ab plane. The magnetic moments are inclined at an angle of ~ ±28° to the b axis. We show that the ground-state Kramers doublet of Dy 3+ is made up of primarily |±15/2> eigenvectors and well separated by a crystal field from the first excited state at E 1 =more » 24.9 meV. This leads to an extreme Ising single-ion anisotropy, M ⊥/M ∥~0.05. The transverse magnetic fluctuations, which are proportional to M 2 ⊥/M 2 ∥, are suppressed, and only moment fluctuations along the local Ising direction are allowed. We also found that the Dy-Dy dipolar interactions along the crystallographic c axis are two to four times larger than in-plane interactions.« less

Dilution-triggered SMM behavior under zero field in a luminescent Zn2Dy2 tetranuclear complex incorporating carbonato-bridging ligands derived from atmospheric CO2 fixation.

PubMed

Titos-Padilla, Silvia; Ruiz, José; Herrera, Juan Manuel; Brechin, Euan K; Wersndorfer, Wolfgang; Lloret, Francesc; Colacio, Enrique

2013-08-19

The synthesis, structure, magnetic, and luminescence properties of the Zn2Dy2 tetranuclear complex of formula {(μ3-CO3)2[Zn(μ-L)Dy(NO3)]2}·4CH3OH (1), where H2L is the compartmental ligand N,N',N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine, are reported. The carbonate anions that bridge two Zn(μ-L)Dy units come from the atmospheric CO2 fixation in a basic medium. Fast quantum tunneling relaxation of the magnetization (QTM) is very effective in this compound, so that single-molecule magnet (SMM) behavior is only observed in the presence of an applied dc field of 1000 Oe, which is able to partly suppress the QTM relaxation process. At variance, a 1:10 Dy:Y magnetic diluted sample, namely, 1', exhibits SMM behavior at zero applied direct-current (dc) field with about 3 times higher thermal energy barrier than that in 1 (U(eff) = 68 K), thus demonstrating the important role of intermolecular dipolar interactions in favoring the fast QTM relaxation process. When a dc field of 1000 Oe is applied to 1', the QTM is almost fully suppressed, the reversal of the magnetization slightly slows, and U(eff) increases to 78 K. The dilution results combined with micro-SQUID magnetization measurements clearly indicate that the SMM behavior comes from single-ion relaxation of the Dy(3+) ions. Analysis of the relaxation data points out that a Raman relaxation process could significantly affect the Orbach relaxation process, reducing the thermal energy barrier U(eff) for slow relaxation of the magnetization.

Synthesis and characterization of Silica/polyvinyl imidazole/H2PO4-core-shell nanoparticles as recyclable adsorbent for efficient scavenging of Sm(III) and Dy(III) from water.

PubMed

Ettehadi Gargari, Jafar; Sid Kalal, Hossein; Shakeri, Alireza; Khanchi, Alireza

2017-11-01

In this study, we used Silica/polyvinyl imidazole core-shell nanoparticles impregnated with sodium dihydrogen phosphate (SiO 2 /PVI/H 2 PO 4 - NPs) for adsorption of samarium and dysprosium ions from aqueous solutions. The effects of the pH, adsorbent dose, contact time, and initial concentration of the adsorbate on the Core-shell nanoparticles adsorption capacity have been studied. The pH value for maximum removal of Sm (III) and Dy (III) on the core-shell nanoparticles surface were found to be 4. The saturated capacity of SiO 2 /PVI/H 2 PO 4 - NPs was up to 160mg.g -1 and 150mg.g -1 at 25°C for Sm (III) and Dy (III) ions respectively. The obtained uptake data were analyzed by the Langmuir and Freundlich equations using a linearized correlation coefficient at room temperature. The Freundlich isotherm was found to fit well with the equilibrium data. The adsorption kinetics could be modeled by a pseudo-second-order rate expression. Thermodynamic investigation revealed the adsorption process of the studied ions is entropy driven. Furthermore, the performance of regeneration and reutilization were studied. The adsorbed Sm (III) and Dy (III) can be desorbed by 0.5mol/L HCl, with the desorption percentage of 90% for Sm (III) and Dy (III). After five adsorption-desorption cycles, the adsorption capacity shows a slight decrease (about 15%), implying that the SiO 2 /PVI/H 2 PO 4 - NPs can be used as an effective adsorbent for the removal and recovery of Sm(III) and Dy(III) from aqueous solution. The colloid stability of the SiO 2 /PVI/H 2 PO 4 - NPs was investigated by dynamic light scattering measurements. The SiO 2 /PVI/H 2 PO 4 - NPs are stable in adsorption media after five adsorption - desorption cycles. The high stability of SiO 2 /PVI/H 2 PO 4 - NPs can be attributed to steric stabilization by polyvinyl imidazole adsorbed on SiO 2 nanoparticle surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats1[OPEN

PubMed Central

de Boer, Hugo J.; Drake, Paul L.; Wendt, Erin; Price, Charles A.; Schulze, Ernst-Detlef; Turner, Neil C.; Nicolle, Dean

2016-01-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. PMID:27784769

Efficient enhancement of magnetic anisotropy by optimizing the ligand-field in a typically tetranuclear dysprosium cluster.

PubMed

Liu, Jiang; Chen, Yan-Cong; Jiang, Zhong-Xia; Liu, Jun-Liang; Jia, Jian-Hua; Wang, Long-Fei; Li, Quan-Wen; Tong, Ming-Liang

2015-05-07

The perturbation to the ligand field around the lanthanide ion may significantly contribute to the magnetic dynamics of single molecule magnets. This can be demonstrated by two typical Dy4 cluster-based single molecular magnets (SMMs), [Dy4X2(μ3-OH)2(μ-OH)2(2,2-bpt)4(H2O)4]X2·2H2O·4EtOH (X = Cl and Br for and , respectively), which were constructed by using 3,5-bis(pyridin-2-yl)-1,2,4-triazole (2,2-bptH) as the polynuclear-chelating ligand. Alternating-current (ac) magnetic susceptibility measurements show that the energy barriers in complexes and were immensely enhanced by comparing with our previous work due to the optimization of the ligand field around Dy(III) ions. Remarkably, their high thermal active barriers at 190 K () and 197 K () under a zero applied external dc magnetic field are also among the highest within the reported tetranuclear lanthanide-based SMMs.

Designing a Dy2 Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine- N-Oxide Ligand: A Comparison with Mononuclear Counterparts.

PubMed

Díaz-Ortega, Ismael F; Herrera, Juan Manuel; Aravena, Daniel; Ruiz, Eliseo; Gupta, Tulika; Rajaraman, Gopalan; Nojiri, H; Colacio, Enrique

2018-06-04

Herein we report a dinuclear [(μ-mbpymNO){(tmh) 3 Dy} 2 ] (1) single-molecule magnet (SMM) showing two nonequivalent Dy III centers, which was rationally prepared from the reaction of Dy(tmh) 3 moieties (tmh = 2,2,6,6-tetramethyl-3,5-heptanedionate) and the asymmetric bis-bidentate bridging ligand 4-methylbipyrimidine (mbpymNO). Depending on whether the Dy III ions coordinate to the N^O or N^N bidentate donor sets, the Dy III sites present a NO 7 ( D 2 d geometry) or N 2 O 6 ( D 4 d ) coordination sphere. As a consequence, two different thermally activated magnetic relaxation processes are observed with anisotropy barriers of 47.8 and 54.7 K. Ab initio calculations confirm the existence of two different relaxation phenomena and allow one to assign the 47.8 and 54.7 K energy barriers to the Dy(N 2 O 6 ) and Dy(NO 7 ) sites, respectively. Two mononuclear complexes, [Dy(tta) 3 (mbpymNO)] (2) and [Dy(tmh) 3 (phenNO)] (3), have also been prepared for comparative purposes. In both cases, the Dy III center shows a NO 7 coordination sphere and SMM behavior is observed with U eff values of 71.5 K (2) and 120.7 K (3). In all three cases, ab initio calculations indicate that relaxation of the magnetization takes place mainly via the first excited-state Kramers doublet through Orbach, Raman, and thermally assisted quantum-tunnelling mechanisms. Pulse magnetization measurements reveal that the dinuclear and mononuclear complexes exhibit hysteresis loops with double- and single-step structures, respectively, thus supporting their SMM behavior.

Probing influence of rare earth ions (Er3+, Dy3+ and Gd3+) on structural, magnetic and optical properties of magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Jain, Richa; Luthra, Vandna; Gokhale, Shubha

2018-06-01

Fe3-xRExO4 (RE = Er, Dy and Gd) nanoparticles with x varying from 0 to 0.1 were synthesized using co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and UV-Vis spectroscopy techniques. TEM images reveal round shaped particles of ∼8-14 nm diameter in case of undoped magnetite (Fe3O4) nanoparticles whereas there is evolution of rod like structures by the doping of RE ions with aspect ratio in the range of 6-16. The room temperature saturation magnetization (Ms) values show gradual increase with doping till a critical doping level which is found to depend on the ionic radius of dopant ion (x = 0.01 for Er, 0.03 for Dy and 0.04 for Gd). There is a variation in the maximum value of saturation magnetization which is directly proportional to the number of unpaired 4f electrons in the dopant element. Low temperature magnetization study, carried out at 5 K and 120 K reveal an increase in the value of Ms as well as coercivity. The direct bandgaps calculated from UV-Visible data are found to decrease with increasing number of unpaired electrons in the dopant ions.

Synthesis and characterization of white light-emitting Dy3+-doped Gd2O3 nanophosphors

NASA Astrophysics Data System (ADS)

Nambram, S.; Singh, S. D.; Meetei, S. D.

2016-03-01

A series of Gd2O3 nanophosphors doped with different concentration of Dy3+ has been synthesized by chemical precipitation method. X-ray diffraction study of the undoped and doped samples suggests that Dy3+ atoms remain in the crystallite cubic lattice of the host. The particle sizes are in the range of 14-19 nm. Energy-dispersive analysis of X-ray spectroscopy study and Fourier transform infrared spectroscopy studies are also performed to analyze the elements present in the samples. Photoluminescence emission peak of Dy3+ in doped samples are observed at 487, 575 and 672 nm corresponding to the 4F9/2-6H15/2, 4F9/2-6H13/2 and 4F9/2-6H11/2 transition, respectively. Effective energy transfer from Gd3+ to Dy3+ is observed, yielding efficient emission under UV excitation. The maximum emission intensity is found at 1.5 at.% Dy3+-doped Gd2O3 sample. The enhancement in the emission intensity with the increase in Dy3+ is due to the increase in energy transfer from Gd3+ of host to Dy3+ ions. The CIE ( Commission Internationale de l'é clairage) coordinates of the doped samples are found to be very close to that of standard white color (0.33, 0.33).

Structural and magnetic properties of two branches of the tripod-kagome-lattice family A2R3Sb3O14 (A = Mg, Zn; R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb)

NASA Astrophysics Data System (ADS)

Dun, Z. L.; Trinh, J.; Lee, M.; Choi, E. S.; Li, K.; Hu, Y. F.; Wang, Y. X.; Blanc, N.; Ramirez, A. P.; Zhou, H. D.

2017-03-01

We present a systematic study of the structural and magnetic properties of two branches of the rare-earth tripod-kagome-lattice (TKL) family A2R3Sb3O14 (A = Mg, Zn; R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb; here, we use abbreviation A-R, as in MgPr for Mg2Pr3Sb3O14 ), which complements our previously reported work on MgDy, MgGd, and MgEr [Z. L. Dun et al., Phys. Rev. Lett. 116, 157201 (2016), 10.1103/PhysRevLett.116.157201]. The present susceptibility (χdc, χac) and specific-heat measurements reveal various magnetic ground states, including the nonmagnetic singlet state for MgPr, ZnPr; long-range orderings (LROs) for MgGd, ZnGd, MgNd, ZnNd, and MgYb; a long-range magnetic charge ordered state for MgDy, ZnDy, and potentially for MgHo; possible spin-glass states for ZnEr, ZnHo; the absence of spin ordering down to 80 mK for MgEr, MgTb, ZnTb, and ZnYb compounds. The ground states observed here bear both similarities as well as striking differences from the states found in the parent pyrochlore systems. In particular, while the TKLs display a greater tendency towards LRO, the lack of LRO in MgHo, MgTb, and ZnTb can be viewed from the standpoint of a balance among spin-spin interactions, anisotropies, and non-Kramers nature of single-ion state. While substituting Zn for Mg changes the chemical pressure, and subtly modifies the interaction energies for compounds with larger R ions, this substitution introduces structural disorder and modifies the ground states for compounds with smaller R ions (Ho, Er, Yb).

Features of proteolytic properties of tetraphenylporphyrin complex with lanthanide group metals

NASA Astrophysics Data System (ADS)

Tobolkina, Elena A.; Skripnikova, Tatiana A.; Starikova, Anna A.; Shumilova, Galina I.; Pendin, Andrey A.

2018-01-01

Demetallation of metalloporphyrin molecules is one of the essential degradation reactions in photosynthesis. The effect of metalloporphyrin nature on removal of central metals from tetraphenylporphyrin complexes based on lanthanide group metals (Dy, Er, Lu, Ho) has been studied. pH values, at which the metal ions leave the metalloporphyrin complex were established using two-phase spectrophotometric titration with potentiometric pH-control. The pH values decrease with the increase of atomic numbers of lanthanide groups, as well as with increase of 4f-electrons. The reaction of an extra ligand exchange for the hydroxide ion was studied. For Dy-, Er- and Ho-tetraphenylporphyrin complexes one particle of extra ligand coordinates with one porphyrin complex. A complex with dimeric particles can be formed for the system of Lu-tetraphenylporphyrin. Constants of the ion exchange reactions were calculated.

Biosynthesised ZnO : Dy3+ nanoparticles: Biodiesel properties and reusable catalyst for N-formylation of aromatic amines with formic acid

NASA Astrophysics Data System (ADS)

Reddy Yadav, L. S.; Raghavendra, M.; Sudheer Kumar, K. H.; Dhananjaya, N.; Nagaraju, G.

2018-04-01

ZnO nanoparticles doped with trivalent dysprosium ions (Dy3+) were prepared through the green combustion technique using E. tirucalli plant latex as a fuel. The fundamental and optical properties of the samples are examined via the X-ray diffraction, FTIR, UV-visible analytical methods and morphology by scanning electron microscope and transmission electron microscope. Rietveld refinement results show that the ZnO : Dy3+ were crystallized in the wurtzite hexagonal structure with space group P63mc (No. 186). The average particle size of ZnO : Dy3+ prepared with the different concentration of latex was found to be in the range 30-38nm, which is also confirmed by TEM analysis. A rapid and convenient method for the one-pot preparation of N-formamide derivatives aromatic amines and amino acid esters has been developed using Dy3+ doped ZnO as a catalytic agent. This method provides an efficient and much improved modification over reported protocols regarding yield, clean and work-up procedure milder reaction conditions. In this work, Pongamiapinnata oil was recycled for the preparation of biodiesel via Dy3+ doped ZnO as a catalytic agent.

Magnetic Properties and Magnetic Phase Diagrams of Trigonal DyNi3Ga9

NASA Astrophysics Data System (ADS)

Ninomiya, Hiroki; Matsumoto, Yuji; Nakamura, Shota; Kono, Yohei; Kittaka, Shunichiro; Sakakibara, Toshiro; Inoue, Katsuya; Ohara, Shigeo

2017-12-01

We report the crystal structure, magnetic properties, and magnetic phase diagrams of single crystalline DyNi3Ga9 studied using X-ray diffraction, electrical resistivity, specific heat, and magnetization measurements. DyNi3Ga9 crystallizes in the chiral structure with space group R32. The dysprosium ions, which are responsible for the magnetism in this compound, form a two-dimensional honeycomb structure on a (0001) plane. We show that DyNi3Ga9 exhibits successive phase transitions at TN = 10 K and T'N = 9 K. The former suggests quadrupolar ordering, and the latter is attributed to the antiferromagnetic order. It is considered that DyNi3Ga9 forms the canted-antiferromagnetic structure below T'N owing to a small hysteresis loop of the low-field magnetization curve. We observe the strong easy-plane anisotropy, and the multiple-metamagnetic transitions with magnetization-plateaus under the field applied along the honeycomb plane. For Hallel [2\\bar{1}\\bar{1}0], the plateau-region arises every 1/6 for saturation magnetization. The magnetic phase diagrams of DyNi3Ga9 are determined for the fields along principal-crystal axes.

Carbon ions irradiation on nano- and microcrystalline CaSO4 : Dy

NASA Astrophysics Data System (ADS)

Salah, Numan

2008-08-01

Nanoparticles of CaSO4 : Dy phosphor with a particle size of around 30 nm have been prepared by the chemical co-precipitation technique. Pellet samples of the nanomaterials were irradiated by a 75 MeV C6+ ion beam at the fluence range 1 × 109-1 × 1013 ions cm-2. Thermoluminescence (TL) glow curves of the irradiated samples were recorded and studied. The microcrystalline form of this sample is also included in the study with the aim of reporting a comparative measurement. The TL analysis shows that the glow curve of the nanomaterial has two peaks at around 166 and 210 °C. These peaks are similar to those induced in the microcrystalline sample with a slight difference in their TL response. The second peak is more prominent in the case of the microcrystalline sample at low fluences, while the first one dominates in the nanostructured sample mainly at higher fluences. The TRIM code based on Monte Carlo simulation was also used for calculating some ion beam parameters. Dosimetric properties of the carbon ion beam irradiated materials show that the nanostructure material has excellent features such as a simple glow curve structure and a linear TL response over a wider range than the corresponding microcrystalline sample. These results show that the nanostructure form of CaSO4 : Dy might be useful for detecting the high doses of carbon ions used in radiotherapy. Thermal analysis of the prepared nano- and microcrystalline materials was also done in the range 50-500 °C using thermogravimetry analysis and differential thermal analysis. No phase transitions within this range of heating for both the materials are observed.

Construction of three lanthanide metal-organic frameworks: Synthesis, structure, magnetic properties and highly selective sensing of metal ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiu-Mei, E-mail: zhangxiumeilb@126.com; Li, Peng; Gao, Wei

Three lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TZI)(H{sub 2}O){sub 4}]·3H{sub 2}O (Ln=Gd (1) and Tb (2) and Dy (3), H{sub 3}TZI=5-(1H-tetrazol-5-yl)isophthalic acid), have been synthesized under hydrothermal conditions. Single crystal X-ray diffraction reveals that 1–3 are isostructural and display a 1D double chain based on dinuclear motifs with (μ-COO){sub 2} double bridges. Magnetic studies indicate antiferromagnetic interactions in 1, ferromagnetic interactions in 2 and 3. Furthermore, compound 3 displays a slow relaxation behavior. Compound 2 exhibits intense characteristic green emission of Tb(III) ions in the solid state, which can be observed by the naked eye under UV light. Interestingly, 2 can selectivelymore » sense Pb{sup 2+} and Fe{sup 3+} ions through luminescence enhancement and quenching, respectively. The luminescence quenching mechanisms have been investigated in detail. The study on luminescence Ln-MOFs as a probe for sensing Pb{sup 2+} and Fe{sup 3+} ions is exceedingly rare example. - Graphical abstract: Three Ln-MOFs were successfully synthesized using a 5-(1H-tetrazol-5-yl)isophthalic acid ligand. They displays different magnetic behavior. Especially, the Dy(III) compound slow relaxation behavior. Interestingly, the Tb(III) compound can selectively sense Pb{sup 2+} and Fe{sup 3+} ions through luminescence enhancement and quenching, respectively. - Highlights: • Three Ln-MOFs with tetrazolate dicarboxylate ligand. • Dy(III) compound displays slow relaxation behavior. • The Tb(III) compound shows highly selective luminescence sensing of the Fe{sup 3+} and Pb{sup 2+} ions.« less

THEORETICAL RESEARCH OF THE OPTICAL SPECTRA AND EPR PARAMETERS FOR Cs2NaYCl6:Dy3+ CRYSTAL

NASA Astrophysics Data System (ADS)

Dong, Hui-Ning; Dong, Meng-Ran; Li, Jin-Jin; Li, Deng-Feng; Zhang, Yi

2013-09-01

The calculated EPR parameters are in reasonable agreement with the observed values. The important material Cs2NaYCl6 doped with rare earth ions have received much attention because of its excellent optical and magnetic properties. Based on the superposition model, in this paper the crystal field energy levels, the electron paramagnetic resonance parameters g factors of Dy3+ and hyperfine structure constants of 161Dy3+ and 163Dy3+ isotopes in Cs2NaYCl6 crystal are studied by diagonalizing the 42 × 42 energy matrix. In the calculations, the contributions of various admixtures and interactions such as the J-mixing, the mixtures among the states with the same J-value, and the covalence are all considered. The calculated results are in reasonable agreement with the observed values. The results are discussed.

Spontaneous structural distortion of the metallic Shastry-Sutherland system Dy B4 by quadrupole-spin-lattice coupling

NASA Astrophysics Data System (ADS)

Sim, Hasung; Lee, Seongsu; Hong, Kun-Pyo; Jeong, Jaehong; Zhang, J. R.; Kamiyama, T.; Adroja, D. T.; Murray, C. A.; Thompson, S. P.; Iga, F.; Ji, S.; Khomskii, D.; Park, Je-Geun

2016-11-01

Dy B4 has a two-dimensional Shastry-Sutherland (Sh-S) lattice with strong Ising character of the Dy ions. Despite the intrinsic frustrations, it undergoes two successive transitions: a magnetic ordering at TN=20 K and a quadrupole ordering at TQ=12.5 K . From high-resolution neutron and synchrotron x-ray powder diffraction studies, we have obtained full structural information on this material in all phases and demonstrate that structural modifications occurring at quadrupolar transition lead to the lifting of frustrations inherent in the Sh-S model. Our paper thus provides a complete experimental picture of how the intrinsic frustration of the Sh-S lattice can be lifted by the coupling to quadrupole moments. We show that two other factors, i.e., strong spin-orbit coupling and long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in metallic Dy B4 , play an important role in this behavior.

Bridgman growth and luminescence properties of dysprosium doped lead potassium niobate crystal

NASA Astrophysics Data System (ADS)

Liu, Wenbin; Tian, Tian; Yang, Bobo; Xu, Jiayue; Liu, Hongde

2017-06-01

Dy-doped lead potassium niobate (Pb2KNb5O15, PKN) single crystal was grown by the modified vertical Bridgman method through spontaneous nucleation. The crystal was brownish, transparent and inclusion free. Five excitation peaks of Dy3+ ions were clearly seen from near ultraviolet region to blue range. It was unique that the excitation peaks in blue range were more intense, especially the one centered at 455 nm. The emission bands consisted of blue, yellow and red emissions, which were at about 487 nm, 573 nm and 662 nm respectively. The CIE chromaticity diagram of PKN:Dy indicated that white light and yellow light could be emitted when the crystal was excited under near ultraviolet light and blue light, respectively. Thus PKN:Dy crystal is a candidate material whose emitting light could be tunable through changing the excited light wavelength.

Spectroscopy and energy transfer in lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3)(+)-Eu(3+) ions.

PubMed

Pisarska, Joanna; Kos, Agnieszka; Pisarski, Wojciech A

2014-08-14

Lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3+)-Eu(3+) were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to (5)D4→(7)F5 transition of Tb(3+) is observed under excitation of Dy(3+), whereas the main red emission band related to (5)D0→(7)F2 transition of Eu(3+) is successfully observed under direct excitation of Tb(3+). In both cases, the energy transfer processes from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) in lead borate glasses occur through a nonradiative processes with efficiencies up to 16% and 18%, respectively. The presence of energy transfer process was also confirmed by excitation spectra measurements. Copyright © 2014 Elsevier B.V. All rights reserved.

Spectral properties of Dy3+ doped ZnAl2O4 phosphor

NASA Astrophysics Data System (ADS)

Prakash, Ram; Kumar, Sandeep; Mahajan, Rubby; Khajuria, Pooja; Kumar, Vinay; Choudhary, R. J.; Phase, D. M.

2018-05-01

Herein, Dy3+ doped ZnAl2O4 phosphor was synthesized by the solution combustion method. The synthesized phosphor was characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The phase purity of the phosphor was confirmed by the XRD studies that showed cubic symmetry of the synthesized phosphor. Under UV excitation (388 nm) the PL emission spectrum of the phosphor shows characteristic transition from the Dy3+ ion. A band gap of 5.2 eV was estimated from the diffused reflectance spectroscopy. The surface properties of the phosphor were studied using the X-ray photoelectron spectroscopy.

Luminescence study of Dy or Ce activated LiCaBO3 phosphor for γ-ray and C5+ ion beam irradiation.

PubMed

Oza, Abha H; Dhoble, N S; Lochab, S P; Dhoble, S J

2015-11-01

The photoluminescence and thermoluminescence characteristics of rare earths (Dy or Ce) activated LiCaBO3 phosphors have been studied. Phosphors were synthesized by modified solid state synthesis. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescence studies. Dy(3+) activated LiCaBO3 shows emission at 486 and 577 nm due to (4) F9/2 →(6) H15/2 and (4) F9/2 → (6) H13/2 transition, respectively, whereas the PL emission spectra of Ce(3+) activated LiCaBO3 phosphor shows a broad band peaking at 432 nm, which is due to the transition from 5d level to the ground state of the Ce(3+) ion. The thermoluminescence study was also carried out for both these phosphors for γ-ray irradiation and carbon beam irradiation. Linearity was studied for a 0.4-3.1 Rad dose γ-rays. Linear behaviour over this dose range was observed. Gamma ray-irradiated phosphors were shown to be negligible fading upon storage. All the samples were also studied for 75 MeV C(5+) ion beam exposure in the range of 3.75 × 10(12) - 7.5 × 10(13) ion cm(-2) fluence. In addition to this, trapping parameters of all the samples were also calculated using Chen's peak shape method. Copyright © 2015 John Wiley & Sons, Ltd.

Luminescence and energy transfer properties of Ca2Ba3(PO4)3Cl and Ca2Ba3(PO4)3Cl:A (A = Eu2+/Ce3+/Dy3+/Tb3+) under UV and low-voltage electron beam excitation.

PubMed

Shang, Mengmeng; Geng, Dongling; Yang, Dongmei; Kang, Xiaojiao; Zhang, Yang; Lin, Jun

2013-03-18

Pure Ca2Ba3(PO4)3Cl and rare earth ion (Eu(2+)/Ce(3+)/Dy(3+)/Tb(3+)) doped Ca2Ba3(PO4)3Cl phosphors with the apatite structure have been prepared via a Pechini-type sol-gel process. X-ray diffraction (XRD) and structure refinement, photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, absolute quantum yield, as well as lifetimes were utilized to characterize samples. Under UV light excitation, the undoped Ca2Ba3(PO4)3Cl sample shows broad band photoluminescence centered near 480 nm after being reduced due to the defect structure. Eu(2+) and Ce(3+) ion doped Ca2Ba3(PO4)3Cl samples also show broad 5d → 4f transitions with cyan and blue colors and higher quantum yields (72% for Ca2Ba3(PO4)3Cl:0.04Eu(2+); 67% for Ca2Ba3(PO4)3Cl:0.016Ce(3+)). For Dy(3+) and Tb(3+) doped Ca2Ba3(PO4)3Cl samples, they give strong line emissions coming from 4f → 4f transitions. Moreover, the Ce(3+) ion can transfer its energy to the Tb(3+) ion in the Ca2Ba3(PO4)3Cl host, and the energy transfer mechanism has been demonstrated to be a resonant type, via a dipole-quadrupole interaction. However, under the low voltage electron beam excitation, Tb(3+) ion doped Ca2Ba3(PO4)3Cl samples present different luminescence properties compared with their PL spectra, which is ascribed to the different excitation mechanism. On the basis of the good PL and CL properties of the Ca2Ba3(PO4)3Cl:A (A = Ce(3+)/Eu(2+)/Tb(3+)/Dy(3+)), Ca2Ba3(PO4)3Cl might be promising for application in solid state lighting and field-emission displays.

Electronic structure and magnetic properties of Dy adatom on Ir surface

NASA Astrophysics Data System (ADS)

Shick, A. B.; Lichtenstein, A. I.

2018-05-01

The electronic structure and magnetism of individual Dy atom adsorbed on the (1 1 1) surface of Ir is investigated using the combination of the density functional theory with the Hubbard-I approximation to the Anderson impurity model (DFT + HIA). The Dy3+ adatom is found magnetic with the magnetic moment of 9.35μB in the external magnetic field. The spin and orbital magnetic moments, and their ratio are evaluated, and compared with the X-ray magnetic circular dichroism data. The positive magnetic anisotropy energy of ≈ 1.3 meV determines the out-of-plane orientation of the Dy adatom magnetic moment. The role of 5d-4f interorbital exchange polarization in modification of the 4f shell energy spectrum is emphasized. We predict the Dy magnetization to drop by the factor of three with switching off the external magnetic field.

Bi3+ sensitized Y2WO6:Ln3+ (Ln=Dy, Eu, and Sm) phosphors for solar spectral conversion.

PubMed

Huang, M N; Ma, Y Y; Xiao, F; Zhang, Q Y

2014-01-01

The phosphors of Y2WO6:Bi3+, Ln3+ (Ln=Dy, Eu and Sm) were synthesized by solid-state reaction in this study. The crystal structure, photoluminescence properties and energy transfer mechanism were investigated. By introducing Bi3+ ions, the excitation band of the phosphors was broadened to be 250-380 nm, which could be absorbed by the dye-sensitized solar cells (DSSCs). The overlap between excitation of W-O groups/Bi3+ and the emission of Ln3+ (Dy, Eu, and Sm) indicated that the probability of energy transfer from W-O groups and Bi3+ to Ln3+. The energy transfer efficiency from Bi3+ to Ln3+ (Ln=Dy, Eu and Sm) are calculated to be 16%, 20% and 58%. This work suggested that Y2WO6:Bi3+, Ln3+ (Ln=Dy, Eu and Sm) might be a promising ultraviolet-absorbing luminescent converter to enhance the photoelectrical conversion efficiency of dye-sensitized solar cells (DSSCs). Copyright © 2013 Elsevier B.V. All rights reserved.

Laser Materials Search and Characterization

DTIC Science & Technology

2014-05-30

AgBr doped with dysprosium ions are obtained by extrusion, and their optical and spectral properties are studied. Task 3. Waveguides based on LiF...fluoride are obtained by extrusion for the first time. Task 4. Spectroscopic properties of Dy3+ ions in chalcogenide crystals and fibers are studied...Task 5. Crystals and ceramics doped with rare-earth ions , as well as glasses and crystals doped with bismuth ions , are synthesized. Their

GeS2–In2S3–CsI Chalcogenide Glasses Doped with Rare Earth Ions for Near- and Mid-IR Luminescence

PubMed Central

Li, Legang; Bian, Junyi; Jiao, Qing; Liu, Zijun; Dai, Shixun; Lin, Changgui

2016-01-01

Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm3+, Er3+, and Dy3+) doped 65GeS2–25In2S3–10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm3+, Er3+, and Dy3+ ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions. PMID:27869231

Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji

2014-08-15

Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900more » K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.« less

Influence of rare earth ion doping (Ce and Dy) on electrical and magnetic properties of cobalt ferrites

NASA Astrophysics Data System (ADS)

Hashim, Mohd.; Raghasudha, M.; Meena, Sher Singh; Shah, Jyoti; Shirsath, Sagar E.; Kumar, Shalendra; Ravinder, D.; Bhatt, Pramod; Alimuddin; Kumar, Ravi; Kotnala, R. K.

2018-03-01

Ce and Dy substituted Cobalt ferrites with the chemical composition CoCexDyxFe2-2xO4 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) were synthesized through the chemical route, citrate-gel auto-combustion method. The structural characterization was carried out with the help of XRD Rieveld analysis, SEM and EDAX analysis. Formation of spinel cubic structure of the ferrites was confirmed by XRD analysis. SEM and EDAX results show that the particles are homogeneous with slight agglomeration without any impurity pickup. The effect of RE ion doping (Ce and Dy) on the dielectric, magnetic and impedance studies was systematically investigated by LCR meter, Vibrating Sample Magnetometer and Impedance analyzer respectively at room temperature in the frequency range of 10 Hz-10 MHz. Various dielectric parameters viz., dielectric constant, dielectric loss and ac conductivity were measured. The dielectric constant of all the ferrite compositions shows normal dielectric dispersion of ferrites with frequency. Impedance analysis confirms that the conduction in present ferrites is majorly due to the grain boundary mechanism. Ferrite sample with x = 0.03 show high dielectric constant, low dielectric loss and hence can be utilized in high frequency electromagnetic devices. Magnetization measurements indicate that with increase in Ce and Dy content in cobalt ferrites, the magnetization values decreased and coercivity has increased.

Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

PubMed

Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

2013-03-04

Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

NASA Astrophysics Data System (ADS)

Sahu, Ishwar Prasad; Bisen, D. P.; Brahme, N.; Tamrakar, Raunak Kumar

2016-04-01

A single-host lattice, white light-emitting SrAl2O4:Dy3+ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl2O4:Dy3+ phosphor was in a monoclinic phase with space group P21. The chemical composition of the sintered SrAl2O4:Dy3+ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy3+ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 →&!nbsp; 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+ ions. Commission International de I'Eclairage color coordinates of SrAl2O4:Dy3+ are suitable for white light-emitting phosphor. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl2O4:Dy3+ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl2O4:Dy3+ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl2O4:Dy3+ phosphor was useful for the white light-emitting diodes and stress sensor respectively.

Dy:Eu doped CaBAl glasses for white light applications

NASA Astrophysics Data System (ADS)

Lodi, T. A.; Sandrini, M.; Medina, A. N.; Barboza, M. J.; Pedrochi, F.; Steimacher, A.

2018-02-01

The combination of Eu3+ and Dy3+ in co-doped glassy materials provides interesting applicability for white light emission devices. In this work, Dy:Eu doped Calcium Boroaluminate (CaBAl) glasses were prepared by conventional melting quenching, with 3 wt% of Dy2O3 and Eu2O3 content varying from 0 to 3 wt%, and results of absorption spectra, photoluminescence and photoluminescence lifetime are discussed in terms of Eu2O3 content. The photoluminescence of the samples was studied under excitation of 365 and 405 nm light source. The 365 nm excitation shows favor to the Dy3+ ion emission. The results of photoluminescence lifetime at 575 nm (Dy3+) shows a decrease due to Eu2O3 addition, which suggests an energy transfer from Dy3+ (donor) to the Eu3+ (acceptor). On the other hand, under excitation of 405 nm, the photoluminescence lifetime at 575 nm (Dy3+) shows no significant changes due to Eu2O3 amount, which indicates that the energy transfer from Dy3+ to Eu3+ (under λexc = 405 nm) is negligible. However, the results of photoluminescence under 405 nm excitation present a white yellowish emission in the CIE diagram, which shifts to red with Eu2O3 addition. The combination of a Blue LED (BL) emission with the emission of the samples was also studied in the CIE diagram, in order to improve light emission and to obtain ideal White Light (WL). The results show that by modifying the emission intensity of BL, it is possible to achieve a route for smart lighting, close to the circadian light cycle.

Synthesis, crystal structure, optical and thermal properties of lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho).

PubMed

Förg, Katharina; Höppe, Henning A

2015-11-28

Lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho) were synthesised as colourless (Ln = Tb, Dy) and light pink (Ln = Ho) crystalline powders by reaction of Tb4O7/Dy2O3/Ho2O3 with H3PO3 at 380 °C. All compounds crystallise isotypically (P2(1)/c (no. 14), Z = 4, a(Tb) = 1368.24(4) pm, b(Tb) = 710.42(2) pm, c(Tb) = 965.79(3) pm, β(Tb) = 101.200(1)°, 3112 data, 160 parameters, wR2 = 0.062, a(Ho) = 1363.34(5) pm, b(Ho) = 709.24(3) pm, c(Ho) = 959.07(4) pm, β(Ho) = 101.055(1)°, 1607 data, 158 parameters, wR2 = 0.058). The crystal structure comprises two different infinite helical chains of corner-sharing phosphate tetrahedra. In-between these chains the lanthanide ions are located, coordinated by seven oxygen atoms belonging to four different polyphosphate chains. Vibrational, UV/Vis and fluorescence spectra of Ln[H(PO3)4] (Ln = Tb, Dy, Ho) as well as Dy[H(PO3)4]:Ln (Ln = Ce, Eu) and the magnetic and thermal behaviour of Tb[H(PO3)4] are reported.

White Light Emitting MZr4(PO4)6:Dy3+ (M = Ca, Sr, Ba) Phosphors for WLEDs.

PubMed

Nair, Govind B; Dhoble, S J

2017-03-01

A series of MZr 4 (PO 4 ) 6 :Dy 3+ (M = Ca, Sr, Ba) phosphors were prepared by the solid state diffusion method. Confirmation of the phase formation and morphological studies were performed by X-ray powder diffraction (XRD) measurements and scanning electron microscopy, respectively. Photoluminescence (PL) properties of these phosphors were thoroughly analyzed and the characteristic emissions of Dy 3+ ions were found to arise from them at an excitation wavelength of 351 nm. The PL emission spectra of the three phosphors were analyzed and compared. The CIE chromaticity coordinates assured that the phosphors produced cool white-light emission and hence, they are potential candidates for UV excited white-LEDs (WLEDs). Graphical Abstract ᅟ.

Structural, thermal and optical investigations of Dy3+ ions doped lead containing lithium fluoroborate glasses for simulation of white light

NASA Astrophysics Data System (ADS)

Zulfiqar Ali Ahamed, Sd.; Madhukar Reddy, C.; Deva Prasad Raju, B.

2013-05-01

Lead containing barium zinc lithium fluoroborate (LBZLFB) glasses doped with different concentrations of trivalent dysprosium ions were synthesized by conventional melt quenching method and characterized through the XRD, DSC, FTIR, FT-Raman, optical absorption, photoluminescence and decay curve analysis. X-ray diffraction studies revealed amorphous nature of the studied glass matrices. The thermal behavior has been reported by recording DSC thermograms. Coexistence of trigonal BO3 and tetrahedral BO4 units was evidenced by IR and Raman spectroscopy. Judd-Ofelt intensity parameters have been evaluated for 1.0 mol% Dy3+ ions doped LBZLFB glass. The measuring branching ratios are reasonably high for transitions 4F9/2 → 6H15/2 and 6H13/2 suggesting that the emission at 486 and 577 nm, respectively can give rise to lasing action in the visible region. From the visible emission spectra, the yellow to blue (Y/B) intensity ratios and chromaticity color coordinates were estimated. A combination of blue and yellow emissions has emerged in the glasses, which allows the observation of white light when the glasses are excited by the ultraviolet/blue light. These Dy3+ doped glasses are studied for their utility for white light generation under 454 nm excitation and the present LBZLFB glass is more suitable for generation of white light for blue LED chips.

Host-sensitized luminescence properties in CaNb2O6:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) phosphors with abundant colors.

PubMed

Li, Kai; Liu, Xiaoming; Zhang, Yang; Li, Xuejiao; Lian, Hongzhou; Lin, Jun

2015-01-05

A series of Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) ion doped CaNb2O6 (CNO) phosphors have been prepared via the conventional high-temperature solid-state reaction route. The X-ray diffraction (XRD) and structure refinement, diffuse reflection, photoluminescence (PL), and fluorescent decay curves were used to characterize the as-prepared samples. Under UV radiation, the CNO host present a broad emission band from about 355 to 605 nm centered around 460 nm originating from the NbO6 octahedral groups, which has spectral overlaps with the excitation of f-f transitions of Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) samples. They show both host emission and respective emission lines derived from the characteristic f-f transitions of activators, which present different emission colors owing to the energy transfer from the NbO6 group in the host to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) with increasing activator concentrations. The decreases of decay lifetimes of host emissions in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) demonstrate the energy transfer from the hosts to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+). The energy transfer mechanisms in CNO:Eu(3+)/Tb(3+)/Dy(3+) phosphors have been determined to be a resonant type via dipole-dipole mechanisms. For CNO:Sm(3+), the metal-metal charge transfer transition (MMCT) might contribute to the different variations of decay lifetimes and emission intensity from CNO:Eu(3+)/Tb(3+)/Dy(3+) samples. The best quantum efficiency is 71.2% for CNO:0.01/0.02Dy(3+). The PL properties of as-prepared materials indicate the promising application in UV-pumped white-emitting lighting diodes field.

Emission analysis of RE3+ (RE = Sm, Dy):B2O3-TeO2-Li2O-AlF3 glasses.

PubMed

Raju, C Nageswara; Sailaja, S; Kumari, S Pavan; Dhoble, S J; Kumar, V Ramesh; Ramanaiah, M V; Reddy, B Sudhakar

2013-01-01

This article reports on the optical properties of 0.5% mol of Sm(3+), Dy(3+) ion-doped B2O3-TeO2-Li2O-AlF3 (LiAlFBT) glasses. The glass samples were characterized by optical absorption and emission spectra. Judd-Ofelt theory was applied to analyze the optical absorption spectra and calculate the intensity parameters and radiative properties of the emission transitions. The emission spectra of Sm(3+) and Dy(3+):LiAlFBT glasses showed a bright reddish-orange emission at 598 nm ((4)G5/2 → (6)H7/2) and an intense yellow emission at 574 nm ((4)F9/2 → (6)H13/2), respectively. Full width at half maximum (FWHM), stimulated emission cross section, gain bandwidth and optical gain values were also calculated to extend the applications of the Sm(3+) and Dy(3+):LiAlFBT glasses. Copyright © 2012 John Wiley & Sons, Ltd.

Nonlinear optical properties and excited state dynamics of sandwich-type mixed (phthalocyaninato)(Schiff-base) triple-decker complexes: Effect of rare earth atom

NASA Astrophysics Data System (ADS)

Li, Zhongguo; Gao, Feng; Xiao, Zhengguo; Wu, Xingzhi; Zuo, Jinglin; Song, Yinglin

2018-07-01

The third-order nonlinear optical properties of two di-lanthanide (Ln = Tb and Dy) sandwich complexes with mixed phthalocyanine and Schiff-base ligands were studied using Z-scan technique at 532 nm with 20 ps and 4 ns pulses. Both complexes exhibit reverse saturable absorption and self-focusing effect in ps regime, while the second-order hyperpolarizability decreases from Dy to Tb. Interestingly, the Tb triple-decker complexes show larger nonlinear absorption than Dy complexes on ns timescale. The time-resolved pump-probe measurements demonstrate that the nonlinear optical response was caused by excited-state mechanism related to the five-level model, while the singlet state lifetime of Dy complexes is 3 times shorter than that of Tb complexes. Our results indicate the lanthanide ions play a critical role in the photo-physical properties of triple-decker phthalocyanine complexes for their application as optical limiting materials.

Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

PubMed

Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

2013-11-04

Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those of Zn(II)2Dy(III)2 were not detected. The fine structure assignable to the (5)D4 → (7)F6 transition of ZnTb1 and ZnTb2 is in good accord with the energy pattern from the magnetic analysis. The Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) showed an out-of-phase signal with frequency-dependence in alternating current susceptibility, indicative of single molecule magnet. Under a dc bias field of 1000 Oe, the signals become significantly more intense and the energy barrier, Δ/kB, for the magnetic relaxation was estimated from the Arrhenius plot to be 39(1) and 42(8) K for ZnTb1 and ZnTb2, and 52(2) and 67(2) K for ZnDy1 and ZnDy2, respectively.

Crystal structure and partial Ising-like magnetic ordering of orthorhombic D y 2 Ti O 5

DOE PAGES

Shamblin, Jacob; Calder, Stuart; Dun, Zhiling; ...

2016-07-12

The structure and magnetic properties of orthorhombic Dy 2TiO 5 have been investigated using x-ray diffraction, neutron diffraction, and alternating current (ac)/direct current (dc) magnetic susceptibility measurements. In this paper, we report a continuous structural distortion below 100 K characterized by negative thermal expansion in the [0 1 0] direction. Neutron diffraction and magnetic susceptibility measurements revealed that two-dimensional (2D) magnetic ordering begins at 3.1 K, which is followed by a three-dimensional magnetic transition at 1.7 K. The magnetic structure has been solved through a representational analysis approach and can be indexed with the propagation vector k = [0 1/2more » 0]. The spin structure corresponds to a coplanar model of interwoven 2D “sheets” extending in the [0 1 0] direction. The local crystal field is different for each Dy 3+ ion (Dy1 and Dy2), one of which possesses strong uniaxial symmetry indicative of Ising-like magnetic ordering. In conclusion, consequently, two succeeding transitions under magnetic field are observed in the ac susceptibility, which are associated with flipping each Dy 3+ spin independently.« less

Structural and luminescence studies on Dy3+ doped lead boro-telluro-phosphate glasses

NASA Astrophysics Data System (ADS)

Selvi, S.; Venkataiah, G.; Arunkumar, S.; Muralidharan, G.; Marimuthu, K.

2014-12-01

This paper reports results obtained on the structural and luminescence properties of Dy3+doped lead boro-telluro-phosphate glasses prepared following the melt quenching technique. FTIR spectra exhibit the presence of B-O vibrations, P-O-P symmetric vibrations and Te-O stretching modes of TeO3 and TeO6 units. The metal-ligand bond was identified through UV-vis-NIR absorption spectra and to determine the band tailing parameter, direct and indirect band gap energy of the prepared glasses. The Judd-Ofelt (JO) intensity parameters (Ω2, Ω4 and Ω6), experimental and theoretical oscillator strengths were also determined and reported. Luminescence measurements were made to determine the transition probability (A), stimulated emission cross-section (σPE) and branching ratio (βR) for the transitions that include 4F9/2→6H11/2, 6H13/2 and 6H15/2 bands. The effect of Dy3+ ion concentration on the intensity ratio of yellow to blue emission bands has also been studied and reported. The lifetime corresponding to the 4F9/2 level of the title glasses has been found to decrease with the increase in Dy3+ ion concentration. The chromaticity coordinates (x,y) have been estimated from the luminescence spectra and the suitability of title glasses for white light applications has been analyzed using CIE chromaticity diagram. The variation of optical properties with the concentration of dysprosium oxide content in the glasses have been studied and reported.

Structural and luminescence properties of Dy3+ doped bismuth phosphate glasses for greenish yellow light applications

NASA Astrophysics Data System (ADS)

Damodaraiah, S.; Reddy Prasad, V.; Babu, S.; Ratnakaram, Y. C.

2017-05-01

Different compositions of (5, 10, 15 and 20 mol%) of bismuth and different concentrations (0.5, 1.0, 1.5 and 2.0 mol%) of Dy3+ ion doped bismuth phosphate (BiP) glasses were synthesized by melt-quenching technique. The structural characterization was accomplished by XRD, SEM with EDS, FTIR, FT-Raman and 31P MAS NMR spectroscopy. The optical properties were studied using absorption and photoluminescence spectroscopy. Different structural groups were identified using FTIR and FT-Raman spectra. The depolymerization of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups (Q1) revealed by 31P MAS NMR spectroscopic investigations. Judd-Ofelt intensity parameters Ωλ (λ = 2, 4 and 6) were evaluated from absorption spectra. Radiative parameters such as radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βR) were calculated using Judd-Ofelt intensity parameters. From photoluminescence spectra, experimental branching ratios (βexp) and stimulated emission cross-sections (σP) were calculated for all the observed emission transitions of prepared glasses. The decay profiles for 4F9/2 level were recorded and fit exponential for 0.5 mol% and non-exponential for higher concentrations of Dy3+ due to non-radiative energy transfer among excited Dy3+ ions. The CIE chromaticity co-ordinates have been calculated from the luminescence spectra which confirmed greenish yellow light emission.

Syntheses, crystal structures, and properties of six new lanthanide(III) transition metal tellurium(IV) oxyhalides with three types of structures.

PubMed

Shen, Yue-Ling; Mao, Jiang-Gao

2005-07-25

Solid-state reactions of lanthanide(III) oxide (and lanthanide(III) oxyhalide), transition metal halide (and transition metal oxide), and TeO(2) at high temperature lead to six new lanthanide transition metal tellurium(IV) oxyhalides with three different types of structures, namely, DyCuTe(2)O(6)Cl, ErCuTe(2)O(6)Cl, ErCuTe(2)O(6)Br, Sm(2)Mn(Te(5)O(13))Cl(2), Dy(2)Cu(Te(5)O(13))Br(2), and Nd(4)Cu(TeO(3))(5)Cl(3). Compounds DyCuTe(2)O(6)Cl, ErCuTe(2)O(6)Cl, and ErCuTe(2)O(6)Br are isostructural. The lanthanide(III) ion is eight-coordinated by eight oxygen atoms, and the copper(II) ion is five-coordinated by four oxygens and a halide anion in a distorted square pyramidal geometry. The interconnection of Ln(III) and Cu(II) ions by bridging tellurite anions results in a three-dimensional (3D) network with tunnels along the a-axis; the halide anion and the lone-pair electrons of the tellurium(IV) ions are oriented toward the cavities of the tunnels. Compounds Sm(2)Mn(Te(5)O(13))Cl(2) and Dy(2)Cu(Te(5)O(13))Br(2) are isostructural. The lanthanide(III) ions are eight-coordinated by eight oxygens, and the divalent transition metal ion is octahedrally coordinated by six oxygens. Two types of polymeric tellurium(IV) oxide anions are formed: Te(3)O(8)(4)(-) and Te(4)O(10)(4)(-). The interconnection of the lanthanide(III) and divalent transition metal ions by the above two types of polymeric tellurium(IV) oxide anions leads to a 3D network with long, narrow-shaped tunnels along the b-axis. The halide anions remain isolated and are located at the above tunnels. Nd(4)Cu(TeO(3))(5)Cl(3) features a different structure. All five of the Nd(III) ions are eight-coordinated (NdO(8) for Nd(1), Nd(2), Nd(4), and Nd(5) and NdO(7)Cl for Nd(3)), and the copper(I) ion is tetrahedrally coordinated by four chloride anions. The interconnection of Nd(III) ions by bridging tellurite anions resulted in a 3D network with large tunnels along the b-axis. The CuCl(4) tetrahedra are interconnected into a 1D two-unit repeating (zweier) chain via corner-sharing. These 1D copper(I) chloride chains are inserted into the tunnels of the neodymium(III) tellurite via Nd-Cl-Cu bridges. Luminescent studies show that ErCuTe(2)O(6)Cl and Nd(4)Cu(TeO(3))(5)Cl(3) exhibit strong luminescence in the near-IR region. Magnetic measurements indicate the antiferromagnetic interactions between magnetic centers in these compounds.

Field induced 4f5d [Re(salen)]2O3[Dy(hfac)3(H2O)]2 single molecule magnet.

PubMed

Pointillart, Fabrice; Bernot, K; Sessoli, R; Gatteschi, D

2010-05-03

The reaction between the mononuclear [ReO(salen)(OMe)] (salen(2-) = N,N'-ethan-1,2-diylbis(salicylidenamine) dianion) and Dy(hfac)(3).2H(2)O (hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate anion) complexes lead to the formation of a compound with the formula {[Re(salen)](2)O(3)[Dy(hfac)(3)(H(2)O)](2)}(CHCl(3))(2)(CH(2)Cl(2))(2) noted (Dy(2)Re(2)). This compound has been characterized by single crystal and powder X-ray diffraction and has been found isostructural to the Y(III) derivative (Y(2)Re(2)) that we previously reported. The cyclic voltammetry demonstrates the redox activity of the system. The characterization of both static and dynamic magnetic properties is reported. Static magnetic data has been analyzed after the cancellation of the crystal field contribution by two different methods. Weak ferromagnetic exchange interactions between the Dy(III) ions are highlighted. The compound Dy(2)Re(2) displays slow relaxation of the magnetization when an external magnetic field is applied. Alternating current susceptibility shows a thermally activated behavior with pre-exponential factors of 7.13 (+/-0.10) x 10(-6) and 5.76 (+/-0.27) x 10(-7) s, and energy barriers of 4.19 (+/-0.02) and 8.52 (+/-0.55) K respectively for low and high temperature regimes.

Two Series of Homodinuclear Lanthanide Complexes: Greatly Enhancing Energy Barriers through Tuning Terminal Solvent Ligands in Dy2 Single-Molecule Magnets.

PubMed

Qin, Yaru; Zhang, Haifeng; Sun, Hao; Pan, Yangdan; Ge, Yu; Li, Yahong; Zhang, Yi-Quan

2017-11-02

The utilization of 2-ethoxy-6-{[(2-hydroxy-3-methoxybenzyl)imino]methyl}phenol (H 2 L) as a chelating ligand, in combination with the employment of alcohols (EtOH and MeOH) as auxiliary ligands, in 4 f-metal chemistry afforded two series of dinuclear lanthanide complexes of compositions [Ln 2 L 2 (NO 3 ) 2 (EtOH) 2 ] (Ln=Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7)) and [Ln 2 L 2 (NO 3 ) 2 (MeOH) 2 ] (Ln=Sm (8), Eu (9), Gd (10), Tb (11), Dy (12), Ho (13), Er (14)). The structures of 1-14 were determined by single-crystal X-ray crystallography. Complexes 1-7 are isomorphous. The two lanthanide(III) ions in 1-7 are doubly bridged by two deprotonated aminophenoxide oxygen atoms of two μ 2 :η 0 :η 1 :η 2 :η 1 :η 1 :η 0 -L 2- ligands. One nitrogen atom, two oxygen atoms of the NO 3 - anion, two methoxide oxygen atoms of two ligand sets, and one oxygen atom of the terminally coordinated EtOH molecule complete the distorted dodecahedron geometry of each lanthanide(III) ion. Compounds 8-14 are isomorphous and their structures are similar to those of 1-7. The slight difference between 1-7 and 8-14 stems from purposefully replacing the EtOH ligands in 1-7 with MeOH in 8-14. Direct-current magnetic susceptibility studies in the 2-300 K range reveal weak antiferromagnetic interactions for 3, 4, 7, 10, 11, and 14, and ferromagnetic interactions at low temperature for 5, 6, 12, and 13. Complexes 5 and 12 exhibit single-molecule magnet (SMM) behavior with energy barriers of 131.3 K for 5 and 198.8 K for 12. The energy barrier is significantly enhanced by dexterously regulating the terminal ligands. To rationalize the observed difference in the magnetic behavior, complete-active-space self-consistent field (CASSCF) calculations were performed on two Dy 2 complexes. Subtle variation in the angle between the magnetic axes and the vector connecting two dysprosium(III) ions results in a weaker influence on the tunneling gap of individual dysprosium(III) ions by the dipolar field in 12. This work proposes an efficient strategy for synthesizing Dy 2 SMMs with high energy barriers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pressure dependence of the charge-density-wave and superconducting states in GdTe 3 ,   TbTe 3 , and DyTe 3

DOE PAGES

Zocco, D. A.; Hamlin, J. J.; Grube, K.; ...

2015-05-14

Here, we present electrical resistivity and ac-susceptibility measurements of GdTe 3, TbTe 3 and DyTe 3 performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of dT CW,1/dP~ –85K/GPa. For TbTe 3 and DyTe 3, a second CDW below T CDW,2 increases with pressure until it reaches the T CDW,1(P) line. For GdTe 3, the lower CDW emerges as pressure is increased above ~1GPa. As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on TbTe 3 provide compelling evidence for bulk SC in themore » low-pressure region of the phase diagram. We provide measurements of superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.« less

High-temperature thermoelectric properties of Ca0.92La0.04RE0.04MnO3 (RE = Sm, Dy and Yb) prepared by coprecipitation

NASA Astrophysics Data System (ADS)

Li, Cuiqin; Chen, Qianlin; Yan, Yunan; Li, Yanan; Zhao, Ying

2018-02-01

A series of Ca0.92La0.04RE0.04MnO3 (RE = Sm, Dy and Yb) compounds are synthesized via a coprecipitation technique. The influence of La/RE dual doping on the phase structure, microstructure and thermoelectric properties of the CaMnO3 system is investigated. Increased material density with grain sizes of 1-2 μm and a homogeneous microstructure is realized. Dual doping decreases the electrical resistivity due to an increase in the carrier concentration and also decreases the thermal conductivity due to increased grain scattering, damping of local vibrations by heavier La/RE ions compared to Ca and lattice distortion. The Ca0.92La0.04Yb0.04MnO3 shows the highest power factor of 3.49 × 10-4 W m-1 K-2 and the highest dimensionless figure of merit ZT of 0.25 at 770 K, which is approximately 3 times larger than that obtained for the undoped CaMnO3 and significantly larger than that of single-doped CaMnO3 prepared by solid-state reaction. This work provides a basic foundation for the industrial application of this thermoelectric material.

Magnetic Memory from Site Isolated Dy(III) on Silica Materials

PubMed Central

2017-01-01

Achieving magnetic remanence at single isolated metal sites dispersed at the surface of a solid matrix has been envisioned as a key step toward information storage and processing in the smallest unit of matter. Here, we show that isolated Dy(III) sites distributed at the surface of silica nanoparticles, prepared with a simple and scalable two-step process, show magnetic remanence and display a hysteresis loop open at liquid 4He temperature, in contrast to the molecular precursor which does not display any magnetic memory. This singular behavior is achieved through the controlled grafting of a tailored Dy(III) siloxide complex on partially dehydroxylated silica nanoparticles followed by thermal annealing. This approach allows control of the density and the structure of isolated, “bare” Dy(III) sites bound to the silica surface. During the process, all organic fragments are removed, leaving the surface as the sole ligand, promoting magnetic remanence. PMID:28386602

Magnetic memory from site isolated Dy(III) on silica materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allouche, Florian; Lapadula, Giuseppe; Siddiqi, Georges

Achieving magnetic remanence at single isolated metal sites dispersed at the surface of a solid matrix has been envisioned as a key step toward information storage and processing in the smallest unit of matter. Here, we show that isolated Dy(III) sites distributed at the surface of silica nanoparticles, prepared with a simple and scalable two-step process, show magnetic remanence and display a hysteresis loop open at liquid 4He temperature, in contrast to the molecular precursor which does not display any magnetic memory. This singular behavior is achieved through the controlled grafting of a tailored Dy(III) siloxide complex on partially dehydroxylatedmore » silica nanoparticles followed by thermal annealing. This approach allows control of the density and the structure of isolated, “bare” Dy(III) sites bound to the silica surface. Throughout the process, all organic fragments are removed, leaving the surface as the sole ligand, promoting magnetic remanence.« less

Magnetic memory from site isolated Dy(III) on silica materials

DOE PAGES

Allouche, Florian; Lapadula, Giuseppe; Siddiqi, Georges; ...

2017-02-22

Achieving magnetic remanence at single isolated metal sites dispersed at the surface of a solid matrix has been envisioned as a key step toward information storage and processing in the smallest unit of matter. Here, we show that isolated Dy(III) sites distributed at the surface of silica nanoparticles, prepared with a simple and scalable two-step process, show magnetic remanence and display a hysteresis loop open at liquid 4He temperature, in contrast to the molecular precursor which does not display any magnetic memory. This singular behavior is achieved through the controlled grafting of a tailored Dy(III) siloxide complex on partially dehydroxylatedmore » silica nanoparticles followed by thermal annealing. This approach allows control of the density and the structure of isolated, “bare” Dy(III) sites bound to the silica surface. Throughout the process, all organic fragments are removed, leaving the surface as the sole ligand, promoting magnetic remanence.« less

Direct observation of the discrete energy spectrum of two lanthanide-based single-chain magnets by far-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Haas, Sabrina; Heintze, Eric; Zapf, Sina; Gorshunov, Boris; Dressel, Martin; Bogani, Lapo

2014-05-01

The far-infrared optical transmission has been studied for two lanthanide-based single-chain magnets DyPhOPh and TbPhOPh in the frequency range between 3 and 80 cm-1. The spectra were acquired at temperatures between 2 and 80 K and magnetic fields up to 6 T. Based on their magnetic field dependence in DyPhOPh two of the observed absorption lines are identified as transitions inside the crystal field split Dy3+ ground multiplet 6H15/2, coupled to the neighboring spins. In TbPhOPh one transition was observed inside the crystal-field-split Tb3+ ground multiplet 7F6. The results allow a spectroscopic investigation of the role of single-ion anisotropy and exchange in Glauber dynamics.

Inelastic Neutron Scattering and Magnetisation Investigation of an Exchange-Coupled Dy2 SMM

NASA Astrophysics Data System (ADS)

Baker, Michael L.; Zhang, Qing; Sarachik, Myriam P.; Kent, Andrew D.; Chen, Yizhang; Butch, Nicholas; Pineda, Eufemio M.; McInnes, Eric

The strong spin orbit coupling and weak crystal field energies of simple exchange-coupled rare earth SMMs makes the precise evaluation of their magnetic properties nontrivial. Here we report a detailed investigation of the single molecule magnet hqH2Dy2(hq)4(NO3)3MeOH. Inelastic neutron scattering is used to obtain direct access to several low energy crystal field excitations. The INS results display several features that are not found in earlier FIR absorption experiments, while other features found in the latter are absent. Based on the effective point charge model, numerical calculations are currently underway to resolve these apparent discrepancies using complementary magnetisation measurements to resolve the exchange between Dy ions. Work supported by ARO W911NF-13-1-1025 (CCNY) and NSF-DMR-1309202 (NYU).

Magnetic Behavior of a Dy8 Molecular Nanomagnet

NASA Astrophysics Data System (ADS)

Zhang, Qing; Sarachik, Myriam; Baker, Michael; Chen, Yizhang; Kent, Andrew; Stamatatos, Theocharis

2015-03-01

As part of a study of quantum tunneling in a newly synthesized family of dysprosium-based molecular magnets that exhibit a chiral spin structure, we report initial investigations of the magnetic response of a Dy8 cluster with the formula (Et4N)4[Dy8O(nd)8(NO3)10(H2O)2] .2MeCN. The molecular complex contains triangular arrangements of exchange coupled Dy(III) ions. The compound forms an approximate snub-square Archimedean lattice unit. The measured magnetization of this network of four triangles suggests the presence of multiple spin chiral vortexes. Single crystal susceptibility and magnetization measurements indicate the presence of a hard-axis direction and an easy plane. These principal orientations have been investigated in magnetic fields up to 5 Tesla for temperatures between 1.8 and 100 K using a SQUID-based Quantum Design MPMS magnetometer. Complex easy plane magnetic hysteresis loops emerge at lower temperatures measured using Hall probe magnetometry at sub 1 K temperatures. The analysis of these measurements will be discussed and compared with results of theoretical calculations. Work supported by ARO W911NF-13-1-1025 (CCNY), NSF-DMR-1309202 (NYU); the synthesis of the Dy8 cluster was supported by NSERC (Discovery grant to Th.C.S.).

Dy{sup 3+}-doped Ga–Sb–S chalcogenide glasses for mid-infrared lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Mingjie; Yang, Anping, E-mail: apyang@jsnu.edu.cn; Peng, Yuefeng

2015-10-15

Highlights: • Novel Ga–Sb–S chalcogenide glasses doped with Dy{sup 3+} ions were synthesized. • The glasses show good thermal stability and excellent infrared transparency. • The glasses show low phonon energy and intense mid-infrared emissions. • The mid-infrared emissions have high quantum efficiency. • The mid-infrared emissions have large stimulated emission cross sections. - Abstract: Novel Ga–Sb–S chalcogenide glasses doped with different amount of Dy{sup 3+} ions were prepared. Their thermal stability, optical properties, and mid-infrared (MIR) emission properties were investigated. The glasses show good thermal stability, excellent infrared transparency, very low phonon energy (∼306 cm{sup −1}), and intense emissionsmore » centered at 2.95, 3.59, 4.17 and 4.40 μm. Three Judd–Ofelt intensity parameters (Ω{sub 2} = 8.51 × 10{sup −20} cm{sup 2}, Ω{sub 4} = 2.09 × 10{sup −20} cm{sup 2}, and Ω{sub 6} = 1.60 × 10{sup −20} cm{sup 2}) are obtained, and the related radiative transition properties are evaluated. The high quantum efficiencies and large stimulated emission cross sections of the MIR emissions (88.10% and 1.11 × 10{sup −20} cm{sup 2} for 2.95 μm emission, 75.90% and 0.38 × 10{sup −20} cm{sup 2} for 4.40 μm emission, respectively) in the Dy{sup 3+}-doped Ga–Sb–S glasses make them promising gain materials for the MIR lasers.« less

Layered Crystal Structure, Color-Tunable Photoluminescence, and Excellent Thermal Stability of MgIn2P4O14 Phosphate-Based Phosphors.

PubMed

Zhang, Jing; Cai, Ge-Mei; Yang, Lv-Wei; Ma, Zhi-Yuan; Jin, Zhan-Peng

2017-11-06

Single-component white phosphors stand a good chance to serve in the next-generation high-power white light-emitting diodes. Because of low thermal stability and containing lanthanide ions with reduced valence state, most of reported phosphors usually suffer unstable color of lighting for practical packaging and comparably complex synthetic processes. In this work, we present a type of novel color-tunable blue-white-yellow-emitting MgIn 2 P 4 O 14 :Tm 3+ /Dy 3+ phosphor with high thermal stability, which can be easily fabricated in air. Under UV excitation, the MgIn 2 P 4 O 14 :Tm 0.02 Dy 0.03 white phosphor exhibits negligible thermal-quenching behavior, with a 99.5% intensity retention at 150 °C, relative to its initial value at room temperature. The phosphor host MgIn 2 P 4 O 14 was synthesized and reported for the first time. MgIn 2 P 4 O 14 crystallizes in the space group of C2/c (No. 15) with a novel layered structure built of alternate anionic and cationic layers. Its disordering structure, with Mg and In atoms co-occupying the same site, is believed to facilitate the energy transfer between rare-earth ions and benefit by sustaining the luminescence with increasing temperature. The measured absolute quantum yields of MgIn 2 P 4 O 14 :Dy 0.04 , MgIn 2 P 4 O 14 :Tm 0.01 Dy 0.04 , and MgIn 2 P 4 O 14 :Tm 0.02 Dy 0.03 phosphors under the excitation of 351 nm ultraviolet radiation are 70.50%, 53.24%, and 52.31%, respectively. Present work indicates that the novel layered MgIn 2 P 4 O 14 is a promising candidate as a single-component white phosphor host with an excellent thermal stability for near-UV-excited white-light-emitting diodes (wLEDs).

Microscopic effects of Dy doping in the topological insulator Bi2Te3

NASA Astrophysics Data System (ADS)

Duffy, L. B.; Steinke, N.-J.; Krieger, J. A.; Figueroa, A. I.; Kummer, K.; Lancaster, T.; Giblin, S. R.; Pratt, F. L.; Blundell, S. J.; Prokscha, T.; Suter, A.; Langridge, S.; Strocov, V. N.; Salman, Z.; van der Laan, G.; Hesjedal, T.

2018-05-01

Magnetic doping with transition metal ions is the most widely used approach to break time-reversal symmetry in a topological insulator (TI)—a prerequisite for unlocking the TI's exotic potential. Recently, we reported the doping of Bi2Te3 thin films with rare-earth ions, which, owing to their large magnetic moments, promise commensurately large magnetic gap openings in the topological surface states. However, only when doping with Dy has a sizable gap been observed in angle-resolved photoemission spectroscopy, which persists up to room temperature. Although disorder alone could be ruled out as a cause of the topological phase transition, a fundamental understanding of the magnetic and electronic properties of Dy-doped Bi2Te3 remained elusive. Here, we present an x-ray magnetic circular dichroism, polarized neutron reflectometry, muon-spin rotation, and resonant photoemission study of the microscopic magnetic and electronic properties. We find that the films are not simply paramagnetic but that instead the observed behavior can be well explained by the assumption of slowly fluctuating, inhomogeneous, magnetic patches with increasing volume fraction as the temperature decreases. At liquid helium temperatures, a large effective magnetization can be easily introduced by the application of moderate magnetic fields, implying that this material is very suitable for proximity coupling to an underlying ferromagnetic insulator or in a heterostructure with transition-metal-doped layers. However, the introduction of some charge carriers by the Dy dopants cannot be excluded at least in these highly doped samples. Nevertheless, we find that the magnetic order is not mediated via the conduction channel in these samples and therefore magnetic order and carrier concentration are expected to be independently controllable. This is not generally the case for transition-metal-doped topological insulators, and Dy doping should thus allow for improved TI quantum devices.

Absorption and emission spectra of Ga1.7Ge25As8.3S65 glasses doped with rare-earth ions

NASA Astrophysics Data System (ADS)

Lupan, E. V.; Iaseniuc, O. V.; Ciornea, V. I.; Iovu, M. S.

2016-12-01

Excellent optical properties of chalcogenide glasses make them interesting for optoelectronic devices in the visible (VIS) and, especially, in the near- and mid-infrared (NIR and MIR) spectral regions. The rare-earth (RE3+) doped Ga17Ge25As8.3S65 glasses were prepared in evacuated ( 10-5 Pa) silica-glass ampoules which were heated up to 1000 °C at 2-4°C min-1, and then the melt was quenched. The absorption and photoluminescence spectra in the visible and near IR regions for GA1.7Ge25As8.3S65 doped with rare-earth RE+) ions (Sm3+, Nd3+, Pr3+, Dy3+ and co-doped with Ho3++Dy3+) are investigated. The energy transfer of the absorbed light in the broad band Urbach region of the host glass to the RE3+ ions is suggested for increasing the emission efficiency. The investigated Ga17Ge25As8.3S65 glasses doped with RE3+ ions are promising materials for optical amplifiers operating at 1300 and 1500 nm telecommunication windows.

Rare-earth doped gadolinia based phosphors for potential multicolor and white light emitting deep UV LEDs.

PubMed

Bedekar, Vinila; Dutta, Dimple P; Mohapatra, M; Godbole, S V; Ghildiyal, R; Tyagi, A K

2009-03-25

Gadolinium oxide host and europium/dysprosium/terbium doped gadolinium oxide nanoparticles were synthesized using the sonochemical technique. Gadolinium oxide nanocrystals were also co-doped with total 2 mol% of Eu(3+)/Dy(3+),Eu(3+)/Tb(3+),Dy(3+)/Tb(3+), and also Eu(3+)/Dy(3+)/Tb(3+) ions, by the same method. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The size of the particles ranged from 15 to 30 nm. The triple doped samples showed multicolor emission on single wavelength excitation. The photoluminescence results were correlated with the lifetime data to get an insight into the luminescence and energy transfer processes taking place in the system. On excitation at 247 nm, the novel nanocrystalline Gd(2)O(3):RE (RE = Dy, Tb) phosphor resulted in having very impressive CIE chromaticity coordinates of x = 0.315 and y = 0.316, and a correlated color temperature of 6508 K, which is very close to standard daylight.

Absence of long range order in SrDy2O4 frustrated magnet due to trapped defects from a dimensionality crossover

NASA Astrophysics Data System (ADS)

Gauthier, Nicolas; Fennell, Amy; Uldry, Anne-Christine; Delley, Bernard; Sibille, Romain; White, Jonathan; Niedermayer, Christof; Pomjakushin, Vladimir; Kenzelmann, Michel; Prevost, Bobby; Desilets-Benoit, Alexandre; Bianchi, Andrea D.; Dabkowska, Hanna A.; Nilsen, Goran; Regnault, Louis-Pierre

The simultaneous occurence of geometrical frustration and low dimensionality can lead to strongly correlated fluctuating ground states. In the SrLn2O4 compounds, the Ln magnetic ions form one-dimensional (1D) zig-zag chains that have both of these characteristics, offering a playground to study novel states of matter. In SrDy2O4, the two inequivalent Dy3+ sites are Ising-like with perpendicular easy-axes, favouring the decoupling of neighbouring zig-zag chains. No long range order is observed down to T = 60 mK in zero field but diffuse neutron scattering indicates short range correlations that are consistent with those of the 1D Ising zig-zag chain model. AC susceptibility measurements indicate a slowing down of the fluctuations at low temperatures. We attribute this behaviour to the domain walls in the zig-zag chains. Experimental evidence of a dimensionality crossover at low temperatures in SrDy2O4 suggest that the domains walls are trapped because of interchain interactions, precluding long-range order to the lowest temperatures.

Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors.

PubMed

Liu, Chenglu; Wang, Fang; Jia, Peiyun; Lin, Jun; Zhou, Zhiqiang

2012-01-01

Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail.

Synthesis and Absorption Properties of Hollow-spherical Dy2Cu2O5 via a Coordination Compound Method with [DyCu(3,4-pdc)2(OAc)(H2O)2]•10.5H2O Precursor.

PubMed

Liu, Xuanwen; You, Junhua; Wang, Renchao; Ni, Zhiyuan; Han, Fei; Jin, Lei; Ye, Zhiqi; Fang, Zhao; Guo, Rui

2017-10-12

Dy 2 Cu 2 O 5 nanoparticles with perovskite structures were synthesized via a simple solution method (SSM) and a coordination compound method (CCM) using [DyCu(3,4-pdc) 2 (OAc)(H 2 O) 2 ]•10.5H 2 O (pdc = 3,4-pyridinedicarboxylic acid) as precursor. The as-prepared samples were structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS) and standard Brunauer-Emmett-Teller (BET) methods. Compared to the aggregated hexahedral particles prepared by SSM, the Dy 2 Cu 2 O 5 of CCM showed hollow spherical morphology composed of nanoparticles with average diameters of 100-150 nm and a larger special surface area up to 36.5 m 2 /g. The maximum adsorption capacity (Q m ) of CCM for malachite green (MG) determined by the adsorption isotherms with different adsorbent dosages of 0.03-0.07 g, reached 5.54 g/g at room temperature. The thermodynamic parameters of adsorption process were estimated by the fittings of the isotherms at 298, 318, and 338 K, and the kinetic parameters were obtained from the time-dependent adsorption isotherms. The results revealed that the adsorption process followed a pseudo-second-order reaction. Finally, the adsorption mechanism was studied using a competitive ion (CI) experiments, and the highly efficient selective adsorption was achieved due to strong O-Cu and O-Dy coordination bonds between Dy 2 Cu 2 O 5 and MG.

Energy transfer and tunable multicolor emission and paramagnetic properties of GdF3:Dy(3+),Tb(3+),Eu(3+) phosphors.

PubMed

Guan, Hongxia; Sheng, Ye; Xu, Chengyi; Dai, Yunzhi; Xie, Xiaoming; Zou, Haifeng

2016-07-20

A series of Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy(3+), GdF3:Tb(3+) and GdF3:Eu(3+) samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy(3+), Tb(3+) and Tb(3+), Eu(3+) ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy(3+) → Tb(3+) and (2) Tb(3+) → Eu(3+). More significantly, in the Dy(3+), Tb(3+), and Eu(3+) tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu(3+). In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy(3+), Tb(3+), Eu(3+) tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Bipin Kumar, E-mail: bipinbhu@yahoo.com; Kumar, Arun; Amity Institute of Applied Science, Amity University, Noida, Uttar Pradesh 201303

Herein, a novel green emitting long-persistent Sr{sub 3}SiAl{sub 4}O{sub 11}:Eu{sup 2+}/Dy{sup 3+} phosphor was synthesized in a single phase form using facile solid state reaction method under the reducing atmosphere of 10% H{sub 2} and 90% N{sub 2}. The resulting phosphor exhibits hyper-sensitive strong broad green emission, peaking at 510 nm upon 340 nm excitation wavelength, which is attributed to the 4f{sup 6}5d{sup 1}-4f{sup 7} transitions of emission center of europium (Eu{sup 2+}) ions. Moreover, the incorporation of dysprosium (Dy{sup 3+}) ions, which act as effective hole trap centers with appropriate depth, largely enhances the photoluminescence characteristics and greatly improves the persistentmore » intense luminescence behavior of Sr{sub 3}SiAl{sub 4}O{sub 11}:Eu{sup 2+}/Dy{sup 3+} phosphor under ultraviolet (UV) excitation. In addition, with the optimum doping concentration and sufficient UV excitation time period, the as-synthesized phosphor can be persisted afterglow for time duration ∼4 h with maximum luminescence intensity. Thus, these results suggest that this phosphor could be expected as an ultimate choice for next generation advanced luminescent materials in security applications such as latent finger-marks detection, photo-masking induced phosphorescent images, and security code detection.« less

Rare earth-based low-index films for IR and multispectral thin film solutions

NASA Astrophysics Data System (ADS)

Stolze, Markus; Neff, Joe; Waibel, Friedrich

2017-10-01

Non-thoriated rare-earth fluoride based coating solutions involving DyF3 and YbF3 based films as well as non-wetting fluorohydrocarbon cap layers on such films, have been deposited, analyzed and partly optimized. Intermediate results for DyF3 based films from ion assisted e-gun deposition with O2 and N2 alone and as base for the non-wetting to-player as well as for YbF3 starting material with or without admixtures of CaF2 are discussed for low-loss LWIR and multispectral solutions.

Decay of the neutron-rich isotope 171Ho and the identification of 169Dy

NASA Astrophysics Data System (ADS)

Chasteler, R. M.; Nitschke, J. M.; Firestone, R. B.; Vierinen, K. S.; Wilmarth, P. A.

1990-10-01

Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between 170Er ions and natW targets. On-line mass separation was used together with β- and γ-ray spectroscopy in these studies. At mass A=169, the heaviest known dysprosium isotope, 39(8) s,169Dy, was identified. It was observed to β- decay to the ground state of 169Ho or through a level at 1578 keV. In the A=171 mass chain, a partial decay scheme for 55(3)-s 171Ho was determined.

Room and low temperature luminescence properties of CaSO4: Dy , Tm codoped with Li

NASA Astrophysics Data System (ADS)

Can, N.; Karalı, T.; Wang, Y.; Townsend, P. D.; Prokic, M.; Canimoglu, A.

2009-08-01

Rare earths, especially Dy or Tm doped CaSO4 phosphors are actively studied. They have high sensitivity, a large dynamic range, thermal stability and ease of preparation. Nevertheless, they can be enhanced by inclusion of lithium and this study reports some effects of lithium co-dopant on the TL and radioluminescence (RL) emissions of two TL phosphors. Addition of Li as a co-dopant ion was made either during chemical preparation of the phosphors, or as a binder component mixed with the basic phosphors matrix during the process of pressing and sintering the TLD pellets.

Evidence for SrHo2O4 and SrDy2O4 as model J1-J2 zigzag chain materials

NASA Astrophysics Data System (ADS)

Fennell, A.; Pomjakushin, V. Y.; Uldry, A.; Delley, B.; Prévost, B.; Désilets-Benoit, A.; Bianchi, A. D.; Bewley, R. I.; Hansen, B. R.; Klimczuk, T.; Cava, R. J.; Kenzelmann, M.

2014-06-01

Neutron diffraction and inelastic spectroscopy is used to characterize the magnetic Hamiltonian of SrHo2O4 and SrDy2O4. Through a detailed computation of the crystal-field levels we find site-dependent anisotropic single-ion magnetism in both materials, and diffraction measurements show the presence of strong one-dimensional spin correlations. Our measurements indicate that competing interactions of the zigzag chain, combined with frustrated interchain interactions, play a crucial role in stabilizing spin-liquid type correlations in this series.

Plant Habitat-Conscious White Light Emission of Dy(3+) in Whitlockite-like Phosphates: Reduced Photosynthesis and Inhibition of Bloom Impediment.

PubMed

Nakajima, Tomohiko; Tsuchiya, Tetsuo

2015-09-30

It has been pointed out that agricultural crops and other natural plants may be damaged by outdoor lighting systems. Therefore, lighting that does not affect plant growth is needed. To address this problem, we have prepared a new whitlockite-like phosphate Dy-phosphor Ca8MgY1-x-yLaxDyy(PO4)7, which exhibits a yellow-white Dy(3+) luminescence that has a maximum internal quantum efficiency of 65.6% under a 387 nm excitation light for x = 0.10 and y = 0.05. The x dependence of IQE showed two maxima at x = 0.10-0.15 and 0.80-0.85, which could be due to the partial allowance of f-f forbidden transitions by local lattice distortion around the Dy(3+) ions originating from the La incorporation at near end members of Ca8MgY1-x-yLaxDyy(PO4)7. Concentration quenching occurred for x > 0.05. A white light-emitting diode (LED) was fabricated from a UV LED emitting at 385 nm and a Ca8MgY1-x-yLaxDyy(PO4)7 phosphor (Dy-WLED) for which the CIE color coordinates and correlated color temperature were CIE(0.350,0.378) and 4919 K, respectively. Plant cultivation experiments on Chlorella photosynthetic growth and blooming of the short-day plant Cosmos were carried out using the prepared Dy-WLED and reference commercial LEDs. We found that the Dy-WLED substantially reduced the photosynthesis of Chlorella and inhibited bloom impediment in Cosmos. These effects originated especially from the reduction of red-near-IR emissions. Thus, we conclude that the Dy-WLED is a very promising candidate for plant habitat-conscious white LEDs for outdoor lights that can protect both natural plant habitats and crop yields.

Luminescence studies of a combustion-synthesized blue-green BaAlxOy:Eu2+,Dy3+ nanoparticles

NASA Astrophysics Data System (ADS)

Bem, Daniel B.; Dejene, F. B.; Luyt, A. S.; Swart, H. C.

2012-05-01

Blue-green emitting BaAlxOy:Eu2+,Dy3+ phosphor was synthesized by the combustion method. The influence of various parameters on the structural, photoluminescence (PL) and thermoluminescence (TL) properties of the phosphor were investigated by various techniques. Phosphor nanocrystallites with high brightness were obtained without significantly changing the crystalline structure of the host. In the PL studies, broad-band excitation and emission spectra were observed with major peaks at 340 and 505 nm, respectively. The observed afterglow is ascribed to the generation of suitable traps due to the presence of the co-doped Dy3+ ions. Though generally broad, the peak structure of the TL glow curves obtained after irradiation with UV light was non-uniform with suggesting the contribution to afterglow from multiple events at the luminescent centers. Further insight on the afterglow behavior of the phosphor was deduced from TL decay results.

Record high magnetic ordering temperature in a lanthanide at extreme pressure

DOE PAGES

Lim, J.; Fabbris, G.; Haskel, D.; ...

2017-11-07

Today's best permanent magnet materials, SmCo 5 and Nd 2Fe 14B, could likely be made signi fi cantly more powerful were it not necessary to dilute the strong magnetism of the rare earth ions (Sm, Nd) with the 3 d transition elements (Fe, Co). Since the rare-earth metals order magnetically at relatively low temperatures T o <= 292 K, transition elements must be added to bring T o to temperatures well above ambient. Under pressure T o (P) for the neighboring lanthanides Gd, Tb, and Dy follows a notably nonmonotonic, but nearly identical, dependence to similar to 60 GPa. Atmore » higher pressures, however, Tb and Dy exhibit highly anomalous behavior, T o for Dy soaring to temperatures well above ambient. In conclusion, we suggest that this anomalously high magnetic ordering temperature is an heretofore unrecognized feature of the Kondo lattice state.« less

Anomalous pressure dependence of magnetic ordering temperature in Tb revealed by resistivity measurements to 141 GPa. Comparison with Gd and Dy

DOE PAGES

Lim, J.; Fabbris, G.; Haskel, D.; ...

2015-05-26

In previous studies the pressure dependence of the magnetic ordering temperature T o of Dy was found to exhibit a sharp increase above its volume collapse pressure of 73 GPa, appearing to reach temperatures well above ambient at 157 GPa. In a search for a second such lanthanide, electrical resistivity measurements were carried out on neighboring Tb to 141 GPa over the temperature range 3.8 - 295 K. Below Tb’s volume collapse pressure of 53 GPa, the pressure dependence T o(P) mirrors that of both Dy and Gd. However, at higher pressures T o(P) for Tb becomes highly anomalous. Thismore » result, together with the very strong suppression of superconductivity by dilute Tb ions in Y, suggests that extreme pressure transports Tb into an unconventional magnetic state with an anomalously high magnetic ordering temperature.« less

Record high magnetic ordering temperature in a lanthanide at extreme pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, J.; Fabbris, G.; Haskel, D.

Today's best permanent magnet materials, SmCo 5 and Nd 2Fe 14B, could likely be made signi fi cantly more powerful were it not necessary to dilute the strong magnetism of the rare earth ions (Sm, Nd) with the 3 d transition elements (Fe, Co). Since the rare-earth metals order magnetically at relatively low temperatures T o <= 292 K, transition elements must be added to bring T o to temperatures well above ambient. Under pressure T o (P) for the neighboring lanthanides Gd, Tb, and Dy follows a notably nonmonotonic, but nearly identical, dependence to similar to 60 GPa. Atmore » higher pressures, however, Tb and Dy exhibit highly anomalous behavior, T o for Dy soaring to temperatures well above ambient. In conclusion, we suggest that this anomalously high magnetic ordering temperature is an heretofore unrecognized feature of the Kondo lattice state.« less

Unusual undecanuclear heterobimetallic Zn4Ln7 (Ln = Gd, Dy) nano-sized clusters encapsulating two peroxide anions through spontaneous intake of dioxygen.

PubMed

Ke, Hongshan; Lu, Xiaohua; Wei, Wen; Wang, Wenyuan; Xie, Gang; Chen, Sanping

2017-06-27

The synthesis, characterization and properties of two unprecedented undecanuclear heterobimetallic Zn 4 Ln 7 complexes of formula [Zn 4 Ln 7 (L) 8 (O 2 ) 2 (OH) 4 (Cl) 4 (H 2 O) 4 ]·Cl·4H 2 O·4CH 3 CN (Ln = Gd (1), Dy (2)) encapsulating two peroxide anions are presented, representing a very rare example of a 3d-peroxo-Ln system and expanding the realm of metal-peroxo complexes. These eleven metal ions are arranged in a peculiar structural motif, where Zn 4 is located at the peripheral shell wrapping Ln 7 in the inner core. The Zn ions are penta-coordinate in all cases, linked to the NO 2 donor atoms from the L 2- ligand and to a hydroxyl group, and the apical position is occupied by a chloride anion. All Ln III ions in these systems are octa-coordinate with LnO 8 and LnNO 7 coordination spheres. Magnetocaloric effect (MCE) behavior has been found in the Gd analogue due to multiple low lying excited states arising from antiferromagnetic Gd-Gd exchange interactions. The Dy derivative shows frequency dependent out-of-phase signals indicating the presence of slow relaxation of magnetization below 8 K under zero applied direct current (dc) field, but without reaching a maximum, which is due to a faster quantum tunneling relaxation. The effective barrier extracted from the frequency dependent data is U eff = 11.2 K and a τ 0 of 4.18 × 10 -6 s.

Multiple-decker phthalocyaninato dinuclear lanthanoid(III) single-molecule magnets with dual-magnetic relaxation processes.

PubMed

Katoh, Keiichi; Horii, Yoji; Yasuda, Nobuhiro; Wernsdorfer, Wolfgang; Toriumi, Koshiro; Breedlove, Brian K; Yamashita, Masahiro

2012-11-28

The SMM behaviour of dinuclear Ln(III)-Pc multiple-decker complexes (Ln = Tb(3+) and Dy(3+)) with energy barriers and slow-relaxation behaviour were explained by using X-ray crystallography and static and dynamic susceptibility measurements. In particular, interactions among the 4f electrons of several dinuclear Ln(III)-Pc type SMMs have never been discussed on the basis of the crystal structure. For dinuclear Tb(III)-Pc complexes, a dual magnetic relaxation process was observed. The relaxation processes are due to the anisotropic centres. Our results clearly show that the two Tb(3+) ion sites are equivalent and are consistent with the crystal structure. On the other hand, the mononuclear Tb(III)-Pc complex exhibited only a single magnetic relaxation process. This is clear evidence that the magnetic relaxation mechanism depends heavily on the dipole-dipole (f-f) interactions between the Tb(3+) ions in the dinuclear systems. Furthermore, the SMM behaviour of dinuclear Dy(III)-Pc type SMMs with smaller energy barriers compared with that of Tb(III)-Pc and slow-relaxation behaviour was explained. Dinuclear Dy(III)-Pc SMMs exhibited single-component magnetic relaxation behaviour. The results indicate that the magnetic relaxation properties of dinuclear Ln(III)-Pc multiple-decker complexes are affected by the local molecular symmetry and are extremely sensitive to tiny distortions in the coordination geometry. In other words, the spatial arrangement of the Ln(3+) ions (f-f interactions) in the crystal is important. Our work shows that the SMM properties can be fine-tuned by introducing weak intermolecular magnetic interactions in a controlled SMM spatial arrangement.

Ferrielectricity in DyMn2O5: A golden touchstone for multiferroicity of RMn2O5 family

NASA Astrophysics Data System (ADS)

Liu, J.-M.; Dong, S.

2015-06-01

The RMn2O5 manganite compounds represent one class of multiferroic family with magnetic origins, which has been receiving continuous attention in the past decade. So far, our understanding of the magnetic origins for ferroelectricity in RMn2O5 is associated with the nearly collinear antiferromagnetic structure of Mn ions, while the exchange striction induced ionic displacements are the consequence of the spin frustration competitions. While this scenario may be applied to almost all RMn2O5 members, its limitation is either clear: the temperature-dependent behaviors of electric polarization and its responses to external stimuli are seriously materials dependent. These inconsistences raise substantial concern with the state-of-the-art physics of ferroelectricity in RMn2O5. In this mini-review, we present our recent experimental results on the roles of the 4f moments from R ions which are intimately coupled with the 3d moments from Mn ions. DyMn2O5 is a golden figure for illustrating these roles. It is demonstrated that the spin structure accommodates two nearly collinear sublattices which generate respectively two ferroelectric (FE) sublattices, enabling DyMn2O5 an emergent ferrielectric (FIE) system rarely identified in magnetically induced FEs. The evidence is presented from several aspects, including FIE-like phenomena and magnetoelectric responses, proposed structural model, and experimental check by nonmagnetic substitutions of the 3d and 4f moments. Additional perspectives regarding possible challenges in understanding the multiferroicity of RMn2O5 as a generalized scenario are discussed.

Adsorption of dysprosium on the graphite (0001) surface: Nucleation and growth at 300 K

DOE PAGES

Kwolek, Emma J.; Lei, Huaping; Lii-Rosales, Ann; ...

2016-06-13

We have studied nucleation and growth of Dy islands on the basal plane of graphite at 300 K using scanning tunneling microscopy, density functional theory (DFT) in a form that includes van der Waals interactions, and analytic theory. The interaction of atomic Dy with graphite is strong, while the diffusion barrier is small. Experiment shows that at 300 K, the density of nucleated islands is close to the value predicted for homogeneous nucleation, using critical nucleus size of 1 and the DFT-derived diffusion barrier. Homogeneous nucleation is also supported by the monomodal shape of the island size distributions. Comparison withmore » the published island density of Dy on graphene shows that the value is about two orders of magnitude smaller on graphite, which can be attributed to more effective charge screening in graphite. The base of each island is 3 atomic layers high and atomically ordered, forming a coincidence lattice with the graphite. Islands resist coalescence, probably due to multiple rotational orientations associated with the coincidence lattice. Upper levels grow as discernible single-atom layers. Analysis of the level populations reveals significant downward interlayer transport, which facilitates growth of the base. As a result, this island shape is metastable, since more compact three-dimensional islands form at elevated growth temperature.« less

Adsorption of dysprosium on the graphite (0001) surface: Nucleation and growth at 300 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwolek, Emma J.; Lii-Rosales, Ann; Department of Chemistry, Iowa State University, Ames, Iowa 50011

2016-12-07

We have studied nucleation and growth of Dy islands on the basal plane of graphite at 300 K using scanning tunneling microscopy, density functional theory (DFT) in a form that includes van der Waals interactions, and analytic theory. The interaction of atomic Dy with graphite is strong, while the diffusion barrier is small. Experiment shows that at 300 K, the density of nucleated islands is close to the value predicted for homogeneous nucleation, using critical nucleus size of 1 and the DFT-derived diffusion barrier. Homogeneous nucleation is also supported by the monomodal shape of the island size distributions. Comparison withmore » the published island density of Dy on graphene shows that the value is about two orders of magnitude smaller on graphite, which can be attributed to more effective charge screening in graphite. The base of each island is 3 atomic layers high and atomically ordered, forming a coincidence lattice with the graphite. Islands resist coalescence, probably due to multiple rotational orientations associated with the coincidence lattice. Upper levels grow as discernible single-atom layers. Analysis of the level populations reveals significant downward interlayer transport, which facilitates growth of the base. This island shape is metastable, since more compact three-dimensional islands form at elevated growth temperature.« less

The properties of RE-TM magneto-optical films

NASA Astrophysics Data System (ADS)

Lee, Z. Y.; Miao, X. S.; Zhu, P.; Hu, Y. S.; Wan, D. F.; Dai, D. W.; Chen, S. B.; Lin, G. Q.

1992-09-01

In this paper, the magnetic, magneto-optical and galvonomagnetic properties, and their temperature dependence for LRE-TM SmCo, SmCoDy and HRE-TM TbFeCo magneto-optical films as high density recording media prepared by rf magnetron sputtering or evaporation are reported. By adding Dy to SmCo thin film, the SmCoDy thin film is more suitable for magneto-optical recording, its domain size being below 0.63 μm. The Kerr enhancement and corrosion protective effects of AIN and AlSiN for optimum design of the multi-layer structure of magneto-optical disk are described. The instruments of measuring the magneto-optical Kerr effect and magneto-optical recording domain characteristics of thin films are reviewed.

Composition anisotropy compensation and magnetostriction of Co-doped Laves compounds Tb0.2Dy0.8-xPrxFe1.93 (0 ≤ x ≤ 0.40)

NASA Astrophysics Data System (ADS)

Li, F.; Liu, J. J.; Zhu, X. Y.; Shen, W. C.; Lin, L. L.; Du, J.; Si, P. Z.

2018-07-01

Alloys of Tb0.2Dy0.8-xPrx(Fe0.8Co0.2)1.93 (0 ≤ x ≤ 0.40) are arc melted and investigated for structural, magnetic and magnetoelastic properties by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain technique. The 20 at.% Co substitution for Fe is shown to enable the formation of the single Laves phase with a high Pr content up to x = 0.25. Experimental evidence for magnetocrystalline-anisotropy compensation between Pr3+ and Dy3+ ions is obtained in the Laves phase system. The easy magnetization direction (EMD) at room temperature rotates from <100> to <110> axis when x increases from 0 to 0.40. The linear anisotropic magnetostriction λa (=λ||-λ⊥) increases with increasing Pr content when x ≤ 0.25 ascribed to both the larger magnetostriction of PrFe2 than that of DyFe2 and the decrease of the resulted anisotropy due to compensation. The composition anisotropy compensation is found to be around x = 0.25, shifting to the Pr-rich side at room temperature as compared to the Co-free counterpart Tb0.2Dy0.8-xPrxFe1.93 system. The Tb0.2Dy0.55Pr0.25(Fe0.8Co0.2)1.93 alloy has good magnetoelastic properties at room temperature, that is, a low anisotropy and a high low-field magnetostriction λa ∼140 ppm at 1 kOe.

Structural and luminescent study of TeO2-BaO-Bi2O3-Ag glass system doped with Eu3+ and Dy3+ for possible color-tunable phosphor application

NASA Astrophysics Data System (ADS)

Lewandowski, Tomasz; Seweryński, Cezary; Walas, Michalina; Łapiński, Marcin; Synak, Anna; Sadowski, Wojciech; Kościelska, Barbara

2018-05-01

Tellurite glass systems of 73TeO2-4BaO-3Bi2O3-1Ag:xEu2O3-(2-x)Dy2O3 (where x = 0.5, 1, 1.5, 2 in molar ratio) composition have been successfully synthesized. In order to acquire Ag nanoparticles, materials have been heat treated at 350 °C in the air atmosphere. Structural properties of obtained samples were evaluated with various techniques. X-Ray Diffraction (XRD) measurements indicated that obtained materials are amorphous in nature. UV-vis results presented transitions characteristic to Dy3+ and Eu3+ ions. Additionally, X-Ray Photoelectron Spectroscopy (XPS) analysis indicated the presence of silver in metallic form. Photoluminescence measurements shown influence of Ag nanoparticles on emission characteristics. Simultaneous emission of Dy3+ and Eu3+ has been observed when samples were excited with λexc = 390 nm. Change of the emission color induced by heat treatment has been observed and described in case of x = 1 glass series. According to CIE results emission color changes as Eu/Dy ratio and heat treatment time are changed. Emission shifts from reddish-orange to yellowish white color. Obtained photoluminescence results confirm that synthesized materials are good candidates for color tunable phosphors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahesh, P., E-mail: pamu@iitg.ernet.in; Subhash, T., E-mail: pamu@iitg.ernet.in; Pamu, D., E-mail: pamu@iitg.ernet.in

We report the dielectric properties of (K{sub 0.5}Na{sub 0.5})NbO{sub 3} ceramics doped with x wt% of Dy{sub 2}O{sub 3} (x= 0.0-1.5 wt%) using the broadband dielectric spectroscopy. The X-ray diffraction studies showed the formation of perovskite structure signifying that Dy{sub 2}O{sub 3} diffuse into the KNN lattice. Samples doped with x > 0.5 wt% exhibit smaller grain size and lower relative densities. The dielectric properties of KNN ceramics doped with Dy{sub 2}O{sub 3} are enhanced by increasing the Dy{sup 3+} content; among the compositions studied, x = 0.5 wt% exhibited the highest dielectric constant and lowest loss at 1MHz overmore » the temperature range of 30°C to 400°C. All the samples exhibit maximum dielectric constant at the Curie temperature (∼ 326°C) and a small peak in the dielectric constant at around 165°C is due to a structural phase transition.« less

The cataphoretic emitter effect exhibited in high intensity discharge lamp electrodes

NASA Astrophysics Data System (ADS)

Mentel, Juergen

2018-01-01

A mono-layer of atoms, electropositive with respect to the substrate atoms, forms a dipole layer, reducing its work function. Such a layer is generated by diffusion of emitter material from the interior of the substrate, by vapour deposition or by deposition of emitter material onto arc electrodes by cataphoresis. This cataphoretic emitter effect is investigated within metal halide lamps with transparent YAG ceramic burners, and within model lamps. Within the YAG lamps, arcs are operated with switched-dc current between rod shaped tungsten electrodes in high pressure Hg vapour seeded with metal iodides. Within the model lamps, dc arcs are operated between rod-shaped tungsten electrodes—one doped—in atmospheric pressure Ar. Electrode temperatures are determined by 1λ -pyrometry, combined with simulation of the electrode heat balance. Plasma temperatures, atom and ion densities of emitter material are determined by emission and absorption spectroscopy. Phase resolved measurements in YAG lamps seeded with CeI3, CsI, DyI3, TmI3 and LaI3 show, within the cathodic half period, a reduction of the electrode temperature and an enhanced metal ion density in front of the electrode, and an opposite behavior after phase reversal. With increasing operating frequency, the state of the cathode overlaps onto the anodic phase—except for Cs, being low in adsorption energy. Generally, the phase averaged electrode tip temperature is reduced by seeding a lamp with emitter material; its height depends on admixtures. Measurements at tungsten electrodes doped with ThO2, La2O3 and Ce2O3 within the model lamp show that evaporated emitter material is redeposited by an emitter ion current onto the electrode surface. It reduces the work function of tungsten cathodes above the evaporation temperature of the emitter material, too; and also of cold anodes, indicating a field reversal in front of them. The formation of an emitter spot at low cathode temperature and high emitter material density is traced back to a locally reduced work function generated by a locally enhanced emitter ion current density.

Induction of sustained hypercholesterolemia by single adeno-associated virus-mediated gene transfer of mutant hPCSK9.

PubMed

Roche-Molina, Marta; Sanz-Rosa, David; Cruz, Francisco M; García-Prieto, Jaime; López, Sergio; Abia, Rocío; Muriana, Francisco J G; Fuster, Valentín; Ibáñez, Borja; Bernal, Juan A

2015-01-01

Patients with mutations in the proprotein convertase subtilisin/kexin type 9 (PCSK9) gene have hypercholesterolemia and are at high risk of adverse cardiovascular events. We aimed to stably express the pathological human D374Y gain-of-function mutant form of PCSK9 (PCSK9(DY)) in adult wild-type mice to generate a hyperlipidemic and proatherogenic animal model, achieved with a single systemic injection with adeno-associated virus (AAV). We constructed an AAV-based vector to support targeted transfer of the PCSK9(DY) gene to liver. After injection with 3.5×10(10) viral particles, mice in the C57BL/6J, 129/SvPasCrlf, or FVB/NCrl backgrounds developed long-term hyperlipidemia with a strong increase in serum low-density lipoprotein. Macroscopic and histological analysis showed atherosclerotic lesions in the aortas of AAV-PCSK9(DY) mice fed a high-fat-diet. Advanced lesions in these high-fat-diet-fed mice also showed evidence of macrophage infiltration and fibrous cap formation. Hepatic AAV-PCSK9(DY) infection did not result in liver damage or signs of immunologic response. We further tested the use of AAV-PCSK9(DY) to study potential genetic interaction with the ApoE gene. Histological analysis of ApoE(-/-) AAV-PCSK9(DY) mice showed a synergistic response to ApoE deficiency, with aortic lesions twice as extensive in ApoE(-/-) AAV-PCSK9(DY)-transexpressing mice as in ApoE(-/-) AAV-Luc controls without altering serum cholesterol levels. Single intravenous AAV-PCSK9(DY) injection is a fast, easy, and cost-effective approach, resulting in rapid and long-term sustained hyperlipidemia and atherosclerosis. We demonstrate as a proof of concept the synergy between PCSK9(DY) gain-of-function and ApoE deficiency. This methodology could allow testing of the genetic interaction of several mutations without the need for complex and time-consuming backcrosses. © 2014 American Heart Association, Inc.

A Cesium Rare-Earth Silicate Cs3 RESi6 O15 (RE=Dy-Lu, Y, In): The Parent of an Unusual Structural Class Featuring a Remarkable 57 Å Unit Cell Axis.

PubMed

Terry, Rylan; Vinton, Daniel; McMillen, Colin D; Kolis, Joseph W

2018-02-19

The structure of Cs 3 RESi 6 O 15 , where RE=Dy-Lu, Y, In, is unusual in that it contains octahedrally coordinated rare-earth ions; their relative orientation dictates the structure, as they rotate about the c-axis supported by the cyclic Si 6 O 15 framework. The repeat unit of the rotation is eight units generating a very long (ca. 57 Å) unit cell axis. This unusual repeat unit is created by the structural flexibility of the hexasilicate ring, which is in turn affected by the size of the rare earth ion as well as the size of alkali ion residing within the silicate layers. Previous work showed for the smaller Sc 3+ ion, the rotation of the octahedra is not sufficient to achieve closure at an integral repeat unit and an incommensurate structure results. The products are prepared as large, high quality single crystals using a high-temperature (650 °C) hydrothermal method with CsOH and F - mineralizers. The presence of fluoride is essential to the formation of the product. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization and Luminescence Properties of Color-Tunable Dy3+-Doped BaY2ZnO5 Nanophosphors

NASA Astrophysics Data System (ADS)

Sonika; Khatkar, S. P.; Khatkar, Avni; Kumar, Rajesh; Taxak, V. B.

2015-01-01

Dy3+-doped BaY2ZnO5 nanophosphors were successfully synthesized by use of a solution combustion process. The effects of sintering temperature and dysprosium concentration on the structural and luminescence characteristics of the phosphors were investigated. X-ray diffraction (XRD) analysis confirmed the formation of pure orthorhombic BaY2ZnO5 with the space group Pbnm at 1100°C. Morphological investigation revealed spherical nanoparticles with smooth surfaces. The luminescence features of the nanophosphor were studied by use of photoluminescence excitation (PLE) and photoluminescence emission (PL), with luminescence decay curves and color ( x, y) coordinates. On excitation at 355 nm, BaY2ZnO5 nanophosphor doped with trivalent dysprosium ion emits white light as a mixture of blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emission. Concentration quenching is explained on the basis of cross-relaxation between intermediate Dy3+ states. Thus, BaY2ZnO5:Dy3+ nanophosphor may be suitable for producing efficient white light for ultraviolet-light-emitting diodes (UV-LEDs), fluorescent lamps, and a variety of optical display panels.

Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

PubMed

Zhao, Lang; Wu, Jianfeng; Ke, Hongshan; Tang, Jinkui

2014-04-07

Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of χ″ signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes.

Thermoluminescence properties of lithium magnesium borate glasses system doped with dysprosium oxide.

PubMed

Mhareb, M H A; Hashim, S; Ghoshal, S K; Alajerami, Y S M; Saleh, M A; Razak, N A B; Azizan, S A B

2015-12-01

We report the impact of dysprosium (Dy(3+)) dopant and magnesium oxide (MgO) modifier on the thermoluminescent properties of lithium borate (LB) glass via two procedures. The thermoluminescence (TL) glow curves reveal a single prominent peak at 190 °C for 0.5 mol% of Dy(3+). An increase in MgO contents by 10 mol% enhances the TL intensity by a factor of 1.5 times without causing any shift in the maximum temperature. This enhancement is attributed to the occurrence of extra electron traps created via magnesium and the energy transfer to trivalent Dy(3+) ions. Good linearity in the range of 0.01-4 Gy with a linear correlation coefficient of 0.998, fading as low as 21% over a period of 3 months, excellent reproducibility without oven annealing and tissue equivalent effective atomic numbers ~8.71 are achieved. The trap parameters, including geometric factor (μg), activation energy (E) and frequency factor (s) associated with LMB:Dy are also determined. These favorable TL characteristics of prepared glasses may contribute towards the development of Li2O-MgO-B2O3 radiation dosimeters. Copyright © 2015 John Wiley & Sons, Ltd.

Aridity induces super-optimal investment in leaf venation by Eucalyptus and Corymbia

NASA Astrophysics Data System (ADS)

Drake, Paul L.; de Boer, Hugo J.; Price, Charles A.; Veneklaas, Erik J.

2016-04-01

The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on carbon uptake, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Zwieniecki and Boyce (2014) proposed a generic framework on the hydraulic architecture of leaves based on the argument that water is optimally distributed when the lateral distance between neighboring water transport veins (dx) is approximately equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈1. Many derived angiosperms realize this optimal hydraulic architecture by closely coordinating leaf vein density with leaf thickness and the lateral position of veins inside the leaf. Zwieniecki and Boyce (2014) further suggested that over-investment in veins (dx:dy <1) provides no functional benefit owing to the minor additional increases in leaf gas exchange that may be achieved by reducing dx beyond dy. Although this framework is valid for derived angiosperms adapted to temperate and moist (sub)tropical environments, we hypothesize that super-investment in leaf venation (resulting in dx:dy<<1) may provide a specific gas exchange advantage in arid environments that select for thick and amphistomatous leaf morphologies. The relatively long dy inherent to these leaf morphologies imposes hydraulic constraints on productivity that may (partially) be offset by reducing dx beyond dy. To test our hypothesis we assembled the leaf hydraulic, morphological and photosynthetic traits of 65 species (401 individuals) within the widely distributed and closely related genera Eucalyptus and Corymbia along a 2000-km-long aridity gradient in Western Australia (see Schulze et al., 2006). We inferred the potential functional benefit of reducing dx beyond dy using a semi-empirical model that links leaf morphology and hydraulics to photosynthesis. Our results reveal that Eucalyptus and Corymbia evolved extremely high vein densities in addition to thick amphistomatous leaf morphologies along the natural aridity gradient resulting in dx:dy ratios ranging between 0.8 and 0.08. We propose that as the thickness of amphistomatous leaves increases, the effect of reducing dx beyond dy is to offset the reduction in photosynthesis that would result from the theoretical optimal architecture of dx:dy ≈1. Our model quantified the resulting relative gain in photosynthesis at 10% to 15%, which could provide a crucial gas exchange advantage. We conclude that aridity confounds selection for leaf traits associated with a long leaf lifespan and thermal capacitance as well as those supporting higher rates of leaf water transport and photosynthesis. References Schulze, E.-D., Turner, N. C., Nicolle, D. and Schumacher, J.: Species differences in carbon isotope ratios, specific leaf area and nitrogen concentrations in leaves of Eucalyptus growing in a common garden compared with along an aridity gradient, Physiol. Plant., 127(3), 434-444, 2006. Zwieniecki, M. A. and Boyce, C. K.: Evolution of a unique anatomical precision in angiosperm leaf venation lifts constraints on vascular plant ecology, Proc. R. Soc. B Biol. Sci., 281(1779), 2014.

Trivalent rare-earth activated hexagonal lanthanum fluoride (LaF3 :RE3+ , where RE = Tb, Sm, Dy and Tm) nanocrystals: Synthesis and optical properties.

PubMed

Kasturi, Singh; Marikumar, R; Vaidyanathan, Sivakumar

2018-05-10

The LaF 3 nanocrystals through a facile hydrothermal route with hexagonal structures have been synthesized via doping of trivalent rare earth (RE 3+ ) ions - RE = Tb, Sm, Dy and Tm - with rod-like and perforated morphologies using NH 4 F as fluorine precursor. Hexagonal phase formation was confirmed by powder X-ray diffraction. The crystalline sizes were calculated by the Scherrer equation where found to have an average crystalline size of 12 to 35 nm. The morphological studies of the nanocrystals were carried out by means of transmission electron microscopy (TEM). The LaF 3 :Tm 3+ ,Sm 3+ ions show the characteristic emission of Tb 3+ and Tm 3+ respectively. In Sm 3+ -doped LaF 3 , three prominent emission peaks at 561, 597 and 641 nm were found, which belong to 4 G 5/2  →  6 H 5/2 , 4 G 5/2  →  6 H 7/2 (magnetic dipole) and 4 G 5/2  →  6 H 9/2 (electric dipole) transitions, respectively. The Dy 3+ activated LaF 3 shows blue and yellow emission and the corresponding CIE color coordinate show white light emission (CCT value 10650 K). Copyright © 2018 John Wiley & Sons, Ltd.

Fluoride release and recharge behavior of a nano-filled resin-modified glass ionomer compared with that of other fluoride releasing materials.

PubMed

Mitra, Sumita B; Oxman, Joe D; Falsafi, Afshin; Ton, Tiffany T

2011-12-01

To compare the long-term fluoride release kinetics of a novel nano-filled two-paste resin-modified glass-ionomer (RMGI), Ketac Nano (KN) with that of two powder-liquid resin-modified glass-ionomers, Fuji II LC (FLC) and Vitremer (VT) and one conventional glass-ionomer, Fuji IX (FIX). Fluoride release was measured in vitro using ion-selective electrodes. Kinetic analysis was done using regression analysis and compared with existing models for GIs and compomers. In a separate experiment the samples of KN and two conventional glass-ionomers, FIX and Ketac Molar (KM) were subjected to a treatment with external fluoride source (Oral-B Neutra-Foam) after 3 months of fluoride release and the recharge behavior studied for an additional 7-day period. The cumulative amount of fluoride released from KN, VT and FLC and the release profiles were statistically similar but greater than that for FIX at P < 0.05. All four materials, including KN, showed a burst of fluoride ions at shorter times (t) and an overall rate dependence on t1/2 typical for glass-ionomers. The coating of KN with its primer and of DY with its adhesive did not significantly alter the fluoride release behavior of the respective materials. The overall rate for KN was significantly higher than for the compomer DY. DY showed a linear rate of release vs. t and no burst effect as expected for compomers. The nanoionomer KN showed fluoride recharge behavior similar to the conventional glass ionomers FIX and KM. Thus, it was concluded that the new RMGI KN exhibits fluoride ion release behavior similar to typical conventional and RMGIs and that the primer does not impede the release of fluoride.

Assessing the exchange coupling in binuclear lanthanide(iii) complexes and the slow relaxation of the magnetization in the antiferromagnetically coupled Dy2 derivative.

PubMed

Chow, Chun Y; Bolvin, Hélène; Campbell, Victoria E; Guillot, Régis; Kampf, Jeff W; Wernsdorfer, Wolfgang; Gendron, Frédéric; Autschbach, Jochen; Pecoraro, Vincent L; Mallah, Talal

2015-07-01

We report here the synthesis and the investigation of the magnetic properties of a series of binuclear lanthanide complexes belonging to the metallacrown family. The isostructural complexes have a core structure with the general formula [Ga 4 Ln 2 (shi 3- ) 4 (Hshi 2- ) 2 (H 2 shi - ) 2 (C 5 H 5 N) 4 (CH 3 OH) x (H 2 O) x ]· x C 5 H 5 N· x CH 3 OH· x H 2 O (where H 3 shi = salicylhydroxamic acid and Ln = Gd III 1 ; Tb III 2 ; Dy III 3 ; Er III 4 ; Y III 5 ; Y III 0.9 Dy III 0.1 6 ). Apart from the Er-containing complex, all complexes exhibit an antiferromagnetic exchange coupling leading to a diamagnetic ground state. Magnetic studies, below 2 K, on a single crystal of 3 using a micro-squid array reveal an opening of the magnetic hysteresis cycle at zero field. The dynamic susceptibility studies of 3 and of the diluted DyY 6 complexes reveal the presence of two relaxation processes for 3 that are due to the excited ferromagnetic state and to the uncoupled Dy III ions. The antiferromagnetic coupling in 3 was shown to be mainly due to an exchange mechanism, which accounts for about 2/3 of the energy gap between the antiferro- and the ferromagnetic states. The overlap integrals between the Natural Spin Orbitals (NSOs) of the mononuclear fragments, which are related to the magnitude of the antiferromagnetic exchange, are one order of magnitude larger for the Dy 2 than for the Er 2 complex.

Effect of annealing on the structural, optical and emissive properties of SrWO4:Ln3+ (Dy3+, Eu3+ and Sm3+) nanoparticles

NASA Astrophysics Data System (ADS)

Maheshwary; Singh, B. P.; Singh, R. A.

2016-01-01

Lanthanide ions, Ln3+ (Dy3+, Eu3+ and Sm3+) doped SrWO4 nanoparticles were synthesized using ethylene glycol (EG) as a capping agent as well as reaction medium. The X-ray diffraction (XRD) study reveals that all the Ln3+ (Dy3+, Eu3+ and Sm3+) doped samples are well crystalline in nature with a tetragonal scheelite structure of SrWO4 phase. TG study reveals that the nanophosphors are thermally stable. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy techniques were used to obtain the information about internal and external vibrational modes present in the SrWO4 structure. Optical properties were investigated using UV-vis and photoluminescence (PL) spectroscopy. The average crystallite size was calculated using Debye-Scherrer's for as-prepared and 800 °C annealed samples and is found to be in the range of ∼35-70 nm. The luminescence intensity of Eu3+ doped SrWO4 nanoparticles under 364 nm excitation wavelength reveals that 5D0 → 7F2 transition at ∼613 nm (red) is more prominent than that of 5D0 → 7F1 transition at ∼590 nm (orange). Also upon excitation by UV radiation, the SrWO4:Dy3+ phosphor shows the yellow and blue transition lines appearing at ∼572 and 484 nm which are the characteristic electronic transitions of 4F9/2-6H13/2 and 4F9/2-6H15/2 emission line of Dy3+, respectively. Also Sm3+ doped SrWO4 nanophosphor shows its characteristic emission lines in the range of 550-720 nm, corresponding to 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2 and 11/2) transitions of Sm3+ ions. The predominant orange red color can be attributed to 4G5/2 → 6H9/2 located at ∼642 nm. This is related to the polarizing effect due to the energy transfer from WO42- to the Eu3+, Dy3+ and Sm3+ sites, respectively. Effect of annealing on the photoluminescence properties of samples has been studied and it was found that luminescence intensity increases up to ∼3 times on heating the samples at 800 °C. This may be due to reduction in non-radiative decay channels pathways and reduced surface defects associated with the samples. These studies show that these Ln3+ (Dy3+, Eu3+ and Sm3+) doped SrWO4 nanophosphors may be used as potential candidates for the advancement in LEDs.

Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

NASA Astrophysics Data System (ADS)

de Boer, Hugo; Drake, Paul; Veneklaas, Erik

2017-04-01

The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. Our results highlight the need to consider the specific leaf hydraulic architecture of aridity-adapted plants when studying ecohydrological processes in arid ecosystems.

Predictive model for ionic liquid extraction solvents for rare earth elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grabda, Mariusz; Oleszek, Sylwia; Institute of Environmental Engineering of the Polish Academy of Sciences, ul. M. Sklodowskiej-Curie 34, 41-819, Zabrze

2015-12-31

The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF{sub 3}-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effectivemore » extraction solvents for liquid-liquid extraction of DyF{sub 3} were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests.« less

Dy3+ doped cubic zirconia nanostructures prepared via ultrasound route for display applications

NASA Astrophysics Data System (ADS)

Yadav, H. J. Amith; Eraiah, B.; Nagabhushana, H.; Basavaraj, R. B.; Deepthi, N. H.

2017-05-01

White light emitting dysprosium (Dy) doped Zirconia (ZrO2) nanostructures were prepared first time via ultrasound assisted sonochemical synthesis route using cetyltrimethylammonium bromide (CTAB) surfactant. The obtained product was well characterized. The powder X-ray diffraction (PXRD) profiles confirmed that the product was highly crystalline in nature with cubic phase. Various reaction parameters such as, effect of sonication time, concentration of the surfactant was studied in detail. Diffuse reflectance spectroscopy (DRS) was studied to evaluate the band gap energy of the products and the values were found in the range of 4.13 - 4.53 eV. The particle size was estimated by transmission electron microscope (TEM) and it was found in the range of 10-20 nm. Photoluminescence (PL) properties were studied in detail by recording emission spectra of all the Dy doped Zirconia nanostructures at an excitation wavelength of 350 nm. The emission peaks were observed at 480, 574 and 666 nm which corresponds to Dy3+ ion transitions. The 3 mol% Dy3+ doped ZrO2 nanostructures showed maximum intensity. Further photometric measurements were done by evaluating, Commission International De I-Eclairage (CIE) and correlated color temperature (CCT). From CIE it was observed that the color coordinates lies in white region. The color purity and quantum efficiency were also estimated and the results indicate that the nanophosphor obtained in this route can be used in preparing solid state lighting application.

Near white light emitting ZnAl{sub 2}O{sub 4}:Dy{sup 3+} nanocrystals: Sol–gel synthesis and luminescence studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Mithlesh, E-mail: mithlesh@barc.gov.in; Gupta, Santosh K.; Kadam, R.M.

2016-02-15

Highlights: • ZnAl{sub 2}O{sub 4}:Dy{sup 3+} spinel synthesized using sol–gel method. • Characterized by XRD, SEM and PL spectroscopy. • Investigations of emission, excitation and lifetime properties. • Evaluation of defect centers and trap parameters of the system. • Evaluation of CIE indices of near white light emitting phosphor. - Abstract: ZnAl{sub 2}O{sub 4}:Dy{sup 3+} nanoparticles were synthesized using citrate sol–gel method and characterized systematically using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. Emission spectrum of pure ZnAl{sub 2}O{sub 4} shows intense violet blue emission under ultra violet irradiation. Based on electron paramagnetic resonance (EPR) results; it was attributedmore » to presence of singly ionized oxygen vacancy centres in ZnAl{sub 2}O{sub 4}. On doping Dy{sup 3+} in ZnAl{sub 2}O{sub 4}, complete host–dopant energy transfer does not take place. Local structural investigation and lifetime measurements reveal that dysprosium ion is distributed between both Zn{sup 2+} and Al{sup 3+} sites. Near white light from ZnAl{sub 2}O{sub 4}:Dy{sup 3+} is attributed to combined host and dopant luminescence. The trap parameters such as activation energy (E) and frequency factor (s) for TSL glow peak 165 °C were determined using different heating rate method. Thermally stimulated emission showed the presence of oxygen related defect centre.« less

Dielectric spectroscopy of Dy2O3 doped (K0.5Na0.5)NbO3 piezoelectric ceramics

NASA Astrophysics Data System (ADS)

Mahesh, P.; Subhash, T.; Pamu, D.

2014-06-01

We report the dielectric properties of ( K 0.5 Na 0.5 ) NbO 3 ceramics doped with x wt% of Dy 2 O 3 (x= 0.0-1.5 wt%) using the broadband dielectric spectroscopy. The X-ray diffraction studies showed the formation of perovskite structure signifying that Dy 2 O 3 diffuse into the KNN lattice. Samples doped with x > 0.5 wt% exhibit smaller grain size and lower relative densities. The dielectric properties of KNN ceramics doped with Dy 2 O 3 are enhanced by increasing the Dy 3+ content; among the compositions studied, x = 0.5 wt% exhibited the highest dielectric constant and lowest loss at 1MHz over the temperature range of 30°C to 400°C. All the samples exhibit maximum dielectric constant at the Curie temperature (˜ 326°C) and a small peak in the dielectric constant at around 165°C is due to a structural phase transition. At the request of all authors, and by agreement with the Proceedings Editors, a corrected version of this article was published on 19 June 2014. The full text of the Corrigendum is attached to the corrected article PDF file.

Dyeing regions of oxidative hair dyes in human hair investigated by nanoscale secondary ion mass spectrometry.

PubMed

Kojima, Toru; Yamada, Hiromi; Yamamoto, Toshihiko; Matsushita, Yasuyuki; Fukushima, Kazuhiko

2013-06-01

To develop more effective oxidative hair coloring products, it is important to understand the localization of colored chromophores, which are formed from oxidative dyes, in the fine structure of hair. However, the dyeing regions of oxidative hair dyes in the fine structure of hair have not been extensively examined. In this study, we investigated the distribution and localization of colored chromophores formed by an oxidative hair coloring product in the fine structure of human hair by using a stable isotope-labeled oxidative dye with nanoscale secondary ion mass spectrometry (NanoSIMS). First, formation of the colored chromophore from a deuterium-labeled oxidative dye was examined by visible spectra similarly to a study of its formation using nonlabeled oxidative dye. Furthermore, the formation of binuclear indo dye containing deuterium in its chemical structure was confirmed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis. As a result of the NanoSIMS image on a cross-sectional dyed hair, although deuterium ions were detected in whole hair cross-section, quite a few of them were detected at particulate regions. These particulate regions of the dyed black hair in which deuterium ions were intensely detected were identified as melanin granules, by comparing the dyeing behaviors of black and white hair. NanoSIMS analysis revealed that melanin granules of black human hair are important dyeing regions in oxidative hair coloring. Copyright © 2013 Elsevier B.V. All rights reserved.

Observing quantum control of up-conversion luminescence in Dy3+ ion doped glass from weak to intermediate shaped femtosecond laser fields

NASA Astrophysics Data System (ADS)

Liu, Pei; Cheng, Wenjing; Yao, Yunhua; Xu, Cheng; Zheng, Ye; Deng, Lianzhong; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

2017-11-01

Controlling the up-conversion luminescence of rare-earth ions in real-time, in a dynamical and reversible manner, is very important for their application in laser sources, fiber-optic communications, light-emitting diodes, color displays and biological systems. In previous studies, the up-conversion luminescence control mainly focused on the weak femtosecond laser field. Here, we further extend this control behavior from weak to intermediate femtosecond laser fields. In this work, we experimentally and theoretically demonstrate that the up-conversion luminescence in Dy3+ ion doped glass can be artificially controlled by a π phase step modulation, but the up-conversion luminescence control behavior will be affected by the femtosecond laser intensity, and the up-conversion luminescence is suppressed by lower laser intensity while enhanced by higher laser intensity. We establish a new theoretical model (i.e. the fourth-order perturbation theory) to explain the physical control mechanism by considering the two- and four-photon absorption processes, and the theoretical results show that the relative weight of four-photon absorption in the whole excitation process will increase with the increase in laser intensity, and the interference between two- and four-photon absorptions results in up-conversion luminescence control modulation under different laser intensities. These theoretical and experimental works can provide a new method to control and understand up-conversion luminescence in rare-earth ions, and also may open a new opportunity to the related application areas of rare-earth ions.

Investigating the influence of sea level oscillations in the Danish Straits on the Baltic Sea dynamics

NASA Astrophysics Data System (ADS)

Tikhonova, Natalia; Gusev, Anatoly; Diansky, Nikolay; Zakharchuk, Evgeny

2016-04-01

In this research, we study the influence of dynamic processes in the Danish Straits on the sea surface height (SSH) oscillations in the Baltic Sea. For this purpose, we use the model of marine and oceanic circulation INMOM (Institute of Numerical Mathematics Ocean Model). The simulations were carried out for the period 2009-2010, and the coastal station data were used for verification of SSH modelling quality. Comparison of the simulated data with the ones measured in the coastal points showed us that the model does not describe SSH variability in different areas of the Baltic Sea well enough, so in the following simulation series the in situ SSH data of the coastal measurements were assimilated at the open boundary in the Danish Straits. The results of the new simulation showed us that this approach significantly increases the SSH simulation quality in all areas of the sea, where the comparison was made. In particular, the correlation coefficients between the simulated and measured SSH data increased from 0.21-0.73 to 0.81-0.90. On the basis of these results, it has been suggested that the Baltic Sea SSH variability is largely determined by the influence of the dynamic processes in the Danish Straits, which can be represented as a superposition of oscillations of different space-time scales. These oscillations can either be generated in the straits themselves, or propagate from the North Sea. For verification of this hypothesis and assessment of the oscillation propagation distance in the Baltic Sea, the following experiment was performed. At the open boundary in the Danish Straits, the six harmonics were set with the following parameters: the periods are 1.5, 3.0, 6.0, 13.5, 40.5, and 121.5 days, and the amplitude for all the harmonics is 50 cm. The results showed us that the prescribed harmonic oscillations at the open boundary propagate into all areas of the sea without changing the frequency, but with decreasing amplitude. The decrease in amplitude is not related to the distance between the measurement point and open boundary. For example, in the Gulfs of Finland and Riga, the 36hr harmonic has an amplitude substantially higher than in the open sea, and in the Stockholm area, this harmonic is at the noise level. The 40dy and 121dy harmonics have slightly lower amplitudes than the original prescribed signal, but they are almost unchanged while propagating further into the sea, and in all the investigated locations have almost identical peaks of spectral density. The 3dy and 6dy harmonics significantly lost their amplitude in all parts of the sea, and spectral density peaks are at the noise level. The simulation results showed us that the Danish straits do not filter 121dy and 40dy oscillations, and their amplitude does not decrease much. The 13dy, 6dy and 3dy oscillations significantly lose in amplitude and have no significant peaks of the spectral density. The 1.5dy harmonic propagates to the Gulfs of Finland and Riga, and increases in amplitude due to resonance at the natural frequency of the basin. It is suggested that, while Danish straits do not filter or transform frequency characteristics of oscillations propagated from the North Sea, but the Baltic Sea configuration may affect the magnitude and propagation extent of these oscillations. Thus, the fluctuations in the North Sea and the Danish Straits can significantly contribute to the Baltic Sea dynamics in the low-frequency range of the spectrum, and the periods of natural oscillations of the basin. The research was supported by the Russian Foundation for Basic Research (grant № 16-05-00534) and Saint-Petersburg State University (grant №18.37.140.2014)

Comparison of the Supercooled Spin Liquid States in the Pyrochlore Magnets Dy2Ti2O7 and Ho2Ti2O7

NASA Astrophysics Data System (ADS)

Eyal, Anna; Eyvazov, Azar B.; Dusad, Ritika; Munsie, Timothy J. S.; Luke, Graeme M.; Davis, J. C. Séamus

Despite a well-ordered crystal structure and strong magnetic interactions between the Dy or Ho ions, no long-range magnetic order has been detected in the pyrochlore titanates Ho2Ti2O7 and Dy2Ti2O7. The low temperature state in these materials is governed by spin-ice rules. These constrain the Ising like spins in the materials, yet does not result in a global broken symmetry state. To explore the actual magnetic phases, we simultaneously measure the time- and frequency-dependent magnetization dynamics of Dy2Ti2O7 and Ho2Ti2O7 using toroidal, boundary-free magnetization transport techniques. We demonstrate a distinctive behavior of the magnetic susceptibility of both compounds, that is indistinguishable in form from the permittivity of supercooled dipolar liquids. Moreover, we show that the microscopic magnetic relaxation times for both materials increase along a super-Arrhenius trajectory also characteristic of supercooled glass-forming liquids. Both materials therefore exhibit characteristics of a supercooled spin liquid. Strongly-correlated dynamics of loops of spins is suggested as a possible mechanism which could account for these findings. Potential connections to many-body spin localization will also be discussed.

Magnetocaloric properties of rare-earth substituted DyCrO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDannald, A.; Jain, M., E-mail: menka.jain@uconn.edu; Department of Physics, University of Connecticut, Storrs, Connecticut 06269

Recently, there has been a focus on the need for efficient refrigeration technology without the use of expensive or harmful working fluids, especially at temperatures below 30 K. Solid state refrigeration, based on the magnetocaloric effect, provides a possible solution to this problem. The rare-earth chromites (RCrO{sub 3}), especially DyCrO{sub 3}, with its large magnetic moment dysprosium ion, are potential candidates for such an application. The Dy{sup 3+} ordering transition at low temperatures (<10 K) likely causes a large magnetocaloric response in this material. This study investigates the possibility of tuning the magnetocaloric properties through the use of rare-earth substitution. Both Y{supmore » 3+} and Ho{sup 3+} substitutions were found to decrease the magnetocaloric response by disrupting the R{sup 3+} ordering. Whereas Er{sup 3+} substitution was found to increase the magnetocaloric response, likely due to an increase in the R{sup 3+} ordering temperature. The large magnetocaloric entropy change of Er{sup 3+} substituted DyCrO{sub 3} (10.92 J/kg K with a relative cooling power of 237 J/kg at 40 kOe and 5 K) indicates that this material system is well suited for low temperature (<30 K) solid state refrigeration applications.« less

Manipulation of Dirac cones in intercalated epitaxial graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Minsung; Tringides, Michael C.; Hershberger, Matthew T.

Graphene is an intriguing material in view of its unique Dirac quasi-particles, and the manipulation of its electronic structure is important in material design and applications. Here, we theoretically investigate the electronic band structure of epitaxial graphene on SiC with intercalation of rare earth metal ions (e.g., Yb and Dy) using first-principles calculations. We can use the intercalation to control the coupling of the constituent components (buffer layer, graphene, and substrate), resulting in strong modification of the graphene band structure. We also demonstrate that the metal-intercalated epitaxial graphene has tunable band structures by controlling the energies of Dirac cones asmore » well as the linear and quadratic band dispersion depending on the intercalation layer and density. Thus, the metal intercalation is a viable method to manipulate the electronic band structure of the epitaxial graphene, which can enhance the functional utility and controllability of the material.« less

Manipulation of Dirac cones in intercalated epitaxial graphene

DOE PAGES

Kim, Minsung; Tringides, Michael C.; Hershberger, Matthew T.; ...

2017-07-12

Graphene is an intriguing material in view of its unique Dirac quasi-particles, and the manipulation of its electronic structure is important in material design and applications. Here, we theoretically investigate the electronic band structure of epitaxial graphene on SiC with intercalation of rare earth metal ions (e.g., Yb and Dy) using first-principles calculations. We can use the intercalation to control the coupling of the constituent components (buffer layer, graphene, and substrate), resulting in strong modification of the graphene band structure. We also demonstrate that the metal-intercalated epitaxial graphene has tunable band structures by controlling the energies of Dirac cones asmore » well as the linear and quadratic band dispersion depending on the intercalation layer and density. Thus, the metal intercalation is a viable method to manipulate the electronic band structure of the epitaxial graphene, which can enhance the functional utility and controllability of the material.« less

Magnetic properties of rare-earth-doped La0.7Sr0.3MnO3.

PubMed

Veverka, Pavel; Kaman, Ondřej; Knížek, Karel; Novák, Pavel; Maryško, Miroslav; Jirák, Zdeněk

2017-01-25

Rare-earth-doped ferromagnetic manganites La 0.63 RE 0.07 Sr 0.30 MnO 3 (RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles. Non-zero moments are also detected at the perovskite A sites, which can be attributed to magnetic polarization of the rare-earth dopants. The measurements in external field up to 70 kOe show a standard Curie-type contribution of the spin-only moments of Gd 3+ ions, whereas Kramers ions Dy 3+ and non-Kramers ions Ho 3+ contribute by Ising moments due to their doublet ground states. The behaviour of non-Kramers ions Tb 3+ is anomalous, pointing to singlet ground state with giant Van Vleck paramagnetism. The Tb 3+ doping leads also to a notably increased coercivity compared to other La 0.63 RE 0.07 Sr 0.30 MnO 3 systems.

Enhancing the Photocatalytic Activity of Sr4 Al14 O25 : Eu2+ , Dy3+ Persistent Phosphors by Codoping with Bi3+ Ions.

PubMed

García, Carlos R; Oliva, Jorge; Romero, Maria Teresa; Diaz-Torres, Luis A

2016-03-01

The photocatalytic activity of Bismuth-codoped Sr 4 Al 14 O 25 : Eu 2+ , Dy 3+ persistent phosphors is studied by monitoring the degradation of the blue methylene dye UV light irradiation. Powder phosphors are obtained by a combustion synthesis method and a postannealing process in reductive atmosphere. The XRD patterns show a single orthorhombic phase Sr 4 Al 14 O 25 : Eu 2+ , Dy 3+ , Bi 3+ phosphors even at high Bismuth dopant concentrations of 12 mol%, suggesting that Bi ions are well incorporated into the host lattice. SEM micrographs show irregular micrograins with sizes in the range of 0.5-20 μm. The samples present an intense greenish-blue fluorescence and persistent emissions at 495 nm, attributed to the 5d-4f allowed transitions of Eu 2+ . The fluorescence decreases as Bi concentration increases; that suggest bismuth-induced traps formation that in turn quench the luminescence. The photocatalytic evaluation of the powders was studied under both 365 nm UV and solar irradiations. Sample with 12 mol% of Bi presented the best MB degradation activity; 310 min of solar irradiation allow 100% MB degradation, whereas only 62.49% MB degradation is achieved under UV irradiation. Our results suggest that codoping the persistent phosphors with Bi 3+ can be an alternative to enhance their photocatalytic activity. © 2016 The American Society of Photobiology.

Transition metal redox switches for reversible "on/off" and "slow/fast" single-molecule magnet behaviour in dysprosium and erbium bis-diamidoferrocene complexes.

PubMed

Dickie, Courtney M; Laughlin, Alexander L; Wofford, Joshua D; Bhuvanesh, Nattamai S; Nippe, Michael

2017-12-01

Single-molecule magnets (SMMs) are considered viable candidates for next-generation data storage and quantum computing. Systems featuring switchability of their magnetization dynamics are particularly interesting with respect to accessing more complex logic gates and device architectures. Here we show that transition metal based redox events can be exploited to enable reversible switchability of slow magnetic relaxation of magnetically anisotropic lanthanide ions. Specifically, we report anionic homoleptic bis-diamidoferrocene complexes of Dy 3+ (oblate) and Er 3+ (prolate) which can be reversibly oxidized by one electron to yield their respective charge neutral redox partners (Dy: [1] - , 1 ; Er: [2] - , 2 ). Importantly, compounds 1 and 2 are thermally stable which allowed for detailed studies of their magnetization dynamics. We show that the Dy 3+ [1] - / 1 system can function as an "on"/"off" or a "slow"/"fast" redox switchable SMM system in the absence or presence of applied dc fields, respectively. The Er 3+ based [2] - / 2 system features "on"/"off" switchability of SMM properties in the presence of applied fields. Results from electrochemical investigations, UV-vis-NIR spectroscopy, and 57 Fe Mössbauer spectroscopy indicate the presence of significant electronic communication between the mixed-valent Fe ions in 1 and 2 in both solution and solid state. This comparative evaluation of redox-switchable magnetization dynamics in low coordinate lanthanide complexes may be used as a potential blueprint toward the development of future switchable magnetic materials.

Synthesis, luminescence, and energy-transfer properties of β-Na2Ca4(PO4)2(SiO4):A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors.

PubMed

Li, Kai; Shang, Mengmeng; Geng, Dongling; Lian, Hongzhou; Zhang, Yang; Fan, Jian; Lin, Jun

2014-07-07

A series of β-Na2Ca4(PO4)2(SiO4) (β-NCPS):A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors were prepared via a high-temperature solid-state reaction route. The X-ray diffraction, Fourier transform infrared, photoluminescence (PL), cathodoluminescence (CL) properties, fluorescent lifetimes, and absolute quantum yield were exploited to characterize the samples. Under UV radiation, the β-NCPS:Eu(2+) phosphors present bright green emissions, and the β-NCPS:Ce(3+) phosphors show strong blue emissions, which are attributed to their 4f(6)5d(1) → 4f(7) and 5d-4f allowed transitions, respectively. The β-NCPS:Ce(3+), Tb(3+) phosphors display intense tunable color from blue to green and high absolute quantum yields (81% for β-NCPS:0.12Ce(3+) and 83% for β-NCPS:0.12Ce(3+), 0.08Tb(3+)) when excited at 365 nm. Simultaneously, the energy transfer from Ce(3+) to Tb(3+) ions is deduced from the spectral overlap between Ce(3+) emission and Tb(3+) excitation spectra and demonstrated by the change of emission spectra and decay lifetimes. Moreover, the energy-transfer mechanism from Ce(3+) to Tb(3+) ions is confirmed to be exchange interaction according to the discussion of expression from Dexter and Reisfeld. Under a low-voltage electron-beam excitation, the β-NCPS:A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors exhibit their characteristic emissions, and the emission profiles of β-NCPS:Ce(3+),Tb(3+) phosphors are obviously different from those of the PL spectra; this difference might be ascribed to their different luminescence mechanisms. These results in PL and CL properties suggest that β-NCPS:A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors are potential candidates for solid-state lighting and field-emission displays.

``Smart'' theranostic lanthanide nanoprobes with simultaneous up-conversion fluorescence and tunable T1-T2 magnetic resonance imaging contrast and near-infrared activated photodynamic therapy

NASA Astrophysics Data System (ADS)

Zhang, Yan; Das, Gautom Kumar; Vijayaragavan, Vimalan; Xu, Qing Chi; Padmanabhan, Parasuraman; Bhakoo, Kishore K.; Tamil Selvan, Subramanian; Tan, Timothy Thatt Yang

2014-10-01

The current work reports a type of ``smart'' lanthanide-based theranostic nanoprobe, NaDyF4:Yb3+/NaGdF4:Yb3+,Er3+, which is able to circumvent the up-converting poisoning effect of Dy3+ ions to give efficient near infrared (980 nm) triggered up-conversion fluorescence, and offers not only excellent dark T2-weighted MR contrast but also tunable bright and T1-weighted MR contrast properties. Due to the efficient up-converted energy transfer from the nanocrystals to chlorin e6 (Ce6) photosensitizers loaded onto the nanocrystals, cytotoxic singlet oxygen was generated and photodynamic therapy was demonstrated. Therefore, the current multifunctional nanocrystals could be potentially useful in various image-guided diagnoses where bright or dark MRI contrast could be selectively tuned to optimize image quality, but also as an efficient and more penetrative near-infrared activated photodynamic therapy agent.The current work reports a type of ``smart'' lanthanide-based theranostic nanoprobe, NaDyF4:Yb3+/NaGdF4:Yb3+,Er3+, which is able to circumvent the up-converting poisoning effect of Dy3+ ions to give efficient near infrared (980 nm) triggered up-conversion fluorescence, and offers not only excellent dark T2-weighted MR contrast but also tunable bright and T1-weighted MR contrast properties. Due to the efficient up-converted energy transfer from the nanocrystals to chlorin e6 (Ce6) photosensitizers loaded onto the nanocrystals, cytotoxic singlet oxygen was generated and photodynamic therapy was demonstrated. Therefore, the current multifunctional nanocrystals could be potentially useful in various image-guided diagnoses where bright or dark MRI contrast could be selectively tuned to optimize image quality, but also as an efficient and more penetrative near-infrared activated photodynamic therapy agent. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01717j

Evaluating the electronic structure of formal Ln II ions in Ln II(C 5H 4SiMe 3) 3 1– using XANES spectroscopy and DFT calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fieser, Megan E.; Ferrier, Maryline Ghislaine; Su, Jing

Here, the isolation of [K(2.2.2-cryptand)][Ln(C 5H 4SiMe 3) 3], formally containing LnII, for all lanthanides (excluding Pm) was surprising given that +2 oxidation states are typically regarded as inaccessible for most 4f-elements. Herein, X-ray absorption near-edge spectroscopy (XANES), ground-state density functional theory (DFT), and transition dipole moment calculations are used to investigate the possibility that Ln(C 5H 4SiMe 3) 3 1– (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) compounds represented molecular Ln II complexes. Results from the ground-state DFT calculations were supported by additional calculations that utilized complete-active-space multi-configuration approach with second-ordermore » perturbation theoretical correction (CASPT2). Through comparisons with standards, Ln(C 5H 4SiMe 3) 3 1– (Ln = Sm, Tm, Yb, Lu, Y) are determined to contain 4f 6 5d 0 (Sm II), 4f 13 5d 0 (Tm II), 4f 14 5d 0 (Yb II), 4f 14 5d 1 (Lu II), and 4d 1 (Y II) electronic configurations. Additionally, our results suggest that Ln(C 5H 4SiMe 3) 3 1– (Ln = Pr, Nd, Gd, Tb, Dy, Ho, and Er) also contain Ln II ions, but with 4f n 5d 1 configurations (not 4f n +1 5d 0). In these 4f n 5d 1 complexes, the C 3h-symmetric ligand environment provides a highly shielded 5d-orbital of a' symmetry that made the 4f n 5d 1 electronic configurations lower in energy than the more typical 4f n+1 5d 0 configuration.« less

Evaluating the electronic structure of formal Ln II ions in Ln II(C 5H 4SiMe 3) 3 1– using XANES spectroscopy and DFT calculations

DOE PAGES

Fieser, Megan E.; Ferrier, Maryline Ghislaine; Su, Jing; ...

2017-06-30

Here, the isolation of [K(2.2.2-cryptand)][Ln(C 5H 4SiMe 3) 3], formally containing LnII, for all lanthanides (excluding Pm) was surprising given that +2 oxidation states are typically regarded as inaccessible for most 4f-elements. Herein, X-ray absorption near-edge spectroscopy (XANES), ground-state density functional theory (DFT), and transition dipole moment calculations are used to investigate the possibility that Ln(C 5H 4SiMe 3) 3 1– (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) compounds represented molecular Ln II complexes. Results from the ground-state DFT calculations were supported by additional calculations that utilized complete-active-space multi-configuration approach with second-ordermore » perturbation theoretical correction (CASPT2). Through comparisons with standards, Ln(C 5H 4SiMe 3) 3 1– (Ln = Sm, Tm, Yb, Lu, Y) are determined to contain 4f 6 5d 0 (Sm II), 4f 13 5d 0 (Tm II), 4f 14 5d 0 (Yb II), 4f 14 5d 1 (Lu II), and 4d 1 (Y II) electronic configurations. Additionally, our results suggest that Ln(C 5H 4SiMe 3) 3 1– (Ln = Pr, Nd, Gd, Tb, Dy, Ho, and Er) also contain Ln II ions, but with 4f n 5d 1 configurations (not 4f n +1 5d 0). In these 4f n 5d 1 complexes, the C 3h-symmetric ligand environment provides a highly shielded 5d-orbital of a' symmetry that made the 4f n 5d 1 electronic configurations lower in energy than the more typical 4f n+1 5d 0 configuration.« less

Sensitivity of magnetic properties to chemical pressure in lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li

NASA Astrophysics Data System (ADS)

Mukherjee, P.; Sackville Hamilton, A. C.; Glass, H. F. J.; Dutton, S. E.

2017-10-01

A systematic study of the structural and magnetic properties of three-dimensionally frustrated lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li is presented. Garnets with Ln  =  Gd show magnetic behaviour consistent with isotropic Gd3+ spins; no magnetic ordering is observed for T  ⩾  0.4 K. Magnetic ordering features are seen for garnets with Ln  =  Tb, Dy, Ho in the temperature range 0.4  <  T  <  2.5 K, however the nature of the magnetic ordering varies for the different Ln as well as for different combinations of A and X. The magnetic behaviour can be explained by tuning of the magnetic interactions and changes in the single-ion anisotropy. The change in magnetic entropy is evaluated from isothermal magnetisation measurements to characterise the magnetocaloric effect in these materials. Among the Gd garnets, the maximum change in magnetic entropy per mole (15.45 J K-1 molGd-1 ) is observed for Gd3Sc2Ga3O12 at 2 K, in a field of 9 T. The performance of Dy3Ga5O12 as a magnetocaloric material surpasses the other garnets with Ln  =  Tb, Dy, Ho.

Informatics-Aided Density Functional Theory Study on the Li Ion Transport of Tavorite-Type LiMTO4F (M(3+)-T(5+), M(2+)-T(6+)).

PubMed

Jalem, Randy; Kimura, Mayumi; Nakayama, Masanobu; Kasuga, Toshihiro

2015-06-22

The ongoing search for fast Li-ion conducting solid electrolytes has driven the deployment surge on density functional theory (DFT) computation and materials informatics for exploring novel chemistries before actual experimental testing. Existing structure prototypes can now be readily evaluated beforehand not only to map out trends on target properties or for candidate composition selection but also for gaining insights on structure-property relationships. Recently, the tavorite structure has been determined to be capable of a fast Li ion insertion rate for battery cathode applications. Taking this inspiration, we surveyed the LiMTO4F tavorite system (M(3+)-T(5+) and M(2+)-T(6+) pairs; M is nontransition metals) for solid electrolyte use, identifying promising compositions with enormously low Li migration energy (ME) and understanding how structure parameters affect or modulate ME. We employed a combination of DFT computation, variable interaction analysis, graph theory, and a neural network for building a crystal structure-based ME prediction model. Candidate compositions that were predicted include LiGaPO4F (0.25 eV), LiGdPO4F (0.30 eV), LiDyPO4F (0.30 eV), LiMgSO4F (0.21 eV), and LiMgSeO4F (0.11 eV). With chemical substitutions at M and T sites, competing effects among Li pathway bottleneck size, polyanion covalency, and local lattice distortion were determined to be crucial for controlling ME. A way to predict ME for multiple structure types within the neural network framework was also explored.

Magneto-optical properties of nanometer crystal giant magneto-optical BiAlDyIG thin film materials post-treated by rapid recurrent thermal annealing method

NASA Astrophysics Data System (ADS)

Qing-hui, Yang; Huai-wu, Zhang; Ying-li, Liu; Qiye, Wen

2014-05-01

In this paper, high quality BiAlDyIG thin films with different bismuth contents have been prepared by using a sol-gel method and post-treated by a rapid recurrent thermal annealing (RRTA) method. Results indicate that the RRTA method improves the Faraday Effect of the films notably, a maximum Faraday angle of -4.9° in the 450 nm thickness film (Bi1.96Dy1.04Fe4AlO12) was obtained at the wavelength of 520 nm, which is about two times larger than that of the common thermal annealed sample, and furthermore the reason of giant Faraday angle was also analyzed in detail. These results are potentially helpful to improve the recording density and signal-to-noise ratio of magneto-optical disk.

Studies of magnetostriction and spin polarized band structures of rare earth intermetallics

NASA Technical Reports Server (NTRS)

Wallace, W. E.

1979-01-01

Anisotropic magnetostriction measurements of R6Fe23, R = (Tb, Dy, Ho, and Er) were carried out from 77 K to room temperature. Magnetic fields up to 2.1 Tesla were applied. All the compounds exhibited large magnetostrictions at 77 K, the largest effect being obtained for Tb6Fe23. Saturation magnetostriction values for the compounds were also determined for 77 K and room temperature. Results of the temperature dependence of magnetostriction for Er6Fe23 are in good agreement with Callen and Callen's single ion theory. Therefore, the main sources of magnetostriction in this compound is the Er ion. The spin-up and spin-down electronic energy bands, the density of states and the magnetic moments of YCo5, SmCo5, and GdCo5 were calculated by the spin polarized augmented plane wave technique. The calculations obtained show the origin of the moment, provide good estimates of its magnitude and variation, and the reasons for those variations. They also show the important role of partial charge transfer and of d-d electronic coupling. Calculations for LaNi5 and GdNi5 systems are discussed.

Lightweight high performance ceramic material

DOEpatents

Nunn, Stephen D [Knoxville, TN

2008-09-02

A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

Materials Data on DyTh (SG:221) by Materials Project

DOE Data Explorer

Kristin Persson

2014-11-02

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyNi (SG:62) by Materials Project

DOE Data Explorer

Kristin Persson

2015-01-27

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Thermoluminescent Mechanisms in Calcium Sulphate Doped with Dysprosium.

NASA Astrophysics Data System (ADS)

Matthews, Robert James

Thermoluminescent (TL) mechanisms in CaSO(,4):Dy caused by ionizing irradiation are investigated. Influences of the background impurities on the structure of the glow curve are determined and are correlated with known electron spin resonance (ESR) results. These are combined with fading studies that determine the TL process as bimolecular or monomolecular and the order of the kinetics involved. The TL emission spectrum is determined for all temperature regions of the TL emission to 400(DEGREES)C; optical absorption (OA) in the visible provides information on the valence state of the Dy ion. Photo stimulated transfer of TL (PTTL) helps determine the influence of traps deeper than 400(DEGREES)C, while studies of CaSO(,4):Dy in the scanning electron microscope (SEM) operated in the cathodoluminescent (CL) mode provide information on processes occurring during electron bombardment and on the distribution of Dy in CaSO(,4). The information from these studies is combined to form comprehensive models of the TL mechanisms responsible for the TL glow peaks.(,). The glow peak occurring between 130(DEGREES)C and 260(DEGREES)C, usually designated as the dosimetric peak, was determined to be the result of two primary processes. In the first mechanism, the SO(,3)('-) radical recombines with an oxygen interstitial (O(,i)('-)) associated with the Dy('3+) in charge compensation. The recombination energy is given up as TL. In the second mechanism, it is concluded that divalent Dy release electrons to the conduction band in a non-radiative process. The liberated electron recombines with a hole center at a remote SO(,4)(' -) site. The recombination energy is either transferred to trivalent Dy, which emits TL, or this energy causes the (SO(,4)('-))* to disassociate and form an SO(,3)(' -) and an O(,i)('-). These defects are thought to recombine at about 300(DEGREES)C. In the low temperature region (room temperature to 130(DEGREES)C), the monovalent cation, particularly Na('+) acting as charge compensation for the trivalent Dy, stabilizes the SO(,4)('-) radical and the SO(,2)(' -) radical produced during irradiation. These are determined to be monomolecular type defect comples. The TL mechanisms proposed for the dosimetric region (130(DEGREES)C - 260(DEGREES)C) and the low temperature region (RT - 130(DEGREES)C) are those most consistent with all the results of the various methods of research.

Local magnetic moment formation at 119Sn Mössbauer impurity in RCo2 (R=Gd,Tb,Dy,Ho,Er) Laves phase compounds

NASA Astrophysics Data System (ADS)

de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

2008-04-01

In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.

Bis(μ-2-{[2-(1,3-benzothia­zol-2-yl)hydrazinyl­idene]meth­yl}-6-meth­oxy­phenolato)bis­[dinitratodysprosium(III)] methanol disolvate

PubMed Central

Xu, Xuebin; Ding, Shuai; Shen, Si; Tang, Jinkui; Liu, Zhiliang

2011-01-01

In the centrosymmetric dinuclear title compound, [Dy2(C15H12N3O2S)2(NO3)4]·2CH3OH, the two DyIII atoms are coordinated by two deprotonated 2-{[2-(1,3-benzothia­zol-2-yl)hydrazinyl­idene]meth­yl}-6-meth­oxy­phenol ligands and four nitrate ions, all of which are chelating. The crystal packing is stabilized by inter­molecular N—H⋯O hydrogen bonds and weak O—H⋯O inter­actions, forming a two-dimensional network parallel to (010). PMID:21754674

Absorption of Dy3+ and Nd3+ ions in Ba R 2F8 single crystals

NASA Astrophysics Data System (ADS)

Apollonov, V. V.; Pushkar', A. A.; Uvarova, T. V.; Chernov, S. P.

2008-09-01

The Dy3+ absorption and excitation spectra of BaY2F8 and BaYb2F8 single crystals are investigated in the ultraviolet, vacuum ultraviolet, and visible ranges at a temperature of 300 K. These crystals exhibit intense broad absorption bands due to the spin-allowed 4 f-5 d transitions in the range (56-78) × 10-3 cm-1 and less intense absorption bands that correspond to the spin-forbidden transitions in the range (50-56) × 10-3 cm-1. The Nd3+ absorption spectra of BaY2F8 single crystals are studied in the range (34-82) × 10-3 cm-1 at 300 K for different crystal orientations.

Chemical environment of rare earth ions in Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glass-ceramics doped with Dy{sup 3+}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Rongping, E-mail: rongping.wang@anu.edu.au; Yan, Kunlun; Luther-Davies, Barry

2015-10-19

We have annealed Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga{sub 2}S{sub 3} crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga{sub 2}S{sub 3} crystalline grains. From the unchanged lineshape of the emissions at 2.9 andmore » 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga{sub 2}S{sub 3} crystals.« less

Series of edge-sharing bi-triangle Ln4 clusters with a μ4-NO3- bridge: syntheses, structures, luminescence, and the SMM behavior of the Dy4 analogue.

PubMed

Zou, Hua-Hong; Wang, Rong; Chen, Zi-Lu; Liu, Dong-Cheng; Liang, Fu-Pei

2014-02-14

A series of Ln4 clusters, [Ln4L2(μ3-OH)2(μ4-NO3)(NO3)4(OCH3)(H2O)]·xMeCN·yMeOH (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5), Yb (6), L = 2-{[2-(2-hydroxy-ethoxy)-ethylimino]-methyl}-6-methoxyphenol), have been synthesized by the reaction of Ln(NO)3 and a Schiff-base ligand formed in situ. The six complexes display similar structures, with an overall metal core comprising two edge-sharing triangular Ln3 units linked by a μ4-NO3(-) bridge. The luminescence spectrum of complex 2 shows the characteristic emission of the Tb(III) ions. The magnetic susceptibility studies reveal that the Ln(III) ions are very weakly interacting in all six compounds. Frequency dependence of the ac-susceptibility was found for 3, suggesting a typical single-molecule magnet (SMM) behavior with an anisotropic barrier of 28 K.

Observation of short range order driven large refrigerant capacity in chemically disordered single phase compound Dy2Ni0.87Si2.95.

PubMed

Pakhira, Santanu; Mazumdar, Chandan; Choudhury, Dibyasree; Ranganathan, R; Giri, S

2018-05-16

In this work, we report the successful synthesis of a new intermetallic compound Dy2Ni0.87Si2.95 forming in single phase only with a chemically disordered structure. The random distribution of Ni/Si and crystal defects create a variation in the local electronic environment between the magnetic Dy ions. In the presence of both disorder and competing exchange interactions driven magnetic frustration, originating due to c/a ∼ 1, the compound undergoes spin freezing behaviour below 5.6 K. In the non-equilibrium state below the spin freezing behaviour, the compound exhibits aging phenomena and magnetic memory effects. In the magnetically short-range ordered region, much above the freezing temperature, an unusual occurrence of considerable magnetic entropy change, -ΔSmaxM ∼ 21 J kg-1 K-1 with large cooling power RCP ∼ 531 J kg-1 and adiabatic temperature change, ΔTad ∼ 10 K for a field change of 70 kOe, is observed for this short range ordered cluster-glass compound without any magnetic hysteresis loss.

Assessing the exchange coupling in binuclear lanthanide(iii) complexes and the slow relaxation of the magnetization in the antiferromagnetically coupled Dy2 derivative† †Electronic supplementary information (ESI) available: Additional magnetic data, additional figures and computational details. CCDC 1020818–1020822. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01029b

PubMed Central

Chow, Chun Y.; Bolvin, Hélène; Campbell, Victoria E.; Guillot, Régis; Kampf, Jeff W.; Wernsdorfer, Wolfgang; Gendron, Frédéric; Autschbach, Jochen

2015-01-01

We report here the synthesis and the investigation of the magnetic properties of a series of binuclear lanthanide complexes belonging to the metallacrown family. The isostructural complexes have a core structure with the general formula [Ga4Ln2(shi3–)4(Hshi2–)2(H2shi–)2(C5H5N)4(CH3OH)x(H2O)x]·xC5H5N·xCH3OH·xH2O (where H3shi = salicylhydroxamic acid and Ln = GdIII1; TbIII2; DyIII3; ErIII4; YIII5; YIII0.9DyIII0.16). Apart from the Er-containing complex, all complexes exhibit an antiferromagnetic exchange coupling leading to a diamagnetic ground state. Magnetic studies, below 2 K, on a single crystal of 3 using a micro-squid array reveal an opening of the magnetic hysteresis cycle at zero field. The dynamic susceptibility studies of 3 and of the diluted DyY 6 complexes reveal the presence of two relaxation processes for 3 that are due to the excited ferromagnetic state and to the uncoupled DyIII ions. The antiferromagnetic coupling in 3 was shown to be mainly due to an exchange mechanism, which accounts for about 2/3 of the energy gap between the antiferro- and the ferromagnetic states. The overlap integrals between the Natural Spin Orbitals (NSOs) of the mononuclear fragments, which are related to the magnitude of the antiferromagnetic exchange, are one order of magnitude larger for the Dy2 than for the Er2 complex. PMID:29218180

A Systematic Study on the Generation of Multimetallic Lanthanide Fullerene ions by Laser Ablation Mass Spectrometry.

PubMed

Wang, Yiyun; Ma, LiFu; Mu, Lei; Ren, Juan; Kong, Xianglei

2018-06-01

Laser ablation masss spectromety has been previously proved to be a powerful tool for studying endohedro metallofullerene (EMF) ions. Our previous study showed the possiblity of forming multi-metallofullerene ions containg more than six metal atoms for La, Y and Lu. Thus, it is important to conduct a systematic study on the generation of multi-metallofullerenes and their distribuitons for all lanthanide elements. Experiments were performed on a 7.0 T Fourier transform ion cyclotron resonance (FT ICR) mass spectrometer. Laser ablation mass spectra were obtained by laser irradiation on mixtures of graphene and MCl 3 on a stainless steel plate, applying a 355 nm Nd: YAG laser with a typical energy of 2.5 mJ/pulse. Reaction test experiments were performed by introducing O 2 into the FT ICR cell with a pulse valve. Multi-metallofullerene ions Ce2-4C2m+, Pr2-4C2m+, Gd2-4C2m+, Nd3C2m+, Dy2-3C2m+, Tb2-7C2m+, Ho2-6C2m+ were observed in the mass spectra. For metal Sm and Eu, no multi-metallofullerene ion was observed. No reaction with O 2 was observed in the reaction experiments, verifying that these species had endohedral structures. For the observed series of multi-metallofullerene ions, tri-metallofullerene ions dominated their mass spectra. The results were further compared with previously generated EMF ions for La, Er, Tm, Yb and Lu. Endohedral lanthanide metallofullerene ions were generated by laser ablation of graphene and the corresponding metal salts MCl 3 (M = Ce, Pr, Nd, Gd, Tb, Dy and Ho) and studied with a FT ICR mass spectrometer. Typically, multi-metallofullerene ions of TbnC2m+2≤n≤780≤2m≤176, Ho6C2m+2≤n≤674≤2m≤162 were observed. The results show that the formation of multi-EMF ions containing lanthanides that have +3 and +4 oxidation states is easier than those containing +2 oxidation states in the process of laser ablation. This article is protected by copyright. All rights reserved.

Photoluminescence properties of white light emitting La2O3:Dy3+ nanocrystals

NASA Astrophysics Data System (ADS)

Reenabati Devi, Konsam; Dorendrajit Singh, Shougaijam; David Singh, Th.

2018-06-01

White light emitting nanocrystalline La2O3:Dy3+ phosphors with different concentration (0.5-2 at.%) were synthesized by simple precipitation method. X-ray diffraction (XRD) pattern indicates all the samples crystallizes in the hexagonal phase. Average crystallite sizes of the samples calculated from XRD data were found to be in the range of 20-55 nm. Transmission electron microscopy, selected area electron diffraction, energy dispersive analysis of X-ray and photoluminescence (PL) of the samples are also reported. Strong PL excitation peak due to charge transfer band was observed at 230 nm. Photoluminescence emission peaks observed at 486 and 575 nm were probably attributed to 4F9/2-6H15/2 and 4F9/2-6H13/2 of Dy3+ ions respectively. Optimum luminescence intensity is found at 1 at.% Dy3+ doped La2O3 sample. Further, Commission Internationale de l'é clairage (CIE, 1931) co-ordinates and correlated color temperature (CCT) of the doped sample were calculated to investigate the phosphors' performance and technical applicability of the emitted light respectively. CCT of the 0.5 and 1 at.% samples is 5894 K (white light), within the range of vertical daylight, which makes the synthesised samples promising nanophosphor and may find application in simulating vertical daylight of the Sun.

Photoluminescence properties of white light emitting La2O3:Dy3+ nanocrystals

NASA Astrophysics Data System (ADS)

Reenabati Devi, Konsam; Dorendrajit Singh, Shougaijam; David Singh, Th.

2018-01-01

White light emitting nanocrystalline La2O3:Dy3+ phosphors with different concentration (0.5-2 at.%) were synthesized by simple precipitation method. X-ray diffraction (XRD) pattern indicates all the samples crystallizes in the hexagonal phase. Average crystallite sizes of the samples calculated from XRD data were found to be in the range of 20-55 nm. Transmission electron microscopy, selected area electron diffraction, energy dispersive analysis of X-ray and photoluminescence (PL) of the samples are also reported. Strong PL excitation peak due to charge transfer band was observed at 230 nm. Photoluminescence emission peaks observed at 486 and 575 nm were probably attributed to 4F9/2-6H15/2 and 4F9/2-6H13/2 of Dy3+ ions respectively. Optimum luminescence intensity is found at 1 at.% Dy3+ doped La2O3 sample. Further, Commission Internationale de l'é clairage (CIE, 1931) co-ordinates and correlated color temperature (CCT) of the doped sample were calculated to investigate the phosphors' performance and technical applicability of the emitted light respectively. CCT of the 0.5 and 1 at.% samples is 5894 K (white light), within the range of vertical daylight, which makes the synthesised samples promising nanophosphor and may find application in simulating vertical daylight of the Sun.

Self-assembled 3D sphere-like SrMoO4 and SrMoO4:Ln3+ (Ln=Eu, Sm, Tb, Dy) microarchitectures: facile sonochemical synthesis and optical properties.

PubMed

Zhang, Junjun; Li, Ruiqing; Liu, Lu; Li, Linlin; Zou, Lianchun; Gan, Shucai; Ji, Guijuan

2014-09-01

Three-dimensional (3D) well-defined SrMoO4 and SrMoO4:Ln(3+) (Ln=Eu, Sm, Tb, Dy) hierarchical structures of obvious sphere-like shape have been successfully synthesized using a large-scale and facile sonochemical route without using any catalysts or templates. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and photoluminescence (PL) spectra were used to characterize the samples. The intrinsic structural feature of SrMoO4 and external factor, namely the ultrasonic time and the pH value, are responsible for the ultimate shape evolutions of the product. The possible formation mechanism for the product is presented. Additionally, the PL properties of SrMoO4 and SrMoO4:Ln(3+) (Ln=Eu, Sm, Tb, Dy) hierarchical structures were investigated in detail. The Ln(3+) ions doped SrMoO4 samples exhibit respective bright red-orange, yellow, green and white light of Eu(3+), Sm(3+), Tb(3+) and Dy(3+) under ultraviolet excitation, and have potential application in the field of color display. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating about the properties of molybdate materials. Copyright © 2014 Elsevier B.V. All rights reserved.

Absence of long-range order in the frustrated magnet SrDy2O4 due to trapped defects from a dimensionality crossover

NASA Astrophysics Data System (ADS)

Gauthier, N.; Fennell, A.; Prévost, B.; Uldry, A.-C.; Delley, B.; Sibille, R.; Désilets-Benoit, A.; Dabkowska, H. A.; Nilsen, G. J.; Regnault, L.-P.; White, J. S.; Niedermayer, C.; Pomjakushin, V.; Bianchi, A. D.; Kenzelmann, M.

2017-04-01

Magnetic frustration and low dimensionality can prevent long-range magnetic order and lead to exotic correlated ground states. SrDy2O4 consists of magnetic Dy3 + ions forming magnetically frustrated zigzag chains along the c axis and shows no long-range order to temperatures as low as T =60 mK. We carried out neutron scattering and ac magnetic susceptibility measurements using powder and single crystals of SrDy2O4 . Diffuse neutron scattering indicates strong one-dimensional (1D) magnetic correlations along the chain direction that can be qualitatively accounted for by the axial next-nearest-neighbor Ising model with nearest-neighbor and next-nearest-neighbor exchange J1=0.3 meV and J2=0.2 meV, respectively. Three-dimensional (3D) correlations become important below T*≈0.7 K. At T =60 mK, the short-range correlations are characterized by a putative propagation vector k1 /2=(0 ,1/2 ,1/2 ) . We argue that the absence of long-range order arises from the presence of slowly decaying 1D domain walls that are trapped due to 3D correlations. This stabilizes a low-temperature phase without long-range magnetic order, but with well-ordered chain segments separated by slowly moving domain walls.

Dielectric properties and microstructures for various MLCCs coated with additives

NASA Astrophysics Data System (ADS)

Oh, Min Wook; Yeo, Dong Hun; Shin, Hyo Soon; Jeong, Dae Yong

2013-12-01

As electronic devices become smaller and have higher capacity, dielectric thin films are being used in the development of multilayer ceramic capacitors (MLCCs). Smaller BaTiO3 dielectric particles should be used to obtain the thickness of low dielectric layers. Further, MLCC properties are achieved through the uniform addition of various additives, but the existing method of adding nano additives has limitations. As such, this study evaluated the dielectric properties of BaTiO3 pellets after using the liquid coating method to add additives such as Dy, Mg, Mn, Cr, and Si to 150 nm BaTiO3 dielectric powder. Mn, Cr, and Si ions were each fixed at 0.1, 0.1, and 0.65 mol-%. Sintering was performed in a reducing atmosphere, and the microstructure and the dielectric properties were evaluated while varying Dy from 0.5 to 1.0 mol-% and Mg from 1.0 to 2.0 mol-%. Grain growth was observed for higher amounts of Dy, but were suppressed for higher amounts of Mg. With regards to changes in particle size, both the permittivity and the temperature coefficient of capacitance (TCC) increased with increasing particle size. The permittivity was highest for Si=0.65, Mn=0.1, Cr=0.1 Dy=0.75, and Mg=2.0 mol-%. These levels also satisfied the TCC properties of X7R. In the microstructure, the core-shell was the most developed.

Optical properties of Sr3B2O6:Dy3+/PMMA polymer nanocomposites

NASA Astrophysics Data System (ADS)

Khursheed, Sumara; Kumar, Vinay; Singh, Vivek K.; Sharma, Jitendra; Swart, H. C.

2018-04-01

The paper presents a facile way to synthesize luminescent polymer nanocomposite (PNC) films consisting of nanophosphors (NPs) of rare earth ions doped alkaline earth borates (Sr3B2O6:Dy3+) dispersed in a polymer (PMMA) matrix via a solution casting method and the results of their detailed structural and optical properties measurements. The PNC films were characterized using X-ray diffraction (XRD), Photoluminescence (PL), and differential scanning calorimetry (DSC). The crystallinity of the dispersed NPs did not suffer on account of being dispersed in the PMMA. The Rhombohedral structure and the formation of a single phase of Sr3B2O6:Dy3+ were confirmed by the XRD data of both the NP powders and the PNC films with an average particle size of 43 nm. Also, the observed PL emission and excitation spectra of the PNC films amply suggested that embedding of the nanophosphors in the PMMA matrix preserves their typical luminescence emission. The chromaticity coordinates (x = 0.37, y = 0.39) of the PNC films also validated the yellowish white emission of the nanophosphor. DSC scans on the PMMA only and the Sr3B2O6:Dy3+/PMMA films suggested an increase in the thermal stability of the PNC films as compared to pure PMMA although no significant change in the glass transition temperature was observed.

Materials Data on DySb2 (SG:21) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2017-04-07

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on Dy2SO2 (SG:164) by Materials Project

DOE Data Explorer

Kristin Persson

2014-11-02

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on Dy(CuS)2 (SG:164) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2017-04-09

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyBPd3 (SG:221) by Materials Project

DOE Data Explorer

Kristin Persson

2015-02-09

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on Dy(BC)2 (SG:131) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2016-02-05

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyCoC (SG:131) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2016-02-05

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyTe3 (SG:63) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2017-05-05

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyMn2 (SG:227) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2016-02-05

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on Dy11S16 (SG:18) by Materials Project

DOE Data Explorer

Kristin Persson

2016-02-10

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyCoSn2 (SG:63) by Materials Project

DOE Data Explorer

Kristin Persson

2016-02-10

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DySn2 (SG:63) by Materials Project

DOE Data Explorer

Kristin Persson

2015-01-27

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

A family of acetato-diphenoxo triply bridged dimetallic Zn(II)Ln(III) complexes: SMM behavior and luminescent properties.

PubMed

Oyarzabal, Itziar; Artetxe, Beñat; Rodríguez-Diéguez, Antonio; García, JoséÁngel; Seco, José Manuel; Colacio, Enrique

2016-06-21

Eleven dimetallic Zn(II)-Ln(III) complexes of the general formula [Zn(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (Ln(III) = Pr (1), Nd (2), Sm (3), Eu (4), Gd (5), Tb (6), Dy (7), Ho (8), Er (9), Tm (10), Yb (11)) have been prepared in a one-pot reaction from the compartmental ligand N,N'-dimethyl-N,N'-bis(2-hydroxy-3-formyl-5-bromo-benzyl)ethylenediamine (H2L). In all these complexes, the Zn(II) ions occupy the internal N2O2 site whereas the Ln(III) ions show preference for the O4 external site. Both metallic ions are bridged by an acetate bridge, giving rise to triple mixed diphenoxido/acetate bridged Zn(II)Ln(III) compounds. The Nd, Dy, Er and Yb complexes exhibit field induced single-ion magnet (SIM) behaviour, with Ueff values ranging from 14.12 to 41.55 K. The Er complex shows two relaxation processes, but only the second relaxation process with an energy barrier of 21.0 K has been characterized. The chromophoric L(2-) ligand is able to act as an "antenna" group, sensitizing the near-infrared (NIR) Nd(III) and Yb(III)-based luminescence in complexes 2 and 11 and therefore, both compounds can be considered as magneto-luminescent materials. In addition, the Sm(III), Eu(III) and Tb(III) derivatives exhibit characteristic emissions in the visible region.

Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Buhao; Xu, Xuhui; Li, Qianyue

Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R{sup 3+} ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}. The greatly improved LPL performance was observed in Nd{sup 3+} co-doped samples, which indicates that the incorporation of Nd{sup 3+} creates suitable traps for LPL. While co-doping Tm{sup 3+} ions, the intensity of high temperature of thermoluminescence band in CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphors is enhanced for the formation of the most suitable trapsmore » which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R{sup 3+} ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} exhibits different read-in/read-out performance as well. - Graphical abstract: OSL emission spectra of Ca{sub 0.995}Al{sub 2}O{sub 4}:0.0025Eu{sup 2+}, 0.0025R{sup 3+} (R=Nd, Dy, Tm) taken under varying stimulation time (0, 25, 50, 75, 100 s). Inset: Blue emission pictures under varying stimulation time. - Highlights: • The LPL and OSL properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} were investigated. • An alternative approach to control the trap depth of CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphor was proposed. • A new oxide ETM phosphor exhibiting intense and stable OSL was explored.« less

Raman scattering of rare earth hexaborides

NASA Astrophysics Data System (ADS)

Ogita, Norio; Hasegawa, Takumi; Udagawa, Masayuki; Iga, Fumitoshi; Kunii, Satoru

2009-06-01

Raman scattering spectra were measured for the rare-earth hexaborides RB6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B6 vibrations were observed in the range 600 - 1400 cm-1. Anomalous peaks were detected below 200 cm-1, which correspond to vibrations of rare-earth ion excited by second-order Raman scattering process. The intensity and energy of the rare-earth mode decrease with decreasing temperature. This suggests that the rare-earth ion vibrates in a shallow and anharmonic potential due to the boron cage. Using the reported values of mean square displacement of rare-earth ion, we estimated the anharmonic contribution for the rare-earth vibrations.

Transport properties of RCo_2B_2C with R = Dy, Ho, and Pr single

NASA Astrophysics Data System (ADS)

Duran, Alejandro; Escudero, Roberto

2002-03-01

Single crystals of (Dy, Ho, Pr)Co_2B_2C have been grown by a cold copper crucible method. Metallurgical and structural studies indicate that this borocarbide family melts incongruently and crystallizes as a derivative structure of the ThCr_2Si_2. The family accepts rare earth atoms depending on the type of transition metals used to form the compound. For instance with Ni atoms, all lanthanides ranging from the large lanthanum to lutetium ions are reported to form RNi_2B_2C single crystals, so far no single crystals have been obtained when changing Ni by Cobalt. A comparison of the structural parameters of the RCo_2B_2C with the RNiHo, Pr) compounds indicate that the atomic distance between transition metal atoms contracts with the insertion of the Co ion, resulting in an increasing of the c parameter and decreasing volume. Several recent reports published in the current literature related on the physical properties of RCo_2B_2C (R = rare earth metals and Y) have been only performed on polycrystalline samples, they commonly contain small amounts of second phases. High quality single crystals are necessaries in order to better understand the physical properties, such as anisotropy in the transport and in the magnetic properties. In this report we show magnetic susceptibility and resistivity measurements performed in single crystals in the ab-plane and c direction for 2 - 320 K temperature range for the three single crystals of (Dy, Ho, Pr)Co_2B_2C.

Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior.

PubMed

Chandrasekhar, Vadapalli; Hossain, Sakiat; Das, Sourav; Biswas, Sourav; Sutter, Jean-Pascal

2013-06-03

The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.

Complexation of lanthanides and actinides by acetohydroxamic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, R.J.; Sinkov, S.I.; Choppin, G.R.

2008-07-01

Acetohydroxamic acid (AHA) has been proposed as a suitable reagent for the complexant-based, as opposed to reductive, stripping of plutonium and neptunium ions from the tributylphosphate solvent phase in advanced PUREX or UREX processes designed for future nuclear-fuel reprocessing. Stripping is achieved by the formation of strong hydrophilic complexes with the tetravalent actinides in nitric acid solutions. To underpin such applications, knowledge of the complexation constants of AHA with all relevant actinide (5f) and lanthanide (4f) ions is therefore important. This paper reports the determination of stability constants of AHA with the heavier lanthanide ions (Dy-Yb) and also U(IV) andmore » Th(IV) ions. Comparisons with our previously published AHA stability-constant data for 4f and 5f ions are made. (authors)« less

Materials Data on Ca(DyS2)2 (SG:122) by Materials Project

DOE Data Explorer

Kristin Persson

2014-11-02

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on Dy4(SiS4)3 (SG:14) by Materials Project

DOE Data Explorer

Kristin Persson

2014-11-02

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyCu(WO4)2 (SG:2) by Materials Project

DOE Data Explorer

Kristin Persson

2014-07-09

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on DyTa7O19 (SG:188) by Materials Project

DOE Data Explorer

Kristin Persson

2014-11-02

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Materials Data on Dy2Sn2O7 (SG:227) by Materials Project

DOE Data Explorer

Kristin Persson

2014-07-09

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Low-mass vector-meson production at forward rapidity in p +p collisions at √s =200 GeV

NASA Astrophysics Data System (ADS)

Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Ta'Ani, H.; Alexander, J.; Alfred, M.; Andrews, K. R.; Angerami, A.; Aoki, K.; Apadula, N.; Appelt, E.; Aramaki, Y.; Armendariz, R.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Ben-Benjamin, J.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Black, D.; Blau, D. S.; Bok, J.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Broxmeyer, D.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Campbell, S.; Castera, P.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Csanád, M.; Csörgő, T.; Dairaku, S.; Datta, A.; Daugherity, M. S.; David, G.; Dayananda, M. K.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Ding, L.; Dion, A.; Do, J. H.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guo, L.; Guragain, H.; Gustafsson, H.-Å.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Han, S. Y.; Hanks, J.; Harper, C.; Hasegawa, S.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Hoshino, T.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Issah, M.; Ivanischev, D.; Ivanishchev, D.; Iwanaga, Y.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; John, D.; Johnson, B. M.; Jones, T.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Key, J. A.; Khachatryan, V.; Khanzadeev, A.; Kihara, K.; Kijima, K. M.; Kim, B. I.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.-J.; Kim, H.-J.; Kim, M.; Kim, Y.-J.; Kim, Y. K.; Kinney, E.; Kiss, Á.; Kistenev, E.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kochenda, L.; Kofarago, M.; Komkov, B.; Konno, M.; Koster, J.; Kotov, D.; Král, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miki, K.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyachi, Y.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, H. J.; Moon, T.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Newby, J.; Nguyen, M.; Nihashi, M.; Niida, T.; Nouicer, R.; Novitzky, N.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Ogilvie, C. A.; Oka, M.; Okada, K.; Orjuela Koop, J. D.; Oskarsson, A.; Ouchida, M.; Ozaki, H.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Pei, H.; Peng, J.-C.; Pereira, H.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reygers, K.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Riveli, N.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosendahl, S. S. E.; Rowan, Z.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sano, S.; Sarsour, M.; Sato, S.; Sato, T.; Savastio, M.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shim, H. H.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Sodre, T.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Themann, H.; Thomas, D.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Togawa, M.; Tomášek, L.; Tomášek, M.; Torii, H.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Utsunomiya, K.; Vale, C.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; Wessels, J.; Whitaker, S.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. S.; Yoon, I.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Phenix Collaboration

2014-09-01

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson, ω, ρ, and ϕ, production through the dimuon decay channel at forward rapidity (1.2<|y|<2.2) in p+p collisions at √s =200 GeV. The differential cross sections for these mesons are measured as a function of both pT and rapidity. We also report the integrated differential cross sections over 1

Baryon spectra and antiparticle-to-particle ratios from the improved AMPT model

NASA Astrophysics Data System (ADS)

He, Yuncun; Lin, Zi-Wei

2018-02-01

The current version of a multi-phase transport (AMPT) model with string melting can reasonably describe the dN/dy yields, pT spectra and anisotropic flows of pions and kaons at low pT in heavy ion collisions at RHIC and LHC energies, although it failed to reproduce the dN/dy and pT spectra of baryons. In this work, we improve the quark coalescence mechanism in AMPT by removing the forced separate number conservations of mesons, baryons and antibaryons in each event. We find that the improved AMPT model can better describe the yields at midrapidity, the pT spectra and elliptic flow of low-pT baryons in comparison with the experimental data. Antiparticle-to-particle ratios of strange baryons are also significantly improved.

78 FR 39713 - Determination Under the Textile and Apparel Commercial Availability Provision of the Dominican...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-02

...). Weight: 220-315 grams per square meter. Thread Count (Density): 76-110 ends per inch (Warp) X 70-90 picks.... Finishing Processes: Airjet Dyed. Kim Glas, Chairman Committee for the Implementation of Textile Agreements...

Materials Data on Ba2DyCu3O7 (SG:47) by Materials Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristin Persson

2016-04-22

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

M-shell x-ray production cross sections for 19 elements in the range Z=54-92 by H/sup +/, He/sup +/ and He/sup + +/ ions from 300 keV to 40 MeV. [Xe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Hf, Ta, W, Pt, Au, Hg, Pb, Bi, and U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, R.; Duggan, J.L.; Kocur, P.M.

1983-04-01

In this report, the measurements done over the last three decades at various laboratories are surveyed. The elements studied were Xe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Hf, Ta, W, Pt, Au, Hg, Pb, Bi, and U. The projectile energies investigated range from 300 keV to 40 MeV for the protons and 250 keV to 2.5 MeV for He/sup +/ ions. Also reported are the M-shell x-ray production cross sections of some rare-earth elements recently measured at NTSU. For these measurements the energy of incident /sup 1/H/sup +/ and /sup 4/He/sup +/ ions ranged from 0.25 tomore » 2.5 MeV. The experimental data are compared to the M-shell ionization cross section predictions of first Born approximation, i.e. the PWBA for direct ionization plus the OBK of Nikolaev for electron capture. Comparison is also made with the theory by Brandt and Lapicki that goes beyond the first Born approximation, i.e. the ECPSSR approach which accounts for the Energy loss, Coulomb deflection and Relativistic effects in the Perturbed Stationary State theory.« less

Three series of heterometallic NiII-LnIII Schiff base complexes: synthesis, crystal structures and magnetic characterization.

PubMed

Jiang, Lin; Liu, Yue; Liu, Xin; Tian, Jinlei; Yan, Shiping

2017-09-26

Three series of Ni II -Ln III complexes were synthesized with the general formulae [(μ 3 -CO 3 ) 2 {Ni(HL)(CH 3 -CH 2 OH)Ln(CH 3 COO)} 2 ]·2CH 3 CH 2 OH (1-6) (Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6); H 3 L = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2-prop-anol), [Ni(HL)Ln(dbm) 3 ]·CH 3 OH 2 ·2CH 2 Cl 2 (7-10) (Ln = Tb (7), Eu (8), Gd (9), Ho (10); Hdbm = 1,3-diphenyl-1,3-propanedione) and [Ni(HL)(H 2 O)(tfa)Ln(hfac) 2 ] (11-15) (Ln = Tb (11), Dy (12), Eu (13), Gd (14), Ho (15); Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, tfa - = trifluoroacetate) using compartmental Schiff base ligands in conjunction with auxiliary ligands. For the NiLn series, the tetranuclear structure could be considered as two Ni II -Ln III dinuclear subunits bridged by two carbonates derived from atmospheric carbon dioxide. The Ln III ions of complexes 1-6 were octa-coordinated with distorted triangular dodecahedral geometry, while the Ln III ions of the dinuclear complexes 7-15 were nona-coordinated with distorted muffin geometry. The magnetic properties of the three series complexes were studied using dc and ac magnetic measurements. For the Ni II -Gd III complexes, the dc magnetic susceptibility measurements suggested the existence of the anticipated ferromagnetic interaction between Ni II and Gd III ions. The fitting of the χ M T vs. T data processed by PHI software provided the parameters g = 2.08 (J = +0.87 cm -1 ) for 9 and g = 2.02 (J = +1.83 cm -1 ) for 14. The interaction exchange was magneto-structurally correlated to the Ni-O-Gd angle (α) and Ni(μ-O)Gd dihedral angle (β). With an applied dc field, complexes 1 (Tb), 2 (Dy), 7 (Tb) and 12 (Dy) exhibited single magnetic relaxation with SMM parameters of U eff /k = 13.60 K, 11.52 K, 7.69 K and 5.14 K, respectively. Analysis of the Cole-Cole plots for complexes 2 and 7 suggested that a single relaxation process was mainly involved in the relaxation process, with α values in the range of 0.37-0.17 and 0.14-0.11, respectively.

Structural refinement, band-gap analysis and optical properties of GdAlO3 nanophosphors influenced by Dy3+ ion concentrations for white light emitting device applications

NASA Astrophysics Data System (ADS)

Jisha, P. K.; Naik, Ramachandra; Prashantha, S. C.; Nagaswarupa, H. P.; Nagabhushana, H.; Basavaraj, R. B.; Sharma, S. C.; Prasad, Daruka

2016-04-01

Nanosized GdAlO3 phosphors activated with Dy3+ were prepared by a combustion method. Synthesized phosphors were calcined at 1000 °C for 3 h in order to achieve crystallinity. Powder x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis was used to characterize the prepared product. The orthorhombic phase was observed in the XRD pattern. The particle size of the samples was calculated as around 25 nm. The SEM images show an irregular shape of the prepared nanophosphor. Functional groups of the phosphors were examined by Fourier transform infrared (FTIR) spectroscopy. Photoluminescence (PL) properties of Dy3+ doped GdAlO3 for near-ultraviolet excitation (352 nm) were studied in order to investigate the possibility of its use in white light emitting device applications. Judd-Ofelt intensity parameters, radiative transition rate (A T) and radiative lifetimes (τ rad) were evaluated from the emission spectrum by adopting a standard procedure. The Commission International de l’Eclairage (CIE) color coordinates and correlated color temperature (CCT) are studied for the optimized phosphor. It is found that the color coordinates of Dy3+ doped GdAlO3 powders fall in the white region of the CIE diagram, and the average CCT value was found to be about 6276 K. Therefore, the present phosphor is highly useful for display applications.

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3{NIT(C6H4OPh)}]: A μ+ spin relaxation study

NASA Astrophysics Data System (ADS)

Arosio, Paolo; Corti, Maurizio; Mariani, Manuel; Orsini, Francesco; Bogani, Lapo; Caneschi, Andrea; Lago, Jorge; Lascialfari, Alessandro

2015-05-01

The spin dynamics of the molecular magnetic chain [Dy(hfac)3{NIT(C6H4OPh)}] were investigated by means of the Muon Spin Relaxation (μ+SR) technique. This system consists of a magnetic lattice of alternating Dy(III) ions and radical spins, and exhibits single-chain-magnet behavior. The magnetic properties of [Dy(hfac)3{NIT(C6H4OPh)}] have been studied by measuring the magnetization vs. temperature at different applied magnetic fields (H = 5, 3500, and 16500 Oe) and by performing μ+SR experiments vs. temperature in zero field and in a longitudinal applied magnetic field H = 3500 Oe. The muon asymmetry P(t) was fitted by the sum of three components, two stretched-exponential decays with fast and intermediate relaxation times, and a third slow exponential decay. The temperature dependence of the spin dynamics has been determined by analyzing the muon longitudinal relaxation rate λinterm(T), associated with the intermediate relaxing component. The experimental λinterm(T) data were fitted with a corrected phenomenological Bloembergen-Purcell-Pound law by using a distribution of thermally activated correlation times, which average to τ = τ0 exp(Δ/kBT), corresponding to a distribution of energy barriers Δ. The correlation times can be associated with the spin freezing that occurs when the system condenses in the ground state.

Spin-Parity Behavior in the Exchange-Coupled Lanthanoid-Nitroxide Molecular Magnets

NASA Astrophysics Data System (ADS)

Ishida, T.

2017-05-01

To develop lanthanoid-based magnetic materials and relevant devices, reliable prescriptions for molecular/crystal design have long been desired. Ln3+-ion dependence on the molecular magnetism was investigated in the isomorphous series [Ln(hfac)3(2pyNO)] (Ln = Tb, Dy, Ho, Er), where 2pyNO stands for tert-butyl 2-pyridyl nitroxide as a paramagnetic ligand, and hfac for 1,1,1,5,5,5-hexafluoropentane-2,4-dionate. The slow magnetization reversal was evaluated as an indication of single-molecule magnets (SMMs) by out-of-phase ac magnetic susceptibility χ”. Whereas the Tb3+ (4f8) and Ho3+ (4f10) derivatives exhibited frequency-dependent χ”, practically null χ” was recorded for the Dy3+(4f9) and Er3+ (4f11) derivatives. As for another series with Ln/radical = 1/2, [Ln(hfac)3(TEMPO)2] complexes were prepared (Ln = Tb, Dy, Ho, Er, Tm; TEMPO = 2,2,6,6-tetramethylpiperidin-1-oxyl). The Dy3+ and Er3+ derivatives showed appreciable χ”, but the Tb3+, Ho3+, and Tm3+ derivatives did not. Thus, the S = 1/2 paramagnetic ligands play a role of a spin-parity switch to regulate whether the compound behaves as an SMM. In the strongly exchange-coupled regime owing to the direct radical coordination bond, the whole molecular electron counting may provide a useful criterion to predict Kramers molecules and accordingly to explore potential SMM candidates.

Trends in Syntheses, Structures, and Properties for Three Series of Ammine Rare-Earth Metal Borohydrides, M(BH4)3·nNH3 (M = Y, Gd, and Dy).

PubMed

Jepsen, Lars H; Ley, Morten B; Černý, Radovan; Lee, Young-Su; Cho, Young Whan; Ravnsbæk, Dorthe; Besenbacher, Flemming; Skibsted, Jørgen; Jensen, Torben R

2015-08-03

Fourteen solvent- and halide-free ammine rare-earth metal borohydrides M(BH4)3·nNH3, M = Y, Gd, Dy, n = 7, 6, 5, 4, 2, and 1, have been synthesized by a new approach, and their structures as well as chemical and physical properties are characterized. Extensive series of coordination complexes with systematic variation in the number of ligands are presented, as prepared by combined mechanochemistry, solvent-based methods, solid-gas reactions, and thermal treatment. This new synthesis approach may have a significant impact within inorganic coordination chemistry. Halide-free metal borohydrides have been synthesized by solvent-based metathesis reactions of LiBH4 and MCl3 (3:1), followed by reactions of M(BH4)3 with an excess of NH3 gas, yielding M(BH4)3·7NH3 (M = Y, Gd, and Dy). Crystal structure models for M(BH4)3·nNH3 are derived from a combination of powder X-ray diffraction (PXD), (11)B magic-angle spinning NMR, and density functional theory (DFT) calculations. The structures vary from two-dimensional layers (n = 1), one-dimensional chains (n = 2), molecular compounds (n = 4 and 5), to contain complex ions (n = 6 and 7). NH3 coordinates to the metal in all compounds, while BH4(-) has a flexible coordination, i.e., either as a terminal or bridging ligand or as a counterion. M(BH4)3·7NH3 releases ammonia stepwise by thermal treatment producing M(BH4)3·nNH3 (6, 5, and 4), whereas hydrogen is released for n ≤ 4. Detailed analysis of the dihydrogen bonds reveals new insight about the hydrogen elimination mechanism, which contradicts current hypotheses. Overall, the present work provides new general knowledge toward rational materials design and preparation along with limitations of PXD and DFT for analysis of structures with a significant degree of dynamics in the structures.

Antiferromagnetic coupling between rare earth ions and semiquinones in a series of 1:1 complexes.

PubMed

Caneschi, Andrea; Dei, Andrea; Gatteschi, Dante; Poussereau, Sandrine; Sorace, Lorenzo

2004-04-07

We use the strategy of diamagnetic substitution for obtaining information on the crystal field effects in paramagnetic rare earth ions using the homologous series of compounds with the diamagnetic tropolonato ligand, Ln(Trp)(HBPz(3))(2), and the paramagnetic semiquinone ligand, Ln(DTBSQ)(HBPz(3))(2), (DTBSQ = 3,5-di-tert-butylsemiquinonato, Trp = tropolonate, HBPz(3)= hydrotrispyrazolylborate) for Ln = Sm(iii), Eu(iii), Gd(iii), Tb(iii), Dy(iii), Ho(iii), Er(iii) or Yb(iii). The X-ray crystal structure of a new form of tropolonate derivative is presented, which shows, as expected, a marked similarity with the structure of the semiquinonate derivative. The Ln(Trp)(HBPz(3))(2) derivatives were then used as a reference for the qualitative determination of crystal field effects in the exchange coupled semiquinone derivatives. Through magnetisation and susceptibility measurements this empirical diamagnetic substitution method evidenced for Er(iii), Tb(iii), Dy(iii) and Yb(iii) derivatives a dominating antiferromagnetic coupling. The increased antiferromagnetic contribution compared to other radical-rare earth metal complexes formed by nitronyl nitroxide ligands may be related to the increased donor strength of the semiquinone ligand.

In situ hydrostatic pressure induced improvement of critical current density and suppression of magnetic relaxation in Y(Dy0.5)Ba2Cu3O7‑δ coated conductors

NASA Astrophysics Data System (ADS)

Sang, Lina; Gutiérrez, Joffre; Cai, Chuanbing; Dou, Shixue; Wang, Xiaolin

2018-07-01

We report on the effect of in situ hydrostatic pressure on the enhancement of the in-magnetic-field critical current density parallel to the crystallographic c-axis and vortex pinning in epitaxial Y(Dy0.5)Ba2Cu3O7‑δ coated conductors prepared by metal organic deposition. Our results show that in situ hydrostatic pressure greatly enhances the critical current density at high fields and high temperatures. At 80 K and 5 T we observe a ten-fold increase in the critical current density under the pressure of 1.2 GPa, and the irreversibility line is shifted to higher fields without changing the critical temperature. The normalized magnetic relaxation rate shows that vortex creep rates are strongly suppressed due to applied pressure, and the pinning energy is significantly increased based on the collective creep theory. After releasing the pressure, we recover the original superconducting properties. Therefore, we speculate that the in situ hydrostatic pressure exerted on the coated conductor enhances the pinning of existing extended defects. This is totally different from what has been observed in REBa2Cu3O7‑δ melt-textured crystals, where the effect of pressure generates point-like defects.

OptoDyCE: Automated system for high-throughput all-optical dynamic cardiac electrophysiology

NASA Astrophysics Data System (ADS)

Klimas, Aleksandra; Yu, Jinzhu; Ambrosi, Christina M.; Williams, John C.; Bien, Harold; Entcheva, Emilia

2016-02-01

In the last two decades, <30% of drugs withdrawals from the market were due to cardiac toxicity, where unintended interactions with ion channels disrupt the heart's normal electrical function. Consequently, all new drugs must undergo preclinical testing for cardiac liability, adding to an already expensive and lengthy process. Recognition that proarrhythmic effects often result from drug action on multiple ion channels demonstrates a need for integrative and comprehensive measurements. Additionally, patient-specific therapies relying on emerging technologies employing stem-cell derived cardiomyocytes (e.g. induced pluripotent stem-cell-derived cardiomyocytes, iPSC-CMs) require better screening methods to become practical. However, a high-throughput, cost-effective approach for cellular cardiac electrophysiology has not been feasible. Optical techniques for manipulation and recording provide a contactless means of dynamic, high-throughput testing of cells and tissues. Here, we consider the requirements for all-optical electrophysiology for drug testing, and we implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We demonstrate the high-throughput capabilities using multicellular samples in 96-well format by combining optogenetic actuation with simultaneous fast high-resolution optical sensing of voltage or intracellular calcium. The system can also be implemented using iPSC-CMs and other cell-types by delivery of optogenetic drivers, or through the modular use of dedicated light-sensitive somatic cells in conjunction with non-modified cells. OptoDyCE provides a truly modular and dynamic screening system, capable of fully-automated acquisition of high-content information integral for improved discovery and development of new drugs and biologics, as well as providing a means of better understanding of electrical disturbances in the heart.

Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

NASA Astrophysics Data System (ADS)

Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

2015-01-01

For the first time, we report the successful synthesis of novel nanoparticle-sheathed bipyramid-like and almond-like Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) 3D hierarchical microstructures through a simple disodium ethylenediaminetetraacetic acid (Na2EDTA) facilitated hydrothermal method. Interestingly, time-dependent experiments confirm that the assembly-disassembly process is responsible for the formation of self-aggregated 3D architectures via Ostwald ripening phenomena. The resultant products are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and magnetic measurements. The growth and formation mechanisms of the self-assembled 3D micro structures are discussed in detail. To confirm the presence of all the elements in the microstructure, the energy loss induced by the K, L shell electron ionization is observed in order to map the Fe, Gd, Mo, O, and Eu components. The photo luminescence properties of Fe0.5R0.5(MoO4)1.5 doped with Eu3+, Tb3+, Dy3+ are investigated. The room temperature and low temperature magnetic properties suggest that the interaction between the local-fields introduced by the magnetic Fe3+ ions and the R3+ (La, Gd) ions in the dodecahedral sites determine the magnetism in Fe0.5R0.5(MoO4)1.5:Eu3+. This work provides a new approach to synthesizing the novel Fe0.5R0.5(MoO4)1.5:Ln3+ for bi-functional magnetic and luminescence applications.

Cathodoluminescence emission of REE (Dy, Pr and Eu) doped LaAlO3 phosphors

NASA Astrophysics Data System (ADS)

Boronat, C.; Rivera, T.; Garcia-Guinea, J.; Correcher, V.

2017-01-01

Luminescence emission from rare earth (REE) ions doped materials are being of interest since can be employed as scintillators, catalysts, battery and magnetic materials, etc. We herein report on the preliminary results obtained from the cathodoluminescence (CL) properties of undoped LaAlO3 (LAO) and LaAlO3: REE3+ (REE=Dy3+, Pr3+ and Eu3+) samples synthesized by a sol-gel process based on the Pechini's method with a spray-drying technique. The samples, previously characterized by means of Environmental Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis Spectrometry, display CL spectra with well-defined peaks that could specifically be associated with the LAO structure (in the range of 300-450 nm) and point defects (from 450 to 800 nm) spectral regions. The observed wavebands are as follows: (i) 480 and 570 from the Dy-doped LAO correspond respectively to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, (ii) 490-638 from the Pr-doped LAO is linked to 3P0→3H4, 1D2→3H4 transitions and (iii) 590 and 620 where the dopant Eu3+ gives rise to 5D0→7F1 and 5D0→7F2 transitions and (iv) a UV-blue broad band is associated with NBHOC in undoped LAO. Such emissions are due to the presence of the 4f electrons of rare earth ions that are shielded by the outer 5s and 5p electrons, the intra-4f emission spectra of REE that induce sharp and narrow wavebands.

Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Xue-Qin, E-mail: songxq@mail.lzjtu.cn; Lei, Yao-Kun; Wang, Xiao-Run

2014-10-15

The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversitiesmore » indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.« less

Thermodynamics of radiation induced amorphization and thermal annealing of Dy 2Sn 2O 7 pyrochlore

DOE PAGES

Chung, Cheng-Kai; Lang, Maik; Xu, Hongwu; ...

2018-06-14

Thermodynamics and annealing behavior of swift heavy ion amorphized Dy 2Sn 2O 7 pyrochlore were studied. Its amorphization enthalpy, defined as the total energetic difference between the irradiation amorphized and undamaged Dy 2Sn 2O 7 states, was determined to be 283.6 ± 6.5 kJ/mol by high temperature oxide melt drop solution calorimetry. It has been an enigma that stannate and some other pyrochlores do not follow the general r A/r B-radiation resistance relation seen in most pyrochlore systems. In this paper, we use the amorphization enthalpy, which reflects all the complex chemical and structural characteristics, as a more effective parametermore » to correlate the radiation damage resistance of pyrochlores with their compositions. It successfully explains the superior radiation damage resistance of the stannate pyrochlores compared with titanate pyrochlores. Differential scanning calorimetry (DSC) reveals a strong exothermic event starting at 978 K, which is attributed to long-range recrystallization based on X-ray diffraction (XRD) analysis, similar to the effect previously observed in Dy 2Ti 2O 7. A second pronounced heat event beginning at ~1148 K, which results from local structural rearrangement, is clearly decoupled from the first event for irradiated Dy 2Sn 2O 7. Both the heat releases measured by DSC on heating to 1023 and 1473 K, and the excess enthalpies of the annealed samples indicate that the recovery to the original, ordered state was not fully achieved up to even 1473 K, despite XRD showing the apparent restoration of crystalline pyrochlore structure. The remaining metastability may be attributed to local disorder in the form of weberite-like short-range domains in the recrystallized material. Intriguingly, the second event for different pyrochlores generally starts at similar temperatures while the onset of the long range recrystallization is compositionally dependent. Finally, the amorphization and thermal annealing behavior observed in irradiated Dy 2Sn 2O 7 may provide insights into the general mechanisms of radiation damage and recovery of pyrochlores relevant to their nuclear applications.« less

The Dy–Ni–Si system as a representative of the rare earth–Ni–Si family: Its isothermal section and new rare-earth nickel silicides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, Fang; Mozharivskyj, Y.; Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru

The Dy–Ni–Si system has been investigated at 1070 K by X-ray and microprobe analysis. The system contains the 12 known compounds DyNi{sub 10}Si{sub 2}, DyNi{sub 5}Si{sub 3}, DyNi{sub 6}Si{sub 6}, DyNi{sub 4}Si, DyNi{sub 2}Si{sub 2}, Dy{sub 2}Ni{sub 3}Si{sub 5}, DyNiSi{sub 3}, Dy{sub 3}Ni{sub 6}Si{sub 2}, DyNiSi{sub 2}, DyNiSi, Dy{sub 3}NiSi{sub 3}, Dy{sub 3}NiSi{sub 2}, and the new compounds Dy{sub 34}Ni{sub 16−27}Si{sub 50−39} (AlB{sub 2}-type), Dy{sub 2}Ni{sub 15.2−14.1}Si{sub 1.8−2.9} (Th{sub 2}Zn{sub 17}-type), ∼Dy{sub 11}Ni{sub 65}Si{sub 24}, ∼Dy{sub 16}Ni{sub 62}Si{sub 22} (unknown structures), DyNi{sub 7}Si{sub 6} (GdNi{sub 7}Si{sub 6}-type), Dy{sub 3}Ni{sub 8}Si (Ce{sub 3}Co{sub 8}Si-type), DyNi{sub 2}Si (YPd{sub 2}Si-type), ∼Dy{sub 40}Ni{sub 47}Si{submore » 13} and ∼Dy{sub 5}Ni{sub 2}Si{sub 3} (unknown structures). Quasi–binary solid solutions were detected at 1070 (870 K) for Dy{sub 2}Ni{sub 17}, DyNi{sub 5}, DyNi{sub 7}, DyNi{sub 3}, DyNi{sub 2}, DyNi, DySi{sub 2} and DySi{sub 1.67}. No detectable solubility is observed for the other binary compounds of the Dy–Ni–Si system. The crystal structures of new phases RNi{sub 7}Si{sub 6} (GdNi{sub 7}Si{sub 6}-type), R{sub 3}Ni{sub 8}Si (Ce{sub 3}Co{sub 8}Si-type), RNi{sub 2}Si (YPd{sub 2}Si-type) and R{sub 3}Ni{sub 12}Si{sub 4} (Gd{sub 3}Ru{sub 4}Al{sub 12}-type), with R=Y, Gd–Tm, has been studied. Magnetic properties of few representative compounds are also reported. - Graphical abstract: The Dy–Ni–Si system has been investigated at 1070 K by X-ray and microprobe analysis. The system contains the 12 known compounds DyNi{sub 10}Si{sub 2}, DyNi{sub 5}Si{sub 3}, DyNi{sub 6}Si{sub 6}, DyNi{sub 4}Si, DyNi{sub 2}Si{sub 2}, Dy{sub 2}Ni{sub 3}Si{sub 5}, DyNiSi{sub 3}, Dy{sub 3}Ni{sub 6}Si{sub 2}, DyNiSi{sub 2}, DyNiSi, Dy{sub 3}NiSi{sub 3}, Dy{sub 3}NiSi{sub 2}, and the new compounds Dy{sub 34}Ni{sub 16−27}Si{sub 50−39}, Dy{sub 2}Ni{sub 15.2−14.1}Si{sub 1.8−2.9}, ∼Dy{sub 11}Ni{sub 65}Si{sub 24}, ∼Dy{sub 16}Ni{sub 62}Si{sub 22}, DyNi{sub 7}Si{sub 6}, Dy{sub 3}Ni{sub 8}Si, DyNi{sub 2}Si, ∼Dy{sub 40}Ni{sub 47}Si{sub 13} and ∼Dy{sub 5}Ni{sub 2}Si{sub 3}. Quasi–binary solid solutions were detected for Dy{sub 2}Ni{sub 17}, DyNi{sub 5}, DyNi{sub 7}, DyNi{sub 3}, DyNi{sub 2}, DyNi, DySi{sub 2} and DySi{sub 1.67}. The crystal structures and magnetic properties of new phases RNi{sub 7}Si{sub 6} (GdNi{sub 7}Si{sub 6}-type), R{sub 3}Ni{sub 8}Si (Ce{sub 3}Co{sub 8}Si-type), RNi{sub 2}Si (YPd{sub 2}Si-type) and R{sub 3}Ni{sub 12}Si{sub 4} (Gd{sub 3}Ru{sub 4}Al{sub 12}-type), with R=Y, Gd–Tm, are also reported. - Highlights: • Dy–Ni–Si isothermal section was obtained at 870 K/1070 K. • Twelve known ternary dysprosium nickel silicides were confirmed in Dy–Ni–Si. • Nine new dysprosium nickel silicides were detected in Dy–Ni–Si. • Seventeen new rare earth nickel silicides were detected in (Y, Gd–Tm)–Ni–Si. • Tb{sub 3}Ni{sub 8}Si, Dy{sub 3}Ni{sub 8}Si, Ho{sub 3}Ni{sub 12}Si{sub 4} and DyNi{sub 2}Si show ferromagnetic-like ordering.« less

Steric hindrances create a discrete linear Dy4 complex exhibiting SMM behaviour.

PubMed

Lin, Shuang-Yan; Zhao, Lang; Ke, Hongshan; Guo, Yun-Nan; Tang, Jinkui; Guo, Yang; Dou, Jianmin

2012-03-21

Two linear tetranuclear lanthanide complexes of general formula [Ln(4)(L)(2)(C(6)H(5)COO)(12)(MeOH)(4)], where HL = 2,6-bis((furan-2-ylmethylimino)methyl)-4-methylphenol, () and Ln(III) = Dy(III) (1) and Gd(III) (2), have been synthesized and characterized. The crystal structural analysis demonstrates that two Schiff-base ligands inhibit the growth of benzoate bridged 1D chains, leading to the isolation of discrete tetranuclear complexes due to their steric hindrances. Every Ln(III) ion is coordinated by eight donor atoms in a distorted bicapped trigonal-prismatic arrangement. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent out-of-phase signal under zero dc field, typical of single-molecule magnet (SMM) behaviour with an anisotropic barrier Δ(eff) = 17.2 K.

Nonlinear optical crystal optimized for Ytterbium laser host wavelengths

DOEpatents

Ebbers, Christopher A [Pleasanton, CA; Schaffers, Kathleen I [Livermore, CA

2008-05-27

A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4 (BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(B0.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

Nonlinear optical crystal optimized for Ytterbium laser host wavelengths

DOEpatents

Ebbers, Christopher A [Livermore, CA; Schaffers, Kathleen I [Pleasanton, CA

2007-02-20

A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4 (BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(BO.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

Nonlinear optical crystal optimized for ytterbium laser host wavelengths

DOEpatents

Ebbers, Christopher A [Livermore, CA; Schaffers, Kathleen I [Pleasanton, CA

2007-08-21

A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4(BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(B0.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

Dinuclear lanthanide complexes based on amino alcoholate ligands: Structure, magnetic and fluorescent properties

NASA Astrophysics Data System (ADS)

Sun, Gui-Fang; Zhang, Cong-Ming; Guo, Jian-Ni; Yang, Meng; Li, Li-Cun

2017-05-01

Two binuclear lanthanide complexes [Ln2(hfac)6(HL)2] (LnIII = Dy(1), Tb(2); hfac = hexafluoroacetylacetonate, HL = (R)-2-amino-2-phenylethanol) have been successfully obtained by using amino alcoholate ligand. In two complexes, the Ln(III) ions are bridged by two alkoxido groups from HL ligands, resulting in binuclear complexes. The variable-temperature magnetic susceptibility studies indicate that there exists ferromagnetic interaction between two Ln(III) ions. Frequency dependent out-of-phase signals are observed for complex 1, suggesting SMM type behavior. Complexes 1 and 2 display intensely characteristic luminescent properties.

Synthesis and characterization of a family of structurally characterized dysprosium alkoxides for improved fatigue-resistance characteristics of PDyZT thin films.

PubMed

Boyle, Timothy J; Bunge, Scott D; Clem, Paul G; Richardson, Jacob; Dawley, Jeffrey T; Ottley, Leigh Anna M; Rodriguez, Mark A; Tuttle, Bruce A; Avilucea, Gabriel R; Tissot, Ralph G

2005-03-07

Using either an ammoniacal route, the reaction between DyCl3, Na0, and HOR in liquid ammonia, or preferentially reacting Dy(N(SiMe3)2)3 with HOR in a solvent, we isolated a family of dysprosium alkoxides as [Dy(mu-ONep)2(ONep)]4 (1), (ONep)2Dy[(mu3-ONep)(mu-ONep)Dy(ONep)(THF)]2(mu-ONep) (2), (ONep)2Dy[(mu3-ONep)(mu-ONep)Dy(ONep)(py)]2(mu-ONep) (3), [Dy3(mu3-OBut)2(mu-OBut3(OBut)4(HOBut)2] (4), [Dy3(mu3-OBut)2(mu-OBut)3(OBut)4(THF)2] (5), [Dy3(mu3-OBut)2(mu-OBut)3(OBut)4(py)2] (6), (DMP)Dy(mu-DMP)4[Dy(DMP)2(NH3)]2 (7), [Dy(eta6-DMP)(DMP)2]2 (8), Dy(DMP)3(THF)3 (9), Dy(DMP)3(py)3 (10), Dy(DIP)3(NH3)2 (11), [Dy(eta6-DIP)(DIP)2]2 (12), Dy(DIP)3(THF)2 (13), Dy(DIP)3(py)3 (14), Dy(DBP)3(NH3) (15), Dy(DBP)3 (16), Dy(DBP)3(THF) (17), Dy(DBP)3(py)2 (18), [Dy(mu-TPS)(TPS2]2 (19), Dy(TPS)3(THF)3 (20), and Dy(TPS)3(py)3 (21), where ONep = OCH2CMe3, OBut) = OCMe3, DMP = OC6H3(Me)(2)-2,6, DIP = OC6H3(CHMe2)(2)-2,6, DBP = OC6H3(CMe3)(2)-2,6, TPS = OSi(C6H5)3, tol = toluene, THF = tetrahydrofuran, and py = pyridine. We were not able to obtain X-ray quality crystals of compounds 2, 8, and 9. The structures observed and data collected for the Dy compounds are consistent with those reported for its other congeners. A number of these precursors were used as Dy dopants in Pb(Zr0.3Ti0.7)O3 (PZT 30/70) thin films, with compound 12 yielding the highest-quality films. The resulting Pb0.94Dy0.04(Zr0.3Ti0.7)O3 [PDyZT (4/30/70)] had similar properties to PZT (30/70), but showed substantial resistance to polarization reversal fatigue.

Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+ ,Dy3+ co-doped Ba2 MgSi2 O7 phosphors.

PubMed

Sao, Sanjay Kumar; Brahme, Nameeta; Bisen, D P; Tiwari, Geetanjali

2016-11-01

In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu 2 + -doped and Eu 2 + ,Dy 3 + -co-doped Ba 2 MgSi 2 O 7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba 2 MgSi 2 O 7 :Eu 2 + showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba 2 MgSi 2 O 7 :Eu 2 + Dy 3 + showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f 6 5d 1 to 4f 7 transition of Eu 2 + . TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu 2 + doping in Ba 2 MgSi 2 O 7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy 3 + ions were co-doped in Ba 2 MgSi 2 O 7 :Eu 2 + and maximum TL intensity was observed for 2 mol% of Dy 3 + . TL emission spectra of Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co-doping. The trap depths were calculated to be 0.54 eV for Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and 0.54 eV and 0.75 eV for Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors. It was observed that co-doping with small amounts of Dy 3 + enhanced the thermoluminescence properties of Ba 2 MgSi 2 O 7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f 6 5d 1 ', '4f7' has been corrected to '4f 7 ', 'Ba1.95' has been corrected to 'Ba 1.95 ' and 'Ba1.93' has been corrected to 'Ba 1.93 ' respectively.]. Copyright © 2016 John Wiley & Sons, Ltd.

Tunable-color luminescence via energy transfer in NaCa13/18Mg5/18PO4:A (A = Eu2+/Tb3+/Mn2+, Dy3+) phosphors for solid state lighting.

PubMed

Li, Kai; Fan, Jian; Mi, Xiaoyun; Zhang, Yang; Lian, Hongzhou; Shang, Mengmeng; Lin, Jun

2014-11-17

A series of NaCa13/18Mg5/18PO4(NCMPO):A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) phosphors have been prepared by the high-temperature solid-state reaction method. The X-ray diffraction (XRD) and Rietveld refinement, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), cathodoluminescence (CL), decay lifetimes, and PL quantum yields (QYs) were utilized to characterize the phosphors. The pure crystalline phase of as-prepared samples has been demonstrated via XRD measurement and Rietveld refinements. XPS reveals that the Eu(2+)/Tb(3+)/Mn(2+) can be efficiently doped into the crystal lattice. NCMPO:Eu(2+)/Tb(3+)/Mn(2+) phosphors can be effectively excited under UV radiation, which show tunable color from purple-blue to red including white emission based on energy transfer from Eu(2+) to Tb(3+)/Mn(2+) ions. Under low-voltage electron beam bombardment, the NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) display their, respectively, characteristic emissions with different colors, and the CL spectrum of NCMPO:0.04Tb(3+) has the comparable intensity to the ZnO:Zn commercial product. In addition, the calculated CIE coordinate of NCMPO:0.04Tb(3+) (0.252, 0.432) is more saturated than it (0.195, 0.417). These results reveal that NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) may be potential candidate phosphors for WLEDs and FEDs.

Lanthanide Complexes with Multidentate Oxime Ligands as Single-Molecule Magnets and Atmospheric Carbon Dioxide Fixation Systems.

PubMed

Hołyńska, Małgorzata; Clérac, Rodolphe; Rouzières, Mathieu

2015-09-14

The synthesis, structure, and magnetic properties of five lanthanide complexes with multidentate oxime ligands are described. Complexes 1 and 2 (1: [La2 (pop)2 (acac)4 (CH3 OH)], 2: [Dy2 (pop)(acac)5 ]) are synthesized from the 2-hydroxyimino-N-[1-(2-pyridyl)ethylidene]propanohydrazone (Hpop) ligand, while 3, 4, and 5 (3: [Dy2 (naphthsaoH)2 (acac)4 H(OH)]⋅0.85 CH3 CN⋅1.58 H2 O; 4: [Tb2 (naphthsaoH)2 (acac)4 H(OH)]⋅0.52 CH3 CN⋅1.71 H2 O; 5: [La6 (CO3 )2 (naphthsao)5 (naphthsaoH)0.5 (acac)8 (CO3 )0.5 (CH3 OH)2.76 H5.5 (H2 O)1.24 ]⋅2.39 CH3 CN⋅0.12 H2 O) contain 1-(1-hydroxynaphthalen-2-yl)-ethanone oxime (naphthsaoH2 ). In 1-4, dinuclear [Ln2 ] complexes crystallize, whereas hexanuclear La(III) complex 5 is formed after fixation of atmospheric carbon dioxide. Dy(III) -based complexes 2 and 3 display single-molecule-magnet properties with energy barriers of 27 and 98 K, respectively. The presence of a broad and unsymmetrical relaxation mode observed in the ac susceptibility data for 3 suggest two different dynamics of the magnetization which might be a consequence of independent relaxation processes of the two different Dy(3+) ions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3(NIT(C6H4OPh))]: A μ{sup +} spin relaxation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arosio, Paolo, E-mail: paolo.arosio@guest.unimi.it; Orsini, Francesco; Corti, Maurizio

2015-05-07

The spin dynamics of the molecular magnetic chain [Dy(hfac){sub 3}(NIT(C{sub 6}H{sub 4}OPh))] were investigated by means of the Muon Spin Relaxation (μ{sup +}SR) technique. This system consists of a magnetic lattice of alternating Dy(III) ions and radical spins, and exhibits single-chain-magnet behavior. The magnetic properties of [Dy(hfac){sub 3}(NIT(C{sub 6}H{sub 4}OPh))] have been studied by measuring the magnetization vs. temperature at different applied magnetic fields (H = 5, 3500, and 16500 Oe) and by performing μ{sup +}SR experiments vs. temperature in zero field and in a longitudinal applied magnetic field H = 3500 Oe. The muon asymmetry P(t) was fitted by the sum of three components, twomore » stretched-exponential decays with fast and intermediate relaxation times, and a third slow exponential decay. The temperature dependence of the spin dynamics has been determined by analyzing the muon longitudinal relaxation rate λ{sub interm}(T), associated with the intermediate relaxing component. The experimental λ{sub interm}(T) data were fitted with a corrected phenomenological Bloembergen-Purcell-Pound law by using a distribution of thermally activated correlation times, which average to τ = τ{sub 0} exp(Δ/k{sub B}T), corresponding to a distribution of energy barriers Δ. The correlation times can be associated with the spin freezing that occurs when the system condenses in the ground state.« less

Luminescence in Ba2 Sr2 Al2 O7 :RE (RE = Tb(3) (+) ,Eu(3) (+) and Dy(3) (+) ) novel aluminate phosphors.

PubMed

Pardhi, S A; Panse, V R; Dhoble, S J

2016-09-01

The luminescence of novel rare earth (Tb(3) (+) , Eu(3) (+) and Dy(3) (+) )-activated Ba2 Sr2 Al2 O7 phosphors for solid-state lighting is presented. The aluminate phosphors were synthesized using a one-step combustion method. X-Ray diffraction, scanning electron microscopy and photoluminescence characterizations were performed to understand the mechanism of excitation and the corresponding emission in the as-prepared phosphor, as characterized the phase purity and microstructure. Improvements in the luminescence properties of the phosphors with rare earth concentration were observed. The phosphor hue could be tuned from blue, green and red by proper selection of rare earth ions in typical concentrations. Effective absorption in the near-ultraviolet region was observed, which makes the phosphor a potential candidate for ultraviolet light-emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis, Crystal Structures, Magnetic Properties, and Theoretical Investigation of a New Series of NiII-LnIII-WV Heterotrimetallics: Understanding the SMM Behavior of Mixed Polynuclear Complexes.

PubMed

Vieru, Veacheslav; Pasatoiu, Traian D; Ungur, Liviu; Suturina, Elizaveta; Madalan, Augustin M; Duhayon, Carine; Sutter, Jean-Pascal; Andruh, Marius; Chibotaru, Liviu F

2016-12-05

The polynuclear compounds containing anisotropic metal ions often exhibit efficient barriers for blocking of magnetization at fairly arbitrary geometries. However, at variance with mononuclear complexes, which usually become single-molecule magnets (SMM) under the sole requirement of a highly axial crystal field at the metal ion, the factors influencing the SMM behavior in polynuclear complexes, especially, with weakly axial magnetic ions, still remain largely unrevealed. As an attempt to clarify these conditions, we present here the synthesis, crystal structures, magnetic behavior, and ab initio calculations for a new series of Ni II -Ln III -W V trimetallics, [(CN) 7 W(CN)Ni(H 2 O)(valpn)Ln(H 2 O) 4 ]·H 2 O (Ln = Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Lu 6). The surprising finding is the absence of the magnetic blockage even for compounds involving strongly anisotropic Dy III and Tb III metal ions. This is well explained by ab initio calculations showing relatively large transversal components of the g-tensor in the ground exchange Kramers doublets of 1 and 4 and large intrinsic tunneling gaps in the ground exchange doublets of 3 and 5. In order to get more insight into this behavior, another series of earlier reported compounds with the same trinuclear [W V Ni II Ln III ] core structure, [(CN) 7 W(CN)Ni(dmf)(valdmpn)Ln(dmf) 4 ]·H 2 O (Ln = Gd III 7, Tb III 8a, Dy III 9, Ho III 10), [(CN) 7 W(CN)Ni(H 2 O)(valdmpn)Tb(dmf) 2.5 (H 2 O) 1.5 ]·H 2 O·0.5dmf 8b, and [(CN) 7 W(CN)Ni(H 2 O)(valdmpn)Er(dmf) 3 (H 2 O) 1 ]·H 2 O·0.5dmf 11, has been also investigated theoretically. In this series, only 8b exhibits SMM behavior which is confirmed by the present ab initio calculations. An important feature for the entire series is the strong ferromagnetic coupling between Ni(II) and W(V), which is due to an almost perfect trigonal dodecahedron geometry of the octacyano wolframate fragment. The reason why only 8b is an SMM is explained by positive zero-field splitting on the nickel site, precluding magnetization blocking in complexes with fewer axial Ln ions. Further analysis has shown that, in the absence of ZFS on Ni ion, all compounds in the two series (except those containing Y and Gd) would be SMMs. The same situation arises for perfectly axial ZFS on Ni(II) with the main anisotropy axis parallel to the main magnetic axis of Ln(III) ions. In all other cases the ZFS on Ni(II) will worsen the SMM properties. The general conclusion is that the design of efficient SMMs on the basis of such complexes should involve isotropic or weekly anisotropic metal ions, such as Mn(II), Fe(III), etc., along with strongly axial lanthanides.

Thermoluminescence, ESR and x-ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature thermal treatment

NASA Astrophysics Data System (ADS)

Bakshi, A. K.; Patwe, S. J.; Bhide, M. K.; Sanyal, B.; Natarajan, V.; Tyagi, A. K.; Kher, R. K.

2008-01-01

Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000 °C. The influence of the annealing atmosphere on the TL glow curve structure was also observed. Reduction of the photoluminescence intensity of the annealed phosphor indicated that the environment of Dy3+ ions might have undergone some change due to high temperature treatment. Reduction in the ESR signal intensity corresponding to O_{3}^{-} and SO_{3}^{-} radicals was observed initially with the increase in the annealing temperaure; subsequently their intensity increased with temperature. Signals due to the SO_{4}^{-} radical vanished, when the phosphor was annealed beyond 800 °C. A signal corresponding to SH2- radicals was also observed in the ESR spectra for samples subjected to annealing in the temperature regime 800-1000 °C. XRD of the in situ annealed phosphor showed a change in the unit cell parameters. An endothermic peak at 860 °C in the DTA spectrum was observed.

An investigation of density measurement method for yarn-dyed woven fabrics based on dual-side fusion technique

NASA Astrophysics Data System (ADS)

Zhang, Rui; Xin, Binjie

2016-08-01

Yarn density is always considered as the fundamental structural parameter used for the quality evaluation of woven fabrics. The conventional yarn density measurement method is based on one-side analysis. In this paper, a novel density measurement method is developed for yarn-dyed woven fabrics based on a dual-side fusion technique. Firstly, a lab-used dual-side imaging system is established to acquire both face-side and back-side images of woven fabric and the affine transform is used for the alignment and fusion of the dual-side images. Then, the color images of the woven fabrics are transferred from the RGB to the CIE-Lab color space, and the intensity information of the image extracted from the L component is used for texture fusion and analysis. Subsequently, three image fusion methods are developed and utilized to merge the dual-side images: the weighted average method, wavelet transform method and Laplacian pyramid blending method. The fusion efficacy of each method is evaluated by three evaluation indicators and the best of them is selected to do the reconstruction of the complete fabric texture. Finally, the yarn density of the fused image is measured based on the fast Fourier transform, and the yarn alignment image could be reconstructed using the inverse fast Fourier transform. Our experimental results show that the accuracy of density measurement by using the proposed method is close to 99.44% compared with the traditional method and the robustness of this new proposed method is better than that of conventional analysis methods.

Bifunctional Zn(II)Ln(III) dinuclear complexes combining field induced SMM behavior and luminescence: enhanced NIR lanthanide emission by 9-anthracene carboxylate bridging ligands.

PubMed

Palacios, María A; Titos-Padilla, Silvia; Ruiz, José; Herrera, Juan Manuel; Pope, Simon J A; Brechin, Euan K; Colacio, Enrique

2014-02-03

There were new dinuclear Zn(II)-Ln(III) complexes of general formulas [Zn(μ-L)(μ-OAc)Ln(NO3)2] (Ln(III) = Tb (1), Dy (2), Er (3), and Yb (4)), [Zn(μ-L)(μ-NO3)Er(NO3)2] (5), [Zn(H2O)(μ-L)Nd(NO3)3]·2CH3OH (6), [Zn(μ-L)(μ-9-An)Ln(NO3)2]·2CH3CN (Ln(III) = Tb (7), Dy (8), Er (9), Yb(10)), [Zn(μ-L)(μ-9-An)Yb(9-An)(NO3)3]·3CH3CN (11), [Zn(μ-L)(μ-9-An)Nd(9-An)(NO3)3]·2CH3CN·3H2O (12), and [Zn(μ-L)(μ-9-An)Nd(CH3OH)2(NO3)]ClO4·2CH3OH (13) prepared from the reaction of the compartmental ligand N,N',N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L), with ZnX2·nH2O (X = NO3(-) or OAc(-)) salts, Ln(NO3)3·nH2O, and, in some instances, 9-anthracenecarboxylate anion (9-An). In all these complexes, the Zn(II) ions invariably occupy the internal N3O2 site whereas the Ln(III) ions show preference for the O4 external site, giving rise to a Zn(μ-diphenoxo)Ln bridging fragment. Depending on the Zn(II) salt and solvent used in the reaction, a third bridge can connect the Zn(II) and Ln(III) metal ions, giving rise to triple-bridged diphenoxoacetate in complexes 1-4, diphenoxonitrate in complex 5, and diphenoxo(9-anthracenecarboxylate) in complexes 8-13. Dy(III) and Er(III) complexes 2, 8 and 3, 5, respectively, exhibit field induced single molecule magnet (SMM) behavior, with Ueff values ranging from 11.7 (3) to 41(2) K. Additionally, the solid-state photophysical properties of these complexes are presented showing that ligand L(2-) is able to sensitize Tb(III)- and Dy(III)-based luminescence in the visible region through an energy transfer process (antenna effect). The efficiency of this process is much lower when NIR emitters such as Er(III), Nd(III), and Yb(III) are considered. When the luminophore 9-anthracene carboxylate is incorporated into these complexes, the NIR luminescence is enhanced which proves the efficiency of this bridging ligand to act as antenna group. Complexes 2, 3, 5, and 8 can be considered as dual materials as they combine SMM behavior and luminescent properties.

Peripheral Substitution: An Easy Way to Tuning the Magnetic Behavior of Tetrakis(phthalocyaninato) Dysprosium(III) SMMs

PubMed Central

Shang, Hong; Zeng, Suyuan; Wang, Hailong; Dou, Jianmin; Jiang, Jianzhuang

2015-01-01

Two tetrakis(phthalocyaninato) dysprosium(III)-cadmium(II) single-molecule magnets (SMMs) with different extent of phthalocyanine peripheral substitution and therefore different coordination geometry for the Dy ions were revealed to exhibit different SMM behavior, providing an easy way to tuning and controlling the molecular structure and in turn the magnetic properties of tetrakis(tetrapyrrole) lanthanide SMMs through simple tetrapyrrole peripheral substitution. PMID:25744587

Coumarin Derivative Directly Coordinated to Lanthanides Acts as an Excellent Antenna for UV-Vis and Near-IR Emission.

PubMed

Guzmán-Méndez, Óscar; González, Federico; Bernès, Sylvain; Flores-Álamo, Marcos; Ordóñez-Hernández, Javier; García-Ortega, Héctor; Guerrero, Joselin; Qian, Wenjie; Aliaga-Alcalde, Nuria; Gasque, Laura

2018-02-05

A chelating coumarin-derived ligand sensitizes all emitting lanthanide ions in the solid state and gives high absolute quantum yields for ethanol solutions of complexes of Sm, Eu, Tb, and Dy, above 20% for the last two. Crystal structures of these four complexes are [Ln(Cum) 3 (H 2 O)(X)]·X where X = MeOH or EtOH.

Absence of microRNA-21 does not reduce muscular dystrophy in mouse models of LAMA2-CMD.

PubMed

Moreira Soares Oliveira, Bernardo; Durbeej, Madeleine; Holmberg, Johan

2017-01-01

MicroRNAs (miRNAs) are short non-coding RNAs that modulate gene expression post-transcriptionally. Current evidence suggests that miR-21 plays a significant role in the progression of fibrosis in muscle diseases. Laminin-deficient congenital muscular dystrophy (LAMA2-CMD) is a severe form of congenital muscular dystrophy caused by mutations in the gene encoding laminin α2 chain. Mouse models dy3K/dy3K and dy2J/dy2J, respectively, adequately mirror severe and milder forms of LAMA2-CMD. Both human and mouse LAMA2-CMD muscles are characterized by extensive fibrosis and considering that fibrosis is the final step that destroys muscle during the disease course, anti-fibrotic therapies may be effective strategies for prevention of LAMA2-CMD. We have previously demonstrated a significant up-regulation of the pro-fibrotic miR-21 in dy3K/dy3K and dy2J/dy2J skeletal muscle. Hence, the objective of this study was to explore if absence of miR-21 reduces fibrogenesis and improves the phenotype of LAMA2-CMD mice. Thus, we generated dy3K/dy3K and dy2J/dy2J mice devoid of miR-21 (dy3K/miR-21 and dy2J/miR-21 mice, respectively). However, the muscular dystrophy phenotype of dy3K/miR-21 and dy2J/miR-21 double knock-out mice was not improved compared to dy3K/dy3K or dy2J/dy2J mice, respectively. Mice displayed the same body weight, dystrophic muscles (with fibrosis) and impaired muscle function. These data indicate that miR-21 may not be involved in the development of fibrosis in LAMA2-CMD.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robledo, L. M.; Baldo, M.; Schuck, P.

We explore the deformation properties of the newly postulated Barcelona-Catania-Paris (BCP) energy density functional (EDF). The results obtained for three isotope chains of Mg, Dy, and Ra are compared to the available experimental data as well as to the results of the Gogny-D1S force. Results for the fission barrier of {sup 240}Pu are also discussed.

Purification and characterization of two DyP isozymes from Thanatephorus cucumeris Dec 1 specifically expressed in an air-membrane surface bioreactor.

PubMed

Shimokawa, Takuya; Shoda, Makoto; Sugano, Yasushi

2009-02-01

DyP isozymes (DyP2 and DyP3) from the culture fluid of the fungus Thanatephorus cucumeris Dec 1 by air-membrane surface bioreactor were purified and characterized. The characteristics of DyP2 were almost the same as those of a recombinant DyP reported previously, but different from DyP3.

High Curie temperature drive layer materials for ion-implanted magnetic bubble devices

NASA Technical Reports Server (NTRS)

Fratello, V. J.; Wolfe, R.; Blank, S. L.; Nelson, T. J.

1984-01-01

Ion implantation of bubble garnets can lower the Curie temperature by 70 C or more, thus limiting high temperature operation of devices with ion-implanted propagation patterns. Therefore, double-layer materials were made with a conventional 2-micron bubble storage layer capped by an ion-implantable drive layer of high Curie temperature, high magnetostriction material. Contiguous disk test patterns were implanted with varying doses of a typical triple implant. Quality of propagation was judged by quasistatic tests on 8-micron period major and minor loops. Variations of magnetization, uniaxial anisotropy, implant dose, and magnetostriction were investigated to ensure optimum flux matching, good charged wall coupling, and wide operating margins. The most successful drive layer compositions were in the systems (SmDyLuCa)3(FeSi)5O12 and (BiGdTmCa)3(FeSi)5O12 and had Curie temperatures 25-44 C higher than the storage layers.

Structural and optical properties of Dy3+ doped Aluminofluoroborophosphate glasses for white light applications

NASA Astrophysics Data System (ADS)

Vijayakumar, M.; Mahesvaran, K.; Patel, Dinesh K.; Arunkumar, S.; Marimuthu, K.

2014-11-01

Dy3+ doped Aluminofluoroborophosphate glasses (BPAxD) have been prepared following conventional melt quenching technique and their structural and optical properties were explored through XRD, FTIR, optical absorption, excitation, emission and decay measurements. The coexistence of BO3 groups in borate rich domain and BO4 groups in phosphate rich domain have been confirmed through vibrational energy analysis. Negative bonding parameter (δ) values indicate that, the metal-ligand environment in the prepared glasses is of ionic in nature. The oscillator strength and the luminescent intensity Ωλ (λ = 2, 4 and 6) parameters are calculated using Judd-Ofelt theory. The radiative properties such as transition probability (A), stimulated emission cross-section (σpE) and branching ratios (β) have been calculated using JO intensity parameters and compared with the reported Dy3+ doped glasses. Concentration effect on Y/B intensity ratios and the CIE chromaticity coordinates were calculated for the generation of white light from the luminescence spectra. The color purity and the correlated color temperature were also calculated and the results are discussed in the present work. The decay of the 4F9/2 excited level is found to be single exponential for lower concentration and become non-exponential for higher concentration. The non-exponential behavior arises due to the efficient energy transfer between the Dy3+ ions through various non-radiative relaxation channels and the decay of the 4F9/2 excited level have been analyzed with IH model. Among the prepared glasses, BPA0.5D glass exhibits higher σpE, βR, σpE×σpE, σpE×Δλeff and η values for the 6H13/2 emission band which in turn specifies its suitability for white LEDs, laser applications and optical amplifiers.

Mixed (phthalocyaninato)(Schiff-base) di-dysprosium sandwich complexes. Effect of magnetic coupling on the SMM behavior.

PubMed

Wang, Hailong; Liu, Chenxi; Liu, Tao; Zeng, Suyuan; Cao, Wei; Ma, Qi; Duan, Chunying; Dou, Jianmin; Jiang, Jianzhuang

2013-11-21

Reaction between Schiff-base ligand and half-sandwich complex M(Pc)(acac) led to the isolation of new sandwich-type mixed (phthalocyaninato)(Schiff-base) di-lanthanide compounds M2(Pc)2(L)H2O (M = Dy, Gd) (1, 2) [H2Pc = metal free phthalocyanine, Hacac = acetylacetone, H2L = N,N'-bis(3-methyloxysalicylidene)benzene-1,2-diamine] with the triple-decker molecular structure clearly revealed by single crystal X-ray diffraction analysis. For the comparative studies, sandwich triple-decker analogues with pure Schiff-base ligand M2(L)3H2O (M = Dy, Gd) (3, 4) were also prepared. Dynamic magnetic measurement result reveals the single-molecule magnet (SMM) nature of the di-dysprosium derivative 1, while the static magnetic investigation over both pure and the diamagnetic diluted samples of this compound discloses the interionic ferromagnetic coupling between the two dysprosium ions, which in turn effectively suppresses the QTM and enhances the energy barrier of this SMM. Nevertheless, comparative studies over the static magnetic properties of the di-dysprosium triple-decker complexes 1 and 3 indicate the stronger magnetic coupling between the two lanthanide ions in mixed (phthalocyaninato)(Schiff-base) species than in the pure Schiff-base triple-decker analogue, suggesting the special coordination sphere around the dysprosium ions in the former compound over the latter one on the more intense inter-ionic ferromagnetic coupling. As a very small step towards understanding the structure-property relationship, the present result will be surely helpful for the design and synthesis of the multinuclear lanthanide-based SMMs with good properties.

Smart polymer brush nanostructures guide the self-assembly of pore-spanning lipid bilayers with integrated membrane proteins

NASA Astrophysics Data System (ADS)

Wilhelmina de Groot, G.; Demarche, Sophie; Santonicola, M. Gabriella; Tiefenauer, Louis; Vancso, G. Julius

2014-01-01

Nanopores in arrays on silicon chips are functionalized with pH-responsive poly(methacrylic acid) (PMAA) brushes and used as supports for pore-spanning lipid bilayers with integrated membrane proteins. Robust platforms are created by the covalent grafting of polymer brushes using surface-initiated atom transfer radical polymerization (ATRP), resulting in sensor chips that can be successfully reused over several assays. His-tagged proteins are selectively and reversibly bound to the nitrilotriacetic acid (NTA) functionalization of the PMAA brush, and consequently lipid bilayer membranes are formed. The enhanced membrane resistance as determined by electrochemical impedance spectroscopy and free diffusion of dyed lipids observed as fluorescence recovery after photobleaching confirmed the presence of lipid bilayers. Immobilization of the His-tagged membrane proteins on the NTA-modified PMAA brush near the pore edges is characterized by fluorescence microscopy. This system allows us to adjust the protein density in free-standing bilayers, which are stabilized by the polymer brush underneath. The potential application of the integrated platform for ion channel protein assays is demonstrated.

PSEUDO-BINARY SYSTEMS INVOLVING RARE EARTH LAVES PHASES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wernick, J.H.; Haszko, S.E.; Dorsi, D.

1962-06-01

The phase relations in a number of pseudo-binary systems involving rare earth Laves phases were determined. Complete series of cubic solid-solutions occur in the DyMn/sub 2/HoMn/sub 2/, HoMn/sub 2/-HoFe/sub 2/, DyMn/sub 2/-DyFe/ sub 2/, HoMn/sub 2/-HoAl/ sub 2/, TbMn/sub 2/TbAl/sub 2/, and DyMn/sub 2/-DyAl/ sub 2/ pseudobinary systems. Deviations from linearity in the lattice constants with composition occur in all these systems. Complete series of cubic solidsolutions also exist in the GdAl/sub 2/-ErAl/sub 2/, GdAl/sub 2/-PrAl/sub 2/ , GdAl/sub 2/-NdAl/sub 2/, GdAl/sub 2/-DyAl/sub 2/, TbAl/sub 2/-NdAl/sub 2/, and T bAl/sub 2/-DyAl/sub 2/ systems. For these systems, no deviation from linearitymore » occurs in the lattice constants. For the DyFe/sub 2/-DyAl/sub 2/ and DyCo/sub 2/- DyAl/sub 2/ systems, two new ternary phases, DyFeAl and DyCoAl, form and have the MgZn/sub 2/ structure. Their structures were determined from x-ray powder data only. The electronic state giving rise to the formation of these ternary phases is discussed qualitatively. For the DyMn/sub 2/TmMn/sub 2/ system, the range of composition in which the cubic MgCu/sub 2/ and hexagonal MgZn/sub 2/ structures exist are reported. No complete series of solid solutions or intermediate phases are formed in the DyNi/sub 2/-DyAl/sub 2/ system. (auth)« less

Energy storage properties of Dy3+ doped Sr0.5Ba0.5Nb2O6 thick film with nano-size grains

NASA Astrophysics Data System (ADS)

Yang, Daeyeol; Kang, Soo-Bin; Lim, Ji-Ho; Yoon, Songhyeon; Ryu, Jungho; Choi, Jong-Jin; Velayutham, Thamil Selvi; Kim, Hyungsun; Jeong, Dae-Yong

2017-09-01

We studied the temperature stable high-energy storage capacitors. Sr0.5Ba0.5Nb2O6 (SBN) is the lead-free ferroelectric solid solution between BaNb2O6 and SrNb2O6. By doping Dy into SBN, the Curie temperature was lowered and dielectric constant was increased. To improve the breakdown behavior of Dy-doped SBN, the aerosoldeposition(AD) was applied to fabricate the dense films with nano-sized grains. These nano-grain give a large number of grain boundaries, suppressing the electron conduction in ceramics. The dielectric constant and breakdown electric field of the AD films annealed at 650 °C were measured as 2307 and 9.9 MV/m, while bulk were 1080 and 4 MV/m. Energy density and efficiency of the AD films annealed at 650 °C were also enhanced as 0.65 J/cc and 90.2% and bulk were 0.08 J/cc and 72.1%, respectively. In addition, the dielectric constant of AD film annealed at 550 °C and 650 °C were quite stable up to 150 °C.

Three isostructural one-dimensional Ln(III) chains with distorted cubane motifs showing dual fluorescence and slow magnetic relaxation/magnetocaloric effect.

PubMed

Li, Yan; Yu, Jia-Wen; Liu, Zhong-Yi; Yang, En-Cui; Zhao, Xiao-Jun

2015-01-05

Three new homometallic lanthanide complexes with mixed carboxylate-modified rigid ligands, [Ln(μ3-OH)(na)(pyzc)]n (na(-) = 1-naphtholate, pyzc(-) = 2-pyrazinecarboxylate, Ln = Dy (1), Yb (2), and Gd (3)), were solvothermally synthesized, and their structures and magnetic as well as photophysical properties were completely investigated. Complexes 1-3 are crystallographically isostructural, exhibiting linear chains with four bidentate bridging μ-COO(-) moieties encapsulated cubic {Ln4(μ3-OH)4}(8+) clusters repeatedly extended by 4-fold chelating-bridging-pyzc(-) connectors. Magnetically, the former two complexes with highly anisotropic Dy(III) and weak anisotropic Yb(III) ions in the distorted NO7 triangular dodecahedron coordination environment display field-induced slow relaxation of magnetization. Fitting the dynamic magnetic data to the Arrhenius law gives energy barrier ΔE/kB = 39.6 K and pre-exponential factor τo = 1.52 × 10(-8) s for 1 and ΔE/kB = 14.1 K and τo = 2.13 × 10(-7) s for 2. By contrast, complex 3 with isotropic Gd(III) ion and weak intracluster antiferromagnetic coupling shows a significant cryogenic magnetocaloric effect, with a maximum -ΔSm value of 30.0 J kg(-1) K(-1) at 2.5 K and 70 kOe. Additionally, the chromophoric na(-) and pyzc(-) ligands can serve as antenna groups, selectively sensitizing the Dy(III)- and Yb(III)-based luminescence of 1 and 2 in the UV-visible region by an intramolecular energy transfer process. Thus, complexes 1-3, incorporating field-induced slow magnetic magnetization and interesting luminescence together, can be used as composite magneto-optical materials. More importantly, these interesting results further demonstrate that the mixed-ligand system with rigid carboxylate-functionalized chromophores can be excellent candidates for the preparations of new bifunctional magneto-optical materials.

Synthesis, structures, and luminescent and magnetic properties of Ln-Ag heterometal-organic frameworks.

PubMed

Zhao, Xiao-Qing; Zhao, Bin; Wei, Shi; Cheng, Peng

2009-12-07

A series of Ln-Ag heterometal-organic frameworks based on 4-hydroxylpyridine-2,6-dicarboxylic acid (H(3)CAM) with formulas {LaAg(2)(CAM)(HCAM)(H(2)O)(2)}(n) (1), {LnAg(HCAM)(2)(H(2)O)(3)}(n) (Ln = Pr, 2; Nd, 3; Sm, 4; Eu, 5), and {LnAg(3)(CAM)(2)(H(2)O)}(n) (Ln = Gd, 6; Tb, 7; Dy, 8; Tm, 9; Yb, 10), have been synthesized with the hydrothermal reaction of Ln(OH)(3), Ag(2)O, and H(3)CAM at 160 degrees C. The single-crystal X-ray diffraction analyses reveal that three kinds of structures are exclusively governed by the size of lanthanide ions and the progression of structures is mainly ascribed to the lanthanide contraction effect. Compound 1 consists of a 3D network with an alpha-polonium-like Ag(+)-homometallic net and helical La(3+) chain. Compounds 2-5 display a 2D honeycomb-like structure with 18-membered Ln(3)Ag(3)O(12) motifs, and compounds 6-10 can be described as a sandwich-like 3D framework built of a 3D Ag(+)-homometallic net and 2D Ln(3+)-4(4) layer. In 4 (Sm), 5 (Eu), 7 (Tb), and 8 (Dy) samples, the efficient energy transfer from CAM to Ln(III) ions was observed, which results in the typical intense emissions of corresponding Ln(III) ions in the visible region, and the strongest emissions are (4)G(5/2) --> (6)H(7/2) (602 nm), (5)D(0) --> (7)F(2) (614 nm), (5)D(4) --> (7)F(5) (548 nm), and (4)F(9/2) --> (6)H(13/2) (576 nm) transitions. Variable-temperature magnetic susceptibility measurements of 6-10 show that the ferromagnetic interaction between gadolinium(III) ions appears in 6, whereas the mu(eff) values of 7-10 smoothly decrease on cooling. For the orbital contribution of Ln(III) ions, it is very difficult to determine the intrinsic magnetic interactions between Ln(III) ions.

Molecular assembly and magnetic dynamics of two novel Dy6 and Dy8 aggregates.

PubMed

Guo, Yun-Nan; Chen, Xiao-Hua; Xue, Shufang; Tang, Jinkui

2012-04-02

Complexation of dysprosium(III) with the heterodonor chelating ligand o-vanillin picolinoylhydrazone (H(2)ovph) in the presence of a carbonato ligand affords two novel Dy(6) and Dy(8) clusters, namely, [Dy(6)(ovph)(4)(Hpvph)(2)Cl(4)(H(2)O)(2)(CO(3))(2)]·CH(3)OH·H(2)O·CH(3)CN (2) and [Dy(8)(ovph)(8)(CO(3))(4)(H(2)O)(8)]·12CH(3)CN·6H(2)O (3). Compound 2 is composed of three petals of the Dy(2) units linked by two carbonato ligands, forming a triangular prism arrangement, while compound 3 possesses an octanuclear core with an unprecedented tub conformation, in which Dy(ovph) fragments are attached to the sides of the carbonato core. The static and dynamic magnetic properties are reported and discussed. In the Dy(6) aggregate, three Dy(2) "skeletons", having been well preserved (see the scheme), contribute to the single-molecule-magnet behavior with a relatively slow tunneling rate, while the Dy(8) cluster only exhibits a rather small relaxation barrier.

Influence of Dy in solid solution on the degradation behavior of binary Mg-Dy alloys in cell culture medium.

PubMed

Yang, Lei; Ma, Liangong; Huang, Yuanding; Feyerabend, Frank; Blawert, Carsten; Höche, Daniel; Willumeit-Römer, Regine; Zhang, Erlin; Kainer, Karl Ulrich; Hort, Norbert

2017-06-01

Rare earth element Dy is one of the promising alloying elements for magnesium alloy as biodegradable implants. To understand the effect of Dy in solid solution on the degradation of Mg-Dy alloys in simulated physiological conditions, the present work studied the microstructure and degradation behavior of Mg-Dy alloys in cell culture medium. It is found the corrosion resistance enhances with the increase of Dy content in solid solution in Mg. This can be attributed to the formation of a relatively more corrosion resistant Dy-enriched film which decreases the anodic dissolution of Mg. Copyright © 2017 Elsevier B.V. All rights reserved.

Luminescence analysis of SrGa2 Si2 O8 : RE3+ (RE = Dy, Tm) phosphors.

PubMed

R Kadukar, Monali; Dhoble, S J; Sahu, A K; Nayar, V; Sailaja, S; Reddy, B Sudhakar

2017-03-01

This article reports on the luminescence properties of rare earth (Dy 3 + and Tm 3 + )ions doped SrGa 2 Si 2 O 8 phosphor were studied. SrGa 2 Si 2 O 8 phosphors weresynthesizedby employing solid state reaction method.From the measured X-ray diffraction (XRD) pattern of the samplemonoclinic phase structure has been observed. Thermoluminescenceand Mechanoluminescence properties of the γ-ray irradiated samples have been studied. Photoluminescence spectra of Dy 3 + activated SrGa 2 Si 2 O 8 phosphor has been measured with an excitation wavelength at 348 nm,and it shows two emission bands at 483 and 574 nm due to 4 F 9 /2  →  6 H 15 /2 and 4 F 9 /2  →  6 H 13 /2 transitions respectively. Whereas the photoluminescence spectra of Tm 3 + activated SrGa 2 Si 2 O 8 phosphor has been measured with an excitation wavelength at 359 nm and it exhibits two emission bands at 454 and 472 nm due to 1 D 2  →  3 F 4 and 1 G 4  →  3 H 6 transitions respectively. In thermoluminescence study, γ-irradiatedthermoluminescence glow curve of SrGa 2 Si 2 O 8 :Dy 3 + phosphor shows two well defined peaks at 293 °C (peak1)and 170 °C (peak2) whereas thermoluminescence glow curve of SrGa 2 Si 2 O 8 :Tm 3 + phosphor shows peaks at 292 °C (peak1) and 184 °C (peak2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameters associated with the prominent glow peaks of SrGa 2 Si 2 O 8 :Dy 3 + and SrGa 2 Si 2 O 8 :Tm 3 + are calculated using Chen's peak shape and initial rise method.From the Mechanoluminescence study, only one glow peak has been observed. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Magnetostriction of some rare earth-aluminum Laves phase compounds

NASA Technical Reports Server (NTRS)

Pourarian, F.; Wallace, W. E.

1979-01-01

Measurements of the linear and volume magnetostriction of RAl2 cubic Laves compounds in which R is one of the rare earth elements Gd, Dy, Ho or Er, at temperatures between 4.2 K and the Curie temperature of each compound, are reported. Magnetic fields up to 2.5 Tesla were applied, and magnetostriction was measured using standard strain gage techniques. Saturation magnetostrictions of 17 x 10 to the -6th, -1420 x 10 to the -6th, 60 x 10 to the -6th and -920 x 10 to the -6th are determined at 4.2 K for GdAl2, DyAl2, HoAl2 and ErAl2, respectively. Large forced magnetostriction is observed in GdAl2 above the saturation field and the strain temperature dependence shows a decrease in magnitude below 40 K. A linear dependence of magnetostriction on magnetic field was observed for DyAl2 above 40 K, and the observed temperature dependence is interpreted in terms of the lowest order single-ion magnetoelastic theory. An observed decrease in the magnitude of the strain of HoAl2 below 15 K is associated with a change of the easy direction of magnetization, while in the case of ErAl2, magnetostriction is observed to occur normally up to the Curie temperature. Large volume magnetostriction is obtained for all the compounds with the exception of GdAl2.

Identical superdeformed bands in yrast 152Dy: a systematic description

NASA Astrophysics Data System (ADS)

Dadwal, Anshul; Mittal, H. M.

2018-06-01

The nuclear softness (NS) formula, semiclassical particle rotor model (PRM) and modified exponential model with pairing attenuation are used for the systematic study of the identical superdeformed bands in the A ∼ 150 mass region. These formulae/models are employed to study the identical superdeformed bands relative to the yrast SD band 152Dy(1), {152Dy(1), 151Tb(2)}, {152Dy(1), 151Dy(4)} (midpoint), {152Dy(1), 153Dy(2)} (quarter point), {152Dy(1), 153Dy(3)} (three-quarter point). The parameters, baseline moment of inertia ({{I}}0), alignment (i) and effective pairing parameter (Δ0) are calculated using the least-squares fitting of the γ-ray transitions energies in the NS formula, semiclassical-PRM and modified exponential model with pairing attenuation, respectively. The calculated parameters are found to depend sensitively on the proposed baseline spin (I 0).

Rational Design of a Lanthanide-Based Complex Featuring Different Single-Molecule Magnets.

PubMed

Pointillart, F; Guizouarn, T; Lefeuvre, B; Golhen, S; Cador, O; Ouahab, L

2015-11-16

The rational synthesis of the 2-{1-methylpyridine-N-oxide-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1H-benzimidazol-2-yl}pyridine ligand (L) is described. It led to the tetranuclear complex [Dy4(tta)12(L)2] (Dy-Dy2-Dy) after coordination reaction with the precursor Dy(tta)3⋅2 H2O (tta(-) = 2-thenoyltrifluoroacetonate). The X-ray structure of Dy-Dy2-Dy can be described as two terminal mononuclear units bridged by a central antiferromagnetically coupled dinuclear complex. The terminal N2O6 and central O8 environments are described as distorted square antiprisms. The ac magnetism measurements revealed a strong out-of-phase signal of the magnetic susceptibility with two distinct sets of data. The high- and low-frequency components were attributed to the two terminal mononuclear single-molecule magnets (SMMs) and the central dinuclear SMM, respectively. A magnetic hysteresis loop was detected at very low temperature. From both structural and magnetic points of view, the tetranuclear SMM Dy-Dy2-Dy is a self-assembly of two known mononuclear SMMs bridged by a known dinuclear SMM. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intralanthanide Separation on Layered Titanium(IV) Organophosphate Materials via a Selective Transmetalation Process.

PubMed

Zhang, Wenzhong; Hietala, Sami; Khriachtchev, Leonid; Hatanpää, Timo; Doshi, Bhairavi; Koivula, Risto

2018-06-21

The lanthanides (Ln) are an essential part of many advanced technologies. Our societal transformation toward renewable energy drives their ever-growing demand. The similar chemical properties of the Ln pose fundamental difficulties in separating them from each other, yet high purity elements are crucial for specific applications. Here, we propose an intralanthanide separation method utilizing a group of titanium(IV) butyl phosphate coordination polymers as solid-phase extractants. These materials are characterized, and they contain layered structures directed by the hydrophobic interaction of the alkyl chains. The selective Ln uptake results from the transmetalation reaction (framework metal cation exchange), where the titanium(IV) serves as sacrificial coordination centers. The "tetrad effect" is observed from a dilute Ln 3+ mixture. However, smaller Ln 3+ ions are preferentially extracted in competitive binary separation models between adjacent Ln pairs. The intralanthanide ion-exchange selectivity arises synergistically from the coordination and steric strain preferences, both of which follow the reversed Ln contraction order. A one-step aqueous separation of neodymium (Nd) and dysprosium (Dy) is quantitatively achievable by simply controlling the solution pH in a batch mode, translating into a separation factor of greater than 2000 and 99.1% molar purity of Dy in the solid phase. Coordination polymers provide a versatile platform for further exploring selective Ln separation processes via the transmetalation process.

Syntheses, structures and luminescent properties of a series of 3D lanthanide coordination polymers with tripodal semirigid ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin Junsheng; Department of Applied Chemistry, Jilin Institute of Chemical Technology, Jilin 132022; Du Dongying

2011-02-15

Reactions of the tripodal bridging ligand 5-(4-carboxy-phenoxy)-isophthalic acid (abbreviated as H{sub 3}cpia) with lanthanide salts lead to the formation of a family of different coordination polymers, that is, [Ln(cpia)(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (Ln=Ce (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Dy (7), Er (8), Tm (9) and Y (10)) in the presence of formic acid or diethylamine, which are characterized by elemental analysis, IR spectrum, thermogravimetric analysis (TGA), XRPD spectrum and single-crystal X-ray diffraction. Compounds 1-10 are isostructural and exhibit three-dimensional microporous frameworks. Furthermore, the photoluminescent properties of 4, 5 and 7 have been studiedmore » in detail. -- Graphical abstract: Reactions of the tripodal bridging ligand (H{sub 3}cpia) with lanthanide ions lead to the formation of a series of coordination polymers in the presence of formic acid or diethylamine. Display Omitted Research Highlights: {yields} Ten new lanthanides-based coordination polymers (1-10) have been synthesized. {yields} 1-10 exhibit 3D (4,8)-connected fluorite topology networks with 1D channel parallel to the b-axis. {yields} Compounds 4, 5 and 7 exhibit characteristic luminescence of Sm{sup 3+}, Eu{sup 3+} and Dy{sup 3+} ions, respectively.« less

Microstructure characterization and room temperature deformation of a rapidly solidified NiAl-based eutectic alloy containing trace Dy

NASA Astrophysics Data System (ADS)

Li, Hutian; Guo, Jianting; Huai, Kaiwen; Ye, Hengqiang

2006-04-01

The microstructure and room temperature compressive deformation behavior of a rapidly solidified NiAl-Cr(Mo)-Dy eutectic alloy fabricated by water-cooled copper mold method were studied by a combination of SEM, EDS and compressive tests. The morphology stability after hot isostatic pressing (HIP) treatment was evaluated. Rapid solidification resulted in a shift in the coupled zone for the eutectic growth towards the Cr(Mo) phase, indicating a hypoeutectic composition, hence increasing the volume fraction of primary dendritic NiAl. Meanwhile, significantly refined microstructure and lamellar/rod-like Cr(Mo) transition were observed due to trace rare earth (RE) element Dy addition and rapid solidification effects. Compared with the results in literature [H.E. Cline, J.L. Walter, Metall. Trans. 1(1970)2907-2917; P. Ferrandini, W.W. Batista, R. Caram, J. Alloys Comp. 381(2004)91-98], an interesting phenomenon, viz., NiAl halos around the primary Cr(Mo) dendrites in solidified NiAl-Cr(Mo) hypereutectic alloy, was not observed in this study. This difference was interpreted in terms of their different reciprocal nucleation ability. In addition, it was proposed that the localized destabilization of morphology after HIP treatment is closely related to the presence of primary NiAl dendrites. The improved mechanical properties can be attributed to the synergistic effects of rapid solidification and Dy addition, which included refined microstructure, suppression of the crack development along eutectic grain boundaries, enhancement of density of geometrically necessary dislocations located at NiAl/Cr(Mo) interfaces and the Cr solubility extension in NiAl.

Direct Measurement of the Mass Difference of 163Ho and 163Dy Solves the Q -Value Puzzle for the Neutrino Mass Determination

NASA Astrophysics Data System (ADS)

Eliseev, S.; Blaum, K.; Block, M.; Chenmarev, S.; Dorrer, H.; Düllmann, Ch. E.; Enss, C.; Filianin, P. E.; Gastaldo, L.; Goncharov, M.; Köster, U.; Lautenschläger, F.; Novikov, Yu. N.; Rischka, A.; Schüssler, R. X.; Schweikhard, L.; Türler, A.

2015-08-01

The atomic mass difference of 163 and 163Dy has been directly measured with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. Our measurement has solved the long-standing problem of large discrepancies in the Q value of the electron capture in 163Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 [G. Audi et al., Chin. Phys. C 36, 1157 (2012)] by more than 7 σ to 2833 (30stat)(15sys) eV /c2 . With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude.

Ferrotoroidic ground state in a heterometallic {CrIIIDyIII6} complex displaying slow magnetic relaxation.

PubMed

Vignesh, Kuduva R; Soncini, Alessandro; Langley, Stuart K; Wernsdorfer, Wolfgang; Murray, Keith S; Rajaraman, Gopalan

2017-10-18

Toroidal quantum states are most promising for building quantum computing and information storage devices, as they are insensitive to homogeneous magnetic fields, but interact with charge and spin currents, allowing this moment to be manipulated purely by electrical means. Coupling molecular toroids into larger toroidal moments via ferrotoroidic interactions can be pivotal not only to enhance ground state toroidicity, but also to develop materials displaying ferrotoroidic ordered phases, which sustain linear magneto-electric coupling and multiferroic behavior. However, engineering ferrotoroidic coupling is known to be a challenging task. Here we have isolated a {Cr III Dy III 6 } complex that exhibits the much sought-after ferrotoroidic ground state with an enhanced toroidal moment, solely arising from intramolecular dipolar interactions. Moreover, a theoretical analysis of the observed sub-Kelvin zero-field hysteretic spin dynamics of {Cr III Dy III 6 } reveals the pivotal role played by ferrotoroidic states in slowing down the magnetic relaxation, in spite of large calculated single-ion quantum tunneling rates.

"Smart" theranostic lanthanide nanoprobes with simultaneous up-conversion fluorescence and tunable T1-T2 magnetic resonance imaging contrast and near-infrared activated photodynamic therapy.

PubMed

Zhang, Yan; Das, Gautom Kumar; Vijayaragavan, Vimalan; Xu, Qing Chi; Padmanabhan, Parasuraman; Bhakoo, Kishore K; Selvan, Subramanian Tamil; Tan, Timothy Thatt Yang

2014-11-07

The current work reports a type of "smart" lanthanide-based theranostic nanoprobe, NaDyF4:Yb(3+)/NaGdF4:Yb(3+),Er(3+), which is able to circumvent the up-converting poisoning effect of Dy(3+) ions to give efficient near infrared (980 nm) triggered up-conversion fluorescence, and offers not only excellent dark T2-weighted MR contrast but also tunable bright and T1-weighted MR contrast properties. Due to the efficient up-converted energy transfer from the nanocrystals to chlorin e6 (Ce6) photosensitizers loaded onto the nanocrystals, cytotoxic singlet oxygen was generated and photodynamic therapy was demonstrated. Therefore, the current multifunctional nanocrystals could be potentially useful in various image-guided diagnoses where bright or dark MRI contrast could be selectively tuned to optimize image quality, but also as an efficient and more penetrative near-infrared activated photodynamic therapy agent.

General synthesis and structural evolution of a layered family of Ln8(OH)20Cl4 x nH2O (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y).

PubMed

Geng, Fengxia; Matsushita, Yoshitaka; Ma, Renzhi; Xin, Hao; Tanaka, Masahiko; Izumi, Fujio; Iyi, Nobuo; Sasaki, Takayoshi

2008-12-03

The synthesis process and crystal structure evolution for a family of stoichiometric layered rare-earth hydroxides with general formula Ln(8)(OH)(20)Cl(4) x nH(2)O (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y; n approximately 6-7) are described. Synthesis was accomplished through homogeneous precipitation of LnCl(3) x xH(2)O with hexamethylenetetramine to yield a single-phase product for Sm-Er and Y. Some minor coexisting phases were observed for Nd(3+) and Tm(3+), indicating a size limit for this layered series. Light lanthanides (Nd, Sm, Eu) crystallized into rectangular platelets, whereas platelets of heavy lanthanides from Gd tended to be of quasi-hexagonal morphology. Rietveld profile analysis revealed that all phases were isostructural in an orthorhombic layered structure featuring a positively charged layer, [Ln(8)(OH)(20)(H(2)O)(n)](4+), and interlayer charge-balancing Cl(-) ions. In-plane lattice parameters a and b decreased nearly linearly with a decrease in the rare-earth cation size. The interlamellar distance, c, was almost constant (approximately 8.70 A) for rare-earth elements Nd(3+), Sm(3+), and Eu(3+), but it suddenly decreased to approximately 8.45 A for Tb(3+), Dy(3+), Ho(3+), and Er(3+), which can be ascribed to two different degrees of hydration. Nd(3+) typically adopted a phase with high hydration, whereas a low-hydration phase was preferred for Tb(3+), Dy(3+), Ho(3+), Er(3+), and Tm(3+). Sm(3+), Eu(3+), and Gd(3+) samples were sensitive to humidity conditions because high- and low-hydration phases were interconvertible at a critical humidity of 10%, 20%, and 50%, respectively, as supported by both X-ray diffraction and gravimetry as a function of the relative humidity. In the phase conversion process, interlayer expansion or contraction of approximately 0.2 A also occurred as a possible consequence of absorption/desorption of H(2)O molecules. The hydration difference was also evidenced by refinement results. The number of coordinated water molecules per formula weight, n, changed from 6.6 for the high-hydration Gd sample to 6.0 for the low-hydration Gd sample. Also, the hydration number usually decreased with increasing atomic number; e.g., n = 7.4, 6.3, 7.2, and 6.6 for high-hydration Nd, Sm, Eu, and Gd, and n = 6.0, 5.8, 5.6, 5.4, and 4.9 for low-hydration Gd, Tb, Dy, Ho, and Er. The variation in the average Ln-O bond length with decreasing size of the lanthanide ions is also discussed. This family of layered lanthanide compounds highlights a novel chemistry of interplay between crystal structure stability and coordination geometry with water molecules.

Reddish-orange, neutral and warm white emissions in Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses

NASA Astrophysics Data System (ADS)

Rodríguez-Carvajal, David A.; Meza-Rocha, A. N.; Caldiño, U.; Lozada-Morales, R.; Álvarez, E.; Zayas, Ma. E.

2016-11-01

Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses were prepared using the melt-quenching process and analyzed by X-diffraction, Raman spectroscopy, excitation and emission spectra, and emission decay time profiles. The lack of X ray diffraction peaks revealed that all samples are amorphous. Vibrational modes associated with Tesbnd Osbnd Te and Gesbnd Osbnd Ge related bonds and molecular oxygen were detected by Raman spectroscopy. The luminescence characteristics were studied upon excitations that correspond with the emission of InGaN (370-420 nm) based LEDs. The Eu3+ singly doped glass displayed reddish-orange global emission, with x = 0.601 and y = 0.349 CIE1931 chromaticity coordinates, upon 393 nm excitation. Neutral emission with x = 0.373 and y = 0.412 CIE1931 chromaticity coordinates and correlated color temperature (CCT) of 4400 K, was achieved in the Dy3+ singly doped glass excited at 388 nm. The Dy3+/Eu3+ co-doped glass exhibited warm, neutral and soft warm white emissions with CCT values of 3435, 4153 and 2740 K, under excitations at 382, 388 and 393 nm, respectively, depending mainly on the Dy3+ and Eu3+ relative excitation. The Dy3+ excitation bands observed in the Dy3+/Eu3+ glass by monitoring the 611 nm Eu3+ emission, suggest that Dy3+ → Eu3+ energy transfer takes place, despite the fact that the Dy3+ emission decays in the Dy3+ and Dy3+/Eu3+ doped glass, remain without changes. The shortening of Eu3+ decay in presence of Dy3+ was attributed to an Eu3+ → Dy3+ non-radiative energy transfer process, which according with the Inokuti-Hirayama model might be dominated through an electric quadrupole-quadrupole interaction, with efficiency and probability of 5.5% and 51.6 s-1, respectively.

Location and magnetic relaxation properties of the stable tyrosine radical in photosystem II.

PubMed

Innes, J B; Brudvig, G W

1989-02-07

Dipolar interactions with neighboring metal ions can cause enhanced spin-lattice relaxation of free radicals. We have applied the theory of dipolar relaxation enhancement and shown that the dependence of the enhanced relaxation on the protein structure surrounding the free radical can be used to obtain distances from the free radical to the protein surface. To test the theoretical predictions, we have examined the effect of added Dy3+ complexes on the microwave power saturation of free radicals in two protein complexes of known structure: myoglobin nitroxide and the reaction center from Rhodobacter sphaeroides. Three cases have been considered: (1) metal ions bound to a specific site, (2) metal ions bound randomly over the protein surface, and (3) metal ions distributed randomly in solution. Only case 3, which assumes no specific binding, gave good agreement between the distances obtained by using the two model systems. The effect of added Dy3+ complexes on the microwave power saturation of signal IIslow from photosystem II (PSII) was used to determine the location of the stable tyrosine radical giving rise to signal IIslow. Assuming that the surface of a membrane-bound protein can be approximated as planar, we have obtained distances from the tyrosine radical to the membrane surface in thylakoids, in PSII membranes, and in Tris-washed PSII membranes. The distances we have determined are in good agreement with those predicted on the basis of a structural homology between the D1 and D2 subunits of PSII and the structurally characterized L and M subunits of the reaction center from purple non-sulfur bacteria. We have also examined the temperature dependence of the microwave power at half-saturation (P1/2) of signal IIslow from 4 to 200 K in dark-adapted PSII membranes. Above 70 K, the P1/2 increases as T2.5, which is consistent with a Raman relaxation mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Design principles and theory of paramagnetic fluorine-labelled lanthanide complexes as probes for (19)F magnetic resonance: a proof-of-concept study.

PubMed

Chalmers, Kirsten H; De Luca, Elena; Hogg, Naomi H M; Kenwright, Alan M; Kuprov, Ilya; Parker, David; Botta, Mauro; Wilson, J Ian; Blamire, Andrew M

2010-01-04

The synthesis and spectroscopic properties of a series of CF(3)-labelled lanthanide(III) complexes (Ln=Gd, Tb, Dy, Ho, Er, Tm) with amide-substituted ligands based on 1,4,7,10-tetraazacyclododecane are described. The theoretical contributions of the (19)F magnetic relaxation processes in these systems are critically assessed and selected volumetric plots are presented. These plots allow an accurate estimation of the increase in the rates of longitudinal and transverse relaxation as a function of the distance between the Ln(III) ion and the fluorine nucleus, the applied magnetic field, and the re-rotational correlation time of the complex, for a given Ln(III) ion. Selected complexes exhibit pH-dependent chemical shift behaviour, and a pK(a) of 7.0 was determined in one example based on the holmium complex of an ortho-cyano DO3A-monoamide ligand, which allowed the pH to be assessed by measuring the difference in chemical shift (varying by over 14 ppm) between two (19)F resonances. Relaxation analyses of variable-temperature and variable-field (19)F, (17)O and (1)H NMR spectroscopy experiments are reported, aided by identification of salient low-energy conformers by using density functional theory. The study of fluorine relaxation rates, over a field range of 4.7 to 16.5 T allowed precise computation of the distance between the Ln(III) ion and the CF(3) reporter group by using global fitting methods. The sensitivity benefits of using such paramagnetic fluorinated probes in (19)F NMR spectroscopic studies are quantified in preliminary spectroscopic and imaging experiments with respect to a diamagnetic yttrium(III) analogue.

Thermoelectric properties of (DyNiSn)1-x(DyNiSb)x composite

NASA Astrophysics Data System (ADS)

Synoradzki, Karol; Ciesielski, Kamil; Kępiński, Leszek; Kaczorowski, Dariusz

2018-05-01

High temperature thermoelectric properties of bulk and ball-milled cold-pressed (DyNiSn)1-x(DyNiSb)x composite materials have been studied. For bulk pure DyNiSn and DyNiSb samples the Seebeck coefficient reaches - 5.5 μV/K at 480 K and 120 μV/K at 540 K, respectively. Composite materials show metallic-like electrical resistivity and positive sign of Seebeck coefficient with values up to 50 times higher than in pure DyNiSn compound at 1000 K. Only for the sample with x = 0.47, the ball-milling drives to increase of Seebeck coefficient of about 37% at 650 K.

Influence of rare earth doping on thermoelectric properties of SrTiO3 ceramics

NASA Astrophysics Data System (ADS)

Liu, J.; Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

2013-12-01

Thermoelectric properties of SrTiO3 ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO3 ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO3 ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr0.8La0.18Yb0.02TiO3 ceramics were prepared, whose ZT value at 1 023 K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr0.8La0.2TiO3 (ZT = 0.26).

Operation TEAPOT. Technical Summary of Military Effects, Programs 1-9

DTIC Science & Technology

1981-05-01

54 2.26 Dust dynami c pressure (,I( ) deorived from Greg, and Snob a.ir dynamic preo mu e (qa~) at 2,500.-foot...ration. An instrument designated as Greg was expected to respond to the total dy- lalmic pi ussure of !he air and the (lust, while the Snob ...the 3-foot Snob and Grtg ga cs gave abnormally low values again Inconsistent A ith other i’,.,trumentatIon. Although an interiediate value v.as l,o:sen

The Effects of Dy Addition on Microstructure and Mechanical Properties of the As-Cast Mg-5Al-3Ca-2Nd Alloys.

PubMed

Son, Hyeon-Taek; Kim, Yong-Ho; Yoo, Hyo-Sang

2018-03-01

The microstructure of the as-cast Mg-5Al-3Ca-2Nd-xDy alloys consists of α-Mg matrix, (Mg, Al)2Ca eutectic phase, Al-Nd and Al-Dy intermetallic compounds. α-Mg matrix morphology was changed from dendritic to equiaxed with the increase Dy addition. And grain size was remarkably refined. As Dy content was increased, yield strength was improved due to the refined grains and the homogeneous distribution of Al-Dy phase.

Selective arc-discharge synthesis of Dy2S-clusterfullerenes and their isomer-dependent single molecule magnetism.

PubMed

Chen, Chia-Hsiang; Krylov, Denis S; Avdoshenko, Stanislav M; Liu, Fupin; Spree, Lukas; Yadav, Ravi; Alvertis, Antonis; Hozoi, Liviu; Nenkov, Konstantin; Kostanyan, Aram; Greber, Thomas; Wolter, Anja U B; Popov, Alexey A

2017-09-01

A method for the selective synthesis of sulfide clusterfullerenes Dy 2 S@C 2 n is developed. Addition of methane to the reactive atmosphere reduces the formation of empty fullerenes in the arc-discharge synthesis, whereas the use of Dy 2 S 3 as a source of metal and sulfur affords sulfide clusterfullerenes as the main fullerene products along with smaller amounts of carbide clusterfullerenes. Two isomers of Dy 2 S@C 82 with C s (6) and C 3v (8) cage symmetry, Dy 2 S@C 72 - C s (10528), and a carbide clusterfullerene Dy 2 C 2 @C 82 - C s (6) were isolated. The molecular structure of both Dy 2 S@C 82 isomers was elucidated by single-crystal X-ray diffraction. SQUID magnetometry demonstrates that all of these clusterfullerenes exhibit hysteresis of magnetization, with Dy 2 S@C 82 - C 3v (8) being the strongest single molecule magnet in the series. DC- and AC-susceptibility measurements were used to determine magnetization relaxation times in the temperature range from 1.6 K to 70 K. Unprecedented magnetization relaxation dynamics with three consequent Orbach processes and energy barriers of 10.5, 48, and 1232 K are determined for Dy 2 S@C 82 - C 3v (8). Dy 2 S@C 82 - C s (6) exhibits faster relaxation of magnetization with two barriers of 15.2 and 523 K. Ab initio calculations were used to interpret experimental data and compare the Dy-sulfide clusterfullerenes to other Dy-clusterfullerenes. The smallest and largest barriers are ascribed to the exchange/dipolar barrier and relaxation via crystal-field states, respectively, whereas an intermediate energy barrier of 48 K in Dy 2 S@C 82 - C 3v (8) is assigned to the local phonon mode, corresponding to the librational motion of the Dy 2 S cluster inside the carbon cage.

Doping Lanthanide into Perovskite Nanocrystals: Highly Improved and Expanded Optical Properties.

PubMed

Pan, Gencai; Bai, Xue; Yang, Dongwen; Chen, Xu; Jing, Pengtao; Qu, Songnan; Zhang, Lijun; Zhou, Donglei; Zhu, Jinyang; Xu, Wen; Dong, Biao; Song, Hongwei

2017-12-13

Cesium lead halide (CsPbX 3 ) perovskite nanocrystals (NCs) have demonstrated extremely excellent optical properties and great application potentials in various optoelectronic devices. However, because of the anion exchange, it is difficult to achieve white-light and multicolor emission for practical applications. Herein, we present the successful doping of various lanthanide ions (Ce 3+ , Sm 3+ , Eu 3+ , Tb 3+ , Dy 3+ , Er 3+ , and Yb 3+ ) into the lattices of CsPbCl 3 perovskite NCs through a modified hot-injection method. For the lanthanide ions doped perovskite NCs, high photoluminescence quantum yield (QY) and stable and widely tunable multicolor emissions spanning from visible to near-infrared (NIR) regions are successfully obtained. This work indicates that the doped perovskite NCs will inherit most of the unique optical properties of lanthanide ions and deliver them to the perovskite NC host, thus endowing the family of perovskite materials with excellent optical, electric, or magnetic properties.

Natural disease history of the dy2J mouse model of laminin α2 (merosin)-deficient congenital muscular dystrophy.

PubMed

Pasteuning-Vuhman, S; Putker, K; Tanganyika-de Winter, C L; Boertje-van der Meulen, J W; van Vliet, L; Overzier, M; Plomp, J J; Aartsma-Rus, A; van Putten, M

2018-01-01

Merosin deficient congenital muscular dystrophy 1A (MDC1A) is a very rare autosomal recessive disorder caused by mutations in the LAMA2 gene leading to severe and progressive muscle weakness and atrophy. Although over 350 causative mutations have been identified for MDC1A, no treatment is yet available. There are many therapeutic approaches in development, but the lack of natural history data of the mouse model and standardized outcome measures makes it difficult to transit these pre-clinical findings to clinical trials. Therefore, in the present study, we collected natural history data and assessed pre-clinical outcome measures for the dy2J/dy2J mouse model using standardized operating procedures available from the TREAT-NMD Alliance. Wild type and dy2J/dy2J mice were subjected to five different functional tests from the age of four to 32 weeks. Non-tested control groups were taken along to assess whether the functional test regime interfered with muscle pathology. Respiratory function, body weights and creatine kinase levels were recorded. Lastly, skeletal muscles were collected for further histopathological and gene expression analyses. Muscle function of dy2J/dy2J mice was severely impaired at four weeks of age and all mice lost the ability to use their hind limbs. Moreover, respiratory function was altered in dy2J/dy2J mice. Interestingly, the respiration rate was decreased and declined with age, whereas the respiration amplitude was increased in dy2J/dy2J mice when compared to wild type mice. Creatine kinase levels were comparable to wild type mice. Muscle histopathology and gene expression analysis revealed that there was a specific regional distribution pattern of muscle damage in dy2J/dy2J mice. Gastrocnemius appeared to be the most severely affected muscle with a high proportion of atrophic fibers, increased fibrosis and inflammation. By contrast, triceps was affected moderately and diaphragm only mildly. Our study presents a complete natural history dataset which can be used in setting up standardized studies in dy2J/dy2J mice.

Production of 4He and He4‾ in Pb-Pb collisions at √{sNN } = 2.76TeV at the LHC

NASA Astrophysics Data System (ADS)

Acharya, S.; Adamová, D.; Adolfsson, J.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Al-Turany, M.; Alam, S. N.; Albuquerque, D. S. D.; Aleksandrov, D.; Alessandro, B.; Alfaro Molina, R.; Ali, Y.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altenkamper, L.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andreou, D.; Andrews, H. A.; Andronic, A.; Anguelov, V.; Anson, C.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barioglio, L.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartsch, E.; Bastid, N.; Basu, S.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Bazo Alba, J. L.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Beltran, L. G. E.; Belyaev, V.; Bencedi, G.; Beole, S.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhattacharjee, B.; Bhom, J.; Bianchi, A.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Blair, J. T.; Blau, D.; Blume, C.; Boca, G.; Bock, F.; Bogdanov, A.; Boldizsár, L.; Bombara, M.; Bonomi, G.; Bonora, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Botta, E.; Bourjau, C.; Bratrud, L.; Braun-Munzinger, P.; Bregant, M.; Broker, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buhler, P.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Cabala, J.; Caffarri, D.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Capon, A. A.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Chandra, S.; Chang, B.; Chang, W.; Chapeland, S.; Chartier, M.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Chojnacki, M.; Choudhury, S.; Chowdhury, T.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Concas, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Costanza, S.; Crkovská, J.; Crochet, P.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; de Souza, R. D.; Degenhardt, H. F.; Deisting, A.; Deloff, A.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; di Ruzza, B.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Ding, Y.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Doremalen, L. V. R.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dudi, S.; Duggal, A. K.; Dukhishyam, M.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erhardt, F.; Espagnon, B.; Eulisse, G.; Eum, J.; Evans, D.; Evdokimov, S.; Fabbietti, L.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Gallio, M.; Galvan, C. D.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Garg, K.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Gay Ducati, M. B.; Germain, M.; Ghosh, J.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, A. S.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Greiner, L.; Grelli, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Gronefeld, J. M.; Grosa, F.; Grosse-Oetringhaus, J. F.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Guzman, I. B.; Haake, R.; Hadjidakis, C.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Haque, M. R.; Harris, J. W.; Harton, A.; Hassan, H.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Hellbär, E.; Helstrup, H.; Herghelegiu, A.; Hernandez, E. G.; Herrera Corral, G.; Herrmann, F.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hills, C.; Hippolyte, B.; Hohlweger, B.; Horak, D.; Hornung, S.; Hosokawa, R.; Hristov, P.; Hughes, C.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Iga Buitron, S. A.; Ilkaev, R.; Inaba, M.; Ippolitov, M.; Islam, M. S.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacak, B.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jaelani, S.; Jahnke, C.; Jakubowska, M. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jercic, M.; Jimenez Bustamante, R. T.; Jones, P. G.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karczmarczyk, P.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Ketzer, B.; Khabanova, Z.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Khatun, A.; Khuntia, A.; Kielbowicz, M. M.; Kileng, B.; Kim, B.; Kim, D.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, J.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Konyushikhin, M.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kreis, L.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kundu, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lai, Y. S.; Lakomov, I.; Langoy, R.; Lapidus, K.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lavicka, R.; Lea, R.; Leardini, L.; Lee, S.; Lehas, F.; Lehner, S.; Lehrbach, J.; Lemmon, R. C.; Leogrande, E.; León Monzón, I.; Lévai, P.; Li, X.; Lien, J.; Lietava, R.; Lim, B.; Lindal, S.; Lindenstruth, V.; Lindsay, S. W.; Lippmann, C.; Lisa, M. A.; Litichevskyi, V.; Llope, W. J.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Loncar, P.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Luhder, J. R.; Lunardon, M.; Luparello, G.; Lupi, M.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martinengo, P.; Martinez, J. A. L.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Masciocchi, S.; Masera, M.; Masoni, A.; Masson, E.; Mastroserio, A.; Mathis, A. M.; Matuoka, P. F. T.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzilli, M.; Mazzoni, M. A.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Mhlanga, S.; Miake, Y.; Mieskolainen, M. M.; Mihaylov, D. L.; Mikhaylov, K.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, A. P.; Mohanty, B.; Mohisin Khan, M.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mulligan, J. D.; Munhoz, M. G.; Münning, K.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Myers, C. J.; Myrcha, J. W.; Nag, D.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Narayan, A.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Negrao de Oliveira, R. A.; Nellen, L.; Nesbo, S. V.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, H.; Ohlson, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Oravec, M.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Pachmayer, Y.; Pacik, V.; Pagano, D.; Paić, G.; Palni, P.; Pan, J.; Pandey, A. K.; Panebianco, S.; Papikyan, V.; Pareek, P.; Park, J.; Parmar, S.; Passfeld, A.; Pathak, S. P.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Peng, X.; Pereira, L. G.; Pereira da Costa, H.; Peresunko, D.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Pezzi, R. P.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pliquett, F.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Poppenborg, H.; Porteboeuf-Houssais, S.; Pozdniakov, V.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Punin, V.; Putschke, J.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Rana, D. B.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Ratza, V.; Ravasenga, I.; Read, K. F.; Redlich, K.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reshetin, A.; Reygers, K.; Riabov, V.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rodríguez Cahuantzi, M.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Rokita, P. S.; Ronchetti, F.; Rosas, E. D.; Rosnet, P.; Rossi, A.; Rotondi, A.; Roukoutakis, F.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rueda, O. V.; Rui, R.; Rumyantsev, B.; Rustamov, A.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Saarinen, S.; Sadhu, S.; Sadovsky, S.; Šafařík, K.; Saha, S. K.; Sahlmuller, B.; Sahoo, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sandoval, A.; Sarkar, A.; Sarkar, D.; Sarkar, N.; Sarma, P.; Sas, M. H. P.; Scapparone, E.; Scarlassara, F.; Schaefer, B.; Scheid, H. S.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schmidt, M. O.; Schmidt, M.; Schmidt, N. V.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sett, P.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shahoyan, R.; Shaikh, W.; Shangaraev, A.; Sharma, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Sheikh, A. I.; Shigaki, K.; Shirinkin, S.; Shou, Q.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silaeva, S.; Silvermyr, D.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singhal, V.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Song, J.; Song, M.; Soramel, F.; Sorensen, S.; Sozzi, F.; Sputowska, I.; Stachel, J.; Stan, I.; Stankus, P.; Stenlund, E.; Stocco, D.; Storetvedt, M. M.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Sumowidagdo, S.; Suzuki, K.; Swain, S.; Szabo, A.; Szarka, I.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thakur, D.; Thakur, S.; Thomas, D.; Thoresen, F.; Tieulent, R.; Tikhonov, A.; Timmins, A. R.; Toia, A.; Toppi, M.; Torres, S. R.; Tripathy, S.; Trogolo, S.; Trombetta, G.; Tropp, L.; Trubnikov, V.; Trzaska, W. H.; Trzeciak, B. A.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Umaka, E. N.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vala, M.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vázquez Doce, O.; Vechernin, V.; Veen, A. M.; Velure, A.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Vértesi, R.; Vickovic, L.; Vigolo, S.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Virgili, T.; Vislavicius, V.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Voscek, D.; Vranic, D.; Vrláková, J.; Wagner, B.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wenzel, S. C.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Willems, G. A.; Williams, M. C. S.; Willsher, E.; Windelband, B.; Witt, W. E.; Xu, R.; Yalcin, S.; Yamakawa, K.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yun, E.; Yurchenko, V.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, Y.; Zichichi, A.; Zimmermann, M. B.; Zinovjev, G.; Zmeskal, J.; Zou, S.; Alice Collaboration

2018-03-01

Results on the production of 4He and He4‾ nuclei in Pb-Pb collisions at √{sNN } = 2.76TeV in the rapidity range | y | < 1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN / dy 4He = (0.8 ± 0.4 (stat) ± 0.3 (syst)) ×10-6 and dN / dyHe4‾ = (1.1 ± 0.4 (stat) ± 0.2 (syst)) ×10-6, respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (Tchem = 156MeV) as for light hadrons. The measured ratio of He4‾/4 He is 1.4 ± 0.8 (stat) ± 0.5 (syst).

Cracking on anisotropic neutron stars

NASA Astrophysics Data System (ADS)

Setiawan, A. M.; Sulaksono, A.

2017-07-01

We study the effect of cracking of a local anisotropic neutron star (NS) due to small density fluctuations. It is assumed that the neutron star core consists of leptons, nucleons and hyperons. The relativistic mean field model is used to describe the core of equation of state (EOS). For the crust, we use the EOS introduced by Miyatsu et al. [1]. Furthermore, two models are used to describe pressure anisotropic in neutron star matter. One is proposed by Doneva-Yazadjiev (DY) [2] and the other is proposed by Herrera-Barreto (HB) [3]. The anisotropic parameter of DY and HB models are adjusted in order the predicted maximum mass compatible to the mass of PSR J1614-2230 [4] and PSR J0348+0432 [5]. We have found that cracking can potentially present in the region close to the neutron star surface. The instability due cracking is quite sensitive to the NS mass and anisotropic parameter used.

Dirac strings and magnetic monopoles in the spin ice Dy2Ti2O7.

PubMed

Morris, D J P; Tennant, D A; Grigera, S A; Klemke, B; Castelnovo, C; Moessner, R; Czternasty, C; Meissner, M; Rule, K C; Hoffmann, J-U; Kiefer, K; Gerischer, S; Slobinsky, D; Perry, R S

2009-10-16

Sources of magnetic fields-magnetic monopoles-have so far proven elusive as elementary particles. Condensed-matter physicists have recently proposed several scenarios of emergent quasiparticles resembling monopoles. A particularly simple proposition pertains to spin ice on the highly frustrated pyrochlore lattice. The spin-ice state is argued to be well described by networks of aligned dipoles resembling solenoidal tubes-classical, and observable, versions of a Dirac string. Where these tubes end, the resulting defects look like magnetic monopoles. We demonstrated, by diffuse neutron scattering, the presence of such strings in the spin ice dysprosium titanate (Dy2Ti2O7). This is achieved by applying a symmetry-breaking magnetic field with which we can manipulate the density and orientation of the strings. In turn, heat capacity is described by a gas of magnetic monopoles interacting via a magnetic Coulomb interaction.

Microstructural Evolution of Dy2O3-TiO2 Powder Mixtures during Ball Milling and Post-Milled Annealing

PubMed Central

Huang, Jinhua; Ran, Guang; Lin, Jianxin; Shen, Qiang; Lei, Penghui; Wang, Xina; Li, Ning

2016-01-01

The microstructural evolution of Dy2O3-TiO2 powder mixtures during ball milling and post-milled annealing was investigated using XRD, SEM, TEM, and DSC. At high ball-milling rotation speeds, the mixtures were fined, homogenized, nanocrystallized, and later completely amorphized, and the transformation of Dy2O3 from the cubic to the monoclinic crystal structure was observed. The amorphous transformation resulted from monoclinic Dy2O3, not from cubic Dy2O3. However, at low ball-milling rotation speeds, the mixtures were only fined and homogenized. An intermediate phase with a similar crystal structure to that of cubic Dy2TiO5 was detected in the amorphous mixtures annealed from 800 to 1000 °C, which was a metastable phase that transformed to orthorhombic Dy2TiO5 when the annealing temperature was above 1050 °C. However, at the same annealing temperatures, pyrochlore Dy2Ti2O7 initially formed and subsequently reacted with the remaining Dy2O3 to form orthorhombic Dy2TiO5 in the homogenous mixtures. The evolutionary mechanism of powder mixtures during ball milling and subsequent annealing was analyzed. PMID:28772375

Independent Control of Grafting Density and Conformation of Single-Stranded DNA Brushes

DTIC Science & Technology

2007-01-02

Abstreiter G, Tornow M (2004) Langmuir 20:10086–10092. 20. Kimura-Suda H, Petrovykh DY, Tarlov MJ, Whitman LJ (2003) J Am Chem Soc 125:9014–9015. 21. Wolf...Tarlov MJ, Himpsel FJ, Whitman LJ (2006) J Am Chem Soc 128:2–3. 25. Rant U, Arinaga K, Fujiwara T, Fujita S, Tornow M, Yokoyama N, Abstreiter G (2003

Equation of state of zircon- and scheelite-type dysprosium orthovanadates: a combined experimental and theoretical study.

PubMed

Paszkowicz, Wojciech; Ermakova, Olga; López-Solano, Javier; Mujica, Andrés; Muñoz, Alfonso; Minikayev, Roman; Lathe, Christian; Gierlotka, Stanisław; Nikolaenko, Irina; Dabkowska, Hanna

2014-01-15

Dysprosium orthovanadate, DyVO4, belongs to a family of zircon-type orthovanadates showing a phase transition to scheelite-type structures at moderate pressures below 10 GPa. In the present study, the equations of state (EOSs) for both these phases were determined for the first time using high-pressure x-ray diffraction experiments and ab initio calculations based on the density functional theory. Structural parameters for scheelite-type DyVO4 were calculated from x-ray powder diffraction data as well. The high-pressure experiments were performed under pseudo-hydrostatic conditions at pressures up to 8.44 GPa and 5.5 GPa for the stable zircon-type and metastable (quenched) scheelite-type samples, respectively. Assuming as a compression model the Birch-Murnaghan EOS, we obtained the EOS parameters for both phases. The experimental bulk moduli (K0) for zircon-type and scheelite-type DyVO4 are 118(4) GPa and 153(6) GPa, respectively. Theoretical equations of state were determined by ab initio calculations using the PBE exchange-correlation energy functional of Perdew, Burke, and Ernzerhof. These calculations provide K0 values of 126.1 GPa and 142.9 GPa for zircon-type and scheelite-type DyVO4, respectively. The reliability of the present experimental and theoretical results is supported by (i) the consistency between the values yielded by the two methods (the discrepancy in K0 is as low as about 7% for each of the studied polymorphs) and (ii) their similarity to results obtained under similar compression conditions (hydrostatic or pseudo-hydrostatic) for other rare-earth orthovanadates, such as YVO4 and TbVO4.

Efficient 2.96 micron dysprosium-doped ZBLAN fibre laser pumped at 1.3 micron

NASA Astrophysics Data System (ADS)

Tsang, Yuen H.; El-Taher, Atalla E.; King, Terence A.; Chang, Kuang-Po; Jackson, Stuart D.

2006-04-01

Wavelengths around 1.15 μm, 1.3 μm and 1.7 μm can be used to pump Dy-doped ZBLAN fibre in order to generate ~3 μm with high efficiency. Previously the generation of 2.9 μm from the Dy-ZBLAN fibre was demonstrated by pumping with 1.1 μm Yb-silica fibre laser sources. The laser slope efficiency and lasing threshold demonstrated was about ~5% and ~1.78 W. In this investigation, the longer wavelength absorption band ( 6H 9/2 , 6F 11/2) centred at 1.3 μm of Dy 3+-doped ZBLAN is utilised and the lasing transition around ~3 μm takes places from 6H 13/2 --> 6H 15/2. With this pumping scheme the Stokes' efficiency is expected to be up to ~45%. A quasi-continuous wave Dy 3+-ZBLAN fibre laser pumped by a ~1.3 μm Nd:YAG laser and operating at 2.96 μm with a bandwidth (FWHM) of ~14 nm has been demonstrated. For a 60cm fibre length, a threshold of 0.5W and a slope efficiency of ~20% with respect to the absorbed pump power was observed. The overall pump absorption in the fibre was around 84%. The cavity reflectivities at 2.9 μm were 99% and 50%. The demonstrated slope efficiency was 45% of the Stokes' limit. The slope efficiency was around four times higher and the threshold around 3.6 times lower than the previous performance demonstrated by using the 1.1 μm Yb fibre laser pumping scheme. The higher performance achieved compared to the 1.1 μm pump scheme is due to the higher Stokes' limit, lower pump ESA losses and higher cavity reflectivity. About 590 cm -1 Raman Stokes shift has also detected by using 514.5 nm and 488 nm Ar ion laser as excitation pump sources.

Hymenobacter swuensis sp. nov., a gamma-radiation-resistant bacteria isolated from mountain soil.

PubMed

Lee, Jae-Jin; Srinivasan, Sathiyaraj; Lim, Sangyong; Joe, Minho; Lee, Sang Hee; Kwon, Shin Ae; Kwon, Yoon Jung; Lee, Jin; Choi, Jin Ju; Lee, Hye Min; Auh, Young Kyung; Kim, Myung Kyum

2014-03-01

Gram stain-negative and non-motile bacteria, designated as DY53(T) and DY43, were isolated from mountain soil in South Korea prior exposure with 5 kGy gamma radiation. Phylogenetic analysis based on 16S rRNA gene sequence revealed that the strains belonged to the family Cytophagaceae in the class Cytophagia. 16S rRNA gene sequence similarity of strains DY53(T) and DY43 was 100 %. The highest degrees of sequence similarities of strains DY53(T) and DY43 were found with Hymenobacter perfusus A1-12(T) (98.8 %), Hymenobacter rigui WPCB131(T) (98.5 %), H. yonginensis HMD1010(T) (97.9 %), H. xinjiangensis X2-1g(T) (96.6 %), and H. gelipurpurascens Txg1(T) (96.5 %). The DNA G+C content of the novel strains DY53(T) and DY43 were 59.5 mol%. Chemotaxonomic data revealed that strains possessed major fatty acids such as C₁₅:₀ iso, C₁₅:₀ anteiso, C₁₆:₁ ω5c, summed feature 3 (16:1 ω7c/ω6c), summed feature 4 (17:1 anteiso B/iso I) and C₁₇:₀ iso, and major polar lipid was phosphatidylethanolamine. The novel strains showed resistance to gamma radiation, with a D10 value (i.e., the dose required to reduce the bacterial population by tenfold) in excess of 5 kGy. Based on these data, strains DY53(T) and DY43 should be classified as representing a novel species, for which the name Hymenobacter swuensis sp. nov. is proposed, with the type strain DY53(T) (=KCTC 32018(T) = JCM 18582(T)) and DY43 (=KCTC 32010).

Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted 163Ho ions

NASA Astrophysics Data System (ADS)

Gastaldo, L.; Ranitzsch, P. C.-O.; von Seggern, F.; Porst, J.-P.; Schäfer, S.; Pies, C.; Kempf, S.; Wolf, T.; Fleischmann, A.; Enss, C.; Herlert, A.; Johnston, K.

2013-05-01

For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of 163Ho using MMCs having the radioactive 163Ho ions implanted in the absorber. The isotope 163Ho decays through electron capture to 163Dy and features the smallest known QEC value. This peculiarity makes 163Ho a very interesting candidate to investigate the value of the electron neutrino mass by the analysis of the energy spectrum. The implantation of 163Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. Moreover the performance of the detector prototype having the 163Ho ions implanted in the absorber is already close to the requirements needed for an experiment with sub-eV sensitivity to the electron neutrino mass. Based on these results, an optimized detector design for future 163Ho experiments is presented.

Pico-level DNA sensing by hetero-polymetalate, Na10{Dy2W10O30(µ-S)6}·80H2O, cluster

NASA Astrophysics Data System (ADS)

Dutta, Taposhree; Ganguly, Jhuma; Sarkar, Sabyasachi

2018-04-01

The polyoxometalate dysprosium cluster, (Dy-S-W POM) , Na10[Dy2W10O30(µ-S)6]·80H2O, shows remarkable dsDNA denaturation property. In the presence of 0.22 µmol of this Dy-S-W POM, the melting temperature (Tm) of calf-thymus (CT) dsDNA is decreased to 62.35 °C. Dy-S-W POM shows bleaching of methylene blue (MB). Addition of CT-DNA in the MB bleached solution of Dy-S-W POM apparently intercalates MB. Such trapped MB by CT-DNA responds to its re-oxidation by elemental sulfur formed in the bleaching process involving Dy-S-W POM. This reduction-oxidation property of MB with Dy-S-W POM led to the detection of pico (13.20 pmol) level of DNA even by naked eye, which will be helpful for rapid trace DNA detection in forensic science and DNA-related diagnostics, complimenting time-consuming sophisticated methodology.

The Effects of the Addition of Dy, Nb, and Ga on Microstructure and Magnetic Properties of Nd2Fe14B/α-Fe Nanocomposite Permanent Magnetic Alloys.

PubMed

Ren, Kezhi; Tan, Xiaohua; Li, Heyun; Xu, Hui; Han, Ke

2017-04-01

We study the effects of Dy, Nb, and Ga additions on the microstructure and magnetic properties of Nd2Fe14B/α-Fe nanocomposites. Dy, Nb, and Ga additions inhibit the growth of the soft magnetic α-Fe phase. Dy and Nb additions are able to refine the microstructure, whereas Ga addition plays only a minor role in prohibiting crystal growth. The magnetic properties are sensitive to Dy, Nb, and Ga additions. The Dy-containing alloy enhances the intrinsic coercivity of 872 kA/m because Dy partially replaces Nd, forming (Nd, Dy)2Fe14B. Nb addition refines the microstructure, and consequently increases the exchange coupling between magnetic grains. The Nd9.5Fe75.4Co5Zr3B6.5Ga0.6 alloy exhibits the highest remanence (0.92 T) due to Ga addition.

Generic NICA-Donnan model parameters for metal-ion binding by humic substances.

PubMed

Milne, Christopher J; Kinniburgh, David G; van Riemsdijk, Willem H; Tipping, Edward

2003-03-01

A total of 171 datasets of literature and experimental data for metal-ion binding by fulvic and humic acids have been digitized and re-analyzed using the NICA-Donnan model. Generic parameter values have been derived that can be used for modeling in the absence of specific metalion binding measurements. These values complement the previously derived generic descriptions of proton binding. For ions where the ranges of pH, concentration, and ionic strength conditions are well covered by the available data,the generic parameters successfully describe the metalion binding behavior across a very wide range of conditions and for different humic and fulvic acids. Where published data for other metal ions are too sparse to constrain the model well, generic parameters have been estimated by interpolating trends observable in the parameter values of the well-defined data. Recommended generic NICA-Donnan model parameters are provided for 23 metal ions (Al, Am, Ba, Ca, Cd, Cm, Co, CrIII, Cu, Dy, Eu, FeII, FeIII, Hg, Mg, Mn, Ni, Pb, Sr, Thv, UVIO2, VIIIO, and Zn) for both fulvic and humic acids. These parameters probably represent the best NICA-Donnan description of metal-ion binding that can be achieved using existing data.

Selective arc-discharge synthesis of Dy2S-clusterfullerenes and their isomer-dependent single molecule magnetism† †Electronic supplementary information (ESI) available. CCDC 1546957 and 1551313. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc02395b

PubMed Central

Chen, Chia-Hsiang; Krylov, Denis S.; Avdoshenko, Stanislav M.; Liu, Fupin; Spree, Lukas; Yadav, Ravi; Alvertis, Antonis; Hozoi, Liviu; Nenkov, Konstantin; Kostanyan, Aram; Greber, Thomas; Wolter, Anja U. B.

2017-01-01

A method for the selective synthesis of sulfide clusterfullerenes Dy2S@C2n is developed. Addition of methane to the reactive atmosphere reduces the formation of empty fullerenes in the arc-discharge synthesis, whereas the use of Dy2S3 as a source of metal and sulfur affords sulfide clusterfullerenes as the main fullerene products along with smaller amounts of carbide clusterfullerenes. Two isomers of Dy2S@C82 with Cs(6) and C3v(8) cage symmetry, Dy2S@C72-Cs(10528), and a carbide clusterfullerene Dy2C2@C82-Cs(6) were isolated. The molecular structure of both Dy2S@C82 isomers was elucidated by single-crystal X-ray diffraction. SQUID magnetometry demonstrates that all of these clusterfullerenes exhibit hysteresis of magnetization, with Dy2S@C82-C3v(8) being the strongest single molecule magnet in the series. DC- and AC-susceptibility measurements were used to determine magnetization relaxation times in the temperature range from 1.6 K to 70 K. Unprecedented magnetization relaxation dynamics with three consequent Orbach processes and energy barriers of 10.5, 48, and 1232 K are determined for Dy2S@C82-C3v(8). Dy2S@C82-Cs(6) exhibits faster relaxation of magnetization with two barriers of 15.2 and 523 K. Ab initio calculations were used to interpret experimental data and compare the Dy-sulfide clusterfullerenes to other Dy-clusterfullerenes. The smallest and largest barriers are ascribed to the exchange/dipolar barrier and relaxation via crystal-field states, respectively, whereas an intermediate energy barrier of 48 K in Dy2S@C82-C3v(8) is assigned to the local phonon mode, corresponding to the librational motion of the Dy2S cluster inside the carbon cage. PMID:29263779

Hydrothermal synthesis and tunable luminescence of CaSiO{sub 3}:RE{sup 3+}(RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Linlin; Yang, Xingxing; Fu, Zuoling, E-mail: zlfu@jlu.edu.cn

2015-05-15

Highlights: • Near-spherical CaSiO{sub 3} nanocrystals were synthesized via a hydrothermal method. • The effect of calcination temperature on crystalline phase formation was discussed. • Optical properties of trivalent ions doped CaSiO{sub 3} nanocrystals were investigated. • Tunable luminescence of CaSiO{sub 3}:Tb{sup 3+}, Eu{sup 3+} can be achieved by a simple method. - Abstract: CaSiO{sub 3}:RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanocrystals were prepared by facile hydrothermal method with further calcinations. The crystal structure and the effects of annealing temperature on phase transition have been characterized by X-ray diffraction (XRD). The photoluminescence (PL)more » and PL excitation (PLE) spectra were used to characterize the optical properties of all samples. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity were also investigated in details, respectively. Moreover, the luminescence colors of the Tb{sup 3+} and Eu{sup 3+} co-doped CaSiO{sub 3} samples can be tuned by simply adjusting the relative doping concentrations of the rare earth ions under a single wavelength excitation, which might find potential applications in the fields of light display systems and optoelectronic devices.« less

Building 1D lanthanide chains and non-symmetrical [Ln2] "triple-decker" clusters using salen-type ligands: magnetic cooling and relaxation phenomena.

PubMed

Canaj, Angelos B; Siczek, Milosz; Otręba, Marta; Lis, Tadeusz; Lorusso, Giulia; Evangelisti, Marco; Milios, Constantinos J

2016-11-22

A solvothermal reaction between Ln(NO 3 ) 3 ·6H 2 O (Ln: Gd, Tb and Dy), 2-hydroxy-1-naphthaldehyde, 2-OH-naphth, and ethylenediamine, en, in MeOH in the presence of a base, NEt 3 , led to the formation of the 1D coordination polymers [Ln(L)(MeO)(MeOH) 0.5 ] n ·MeOH (Ln = Gd (1·MeOH), Tb(2), Dy (3·MeOH); H 2 L = 1,1'-((1E,1'E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol), the Schiff-base ligand derived from the condensation of 2-OH-naphth and en), while a similar reaction in an excess of NaN 3 yielded 1D coordination polymers [Ln(L)(N 3 ) 0.75 (MeO) 0.25 (MeOH)] n (Ln = Gd (4), Tb (5), Dy (6)). Finally, upon replacing ethylenediamine with o-phenylenediamine, o-phen, we managed to isolate the discrete dimers [Dy 2 (L') 3 (MeOH)]·2MeOH (7·2MeOH) and [Gd 2 (L') 3 (MeOH)]·2MeOH (8·2MeOH) (H 2 L' = 1,1'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis (naphthalen-2-ol), the Schiff-base ligand from the condensation of 2-OH-naphth and o-phen). Polymers 1-3 describe one-dimensional chains, containing alternating seven- and eight-coordinate Ln III metal centers, polymers 4-6 contain eight-coordinate lanthanide ions, while in both 7 and 8 the two Ln III centers are eight- and seven-coordinate, adopting square antiprismatic and "piano-stool" geometry, respectively. The magnetocaloric properties of the three Gd III analogues were determined from magnetic measurements, yielding the magnetic entropy change -ΔS m = 21.8, 23.0 and 16.0 J kg -1 K -1 at T = 3.0 K on demagnetization of 7 T to 0, for 1, 4 and 8, respectively. The study of the magnetic properties also revealed that all three Dy III analogues (3, 6 and 7) display out-of-phase signals, therefore suggesting slow magnetic relaxation, while such behaviour was not established in the Tb III analogues.

High electrical resistivity Nd-Fe-B die-upset magnet doped with eutectic DyF3-LiF salt mixture

NASA Astrophysics Data System (ADS)

Kim, K. M.; Kim, J. Y.; Kwon, H. W.; Kim, D. H.; Lee, J. G.; Yu, J. H.

2017-05-01

Nd-Fe-B-type die-upset magnet with high electrical resistivity was prepared by doping of eutectic DyF3-LiF salt mixture. Mixture of melt-spun Nd-Fe-B flakes (MQU-F: Nd13.6Fe73.6Co6.6Ga0.6B5.6) and eutectic binary (DyF3-LiF) salt (25 mol% DyF3 - 75 mol% LiF) was hot-pressed and then die-upset. By adding the eutectic salt mixture (> 4 wt%), electrical resistivity of the die-upset magnet was enhanced to over 400 μ Ω .cm compared to 190 μ Ω .cm of the un-doped magnet. Remarkable enhancement of the electrical resistivity was attributed to homogeneous and continuous coverage of the interface between flakes by the easily melted eutectic salt dielectric mixture. It was revealed that active substitution of the Nd atoms in neighboring flakes by the Dy atoms from the added (DyF3-LiF) salt mixture had occurred during such a quick thermal processing of hot-pressing and die-upsetting. This Dy substitution led to coercivity enhancement in the die-upset magnet doped with the eutectic (DyF3-LiF) salt mixture. Coercivity and remanence of the die-upset magnet doped with (DyF3-LiF) salt mixture was as good as those of the DyF3-doped magnet.

Photoluminescence properties of Li2SrGeO4:RE3+ (RE = Ce/Tb/Dy) phosphors and enhanced luminescence through energy transfer between Ce3+ and Tb3+/Dy3+

NASA Astrophysics Data System (ADS)

Huang, Shuai; Li, Guogang

2014-07-01

Li2SrGeO4:RE3+ (RE = Tb/Dy/Ce) phosphors were prepared by the conventional solid-state reaction. X-ray diffraction (XRD), photoluminescence (PL) spectra, and lifetimes were utilized to characterize samples. Under the excitation of ultraviolet (231 nm for Tb3+ and 351 nm for Dy3+), the Li2SrGeO4:Tb3+ and Li2SrGeO4:Dy3+ phosphors show their respective characteristic emissions of Tb3+ (5D3,4 → 7FJ‧, J‧ = 3, 4, 5, 6) and Dy3+ (4F9/2 → 6H15/2 and 4F9/2 → 6H13/2), respectively. Ce3+ activated Li2SrGeO4 phosphors exhibit broad band blue emission due to the 5d-4f transition of Ce3+. Co-doping Ce3+ into the LSG: Ce3+/Dy3+ samples enhances the luminescence intensity of Tb3+ and Dy3+ significantly under the excitation wavelength at 340 nm through energy transfer from Ce3+ to Tb3+/Dy3+. In addition, the energy transfer mechanism between Ce3+ and Tb3+/Dy3+ has been demonstrated to be a resonant type via a dipole-quadrupole interaction.

Optical absorption, luminescence, and energy transfer processes studies for Dy3+/Tb3+-codoped borate glasses for solid-state lighting applications

NASA Astrophysics Data System (ADS)

Lakshminarayana, G.; Kaky, Kawa M.; Baki, S. O.; Lira, A.; Caldiño, U.; Kityk, I. V.; Mahdi, M. A.

2017-10-01

By using melt quenching technique, good optical quality singly doped Dy3+ or Tb3+ and Dy3+/Tb3+-codoped borate glasses were synthesized and studied by optical absorption, excitation, emission and decay lifetimes curve analysis. Following the absorption spectrum, the evaluated Judd-Ofelt (J-O) intensity parameters (Ωλ (λ = 2, 4 and 6)) were used to calculate the transition probability (AR), the branching ratio (βR), and the radiative lifetime (τR) for different luminescent transitions such as 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 and 4F9/2 → 6H9/2,6F11/2 for the 0.5 mol % singly Dy3+-doped glass. The βR calculated (65%) indicates that for lasing applications, 4F9/2 → 6H13/2 emission transition is highly suitable. For all the Dy3+/Tb3+-codoped glasses, Tb3+: 5D3→7F6 emission decay lifetime curves are found to be non-exponential in nature for different concentrations of Dy3+ codoping. Using the Inokuti-Hirayama model, these nonexponential decay curves were analyzed to identify the nature of the energy transfer (ET) processes and here the electric dipole-dipole interaction is dominant for the ET. Based on the excitation and emission spectra and decay lifetimes curve analysis, the cross relaxation and ET processes between Dy3+ and Tb3+ were confirmed. For the 0.5 mol % Tb3+ and 2.0 mol % Dy3+-codoped glass, the evaluated Tb3+→Dy3+ ET efficiency (η) is found to be 45% under 369 nm excitation. Further, for Tb3+/Dy3+ -codoped glasses, an enhancement of Tb3+ green emission is observed up to 1.5 mol % Dy3+ codoping, and this is due to the non-radiative resonant ET from Dy3+ to Tb3+ upon 395 nm excitation. For singly 0.5 mol % Dy3+ or 0.5 mol % Tb3+-doped glass, the calculated color coordinates (x,y) and correlated color temperatures (CCT) represent the neutral white or warm white light regions, whereas Dy3+/Tb3+-codoped glasses (x,y) and CCT values fall in the yellowish green region with respect to the different Dy3+ concentrations under 350 and 395 nm excitations. Following the analyzed optical data, the singly Dy3+ or Tb3+-doped and Dy3+/Tb3+-codoped glasses could be suggested as promising materials for their applications in solid state light emitting diodes and luminescent display devices.

X-ray absorption spectroscopy and X-ray photoelectron spectroscopy studies of CaSO 4:Dy thermoluminescent phosphors

NASA Astrophysics Data System (ADS)

Bakshi, A. K.; Jha, S. N.; Olivi, L.; Phase, D. M.; Kher, R. K.; Bhattacharyya, D.

2007-11-01

Extended X-ray absorption fine structure (EXAFS) measurements have been carried out on CaSO4:Dy phosphor samples at the Dy L3 edge with synchrotron radiation. Measurements were carried out on a set of samples which were subjected to post-preparation annealing at different temperatures and for different cycles. The EXAFS data have been analysed to find the Dy-S and Dy-O bond lengths in the neighbourhood of the Dy atoms in a CaSO4 matrix. The observations from EXAFS measurements were verified with XANES and XPS techniques. On the basis of these measurements, efforts were made to explain the loss of thermoluminescence sensitivity of CaSO4:Dy phosphors after repeated cycles of annealing at 400 °C in air for 1 h.

Effect of dysprosium and lutetium metal buffer layers on the resistive switching characteristics of Cu-Sn alloy-based conductive-bridge random access memory.

PubMed

Vishwanath, Sujaya Kumar; Woo, Hyunsuk; Jeon, Sanghun

2018-06-18

Conductive-bridge random access memory (CBRAM) has become one of the most suitable candidates for non-volatile memory in next-generation information and communication technology. The resistive switching mechanism of CBRAM depends on the formation/annihilation of the conductive filament (CF) between the active metal electrode and the inert electrode. However, excessive ion injection from the active electrode into the solid electrolyte is reduces the uniformity and reliability of the resistive switching devices. To solve this problem, we investigated the resistive switching characteristics of a modified active electrode with different compositions of Cu_x-Sn_{_1-x}(0.13 < X < 0.55). The resistive switching characteristics were further improved by inserting a dysprosium (Dy) or lutetium (Lu) buffer layer at the interface of Cu_x-Sn_1-x/Al₂O₃. Electrical analysis of the optimal Cu_0.27-Sn_0.73/Lu-based CBRAM exhibited stable resistive switching behavior with low operation voltage (SET: 0.7 V and RESET: -0.3 V), a high on/off resistive ratio (10⁶), cyclic endurance (>10⁴), and long-term retention (85℃/10 years). To achieve these performance parameters, CFs were locally formed inside the electrolyte using a modified CuSn active electrode, and the amount of Cu-ion injection was reduced by inserting the Dy or Lu buffer layer between the CuSn active electrode and the electrolyte. In particular, conductive-atomic force microscopy results at the Dy/ or Lu/Al₂O₃ interface directly showed and defined the diameter of the CF. © 2018 IOP Publishing Ltd.

Characterization of Dye-decolorizing Peroxidase (DyP) from Thermomonospora curvata Reveals Unique Catalytic Properties of A-type DyPs*

PubMed Central

Chen, Chao; Shrestha, Ruben; Jia, Kaimin; Gao, Philip F.; Geisbrecht, Brian V.; Bossmann, Stefan H.; Shi, Jishu; Li, Ping

2015-01-01

Dye-decolorizing peroxidases (DyPs) comprise a new family of heme peroxidases, which has received much attention due to their potential applications in lignin degradation. A new DyP from Thermomonospora curvata (TcDyP) was identified and characterized. Unlike other A-type enzymes, TcDyP is highly active toward a wide range of substrates including model lignin compounds, in which the catalytic efficiency with ABTS (kcatapp/Kmapp = (1.7 × 107) m−1 s−1) is close to that of fungal DyPs. Stopped-flow spectroscopy was employed to elucidate the transient intermediates as well as the catalytic cycle involving wild-type (wt) and mutant TcDyPs. Although residues Asp220 and Arg327 are found necessary for compound I formation, His312 is proposed to play roles in compound II reduction. Transient kinetics of hydroquinone (HQ) oxidation by wt-TcDyP showed that conversion of the compound II to resting state is a rate-limiting step, which will explain the contradictory observation made with the aspartate mutants of A-type DyPs. Moreover, replacement of His312 and Arg327 has significant effects on the oligomerization and redox potential (E°′) of the enzyme. Both mutants were found to promote the formation of dimeric state and to shift E°′ to a more negative potential. Not only do these results reveal the unique catalytic property of the A-type DyPs, but they will also facilitate the development of these enzymes as lignin degraders. PMID:26205819

Synchrotron X-ray studies of epitaxial ferroelectric thin films and nanostructures

NASA Astrophysics Data System (ADS)

Klug, Jeffrey A.

The study of ferroelectric thin films is a field of considerable scientific and technological interest. In this dissertation synchrotron x-ray techniques were applied to examine the effects of lateral confinement and epitaxial strain in ferroelectric thin films and nanostructures. Three materials systems were investigated: laterally confined epitaxial BiFeO3 nanostructures on SrTiO3 (001), ultra-thin commensurate SrTiO 3 films on Si (001), and coherently strained films of BaTiO3 on DyScO3 (110). Epitaxial films of BiFeO3 were deposited by radio frequency magnetron sputtering on SrRuO3 coated SrTiO 3 (001) substrates. Laterally confined nanostructures were fabricated using focused ion-beam processing and subsequently characterized with focused beam x-ray nanodiffraction measurements with unprecedented spatial resolution. Results from a series of rectangular nanostructures with lateral dimensions between 500 nm and 1 mum and a comparably-sized region of the unpatterned BiFeO3 film revealed qualitatively similar distributions of local strain and lattice rotation with a 2-3 times larger magnitude of variation observed in those of the nanostructures compared to the unpatterned film. This indicates that lateral confinement leads to enhanced variation in the local strain and lattice rotation fields in epitaxial BiFeO3 nanostructures. A commensurate 2 nm thick film of SrTiO3 on Si was characterized by the x-ray standing wave (XSW) technique to determine the Sr and Ti cation positions in the strained unit cell in order to verify strain-induced ferroelectricity in SrTiO3/Si. A Si (004) XSW measurement at 10°C indicated that the average Ti displacement from the midpoint between Sr planes was consistent in magnitude to that predicted by a density functional theory (DFT) calculated ferroelectric structure. The Ti displacement determined from a 35°C measurement better matched a DFT-predicted nonpolar structure. The thin film extension of the XSW technique was employed to measure the polar displacement of the Ba cations in a 50 nm thick coherently strained BaTiO3 film on DyScO3 (110). An analysis assuming a bulk-like ratio between the Ti and Ba displacements found that the polar shift of Ba cations was larger than in bulk BaTiO3, which was consistent with strain-induced enhancement of ferroelectric polarization in BaTiO3/DyScO3 (110).

Strain tuning and strong enhancement of ionic conductivity in SrZrO 3-RE 2O 3 (RE = Sm, Eu, Gd, Dy, and Er) nanocomposite films

DOE PAGES

Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

2015-06-05

Fast ion transport channels at interfaces in thin films have attracted great attention due to a range of potential applications for energy materials and devices, for, solid oxide fuel cells, sensors, and memories. Here, it is shown that in vertical nanocomposite heteroepitaxial films of SrZrO 3–RE 2O 3 (RE = Sm, Eu, Gd, Dy, and Er) the ionic conductivity of the composite can be tuned and strongly enhanced using embedded, stiff, and vertical nanopillars of RE 2O 3. With increasing lattice constant of RE 2O 3 from Er 2O 3 to Sm 2O 3, it is found that the tensilemore » strain in the SrZrO 3 increases proportionately, and the ionic conductivity of the composite increases accordingly, by an order of magnitude. Lastly, the results here conclusively show, for the first time, that strain in films can be effectively used to tune the ionic conductivity of the materials.« less

Properties of alginate fiber spun-dyed with fluorescent pigment dispersion.

PubMed

Wang, Ping; Tawiah, Benjamin; Tian, Anli; Wang, Chunxia; Zhang, Liping; Fu, Shaohai

2015-03-15

Spun-dyed alginate fiber was prepared by the spun-dyeing method with the mixture of fluorescent pigment dispersion and sodium alginate fiber spinning solution, and its properties were characterized by SEM, TGA, DSC, and XRD. The results indicate that fluorescent pigment dispersion prepared with esterified poly (styrene-alt maleic acid) had excellent compatibility with sodium alginate fiber spinning solution, and small amount of fluorescent pigment could reduce the viscosity of spun-dyed spinning solutions. SEM photo of spun-dyed alginate fiber indicated that fewer pigment particles deposited on its surface. TGA, DSC, and XRD results suggested that thermal properties and crystal phase of spun-dyed alginate fibers had slight changes compared to the original alginate fibers. The fluorescence intensity of spun-dyed alginate fiber reached its maximum when the content of fluorescent pigment was 4%. The spun-dyed alginate fiber showed excellent rubbing and washing fastness. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thermoelectric properties of Ca(1-x-y)Dy(x)CeyMnO3 for power generation.

PubMed

Park, K; Lee, G W; Jung, J; Kim, S-J; Lim, Y-S; Choi, S-M; Seo, W-S

2011-08-01

The sintered Ca(1-x-y)Dy(x)CeyMnO3 bodies were a single phase with a perovskite structure without any impurity phases. The calculated crystallite sizes of the Ca(1-x-y)Dy(x)CeyMnO3 were in the range of 43.3 to 63.3 nm. The composition significantly affected their microstructural and thermoelectric characteristics. The doped Dy led to both an increase in the electrical conductivity as well as the absolute value of the Seebeck coefficient, resulting in an enhanced power factor. The highest power factor (5.1 x 10(-4) Wm(-1) K(-2)) was obtained for Ca(0.8)Dy(0.2)MnO3 at 800 degrees C. In this study, we systematically discussed the thermoelectric properties of the Ca(1-x-y)Dy(x)CeyMnO3, with respect to the substitution of Dy and/or Ce for Ca.

Feasibility study of electrophoresis deposition of DyF3 on Nd-Fe-B particles for coercivity enhancement

NASA Astrophysics Data System (ADS)

Kim, K. M.; Kang, M. S.; Kwon, H. W.; Lee, J. G.; Yu, J. H.

2018-05-01

Feasibility of the electrophoresis deposition (EPD) technique for homogeneous and adhesive deposition of DyF3 particles on the Nd-Fe-B-type particles was studied, and coercivity enhancement in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD was investigated. HDDR-treated Nd12.5Fe80.6B6.4Ga0.3Nb0.2 particles were deposited with DyF3 particles by EPD. More homogeneous and adhesive deposition of DyF3 particles on the surface of Nd-Fe-B particles was made by the EPD with respect to conventional dip-coating, and this led to more active and homogeneous diffusion of Dy. More profound coercivity enhancement was achieved in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD compared to dip-coated particles.

Single-molecule magnet behavior in an octanuclear dysprosium(iii) aggregate inherited from helical triangular Dy3 SMM-building blocks.

PubMed

Zhang, Li; Zhang, Peng; Zhao, Lang; Wu, Jianfeng; Guo, Mei; Tang, Jinkui

2016-06-28

An unprecedented octanuclear dysprosium(iii) cluster with the formula [Dy8L6(μ3-OH)4(μ2-CH3O)2(CH3OH)6(H2O)2]·6H2O·10CH3OH·2CH3CN () based on a nonlinearly tritopic aroylhydrazone ligand H3L has been isolated, realizing the successful linking of pairwise interesting triangular Dy3 SMMs. It is noteworthy that two enantiomers (Λ and Δ configurations) individually behaving as a coordination-induced chirality presented in the Dy3 helicate are connected in the meso Dy8 cluster. Remarkably, alternating-current magnetic susceptibility measurements revealed that the Dy8 cluster shows typical SMM behavior inherited from its Dy3 helical precursor. It is one of the rare polynuclear Lnn SMMs (n > 7) under zero dc field.

Fluctuation Induced Almost Invariant Sets

DTIC Science & Technology

2006-12-28

Planck) for the probability density function [15], discrete dynamical systems benefit from using the Frobenius - Perron operator (FP) formalism [12] to...from epidemiology. Conclusions are summarized in Section 4. II. GENERAL THEORY A. Stochastic Frobenius - Perron operator We define the Frobenius - Perron ...function ν(x). The stochastic Frobenius - 3 Perron (SFP) operator is defined to be PF [ρ(x)] = ∫ M ν(x− F (y))ρ(y)dy. (4) For our applications, we will

ARPES study of the evolution of band structure and charge density wave properties in RTe3 ( R=Y , La, Ce, Sm, Gd, Tb, and Dy)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hussain, Zahid; Brouet, Veronique; Yang, Wanli

2008-01-16

We present a detailed angle-resolved photoemission spectroscopy (ARPES) investigation of the RTe3 family, which sets this system as an ideal"textbook" example for the formation of a nesting driven charge density wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDWinstabilities, from the opening of large gaps on the best nested parts of Fermi surface (up to 0.4 eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k space. An additional advantage of RTe3more » is that theband structure can be very accurately described by a simple two dimensional tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure by comparing our ARPES measurements with the linear muffin-tinorbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k space, the evolution of the CDW wave vector with R, and the shape of the residual metallic pockets. Finally, we give an estimation of the CDWinteraction parameters and find that the change in the electronic density of states n (EF), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.« less

Coercivity enhancement of Dy-coated Nd-Fe-B flakes by crystallization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukunaga, H.; Sugimoto, Y.; Nakano, M.

2011-04-01

The coercivity of isotropic Dy-coated Nd-Fe-B flakes was enhanced by crystallization and simultaneous diffusion of Dy from their surfaces. Amorphous Dy-coated Nd-Fe-B flakes were crystallized by heating them to 923 K 2over a 2 min period followed by rapid cooling. During crystallization, the Dy on the surface diffused into the flakes. This low-temperature rapid annealing produced flakes with fine grains and the Dy diffusion enhanced their coercivity. The coercivity after crystallization increased with increasing Dy layer thickness, although the remanence decreased when the layer thickness exceeded 3 {mu}m. Thick coatings of over 6 {mu}m resulted in the formation of DyFe{submore » 2}, which degraded the magnetic properties of the crystallized flakes. Flakes with a 3-{mu}m-thick coating exhibited excellent magnetic properties after annealing: They had a coercivity of 1880 kA/m and a remanence of 78 emu/g. This coercivity is approximately 500 kA/m higher than that of uncoated flakes, whereas the remanence is comparable to that of uncoated flakes.« less

Optimization of rare-earth-doped fluorides for infrared lasers

NASA Astrophysics Data System (ADS)

Peterson, Rita Dedomenico

2000-11-01

The rare-earth-doped fluoride crystals Tm,Dy:BaY2F8 (Tm,Dy:BYF), Yb,Pr:NaYF4 (Yb,Pr:NYF), and Nd:NYF show considerable promise as infrared laser materials, operating at 3 μm, 1.3 μm, and 1.06 μm respectively. Lasing has been reported previously on all three ionic transitions, but not in these crystals. Optimization of these materials for laser applications requires a more complete spectroscopic characterization than is currently available, particularly with regard to the key parameters of fluorescence lifetime and stimulated emission cross section. To further the optimization process, polarized absorption and emission have been measured for Tm,Dy:BYF, Yb,Pr:NYF, and Nd:NYF, and relevant fluorescence lifetimes have been measured or estimated. For Tm,Dy:BYF and Yb,Pr:NYF which rely upon sensitization, energy transfer parameters were calculated. Results were used in a mathematical model to determine the conditions in which lasing may be obtained. The long upper laser level lifetime in Tm,Dy:BYF translates into low threshold pump intensity, but the ability to reach threshold depends strongly on active ion concentration. The short lifetime in Yb,Pr:NYF leads to much higher threshold pump intensities, but lasing is still attainable if resonator loss is minimized. In Nd:NYF lasing was demonstrated, with a maximum of 60 mW output from an absorbed pump power of 345 mW, and a slope efficiency of 21%. Thresholds were high owing to resonator losses near 9%. Two chief issues involving the optimization of these laser materials were identified and explored. First, identification of the orientation for which emission cross section is highest is complicated in Tm,Dy:BYF by the presence of strong magnetic dipole radiation on the 3 μm transition. This effect makes it necessary to account for the polarization of both the electric and magnetic fields of the emitted radiation when determining an optimal crystal orientation, an accounting further complicated by the low symmetry of the monoclinic BYF host crystal. Second, the effect of host crystal on fluorescence lifetime was considered by comparing lifetime values for the same ionic manifolds in BYF, NYF, and other host crystals. NYF has especially low phonon energies, which leads to longer lifetimes on the longer wavelength transitions which are susceptible to multiphonon relaxation. This advantage is especially needed for lasing at 1.3 μm in Pr where the upper level lifetime is very short. On the shorter wavelength transitions in Tm and Nd, however, the role of phonons is negligible and lifetimes are somewhat shorter than in other fluoride hosts.

Microanalytical characterization of multi-rare earth nanocrystalline magnets by TEM and APT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Y. Q.; Tang, W.; Miller, Michael K

2006-01-01

The partitioning behavior of various rare-earth (RE) elements during solidification and their segregation behavior at the grain boundaries were investigated in nanocrystalline (Y{sub 0.5}Dy{sub 0.5}{sub 2.2}Fe{sub 14}B and (Nd{sub 0.5}Y{sub 0.25}Dy{sub 0.25}){sub 1.8}Zr{sub 0.4}Co{sub 1.5}Fe{sub 12.5}B alloys by transmission electron microscopy and atom probe tomography. The best hard magnetic properties obtained are H{sub cj} = 22 kOe, B{sub r}=5.10 kG, and (BH){sub max} = 5.97 MG Oe for the Y-Dy-based alloy and H{sub cj}=10.6 kOe, B{sub r}=6.64 kG, and (BH){sub max}=9.56 MG Oe for the Y-Nd-Dy based alloy. The grain size of the Y-Dy based alloy was {approx} 50 nm.more » The Y-Nd-Dy based alloy had an overall finer, bimodal grain size. An intergranular (Y{sub 0.36}Dy{sub 0.64}){sub 6}Fe{sub 23} phase was detected in the Y-Dy based alloy. A uniform distribution of RE elements was found within the 2-14-1 grains in both alloys. The Y:(Dy+Nd) ratio in the Y-Nd-Dy alloy was lower than its nominal composition, indicating that the Y is segregating to grain boundaries or forming a second phase.« less

Electronic structure of the (Nd{sub 1−x}Dy{sub x}){sub 2}Fe{sub 14}B (0 ≤ x ≤ 1) system studied by X-ray photoelectron spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jing; Liang, Le; Yang, Bin

2015-09-15

Systematic characterization of electronic structures in the (Nd{sub 1−x}Dy{sub x}){sub 2}Fe{sub 14}B system, especially the 4f behavior, provides an insight to the physical nature of the evolution of magnetic properties. A series of X-ray photoelectron spectroscopy (XPS) core-level and valence-band spectra were used to study the electronic structures. It was found that substitution of Dy for Nd in Nd{sub 2}Fe{sub 14}B results in a nonlinear variation in the evolution of electronic structures. Only the finite coupling between the Nd 4f states and the Fe 3d states is found at both the Nd-rich regime and the Dy-rich regime. When the Dymore » concentration and the Nd concentration approach to be equal, a strong coupling between the Nd 4f states and the Fe 3d states is found, which results in a bonding state between them. Additionally, the 4f components in the (Nd{sub 1−x}Dy{sub x}){sub 2}Fe{sub 14}B system are ascribed to three parts: 1) the individual contribution of the Dy 4f states, which emerges just after the Dy-substitution; 2) the contribution of the coupling between the Nd 4f states and the Dy 4f states, which arises only when 0.4 ≤ x ≤ 0.6; 3) the associated contributions of the Nd 4f states and the Dy 4f states, where the contribution of the Nd 4f states and that of the Dy 4f states are prominent in the Nd-rich regime and Dy-rich regime, respectively.« less

Description of the first fungal dye-decolorizing peroxidase oxidizing manganese(II)

DOE PAGES

Fernandez-Fueyo, Elena; Linde, Dolores; Almendral, David; ...

2015-05-13

Two phylogenetically divergent genes of the new family of dye-decolorizing peroxidases (DyPs) were found during comparison of the four DyP genes identified in the Pleurotus ostreatus genome with over 200 DyP genes from other basidiomycete genomes. The heterologously expressed enzymes ( Pleos-DyP1 and Pleos-DyP4, following the genome nomenclature) efficiently oxidize anthraquinoid dyes (such as Reactive Blue 19), which are characteristic DyP substrates, as well as low redox-potential dyes (such as 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and substituted phenols. However, only Pleos-DyP4 oxidizes the high redox-potential dye Reactive Black 5, at the same time that it displays high thermal and pH stability. Unexpectedly, bothmore » enzymes also oxidize Mn 2+ to Mn 3+, albeit with very different catalytic efficiencies. Pleos-DyP4 presents a Mn 2+ turnover (56 s –1) nearly in the same order of the two other Mn 2+-oxidizing peroxidase families identified in the P. ostreatus genome: manganese peroxidases (100 s–1 average turnover) and versatile peroxidases (145 s –1 average turnover), whose genes were also heterologously expressed. Oxidation of Mn 2+ has been reported for an Amycolatopsis DyP (24 s –1) and claimed for other bacterial DyPs, albeit with lower activities, but this is the first time that Mn 2+ oxidation is reported for a fungal DyP. Interestingly, Pleos-DyP4 (together with ligninolytic peroxidases) is detected in the secretome of P. ostreatus grown on different lignocellulosic substrates. In conclusion, it is suggested that generation of Mn 3+ oxidizers plays a role in the P. ostreatus white-rot lifestyle since three different families of Mn 2+-oxidizing peroxidase genes are present in its genome being expressed during lignocellulose degradation.« less

Description of the first fungal dye-decolorizing peroxidase oxidizing manganese(II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandez-Fueyo, Elena; Linde, Dolores; Almendral, David

Two phylogenetically divergent genes of the new family of dye-decolorizing peroxidases (DyPs) were found during comparison of the four DyP genes identified in the Pleurotus ostreatus genome with over 200 DyP genes from other basidiomycete genomes. The heterologously expressed enzymes ( Pleos-DyP1 and Pleos-DyP4, following the genome nomenclature) efficiently oxidize anthraquinoid dyes (such as Reactive Blue 19), which are characteristic DyP substrates, as well as low redox-potential dyes (such as 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and substituted phenols. However, only Pleos-DyP4 oxidizes the high redox-potential dye Reactive Black 5, at the same time that it displays high thermal and pH stability. Unexpectedly, bothmore » enzymes also oxidize Mn 2+ to Mn 3+, albeit with very different catalytic efficiencies. Pleos-DyP4 presents a Mn 2+ turnover (56 s –1) nearly in the same order of the two other Mn 2+-oxidizing peroxidase families identified in the P. ostreatus genome: manganese peroxidases (100 s–1 average turnover) and versatile peroxidases (145 s –1 average turnover), whose genes were also heterologously expressed. Oxidation of Mn 2+ has been reported for an Amycolatopsis DyP (24 s –1) and claimed for other bacterial DyPs, albeit with lower activities, but this is the first time that Mn 2+ oxidation is reported for a fungal DyP. Interestingly, Pleos-DyP4 (together with ligninolytic peroxidases) is detected in the secretome of P. ostreatus grown on different lignocellulosic substrates. In conclusion, it is suggested that generation of Mn 3+ oxidizers plays a role in the P. ostreatus white-rot lifestyle since three different families of Mn 2+-oxidizing peroxidase genes are present in its genome being expressed during lignocellulose degradation.« less

Superconducting and magnetic properties of RBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaheen, S.A.; Jisrawi, N.; Lee, Y.H.

Superconducting properties of RBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ compounds (R = Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Yb) have been studied by dc electrical resistivity and ac magnetic susceptibility techniques. Except for R = La, which is superconducting below 50 K, RBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ compounds exhibit sharp resistive and inductive transitions in the 90-K range. The nearly constant value of T/sub c/ for magnetic R ions indicates a very weak interaction between R ions, as anticipated from the known crystal structure of these materials. The effects of annealing in oxygen and argon, andmore » air quenching, on the superconducting properties are also discussed.« less

Superposition-model analysis of rare-earth doped BaY2F8

NASA Astrophysics Data System (ADS)

Magnani, N.; Amoretti, G.; Baraldi, A.; Capelletti, R.

The energy level schemes of four rare-earth dopants (Ce3+ , Nd3+ , Dy3+ , and Er3+) in BaY2 F-8 , as determined by optical absorption spectra, were fitted with a single-ion Hamiltonian and analysed within Newman's Superposition Model for the crystal field. A unified picture for the four dopants was obtained, by assuming a distortion of the F- ligand cage around the RE site; within the framework of the Superposition Model, this distortion is found to have a marked anisotropic behaviour for heavy rare earths, while it turns into an isotropic expansion of the nearest-neighbours polyhedron for light rare earths. It is also inferred that the substituting ion may occupy an off-center position with respect to the original Y3+ site in the crystal.

A Mixed-Ligand Approach for a Gigantic and Hollow Heterometallic Cage {Ni64 RE96 } for Gas Separation and Magnetic Cooling Applications.

PubMed

Chen, Wei-Peng; Liao, Pei-Qin; Yu, Youzhu; Zheng, Zhiping; Chen, Xiao-Ming; Zheng, Yan-Zhen

2016-08-01

Nanosized aggregations of metal ions shielded by organic ligands possessing both exquisite structural aesthetics and intriguing properties are fundamentally interesting. Three isostructural gigantic transition-metal-rare-earth heterometallic coordination cages are reported, abbreviated as {Ni64 RE96 } (RE=Gd, Dy, and Y) and obtained by a mixed-ligand approach, each possessing a cuboidal framework made of 160 metal ions and a nanosized spherical cavity in the center. Along with the structural novelty, these hollow cages show highly selective adsorptions for CO2 over CH4 or N2 at ambient temperatures. Moreover, the gadolinium analogue exhibits large magnetocaloric effect at ultralow temperatures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CaSO4:DY,Mn: A new and highly sensitive thermoluminescence phosphor for versatile dosimetry

NASA Astrophysics Data System (ADS)

Bahl, Shaila; Lochab, S. P.; Kumar, Pratik

2016-02-01

With the advent of newer techniques for dose reduction coupled with the development of more sensitive detectors, the radiation doses in radiological medical investigation are decreasing. Nevertheless, keeping the tenet in mind that all radiation doses could entail risk, there is a need to develop more sensitive dosimeters capable of measuring low doses. This paper gives the account of the development of a new and sensitive phosphor CaSO4:Dy,Mn and its characterization. The standard production procedure based on the recrystallization method was used to prepare CaSO4:Dy,Mn. The Thermoluminescence (TL) studies were carried out by exposing it with gamma radiation (Cs-137) from 10 μGy to 100 Gy. The theoretical studies to determine the number of peaks and kinetic parameters related to the TL glow peaks in CaSO4:Dy,Mn was performed using the Computerized Glow Curve Deconvolution (CGCD) method. Experiments were performed to determine optimum concentration of the dopants Dysprosium (Dy) and Mangnese (Mn) in the host CaSO4 so that maximum sensitivity of the phosphor may be achieved. The optimum dopant concentration turned out to be 0.1 mol%. As there were two dopants Dy and Mn their relative ratio were varied in steps of 0.025 keeping the concentration of total dopant (Dy and Mn) 0.1 mol% always. The maximum TL intensity was seen in the CaSO4:Dy(0.025),Mn(0.075) combination. The TL sensitivity of this phosphor was found to be about 2 and 1.8 times higher than that of popular phosphor CaSO4:Dy and LiF:Mg,Cu,P (TLD-700H) respectively. This new phosphor CaSO4:Dy,Mn showed fading of 11% which is similar to that of the standard phosphor CaSO4:Dy. The paper concludes that the new, highly sensitive TL phosphor CaSO4:Dy,Mn has shown higher sensitivity and hence the potential to replace commonly used CaSO4:Dy.

A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions

NASA Astrophysics Data System (ADS)

Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

2018-03-01

In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu3 +) ion. Upon addition of Eu3 + ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y3 +, Ce3 +, Pr3 +, Nd3 +, Sm3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Yb3 + and Lu3 +, into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu3 + ions were investigated, including solution pH value, Eu3 + ion concentration and interfering substances. The detection mechanism of Eu3 + ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of EuIII-dtpa-bis(cytosine) at 375 nm in the concentration range of 0.50 × 10- 5 mol • L- 1-5.00 × 10- 5 mol • L- 1 of Eu3 + ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65 × 10- 7 mol • L- 1 and the corresponding correlation coefficient (R2) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu3 + ion.

Coercivity enhancement mechanism in Dy-substituted Nd-Fe-B nanoparticles synthesized by sol-gel base method followed by a reduction-diffusion process

NASA Astrophysics Data System (ADS)

Rahimi, Hamed; Ghasemi, Ali; Mozaffarinia, Reza; Tavoosi, Majid

2017-05-01

In current work, Nd15-xDyxFe77.5B7.5 (at%) nanoparticles with different Dy-content (x=0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0) were synthesized by sol-gel method followed by a reduction-diffusion process. The effects of Dy on the magnetic properties and the relations between the microstructure and the coercivity of Dy-substituted Nd-Fe-B nanoparticles have been studied. The coercivity of Nd-Fe-B nanoparticles with the addition of Dy first increase, reaches a maximum, and then starts to decrease. The coercivity of Dy-substituted Nd-Fe-B nanoparticle synthesized by sol-gel method increased from 938.9 to 1663.9 kA/m while the remanence decreased slightly from 1.16 to 1.06 T. The results show that with an increase in Dy content the variation of maximum energy product ((BH)max), lowest-order uniaxial magnetocrystalline anisotropy constant (Ku1), and Curie temperature (Tc) had a trend as same as the coercivity. The Henkel plot showed that the existence of exchange coupling interaction between grains, and the exchange coupling interactions increased with increasing x from 0.0 to 2.0 and then decrease with further increasing x≥2.5. The optimum magnetic properties of Nd-Fe-B nanoparticles with (BH)max =40.38 MGOe, Hc=1663.9 kA/m, Br=1.08 T were obtained by substituted 2.0 at% Dy. The effects of increasing temperature on magnetic properties of Dy-substituted Nd-Fe-B nanoparticle magnets with 2.0 at% Dy was investigated. The reduced spin-reorientation temperature was obtained for Dy-substituted Nd-Fe-B nanoparticles with 2.0 at% Dy. Below 100 K a spin-reorientation transition was takes place. The temperature coefficient of coercivity (β) was -0.36, -0.46, -0.41, -0.34, -0.29, -0.24, -0.25%/°C at different temperature 50, 100, 150, 200, 250, 300, 350 °C, respectively. Mössbauer spectroscopy was applied to study the composition and properties of Dy-substituted Nd-Fe-B magnet. Microstructure analysis showed a homogeneous distribution of Dy in produced samples. The possible reason for observed magnetic behavior is improving the intrinsic material parameter and optimizing the microstructure by a uniform enhancement of magnetocrystalline anisotropy by formation the nanocrystalline compound (Nd,Dy)2Fe14B.

System DyFeO: thermodynamic properties of ternary oxides using Calvet calorimetry and solid-state electrochemical cell

NASA Astrophysics Data System (ADS)

Parida, S. C.; Jacob, K. T.; Venugopal, V.

2002-10-01

The enthalpy increments and the standard molar Gibbs energies of formation of DyFeO 3(s) and Dy 3Fe 5O 12(s) have been measured using a Calvet micro-calorimeter and a solid oxide galvanic cell, respectively. A co-operative phase transition, related to anti-ferromagnetic to paramagnetic transformation, is apparent from the heat capacity data for DyFeO 3 at ˜648 K. A similar type of phase transition has been observed for Dy 3Fe 5O 12 at ˜560 K which is related to ferrimagnetic to paramagnetic transformation. Enthalpy increment data for DyFeO 3(s) and Dy 3Fe 5O 12(s), except in the vicinity of the second-order transition, can be represented by the following polynomial expressions: {H 0m(T)-H 0m(298.15 K)} ( J mol-1) (±1.1%)=-52754+142.9×(T ( K))+2.48×10 -3×(T ( K)) 2+2.951×10 6×(T ( K)) -1;(298.15⩽ T ( K)⩽1000) for DyFeO 3(s), and {H 0m(T)-H 0m(298.15 K)} ( J mol-1) (±1.2%)=-191048+545.0×(T ( K))+2.0×10 -5×(T ( K)) 2+8.513×10 6×(T ( K)) -1;(298.15⩽T ( K)⩽1000) for Dy 3Fe 5O 12(s). The reversible emfs of the solid-state electrochemical cells: (-)Pt/{DyFeO 3(s) + Dy 2O 3(s) + Fe(s)}//YDT/CSZ//{Fe(s) + Fe 0.95O(s)}/Pt(+) and (-)Pt/{Fe(s) + Fe 0.95O(s)}//CSZ//{DyFeO 3(s) + Dy 3Fe 5O 12(s) + Fe 3O 4(s)}/Pt(+), were measured in the temperature range from 1021 to 1250 K and 1035 to 1250 K, respectively. The standard Gibbs energies of formation of solid DyFeO 3 and Dy 3Fe 5O 12 calculated by the least squares regression analysis of the data obtained in the present study, and data for Fe 0.95O and Dy 2O 3 from the literature, are given by: Δ fG 0m( DyFeO3, s) ( kJ mol-1) (±3.2)=-1339.9+0.2473×(T ( K));(1021⩽T ( K)⩽1548) and Δ fG 0m( Dy3Fe5O12, s) ( kJ mol-1) (±3.5)=-4850.4+0.9846×(T ( K));(1035⩽T ( K)⩽1250). The uncertainty estimates for Δ fG 0m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams for the system DyFeO were developed at 1250 K.

Dy–Mn–Si as a representative of family of ‘Dy–Transition Metal–Si’ systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru; Knotko, A.V.; Yapaskurt, V.O.

2013-10-15

X-ray and microprobe analyses were employed for the investigation of Dy–Mn–Si system at 870/1070/1170 K. The Dy–Mn–Si system, contains the known DyMn{sub 2}Si{sub 2}, DyMnSi and Dy{sub 2}Mn{sub 3}Si{sub 5} compounds and DyMn{sub 4}Si{sub 2}, Dy{sub 2}MnSi{sub 2} and Dy{sub 3}Mn{sub 2}Si{sub 3} were new compounds identified first time and their structure are of the type TmCu{sub 4}Sb{sub 2}, Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The quasi-binary solid solutions were detected at 870/1070/1170 K: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-typemore » Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the Dy–Mn–Si system do not show any visible solubility. New phases R{sub 2}MnSi{sub 2} and R{sub 3}Mn{sub 2}Si{sub 3} (R=Gd, Tb, Ho–Tm) were found out and their structure of the type Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The specific features of ‘Dy–Transition Metal–Si’ systems were discussed. - Graphical abstract: The isothermal section of Dy–Mn–Si contains the known DyMn{sub 2}Si{sub 2}, DyMnSi, Dy{sub 2}Mn{sub 3}Si{sub 5} and new TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2}, Sc{sub 2}CoSi{sub 2}-type Dy{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type Dy{sub 3}Mn{sub 2}Si{sub 3} ternary compounds. The ternary solid solution based on the binary compounds of the Dy–Mn and Dy–Si systems: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-type Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the Dy–Mn–Si system do not show any visible solubility. New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} phases were discovered for R=Gd, Tb, Ho–Tm. Display Omitted - Highlights: • The Dy–Mn–Si section contains three known and three new ternary compounds (phases). • New phase the TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2} compound. • New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} were detected for R=Gd–Tm. • Dy–Mn–Si supplements the ‘Dy–3d metal–Si’ series and leads to the ‘RT{sub m}X{sub n}’ row's rule.« less

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology.

PubMed

Kirsch, A J; Chang, D T; Kayton, M L; Libutti, S K; Connor, J P; Hensle, T W

1996-01-01

Tissue welding using laser-activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery. Eleven types of sutures were exposed to diode laser energy (power density = 15.9 W/cm2) for 10, 30, and 60 seconds. Each suture was compared with and without the addition of dye-enhanced albumin-based solder. After exposure, each suture material was strained (2"/min) until ultimate breakage on a tensometer and compared to untreated sutures using ANOVA. The strength of undyed sutures were not significantly affected; however, violet and green-dyed sutures were in general weakened by laser exposure in the presence of dye-enhanced glue. Laser activation of the smallest caliber, dyed sutures (7-0) in the presence of glue caused the most significant loss of tensile strength of all sutures tested. These results indicate that the thermal effects of laser welding using our technique decrease the tensile strength of dyed sutures. A thermally resistant suture material (undyed or clear) may prevent disruption of wounds closed by laser welding techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chasteler, R.M.; Nitschke, J.M.; Firestone, R.B.

Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between {sup 170}Er ions and {sup nat}W targets. On-line mass separation was used together with {beta}- and {gamma}-ray spectroscopy in these studies. At mass {ital A}=169, the heaviest known dysprosium isotope, 39(8) s,{sup 169}Dy, was identified. It was observed to {beta}{sup {minus}} decay to the ground state of {sup 169}Ho or through a level at 1578 keV. In the {ital A}=171 mass chain, a partial decay scheme for 55(3)-s {sup 171}Ho was determined.

Site-specific magnetic anisotropies in R2Fe14B systems

NASA Astrophysics Data System (ADS)

Yoshioka, T.; Tsuchiura, H.

2018-04-01

The local magnetic anisotropy of R ions in R2Fe14B (R = Dy, Ho) systems is studied based on a microscopic effective spin model constructed from the information obtained by using first-principles calculations. By taking into account up to 6-th order crystal electric field parameters, the model satisfactory describes the observed magnetization curves and the temperature dependence of anisotropy constants. We found that at low temperatures, the noncollinear structure appears in the Ho2Fe14B system reflecting the local magnetic anisotropy.

Atomic-Resolution X-ray Energy-Dispersive Spectroscopy Chemical Mapping of Substitutional Dy Atoms in a High-Coercivity Neodymium Magnet

NASA Astrophysics Data System (ADS)

Itakura, Masaru; Watanabe, Natsuki; Nishida, Minoru; Daio, Takeshi; Matsumura, Syo

2013-05-01

We have investigated local element distributions in a Dy-doped Nd2Fe14B hot-deformed magnet by atomic-column resolution chemical mapping using an X-ray energy-dispersive spectrometer (XEDS) attached to an aberration-corrected scanning transmission electron microscope (Cs-corrected STEM). The positions of the Nd and Dy atomic columns were visualized in the XEDS maps. The substitution of Dy was limited to a surface layer 2-3 unit cells thick in the Nd2Fe14B grains, and the Dy atoms preferentially occupied the 4f-Nd sites of Nd2Fe14B. These results provide further insights into the principal mechanism governing the coercivity enhancement due to Dy doping.

Section 9.1 new dosimeters. New dosimetry systems

NASA Astrophysics Data System (ADS)

McLaughlin, William L.

During the past two years there have been significant advances in several forms of radiation measurement systems for radiation processing, covering dose ranges of 1-10 6 Gy. Calorimeters as reference standards for both ionizing photon and electron fields have become well-established. In addition to the older ceric-cerous dosimetry solution analyzed potentiometrically, new liquid-phase dosimeters include those analyzed by spectrophotometry, e.g., improved forms of acidic aqueous solutions of K-Ag dichromate and organic radiochromic dye solutions. It has recently been demonstrated that by using certain refined sugars, e.g., D-(-) ribose, optical rotation response in aqueous solutions can be enhanced for dosimetry at doses > 10 4 Gy. There has been expanded development, use, and formulation (rods, tablets, and thin films) of the amino acid, alanine, as a solid-phase dosimeter analyzed by either ESR spectrometry or by glutamine or alanine spectrophotometry of complexes with ferric ion in the presence of a sulfonphthalein dye (xylenol orange). New commercial types of radiochromic plastic dosimeters, e.g., GafChromic TM, Riso B3 TM, GAMMACHROME YR TM, Radix TM, and Gammex TM, have been introduced and applied in practice. Improvements and broader use of optical waveguide dosimeters, e.g., Opti-Chromic TM, have also been reported, especially in food irradiation applications. Several novel dyed plastic dosimeters are available in large quantities and they lose color due to irradiation. An example is a dyed cellulosic thin film (ATC type DY-42 TM) which can be measured spectrophotometrically or densitometrically up to doses as high as 10 6 Gy.

Pentanuclear heterometallic {Mn(III)(2)Ln(3)} (Ln = Gd, Dy, Tb, Ho) assemblies in an open-book type structural topology: appearance of slow relaxation of magnetization in the Dy(III) and Ho(III) analogues.

PubMed

Bag, Prasenjit; Chakraborty, Amit; Rogez, Guillaume; Chandrasekhar, Vadapalli

2014-07-07

The reaction of Ln(III) nitrate and Mn(ClO4)2·6H2O salts in the presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the isolation of four isostructural pentanuclear hetereometallic complexes [Mn(III)2Gd3(LH)4(NO3)(HOCH3)]ClO4·NO3 (1), [Mn(III)2Dy3(LH)4(NO3)(HOCH3)]ClO4·NO3 (2), [Mn(III)2Tb3(LH)4(NO3)(HOCH3)]ClO4·NO3 (3), and [Mn(III)2Ho3(LH)4(NO3)(HOCH3)]ClO4·NO3 (4) with an open-book type structural topology. 1-4 are dicationic and crystallize in the achiral space group, P21/n. A total of four triply deprotonated ligands, [LH](3-), are involved in holding the pentameric metal framework, {Mn(III)2Ln3}. In these complexes both the lanthanide and the manganese(III) ions are doubly bridged, involving phenolate or ethoxide oxygen atoms. The magnetochemical analysis reveals the presence of global antiferromagnetic interactions among the spin centers at low temperatures in all the four compounds. AC susceptibility measurements show the presence of temperature dependent out-of-phase ac signal for compounds 2 and 4 indicating an SMM behavior.

A Multifunctional Tb-MOF for Highly Discriminative Sensing of Eu3+ /Dy3+ and as a Catalyst Support of Ag Nanoparticles.

PubMed

Xu, Guo-Wang; Wu, Ya-Pan; Dong, Wen-Wen; Zhao, Jun; Wu, Xue-Qian; Li, Dong-Sheng; Zhang, Qichun

2017-06-01

Exploring novel multifunctional rare earth materials is very important because these materials have fundamental interests, such as new structural facts and connecting modes, as well as potential technological applications, including optics, magnetic properties, sorption, and catalytic behaviors. Especially, employing these nanomaterials for sensing or catalytic reactions is still very challenging. Herein, a new superstable, anionic terbium-metal-organic-framework, [H 2 N(CH 3 ) 2 ][Tb(cppa) 2 (H 2 O) 2 ], (China Three Gorges University (CTGU-1), H 2 cppa = 5-(4-carboxyphenyl)picolinic acid), is successfully prepared, which can be used as a turn-on, highly-sensitive fluorescent sensor to detect Eu 3+ and Dy 3+ , with a detection limitation of 5 × 10 -8 and 1 × 10 -4 m in dimethylformamide, respectively. This result represents the first example of lanthanide-metal-organic-frameworks (Ln-MOF) that can be employed as a discriminative fluorescent probe to recognize Eu 3+ and Dy 3+ . In addition, through ion exchanging at room temperature, Ag(I) can be readily reduced in situ and embedded in the anionic framework, which leads to the formation of nanometal-particle@Ln-MOF composite with uniform size and distribution. The as-prepared Ag@CTGU-1 shows remarkable catalytic performance to reduce 4-nitrophenol, with a reduction rate constant κ as large as 2.57 × 10 -2 s -1 ; almost the highest value among all reported noble-metal-nanoparticle@MOF composites. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coercivity enhancement in hot deformed Nd2Fe14B-type magnets by doping low-melting RCu alloys (R = Nd, Dy, Nd + Dy)

NASA Astrophysics Data System (ADS)

Lee, Y. I.; Huang, G. Y.; Shih, C. W.; Chang, W. C.; Chang, H. W.; You, J. S.

2017-10-01

Magnetic properties of the anisotropic NdFeB magnets prepared by hot pressing followed by die-upsetting NdFeB MQU-F powders doped with low-melting RCu alloy powders were explored, where RCu stands for Nd70Cu30, Dy70Cu30 and (Nd0.5Dy0.5)70Cu30, respectively. In addition, the post-annealing at 600 °C was employed to modify the microstructures and the magnetic properties of the hot deformed magnets. It is found that doping RCu alloy powders is effective in enhancing the coercivity of the hot deformed NdFeB magnets from 15.1 kOe to 16.3-19.5 kOe. For Nd70Cu30-doped magnets, the increment of coercivity is only 1.2 kOe. Meanwhile, Dy70Cu30-doped and (Nd0.5Dy0.5)70Cu30-doped magnets show an almost identical enhancement of coercivity of about 4.4 kOe. Importantly, the latter magnet shows a beneficial effect of reducing the usage of Dy from 1.6 wt% to 0.8 wt%. TEM analysis shows that nonmagnetic Nd, Dy and Cu appear at grain boundary and isolate the magnetic grains, leading to an enhancement of coercivity. Doping lower melting point Dy-lean (Nd0.5Dy0.5)70Cu30 powders into commercial MQU-F powders for making high coercivity hot deformed NdFeB magnets might be a potential and economic way for mass production.

Development of YAG:Dy Thermographic Phosphor Coatings for Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Eldridge, J. I.; Jenkins, T. P.; Allison, S. W.; Wolfe, D. E.; Jordan, E. H.

2012-01-01

The selection and development of thermographic phosphor coatings were pursued to meet the objective of demonstrating luminescence-decay-based temperature measurements up to 1300C on the surface of a vane in an operating demonstrator turbine engine. To meet this objective, YAG:Dy was selected based on the desirable luminescence performance observed for YAG:Dy powder: (1) excellent temperature sensitivity and intensity at operating turbine engine temperatures, (2) an emission peak at the relatively short wavelength of 456 nm, where the interference from background blackbody radiation is fairly low, and (3) its nearly single exponential decay which makes for a simple, reliable temperature calibration. However, implementation of YAG:Dy for surface temperature measurements required application of YAG:Dy as a coating onto the surface of a superalloy component with a preexisting yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC). An inherent dilemma in producing a YAG:Dy coating is that coating processing is constrained to be performed at temperatures below (less than 1200C) what is considered safe for the superalloy component, much lower than temperatures used to produce the high quality crystalline powder. Therefore, YAG:Dy coatings tend to exhibit lower luminescence performance compared to well prepared YAG:Dy powder, and the luminescence performance of the coating will depend on the method of coating deposition. In this presentation, the luminescence performance of YAG:Dy coatings prepared by the different methods of (1) application of a binder-based YAG:Dy-containing paint, (2) solution precursor plasma spray (SPPS), and (3) electron-beam physical vapor deposition (EB-PVD) and the effect of post-deposition heat treatments will be discussed.

A comparative study of magnetization dynamics in dinuclear dysprosium complexes featuring bridging chloride or trifluoromethanesulfonate ligands.

PubMed

Burns, Corey P; Wilkins, Branford O; Dickie, Courtney M; Latendresse, Trevor P; Vernier, Larry; Vignesh, Kuduva R; Bhuvanesh, Nattamai S; Nippe, Michael

2017-07-25

We utilized a rigid ligand platform PyCp 2 2- (PyCp 2 2- = [2,6-(CH 2 C 5 H 3 ) 2 C 5 H 3 N] 2- ) to isolate dinuclear Dy 3+ complexes [(PyCp 2 )Dy-(μ-O 2 SOCF 3 )] 2 (1) and [(PyCp 2 )Dy-(μ-Cl)] 2 (3) as well as the mononuclear complex (PyCp 2 )Dy(OSO 2 CF 3 )(thf) (2). Compounds 1 and 2 are the first examples of organometallic Dy 3+ complexes featuring triflate binding. The isolation of compounds 1 and 3 allows us to comparatively evaluate the effects of the bridging anions on the magnetization dynamics of the dinuclear systems. Our investigations show that although the exchange coupling interactions differ for 1 and 3, the dynamic magnetic properties are dominated by relaxation via the first excited state Kramers doublet of the individual Dy sites. Compounds 1 and 3 exhibit barriers to magnetization reversal (U eff = 49 cm -1 ) that can be favorably compared to those of the previously reported examples of [Cp 2 Dy(μ-Cl)] 2 (U eff = 26 cm -1 ) and [Cp 2 Dy(thf)(μ-Cl)] 2 (U eff = 34 cm -1 ).

Magnetic properties of Dy nano-islands on graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Nathaniel A.; Zhang, Qiang; Hupalo, Myron

Here, we have determined the magnetic properties of epitaxially grown Dy islands on graphene/SiC(0001) that are passivated by a gold film (deposited in the ultra-high vacuum growth chamber) for ex-situ X-ray magnetic circular dichroism (XMCD). Our sum-rule analysis of the Dy M 4,5 XMCD spectra at low temperatures ( T = 15 K) as a function of magnetic field assuming Dy 3+ (spin configuration 6 H 15/2) indicate that the projection of the magnetic moment along an applied magnetic field of 5 T is 3.5(3) μ B. Temperature dependence of the magnetic moment (extracted from the M 5 XMCD spectra)more » shows an onset of a change in magnetic moment at about 175 K in proximity of the transition from paramagnetic to helical magnetic structure at T H = 179 K in bulk Dy. No feature at the vicinity of the ferromagnetic transition of hcp bulk Dy at T c = 88 K is observed. However, below ~130 K, the inverse magnetic moment (extracted from the XMCD) is linear in temperature as commonly expected from a paramagnetic system suggesting different behavior of Dy nano-island than bulk Dy.« less

Magnetic properties of Dy nano-islands on graphene

DOE PAGES

Anderson, Nathaniel A.; Zhang, Qiang; Hupalo, Myron; ...

2017-04-07

Here, we have determined the magnetic properties of epitaxially grown Dy islands on graphene/SiC(0001) that are passivated by a gold film (deposited in the ultra-high vacuum growth chamber) for ex-situ X-ray magnetic circular dichroism (XMCD). Our sum-rule analysis of the Dy M 4,5 XMCD spectra at low temperatures ( T = 15 K) as a function of magnetic field assuming Dy 3+ (spin configuration 6 H 15/2) indicate that the projection of the magnetic moment along an applied magnetic field of 5 T is 3.5(3) μ B. Temperature dependence of the magnetic moment (extracted from the M 5 XMCD spectra)more » shows an onset of a change in magnetic moment at about 175 K in proximity of the transition from paramagnetic to helical magnetic structure at T H = 179 K in bulk Dy. No feature at the vicinity of the ferromagnetic transition of hcp bulk Dy at T c = 88 K is observed. However, below ~130 K, the inverse magnetic moment (extracted from the XMCD) is linear in temperature as commonly expected from a paramagnetic system suggesting different behavior of Dy nano-island than bulk Dy.« less

Study of cobalt effect on structural and optical properties of Dy doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Pandey, Praveen C.

2018-05-01

The present study has been carried out to investigate the effect of Co doping on structural and optical properties of Dy doped ZnO nanoparticles. We have prepared pure Zinc oxide, Dy (1%) doped ZnO and Dy (1%) doped ZnO co-doped with Co(2%) with the help of simple sol-gel combustion method. The structural analysis carried out using X-ray diffraction spectra (XRD) indicates substitution of Dy and Co at Zn site of ZnO crystal structure and hexagonal crystal structure without any secondary phase formation in all the samples. The surface morphology was analyzed by transmission electron microscopy (TEM). Absorption study indicates that Dy doping causes a small shift in band edge, while Co co-doping results significant change is absorption edge as well as introduce defect level absorption in the visible region. The band gap of samples decreases due to Dy and Co doping, which can be attributed to defect level formation below the conduction band in the system.

Effects of low central fuelling on density and ion temperature profiles in reversed shear plasmas on JT-60U

NASA Astrophysics Data System (ADS)

Takenaga, H.; Ide, S.; Sakamoto, Y.; Fujita, T.; JT-60 Team

2008-07-01

Effects of low central fuelling on density and ion temperature profiles have been investigated using negative ion based neutral beam injection and electron cyclotron heating (ECH) in reversed shear plasmas on JT-60U. Strong internal transport barrier (ITB) was maintained in density and ion temperature profiles, when central fuelling was decreased by switching positive ion based neutral beam injection to ECH after the strong ITB formation. Similar density and ion temperature ITBs were formed for the low and high central fuelling cases during the plasma current ramp-up phase. Strong correlation between the density gradient and the ion temperature gradient was observed, indicating that particle transport and ion thermal transport are strongly coupled or the density gradient assists the ion temperature ITB formation through suppression of drift wave instabilities such as ion temperature gradient mode. These results support that the density and ion temperature ITBs can be formed under reactor relevant conditions.

26 CFR 48.4081-2 - Taxable fuel; tax on removal at a terminal rack.

Code of Federal Regulations, 2011 CFR

2011-04-01

... connection with the removal of diesel fuel or kerosene that is not dyed and marked in accordance with § 48... fuel or kerosene is dyed and marked in accordance with § 48.4082-1. (4) Example. The following example... blendstocks), 48.4082-1 (relating to dyed diesel fuel and dyed kerosene), 48.4082-5 (relating to diesel fuel...

26 CFR 48.4081-2 - Taxable fuel; tax on removal at a terminal rack.

Code of Federal Regulations, 2012 CFR

2012-04-01

... connection with the removal of diesel fuel or kerosene that is not dyed and marked in accordance with § 48... fuel or kerosene is dyed and marked in accordance with § 48.4082-1. (4) Example. The following example... blendstocks), 48.4082-1 (relating to dyed diesel fuel and dyed kerosene), 48.4082-5 (relating to diesel fuel...

26 CFR 48.4081-2 - Taxable fuel; tax on removal at a terminal rack.

Code of Federal Regulations, 2013 CFR

2013-04-01

... connection with the removal of diesel fuel or kerosene that is not dyed and marked in accordance with § 48... fuel or kerosene is dyed and marked in accordance with § 48.4082-1. (4) Example. The following example... blendstocks), 48.4082-1 (relating to dyed diesel fuel and dyed kerosene), 48.4082-5 (relating to diesel fuel...

Omigapil treatment decreases fibrosis and improves respiratory rate in dy(2J) mouse model of congenital muscular dystrophy.

PubMed

Yu, Qing; Sali, Arpana; Van der Meulen, Jack; Creeden, Brittany K; Gordish-Dressman, Heather; Rutkowski, Anne; Rayavarapu, Sree; Uaesoontrachoon, Kitipong; Huynh, Tony; Nagaraju, Kanneboyina; Spurney, Christopher F

2013-01-01

Congenital muscular dystrophy is a distinct group of diseases presenting with weakness in infancy or childhood and no current therapy. One form, MDC1A, is the result of laminin alpha-2 deficiency and results in significant weakness, respiratory insufficiency and early death. Modification of apoptosis is one potential pathway for therapy in these patients. dy(2J) mice were treated with vehicle, 0.1 mg/kg or 1 mg/kg of omigapil daily via oral gavage over 17.5 weeks. Untreated age matched BL6 mice were used as controls. Functional, behavioral and histological measurements were collected. dy(2J) mice treated with omigapil showed improved respiratory rates compared to vehicle treated dy(2J) mice (396 to 402 vs. 371 breaths per minute, p<0.03) and similar to control mice. There were no statistical differences in normalized forelimb grip strength between dy(2J) and controls at baseline or after 17.5 weeks and no significant differences seen among the dy(2J) treatment groups. At 30-33 weeks of age, dy(2J) mice treated with 0.1 mg/kg omigapil showed significantly more movement time and less rest time compared to vehicle treated. dy(2J) mice showed normal cardiac systolic function throughout the trial. dy(2J) mice had significantly lower hindlimb maximal (p<0.001) and specific force (p<0.002) compared to the control group at the end of the trial. There were no statistically significant differences in maximal or specific force among treatments. dy(2J) mice treated with 0.1 mg/kg/day omigapil showed decreased percent fibrosis in both gastrocnemius (p<0.03) and diaphragm (p<0.001) compared to vehicle, and in diaphragm (p<0.013) when compared to 1 mg/kg/day omigapil treated mice. Omigapil treated dy(2J) mice demonstrated decreased apoptosis. Omigapil therapy (0.1 mg/kg) improved respiratory rate and decreased skeletal and respiratory muscle fibrosis in dy(2J) mice. These results support a putative role for the use of omigapil in laminin deficient congenital muscular dystrophy patients.

Impaired fetal muscle development and JAK-STAT activation mark disease onset and progression in a mouse model for merosin-deficient congenital muscular dystrophy.

PubMed

Nunes, Andreia M; Wuebbles, Ryan D; Sarathy, Apurva; Fontelonga, Tatiana M; Deries, Marianne; Burkin, Dean J; Thorsteinsdóttir, Sólveig

2017-06-01

Merosin-deficient congenital muscular dystrophy type 1A (MDC1A) is a dramatic neuromuscular disease in which crippling muscle weakness is evident from birth. Here, we use the dyW mouse model for human MDC1A to trace the onset of the disease during development in utero. We find that myotomal and primary myogenesis proceed normally in homozygous dyW-/- embryos. Fetal dyW-/- muscles display the same number of myofibers as wildtype (WT) muscles, but by E18.5 dyW-/- muscles are significantly smaller and muscle size is not recovered post-natally. These results suggest that fetal dyW-/- myofibers fail to grow at the same rate as WT myofibers. Consistent with this hypothesis between E17.5 and E18.5 dyW-/- muscles display a dramatic drop in the number of Pax7- and myogenin-positive cells relative to WT muscles, suggesting that dyW-/- muscles fail to generate enough muscle cells to sustain fetal myofiber growth. Gene expression analysis of dyW-/- E17.5 muscles identified a significant increase in the expression of the JAK-STAT target gene Pim1 and muscles from 2-day and 3-week old dyW-/- mice demonstrate a dramatic increase in pSTAT3 relative to WT muscles. Interestingly, myotubes lacking integrin α7β1, a laminin-receptor, also show a significant increase in pSTAT3 levels compared with WT myotubes, indicating that α7β1 can act as a negative regulator of STAT3 activity. Our data reveal for the first time that dyW-/- mice exhibit a myogenesis defect already in utero. We propose that overactivation of JAK-STAT signaling is part of the mechanism underlying disease onset and progression in dyW-/- mice. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Varicocelescintigraphy versus X-ray phlebography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oei, H.Y.; Arndt, J.W.; Mali, W.P.T.

1984-01-01

In this study varicocelescintigraphy (VS) is compared to X-ray phlebography(XP). In 104 patients (pts) suspected for varicocele on physical examination, VS was performed using a large field camera and 5 mCi Tc-99m in-vivo labeled erythrocytes. This was done (without Valsalva) in upright position after taping penis to the abdomen, marking the penisbase and covering the thighs with lead. Twenty 5-sec dynamic images (DY) and 5-min static image (ST) were made. Variocele-size was quantitated by bloodpoolvalue (BPV) using digital image of ST. BPV is the ratio of mean counts/pixel in varicocele and right iliac vessels calculated from adjacent pixels with maximummore » counts. On XP varicocele was diagnosed if the testicular vein was visualized after contrast injection given during Valsalva in the renal vein. In 85 pts varicocele was confirmed on XP. In 67 of them this was recognized easily on both DY and ST; the DY shows activity in the varicocele 10-35 sec later than the iliac artery and the ST shows pooling of activity below the penisbase. In 11 pts the varicocele was only seen on ST and in other 5 pts only on DY. In the remaining 2 pts both DY and ST were false negative. The BPV in 72 pts with abnormal DY and in 11 pts with normal DY varied between 0.4 - 2.2(0.89 +- 0.38) resp. 0.4 - 1.0(0.61 +- 0.19). In 16 of the 19 pts who showed no varicocele on XP, VS also was negative; their BPV varied between 0.2 - 0.4(0.30 +- 0.08). However, in 3 pts who initially had a normal XP, varicocele was diagnosed on both DY and ST, which was confirmed when XP was repeated. Diagnosis of varicocele by physical examination is not accurate. VS is suitable for screenings procedure when both DY and ST are obtained. Pts with abnormal DY have larger varicocele than pts with normal DY.« less

Long-lived K isomer and enhanced γ vibration in the neutron-rich nucleus 172Dy: Collectivity beyond double midshell

NASA Astrophysics Data System (ADS)

Watanabe, H.; Zhang, G. X.; Yoshida, K.; Walker, P. M.; Liu, J. J.; Wu, J.; Regan, P. H.; Söderström, P.-A.; Kanaoka, H.; Korkulu, Z.; Lee, P. S.; Nishimura, S.; Yagi, A.; Ahn, D. S.; Alharbi, T.; Baba, H.; Browne, F.; Bruce, A. M.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Doornenbal, P.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Isobe, T.; Kanaya, S.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lane, G. J.; Lee, C. S.; Lee, E. J.; Lorusso, G.; Lotay, G.; Moon, C.-B.; Nishizuka, I.; Nita, C. R.; Odahara, A.; Patel, Z.; Phong, V. H.; Podolyák, Zs.; Roberts, O. J.; Sakurai, H.; Schaffner, H.; Shand, C. M.; Shimizu, Y.; Sumikama, T.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Valiente-Dóbon, J. J.; Xu, Z. Y.

2016-09-01

The level structure of 172Dy has been investigated for the first time by means of decay spectroscopy following in-flight fission of a 238U beam. A long-lived isomeric state with T1/2 = 0.71 (5) s and Kπ =8- has been identified at 1278 keV, which decays to the ground-state and γ-vibrational bands through hindered electromagnetic transitions, as well as to the daughter nucleus 172Ho via allowed β decays. The robust nature of the Kπ =8- isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus. Meanwhile, the γ-vibrational levels have been identified at unusually low excitation energy compared to the neighboring well-deformed nuclei, indicating the significance of the microscopic effect on the non-axial collectivity in this doubly mid-shell region. The underlying mechanism of enhanced γ vibration is discussed in comparison with the deformed Quasiparticle Random-Phase Approximation based on a Skyrme energy-density functional.

Rare earth separations by selective borate crystallization

PubMed Central

Yin, Xuemiao; Wang, Yaxing; Bai, Xiaojing; Wang, Yumin; Chen, Lanhua; Xiao, Chengliang; Diwu, Juan; Du, Shiyu; Chai, Zhifang; Albrecht-Schmitt, Thomas E.; Wang, Shuao

2017-01-01

Lanthanides possess similar chemical properties rendering their separation from one another a challenge of fundamental chemical and global importance given their incorporation into many advanced technologies. New separation strategies combining green chemistry with low cost and high efficiency remain highly desirable. We demonstrate that the subtle bonding differences among trivalent lanthanides can be amplified during the crystallization of borates, providing chemical recognition of specific lanthanides that originates from Ln3+ coordination alterations, borate polymerization diversity and soft ligand coordination selectivity. Six distinct phases are obtained under identical reaction conditions across lanthanide series, further leading to an efficient and cost-effective separation strategy via selective crystallization. As proof of concept, Nd/Sm and Nd/Dy are used as binary models to demonstrate solid/aqueous and solid/solid separation processes. Controlling the reaction kinetics gives rise to enhanced separation efficiency of Nd/Sm system and a one-step quantitative separation of Nd/Dy with the aid of selective density-based flotation. PMID:28290448

Delayed demagnetization jumps in (NdDy)(FeCo)B magnets in a steady-state magnetic field

NASA Astrophysics Data System (ADS)

L'vova, G. L.; Kirman, M. V.; Koplak, O. V.; Kucheryaev, V. V.; Valeev, R. A.; Piskorskii, V. P.; Morgunov, R. B.

2017-11-01

Spontaneous demagnetization jumps are observed in sintered magnets (Nd0.6Dy0.4)16(Fe0.77Co0.23)78B6 in a constant magnetic field after a sharp decrease in an external magnetic field from the value corresponding to the saturation to a value close to the coercive force. It is shown that the number of the magnetization jumps is proportional to their amplitudes. A low value of the autocorrelation coefficient between the jump amplitude and the time of its appearance ( R < 0.1) demonstrate the stochasticity of the jumps. It is found that the spectral jump density is independent of the frequency, i.e., a white magnetic noise is observed. The distribution of the magnetic field gradient has been obtained near the sample surface that makes it possible to distinguish domains and the grain magnetization in the dependence on the direction of the texturing of the sintered magnet.

Extended phase diagram of R NiC2 family: Linear scaling of the Peierls temperature

NASA Astrophysics Data System (ADS)

Roman, Marta; Strychalska-Nowak, Judyta; Klimczuk, Tomasz; Kolincio, Kamil K.

2018-01-01

Physical properties for the late-lanthanide-based R NiC2 (R =Dy , Ho, Er, and Tm) ternary compounds are reported. All the compounds show antiferromagnetic ground state with the Néel temperature ranging from 3.4 K for HoNiC2 to 8.5 K for ErNiC2. The results of the transport and galvanomagnetic properties confirm a charge density wave state at and above room temperature with transition temperatures TCDW=284 , 335, 366, and 394 K for DyNiC2, HoNiC2, ErNiC2, and TmNiC2, respectively. The Peierls temperature TCDW scales linearly with the unit cell volume. A similar linear dependence has been observed for the temperature of the lock-in transition T1 as well. Beyond the intersection point of the trend lines, the lock-in transition is no longer observed. In this Rapid Communication we demonstrate an extended phase diagram for the R NiC2 family.

A study of the Coriolis effect on the fluid flow profile in a centrifugal bioreactor.

PubMed

Detzel, Christopher J; Thorson, Michael R; Van Wie, Bernard J; Ivory, Cornelius F

2009-01-01

Increasing demand for tissues, proteins, and antibodies derived from cell culture is necessitating the development and implementation of high cell density bioreactors. A system for studying high density culture is the centrifugal bioreactor (CCBR), which retains cells by increasing settling velocities through system rotation, thereby eliminating diffusional limitations associated with mechanical cell retention devices. This article focuses on the fluid mechanics of the CCBR system by considering Coriolis effects. Such considerations for centrifugal bioprocessing have heretofore been ignored; therefore, a simpler analysis of an empty chamber will be performed. Comparisons are made between numerical simulations and bromophenol blue dye injection experiments. For the non-rotating bioreactor with an inlet velocity of 4.3 cm/s, both the numerical and experimental results show the formation of a teardrop shaped plume of dye following streamlines through the reactor. However, as the reactor is rotated, the simulation predicts the development of vortices and a flow profile dominated by Coriolis forces resulting in the majority of flow up the leading wall of the reactor as dye initially enters the chamber, results are confirmed by experimental observations. As the reactor continues to fill with dye, the simulation predicts dye movement up both walls while experimental observations show the reactor fills with dye from the exit to the inlet. Differences between the simulation and experimental observations can be explained by excessive diffusion required for simulation convergence, and a slight density difference between dyed and un-dyed solutions. Implications of the results on practical bioreactor use are also discussed. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.

A Study of the Coriolis Effect on the Fluid Flow Profile in a Centrifugal Bioreactor

PubMed Central

Detzel, Christopher J.; Thorson, Michael R.; Van Wie, Bernard J.; Ivory, Cornelius F.

2011-01-01

Increasing demand for tissues, proteins, and antibodies derived from cell culture is necessitating the development and implementation of high cell density bioreactors. A system for studying high density culture is the centrifugal bioreactor (CCBR) which retains cells by increasing settling velocities through system rotation, thereby eliminating diffusional limitations associated with mechanical cell retention devices. This paper focuses on the fluid mechanics of the CCBR system by considering Coriolis effects. Such considerations for centrifugal bioprocessing have heretofore been ignored; therefore a simpler analysis of an empty chamber will be performed. Comparisons are made between numerical simulations and bromophenol blue dye injection experiments. For the non-rotating bioreactor with an inlet velocity of 4.3 cm/s, both the numerical and experimental results show the formation of a teardrop shaped plume of dye following streamlines through the reactor. However, as the reactor is rotated the simulation predicts the development of vortices and a flow profile dominated by Coriolis forces resulting in the majority of flow up the leading wall of the reactor as dye initially enters the chamber, results confirmed by experimental observations. As the reactor continues to fill with dye, the simulation predicts dye movement up both walls while experimental observations show the reactor fills with dye from the exit to the inlet. Differences between the simulation and experimental observations can be explained by excessive diffusion required for simulation convergence, and a slight density difference between dyed and un-dyed solutions. Implications of the results on practical bioreactor use are also discussed. PMID:19455639

Heterometallic Zn3 Ln3 Ensembles Containing (μ6 -CO3 ) Ligand and Triangular Disposition of Ln3+ ions: Analysis of Single-Molecule Toroic (SMT) and Single-Molecule Magnet (SMM) Behavior.

PubMed

Goura, Joydeb; Colacio, Enrique; Herrera, Juan Manuel; Suturina, Elizaveta A; Kuprov, Ilya; Lan, Yanhua; Wernsdorfer, Wolfgang; Chandrasekhar, Vadapalli

2017-11-21

Two new heterometallic Zn 3 Ln 3 (Ln 3+ =Dy, Tb) complexes, with a double triangular topology of the metal ions, have been assembled from the polytopic Mannich base ligand 6,6'-{[2-(dimethylamino)ethylazanediyl]bis(methylene)}bis(2-methoxy-4-methylphenol) (H 2 L) with the aid of an in situ generated carbonate ligand from atmospheric CO 2 fixation. Theoretical calculations indicate axial ground states for the Ln 3+ ions in these complexes, with their local magnetic moments being almost coplanar and tangential to the Ln 3+ atoms that define the equilateral triangle. Therefore, they can be considered as single-molecule toroics (SMTs) with almost zero total magnetic moment. Micro-SQUID measurements on the Dy 3+ counterpart show hysteresis loops below 3 K that have an S-shape, with large coercive fields opening upon cooling. This behavior is typical of a single molecule magnet (SMM) with very slow zero-field relaxation. At around ±0.35 T, the loops have a broad step, which is due to a direct relaxation process and corresponds to an acceleration of the relaxation of the magnetization, also observed at this magnetic field from ac susceptibility measurements. Simulations suggest that the broad step corresponds to two level avoidance of crossing points where the spin chiral Kramers doublet meets excited states of the coupled manifold, whose position is defined by exchange and dipole interactions. The Tb 3+ counterpart does not exhibit SMM behavior, which is due to the fact that the degeneracy of the ground state of the exchange coupled system is lifted at zero field, thus favoring quantum tunneling of magnetization (QTM). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luminescence characteristics of Dy3+ activated Na 2Sr 2Mg (BO 3)2F 2: Dy 3+ phosphor

NASA Astrophysics Data System (ADS)

Wani, Javaid A.; Dhoble, N. S.; Dhoble, S. J.

2012-11-01

In this paper, we have reported a new Na 2Sr 2Mg (BO 3)2F 2:Dy 3+ thermoluminescence (TL) phosphor prepared via the wet chemical method. Prepared phosphor was characterized by X-ray powder diffraction, photoluminescence (PL), TL and scanning electronmicroscopy techniques. The scanning electronmicroscopic image of Na 2Sr 2Mg (BO 3)2F 2:Dy 3+ phosphor confirms the micron size of particles. Under the PL study, the characteristic emission spectrum of Dy 3+ corresponding to 4F 9/2→6H 15/2 (481 nm) and 4F 9/2→6H 13/2 (576 nm) transitions was observed. The TL property of the as prepared phosphor was also found to be good. TL intensity of Na 2Sr2Mg(BO 3)F 2:Dy 3+ phosphors at 0.99 kGy exposure of γ-irradiations was compared with standard CaSO 4:Dy phosphor. It was seen that TL intensity of Na 2Sr 2Mg (BO 3)2F 2: Dy 3+ phosphors is 1.1 times less compared with the standard CaSO 4:Dy TL dosimeter phosphor. The kinetic parameters are also discussed in detail. The values of activation energy E (eV) and frequency factor S (s -1) were found to be 0.57 eV and 1.25×106 s-1, respectively.

Growth and optical properties of Dy doped and undoped n-type InSe single crystal

NASA Astrophysics Data System (ADS)

Gürbulak, B.

1999-02-01

Undoped n-InSe and Dy doped n-InSe (n-InSe : Dy) single crystals were grown by a method which is similar to direct freezing method. Ingots had no cracks and voids on the surface. There were no processes to polish and clean treatment at cleavage faces of these samples because of the natural mirror-like cleavage faces. The absorption measurements were carried out in n-InSe and n-InSe : Dy samples in the temperature range 10-320 K. The first exciton energies for n=1 were calculated as 1.331, 1.248 eV in n-InSe and were 1.326, 1.244 eV in n-InSe : Dy at 10 and 300 K, respectively. The second exciton energies for n=2 in n-InSe were calculated as 1.346, 1.336 eV and in n-InSe : Dy were 1.340, 1.332 eV at 10 and 80 K, respectively. Binding energies of n-InSe and n-InSe : Dy were calculated as 19.47 and 18.87 meV, respectively. The direct bands gap for n-InSe are 1.350, 1.267 eV and for n-InSe : Dy are 1.344, 1.263 eV at 10, 300 K, respectively.

Calibrating ion density profile measurements in ion thruster beam plasma

NASA Astrophysics Data System (ADS)

Zhang, Zun; Tang, Haibin; Ren, Junxue; Zhang, Zhe; Wang, Joseph

2016-11-01

The ion thruster beam plasma is characterized by high directed ion velocity (104 m/s) and low plasma density (1015 m-3). Interpretation of measurements of such a plasma based on classical Langmuir probe theory can yield a large experimental error. This paper presents an indirect method to calibrate ion density determination in an ion thruster beam plasma using a Faraday probe, a retarding potential analyzer, and a Langmuir probe. This new method is applied to determine the plasma emitted from a 20-cm-diameter Kaufman ion thruster. The results show that the ion density calibrated by the new method can be as much as 40% less than that without any ion current density and ion velocity calibration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zhe, E-mail: zhenzhe1201@sina.com; Yang, Lei; Hang, Yin

Highly transparent Dy{sup 3+}-doped terbium gallium garnet (TGG) single crystal was grown by Czochralski (Cz) method. Phase composition of the crystal was tested by XRD measurements. The distribution coefficient of Dy{sup 3+} in the crystal was obtained. The optical and magneto-optical properties were analyzed in detail, and magnetic properties of the Dy{sup 3+}-TGG crystal were studied. The paramagnetic behavior is observed down to 10 K. The as-grown crystal exhibited high optical transmittance, particularly in the visible region. The Faraday rotation was investigated over visible and near-infrared regions (VIS–NIR) at room temperature. The Verdet constants increase at measured wavelengths and highmore » thermal stability was found in Dy{sup 3+}-doped TGG, as compared to the properties of pure TGG, indicating that Dy{sup 3+}-doped crystals are preferable for magneto-active materials used in Faraday devices at VIS–NIR wavelengths. - Graphical abstract: Highly transparent Dy{sup 3+}-doped terbium gallium garnet (TGG) and pure TGG single crystals were grown by Czochralski method. The Dy{sup 3+}-doped TGG possesses 20–30% higher Verdet values in reference to TGG independently on wavelength.« less

Dysprosium complexes with mono-/di-carboxylate ligands-From simple dimers to 2D and 3D frameworks

NASA Astrophysics Data System (ADS)

Zhang, Yingjie; Bhadbhade, Mohan; Scales, Nicholas; Karatchevtseva, Inna; Price, Jason R.; Lu, Kim; Lumpkin, Gregory R.

2014-11-01

Four dysprosium (Dy) single carboxylates, a formate, a propionate, a butyrate and an oxalate have been synthesized and structurally characterized. The structure of Dy(HCO2)3 (1) contains nine-fold coordinated Dy polyhedra in perfect tricapped trigonal prisms. They are linked through trigonal O atoms forming 1D pillars which are further linked together through tricapped O atoms into a 3D pillared metal organic framework. The network structure is stable up to 360 °C. The structure of [Dy2(C2O4)3(H2O)6]·2.5H2O (2) contains nine-fold coordinated Dy polyhedra linking together through μ2-bridging oxalate anions into a 2D hexagonal layered structure. Both [Dy2(Pr)6(H2O)4]·(HPr)0.5 (3) [Pr=(C2H5CO2)-1] and [Dy2(Bu)6(H2O)4] (4) [Bu=(C3H7CO2)-1] have similar di-nuclear structures. The Raman vibration modes of the complexes have been investigated.

Opportunities for Drell-Yan Physics at RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aschenauer, E.; Bland, L.; Crawford, H.

Drell-Yan (DY) physics gives the unique opportunity to study the parton structure of nucleons in an experimentally and theoretically clean way. With the availability of polarized proton-proton collisions and asymmetric d+Au collisions at the Relativistic Heavy Ion Collider (RHIC), we have the basic (and unique in the world) tools to address several fundamental questions in QCD, including the expected gluon saturation at low partonic momenta and the universality of transverse momentum dependent parton distribution functions. A Drell-Yan program at RHIC is tied closely to the core physics questions of a possible future electron-ion collider, eRHIC. The more than 80 participantsmore » of this workshop focused on recent progress in these areas by both theory and experiment, trying to address imminent questions for the near and mid-term future.« less

Lanthanides in molecular magnetism: old tools in a new field.

PubMed

Sorace, Lorenzo; Benelli, Cristiano; Gatteschi, Dante

2011-06-01

In this tutorial review we discuss some basic aspects concerning the magnetic properties of rare-earth ions, which are currently the subject of a renovated interest in the field of molecular magnetism, after the discovery that slow relaxation of the magnetization at liquid nitrogen temperature can occur in mononuclear complexes of these ions. Focusing on Dy(III) derivatives a tutorial discussion is given of the relation of the crystal field parameters, which determine the anisotropy of these systems and consequently their interesting magnetic properties, with the geometry of the coordination sphere around the lanthanide centre and with the pattern of f orbitals. The problem of systems of low point symmetry is also addressed by showing how detailed single crystal investigation, coupled to more sophisticated calculation procedures, is an absolute necessity to obtain meaningful structure-property relationships in these systems.

16 CFR 301.12 - Country of origin of imported furs.

Code of Federal Regulations, 2011 CFR

2011-01-01

... labeling shall be preceded by the term fur origin; as for example: Dyed Muskrat Fur Origin: Russia or Dyed... example: Tip-dyed Canadian American Sable Fur Origin: Canada or Russian Sable Fur Origin: Russia (f...

16 CFR 301.12 - Country of origin of imported furs.

Code of Federal Regulations, 2014 CFR

2014-01-01

... labeling shall be preceded by the term fur origin; as for example: Dyed Muskrat Fur Origin: Russia or Dyed... example: Tip-dyed Canadian American Sable Fur Origin: Canada or Russian Sable Fur Origin: Russia (f...

16 CFR 301.12 - Country of origin of imported furs.

Code of Federal Regulations, 2012 CFR

2012-01-01

... labeling shall be preceded by the term fur origin; as for example: Dyed Muskrat Fur Origin: Russia or Dyed... example: Tip-dyed Canadian American Sable Fur Origin: Canada or Russian Sable Fur Origin: Russia (f...

16 CFR 301.12 - Country of origin of imported furs.

Code of Federal Regulations, 2013 CFR

2013-01-01

... labeling shall be preceded by the term fur origin; as for example: Dyed Muskrat Fur Origin: Russia or Dyed... example: Tip-dyed Canadian American Sable Fur Origin: Canada or Russian Sable Fur Origin: Russia (f...

16 CFR 301.12 - Country of origin of imported furs.

Code of Federal Regulations, 2010 CFR

2010-01-01

... labeling shall be preceded by the term fur origin; as for example: Dyed Muskrat Fur Origin: Russia or Dyed... example: Tip-dyed Canadian American Sable Fur Origin: Canada or Russian Sable Fur Origin: Russia (f...

Heteropentanuclear Oxalato-Bridged nd–4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis, Crystal Structures, Aqueous Stability and Antiproliferative Activity

PubMed Central

Kuhn, Paul-Steffen; Cremer, Laura; Gavriluta, Anatolie; Jovanović, Katarina K; Filipović, Lana; Hummer, Alfred A; Büchel, Gabriel E; Dojčinović, Biljana P; Meier, Samuel M; Rompel, Annette; Radulović, Siniša; Tommasino, Jean Bernard; Luneau, Dominique; Arion, Vladimir B

2015-01-01

A series of heteropentanuclear oxalate-bridged Ru(NO)-Ln (4d–4f) metal complexes of the general formula (nBu4N)5[Ln{RuCl3(μ-ox)(NO)}4], where Ln=Y (2), Gd (3), Tb (4), Dy (5) and ox=oxalate anion, were obtained by treatment of (nBu4N)2[RuCl3(ox)(NO)] (1) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1, 2, and 5 were in addition analyzed by X-ray crystallography, 1 by Ru K-edge XAS and 1 and 2 by 13C NMR spectroscopy. X-ray diffraction showed that in 2 and 5 four complex anions [RuCl3(ox)(NO)]2− are coordinated to YIII and DyIII, respectively, with formation of [Ln{RuCl3(μ-ox)(NO)}4]5− (Ln=Y, Dy). While YIII is eight-coordinate in 2, DyIII is nine-coordinate in 5, with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu4N+ ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium-lanthanide complexes 2–5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC-5) and compared with those obtained for the previously reported Os(NO)-Ln (5d–4f) analogues (nBu4N)5[Ln{OsCl3(ox)(NO)}4] (Ln=Y (6), Gd (7), Tb (8), Dy (9)). Complexes 2–5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d–4f metal complexes 6–9 in terms of IC50 values. The highest antiproliferative activity with IC50 values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP-MS data, indicating five- to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells. PMID:26260662

A physicochemical research of the Dy-Sn-O system

NASA Astrophysics Data System (ADS)

Malinovskaya, Tatyana; Lysak, Ilya; Zhek, Valentina; Kuznetsova, Svetlana

2017-11-01

A physicochemical research of the processes of phase composition formation in the materials of the Dy-Sn-O system was performed. Phase composition was taking place in the course of thermal treatment of dysprosium (III) and tin (IV) codeposition products. These were codeposited from nitrate solutions at pH 7, and 25% ammonia water was used as the precipitant. Using thermal and X-ray diffraction analysis, it was found that in the above system at 90 wt. % of Dy2O3 and 10 wt. % of SnO2, when the precursors were heated above 600°C there are no solid solutions. In the meanwhile, at temperatures below 1000°C there is only one phase, Dy2O3. At temperatures above 1000°C, the system becomes bi-phase and includes Dy2O3 and Dy2Sn2O7.

Radioluminescence and photoluminescence properties of Dy-doped 12CaO • 7Al2O3 single crystals synthesized by the floating zone method

NASA Astrophysics Data System (ADS)

Kumamoto, Narumi; Nakauchi, Daisuke; Kato, Takumi; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-02-01

We have synthesized Dy-doped 12CaO • 7Al2O3 (Dy:C12A7) single crystals with various Dy concentrations by the floating zone (FZ) method and investigated the photoluminescence (PL) and X-ray induced radioluminescence (RL) properties. The PL emissions are observed around 480-490, 570-590, 650-690, and 750 nm due to the 4f-4f transitions of Dy3+ under excitation around 350-400 and 450 nm. The decay time constant (580 nm emission under 340-390 nm excitation) was approximately 0.54-0.58 ms. The RL also showed line emissions at 487, 580, 668, and 757 nm due to the 4f-4f transitions of Dy3+ while the decay time was approximately 0.49-0.53 ms.

Growth and optical properties of Dy:Y3Al5O12 crystal

NASA Astrophysics Data System (ADS)

Pan, Yuxin; Zhou, Shidong; Li, Dongzhen; Liu, Bin; Song, Qingsong; Liu, Jian; Liu, Peng; Ding, Yuchong; Wang, Xiaodan; Xu, Xiaodong; Xu, Jun

2018-02-01

High optical quality Dy:Y3Al5O12 (Dy:YAG) crystal has been grown by the Czochralski method. Absorption spectra, fluorescence spectra and fluorescence decay curve of Dy:YAG have been recorded at room temperature. The strongest emission of Dy:YAG crystal is near 583 nm, corresponding to the 4F9/2 → 6H13/2 transition. The Judd-Ofelt parameters Ω2, Ω4 and Ω6 were calculated to be 1.49 × 10-20 cm2, 0.94 × 10-20 cm2 and 3.20 × 10-20 cm2, respectively. The radiative transition rates, branching ratios and the emission cross sections were calculated. The fluorescence and radiative lifetimes are 0.40 ms and 1.02 ms, respectively, resulting in a quantum efficiency of 39.2%. The results indicate that the Dy:YAG crystal would be a promising yellow solid state laser material.

A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions.

PubMed

Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

2018-03-15

In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu 3+ ) ion. Upon addition of Eu 3+ ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Yb 3+ and Lu 3+ , into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu 3+ ions were investigated, including solution pH value, Eu 3+ ion concentration and interfering substances. The detection mechanism of Eu 3+ ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of Eu III -dtpa-bis(cytosine) at 375nm in the concentration range of 0.50×10 -5 mol∙L -1 -5.00×10 -5 mol∙L -1 of Eu 3+ ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65×10 -7 mol∙L -1 and the corresponding correlation coefficient (R 2 ) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu 3+ ion. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermo and mechanoluminescence of Dy3+ activated K2Mg2(SO4)3 phosphor

NASA Astrophysics Data System (ADS)

Panigrahi, A. K.; Dhoble, S. J.; Kher, R. S.; Moharil, S. V.

2003-08-01

A solid state diffusion method for the preparation of (K2 : Dy)Mg2(SO4)3 and (K2 : Dy,P)Mg2(SO4)3 phosphors is reported. Thermoluminescence (TL) and mechanoluminescence (ML) characteristics are studied. TL, shown by the (K2 : Dy,P)Mg2(SO4)3 phosphor is 60% as intense as the conventional CaSO4 : Dy phosphor used in the TLD of ionization radiation. It has a linear TL dose response and a negligible fading. These properties of (K2 : Dy,P)Mg2(SO4)3 should be suitable in dosimetry of ionization radiation using TL technique. ML of (K2 : Dy)Mg2(SO4)3 shows one peak which has been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radicals (anion radicals produced by γ-irradiation) released from traps during the mechanical pressure applied on the Dy activated K2Mg2(SO4)3 phosphor. This ML mechanism is proposed for γ-irradiated sulfate based phosphors. It has been found that the total light output, i.e. ML intensity, increases with concentration of dopant, strain rate and irradiation dose of the phosphor. Mechanoluminescence and ML emission spectra of (K2 : Dy)Mg2(SO4)3 were recorded for better understanding of the ML process. The TL and ML measurements have also been performed to elucidate the mechanism of ML. Some correlation between ML and TL has also been found.

Structural and transport properties of double perovskite Dy{sub 2}NiMnO{sub 6}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chanda, Sadhan, E-mail: sadhan.physics@gmail.com; Saha, Sujoy; Dutta, Alo

2015-02-15

Highlights: • Sol–gel citrate method is used to prepare the double perovskite Dy{sub 2}NiMnO{sub 6}. • Structure and dielectric relaxation of the sample are studied for nano and bulk phases. • The relaxation mechanism of the sample is modeled by Cole–Cole equation. • With increasing sintering temperature conductivity increases. • Electronic structures and magnetic properties have been studied by DFT calculations. - Abstract: The double perovskite oxide Dy{sub 2}NiMnO{sub 6} (DNMO) is synthesized in nano and bulk phase by the sol–gel citrate method. The Rietveld refinement of X-ray diffraction pattern of the sample at room temperature shows the monoclinic P2{submore » 1}/n phase. Dielectric relaxation of the sample is investigated in the impedance and electric modulus formalisms in the frequency range from 50 Hz to 1 MHz and in the temperature range from 253 to 415 K. The Cole–Cole model is used to explain the relaxation mechanism in DNMO. The frequency-dependent maxima in the imaginary part of impedance are found to obey an Arrhenius law with activation energy of 0.346 and 0.344 eV for nano and bulk DNMO, respectively. A significant increase in conductivity of bulk DNMO has been observed than that of the nanoceramic. Electronic structures and magnetic properties of DNMO have been studied by performing first principles calculation based on density functional theory.« less

Dysprosium-doped cadmium oxide as a gateway material for mid-infrared plasmonics

DOE PAGES

Sachet, Edward; Shelton, Christopher T.; Harris, Joshua S.; ...

2015-02-16

The interest in plasmonic technologies surrounds many emergent optoelectronic applications, such as plasmon lasers, transistors, sensors and information storage. Although plasmonic materials for ultraviolet–visible and near-infrared wavelengths have been found, the mid-infrared range remains a challenge to address: few known systems can achieve subwavelength optical confinement with low loss in this range. With a combination of experiments and ab initio modelling, here we demonstrate an extreme peak of electron mobility in Dy-doped CdO that is achieved through accurate ‘defect equilibrium engineering’. In so doing, we create a tunable plasmon host that satisfies the criteria for mid-infrared spectrum plasmonics, and overcomesmore » the losses seen in conventional plasmonic materials. In particular, extrinsic doping pins the CdO Fermi level above the conduction band minimum and it increases the formation energy of native oxygen vacancies, thus reducing their populations by several orders of magnitude. The substitutional lattice strain induced by Dy doping is sufficiently small, allowing mobility values around 500 cm 2 V –1 s –1 for carrier densities above 10 20 cm –3. As a result, our work shows that CdO:Dy is a model system for intrinsic and extrinsic manipulation of defects affecting electrical, optical and thermal properties, that oxide conductors are ideal candidates for plasmonic devices and that the defect engineering approach for property optimization is generally applicable to other conducting metal oxides.« less

Dysprosium-doped cadmium oxide as a gateway material for mid-infrared plasmonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sachet, Edward; Shelton, Christopher T.; Harris, Joshua S.

The interest in plasmonic technologies surrounds many emergent optoelectronic applications, such as plasmon lasers, transistors, sensors and information storage. Although plasmonic materials for ultraviolet–visible and near-infrared wavelengths have been found, the mid-infrared range remains a challenge to address: few known systems can achieve subwavelength optical confinement with low loss in this range. With a combination of experiments and ab initio modelling, here we demonstrate an extreme peak of electron mobility in Dy-doped CdO that is achieved through accurate ‘defect equilibrium engineering’. In so doing, we create a tunable plasmon host that satisfies the criteria for mid-infrared spectrum plasmonics, and overcomesmore » the losses seen in conventional plasmonic materials. In particular, extrinsic doping pins the CdO Fermi level above the conduction band minimum and it increases the formation energy of native oxygen vacancies, thus reducing their populations by several orders of magnitude. The substitutional lattice strain induced by Dy doping is sufficiently small, allowing mobility values around 500 cm 2 V –1 s –1 for carrier densities above 10 20 cm –3. As a result, our work shows that CdO:Dy is a model system for intrinsic and extrinsic manipulation of defects affecting electrical, optical and thermal properties, that oxide conductors are ideal candidates for plasmonic devices and that the defect engineering approach for property optimization is generally applicable to other conducting metal oxides.« less

The catalytic mechanism of dye-decolorizing peroxidase DyP may require the swinging movement of an aspartic acid residue.

PubMed

Yoshida, Toru; Tsuge, Hideaki; Konno, Hiroki; Hisabori, Toru; Sugano, Yasushi

2011-07-01

The dye-decolorizing peroxidase (DyP)-type peroxidase family is a unique heme peroxidase family. The primary and tertiary structures of this family are obviously different from those of other heme peroxidases. However, the details of the structure-function relationships of this family remain poorly understood. We show four high-resolution structures of DyP (EC1.11.1.19), which is representative of this family: the native DyP (1.40 Å), the D171N mutant DyP (1.42 Å), the native DyP complexed with cyanide (1.45 Å), and the D171N mutant DyP associated with cyanide (1.40 Å). These structures contain four amino acids forming the binding pocket for hydrogen peroxide, and they are remarkably conserved in this family. Moreover, these structures show that OD2 of Asp171 accepts a proton from hydrogen peroxide in compound I formation, and that OD2 can swing to the appropriate position in response to the ligand for heme iron. On the basis of these results, we propose a swing mechanism in compound I formation. When DyP reacts with hydrogen peroxide, OD2 swings towards an optimal position to accept the proton from hydrogen peroxide bound to the heme iron. © 2011 The Authors Journal compilation © 2011 FEBS.

Enhanced ultraviolet photo-response in Dy doped ZnO thin film

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Singh, Ranveer; Pandey, Praveen C.

2018-02-01

In the present work, a Dy doped ZnO thin film deposited by the spin coating method has been studied for its potential application in a ZnO based UV detector. The investigations on the structural property and surface morphology of the thin film ensure that the prepared samples are crystalline and exhibit a hexagonal crystal structure of ZnO. A small change in crystallite size has been observed due to Dy doping in ZnO. AFM analysis ascertains the grain growth and smooth surface of the thin films. The Dy doped ZnO thin film exhibits a significant enhancement in UV region absorption as compared to the pure ZnO thin film, which suggests that Dy doped ZnO can be used as a UV detector. Under UV irradiation of wavelength 325 nm, the photocurrent value of Dy doped ZnO is 105.54 μA at 4.5 V, which is 31 times greater than that of the un-doped ZnO thin film (3.39 μA). The calculated value of responsivity is found to increase significantly due to the incorporation of Dy in the ZnO lattice. The observed higher value of photocurrent and responsivity could be attributed to the substitution of Dy in the ZnO lattice, which enhances the conductivity, electron mobility, and defects in ZnO and benefits the UV sensing property.

Thermoluminescence dosimetry features of DY and Cu doped SrF2 nanoparticles under gamma irradiation.

PubMed

Zahedifar, M; Sadeghi, E; Kashefi Biroon, M; Harooni, S; Almasifard, F

2015-11-01

Dy and Cu-doped SrF2 nanoparticles (NPs) were synthesized by using co-precipitation method and their possible application to solid state dosimetry were studied and compared to that of pure SrF2 NPs. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used for sample characterization. The highest thermoluminescence (TL) response of SrF2:Dy and SrF2:Cu NPs were found respectively at 0.5 and 0.7mol% of Dy and Cu impurities. Seven overlapping glow peaks at 384, 406, 421, 449, 569, 495, 508K and three component glow peaks at 381, 421 and 467K were identified respectively for SrF2:Dy and SrF2:Cu NPs employing Tm-Tstop and computerized glow curve deconvolution (CGCD) methods. The TL sensitivity of SrF2:Dy is approximately the same as that of LiF:Mg,Ti (TLD-100) cheeps. Linear dose response were observed for the SrF2:Dy and SrF2:Cu NPs up to the absorbed doses of 1kGy and 10kGy correspondingly. Regarding other dosimetry characteristics of the produced NPs such as fading, reproducibility and thermal treatment, Dy and Cu doped SrF2 NPs recommend for high dose TL dosimetry applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Temperature and magnetic field induced multiple magnetic transitions in DyAg(2).

PubMed

Arora, Parul; Chattopadhyay, M K; Sharath Chandra, L S; Sharma, V K; Roy, S B

2011-02-09

The magnetic properties of the rare-earth intermetallic compound DyAg(2) are studied in detail with the help of magnetization and heat capacity measurements. It is shown that the multiple magnetic phase transitions can be induced in DyAg(2) both by temperature and magnetic field. The detailed magnetic phase diagram of DyAg(2) is determined experimentally. It was already known that DyAg(2) undergoes an incommensurate to commensurate antiferromagnetic phase transition close to 10 K. The present experimental results highlight the first order nature of this phase transition, and show that this transition can be induced by magnetic field as well. It is further shown that another isothermal magnetic field induced transition or metamagnetic transition exhibited by DyAg(2) at still lower temperatures is also of first order nature. The multiple magnetic phase transitions in DyAg(2) give rise to large peaks in the temperature dependence of the heat capacity below 17 K, which indicates its potential as a magnetic regenerator material for cryocooler related applications. In addition it is found that because of the presence of the temperature and field induced magnetic phase transitions, and because of short range magnetic correlations deep inside the paramagnetic regime, DyAg(2) exhibits a fairly large magnetocaloric effect over a wide temperature window, e.g., between 10 and 60 K.

Structure of dysprosium(111) dl-tartrate dimer in aqueous solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chevela, V.V.; Vulfson, S.G.; Salnikov, Y.I.

1994-10-01

The paramagnetic birefringence method was supplemented by numerical simulation to determine the molar paramagnetic-birefringence constant of the dysprosium dl-tartrate dimer Dy{sub 2}(d-L)(l-L){sup 2-} (I), where d-L{sup 4-} and l-L{sup 4-} are the deprotonated d- and l-tartaric acid molecules, respectively. The structure of the ligand and hydration surroundings of I was modeled by molecular mechanic calculations (the Dashevskii-Pylamovatyi model). It is shown that adequate results can be obtained only if one takes into account the coordination of I to the Na{sup +} ion.

Poly[[[μ3-N′-(carboxymethyl)ethylene­di­amine-N,N,N′-triacetato]dysprosium(III)] trihydrate

PubMed Central

Zhuang, Xiaomei; Long, Qingping; Wang, Jun

2010-01-01

In the title coordination polymer, {[Dy(C10H13N2O8)]·3H2O}n, the dysprosium(III) ion is coordinated by two N atoms and six O atoms from three different (carb­oxy­meth­yl)ethyl­ene­diamine­triacetate ligands in a distorted square-anti­prismatic geometry. The ligands connect the metal atoms, forming layers parallel to the ab plane. O—H⋯O hydrogen bonds further assemble adjacent layers into a three-dimensional supra­molecular network. PMID:21588859

Orientational Order in Liquid Crystal Complexes Based on Lanthanides

NASA Astrophysics Data System (ADS)

Dobrun, L. A.; Kovshik, A. P.; Ryumtsev, E. I.; Kalinkin, A. A.

2018-04-01

In this study, we have for the first time determined the degree of an orientational order S for a series of liquid-crystal complexes based on lanthanides (Eu+3, Gd+3, Tb+3, Dy+3) with the same ligand composition in the temperature range of existence of the nematic phase by using experimental refractometry results. We have also found an even-odd alternative S as number of protons in the ions complexing agent has consecutively increased. The obtained values of S have been compared with the corresponding degrees of order of the calamite organic liquid crystals.

Electrochemical Approach for Analyzing Electrolyte Transport Properties and Their Effect on Protonic Ceramic Fuel Cell Performance.

PubMed

Danilov, Nikolay; Lyagaeva, Julia; Vdovin, Gennady; Medvedev, Dmitry; Demin, Anatoly; Tsiakaras, Panagiotis

2017-08-16

The design and development of highly conductive materials with wide electrolytic domain boundaries are among the most promising means of enabling solid oxide fuel cells (SOFCs) to demonstrate outstanding performance across low- and intermediate-temperature ranges. While reducing the thickness of the electrolyte is an extensively studied means for diminishing the total resistance of SOFCs, approaches involving an improvement in the transport behavior of the electrolyte membranes have been less-investigated. In the present work, a strategy for analyzing the electrolyte properties and their effect on SOFC output characteristics is proposed. To this purpose, a SOFC based on a recently developed BaCe 0.5 Zr 0.3 Dy 0.2 O 3-δ proton-conducting ceramic material was fabricated and tested. The basis of the strategy consists of the use of traditional SOFC testing techniques combined with the current interruption method and electromotive force measurements with a modified polarization-correction assessment. This allows one to determine simultaneously such important parameters as maximal power density; ohmic and polarization resistances; average ion transport numbers; and total, ionic, and electronic film conductivities and their activation energies. The proposed experimental procedure is expected to expand both fundamental and applied basics that could be further adopted to improve the technology of electrochemical devices based on proton-conducting electrolytes.

Dysprosium electrodeposition from a hexaalkylguanidinium-based ionic liquid

NASA Astrophysics Data System (ADS)

Berger, Claudia A.; Arkhipova, Maria; Maas, Gerhard; Jacob, Timo

2016-07-01

The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer.The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer. Electronic supplementary information (ESI) available. See DOI: 10.1039/C6NR01351A

Positron Annihilation Measurements of High Temperature Superconductors

NASA Astrophysics Data System (ADS)

Jung, Kang

1995-01-01

The temperature dependence of positron annihilation parameters has been measured for basic YBCO, Dy-doped, and Pr-doped superconducting compounds. The physical properties, such as crystal structure, electrical resistance, and critical temperature, have been studied for all samples. In the basic YBCO and Dy-doped samples, the defect -related lifetime component tau_{2 } was approximately constant from room temperature to above the critical temperature and then showed a step -like decrease in the temperature range 90K { ~} 40K. No significant temperature dependence was found in the short- and long-lifetime components, tau_{1} and tau_{3}. The x-ray diffraction data showed that the crystal structure of these two samples was almost the same. These results indicated that the electronic structure changed below the critical temperature. No transition was observed in the Pr-doped YBCO sample. The advanced computer program "PFPOSFIT" for positron lifetime analysis was modified to run on the UNIX system of the University of Utah. The destruction of superconductivity with Pr doping may be due to mechanisms such as hole filling or hole localization of the charge carriers and may be related to the valence state of the Pr ion. One-parameter analyses like the positron mean lifetime parameter and the Doppler line shape parameter S also have been studied. It was found that a transition in Doppler line shape parameter S was associated with the superconducting transition temperature in basic YBCO, Dy -doped, and 0.5 Pr-doped samples, whereas no transition was observed in the nonsuperconducting Pr-doped sample. The Doppler results indicate that the average electron momentum at the annihilation sites increases as temperature is lowered across the superconducting transition range and that electronic structure change plays an important role in high temperature superconductivity.

Synthesis and magneto-structural studies on a new family of carbonato bridged 3d-4f complexes featuring a [CoLn(CO3)] (Ln = La, Gd, Tb, Dy and Ho) core: slow magnetic relaxation displayed by the cobalt(ii)-dysprosium(iii) analogue.

PubMed

Majee, Mithun Chandra; Towsif Abtab, Sk Md; Mondal, Dhrubajyoti; Maity, Manoranjan; Weselski, Marek; Witwicki, Maciej; Bieńko, Alina; Antkowiak, Michał; Kamieniarz, Grzegorz; Chaudhury, Muktimoy

2018-03-06

A new family of [3 + 3] hexanuclear 3d-4f complexes [(μ 3 -CO 3 ){Co II Ln III L(μ 3 -OH)(OH 2 )} 3 ]-(ClO 4 )·mC 2 H 5 OH·nH 2 O (1-5) [Ln = La (1), Gd (2), Tb (3), Dy (4), and Ho (5)] have been prepared in moderate to high yields (62-78%) following a self-assembly reaction between the ligand 6,6',6''-(nitrilotris(methylene))tris-(2-methoxy-4-methylphenol) (H 3 L), Co(OAc) 2 ·4H 2 O and the lanthanide ion precursors in the mandatory presence of tetrabutylammonium hydroxide. During the reaction, atmospheric carbon dioxide is fixed in the product molecule as a bridging carbonato ligand which connects all the three lanthanide centers of this molecular assembly through a rare η 2 :η 2 :η 2 -μ 3 mode of bridging as revealed from X-ray crystallography. The metal centers in all these compounds, except the Gd III analogue (2), are coupled in antiferromagnetic manner while the nature of coupling in the CoGd complex is ferromagnetic. DFT calculations revealed that this ferromagnetic interaction occurs most likely by the Co II -Gd III superexchange, mediated via the bridging oxygen atoms. Only the Co II -Dy III compound (4) displayed a slow relaxation of the magnetization at a very low temperature as established by AC susceptibility measurements. The data provides an estimation of the activation energy U/k B = 9.2 K and the relaxation time constant τ 0 = 1.0 × 10 -7 s.

Core-shell structured SiO2@YVO4:Dy3+/Sm3+ phosphor particles: sol-gel preparation and characterization.

PubMed

Wang, H; Yu, M; Lin, C K; Lin, J

2006-08-01

Spherical SiO(2) particles have been coated with YVO(4):Dy(3+)/Sm(3+) phosphor layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO(2)@YVO(4):Dy(3+)/Sm(3+) particles. X-ray diffraction (XRD), Fourier-transform IR spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting SiO(2)@YVO(4):Dy(3+)/Sm(3+) core-shell phosphors. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 300 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (20 nm for one deposition cycle). The core-shell particles show strong characteristic emission from Dy(3+) for SiO(2)@YVO(4):Dy(3+) and from Sm(3+) for SiO(2)@YVO(4):Sm(3+) due to an efficient energy transfer from YVO(4) host to them. The PL intensity of Dy(3+) and Sm(3+) increases with raising the annealing temperature and the number of coating cycles.

Strategic coating of NdFeB magnets with Dy to improve the coercivity of permanent magnets

DOE PAGES

Ucar, Huseyin; Parker, David S.; Nlebedim, I. C.; ...

2015-12-25

Here, we present a method, supported by theoretical analysis, for optimizing the usage of the critical rare earth element dysprosium in Nd 2Fe 14B (NdFeB)-based permanent magnets. In this method, we use Dy selectively in locations such as magnet edges and faces, where demagnetization factors are most significant, rather than uniformly throughout the bulk sample. A 200 nm thick Dy film was sputtered onto commercial N-38, NdFeB magnets with a thickness of 3 mm and post-annealed at temperatures from 600 - 700 C. Magnets displayed enhanced coercivities after post-annealing. Furthermore, our experimental results indicate as large as a 5 percentmore » increase in the energy product of NdFeB magnets, achieved for a total Dy weight percentage of 0.06 percent, much less than that used in commercial grade Dy-NdFeB magnets. Finally, by assuming all Dy diffused into NdFeB magnets, the improvement in energy product corresponds to a saving of over 1% Dy (critical element). Magnets manufactured using this technique will therefore be higher performing and significantly less expensive than those made presently.« less

Thermoelectric properties of Ca0.8Dy0.2MnO3 synthesized by solution combustion process

NASA Astrophysics Data System (ADS)

Park, Kyeongsoon; Lee, Ga Won

2011-10-01

High-quality Ca0.8Dy0.2MnO3 nano-powders were synthesized by the solution combustion process. The size of the synthesized Ca0.8Dy0.2MnO3 powders was approximately 23 nm. The green pellets were sintered at 1150-1300°C at a step size of 50°C. Sintered Ca0.8Dy0.2MnO3 bodies crystallized in the perovskite structure with an orthorhombic symmetry. The sintering temperature did not affect the Seebeck coefficient, but significantly affected the electrical conductivity. The electrical conductivity of Ca0.8Dy0.2MnO3 increased with increasing temperature, indicating a semiconducting behavior. The absolute value of the Seebeck coefficient gradually increased with an increase in temperature. The highest power factor (3.7 × 10-5 Wm-1 K-2 at 800°C) was obtained for Ca0.8Dy0.2MnO3 sintered at 1,250°C. In this study, we investigated the microstructure and thermoelectric properties of Ca0.8Dy0.2MnO3, depending on sintering temperature.

Thermoelectric properties of Ca0.8Dy0.2MnO3 synthesized by solution combustion process

PubMed Central

2011-01-01

High-quality Ca0.8Dy0.2MnO3 nano-powders were synthesized by the solution combustion process. The size of the synthesized Ca0.8Dy0.2MnO3 powders was approximately 23 nm. The green pellets were sintered at 1150-1300°C at a step size of 50°C. Sintered Ca0.8Dy0.2MnO3 bodies crystallized in the perovskite structure with an orthorhombic symmetry. The sintering temperature did not affect the Seebeck coefficient, but significantly affected the electrical conductivity. The electrical conductivity of Ca0.8Dy0.2MnO3 increased with increasing temperature, indicating a semiconducting behavior. The absolute value of the Seebeck coefficient gradually increased with an increase in temperature. The highest power factor (3.7 × 10-5 Wm-1 K-2 at 800°C) was obtained for Ca0.8Dy0.2MnO3 sintered at 1,250°C. In this study, we investigated the microstructure and thermoelectric properties of Ca0.8Dy0.2MnO3, depending on sintering temperature. PMID:21974984

Thermoelectric properties of Ca0.8Dy0.2MnO3 synthesized by solution combustion process.

PubMed

Park, Kyeongsoon; Lee, Ga Won

2011-10-05

High-quality Ca0.8Dy0.2MnO3 nano-powders were synthesized by the solution combustion process. The size of the synthesized Ca0.8Dy0.2MnO3 powders was approximately 23 nm. The green pellets were sintered at 1150-1300°C at a step size of 50°C. Sintered Ca0.8Dy0.2MnO3 bodies crystallized in the perovskite structure with an orthorhombic symmetry. The sintering temperature did not affect the Seebeck coefficient, but significantly affected the electrical conductivity. The electrical conductivity of Ca0.8Dy0.2MnO3 increased with increasing temperature, indicating a semiconducting behavior. The absolute value of the Seebeck coefficient gradually increased with an increase in temperature. The highest power factor (3.7 × 10-5 Wm-1 K-2 at 800°C) was obtained for Ca0.8Dy0.2MnO3 sintered at 1,250°C. In this study, we investigated the microstructure and thermoelectric properties of Ca0.8Dy0.2MnO3, depending on sintering temperature.

Production and validation of model iron-tannate dyed textiles for use as historic textile substitutes in stabilisation treatment studies

PubMed Central

2012-01-01

Background For millennia, iron-tannate dyes have been used to colour ceremonial and domestic objects shades of black, grey, or brown. Surviving iron-tannate dyed objects are part of our cultural heritage but their existence is threatened by the dye itself which can accelerate oxidation and acid hydrolysis of the substrate. This causes many iron-tannate dyed textiles to discolour and decrease in tensile strength and flexibility at a faster rate than equivalent undyed textiles. The current lack of suitable stabilisation treatments means that many historic iron-tannate dyed objects are rapidly crumbling to dust with the knowledge and value they hold being lost forever. This paper describes the production, characterisation, and validation of model iron-tannate dyed textiles as substitutes for historic iron-tannate dyed textiles in the development of stabilisation treatments. Spectrophotometry, surface pH, tensile testing, SEM-EDX, and XRF have been used to characterise the model textiles. Results On application to textiles, the model dyes imparted mid to dark blue-grey colouration, an immediate tensile strength loss of the textiles and an increase in surface acidity. The dyes introduced significant quantities of iron into the textiles which was distributed in the exterior and interior of the cotton, abaca, and silk fibres but only in the exterior of the wool fibres. As seen with historic iron-tannate dyed objects, the dyed cotton, abaca, and silk textiles lost tensile strength faster and more significantly than undyed equivalents during accelerated thermal ageing and all of the dyed model textiles, most notably the cotton, discoloured more than the undyed equivalents on ageing. Conclusions The abaca, cotton, and silk model textiles are judged to be suitable for use as substitutes for cultural heritage materials in the testing of stabilisation treatments. PMID:22616934

Mechanistic Insights into Dye-Decolorizing Peroxidase Revealed by Solvent Isotope and Viscosity Effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrestha, Ruben; Huang, Gaochao; Meekins, David A.

Dye-decolorizing peroxidases (DyPs) are a family of H2O2-dependent heme peroxidases that have shown potential applications in lignin degradation and valorization. However, the DyP kinetic mechanism remains underexplored. Using structural biology and solvent isotope (sKIE) and viscosity effects, many mechanistic characteristics have been determined for the B-class ElDyP from Enterobacter lignolyticus. Its structure revealed that a water molecule acts as the sixth axial ligand and two channels at diameters of ~3.0 and 8.0 Å lead to the heme center. A conformational change of ERS* to ERS, which have identical spectral characteristics, was proposed as the final step in DyPs’ bisubstrate Ping-Pongmore » mechanism. This step is also the rate-determining step in ABTS oxidation. The normal KIE of wild-type ElDyP with D2O2 at pD 3.5 suggested that compound 0 deprotonation by the distal aspartate is rate-limiting in the formation of compound I, which is more reactive under acidic pH than under neutral or alkaline pH. The viscosity effects and other biochemical methods implied that the reducing substrate binds with compound I instead of the free enzyme. The significant inverse sKIEs of kcat/KM and kERS* suggested that the aquo release in ElDyP is mechanistically important and may explain the enzyme’s adoption of two-electron reduction for compound I. The distal aspartate is catalytically more important than the distal arginine and plays key roles in determining ElDyP’s optimum acidic pH. The kinetic mechanism of D143H-ElDyP was also briefly studied. The results obtained will pave the way for future protein engineering to improve DyPs’ lignolytic activity.« less

Mechanistic Insights into Dye-Decolorizing Peroxidase Revealed by Solvent Isotope and Viscosity Effects

PubMed Central

Shrestha, Ruben; Huang, Gaochao; Meekins, David A.; Geisbrecht, Brian V.; Li, Ping

2017-01-01

Dye-decolorizing peroxidases (DyPs) are a family of H2O2-dependent heme peroxidases, which have shown potential applications in lignin degradation and valorization. However, the DyP kinetic mechanism remains underexplored. Using structural biology and solvent isotope (sKIE) and viscosity effects, many mechanistic characteristics have been uncovered for the B-class ElDyP from Enterobacter lignolyticus. Its structure revealed that a water molecule acts as the sixth axial ligand with two channels at diameters of ~3.0 and 8.0 Å leading to the heme center. A conformational change of ERS* to ERS, which have identical spectral characteristics, was proposed as the final step in DyPs’ bisubstrate Ping-Pong mechanism. This step is also the rate-determining step in ABTS oxidation. The normal KIE of wild-type ElDyP with D2O2 at pH 3.5 suggested that cmpd 0 deprotonation by the distal aspartate is rate-limiting in the formation of cmpd I, which is more reactive under acidic pH than under neutral or alkaline pH. The viscosity effects and other biochemical methods implied that the reducing substrate binds with cmpd I instead of the free enzyme. The significant inverse sKIEs of kcat/KM and kERS* suggested that the aquo release in DyPs is mechanistically important and may explain the enzyme’s adoption of two-electron reduction for cmpd I. The distal aspartate is catalytically more important than the distal arginine and plays key roles in determining DyPs’ acidic pH optimum. The kinetic mechanism of D143H-ElDyP was also briefly studied. The results obtained will pave the way for future protein engineering to improve DyPs’ lignolytic activity. PMID:29308295

Production and validation of model iron-tannate dyed textiles for use as historic textile substitutes in stabilisation treatment studies.

PubMed

Wilson, Helen; Carr, Chris; Hacke, Marei

2012-05-22

For millennia, iron-tannate dyes have been used to colour ceremonial and domestic objects shades of black, grey, or brown. Surviving iron-tannate dyed objects are part of our cultural heritage but their existence is threatened by the dye itself which can accelerate oxidation and acid hydrolysis of the substrate. This causes many iron-tannate dyed textiles to discolour and decrease in tensile strength and flexibility at a faster rate than equivalent undyed textiles. The current lack of suitable stabilisation treatments means that many historic iron-tannate dyed objects are rapidly crumbling to dust with the knowledge and value they hold being lost forever.This paper describes the production, characterisation, and validation of model iron-tannate dyed textiles as substitutes for historic iron-tannate dyed textiles in the development of stabilisation treatments. Spectrophotometry, surface pH, tensile testing, SEM-EDX, and XRF have been used to characterise the model textiles. On application to textiles, the model dyes imparted mid to dark blue-grey colouration, an immediate tensile strength loss of the textiles and an increase in surface acidity. The dyes introduced significant quantities of iron into the textiles which was distributed in the exterior and interior of the cotton, abaca, and silk fibres but only in the exterior of the wool fibres. As seen with historic iron-tannate dyed objects, the dyed cotton, abaca, and silk textiles lost tensile strength faster and more significantly than undyed equivalents during accelerated thermal ageing and all of the dyed model textiles, most notably the cotton, discoloured more than the undyed equivalents on ageing. The abaca, cotton, and silk model textiles are judged to be suitable for use as substitutes for cultural heritage materials in the testing of stabilisation treatments.

Examination of ionic wind and cathode sheath effects in a E-field premixed flame with ion density measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, Stewart V., E-mail: svj0001@uah.edu; Xu, Kunning G., E-mail: gabe.xu@uah.edu

2016-04-15

The effect of the ionic wind on a premixed methane-air flame under a DC electric field is studied via mapping of the ion density with Langmuir probes. Ion densities were observed to increase near the burner with increasing electrode voltage up to 6 kV. Past this electrode supply voltage, ion densities ceased increasing and began to decline in some locations within the premixed flame. The increased ion density is caused by an increase in ionic wind force and cathode sheath thickness. The plateau in density is due to the cathode sheath fully encompassing the flame front which is the ion source,more » thereby collecting all ions in the flame. The spatial density data support the ionic wind hypothesis and provide further explanation of its limits based on the plasma sheath.« less

Facile fabrication of corrosion-resistant superhydrophobic and superoleophilic surfaces with MnWO(4):Dy(3+) microbouquets.

PubMed

Li, Taohai; Li, Quanguo; Yan, Jing; Li, Feng

2014-04-21

Superhydrophobic and superoleophilic MnWO4:Dy(3+) microbouquets were successfully fabricated via a facile hydrothermal process. The surface morphologies and chemical composition were investigated by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The wettability of the as-synthesized MnWO4:Dy(3+) microbouquet film was studied by measuring the water contact angle (CA). A static CA for water of 165° and a very low sliding angle (SA) were observed, which were closely related to both the MnWO4:Dy(3+) microbouquet structure and chemical modification. Furthermore, the as-prepared MnWO4:Dy(3+) surface showed superhydrophobicity for some corrosive liquids such as aqueous basic and salt solutions.

Electron density profile measurements at a self-focusing ion beam with high current density and low energy extracted through concave electrodes.

PubMed

Fujiwara, Y; Hirano, Y; Kiyama, S; Nakamiya, A; Koguchi, H; Sakakita, H

2014-02-01

The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are ∼0.9 eV and ∼8 × 10(8) cm(-3) at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.

Ionization balance in Titan's nightside ionosphere

NASA Astrophysics Data System (ADS)

Vigren, E.; Galand, M.; Yelle, R. V.; Wellbrock, A.; Coates, A. J.; Snowden, D.; Cui, J.; Lavvas, P.; Edberg, N. J. T.; Shebanits, O.; Wahlund, J.-E.; Vuitton, V.; Mandt, K.

2015-03-01

Based on a multi-instrumental Cassini dataset we make model versus observation comparisons of plasma number densities, nP = (nenI)1/2 (ne and nI being the electron number density and total positive ion number density, respectively) and short-lived ion number densities (N+, CH2+, CH3+, CH4+) in the southern hemisphere of Titan's nightside ionosphere over altitudes ranging from 1100 and 1200 km and from 1100 to 1350 km, respectively. The nP model assumes photochemical equilibrium, ion-electron pair production driven by magnetospheric electron precipitation and dissociative recombination as the principal plasma neutralization process. The model to derive short-lived-ion number densities assumes photochemical equilibrium for the short-lived ions, primary ion production by electron-impact ionization of N2 and CH4 and removal of the short-lived ions through reactions with CH4. It is shown that the models reasonably reproduce the observations, both with regards to nP and the number densities of the short-lived ions. This is contrasted by the difficulties in accurately reproducing ion and electron number densities in Titan's sunlit ionosphere.

Comparative Cold Shock Expression and Characterization of Fungal Dye-Decolorizing Peroxidases.

PubMed

Behrens, Christoph J; Zelena, Kateryna; Berger, Ralf G

2016-08-01

Dye-decolorizing peroxidases (DyPs) from Auricularia auricula-judae, Bjerkandera adusta, Pleurotus ostreatus and Marasmius scorodonius (Basidiomycota) were expressed in Escherichia coli using the cold shock-inducible expression system pCOLD I DNA. Functional expression was achieved without the addition of hemin or the co-expression of any chaperones. The presence or absence of the native signal sequence had a strong impact on the success of the expression, but the effect was not consistent for the different DyPs. While BaDyP and AajDyP were stable at 50 °C, the more thermolabile MsP2 and PoDyp, upon catalytic intervention, lend themselves to more rapid thermal inactivation. The bleaching of norbixin (E 160b) using MsP2 was most efficient at pH 4.0, while BaDyP and AajDypP worked best in the weakly acidic to neutral range, indicating a choice of DyPs for a broad field of applications in different food matrices.

Enhanced Emission from Li2CaSiO4:Dy3+ Phosphors by Doping with Al3+ and B3+

NASA Astrophysics Data System (ADS)

Erdoğmuş, E.

2016-05-01

Pure Li2CaSiO4, Li2CaSiO4:Dy3+ and Al3+, B3+ co-doped materials were prepared by a solid-state reaction in air at 900°C for 6 h and characterized by using powder XRD. The luminescence properties of the synthesized phosphors were measured at room temperature with a spectrofluorometer. Li2CaSiO4:Dy3+ emits at 484, 575, and 660 nm upon 352 nm excitation. The emission spectrum intensity of Dy3+ increased from 0.01 to 0.06 mol.%, and beyond 0.06 mol.%, concentration quenching was observed. Also, in this study, the effects of boric acid and aluminum oxide concentration on the photoluminescence properties of Dy3+ doped phosphors were investigated. The results showed that boric acid and aluminum oxide were effective in improving the photoluminescence intensity of Li2CaSiO4:Dy3+ compounds.

Effects of meteoric smoke particles on the D region ion chemistry

NASA Astrophysics Data System (ADS)

Baumann, Carsten; Rapp, Markus; Anttila, Milla; Kero, Antti; Verronen, Pekka T.

2015-12-01

This study focuses on meteor smoke particle (MSP) induced effects on the D region ion chemistry. Hereby, MSPs, represented with an 11 bin size distribution, have been included as an active component into the Sodankyä Ion and Neutral Chemistry model. By doing that, we model the diurnal variation of the negatively and positively charged MSPs as well as ions and the electron density under quiet ionospheric conditions. Two distinct points in time are studied in more detail, i.e., one for sunlit conditions (Solar zenith angle is 72°) and one for dark conditions (Solar zenith angle is 103°). We find nightly decrease of free electrons and negative ions, the positive ion density is enhanced at altitudes above 80 km and reduced below. During sunlit conditions the electron density is enhanced between 60 and 70 km altitude, while there is a reduction in negative and positive ions densities. In general, the MSP influence on the ion chemistry is caused by changes in the electron density. On the one hand, these changes occur due to nightly electron scavenging by MSPs resulting in a reduced electron-ion recombination. As a consequence positive ion density increase, especially water cluster ions are highly affected. On the other hand, the electron density is slightly increased during daytime by a MSP-related production due to solar radiation. Thus, more electrons attach to neutrals and short-lived negative ions increase in number density. The direct attachment of ions to MSPs is a minor process, but important for long living ions.

Synthesis of SrAl2O4:Eu2+ phosphors co-doped with Dy3+, Tb3+, Si4+ and optimization of co-doping amount by response surface method

NASA Astrophysics Data System (ADS)

Wang, Huan; Liang, Xiaoping; Liu, Kai; Zhou, Qianqian; Chen, Peng; Wang, Jun; Li, Jianxin

2016-03-01

Dy3+ doped SrAl2O4:Eu2+ phosphors were synthesized by high temperature solid phase method in a weak reducing atmosphere (5% H2 + 95% N2). The relationship between the crushed granularity and the phosphors brightness was studied. The effect of co-doping amount of Dy3+, Tb3+ and Si4+ on the structure and properties of SrAl2O4:Eu2+ via response surface method was investigated. Photoluminescence measurement results showed that the initial afterglow brightness of 0.002 mol% Dy3+ doped SrAl2O4:Eu2+0.002 phosphors decreased after first increased within the sintering temperature range from 1150 to 1400 °C, which created the highest value of 12,101 mcd/m2 at 1300 °C. Numerous coarse particles in the powder ought to be crushed for the practical application, however, the brightness became lower accompanied by the decrease of the granularity. The luminescence property of SrAl2O4:Eu2+ sintered at 1200 °C improved by co-doping Dy3+-Tb3+-Si4+. The results of response surface method showed that the influence extent on the luminescence property was Dy3+ > Tb3+ > Si4+. When the co-doping amount in SrAl2O4:Eu2+0.002 phosphors of Dy3+, Tb3+ and Si4+ was 0.001 mol%, 0.0005 mol% and 0.002 mol%, respectively, the initial afterglow brightness of SrAl2O4 was up to the highest value of 12,231 mcd/m2, which was in good agreement on the predicted maximum value of 12,519 mcd/m2 with the optimum co-doping amount of 0.0015 mol% Dy3+, 0.0005 mol% Tb3+ and 0.0017 mol% Si4+. The brightness of co-doped phosphors not only increased by 56.79% than that of SrAl2O4:Eu2+0.002, Dy3+0.002 sintered at 1200 °C, but also was above that of 1300 °C. The emission spectra results showed that, compared with 0.001 mol% Dy3+ doped phosphor, the emission peak of 0.001 mol% Dy3+-0.001 mol% Tb3+ co-doped phosphor generated red shift and increased by 9.3% in emission intensity; 0.001 mol% Dy3+-0.004 mol% Si4+ and 0.001 mol% Dy3+-0.001 mol% Tb3+-0.004 mol% Si4+ co-doped SrAl2O4:Eu2+0.002 emission peak created blue shift and increased by 37.2% and 47.6% in emission intensity, respectively.

Effect of annealing high-dose heavy-ion irradiated high-temperature superconductor wires

NASA Astrophysics Data System (ADS)

Strickland, N. M.; Wimbush, S. C.; Kluth, P.; Mota-Santiago, P.; Ridgway, M. C.; Kennedy, J. V.; Long, N. J.

2017-10-01

Heavy-ion irradiation of high-temperature superconducting thin films has long been known to generate damage tracks of amorphized material that are of close-to-ideal dimension to effectively contribute to pinning of magnetic flux lines and thereby enhance the in-field critical current. At the same time, though, the presence of these tracks reduces the superconducting volume fraction available to transport current while the irradiation process itself generates oxygen depletion and disorder in the remaining superconducting material. We have irradiated commercially available superconducting coated conductors consisting of a thick film of (Y,Dy)Ba2Cu3O7 deposited on a buffered metal tape substrate in a continuous reel-to-reel process. Irradiation was by 185 MeV 197Au ions. A high fluence of 3 × 1011 ions/cm2 was chosen to emphasize the detrimental effects. The critical current was reduced following this irradiation, but annealing at relatively low temperatures of 200 °C and 400 °C substantially restore the critical current of the irradiated material. At high fields and high temperatures there is a net benefit of critical current compared to the untreated material.

Lanthanide binding and IgG affinity construct: Potential applications in solution NMR, MRI, and luminescence microscopy

PubMed Central

Barb, Adam W; Ho, Tienhuei Grace; Flanagan-Steet, Heather; Prestegard, James H

2012-01-01

Paramagnetic lanthanide ions when bound to proteins offer great potential for structural investigations that utilize solution nuclear magnetic resonance spectroscopy, magnetic resonance imaging, or optical microscopy. However, many proteins do not have native metal ion binding sites and engineering a chimeric protein to bind an ion while retaining affinity for a protein of interest represents a significant challenge. Here we report the characterization of an immunoglobulin G-binding protein redesigned to include a lanthanide binding motif in place of a loop between two helices (Z-L2LBT). It was shown to bind Tb3+ with 130 nM affinity. Ions such as Dy3+, Yb3+, and Ce3+ produce paramagnetic effects on NMR spectra and the utility of these effects is illustrated by their use in determining a structural model of the metal-complexed Z-L2LBT protein and a preliminary characterization of the dynamic distribution of IgG Fc glycan positions. Furthermore, this designed protein is demonstrated to be a novel IgG-binding reagent for magnetic resonance imaging (Z-L2LBT:Gd3+ complex) and luminescence microscopy (Z-L2LBT: Tb3+ complex). PMID:22851279

Development of the EQ-5D-Y: a child-friendly version of the EQ-5D

PubMed Central

Wille, Nora; Badia, Xavier; Bonsel, Gouke; Burström, Kristina; Cavrini, Gulia; Devlin, Nancy; Egmar, Ann-Charlotte; Greiner, Wolfgang; Gusi, Narcis; Herdman, Michael; Jelsma, Jennifer; Kind, Paul; Scalone, Luciana

2010-01-01

Purpose To develop a self-report version of the EQ-5D for younger respondents, named the EQ-5D-Y (Youth); to test its comprehensibility for children and adolescents and to compare results obtained using the standard adult EQ-5D and the EQ-5D-Y. Methods An international task force revised the content of EQ-5D and wording to ensure relevance and clarity for young respondents. Children’s and adolescents’ understanding of the EQ-5D-Y was tested in cognitive interviews after the instrument was translated into German, Italian, Spanish and Swedish. Differences between the EQ-5D and the EQ-5D-Y regarding frequencies of reported problems were investigated in Germany, Spain and South Africa. Results The content of the EQ-5D dimensions proved to be appropriate for the measurement of HRQOL in young respondents. The wording of the questionnaire had to be adapted which led to small changes in the meaning of some items and answer options. The adapted EQ-5D-Y was satisfactorily understood by children and adolescents in different countries. It was better accepted and proved more feasible than the EQ-5D. The administration of the EQ-5D and of the EQ-5D-Y causes differences in frequencies of reported problems. Conclusions The newly developed EQ-5D-Y is a useful tool to measure HRQOL in young people in an age-appropriate manner. PMID:20405245

Correlation of an infrared absorption with carriers in rare-earth monoantimonides

NASA Astrophysics Data System (ADS)

Kwon, Y. S.; Jung, M. H.; Lee, K. R.; Kimura, S.; Suzuki, T.

1997-09-01

Dielectric constants spectra were obtained in the single crystals LaSb, PrSb, GdSb and DySb at several temperatures. The spectra for these crystals except for LaSb show Drude's behavior with a hump due to an anomalous absorption lying at about 0.25 eV. The inverse of effective electron number ( NIA) of the absorption is linear in temperature, and the NIA at each temperature is dependent on the square of the effective Bohr magneton of each rare-earth ion. The sum of the number of effective electrons due to Drude adsorption and that due to infrared absorption agree well with the number of carriers obtained from their band calculations or their dHvAs. Therefore, this absorption seems to be due to the intraband transition induced by the scattering between the spin of carriers and the localized magnetic moments at each site of rare-earth ion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adare, A.; Afanasiev, S.; Aidala, C.

Measurements of bottomonium production in heavy-ion and p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ(1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and p+p collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV. The Υ(1S + 2S + 3S) → e⁺e⁻ differential cross section at midrapidity was found to be B eedσ/dy = 108 ± 38 (stat) ± 15 (syst) ± 11 (luminosity) pb in p+p collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression ofmore » the total Υ state yield relative to the extrapolation from p+p collision data. Thus, the suppression is consistent with measurements at higher energies by the CMS experiment at the Large Hadron Collider.« less

Characterization of the third-order optical nonlinearity spectrum of barium borate glasses

NASA Astrophysics Data System (ADS)

Santos, S. N. C.; Almeida, J. M. P.; Paula, K. T.; Tomazio, N. B.; Mastelaro, V. R.; Mendonça, C. R.

2017-11-01

Borate glasses have proven to be an important material for applications ranging from radiation dosimetry to nonlinear optics. In particular, B2O3-BaO based glasses are attractive to frequency generation since their barium metaborate phase (β-BaB2O4 or β-BBO) may be crystallized under proper heat treatment. Despite the vast literature covering their linear and second-order optical nonlinear properties, their third-order nonlinearities remain overlooked. This paper thus reports a study on the nonlinear refraction (n2) of BBO and BBS-DyEu glasses through femtosecond Z-scan technique. The results were modeled using the BGO approach, which showed that oxygen ions are playing a role in the nonlinear optical properties of the glasses studied here. In addition, the barium borate glasses containing rare-earths ions were found to exhibit larger nonlinearities, which is in agreement with previous studies.

Challenges in the Search for Magnetic Coupling in 3d/4f Materials: Syntheses, Structures, and Magnetic Properties of the Lanthanide Copper Heterobimetallic Compounds, RE 2 Cu(TeO 3 ) 2 (SO 4 ) 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Jian; Chai, Ping; Diefenbach, Kariem

2014-03-03

Twelve new lanthanide copper heterobimetallic compounds, RE2Cu(TeO3)2(SO4)2 (RE = Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), with two different structural topologies, have been prepared by hydrothermal treatment. Both structure types crystallize in the triclinic space group, Pmore » $$\\bar{1}$$, but the unit cell parameters and structures are quite different. The earlier RE2Cu(TeO3)2(SO4)2 (RE = Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm) share a common structural motif consisting of edge-sharing LnO8 chains and [Cu(TeO3)2(SO4)2]6– units. The later lanthanide version (Yb and Lu) is composed of edge-sharing LnO7 dimers bridged by similar [Cu(TeO3)2(SO4)2]6– units. The change in the structure type can be attributed to the decreasing ionic radii of the lanthanides. The compounds containing RE3+ ions with diamagnetic ground states (Y3+ and Eu3+) exhibit antiferromagnetic ordering at 12.5 K and 15 K, respectively, owing to the magnetic exchange between Cu2+ moments. No magnetic phase transition was observed in all the other phases. The lack of magnetic ordering is attributed to the competing magnetic interactions caused by the presence of paramagnetic RE3+ ions. The magnetism data suggests that substantial 3d–4f coupling only occurs in the Yb analogue.« less

Investigation of the silicon ion density during molecular beam epitaxy growth

NASA Astrophysics Data System (ADS)

Eifler, G.; Kasper, E.; Ashurov, Kh.; Morozov, S.

2002-05-01

Ions impinging on a surface during molecular beam epitaxy influence the growth and the properties of the growing layer, for example, suppression of dopant segregation and the generation of crystal defects. The silicon electron gun in the molecular beam epitaxy (MBE) equipment is used as a source for silicon ions. To use the effect of ion bombardment the mechanism of generation and distribution of ions was investigated. A monitoring system was developed and attached at the substrate position in the MBE growth chamber to measure the ion and electron densities towards the substrate. A negative voltage was applied to the substrate to modify the ion energy and density. Furthermore the current caused by charge carriers impinging on the substrate was measured and compared with the results of the monitoring system. The electron and ion densities were measured by varying the emission current of the e-gun achieving silicon growth rates between 0.07 and 0.45 nm/s and by changing the voltage applied to the substrate between 0 to -1000 V. The dependencies of ion and electron densities were shown and discussed within the framework of a simple model. The charged carrier densities measured with the monitoring system enable to separate the ion part of the substrate current and show its correlation to the generation rate. Comparing the ion density on the whole substrate and in the center gives a hint to the ion beam focusing effect. The maximum ion and electron current densities obtained were 0.40 and 0.61 μA/cm2, respectively.

Ternary Dy-Er-Al magnetic refrigerants

DOEpatents

Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

1995-07-25

A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

78 FR 17642 - Determination Under the Textile and Apparel Commercial Availability Provision of the Dominican...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-22

... Agreements (``CITA'') has determined that certain piece dyed three-thread fleece fabric, as specified below... behalf of Garan Manufacturing, Inc. for certain piece dyed three-thread fleece fabric, as specified below... Commercial Availability proceedings. SPECIFICATIONS: Certain Piece Dyed Three-thread Fleece Fabric HTS: 6001...

Services Training Manager’s Guide.

DTIC Science & Technology

1986-04-01

and Cookies 27906-Dr-Air Force Food Service Program-Vegetable Preparation 27954-DF-Air Force Food Service Program-Mission Support Meals 28003-DF-USAF...Quality Audit Program 28246-DF-Sweet Doughs 59 *. 282 50-DY-Quick Breads 38712-DY-Hamburger Sandwich, The 39420-DYP-Give Your Eggs a Break3 39421-DY

Hydrothermally synthesized barium fluoride nanocubes for thermoluminescence dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhadane, Mahesh S.; Dahiwale, S. S.; Bhoraskar, V. N.

2016-05-23

In this work, we report a hydrothermally synthesized Dy doped BaF{sub 2} (BaF{sub 2}:Dy) nanocubes and its Thermoluminescence studies. The synthesized BaF{sub 2}:Dy samples was found to posses FCC structure and having average size ~ 60-70 nm, as revealed through X-Ray Diffraction. Cubical morphology having size ~90 nm was observed from TEM analysis. The {sup 60}Co γ- ray irradiated BaF{sub 2}:Dy TL dosimetric experiments shows a pre-dominant single glow peak at 153 °C, indicating a single level trap present as a metastable state. Furthermore, BaF{sub 2}:Dy nanophosphor shows a sharp linear response from 10 Gy to 3 kGy, thus it can be applicablemore » as a gamma dosimeter.« less

Thermoelectric Properties of Dy-Doped SrTiO3 Ceramics

NASA Astrophysics Data System (ADS)

Liu, J.; Wang, C. L.; Peng, H.; Su, W. B.; Wang, H. C.; Li, J. C.; Zhang, J. L.; Mei, L. M.

2012-11-01

Sr1- x Dy x TiO3 ( x = 0.02, 0.05, 0.10) ceramics were prepared by the reduced solid-state reaction method, and their thermoelectric properties were investigated from room temperature to 973 K. The resistivity increases with temperature, showing metallic behavior. The Seebeck coefficients tend to saturate at high temperatures, presenting narrow-band behavior, as proved by ab initio calculations of the electronic structure. The magnitudes of the Seebeck coefficient and the electrical resistivity decrease with increasing Dy content. At the same time, the thermal conductivity decreases because the lattice thermal conductivity is reduced by Dy substitution. The maximum value of the figure of merit reaches 0.25 at 973 K for the Sr0.9Dy0.1TiO3 sample.

Luminescence properties of Dy 3+ -doped Li 2 SrSiO 4 for NUV-excited white LEDs

NASA Astrophysics Data System (ADS)

You, Panli; Yin, Guangfu; Chen, Xianchun; Yue, Bo; Huang, Zhongbing; Liao, Xiaoming; Yao, Yadong

2011-09-01

A series of single-phase full color phosphors, Dy 3+-doped Li 2SrSiO 4 was synthesized by a solid-state reaction method. The phase of the as-prepared powders was measured by X-ray diffraction pattern (XRD) and the chemical composition was characterized using energy dispersive spectroscopy (EDS). The luminescent properties of Li 2SrSiO 4:Dy 3+ were systematically investigated by concentration quenching, decay behavior and thermal stability measurements. The results suggested that the emission intensity of the Li 2SrSiO 4:Dy 3+ was much stronger than that of Li 2SrSiO 4:Eu 2+. It was worth to mention that Li 2SrSiO 4:Dy 3+ phosphor possessed excellent thermal stability for use in light-emitting diodes (LEDs) and the emission intensity measured at 300 °C was only decreased 8% comparing with that measured at room temperature. Furthermore, the Commission International del'Eclairage (CIE) chromaticity coordinates of Li 2SrSiO 4:Dy 3+ moved toward the ideal white light coordinates (0.33, 0.33). All results demonstrated that Li 2SrSiO 4:Dy 3+ might be a potential phosphor for NUV-based white light-emitting diodes.

Spin reversal and ferroelectricity in perovskite Dy{sub 0.7}Sr{sub 0.3}MnO{sub 3} and Dy{sub 0.6}Sr{sub 0.4}MnO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Y.; Cao, S. X.; Ren, W., E-mail: renwei@shu.edu.cn

2015-08-17

Multiferroic materials which simultaneously exhibit electric polarization and magnetism have attracted more and more attention due to their novel physical properties and promising applications. Here, we report the magnetic and ferroelectric properties of single phase perovskite manganites Dy{sub 0.7}Sr{sub 0.3}MnO{sub 3} and Dy{sub 0.6}Sr{sub 0.4}MnO{sub 3} by varying temperature and magnetic field. Our results reveal that there exist spin reversal and strong antiferromagnetic pinning effects in both compounds, as well as negative magnetization in Dy{sub 0.6}Sr{sub 0.4}MnO{sub 3}. Moreover, upon Sr-doping, spontaneous electric polarizations have been observed and the maximum polarization value of Dy{sub 0.7}Sr{sub 0.3}MnO{sub 3} is about 1000 μC/m{supmore » 2} while Dy{sub 0.6}Sr{sub 0.4}MnO{sub 3} reaches to 2000 μC/m{sup 2}. The onset of the ferroelectric transition temperature is enhanced to be around 60 K. Our results indicate that the antiferromagnetic coupling is relevant to the ferroelectric properties of these fascinating multiferroic systems.« less

Peripheral territory and neuropeptides of the trigeminal ganglion neurons centrally projecting through the oculomotor nerve demonstrated by fluorescent retrograde double-labeling combined with immunocytochemistry.

PubMed

Bortolami, R; Calzà, L; Lucchi, M L; Giardino, L; Callegari, E; Manni, E; Pettorossi, V E; Barazzoni, A M; Lalatta Costerbosa, G

1991-04-26

The peripheral territories of sheep trigeminal neurons which send their central process to the brainstem through the oculomotor nerve were investigated by the use of fluorescent tracers in double-labeling experiments. For this purpose Diamidino yellow (DY) injection into the oculomotor nerve was combined with Fast blue (FB) injection either into the extraocular muscles (EOMs), or the cornea, or the superior eyelid. Double-labeled DY + FB cells were found in the ophthalmic region of the trigeminal ganglion in addition to single-labeled DY or FB cells. The DY and DY + FB-labeled trigeminal cells were analysed immunocytochemically for their content of substance P (SP)-, calcitonin gene-related peptide (CGRP)-, and cholecystokinin-8 (CCK-8)-like. All single-labeled DY cells showed SP-, CGRP- or CCK-8-like immunoreactivity. Double-labeled DY + FB neurons innervating the EOMs were immunoreactive for each of the three peptides, whereas double-labeled neurons supplying the cornea were only CGRP-like positive. The findings suggest that, in the sheep, trigeminal neurons which send their process centrally through the oculomotor nerve supply the EOMs, the cornea, and the superior eyelid and contain neuropeptides which are usually associated with pain sensation.

The glass-like thermal conductivity in ZrO2-Dy3TaO7 ceramic for promising thermal barrier coating application

NASA Astrophysics Data System (ADS)

Wu, Peng; Hu, Ming Yu; Chong, Xiao Yu; Feng, Jing

2018-03-01

Using the solid-state reaction method, the (ZrO2)x-(Dy3TaO7)1-x (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1) ceramics are synthesized in this work. The identification of the crystal structures indicates that the (ZrO2)x-(Dy3TaO7)1-x ceramics belong to the orthorhombic system, and the space group is C2221 in spite of the value of x increasing to 0.1. The thermal conductivities of the (ZrO2)x-(Dy3TaO7)1-x ceramics range from 1.3 W/(m K) to 1.8 W/(m K), and this value is much lower than that of 7-8 YSZ (yttria-stabilized zirconia). Besides, the (ZrO2)x-(Dy3TaO7)1-x ceramics possess the glass-like thermal conductivity caused by intrinsic oxygen vacancies existing in the lattice of Dy3TaO7. Moreover, the results of thermal expansion rates demonstrate that the (ZrO2)x-(Dy3TaO7)1-x ceramics possess excellent high temperature phase stability, and the thermal expansion coefficients [(9.7-11) × 10-6 K-1] are comparable to that of 7-8 YSZ.

Dysprosium complexes with mono-/di-carboxylate ligands—From simple dimers to 2D and 3D frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yingjie, E-mail: yzx@ansto.gov.au; Bhadbhade, Mohan; Scales, Nicholas

2014-11-15

Four dysprosium (Dy) single carboxylates, a formate, a propionate, a butyrate and an oxalate have been synthesized and structurally characterized. The structure of Dy(HCO{sub 2}){sub 3} (1) contains nine-fold coordinated Dy polyhedra in perfect tricapped trigonal prisms. They are linked through trigonal O atoms forming 1D pillars which are further linked together through tricapped O atoms into a 3D pillared metal organic framework. The network structure is stable up to 360 °C. The structure of [Dy{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 6}]·2.5H{sub 2}O (2) contains nine-fold coordinated Dy polyhedra linking together through μ{sub 2}-bridging oxalate anions into a 2D hexagonalmore » layered structure. Both [Dy{sub 2}(Pr){sub 6}(H{sub 2}O){sub 4}]·(HPr){sub 0.5} (3) [Pr=(C{sub 2}H{sub 5}CO{sub 2}){sup −1}] and [Dy{sub 2}(Bu){sub 6}(H{sub 2}O){sub 4}] (4) [Bu=(C{sub 3}H{sub 7}CO{sub 2}){sup −1}] have similar di-nuclear structures. The Raman vibration modes of the complexes have been investigated. - Graphical abstract: Four dysprosium (Dy) complexes with formate, propionate, butyrate and oxalate ligands have been synthesized and characterized. The Dy formato complex has a 3D pillared metal organic framework and the structure is stable up to 360 °C whilst the complexes with longer alkyl chained mono-carboxylates possess similar di-nuclear structures. The Dy oxalato complex has a 2D hexagonal (honeycomb-type) structure. Their Raman vibration modes have been investigated. - Highlights: • New Dysprosium complexes with formate, propionate, butyrate and oxalate ligands. • Crystal structures range from dimers to two and three dimensional frameworks. • Vibrational modes have been investigated and correlated to the structures. • The complexes are thermal robust and stable to over 300 °C.« less

The effects of the NMR shift-reagents Dy(PPP)2, Dy(TTHA) and Tm(DOTP) on developed pressure in isolated perfused rat hearts. The role of shift-reagent calcium complexes.

PubMed

Gaszner, B; Simor, T; Hild, G; Elgavish, G A

2001-11-01

The 23Na NMR shift-reagent complexes (Dy(PPP)2, Dy(TTHA), and Tm(DOTP)) bind stoichiometric amounts of Ca2+. Thus, in perfused rat heart systems, a supplementation of Ca2+ is required to maintain the requisite extracellular free calcium concentration ([Ca(o)]f) and to approximate a physiological level of contractile function. The amount of reagent-bound Ca2+ in a heart perfusate that contains a shift-reagent depends on: (1) Ca2+ binding by excess ligand used during the preparation of the shift-reagent; and (2) the Ca2+ binding affinity of the shift-reagent. To address point 1), we introduced a 1H and 31P NMR spectroscopic titration method to quantify directly the concentration of the excess ligand. We also used this method to minimize the amount of excess ligand (L) and thus the amount of Ca*L complex. To address point (2), we determined the stepwise Kd (microm) values of the Ca complexes of the three shift-reagents.: Dy(PPP)2, Kd=0.09, Kd2=7.9; Dy(TTHA), Kd1=10.66, Kd2=10.12; and Tm(DOTP), K(d1)=0.502, Kd2=4.98. The Kd values of the Ca complexes of the phosphonate and triphosphate based shift-reagents, Tm(DOTP) and Dy(PPP)2, respectively, are lower than those of the polyaminocarboxylate-based Dy(TTHA), indicating stronger Ca binding affinities for the former two types of complexes. We have also shown a positive correlation between [Ca(o)]f and left ventricular developed pressure (LVDP) in perfused rat hearts. Dy(TTHA) has shown no effect on LVDP v[Ca(o)]f. The LVDP values in the presence of the phosphonate and triphosphate based shift-reagents, however, were significantly higher than expected from the [Ca(o)]f levels alone. Thus a positive inotropic effect, independent of [Ca(o)]f, is evident in the presence of Tm(DOTP) or Dy(PPP)2. Copyright 2001 Academic Press.

Self-assembly of 2-aldehyde-8-hydroxyquinolinate-based lanthanide complexes and NIR luminescence

NASA Astrophysics Data System (ADS)

Zhang, Meiqi; Li, Hongfeng; Chen, Peng; Sun, Wenbin; Zhang, Lei; Yan, Pengfei

2015-02-01

Self-assembly reaction of 2-aldehyde-8-hydroxyquinoline, tris(hydroxymethyl)aminomethane and LnCl3ṡ6H2O affords a series of mononuclear lanthanide complexes Ce(baho)2·Et2O (1) (H2baho = 2,8-bis(2-(8-hydroxylquinolinyl))-1-aza-5-hydroxymethyl-3,7-dioxabicyclo[3.3.0]octane), Dy(nhm)2Cl·0.5H2O (2) and Ln(nhm)2Cl·0.5C6H14 (Ln = Ho (3), Er (4), Yb (5) and Hnhm = N-(2-(8-hydroxylquinolinyl)methylene)(trishydroxymethyl)methylamine. The crystal structures have been determined by X-ray crystallographic analysis, and the tetravalence of Ce in 1 has been proven by XPS. Interestingly, the positive charge of Ce4+ ion in 1 is neutralized by two deprotonated baho2- ligands, while two deprotonated nhm- ligands and one Cl- compensate the positive charge of Ln3+ ions in 2-5. Complex 5 exhibit essential NIR luminescence of Yb3+ ion with lifetime of 17.64 μs in solid and 9.96 μs in CH3OH solution.

Magnetization reversal process in (Sm, Dy, Gd) (Co, Fe, Cu, Zr)z magnets with different cellular structures

NASA Astrophysics Data System (ADS)

Liu, Lei; Liu, Zhuang; Zhang, Xin; Feng, Yanping; Wang, Chunxiao; Sun, Yingli; Lee, Don; Yan, Aru; Wu, Qiong

2017-05-01

Magnetization reversal mechanism is found to vary with cellular structures by a comparative study of the magnetization processes of three (Sm, Dy, Gd) (Co, Fe, Cu, Zr)z magnets with different cellular structures. Analysis of domain walls, initial magnetization curves and recoil loops indicates that the morphology of cellular structure has a significant effect on the magnetization process, besides the obvious connection to the difference of domain energy density between cell boundary phase (CBP) and main phase. The magnetization of Sample 2 (with a moderate cell size and uniformly continuous CBPs) behaves as a strong coherence domain-wall pinning effect to the domain wall and lead to a highest coercivity in the magnet. The magnetization of Sample 1 (with thin and discontinuous CBPs) shows an inconsistent pinning effect to the domain wall while that of Sample 3 (with thick and aggregate CBPs) exhibits a two-phase separation magnetization. Both the two cases lead to lower coercivities. A simplified model is given as well to describe the relationships among cellular structure and magnetization behavior.

500 days of SN 2013dy: spectra and photometry from the ultraviolet to the infrared

NASA Astrophysics Data System (ADS)

Pan, Y.-C.; Foley, R. J.; Kromer, M.; Fox, O. D.; Zheng, W.; Challis, P.; Clubb, K. I.; Filippenko, A. V.; Folatelli, G.; Graham, M. L.; Hillebrandt, W.; Kirshner, R. P.; Lee, W. H.; Pakmor, R.; Patat, F.; Phillips, M. M.; Pignata, G.; Röpke, F.; Seitenzahl, I.; Silverman, J. M.; Simon, J. D.; Sternberg, A.; Stritzinger, M. D.; Taubenberger, S.; Vinko, J.; Wheeler, J. C.

2015-10-01

SN 2013dy is a Type Ia supernova (SN Ia) for which we have compiled an extraordinary data set spanning from 0.1 to ˜ 500 d after explosion. We present 10 epochs of ultraviolet (UV) through near-infrared (NIR) spectra with Hubble Space Telescope/Space Telescope Imaging Spectrograph, 47 epochs of optical spectra (15 of them having high resolution), and more than 500 photometric observations in the BVrRiIZYJH bands. SN 2013dy has a broad and slowly declining light curve (Δm15(B) = 0.92 mag), shallow Si II λ 6355 absorption, and a low velocity gradient. We detect strong C II in our earliest spectra, probing unburned progenitor material in the outermost layers of the SN ejecta, but this feature fades within a few days. The UV continuum of SN 2013dy, which is strongly affected by the metal abundance of the progenitor star, suggests that SN 2013dy had a relatively high-metallicity progenitor. Examining one of the largest single set of high-resolution spectra for an SN Ia, we find no evidence of variable absorption from circumstellar material. Combining our UV spectra, NIR photometry, and high-cadence optical photometry, we construct a bolometric light curve, showing that SN 2013dy had a maximum luminosity of 10.0^{+4.8}_{-3.8} × 10^{42} erg s-1. We compare the synthetic light curves and spectra of several models to SN 2013dy, finding that SN 2013dy is in good agreement with a solar-metallicity W7 model.

Dysprosium electrodeposition from a hexaalkylguanidinium-based ionic liquid.

PubMed

Berger, Claudia A; Arkhipova, Maria; Maas, Gerhard; Jacob, Timo

2016-08-07

The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer.

Correlation of ion and beam current densities in Kaufman thrusters.

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1973-01-01

In the absence of direct impingement erosion, electrostatic thruster accelerator grid lifetime is defined by the charge exchange erosion that occurs at peak values of the ion beam current density. In order to maximize the thrust from an engine with a specified grid lifetime, the ion beam current density profile should therefore be as flat as possible. Knauer (1970) has suggested this can be achieved by establishing a radial plasma uniformity within the thruster discharge chamber; his tests with the radial field thruster provide an example of uniform plasma properties within the chamber and a flat ion beam profile occurring together. It is shown that, in particular, the ion density profile within the chamber determines the beam current density profile, and that a uniform ion density profile at the screen grid end of the discharge chamber should lead to a flat beam current density profile.

Ternary Dy-Er-Al magnetic refrigerants

DOEpatents

Gschneidner, K.A. Jr.; Takeya, Hiroyuki

1995-07-25

A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})Al{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.