Impact of vanadium ions in barium borate glass.

PubMed

Abdelghany, A M; Hammad, Ahmed H

2015-02-25

Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal effects in high average power optical parametric amplifiers.

PubMed

Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

2013-03-01

Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

Method to simulate and analyse induced stresses for laser crystal packaging technologies.

PubMed

Ribes-Pleguezuelo, Pol; Zhang, Site; Beckert, Erik; Eberhardt, Ramona; Wyrowski, Frank; Tünnermann, Andreas

2017-03-20

A method to simulate induced stresses for a laser crystal packaging technique and the consequent study of birefringent effects inside the laser cavities has been developed. The method has been implemented by thermo-mechanical simulations implemented with ANSYS 17.0. ANSYS results were later imported in VirtualLab Fusion software where input/output beams in terms of wavelengths and polarization were analysed. The study has been built in the context of a low-stress soldering technique implemented for glass or crystal optics packaging's called the solderjet bumping technique. The outcome of the analysis showed almost no difference between the input and output laser beams for the laser cavity constructed with an yttrium aluminum garnet active laser crystal, a second harmonic generator beta-barium borate, and the output laser mirror made of fused silica assembled by the low-stress solderjet bumping technique.

Photorefraction in the ultraviolet: Materials and effects

NASA Astrophysics Data System (ADS)

Laeri, F.; Jungen, R.; Angelow, G.; Vietze, U.; Engel, T.; Würtz, M.; Hilgenberg, D.

1995-10-01

Doped as well as nominally pure crystals of Lithium Niobate (LiNbO3), ι-Arginine Phosphate (LAP), Lithium Iodate (LiIO3), Potassium Dihydrogen Phosphate (KDP), Lithium Formate (LFM), Beta-Barium Borate (BBO), and lithium tetra borate were grown and investigated for photorefractive effects at ultraviolet wavelengths down to 333 nm. In nominally undoped LiNbO3 crystals strong beam coupling effects were observed. In contrast to the visible we revealed a diffusion-dominated charge transport mechanism based on holes, and a low photovoltaic field in the order of 550 V/cm. With such a crystal we investigated the modulation transfer function of a lensless image projection system based on a phase conjugation scheme. A spatial frequency response beyond 2800 line pairs per millimeter was observed. Photorefractive beam coupling was also obtained in LiIO3. Light-induced scattering was detected in iron-doped LiIO3 whereas as-grown LAP material did not exhibit any observable photorefractive effects. However, 100 kV X-ray irradiation seems to induce material defects which can lead to weak light-induced scattering at 351 nm. In all other above-mentioned materials, doped as well as undoped, light-induced scattering could not be observed. On the other hand, this is appreciated in all the applications where the crystals are used as nonlinear material for optical frequency conversion.

Ultrabright femtosecond source of biphotons based on a spatial mode inverter.

PubMed

Jarutis, Vygandas; Juodkazis, Saulius; Mizeikis, Vygantas; Sasaki, Keiji; Misawa, Hiroaki

2005-02-01

A method of enhancing the efficiency of entangled biphoton sources based on a type II femtosecond spontaneous parametric downconversion (SPDC) process is proposed and implemented experimentally. Enhancement is obtained by mode inversion of one of the SPDC output beams, which allows the beams to overlap completely, thus maximizing the number of SPDC photon pairs with optimum spatiotemporal overlap. By use of this method, biphoton count rates as high as 16 kHz from a single 0.5-mm-long beta-barium borate crystal pumped by second-harmonic radiation from a Ti:sapphire laser were obtained.

Mid-IR femtosecond frequency conversion by soliton-probe collision in phase-mismatched quadratic nonlinear crystals.

PubMed

Liu, Xing; Zhou, Binbin; Guo, Hairun; Bache, Morten

2015-08-15

We show numerically that ultrashort self-defocusing temporal solitons colliding with a weak pulsed probe in the near-IR can convert the probe to the mid-IR. A near-perfect conversion efficiency is possible for a high effective soliton order. The near-IR self-defocusing soliton can form in a quadratic nonlinear crystal (beta-barium borate) in the normal dispersion regime due to cascaded (phase-mismatched) second-harmonic generation, and the mid-IR converted wave is formed in the anomalous dispersion regime between λ=2.2-2.4  μm as a resonant dispersive wave. This process relies on nondegenerate four-wave mixing mediated by an effective negative cross-phase modulation term caused by cascaded soliton-probe sum-frequency generation.

Intensity noise cancellation in solid-state laser at 1.5  μm using SHG depletion as a buffer reservoir.

PubMed

Audo, Kevin; Alouini, Mehdi

2018-03-01

An absorption mechanism based on second-harmonic generation (SHG) is successfully implemented as a buffer reservoir in a solid-state Er,Yb:Glass laser emitting at the telecom wavelength. We show that a slight absorption mechanism based on SHG rate conversion of 0.016% using a beta barium borate crystal enables the canceling out of the excess intensity noise at the relaxation oscillation frequency, i.e., 35 dB reduction, as well as canceling the amplified spontaneous emission beating at the free spectral range resonances of the laser lying in the gigahertz range. Laser robustness is discussed.

Optical and physical properties of sodium lead barium borate glasses doped with praseodymium ion

NASA Astrophysics Data System (ADS)

Lenkennavar, Susheela K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

2018-05-01

Praseodymium doped sodium lead barium borate glasses have been prepared using single step melt quenching technique. The XRD spectrum confirms amorphous nature of glasses. The optical absorbance studies were carried out on these glasses using PekinElemer Lambda-35 Uv-Vis spectrometer in the range of 200 -1100 nm. The optical direct band gap energies were found to be in the range of 3.62 eV to 3.69 eV and indirect band gap energies were found to be in the range of 3.57 eV to 3.62eV. The refractive indices were measured by using Abbe refractometer the values are in the range of 1.620 to 1.625.

Realization of the purely spatial Einstein-Podolsky-Rosen paradox in full-field images of spontaneous parametric down-conversion

NASA Astrophysics Data System (ADS)

Moreau, Paul-Antoine; Mougin-Sisini, Joé; Devaux, Fabrice; Lantz, Eric

2012-07-01

We demonstrate Einstein-Podolsky-Rosen (EPR) entanglement by detecting purely spatial quantum correlations in the near and far fields of spontaneous parametric down-conversion generated in a type-2 beta barium borate crystal. Full-field imaging is performed in the photon-counting regime with an electron-multiplying CCD camera. The data are used without any postselection, and we obtain a violation of Heisenberg inequalities with inferred quantities taking into account all the biphoton pairs in both the near and far fields by integration on the entire two-dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position-momentum form.

Optimization of two-photon wave function in parametric down conversion by adaptive optics control of the pump radiation.

PubMed

Minozzi, M; Bonora, S; Sergienko, A V; Vallone, G; Villoresi, P

2013-02-15

We present an efficient method for optimizing the spatial profile of entangled-photon wave function produced in a spontaneous parametric down conversion process. A deformable mirror that modifies a wavefront of a 404 nm CW diode laser pump interacting with a nonlinear β-barium borate type-I crystal effectively controls the profile of the joint biphoton function. The use of a feedback signal extracted from the biphoton coincidence rate is used to achieve the optimal wavefront shape. The optimization of the two-photon coupling into two, single spatial modes for correlated detection is used for a practical demonstration of this physical principle.

Emission properties of Ce3+ centers in barium borate glasses prepared from different precursor materials

NASA Astrophysics Data System (ADS)

Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki; Ohkubo, Takahiro

2017-10-01

The photoluminescence (PL) and X-ray induced luminescence properties of Ce-doped barium borate glasses prepared from different precursor materials have been investigated. Oxidation of Ce3+ takes place during the melting process performed using a pre-vitrified non-doped glass. Residual groups originated from the precursor materials, such as fluorine atoms and OH groups, are found to affect the optical and emission properties of the glasses. Moreover, both the PL and the X-ray induced luminescence properties of the glasses depend on the precursor materials used for their synthesis. Based on a thorough analysis of the emission properties, we conclude that the best synthesis conditions involve melting a batch containing Ce(CH3COO)3·H2O, BaCO3, and B2O3 in Ar atmosphere.

Green colorants based on energetic azole borates.

PubMed

Glück, Johann; Klapötke, Thomas M; Rusan, Magdalena; Stierstorfer, Jörg

2014-11-24

The investigation of green-burning boron-based compounds as colorants in pyrotechnic formulations as alternative for barium nitrate, which is a hazard to health and to the environment, is reported. Metal-free and nitrogen-rich dihydrobis(5-aminotetrazolyl)borate salts and dihydrobis(1,3,4-triazolyl)borate salts have been synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and vibrational spectroscopy. Their thermal and energetic properties have been determined as well. Several pyrotechnic compositions using selected azolyl borate salts as green colorants were investigated. Formulations with ammonium dinitramide and ammonium nitrate as oxidizers and boron and magnesium as fuels were tested. The burn time, dominant wavelength, spectral purity, luminous intensity, and luminous efficiency as well as the thermal and energetic properties of these compositions were measured. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-magnification super-resolution FINCH microscopy using birefringent crystal lens interferometers

NASA Astrophysics Data System (ADS)

Siegel, Nisan; Lupashin, Vladimir; Storrie, Brian; Brooker, Gary

2016-12-01

Fresnel incoherent correlation holography (FINCH) microscopy is a promising approach for high-resolution biological imaging but has so far been limited to use with low-magnification, low-numerical-aperture configurations. We report the use of in-line incoherent interferometers made from uniaxial birefringent α-barium borate (α-BBO) or calcite crystals that overcome the aberrations and distortions present with previous implementations that employed spatial light modulators or gradient refractive index lenses. FINCH microscopy incorporating these birefringent elements and high-numerical-aperture oil immersion objectives could outperform standard wide-field fluorescence microscopy, with, for example, a 149 nm lateral point spread function at a wavelength of 590 nm. Enhanced resolution was confirmed with sub-resolution fluorescent beads. Taking the Golgi apparatus as a biological example, three different proteins labelled with GFP and two other fluorescent dyes in HeLa cells were resolved with an image quality that is comparable to similar samples captured by structured illumination microscopy.

Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

DOEpatents

Gruen, Dieter M.

2000-01-01

A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

Growth and characterization of a novel nonlinear optical borate crystal - Yttrium calcium borate (YCB)

NASA Astrophysics Data System (ADS)

Arun Kumar, R.; Arivanandhan, M.; Dhanasekaran, R.; Hayakawa, Y.

2013-06-01

A new nonlinear optical single crystal yttrium calcium borate Y2CaB10O19 (YCB) was grown for the first time from its melt. The starting materials were prepared by the solid-state reaction method. The melting point of the synthesized material was identified to be 967 °C. YCB crystal exhibits monoclinic crystal structure with the space group C2. The crystalline perfection of the grown YCB crystal was found to be good. From the UV-VIS-NIR studies, the lower cutoff wavelength of the crystal occurs below 200 nm. The functional groups of the grown crystal were assigned using the FTIR data. The second harmonic generation (SHG) of the YCB crystal was observed using a Nd:YAG laser with a fundamental wavelength of 1064 nm. The laser damage threshold value of the YCB crystal was found to be very high - 10.5 GW/cm2.

Characterization of Barium Borate Frameworks Using Raman Spectroscopy.

PubMed

Gharavi-Naeini, Jafar; Yoo, Kyung W; Stump, Nathan A

2018-04-01

Systematic micro-Raman scattering investigations have been carried out on Sm +2 doped 2(BaO)-n(B 2 O 3 ) matrices for n = 4, 5, 8, and 2(BaO)-(Na 2 O)-9(B 2 O 3 ) using the 364 nm excitation of an Ar + laser. The Raman results have been compared with the known structures of barium tetraborate, barium pentaborate, barium octaborate, and barium sodium nonaborate. An excellent correlation has been found between the BO 4 /BO 3 composition ratios for each product and intensity ratios of the designated BO 4 and BO 3 Raman peaks. Furthermore, the Raman frequencies of both BO 4 and BO 3 groups undergo a systematic blueshift as n increases from four to nine. The shift results from a decrease of the B-O bond lengths for both BO 4 and BO 3 groups as the samples transition from the tetraborate to nonaborate structures. Linear relations (with negative slopes) have been determined between the measured Raman frequencies and B-O bond lengths in the frameworks.

Effect of zinc-borate glass addition on the thermal properties of the cordierite/Al2O3 composites containing nano-sized spinel crystal.

PubMed

Jo, Sinae; Kang, Seunggu

2013-11-01

Low-melting zinc-borate glass was added to the cordierite/Al2O3 composite in order to improve the sintering facility of Al2O3 and formation of nano-sized spinel crystal of high thermal conductivity. Increasing the ZnO/B2O3 ratio in the zinc-borate glass increased the ZnAl2O4 spinel and decreased the Al4B2O9 crystal peak intensities in X-ray diffraction pattern. The XRD peak intensities of the ZnAl2O4 spinel and Al4B2O9 crystals in the specimen containing 10 wt% zinc-borate glass (10G series) are higher than that of the specimen containing 5 wt% zinc-borate glass (5G series). The microstructures of most 10G series specimens had the flower-shaped crystal which was composed of 50 nm wide and 250 nm long needle-like crystals and identified as ZnAl2O4 spinel phase. The thermal conductivity of the 10G series specimen was higher than that of the 5G series in any ZnO/B2O3 ratio due to the formation of plenty of nano-sized ZnAl2O4 spinel of high thermal conductivity. Particularly, the thermal conductivity of the cordierite/Al2O3 composite containing 10 wt% zinc-borate glass of ZnO/B2O3 weight ratio = 1.5 was 3.8 W/Km which is much higher than that of the published value (3.0 W/Km).

A crystal-chemical classification of borate structures with emphasis on hydrated borates

USGS Publications Warehouse

Christ, C.L.; Clark, J.R.

1977-01-01

The rules governing formation of hydrated borate polyanions that were proposed by C.L. Christ in 1960 are critically reviewed and new rules added on the basis of recent crystal structure determinations. Principles and classifications previously published by others are also critically reviewed briefly. The fundamental building blocks from which borate polyanions can be constructed are defined on the basis of the number n of boron atoms, and the fully hydrated polyanions are illustrated. Known structures are grouped accordingly, and a shorthand notation using n and symbols ?? = triangle, T = tetrahedron is introduced so that the polyanions can be easily characterized. For example, 3:??+2T describes [B3O3(OH)5]2-. Correct structural formulas are assigned borates with known structures whereas borates of unknown structure are grouped separately. ?? 1977 Springer-Verlag.

Waveguide structures in anisotropic nonlinear crystals

NASA Astrophysics Data System (ADS)

Li, Da; Hong, Pengda; Meissner, Helmuth E.

2017-02-01

We report on the design and manufacturing parameters of waveguiding structures of anisotropic nonlinear crystals that are employed for harmonic conversions, using Adhesive-Free Bonding (AFB®). This technology enables a full range of predetermined refractive index differences that are essential for the design of single mode or low-mode propagation with high efficiency in anisotropic nonlinear crystals which in turn results in compact frequency conversion systems. Examples of nonlinear optical waveguides include periodically bonded walk-off corrected nonlinear optical waveguides and periodically poled waveguide components, such as lithium triborate (LBO), beta barium borate (β-BBO), lithium niobate (LN), potassium titanyl phosphate (KTP), zinc germanium phosphide (ZGP) and silver selenogallate (AGSE). Simulation of planar LN waveguide shows that when the electric field vector E lies in the k-c plane, the power flow is directed precisely along the propagation direction, demonstrating waveguiding effect in the planar waveguide. Employment of anisotropic nonlinear optical waveguides, for example in combination with AFB® crystalline fiber waveguides (CFW), provides access to the design of a number of novel high power and high efficiency light sources spanning the range of wavelengths from deep ultraviolet (as short as 200 nm) to mid-infrared (as long as about 18 μm). To our knowledge, the technique is the only generally applicable one because most often there are no compatible cladding crystals available to nonlinear optical cores, especially not with an engineer-able refractive index difference and large mode area.

Self-assembled 3D zinc borate florets via surfactant assisted synthesis under moderate pressures: Process temperature dependent morphology study

NASA Astrophysics Data System (ADS)

Mahajan, Dhiraj S.; Deshpande, Tushar; Bari, Mahendra L.; Patil, Ujwal D.; Narkhede, Jitendra S.

2018-04-01

In the present study, we prepared zinc borates using aqueous phase synthesis under moderate pressures (MP) (<150 psi) with ethanol as a co-solvent in the presence of a quaternary ammonium surfactant-Cetyltrimethylammonium bromide (CTAB). 3D morphologies of self-assembled zinc borate (Zn(H2O)B2O4 · 0.12 H2O, Zn3B6O12 · 3.5H2O, ZnB2O4) resembling flower-like structures were obtained by varying temperature under moderate pressure conditions. Synthesized zinc borates’ florets were morphologically characterized by Field Emission Scanning Electron Microscopy. The x-ray diffractions of borate species reveal rhombohydra, monoclinic and cubic phases of zinc borate crystals as a function of process temperature. Additionally, thermal analysis confirms excellent dehydration/degradation behavior for the zinc borate crystals synthesized at moderate pressures and elevated temperatures and could be utilized as potential flame retardant fillers in the polymer matrices.

Investigation of inorganic nonlinear optical potassium penta borate tetra hydrate (PPBTH) single crystals grown by slow evaporation method

NASA Astrophysics Data System (ADS)

Arivuselvi, R.; Babu, P. Ramesh

2018-03-01

Borates family crystals were plays vital role in the field of non linear optics (NLO) due to needs of wide range of applications. In this report, NLO crystals (potassium penta borate tetra hydrate (KB5H8O12) are grown by slow evaporation method at room temperature (28° C) and studied their physical properties. The harvested single crystals are transparent with the dimension of 12 × 10 × 6 mm3 and colourless. X-ray diffraction of single crystals reveals that the grown crystal belongs to orthorhombic system with non-centrosymmetric space group Pba2. All the absorbed functional groups are present in the order of inorganic compounds expect 1688 cm-1 because of water (Osbnd H sbnd O blending) molecule present in the pristine. Crystals show transparent in the entire visible region with 5.9 eV optical band gap and also it shows excellence in both second and third order nonlinear optical properties. Crystals can withstand upto 154 °C without any phase changes which is observed using thermal (TGA/DTA) analysis.

Ytterbium-doped borate fluoride laser crystals and lasers

DOEpatents

Schaffers, Kathleen I.; DeLoach, Laura D.; Payne, Stephen A.; Keszler, Douglas A.

1997-01-01

A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

High-Q BBO whispering gallery mode resonators

NASA Astrophysics Data System (ADS)

Lin, Guoping; Fürst, Josef U.; Strekalov, Dmitry V.; Grudinin, Ivan S.; Yu, Nan

2013-02-01

We report an investigation on optical whispering gallery mode (WGM) resonators made from non z-cut beta barium borate (BBO) crystals. We first fabricated high quality (Q) factor WGM resonators made of an angle-cut BBO crystal. Q factors of 1×108 level have been demonstrated at various wavelengths including UV. They led to new upper bounds for the absorption coefficients of BBO at 1560 nm, 980 nm and 370 nm. We observed only one set of ordinarily polarized WGMs with polarization rotating along the resonator circumference. We also fabricated xy-cut BBO WGM resonators, in which the optic axis is parallel to the resonator plane. In that case, two WGM families with different polarization exist, one with constant the other with oscillatory phase velocity. This enables a novel way of broadband phase matching in WGM resonators with cyclic gain. We experimentally demonstrated efficient second harmonic generation (SHG) to a wide harmonic wavelength range from 780 nm at near infrared to 317 nm in UV. It is also the first reported direct UV SHG in a high-Q WGM resonator. This work lays a foundation for further investigations of WGM properties of non-z cut birefringent resonators and their applications in nonlinear optics.

New insight in the nature of surface magnetic anisotropy in iron borate

NASA Astrophysics Data System (ADS)

Strugatsky, M.; Seleznyova, K.; Zubov, V.; Kliava, J.

2018-02-01

The theory of surface magnetism of iron borate, FeBO3, has been extended by taking into consideration a crystal field contribution to the surface magnetic anisotropy energy. For this purpose, a model of distortion of the six-fold oxygen environment of iron ions in the near-surface layer of iron borate has been put forward. The spin Hamiltonian parameters for isolated Fe3+ ions in the distorted environment of the near-surface layer have been calculated using the Newman's superposition model. The crystal field contribution to the surface magnetic anisotropy energy has been calculated in the framework of the perturbation theory. The model developed allows concluding that the distortions of the iron environment produce a significant crystal field contribution to the surface magnetic anisotropy constant. The results of experimental studies of the surface magnetic anisotropy in iron borate can be described assuming the existence of relative contractions in the near-surface layer of the order of 1 %.

Growth and characterization of high-performance photorefractive BaTiO3 crystals

NASA Technical Reports Server (NTRS)

Warde, C.; Garrett, M. H.; Chang, J. Y.; Jenssen, H. P.; Tuller, H. L.

1991-01-01

Barium titanate has been used for many nonlinear optical applications primarily because it has high grain and high self-pumped phase conjugate reflectivities. However, barium titanate has had a relatively slow response time, and thus low sensitivity. Therefore, it has not been suited to real-time operations. In this report we will describe the modifications in crystal growth, doping, reduction, and poling that have produced barium titanate crystals with the fastest photorefractive response time reported to date, approximately 21 microseconds with a beam-coupling gain coefficient of 38.7 cm(exp -1) and the highest sensitivity reported to date of 3.44 cm(exp 3)/kJ. The sensitivity of these barium titanate crystals is comparable to or greater than other photorefractive oxides. We will show, for the first time, beam-coupling in barium titanate at video frame rates. We infer from response time measurements that barium titanate has a phonon limited mobility. Also, photorefractive response time measurements as a function of the crystallographic orientation and grating wave vector for our cobalt-doped oxygen reduced crystals indicate that their faster response time arise because of an increase in the free carrier lifetime.

The molecular structure of the borate mineral rhodizite (K, Cs)Al4Be4(B, Be)12O28 - A vibrational spectroscopic study

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Xi, Yunfei; Scholz, Ricardo; Souza, Larissa; Lana, Cristiano

2014-07-01

We have studied the borate mineral rhodizite (K, Cs)Al4Be4(B, Be)12O28 using a combination of DEM with EDX and vibrational spectroscopic techniques. The mineral occurs as colorless, gray, yellow to white crystals in the triclinic crystal system. The studied sample is from the Antandrokomby Mine, Sahatany valley, Madagascar. The mineral is prized as a semi-precious jewel. Semi-quantitative chemical composition shows a Al, Ca, borate with minor amounts of K, Mg and Cs. The mineral has a characteristic borate Raman spectrum and bands are assigned to the stretching and bending modes of B, Be and Al. No Raman bands in the OH stretching region were observed.

Improved synthesis of fine zinc borate particles using seed crystals

NASA Astrophysics Data System (ADS)

Gürhan, Deniz; Çakal, Gaye Ö.; Eroğlu, İnci; Özkar, Saim

2009-03-01

Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical compositions and structures. In this study, the production of zinc borate having the molecular formula of 2ZnO·3B 2O 3·3.5H 2O was reexamined by studying the effects of reaction parameters on the properties of product as well as the reaction kinetics. Production of zinc borate from the reaction of boric acid and zinc oxide in the presence of seed crystals was performed in a continuously stirred, temperature-controlled batch reactor having a volume of 1.5 L. Samples taken in regular time intervals during the experiments were analyzed for the concentration of zinc oxide and boron oxide in the solid as well as for the conversion of zinc oxide to zinc borate versus time. The zinc borate production reaction was fit to the logistic model. The reaction rate, reaction completion time, composition and particle size distribution of zinc borate product were determined by varying the following parameters: the boric acid to zinc oxide ratio (H 3BO 3:ZnO=3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10 and 25 μm), stirring rate (275, 400, 800 and 1600 rpm), temperature (75, 85 and 95 °C) and the size of seed crystals (10 and 2 μm). The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increases with the increase in H 3BO 3:ZnO ratio, particle size of zinc oxide, stirring rate and temperature. Concomitantly, the reaction completion time is decreased by increasing the H 3BO 3:ZnO ratio, stirring rate and temperature. The average particle sizes of the zinc borate products are in the range 4.3-16.6 μm (wet dispersion analysis).

Ytterbium-doped borate fluoride laser crystals and lasers

DOEpatents

Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.; Keszler, D.A.

1997-10-14

A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM{prime}(BO{sub 3})F, where M, M{prime} are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO{sub 3}F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator. 6 figs.

Turnable Blue-Green LIDAR Transmitter Demonstration: Injection Laser Technology

DTIC Science & Technology

1990-08-30

5-1 5.2 Baseline Requirements ............................................. 5-1 5.3 Optical Parametric Oscillator Using Beta Barium Borate... optical parametric oscillators , and organic dye lasers. Tunable solid state lasers such as Ti: sapphire operate in the infrared and would have to be...The same is true of I frequency mixing schemes. Optical parametric oscillators (OPOs) are attractive because of their extremely wide potential tuning

SAD phasing with in-house cu Ka radiation using barium as anomalous scatterer.

PubMed

Dhanasekaran, V; Velmurugan, D

2011-12-01

Phasing of lysozyme crystals using co-crystallized barium ions was performed using single-wavelength anomalous diffraction (SAD) method using Cu Ka radiation with in-house source of data collection. As the ion binding sites vary with respect to the pH of the buffer during crystallization, the highly isomorphic forms of lysozyme crystals grown at acidic and alkaline pH were used for the study. Intrinsic sulphur anomalous signal was also utilized with anomalous signal from lower occupancy ions for phasing. The study showed that to solve the structure by SAD technique, 2.8-fold data redundancy was sufficient when barium was used as an anomalous marker in the in-house copper X-ray radiation source for data collection. Therefore, co-crystallization of proteins with barium containing salt can be a powerful tool for structure determination using lab source.

The molecular structure of the borate mineral rhodizite (K, Cs)Al4Be4(B, Be)12O28--a vibrational spectroscopic study.

PubMed

Frost, Ray L; López, Andrés; Xi, Yunfei; Scholz, Ricardo; Souza, Larissa; Lana, Cristiano

2014-07-15

We have studied the borate mineral rhodizite (K, Cs)Al4Be4(B, Be)12O28 using a combination of DEM with EDX and vibrational spectroscopic techniques. The mineral occurs as colorless, gray, yellow to white crystals in the triclinic crystal system. The studied sample is from the Antandrokomby Mine, Sahatany valley, Madagascar. The mineral is prized as a semi-precious jewel. Semi-quantitative chemical composition shows a Al, Ca, borate with minor amounts of K, Mg and Cs. The mineral has a characteristic borate Raman spectrum and bands are assigned to the stretching and bending modes of B, Be and Al. No Raman bands in the OH stretching region were observed. Copyright © 2014 Elsevier B.V. All rights reserved.

The preparation and characterization of a lithium borate glass prepared by the gel technique

NASA Technical Reports Server (NTRS)

Weinberg, M. C.; Neilson, G. F.; Smith, G. L.; Dunn, B.; Moore, G. S.; Mackenzie, J. D.

1985-01-01

The preparation of an amorphous lithium borate gel by the metal organic procedure is described. In addition, a preliminary evaluation of the behavior of the gel upon heating is given. In particular the crystallization tendency of the gel is studied with the aid of DTA and X-ray diffraction, and the structural changes in the gel are monitored with the aid of IR spectroscopy. The glass produced from the lithium borate gel is compared to both the gel precursor material and a glass of similar composition prepared by conventional techniques. Specifically, the relevant water contents, crystallization behavior, and structural features are contrasted.

Crystal chemistry and structure refinement of five hydrated calcium borates

USGS Publications Warehouse

Clark, J.R.; Appleman, D.E.; Christ, C.L.

1964-01-01

The crystal structures of the five known members of the series Ca2B6O11??xH2O (x = 1, 5, 5, 7, 9, and 13) have been refined by full-matrix least-squares techniques, yielding bond distances and angles with standard errors of less than 0??01 A?? and 0??5??, respectively. The results illustrate the crystal chemical principles that govern the structures of hydrated borate compounds. The importance of hydrogen bonding in the ferroelectric transition of colemanite is confirmed by more accurate proton assignments. ?? 1964.

Luminescence study and CIE diagram of certain alkaline sodium lead borate glass for LED applications

NASA Astrophysics Data System (ADS)

Lenkennavar, S. K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

2018-04-01

In the present work, the glass composition 20Na2O -10PbO-10MO -60B2O3 doped with Praseodymium ions have been synthesised using muffle furnace by the conventional melt quenching technique and the effect of Pr3+ ions on optical properties of present glasses have been examined. The emission spectra were recorded in the wavelength range of 450-750nm upon excitation at 450 and 550nm. The Commission International deI'Eclairage (CIE) chromaticity coordinates are determined to estimate the emission colour of the Pr3+ incorporated barium/calcium/strontium sodium lead borate glasses. It is observed that blue LED and red LED applications can be expected by tuning the excitation wavelength applied to the same glass matrices.

Growth of new borate crystals with fiber shape by the micro-pulling down technique

NASA Astrophysics Data System (ADS)

Assi, Farah; Ferriol, Michel; Aillerie, Michel; Cochez, Marianne

2017-07-01

Borate-based materials are of high interest to generate an UV laser light from a crystal. Fiber-shaped crystals combining the advantages of fiber lasers and crystalline lasers, we have investigated the growing conditions required to obtain usable fibers of Bi2ZnB2O7 (BZBO) and LaBGeO5 (LBGO). For BZBO, the major drawback was the pronounced color of the fibers and for LBGO, it was the high viscosity of its melt leading to use a flux. This paper presents our state of the art to obtain good quality BZBO and LBGO crystal fibers.

Selections From Kung-Jen JIH-PAO (Source Span: 9 May-30 June 1961) Number 7 -Communist China.

DTIC Science & Technology

1961-08-17

sulphate Ammonium hydrogen carbonate Sodium borate Titaniüm-iron powder Sodium fluoride Silicon dioxide Barium chloride beryllium carbonate ...Vinzenstrasse, 22a :■ P. 0. Box 3521 Aachen, Germany Washington 7> B.C. , Institute de Sociologie Solvay Rue du Chatelain, k9 Brussels, Belgium State... Sodium nitrite Specifications Pure n industrial Boric Acid " A^ua ammonia " Magnesium sulphate Industrial Manganese tedroxide Pure

Photonic crystal borax competitive binding carbohydrate sensing motif†

PubMed Central

Cui, Qingzhou; Muscatello, Michelle M. Ward; Asher, Sanford A.

2009-01-01

We developed a photonic crystal sensing method for diol containing species such as carbohydrates based on a poly(vinyl alcohol) (PVA) hydrogel containing an embedded crystalline colloidal array (CCA). The polymerized CCA (PCCA) diffracts visible light. We show that in the presence of borax the diffraction wavelength shifts as the concentration of glucose changes. The diffraction shifts result from the competitive binding of glucose to borate, which reduces the concentration of borate bound to the PVA diols. PMID:19381378

Crystallization of lithium borate glasses

NASA Technical Reports Server (NTRS)

Goktas, A. A.; Neilson, G. F.; Weinberg, M. C.

1992-01-01

The glass-forming ability and crystallization behavior of lithium borate compositions, in the diborate-to-metaborate-range, were studied. In particular, the nature and sequence of formation of crystalline phases and the tendency toward devitrification were investigated as functions of temperature, thermal history and batch composition. It was found that the sequence of crystalline phase formation was sensitive to all of the three latter factors, and it was observed that under certain conditions metastable defect structures of the metaborate can appear.

Preliminary experiments on phase conjugation for flow visualization. [barium titanate single crystals

NASA Technical Reports Server (NTRS)

Weimer, D.; Howes, W. L.

1984-01-01

Barium titanate single crystals are discussed in the context of: the procedure for polarizing a crystal; a test for phase conjugation; transients in the production of phase conjugation; real time readout by a separate laser of a hologram induced within the crystal, including conjugation response times to on-off switching of each beam; and a demonstration of a Twyman-Green interferometer utilizing phase conjugation.

Study on improving the heat storage property of Ba(OH)2·8H2O with paraffin

NASA Astrophysics Data System (ADS)

Cui, Kaixuan; Liu, Liqiang; Sun, Mingjie

2017-12-01

Barium hydroxide octahydrate is the crystalline hydration salt with the highest latent heat density within the phase change temperature interval of 0-120 °C and it has a broad application prospect as a phase-change material (PCM). Firstly, red copper test tube was used for the melting—solidification heat cycle experiment in this paper, which was verified by the corrosion experiment of barium hydroxide solution. After the thermogravimetric analysis, it is found that paraffin can effectively reduce the evaporation escape of barium hydroxide octahydrate crystal water within 100 °C. Repeated heat cycle experiments indicated that the paraffin with larger coverage mass fraction can reduce the inhibiting effect of barium hydroxide octahydrate crystal water more obviously. X-ray diffraction analysis indicated that the phase composition of the barium hydroxide octahydrate sample covered with 50 wt% paraffin nearly had no change, while the sample not covered with paraffin has the weight loss ratio of 34.67% and reacted with CO2 in the air, generating BaCO3. In summary, paraffin can not only inhibit the evaporation of crystal water, but also effectively isolate the air to prevent barium hydroxide octahydrate from denaturation. This greatly improved the practicability of barium hydroxide octahydrate as a PCM, laying a good foundation for the further application of barium hydroxide octahydrate.

High-capacity quantum secure direct communication with two-photon six-qubit hyperentangled states

NASA Astrophysics Data System (ADS)

Wu, FangZhou; Yang, GuoJian; Wang, HaiBo; Xiong, Jun; Alzahrani, Faris; Hobiny, Aatef; Deng, FuGuo

2017-12-01

This study proposes the first high-capacity quantum secure direct communication (QSDC) with two-photon six-qubit hyper-entangled Bell states in two longitudinal momentum and polarization degrees of freedom (DOFs) of photon pairs, which can be generated using two 0.5 mm-thick type-I β barium borate crystal slabs aligned one behind the other and an eight-hole screen. The secret message can be independently encoded on the photon pairs with 64 unitary operations in all three DOFs. This protocol has a higher capacity than previous QSDC protocols because each photon pair can carry 6 bits of information, not just 2 or 4 bits. Our QSDC protocol decreases the influence of decoherence from environment noise by exploiting the decoy photons to check the security of the transmission of the first photon sequence. Compared with two-way QSDC protocols, our QSDC protocol is immune to an attack by an eavesdropper using Trojan horse attack strategies because it is a one-way quantum communication. The QSDC protocol has good applications in the future quantum communication because of all these features.

Barium recovery by crystallization in a fluidized-bed reactor: effects of pH, Ba/P molar ratio and seed.

PubMed

Su, Chia-Chi; Reano, Resmond L; Dalida, Maria Lourdes P; Lu, Ming-Chun

2014-06-01

The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO₄ crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR. Experimental results show that an upward velocity of 48 cmmin(-1) produced the largest BaHPO₄ crystals with a size of around 0.84-1.0mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseeded<0.149-0.29 mm<0.149 mm<0.29-0.42 mm produced increasing amounts of increasingly large crystals. The largest BaHPO₄ crystals were obtained at pH 8.4-8.8 with a Ba/P molar ratio of 1.0. In the homogeneous and heterogeneous processes, around 98% of barium was removed at pH 8.4-8.6 and [Ba]/[P]=1.0. The XRD results show that a significant amount of barium phosphate (Ba₃(PO₄)₂) was obtained at pH 11. The compounds BaHPO₄ and BaO were present at a pH of below 10. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

Raman and Infrared Spectroscopy of Yttrium Aluminum Borate Glasses and Glass-ceramics

NASA Technical Reports Server (NTRS)

Bradley, J.; Brooks, M.; Crenshaw, T.; Morris, A.; Chattopadhyay, K.; Morgan, S.

1998-01-01

Raman spectra of glasses and glass-ceramics in the Y2O3-Al2O3-B2O3 system are reported. Glasses with B2O3 contents ranging from 40 to 60 mole percent were prepared by melting 20 g of the appropriate oxide or carbonate powders in alumina crucibles at 1400 C for 45 minutes. Subsequent heat treatments of the glasses at temperatures ranging from 600 to 800 C were performed in order to induce nucleation and crystallization. It was found that Na2CO3 added to the melt served as a nucleating agent and resulted in uniform bulk crystallization. The Raman spectra of the glasses are interpreted primarily in terms of vibrations of boron - oxygen structural groups. Comparison of the Raman spectra of the glass-ceramic samples with spectra of aluminate and borate crystalline materials reveal that these glasses crystallize primarily as yttrium aluminum borate, YAl3(BO3)4.

Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification.

PubMed

Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F

2014-07-28

The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed.

High-power 266 nm ultraviolet generation in yttrium aluminum borate.

PubMed

Liu, Qiang; Yan, Xingpeng; Gong, Mali; Liu, Hua; Zhang, Ge; Ye, Ning

2011-07-15

A yttrium aluminum borate [YAl(3)(BO(3))(4)] (YAB) crystal with UV cutoff wavelength of 165 nm is used as the nonlinear optical crystal for fourth harmonic generation. The fundamental frequency laser at 1064 nm from an Nd:YVO(4) master oscillator power amplifier laser was frequency doubled to 532 nm. Using the type I phase-matching YAB crystal, a 5.05 W average power 266 nm UV laser was obtained at the pulse repetition frequency of 65 kHz, corresponding to the conversion efficiency of 12.3% from 532 to 266 nm. The experimental results show great potential for the application of using YAB as a nonlinear optical crystal to get high-power fourth harmonic generation. © 2011 Optical Society of America

Phase transition studies in barium and strontium titanates at microwave frequencies

NASA Technical Reports Server (NTRS)

Dahiya, Jai N.

1993-01-01

The objectives were the following: to understand the phase transformations in barium and strontium titanates as the crystals go from one temperature to the other; and to study the dielectric behavior of barium and strontium titanate crystals at a microwave frequency of 9.12 GHz and as a function of temperature. Phase transition studies in barium and strontium titanate are conducted using a cylindrical microwave resonant cavity as a probe. The cavity technique is quite successful in establishing the phase changes in these crystals. It appears that dipole relaxation plays an important role in the behavior of the dielectric response of the medium loading the cavity as phase change takes place within the sample. The method of a loaded resonant microwave cavity as applied in this work has proven to be sensitive enough to monitor small phase changes of the cavity medium.

Effect of chloride incorporation on the crystallization of zirconium-barium-lanthanum-aluminum fluoride glass

NASA Technical Reports Server (NTRS)

Neilson, G. F.; Smith, G. L.; Weinberg, M. C.

1985-01-01

One aspect of the influence of preparation procedure on the crystallization behavior of a zirconium-barium-lanthanum-aluminum fluoride glass was studied. The crystallization pattern of this glass may be affected by the chlorine concentration within it. In particular, when such glasses are heated at low temperatures, the alpha-Ba-Zr-F6 crystalline phase forms only in those glasses which contain chloride.

Analysis of barium and strontium in sediments by dc plasma emission spectrometry

USGS Publications Warehouse

Bowker, P.C.; Manheim, F. T.

1982-01-01

The dc plasma are is suited to analysis of barium and strontium in a wide range of sedimentary rock matrices, from sands, shales, and carbonates, to ferromanganese nodules. Samples containing 10 ppm to more than 3000 ppm barium and strontium were studied. Both alkali (3500 ppm lithium borate, from a preliminary fusion) and lanthanum salts (1%) in the final solution are needed to achieve freedom from systematic effects due to extreme variation in matrix. In the absence of La, neither Li, Na, K, nor Cs totally eliminated effects of Al and other constituents on emission. Silica addition to the fusion helps achieve proper flux viscosity to aid removal of fused beads from graphite crucibles. The effect of refractory-substance formers such as aluminum with calcium can be reduced or removed by selection of a portion of the are for emission measurement. However, it was decided not to pursue this approach because of loss in analytical sensitivity and need for greater precision in optical adjustment. Analysis of standard rock samples showed generally satisfactory agreement with precision methods of analysis, and some new standard rock data are reported.

Effect of certain alkaline metals on Pr doped glasses to investigate spectroscopic studies

NASA Astrophysics Data System (ADS)

Lenkennavar Susheela, K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

2018-02-01

Incorporation of different Alkaline earth metal like Barium, Calcium and strontium in sodium lead borate glass doped with Pr3+ is studied. Physical parameters such as density, molar volume, molar refractivity etc have been evaluated. Effect of different atomic size of alkaline metal using optical and physical parameters is analysed. XRD and FTIR were carried out to know the structural behaviour of the glasses. Absorption and Emission spectra are recorded at room temperature and the results were discussed.

A Compact Ti:Sapphire Laser With its Third Harmonic Generation (THG) for an Airborne Ozone Differential Absorption Lidar (DIAL) Transmitter

NASA Technical Reports Server (NTRS)

Chen, Songsheng; Storm, Mark E.; Marsh, Waverly D.; Petway, Larry B.; Edwards, William C.; Barnes, James C.

2000-01-01

A compact and high-pulse-energy Ti:Sapphire laser with its Third Harmonic Generation (THG) has been developed for an airborne ozone differential absorption lidar (DIAL) to study the distributions and concentrations of the ozone throughout the troposphere. The Ti:Sapphire laser, pumped by a frequency-doubled Nd:YAG laser and seeded by a single mode diode laser, is operated either at 867 nm or at 900 nm with a pulse repetition frequency of 20 Hz. High energy laser pulses (more than 110 mJ/pulse) at 867 nm or 900 nm with a desired beam quality have been achieved and utilized to generate its third harmonic at 289nm or 300nm, which are on-line and off-line wavelengths of an airborne ozone DIAL. After being experimentally compared with Beta-Barium Borate (beta - BaB2O4 or BBO) nonlinear crystals, two Lithium Triborate (LBO) crystals (5 x 5 x 20 cu mm) are selected for the Third Harmonic Generation (THG). In this paper, we report the Ti:Sapphire laser at 900 nm and its third harmonic at 300 nm. The desired high ultraviolet (UV) output pulse energy is more than 30 mJ at 300 nm and the energy conversion efficiency from 900 nm to 300 nm is 30%.

High-Pressure Synthesis and Characterization of the Ammonium Yttrium Borate (NH4)YB8O14.

PubMed

Schmitt, Martin K; Podewitz, Maren; Liedl, Klaus R; Huppertz, Hubert

2017-11-20

The first high-pressure yttrium borate (NH 4 )YB 8 O 14 was synthesized at 12.8 GPa/1300 °C using a Walker-type multianvil module. The compound crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 17.6375(9), b = 10.7160(5), and c = 4.2191(2) Å. (NH 4 )YB 8 O 14 constitutes a novel structure type but exhibits similarities to the crystal structure of β-BaB 4 O 7 . X-ray single-crystal and powder diffraction, EDX, vibrational spectroscopy as well as quantum chemical calculations were used to characterize (NH 4 )YB 8 O 14 .

The new silver borate Ag{sub 3}B{sub 5}O{sub 9}

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

Sohr, Gerhard; Falkowski, Viktoria; Huppertz, Hubert, E-mail: hubert.huppertz@uibk.ac.at

2015-05-15

Single crystals of Ag{sub 3}B{sub 5}O{sub 9} were obtained via high-pressure synthesis at 3 GPa and 600 °C, using a Walker-type multianvil high-pressure device. Ag{sub 3}B{sub 5}O{sub 9} crystalizes with a=674.7(2), b=943.5(2), c=1103.5(2) pm, V=0.7025(2) nm{sup 3}, and Z=4 in the noncentrosymmetric space group P2{sub 1}2{sub 1}2{sub 1} (no. 19). The orthorhombic structure was refined from 3740 independent reflections with R1=0.0496 and wR2=0.587 (all data). It is built up from infinite corner-sharing chains of BO{sub 4} tetrahedra along the a axis, which are interconnected by BO{sub 3} groups to form a network. In the structure, three crystallographically independent sites aremore » occupied with Ag{sup +} cations exhibiting argentophillic interactions. The synthetic conditions as well as the results of the single crystal structure analysis are presented. - Graphical abstract: Noncentrosymmetric silver borate: During investigations in the system Ag–B–O, a new noncentrosymmetric silver borate Ag{sub 3}B{sub 5}O{sub 9} was discovered. The new structure type is built up from corner-sharing BO{sub 3} and BO{sub 4} groups, forming a network. Argentophillic interactions are clearly indicated by the Ag{sup +}⋯Ag{sup +} distances present in the structure. - Highlights: • A noncentrosymmetric borate Ag{sub 3}B{sub 5}O{sub 9} is accessible via high-pressure synthesis. • Ag{sub 3}B{sub 5}O{sub 9} is the second high-pressure silver borate. • Ag{sup +}⋯Ag{sup +} distances in Ag3B5O9 clearly indicate the presence of argentophillic interactions.« less

N-Alkyl-N-methylpyrrolidinium Difluoro(oxalato)borate Ionic Liquids: Physical/Electrochemical Properties and Al Corrosion

DTIC Science & Technology

2013-01-01

U.S. Army Research Laboratory, Adelphi, MD 20783, USA The synthesis and physical properties of difluoro(oxalato) borate (DFOB-)-based ionic...have a melting point (Tm) of -5°C and 31°C, respectively, whereas the PY15DFOB salt does not crystallize. Instead, this salt has a glass transition

Vibrational spectroscopy of the borate mineral tunellite SrB6O9(OH)2·3(H2O) - Implications for the molecular structure

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Scholz, Ricardo; Xi, Yunfei

2014-02-01

Tunellite is a strontium borate mineral with formula: SrB6O9(OH)2·3(H2O) and occurs as colorless crystals in the monoclinic pyramidal crystal system. An intense Raman band at 994 cm-1 was assigned to the BO stretching vibration of the B2O3 units. Raman bands at 1043, 1063, 1082 and 1113 cm-1 are attributed to the in-plane bending vibrations of trigonal boron. Sharp Raman bands observed at 464, 480, 523, 568 and 639 cm-1 are simply defined as trigonal and tetrahedral borate bending modes. The Raman spectrum clearly shows intense Raman bands at 3567 and 3614 cm-1, attributed to OH units. The molecular structure of a natural tunellite has been assessed by using vibrational spectroscopy.

Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

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

Jin Yi; Zhu Yihua; Yang Xiaoling

Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allowsmore » one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices. - Graphical abstract: Cerium-doped barium titanate inverted opal was synthesized from barium acetate acid contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a PS opal, which involves infiltration of precursors into the interstices of the PS opal template and removal of the PS opal by calcination.« less

Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba11B26O44(PO4)2(OH)6, Li9BaB15O27(CO3) and Ba3Si2B6O16

NASA Astrophysics Data System (ADS)

Heyward, Carla; McMillen, Colin D.; Kolis, Joseph

2013-07-01

Several new borate compounds, Ba11B26O44(PO4)2(OH)6 (1), Li9BaB15O27(CO3) (2), and Ba3Si2B6O16 (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P21/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17) Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO4]3- and [CO3]2- respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO4]4- groups directly bonded to the borate groups creating a B-O-Si framework.

Low-energy vibrational dynamics of cesium borate glasses.

PubMed

Crupi, C; D'Angelo, G; Vasi, C

2012-06-07

Low-temperature specific heat and inelastic light scattering experiments have been performed on a series of cesium borate glasses and on a cesium borate crystal. Raman measurements on the crystalline sample have revealed the existence of cesium rattling modes in the same frequency region where glasses exhibit the boson peak (BP). These localized modes are supposed to overlap with the BP in cesium borate glasses affecting its magnitude. Their influence on the low frequency vibrational dynamics in glassy samples has been considered, and their contribution to the specific heat has been estimated. Evidence for a relation between the changes of the BP induced by the increased amount of metallic oxide and the variations of the elastic medium has been provided.

Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

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

Champenois, Jean-Baptiste; Dhoury, Mélanie; Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr

Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorlymore » crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.« less

Ba 2TeO: A new layered oxytelluride

DOE PAGES

Besara, T.; Ramirez, D.; Sun, J.; ...

2015-02-01

For single crystals of the new semiconducting oxytelluride phase, Ba 2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba 2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba 2TeO is highly insulating.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Thermally induced optical damage to barium-sodium niobate crystals

NASA Astrophysics Data System (ADS)

Baryshev, S. A.; Goncharova, I. F.; Konvisar, P. G.; Kuznetsov, V. A.

1990-06-01

Thermally induced optical damage (TIOD) was observed in undoped barium-sodium niobate (BSN) crystals as a result of changes in their temperature. This damage was deduced from the behavior of YAG:Nd3+ laser radiation when a BSN crystal was inserted in the resonator and also using a helium-neon laser probe beam. The experimental results were satisfactorily explained by the familiar pyroelectric model of TIOD and, in the crystals studied, an inhomogeneity of the conductivity rather than an inhomogeneity of the pyroelectric constant played the main role.

Power and efficiency scaling of diode pumped Cr:LiSAF lasers: 770-1110 nm tuning range and frequency doubling to 387-463 nm.

PubMed

Demirbas, Umit; Baali, Ilyes

2015-10-15

We report significant average power and efficiency scaling of diode-pumped Cr:LiSAF lasers in continuous-wave (cw), cw frequency-doubled, and mode-locked regimes. Four single-emitter broad-area laser diodes around 660 nm were used as the pump source, which provided a total pump power of 7.2 W. To minimize thermal effects, a 20 mm long Cr:LiSAF sample with a relatively low Cr-concentration (0.8%) was used as the gain medium. In cw laser experiments, 2.4 W of output power, a slope efficiency of 50%, and a tuning range covering the 770-1110 nm region were achieved. Intracavity frequency doubling with beta-barium borate (BBO) crystals generated up to 1160 mW of blue power and a record tuning range in the 387-463 nm region. When mode locked with a saturable absorber mirror, the laser produced 195 fs pulses with 580 mW of average power around 820 nm at a 100.3 MHz repetition rate. The optical-to-optical conversion efficiency of the system was 33% in cw, 16% in cw frequency-doubled, and 8% in cw mode-locked regimes.

Realization of a mW-level 10.7-eV (λ = 115.6 nm) laser by cascaded third harmonic generation of a Yb:fiber CPA laser at 1-MHz.

PubMed

Zhao, Zhigang; Kobayashi, Yohei

2017-06-12

We demonstrate a 10.7-eV (λ = 115.6 nm) laser with mW levels of average power and a 1-MHz repetition rate, which was driven by the third harmonic radiation (THG), at 347 nm, of an Yb:fiber chirped pulse amplifier (CPA) laser. The 347 nm ultraviolet radiation was obtained by frequency conversion of the high power output of a 1-MHz Yb:fiber CPA, using beta barium borate (BBO) nonlinear crystals. The frequency converted output was focused down into a gas cell filled with a mixture of Ar and Xe, and was subjected to a second THG frequency conversion. The generated 10.7-eV laser was separated from the fundamental beam using a LiF prism and no further separation from other harmonic waves was required. The highest measured output power was ~80 μW, which corresponded to an average power of ~1.25 mW inside the gas cell when the transmission coefficients of the LiF optics were taken into account. The corresponding conversion efficiency from 347 nm down to 115.6 nm was ~2.5 × 10 -4 .

Assessment of Barium Sulphate Formation and Inhibition at Surfaces with Synchrotron X-ray Diffraction (SXRD)

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

E Mavredaki; A Neville; K Sorbie

2011-12-31

The precipitation of barium sulphate from aqueous supersaturated solutions is a well-known problem in the oil industry often referred to as 'scaling'. The formation and growth of barite on surfaces during the oil extraction process can result in malfunctions within the oil facilities and serious damage to the equipment. The formation of barium sulphate at surfaces remains an important topic of research with the focus being on understanding the mechanisms of formation and means of control. In situ synchrotron X-ray diffraction (SXRD) was used to investigate the formation of barium sulphate on a stainless steel surface. The effect of Poly-phosphinocarboxylicmore » acid (PPCA) and Diethylenetriamine-penta-methylenephosphonic acid (DETPMP) which are two commercial inhibitors for barium sulphate was examined. The in situ SXRD measurements allowed the identification of the crystal faces of the deposited barite in the absence and presence of the two inhibitors. The preferential effect of the inhibitors on some crystal planes is reported and the practical significance discussed.« less

Intracavity frequency doubling of a continuous-wave, diode-laser-pumped neodymium lanthanum scandium borate laser.

PubMed

Meyn, J P; Huber, G

1994-09-15

Neodymium-doped lanthanum scandium borate [Nd:LaSc(3)(BO(3))(4)] is a new material for efficient and compact diode-pumped solid-state lasers. A simple plane-plane 3-mm-long resonator is formed by a coated Nd(10%):LaSc(3)(BO(3))(4) crystal and a coated potassium titanyl phosphate (KTP) crystal. The second-harmonic output power at 531 nm is 522 mW at 2.05-W incident pump power of the diode laser. The corresponding optical efficiency is 25%, and the conversion efficiency from the fundamental to the second harmonic is 55%. The wellknown chaotic power fluctuations of intracavity frequency-doubled lasers (green problem) are avoided by use of a short KTP crystal, between 0.5 and 2 mm in length.

Crystal nucleation in lithium borate glass

NASA Technical Reports Server (NTRS)

Smith, Gary L.; Neilson, George F.; Weinberg, Michael C.

1988-01-01

Crystal nucleation measurements were made on three lithium borate compositions in the vicinity of Li2O-2Br2O3. All nucleation measurements were performed at 500 C. Certain aspects of the nucleation behavior indicated (tentatively) that it proceeded by a homogeneous mechanism. The steady state nucleation rate was observed to have the largest value when the Li2O concentration was slightly in excess of the diborate composition. The change in nucleation rate with composition is controlled by the variation of viscosity as well as the change in free energy with composition. The variation of nucleation rate is explained qualitatively in these terms.

Na{sub 6}B{sub 13}O{sub 22.5}, a new noncentrosymmetric sodium borate

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

Penin, N.; Touboul, M.; Nowogrocki, G.

2005-03-15

Na{sub 6}B{sub 13}O{sub 22.5} (B/Na=2.17) single crystals were obtained by heating, melting and appropriately cooling borax, Na{sub 2}[B{sub 4}O{sub 5}(OH){sub 4}].8H{sub 2}O. Its formula has been determined by the resolution of the structure from single-crystal X-ray diffraction data. The compound crystallizes in the noncentrosymmetric orthorhombic Iba2 space group, with the following unit cell parameters: a=33.359(11)A, b=9.554(3)A, c=10.644(4)A; V=3392.4(19)A{sup 3}; Z=8. The crystal structure was solved from 3226 reflections until R{sub 1}=0.0385. It exhibits a three-dimensional framework built up from BO{sub 3} triangles ({delta}) and BO{sub 4} tetrahedra (T). Two kinds of borate groups can be considered forming two different doublemore » B{sub 3}O{sub 3} rings: two B{sub 4}O{sub 9} (linkage by two boron atoms) and one B{sub 5}O{sub 11} (linkage by one boron atom); the shorthand notation of the new fundamental building block (FBB) existing in this compound is: 13: {infinity}{sup 3} [(5: 3{delta}+2T)+2(4: 2{delta}+2T)]. The discovery of this new borate questions the real number of Na{sub 2}B{sub 4}O{sub 7} varieties. The existence of Na{sub 6}B{sub 13}O{sub 22.5} (B/Na=2.17) and of another recently discovered borate, Na{sub 3}B{sub 7}O{sub 12} (B/Na=2.33; FBB 7: {infinity}{sup 3} [(3: 2{delta}+T)+(3: {delta}+2T)+(1: {delta})], with a composition close to the long-known borate {alpha}-Na{sub 2}B{sub 4}O{sub 7} (B/Na=2; FBB 8: {infinity}{sup 3} [(5: 3{delta}+2T)+(3: 2{delta}+T)], may explain the very complex equilibria reported in the Na{sub 2}O-B{sub 2}O{sub 3} phase diagram, especially in this range of composition.« less

Supramolecular assembly of borate with quaternary ammonium: Crystal structure and tunable luminescent properties

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

Liang, Jie; Wang, Yong-gang; Wang, Ying-xia, E-mail: wangyx@pku.edu.cn

2013-04-15

A new borate [C{sub 6}H{sub 16}N][B{sub 5}O{sub 6}(OH){sub 4}] (1) is synthesized hydrothermally by the reaction of isopropyltrimethylammonium hydroxide with boric acid. It crystallizes in the triclinic space group P-1 with the parameters a=9.1578(10) Å, b=9.372(9) Å, c=9.9812(10) Å, α=66.508(2)°, β=74.751(2)°, γ=81.893(2)°. The [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH{sub 3}){sub 3}(i-C{sub 3}H{sub 7}) N{sup +} cations. This borate shows tunable luminescent properties with temperature, heating-treatment, exciting-light, and solvents. The fluorescent intensity of 1 enhances 6-fold with decreasing the temperature from 25 K tomore » 78 K. By treatment under different temperatures, the luminescence of 1 shifted from blue to white and the sample treated at 230 °C emits bright white light to naked eyes. The hybrid borate can disperse in different solvents, and shows a red-shifted and intense emission in polar solvents. - Graphical abstract: The new quaternary ammonium borate [C{sub 6}H{sub 17}N][B{sub 5}O{sub 6}(OH){sub 4}] contains a 3D supramolecular network formed by hydrogen bond linked [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions and shows tunable luminescent properties with temperature, excitation light, and solvents. Highlights: ► A novel quaternary ammonium borate was synthesized. ► It possesses a supramolecular network fomed by H-bonded [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions. ► This borate shows tunable luminescent properties with temperature, heating treatment, excitation light, and solvents.« less

Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

NASA Astrophysics Data System (ADS)

Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

2015-05-01

194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

High-pressure synthesis and characterization of the first cerium fluoride borate CeB{sub 2}O{sub 4}F

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

Hinteregger, Ernst; Wurst, Klaus; Tribus, Martina

2013-08-15

CeB{sub 2}O{sub 4}F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) Å{sup 3}, R{sub 1}=0.0698, and wR{sub 2}=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−}more » groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed. - Graphical abstract: A new rare-earth fluoride borate CeB{sub 2}O{sub 4}F could be synthesized under high-pressure/high-temperature conditions of 0.9 °GPa and 1450 °Cin a Walker-type multianvil apparatus. The crystal structure represents a new structure type in the class of rare-earth fluoride borates. The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−} groups. A closer view on the ac-plane shows an interesting wave-like modulation of the borate chains. Highlights: • CeB{sub 2}O{sub 4}F is the first fluoride borate exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. • CeB{sub 2}O{sub 4}F is the first cerium fluoride borate. • High-pressure conditions were necessary to synthesize CeB{sub 2}O{sub 4}F.« less

Devitrification properties of lead borate glasses

NASA Astrophysics Data System (ADS)

Bajaj, Anu; Khanna, Atul; Krishnan, K.; Aggarwal, Suresh K.

2013-06-01

Lead borate glasses containing 30 to 60 mol% PbO were prepared by melt quenching technique and devitrified by long duration heat treament in the supercooled region. Glasses crystallized on heating above their glass transition temperature, and the crystalline phases produced on devitrification were characterized by XRD and DSC analyses. Glass with 30 mol% PbO slowly formed a solid solution of Pb6B10O21 and Pb5B8O17 crystalline phases, while glasses with 40 and 50 mol% PbO formed a mixture of Pb6B10O21, Pb5B8O17 and the remanent glassy phase. Glasses with higher PbO concentration of 56 to 60 mol% devitrified completely and produced only Pb5B8O17 crystalline phase. Lead borate glasses with PbO concentration of 40 to 50 mol% showed maximum thermal stability against devitrification, the ease of crystallization of glasses was correlated with the fraction of tetrahedral borons in them.

Fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses containing lithium, zinc and lead.

PubMed

Venkatramu, V; Babu, P; Jayasankar, C K

2006-02-01

The influence of glass composition on the fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses modified with Li+, Zn2+ and Pb2+ cations have been investigated. The magnitude of splittings of 7F1 levels are analyzed using crystal-field (CF) analysis. The relative intensities of 5D0 --> 7F2 to 5D0 --> 7F1 transitions, crystal-field strength parameters and decay times of the 5D0 level have been determined and are found to be lower for Pb based glasses than those of Zn/Li based glasses. The lifetimes of 5D0 level are found to increase when borate glasses are modified with pure fluorides than with oxides and oxyfluorides. The fluorescence decay of 5D0 level fits perfect single exponential in the Eu3+:glass systems studied which indicates the absence of energy transfer between Eu3+ ions in these glasses.

Upper Gastrointestinal (GI) Series

MedlinePlus

... abdomen or ask you to change position several times to evenly coat your upper GI tract with the barium. If you are having a double-contrast study, you will swallow gas-forming crystals that mix with the barium coating your stomach. ...

Synthesis and characterization of barium hexaferrite with manganese (Mn) doping material as anti-radar

NASA Astrophysics Data System (ADS)

Susilawati, Doyan, Aris; Khalilurrahman

2017-01-01

Have been successfully synthesized barium powder doping Manganese hexaferrite with the expected potential as anti-radar material. Synthesis was done by using the co-precipitation method, the variation of the variable x concentrations used were 0; 0.2; 0.4; and 0.6 and calcined at temperatures of 400, 600 and 800°C. Characterization powders of hexaferrite have used XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), LCR (inductance, capacitance, and resistance) meter, and VSM (Vibrating Sample Magnetometer). The higher the concentration and temperature of calcinations given affect the color of the powder. The test results using XRD indicates that it has formed barium hexaferrite phase with a hexagonal crystal structure. Tests using SEM showed that all the constituent elements barium powder hexaferrite by doping Manganese powders have been spread evenly. XRD test results were confirmed by a test using a TEM showing the crystal structure and the powder was sized nano particles. The results from the LCR meter showed that the barium powder hexaferrite by doping Manganese that has been synthesized classified in semiconductor materials. The result from VSM showed that the value of coercivity magnetic powder doped barium hexaferrite Manganese is smaller when compared with barium hexaferrite without doping and belong to the soft magnetic. Based on the results of the synthesis and characterization, we can conclude that the barium powder heksaferrite by doping Manganese potential as a material anti-radar.

Effect of modifying agents on the hydrophobicity and yield of zinc borate synthesized by zinc oxide

NASA Astrophysics Data System (ADS)

Acarali, Nil Baran; Bardakci, Melek; Tugrul, Nurcan; Derun, Emek Moroydor; Piskin, Sabriye

2013-06-01

The aim of this study was to synthesize zinc borate using zinc oxide, reference boric acid, and reference zinc borate (reference ZB) as the seed, and to investigate the effects of modifying agents and reaction parameters on the hydrophobicity and yield, respectively. The reaction parameters include reaction time (1-5 h), reactant ratio (H3BO3/ZnO by mass: 2-5), seed ratio (seed crystal/(H3BO3+ZnO) by mass: 0-2wt%), reaction temperature (50-120°C), cooling temperature (10-80°C), and stirring rate (400-700 r/min); the modifying agents involve propylene glycol (PG, 0-6wt%), kerosene (1wt%-6wt%), and oleic acid (OA, 1wt%-6wt%) with solvents (isopropyl alcohol (IPA), ethanol, and methanol). The results of reaction yield obtained from either magnetically or mechanically stirred systems were compared. Zinc borate produced was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and contact angle tests to identify the hydrophobicity. In conclusion, zinc borate is synthesized successfully under the optimized reaction conditions, and the different modifying agents with various solvents affect the hydrophobicity of zinc borate.

Power scaling of diode-pumped neodymium yttrium aluminum borate laser

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

1991-01-01

Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

Oilfield scales: controls on precipitation and crystal morphology of barite (barium sulphate)

NASA Astrophysics Data System (ADS)

Stark, A. I. R.; Wogelius, R. A.; Vaughan, D. J.

2003-04-01

The precipitation and subsequent build up of barite (barium sulphate) inside extraction tubing presents a costly problem for off shore oil wells which use seawater to mobilize oil during hydrocarbon recovery. Mixing of reservoir formation water containing Ba2+ ions and seawater containing SO_42- ions results in barite precipitation within the reservoir well-bore region and piping. Great effort has been expended in designing strategies to minimize scale formation but details of the reaction mechanism and sensitivity to thermodynamic variables are poorly constrained. Furthermore, few detailed studies have been carried out under simulated field conditions. Hence an experimental programme was designed to study barite formation under environmentally relevant conditions with control of several system variables during the precipitation reaction. Synthetic sea-water and formation-water brines containing sodium sulphate and barium chloride, respectively, were mixed to induce BaSO_4 precipitation. Experiments were carried out at high temperature (100^oC) and high pressure (500 bars) in double rocking autoclave bombs. Barite formation as a function of the addition of calcium, magnesium, and a generic phosphonate based scale inhibitor was investigated whilst maintaining constant pH, temperature and ionic strength (0.5159). Additional experiments were performed at ambient conditions for comparison. Data concerning nucleation, growth rates, and crystal morphology were obtained. ICP-AES data from the supernatant product solutions showed considerable variation in quantity of barium sulphate precipitated as a function of the listed experimental variables. For example, ESEM analysis of barium sulphate crystals showed a dramatic shift in crystal habit from the typical tabular habit produced in control experiments; experiments performed in the presence of foreign cations produced more equant crystals, while those experiments completed in the presence of the phosphonate scale inhibitor produced precipitates with distorted anhedral shapes. Based on these preliminary results, further experiments which monitor rate and morphology as a function of Ba/Ca ratio, ionic strength, and ion activity product for barite will also be completed.

Structure determination and characterization of two rare-earth molybdenum borate compounds: LnMoBO(6) (Ln = La, Ce).

PubMed

Zhao, Dan; Cheng, Wen-Dan; Zhang, Hao; Hang, Shu-Ping; Fang, Ming

2008-07-28

The structural, optical, and electronic properties of two rare-earth molybdenum borate compounds, LnMoBO(6) (Ln = La, Ce), have been investigated by means of single-crystal X-ray diffraction, elemental analyses, and spectral measurements, as well as calculations of energy band structures, density of states, and optical response functions by the density functional method. The title compounds, which crystallize in monoclinic space group P2(1)/c, possess a similar network of interconnected [Ce(2)(MoO(4))(2)](2+) chains and [BO(2)](-) wavy chains. Novel 1D molybdenum oxide chains are contained in their three-dimensional (3D) networks. The calculated results of crystal energy band structure by the density functional theory (DFT) method show that the solid-state compound LaMoBO(6) is a semiconductor with indirect band gaps.

High-pressure synthesis and characterization of new actinide borates, AnB4O8 (An=Th, U).

PubMed

Hinteregger, Ernst; Hofer, Thomas S; Heymann, Gunter; Perfler, Lukas; Kraus, Florian; Huppertz, Hubert

2013-11-18

New actinide borates ThB4O8 and UB4O8 were synthesized under high-pressure, high-temperature conditions (5.5 GPa/1100 °C for thorium borate, 10.5 GPa/1100 °C for the isotypic uranium borate) in a Walker-type multianvil apparatus from their corresponding actinide oxide and boron oxide. The crystal structure was determined on basis of single-crystal X-ray diffraction data that were collected at room temperature. Both compounds crystallized in the monoclinic space group C2/c (Z=4). Lattice parameters for ThB4O8: a=1611.3(3), b=419.86(8), c=730.6(2) pm; β=114.70(3)°; V=449.0(2) Å(3); R1=0.0255, wR2=0.0653 (all data). Lattice parameters for UB4O8: a=1589.7(3), b=422.14(8), c=723.4(2) pm; β=114.13(3)°; V=443.1(2) Å(3); R1=0.0227, wR2=0.0372 (all data). The new AnB4O8 (An=Th, U) structure type is constructed from corner-sharing BO4 tetrahedra, which form layers in the bc plane. One of the four independent oxygen atoms is threefold-coordinated. The actinide cations are located between the boron-oxygen layers. In addition to Raman spectroscopic investigations, DFT calculations were performed to support the assignment of the vibrational bands. © 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This isan open access article under the terms of the Creative Commons AttributionLicense, which permits use, distribution and reproduction in any medium,provided the original work is properly cited.

Crystal structure of a new polar borate Na{sub 2}Ce{sub 2}[BO{sub 2}(OH)][BO{sub 3}]{sub 2} · H{sub 2}O with isolated boron triangles

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

Topnikova, A. P.; Belokoneva, E. L., E-mail: elbel@geol.msu.ru; Dimitrova, O. V.

2016-11-15

Crystals of a new polar borate Na{sub 2}Ce{sub 2}[BO{sub 2}(OH)][BO{sub 3}]{sub 2} · H{sub 2}O were prepared by hydrothermal synthesis. The crystals are orthorhombic, a = 7.2295(7) Å, b = 11.2523(8) Å, c = 5.1285(6) Å, Z = 2, sp. gr. C2mm (Amm2), R = 0.0253. The formula of the compound was derived from the structure determination. The Ce and Na atoms are coordinated by nine and six O atoms, respectively. The Ce position is split, and a small amount of Ce is incorporated into the Na1 site with the isomorphous substitution for Na. The anionic moieties exist as isolatedmore » BO{sub 3} and BO{sub 2}(OH) triangles. The planes of the BO{sub 2}(OH) triangles with mm2 symmetry are parallel to the ab plane. The planes of the BO{sub 3} triangles with m symmetry are perpendicular to the ab plane and are rotated in a diagonal way. The splitting of the Ce positions and the polar arrangement of the BO{sub 2}(OH) triangles, water molecules, and Na atoms are observed along the polar a axis. The new structure is most similar to the new borate NaCa{sub 4}[BO{sub 3}]{sub 3} (sp. gr. Ama2), in which triangles of one type are arranged in a polar fashion along the c axis. Weak nonlinear-optical properties of both polar borates are attributed to the quenching of the second-harmonic generation due to the mutually opposite orientation of two-thirds of B triangles in the unit cell.« less

The effect of B 2O 3 addition on the crystallization of amorphous TiO 2-ZrO 2 mixed oxide

NASA Astrophysics Data System (ADS)

Mao, Dongsen; Lu, Guanzhong

2007-02-01

The effect of B 2O 3 addition on the crystallization of amorphous TiO 2-ZrO 2 mixed oxide was investigated by X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG/DTA). TiO 2-ZrO 2 mixed oxide was prepared by co-precipitation method with aqueous ammonia as the precipitation reagent. Boric acid was used as a source of boria, and boria contents varied from 2 to 20 wt%. The results indicate that the addition of small amount of boria (<8 wt%) hinders the crystallization of amorphous TiO 2-ZrO 2 into a crystalline ZrTiO 4 compound, while a larger amount of boria (⩾8 wt%) promotes the crystallization process. FT-IR spectroscopy and 11B MAS NMR results show that tetrahedral borate species predominate at low boria loading, and trigonal borate species increase with increasing boria loading. Thus it is concluded that highly dispersed tetrahedral BO 4 units delay, while a build-up of trigonal BO 3 promote, the crystallization of amorphous TiO 2-ZrO 2 to form ZrTiO 4 crystals.

Optical properties of β-BBO and potential for THz applications

NASA Astrophysics Data System (ADS)

Nikolaev, N. A.; Andreev, Yu. M.; Antsygin, V. D.; Bekker, T. B.; Ezhov, D. M.; Kokh, A. E.; Kokh, K. A.; Lanskii, G. V.; Mamrashev, A. A.; Svetlichnyi, V. A.

2018-01-01

The anisotropy of optical properties of high quality beta barium borate crystal (β-BaB2O4, β-BBO) was studied in the main transparency window by using classic spectroscopic methods and in the range of 0.2 - 2 THz by using THz time-domain spectroscopy. β-BBO crystals were grown by the top-seeded solution technique in a highly resistive furnace with a heat field of 3-fold axis symmetry. At room temperature (RT), absorption coefficient in the maximal transparency window in grown crystals did not exceed 0.05 cm-1. Strong absorption anisotropy was observed in 3 - 5 μm and the THz range. At 1 THz absorption coefficients for e and o wave were, respectively, 7 cm-1 and 21 cm-1 at RT; 2 cm-1 and 10 cm-1 at 81 K. At the most attractive for out-of-door applications range < 0.4 THz the absorption coefficient is found to be very low: below 0.2 cm-1 at RT and 1 cm-1 at 81 K. Refractive indices dispersions measured by THz-TDS were approximated in the form of Sellmeier equations. Birefringence is found quite large for phase matched difference frequency generation (DFG) or down-conversion into the THz range (THz-DFG) under near IR pump at RT and 81 K. Type II (oe-o and eo-o), and type I (ee-e) three wave interactions can be realized at RT. THz-DFG of Nd:YAG laser and KTP OPO can be realized by type II (oe-o) three-wave interaction. For selected spectral ranges of femtosecond Ti:Sapphire laser efficient phase matched and group velocity matched optical rectification can be realized by another two types of three wave interactions. Accounting other well-known attractive physical properties of β-BBO crystal, wide application in THz technique can be forecasted.

Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6}, Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16}

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

Heyward, Carla, E-mail: cheywar@clemson.edu; McMillen, Colin D., E-mail: cmcmill@clemson.edu; Kolis, Joseph, E-mail: kjoseph@clemson.edu

2013-07-15

Several new borate compounds, Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} (1), Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) (2), and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P2{sub 1}/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17)more » Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO{sub 4}]{sup 3−} and [CO{sub 3}]{sup 2−} respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO{sub 4}]{sup 4−} groups directly bonded to the borate groups creating a B–O–Si framework. - Highlights: • Hydrothermal syntheses of three new mixed oxyanion borates are presented. • Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} contains isolated [PO{sub 4}]{sup 3−} in voids of the borate framework. • Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) contains isolated [CO{sub 3}]{sup 2−} in channels created by the framework. • Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} has direct bonding of [SiO{sub 4}]{sup 4−} and borates creating a B–O–Si framework.« less

Linking 1D Transition-Metal Coordination Polymers and Different Inorganic Boron Oxides To Construct a Series of 3D Inorganic-Organic Hybrid Borates.

PubMed

Zhi, Shao-Chen; Wang, Yue-Lin; Sun, Li; Cheng, Jian-Wen; Yang, Guo-Yu

2018-02-05

Three inorganic-organic hybrid borates, M(1,4-dab)[B 5 O 7 (OH) 3 ] [M = Zn (1), Cd (2), 1,4-dab = 1,4-diaminobutane)] and Co(1,3-dap)[B 4 O 7 ] (3, 1,3-dap = 1,3-diaminopropane), which integrated characteristics of 1D coordination polymers and 1D/3D inorganic boron oxides have been obtained under solvothermal conditions. Compounds 1 and 2 are isostructural and crystallize in a centrosymmetric space group P2 1 /c; the 3D achiral structures of 1 and 2 consist of the nonhelical Zn/Cd-1,4-dap coordination polymers and 1D B-O chains. Compound 3 crystallizes in a chiral space group P4 3 2 1 2; the helical Co-1,3-dap coordination polymer chains are entrained within a 3D B-O network and finally form the chiral framework. Compounds 1-3 represent good examples of using coordination polymers to construct mixed-motif inorganic-organic hybrid borates. Compounds 1 and 2 display blue luminescence when excited with UV light.

Phase diagrams and physicochemical properties of Li+,K+(Rb+)//borate-H2O systems at 323 K

NASA Astrophysics Data System (ADS)

Feng, Shan; Yu, Xudong; Cheng, Xinglong; Zeng, Ying

2017-11-01

The phase and physicochemical properties diagrams of Li+,K+(Rb+)//borate-H2O systems at 323 K were constructed using the experimentally measured solubilities, densities, and refractive indices. The Schreinemakers' wet residue method and the X-ray diffraction were used for the determination of the compositions of solid phase. Results show that these two systems belong to the hydrate I type, with no solid solution or double salt formation. The borate phases formed in our experiments are RbB5O6(OH)4 · 2H2O, Li2B4O5(OH)4 · H2O, and K2B4O5(OH)4 · 2H2O. Comparison between the stable phase diagrams of the studied system at 288, 323, and 348 K show that in this temperature range, the crystallization form of salts do not changed. With the increase in temperature, the crystallization field of Li2B4O5(OH)4 · H2O salt at 348 K is obviously larger than that at 288 K. In the Li+,K+(Rb+)//borate-H2O systems, the densities and refractive indices of the solutions (at equilibrium) increase along with the mass fraction of K2B4O7 (Rb2B4O7), and reach the maximum values at invariant point E.

Spectroscopic analysis of a novel Nd3+-activated barium borate glass for broadband laser amplification

NASA Astrophysics Data System (ADS)

Vázquez, G. V.; Muñoz H., G.; Camarillo, I.; Falcony, C.; Caldiño, U.; Lira, A.

2015-08-01

Spectroscopic parameters of a novel Nd3+-activated barium borate (BBONd) glass have been analyzed for broadband laser amplification. The Judd-Ofelt (JO) intensity parameters were determined through a systematic analysis of the absorption spectrum of Nd3+ ions in the BBONd glass. High values of the JO intensity parameters reveal a great centro-symmetrical loss of the Nd3+ sites and high covalency degree of the ligand field. The very high Ω6 intensity parameter value makes evident both a great structural distortion of the Nd3+ sites and a strong electron-phonon coupling between Nd3+ and free OH- ions, which is consistent with the phonon energy maximum (3442.1 cm-1) recorded by Raman spectroscopy. This strong electron-phonon coupling favors high effective bandwidth and gain bandwidth values of the laser emission (4F3/2 → 4I11/2) of Nd3+ ions. The electric-dipole oscillator strengths of all the Nd3+ absorption transitions, and in particular that of the hypersensitive transition (4I9/2 → 4G5/2), are enhanced by this great structural distortion of the host. Broadband laser amplification of the 4F3/2 → 4I11/2 emission (1062 nm) of Nd3+ ions in the BBONd glass pumped at 805 nm (4I9/2 → 4F5/2 + 2H9/2) is evaluated through the main fluorescent parameters in competition with non-radiative processes. In general, the BBONd glass exhibits spectroscopic parameters comparable with those reported in the literature for broadband laser amplification into the IR region.

Morphology control of anisotropic BaTiO 3 and BaTiOF 4 using organic-inorganic interaction

NASA Astrophysics Data System (ADS)

Masuda, Yoshitake; Tanaka, Yuki; Gao, Yanfeng; Koumoto, Kunihito

2009-01-01

We proposed a novel concept for morphology control of barium titanate precursor to fabricate platy particles. Organic molecules play an essential role in the crystallization of BaTiOF 4 to synthesize multi-needle particles, polyhedron particles or platy particles in an aqueous solution. Precursors were successfully transformed to barium titanate single phase by annealing. Platy barium titanate precursor particles are expected for future multilayer ceramic capacitors.

Record fifth-harmonic-generation efficiency producing 211 nm, joule-level pulses using cesium lithium borate

DOE PAGES

Begishev, I. A.; Bromage, J.; Yang, S. T.; ...

2018-05-16

The fifth harmonic of a pulsed Nd:YLF laser has been realized in a cascade of nonlinear crystals with a record efficiency of 30%. Cesium lithium borate is used in a Type-I configuration for sum-frequency mixing of 1053 nm and 266 nm, producing 211-nm pulses. Flattopped beam profiles and pulse shapes optimize efficiency. Furthermore, energies of the fifth harmonic up to 335 mJ in 2.4 ns pulses were demonstrated.

Record fifth-harmonic-generation efficiency producing 211  nm, joule-level pulses using cesium lithium borate

DOE PAGES

Begishev, I. A.; Bromage, J.; Yang, S. T.; ...

2018-01-01

The fifth harmonic of a pulsed Nd:YLF laser has been realized in a cascade of nonlinear crystals with a record efficiency of 30%. Cesium lithium borate is used in a Type-I configuration for sum-frequency mixing of 1053 nm and 266 nm, producing 211-nm pulses. Flattopped beam profiles and pulse shapes optimize efficiency. Energies of the fifth harmonic up to 335 mJ in 2.4 ns pulses were demonstrated.

Record fifth-harmonic-generation efficiency producing 211 nm, joule-level pulses using cesium lithium borate

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

Begishev, I. A.; Bromage, J.; Yang, S. T.

The fifth harmonic of a pulsed Nd:YLF laser has been realized in a cascade of nonlinear crystals with a record efficiency of 30%. Cesium lithium borate is used in a Type-I configuration for sum-frequency mixing of 1053 nm and 266 nm, producing 211-nm pulses. Flattopped beam profiles and pulse shapes optimize efficiency. Furthermore, energies of the fifth harmonic up to 335 mJ in 2.4 ns pulses were demonstrated.

Efficient second to ninth harmonic generation using megawatt peak power microchip laser.

PubMed

Bhandari, R; Tsuji, N; Suzuki, T; Nishifuji, M; Taira, T

2013-11-18

We report the design and use of a megawatt peak power Nd:YAG/Cr4+:YAG microchip laser for efficient second to ninth harmonic generation. We show that the sub-nanosecond pulse width region, between 100 ps and 1 ns, is ideally suited for efficient wavelength conversion. Using this feature, we report 85% second harmonic generation efficiency using lithium triborate (LBO), 60% fourth harmonic generation efficiency usingß-barium borate, and 44% IR to UV third harmonic generation efficiency using Type I and Type II LBO. Finally, we report the first demonstration of 118 nm VUV generation in xenon gas using a microchip laser.

Growth, structural, spectroscopic and optical characterization of barium doped calcium tartrate

NASA Astrophysics Data System (ADS)

Verma, Seema; Raina, Bindu; Gupta, Vandana; Bamzai, K. K.

2018-05-01

Barium doped calcium tartrates synthesized by controlled diffusion using silica gel technique at ambient temperature was characterized by single crystal X-ray diffraction which establishes monoclinic crystal system with volume of the unit cell 923.97(10) Ǻ3 and the space group being P21. UV - Vis characterization gives various linear optical constants like absorption, transmittance, reflectance, band gap, extinction coefficient, urbach energy, complex dielectric constant, optical and electrical conductivity. These constants are considered to be essential in characterizing materials that are used in various applications like fabrication of optoelectronic devices. FTIR spectrum establishes the presence of various bands of functional groups expected from metal tartrate with water of crystallization.

Borate minerals and origin of the RNA world.

PubMed

Grew, Edward S; Bada, Jeffrey L; Hazen, Robert M

2011-08-01

The RNA World is generally thought to have been an important link between purely prebiotic (>3.7 Ga) chemistry and modern DNA/protein biochemistry. One concern about the RNA World hypothesis is the geochemical stability of ribose, the sugar moiety of RNA. Prebiotic stabilization of ribose by solutions associated with borate minerals, notably colemanite, ulexite, and kernite, has been proposed as one resolution to this difficulty. However, a critical unresolved issue is whether borate minerals existed in sufficient quantities on the primitive Earth, especially in the period when prebiotic synthesis processes leading to RNA took place. Although the oldest reported colemanite and ulexite are 330 Ma, and the oldest reported kernite, 19 Ma, boron isotope data and geologic context are consistent with an evaporitic borate precursor to 2400-2100 Ma borate deposits in the Liaoning and Jilin Provinces, China, as well as to tourmaline-group minerals at 3300-3450 Ma in the Barberton belt, South Africa. The oldest boron minerals for which the age of crystallization could be determined are the metamorphic tourmaline species schorl and dravite in the Isua complex (metamorphism between ca. 3650 and ca. 3600 Ma). Whether borates such as colemanite, ulexite and kernite were present in the Hadean (>4000 Ma) at the critical juncture when prebiotic molecules such as ribose required stabilization depends on whether a granitic continental crust had yet differentiated, because in its absence we see no means for boron to be sufficiently concentrated for borates to be precipitated.

Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

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

Trull, J.; Wang, B.; Parra, A.

2015-06-01

Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

Spirocyclic character of ixazomib citrate revealed by comprehensive XRD, NMR and DFT study

NASA Astrophysics Data System (ADS)

Skorepova, Eliska; Čerňa, Igor; Vlasáková, Růžena; Zvoníček, Vít; Tkadlecová, Marcela; Dušek, Michal

2017-11-01

Ixazomib citrate is a very recently approved anti-cancer drug. Until now, to the best of our knowledge, no one has been able to solve any crystal structures of this compound. In this work, we present the crystal structures of two isostructural solvates of ixazomib citrate. In all currently available literature, the molecule is characterized as containing a single optically active carbon atom and a borate cycle formed when ixazomib is reacted with citric acid to form a stabilized ixazomib citrate that can be administered orally. However, the crystal structures revealed that none of the up-to-date presented structural formulas of ixazomib citrate are fully accurate. In addition to the citrate ring, another 5-membered ring is formed. These two rings are connected by the boron atom, making this compound a spirocyclic borate. By spirocyclization, the boron atom becomes tetrahedral and therefore optically active. In the crystal structures, ixazomib citrate was found to be in forms of two RR and RS stereoisomers. The results are supported by solid-state and solution NMR and DFT quantum mechanical calculations.

Synthesis and crystal structure of the rhodium(I) cyclooctadiene complex with bis(3-tert-butylimidazol-2-ylidene)borate ligand

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

Chen, F.; Shao, K.-J.; Xiao, Y.-C.

2015-12-15

The rhodium(I) cyclooctadiene complex with the bis(3-tert-butylimidazol-2-ylidene)borate ligand [H{sub 2}B(Im{sup t}Bu){sup 2}]Rh(COD) C{sup 22}H{sup 36}BN{sup 4}Rh, has been prepared, and its crystal structure is determined by X-ray diffraction. Complex exhibits slightly distorted square planar configurations around the metal center, which is coordinated by the bidentate H{sup 2}B(Im{sup t}Bu){sub 2} and one cyclooctadiene group. The Rh–C{sub carbene} bond lengths are 2.043(4) and 2.074(4) Å, and the bond angle C–Rh1–C is 82.59°. The dihedral angle between two imidazol-2-ylidene rings is 67.30°.

Calcium sulfoaluminate cement blended with OPC: A potential binder to encapsulate low-level radioactive slurries of complex chemistry

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

Cau Dit Coumes, Celine; Courtois, Simone; Peysson, Sandrine

Investigations were carried out in order to solidify in cement a low-level radioactive waste of complex chemistry obtained by mixing two process streams, a slurry produced by ultra-filtration and an evaporator concentrate with a salinity of 600 gxL{sup -1}. Direct cementation with Portland cement (OPC) was not possible due to a very long setting time of cement resulting from borates and phosphates contained in the waste. According to a classical approach, this difficulty could be solved by pre-treating the waste to reduce adverse cement-waste interactions. A two-stage process was defined, including precipitation of phosphates and sulfates at 60 deg. Cmore » by adding calcium and barium hydroxide to the waste stream, and encapsulation with a blend of OPC and calcium aluminate cement (CAC) to convert borates into calcium quadriboroaluminate. The material obtained with a 30% waste loading complied with specifications. However, the pre-treatment step made the process complex and costly. A new alternative was then developed: the direct encapsulation of the waste with a blend of OPC and calcium sulfoaluminate cement (CSA) at room temperature. Setting inhibition was suppressed, which probably resulted from the fact that, when hydrating, CSA cement formed significant amounts of ettringite and calcium monosulfoaluminate hydrate which incorporated borates into their structure. As a consequence, the waste loading could be increased to 56% while keeping acceptable properties at the laboratory scale.« less

BiSr3(YO)3(BO3)4: a new gaudefroyite-type rare-earth borate with moderate SHG response.

PubMed

Gao, Jianhua; Li, Shuai

2012-01-02

The synthesis, crystal structure, crystal growth, and characterization of a new noncentrosymmetric rare-earth borate BiSr(3)(YO)(3)(BO(3))(4) are reported. BiSr(3)(YO)(3)(BO(3))(4) belongs to gaudefroyite type of structure and crystallizes in the polar hexagonal space group P6(3) (no. 173) with a = 10.6975(16) Å and c = 6.7222(12) Å. In the structure, the YO(7) polyhedra share edges to form an one-dimensional chain along the [001] direction. These chains are interconnected by the BO(3) group to construct a three-dimensional framework, leaving two kinds of channels for Bi atoms and Sr atoms together with BO(3) groups, respectively. On the basis of the powder second-harmonic generation (SHG) measurement, BiSr(3)(YO)(3)(BO(3))(4) belongs to the phase-matchable class with a SHG response of about 3 × KDP.

Growth and characterization of barium complex of 1,3,5-triazinane-2,4,6-trione in gel: a corrosion inhibiting material

NASA Astrophysics Data System (ADS)

Divya, R.; Nair, Lekshmi P.; Bijini, B. R.; Nair, C. M. K.; Babu, K. Rajendra

2018-05-01

Good quality prismatic crystals of industrially applicable corrosion inhibiting barium complex of 1,3,5-triazinane-2,4,6-trione have been grown by conventional gel method. The crystal structure, packing, and nature of bonds are revealed in the single crystal X-ray diffraction analysis. The crystal has a three-dimensional polymeric structure having a triclinic crystal system with the space group P-1. The powder X-ray diffraction analysis confirms its crystalline nature. The functional groups present in the crystal are identified by Fourier transform infrared spectroscopy. Elemental analysis confirms the stoichiometry of the elements present in the complex. Thermogravimetric analysis and differential thermal analysis reveal its good thermal stability. The optical properties like band gap, refractive index and extinction coefficient are evaluated from the UV-visible spectral analysis. The singular property of the material, corrosion inhibition efficiency achieved by the adsorption of the sample molecules is determined by the weight loss method.

Upper Gastrointestinal (GI) Tract X-Ray (Radiography)

MedlinePlus

... to drinking barium, some patients are also given baking-soda crystals (similar to Alka-Seltzer) to further ... contrast upper GI series. The patient will swallow baking-soda crystals that create gas in the stomach ...

Precipitation of calcium, magnesium, strontium and barium in tissues of four Acacia species (Leguminosae: Mimosoideae).

PubMed

He, Honghua; Bleby, Timothy M; Veneklaas, Erik J; Lambers, Hans; Kuo, John

2012-01-01

Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory.

Precipitation of Calcium, Magnesium, Strontium and Barium in Tissues of Four Acacia Species (Leguminosae: Mimosoideae)

PubMed Central

He, Honghua; Bleby, Timothy M.; Veneklaas, Erik J.; Lambers, Hans; Kuo, John

2012-01-01

Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory. PMID:22848528

Photoluminescent carbon dots based on a rare 3D inorganic-organic hybrid cadmium borate crystal.

PubMed

Zhou, Kang; Zhang, Wen-Jin; Luo, Yuan-Zhang; Pan, Chun-Yang

2018-05-17

A 3D inorganic-organic hybridized skeleton cadmium borate [Cden][B5O8(OH)] (1) (en = ethylenediamine) has been solvothermally synthesized. By calcining it, specific shape carbon dots (C-dots) with abundant free radicals were observed. In addition, C-dots in the ethanol phase exhibited variable photoluminescence and showed rare turn on or off effects to Cr3+ ions and CdSe/ZnS quantum dots, but only a turn on effect to Cs+ ions and a turn off effect to CsPbBr3 quantum dots.

Piperidinium bis­(2-oxidobenzoato-κ2 O 1,O 2)borate

PubMed Central

Tang, Zhi-Hua; Huang, Chaojun

2009-01-01

The asymmetric unit of the title compound, C5H12N+·C14H8BO6 − or [C5H12N][BO4(C7H4O)2], contains two piperidinium cations and two bis­(salicylato)borate anions. The coordination geometries around the B atoms are distorted tetra­hedral. In the two mol­ecules, the aromatic rings are oriented at dihedral angles of 76.27 (3) and 83.86 (3)°. The rings containing B atoms have twist-boat conformations, while the two cations adopt chair conformations. In the crystal, the component species are linked by N—H⋯O hydrogen bonds. In the crystal structure, intra- and inter­molecular N—H⋯O hydrogen bonds link the mol­ecules. PMID:21581628

Occurrence of Tourmaline in Metasedimentary Rocks of the Isua Supracrustal Belt, Greenland: Implications for Ribose Stabilization in Hadean Marine Sediments.

PubMed

Mishima, Shinpei; Ohtomo, Yoko; Kakegawa, Takeshi

2016-06-01

Abiotic formation of RNA was important for the emergence of terrestrial life, but the acknowledged difficulties of generating and stabilizing ribose have often raised questions regarding how the first RNA might have formed. Previous researchers have proposed that borate could have stabilized ribose; however, the availability of borate on the early Earth has been the subject of intense debate. In order to examine whether borate was available on the early Earth, this study examined metasedimentary rocks from the Isua Supracrustal Belt. Garnet, biotite, and quartz comprise the major constituents of the examined rocks. Field relationships and the chemical compositions of the examined rocks suggest sedimentary origin. The present study found that garnet crystals contain a number of inclusions of tourmaline (a type of borosilicate mineral). All tourmaline crystals are Fe-rich and categorized as schorl. Both garnet and tourmaline often contain graphite inclusions and this close association of tourmaline with garnet and graphite has not been recognized previously. Garnet-biotite and graphite geothermometers suggest that the tourmaline in garnet experienced peak metamorphic conditions (~500 °C and 5 kbar). The mineralogical characteristics of the tourmaline and the whole rock composition indicate that the tourmaline formed authigenically in the sediment during diagenesis and/or early metamorphism. Clay minerals in modern sediments have the capability to adsorb and concentrate borate, which could lead to boron enrichment during diagenesis, followed by tourmaline formation under metamorphic conditions. Clay minerals, deposited on the early Archean seafloor, were the precursors of the garnet and biotite in the examined samples. The studied tourmaline crystals were most likely formed in the same way as modern tourmaline in marine sediments. Therefore, boron enrichment by clays must have been possible even during the early Archean. Thus, similar enrichment could have been possible during the Hadean, providing a stabilization agent for ribose.

Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

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

Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi

Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO inmore » the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long lengths (e.g., 20 mm) were patterned at the depth of 200 μm.« less

Synthesis and study on the luminescence properties of cadmium borate phosphors

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

Annalakshmi, O.; Jose, M.T., E-mail: mtjosein@yahoo.co.in; Venkatraman, B.

2014-02-01

Highlights: • Cadmium borate synthesized by solid state sintering technique. • Neutron sensitivity of the material ten times that of TLD-600. • Gamma sensitivity is found to be twice that of TLD-100. • Gamma response is linear from 0.1 to 10{sup 3} mGy. - Abstract: Cadmium borate compound prepared through wet chemical reaction from the starting chemicals followed by high temperature solid state synthesis below the melting point to get the final TL phosphor powder. Phase purity and bond details of cadmium borate crystals are characterized using X-ray diffraction technique and infrared spectroscopy. Feasibility of these materials for radiation dosimetrymore » applications was studied after gamma and neutron irradiation. Gamma irradiation of undoped phosphors show a single peak around 185 °C whereas doping with gadolinium and silver, new more intense peak observed at 290 °C. Irradiation to thermal neutrons revealed single peak around 170 °C for all the phosphors. TL emission spectra and photoluminescence (PL) studies were also carried out on the phosphors. These borate materials are found to be highly sensitive to neutrons and hence can be used for neutron detection. Neutron sensitivity of the material is about ten times that of TLD-600.« less

Energy levels and optical properties of neodymium-doped barium fluorapatite

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

Stefanos, Sennay M.; Bonner, Carl E. Jr.; Meegoda, Chandana

Energy levels of the 4f{sup 3} electronic configuration of Nd{sup 3+} in barium fluorapatite, Ba{sub 5}(PO{sub 4}){sub 3}F(B-FAP) have been determined from polarized absorption and fluorescence spectra using crystals at 8 K. Experimental energy-level assignments were made initially by comparing the crystal spectra energy levels with those obtained from those previously reported for Nd{sup 3+} in strontium fluorapatite and fluorapatite. The initial crystal-field parameters were calculated by using lattice summation techniques. The crystal-field parameters were varied to obtain a best fit between experimental and theoretical energies and the final values give a root-mean-square deviation of 7.1 cm-1. The odd-fold crystal-fieldmore » components are used to calculate the emission intensities and lifetimes of the Nd{sup 3+} ions in B-FAP. These calculations yield results in good agreement with the experimental measurements of the absorption and emission cross sections and lifetimes. (c) 2000 American Institute of Physics.« less

Preparation and characterization of magnesium borate for special glass

NASA Astrophysics Data System (ADS)

Dou, Lishuang; Zhong, Jianchu; Wang, Hongzhi

2010-05-01

Magnesium borate with a variety of B2O3/MgO molar ratios, which can be applied for special glass, has been prepared through the reaction of light-burned magnesia with boric acid by a hydrothermal method. The effects of the B2O3/MgO molar ratio of raw materials, reaction time, temperature and liquid to solid ratio (ml g-1) on the synthetic product are investigated. The XRD and TG-DTG analyses indicate that the prepared magnesium borate is a mixture of magnesium hexaborate hydrate and ascharite. The results show that high B2O3/MgO molar ratios of raw materials and low reaction liquid-solid ratios favour the product with a high B2O3/MgO molar ratio and vice versa. There exists free MgO in the product when the reaction temperature is below 140 °C or the reaction time is not enough, because of the incomplete reaction of magnesium oxide with boric acid. The process of fractional crystallization for the magnesium borate mixture is also discussed.

20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier

PubMed Central

Alismail, Ayman; Wang, Haochuan; Brons, Jonathan; Fattahi, Hanieh

2017-01-01

This is a report on a 100 W, 20 mJ, 1 ps Yb:YAG thin-disk regenerative amplifier. A homemade Yb:YAG thin-disk, Kerr-lens mode-locked oscillator with turn-key performance and microjoule-level pulse energy is used to seed the regenerative chirped-pulse amplifier. The amplifier is placed in airtight housing. It operates at room temperature and exhibits stable operation at a 5 kHz repetition rate, with a pulse-to-pulse stability less than 1%. By employing a 1.5 mm-thick beta barium borate crystal, the frequency of the laser output is doubled to 515 nm, with an average power of 70 W, which corresponds to an optical-to-optical efficiency of 70%. This superior performance makes the system an attractive pump source for optical parametric chirped-pulse amplifiers in the near-infrared and mid-infrared spectral range. Combining the turn-key performance and the superior stability of the regenerative amplifier, the system facilitates the generation of a broadband, CEP-stable seed. Providing the seed and pump of the optical parametric chirped-pulse amplification (OPCPA) from one laser source eliminates the demand of active temporal synchronization between these pulses. This work presents a detailed guide to set up and operate a Yb:YAG thin-disk regenerative amplifier, based on chirped-pulse amplification (CPA), as a pump source for an optical parametric chirped-pulse amplifier. PMID:28745636

Evaluation to the effect of B2O3-La2O3-SrO-Na2O-Al2O3 bonding agent on Ti6Al4V-porcelain bonding.

PubMed

Zhao, C Q; Wu, S Q; Lu, Y J; Gan, Y L; Guo, S; Lin, J J; Huang, T T; Lin, J X

2016-10-01

Low-fusing bonding agents have been widely applied in Ti-ceramics restorations. As an important category, borate bonding agents have great potentials in increasing Ti-porcelain bonding. The purpose of this study is to evaluate the effect of borate bonding agent with addition of Na2O and Al2O3 on Ti6Al4V-porcelain bonding. The thermal properties of borate bonding agent, such as glass transition temperature (Tg) and crystallization peak temperature (Tp), were investigated to establish the sintering process. And the coefficient of thermal expansion (CTE) was to evaluate the matching effect of porcelain to Ti6Al4V. The bond strength was analyzed by the three point bending test. The microscopic morphology of the borate bonding agent surface after sintering, the interface of Ti-borate bonding agent-porcelain, and the fracture mode after porcelains fracture, were studied to assess the influence of borate bonding agent on Ti6Al4V-ceramics. With the addition of Na2O and Al2O3, the porcelain residues were observed increased indication on the Ti6Al4V surface after porcelain fracture and the bond strength was acquired the maximum (49.45MPa) in the bonding agent composition of 75.70B2O3-5.92La2O3-11.84SrO-4.67Na2O-1.87Al2O3. Those results suggest that borate bonding agent is an effective way to improve the Ti6Al4V-ceramics bond strength. And the addition of Na2O and Al2O3 strengthen this effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Large Faraday effect of borate glasses with high Tb3+ content prepared by containerless processing

NASA Astrophysics Data System (ADS)

Suzuki, Futoshi; Sato, Fumio; Oshita, Hiroyuki; Yao, Situ; Nakatsuka, Yuko; Tanaka, Katsuhisa

2018-02-01

Borate glasses containing a large amount of Tb3+ ions have been prepared by containerless processing. The content of Tb2O3 reached 60 mol%. The glass bearing the highest content of Tb3+ ions showed a large Faraday effect; the Verdet constant was 234 rad/T m. Annealing of the glasses in H2/N2 atmosphere resulted in a low optical absorption coefficient, leading to an extremely large magneto-optical figure of merit that was ∼1.7 times higher than that of Tb3Ga5O12 single crystal.

Evaluation of a Fluorochlorozirconate Glass-Ceramic Storage Phosphor Plate for Gamma-Ray Computed Radiography

DOE PAGES

Leonard, Russell L.; Gray, Sharon K.; Alvarez, Carlos J.; ...

2015-05-21

In this paper, a fluorochlorozirconate (FCZ) glass-ceramic containing orthorhombic barium chloride crystals doped with divalent europium was evaluated for use as a storage phosphor in gamma-ray imaging. X-ray diffraction and phosphorimetry of the glass-ceramic sample showed the presence of a significant amount of orthorhombic barium chloride crystals in the glass matrix. Transmission electron microscopy and scanning electron microscopy were used to identify crystal size, structure, and morphology. The size of the orthorhombic barium chloride crystals in the FCZ glass matrix was very large, ~0.5–0.7 μm, which can limit image resolution. The FCZ glass-ceramic sample was exposed to 1 MeV gammamore » rays to determine its photostimulated emission characteristics at high energies, which were found to be suitable for imaging applications. Test images were made at 2 MeV energies using gap and step wedge phantoms. Gaps as small as 101.6 μm in a 440 stainless steel phantom were imaged using the sample imaging plate. Analysis of an image created using a depleted uranium step wedge phantom showed that emission is proportional to incident energy at the sample and the estimated absorbed dose. Finally, the results showed that the sample imaging plate has potential for gamma-ray-computed radiography and dosimetry applications.« less

Photorefractive Effect in Barium Titanate Crystals

DTIC Science & Technology

1988-08-15

photorefractivity. The titanium dioxide feed material was prepared by the hydrolysis of titanium isopropoxide , Ti(ioc3H7 )4 , according to the reaction...reduced pressure fractional distillation. This purification technique was based on the observation that titanium isopropoxide has a much lower boiling...Starting materials A major effort in this research was devoted to the synthesis of high-purity starting materials, since titanium dioxide and barium

Multi-Step Crystallization of Barium Carbonate: Rapid Interconversion of Amorphous and Crystalline Precursors.

PubMed

Whittaker, Michael L; Smeets, Paul J M; Asayesh-Ardakani, Hasti; Shahbazian-Yassar, Reza; Joester, Derk

2017-12-11

The direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate (herewith named gortatowskite) within a few hundred milliseconds of formation, is described. In situ X-ray scattering, cryo-, and low-dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 μm in width, yet only about 10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds. We describe a bulk synthesis and report a first assessment of the composition, vibrational spectra, and structure of gortatowskite. Our findings indicate that transient amorphous and crystalline precursors can play a role in aqueous precipitation pathways that may often be overlooked owing to their extremely short lifetimes and small dimensions. However, such transient precursors may be integral to the formation of more stable phases. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multiple electrical phase transitions in Al substituted barium hexaferrite

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Supriya, Sweety; Kar, Manoranjan

2017-12-01

Barium hexaferrite is known to be a very good ferromagnetic material. However, it shows very good dielectric properties, i.e., the dielectric constant is comparable to that of the ferroelectric material. However, its crystal symmetry does not allow it to be a ferroelectric material. Hence, the electrical properties have revived the considerable research interest on these materials, not only for academic interest, but also for technological applications. There are a few reports on temperature dependent dielectric behavior of these materials. However, the exact cause of dielectric as well as electrical conductivity is yet to be established. Hence, Al (very good conducting material) substituted barium hexaferrite (BaFe12-xAlxO19, x = 0.0-4.0) has been prepared by following the modified sol-gel method to understand the ac and DC electrical properties of these materials. The crystal structure and parameters have been studied by employing the XRD and FTIR techniques. There are two transition temperatures, which have been observed in the temperature dependent ac dielectric and DC resistivity measurement. The response of dielectric behaviors to temperature is similar to that of the ferroelectric material; however, the dielectric polarization is due to the polaron hopping, which is evident from the DC resistivity analysis. Hence, the present observations lead to understand the electrical properties of barium hexaferrite. The frequency dependent dielectric dispersion can be understood by the modified Debye model. More interestingly, the dielectric constant decreases and DC resistivity increases with the increase in the Al concentration, which has the correlation between bond length modifications in the crystal due to substitution.

Shallow-trap-induced positive absorptive two-beam coupling 'gain' and light-induced transparency in nominally undoped barium titanate

NASA Technical Reports Server (NTRS)

Garrett, M. H.; Tayebati, P.; Chang, J. Y.; Jenssen, H. P.; Warde, C.

1992-01-01

The asymmetry of beam coupling with respect to the orientation of the polar axis in a nominally undoped barium titanate crystal is used to determine the electro-optic and absorptive 'gain' in the usual beam-coupling geometry. For small grating wave vectors, the electrooptic coupling vanishes but the absorptive coupling remains finite and positive. Positive absorptive coupling at small grating wave vectors is correlated with the light-induced transparency of the crystal described herein. The intensity and grating wave vector dependence of the electrooptic and absorptive coupling, and the light-induced transparency are consistent with a model incorporating deep and shallow levels.

Li{sub 2}Sr{sub 4}B{sub 12}O{sub 23}: A new alkali and alkaline-earth metal mixed borate with [B{sub 10}O{sub 18}]{sup 6-} network and isolated [B{sub 2}O{sub 5}]{sup 4-} unit

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

Zhang Min; Graduate University of Chinese Academy of Sciences, Beijing 100049; Pan Shilie, E-mail: slpan@ms.xjb.ac.cn

2012-06-15

A novel ternary lithium strontium borate Li{sub 2}Sr{sub 4}B{sub 12}O{sub 23} crystal with size up to 20 mm Multiplication-Sign 10 mm Multiplication-Sign 4 mm has been grown via the top-seeded solution growth method below 730 Degree-Sign C. Single-crystal XRD analyses showed that Li{sub 2}Sr{sub 4}B{sub 12}O{sub 23} crystallizes in the monoclinic space group P2{sub 1}/c with a=6.4664(4) A, b=8.4878(4) A, c=15.3337(8) A, {beta}=102.02(3) Degree-Sign , Z=2. The crystal structure is composed of [B{sub 10}O{sub 18}]{sup 6-} network and isolated [B{sub 2}O{sub 5}]{sup 4-} unit. The IR spectrum further confirmed the presence of both BO{sub 3} and BO{sub 4} groups. TG-DSCmore » and Transmission spectrum were reported. Band structures and density of states were calculated. - Graphical abstract: A new phase, Li{sub 2}Sr{sub 4}B{sub 12}O{sub 23}, has been discovered in the ternary M{sub 2}O-M Prime O-B{sub 2}O{sub 3} (M=alkali-metal, M Prime =alkalineearth metal) system. The crystal structure consists of [B{sub 10}O{sub 18}]{sup 6-} network and isolated [B{sub 2}O{sub 5}]{sup 4-} unit. Highlights: Black-Right-Pointing-Pointer Li{sub 2}Sr{sub 4}B{sub 12}O{sub 23} is a a novel borate discovered in the M{sub 2}O-M Prime O-B{sub 2}O{sub 3} (M=alkali-metal, M Prime =alkaline-earth metal) system. Black-Right-Pointing-Pointer Li{sub 2}Sr{sub 4}B{sub 12}O{sub 23} crystal structure has a three-dimensional crystal structure with [B{sub 10}O{sub 18}]{sup 6-} network and isolated [B{sub 2}O{sub 5}]{sup 4-} unit. Black-Right-Pointing-Pointer Sr{sub 1} and Sr{sub 2} are located in two different channels constructed by {sup 3}{sub {infinity}}[B{sub 10}O{sub 18}] network.« less

Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations

DOE PAGES

Bracco, Jacquelyn N.; Lee, Sang Soo; Stubbs, Joanne E.; ...

2017-05-11

The three-dimensional structure of the barite (001)-water interface was studied using in situ specular and non-specular X-ray reflectivity (XR). Displacements of the barium and sulfate ions in the surface of a barite crystal and the interfacial water structure were defined in the analyses. The largest relaxations (0.13 Å lateral and 0.08 Å vertical) were observed for the barium and sulfate ions in the topmost unit cell layer, which diminished rapidly with depth. The best fit structure identified four distinct adsorbed species, which in comparison with molecular dynamics (MD) simulations, reveals that they are associated with positions of adsorbed water, eachmore » of which coordinates one or two surface ions (either barium, sulfate, or both). These water molecules also adsorb in positions consistent with those of bariums and sulfates in the bulk crystal lattice. These results demonstrate the importance of combining high resolution XR with MD simulations to fully describe the atomic structure of the hydrated mineral surface. As a result, the agreement between the results indicates both the uniqueness of the structural model obtained from the XR analysis and the accuracy of the force field used in the simulations.« less

Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations

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

Bracco, Jacquelyn N.; Lee, Sang Soo; Stubbs, Joanne E.

The three-dimensional structure of the barite (001)-water interface was studied using in situ specular and non-specular X-ray reflectivity (XR). Displacements of the barium and sulfate ions in the surface of a barite crystal and the interfacial water structure were defined in the analyses. The largest relaxations (0.13 Å lateral and 0.08 Å vertical) were observed for the barium and sulfate ions in the topmost unit cell layer, which diminished rapidly with depth. The best fit structure identified four distinct adsorbed species, which in comparison with molecular dynamics (MD) simulations, reveals that they are associated with positions of adsorbed water, eachmore » of which coordinates one or two surface ions (either barium, sulfate, or both). These water molecules also adsorb in positions consistent with those of bariums and sulfates in the bulk crystal lattice. These results demonstrate the importance of combining high resolution XR with MD simulations to fully describe the atomic structure of the hydrated mineral surface. As a result, the agreement between the results indicates both the uniqueness of the structural model obtained from the XR analysis and the accuracy of the force field used in the simulations.« less

Growth and characterisation of a new polymorph of barium maleate: a metal organic framework.

PubMed

Nair, Lekshmi P; Bijini, B R; Prasanna, S; Eapen, S M; Nair, C M K; Deepa, M; RajendraBabu, K

2015-02-25

A new polymorph of barium maleate (BM) with chemical formula C24H14O24Ba5⋅7H2O is grown by modified gel method. Transparent plate like crystals of dimensions 9×4×1 mm(3) were obtained. Single crystal X-ray Diffraction analysis was done to determine the structure and the crystal belongs to triclinic system, P-1 space group with cell dimensions a=7.2929(3) Å, b=10.5454(4) Å, c=14.2837(6) Å, α=102.0350(10)°, β=99.1580(10)°, γ=102.9170(10)°. Hydrogen bonding stabilises the two dimensional polymeric crystal structure. Fourier Transform Infrared spectroscopic method was utilised for the analysis of various functional groups present in the complex. Elemental analysis confirmed the stoichiometry of the complex. Thermal properties of the crystal were studied by TGA/DTA. The material melts at 368°C. The optical transparency of the crystal was studied using UV-Visible absorption spectra. The optical band gap is found to be 3.35 eV. Copyright © 2014 Elsevier B.V. All rights reserved.

Zirconium fluoride glass - Surface crystals formed by reaction with water

NASA Technical Reports Server (NTRS)

Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

1984-01-01

The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

Growth of crystals for synchrotron radiation Mössbauer investigation

NASA Astrophysics Data System (ADS)

Kotrbova, M.; Hejduk, J.; Malnev, V. V.; Seleznev, V. N.; Yagupov, S. V.; Andronova, N. V.; Chechin, A. I.; Mikhailov, A. Yu.

1991-10-01

Iron borate crystals (FeBO 3) were flux grown at the Physical Institute (Prague) and at Simferopol State University. During the crystal growth procedure the temperature regime was held constant to 0.1°C accuracy. Crystals were investigated with the help of a double crystal X-ray diffractometer DRON-2 (SiO 2(30 overline33)FeBO 3(444), MoK α 1 radiation). The rocking curve measurements were carried out in a constant magnetic field of 1kG. Most of the crystal surface has a rocking curve 10″-15″ wide. Some parts of some crystals with the area 1 × 1 mm 2 have rocking curves of 3″-4″ width and can be considered ideal.

Reaction of sodium calcium borate glasses to form hydroxyapatite.

PubMed

Han, Xue; Day, Delbert E

2007-09-01

This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction was between either 1CaO . 2Na(2)O . 6B(2)O(3) or 2CaO . 2Na(2)O . 6B(2)O(3) glass and a 0.25 M phosphate (K(2)HPO(4)) solution at 37, 75 and 200 degrees C. Glass samples in the form of irregular particles (125-180 microm) and microspheres (45-90 and 125-180 microm) were used in order to understand the reaction mechanism. The effect of glass composition (calcium content) on the weight loss rate and reaction temperature on crystal size, crystallinity and grain shape of the reaction products were studied. Carbonated HA was made by dissolving an appropriate amount of carbonate (K(2)CO(3)) in the 0.25 M phosphate solution. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the reaction products. The results show that sodium calcium borate glasses can be transformed to HA by reacting with a phosphate solution. It is essentially a process of dissolution of glass and precipitation of HA. The transformation begins from an amorphous state to calcium-deficient HA without changing the size and shape of the original glass sample. Glass with a lower calcium content (1CaO . 2Na(2)O . 6B(2)O(3)), or reacted at an elevated temperature (75 degrees C), has a higher reaction rate. The HA crystal size increases and grain shape changes from spheroidal to cylindrical as temperature increases from 37 to 200 degrees C. Increase in carbonate concentration can also decrease the crystal size and yield a more needle-like grain shape.

N,N,N′,N′,N′′-Penta­methyl-N′′-[3-(1,3,3-trimethyl­ureido)prop­yl]guanidinium tetra­phenyl­borate

PubMed Central

Tiritiris, Ioannis; Kantlehner, Willi

2012-01-01

In the crystal structure of the title molecular salt, C13H30N5O+·C24H20B−, discrete guanidinium cations and tetra­phenyl­borate anions are present. The C—N bond lengths in the CN3 unit are 1.3427 (12), 1.3445 (12) and 1.3453 (13) Å, indicating double-bond character. The central C atom is surrounded in a nearly ideal trigonal-planar geometry by three N atoms and the positive charge is delocalized on the CN3 plane. The bonds between the N atoms and the terminal C-methyl groups all have values close to a typical single bond [1.4595 (15)–1.4688 (12) Å]. In the crystal, cations are connected by C—H⋯O contacts generating a chain along the c axis. PMID:22798881

Reactivity of cyclopentadienyl transition metal(ii) complexes with borate ligands: structural characterization of the toluene-activated molybdenum complex [Cp*Mo(CO)2(η3-CH2C6H5)].

PubMed

Ramalakshmi, Rongala; Maheswari, K; Sharmila, Dudekula; Paul, Anamika; Roisnel, Thierry; Halet, Jean-François; Ghosh, Sundargopal

2016-10-18

Reactions of cyclopentadienyl transition-metal halide complexes [Cp*Mo(CO) 3 Cl], 1, and [CpFe(CO) 2 I], 2, (Cp = C 5 H 5 ; Cp* = η 5 -C 5 Me 5 ) with borate ligands are reported. Treatment of 1 with [NaBt 2 ] (Bt 2 = dihydrobis(2-mercapto-benzothiazolyl)borate) in toluene yielded [Cp*Mo(CO) 2 (C 7 H 4 S 2 N)], 3, and [Cp*Mo(CO) 2 (η 3 -CH 2 C 6 H 5 )], 4, with a selective binding of toluene through C-H activation followed by orthometallation. Note that compound 4 is a structurally characterized toluene-activated molecule in which the metal is in η 3 -coordination mode. Under similar reaction conditions, [NaPy 2 ] (Py 2 = dihydrobis(2-mercaptopyridyl)borate) produced only the mercaptopyridyl molybdenum complex [Cp*Mo(CO) 2 (C 5 H 4 SN)], 5, in good yield. On the other hand, when compound 2 was treated individually with [NaBt] (Bt = trihydro(2-mercapto-benzothiazolyl)borate) and [NaPy 2 ] in THF, formation of the η 1 -coordinated complexes [CpFe(CO) 2 (C 7 H 4 S 2 N)], 6, and [CpFe(CO) 2 (C 5 H 4 SN)], 7, was observed. The solid-state molecular structures of compounds 3, 4, 6, and 7 have been established by single-crystal X-ray crystallographic analyses.

Investigation of the photosensitivity of LiNbO3:BaFeO3 crystal

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Koplitz, Brent D.; Jackson, E.; Jalbout, F.; Jalbout, A.; Aggarwal, Mohan D.

2002-01-01

Ferromagnetic resonance (FMR) absorptions from six fine particle-samples of barium ferrite were studied over a temperature range of -195 degree(s)C to 500 degree(s)C. It was found that the shape of the FMR absorption signal is affected by the particle shape and crystalline anisotropy of each sample. From this analysis, the first magnetic anisotropy constant K1 was estimated approximately as a function of temperature. The estimation suggested that the value of K1 was sensitive to the condition of preparation of fine powders. In addition the photosensitivity of the LiNbO3:BaFe doped crystal was enhanced, suggesting the importance of Barium Ferrite powder as a potential candidate with NOL materials.

A Non-Linear Model for Elastic Dielectric Crystals with Mobile Vacancies

DTIC Science & Technology

2009-07-01

crystals, vacancies typically carry an electric charge [18,37]. Such charged vacancies notably influence dielectric properties and elec- trical loss...characteristics of capacitors, oscillators, and tunable fil- ters [19], for example those comprised of perovskite ceramic crystals such as barium titanate...thermomechanical and thermoelectrical couplings, respectively, and the final term capturing non-mechanical sources of heat energy. 3.3. Representative free energy

Influence of barium substitution on bioactivity, thermal and physico-mechanical properties of bioactive glass.

PubMed

Arepalli, Sampath Kumar; Tripathi, Himanshu; Vyas, Vikash Kumar; Jain, Shubham; Suman, Shyam Kumar; Pyare, Ram; Singh, S P

2015-04-01

Barium with low concentration in the glasses acts as a muscle stimulant and is found in human teeth. We have made a primary study by substituting barium in the bioactive glass. The chemical composition containing (46.1-X) SiO2--24.3 Na2O-26.9 CaO-2.6 P2O5, where X=0, 0.4, 0.8, 1.2 and 1.6mol% of BaO was chosen and melted in an electric furnace at 1400±5°C. The glasses were characterized to determine their use in biomedical applications. The nucleation and crystallization regimes were determined by DTA and the controlled crystallization was carried out by suitable heat treatment. The crystalline phase formed was identified by using XRD technique. Bioactivity of these glasses was assessed by immersion in simulated body fluid (SBF) for various time periods. The formation of hydroxy carbonate apatite (HCA) layer was identified by FTIR spectrometry, scanning electron microscope (SEM) and XRD which showed the presence of HCA as the main phase in all tested bioactive glass samples. Flexural strength and densities of bioactive glasses have been measured and found to increase with increasing the barium content. The human blood compatibility of the samples was evaluated and found to be pertinent. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Cao, Jianjun; Shen, Dongyi; Feng, Yaming

Negative refraction has attracted much interest for its promising capability in imaging applications. Such an effect can be implemented by negative index meta-materials, however, which are usually accompanied by high loss and demanding fabrication processes. Recently, alternative nonlinear approaches like phase conjugation and four wave mixing have shown advantages of low-loss and easy-to-implement, but associated problems like narrow accepting angles can still halt their practical applications. Here, we demonstrate theoretically and experimentally a scheme to realize negative refraction by nonlinear difference frequency generation with wide tunability, where a thin Beta barium borate slice serves as a negative refraction layer bendingmore » the input signal beam to the idler beam at a negative angle. Furthermore, we realize optical focusing effect using such nonlinear negative refraction, which may enable many potential applications in imaging science.« less

Precipitation method for barium metaborate (BaB2O4) synthesis from borax solution

NASA Astrophysics Data System (ADS)

Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

2013-12-01

In this study, barium metaborate (BaB2O4, BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also β-BaB2O4 single crystals are the best candidate for fabrication of solid-state UV lasers operating at a wavelength of 200 nm due to excellent nonlinear optical properties. In the present study, synthesis was carried out from the borax solution (Na2B4O7ṡ10H2O, BDH) and barium chloride (BaCI2ṡ2H2O, Ba) in the glass-batch reactor with stirring. The effect of, times (5-15 min), molar ratio [stoich.ration (1.0:2.0), 1.25:2.0, 1.5:2.0, 2.5:2:0, 3.0:2.0, 3.5:2.0,4.0:2.0, 5.0:2.0] and also crystallization time (2-6 hour) on the BMB yield (%) was investigated at 80 °C reaction temperature. It is found that, BMB precipitation synthesis with 90 % yield can be performed from 0.50 molar ration (BDH:Ba), under 80 °C, 15 minute, and 6 hours crystallization time. The structural properties of BMB powders were characterized by using XRD, FT-IR and DTA-TG instrumental analysis technique.

Growth and optical property characterization of textured barium titanate thin films for photonic applications

NASA Astrophysics Data System (ADS)

Dicken, Matthew J.; Diest, Kenneth; Park, Young-Bae; Atwater, Harry A.

2007-03-01

We have investigated the growth of barium titanate thin films on bulk crystalline and amorphous substrates utilizing biaxially oriented template layers. Ion beam-assisted deposition was used to grow thin, biaxially textured, magnesium oxide template layers on amorphous and silicon substrates. Growth of highly oriented barium titanate films on these template layers was achieved by molecular beam epitaxy using a layer-by-layer growth process. Barium titanate thin films were grown in molecular oxygen and in the presence of oxygen radicals produced by a 300 W radio frequency plasma. We used X-ray and in situ reflection high-energy electron diffraction (RHEED) to analyze the structural properties and show the predominantly c-oriented grains in the films. Variable angle spectroscopic ellipsometry was used to analyze and compare the optical properties of the thin films grown with and without oxygen plasma. We have shown that optical quality barium titanate thin films, which show bulk crystal-like properties, can be grown on any substrate through the use of biaxially oriented magnesium oxide template layers.

Crystal growth, differential gas adsorption, high thermal stability, and reversible coordination of two new barium-organic frameworks, Ba(SBA)(DMF){sub 4} and Ba{sub 2}(BTEC)(H{sub 2}O)

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

Halake, Shobha; Ok, Kang Min, E-mail: kmok@cau.ac.kr

2015-11-15

Single crystals of two barium-organic framework materials, Ba(SBA)(DMF){sub 4} (CAUMOF-15) and Ba{sub 2}(BTEC)(H{sub 2}O) (CAUMOF-16), have been grown through solvothermal reactions (H{sub 2}SBA=4,4′-sulfonyldibenzoic acid and H{sub 4}BTEC=1,2,4,5-benzenetetracarboxylic acid). The crystal structures of the reported frameworks have been determined by single-crystal X-ray diffraction. The materials have been fully characterized by powder X-ray diffraction (PXRD), elemental analyses, Infrared (IR) spectroscopy, and thermogravimetric analyses (TGA). CAUMOF-15 reveals a three-dimensional open-framework that comprises of an inorganic motif with one-dimensional chains and the SBA linkers. CAUMOF-16 shows another three-dimensional backbone consisting of layers of edge-shared BaO{sub 9} and BaO{sub 10} polyhedra, and BTEC pillars. Bothmore » of the 3D frameworks exhibit relatively high thermal stabilities. The PXRD and IR spectral data confirm that CAUMOF-15 and CAUMOF-16 reveal reversible coordinations of the respective solvent molecules, DMF and H{sub 2}O. Gas adsorption properties towards nitrogen, hydrogen, and carbon dioxide have been also investigated. - Graphical abstract: Crystals of two new barium-organic frameworks, Ba(SBA)(DMF){sub 4} and Ba{sub 2}(BTEC)(H{sub 2}O), exhibiting a differential gas adsorption, a high thermal stability, and a reversible coordination of solvent molecules have been grown. - Highlights: • Crystals of two new 3D Ba-MOFs are grown. • The two Ba-MOFs reveal very high thermal stabilities up to ca. 400 °C. • Ba(SBA)(DMF){sub 4} exhibits differential gas adsorption properties. • The two Ba-MOFs show reversible coordination of the solvent molecules.« less

Ferromagnetic resonance in a single crystal of iron borate and magnetic field tuning of hybrid oscillations in a composite structure with a dielectric: Experiment and theory

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

Popov, M. A.; Zavislyak, I. V.; Chumak, H. L.

2015-07-07

The high-frequency properties of a composite resonator comprised single crystal iron borate (FeBO{sub 3}), a canted antiferromagnet with a weak ferromagnetic moment, and a polycrystalline dielectric were investigated at 9–10 GHz. Ferromagnetic resonance in this frequency range was observed in FeBO{sub 3} for bias magnetic fields of ∼250 Oe. In the composite resonator, the magnetic mode in iron borate and dielectric mode are found to hybridize strongly. It is shown that the hybrid mode can be tuned with a static magnetic field. Our studies indicate that coupling between the magnetic mode and the dielectric resonance can be altered from maximum hybridization tomore » a minimum by adjusting the position of resonator inside the waveguide. Magnetic field tuning of the resonance frequency by a maximum of 145 MHz and a change in the transmitted microwave power by as much as 16 dB have been observed for a bias field of 250 Oe. A model is discussed for the magnetic field tuning of the composite resonator and theoretical estimates are in reasonable agreement with the data. The composite resonator with a weak ferromagnet and a dielectric is of interest for application in frequency agile devices with electronically tunable electrodynamic characteristics for the mm and sub-mm wave bands.« less

Comparative analysis of ferroelectric domain statistics via nonlinear diffraction in random nonlinear materials.

PubMed

Wang, B; Switowski, K; Cojocaru, C; Roppo, V; Sheng, Y; Scalora, M; Kisielewski, J; Pawlak, D; Vilaseca, R; Akhouayri, H; Krolikowski, W; Trull, J

2018-01-22

We present an indirect, non-destructive optical method for domain statistic characterization in disordered nonlinear crystals having homogeneous refractive index and spatially random distribution of ferroelectric domains. This method relies on the analysis of the wave-dependent spatial distribution of the second harmonic, in the plane perpendicular to the optical axis in combination with numerical simulations. We apply this technique to the characterization of two different media, Calcium Barium Niobate and Strontium Barium Niobate, with drastically different statistical distributions of ferroelectric domains.

Study of the photovoltaic effect in thin film barium titanate

NASA Technical Reports Server (NTRS)

Grannemann, W. W.; Dharmadhikari, V. S.

1982-01-01

Ferroelectric films of barium titanate were synthesized on silicon and quartz substrates, and the photoelectric effect in the structure consisting of metal deposited ferroelectric barium titanate film silicon was studied. A photovoltage with polarity that depends on the direction of the remanent polarization was observed. The deposition of BaTiO3 on silicon and fused quartz substrates was accomplished by an rf sputtering technique. A series of experiments to study the growth of ferroelectric BaTiO3 films on single crystal silicon and fused quartz substrates were conducted. The ferroelectric character in these films was found on the basis of evidence from the polarization electric field hysteresis loops, capacitance voltage and capacitance temperature techniques and from X-ray diffraction studies.

Hydrothermal Crystal Growth of Lithium Tetraborate and Lithium Gamma-Metaborate

DTIC Science & Technology

2014-03-27

could be atomic nuclei, the center of mass of some complex—those details are immaterial. Both the rectangle and lozenge form potential cross-sections...HR y d L Figure 10. The red lines are the various contours of solution of 9, using a = 10 Bohr radii and the mass of coefficients on the LHS forced to...absorptivity is significantly below that of the transition metals or the actinides [9]. The lithium borate crystals are therefore a strong candidate for

Synthesis of barium and strontium carbonate crystals with unusual morphologies using an organic additive

NASA Astrophysics Data System (ADS)

Chen, Long; Jiang, Jizhong; Bao, Zuben; Pan, Jian; Xu, Weibing; Zhou, Lili; Wu, Zhigang; Chen, Xu

2013-12-01

In this paper, strontium carbonate (SrCO3) and barium carbonate (BaCO3) crystals were synthesized in the presence of an organic additive-hexamethylenetetramine (HMT) using two CO2 sources. Scanning electron microscopy and X-ray powder diffractometry were used to characterize the products. The results showed that the morphologies of orthorhombic strontianite SrCO3 transformed from branch-like to flower-like, and to capsicum-like at last, while the morphologies of BaCO3 change from fiber-like to branchlike, and to rod-like finally with an increase of the molar ratio HMT/Sr2+ and HMT/Ba2+ from 0.2 to 10 using ammonium carbonate as CO2 source. When using diethyl carbonate instead of ammonium carbonate as CO2 source, SrCO3 flowers aggregated by rods and BaCO3 shuttles were formed. The possible formation mechanisms of SrCO3 and BaCO3 crystals obtained in different conditions were also discussed.

Laser stimulated third harmonic generation studies in ZnO-Ta2O5-B2O3 glass ceramics entrenched with Zn3Ta2O8 crystal phases

NASA Astrophysics Data System (ADS)

Siva Sesha Reddy, A.; Jedryka, J.; Ozga, K.; Ravi Kumar, V.; Purnachand, N.; Kityk, I. V.; Veeraiah, N.

2018-02-01

In this study zinc borate glasses doped with different concentrations Ta2O5 were synthesized and were crystallized by heat treatment for prolonged times. The samples were characterized by XRD, SEM, IR and Raman spectroscopy techniques. The SEM images of the crystallized samples have indicated that the samples contain randomly distributed crystal grains with size ∼1 μm entrenched in the residual amorphous phase. XRD studies have exhibited diffraction peaks identified as being due to the reflections from (1 1 1) planes of monoclinic Zn3Ta2O8 crystal phase that contains intertwined tetrahedral zinc and octahedral tantalate structural units. The concentration of such crystal phases in the bulk samples is observed to increase with increase of Ta2O5 up to 3.0 mol%. The IR and Raman spectroscopy studies have confirmed the presence of ZnO4 and TaO6 structural units in the glass network in addition to the conventional borate structural units. For measuring third harmonic generation (THG) in the samples, the samples were irradiated with 532 nm laser beam and the intensity of THG of probing beam (Nd:YAG λ = 1064 nm 20 ns pulsed laser (ω)) is measured as a function of fundamental beam power varying up to 200 J/m2. The intensity of THG is found to be increasing with increase of fundamental beam power and found to be the maximal for the glass crystallized with 3.0 mol% of Ta2O5. The intensity of THG of the ceramicized samples is found to be nearly 5 times higher with respect to that of pre-crystallized samples. The generation of 3ω is attributed to the perturbation/interaction between Zn3Ta2O8 anisotropic crystal grains and the incident probing beam.

Crystal structure of N′′-benzyl-N′′-[3-(benzyl­dimethyl­aza­nium­yl)prop­yl]-N,N,N′,N′-tetra­methyl­guanidinium bis­(tetra­phenyl­borate)

PubMed Central

Tiritiris, Ioannis; Kantlehner, Willi

2015-01-01

In the crystal structure of the title salt, C24H38N4 2+·2C24H20B−, the C—N bond lengths in the central CN3 unit of the guanidinium ion are 1.3364 (13), 1.3407 (13) and 1.3539 (13) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3 plane. The bonds between the N atoms and the terminal methyl groups of the guanidinium moiety and the four C—N bonds to the central N atom of the (benzyl­dimethyl­aza­nium­yl)propyl group have single-bond character. In the crystal, C—H⋯π inter­actions between the guanidin­ium H atoms and the phenyl C atoms of the tetra­phenyl­borate ions are present, leading to the formation of a two-dimensional supra­molecular pattern parallel to the ac plane. PMID:26870511

Crystallization of a barium-aluminosilicate glass

NASA Technical Reports Server (NTRS)

Drummond, C. H., III; Lee, W. E.; Bansal, N. P.; Hyatt, M. J.

1989-01-01

The crystallization of a celsian glass composition was investigated as a possible high-temperature ceramic matrix material. Heat treatments invariably resulted in crystallization of the hexaclesian phase unless a flux, such as lithia, was added or a nucleating agent used (e.g., celsian seeds). TEM analysis revealed complex microstructures. Glasses with Mo additions contained hexacelsian, mullite, and an Mo-rich glass. Li2O additions stabilized celsian but mullite and Mo-rich glass were still present.

The crystallization behavior and kinetics of a barium fluorozirconate type glass

NASA Technical Reports Server (NTRS)

Neilson, G. F.; Smith, G. L.; Weinberg, M. C.

1984-01-01

An investigation of the crystallization behavior of a Zr-Ba-La-Al-F glass which is subjected to isothermal heat treatments is presented. The number and nature of the crystalline phases which form and their nucleation sites are determined at three temperatures. Also, the growth rate and volume fraction of crystals which nucleate internally in the glass, when heated at 320 C, are determined as a function of time.

XRD and FTIR studies the effect of heat treatment and doping the transition metal oxide on LiNbO3 and LiNb3O8 nano-crystallite phases in lithium borate glass system.

PubMed

Kashif, Ismail; Soliman, Ashia A; Sakr, Elham M; Ratep, Asmaa

2013-09-01

Glasses of various compositions in the system 90 Li2B4O7-10 Nb2O5 mixed with T.M ions (where T.M is the transition metal) were prepared by quenching technique. Heat-treatment of the parent glasses was performed at 540, 570 and 620 °C, for 5 and 16 h. The glass structure evolution during the controlled crystallization was examined by XRD and FT-IR spectroscopy analysis. The crystalline phases present in the glass ceramics were identified via X-ray diffraction as a function of heat treatment. The FT-IR data propose for these glasses and heat-treated glass network structures mainly built by: di-, tri-, tetra-, penta-and ortho-borate groups. It was found that the quantitative evolution of these various borate species in the glass structures is influenced by the transition metal. A detailed discussion relating to the N4 evolution with the T.M content was made. Copyright © 2013 Elsevier B.V. All rights reserved.

Facile Synthesis of Calcium Borate Nanoparticles and the Annealing Effect on Their Structure and Size

PubMed Central

Erfani, Maryam; Saion, Elias; Soltani, Nayereh; Hashim, Mansor; Wan Abdullah, Wan Saffiey B.; Navasery, Manizheh

2012-01-01

Calcium borate nanoparticles have been synthesized by a thermal treatment method via facile co-precipitation. Differences of annealing temperature and annealing time and their effects on crystal structure, particle size, size distribution and thermal stability of nanoparticles were investigated. The formation of calcium borate compound was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Thermogravimetry (TGA). The XRD patterns revealed that the co-precipitated samples annealed at 700 °C for 3 h annealing time formed an amorphous structure and the transformation into a crystalline structure only occurred after 5 h annealing time. It was found that the samples annealed at 900 °C are mostly metaborate (CaB2O4) nanoparticles and tetraborate (CaB4O7) nanoparticles only observed at 970 °C, which was confirmed by FTIR. The TEM images indicated that with increasing the annealing time and temperature, the average particle size increases. TGA analysis confirmed the thermal stability of the annealed samples at higher temperatures. PMID:23203073

Bioaccessibility of barium from barite contaminated soils based on gastric phase in vitro data and plant uptake.

PubMed

Abbasi, Sedigheh; Lamb, Dane T; Palanisami, Thavamani; Kader, Mohammed; Matanitobua, Vitukawalu; Megharaj, Mallavarapu; Naidu, Ravi

2016-02-01

Barite contamination of soil commonly occurs from either barite mining or explorative drilling operations. This work reported in vitro data for barite contaminated soils using the physiologically based extraction test (PBET) methodology. The existence of barite in plant tissue and the possibility of 'biomineralised' zones was also investigated using Scanning Electron Microscopy. Soils with low barium (Ba) concentrations showed a higher proportion of Ba extractability than barite rich samples. Barium uptake to spinach from soil was different between short term spiking studies and field weathered soils. Furthermore, Ba crystals were not evident in spinach tissue or acid digest solutions grown in barium nitrate spiked soils despite high accumulation. Barite was found in the plant digest solutions from barite contaminated soils only. Results indicate that under the conservative assumptions made, a child would need to consume extreme quantities of soil over an extended period to cause chronic health problems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Barium Titanate Nanoparticles for Biomarker Applications

NASA Astrophysics Data System (ADS)

Matar, O.; Posada, O. M.; Hondow, N. S.; Wälti, C.; Saunders, M.; Murray, C. A.; Brydson, R. M. D.; Milne, S. J.; Brown, A. P.

2015-10-01

A tetragonal crystal structure is required for barium titanate nanoparticles to exhibit the nonlinear optical effect of second harmonic light generation (SHG) for use as a biomarker when illuminated by a near-infrared source. Here we use synchrotron XRD to elucidate the tetragonal phase of commercially purchased tetragonal, cubic and hydrothermally prepared barium titanate (BaTiO3) nanoparticles by peak fitting with reference patterns. The local phase of individual nanoparticles is determined by STEM electron energy loss spectroscopy (EELS), measuring the core-loss O K-edge and the Ti L3-edge energy separation of the t2g, eg peaks. The results show a change in energy separation between the t2g and eg peak from the surface and core of the particles, suggesting an intraparticle phase mixture of the barium titanate nanoparticles. HAADF-STEM and bright field TEM-EDX show cellular uptake of the hydrothermally prepared BaTiO3 nanoparticles, highlighting the potential for application as biomarkers.

Theoretical study of phonon dispersion, elastic, mechanical and thermodynamic properties of barium chalcogenides

NASA Astrophysics Data System (ADS)

Musari, A. A.; Orukombo, S. A.

2018-03-01

Barium chalcogenides are known for their high-technological importance and great scientific interest. Detailed studies of their elastic, mechanical, dynamical and thermodynamic properties were carried out using density functional theory and plane-wave pseudo potential method within the generalized gradient approximation. The optimized lattice constants were in good agreement when compared with experimental data. The independent elastic constants, calculated from a linear fit of the computed stress-strain function, were used to determine the Young’s modulus (E), bulk modulus (B), shear modulus (G), Poisson’s ratio (σ) and Zener’s anisotropy factor (A). Also, the Debye temperature and sound velocities for barium chalcogenides were estimated from the three independent elastic constants. The calculations of phonon dispersion showed that there are no negative frequencies throughout the Brillouin zone. Hence barium chalcogenides have dynamically stable NaCl-type crystal structure. Finally, their thermodynamic properties were calculated in the temperature range of 0-1000 K and their constant-volume specific heat capacities at room-temperature were reported.

Chem 13 News Digest

ERIC Educational Resources Information Center

Friesen, R. J., Ed.

1975-01-01

Describes an experiment, using a soap bubble raft, intended to provide insight into the orderly packing of spherical objects and the properties of metallic crystals. Also describes a solubility product experiment which uses barium hydroxide. (MLH)

Two Barium Gold Iodates: Syntheses, Structures, and Properties of Polar BaAu(IO3)5 and Nonpolar HBa4Au(IO3)12 Materials.

PubMed

Yang, Bing-Ping; Hu, Chun-Li; Mao, Fei-Fei; Xu, Xiang; Mao, Jiang-Gao

2017-06-19

Two new barium gold iodates, namely, BaAu(IO 3 ) 5 and HBa 4 Au(IO 3 ) 12 , have been prepared. BaAu(IO 3 ) 5 crystallizes in the polar space group Pca2 1 , whereas HBa 4 Au(IO 3 ) 12 crystallizes in the centrosymmetric space group P2 1 /c. BaAu(IO 3 ) 5 consists of unique polar [Au(IO 3 ) 4 ] - anions whose four iodate groups are located at both sides of the AuO 4 plane and the polarity points in the [001̅] direction. BaAu(IO 3 ) 5 displays strong second-harmonic-generation (SHG) effects about 0.6KTiOPO 4 (KTP) and is phase-matchable. Thermal properties, optical spectra analyses, and theoretical calculations are also reported.

Precipitation method for barium metaborate (BaB{sub 2}O{sub 4}) synthesis from borax solution

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

Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

2013-12-16

In this study, barium metaborate (BaB{sub 2}O{sub 4}, BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also β−BaB{sub 2}O{sub 4} single crystals are the best candidate for fabrication of solid-state UV lasers operating at a wavelength of 200 nm due to excellent nonlinear optical properties. In the present study, synthesis was carried out from the borax solution (Na{sub 2}B{sub 4}O{sub 7⋅}10H{sub 2}O, BDH) and barium chloride (BaCI{sub 2⋅}2H{sub 2}O, Ba) in the glass-batch reactor with stirring.more » The effect of, times (5-15 min), molar ratio [stoich.ration (1.0:2.0), 1.25:2.0, 1.5:2.0, 2.5:2:0, 3.0:2.0, 3.5:2.0,4.0:2.0, 5.0:2.0] and also crystallization time (2-6 hour) on the BMB yield (%) was investigated at 80 °C reaction temperature. It is found that, BMB precipitation synthesis with 90 % yield can be performed from 0.50 molar ration (BDH:Ba), under 80 °C, 15 minute, and 6 hours crystallization time. The structural properties of BMB powders were characterized by using XRD, FT-IR and DTA-TG instrumental analysis technique.« less

Barium Titanate Photonic Crystal Electro-Optic Modulators for Telecommunication and Data Network Applications

NASA Astrophysics Data System (ADS)

Girouard, Peter D.

The microwave, optical, and electro-optic properties of epitaxial barium titanate thin films grown on (100) MgO substrates and photonic crystal electro-optic modulators fabricated on these films were investigated to demonstrate the applicability of these devices for telecommunication and data networks. The electrical and electro-optical properties were characterized up to modulation frequencies of 50 GHz, and the optical properties of photonic crystal waveguides were determined for wavelengths spanning the optical C band between 1500 and 1580 nm. Microwave scattering parameters were measured on coplanar stripline devices with electrode gap spacings between 5 and 12 mum on barium titanate films with thicknesses between 230 and 680 nm. The microwave index and device characteristic impedance were obtained from the measurements. Larger (lower) microwave indices (impedances) were obtained for devices with narrower electrode gap spacings and on thicker films. Thinner film devices have both lower index mismatch between the co-propagating microwave and optical signals and lower impedance mismatch to a 50O system, resulting in a larger predicted electro-optical 3 dB bandwidth. This was experimentally verified with electro-optical frequency response measurements. These observations were applied to demonstrate a record high 28 GHz electro-optic bandwidth measured for a BaTiO3 conventional ridge waveguide modulator having 1mm long electrodes and 12 mum gap spacing on a 260nm thick film. The half-wave voltage and electro-optic coefficients of barium titanate modulators were measured for films having thicknesses between 260 and 500 nm. The half-wave voltage was directly measured at low frequencies using a polarizer-sample-compensator-analyzer setup by over-driving waveguide integrated modulators beyond their linear response regime. Effective in-device electro-optic coefficients were obtained from the measured half-wave voltages. The effective electro-optic coefficients were found to increase with both applied electrical dc bias and with film thickness. A record low 0.39V ˙ cm (0.45V ˙ cm) voltage-length product was measured for barium titanate modulators operating at telecommunication wavelengths on a device with 5 ?m electrode gap spacing on a 500nm thick film modulated at a frequency of 100 Hz (1 MHz). This measured voltage-length product is more than a factor of 5 lower than that reported for state-of-the-art silicon conventional waveguide modulators. The electro-optical characterization of BaTiO3 films revealed a trade-off that exists for traveling wave BaTiO3 modulators: lower voltages are obtained in thicker film devices with narrow electrode gap spacing while larger bandwidths are obtained in thinner film devices with wider electrode gap spacing. These findings were supported by calculations of the film thickness dependent half-wave voltage and electro-optic bandwidth. In order to demonstrate modulators having simultaneously low voltage operation and high electro-optic bandwidth, photonic crystal waveguide modulators with large group index were investigated through theory and experiment. The theory for slow light phase delay in linear optical materials was extended for second order nonlinear optical materials. This theory was incorporated into a detailed model for predicting photonic crystal modulator performance in terms of voltage-length product and electro-optic bandwidth. Modeling shows that barium titanate photonic crystal modulators with sub-millimeter length, sub-volt operation, and greater than 40 GHz electro-optic bandwidth are achievable in a single device. Two types of photonic crystal waveguides (PC) on BaTiO3 films were designed, fabricated, and characterized: waveguides with hexagonal lattice symmetry and waveguides with hexagonal symmetry having a line defect oriented in the direction of light propagation. Excellent agreement was obtained between the simulated and measured transmission for hexagonal lattice PC waveguides. An extinction of 20 dB was measured across a 9.9 nm stop band edge, yielding a record large band edge sharpness of 2 dB/nm for all photonic crystal waveguides on ferroelectric films. A 12-fold enhancement of the electro-optic coefficient was measured via optical spectral analysis in a line defect BaTiO3 modulator, yielding an effective electro-optic coefficient of 900 pm/V in the photonic crystal region at a modulation frequency of 10 GHz. This enhancement was demonstrated over a 48 nm range, demonstrating the wideband operation of these devices.

Order–Disorder Transitions and Superionic Conductivity in the Sodium nido -Undeca(carba)borates

DOE PAGES

Tang, Wan Si; Dimitrievska, Mirjana; Stavila, Vitalie; ...

2017-11-20

The salt compounds NaB 11H 14, Na-7-CB10H13, Li-7-CB 10H 13, Na-7,8-C 2B 9H 12, and Na-7,9-C 2B 9H 12 all contain geometrically similar, monocharged, nido-undeca(carba)borate anions (i.e., truncated icosohedral-shaped clusters constructed of only 11 instead of 12 {B-H} + {C-H} vertices and an additional number of compensating bridging and/or terminal H atoms). We used first-principles calculations, X-ray powder diffraction, differential scanning calorimetry, neutron vibrational spectroscopy, neutron elastic-scattering fixed-window scans, quasielastic neutron scattering, and electrochemical impedance measurements to investigate their structures, bonding potentials, phase-transition behaviors, anion orientational mobilities, and ionic conductivities compared to those of their closo-poly(carba)borate cousins. All exhibited order-disordermore » phase transitions somewhere between room temperature and 375 K. All disordered phases appear to possess highly reorientationally mobile anions (> ~10 10 jumps s -1 above 300 K) and cation-vacancy-rich, close-packed or body-center-cubic-packed structures [like previously investigated closo-poly(carba)borates]. Moreover, all disordered phases display superionic conductivities but with generally somewhat lower values compared to those for the related sodium and lithium salts with similar monocharged 1-CB 9H 10- and CB 11H 12- closo-carbaborate anions. This study significantly expands the known toolkit of solid-state, poly(carba)borate-based salts capable of superionic conductivities and provides valuable insights into the effect of crystal lattice, unit cell volume, number of carbon atoms incorporated into the anion, and charge polarization on ionic conductivity.« less

Hydrothermal synthesis and characterization of the first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3}

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

Ortner, Teresa S.; Wurst, Klaus; Perfler, Lukas

2015-01-15

The first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3} was synthesized under hydrothermal conditions from Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}O and K{sub 2}B{sub 4}O{sub 7}·4H{sub 2}O using KNO{sub 3} as a nitrate source. The compound crystallizes in the space group Pnnm (no. 58) with the lattice parameters a=1320.8(3), b=910.7(2), and c=1232.5(3) pm (Z=4). Isolated Sechserrings formed by BO{sub 4} and BO{sub 3} groups are linked through hydrogen bridges to form a three-dimensional network. - Graphical abstract: The first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3} was synthesized under hydrothermal conditions from Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}Omore » and K{sub 2}B{sub 4}O{sub 7}·4H{sub 2}O using KNO{sub 3} as a nitrate source. - Highlights: • The first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3} is reported. • Hydrothermal conditions (240 °C, 3d) were used for the synthesis of K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3}. • Borate Sechserrings are interconnected through hydrogen-bonding.« less

Tunable Optical Properties and Increased Thermal Quenching in the Blue-Emitting Phosphor Series: Ba 2 (Y 1–x Lu x ) 5 B 5 O 17 :Ce 3+ ( x = 0–1)

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

Hermus, Martin; Phan, Phu-Cuong; Duke, Anna C.

The preparation of cerium-substituted barium lutetium borate, Ba2Lu5B5O17:Ce3+, is achieved using high temperature solid state synthesis. This compound crystallizes in the Ba2Y5B5O17-type structure and shows an efficient blue emission (λmax = 447 nm) when excited by UV-light (λex = 340 nm) with a photoluminescent quantum yield near 90%, a fast luminescence decay time (<40 ns), and a thermal quenching temperature of 452 K. Further, preparing a solid solution following Ba2(Y1–xLux)5B5O17:Ce3+ (x = 0, 0.25, 0.50, 0.75, 1) confirms that all compounds are isostructural and follow Vegard’s law. Substituting Y3+ for Lu3+ yields a nearly constant emission spectrum that blue-shifts bymore » only 9 nm and has a consistent luminescence lifetime across the range prepared. The photoluminescent quantum yield (PLQY) and thermal quenching (T50) of the solid solution, however, are dramatically impacted by the composition, with the PLQY decreasing to ≈70% and the T50 dropping 49 K going from x = 1 to x = 0. These significant changes in the optical properties likely stem from enhanced structural rigidity as the larger, more polarizable Y3+ is substituted for the smaller, harder Lu3+ cation. These results highlight the importance of optimizing chemical bonding to improve a phosphor’s optical properties.« less

Chinese Journal of Lasers (Selected Articles),

DTIC Science & Technology

1986-04-22

properties We first investigated silicate based glasses, then the other inorganic glasses such as borate, phosphate, germanate. tellurate ...of the growth of high melting temperature I.~ oxides, several upward pulling single crystal furnaces with nigh precision mechanical movement and high...automatic electronic weighting systems, and programmable automatic movement correction systems. The reliability of most of these control systems

3-Methyl-4,5-di­hydro­oxazolium tetra­phenyl­borate

PubMed Central

Tiritiris, Ioannis; Saur, Stefan; Kantlehner, Willi

2014-01-01

In the cation of the title salt, C4H8NO+·C24H20B−, the C—N bond lengths are 1.272 (2), 1.4557 (19) and 1.4638 (19) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.3098 (19) Å shows that double-bond character and charge delocalization occurs within the NCO plane of the cation. In the crystal, a C—H⋯π inter­action is present between the methyl­ene H atom of the cation and one phenyl ring of the tetra­phenyl­borate ion. The latter forms an aromatic pocket in which the cation is embedded. PMID:24765023

Preparation, characterization and luminescence properties of a new hydrous red phosphor CaB3 O5 (OH):Eu3+ with different morphologies.

PubMed

Huang, H S; Tang, A J; Yang, C; Jin, H F

2017-03-01

A new borate phosphor CaB 3 O 5 (OH):Eu 3 + with different morphologies was synthesized using a hydrothermal method and its luminescence properties were studied. The effects of surfactants on the crystal structures, morphologies and luminescence properties of the samples were studied. The results showed that the surfactants play an important role in controlling the morphology and improving the luminescence properties of phosphors. The luminescence intensity and R/O(I615/I592) value were enhanced for the prepared sample by adding PEG4000. The prepared sample exhibited a higher R/O than some anhydrous calcium borate phosphors, indicating that this product could serve as a new potential red phosphor. Copyright © 2016 John Wiley & Sons, Ltd.

Growth of EuO Single Crystals at Reduced Temperatures

NASA Astrophysics Data System (ADS)

Besara, Tiglet; Ramirez, Daniel; Whalen, Jeffrey; Siegrist, Theo

Single crystals of Eu1-xBaxO have been grown in a barium-magnesium flux at moderate temperatures up to 1000°C, producing single crystals with barium doping levels ranging from x = 0 . 03 to x = 0 . 25 . Magnetic measurements show that the ferromagnetic Curie temperature TC correlates with the Ba doping levels, and a modified Heisenberg model is employed to describe the TC dependence on the stoichiometry. The decrease in TC is dominated by the Ba substitution on the Eu lattice with a small contribution arising from the lattice strain. Extrapolation of results indicates that a sample at x = 0 . 72 should have a TC = 0 K, potentially producing a quantum phase transition in this material. DOE SC-0008832, NSF DMR-1157490. This work was supported by the Department of Energy, Office of Basic Science, under contract DOE SC-0008832. This work has been performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement DMR-1157490, the State of Florida, and the U.S. Department of Energy.

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

Xu, Jing; Chongqing University of Science and Technology, Chongqing 401331; Hu, Chenguo, E-mail: hucg@cqu.edu.cn

Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: {yields} In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g,more » coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non-orthovanadate phase with spin S = 1/2.« less

Self-assembly of a tetrahedral 58-nuclear barium vanadium oxide cluster.

PubMed

Kastner, Katharina; Puscher, Bianka; Streb, Carsten

2013-01-07

We report the synthesis and characterization of a molecular barium vanadium oxide cluster featuring high nuclearity and high symmetry. The tetrameric, 2.3 nm cluster H(5)[Ba(10)(NMP)(14)(H(2)O)(8)[V(12)O(33)](4)Br] is based on a bromide-centred, octahedral barium scaffold which is capped by four previously unknown [V(12)O(33)](6-) clusters in a tetrahedral fashion. The compound represents the largest polyoxovanadate-based heterometallic cluster known to date. The cluster is formed in organic solution and it is suggested that the bulky N-methyl-2-pyrrolidone (NMP) solvent ligands allow the isolation of this giant molecule and prevent further condensation to a solid-state metal oxide. The cluster is fully characterized using single-crystal XRD, elemental analysis, ESI mass spectrometry and other spectroscopic techniques.

Effect of 120 MeV Ag9+ ion irradiation of YCOB single crystals

NASA Astrophysics Data System (ADS)

Arun Kumar, R.; Dhanasekaran, R.

2012-09-01

Single crystals of yttrium calcium oxy borate (YCOB) grown from boron-tri-oxide flux were subjected to swift heavy ion irradiation using silver Ag9+ ions from the 15 UD Pelletron facility at Inter University Accelerator Center, New Delhi. The crystals were irradiated at 1 × 1013, 5 × 1013 and 1 × 1014 ions/cm2 fluences at room temperature and with 5 × 1013 ions/cm2 fluence at liquid nitrogen temperature. The pristine and the irradiated samples were characterized by glancing angle X-ray diffraction, UV-Vis-NIR and photoluminescence studies. From the characterization studies performed on the samples, it is inferred that the crystals irradiated at liquid nitrogen temperature had fewer defects compared to the crystals irradiated at room temperature and the defects increased when the ion fluence was increased at room temperature.

Degradation and recovery of iron doped barium titanate single crystals via modulus spectroscopy and thermally stimulated depolarization current

NASA Astrophysics Data System (ADS)

Carter, J. J.; Bayer, T. J. M.; Randall, C. A.

2017-04-01

Understanding resistance degradation during the application of DC bias and recovery after removing the DC bias provides insight into failure mechanisms and defects in dielectric materials. In this experiment, modulus spectroscopy and thermally stimulated depolarization current (TSDC) techniques were used to characterize the degradation and recovery of iron-doped barium titanate single crystals. Modulus spectroscopy is a very powerful analytical tool applied during degradation and recovery to observe changes in the local conductivity distribution. During degradation, oxygen vacancies migrate to the cathode region, and a counter flow of oxygen anions migrates towards the anode. With increasing time during degradation, the distribution of conductivity broadens only slightly exhibiting crucial differences to iron doped strontium titanate. After removing the DC bias, the recovery shows that a second previously unobserved and distinct conductivity maximum arises in the modulus data. This characteristic with two maxima related to different conductivities in the anode and cathode region is what can be expected from the published defect chemistry. It will be concluded that only the absence of an external electric field during recovery measurements permits the observation of local conductivity measurements without the presence of non-equilibrium conditions such as charge injection. Equilibrium conductivity as a function of oxygen vacancy concentration is described schematically. Oxygen vacancy migration during degradation and recovery is verified by TSDC analysis. We establish a self-consistent rationale of the transient changes in the modulus and TSDC for the iron doped barium titanate single crystal system including electron, hole and oxygen vacancy conductivity. During degradation, the sample fractured.

Bioactive borate glass scaffolds: in vitro and in vivo evaluation for use as a drug delivery system in the treatment of bone infection.

PubMed

Liu, Xin; Xie, Zongping; Zhang, Changqing; Pan, Haobo; Rahaman, Mohamed N; Zhang, Xin; Fu, Qiang; Huang, Wenhai

2010-02-01

The objective of this work was to evaluate borate bioactive glass scaffolds (with a composition in the system Na(2)O-K(2)O-MgO-CaO-B(2)O(3)-P(2)O(5)) as devices for the release of the drug Vancomycin in the treatment of bone infection. A solution of ammonium phosphate, with or without dissolved Vancomycin, was used to bond borate glass particles into the shape of pellets. The in vitro degradation of the pellets and their conversion to a hydroxyapatite-type material in a simulated body fluid (SBF) were investigated using weight loss measurements, chemical analysis, X-ray diffraction, and scanning electron microscopy. The results showed that greater than 90% of the glass in the scaffolds degraded within 1 week, to form poorly crystallized hydroxyapatite (HA). Pellets loaded with Vancomycin provided controlled release of the drug over 4 days. Vancomycin-loaded scaffolds were implanted into the right tibiae of rabbits infected with osteomyelitis. The efficacy of the treatment was assessed using microbiological examination and histology. The HA formed in the scaffolds in vivo, resulting from the conversion of the glass, served as structure to support the growth of new bone and blood vessels. The results in this work indicate that bioactive borate glass could provide a promising biodegradable and bioactive material for use as both a drug delivery system and a scaffold for bone repair.

Optical and EPR studies of barium alumino borate glasses containing Cu2+ ions

NASA Astrophysics Data System (ADS)

Ahmed, Mohamad Raheem; Phani, A. V. Lalitha; Narsimha Chary, M.; Shareefuddin, Md.

2018-05-01

Glass containing Cu2+ ions in (30-x) BaO-xAl2O3-69.5B2O3-0.5CuO (0 ≤ x ≤ 15 mol %) were prepared by the conventional melt quenching technique. Peak free X-ray diffractograms confirmed the amorphous nature of the glass samples. Spectroscopic studies such as optical absorption, EPR were studied to understand the effect of modifier oxide and CuO dopant. From EPR spectra the spin-Hamiltonian parameter were evaluated. The ground state of Cu2+ is dx2-y2 (2B1g state) and the site symmetry around Cu2+ is tetragonally distorted octahedral. A broad optical absorption band was observed for all the glasses containing Cu2+ ions corresponding to the 2B1g → 2B2g transition. The optical band gap and Urbach energy values are calculated.

Study on the Structural, Morphological and Optical Properties of RF-Sputtered Dysprosium-Doped Barium Tungstate Thin Films

NASA Astrophysics Data System (ADS)

Hridya, S.; Kavitha, V. S.; Chalana, S. R.; Reshmi Krishnan, R.; Sreeja Sreedharan, R.; Suresh, S.; Nampoori, V. P. N.; Sankararaman, S.; Prabhu, Radhakrishna; Mahadevan Pillai, V. P.

2017-11-01

Barium tungstate films with different Dy3+ doping concentrations, namely 0 wt.%, 1 wt.%, 3 wt.% and 5 wt.%, are deposited on cleaned quartz substrate by radio frequency magnetron sputtering technique and the prepared films are annealed at a temperature of 700°C. The structural, morphological and optical properties of the annealed films are studied using techniques such as x-ray diffraction (XRD), micro-Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and photoluminescence spectroscopy. XRD analysis shows that all the films are well-crystallized in nature with a monoclinic barium tungstate phase. The presence of characteristic modes of the tungstate group in the Raman spectra supports the formation of the barium tungstate phase in the films. Scanning electron microscopic images of the films present a uniform dense distribution of well-defined grains with different sizes. All the doped films present a broad emission in the 390-500 nm region and its intensity increases up to 3 wt.% and thereafter decreases due to usual concentration quenching.

Significant reduction of saturation magnetization and microwave-reflection loss in barium-natural ferrite via Nd3+ substitution

NASA Astrophysics Data System (ADS)

Widanarto, W.; Ardenti, E.; Ghoshal, S. K.; Kurniawan, C.; Effendi, M.; Cahyanto, W. T.

2018-06-01

To minimize the signal degradation, many electronic devices require efficient microwave absorbers with very low reflection-losses within the X-band. We prepared a series of trivalent neodymium-ion (Nd3+) substituted barium-natural ferrite using a modified solid-state reaction method. The effect of the Nd3+-ion content on the structure, surface morphology, magnetic properties, and microwave reflection loss was studied. The composites were characterized using X-ray diffraction, a vibrating sample magnetometer, scanning electron microscopy, and a vector network analyzer. The XRD patterns of the sample without Nd3+ reveal the presence of BaFe12O19 (hexagonal) and BaFe2O4 (rhombohedral) phases. Furthermore, a new hexagonal crystal phase of Ba6Nd2Fe4O15 appeared after substituting Nd3+. The average size of the prepared barium-natural ferrite particles was estimated to be between 0.4 and 0.8 μm. Both saturation magnetization and microwave reflection losses of these barium-ferrites were significantly reduced by increasing the Nd3+ content.

Effect of Boron and Phosphate compounds on Thermal and Fire Properties of wood/HDPE composites

Treesearch

Turgay Akbulut; Nadir Ayrilmis; Turker Dundar; Ali Durmus; Robert H. White; Murat Teker

2011-01-01

Melting and non-isothermal crystallization behaviors, oxidative induction time, and fire performance of the injection-molded wood flour-high density polyethylene (HDPE) composites (WPCs) incorporated with different levels (4, 8, or 12 wt %) of boron compounds [borax/boric acid (BX/BA) (0.5:0.5 wt %), zinc borate (ZB)] and phosphorus compounds [mono- and di-ammonium...

Crystal chemistry and temperature behavior of the natural hydrous borate colemanite, a mineral commodity of boron

NASA Astrophysics Data System (ADS)

Lotti, Paolo; Gatta, G. Diego; Demitri, Nicola; Guastella, Giorgio; Rizzato, Silvia; Ortenzi, Marco Aldo; Magrini, Fabrizio; Comboni, Davide; Guastoni, Alessandro; Fernandez-Diaz, Maria Teresa

2018-05-01

Colemanite, CaB3O4(OH)3ṡH2O, is the most common hydrous Ca-borate, as well as a major mineral commodity of boron. In this study, we report a thorough chemical analysis and the low-temperature behavior of a natural sample of colemanite by means of a multi-methodological approach. From the chemical point of view, the investigated sample resulted to be relatively pure, its composition being very close to the ideal one, with only a minor substitution of Sr2+ for Ca2+. At about 270.5 K, a displacive phase transition from the centrosymmetric P21/ a to the acentric P21 space group occurs. On the basis of in situ single-crystal synchrotron X-ray (down to 104 K) and neutron diffraction (at 20 K) data, the hydrogen-bonding configuration of both the polymorphs and the structural modifications at the atomic scale at varying temperatures are described. The asymmetric distribution of ionic charges along the [010] axis, allowed by the loss of the inversion center, is likely responsible for the reported ferroelectric behavior of colemanite below the phase transition temperature.

Diode-pumped Tunable 3 Micron Laser Sources

DTIC Science & Technology

2000-02-21

DoD Ballistic Missile Defense Organization U.S. Army Space and Missile Defense Command SBIR Phase I Final Report AC Materials, Inc. 2721 Forsyth...pumped tunable 3 micron laser sources 6. AUTHORISI Arlete Cassanho, Hans Jenssen 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) AC Materials, Inc...impurities in the final crystal, starting materials for the crystal growth were prepared at AC Materials from optical grade barium fluoride and

Crystallization kinetics of BaO-Al2O3-SiO2 glasses

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Hyatt, Mark J.

1989-01-01

Barium aluminosilicate glasses are being investigated as matrix materials in high-temperature ceramic composites for structural applications. Kinetics of crystallization of two refractory glass compositions in the barium aluminosilicate system were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). From variable heating rate DTA, the crystallization activation energies for glass compositions (wt percent) 10BaO-38Al2O3-51SiO2-1MoO3 (glass A) and 39BaO-25Al2O3-35SiO2-1MoO3 (glass B) were determined to be 553 and 558 kJ/mol, respectively. On thermal treatment, the crystalline phases in glasses A and B were identified as mullite (3Al2O3-2SiO2) and hexacelsian (BaO-Al2O3-2SiO2), respectively. Hexacelsian is a high-temperature polymorph which is metastable below 1590 C. It undergoes structural transformation into the orthorhombic form at approximately 300 C accompanied by a large volume change which is undesirable for structural applications. A process needs to be developed where stable monoclinic celsian, rather than hexacelsian, precipitates out as the crystal phase in glass B.

Crystallization kinetics of BaO-Al2O3-SiO2 glasses

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Hyatt, Mark J.

1988-01-01

Barium aluminosilicate glasses are being investigated as matrix materials in high-temperature ceramic composites for structural applications. Kinetics of crystallization of two refractory glass compositions in the barium aluminosilicate system were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). From variable heating rate DTA, the crystallization activation energies for glass compositions (wt percent) 10BaO-38Al2O3-51SiO2-1MoO3 (glass A) and 39BaO-25Al2O3-35SiO2-1MoO3 (glass B) were determined to be 553 and 558 kJ/mol, respectively. On thermal treatment, the crystalline phases in glasses A and B were identified as mullite (3Al2O3-2SiO2) and hexacelsian (BaO-Al2O3-2SiO2), respectively. Hexacelsian is a high-temperature polymorph which is metastable below 1590 C. It undergoes structural transformation into the orthorhombic form at approximately 300 C accompanied by a large volume change which is undesirable for structural applications. A process needs to be developed where stable monoclinic celsian, rather than hexacelsian, precipitates out as the crystal phase in glass B.

Conversion of melt-derived microfibrous borate (13-93B3) and silicate (45S5) bioactive glass in a simulated body fluid.

PubMed

Liu, Xin; Rahaman, Mohamed N; Day, Delbert E

2013-03-01

Microfibrous bioactive glasses are showing a considerable capacity to heal soft tissue wounds, but little information is available on the mechanism of healing. In the present study, the conversion of microfibrous borate bioactive glass (diameter = 0.2-5 μm) with the composition designated 13-93B3 (5.5 Na2O, 11.1 K2O, 4.6 MgO, 18.5 CaO, 3.7 P2O5, 56.6 B2O3 wt%) was evaluated in vitro as a function of immersion time in a simulated body fluid (SBF) at 37 °C using structural and chemical techniques. Silicate 45S5glass microfibers (45 SiO2, 24.5 Na2O, 24.5 CaO, 6 P2O5 wt%) were also studied for comparison. Microfibrous 13-93B3 glass degraded almost completely and converted to a calcium phosphate material within 7-14 days in SBF, whereas >85 % of the silica remained in the 45S5 microfibers, forming a silica gel phase. An amorphous calcium phosphate (ACP) product that formed on the 13-93B3 microfibers crystallized at a slower rate to hydroxyapatite (HA) when compared to the ACP that formed on the 45S5 fibers. For immersion times >3 days, the 13-93B3 fibers released a higher concentration of Ca into the SBF than the 45S5 fibers. The fast and more complete degradation, slow crystallization of the ACP product, and higher concentration of dissolved Ca in SBF could contribute to the capacity of the microfibrous borate 13-93B3 glass to heal soft tissue wounds.

Method for harvesting rare earth barium copper oxide single crystals

DOEpatents

Todt, V.R.; Sengupta, S.; Shi, D.

1996-04-02

A method of preparing high temperature superconductor single crystals is disclosed. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid. 2 figs.

Method for harvesting rare earth barium copper oxide single crystals

DOEpatents

Todt, Volker R.; Sengupta, Suvankar; Shi, Donglu

1996-01-01

A method of preparing high temperature superconductor single crystals. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid.

The Phase Transformation and Crystal Structure Studies of Strontium Substituted Barium Monoferrite

NASA Astrophysics Data System (ADS)

Mulyawan, A.; Adi, W. A.; Mustofa, S.; Fisli, A.

2017-03-01

Unlike other AFe2O4 ferrite materials, Barium Monoferrite (BaFe2O4) have an orthorhombic structure which is very interesting to further study the crystal structure and phase formation. In this study, Strontium substituted Barium Monoferrite in the form of Ba(1-x)Sr(x)Fe2O4 has successfully been synthesized through solid state reaction method which includes BaCO3, SrCO3, and Fe2O3 as starting materials. Ba(1-x)Sr(x)Fe2O4 was made by varying the dopant composition of Strontium (Sr2+) from x = 0, 0.1, 0.3, and 0.5. Each composition was assisted by ethanol and continued to the milling process for 5 hours then followed by sintering process at 900 °C for 5 hours. The phase transformation was studied by using X-ray diffractometer (XRD) and Rietveld refinement using General Structure Analysis System (GSAS) also 3D crystal visualization using VESTA. Referring to the refinement results, a single phase of BaFe2O4 was formed in x = 0 and 0.1. The composition has orthorhombic structure, space group B b21m, and lattice parameters of a = 19.0229, b = 5.3814 c = 8.4524 Å, α = β = γ = 90° and a = 18.9978, b = 5.3802 c = 8.4385 Å, α = β = γ = 90° respectively. In the composition of x = 0.3 it was found that the phase of BaSrFe4O8 begin to form due to the overload expansion of the Sr2+ occupancy which made the distortion of the initial lattice parameters and finally in the x = 0.5 composition the single phase of BaSrFe4O8 was clearly formed. Energy Dispersive Spectroscopy (EDS) was used to confirm the change of the material structure by measuring the elemental compound composition ratio. The result of EDS spectra clearly exhibited the dominant elements were Barium (Ba), Strontium (Sr), Iron (Fe), and Oxygen (O) with the compound ratio (Atomic percentage and mass percentage) correspond to the BaFe2O4 and BaSrFe4O8 phase.

Specific Features of the Domain Structure of BaTiO3 Crystals during Thermal Heating and Cooling

NASA Astrophysics Data System (ADS)

Kiselev, D. A.; Ilina, T. S.; Malinkovich, M. D.; Sergeeva, O. N.; Bolshakova, N. N.; Semenova, E. M.; Kuznetsova, Yu. V.

2018-04-01

This paper presents the results of the study of the domain structure of barium titanate crystals in a wide temperature range including the Curie point ( T C) using the polarization-optical method in the reflected light and the force microscopy of the piezoelectric response. It is shown that a new a-c domain structure forms during cyclic heating of the crystal above T C and subsequent cooling to the ferroelectric phase. The role of uncompensated charges appeared on the crystal surface during the phase transition and their influence on the formation of the domain structure during cooling are discussed.

Hygroscopic La[B{sub 5}O{sub 8}(OH)]NO{sub 3}·2H{sub 2}O: Insight into the evolution of borate fundamental building blocks

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

Zhao, Biao-Chun, E-mail: zhaobiaochun@sohu.com; Sun, Wei, E-mail: 421221789@qq.com; Ren, Wei-Jian, E-mail: 935428502@qq.com

2013-10-15

Borates have exceptionally diverse fundamental building blocks (FBBs), but factors controlling the formation of borate FBBs are poorly understood. The title compound La[B{sub 5}O{sub 8}(OH)]NO{sub 3}·2H{sub 2}O crystallizes in the space group P2{sub 1}/n with a=6.5396(12) Å, b=15.550(3) Å, c=10.6719(19) Å, β=90.44(1)° and Z=4 at 173(2) K. Its structure has been refined from single-crystal X-ray diffraction data to R{sub 1}=0.049 (for 2465) and wR{sub 2}=0.173 (for 2459 I>2σ(I)). This structure analysis and first-principles calculations show that the change of the FBB from 3Δ2□ in the title compound to 2Δ3□ in La[B{sub 5}O{sub 8}(OH)(H{sub 2}O)]NO{sub 3}·2H{sub 2}O is accompanied by amore » rotation of the NO{sub 3} group. FTIR, Rietveld and thermal analysis results show that the hygroscopic title compound is partially changed to La[B{sub 5}O{sub 8}(OH)(H{sub 2}O)]NO{sub 3}·2H{sub 2}O, with the conversion of [BO{sub 3}] to [BO{sub 3}(H{sub 2}O)] by water absorption. - Graphical abstract: The change of fundamental building blocks from La[B{sub 5}O{sub 8}(OH)]NO{sub 3}·2H{sub 2}O to La[B{sub 5}O{sub 8}(OH)(H{sub 2}O)]NO{sub 3}·2H{sub 2}O is accompanied by a rotation of the NO{sub 3} group . Display Omitted - Highlights: • Synthesis of a new hydrous lanthanum polyborate nitrate. • Single-crystal XRD structure with the 3Δ2⎕ FBB and an oriented NO{sub 3} group. • DFT calculations locate the H positions in three lanthanide polyborate nitrates. • Rietveld, FTIR and DFT results show hygroscopicity changes the FBBs.« less

The analysis of photon pair source at telecom wavelength based on the BBO crystal (Conference Presentation)

NASA Astrophysics Data System (ADS)

Gajewski, Andrzej; Kolenderski, Piotr L.

2016-10-01

There are several problems that must be solved in order to increase the distance of quantum communication protocols based on photons as an information carriers. One of them is the dispersion, whose effects can be minimized by engineering spectral properties of transmitted photons. In particular, it is expected that positively correlated photon pairs can be very useful. We present the full characterization of a source of single photon pairs at a telecom wavelength based on type II spontaneous parametric down conversion (SPDC) process in a beta-barium borate (BBO) crystal. In the type II process, a pump photon, which is polarized extraordinarily, splits in a nonlinear medium into signal and idler photons, which are polarized perpendicularly to each other. In order for the process to be efficient a phase matching condition must be fulfilled. These conditions originate from momentum and energy conservation rules and put severe restrictions on source parameters. Seemingly, these conditions force the photon pair to be negatively correlated in their spectral domain. However, it is possible to achieve positive correlation for pulsed pumping. The experimentally available degrees of freedom of a source are the width of the pumping beam, the collected modes' widths, the length of the nonlinear crystal and the duration of the pumping pulse. In our numerical model we use the following figures of merit: the pair production rate, the efficiency of photon coupling into a single mode fiber, the spectral correlation of the coupled photon pair. The last one is defined as the Pearson correlation parameter for a joint spectral distribution. The aim here is to find the largest positive spectral correlation and the highest coupling efficiency. By resorting to the numerical model Ref. [1] we showed in Ref. [2], that by careful adjustment of the pump's and the collected modes' characteristics, one can optimize any of the source's parameters. Our numerical outcomes conform to the experimental results presented in Refs [3,4]. Here we investigate typical, experimentally available source parameters: the widths of the pump beam and collected modes ranging from 20μm to 500m, the crystal length ranging from 1mm to 7.5mm while the pulse duration is set to 50fs, 100fs or 150fs. We achieve the correlation coefficient value as high as approximately 0.8, or - for different values of parameters - coupling efficiency equal to 0.76.

Hydrothermal synthesis of barium strontium titanate and bismuth titanate materials

NASA Astrophysics Data System (ADS)

Xu, Huiwen

Hydrothermal processing facilitates the synthesis of crystalline ceramic materials of varying composition or complex crystal structure. The present work can be divided into two parts. First is to study the low temperature hydrothermal synthesis of bismuth titanate. Second is to study both thermodynamic and kinetic aspects of the hydrothermally synthesized barium strontium titanate. A chelating agent was used to form a Bi-Ti gel precursor. By hydrothermally treating the Bi-Ti gel, crystalline bismuth titanate has been synthesized at 160°C for the first time. Microstructural evolution during the low temperature synthesis of bismuth titanate can be divided into two stages, including condensation of Bi-Ti gel particles and crystallization of bismuth titanate. Crystallization of bismuth titanate occurred by an in situ transformation mechanism at an early stage followed by a dissolution-reprecipitation mechanism. Phase separation was observed in hydrothermally synthesized barium strontium titanate (BST). By hydrothermally treating BST powders between 250°C--300°C, an asymmetrical miscibility gap was found in the BaTiO3-SrTiO 3 system at low temperatures (T ≤ 320°C). A subregular solid solution model was applied to calculate the equilibrium compositions and the Gibbs free energy of formation of BST solid solution at low temperatures (T ≤ 320°C). The Gibbs free energy of formation of Sr-rich BST phase is larger than that of Ba-rich BST phase. Kinetic studies of single phase BST solid solution at 80°C show that, compared to the BaTiO3 or Ba-rich BST, SrTiO3 and Sr-rich BST powders form at lower reaction rates.

Synthesis, characterisation, electrical and optical properties of copper borate compounds

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

Kipcak, Azmi Seyhun; Senberber, Fatma Tugce; Aydin Yuksel, Sureyya

2015-10-15

Highlights: • Cu(BO{sub 2}){sub 2} was synthesized at the form of with pdf number of “00-001-0472”. • Particle sizes were found between 162.72 and 56.44 nm and 195.76 and 75.73 nm at CuSNaH. • Reaction yields were 90.4 ± 0.84, 96.9 ± 0.78 and 78.9 ± 0.76% for CuST, CuSB and CuSNaH. • The resistivity of CuST, CuSB and CuSNaH are 1.10 × 10{sup 7}, 7.02 × 10{sup 6} and 8.62 × 10{sup 5} Ωm. • The optical energy gap was 3.76 eV. - Abstract: The hydrothermal synthesis of copper borate compounds [Cu(BO{sub 2}){sub 2}] was studied, and several parametersmore » were found to affect the synthesis. Raw materials, including CuSO{sub 4}·5H{sub 2}O, Na{sub 2}B{sub 4}O{sub 7}·5H{sub 2}O, Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}O, NaOH and H{sub 3}BO{sub 3}, were used. Reaction temperatures and reaction times between 40 °C and 100 °C and 15 and 240 min, respectively, were used. The as-synthesised copper borate was analysed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The yields of the reactions were also calculated. Single-phase, nanoparticulate copper borate compounds (Cu(BO{sub 2}){sub 2}) possessing high XRD crystal scores were obtained; the reactions used to obtain these materials were highly efficient. Electrical resistivity and optical absorbance measurements were carried out on the compounds obtained from the highest yielding reactions. The results of this study showed that even using a reaction time of 15 min, copper borate formation was successfully achieved.« less

Synthesis, structure characterization, photoluminescence properties and TD-DFT calculations for two new borates.

PubMed

Hadjadj, Nasreddine; Dems, Mohamed AbdEsselem; Merazig, Hocine; Bendjeddou, Lamia

2018-04-01

Due to their rich structural chemistry and wide variety of applications, borate materials have provided a rich area of research. In a continuation of this research, diethylammonium bis(2-oxidobenzoato-κ 2 O 1 ,O 2 )borate, C 4 H 12 N + ·BO 4 (C 7 H 4 O) 2 - , (1), and propylammonium bis(2-oxidobenzoato-κ 2 O 1 ,O 2 )borate, C 3 H 10 N + ·BO 4 (C 7 H 4 O) 2 - , (2), have been synthesized by the reaction of boric acid with salicylic acid under ambient conditions. In both structures, the B atom exhibits a slightly distorted tetrahedral environment formed by the bidentate coordination of two salicylate anions via the O atoms of the central carboxylate and oxide groups. In the crystals of salts (1) and (2), mixed cation-anion layers lying parallel to the (101) plane are formed through N-H...O, C-H...O and C-H...π/N-H...O hydrogen-bonding interactions, resulting, in each case, in a two-dimensional supramolecular architecture in the solid state. The photoluminescence properties of the salts were studied using the as-synthesized samples and reveal that salts (1) and (2) both display a strong blue-light emission, with maxima at 489 and 491 nm, respectively. In DFT/TD-DFT (time-dependent density functional theory) studies, the blue emission appears to be derived from an intramolecular charge transfer (ICT) excited state. In addition, IR and UV-Vis spectroscopies were used to investigate the title salts.

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

Tang, Wan Si; Dimitrievska, Mirjana; Stavila, Vitalie

The salt compounds NaB 11H 14, Na-7-CB10H13, Li-7-CB 10H 13, Na-7,8-C 2B 9H 12, and Na-7,9-C 2B 9H 12 all contain geometrically similar, monocharged, nido-undeca(carba)borate anions (i.e., truncated icosohedral-shaped clusters constructed of only 11 instead of 12 {B-H} + {C-H} vertices and an additional number of compensating bridging and/or terminal H atoms). We used first-principles calculations, X-ray powder diffraction, differential scanning calorimetry, neutron vibrational spectroscopy, neutron elastic-scattering fixed-window scans, quasielastic neutron scattering, and electrochemical impedance measurements to investigate their structures, bonding potentials, phase-transition behaviors, anion orientational mobilities, and ionic conductivities compared to those of their closo-poly(carba)borate cousins. All exhibited order-disordermore » phase transitions somewhere between room temperature and 375 K. All disordered phases appear to possess highly reorientationally mobile anions (> ~10 10 jumps s -1 above 300 K) and cation-vacancy-rich, close-packed or body-center-cubic-packed structures [like previously investigated closo-poly(carba)borates]. Moreover, all disordered phases display superionic conductivities but with generally somewhat lower values compared to those for the related sodium and lithium salts with similar monocharged 1-CB 9H 10- and CB 11H 12- closo-carbaborate anions. This study significantly expands the known toolkit of solid-state, poly(carba)borate-based salts capable of superionic conductivities and provides valuable insights into the effect of crystal lattice, unit cell volume, number of carbon atoms incorporated into the anion, and charge polarization on ionic conductivity.« less

Density functional calculations of carbon substituting for Zr in barium zirconate

NASA Astrophysics Data System (ADS)

Al-Hadidi, Meaad; Goss, J. P.; Al-Ani, Oras A.; Briddon, P. R.; Rayson, M. J.

2017-06-01

Oxide perovskites such as BaZrO3 possess many significant properties which render them useful in many technological and scientific applications such as sensors, optoelectronics, laser frequency doubling and high capacity memory cells. Several methods are used to grow BaZrO3 crystal, and organic species that may be present during growth lead to carbon contamination. We have investigated, using density-functional theory, the role of carbon impurities on the structural, electrical and electronic properties of carbon substituting of Zr in cubic barium zirconate. The local vibrational modes of the defect centre has been calculated and we suggest it is a feasible route to experimental identification

Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

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

Lin, Guoping, E-mail: guoping.lin@femto-st.fr; Diallo, Souleymane; Saleh, Khaldoun

2014-12-08

We report the observation of stimulated Brillouin scattering and lasing at 1550 nm in barium fluoride (BaF{sub 2}) crystal. Brillouin lasing was achieved with ultra-high quality (Q) factor monolithic whispering gallery mode mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from 8.2 GHz up to 49 GHz have been generated through cascaded Brillouin lasing. BaF{sub 2} resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

Properties of barium strontium titanate and niobate nanoparticles produced in gas discharge

NASA Astrophysics Data System (ADS)

Plyaka, Pavel; Kazaryan, Mishik; Pavlenko, Anatoly

2018-03-01

Dust particles produced in the gas-discharge plasma by barium-strontium titanate and niobate targets sputtering have been investigated in the paper. Particles shape, size and chemical composition were identified. It have been established by Raman scattering investigation and X-ray structure analysis that a part of the collected dust particles retained original crystal structure of the sputtering target. For electro-physical investigations two discs were formed by pressuring from produced particles, and electrodes were deposited on disc flat surface. Capacitance and dielectric loss temperature dependences measurement resulted in the frequency range proving the ferroelectric properties of assembled nanoparticles, similar to the sputtered material.

Effect of lattice strain on structural and magnetic properties of Ca substituted barium hexaferrite

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Supriya, Sweety; Pandey, Rabichandra; Pradhan, Lagen Kumar; Singh, Rakesh Kumar; Kar, Manoranjan

2018-07-01

The calcium (Ca2+) substituted M-type barium hexaferrite (Ba1-xCaxFe12O19) for Ca2+ (x = 0.00, 0.025, 0.050, 0.075, 0.100, 0.150, and 0.200) have been synthesized by the citrate sol-gel method. The X-ray diffraction (XRD) patterns with Rietveld refinement reveal the formation of hexagonal crystal structure with P63/mmc space group. The lattice parameters a = b and c decrease, whereas lattice strain found to increase with the increase in Ca concentration in the samples. The analysis of Raman spectra well supports the XRD patterns analysis. The average particle size is obtained from the FE-SEM (Field Emission Scanning Electron Microscopy) micrographs and these are similar to that of crystallite size obtained from the XRD pattern analysis. The saturation magnetization and magnetocrystalline anisotropy have been obtained by employing the "Law of Approach (LA) to Saturation magnetization" technique at room temperature. The saturation magnetization and magnetocrystalline anisotropy constant are maximum for 5% Ca substitution in barium hexaferrite. It could be due to lattice strain mediated magnetism. However, these magnetic properties decrease for more than the 5% Ca substitution in barium hexaferrite. It could be due to decrease of magnetic exchange interaction (Fe-O-Fe) in the sample. A correlation between magnetic interaction and lattice strain has been observed in Ca2+ substituted M-type barium hexaferrite.

[Microanalytical identification of barium sulphate crystals in statoliths of Chara rhizoids (Ch. fragilis, desv.)].

PubMed

Schröter, K; Läuchli, A; Sievers, A

1975-01-01

In contrast to the statocytes of higher plants, in which amyloplasts function as statoliths, Chara-rhizoids contain statolith vacuoles filled with biocrystallites of BaSO4. This was revealed by qualitative and quantitative electron microprobe analysis, atomic absorption spectrophotometry and selected area electron diffraction. The barium sulphate crystallites are rods which are linearly composed of globular subunits approximately 7 nm in diameter.The electron optical evidence of the crystallites depends on the nature of the fixatives. Best structural preservation was observed after fixation in a buffered solution of glutaraldehyde plus acrolein without addition of heavy metals. OsO4 and particularly KMnO4 partially dissolve the biocrystallites as well as synthetic BaSO4. The crystal solubility must be taken into consideration when micrographs of such small crystallites are interpreted.The fact that BaSO4 is chemically very inert seems to exclude biochemical interactions of the statoliths with other cell components during graviperception. It favours the theory that only the mass of the statoliths is effective.

Synthesis and structural characterization of two half-sandwich nickel(II) complexes with the scorpionate ligands

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

Wang, G.-F., E-mail: wgf1979@126.com, E-mail: s-shuwen@163.com; Zhang, X., E-mail: zhangx@hit.edu.cn; Sun, S.-W.

The synthesis and characterization of two new halfsandwich mononuclear nickel(II) complexes with the scorpionate ligands, [k{sup 3}-N, N',N''-Tp{sup t-Bu}, {sup Me}NiI] (1) and [k{sup 3}-N,N',N''-Tp{sup t-Bu}, {sup Me}NiNO{sub 3}] (2), are reported. These complexes have been fully characterized by elemental analyses and infrared spectra. Their molecular structures were determined by single crystal X-ray diffraction. The nickel(II) ion of complex 1 is in a four-coordinate environment, in which the donor atoms are provided by three nitrogen atoms of a hydrotris(pyrazolyl) borate ligand and one iodide atom, while that of complex 2 is in a five-coordinate environment with three nitrogen atoms frommore » a hydrotris(pyrazolyl)borate ligand and two oxygen atoms from a nitrate ion.« less

Synthesis and photoluminescence properties of Pb2+ doped inorganic borate phosphor NaSr4(BO3)3

NASA Astrophysics Data System (ADS)

Chauhan, A. O.; Koparkar, K. A.; Bajaj, N. S.; Omanwar, S. K.

2016-05-01

A series of Inorganic borate phosphors NaSr4(BO3)3 doped with Pb2+ was successfully synthesized by modified solid state diffusion method. The crystal structure and the phase purity of sample were characterized by powder X-ray diffraction (XRD). The photoluminescence properties of synthesized materials were investigated using spectrofluorometer at room temperature. The phosphor show strong broad band emission spectra in UVA region maximum at 370 nm under the excitation of 289 nm. The dependence of the emission intensity on the Pb2+ concentration for the NaSr4(BO3)3 were studied in details. The concentration quenching of Pb2+ doped NaSr4(BO3)3 was observed at 0.02 mol. The Stokes shifts of NaSr4(BO3)3: Pb2+ phosphor was calculated to be 7574 cm-1.

Preparation and Characterization of Chromium(III)-Activated Yttrium Aluminum Borate: A New Thermographic Phosphor for Optical Sensing and Imaging at Ambient Temperatures

PubMed Central

2010-01-01

A new thermographic phosphor based on chromium(III)-doped yttrium aluminum borate (YAB) is obtained as single crystals by high temperature flux growth and as a microcrystalline powder via solution combustion synthesis. The phosphor is excitable both in the blue (λmax 422 nm) and in the red part of the spectrum (λmax 600 nm) and shows bright NIR emission. The brightness of the phosphor is comparable to that of a well-known lamp phosphor Mn(IV)-doped magnesium fluorogermanate. At ambient temperatures, the Cr(III)-doped YAB shows high temperature dependence of the luminescence decay time, which approaches 1% per deg. The material shows no decrease in luminescence intensity at higher temperatures. The new phosphor is particularly promising for applications in temperature-compensated optical chemosensors (including those based on NIR-emitting indicators) and in pressure-sensitive paints. PMID:20473368

Synthesis, structure, and electronic structure calculation of a new centrosymmetric borate Pb{sub 2}O[BO{sub 2}(OH)] based on anion-centered OPb{sub 4} tetrahedra

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

Sun, Feng; Wang, Li, E-mail: wangliresearch@163.com; Stoumpos, Constantinos C.

2016-08-15

The synthesis, structure, and characterization of a new centrosymmetric borate Pb{sub 2}O[BO{sub 2}(OH)] based on anion-centered OPb{sub 4} tetrahedra are reported. Pb{sub 2}O[BO{sub 2}(OH)] crystallizes in monoclinic space group C2/m with a=12.725(7) Å, b=5.698(3) Å, c=7.344(4) Å, β=116.277(6)°. The electronic band structure and density of states of Pb{sub 2}O[BO{sub 2}(OH)] have been calculated via the density functional theory (DFT). Electron density difference calculation indicates that lone-pair electrons of Pb{sup 2+} cation should be stereoactive. - Graphical abstract: An indirect gap compound of Pb{sub 2}O[BO{sub 2}(OH)] with 2D inorganic layers motif based on OPb{sub 4} tetrahedra has been synthesized and fullmore » characterized by crystallographic, IR, TG, UV–vis-NIR Diffuse Reflectance, and theoretical calculations. Display Omitted - Highlights: • A centrosymmetric borate Pb{sub 2}O[BO{sub 2}(OH)] was synthesized and characterized. • The crystalstructure, electronic band and density states was analyzed. • The lone-pair electrons of Pb{sup 2+} were proved to be stereoactive.« less

Comments on "Optical properties of borate crystals in the terahertz domain"

NASA Astrophysics Data System (ADS)

Svetlichnyi, V. A.; Naftaly, M.; Molloy, J. F.; Andreev, Yu. M.; Kokh, K. A.; Lanskii, G. V.; Kononova, N. G.; Kokh, A. E.

2016-04-01

We comment on the recent paper by V.D. Antsygin et al. [Opt. Commun. 309 (2013) 333-337], in which for the first time dispersions of refractive indices nx,z in lithium triborate (LBO) were presented for the THz domain. Their claim of "nx>nz", based on measurements by THz time-domain spectroscopy (TDS), is contrary to the well-known relationship for the maximum transparency region.

Contribution of nanointerfaces to colossal permittivity of doped Ba(Ti,Sn)O3 ceramics

NASA Astrophysics Data System (ADS)

V'yunov, Oleg; Reshytko, Borys; Belous, Anatolii; Kovalenko, Leonid

2018-03-01

The microstructure, crystal chemical parameters and electrical-physical properties of samples of barium titanate-based dielectric and semiconductor ceramics were investigated in a wide frequency range. The contributions of different nanointerfaces to the permittivity of samples under investigation have been determined.

Correlation of EMR and optical spectroscopy data for Cr3+ and Mn2+ ions doped into yttrium aluminum borate YAl3(BO3)4 crystal - Extracting low symmetry aspects

NASA Astrophysics Data System (ADS)

Rudowicz, Czesław; Gnutek, Paweł; Açıkgöz, Muhammed

2015-08-01

In this study, the crystal field analysis for Cr3+ and Mn2+ ions doped into yttrium aluminum borate YAl3(BO3)4, for short YAB, crystal has been carried out to complement earlier study of the zero-field splitting (ZFS) parameters (ZFSPs). This analysis utilizes data on the distortion models obtained from analysis of the ZFSPs obtained experimentally by EMR for Cr3+ and Mn2+ ions at the Y3+ and Al3+ sites in YAB. This approach enables to verify and enhance reliability of the ZFSP modeling based on superposition model (SPM) analysis and the distortion models predicted previously. Subsequently, modeling of the crystal field parameters (CFPs) based on SPM analysis is carried out for Cr3+ and Mn2+ ions located at possible cation sites in YAB. The SPM predicted CFP values serve as input for the Crystal Field Analysis (CFA) package to calculate the CF energy levels. The predicted physical ZFS of the ground spin state, i.e. the 4A2 state for Cr3+ ion and the 6S state Mn2+ ions, enable calculation of the theoretical ZFSP values, D and D & (a-F), respectively, using the microscopic spin Hamiltonian (MSH) module in the CFA package. In this way, data on the distortions around the Cr3+ centers in YAB (and to a certain extent also for Mn2+ centers) obtained using the ZFSP data from EMR measurements may be correlated with data on the CF energy levels measured by optical spectroscopy. This modeling approach uncovers certain incompatibilities in the existing data for Cr3+:YAB, which call for reanalysis of the previous assignments of the energy levels observed in optical spectra and more accurate experimental data.

Crystallization and preliminary crystallographic study of 3 alpha, 20 beta-hydroxysteroid dehydrogenase from Streptomyces hydrogenans.

PubMed

Fitzgerald, P M; Duax, W L; Punzi, J S; Orr, J C

1984-05-15

3 alpha, 20 beta-Hydroxysteroid dehydrogenase, an NADH-dependent oxidoreductase isolated from Streptomyces hydrogenans , is a tetramer containing four subunits each of Mr 25,000. The enzyme has been crystallized by the vapor diffusion technique using either phosphate or borate buffered ammonium sulfate (pH between 6.0 and 8.7) as the precipitant. The crystals are hexagonal bipyramids ; they have the symmetry of space group P6(4)22 (or P6(2)22), with unit cell dimensions a = 127.3 A, c = 112.2 A. Volume and density considerations imply that the crystallographic asymmetric unit contains two monomers, and therefore that the tetramer possesses a 2-fold axis of symmetry that is coincident with a crystallographic 2-fold symmetry element.

Norm removal from frac water

DOEpatents

Silva, James Manio; Matis, Hope; Kostedt, IV, William Leonard

2014-11-18

A method for treating low barium frac water includes contacting a frac water stream with a radium selective complexing resin to produce a low radium stream, passing the low radium stream through a thermal brine concentrator to produce a concentrated brine; and passing the concentrated brine through a thermal crystallizer to yield road salt.

Size effects of 109° domain walls in rhombohedral barium titanate single crystals—A molecular statics analysis

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

Endres, Florian, E-mail: florian.endres@ltm.uni-erlangen.de; Steinmann, Paul, E-mail: paul.steinmann@ltm.uni-erlangen.de

2016-01-14

Ferroelectric functional materials are of great interest in science and technology due to their electromechanically coupled material properties. Therefore, ferroelectrics, such as barium titanate, are modeled and simulated at the continuum scale as well as at the atomistic scale. Due to recent advancements in related manufacturing technologies the modeling and simulation of smart materials at the nanometer length scale is getting more important not only to predict but also fundamentally understand the complex material behavior of such materials. In this study, we analyze the size effects of 109° nanodomain walls in ferroelectric barium titanate single crystals in the rhombohedral phasemore » using a recently proposed extended molecular statics algorithm. We study the impact of domain thicknesses on the spontaneous polarization, the coercive field, and the lattice constants. Moreover, we discuss how the electromechanical coupling of an applied electric field and the introduced strain in the converse piezoelectric effect is affected by the thickness of nanodomains.« less

Multiferroic properties and structural features of M-type Al-substituted barium hexaferrites

NASA Astrophysics Data System (ADS)

Trukhanov, A. V.; Trukhanov, S. V.; Kostishin, V. G.; Panina, L. V.; Salem, M. M.; Kazakevich, I. S.; Turchenko, V. A.; Kochervinskii, V. V.; Krivchenya, D. A.

2017-04-01

Precise studies of the crystal and magnetic structures of M-type substituted barium hexaferrites BaFe12- x Al x O19 (0.1 ≤ x ≤ 1.2) have been performed by powder neutron diffraction in the temperature range 300-730 K. The electric polarization and the magnetization, and also the magnetoelectric effect of the compositions under study have been studied in electric (to 110 kV/m) and magnetic (to 14 T) fields at room temperature. The spontaneous polarization and significant correlation between the dielectric and magnetic subsystems have been observed at room temperature. The magnetoelectric effect value is, on average, about 5%, and it increases slightly with the aluminum cation concentration. The precise structural studies made it possible to reveal the cause and the mechanism of formation of the spontaneous polarization in M-type substituted barium hexaferrites BaFe12- x Al x O19 ( x ≤ 1.2) with a collinear ferromagnetic structure.

Crystal Chemistry of the Potassium and Rubidium Uranyl Borate Families Derived from Boric Acid Fluxes

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

Wang, Shuao; Alekseev, Evgeny V.; Stritzinger, Jared T.

2010-07-19

The reaction of uranyl nitrate with a large excess of molten boric acid in the presence of potassium or rubidium nitrate results in the formation of three new potassium uranyl borates, K{sub 2}[(UO{sub 2}){sub 2}B{sub 12}O{sub 19}(OH){sub 4}]·0.3H{sub 2}O (KUBO-1), K[(UO{sub 2}){sub 2}B{sub 10}O{sub 15}(OH){sub 5}] (KUBO-2), and K[(UO{sub 2}){sub 2}B{sub 10}O{sub 16}(OH){sub 3}]·0.7H{sub 2}O (KUBO-3) and two new rubidium uranyl borates Rb{sub 2}[(UO{sub 2}){sub 2}B{sub 13}O{sub 20}(OH){sub 5}] (RbUBO-1) and Rb[(UO{sub 2}){sub 2}B{sub 10}O{sub 16}(OH){sub 3}]·0.7H{sub 2}O (RbUBO-2). The latter is isotypic with KUBO-3. These compounds share a common structural motif consisting of a linear uranyl, UO{sub 2}{sup 2+},more » cation surrounded by BO{sub 3} triangles and BO{sub 4} tetrahedra to create an UO{sub 8} hexagonal bipyramidal environment around uranium. The borate anions bridge between uranyl units to create sheets. Additional BO{sub 3} triangles extend from the polyborate layers and are directed approximately perpendicular to the sheets. All of these compounds adopt layered structures. With the exception of KUBO-1, the structures are all centrosymmetric. All of these compounds fluoresce when irradiated with long-wavelength UV light. The fluorescence spectrum yields well-defined vibronically coupled charge-transfer features.« less

In vitro bioactivity behavior of modified multicomponent borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5

NASA Astrophysics Data System (ADS)

Marzouk, M. A.; ElBatal, F. H.; Ghoneim, N. A.

2018-02-01

Some multi-component borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5 were prepared. Multi-characterization techniques were carried out to investigate their bioactivity, corrosion weight loss after immersion in phosphate solution. Controlled thermal heat-treatment by two-step technique was done to convert the prepared glasses to their corresponding glass-ceramic derivatives. X-ray diffraction analysis was performed to identify the crystalline phases formed by thermal treatment. Infrared absorption of glasses and glass-ceramics reveal vibrational bands due to combined main triangular and tetrahedral borate groups in their specific wavenumbers besides some sharing of phosphate group. After immersion in the phosphate solution, two extra characteristic peaks are generated indicating the bioactivity of the studied glasses and glass-ceramics through the formation of calcium phosphate (hydroxyapatite). X-ray diffraction data indicate the formation of crystalline phases which are variable with the introduced dopants. The main crystalline phase identified is calcium borate together with some other phases some of which contain phosphate ions. These data indicate that the presence of CaO and P2O5 initiates phase separation and subsequent crystallization of the parent and doped glasses. Weight loss data indicate that glass-ceramics are obviously durable than the parent glasses. SEM micrographs of glass-ceramics before immersion show multiconstituent crystalline phases due to the basic chemical composition consisting of multicomponent mixed alkali and alkaline earth oxides beside P2O5 and with the main B2O3 constituent. After immersion, the crystalline phases are identified to be more distinct in different shapes because of the multi-composition involved.

Synthesis of nanocomposites comprising iron and barium hexaferrites

NASA Astrophysics Data System (ADS)

Pal, M.; Bid, S.; Pradhan, S. K.; Nath, B. K.; Das, D.; Chakravorty, D.

2004-02-01

Composites of nanometre-sized α-iron and barium hexaferrite phases, respectively, have been synthesized by the ceramic processing route. Pure barium hexaferrite (BaO·6Fe 2O 3) was first of all prepared by calcinations of the precursor oxides at a maximum temperature of 1200°C for 4 h. By subjecting the resulting powder having particle size of the order of 1 μm to a reduction treatment in the temperature range 500-650°C for a period varying from 10 to 15 min it was possible to obtain a composite consisting of nanosized barium hexaferrite and α-Fe. At reduction temperature of 650°C for a period greater than 15 min all the ferrite phase was converted to α-Fe and Ba—the particle sizes being 59.4 and 43.6 nm, respectively. These conclusions are based on X-ray diffraction and Mossbauer studies of different samples. During reduction H + ions are introduced into the hexaferrite crystallite. It is believed that due to a tensile stress the crystals are broken up into smaller dimensions and the reduction brings about the growth of nanosized α-Fe and barium, respectively, around the hexaferrite particles. Magnetic measurements show coercivity values for the reduced samples in the range 120-440 Oe and saturation magnetization varying from 158 to 53.7 emu/g. These values have been ascribed to the formation and growth of α-Fe particles as the reduction treatment is increased. By heating the nanocomposites at a temperature of 1000°C for 1 h in ordinary atmosphere it was found that they were reconverted to the barium hexaferrite phase with a particle size ˜182.3 nm. The reaction described in this study is thus reversible.

Crystal structure of a mixed-ligand dinuclear Ba-Zn complex with 2-meth-oxy-ethanol having tri-phenyl-acetate and chloride bridges.

PubMed

Utko, Józef; Sobocińska, Maria; Dobrzyńska, Danuta; Lis, Tadeusz

2015-07-01

The dinuclear barium-zinc complex, μ-chlorido-1:2κ(2) Cl:Cl-chlorido-2κCl-bis-(2-meth-oxy-ethanol-1κO)bis-(2-meth-oxy-ethanol-1κ(2) O,O')bis-(μ-tri-phenyl-acetato-1:2κ(2) O:O')bariumzinc, [BaZn(C20H15O2)2Cl2(C3H8O2)4], has been synthesized by the reaction of barium tri-phenyl-acetate, anhydrous zinc chloride and 2-meth-oxy-ethanol in the presence of toluene. The barium and zinc metal cations in the dinuclear complex are linked via one chloride anion and carboxyl-ate O atoms of the tri-phenyl-acetate ligands, giving a Ba⋯Zn separation of 3.9335 (11) Å. The irregular nine-coordinate BaO8Cl coordination centres comprise eight O-atom donors, six of them from 2-meth-oxy-ethanol ligands (four from two bidentate O,O'-chelate inter-actions and two from monodentate inter-actions), two from bridging tri-phenyl-acetate ligands and one from a bridging Cl donor. The distorted tetra-hedral coordination sphere of zinc comprises two O-atom donors from the tri-phenyl-acetate ligands and two Cl donors (one bridging and one terminal). In the crystal, O-H⋯Cl, O-H⋯O and C-H⋯Cl inter-molecular inter-actions form a layered structure, lying parallel to (001).

Crystallization and photoluminescence properties of α-RE2(WO4)3 (RE: Gd, Eu) in rare-earth tungsten borate glasses

NASA Astrophysics Data System (ADS)

Wang, Yong; Honma, Tsuyoshi; Komatsu, Takayuki

2013-03-01

Glasses with the compositions of 22.5RE2O3-47.5WO3-30B2O3 (mol%) (RE: Gd, Eu) were prepared by a conventional melt quenching method, and α-Gd2(WO4)3 and α-Eu2(WO4)3 crystals were synthesized through their crystallization. The two types of WO4 tetrahedra present in α-RE2(WO4)3 provide the Raman bands at 931-934 cm-1 for WIIO4 tetrahrdra with much distortions and at 946-950 cm-1 for WIO4 tetrahedra with a near regular symmetry. The crystallized samples containing α-Eu2(WO4)3 exhibit strong red emissions under the excitation at 396 and 467 nm, although the base glass has no photoluminescence emission. α-Gd2(WO4)3 and α-Eu2(WO4)3 crystals were patterned on the glass surface by irradiations of a continuous wave Yb:YVO4 fiber laser (wavelength: 1080 nm).

Cr-doped scandium borate laser

DOEpatents

Chai, Bruce H.; Lai, Shui T.; Long, Margaret N.

1989-01-01

A broadly wavelength-tunable laser is provided which comprises as the laser medium a single crystal of MBO.sub.3 :Cr.sup.3+, where M is selected from the group of Sc, In and Lu. The laser may be operated over a broad temperature range from cryogenic temperatures to elevated temperatures. Emission is in a spectral range from red to infrared, and the laser is useful in the fields of defense, communications, isotope separation, photochemistry, etc.

Barium iodide and strontium iodide crystals andd scintillators implementing the same

DOEpatents

Payne, Stephen A; Cherepy, Nerine J; Hull, Giulia E; Drobshoff, Alexander D; Burger, Arnold

2013-11-12

In one embodiment, a material comprises a crystal comprising strontium iodide providing at least 50,000 photons per MeV. A scintillator radiation detector according to another embodiment includes a scintillator optic comprising europium-doped strontium iodide providing at least 50,000 photons per MeV. A scintillator radiation detector in yet another embodiment includes a scintillator optic comprising SrI.sub.2 and BaI.sub.2, wherein a ratio of SrI.sub.2 to BaI.sub.2 is in a range of between 0:1 A method for manufacturing a crystal suitable for use in a scintillator includes mixing strontium iodide-containing crystals with a source of Eu.sup.2+, heating the mixture above a melting point of the strontium iodide-containing crystals, and cooling the heated mixture near the seed crystal for growing a crystal. Additional materials, systems, and methods are presented.

Synthesis and evaluation of borates derived from boric acid and diols for the protection of wood against fungal decay and thermal degradation

Treesearch

George C. Chen

2004-01-01

N,N-dimethyl amino carbinol catechol borate(1). N,N-dimethyl amino carbinol-4-methyl catechol borate(2), N,N-dimethyl amino carbinol-4-t- butyl catechol borate(3). N,N-dimethyl amino carbinol-2,3-naphthyl borate 4) were synthesized by refluxing boric acid and diol in DMF(N,N-dimethyl formamide). The borates were characterized by NMR. Wood impregnated with borate 1,2 or...

Mineralogy and sedimentology of the Miocene Göcenoluk borate deposit, Kırka district, western Anatolia, Turkey

NASA Astrophysics Data System (ADS)

García-Veigas, Javier; Helvacı, Cahit

2013-05-01

The Miocene boratiferous district of Kırka, in western Anatolia (Turkey), is the most important Na-borate (borax) resource in the world. Two separate deposits in the Kırka district are located near the villages of Sarıkaya and Göcenoluk (Eskişehir Province). Borax is intensively exploited in open-pit mines in the Sarıkaya deposit while only small quarries of colemanite are known in the Göcenoluk deposit. Recent exploratory drilling in the Göcenoluk area intersected a thick succession of dolostones, tuffs and three borate-bearing units (Lower, Intermediate and Upper Borate Units). In them, the most abundant borate mineral is ulexite (Ca-Na-borate) passing at depth to probertite. Borax (Na-borate) is only present in the Intermediate Borate Unit. Minor amounts of colemanite (Ca-borate) and hydroboracite (Ca-Mg-borate) occur at the base, and/or top, of each mineralized unit. Pyroclastic layers within the borate units show intense alteration by alkaline, boron-bearing waters and formation of diagenetic clay minerals (smectites), zeolites (analcime) and borosilicates (searlesite). The Göcenoluk succession is interpreted as a shallow, ephemeral, alkaline lake deposit in which carbonates formed as stromatolites and travertines. Borate precipitation in the Göcenoluk area took place interstitially within muddy and carbonate sediments in a lateral progression from marginal Ca-borates towards Na-Ca-borates and rarely to Na-borates in the center of the lake. Authigenic silicate mineral distribution shows parallel changes toward the center of the lake that reflect increasing pH gradient.

Variation of Strontium (Sr) in the Ferroelectric Material Barium Strontium Titanate (Ba1-xSrxTiO3) by Co precipitation Method

NASA Astrophysics Data System (ADS)

Subarwanti, Y.; Safitri, R. D.; Supriyanto, A.; Iriani, Y.; Jamaludin, A.

2017-02-01

Barium Strontium Titanate (BST) have been made with variation strontium (Sr) 10%, 30% and 50% by co-precipitation method. This study aims to determine influence addition Sr against the crystal structure, crystallite size, lattice parameter, grain size and dielectric constant. Samples have been made by co-precipitation method and then the samples were sintered by furnace at 1100°C with holding time 4 hours. Characterization of BST use X-Ray Diffraction instrument, Scanning Electron Microscopy and Resistance Capacitance Inductance (RCL meter). Based on result obtained, the larger Sr content cause the diffraction angle shift to the right (the greater) and crystallinity increasing. But, the value of dielectric constant, crystallite size and grain size decreasing with additional Sr content. Measurement of dielectric constant (K) performed in the frequency range 1 kHz to 100 kHz and the highest value at Sr content 0.1 i.e. 258.35. The addition of Sr content 30% and 50% change the crystal structure from tetragonal to cubic which has paraelectric phase.

Study of structural, surface and hydrogen storage properties of boric acid mediated metal (sodium)-organic frameworks

NASA Astrophysics Data System (ADS)

Ozer, Demet; Köse, Dursun A.; Sahin, Onur; Oztas, Nursen A.

2018-04-01

Three boric acid mediated metal organic frameworks were synthesized by solution method with using succinic acid, fumaric acid and acetylene dicarboxylic acid as a ligand source and sodium as a metal source. The complexes were characterized by FT-IR, powder XRD, elemental analyses and single crystal measurements. The complexes with the formula, C4H18B2Na2O14, C4H16B2Na2O14 and C4H14B2Na2O14 were successfully obtained. BET surface area of complexes were calculated and found as 13.474 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-succinato)-di-sodium boric acid solvate), 1.692 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-fumarato)-di-sodium boric acid solvate) and 5.600 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-acetylenedicarboxylato)-di-sodium boric acid solvate). Hydrogen storage capacities of the complexes were also studied at 77 K 1 bar pressure and found as 0.108%, 0.033%, 0.021% by mass. When different ligands were used, the pore volume, pore width and surface area of the obtained complexes were changed. As a consequence, hydrogen storage capacities also changed.

Point defect disorder in high-temperature solution grown Sr6Tb0.94Fe1.06(BO3)6 single crystals

NASA Astrophysics Data System (ADS)

Velázquez, M.; Péchev, S.; Duttine, M.; Wattiaux, A.; Labrugère, C.; Veber, Ph.; Buffière, S.; Denux, D.

2018-08-01

New Sr6Tb0.94Fe1.06(BO3)6 single crystals were obtained from lithium borate high-temperature solution growth under controlled atmosphere. Their average crystal structure was found to adopt the trigonal R-3 space group with lattice parameters a = 12.2164 Å and c = 9.1934 Å. A combined multiscale characterization approach, involving diffuse reflectance, X-ray photoelectron (XPS) and Mössbauer spectroscopies, was undertaken to establish the exact nature of the point defect disorder in this crystal structure. The FeTb× antisite disorder in the Sr6Tb0.94Fe1.06(BO3)6 single crystals is different from the kind of point defect disorder known to exist in the powder phase material counterpart. The absence of Tb4+ cations in the crystal lattice was established by XPS, and that of any phase transition down to 4 K was checked by specific heat measurements. The magnetic susceptibility curve was found to follow a Curie-Weiss behaviour in the 4-354 K temperature range.

Bibliography of Soviet Laser Developments, Number 49, September-October 1980

DTIC Science & Technology

1981-10-01

Shcherbakov ( 1 ). Synthesis and study of spectral-luminescent and lasing properties of aluminum borate crystals doped with chromium and neodymium. KE, no. 10...A ’IDST-2700Z4004- 1 LEVEt~ I i DEFENSEINTELLIGENCE / 7O AGENCY Bibliography of Soviet Laser Developments (U) September- October 1980 OCTOBER INI...DOCUMENTATION PAGE READ ISTRPUCTONSBEFORE COMPLETING FORM 1 . REPOR NUMN 2. GOVT ACCES SION O. L. RECIPIENT’S CATALOG NUM BER DST-2700Z-004-81 - ’.,) ___ _ _ 4

Supercritical fluid route for synthesizing crystalline Barium Strontium Titanate nanoparticles.

PubMed

Reverón, H; Elissalde, C; Aymonier, C; Bidault, O; Maglione, M; Cansell, F

2005-10-01

Pure and well-crystallized Barium Strontium Titanate (BST) nanoparticles with controlled Ba/Sr ratio have been successfully synthesized under supercritical conditions using a continuous-flow reactor in the temperature range of 150-380 degrees C at 26 MPa. To synthesize the Ba0.6Sr0.4TiO3 composition, alkoxides, ethanol and water were used. The resulting nanopowder consists of fine particles with an average particle size of 23 nm. The results show that the Ba/Sr ratio of this powder can be accurately controlled from the composition of precursor. The characterization of the as-synthesized Ba0.6Sr0.4TiO3 solid-solution and the dielectric properties of the sintered ceramics are here reported.

Large single domain 123 material produced by seeding with single crystal rare earth barium copper oxide single crystals

DOEpatents

Todt, V.; Miller, D.J.; Shi, D.; Sengupta, S.

1998-07-07

A method of fabricating bulk YBa{sub 2}Cu{sub 3}O{sub x} where compressed powder oxides and/or carbonates of Y and Ba and Cu present in mole ratios to form YBa{sub 2}Cu{sub 3}O{sub x} are heated in the presence of a Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub y} seed crystal to a temperature sufficient to form a liquid phase in the YBa{sub 2}Cu{sub 3}O{sub x} while maintaining the seed crystal solid. The materials are slowly cooled to provide a YBa{sub 2}Cu{sub 3}O{sub x} material having a predetermined number of domains between 1 and 5. Crack-free single domain materials can be formed using either plate shaped seed crystals or cube shaped seed crystals with a pedestal of preferential orientation material. 7 figs.

Large single domain 123 material produced by seeding with single crystal rare earth barium copper oxide single crystals

DOEpatents

Todt, Volker; Miller, Dean J.; Shi, Donglu; Sengupta, Suvankar

1998-01-01

A method of fabricating bulk YBa.sub.2 Cu.sub.3 O.sub.x where compressed powder oxides and/or carbonates of Y and Ba and Cu present in mole ratios to form YBa.sub.2 Cu.sub.3 O.sub.x are heated in the presence of a Nd.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y seed crystal to a temperature sufficient to form a liquid phase in the YBa.sub.2 Cu.sub.3 O.sub.x while maintaining the seed crystal solid. The materials are slowly cooled to provide a YBa.sub.2 Cu.sub.3 O.sub.x material having a predetermined number of domains between 1 and 5. Crack-free single domain materials can be formed using either plate shaped seed crystals or cube shaped seed crystals with a pedestal of preferential orientation material.

Thermo-optical characteristics and concentration quenching effects in Nd3+doped yttrium calcium borate glasses

NASA Astrophysics Data System (ADS)

Santos, D. R. S.; Santos, C. N.; de Camargo, A. S. S.; Silva, W. F.; Santos, W. Q.; Vermelho, M. V. D.; Astrath, N. G. C.; Malacarne, L. C.; Li, M. S.; Hernandes, A. C.; Ibanez, A.; Jacinto, C.

2011-03-01

In this work we present a comprehensive study of the spectroscopic and thermo-optical properties of a set of samples with composition xNd2O3-(5-x)Y2O3-40CaO-55B2O3 (0 ≤ x ≤ 1.0 mol%). Their fluorescence quantum efficiency (η) values were determined using the thermal lens technique and the dependence on the ionic concentration was analyzed in terms of energy transfer processes, based on the Förster-Dexter model of multipolar ion-ion interactions. A maximum η = 0.54 was found to be substantially higher than for yttrium aluminoborate crystals and glasses with comparable Nd3+ content. As for the thermo-optical properties of yttrium calcium borate, they are comparable to other well-known laser glasses. The obtained energy transfer microparameters and the weak dependence of η on the Nd3+ concentration with a high optimum Nd3+ concentration put this system as a strong candidate for photonics applications.

Synthesis and photoluminescence properties of Pb{sup 2+} doped inorganic borate phosphor NaSr{sub 4}(BO{sub 3}){sub 3}

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

Chauhan, A. O., E-mail: abhi2718@gmail.com; Koparkar, K. A.; Omanwar, S. K.

2016-05-06

A series of Inorganic borate phosphors NaSr{sub 4}(BO{sub 3}){sub 3} doped with Pb{sup 2+} was successfully synthesized by modified solid state diffusion method. The crystal structure and the phase purity of sample were characterized by powder X-ray diffraction (XRD). The photoluminescence properties of synthesized materials were investigated using spectrofluorometer at room temperature. The phosphor show strong broad band emission spectra in UVA region maximum at 370 nm under the excitation of 289 nm. The dependence of the emission intensity on the Pb{sup 2+} concentration for the NaSr{sub 4}(BO{sub 3}){sub 3} were studied in details. The concentration quenching of Pb{sup 2+}more » doped NaSr{sub 4}(BO{sub 3}){sub 3} was observed at 0.02 mol. The Stokes shifts of NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+} phosphor was calculated to be 7574 cm{sup −1}.« less

Infrared Optics Hot Pressed From Fluoride Glass

NASA Astrophysics Data System (ADS)

Turk, R. R.

1982-02-01

Optical figured surfaces were formed directly by hot pressing a fluoride glass in a closed die of tungsten carbide. Microduplication of the surface finish was also obtained. A glass composed of the fluorides of barium, thorium and zirconium or hafnium, and transmitting into the infrared out to 8 microns was press formed into an optical flat above its softening temperature and below its crystallization temperature. Also, small vitreous pieces were consolidated into larger pieces under moderate heat and pressure, thus avoiding the crystallization which occurs in large batches cooled from the melt.

Mg- and K-bearing borates and associated evaporites at Eagle Borax spring, Death Valley, California: A spectroscopic exploration

USGS Publications Warehouse

Crowley, J.K.

1996-01-01

Efflorescent crusts at the Eagle Borax spring in Death Valley, California, contain an array of rare Mg and K borate minerals, several of which are only known from one or two other localities. The Mg- and/or K-bearing borates include aristarainite, hydroboracite, kaliborite, mcallisterite, pinnoite, rivadavite, and santite. Ulexite and probertite also occur in the area, although their distribution is different from that of the Mg and K borates. Other evaporite minerals in the spring vicinity include halite, thenardite, eugsterite, gypsum-anhydrite, hexahydrite, and bloedite. Whereas the first five of these minerals are found throughout Death Valley, the last two Mg sulfates are more restricted in occurrence and are indicative of Mg-enriched ground water. Mineral associations observed at the Eagle Borax spring, and at many other borate deposits worldwide, can be explained by the chemical fractionation of borate-precipitating waters during the course of evaporative concentration. The Mg sulfate and Mg borate minerals in the Eagle Borax efflorescent crusts point to the fractionation of Ca by the operation of a chemical divide involving Ca carbonate and Na-Ca borate precipitation in the subsurface sediments. At many other borate mining localities, the occurrence of ulexite in both Na borate (borax-kernite) and Ca borate (ulexite-colemanite) deposits similarly reflects ulexite's coprecipitation with Ca carbonate at an early concentration stage. Such ulexite may perhaps be converted to colemanite by later reaction with the coexisting Ca carbonate - the latter providing the additional Ca2+ ions needed for the conversion. Mg and Ca-Mg borates are the expected late-stage concentration products of waters forming ulexite-colemanite deposits and are therefore most likely to occur in the marginal zones or nearby mud facies of ulexite-colemanite orebodies. Under some circumstances, Mg and Ca-Mg borates might provide a useful prospecting guide for ulexite-colemanite deposits, although the high solubility of Mg borate minerals may prevent their formation in lacustrine settings and certainly inhibits their geologic preservation. The occurrence of Mg borates in borax-kernite deposits is also related to fractionation processes and points to the operation of an Mg borate chemical divide, characterized by Mg borate precipitation ahead of Mg carbonate. All of these considerations imply that Mg is a significant chemical component of many borate-depositing ground waters, even though Mg borate minerals may not be strongly evident in borate orebodies. The Eagle Borax spring borates and other evaporite minerals were studied using spectroscopic and X-ray powder diffraction methods, which were found to be highly complementary. Spectral reflectance measurements provide a sensitive means for detecting borates present in mixtures with other evaporites and can be used to screen samples rapidly for X-ray diffraction analysis. The apparently limited occurrence of Mg and K borate minerals compared to Ca and Na borates may stem partly from the inefficiency of X-ray diffraction methods for delineating the mineralogy of large and complex deposits. Spectral reflectance measurements can be made in the laboratory, in the field, on the mine face, and even remotely. Reflectance data should have an important role in studies of existing deposit mineralogy and related chemical fractionation processes, and perhaps in the discovery of new borate mineral resources.

Synthesis and Characterization Materials M-Barium Hexaferrite Doping Ions Co-Mn Nano Particle

NASA Astrophysics Data System (ADS)

Susilawati; Doyan, A.; Sahlam

2017-05-01

This research has been success in the synthesis of M-Barium hexaferrite (BaM) doping Co-Mn ions using coprecipitation method are expected to be applied as a base material in the coating RADAR. M-Barium hexaferrite (BaM) are BaFe12-2xCoxMnxO19 synthesized with various concentrations (x = 0.0, 0.1, 0.2, 0.3) and the calcinations temperature (T = 400°C, 600°C, 800°C). The materials characterization using a X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM), Inductance Capacitance and resistance (LCR) meter, and Vibrating Sample Magnetometer (VSM) Instruments. The measurement results using XRD shows the material has a hexagonal crystalline structure. The measurement results using a TEM show a sample of nano crystal materials with grain diameters up to 40 nm and spacing of the crystal lattice. The measurement results using a LCR-meter shows the electric conductivity of 1.15 × 10-6 S/cm to BaM without doping, 3.75 × 10-6 S/cm to 0.1 doping concentration calcination temperature of 400 °C, and 1,23 × 10-5 S/cm to 0.3 doping concentration calcination temperature of 800 °C, thus including semiconductor materials. The magnetic properties of materials using a VSM test results show the value of coercivity of 0.1 T; remanence value of 0.06 emu/g; and the saturation value of 0.42 emu/g. The results above show BaM Co-Mn metal doping potential as anti-radar material.

Self-amplified optical pattern recognition system

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang (Inventor)

1994-01-01

A self amplifying optical pattern recognizer includes a geometric system configuration similar to that of a Vander Lugt holographic matched filter configuration with a photorefractive crystal specifically oriented with respect to the input beams. An extraordinarily polarized, spherically converging object image beam is formed by laser illumination of an input object image and applied through a photorefractive crystal, such as a barium titanite (BaTiO.sub.3) crystal. A volume or thin-film dif ORIGIN OF THE INVENTION The invention described herein was made in the performance of work under a NASA contract, and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the Contractor has elected to retain title.

Photovoltaic effect in ferroelectric ceramics

NASA Technical Reports Server (NTRS)

Epstein, D. J.; Linz, A.; Jenssen, H. P.

1982-01-01

The ceramic structure was simulated in a form that is more tractable to correlation between experiment and theory. Single crystals (of barium titanate) were fabricated in a simple corrugated structure in which the pedestals of the corrugation simulated the grain while the intervening cuts could be filled with materials simulating the grain boundaries. The observed photovoltages were extremely small (100 mv).

Effect of Sintering Temperature to Physical, Magnetic Properties and Crystal Structure on Permanent Magnet BaFe12O19 Prepared From Mill Scale

NASA Astrophysics Data System (ADS)

Ramlan; Muljadi; Sardjono, Priyo; Gulo, Fakhili; Setiabudidaya, Dedi

2017-07-01

Permanent magnet of Barium hexa Ferrite with formula BaFe12O19 has been made by metallurgy powder method from raw materials : Barium carbonate (BaCO3 E-merck) and Iron Oxide (Fe2O3 from mill scale). Both of raw materials have been mixed with stoichiometry composition by using a ball mill for 24 hours. The fine powder obtained from milling process was formed by using a hydraulic press at pressure 50 MPa and continued with sintering process. The sintering temperature was varied : 1150°C, 1200°C, 1250°C and 1300°C with holding time for 1 hour. The sintered samples were characterized such as : physical properties (bulk density, porosity and shrinkage), magnetic properties (flux density, remanence, coercivity and magnetic saturation) by using VSM and crystal structure by using XRD. According characterization results show that the crystal structure of BaFe12O19 does not change after sintering process, but the grain size tends to increase. The optimum condition is achieved at temperature 1250°C, and at this condition, the sample has characterization such as : bulk density = 4.35 g/cm3, porosity = 1.03% and firing shrinkage = 11.63%, flux density = 681.1 Gauss, remanence (σr) = 20.78 emu/g, coercivity (Hc) = 2058 Oe and magnetic saturation (σs) 45.16 emu/g.

Uranium(iii) complexes supported by hydrobis(mercaptoimidazolyl)borates: synthesis and oxidation chemistry.

PubMed

Maria, Leonor; Santos, Isabel C; Santos, Isabel

2018-05-23

The reaction of [UI3(thf)4] with the sodium or lithium salts of hydrobis(2-mercapto-1-methylimidazolyl)borate ligands ([H(R)B(timMe)2]-) in a 1 : 2 ratio, in tetrahydrofuran, gave the U(iii) complexes [UI{κ3-H,S,S'-H(R)B(timMe)2}2(thf)2] (R = H (1), Ph (2)) in good yields. Crystals of [UI{κ3-H,S,S'-H(Ph)B(timMe)2}2(thf)2] (2) were obtained by recrystallization from a tetrahydrofuran/acetonitrile solution, and the ion-separated uranium complex [U{κ3-H,S,S'-H(Ph)B(timMe)2}2(CH3CN)3][I] (3-I) was obtained by dissolution of 2 in acetonitrile followed by recrystallization. One-electron oxidation of 2 with AgBPh4 or I2 resulted in the formation of the cationic U(iv) complexes [U{κ3-H,S,S'-H(Ph)B(timMe)2}3][X] (X = BPh4 (6-BPh4), I (6-I)), due to a ligand redistribution process. These complexes are the first examples of homoleptic poly(azolyl)borate U(iv) complexes. Treatment of complex 2 with azobenzene led to the isolation of crystals of the U(iv) compound [UI{κ3-H(Ph)B(timMe)2}2(κ2-timMe)] (7). Treatment of 2 with pyridine-N oxide (pyNO) led to the formation of the uranyl complex [UO2{κ2-S,S'-H(Ph)B(timMe)2}2] (8) and of complex 6-I, while from the reaction of [U{κ3-H(Ph)B(timMe)2}2(thf)3][BPh4] (5) with pyNO, the oxo-bridged U(iv) complex [{U{κ3-H(Ph)B(timMe)2}2(pyNO)}2(μ-O)][BPh4]2 (9) was also obtained. In the U(iii) and U(iv) complexes, the bis(azolyl)borate ligands bind to the uranium center in a κ3-H,S,S' coordination mode, while in the U(vi) complex the ligands bind to the metal in a κ2-S,S' mode. The presence of UH-B interactions in the solid-state, for the nine-coordinate complexes 1, 2, 3, 6 and 7 and for the eight-coordinate complex 9, was supported by IR spectroscopy and/or X-ray diffraction analysis.

Penetration of boron from topically applied borate solutions

Treesearch

Stan T. Lebow; Patricia K. Lebow; Steven A. Halverson

2010-01-01

Borate penetration relies on diffusion when borate and glycol-borate preservatives are applied to the surface of wood. This study evaluated the extent of borate penetration in framing lumber as a function of preservative formulation, wood moisture content, and diffusion time after treatment. In Phase I of the study, end-matched specimens were conditioned to target...

1,1,2,2-Tetra­kis(dimethyl­amino)­ethane-1,2-diium bis­(tetra­phenyl­borate) acetone disolvate

PubMed Central

Tiritiris, Ioannis; Kantlehner, Willi

2012-01-01

The title compound, C10H24N4 2+·2C24H20B−·2C3H6O, crystallizes with two acetone solvent mol­ecules per asymmetric unit. In the dication, both amidinium units are twisted about the central C—C single bond by 63.8 (3)° and the positive charges are delocalized over both N—C—N planes. PMID:22590264

Understanding fifth-harmonic generation in CLBO

NASA Astrophysics Data System (ADS)

Patankar, S.; Yang, S. T.; Moody, J. D.; Bayramian, A. J.; Swadling, G. F.; Barker, D.; Datte, P.; Mennerat, G.; Norton, M.; Carr, C. W.; Begishev, I. A.; Bromage, J.; Ross, J. S.

2018-02-01

We report on results of fifth harmonic generation in Cesium Lithium Borate (CLBO) using a three-crystal cascaded frequency conversion scheme designed to study the energy balance of the final sum frequency generation stage. The experimental setup independently combines the first and fourth harmonic of a Nd:Glass laser in a 5mm thick CLBO crystal. Energy balance between the incoming and output energy is close to unity when the CLBO is out of phase matching and approximately 80% when the crystal is in phase matching. A detailed analysis of the residual fundamental and fourth harmonic energy indicates 5th harmonic light is being generated but only 26% is unaccounted for. We attribute the missing light to linear transmission loss in the CLBO oven. The ratio of the output to input energy is unity when the missing 5th harmonic is incorporated into the calculations. Two-dimensional plane wave mixing simulations show agreement with the results at lower intensities.

Effects of Borax on the Reduction of Pre-oxidized Panzhihua Ilmenite

NASA Astrophysics Data System (ADS)

Guo, Yufeng; Zheng, Fuqiang; Jiang, Tao; Chen, Feng; Wang, Shuai; Qiu, Guanzhou

2018-01-01

The effects of borax (sodium borate) on the enhancement reduction of pre-oxidized Panzhihua ilmenite were investigated. The effects of borax on the mineral phase transformation, microstructures, crystal cell parameter, melting point and Mg distribution were studied to reveal the mechanism of enhancement reduction. Under the constant reduction conditions, the borax could reduce the reduction activation energy of pre-oxidized ilmenite. The reduction kinetics analysis indicated that the reduction rate was controlled by interfacial chemical reaction. The reduction activation energy of the pre-oxidized ilmenite with 4% borax was 80.263 kJ/mol, which was 28.585 kJ/mol less than that of the pre-oxidized ilmenite without borax. Borax could eliminate the migration of Mg into the reduced particle center. The crystal cell parameter of the reduced product was increased by adding borax. Borax could improve the growth of dendritic crystals in the pre-oxidized ilmenite.

Relaxor properties of barium titanate crystals grown by Remeika method

NASA Astrophysics Data System (ADS)

Roth, Michel; Tiagunov, Jenia; Dul'kin, Evgeniy; Mojaev, Evgeny

2017-06-01

Barium titanate (BaTiO3, BT) crystals have been grown by the Remeika method using both the regular KF and mixed KF-NaF (0.6-0.4) solvents. Typical acute angle "butterfly wing" BT crystals have been obtained, and they were characterized using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy), conventional dielectric and acoustic emission methods. A typical wing has a triangular plate shape which is up to 0.5 mm thick with a 10-15 mm2 area. The plate has a (001) habit and an atomically smooth outer surface. Both K+ and F- solvent ions are incorporated as dopants into the crystal lattice during growth substituting for Ba2+ and O2- ions respectively. The dopants' distribution is found to be inhomogeneous, their content being almost an order of magnitude higher (up to 2 mol%) at out surface of the plate relatively to the bulk. A few μm thick surface layer is formed where a multidomain ferroelectric net is confined between two≤1 μm thick dopant-rich surfaces. The layer as a whole possess relaxor ferroelectric properties, which is apparent from the appearance of additional broad maxima, Tm, in the temperature dependence of the dielectric permittivity around the ferroelectric phase transition. Intense acoustic emission responses detected at temperatures corresponding to the Tm values allow to observe the Tm shift to lower temperatures at higher frequencies, or dispersion, typical for relaxor ferroelectrics. The outer surface of the BT wing can thus serve as a relaxor thin film for various electronic application, such as capacitors, or as a substrate for BT-based multiferroic structure. Crystals grown from KF-NaF fluxes contain sodium atoms as an additional impurity, but the crystal yield is much smaller, and while the ferroelectric transition peak is diffuse it does not show any sign of dispersion typical for relaxor behavior.

Stress dependence of the Raman spectrum of polycrystalline barium titanate in presence of localized domain texture

NASA Astrophysics Data System (ADS)

Sakashita, Tatsuo; Deluca, Marco; Yamamoto, Shinsuke; Chazono, Hirokazu; Pezzotti, Giuseppe

2007-06-01

The stress dependence of the Raman spectrum of polycrystalline barium titanate (BaTiO3, BT) ceramics has been examined with microprobe polarized Raman spectroscopy. The angular dependence of the Raman spectrum of the tetragonal BT crystal has been theoretically established, enabling us to assess the stress dependence of selected spectral modes without the influence of crystallographic domain orientation. Upon considering the frequency shift of selected Raman modes as a function of orientation between the crystallographic axis and the polarization vector of incident and scattered light, a suitable instrumental configuration has been selected, which allowed a direct residual stress measurement according to a modified piezospectroscopic procedure. The analysis is based on the selection of mixed photostimulated spectral modes in two perpendicular angular orientations.

Pathways for Metastable Carbonate Synthesis

NASA Astrophysics Data System (ADS)

Whittaker, Michael L.

Carbonate minerals are integral to life on earth, as reservoirs for CO 2 in the earth's natural carbon cycle and as the skeletal elements of abundant organisms like corals and plankton. Because of its relevance, availability, and low toxicity, calcium carbonate is also an important model system for phase transformations in aqueous solutions. However, it often does not conform to classical theories of nucleation, prompting a critical reevaluation of both the pathways of carbonate mineralization and the theories that describe them. Most importantly, it has been shown that amorphous calcium carbonate (ACC) is frequently a precursor to crystalline calcium carbonate during precipitation, in both biological and inorganic systems. Amorphous precursors influence phase transformations in several ways, including decoupling densification of ions in solution from their arrangement on a crystalline lattice, altering solution thermodynamics, creating new interfaces, and changing kinetic barriers. To exert control over these processes in vivo, organisms generally confine precipitation reactions to small volumes, often within lipid membrane vesicles. Herein, I describe in vitro model systems designed to elucidate and replicate biological mineralization pathways. Giant unilamellar vesicles are shown to slow the rate of crystallization of ACC by excluding nucleation accelerants, and by preserving the high kinetic barriers to lower energy phases that result. Phosphatidylcholine, one of the most abundant natural lipids, does not interact strongly with ACC, but the interfacial chemistry canbe tuned by changing the lipid charge or reducing steric shielding. Microfluidically produced water-in-oil emulsions were used as liposome analogs to study crystallization kinetics. In ensembles of hundreds of emulsion drops, we show that vaterite forms from ACC via a classical, two-step nucleation process. We also extend the classical theory of nucleation to highly confined aqueous systems, where the formation of a nucleus changes the system composition. In systems chemically similar to ACC, amorphous strontium carbonate (ASC) is also observed in liposomes, but crystallizes rapidly, while amorphous barium carbonate (ABC) is not. We show that ACC can be made with over 50% barium, forming ACBC, but crystallizes at a dramatically faster rate with increasing barium. I demonstrate that this process dramatically departs from the classical description applied to ACC crystallization. It can be explained by the increasing short- and mid-range order in ACBC with increasing barium, which resembles that of crystalline Ca1-xBaxCO3 and selectively lowers the barrier to its formation relative to lower-energy structures. This Ca1-xBaxCO3 phase has been misidentified as calcite in the literature, but we solve the structure, assign the new spacegroup R3m, and call it balcite. Balcite is only thermodynamically stable above 525°C, and is over 30% harder than calcite. In the absence of calcium, I show that ABC is a highly transient precursor to a previously uncharacterized BaCO3·H2 O phase. This phase forms as very thin (10 nm) and extremely anisotropic platelets, which themselves recrystallize rapidly into witherite (BaCO 3). These examples demonstrate the power of amorphous precursors to enable metastable crystalline materials through thermodynamically downhill transformations, and the ability of confined volumes to reduce the rate of these transformations and enable their quantification.

Haloacyl complexes of boron, [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I).

PubMed

Finze, Maik; Bernhardt, Eduard; Willner, Helge; Lehmann, Christian W

2005-11-04

The haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2 or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3B-C fragment. All borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B, 13C, 17O, 19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space group P2/c (no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6-311+G(d)].

Simultaneous effect of crystal lattice and non magnetic substitution on magnetic properties of barium hexaferrite

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Supriya, Sweety; Pradhan, Lagen Kumar; Pandey, Rabichandra; Kar, Manoranjan

2018-05-01

The aluminium doped barium hexaferrite BaFe12-xAlxO19 with x =0.0, 1.0, 2.0, 4.0 and 6.0 have been synthesized by the sol-gel method to modify the magnetic properties for technological applications. The crystal structure and phase purity of all the samples have been explored by employing the X-ray diffraction (XRD) technique. It confirms that the sample is nanocrystalline, hexagonal symmetry and all the intense peaks could be indexed to the P63/mmc space group. The obtained lattice parameters from the XRD analysis decrease with the increase in Al3+ content in the samples. The microstructural morphology and particle sizes of all samples were studied by using the Field Emission Scanning Electron Microscopy (FESEM-Hitachi-S4800) technique. The magnetic hysteresis (M-H) loops measurement has been carried out at room temperature by employing the vibrating sample magnetometer (VSM) over a field range of +20 kOe to -20 kOe. The magnetic hysteresis (M-H) loops revealed the ferromagnetic (hard magnetic materials) nature of the samples and, analyzed by using the Law of Approach to Saturation.

Crystal structure of BaMn2(AsO4)2 containing discrete [Mn4O18]28- units.

PubMed

Alcantar, Salvador; Ledbetter, Hollis R; Ranmohotti, Kulugammana G S

2017-12-01

In our attempt to search for mixed alkaline-earth and transition metal arsenates, the title compound, barium dimanganese(II) bis-(arsenate), has been synthesized by employing a high-temperature RbCl flux. The crystal structure of BaMn 2 (AsO 4 ) 2 is made up of MnO 6 octa-hedra and AsO 4 tetra-hedra assembled by sharing corners and edges into infinite slabs with composition [Mn 2 (AsO 4 ) 2 ] 2- that extend parallel to the ab plane. The barium cations reside between parallel slabs maintaining the inter-slab connectivity through coordination to eight oxygen anions. The layered anionic framework comprises weakly inter-acting [Mn 4 O 18 ] 28- tetra-meric units. In each tetra-mer, the manganese(II) cations are in a planar arrangement related by a center of inversion. Within the slabs, the tetra-meric units are separated from each other by 6.614 (2) Å (Mn⋯Mn distances). The title compound has isostructural analogues amongst synthetic Sr M 2 ( X O 4 ) 2 compounds with M = Ni, Co, and X = As, P.

Preparation of Scandium-Doped, Textured, M-Type Barium Ferrite via a Wet Magnetizing Orientation Process

NASA Astrophysics Data System (ADS)

Wang, Yu; Liu, Yingli; Zhang, Huaiwu; Li, Jie; Gao, Liwen; Chen, Daming; Chen, Yong

2018-02-01

In this paper, a wet magnetizing orientation process was applied to synthesize c-axis-textured, M-type barium ferrite (BaFe12O19 or BaM), which is widely used to produce hard magnetic materials. To modify the magnetic properties of the BaM ferrite and make it suitable for certain operating frequencies, Sc3+ was substituted into Fe3+ sites of the BaM crystal structure. A BaSc x Fe12- x O19 ferrite with a typical relative density of ˜ 75% was successfully obtained. We used x-ray diffraction, scanning electronic microscopy, and a vibrating sample magnetometer to obtain phase information, detail of the microstructure, and magnetic properties of the BaSc x Fe12- x O19, respectively. The composition BaSc x Fe12- x O19 ( x = 0.1) featured a superior squareness ratio of ˜ 67% and a saturation magnetization ( M S) of ˜ 5300 Gauss in magnetic hysteresis loop measurements. These features match well with requirements for self-biased passive devices. Moreover, the site preference of Sc3+ in the hexagonal crystal structure was investigated.

Divalent fluoride doped cerium fluoride scintillator

DOEpatents

Anderson, David F.; Sparrow, Robert W.

1991-01-01

The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites

NASA Astrophysics Data System (ADS)

Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

2017-05-01

Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.

Amount of leachant and water absorption levels of wood treated with borates and water repellents.

PubMed

Baysal, Ergun; Sonmez, Abdullah; Colak, Mehmet; Toker, Hilmi

2006-12-01

Wood protection efficacy of borates against biological agents, flame retardancy, and suitability to the environment is well known. Since borates can be applied to timber as water based solutions, they are preferred economically as well. Even though they are highly mobile in wood, boron compounds are widely used in timber preservation. Borates migrate in liquid and increase the hygroscopicity of wood in damp conditions. This study deals with the physical restriction of water access in wood by impregnating water repellent agents into wood to limit amount of leachant and water absorption levels of wood after boron treatment. Borates were incorporated with polyethylene glycol-400 (PEG-400) their bulking effect in wood was considered. Results indicated that the amount of leachates from wood treated with borates in PEG-400 was remarkably higher compared to those of wood treated with the aqueous solutions of borates. Water absorption (WA) levels of wood treated with aqueous solutions of borates were higher than those of their treated samples with the solutions in PEG-400. Secondary treatments of wood with the water repellent (WR) chemicals following borate impregnation reduced the leaching of chemicals from wood in water and also WA of the specimens were less than those of the wood treated with only borates from aqueous and PEG solutions. Styrene (St) was the most effective monomer among the other agents used in terms of immobility effect on borates and WA.

Barium iodide and strontium iodide crystals and scintillators implementing the same

DOEpatents

Payne, Stephen A.; Cherepy, Nerine; Pedrini, Christian; Burger, Arnold

2016-09-13

In one embodiment, a crystal includes at least one metal halide; and an activator dopant comprising ytterbium. In another general embodiment, a scintillator optic includes: at least one metal halide doped with a plurality of activators, the plurality of activators comprising: a first activator comprising europium, and a second activator comprising ytterbium. In yet another general embodiment, a method for manufacturing a crystal suitable for use in a scintillator includes mixing one or more salts with a source of at least one dopant activator comprising ytterbium; heating the mixture above a melting point of the salt(s); and cooling the heated mixture to a temperature below the melting point of the salts. Additional materials, systems, and methods are presented.

Combined effects of lithium and borate ions on the hydration of calcium sulfoaluminate cement

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

Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr; Dhoury, Mélanie; Champenois, Jean-Baptiste

This work investigates the combined influence of borate and lithium ions on the hydration of two calcium sulfoaluminate (CSA) cements containing 0 or 10 wt% gypsum. On the one hand, borates are known to retard CSA cement hydration due to the rapid precipitation of ulexite. On the other hand, lithium ions accelerate CSA cement hydration thanks to the fast precipitation of Li-containing aluminum hydroxide. When borates and lithium are present simultaneously, these two mechanisms are superimposed. With a gypsum-free cement, a third process is additionally observed: lithium promotes the initial precipitation of a borated AFm phase which is later convertedmore » into a borated AFt phase when hydration accelerates. Lithium salts can counteract the retardation by sodium borate. However, their influence is limited once a sufficient amount of Li-containing Al(OH){sub 3} seeds is formed. For the CSA cements under investigation, the threshold lithium concentration is close to 0.03 mmol/g of cement and similar with or without borate.« less

Characterization of Yb{sup 3+}:Sr{sub 5{minus}x}Ba{sub x}(PO{sub 4}){sub 3}F crystals for diode pumped lasers

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

Bayramian, A.J.; Marshall, C.D.; Schaffers, K.I.

Ytterbium-doped Sr{sub 5}(PO{sub 4}){sub 3}F (S-FAP) has been shown to be a useful material for diode pumping, since it displays high gain, low loss, and a long radiative lifetime. One of the issues with S-FAP is that it has a relatively narrow absorption bandwidth ({approximately}5 nm) at 900 nm, the diode-pumping wavelength, while the diode`s output bandwidth can be large ({approximately}10 nm). By changing the host slightly, the absorption feature can be broadened to better match the pump bandwidth. Four mixed crystal boules of Yb{sup 3+}:Sr{sub 5{minus}x}Ba{sub x}(PO{sub 4}){sub 3}F were grown by the Czochralski method with x = 0.25,more » 0.5, 1, and 2. The bandwidth of the 900-nm absorption feature was found to grow with increasing barium concentration from 4.7 nm to a maximum of 15.9 nm. Emission spectra showed a similar bandwidth increase with barium content from 4.9 nm to a maximum of 10 nm. Emission cross sections for these materials were deduced by the methods of reciprocity, the Einstein method, and small-signal gain. The absorption feature`s homogeneity was probed using a tunable pump source which qualitatively showed that the barium-broadened lines were at least partly inhomogeneous. Each of these materials lased with a variety of output couplers. This family of materials was found to provide suitable laser hosts where a broader absorption and/or emission bandwidth is desired.« less

Quantum Sensing and Communications Being Developed for Nanotechnology

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet; Seibert, Marc A.

2003-01-01

An interdisciplinary quantum communications and sensing research effort has been underway at the NASA Glenn Research Center since the summer of 2000. Researchers in the Communications Technology, Instrumentation and Controls, and Propulsion and Turbomachinery Divisions have been working together to study and develop techniques that use the principle of quantum entanglement (QE). This work is supported principally by the Nanotechnology Base R&T program at Glenn. As applied to communications and sensing, QE is an emerging technology that holds promise as a new and innovative way to communicate faster and farther, and to sense, measure, and image environmental properties in ways that are not possible with existing technology. Quantum entangled photons are "inseparable" as described by a wave function formalism. For two entangled photons, the term "inseparable" means that one cannot describe one photon without completely describing the other. This inseparability gives rise to what appears as "spooky," or nonintuitive, behavior because of the quantum nature of the process. For example, two entangled photons of lower energy can be created simultaneously from a single photon of higher energy in a process called spontaneous parametric down-conversion. Our research is focused on the use of polarization-entangled photons generated by passing a high-energy (blue) photon through a nonlinear beta barium borate crystal to generate two red photons that have orthogonal, but entangled, polarization states. Although the actual polarization state of any one photon is not known until it is measured, the act of measuring the polarization of one photon completely determines the polarization state of its twin because of entanglement. This unique relationship between the photons provides extra information about the system. For example, entanglement makes it easy to distinguish entangled photons from other photons impinging on a detector. For many other applications, ranging from quantum computation and information to quantum sensing, the entanglement property is critical.

Borates

USGS Publications Warehouse

Crangle, R.D.

2013-01-01

Four minerals represent 90 percent of the borates used by industry worldwide — the sodium borates (tincal and kernite), calcium borate (colemanite) and the sodium-calcium borate (ulexite). Borax is a white crystalline substance, chemically known as sodium tetraborate decahydrate, and is found naturally as the mineral tincal. Boric acid is a colorless crystalline solid sold in technical, national formulary and special quality grades as granules or powder and marketed most often as anhydrous boric acid. Deposits of borates are associated with volcanic activity and arid climates, with the largest economically viable deposits located in the Mojave Desert of the United States near Boron, CA, the Alpide belt in southern Asia and the Andean belt of South America.

Effect of ZnSe and CdSe nanoparticles on the fluorescence and optical band gap of Sm3+ doped lead borate glasses

NASA Astrophysics Data System (ADS)

Fatokun, Stephen O.

For the first part of this work, we prepared a series of Sm-doped lead borate (PbO-B2O3) glasses containing zinc selenide (ZnSe) and cadmium selenide (CdSe) nanoparticles (NPs) and studied the Sm 3+ fluorescence by varying the glass composition and size of the NPs. We have chosen these heavy metal oxide glasses to incorporate Sm3+ ions because they have large glass forming region, high refractive index, and good physical and thermal stability. Lead borate glasses with the following compositions xPbO:(96.5-x)B2O 3:0.5Sm2O3:3ZnSe/CdSe, x=36.5 and 56.5 mol%) are prepared using the melt-quenching method. Transmission electron microscopy characterization was done to confirm both nucleation and growth of the NPs for different annealing times. Fluorescence spectra of these samples are obtained with the excitation wavelengths at 403 and 477nm. Three fluorescence transitions are observed at 563 nm, 598 nm and 646 nm. The transition at 646 nm is a electric dipole (ED) transition that strongly depends on the covalency of the Sm-O bond and the asymmetry of the crystal field at the Sm3+ site. The 646 nm/598 nm fluorescence intensity ratio has been studied for different annealing times and PbO concentration for both ZnSe and CdSe samples. Longer annealing times tend to make the crystal field at the Sm3+ site more symmetric in nature for these glasses. The presence of CdSe NPs is seen to produce the greatest influence on the fluorescence intensity ratio. This is believed to be due to the larger size of the CdSe nanoparticles and its stronger influence on Sm3+ ions. The second part of this work was dedicated to the understanding of the optical band gap of samarium doped lead borate glasses with and without ZnSe/CdSe NPs. Optical absorption spectra for all these glass samples show their absorption edge in the ultraviolet region. Detailed analysis of the absorption edge was carried out using the Mott-Davis model and the optical band gap and the width of the tail in the band gap (Urbach edge) were obtained. Our glass samples show both direct and indirect transitions. For samples without the NPs, the optical band gap decreases with increasing PbO concentration. The presence of ZnSe NPs shows a similar trend. The introduction of CdSe NPs, however, shows an increase in the optical band gap with increase in PbO contents. Our results indicate that CdSe NPs show markedly different effect on the optical properties of lead borate glasses compared to ZnSe NPs. TEM characterization shows that CdSe NPs are considerably larger than ZnSe NPs. These size differences could produce significant differences in the electronic properties of these NPs and their interaction with the glass matrices.

Method of recycling lithium borate to lithium borohydride through methyl borate

DOEpatents

Filby, Evan E.

1977-01-01

This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a methyl borate intermediate to complete the recycle scheme.

40 CFR 721.10631 - Mixed metal borate (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal borate (generic). 721... Substances § 721.10631 Mixed metal borate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal borate (PMN P-12-64...

40 CFR 721.10631 - Mixed metal borate (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal borate (generic). 721... Substances § 721.10631 Mixed metal borate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal borate (PMN P-12-64...

Investigations on Mg-borate kinetics and mechanisms during evaporation, dilution and crystallization by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Peng, Jiaoyu; Chen, Jing; Dong, Yaping; Li, Wu

2018-06-01

Raman spectra of boron-concentrated, diluted, and corresponding mother solutions of brine were recorded at 298.15 K. The main polyborate anions present and their interactions in brine during evaporation and dilution were proposed according to the Raman spectra. The polyborate anions B(OH)3, B3O3(OH)4-, B5O6(OH)4-, and B6O7(OH)62- were found to be the main forms in boron-concentrated brine with B3O3(OH)4- ion being the principal form. Diluting brines with water accelerated depolymerization of B5O6(OH)4- and B6O7(OH)62- anions into B(OH)3 and B3O3(OH)4- ions and generated OH- ions, causing the pH of the solutions to increase from 4.2 to almost 8.0. Mg-borates precipitated from all diluted solutions could be classified as either hexaborates or triborates. A mechanism of solid phase transformation was also proposed and discussed based on Raman spectra analysis and solid species and solution pH data.

Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass

PubMed Central

Masai, Hirokazu; Yamada, Yasuhiro; Suzuki, Yuto; Teramura, Kentaro; Kanemitsu, Yoshihiko; Yoko, Toshinobu

2013-01-01

Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and formability. However, photoluminescence dynamics of ns2-type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn2+-doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S1-S0 transition and a slower T1-S0 relaxation, and also that the energy difference between T1 and S1 states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S1 and T1 states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors. PMID:24345869

Crystal structure of (1-eth­oxy­ethyl­idene)di­methyl­aza­nium tetra­phenyl­borate

PubMed Central

Tiritiris, Ioannis; Saur, Stefan; Kantlehner, Willi

2015-01-01

In the cation of the title salt, C6H14NO+·C24H20B−, the C—N bond lengths are 1.297 (2), 1.464 (2) and 1.468 (2) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.309 (2) Å shows double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. In the crystal, C—H⋯π inter­actions between the iminium H atoms and the phenyl C atoms of the anion are present. The phenyl rings form aromatic pockets, in which the iminium ions are embedded. PMID:26870564

A Simple Method Based on the Application of a CCD Camera as a Sensor to Detect Low Concentrations of Barium Sulfate in Suspension

PubMed Central

de Sena, Rodrigo Caciano; Soares, Matheus; Pereira, Maria Luiza Oliveira; da Silva, Rogério Cruz Domingues; do Rosário, Francisca Ferreira; da Silva, Joao Francisco Cajaiba

2011-01-01

The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue) color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds. PMID:22346607

The new high-pressure borate Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O-Formation of edge-sharing BO{sub 4} tetrahedra in a hydrated borate

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

Neumair, Stephanie C.; Kaindl, Reinhard; Huppertz, Hubert, E-mail: hubert.huppertz@uibk.ac.at

2012-01-15

The new borate hydrate Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O was synthesized under high-pressure/high-temperature conditions of 6 GPa and 880 Degree-Sign C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbam (Z=2) with the lattice parameters a=819.0(2), b=2016.9(4), c=769.9(2) pm, V=1.2717(4) nm{sup 3}, R{sub 1}=0.0758, wR{sub 2}=0.0836 (all data). The new structure type of Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O is built up from corner-sharing BO{sub 4} tetrahedra forming corrugated layers, that are interconnected among each other by two edge-sharing BO{sub 4} tetrahedra (B{sub 2}O{sub 6} units) forming Z-shaped channels. Interestingly, the heremore » presented structure of Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O is closely related to the structures of M{sub 6}B{sub 22}O{sub 39}{center_dot}H{sub 2}O (M=Fe, Co), which exhibit BO{sub 4} tetrahedra in an intermediate state on the way to edge-sharing BO{sub 4} tetrahedra. - Graphical Abstract: The new high-pressure borate hydrate Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O is built up from corner-sharing BO{sub 4} tetrahedra forming corrugated layers, that are interconnected among each other by two edge-sharing BO{sub 4} tetrahedra (B{sub 2}O{sub 6} units). In this paper we report on synthesis, structural details, and properties of the new compound Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O. Highlights: Black-Right-Pointing-Pointer High-pressure/high-temperature synthesis of the new borate hydrate Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O. Black-Right-Pointing-Pointer In the structure of Co{sub 7}B{sub 24}O{sub 42}(OH){sub 2}{center_dot}2 H{sub 2}O, two B{sub 2}O{sub 6} units are connected to 'vierer' rings. Black-Right-Pointing-Pointer Pressure favours the formation of edge-sharing BO{sub 4} tetrahedra in the chemistry of borates.« less

21 CFR 872.3400 - Karaya and sodium borate with or without acacia denture adhesive.

Code of Federal Regulations, 2010 CFR

2010-04-01

... denture adhesive. 872.3400 Section 872.3400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... and sodium borate with or without acacia denture adhesive. (a) Identification. A karaya and sodium borate with or without acacia denture adhesive is a device composed of karaya and sodium borate with or...

Potassium deca­borate monohydrate

PubMed Central

Gao, Yi-Hong

2011-01-01

In the crystal structure of the title compound, K2[B10O14(OH)4]·H2O, the polyborate [B10O14(OH)4]2− anions are linked together through their common O atoms, forming a helical chain-like structure. Adjacent chains are further connected into a three-dimensional structure by O—H⋯O hydrogen bonds. The water mol­ecules and potassium cations are located between these chains. Further O—H⋯O hydrogen bonds occur between the anions and the water mol­ecules PMID:22058681

Characterization of the Terminal Iron(IV) Imides {[PhBPtBu2(pz’)]FeIV≡NAd}+

PubMed Central

Thomas, Christine M.; Mankad, Neal P.; Peters, Jonas C.

2008-01-01

New hybrid bis(phosphine)(pyrazole)borate tripodal ligands ([PhBPtBu2(pz’)]−) are reported that support pseudotetrahedral iron in the oxidation states +1, +2, +3, and +4. The higher oxidation states are stabilized by a terminal Fe≡NR linkage. Of particular interest is the generation and thorough characterization of an S = 1 FeIV≡NR+ imide cation using this new ligand system. The latter species can be observed electrochemically and spectroscopically, and its solid-state crystal structure is reported. PMID:16608321

Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells

PubMed Central

Matsuoka, Ken

2013-01-01

In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species. PMID:24715955

Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells.

PubMed

Yamauchi, Noboru; Gosho, Tadashi; Asatuma, Satoru; Toyooka, Kiminori; Fujiwara, Toru; Matsuoka, Ken

2013-01-01

In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species.

Low-energy neutron detector based upon lithium lanthanide borate scintillators

DOEpatents

Czirr, John B.

1998-01-01

An apparatus for detecting neutrons includes a cerium activated scintillation crystal containing .sup.10 B, with the scintillation crystal emitting light in response to .alpha. particles emitted from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus also includes a gamma scintillator positioned adjacent the crystal and which generates light in response to gamma rays emitted from the decay of Li*. The apparatus further includes a first and a second light-to-electronic signal converter each positioned to respectively receive light from the crystal and the gamma scintillator, and each respectively outputting first and second electronic signals representative of .alpha. particles from the .sup.10 B(n,.alpha.)Li* reaction and gamma rays from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus includes a coincidence circuit connected to receive the first and second signals and which generates a coincidence signal when the first and second signals coincide. The apparatus also includes a data analyzer for receiving an additional signal from at least one of the first and second converters, and for operating in response to the coincidence signal.

Radiation effects and defects in lithium borate crystals

NASA Astrophysics Data System (ADS)

Ogorodnikov, Igor N.; Poryvay, Nikita E.; Pustovarov, Vladimir A.

2010-11-01

The paper presents the results of a study of the formation and decay of lattice defects in wide band-gap optical crystals of LiB3O5 (LBO), Li2B4O7 (LTB) and Li6Gd(BO3)3 (LGBO) with a sublattice of mobile lithium cations. By means of thermoluminescence techniques, and luminescent and absorption optical spectroscopy with a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption in these crystals in the visible and ultraviolet spectral ranges is produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines mainly the optical absorption spectral profile, and the relaxation kinetics is rated by the interdefect non-radiative tunnel recombination between the trapped-hole center and the Li0 trapped-electron centers. At 290 K, the Li0 centers are subject to thermally stimulated migration. Based on experimental results, the overall picture of thermally stimulated recombination processes with the participation of shallow traps was established for these crystals.

Multiple seeding for the growth of bulk GdBCO-Ag superconductors with single grain behaviour

NASA Astrophysics Data System (ADS)

Shi, Y.; Durrell, J. H.; Dennis, A. R.; Huang, K.; Namburi, D. K.; Zhou, D.; Cardwell, D. A.

2017-01-01

Rare earth-barium-copper oxide bulk superconductors fabricated in large or complicated geometries are required for a variety of engineering applications. Initiating crystal growth from multiple seeds reduces the time taken to melt-process individual samples and can reduce the problem of poor crystal texture away from the seed. Grain boundaries between regions of independent crystal growth can reduce significantly the flow of current due to crystallographic misalignment and the agglomeration of impurity phases. Enhanced supercurrent flow at such boundaries has been achieved by minimising the depth of the boundary between A growth sectors generated during the melt growth process by reducing second phase agglomerations and by a new technique for initiating crystal growth that minimises the misalignment between different growth regions. The trapped magnetic fields measured for the resulting samples exhibit a single trapped field peak indicating they are equivalent to conventional single grains.

North Pacific barium isotope distributions illustrate importance of ocean mixing in controlling barium distributions despite weak regional circulation

NASA Astrophysics Data System (ADS)

Geyman, B.; Auro, M. E. E.; LaVigne, M.; Ptacek, J. L.; Horner, T. J.

2016-12-01

The dissolved behavior of barium in the ocean exhibits a `refractory' nutrient-type profile similar to that of silicon, which has led to the use of Ba as a proxy for paleo-productivity and carbon cycling. Marine barium cycling appears to be controlled by the precipitation of micron-scale barite crystals in the mesopelagic and their subsequent dissolution throughout the water column, which has been shown to impart an isotopic signature that may itself harbor information about ocean circulation and export production. However, the utility of Ba-based proxies in chemical and paleoceanography relies on a sound understanding of the processes governing marine barium distributions, which remain unresolved. Here, we report the first full oceanographic depth profile of barium isotopes from the North Pacific Ocean (30 N, 140 W), which offers the ability to resolve biogeochemical cycling from mixing processes in a given water mass. Our data confirm findings from other oceanographic regions showing a close coupling between increasing [Ba] and decreasing Ba-isotope compositions with depth. Unlike other profiles however, this coupling is restricted to the upper 1,000 m of the North Pacific water column, with samples from between 1,000 m and 4,500 m showing a roughly 60 % increase in [Ba] but essentially no changes in their Ba-isotope compositions (within measurement uncertainty of 15 ppm/AMU). As with Atlantic data, samples spanning the entire profile define a linear trend (R2 > 0.9) when plotted as Ba-isotope compositions against 1/[Ba], indicating that conservative mixing can account for much of the Ba-isotope variation in the North Pacific water column. Overall, these findings highlight the utility of stable isotope measurements to illuminate the processes governing nutrient cycling, and support the critical role of large-scale ocean circulation in setting `refractory' nutrient distributions. These results have particular relevance to regions with relatively weak overturning circulation, such as the North Pacific, because they elucidate the mechanistic basis that underpins Ba/Ca and other Ba-based tracers of the marine carbon cycle in paleoceanography.

Effective binding of perhalogenated closo-borates to serum albumins revealed by spectroscopic and ITC studies

NASA Astrophysics Data System (ADS)

Kuperman, Marina V.; Losytskyy, Mykhaylo Yu.; Bykov, Alexander Yu.; Yarmoluk, Sergiy M.; Zhizhin, Konstantin Yu.; Kuznetsov, Nikolay T.; Varzatskii, Oleg A.; Gumienna-Kontecka, Elzbieta; Kovalska, Vladyslava B.

2017-08-01

The interactions of boron cluster compounds closo-borates with biomolecules are widely studied due to their efficiency as agents for boron neutron capture therapy of cancer. In present work the binding abilities of anionic halogen closo-borates [B10Hal10]2- (Hal = Cl, Br, I) and [B12Hal12]2- (Hal = Cl, I) towards bovine and human serum albumins were investigated by spectroscopic and isothermal titration calorimetry (ITC) methods. The protein fluorescence quenching method and ITC studies confirmed the complex formation. The degree of protein fluorescence quenching increased from chlorine to iodine boron derivatives that is attributed to external heavy atom effect. The ITC data point on the existence in the protein structure of two types of binding sites: with higher and lower affinity to closo-borates. Albumin-closo-borate complex binding ratio, n (4-5 anions per protein molecule) is higher than for the parent hydrogen closo-borates (2 anions per protein molecule). Binding constants estimated by fluorescent and ITC methods indicate higher affinity of halogen closo-borates to albumins (K in the range of 104-106 M-1) comparing to that of the hydrogen closo-borate (K about 103 M-1). Due to their high affinity and high binding ratio to albumins halogen closo-borates are proposed for further studies as agents for boron neutron capture therapy.

A fresnoite-structure-related mixed valent titanium(III/IV) chlorosilicate, Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl: A flux crystal growth route to Ti(III) containing oxides

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

Abeysinghe, Dileka; Smith, Mark D.; Loye, Hans-Conrad zur, E-mail: zurloye@mailbox.sc.edu

Single crystals of mixed valent barium titanium(III/IV) chlorosilicate, Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09}, were grown in a high temperature molten chloride flux involving an in situ reduction step. The fresnoite structure related Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09} crystallizes in the tetragonal space group P4/mbm with lattice parameters of a=8.6717(2) Å, c=18.6492(5) Å. The title compound exhibits a 3D structure consisting of 2D layers of fused Ti{sub 2}O{sub 9} and Si{sub 4}O{sub 12} groups and 2D layers of fused Ti{sub 2}O{sub 9}Cl{sub 2} and Si{sub 2}O{sub 7} groups that are linked via barium atoms. The in situmore » reduction of Ti(IV) to Ti(III) is achieved via the addition of metallic Mg to the flux to function as the reducing agent. The temperature dependence of the magnetic susceptibility shows simple paramagnetism above 100 K. There is a discontinuity in the susceptibility data below 100 K, which might be due to a structural change that takes place resulting in charge ordering. - Graphical abstract: The fresnoite structure related novel reduced barium titanium chlorosilicate, Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09}, were synthesized via flux method. An in situ reduction of Ti(IV) to Ti(III) achieved using Mg metal. The 3D structure consists 2D layers of fused Ti{sub 2}O{sub 9} and Si{sub 4}O{sub 12} and 2D layers of fused Ti{sub 2}O{sub 9}Cl{sub 2} and Si{sub 2}O{sub 7} connected via barium atoms. Compound shows simple paramagnetism above 100 K. - Highlights: • The fresnoite related Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09} were grown via molten flux method. • The in situ reduction of Ti(IV) to Ti(III) is achieved using metallic Mg. • 2D layers of Ti{sub 2}O{sub 9} and Si{sub 4}O{sub 12} and Ti{sub 2}O{sub 9}Cl{sub 2} and Si{sub 2}O{sub 7} connect via Ba atoms. • The magnetic susceptibility shows simple paramagnetism above 100 K.« less

Influence of processing parameters on the structure and properties of barium strontium titanate ceramics

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

Yun Sining; Department of Materials Physics, School of Science, Xi'an Jiaotong University, Xi'an 710049; Wang Xiaoli

2008-08-04

Barium strontium titanate (BST) with the molar formula (Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}) has been prepared by two different processing methods: mixed-oxide (BST-MO) and reaction-sintering (BST-RS). X-ray powder diffraction study shows differences in grain size and crystal symmetry for both these ceramics. The former shows a tetragonal symmetry while the latter presents a cubic symmetry. The occurrence of polar micro-regions associated with the higher chemical non-homogeneous distribution of ion defects from the influence of the processing parameters is the main reason for the higher peak dielectric constant (K{sub m}), the higher remanent polarization (P{sub r}), the higher coercive field (E{sub c}),more » the higher peak current density (J{sub m}), and the lower temperature of peak dielectric constant (T{sub m}) in BST-MO ceramics.« less

Ternary borate-nucleoside complex stabilization by Ribonuclease A demonstrates phosphate mimicry

PubMed Central

Gabel, Scott A.; London, Robert E.

2010-01-01

Phosphate esters play a central role in cellular energetics, biochemical activation, signal transduction and conformational switching. The structural homology of the borate anion with phosphate, combined with its ability to spontaneously esterify hydroxyl groups, suggested that phosphate-ester recognition sites on proteins might exhibit significant affinity for non-enzymatically formed borate esters. 11B NMR studies and activity measurements on ribonuclease A in the presence of borate and several cytidine analogs demonstrate the formation of a stable ternary RNase A•3′-deoxycytidine-2′-borate ternary complex that mimics the complex formed between RNase A and a 2′-cytidine monophosphate (2′-CMP) inhibitor. Alternatively, no slowly exchanging borate resonance is observed for a ternary RNase A, borate, 2′-deoxycytidine mixture, demonstrating the critical importance of the 2′-hydroxyl group for complex formation. Titration of the ternary complex with 2′-CMP shows that it can displace the bound borate ester with a binding constant that is close to the reported inhibition constant of RNase A by 2′CMP. RNase A binding of a cyclic cytidine-2′,3′-borate ester, which is a structural homolog of the cytidine-2′,3′-cyclic phosphate substrate, could also be demonstrated. The apparent dissociation constant for the cytidine-2′,3′-borate•RNase A complex is 0.8 mM, which compares with a Michaelis constant of 11 mM for cCMP at pH 7, indicating considerably stronger binding. However, the value is 1000-fold larger than the reported dissociation constant of the RNase A complex with uridine-vanadate. These results are consistent with recent reports suggesting that in situ formation of borate esters that mimic the corresponding phosphate esters support enzyme catalysis. PMID:17957392

A novel mixed-metal borate with large [B12O18(OH)6]6- motif: Synthesis, structure and property

NASA Astrophysics Data System (ADS)

Wei, Li; Pan, Jie; Xue, Zhen-Zhen; Wang, Guo-Ming; Wang, Ying-Xia

2018-01-01

A new mixed-metal polyborate, Na5Li[B12O18(OH)6]·2H2O (1), has been synthesized using solvothermal method and characterized by IR spectroscopy, thermogravimetric analysis, UV-Vis spectroscopy, powder and single-crystal X-ray diffraction, respectively. It crystallizes in the trigonal space group R-3c (No. 167) with unit cell parameters of a = b = 9.6767(6) Å, c = 36.358(5) Å, and Z = 6. Its structure features unprecedented 3D framework constructed from novel honeycomb-shaped inorganic Na-O sheets with unique 12-MR sodium rings and supramolecular polyborate 2D layers of lithium-centered [B12O18(OH)6]6-. UV-Vis spectral characterization indicates that compound 1 is a wide-band-gap semiconductor.

Simultaneous immobilization of borate, arsenate, and silicate from geothermal water derived from mining activity by co-precipitation with hydroxyapatite.

PubMed

Sasaki, Keiko; Hayashi, Yoshikazu; Toshiyuki, Kenta; Guo, Binglin

2018-09-01

The treatment of the geothermal water discharged through mining activity is a critical issue because the rate of discharge is 12,000 m 3 per day and the discharge contains high concentrations of borate (>20 mg/L) and arsenate (ca. 0.4 mg/L) as well as silicate and carbonate. The simultaneous reduction of borate and arsenate concentrations to acceptable levels was successfully performed by co-precipitation with hydroxyapatite (HAp). Although the coexisting high concentrations of carbonate act as a disturbing element, the co-precipitation equilibrium of borate was shifted to lower values by adjusting the P/Ca molar ratio, and the removal rate of borate was accelerated by using Al 3+ additives, resulting in the efficient reduction of borate within 1 h. The initially immobilized boron in HAp is in the tetragonal form, which probably occupies the hydroxyl sites in HAp, gradually transforming into the trigonal form in the solid state, as interpreted by 1 H NMR and 11 B-NMR. The coexisting silicate was also immobilized in an ellestadite form, as confirmed by 29 Si-NMR measurements. Arsenate and silicate were immobilized before borate in geothermal water. A dissolution assay of borate in the solid residues after co-precipitation with HAp verified the acceptable stability of borate, which is independent of the amount of added Al 3+ . Copyright © 2018 Elsevier Ltd. All rights reserved.

Borates

USGS Publications Warehouse

Angulo, M.A.

2011-01-01

The article discusses the latest developments in the borates industry, particularly in the U.S., as of June 2011. It claims that the biggest economically feasible deposits of borates are seen in the U.S.' Mojave Desert, the Alpide belt in southern Asia and the Andean belt of South America. Turkish state-owned mining firm Eti Maden AS reported that borates were mainly used in the manufacture of glass, ceramics, fertilizer and detergent in 2009.

Crystallographic control on the boron isotope paleo-pH proxy

NASA Astrophysics Data System (ADS)

Noireaux, J.; Mavromatis, V.; Gaillardet, J.; Schott, J.; Montouillout, V.; Louvat, P.; Rollion-Bard, C.; Neuville, D. R.

2015-11-01

When using the boron isotopic composition (δ11B) of marine carbonates as a seawater pH proxy, it is assumed that only the tetrahedral borate ion is incorporated into the growing carbonate crystals and that no boron isotope fractionation occurs during uptake. However, the δ11B of the calcium carbonate from most modern foraminifera shells or corals skeletons is not the same as the δ11B of seawater borate, which depends on pH, an observation commonly attributed to vital effects. In this study, we combined previously published high-field 11B MAS NMR and new δ11B measurements on the same synthetic calcite and aragonite samples precipitated inorganically under controlled environments to avoid vital effects. Our results indicate that the main controlling factors of δ11B are the solution pH and the mineralogy of the precipitated carbonate mineral, whereas the aqueous boron concentration of the solution, CaCO3 precipitation rate and the presence or absence of growth seeds all appear to have negligible influence. In aragonite, the NMR data show that boron coordination is tetrahedral (BO4), in addition, its δ11B is equal to that of aqueous borate, thus confirming the paleo-pH hypothesis. In contrast, both trigonal BO3 and tetrahedral BO4 are present in calcite, and its δ11B values are higher than that of aqueous borate and are less sensitive to solution pH variations compared to δ11B in aragonite. These observations are interpreted in calcite as a reflection of the incorporation of decreasing amounts of boric acid with increasing pH. Moreover, the fraction of BO3 measured by NMR in calcite is higher than that inferred from δ11B which indicates a coordination change from BO4 to BO3 upon boron incorporation in the solid. Overall, this study shows that although the observed differences in δ11B between inorganic and biological aragonite are compatible with a pH increase at calcification sites, the B speciation and isotope composition of biological calcites call for a more complex mechanism of boron incorporation.

Three-dimensional barium-sulfate-impregnated reduced graphene oxide aerogel for removal of strontium from aqueous solutions

NASA Astrophysics Data System (ADS)

Jang, Jiseon; Lee, Dae Sung

2018-06-01

A three-dimensional barium-sulfate-impregnated reduced graphene oxide (BaSO4-rGO) aerogel was successfully synthesized by a facile one-step hydrothermal method and was used as an adsorbent to remove strontium from aqueous solutions. The characterized elemental composition, crystal structure, and morphology of the prepared aerogel confirmed that barium sulfate particles were firmly anchored on the surface of the rGO sheets and exhibited a porous 3D structure with a high surface area of 129.37 m2/g. The mass ratio of BaSO4 in the BaSO4-rGO aerogel substantially affected strontium adsorption, and the optimal BaSO4/rGO ratio was found to be 1:1. The synthesized BaSO4-rGO aerogel not only reached adsorption equilibrium within 1 h, but also showed much higher adsorption capacity than an rGO aerogel. The experimental data were well fitted to a pseudo-second-order kinetic model and the adsorption behavior followed the Langmuir isotherm. The adsorption capacity of strontium on BaSO4-rGO aerogels remained relatively high even under ionic competition in simulated seawater. These results showed that the BaSO4-rGO aerogel is an efficient and promising adsorbent for the treatment of strontium in aqueous solutions.

Characterisation of mineralogical forms of barium and trace heavy metal impurities in commercial barytes by EPMA, XRD and ICP-MS.

PubMed

Ansari, T M; Marr, I L; Coats, A M

2001-02-01

This study was carried out to characterise the mineralogical forms of barium and the trace heavy metal impurities in commercial barytes of different origins using electron probe microanalysis (EPMA), X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). Qualitative EPMA results show the presence of typically eight different minerals in commercial barytes including barite (BaSO4), barium feldspar, galena (PbS), pyrite (FeS2), sphalerite (ZnS), quartz (SiO2), and silicates, etc. Quantitative EPMA confirms that the barite crystals in the barytes contain some strontium and a little calcium, whereas trace heavy metals occur in the associated minerals. Analysis of aqua regia extracts of barytes samples by ICP-MS has shown the presence of a large number of elements in the associated minerals. Arsenic, copper and zinc concentrations correlate closely in all 10 samples. The findings suggest that barytes is not, as traditionally thought, an inert mineral, but is a potentially toxic substance due to its associated heavy metal impurities, which can be determined by an aqua regia digest without the need for complete dissolution of the barite itself. X-ray powder diffraction was not informative as the complex barite pattern masks the very weak lines from the small amounts of associated minerals.

Complete Transmetalation in a Metal-Organic Framework by Metal Ion Metathesis in a Single Crystal for Selective Sensing of Phosphate Ions in Aqueous Media.

PubMed

Asha, K S; Bhattacharjee, Rameswar; Mandal, Sukhendu

2016-09-12

A complete transmetalation has been achieved on a barium metal-organic framework (MOF), leading to the isolation of a new Tb-MOF in a single-crystal (SC) to single-crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core-shell metal exchange through dissociation of metal-ligand bonds. This Tb-MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and evaluation of aminoborates derived from boric acid and diols for protecting wood against fungal and thermal degradation

Treesearch

George C. Chen

2008-01-01

N-methyl amino catechol borate (1), N-methyl amino-4-methyl catechol borate (2), N-methyl amino-4-t-butyl catechol borate (3), and N-methyl amino-2, 3-naphthyl borate (4) were synthesized by reflux of boric acid with a diol in solvent N,N-dimethyl formamide. The aminoborates were characterized by proton nuclear magnetic resonance spectroscopy, FTIR spectroscopy and...

Recent advances in rare earth doped alkali-alkaline earth borates for solid state lighting applications

NASA Astrophysics Data System (ADS)

Verma, Shefali; Verma, Kartikey; Kumar, Deepak; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

2018-04-01

As a novel class of inorganic phosphor, the alkali-alkaline earth borate phosphors have gained huge attention due to their charming applications in solid-state lighting (SSL) and display devices. The current research drive shows that phosphors based on the alkali-alkaline earth borates have transformed the science and technology due to their high transparency over a broad spectral range, their flexibility in structure and durability for mechanical and high-laser applications. Recent advances in various aspects of rare-earth (RE) doped borate based phosphors and their utilizations in SSL and light emitting diodes are summarized in this review article. Moreover, the present status and upcoming scenario of RE-doped borate phosphors were reviewed in general along with the proper credential from the existing literature. It is believed that this review is a sole compilation of crucial information about the RE-doped borate phosphors in a single platform.

Microgravity

NASA Image and Video Library

1998-02-05

This graph depicts the increased signal quality possible with optical fibers made from ZBLAN, a family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium) as compared to silica fibers. NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. In the graph, a line closer to the black theoretical maximum line is better. Photo credit: NASA/Marshall Space Flight Center

Stimulated Raman amplification, oscillation, and linewidth in barium nitrate

NASA Technical Reports Server (NTRS)

McCray, Christopher J.; Chyba, Thomas H.

1998-01-01

Measurements of Raman gain in a Ba(NO3)2 crystal are reported at 532 nm using a Raman oscillator/amplifier arrangement for differential absorption lidar measurements of ozone. The experimentally determined gain coefficient will be compared with theoretical results. The effect of single and multi-longitudinal mode pumping upon the amplification process will be discussed. Measurement of the Raman linewidth for 1st 2nd and 3d stokes shifts arc presented.

Real-time generation of the Wigner distribution of complex functions using phase conjugation in photorefractive materials.

PubMed

Sun, P C; Fainman, Y

1990-09-01

An optical processor for real-time generation of the Wigner distribution of complex amplitude functions is introduced. The phase conjugation of the input signal is accomplished by a highly efficient self-pumped phase conjugator based on a 45 degrees -cut barium titanate photorefractive crystal. Experimental results on the real-time generation of Wigner distribution slices for complex amplitude two-dimensional optical functions are presented and discussed.

Coated conductors

DOEpatents

Arendt, Paul N.; Foltyn, Stephen R.; Stan, Liliana; Usov, Igor O.; Wang, Haiyan

2010-06-15

Articles are provided including a base substrate having a layer of an IBAD oriented material thereon, and, a layer of barium-containing material selected from the group consisting of barium zirconate, barium hafnate, barium titanate, barium strontium titanate, barium dysprosium zirconate, barium neodymium zirconate and barium samarium zirconate, or a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the layer of an IBAD oriented material. Such articles can further include thin films of high temperature superconductive oxides such as YBCO upon the layer of barium-containing material selected from the group consisting of barium zirconate, barium hafnate, barium titanate, barium strontium titanate, barium dysprosium zirconate, barium neodymium zirconate and barium samarium zirconate, or a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates.

Nano crystalline Bi2(VO5) phases in lithium bismuth borate glasses containing mixed vanadium-nickel oxides

NASA Astrophysics Data System (ADS)

Yadav, Arti; Khasa, S.; Dahiya, M. S.; Agarwal, A.

2016-05-01

Glass composition 7V2O5.23Li2O.20Bi2O3.50B2O3 and x(2NiO.V2O5).(30-x)Li2O.20Bi2O3.50B2O3, x=0, 2, 5, 7 and 10, were produced by conventional melt quenching technique. The quenched amorphous glass samples were annealed at temperatures 400°C and 500°C for 6 hours. The Bi2(VO5) crystallite were grown in all prepared glass matrix. Tn vanadium lithium bismuth borate glass (annealed), the some phrase of V2O5-crystal were observed along with the nano crystalline Bi2(VO5) phase. The sharp peaks in FTTR spectra of all annealed compositions were also compatible with the XRD diffraction peaks of the system under investigation. Average crystalline size (D) of the Bi2(VO5) nano-crystallite was ~30nm for samples annealed at 400°C and ~42nm for samples annealed at 500°C. Lattice parameter and the lattice strain for all the samples was also calculated corresponding to the (113) plane of Bi2(VO5) crystallite.

Structural and optical properties of lithium sodium borate glasses doped with Sm3+ ions

NASA Astrophysics Data System (ADS)

Dawaud, R. S. E. S.; Hashim, S.; Alajerami, Y. S. M.; Mhareb, M. H. A.; Maqableh, M. M.; Tamchek, N.

2014-07-01

Absorption and emission spectra of Sm3+ doped lithium sodium borate (LNB) have been reported. The samples were prepared by the melt-quenching technique and characterized by X-ray diffraction (XRD), diffraction thermal analysis (DTA), Fourier transforms infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). From the thermo-grams spectrum, glass transition (Tg), crystallization (Tc) and melting temperatures (Tm) have been evaluated. Direct and indirect optical band gaps have been calculated based on the glasses UV absorption spectra. These glasses have shown strong nine absorption bands with hypersensitive transition at 1221 nm (6H5/2→4H3/2) and five emission bands for the transition at 4I7/2→6H13/2 (green color), 4I7/2→6H7/2 (orange color), 4I7/2→6H9/2 (orange color), 4I7/2→6H11/2 (red color) and 4I7/2→6H13/2 (red color) with performing an excitation of 400 nm. The oscillator strengths, refractive index, ions concentration, polaron radius and other parameters have been calculated for each dopant.

Tris-borate is a poor counterion for RNA: a cautionary tale for RNA folding studies

PubMed Central

Buchmueller, Karen L.; Weeks, Kevin M.

2004-01-01

Native polyacrylamide gel electrophoresis is a powerful approach for visualizing RNA folding states and folding intermediates. Tris-borate has a high-buffering capacity and is therefore widely used in electrophoresis-based investigations of RNA structure and folding. However, the effectiveness of Tris-borate as a counterion for RNA has not been systematically investigated. In a recirculated Hepes/KCl buffer, the catalytic core of the bI5 group I intron RNA undergoes a conformational collapse characterized by a bulk transition midpoint, or Mg1/2, of ∼3 mM, consistent with extensive independent biochemical experiments. In contrast, in Tris-borate, RNA collapse has a much smaller apparent Mg1/2, equal to 0.1 mM, because in this buffer the RNA undergoes a different, large amplitude, folding transition at low Mg2+ concentrations. Analysis of structural neighbors using a short-lived, RNA-tethered, photocrosslinker indicates that the global RNA structure eventually converges in the two buffer systems, as the divalent ion concentration approaches ∼1 mM Mg2+. The weak capacity of Tris-borate to stabilize RNA folding may reflect relatively unfavorable interactions between the bulky Tris-borate ion and RNA or partial coordination of RNA functional groups by borate. Under some conditions, Tris-borate is a poor counterion for RNA and its use merits careful evaluation in RNA folding studies. PMID:15601995

Bioactive glass/polymer composites for bone and nerve repair and regeneration

NASA Astrophysics Data System (ADS)

Mohammadkhah, Ali

Bioactive glasses have several attractive properties in hard and soft tissue repair but their brittleness limited their use, as scaffolding materials, for applications in load-bearing hard tissue repair. At the same time, because of their bioactive properties, they are being studied more often for soft tissue repair. In the present work, a new glass/polymer composite scaffold was developed for the repair of load-bearing bones with high flexural strength and without brittle behavior. The new composites have 2.5 times higher flexural strength and ˜100 times higher work of fracture (without catastrophic failure) compared to a similar bare glass scaffold. Also the use of two known bioactive glasses (13-93-B3 and 45S5) was investigated in developing glass/Poly(epsilon-caprolactone) (PCL) composite films for peripheral nerve repair. It was found that a layer of globular hydroxyapatite (HA) formed on both sides of the composites. The borate glass in the composites was fully reacted in SBF and different ions were released into the solution. The addition of bioactive glass particles to the PCL lowered its elastic modulus and yield strength, but the composites remained intact after the 14 day period in SBF at 37°C. Finally, in an effort to design a better bioactive glass, new borosilicate glass compositions were developed that possess advantages of borate and silicate bioactive glasses at the same time. It was found that replacing small amounts of B2O3 with SiO2 improved glass formation, resistance to nucleation and crystallization, and increased the release rate of boron and silicon in vitro. This new borosilicate glass could be a good alternative to existing silicate and borate bioactive glasses.

Transition and post-transition metal ions in borate glasses: Borate ligand speciation, cluster formation, and their effect on glass transition and mechanical properties.

PubMed

Möncke, D; Kamitsos, E I; Palles, D; Limbach, R; Winterstein-Beckmann, A; Honma, T; Yao, Z; Rouxel, T; Wondraczek, L

2016-09-28

A series of transition and post-transition metal ion (Mn, Cu, Zn, Pb, Bi) binary borate glasses was studied with special consideration of the cations impact on the borate structure, the cations cross-linking capacity, and more generally, structure-property correlations. Infrared (IR) and Raman spectroscopies were used for the structural characterization. These complementary techniques are sensitive to the short-range order as in the differentiation of tetrahedral and trigonal borate units or regarding the number of non-bridging oxygen ions per unit. Moreover, vibrational spectroscopy is also sensitive to the intermediate-range order and to the presence of superstructural units, such as rings and chains, or the combination of rings. In order to clarify band assignments for the various borate entities, examples are given from pure vitreous B 2 O 3 to meta-, pyro-, ortho-, and even overmodified borate glass compositions. For binary metaborate glasses, the impact of the modifier cation on the borate speciation is shown. High field strength cations such as Zn 2+ enhance the disproportionation of metaborate to polyborate and pyroborate units. Pb 2+ and Bi 3+ induce cluster formation, resulting in PbO n - and BiO n -pseudophases. Both lead and bismuth borate glasses show also a tendency to stabilize very large superstructural units in the form of diborate polyanions. Far-IR spectra reflect on the bonding states of modifier cations in glasses. The frequency of the measured cation-site vibration band was used to obtain the average force constant for the metal-oxygen bonding, F M-O . A linear correlation between glass transition temperature (T g ) and F M-O was shown for the metaborate glass series. The mechanical properties of the glasses also correlate with the force constant F M-O , though for cations of similar force constant the fraction of tetrahedral borate units (N 4 ) strongly affects the thermal and mechanical properties. For paramagnetic Cu- and Mn-borate glasses, N 4 was determined from the IR spectra after deducing the relative absorption coefficient of boron tetrahedral versus boron trigonal units, α = α 4 /α 3 , using NMR literature data of the diamagnetic glasses.

Single-pass, efficient type-I phase-matched frequency doubling of high-power ultrashort-pulse Yb-fiber laser using LiB_3O_5

NASA Astrophysics Data System (ADS)

Shukla, Mukesh Kumar; Kumar, Samir; Das, Ritwick

2016-05-01

We report 48 % efficient single-pass second harmonic generation of high-power ultrashort-pulse ({≈ }250 fs) Yb-fiber laser by utilizing type-I phase matching in LiB_3O_5 (LBO) crystal. The choice of LBO among other borate crystals for high-power frequency doubling is essentially motivated by large thermal conductivity, low birefringence and weak group velocity dispersion. By optimally focussing the beam in a 4-mm-long LBO crystal, we have generated about 2.3 W of average power at 532 nm using 4.8 W of available pump power at 1064 nm. The ultrashort green pulses were found out to be near-transform limited sech^2 pulses with a pulse width of Δ τ ≈ 150 fs and being delivered at 78 MHz repetition rate. Due to appreciably low spatial walk-off angle for LBO ({≈ }0.4°), we obtain M^2<1.26 for the SH beam which signifies marginal distortion in comparison with the pump beam (M^2<1.15). We also discuss the impact of third-order optical nonlinearity of the LBO crystal on the generated ultrashort SH pulses.

Atomistic determination of flexoelectric properties of crystalline dielectrics

NASA Astrophysics Data System (ADS)

Maranganti, R.; Sharma, P.

2009-08-01

Upon application of a uniform strain, internal sublattice shifts within the unit cell of a noncentrosymmetric dielectric crystal result in the appearance of a net dipole moment: a phenomenon well known as piezoelectricity. A macroscopic strain gradient on the other hand can induce polarization in dielectrics of any crystal structure, even those which possess a centrosymmetric lattice. This phenomenon, called flexoelectricity, has both bulk and surface contributions: the strength of the bulk contribution can be characterized by means of a material property tensor called the bulk flexoelectric tensor. Several recent studies suggest that strain-gradient induced polarization may be responsible for a variety of interesting and anomalous electromechanical phenomena in materials including electromechanical coupling effects in nonuniformly strained nanostructures, “dead layer” effects in nanocapacitor systems, and “giant” piezoelectricity in perovskite nanostructures among others. In this work, adopting a lattice dynamics based microscopic approach we provide estimates of the flexoelectric tensor for certain cubic crystalline ionic salts, perovskite dielectrics, III-V and II-VI semiconductors. We compare our estimates with experimental/theoretical values wherever available and also revisit the validity of an existing empirical scaling relationship for the magnitude of flexoelectric coefficients in terms of material parameters. It is interesting to note that two independent groups report values of flexoelectric properties for perovskite dielectrics that are orders of magnitude apart: Cross and co-workers from Penn State have carried out experimental studies on a variety of materials including barium titanate while Catalan and co-workers from Cambridge used theoretical ab initio techniques as well as experimental techniques to study paraelectric strontium titanate as well as ferroelectric barium titanate and lead titanate. We find that, in the case of perovskite dielectrics, our estimates agree to an order of magnitude with the experimental and theoretical estimates for strontium titanate. For barium titanate however, while our estimates agree to an order of magnitude with existing ab initio calculations, there exists a large discrepancy with experimental estimates. The possible reasons for the observed deviations are discussed.

Phase equilibria in the lysozyme-ammonium sulfate-water system.

PubMed

Moretti, J J; Sandler, S I; Lenhoff, A M

2000-12-05

Ternary phase diagrams were measured for lysozyme in ammonium sulfate solutions at pH values of 4 and 8. Lysozyme, ammonium sulfate, and water mass fractions were assayed independently by UV spectroscopy, barium chloride titration, and lyophilization respectively, with mass balances satisfied to within 1%. Protein crystals, flocs, and gels were obtained in different regions of the phase diagrams, and in some cases growth of crystals from the gel phase or from the supernatant after floc removal was observed. These observations, as well as a discontinuity in protein solubility between amorphous floc precipitate and crystal phases, indicate that the crystal phase is the true equilibrium state. The ammonium sulfate was generally found to partition unequally between the supernatant and the dense phase, in disagreement with an assumption often made in protein phase equilibrium studies. The results demonstrate the potential richness of protein phase diagrams as well as the uncertainties resulting from slow equilibration. Copyright 2000 John Wiley & Sons, Inc.

Structural influence of mixed transition metal ions on lithium bismuth borate glasses

NASA Astrophysics Data System (ADS)

Yadav, Arti; Dahiya, Manjeet S.; Hooda, A.; Chand, Prem; Khasa, S.

2017-08-01

Lithium bismuth borate glasses containing mixed transition metals having composition 7CoO·23Li2O·20Bi2O3·50B2O3 (CLBB), 7V2O5·23Li2O·20Bi2O3·50B2O3 (VLBB) and x(2CoO·V2O5)·(30 - x)Li2O·20Bi2O3·50B2O3 (x = 0.0 (LBB) and x = 2.0, 5.0, 7.0, 10.0 mol% (CVLBB1-4)) are synthesized via melt quench route. The synthesized compositions are investigated for their physical properties using density (D) and molar volume (Vm), thermal properties by analyzing DSC/TG thermo-graphs, structural properties using IR absorption spectra in the mid-IR range and optical properties using UV-Vis-NIR spectroscopy. The Electron Paramagnetic Resonance (EPR) spectra of vanadyl and cobalt ion have been analyzed to study compositional effects on spin-Hamiltonian parameters. The non linear variations in physical properties depict a strong structural influence of Co/V- oxides on the glassy matrix. The compositional variations in characteristic temperatures (glass transition temperature Tg, glass crystallization temperature Tp and glass melting temperature Tm) reveals that Tg for glass samples CLBB is relatively less than that of pure lithium bismuth borate (LBB) glass sample wherein Tg for sample VLBB is higher than that of LBB. The increase in Tg (as compared with LBB) with an enhanced substitution of mixed transition metal oxides (2CoO·V2O5) shows a progressive structure modification of bismuth borate matrix. These predictions are very well corroborated by corresponding compositional trends of Tp and Tm. FTIR studies reveal that Co2+& VO2+ ions lead to structural rearrangements through the conversion of three-coordinated boron into four coordinated boron and thereby reducing number of non-bridging oxygen atoms. Bismuth is found to exist in [BiO6] octahedral units only, whereas boroxol rings are not present in the glass network. The theoretical values of optical basicity (Λth) and corresponding oxide ion polarizability (αo2-) have also been calculated to investigate oxygen covalency of glass matrix. Trends in both these parameters suggested an increase in ionic bonding on substitution of divalent transition metal cations causing a more bonding compaction in glass structure. The UV-Vis-NIR spectra suggest that cobalt ions exist as Co2+ states in octahedral coordination in glass network. Inter-electronic repulsion parameter and crystal field splitting energy were evaluated to understand the site symmetry around Co2+-ion in glass. X-band EPR spectra suggest that vanadium ions (V4+) exists as VO2+-ions in octahedral coordination with tetragonal compression. Spin Hamiltonian parameters g-values and A-values of VO2+ ions in glass were calculated. For sample CLBB two resonance lines in EPR spectrum attribute to octahedral symmetry around Co2+-ions were observed.

A buetschliite-type rare-earth borate, KBaY(BO 3) 2

NASA Astrophysics Data System (ADS)

Gao, Jianhua; Song, Limei; Hu, Xiaoyun; Zhang, Dekai

2011-01-01

The title compound was firstly synthesized by solid state reaction and its single crystals were successfully obtained using a selected flux. It is isotypic with the mineral buetschliite, K 2Ca(CO 3) 2, and crystallizes in the trigonal space group R-3m with a = 5.4526(12) Å, c = 17.781(8) Å, Z = 3. In the structure, Ba and K atoms are disordered on a same site in the proportion of 0.492(4):0.508(4). The fundamental building units are YO 6 octahedra and BO 3 triangles. The structure consists of [YB 2O 6] ∞ double layers constructed by corner-sharing YO 6 and BO 3 groups. Ba/K atoms occupy the spaces between these two layers and play the role of bridges. In addition, the luminescence properties of Eu 3+ doped KBaY(BO 3) 2 were also studied.

Bioactive borate glass coatings for titanium alloys.

PubMed

Peddi, Laxmikanth; Brow, Richard K; Brown, Roger F

2008-09-01

Bioactive borate glass coatings have been developed for titanium and titanium alloys. Glasses from the Na(2)O-CaO-B(2)O(3) system, modified by additions of SiO(2), Al(2)O(3), and P(2)O(5), were characterized and compositions with thermal expansion matches to titanium were identified. Infrared and X-ray diffraction analyses indicate that a hydroxyapatite surface layer forms on the borate glasses after exposure to a simulated body fluid for 2 weeks at 37 degrees C; similar layers form on 45S5 Bioglass((R)) exposed to the same conditions. Assays with MC3T3-E1 pre-osteoblastic cells show the borate glasses exhibit in vitro biocompatibility similar to that of the 45S5 Bioglass((R)). An enameling technique was developed to form adherent borate glass coatings on Ti6Al4V alloy, with adhesive strengths of 36 +/- 2 MPa on polished substrates. The results show these new borate glasses to be promising candidates for forming bioactive coatings on titanium substrates.

Barium iodide and strontium iodide crystals and scintillators implementing the same

DOEpatents

Payne, Stephen A.; Cherepy, Nerine J.; Hull, Giulia E.; Drobshoff, Alexander D.; Burger, Arnold

2016-11-29

In one embodiment, a material comprises a crystal comprising strontium iodide providing at least 50,000 photons per MeV, where the strontium iodide material is characterized by a volume not less than 1 cm.sup.3. In another embodiment, a scintillator optic includes europium-doped strontium iodide providing at least 50,000 photons per MeV, where the europium in the crystal is primarily Eu.sup.2+, and the europium is present in an amount greater than about 1.6%. A scintillator radiation detector in yet another embodiment includes a scintillator optic comprising SrI.sub.2 and BaI.sub.2, where a ratio of SrI.sub.2 to BaI.sub.2 is in a range of between 0:1 and 1.0, the scintillator optic is a crystal that provides at least 50,000 scintillation photons per MeV and energy resolution of less than about 5% at 662 keV, and the crystal has a volume of 1 cm.sup.3 or more; the scintillator optic contains more than about 2% europium.

Crystallization Kinetics of a Solid Oxide Fuel Cell Seal Glass by Differential Thermal Analysis

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Gamble, Eleanor A.

2005-01-01

Crystallization kinetics of a barium calcium aluminosilicate glass (BCAS), a sealant material for planar solid oxide fuel cells, have been investigated by differential thermal analysis (DTA). From variation of DTA peak maximum temperature with heating rate, the activation energy for glass crystallization was calculated to be 259 kJ/mol. Development of crystalline phases on thermal treatments of the glass at various temperatures has been followed by powder x-ray diffraction. Microstructure and chemical composition of the crystalline phases were investigated by scanning electron microscopy and energy dispersive spectroscopic (EDS) analysis. BaSiO3 and hexacelsian (BaAl2Si2O8) were the primary crystalline phases whereas monoclinic celsian (BaAl2Si2O8) and (Ba(x), Ca(y))SiO4 were also detected as minor phases. Needle-shaped BaSiO3 crystals are formed first, followed by the formation of other phases at longer times of heat treatments. The glass does not fully crystallize even after long term heat treatments at 750 to 900 C.

Borate mineral assemblages in the system Na2OCaOMgOB2O3H2O

USGS Publications Warehouse

Christ, C.L.; Truesdell, A.H.; Erd, Richard C.

1967-01-01

he significant known hydrated borate mineral assemblages (principally of the western United States) in the system Na2OCaOz.sbnd;MgOB2O3H2O are expressible in three ternary composition diagrams. Phase rule interpretation of the diagrams is consistent with observation, if the activity of H2O is generally considered to be determined by the geologic environment. The absence of conflicting tie-lines on a diagram indicates that the several mineral assemblages of the diagram were formed under relatively narrow ranges of temperature and pressure. The known structural as well as empirical formulas for the minerals are listed, and the more recent (since 1960) crystal structure findings are discussed briefly. Schematic Gibbs free energy-composition diagrams based on known solubility-temperature relations in the systems Na2B4O7-H2O and Na2B4O7-NaCl-H2O, are highly useful in the interpretation and prediction of the stability relations in these systems; in particular these diagrams indicate clearly that tincalconite, although geologically important, is everywhere a metastable phase. Crystal-chemical considerations indicate that the same thermodynamic and kinetic behavior observed in the Na2B4O7-H2O system will hold in the Ca2B6O11-H2O system. This conclusion is confirmed by the petrologic evidence. The chemical relations among the mineral assemblages of a ternary diagram are expressed by a schematic "activity-activity" diagram. These activity-activity diagrams permit the tracing-out of the paragenetic sequences as a function of changing cation and H2O activities. ?? 1967.

Microanalytical identification of barium sulphate crystals in statoliths of Chara Rhizoids

NASA Technical Reports Server (NTRS)

Schroeter, K.; Lauchli, A.; Sievers, A. J.

1979-01-01

In contrast to higher plants, Chara rhizoids contain statolith vacuoles filled with biocrystallites of BaS04 in the form of rods composed of globular subunits ca. 7 nm in diameter. The revelation of the crystallites under electron microscopy is dependent on the fixative; best structural preservation was observed after fixation in a buffered glutaraldehyde + acrolein solution; 0s04 and KMnO4 partially dissolved both the biocrystallites and synthetic BaS04.

Crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics for immobilization of simulated sulfate bearing high-level liquid waste

NASA Astrophysics Data System (ADS)

Wu, Lang; Xiao, Jizong; Wang, Xin; Teng, Yuancheng; Li, Yuxiang; Liao, Qilong

2018-01-01

The crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics with different content (0-30 wt %) of simulated sulfate bearing high-level liquid waste (HLLW) were evaluated. The sulfate phase segregation in vitrification process was also investigated. The results show that the glass-ceramics with 0-20 wt% of HLLW possess mainly zirconolite phase along with a small amount baddeleyite phase. The amount of perovskite crystals increases while the amount of zirconolite crystals decreases when the HLLW content increases from 20 to 30 wt%. For the samples with 20-30 wt% HLLW, yellow phase was observed during the vitrification process and it disappeared after melting at 1150 °C for 2 h. The viscosity of the sample with 16 wt% HLLW (HLLW-16) is about 27 dPa·s at 1150 °C. The addition of a certain amount (≤20 wt %) of HLLW has no significant change on the aqueous stability of glass-ceramic waste forms. After 28 days, the 90 °C PCT-type normalized leaching rates of Na, B, Si, and La of the sample HLLW-16 are 7.23 × 10-3, 1.57 × 10-3, 8.06 × 10-4, and 1.23 × 10-4 g·m-2·d-1, respectively.

Phenomenological model of spin crossover in molecular crystals as derived from atom-atom potentials.

PubMed

Sinitskiy, Anton V; Tchougréeff, Andrei L; Dronskowski, Richard

2011-08-07

The method of atom-atom potentials, previously applied to the analysis of pure molecular crystals formed by either low-spin (LS) or high-spin (HS) forms (spin isomers) of Fe(II) coordination compounds (Sinitskiy et al., Phys. Chem. Chem. Phys., 2009, 11, 10983), is used to estimate the lattice enthalpies of mixed crystals containing different fractions of the spin isomers. The crystals under study were formed by LS and HS isomers of Fe(phen)(2)(NCS)(2) (phen = 1,10-phenanthroline), Fe(btz)(2)(NCS)(2) (btz = 5,5',6,6'-tetrahydro-4H,4'H-2,2'-bi-1,3-thiazine), and Fe(bpz)(2)(bipy) (bpz = dihydrobis(1-pyrazolil)borate, and bipy = 2,2'-bipyridine). For the first time the phenomenological parameters Γ pertinent to the Slichter-Drickamer model (SDM) of several materials were independently derived from the microscopic model of the crystals with use of atom-atom potentials of intermolecular interaction. The accuracy of the SDM was checked against the numerical data on the enthalpies of mixed crystals. Fair semiquantitative agreement with the experimental dependence of the HS fraction on temperature was achieved with use of these values. Prediction of trends in Γ values as a function of chemical composition and geometry of the crystals is possible with the proposed approach, which opens a way to rational design of spin crossover materials with desired properties. This journal is © the Owner Societies 2011

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Boric acid and its salts, borax... salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride... its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric...

76 FR 74831 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-01

... exposed to treated borated water. In response to a request from the Nuclear Energy Institute (NEI), the... NUCLEAR REGULATORY COMMISSION [NRC-2011-0256] Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY: Nuclear Regulatory Commission. ACTION: Draft interim staff...

Structure and luminescence spectra of lutetium and yttrium borates synthesized from ammonium nitrate melt

NASA Astrophysics Data System (ADS)

Klassen, Nikolay V.; Shmurak, Semion Z.; Shmyt'ko, Ivan M.; Strukova, Galina K.; Derenzo, Stephen E.; Weber, Marvin J.

2005-01-01

Lutetium and yttrium borates doped with europium, terbium, gadolinium, etc. have been synthesized by dissolving initial oxides and nitrates in ammonium nitrate melt and thermal decomposition of the solvent. Annealings in the range of 500-1100°C modified the dimensions of the grains from 2 to 3 nm to more than 100 nm. Significant dependence of the structure of lutetium borate on slight doping with rare earth ions has been found: terbium makes high-temperature vaterite phase preferential at room temperature, whereas europium stabilizes low-temperature calcite phase. Influence of the structure of the borates on the pattern of the luminescence spectra of europium dopant was observed. Possibilities for manufacturing of scintillating lutetium borate ceramics by means of this method of synthesis are discussed.

Angiogenic effects of borate glass microfibers in a rodent model.

PubMed

Lin, Yinan; Brown, Roger F; Jung, Steven B; Day, Delbert E

2014-12-01

The primary objective of this research was to evaluate the use of bioactive borate-based glass microfibers for angiogenesis in soft tissue repair applications. The effect of these fibers on growth of capillaries and small blood vessels was compared to that of 45S5 silica glass microfibers and sham implant controls. Compressed mats of three types of glass microfibers were implanted subcutaneously in rats and tissues surrounding the implant sites histologically evaluated 2-4 weeks post surgery. Bioactive borate glass 13-93B3 supplemented with 0.4 wt % copper promoted extensive angiogenesis as compared to silica glass microfibers and sham control tissues. The angiogenic responses suggest the copper-containing 13-93B3 microfibers may be effective for treating chronic soft tissue wounds. A second objective was to assess the possible systemic cytotoxicity of dissolved borate ions and other materials released from implanted borate glass microfibers. Cytotoxicity was assessed via histological evaluation of kidney tissue collected from animals 4 weeks after subcutaneously implanting high amounts of the borate glass microfibers. The evaluation of the kidney tissue from these animals showed no evidence of chronic histopathological changes in the kidney. The overall results indicate the borate glass microfibers are safe and effective for soft tissue applications. © 2014 Wiley Periodicals, Inc.

Structural and luminescence behavior of Er(3+) ions doped Barium tellurofluoroborate glasses.

PubMed

Annapoorani, K; Maheshvaran, K; Arunkumar, S; Suriya Murthy, N; Marimuthu, K

2015-01-25

Er(3+) doped Barium tellurofluoroborate glasses (BTFBxE) with the chemical composition (30-x)TeO2+30B2O3+20BaO+20BaF+xEr2O3 (where x=0.01, 0.05, 0.1, 0.5, 1.0 and 2.0 in wt%) were prepared following the melt quenching technique. The different vibrational modes of borates and tellurites in the prepared glasses were explored through FTIR and Raman spectra. The optical absorption spectra have been used to determine the ionic/covalent nature of the metal-ligand bond in the prepared glasses with the help of Nephelauxetic ratio (β) and bonding parameter (δ) studies. The optical band gap of direct and indirect allowed transitions were determined from Tauc's plot and the variations of band gap energy with structural arrangements were discussed. The Urbach energy values were determined and the relatively lower values of the Urbach's energy reveal the minimal degree of disorderness in the prepared glasses. The oscillator strengths (fexp and fcal) and Judd-Ofelt (JO) intensity parameters (Ω2, Ω4 and Ω6) were calculated with the application of JO theory and the trends of the JO intensity parameters are found to be Ω2>Ω6>Ω4 for all the prepared glasses with a minimum variation in Ω2 intensity parameter values. A bright green emission was observed from the (2)H11/2+(4)S3/2→ (4)I15/2 transition and the radiative properties such as transition probability (A), stimulated emission cross-section (σP(E)), branching ratio (βr) and radiative lifetime (τ) were calculated using the JO parameters. The suitability of the prepared glasses for the fabrication of photonic devices were also discussed and reported in the present work. Copyright © 2014 Elsevier B.V. All rights reserved.

Propagation characteristics of a focused laser beam in a strontium barium niobate photorefractive crystal under reverse external electric field.

PubMed

Guo, Q L; Liang, B L; Wang, Y; Deng, G Y; Jiang, Y H; Zhang, S H; Fu, G S; Simmonds, P J

2014-10-01

The propagation characteristics of a focused laser beam in a SBN:75 photorefractive crystal strongly depend on the signal-to-background intensity ratio (R=I_s/I_b) under reverse external electric field. In the range 20>R>0.05, the laser beam shows enhanced self-defocusing behavior with increasing external electric field, while it shows self-focusing in the range 0.03>R>0.01. Spatial solitons are observed under a suitable reverse external electric field for R=0.025. A theoretical model is proposed to explain the experimental observations, which suggest a new type of soliton formation due to "enhancement" not "screening" of the external electrical field.

Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.

PubMed

Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

2013-01-01

Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping.

Brillouin function characteristics for La-Co substituted barium hexaferrites

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

Wu, Chuanjian, E-mail: wcjuestc2005@gmail.com, E-mail: ksun@uestc.edu.cn; Yu, Zhong; Sun, Ke, E-mail: wcjuestc2005@gmail.com, E-mail: ksun@uestc.edu.cn

2015-09-14

La-Co substituted barium hexaferrites with the chemical formula of Ba{sub 1−x}La{sub x}Fe{sub 12−x}Co{sub x}O{sub 19} (x = 0.0, 0.1, 0.3, and 0.5), prepared by a conventional ceramic method, were systematically investigated by Raman spectra, X-ray photoelectron spectroscopy, Rietveld refinement of X-ray diffraction patterns, and vibrating sample magnetometer. The result manifests that all the compounds are crystallized in magnetoplumbite hexagonal structure. Trivalent cobalt ions prevailingly occupy the 2a, 4f{sub 1}, and 12k sites. According to Néel model of collinear-spin ferrimagnetism, the molecular-field coefficients ω{sub bf2}, ω{sub kf1}, ω{sub af1}, ω{sub kf2}, and ω{sub bk} of La-Co substituted barium hexaferrites have been calculated usingmore » the nonlinear fitting method, and the magnetic moment of five sublattices (2a, 2b, 4f{sub 1}, 4f{sub 2}, and 12k) versus temperature T has been also investigated. The fitting results are coincided well with the experimental data. Moreover, with the increase of La-Co substitution amount x, the molecular-field coefficients ω{sub bf2} and ω{sub af1} decrease constantly, while the molecular-field coefficients ω{sub kf1}, ω{sub kf2}, and ω{sub bk} show a slight change.« less

Synthesis of 0.1% & 0.2% neodymium doped barium zirconium titanate (BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}) and study of their dielectric behaviour

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

Kumar, Anil, E-mail: anilkantikumar@rediffmail.com; Kumar, Vipin; Gupta, Merry

2015-08-28

Efforts have been made to ease process of producing widely used multilayered ceramics of Barium Zirconium Titanium Oxides and study their dielectric behaviour and structural properties. For this purpose, adequate proportions of Barium Carbonate, Zirconium Oxide and Titanium Oxide were taken and hand milled for 2 hours. Neodymium composition of the order of 0.1% and 0.2% was used for doping to weight percentage of BaZr0.2Ti0.8O3. The samples were authenticated using raw data obtained from Bruker AXS D8 advance Copper KL alpha source XRD equipment. Further, the samples were studied for their phase transition, composition, single phase perovskite structure using XRDmore » technique. The technique has also been applied to know formation of stable homogeneous solid solution from XRD parameters. The other physical parameters like the morphology, micro structural information, crystal arrangements and topography have also been observed through SEM. The SEM has revealed information related to grain size development and composition of sample with fine agglomerates. For complete study of the compounds the atomic and weight composition has also been examined by Electron Dispersive Spectroscopy patterns. The comparison has been made with other works on ceramics at various frequencies and has yielded very interesting results.« less

Mössbauer study of conductive oxide glass

NASA Astrophysics Data System (ADS)

Matsuda, Koken; Kubuki, Shiro; Nishida, Tetsuaki

2014-10-01

Heat treatment of barium iron vanadate glass, BaO - Fe2O3- V2O5, at temperatures higher than crystallization temperature causes a marked decrease in resistivity (ρ) from several MΩcm to several Ωcm. 57Fe Mössbauer spectrum of heat-treated vanadate glass shows a marked decrease in quadrupole splitting (Δ) of FeIII, reflecting a structural relaxation, i.e., an increased symmetry of "distorted" FeO4 and VO4 tetrahedra which are connected to each other by sharing corner oxygen atoms. Structural relaxation of 3D-network of vanadate glass accompanies a decrease in the activation energy for the conduction, reflecting a decreased energy gap between the donor level and conduction band. A marked increase in the conductivity was observed in CuO- or Cu2O -containing barium iron vanadate glass after heat treatment at 450 °C for 30 min or more. "n-type semiconductor model combined with small polaron hopping theory" was proposed in order to explain the high conductivity.

Surface reaction characteristics at low temperature synthesis BaTiO 3 particles by barium hydroxide aqueous solution and titanium tetraisopropoxide

NASA Astrophysics Data System (ADS)

Zeng, Min

2011-05-01

Well-crystallized cubic phase BaTiO 3 particles were prepared by heating the mixture of barium hydroxide aqueous solution and titania derived from the hydrolysis of titanium isopropoxide (TTIP) at 328 K, 348 K or 368 K for 24 h. The morphology and size of obtained particles depended on the reaction temperature and the Ba(OH) 2/TTIP molar ratio. By the direct hydrolytic reaction of titanium tetraisopropoxide, the high surface area titania (TiO 2) was obtained. The surface adsorption characteristics of the titania particles had been studied with different electric charges OH - ions or H + ions. The formation mechanism and kinetics of BaTiO 3 were examined by measuring the concentration of [Ba 2+] ions in the solution during the heating process. The experimental results showed that the heterogeneous nucleation of BaTiO 3 occurred on the titania surface, according to the Avrami's equation.

Method for producing a borohydride

DOEpatents

Kong, Peter C [Idaho Falls, ID

2008-09-02

A method for producing a borohydride is described and which includes the steps of providing a source of borate; providing a material which chemically reduces the source of the borate to produce a borohydride; and reacting the source of borate and the material by supplying heat at a temperature which substantially effects the production of the borohydride.

Method for producing a borohydride

DOEpatents

Kong, Peter C.

2010-06-22

A method for producing a borohydride is described that includes the steps of providing a source of borate; providing a material that chemically reduces the source of the borate to produce a borohydride; and reacting the source of the borate and the material by supplying heat at a temperature that substantially effects the production of the borohydride.

First Observations of Boron on Mars and Implications for Gale Crater Geochemistry

NASA Astrophysics Data System (ADS)

Gasda, P. J.; Haldeman, E. B.; Wiens, R. C.; Rapin, W.; Frydenvang, J.; Maurice, S.; Clegg, S. M.; Delapp, D.; Sanford, V.; McInroy, R.

2016-12-01

Borates are potentially important precursor materials for the origin of life on Earth. It has been shown that borates are required to stabilize ribose, a component of RNA, when produced by the formose reaction, a prebiotically plausible mechanism to produce ribose from formaldehyde. Evaporites, including borates, also shed light on the history of aqueous activity on Mars. The ChemCam instrument onboard the NASA Curiosity rover provides quantitative elemental compositions of targets in Gale Crater, Mars, using laser-induced breakdown spectroscopy (LIBS). Laboratory observations of Fe-free targets indicate that a LIBS emission line is visible with as little as 10 ppm B. We have observed B lines in 23 calcium sulfate veins in Gale Crater: 3 in Yellowknife Bay and 20 in the Murray lacustrine mudstone and the Stimson eolian sandstone units since sol 727, as Curiosity arrived at the base of Mt. Sharp, a 5 km sedimentary mound in the center of Gale Crater. To calibrate these observations, samples composed of borates diluted with Hawaiian basalt have been analyzed using the LANL ChemCam engineering model. Preliminary results show that the Gale Crater veins have between 10-100 ppm B. One possible explanation for borates in veins is that Gale Lake evaporated, depositing evaporites, including borates. Later, Gale Crater was partially buried and its lacustrine and overlying eolian units were lithified and fractured. Water flowed through the evaporite-rich layers, partially dissolving them. Fluid moved through the fractures, re-precipitating the borates and sulfates as veins. ChemCam cannot directly determine mineralogy, but B is likely present as borax as the dominate borate phase in these veins, based on previous estimates of vein fluid temperature. Borates forming in this environment tend to precipitate from mildly alkaline fluids. The fluid temperature and pH implies these veins were potentially habitable environments.

Barium Transport Process in Impregnated Dispenser Cathodes.

DTIC Science & Technology

1982-01-25

experiments were carried out on pure tungsten. The tung- sten was either in the form of thin foils (6 mm on a side) or single crystal disks (6 mm in...temperature reveal the presence of car- bon, silicon , calcium, and nitrogen impurities, with only trace amounts (ɚ%) of calcium and nitrogen. Carbon is not...expected to be present at diffusion temperatures but forms as an overlayer only upon cooling [6]. We hope to re- duce silicon impurity levels by use of

Casting of Halide and Fluoride Alloys for Laser Windows

DTIC Science & Technology

1974-07-15

mechanism leads to an inverse square root dependence of fracture strength on grain size. Since CaF2, SrFp and BaFp all exhibit at least microplastic ...flaws or microplasticity is the strength limiting factor is not known. 4.2.2 Solid-solution strengthening 4.2.2. 1 General If fracture in these...Temperature Microplasticity in SrF2 Single Crystals, " J. Appl. Phys. 41_(4) 1871 (1970). 12. T.S. Liu and C.H. Li, " Plasticity of Barium Fluoride

40 CFR 721.1880 - Borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)-.

Code of Federal Regulations, 2010 CFR

2010-07-01

...)hydro-, sodium, (T-4)-. 721.1880 Section 721.1880 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.1880 Borate(1-), tris(acetato-.kappa.O)hydro-, sodium... substance identified as borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)- (PMN P-00-0922; CAS No...

40 CFR 721.1880 - Borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)-.

Code of Federal Regulations, 2011 CFR

2011-07-01

...)hydro-, sodium, (T-4)-. 721.1880 Section 721.1880 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.1880 Borate(1-), tris(acetato-.kappa.O)hydro-, sodium... substance identified as borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)- (PMN P-00-0922; CAS No...

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate, boric oxide (boric anhydride), sodium borate and sodium metaborate; exemptions from the requirement of a tolerance. 180.1121 Section 180.1121 Protection of Environment ENVIRONMENTAL PROTECTION...

(But­oxy­methyl­idene)di­methyl­aza­nium tetra­phenyl­borate aceto­nitrile monosolvate

PubMed Central

Tiritiris, Ioannis; Saur, Stefan; Kantlehner, Willi

2014-01-01

In the title solvated salt, C7H16NO+·C24H20B−·C2H3N, the C—N bond lengths in the cation are 1.2831 (19), 1.467 (2) and 1.465 (2) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.2950 (18) Å shows a double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. The two C atoms of the n-butyl group are disordered over the two sites, with refined occupancy ratios of 0.890 (5):0.110 (5) and 0.888 (4):0.112 (4). In the crystal, C—H⋯π inter­actions occur between the methine H atom, H atoms of the –N(CH3)2 and –CH2 groups of the cation, and two of the phenyl rings of the tetra­phenyl­borate anion. The latter inter­action forms an aromatic pocket in which the cation is embedded. Thus, a two-dimensional pattern is created in the ac plane. PMID:24826158

Effects of copper on the preparation and characterization of Na-Ca-P borate glasses.

PubMed

Shailajha, S; Geetha, K; Vasantharani, P; Sheik Abdul Kadhar, S P

2015-03-05

Glasses in the system Na2O-CaO-B2O3-P2O5: CuO have been prepared by melt quenching at 1200°C and rapidly cooling at room temperature. The structural, optical and thermal properties have been investigated using X-ray diffraction (XRD), ultraviolet-visible (UV-VIS) spectroscopy, thermogravimetric-differential thermal analysis (TG-DTA), Fourier transform infrared (FTIR) spectroscopy, high resolution scanning electron microscopy (HRSEM) with energy dispersive X-ray (EDX) spectroscopy and high resolution transmission electron microscope (HRTEM) with energy dispersive X-ray (EDAX). The amorphous and crystalline nature of these samples was verified by XRD. Glass transition, crystallization and thermal stability were determined by TG-DTA investigations. Direct optical energy band gaps before and after doping with different percents of copper oxide were evaluated from 4.81eV to 2.99eV indicated the role of copper in the glassy matrix by UV spectra. FTIR spectrum reveals characteristic absorption bands due to various groups of triangular and tetrahedral borate network. Due to the amorphous nature, the particles like agglomerates on the glass surface were investigated by the HRSEM analysis. The crystalline nature of the samples in XRD is confirmed by SAED pattern using HRTEM. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, crystal structure refinement, and nonlinear-optical properties of CaB{sub 3}O{sub 5}(OH): Comparative crystal chemistry of calcium triborates

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

Yamnova, N. A., E-mail: aks.crys@gmail.com; Aksenov, S. M.; Stefanovich, S. Yu.

Calcium triborate CaB{sub 3}O5(OH) obtained by hydrothermal synthesis in the Ca(OH){sub 2}–H{sub 3}BO{sub 3}–Na{sub 2}CO{sub 3}–KCl system is studied by single-crystal X-ray diffraction. The parameters of the orthorhombic unit cell are as follows: a = 13.490(1), b = 6.9576(3), and c = 4.3930(2) Å; V = 412.32(3) Å{sup 3} and space group Pna2{sub 1}. The structure is refined in the anisotropic approximation of the atomic displacement parameters to R = 4.28% using 972 vertical bar F vertical bar > 4σ(F). It is confirmed that the crystal structure of Ca triborate CaB{sub 3}O{sub 5}(OH) is identical to that described earlier. Themore » hydrogen atom is localized. An SHG signal stronger than that of the quartz standard is registered. The phase transition of calcium triborate into calciborite is found on heating. The comparative crystal-chemical analysis of a series of borates with the general chemical formula 2CaO · 3B{sub 2}O{sub 3} · nH{sub 2}O (n = 0–13) with the constant CaO: B{sub 2}O{sub 3}= 2: 3 ratio and variable content of water is performed.« less

Preservation of tissue specimens during transport to mycobacteriology laboratories.

PubMed Central

Richards, W D; Wright, H S

1983-01-01

Chloramine-T and sodium borate solutions were evaluated for their effectiveness in preserving Mycobacterium bovis and controlling the growth of non-mycobacterial contaminants on tissue specimens during transport to laboratories. The number of culturable M. bovis cells in suspension was reduced by 5.1 log10 upon exposure to chloramine-T solution and by less than 1 log10 upon exposure to sodium borate solution for 7 days. Reinoculation of laboratory media (because of overgrowth by non-mycobacterial contaminants) was required for 52.6% of 190 routine bovine tissue specimens shipped refrigerated in chloramine-T solution and for 6.1% of 520 specimens shipped unrefrigerated in sodium borate solution. M. bovis was isolated from bovine tissue stored in sodium borate solution at 23 degrees C for 17 weeks and at 4 degrees C for 25 weeks. Unrefrigerated sodium borate solution has been used successfully to ship tissue specimens to our laboratory for the past 11 years. PMID:6341397

Crystal structures and magnetic properties of lanthanide containing borates LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr)

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

Doi, Yoshihiro, E-mail: doi@sci.hokudai.ac.jp; Satou, Tatsuya; Hinatsu, Yukio

2013-10-15

The synthesis, crystal structures and magnetic properties of LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr) were investigated. The LnCr(BO{sub 3}){sub 2} compounds crystallize in the dolomite-type structure with space group R3{sup ¯}, in which the Ln and Cr ions occupy two octahedral sites. From the result of structural analysis, it was found that there is an anti-site disorder between these two sites and its chemical formula is more exactly Ln{sub 1−r}Cr{sub r}[Cr{sub 1−r}Ln{sub r}](BO{sub 3}){sub 2}. On the other hand, the LnSc(BO{sub 3}){sub 2} adopt the calcite-type structure with space group R3{sup ¯}c. The Ln and Sc ions randomly occupymore » an octahedral site and the chemical formula is represented as (Ln{sub 0.5}Sc{sub 0.5})BO{sub 3}. From the magnetic susceptibility and specific heat measurements, we found that all the LnCr(BO{sub 3}){sub 2} show an antiferromagnetic transition at 6.1–8.1 K. This transition is mainly due to the ordering of Cr{sup 3+} magnetic moments. Among the compounds with magnetic Ln{sup 3+} ions, only YbCr(BO{sub 3}){sub 2} shows an antiferromagnetic ordering of Ln{sup 3+} ion at 2.1 K. - Graphical abstract: The lanthanide containing borates LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr) have the dolomite-type (Ln=Cr) and calcite-type (Ln=Sc) structures. Both structures are similar to each other except for the difference in the partially or fully disordered arrangements of octahedral sites. At low temperatures, the LnCr(BO{sub 3}){sub 2} compounds show an antiferromagnetic transition due to a long-range ordering of Cr{sup 3+} moments. Among them only YbCr(BO{sub 3}){sub 2} shows an antiferromagnetic ordering of Ln{sup 3+} ion at 2.1 K. Display Omitted - Highlights: • Lanthanide containing borates LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr) have been synthesized. • LnCr(BO{sub 3}){sub 2} has the dolomite-type structure with an anti-site disorder between Ln and Cr sites. • LnSc(BO{sub 3}){sub 2} has the calcite-type structure in which the Ln and Cr randomly occupy the same site. • LnCr(BO{sub 3}){sub 2} shows an antiferromagnetic transition at 6.1–8.1 K due to the long-range magnetic ordering of Cr{sup 3+} moments. • Only YbCr(BO{sub 3}){sub 2} shows the two-step antiferromagnetic ordering: Cr{sup 3+} (6.1 K) and Yb{sup 3+} (2.1 K)« less

Modeling and minimization of barium sulfate scale

Treesearch

Alan W. Rudie; Peter W. Hart

2006-01-01

The majority of the barium present in the pulping process exits the digester as barium carbonate. Barium carbonate dissolves in the bleach plant when the pH drops below 7 and, if barium and sulfate concentrations are too high, begins to precipitate as barium sulfate. Barium is difficult to control because a mill cannot avoid this carbonate-to-sulfate transition using...

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

Zhao, Haishuang; Krysiak, Yaşar; Hoffmann, Kristin

The crystal structure and disorder phenomena of Al{sub 4}B{sub 2}O{sub 9}, an aluminum borate from the mullite-type family, were studied using automated diffraction tomography (ADT), a recently established method for collection and analysis of electron diffraction data. Al{sub 4}B{sub 2}O{sub 9}, prepared by sol-gel approach, crystallizes in the monoclinic space group C2/m. The ab initio structure determination based on three-dimensional electron diffraction data from single ordered crystals reveals that edge-connected AlO{sub 6} octahedra expanding along the b axis constitute the backbone. The ordered structure (A) was confirmed by TEM and HAADF-STEM images. Furthermore, disordered crystals with diffuse scattering along themore » b axis are observed. Analysis of the modulation pattern implies a mean superstructure (AAB) with a threefold b axis, where B corresponds to an A layer shifted by ½a and ½c. Diffraction patterns simulated for the AAB sequence including additional stacking disorder are in good agreement with experimental electron diffraction patterns. - Graphical abstract: Crystal structure and disorder phenomena of B-rich Al{sub 4}B{sub 2}O{sub 9} studied by automated electron diffraction tomography (ADT) and described by diffraction simulation using DISCUS. - Highlights: • Ab-initio structure solution by electron diffraction from single nanocrystals. • Detected modulation corresponding mainly to three-fold superstructure. • Diffuse diffraction streaks caused by stacking faults in disordered crystals. • Observed streaks explained by simulated electron diffraction patterns.« less

Laboratory evaluation of borate:amine:copper derivatives In wood for fungal decay protection

Treesearch

George Chen

2011-01-01

This study aimed to evaluate borate:amine:copper derivatives in wood for fungal decay protection as well as the permanence of copper and boron in wood. Each of four derivatives of borate:amine:copper prevented fungal decay in wood. Disodium tetraborate decahydrate (borax):amine:copper derivatives with 0.61-0.63% retention after water leaching prevented decay by...

Corrosion studies of titanium in borated water for TPX

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

Wilson, D.F.; Pawel, S.J.; DeVan, J.H.

1995-12-31

Corrosion testing was performed to demonstrate the compatibility of the titanium vacuum vessel with borated water. Borated water is proposed to fill the annulus of the double wall vacuum vessel to provide effective radiation shielding. Borating the water with 110 grams of boric acid per liter is sufficient to reduce the nuclear heating in the Toroidal Field Coil set and limit the activation of components external to the vacuum vessel. Constant extension rate tensile (CERT) and electrochemical potentiodynamic tests were performed. Results of the CERT tests confirm that stress corrosion cracking is not significant for Ti-6Al4V or Ti-3AI-2.5V. Welded andmore » unwelded specimens were tested in air and in borated water at 150{degree}C. Strength, elongation, and time to failure were nearly identical for all test conditions, and all the samples exhibited ductile failure. Potentiodynamic tests on Ti-6A1-4V and Ti in borated water as a function of temperature showed low corrosion rates over a wide passive potential range. Further, this passivity appeared stable to anodic potentials substantially greater than those expected from MHD effects.« less

Novel method for early investigation of bioactivity in different borate bio-glasses

NASA Astrophysics Data System (ADS)

Abdelghany, A. M.

Some ternary borate glasses were prepared and corrosion behavior of such ternary borate glasses after immersion in aqueous dilute phosphate solution was studied using different immersion times. Fourier transform infrared (FTIR) absorption spectral measurements were done before and after immersion in the mentioned solution for extended times up to 2 days to justify the appearance of the characteristic FTIR bands due to calcium phosphate (hydroxyapatite (HA)) which is considered as the potential indication of bioactivity. Experimental IR data confirm the beginning of the appearance of FTIR bands at about 580 and 620 cm-1 after 3 days and the complete resolution with its characteristic split form after 1 week and more. Deconvolution analysis technique (DAT) of the FTIR spectrum was employed to investigate the bioactivity of such ternary borate system after a short period of immersion. The corrosion behavior of such glasses is explained in relation to a suggested hydrolysis followed by direct dissolution mechanism. The ease of dissolution of all the borate glasses constituents explains the formation of calcium phosphate and conversion to crystalline hydroxyapatite within the borate glass matrix. X-ray diffraction may be used to retrace the structural changes and degree of crystallinity of the prepared glasses.

Development of Natural Anthocyanin Dye-Doped Silica Nanoparticles for pH and Borate-Sensing Applications

NASA Astrophysics Data System (ADS)

Ha, Chu T.; Lien, Nghiem T. Ha; Anh, Nguyen D.; Lam, Nguyen L.

2017-12-01

Anthocyanin belongs to a large group of phenolic compounds called flavonoids. It is found primarily in fruits, flowers, roots and other parts of higher plants. Within the black carrot, it has been found that the cyanidin component 1,2 diol was the major anthocyanine. Since the terminal thiols potentially display chemical interactions with borate additives, anthocyanin from the black carrot can act as a sensing material for detecting borate in the environment. As a natural dye, anthocyanin responds to pH change of the medium. Here, we present an application of black carrot dyes for pH sensing and for the detection of borate additives within meats. The dyes were encapsulated within a mesoporous silica (SiO2) matrix in order to prevent the sensing materials from dissolution into the aqueous medium. The encapsulation was done in situ during preparation of silica nanoparticles (size from 100 nm to 500 nm) following an advanced Stöber method. These anthocyanin-encapsulated silica nanoparticles show a clear color change from green in an aqueous solution free of borate to GRAY-red in the presence of borate additive and red (pH 2) to green (pH 10).

A medium range order structural connection to the configurational heat capacity of borate-silicate mixed glasses.

PubMed

Liu, Hao; Smedskjaer, Morten M; Tao, Haizheng; Jensen, Lars R; Zhao, Xiujian; Yue, Yuanzheng

2016-04-28

It has been reported that the configurational heat capacity (C(p,conf)) first increases and then becomes saturated with increasing B2O3/SiO2 ratio in borate-silicate mixed glasses. Through Raman spectroscopy measurements, we have, in this work, found an implication for the intermediate range order (IRO) structural connection to the composition dependence of the C(p,conf) of borate-silicate mixed glasses. In the silica-rich compositions, the C(p,conf) rapidly increases with increasing B2O3 content. This is attributed to the increase of the content of the B-O-Si network units ([B2Si2O8](2-)) and 6-membered borate rings with 1 or 2 B(4). In the boron-rich compositions, the C(p,conf) is almost constant, independent of the increase in the B2O3/SiO2 ratio. This is likely attributed to the counteraction between the decrease of the fraction of two types of metaborate groups and the increase of the fraction of other borate superstructural units (particularly 6-membered borate rings). The overall results suggest that the glasses containing more types of superstructural units have a larger C(p,conf).

Single crystal X-ray diffraction study of the HgBa2CuO4+δ superconducting compound

NASA Astrophysics Data System (ADS)

Bordet, P.; Duc, F.; Lefloch, S.; Capponi, J. J.; Alexandre, E.; Rosa-Nunes, M.; Antipov, E. V.; Putilin, S.

1996-02-01

A high precision X-ray diffraction analysis up to sin θ/λ = 1.15 of a HgBa2CuO4+δ single crystal having a Tc of ~ 90 K is presented. The cell parameters are a = 3.8815(4), c = 9.485 (7) Å. The refinements indicate the existence of a split barium site due to the presence of excess oxygen in the mercury layer. The position of this excess oxygen might be slightly displaced from the (1/2 1/2 0) position. A 6% mercury deficiency is observed. Models, including mercury defects, substitution by copper cations, or carbonate groups, are compared. However, we obtain no definite evidence for either of the three models. A possible disorder of the Hg position, due to the formation of chemical bonds with neighbouring extra oxygen anions, could correlate to the refinements of mixed species at the Hg site. A low temperature single crystal x-ray diffraction study, and comparison of refinements for the same single crystal with different extra oxygen contents, are in progress to help clarify this problem.

Laboratory evaluation of borate/amine/zinc formulations for fungal decay protection

Treesearch

George C. Chen; Rebecca E. Ibach

2010-01-01

The goals of this study were to evaluate borate/amine/zinc formulations in wood for fungal decay protection as well as the permanence of zinc and boron in wood. Wood treated with each of four formulations of borate/amine/zinc prevented or decreased fungal degradation after a 12-week AWPA Standard soil-block test. For non-leached specimens, wood treated with borax/amine...

A mechanistic study of the interaction of water-soluble borate glass with apatite-bound heterocyclic nitrogen-containing bisphosphonates.

PubMed

Pramanik, Chandrani; Sood, Parveen; Niu, Li-Na; Yuan, He; Ghoshal, Sushanta; Henderson, Walter; Liu, Yaodong; Jang, Seung Soon; Kumar, Satish; Pashley, David H; Tay, Franklin R

2016-02-01

Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) is associated with osteonecrosis of the jaw. Although N-BPs bind strongly to bone surfaces via non-covalent bonds, it is possible for extrinsic ions to dissociate bound N-BPs from mineralized bone by competitive desorption. Here, we investigate the effects and mechanism of using an ionic cocktail derived from borate bioactive glass for sequestration of heterocyclic N-BPs bound to apatite. By employing solid-state and solution-state analytical techniques, we confirmed that sequestration of N-BPs from bisphosphonate-bound apatite occurs in the presence of the borate-containing ionic cocktail. Simulations by density functional theory computations indicate that magnesium cation and borate anion are well within the extent of the risedronate or zoledronate anion to form precipitate complexes. The sequestration mechanism is due to the borate anion competing with bisphosphonates for similar electron-deficient sites on the apatite surface for binding. Thus, application of the borate-containing ionic cocktail represents a new topical lavage approach for removing apatite-bound heterocyclic N-BPs from exposed necrotic bone in bisphosphonate-related osteonecrosis of the jaw. Long-term oral consumption and injections of nitrogen-containing bisphosphonates (N-BPs) may result in death of the jaw bone when there is traumatic injury to the bone tissues. To date, there is no effective treatment for such a condition. This work reported the use of an ionic cocktail derived from water-soluble borate glass microfibers to displace the most potent type of N-BPs that are bound strongly to the mineral component on bone surfaces. The mechanism responsible for such an effect has been identified to be cation-mediated complexation of borate anions with negatively-charged N-BPs, allowing them to be released from the mineral surface. This borate-containing cocktail may be developed into a novel topical rinse for removing mineral-bound N-BPs from exposed dead bone. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Flow-Through Leaching of Marine Barite: New Insights on its Composition and Diagenesis

NASA Astrophysics Data System (ADS)

Hsieh, C.; Torres, M. E.; Ungerer, A.; Klinkhammer, G. P.

2007-12-01

The distribution of stable mineral barite (BaSO4) in marine sediments has long been studied as a proxy for paleoproductivity. It is important to investigate the variation in Sr/Ba ratios of crystal barite, as it has a great influence on barite solubility and its early diagenetic processes. In addition, the role of alternative barium carriers to the sediments (e.g. aluminum silicates and oxyhydroxides) and their contributions to overall barium budget and burial efficiency need to be resolved. The techniques currently used to describe and quantify barium phases are all based on batch leaching techniques that define barium phases operationally, not chemically. Because during batch analyses each phase is characterized by a single-point measurement, variations due to phase heterogeneities cannot be resolved; nor can the results of these experiments be related in any systematic way to what happens in nature. To overcome this problem, we are developing a flow-through method that makes use of automated chromatographic techniques, which allows complete monitoring of the dissolution of barite samples with time-resolved analysis (TRA) as each phase is sequentially leached using different reagents. We have analyzed a barite sample recovered from seeps along the San Clemente escarpment, and show that we can attain complete dissolution of the sample (>85%) in 2 hours, using DTPA at 80°C. Approximately 100 μg of barite are first leached with distilled water (pH 5) for 30 minutes. During this step ~2% of the barite is removed. This highly soluble phase has Sr/Ba ratios that range from 30 to 120 mmol/mol. Acid leaching of the samples with 10 mM HNO3 removes an additional 4~8% of the barite, and this phase has Sr/Ba ratios ranging from 13 to 35 mmol/mol. Higher acid concentration (100 mM HNO3) dissolves up to 40% of the barite. These results are consistent with electron microprobe data that show clear oscillatory zoning of the (Ba,Sr)SO4. Unlike the barite sample, sediment samples collected at the base of the escarpment did not show a Ba release in the water leach. We might speculate that the highly susceptible Sr-rich barium phase present in the barite sample, dissolved during transport from a seep site leaving a barite with a lower Sr/Ba ratio, as found in the sediment samples. Our analytical approach has the potential to further address a variety of outstanding questions on the complex geochemical cycle of barium and its applications to climate change, upper ocean fertility and ocean circulation through time.

Irradiation effect on luminescence properties of fluoroperovskite single crystal (LiBaF3:Eu2+)

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Madhusoodanan, U.; Nithya, R.; Ramasamy, P.

2014-03-01

Single crystals of pure and Eu2+ doped LiBaF3 have been grown from melt by using a vertical Bridgman-Stockbarger method. Effects induced by irradiation on europium doped LiBaF3 (lithium barium fluoride) single crystals were monitored by optical absorption, photoluminescence and thermoluminescence studies. The absorption bands of Eu2+ ions with peaks at 240, 290 and 320 nm were observed in the LiBaF3:Eu2+ crystal. Drastic increase in absorption was noted below 600 nm after gamma irradiation, which was dependent on the radiation dose. The additional absorption peak at around 570 nm was observed in irradiated crystal due to the ionization process Eu2+(-)e-→Eu3+. Photoluminescence of Eu2+ doped LiBaF3 single crystal shows sharp line peaked at ~359 nm and a broad band extending between 370 and 450 nm which shows a considerable reduction in Eu2+ PL intensity after gamma irradiation. Irradiated LiBaF3:Eu2+ sample has revealed three intense TL glow peaks at 128 °C (peak-1), 281 °C (peak-2) and 407 °C (peak-3). Activation energy (E) and frequency factor (s) of the latter two peaks were determined by various heating rate (VHR) method and graphical method.

Orientation control of barium titanate films using metal oxide nanosheet layer

NASA Astrophysics Data System (ADS)

Uchida, Hiroshi; Oi, Tomotake; Noguchi, Keito; Moki, Shota; Kim, Jin Woon; Shima, Hiromi; Nishida, Ken; Kiguchi, Takanori; Akama, Akihiko; Konno, Toyohiko J.; Funakubo, Hiroshi

2016-10-01

In the present work, we aim to achieve the preferred crystal orientation of chemical solution deposition (CSD)-derived BaTiO3 films on ubiquitous Si wafers with the assistance of Ca2Nb3O10 nanosheet (ns-CN) template layers. The ns-CN on platinized Si (Pt/Si) substrates aligned the BaTiO3(100) plane to the substrate surface, because of the favorable lattice matching of the ns-CN (001) plane. The CSD process in air required a high crystallization temperature of 900 °C for the preferred crystal orientation of BaTiO3(100) because of the BaCO3 byproduct generated during the combustion reaction of the precursor gel. The processing in vacuum to remove CO2 species enhanced the crystal orientation even at the crystallization temperature of 800 °C, although it can generate oxygen vacancies (\\text{V}\\text{O}{} \\bullet \\bullet ) that cause distorted polarization behavior under an applied field higher than approximately 150 kV/cm. The relative dielectric constant (εr) of the (100)-oriented BaTiO3 film on the ns-CN-supported Pt/Si substrate (ns-CN/Pt/Si) was generally larger than that of the randomly oriented film on Pt/Si, depending on the degree of crystal orientation.

Investigations on the local structures of Cu2+ at various BaO concentrations in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO glasses

NASA Astrophysics Data System (ADS)

Jin, Jia-Rui; Wu, Shao-Yi; Hong, Jian; Liu, Shi-Nan; Song, Min-Xian; Teng, Bao-Hua; Wu, Ming-He

2017-11-01

The local structures and electron paramagnetic resonance (EPR) parameters for Cu2+ in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO (BKZBC) glasses are theoretically investigated with distinct modifier BaO concentrations x (= 0, 6, 12, 18, 24 and 30 mol %). The ? clusters are found to undergo the relative tetragonal elongations of about 13.5 and 5.0% at zero and higher BaO concentrations. The concentration dependences of the measured d-d transition bands, g factors and A// are suitably reproduced from the Fourier type functions or sign functions of the relevant quantities with x by using only six adjustable parameters. The features of the EPR parameters and the local structures of Cu2+ are analysed in a consistent way by considering the differences in the local ligand field strength and electronic cloud admixtures around Cu2+ under addition of Ba2+ with the highest ionicity and polarisability. The present theoretical studies would be helpful to the researches on the structures, optical and EPR properties for the similar potassium barium zinc borate glasses containing copper with variation concentration of modifier BaO.

Electric, Magnetic, and Magnetoelectric Properties of Yttrium-Containing BaY0.025Ti0.9625O3-SrFe12O19 Composite

NASA Astrophysics Data System (ADS)

Rather, Mehraj ud Din; Samad, Rubiya; Want, Basharat

2018-03-01

The physical properties of BaY0.025Ti0.9625O3, SrFe12O19, and 0.90BaY0.025Ti0.9625O3-0.10 SrFe12O19 composite have been studied. The proposed composite was synthesized by solid-state reaction method from yttrium barium titanate processed by solid-state reaction and strontium hexaferrite obtained by a sol-gel process. Microstructural analysis revealed monophasic grains for yttrium barium titanate phase, while loosely packed biphasic structure was observed for the composite. Powder x-ray analysis showed that the individual phases retained their crystal structure in the composite, without formation of any new additional phase. Measurement of magnetic hysteresis loops at room temperature indicated that the magnetic parameters of the composite were diluted by the presence of the ferroelectric phase. The ferroelectric hysteresis of yttrium barium titanate confirmed the ferroelectric transition at 119°C. Meanwhile, the symmetrical ferroelectric loops observed at different fields established the ferroelectric nature of the composite. Improved dielectric properties and low dielectric losses were observed due to yttrium doping in the composite. The diffuseness of the ferroelectric transitions for the composite was confirmed by the Curie-Weiss law. Activation energy calculations revealed the charge-hopping conduction mechanism in the composite. Magnetodielectric studies confirmed that the overall magnetocapacitance in the composite exhibited combined effects of magnetoresistance and magnetoelectric coupling.

Low-energy collisionally activated dissociation of pentose-borate complexes

NASA Astrophysics Data System (ADS)

Pepi, Federico; Garzoli, Stefania; Tata, Alessandra; Giacomello, Pierluigi

2010-01-01

Pentose-borate 1:1 complexes were generated in the ESI source of a triple quadrupole and ion trap mass spectrometer by electrospray ionization of Na2B4O7 and pentose (arabinose, lyxose, ribose, xylose) 2:1 solution in CH3CN/H2O. The study of their low-energy collisionally activated dissociation (CAD) demonstrated that ribose and lyxose are preferentially complexed at the C2-C3 cis-diol function whereas arabinose and xylose are esterified at the C1-C2 hydroxyl groups. No evidence was found of the stronger affinity for ribose to borate. The ribose probiotic rule can be explained by considering its peculiar capability, among the investigated pentoses, to almost totally complex the borate anion at the C2-C3 hydroxyl group, thus enabling the subsequent stages of nucleotide assembly, such as phosphorylation and linkage to the nucleobases. Finally, the differences observed in the pentose-borate complex CAD spectra can be used for the mass spectrometric discrimination of isomeric pentoses in complex mixtures.

Study on Microstructure and Electrochemical Corrosion Behavior of PEO Coatings Formed on Aluminum Alloy

NASA Astrophysics Data System (ADS)

Xiang, N.; Song, R. G.; Li, H.; Wang, C.; Mao, Q. Z.; Xiong, Y.

2015-12-01

Plasma electrolytic oxidation (PEO) treated 6063 aluminum alloy was applied in a silicate- and borate-based alkaline solution. The microstructure and electrochemical corrosion behavior were studied by scanning electron microscopy, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. The results showed that the silicate-based PEO coating was of a denser structure compared with that of borate-based PEO coating. In addition, the silicate-based PEO coating was composed of more phased (Al9Si) than borate-based PEO coating. The results of corrosion test indicated that the silicate-based PEO coating provided a superior protection to 6063 aluminum alloy substrate, while borate-based PEO coating with a porous structure showed an inferior conservancy against corrosive electrolyte. Furthermore, the EIS tests proved that both coatings were capable to resist the aggressive erosion in 0.5 M NaCl solution after 72 h of immersion. However, the borate-based PEO coating could not provide sufficient protection to the substrate after 72-h immersion in 1 M NaCl solution.

Synthesis of hydrophobic zinc borate nanoflakes and its effect on flame retardant properties of polyethylene

NASA Astrophysics Data System (ADS)

Li, Shengli; Long, Beihong; Wang, Zichen; Tian, Yumei; Zheng, Yunhui; Zhang, Qian

2010-04-01

Zinc borate (2ZnO·3B 2O 3·3.5H 2O) has relatively high dehydration on-set temperature which property permits processing in a wide range of polymer system. But zinc borate particles are hardly dispersed in a polymer matrix so that they prevent their using in industry. To address this problem, we synthesized hydrophobic zinc borate (2ZnO·3B 2O 3·3.5H 2O) nanoflakes by employing solid-liquid reaction of zinc oxide (ZnO) and boric acid (H 3BO 3) in the presence of oleic acid. This method does not bring pollution. By conducting morphological and microscopic analyses, we found that this compound displayed nanoflake morphology with particle size of around 100-200 nm, thickness less than 100 nm and there were uniform mesopores with the diameter about 10 nm within the particles. Furthermore, our products had an effect on flame retardant of polyethylene, especially when the zinc borate was modified by oleic acid.

Boron

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

Cozen, L.F.

1991-05-01

This paper reports that borate minerals and refined borates are used extensively for the manufacture of vitreous materials such as insulation and textile fiberglasses, borosilicate glass, and porcelain enamels and frits. In North America, these applications are estimated to account for over 54% of the borate consumption. Other substantial uses are in soaps and detergents, metallurgy, fire retardants, industrial biocides, agriculture, and various miscellaneous applications. Reported domestic borate consumption in 1990 was estimated by the U.S. Bureau of Mines to be 320 000 metric tons B{sub 2}O{sub 3} versus 354 000 metric tons B{sub 2}O{sub 3} in 1989. Consumption ismore » projected to remain essentially static in 1991. Imports were estimated by the Bureau to be 50 000 metric tons B{sub 2}O{sub 3} in 1990. Exports of boric acid and refined borates were approximately 650 000 metric tons of product, a 15 000 metric ton increase from the 1989 level. This increase partially offsets the drop in the 1990 consumption level.« less

Barium light source method and apparatus

NASA Technical Reports Server (NTRS)

Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

2002-01-01

Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

A review of recent theoretical studies in nonlinear crystals: towards the design of new materials

NASA Astrophysics Data System (ADS)

Luppi, Eleonora; Véniard, Valérie

2016-12-01

Nonlinear optics is an important and exciting field of fundamental and applied research, with applications in many different disciplines such as physics chemistry, material science and biology. In the recent years, nonlinear optical phenomena started to be also widely used in technological applications for optoelectronics and photovoltaics. This coincided with an important experimental and theoretical search for new materials with an efficient and exploitable nonlinear optical response. Here, starting from the discovery of nonlinear optics, we review the most important theoretical formalisms developed to understand, interpret and predict the nonlinear optical phenomena. We show the different level of approximation of the many-electrons interactions that these formalisms can describe which are fundamental in the interpretation of the experiments. The impact of the theory is then analyzed on different classes of new materials particularly studied in these years: silicon bulk to nano, compound semiconductors, graphene, transition metal dichalcogenide, hexagonal boron nitride and borate crystals.

Effect of erbium(III) oxide addition on thermal properties and crystallization behavior of some zinc-borate glasses

NASA Astrophysics Data System (ADS)

Borodi, G.; Bolundut, L. C.; Pascuta, P.

2017-12-01

The effect of replacing B2O3 with Er2O3 on the thermal properties and crystallization behaviour of B2O3-ZnO glasses were investigated by Differential Thermal Analysis (DTA) and X-ray Diffraction Analysis (XRD) measurements. DTA measurements reveal that the temperature of vitreous transition and the glass stability increase with the increasing in concentration the erbium ions added in the samples. The fragility index of the glasses increases also, when the dopant concentration from the studied samples increases. The glass was obtained from kinetically strong-glass-forming liquid (KS type glass). The most stable sample from the thermal point of view seems to be the sample that contains 10 mol% of Er2O3. The XRD patterns of the heat-treated samples at 860°C show new crystalline phases that contain erbium when the concentration of Er2O3 in the samples is higher than 3 mol%.

In vitro stimulation of vascular endothelial growth factor by borate-based glass fibers under dynamic flow conditions.

PubMed

Chen, Sisi; Yang, Qingbo; Brow, Richard K; Liu, Kun; Brow, Katherine A; Ma, Yinfa; Shi, Honglan

2017-04-01

Bioactive borate glass has been recognized to have both hard and soft tissue repair and regeneration capabilities through stimulating both osteogenesis and angiogenesis. However, the underlying biochemical and cellular mechanisms remain unclear. In this study, dynamic flow culturing modules were designed to simulate the micro-environment near the vascular depletion and hyperplasia area in wound-healing regions, thus to better investigate the mechanisms underlying the biocompatibility and functionality of borate-based glass materials. Glass fibers were dosed either upstream or in contact with the pre-seeded cells in the dynamic flow module. Two types of borate glasses, doped with (1605) or without (13-93B3) CuO and ZnO, were studied along with the silicate-based glass, 45S5. Substantial fiber dissolution in cell culture medium was observed, leading to the release of ions (boron, sodium and potassium) and the deposition of a calcium phosphate phase. Different levels of vascular endothelial growth factor secretion were observed from cells exposed to these three glass fibers, and the copper/zinc containing borate 1605 fibers exhibited the most positive influence. These results indicate that dynamic studies of in vitro bioactivity provide useful information to understand the in vivo response to bioactive borate glasses. Copyright © 2016 Elsevier B.V. All rights reserved.

Novel method for early investigation of bioactivity in different borate bio-glasses.

PubMed

Abdelghany, A M

2013-01-01

Some ternary borate glasses were prepared and corrosion behavior of such ternary borate glasses after immersion in aqueous dilute phosphate solution was studied using different immersion times. Fourier transform infrared (FTIR) absorption spectral measurements were done before and after immersion in the mentioned solution for extended times up to 2 days to justify the appearance of the characteristic FTIR bands due to calcium phosphate (hydroxyapatite (HA)) which is considered as the potential indication of bioactivity. Experimental IR data confirm the beginning of the appearance of FTIR bands at about 580 and 620 cm(-1) after 3 days and the complete resolution with its characteristic split form after 1 week and more. Deconvolution analysis technique (DAT) of the FTIR spectrum was employed to investigate the bioactivity of such ternary borate system after a short period of immersion. The corrosion behavior of such glasses is explained in relation to a suggested hydrolysis followed by direct dissolution mechanism. The ease of dissolution of all the borate glasses constituents explains the formation of calcium phosphate and conversion to crystalline hydroxyapatite within the borate glass matrix. X-ray diffraction may be used to retrace the structural changes and degree of crystallinity of the prepared glasses. Copyright © 2012 Elsevier B.V. All rights reserved.

Observation of a different birefringence order at optical and THz frequencies in LBO crystal

NASA Astrophysics Data System (ADS)

Andreev, Yu. M.; Kokh, A. E.; Kokh, K. A.; Lanskii, G. V.; Litvinenko, K.; Mamrashev, A. A.; Molloy, J. F.; Murdin, B.; Naftaly, M.; Nikolaev, N. A.; Svetlichnyi, V. A.

2017-04-01

THz optical properties of lithium borate (LBO) crystals were measured using time-domain spectroscopy (TDS). The LBO crystal samples were of high optical quality and were cut and polished along the 〈100〉, 〈010〉 and 〈001〉 axes. Two independent measurements were performed in order to confirm the reproducibility and consistency of results. The contradictions in the previously published data on the THz optical properties of LBO were clarified. It was shown that the birefringence order at THz frequencies is nz

X-ray diffraction, crystal structure, and spectral features of the optical susceptibilities of single crystals of the ternary borate oxide lead bismuth tetraoxide, PbBiBO4.

PubMed

Reshak, Ali Hussain; Kityk, I V; Auluck, S; Chen, Xuean

2009-05-14

The all-electron full-potential linearized augmented plane-wave method has been used for an ab initio theoretical study of the band structure, the spectral features of the optical susceptibilities, the density of states, and the electron charge density for PbBiBO4. Our calculations show that the valence-band maximum (VBM) and conduction-band minimum (CBM) are located at the center of the Brillouin zone, resulting in a direct energy gap of about 3.2 eV. We have synthesized the PbBiBO4 crystal by employing a conventional solid-state reaction method. The theoretical calculations in this work are based on the structure built from our measured atomic parameters. We should emphasize that the observed experimental X-ray diffraction (XRD) pattern is in good agreement with the theoretical one, confirming that our structural model is valid. Our calculated bond lengths show excellent agreement with the experimental data. This agreement is attributed to our use of full-potential calculations. The spectral features of the optical susceptibilities show a small positive uniaxial anisotropy.

NH4 Be2 BO3 F2 and γ-Be2 BO3 F: Overcoming the Layering Habit in KBe2 BO3 F2 for the Next-Generation Deep-Ultraviolet Nonlinear Optical Materials.

PubMed

Peng, Guang; Ye, Ning; Lin, Zheshuai; Kang, Lei; Pan, Shilie; Zhang, Min; Lin, Chensheng; Long, Xifa; Luo, Min; Chen, Yu; Tang, Yu-Huan; Xu, Feng; Yan, Tao

2018-05-12

KBe 2 BO 3 F 2 (KBBF) is still the only practically usable crystal that can generate deep-ultraviolet (DUV) coherent light by direct second harmonic generation (SHG). However, applications are hindered by layering, leading to difficulty in the growth of thick crystals and compromised mechanical integrity. Despite efforts, it is still a great challenge to discover new nonlinear optical (NLO) materials that overcome the layering while keeping the DUV SHG available. Now, two new DUV NLO beryllium borates have been successfully designed and synthesized, NH 4 Be 2 BO 3 F 2 (ABBF) and γ-Be 2 BO 3 F (γ-BBF), which not only overcome the layering but also can be used as next-generation DUV NLO materials with the shortest type I phase-matching second-harmonic wavelength down to 173.9 nm and 146 nm, respectively. Significantly, γ-BBF is superior to KBBF in all metrics and would be the most outstanding DUV NLO crystal. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Ferroelectric KNbO3 Based Borate Glass System.

PubMed

Kruea-In, Chatchai; Intawin, Pratthana; Leenakul, Wilaiwan

2015-11-01

The incorporation method was employed to produce ferroelectric glass ceramics from the K2O-Nb2O5-B2O3 glass system. The nanocrystalline potassium niobate (KNbO3) was first prepared using a simple mixed oxide method, where the B2O3 was initially mixed and then melted to form glass. The successfully produced optically transparent glass was then subjected to a heat treatment schedule for further crystallization at temperatures ranging from 500 to 650 degrees C, which resulted in the precipitation of the KNbO3 phase, together with the K3B2Nb3O12 phase. Scanning electron microscopy (SEM) showed the presence of randomly oriented KNbO3 crystals dispersed in a continuous glass matrix. It was found that the glass ceramics subjected to the heat treatment at temperatures higher than 545 degrees C were opaque, while the lower gave a highly transparent glass ceramics. The crystal size and crystallinity were found to increase with increasing heat treatment temperature, which in turn plays an important role in controlling the properties of the glass ceramics, including physical, optical, and dielectric properties.

Control of piezoelectricity in amino acids by supramolecular packing

NASA Astrophysics Data System (ADS)

Guerin, Sarah; Stapleton, Aimee; Chovan, Drahomir; Mouras, Rabah; Gleeson, Matthew; McKeown, Cian; Noor, Mohamed Radzi; Silien, Christophe; Rhen, Fernando M. F.; Kholkin, Andrei L.; Liu, Ning; Soulimane, Tewfik; Tofail, Syed A. M.; Thompson, Damien

2018-02-01

Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V-1, limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V-1) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN-1, which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.

Control of piezoelectricity in amino acids by supramolecular packing.

PubMed

Guerin, Sarah; Stapleton, Aimee; Chovan, Drahomir; Mouras, Rabah; Gleeson, Matthew; McKeown, Cian; Noor, Mohamed Radzi; Silien, Christophe; Rhen, Fernando M F; Kholkin, Andrei L; Liu, Ning; Soulimane, Tewfik; Tofail, Syed A M; Thompson, Damien

2018-02-01

Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V -1 , limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V -1 ) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN -1 , which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.

Spectroscopic properties of heavily Ho3+-doped barium yttrium fluoride crystals

NASA Astrophysics Data System (ADS)

Ji, En-Cai; Liu, Qiang; Nie, Ming-Ming; Luo, Hui; Hu, Yu-Xi; Guan, Zhou-Guo; Gong, Ma-Li

2015-09-01

The 30 at.% Ho: BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd-Ofelt theory. The Judd-Ofelt intensity parameters are estimated to be Ω2 = 6.74 × 10-20 cm2, Ω4 = 1.20 × 10-20 cm2, and Ω6 = 0.66 × 10-20 cm2, and the fluorescence branching ratios and radiative lifetimes for a series of excited state manifolds are also determined. The emission cross sections with our measured infrared luminescence spectra, especially important for 4.1 μm, are calculated to be about 4.37 × 10-21 cm2. The crystal quality is preliminarily tested through a mid-infrared laser emission experiment. Project supported by the National Natural Science Foundation of China (Grant No. 61275146), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110066), and the Special Program of the Co-construction with Beijing Municipal Government of China (Grant No. 20121000302).

Borate protection of softwood from Coptotermes acinaciformis (Isoptera: Rhinotermitidae) damage: variation in protection thresholds explained.

PubMed

Peters, Brenton C; Fitzgerald, Christopher J

2006-10-01

Laboratory and field data reported in the literature are confusing with regard to "adequate" protection thresholds for borate timber preservatives. The confusion is compounded by differences in termite species, timber species and test methodology. Laboratory data indicate a borate retention of 0.5% mass/mass (m/m) boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to < or = 5%. Field data generally suggest that borate retentions appreciably > 0.5% m/m BAE are required. We report two field experiments with varying amounts of untreated feeder material in which Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae) responses to borate-treated radiata (Monterey) pine, Pinus radiata D. Don, were measured. The apparently conflicting results between laboratory and field data are explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, wood containing 0.5% BAE provided adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions were required. Furthermore, the retentions required increased with increased amounts of susceptible material present. Some termites, Nasutitermes sp. and Mastotermes darwiniensis Froggatt, for example, are borate-tolerant and borate timber preservatives are not a viable management option with these species. The lack of uniform standards for termite test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of timber preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed.

Structural insights into the thermal decomposition sequence of barium tetrahydrogenorthotellurate(VI), Ba[H{sub 4}TeO{sub 6}

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

Weil, Matthias, E-mail: Matthias.Weil@tuwien.ac.at; Stöger, Berthold; Gierl-Mayer, Christian

2016-09-15

The compounds Ba[H{sub 4}TeO{sub 6}] (I), Ba[H{sub 2}TeO{sub 5}] (II), Ba[Te{sub 2}O{sub 6}(OH){sub 2}] (III) and Ba[TeO{sub 4}] (IV) were prepared by application of a diffusion method (I), under hydrothermal conditions (II and III) and from solid state reactions (IV), respectively. Structure analysis on the basis of single crystal X-ray diffraction data revealed novel structure types for (I), (II) and (III) and isotypism of (IV) with PrSbO{sub 4} and LaSbO{sub 4}. Common feature of the four oxotellurate(VI) structures are [TeO{sub 6}] octahedra. Whereas in the crystal structure of (I) the octahedral units are isolated, they are condensed into chains viamore » corner-sharing in (II) and via edge-sharing in (III) and (IV). The coordination numbers of the barium cations in the four structures range from seven to ten. Although hydrogen atom positions could not be located for the structures of (I) and (II), short interpolyhedral O···O contacts are evident for strong hydrogen bonding. The temperature behaviour of (I), (II) and (IV) was monitored by simultaneous thermal analysis (STA) measurements and in situ powder X-ray diffraction, revealing the decomposition sequence Ba[H{sub 4}TeO{sub 6}] → Ba[H{sub 2}TeO{sub 5}] → Ba[TeO{sub 4}]→ Ba[TeO{sub 3}] upon heating to temperatures up to 900 °C. - Graphical abstract: The crystal structures of the four oxotellurates(VI) were determined from single crystal data. The thermal decomposition of Ba[H{sub 4}TeO{sub 6}], monitored by temperature-dependent X-ray powder diffraction and simultaneous thermal analysis measurements, involves two condensation reactions according to Ba[H{sub 4}TeO{sub 6}]→Ba[H{sub 2}TeO{sub 5}]+H{sub 2}O(↑)→Ba[TeO{sub 4}]+ H{sub 2}O(↑). Display Omitted.« less

Mineralogy and autoradiography of selected mineral-spring precipitates in the Western United States

USGS Publications Warehouse

Bove, Dana; Felmlee, J.K.

1982-01-01

X-ray diffaction analysis of 236 precipitate or sediment samples from 97 mineral-spring sites in nine Western States showed the presence of 25 minerals, some precipitated and some detrital. Calcite and (or) aragonite are the most common of all the precipitated minerals. Gypsum and (or) anhydrite, as well as barite and native sulfur, are less common but are also believed to be precipitated minerals. Precipitated manganese and iron oxides, including romanechite, manganite, pyrolusite, goethite, and hematite, were found in some of the samples. Various salts of sodium, including halite and thenardite, were also identified. Dolomite and an unknown type of siliceous material are present in some of the samples and were possibly precipitated at the spring sites. Quartz, feldspar, and mica are present in many of the samples and are believed to be detrital contaminants. An autoradiographic and thin section study of 11 samples from nine of the most radioactive spring sites showed the radioactivity, which is due primarily to radium, to be directly associated with mineral phases containing barium, manganese, iron, and (or) calcium as major constituents. Furthermore, the radioactivity has an exclusive affinity for the manganese-bearing minerals, which in these samples contain a substantial amount of barium, even if calcite or iron oxides are present. Where calcite predominates and manganese- and barium-bearing minerals are absent, the radioactivity shows a close association with the iron oxides present, especially hematite, but also shows a moderate association with the calcite and (or) aragonite cementing phases. In other samples composed predominantly of calcite but lacking iron oxides, the radioactivity is preferentially associated with an early stage of calcite development and is considerably lower in the later cementing stages. The radioactivity observed in all these samples is believed to be caused by radium substituting for barium in mineral lattices, filling irregularities in other crystal structures, or adsorbing on the surfaces of precipitated molecules.

Design and Adaptation of an Optical System for Slit Lamp Delivery of a CO2 Laser Beam.

DTIC Science & Technology

1981-12-01

laser’s efficacy to serve as a photocoagulator. A non-linear barium sodium niobate crystal converted the near infrared radiation (1.064 pm) to green...recommendations. 10 II. Theoretical Development and Predictions Corneal tissue is an excellent absorber of infrared radiation. Therefore, when high power CO2...in general, that the waist will be formed slightly to one Lde of the focal plane, as shown in Eq (4) (Ref 18:31). f2 (zl-f) 2. = + wW2 (4) (zl-f) 2

Eu-doped BaTiO₃powder and film from sol-gel process with polyvinylpyrrolidone additive.

PubMed

García-Hernández, Margarita; García-Murillo, Antonieta; de J Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

2009-09-17

Transparent BaTiO(3):Eu(3+) films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO(3):Eu(3+) films ~500 nm thick, crystallized after thermal treatment at 700 masculineC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu(3+) doped BaTiO(3).

BARIUM RECOVERY PROCESS

DOEpatents

Blanco, R.E.

1959-07-21

A method of separating barium from nuclear fission products is described. In accordance with the invention, barium may be recovered from an acidic solution of neutron-irradiated fissionable material by carrying ihe barium cut of solution as a sulfate with lead as a carrier and then dissolving the barium-containing precipitate in an aqueous solution of an aliphatic diamine chelating reagent. The barium values together with certain other metallic values present in the diamine solution are then absorbed onto a cation exchange resin and the barium is selectively eluted from the resin bed with concentrated nitric acid.

Method of recycling lithium borate to lithium borohydride through diborane

DOEpatents

Filby, Evan E.

1976-01-01

This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a diborane intermediate to complete the recycle scheme.

The Barium Site in a Potassium Channel by X-Ray Crystallography

PubMed Central

Jiang, Youxing; MacKinnon, Roderick

2000-01-01

X-ray diffraction data were collected from frozen crystals (100°K) of the KcsA K+ channel equilibrated with solutions containing barium chloride. Difference electron density maps (Fbarium − Fnative, 5.0 Å resolution) show that Ba2+ resides at a single location within the selectivity filter. The Ba2+ blocking site corresponds to the internal aspect (adjacent to the central cavity) of the “inner ion” position where an alkali metal cation is found in the absence of the blocking Ba2+ ion. The location of Ba2+ with respect to Rb+ ions in the pore is in good agreement with the findings on the functional interaction of Ba2+ with K+ (and Rb+) in Ca2+-activated K+ channels (Neyton, J., and C. Miller. 1988. J. Gen. Physiol. 92:549–567). Taken together, these structural and functional data imply that at physiological ion concentrations a third ion may interact with two ions in the selectivity filter, perhaps by entering from one side and displacing an ion on the opposite side. PMID:10694255

Microstructural and thermal properties of pure BaFe{sub 12}O{sub 19} and Sr doped barium ferrite (Ba{sub 0.9}Sr{sub 0.1}Fe{sub 12}O{sub 19}) synthesized by auto combustion method

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

Taufeeq, Saba, E-mail: sabataufeeq23@gmail.com; Parveen, Azra; Agrawal, Shraddha

2016-05-23

Nanoparticles (NPs) of Pure BaFe{sub 12}O{sub 19} and Strontium doped Barium Ferrite (Ba{sub 0.9}Sr{sub 0.1}Fe{sub 12}O{sub 19}) have been successfully synthesized by Auto combustion method using citric acid as a chelating agent and calcined at 450°C for 3 hrs and 850°C for 4 hrs. Microstructural studies were carried by XRD and SEM techniques. Structural studies suggest that the crystal system remains hexagonal even with the doping of Strontium. The XRD analysis confirms the formation of the structures in the nanometer regime and the peaks are the evidence of the crystalline phase. The SEM images shows the morphology of surface ofmore » the samples. The thermal property studied by TGA shows the weight loss which is with varying the temperature and weight loss also varies with Sr doping. The TGA analysis exhibits the loss of weight at different temperatures.« less

Low-loss Z-type barium hexaferrite composites from nanoscale ZnAl2O4 addition for high-frequency applications

NASA Astrophysics Data System (ADS)

Zheng, Zongliang; Feng, Quanyuan; Harris, Vincent G.

2018-05-01

In this study, nanocrystalline ZnAl2O4 (ZA) were introduced to Z-type barium hexaferrite (Co2Z) and the effects of ZA addition upon the crystal-phase composition, microstructure, permeability and permittivity as well as losses characteristics over a wide frequency range of 10 MHz-1 GHz have been systematically investigated. With increasing ZA content (x) from 0 to 15 wt%, the permeability μ' at low frequencies decreased from 12.0 to 4.3, while the permittivity ɛ' was decreased from 27.4 to 10.7. Correspondingly, the frequency stability of permeability and permittivity were improved and the losses were effectively reduced. When x is in the range of 5-10 wt%, the magnetic loss tan δμ is in the order of 10-2 and the dielectric loss tan δɛ is in the order of 10-3 at 300 MHz, which is lower by one order of magnitude compared with that of undoped Co2Z. The modified magnetic and dielectric properties are closely related to the changing phase composition and microstructure.

VizieR Online Data Catalog: Infrared properties of barium stars (Chen+, 2001)

NASA Astrophysics Data System (ADS)

Chen, P. S.

2001-04-01

We present the results of a systematic survey for IRAS associations of barium stars. A total of 155 associations were detected, and IRAS low-resolution spectra exist for 50 barium stars. We use different color-color diagrams from the visual band to 60μm, relations between these colors and the spectral type, the barium intensity, and the IRAS low-resolution spectra to discuss physical properties of barium stars in the infrared. It is confirmed that most barium stars have infrared excesses in the near infrared. However, a new result of this work is that most barium stars have no excesses in the far infrared. This fact may imply that infrared excesses of barium stars are mainly due to the re-emission of energy lost from the Bond-Neff depression. It is also shown that the spectral type and the barium intensity of barium stars are not correlated with infrared colors, but may be correlated with V-K color. (1 data file).

Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

PubMed

Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

2016-04-06

Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution.

Selection of plants for phytoremediation of barium-polluted flooded soils.

PubMed

Ribeiro, Paulo Roberto Cleyton de Castro; Viana, Douglas Gomes; Pires, Fábio Ribeiro; Egreja Filho, Fernando Barboza; Bonomo, Robson; Cargnelutti Filho, Alberto; Martins, Luiz Fernando; Cruz, Leila Beatriz Silva; Nascimento, Mauro César Pinto

2018-05-10

The use of barite (BaSO4) in drilling fluids for oil and gas activities makes barium a potential contaminant in case of spills onto flooded soils, where low redox conditions may increase barium sulfate solubility. In order to select plants able to remove barium in such scenarios, the following species were evaluated on barium phytoextraction capacity: Brachiaria arrecta, Cyperus papyrus, Eleocharis acutangula, E. interstincta, Nephrolepsis cf. rivularis, Oryza sativa IRGA 424, O. sativa BRS Tropical, Paspalum conspersum, and Typha domingensis. Plants were grown in pots and exposed to six barium concentrations: 0, 2.5, 5.0, 10.0, 30.0, and 65.0 mg kg -1 . To simulate flooding conditions, each pot was kept with a thin water film over the soil surface (∼1.0 cm). Plants were evaluated for biomass yield and barium removal. The highest amount of barium was observed in T. domingensis biomass, followed by C. papyrus. However, the latter exported most of the barium to the aerial part of the plant, especially at higher BaCl 2 doses, while the former accumulated barium preferentially in the roots. Thus, barium removal with C. papyrus could be achieved by simply harvesting aerial biomass. The high amounts of barium in T. domingensis and C. papyrus resulted from the combination of high barium concentration in plant tissues with high biomass production. These results make T. domingensis and C. papyrus potential candidates for phytoremediation schemes to remove barium from flooded soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Crystal growth, crystal structure of new polymorphic modification, β-Bi 2B 8O 15 and thermal expansion of α-Bi 2B 8O 15

NASA Astrophysics Data System (ADS)

Bubnova, R. S.; Alexandrova, J. V.; Krivovichev, S. V.; Filatov, S. K.; Egorysheva, A. V.

2010-02-01

Single crystals of α- and β-polymorphs of Bi 2B 8O 15 were grown by Czochralski method from a charge of the stoichiometric composition. The crystal structure of β-Bi 2B 8O 15 was solved by direct methods from a twinned crystal and refined to R1=0.081 (w R=0.198) on the basis of 1584 unique observed reflections ( I>2 σ( I)). The compound is triclinic, space group P1¯, a=4.3159(8), b=6. 4604(12), c=22.485(4) Å, α=87.094(15)°, β=86.538(15)°, γ=74.420(14)°, V=602.40(19) Å 3, Z=2. The B-O layered anion of β-Bi 2B 8O 15 is topologically identical to the anion of α-Bi 2B 8O 15 but the orientation of neighboring layers is different. Thermal expansion of α-Bi 2B 8O 15 has been investigated by X-ray powder diffraction in air in temperature range from 20 to 700 °C. It is strongly anisotropic, which can be explained by the hinge mechanism applied to chains of Bi-O polyhedra. While the anisotropy of thermal expansion is rather high, the volume thermal expansion coefficient α V=40×10 6 °C -1 for α-Bi 2B 8O 15 is close to those of other bismuth borates.

Crystallization Kinetics of Barium and Strontium Aluminosilicate Glasses of Feldspar Composition

NASA Technical Reports Server (NTRS)

Hyatt, Mark J.; Bansal, Narottam P.

1994-01-01

Crystallization kinetics of BaO.Al2O3.2SiO2 (BAS) and SrO.Al2O3.2SiO2 (SAS) glasses in bulk and powder forms have been studied by non-isothermal differential scanning calorimetry (DSC). The crystal growth activation energies were evaluated to be 473 and 451 kJ/mol for bulk samples and 560 and 534 kJ/mol for powder specimens in BAS and SAS glasses, respectively. Development of crystalline phases on thermal treatments of glasses at various temperatures has been followed by powder x-ray diffraction. Powder samples crystallized at lower temperatures than the bulk and the crystallization temperature was lower for SAS glass than BAS. Crystallization in both glasses appeared to be surface nucleated. The high temperature phase hexacelsian, MAl2Si2O8 (M = Ba or Sr), crystallized first by nucleating preferentially on the glass surface. Also, monoclinic celsian does not nucleate directly in the glass, but is formed at higher temperatures from the transformation of the metastable hexagonal phase. In SAS the transformation to monoclinic celsian occurred rapidly after 1 h at 1100 C. In contrast, in BAS this transformation is sluggish and difficult and did not go to completion even after 10 h heat treatment at 1400 C. The crystal growth morphologies in the glasses have been observed by optical microscopy. Some of the physical properties of the two glasses are also reported.

The Mechanism of Boron Mobility in Wheat and Canola Phloem1[C][OA

PubMed Central

Stangoulis, James; Tate, Max; Graham, Robin; Bucknall, Martin; Palmer, Lachlan; Boughton, Berin; Reid, Robert

2010-01-01

Low-molecular-weight borate complexes were isolated from canola (Brassica napus) and wheat (Triticum aestivum) phloem exudates, as well as the cytoplasm of the fresh-water alga Chara corallina, and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Phloem exudate was collected from field-grown canola inflorescence stalks by shallow incision, while wheat phloem exudate was collected by aphid stylectomy. Chara cytoplasm was collected by careful manual separation of the cell wall, vacuole, and cytosolic compartments. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry showed the presence of isotopic borate complexes, at mass-to-charge ratio of 690.22/691.22 in the canola and wheat phloem and at 300.11/301.11 in canola phloem and Chara cytoplasm. Using reference compounds, the borate complexes with mass-to-charge ratio 690.22/691.22 was identified as a bis-sucrose (Suc) borate complex in which the 4,6-hydroxyl pairs from the two α-glucopyranoside moieties formed an [L2B]−1 complex. Further investigation using liquid chromatography electrospray ionization triple quadrupole mass spectrometry analysis confirmed the presence of the bis-Suc borate complex in wheat phloem with a concentration up to 220 μm. The 300.11/301.11 complex was putatively identified as a bis-N-acetyl-serine borate complex but its concentration was below the detection limits of the liquid chromatography electrospray ionization triple quadrupole mass spectrometer so could not be quantified. The presence of borate complexes in the phloem provides a mechanistic explanation for the observed phloem boron mobility in canola and wheat and other species that transport Suc as their primary photoassimilate. PMID:20413647

Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation

NASA Technical Reports Server (NTRS)

Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

2010-01-01

Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis.

Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl: Interesting size effects originated from the tetrahedral anions

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

Pan, Ming-Yan; Xia, Sheng-Qing, E-mail: shqxia@sdu.edu.cn; Liu, Xiao-Cun

2014-11-15

Two new barium chalcogenides, Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl, were synthesized by using high temperature solid-state reactions and their structures were determined by single-crystal X-ray diffraction technique. Despite the similar chemical formula, the structures of Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl are subtly different due to the size effects originated from the tetrahedral anions. Ba{sub 3}GeS{sub 5} crystallizes in the orthorhombic space group Pnma (no. 62) with cell parameters of a=12.0528(9) Å, b=9.5497(7) Å and c=8.5979(6) Å, while Ba{sub 3}InS{sub 4}Cl adopts a different tetragonal system (space group: I4/mcm, no. 140, a=b=8.3613(6) Å, c=14.3806(18) Å). The measuredmore » optical band gap of Ba{sub 3}GeS{sub 5} is 3.0 eV, a little smaller than the value of 3.42 eV in Ba{sub 3}InS{sub 4}Cl. Theoretical calculations by Wien2k are provided as well in order to better understand these results. - Graphical abstract: The polyhedral structure view for Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl in which Ba, S and Cl atoms are plotted in purple, red and green spheres. - Highlights: • Two new barium chalcogenides, Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl, were synthesized from the BaCl{sub 2}-flux reactions. • Their crystal structures feature discrete [MS{sub 4}] tetrahedra which embody interesting size effects. • Both compounds exhibit a band gap around 3.0 eV. • They are thermally stable up to 1073 K.« less

Synthesis and Characterization of Polyether Adducts of Barium and Strontium Carboxylates and Their Use in the Formation of MTiO(3) Films.

PubMed

Wojtczak, William A.; Atanassova, Paolina; Hampden-Smith, Mark J.; Duesler, Eileen

1996-11-20

The synthesis, characterization, and reactivity of new polyether adducts of strontium and barium carboxylates of general composition M(O(2)CCF(3))(n)()(L) (M = Ba, L = 15-crown-5, (1); M = Ba (2), Sr (3), respectively, with L = tetraglyme are reported. The compounds were synthesized by reaction of BaCO(3) or MH(2) (M = Sr or Ba) with organic acids in the presence of the polyether ligands. These compounds have been characterized by IR and (13)C and (1)H NMR spectroscopies, elemental analyses, and thermogravimetric analysis. The species Ba(2)(O(2)CCF(3))(4)(15-crown-5)(2) (1) and [Ba(2)(O(2)CCF(3))(4)(tetraglyme)](infinity) (2), were also characterized by single-crystal X-ray diffraction. Ba(2)(O(2)CCF(3))(4)(15-crown-5)(2) (1) crystallizes in the orthorhombic space group Cccm with cell dimensions of a = 13.949(1) Å, b = 19.376(2) Å, c = 16.029(1) Å, and Z = 8. [Ba(2)(O(2)CCF(3))(4)(tetraglyme)](infinity) (2) crystallizes in the monoclinic space group C2/c with cell dimensions of a = 12.8673(12) Å, b = 16.6981(13) Å, c = 15.1191(12) Å, beta = 99.049(8) degrees, and Z = 4. Compounds 1-3 thermally decompose at high temperatures in the solid state to give MF(2). However, solutions of compounds 1-3 dissolved in ethanol with Ti(O-i-Pr)(4) give crystalline perovskite phase MTiO(3) films, or in the case of mixtures of 2 and 3, Ba(1)(-)(x)()Sr(x)()TiO(3) films below 600 degrees C when spin coated onto silicon substrates and thermally treated. The crystallinity, purity, and elemental composition of the films was determined by glancing angle X-ray diffraction and Auger electron spectroscopy.

Precursor dynamics in the ferroelectric phase transition of barium titanate single crystals studied by Brillouin light scattering

NASA Astrophysics Data System (ADS)

Ko, Jae-Hyeon; Kim, Tae Hyun; Roleder, K.; Rytz, D.; Kojima, Seiji

2011-09-01

The acoustic anomalies and precursor dynamics of high-quality barium titanate single crystals were investigated by Brillouin light scattering and the birefringence measurements in the paraelectric phase above the cubic-to-tetragonal ferroelectric phase transition temperature (Tc). Two elastic stiffness coefficients C11 and C44, the related sound velocities, and their absorption coefficients were determined from Tc to 400∘C for the first time. The longitudinal acoustic (LA) mode showed a substantial softening over a wide temperature range above Tc which was accompanied by a remarkable increase in the acoustic damping as well as growth of central peaks. The broad central peak (CP) exhibited a two-mode and one-mode behavior in the paraelectric and ferroelectric phase, respectively, which was consistent with recent far-infrared reflectivity measurements and first-principle-based calculations [Ponomareva , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.77.012102 77, 012102 (2008)]. The acoustic anomalies and CP behavior were correlated with the anomalous birefringence, piezoelectric effect, and the deviation of the Curie-Weiss law observed from the same crystal. This strongly indicates similarity between the dynamics of polar clusters in typical ferroelectrics and the dynamics of polar nanoregions in relaxors, consistent with recent acoustic emission measurements [Dul’kin , Appl. Phys. Lett.APPLAB0003-695110.1063/1.3464968 97, 032903 (2010)]. The relaxation times estimated from the central peak and the LA mode anomalies exhibited similar temperature dependences with comparable orders of magnitude, indicating that the polarization fluctuations due to the precursor polar clusters couples to the LA mode through density fluctuations. All these anomalies share common microscopic origin, correlated Ti off-centered motions forming polar clusters having local symmetry breaking in the paraelectric phase. The existence of the polar clusters were directly evidenced by the temperature evolution of the precise birefringence map. The narrow central peak within ±5 GHz proposed before was not confirmed to exist in the present study.

Geochemical characteristics of The Emet (Espey-Hisarcik) borate deposits, Kütahya, Turkey

NASA Astrophysics Data System (ADS)

Koçak, İ.; Koç, Ş.

2018-06-01

Nearly 72% world's borate reserves are in western part of Turkey. The Emet (Kütahya) deposit is one of these deposits. The Emet borate deposit, like other deposits in western Anatolia, was deposited in Miocene lacustrine environment whose formation coincides with volcanic activity started in Paleogene and lasted to the beginning of Quaternary. The borate ore displaying lenticular structure is alternated with claystone, marl, tuff and thin bedded limestone. The mineral paragenesis is composed of colemanite, hydroboracite, Veatchite, dolomite, calcite, montmorillonite and illite. The Emet borate deposit has been the subject of various geologic and mineralogical studies. In the present study major and trace element contents of 60 borate samples from this deposit are discussed. Among the trace elements, significant enrichment was found in As, Se, Sr, Cs, Sb and Li. Element correlations indicate volcanic source for boron (exhalations and hydrothermal solutions) whilst other elements are found to be derived from a terrestrial source. According to REE data, high Ce concentrations and anomalies are generally indicative of oxygenated depositional environment whilst low Ce contents facilitated the lake waters to be low oxygenated as a result of H2S-rich hydrothermal solutions. The weak negative anomaly detected only in the Hisarcık region is attributed to lacking of Eu contribution to the lake due to insufficient alteration on the continent.

Human γ-Glutamyl Transpeptidase 1: STRUCTURES OF THE FREE ENZYME, INHIBITOR-BOUND TETRAHEDRAL TRANSITION STATES, AND GLUTAMATE-BOUND ENZYME REVEAL NOVEL MOVEMENT WITHIN THE ACTIVE SITE DURING CATALYSIS.

PubMed

Terzyan, Simon S; Burgett, Anthony W G; Heroux, Annie; Smith, Clyde A; Mooers, Blaine H M; Hanigan, Marie H

2015-07-10

γ-Glutamyl transpeptidase 1 (GGT1) is a cell surface, N-terminal nucleophile hydrolase that cleaves glutathione and other γ-glutamyl compounds. GGT1 expression is essential in cysteine homeostasis, and its induction has been implicated in the pathology of asthma, reperfusion injury, and cancer. In this study, we report four new crystal structures of human GGT1 (hGGT1) that show conformational changes within the active site as the enzyme progresses from the free enzyme to inhibitor-bound tetrahedral transition states and finally to the glutamate-bound structure prior to the release of this final product of the reaction. The structure of the apoenzyme shows flexibility within the active site. The serine-borate-bound hGGT1 crystal structure demonstrates that serine-borate occupies the active site of the enzyme, resulting in an enzyme-inhibitor complex that replicates the enzyme's tetrahedral intermediate/transition state. The structure of GGsTop-bound hGGT1 reveals its interactions with the enzyme and why neutral phosphonate diesters are more potent inhibitors than monoanionic phosphonates. These structures are the first structures for any eukaryotic GGT that include a molecule in the active site covalently bound to the catalytic Thr-381. The glutamate-bound structure shows the conformation of the enzyme prior to release of the final product and reveals novel information regarding the displacement of the main chain atoms that form the oxyanion hole and movement of the lid loop region when the active site is occupied. These data provide new insights into the mechanism of hGGT1-catalyzed reactions and will be invaluable in the development of new classes of hGGT1 inhibitors for therapeutic use. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Human γ-glutamyl transpeptidase 1: Structures of the free enzyme, inhibitor-bound tetrahedral transition states, and glutamate-bound enzyme reveal novel movement within the active site during catalysis [Human gamma-glutamyl transpeptidase: Inhibitor binding and movement within the active site

DOE PAGES

Terzyan, Simon S.; Burgett, Anthony W. G.; Heroux, Annie; ...

2015-05-26

γ-Glutamyl transpeptidase 1 (GGT1) is a cell surface, N-terminal nucleophile hydrolase that cleaves glutathione and other γ-glutamyl compounds. GGT1 expression is essential in cysteine homeostasis, and its induction has been implicated in the pathology of asthma, reperfusion injury, and cancer. In this study, we report four new crystal structures of human GGT1 (hGGT1) that show conformational changes within the active site as the enzyme progresses from the free enzyme to inhibitor-bound tetrahedral transition states and finally to the glutamate-bound structure prior to the release of this final product of the reaction. The structure of the apoenzyme shows flexibility within themore » active site. The serine-borate-bound hGGT1 crystal structure demonstrates that serine-borate occupies the active site of the enzyme, resulting in an enzyme-inhibitor complex that replicates the enzyme's tetrahedral intermediate/transition state. The structure of GGsTop-bound hGGT1 reveals its interactions with the enzyme and why neutral phosphonate diesters are more potent inhibitors than monoanionic phosphonates. These structures are the first structures for any eukaryotic GGT that include a molecule in the active site covalently bound to the catalytic Thr-381. The glutamate-bound structure shows the conformation of the enzyme prior to release of the final product and reveals novel information regarding the displacement of the main chain atoms that form the oxyanion hole and movement of the lid loop region when the active site is occupied. Lastly,tThese data provide new insights into the mechanism of hGGT1-catalyzed reactions and will be invaluable in the development of new classes of hGGT1 inhibitors for therapeutic use.« less

Human γ-glutamyl transpeptidase 1: Structures of the free enzyme, inhibitor-bound tetrahedral transition states, and glutamate-bound enzyme reveal novel movement within the active site during catalysis [Human gamma-glutamyl transpeptidase: Inhibitor binding and movement within the active site

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

Terzyan, Simon S.; Burgett, Anthony W. G.; Heroux, Annie

γ-Glutamyl transpeptidase 1 (GGT1) is a cell surface, N-terminal nucleophile hydrolase that cleaves glutathione and other γ-glutamyl compounds. GGT1 expression is essential in cysteine homeostasis, and its induction has been implicated in the pathology of asthma, reperfusion injury, and cancer. In this study, we report four new crystal structures of human GGT1 (hGGT1) that show conformational changes within the active site as the enzyme progresses from the free enzyme to inhibitor-bound tetrahedral transition states and finally to the glutamate-bound structure prior to the release of this final product of the reaction. The structure of the apoenzyme shows flexibility within themore » active site. The serine-borate-bound hGGT1 crystal structure demonstrates that serine-borate occupies the active site of the enzyme, resulting in an enzyme-inhibitor complex that replicates the enzyme's tetrahedral intermediate/transition state. The structure of GGsTop-bound hGGT1 reveals its interactions with the enzyme and why neutral phosphonate diesters are more potent inhibitors than monoanionic phosphonates. These structures are the first structures for any eukaryotic GGT that include a molecule in the active site covalently bound to the catalytic Thr-381. The glutamate-bound structure shows the conformation of the enzyme prior to release of the final product and reveals novel information regarding the displacement of the main chain atoms that form the oxyanion hole and movement of the lid loop region when the active site is occupied. Lastly,tThese data provide new insights into the mechanism of hGGT1-catalyzed reactions and will be invaluable in the development of new classes of hGGT1 inhibitors for therapeutic use.« less

Strontium borate glass: potential biomaterial for bone regeneration

PubMed Central

Pan, H. B.; Zhao, X. L.; Zhang, X.; Zhang, K. B.; Li, L. C.; Li, Z. Y.; Lam, W. M.; Lu, W. W.; Wang, D. P.; Huang, W. H.; Lin, K. L.; Chang, J.

2010-01-01

Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones. PMID:20031984

Is Boron a Prebiotic Element? A Mini-review of the Essentiality of Boron for the Appearance of Life on Earth

NASA Astrophysics Data System (ADS)

Scorei, Romulus

2012-02-01

Boron is probably a prebiotic element with special importance in the so-called "sugars world". Boron is not present on Earth in its elemental form. It is found only in compounds, e.g., borax, boric acid, kernite, ulexite, colemanite and other borates. Volcanic spring waters sometimes contain boron-based acids (e.g., boric, metaboric, tetraboric and pyroboric acid). Borates influence the formation of ribofuranose from formaldehyde that feeds the "prebiotic metabolic cycle". The importance of boron in the living world is strongly related to its implications in the prebiotic origins of genetic material; consequently, we believe that throughout the evolution of life, the primary role of boron has been to provide thermal and chemical stability in hostile environments. The complexation of boric acid and borates with organic cis-diols remains the most probable chemical mechanism for the role of this element in the evolution of the living world. Because borates can stabilize ribose and form borate ester nucleotides, boron may have provided an essential contribution to the "pre-RNA world".

Synthesis and characterization of cerium- and gallium-containing borate bioactive glass scaffolds for bone tissue engineering.

PubMed

Deliormanlı, Aylin M

2015-02-01

Bioactive glasses are widely used in biomedical applications due to their ability to bond to bone and even to soft tissues. In this study, borate based (13-93B3) bioactive glass powders containing up to 5 wt% Ce2O3 and Ga2O3 were prepared by the melt quench technique. Cerium (Ce+3) and gallium (Ga+3) were chosen because of their low toxicity associated with bacteriostatic properties. Bioactive glass scaffolds were fabricated using the polymer foam replication method. In vitro degradation and bioactivity of the scaffolds were evaluated in SBF under static conditions. Results revealed that the cerium- and gallium-containing borate glasses have much lower degradation rates compared to the bare borate glass 13-93B3. In spite of the increased chemical durability, substituted glasses exhibited a good in vitro bioactive response except when the Ce2O3 content was 5 wt%. Taking into account the high in vitro hydroxyapatite forming ability, borate glass scaffolds containing Ce+3 and Ga+3 therapeutic ions are promising candidates for bone tissue engineering applications.

Thermoluminescence response of rare earth activated zinc lithium borate glass

NASA Astrophysics Data System (ADS)

Saidu, A.; Wagiran, H.; Saeed, M. A.; Obayes, H. K.; Bala, A.; Usman, F.

2018-03-01

New glasses of zinc lithium borate doped with terbium oxide were synthesized by high temperature solid-state reaction. The amorphous nature of the glasses was confirmed using x-ray diffraction analysis (XRD). Thermoluminescence (TL) response of pure zinc lithium borate (ZLB) and zinc lithium borate doped with terbium (ZLB: Tb) exposed to gamma radiation was measured and compared. There is significant enhancement in the TL yields of ZLB: Tb compared to that of pure ZLB. Effect of varying concentration of dopant (Tb4O7) on the TL response of zinc lithium borate was investigated. 0.3 mol% concentration of Tb exhibited strongest TL intensity. Thermoluminescence curve of the phosphor consist of single isolated peak. The TL response of the new materials to the exposed radiation is linear within 0.5-100 Gy range of dose with sublinearity at the lower region of the curve. High sensitivity was exhibited by the new amorphous materials. Reproducibility, thermal fading and energy response of the proposed TLD were investigated and shows remarkable result that made the phosphor suitable for radiation dosimetry.

Strontium borate glass: potential biomaterial for bone regeneration.

PubMed

Pan, H B; Zhao, X L; Zhang, X; Zhang, K B; Li, L C; Li, Z Y; Lam, W M; Lu, W W; Wang, D P; Huang, W H; Lin, K L; Chang, J

2010-07-06

Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones.

Secondary relaxations in supercooled and glassy sucrose-borate aqueous solutions.

PubMed

Longinotti, M Paula; Corti, Horacio R; Pablo, Juan J de

2008-10-13

The dielectric relaxation spectra of concentrated aqueous solutions of sucrose-borate mixtures have been measured in the supercooled and glassy regions in the frequency range of 40Hz to 2MHz. The secondary (beta) relaxation process was analyzed in the temperature range 183-233K at water contents between 20 and 30wt%. The relaxation times were obtained, and the activation energy of that process was calculated. In order to assess the effect of borate on the relaxation of disaccharide-water mixtures, we also studied the dielectric behavior of sucrose aqueous solutions in the same range of temperatures and water contents. Our findings support the view that, beyond a water content of approximately 20wt%, the secondary relaxation of water-sucrose and water-sucrose-borate mixtures adopts a universal character that can be explained in terms of a simple exponential function of the temperature scaled by the glass transition temperature (T(g)). The behavior observed for water-sucrose and water-sucrose-borate mixtures is compared with previous results obtained in other water-carbohydrate systems.

Mechanism of Phase Formation in the Batch Mixtures for Slag-Bearing Glass Ceramics - 12207

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

Stefanovsky, Sergey V.; Stefanovsky, Olga I.; Malinina, Galina A.

2012-07-01

Slag surrogate was produced from chemicals by heating to 900 deg. C and keeping at this temperature for 1 hr. The product obtained was intermixed with either sodium di-silicate (75 wt.% waste loading) or borax (85 wt.% slag loading). The mixtures were heat-treated within a temperature range of 25 to 1300 deg. C. The products were examined by X-ray diffraction and infrared spectroscopy. The products prepared at temperatures of up to 1000 deg. C contained both phase typical of the source slag and intermediate phases as well as phases typical of the materials melted at 1350 deg. C such asmore » nepheline, britholite, magnetite and matrix vitreous phase. Vitrification process in batch mixtures consisting of slag surrogate and either sodium di-silicate or sodium tetraborate runs through formation of intermediate phases mainly silico-phosphates capable to incorporate Sm as trivalent actinides surrogate. Reactions in the batch mixtures are in the whole completed by ∼1000 deg. C but higher temperatures are required to homogenize the products. If in the borate-based system the mechanism is close to simple dissolution of slag constituents in the low viscous borate melt, then in the silicate-based system the mechanism was found to be much complicated and includes re-crystallization during melting with segregation of newly-formed nepheline type phase. (authors)« less

Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

NASA Astrophysics Data System (ADS)

Melo, B. M. G.; Graça, M. P. F.; Prezas, P. R.; Valente, M. A.; Almeida, A. F.; Freire, F. N. A.; Bih, L.

2016-08-01

In this work, phosphate-borate based glasses with molar composition 20.7P2O5-17.2Nb2O5-13.8WO3-34.5A2O-13.8B2O3, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σac and σdc, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz-1 MHz.

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

Li, H.K.; Science Center for Phase Diagram and Materials Design and Manufacture, Central South University, Changsha, Hunan 410083; Cai, G.M., E-mail: caigemei@csu.edu.cn

Two novel borate compounds MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8}, have been synthesized via solid-state reactions, and their crystal structures have been solved and refined from powder X-ray diffraction data. The compound MgInBO{sub 4}, which was obtained at 1190 °C, belongs to the warwickite family. It crystallizes in the Pnma space group (no. 62) with a=9.5443(1) Å, b=3.2771(1) Å, c=9.5228(1) Å, and Z=4. The fundamental building units are liner –Mg(In)O{sub 6}–[In(Mg)]{sub 2}O{sub 10}–Mg(In)O{sub 6}– chains and isolated BO{sub 3} triangles. The low-temperature phase, MgIn{sub 7/8}B{sub 7/8}O{sub 29/8}, whose crystal structure is solved ab initio by the charge-flipping method withmore » standard chemical formula MgInBO{sub 4}, was prepared at 1080 °C. It crystallizes in the P12{sub 1}/n1 space group (no. 14) with a=17.0976(1) Å, b=3.2504(1) Å, c=5.3387(1) Å, β=96.0829(3)°, and Z=4. The structure of MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} contains [In(2)/Mg(2)]{sub 2}O{sub 10} groups, –MgO{sub 6}–InO{sub 6}– infinite ribbons and isolated BO{sub 3} triangles. The experiments and the differential thermal analysis (DTA) show the decompositions of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} happen at about 1220 °C and 1180 °C, respectively. The comparative crystal chemistry from MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} to MgInBO{sub 4} has been discussed. Infrared spectra and UV–vis diffuse reflectance spectra of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} were measured. - Graphical abstract: The structural transformation from the monoclinic MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} (P12{sub 1}/n1) to the orthorhombic MgInBO{sub 4} (Pnma). - Highlights: • Two novel borate compounds MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} have been synthesized via solid-state reactions for the first time. • The crystal structures of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} have been solved and refined from powder X-ray diffraction data. • The possible crystal chemical analysis from MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} to MgInBO{sub 4} is discussed. • Infrared spectra and UV–vis diffuse reflectance spectra of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} have been measured.« less

Mössbauer study and magnetic properties of MgFe2O4 crystallized from the glass system B2O3/K2O/P2O5/MgO/Fe2O3

NASA Astrophysics Data System (ADS)

Shabrawy, S. El; Bocker, C.; Miglierini, M.; Schaaf, P.; Tzankov, D.; Georgieva, M.; Harizanova, R.; Rüssel, C.

2017-01-01

An iron containing magnesium borate glass with the mol% composition 51.7 B2O3/9.3 K2O /1 P2O5/27.6MgO/10.4Fe2O3was prepared by the conventional melts quenching method followed by a thermal treatment process at temperatures in the range from 530 to 604 °C.The thermally treated samples were characterized by X-ray diffraction, scanning and transmission electron microscopy. It was shown that superparamagnetic MgFe2O4 nanoparticles were formed during thermal treatment. The size of the spinel type crystals was in the range from 6 to 15 nm. Mössbauer spectra of the powdered glass ceramic samples and the extracted nanoparticles after dissolving the glass matrix in diluted acid were recorded at room temperature. The deconvolution of the spectra revealed the crystallization of two spinel phases MgFe2O4 (as a dominant phase) and superparamagnetic maghemite, γ-Fe2O3 (as a secondary phase). Room temperature magnetic measurements showed that, increasing the crystallization temperature changed the superparamagnetic behavior of the samples to ferrimagnetic behavior. The Curie temperatures of the samples were measured and showed a higher value than that of the pure bulk MgFe2O4.

Barium isotope fractionation during the experimental transformation of aragonite to witherite and of gypsum to barite, and the effect of ion (de)solvation.

PubMed

Böttcher, Michael E; Neubert, Nadja; von Allmen, Katja; Samankassou, Elias; Nägler, Thomas F

2018-06-01

In this study, we present the experimental results for stable barium (Ba) isotope fractionation ( 137 Ba/ 134 Ba) during the transformation of aragonite (CaCO 3 ) and gypsum (CaSO 4 ·2H 2 O) in Ba-bearing aqueous solution to witherite (BaCO 3 ) and barite (BaSO 4 ), respectively. The process was studied at three temperatures between 4 and 60 °C. In all cases, the transformation leads to a relative enrichment of the lighter 134 Ba isotope in the solid compared to the aqueous solution, with 137/134 Ba enrichment factors between -0.11 and -0.17 ‰ for BaCO 3 , and -0.21 and -0.26 ‰ for BaSO 4 . The corresponding mass-dependent 138/134 Ba enrichment factors are -0.15 to -0.23 ‰ for BaCO 3 , and -0.28 to -0.35 ‰ for BaSO 4 . The magnitude of isotope fractionation is within the range of recent reports for witherite and barite formation, as well as trace Ba incorporation into orthorhombic aragonite, and no substantial impact of temperature can be found between 4 and 80 °C. In previous studies, ion (de)solvation has been suggested to impact both the crystallization process of Ba-bearing solids and associated Ba isotope fractionation. Precipitation experiments of BaSO 4 and BaCO 3 using an methanol-containing aqueous solution indicate only a minor effect of ion and crystal surface (de)solvation on the overall Ba isotope fractionation process.

Methods of producing cesium-131

DOEpatents

Meikrantz, David H; Snyder, John R

2012-09-18

Methods of producing cesium-131. The method comprises dissolving at least one non-irradiated barium source in water or a nitric acid solution to produce a barium target solution. The barium target solution is irradiated with neutron radiation to produce cesium-131, which is removed from the barium target solution. The cesium-131 is complexed with a calixarene compound to separate the cesium-131 from the barium target solution. A liquid:liquid extraction device or extraction column is used to separate the cesium-131 from the barium target solution.

Structural and Luminescent property of Holmium doped Borate Glasses

NASA Astrophysics Data System (ADS)

Usharani, V. L.; Eraiah, B.

2018-02-01

Holmium doped Lithium Lead Borate glasses of different compositions were prepared by melt quenching technique. Fourier transform infrared investigations on lithium lead borate glasses have been made to study the local order and vibrations of atoms in the glass network and it contains mainly BO3 and BO4 structural units. Photoluminescence techniques were employed to investigate the luminescent property of these glasses excited at 451nm. Blue emission have been observed from the transition 495 (5F3 → 5I8).

Mineral resource of the month: boron

USGS Publications Warehouse

Crangle, Robert D.

2012-01-01

The article offers information on the mineral, boron. Boron compounds, particularly borates, have more commercial applications than its elemental relative which is a metalloid. Making up the 90% of the borates that are used worldwide are colemanite, kernite, tincal, and ulexite. The main borate deposits are located in the Mojave Desert of the U.S., the Tethyan belt in southern Asia, and the Andean belt of South America. Underground and surface mining are being used in gathering boron compounds. INSETS: Fun facts;Boron production and consumption.

Thermal property of holmium doped lithium lead borate glasses

NASA Astrophysics Data System (ADS)

Usharani, V. L.; Eraiah, B.

2018-04-01

The new glass system of holmium doped lithium lead borate glasses were prepared by conventional melt quenching technique. The thermal stability of the different compositions of Ho3+ ions doped lithium lead borate glasses were studied by using TG-DTA. The Tg values are ranging from 439 to 444 °C with respect to the holmium concentration. Physical parameters like polaron radius(rp), inter-nuclear distance (ri), field strength (F) and polarizability (αm) of oxide ions were calculated using appropriate formulae.

Analysis of magnetite crystals and inclusion bodies inside magnetotactic bacteria from different environmental locations

NASA Astrophysics Data System (ADS)

Oestreicher, Z.; Lower, B.; Lower, S.; Bazylinski, D. A.

2011-12-01

Biomineralization occurs throughout the living world; a few common examples include iron oxide in chiton teeth, calcium carbonate in mollusk shells, calcium phosphate in animal bones and teeth, silica in diatom shells, and magnetite crystals inside the cells of magnetotactic bacteria. Biologically controlled mineralization is characterized by biominerals that have species-specific properties such as: preferential crystallographic orientation, consistent particle size, highly ordered spatial locations, and well-defined composition and structure. It is well known that magnetotactic bacteria synthesize crystals of magnetite inside of their cells, but how they mineralize the magnetite is poorly understood. Magnetosomes have a species-specific morphology that is due to specific proteins involved in the mineralization process. In addition to magnetite crystals, magnetotactic bacteria also produce inclusion bodies or granules that contain different elements, such as phosphorus, calcium, and sulfur. In this study we used the transmission electron microscope to analyze the structure of magnetite crystals and inclusion bodies from different species of magnetotactic bacteria in order to determine the composition of the inclusion bodies and to ascertain whether or not the magnetite crystals contain elements other than iron and oxygen. Using energy dispersive spectroscopy we found that different bacteria from different environments possess inclusion bodies that contain different elements such as phosphorus, calcium, barium, magnesium, and sulfur. These differences may reflect the conditions of the environment in which the bacteria inhabit.

Lactic acid bacterial extract as a biogenic mineral growth modifier

NASA Astrophysics Data System (ADS)

Borah, Ballav M.; Singh, Atul K.; Ramesh, Aiyagari; Das, Gopal

2009-04-01

The formation of minerals and mechanisms by which bacteria could control their formation in natural habitats is now of current interest for material scientists to have an insight of the mechanism of in vivo mineralization, as well as to seek industrial and technological applications. Crystalline uniform structures of calcium and barium minerals formed micron-sized building blocks when synthesized in the presence of an organic matrix consisting of secreted protein extracts from three different lactic acid bacteria (LAB) viz.: Lactobacillus plantarum MTCC 1325, Lactobacillus acidophilus NRRL B4495 and Pediococcus acidilactici CFR K7. LABs are not known to form organic matrix in biological materialization processes. The influence of these bacterial extracts on the crystallization behavior was investigated in details to test the basic coordination behavior of the acidic protein. In this report, varied architecture of the mineral crystals obtained in presence of high molecular weight protein extracts of three different LAB strains has been discussed. The role of native form of high molecular weight bacterial protein extracts in the generation of nucleation centers for crystal growth was clearly established. A model for the formation of organic matrix-cation complex and the subsequent events leading to crystal growth is proposed.

Evolution of borate minerals from contact metamorphic to hydrothermal stages: Ludwigite-group minerals and szaibélyite from the Vysoká - Zlatno skarn, Slovakia

NASA Astrophysics Data System (ADS)

Bilohuščin, Vladimír; Uher, Pavel; Koděra, Peter; Milovská, Stanislava; Mikuš, Tomáš; Bačík, Peter

2017-09-01

Borate minerals of the ludwigite group (LGM) and szaibélyite in association with hydroxylclinohumite, clinochlore, a serpentine mineral, magnesian magnetite, spinel, magnesite, dolomite and sulphide minerals, occur in a magnesian exoskarn in the R-20 borehole located in the Vysoká - Zlatno Cu-Au porphyry-skarn deposit, located within the Štiavnica Neogene stratovolcano, Western Carpathians, central Slovakia. The skarn is developed along the contact of Miocene granodiorite to quartz-diorite porphyry and a Middle-Upper Triassic dolomite-shale-psammite-anhydrite sedimentary sequence. The boron minerals were investigated by electron probe micro-analyser (EPMA) and micro-Raman techniques. The source of boron could have been from the granodiorite/quartz diorite intrusion; however some supply of B from adjacent evaporite-bearing sediments is also possible. Based on textural and compositional data, the minerals originated during two stages. (1) An early high-temperature, contact-metamorphic and metasomatic stage comprises coarse-crystalline aggregate of LGM (types 1 to 3) in association with hydroxylclinohumite, magnetite, and rarely spinel inclusions in LGM. Compositional variations of LGM show a crystallization sequence from early azoproite [≤17 wt% TiO2; 0.40 atoms pre formula unit (apfu) Ti, which correspond to ≤79 mol% of the Mg2(Mg0.5Ti0.5)O2(BO3) end-member], Ti-Al-rich members of LGM, "aluminoludwigite "[≤14 wt% Al2O3; ≤0.53 apfu, ≤53 mol% of Mg2AlO2(BO3) end-member] and Al-rich ludwigite in the central zone of crystals, to Ti-Al-poor ludwigite in outer parts of crystals. (2) Minerals of the late retrograde serpentinization and hydrothermal stage form irregular veinlets and aggregates, including partial alteration of hydroxylclinohumite to the serpentine-group mineral and clinochlore, replacement of LGM by szaibélyite, formation of the latest generation of Fe-rich, Ti-Al poor ludwigite in veinlets (type 4), and precipitation of dolomite, magnesite and sulphide minerals (valleriite, sphalerite, chalcopyrite). The distinct compositional zoning of the LGM documents a complex evolution of the skarn beginning with a high-temperature stage 1 and ending with a low-temperature overprint, stage 2.

Thermally reversible gels in electrophoresis. I - Matrix characterization

NASA Technical Reports Server (NTRS)

Righetti, Pier Giorgio; Snyder, Robert S.

1988-01-01

Two series of thermally reversible hydrogen-bonded gels have been characterized: (5 pct) PVA-(4 pct) PEG and (5 pct) PVA-(0.04 pct) borate gels. They both have extremely low melting points (16-17 C) and could be of potential interest for recovery of proteins after preparative electrophoresis. The PVA-borate gels can be exploited in the pH range 7-11 by progressively increasing the borate content in the pH interval 8 to 7 and concomitantly decreasing the borate levels in the pH zone 8 to 11. It is hypothesized that the low melting point of these gels is due to the fact that they are sparingly and sparsely hydrogen bonded along the PVA chain: on the average, 1 OH group out of 3 or 4 OH groups in the PVA polymer should be engaged in H-bond formation.

Exposure to low-dose barium by drinking water causes hearing loss in mice.

PubMed

Ohgami, Nobutaka; Hori, Sohjiro; Ohgami, Kyoko; Tamura, Haruka; Tsuzuki, Toyonori; Ohnuma, Shoko; Kato, Masashi

2012-10-01

We continuously ingest barium as a general element by drinking water and foods in our daily life. Exposure to high-dose barium (>100mg/kg/day) has been shown to cause physiological impairments. Direct administration of barium to inner ears by vascular perfusion has been shown to cause physiological impairments in inner ears. However, the toxic influence of oral exposure to low-dose barium on hearing levels has not been clarified in vivo. We analyzed the toxic influence of oral exposure to low-dose barium on hearing levels and inner ears in mice. We orally administered barium at low doses of 0.14 and 1.4 mg/kg/day to wild-type ICR mice by drinking water. The doses are equivalent to and 10-fold higher than the limit level (0.7 mg/l) of WHO health-based guidelines for drinking water, respectively. After 2-week exposure, hearing levels were measured by auditory brain stem responses and inner ears were morphologically analyzed. After 2-month exposure, tissue distribution of barium was measured by inductively coupled plasma mass spectrometry. Low-dose barium in drinking water caused severe hearing loss in mice. Inner ears including inner and outer hair cells, stria vascularis and spiral ganglion neurons showed severe degeneration. The Barium-administered group showed significantly higher levels of barium in inner ears than those in the control group, while barium levels in bone did not show a significant difference between the two groups. Barium levels in other tissues including the cerebrum, cerebellum, heart, liver and kidney were undetectably low in both groups. Our results demonstrate for the first time that low-dose barium administered by drinking water specifically distributes to inner ears resulting in severe ototoxicity with degeneration of inner ears in mice. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of the adsorption of lithium and borate species on the zeta potential of particles of cobalt ferrite, nickel ferrite, and magnetite.

PubMed

Barale, M; Lefèvre, G; Carrette, F; Catalette, H; Fédoroff, M; Cote, G

2008-12-01

Zetametric measurements on suspensions of oxide particles (cobalt ferrite, nickel ferrite, and magnetite) representative of corrosion products from primary circuits of pressurized water reactors were performed at 25 and 70 degrees C in the presence of lithium and borate species. No effect of lithium ions was observed. Borate species cause a decrease of the isoelectric point (IEP), attributed to the sorption of borate as a negative complex MOB(OH)3(-). A predictive model based on thermodynamic calculations (2-pK and diffuse layer models) of the surface acidity constants from the data of acid-base titrations combined with an empirical relationship between the surface potential Psi 0 and the zeta potential determined by zetametry was developed. A whole set of parameters valid at 25 degrees C, in a range of ionic strength between 10(-4) and 10(-2) molL(-1) and in a range of pH between 4 and 8, was determined for this model. Increase of temperature to 70 degrees C in the presence of borate results in a decrease of IEP for cobalt ferrite and an increase of the IEP for nickel ferrite.

Optical and physical properties of samarium doped lithium diborate glasses

NASA Astrophysics Data System (ADS)

Hanumantharaju, N.; Sardarpasha, K. R.; Gowda, V. C. Veeranna

2018-05-01

Sm3+ doped lithium di-borate glasses with composition 30Li2O-60B2O3-(10-x) PbO, (where 0 < x < 2 mole. %) were prepared by melt quenching method. The addition of modifier oxide to vitreous B2O3 modifies the glass network by converting three coordinated trigonal boron units (BO3) to weaker anionic four coordinated tetrahedral borons (BO4). The decrease in density and increase in molar volume with samarium ion content indicates the openness of the glass structure. The gradual increase in average separation of boron-boron atoms with VmB clearly indicates deterioration of borate glass network, which in turn leads to decrease in the oxygen packing density. The replacements of Sm2O3 for PbO depolymerise the chain structure and that would increase the concentration of non-bridging oxygens. The marginal increase of optical band gap energy after 1.0 mol.% of Sm2O3 is explained by considering the structural modification in lead-borate. The influence of Sm3+ ion on physical and optical properties in lithium-lead-borate glasses is investigated and the results were discussed in view of the structure of borate glass network.

Barium Depletion in Hollow Cathode Emitters

NASA Technical Reports Server (NTRS)

Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

2009-01-01

The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

Liquid-Phase Processing of Barium Titanate Thin Films

NASA Astrophysics Data System (ADS)

Harris, David Thomas

Processing of thin films introduces strict limits on the thermal budget due to substrate stability and thermal expansion mismatch stresses. Barium titanate serves as a model system for the difficulty in producing high quality thin films because of sensitivity to stress, scale, and crystal quality. Thermal budget restriction leads to reduced crystal quality, density, and grain growth, depressing ferroelectric and nonlinear dielectric properties. Processing of barium titanate is typically performed at temperatures hundreds of degrees above compatibility with metalized substrates. In particular integration with silicon and other low thermal expansion substrates is desirable for reductions in costs and wider availability of technologies. In bulk metal and ceramic systems, sintering behavior has been encouraged by the addition of a liquid forming second phase, improving kinetics and promoting densification and grain growth at lower temperatures. This approach is also widespread in the multilayer ceramic capacitor industry. However only limited exploration of flux processing with refractory thin films has been performed despite offering improved dielectric properties for barium titanate films at lower temperatures. This dissertation explores physical vapor deposition of barium titanate thin films with addition of liquid forming fluxes. Flux systems studied include BaO-B2O3, Bi2O3-BaB2O 4, BaO-V2O5, CuO-BaO-B2O3, and BaO-B2O3 modified by Al, Si, V, and Li. Additions of BaO-B2O3 leads to densification and an increase in average grain size from 50 nm to over 300 nm after annealing at 900 °C. The ability to tune permittivity of the material improved from 20% to 70%. Development of high quality films enables engineering of ferroelectric phase stability using residual thermal expansion mismatch in polycrystalline films. The observed shifts to TC match thermodynamic calculations, expected strain from the thermal expansion coefficients, as well as x-ray diffract measurements . Our system exhibits flux-film-substrate interactions that can lead to dramatic changes to the microstructure. This effect is especially pronounced onc -sapphire, with Al diffusion from the substrate leading to formation of an epitaxial BaAl2O4 second phase at the substrate-film interface. The formation of this second phase in the presence of a liquid phase seeds {111} twins that drive abnormal grain growth. The orientation of the sapphire substrate determines the BaAl2O 4 morphology, enabling control the abnormal grain growth behavior. CuO additions leads to significant grain growth at 900 °C, with average grain size approaching 500 nm. The orthorhombic-tetragonal phase transition is clearly observable in temperature dependent measurements and both linear and nonlinear dielectric properties are improved. All films containing CuO are susceptible to aging. A number of other systems were investigated for efficacy at temperatures below 900 °C. Pulsed laser deposition was used to study flux + BaTiO 3 targets, layered flux films, and in situ liquids. RF-magnetron sputtering using a dual-gun approach was used to explore integration on flexible foils with Ba1-xSrxTiO3. Many of these systems were based on the BaO-B2O3 system, which has proven effective in thin films, multilayer ceramic capacitors, and bulk ceramics. Modifiers allow tailoring of the microstructure at 900 °C, however no compositions were found, and no reports exist in the open literature, that provide significant grain growth or densification below 900 °C. Liquid phase fluxes offer a promising path forward for low temperature processing of barium titanate, with the ultimate goal of integration with metalized silicon substrates. This work demonstrates significant improvements to dielectric properties and the necessity of understanding interactions in the film-flux-substrate system.

Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

PubMed Central

García-Hernández, Margarita; García-Murillo, Antonieta; de J. Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

2009-01-01

Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3. PMID:19865533

Zirconocene mediated acetylboron chemistry.

PubMed

Jian, Zhongbao; Daniliuc, Constantin G; Kehr, Gerald; Erker, Gerhard

2018-05-31

The methyl zirconocene complex Cp*2Zr(Me)OMes reacts with H3C-B(C6F5)2 and CO to give the respective acetyl(methyl)borate Zr complex. Cp*2Zr(H)OMes reacts with H3C-B(C6F5)2 and CO to give the respective acetyl(hydrido)borate Zr product, admixed with a minor amount of the formyl(methyl)borate Zr complex isomer. Prolonged exposure to CO under close to ambient conditions results in the uptake of another CO equivalent to yield the corresponding borata-β-lactone zirconocene product.

The effects of borate minerals on the synthesis of nucleic acid bases, amino acids and biogenic carboxylic acids from formamide.

PubMed

Saladino, Raffaele; Barontini, Maurizio; Cossetti, Cristina; Di Mauro, Ernesto; Crestini, Claudia

2011-08-01

The thermal condensation of formamide in the presence of mineral borates is reported. The products afforded are precursors of nucleic acids, amino acids derivatives and carboxylic acids. The efficiency and the selectivity of the reaction was studied in relation to the elemental composition of the 18 minerals analyzed. The possibility of synthesizing at the same time building blocks of both genetic and metabolic apparatuses, along with the production of amino acids, highlights the interest of the formamide/borate system in prebiotic chemistry.

Hexagonal photonic crystal waveguide based on barium titanate thin films

NASA Astrophysics Data System (ADS)

Li, Jianheng; Liu, Zhifu; Wessels, Bruce W.; Tu, Yongming; Ho, Seng-Tiong; Joshi-Imre, Alexandra; Ocola, Leonidas E.

2011-03-01

The simulation, fabrication and measurement of nonlinear photonic crystals (PhCs) with hexagonal symmetry in epitaxial BaTiO3 were investigated. The optical transmission properties of a PhC were simulated by a 2-D finite-difference time domain (FDTD) method. A complete bandgap exists for both the TE and TM optical modes. The fabricated PhC has a well-defined stop band over the spectral region of 1525 to 1575 nm. A microcavity structure was also fabricated by incorporation of a line defect in the PhC. Transmission of the microcavity structure over the spectral region from 1456 to 1584nm shows a well-defined 5 nm wide window at 1495nm. Simulations indicate that the phase velocity matched PhC microcavity device of 0.5 mm long can potentially serve as modulator with a 3 dB bandwidth of 4 THz.

Status of barium studies in the present era of oncology: Are they a history?

PubMed

Mahajan, Abhishek; Desai, Subash; Sable, Nilesh Pandurang; Thakur, Meenakshi Haresh

2016-01-01

With the advent of the modern imaging technologies, the present era of oncology is seeing steady decline in requests for barium studies due to the many reasons. It is prudent to mention here, that, barium examinations cannot be made obsolete! Our aim to preserve the age old technique of barium studies not only to keep it going on but also for the betterment and appropriate management of the patient. Our goal is not to "save" barium studies simply to keep this technology alive, per se, but rather to preserve barium radiology for the quality in patient care.

Effect of barium-coated halloysite nanotube addition on the cytocompatibility, mechanical and contrast properties of poly(methyl methacrylate) cement.

PubMed

Jammalamadaka, Uday; Tappa, Karthik; Weisman, Jeffery A; Nicholson, James Connor; Mills, David K

2017-01-01

Halloysite nanotubes (HNTs) were investigated as a platform for tunable nanoparticle composition and enhanced opacity in poly(methyl methacrylate) (PMMA) bone cement. Halloysite has been widely used to increase the mechanical properties of various polymer matrices, in stark contrast to other fillers such as barium sulfate that provide opacity but also decrease mechanical strength. The present work describes a dry deposition method for successively fabricating barium sulfate nanoparticles onto the exterior surface of HNTs. A sintering process was used to coat the HNTs in barium sulfate. Barium sulfate-coated HNTs were then added to PMMA bone cement and the samples were tested for mechanical strength and tailored opacity correlated with the fabrication ratio and the amount of barium sulfate-coated HNTs added. The potential cytotoxic effect of barium-coated HNTs in PMMA cement was also tested on osteosarcoma cells. Barium-coated HNTs were found to be completely cytocompatible, and cell proliferation was not inhibited after exposure to the barium-coated HNTs embedded in PMMA cement. We demonstrate a simple method for the creation of barium-coated nanoparticles that imparted improved contrast and material properties to native PMMA. An easy and efficient method for coating clay nanotubes offers the potential for enhanced imaging by radiologists or orthopedic surgeons.

Chemical composition and mineralogy of borate from Rio Grande deposit, Uyuni (Bolivia) as raw materials for industrial applications

NASA Astrophysics Data System (ADS)

Guillen Vargas, Julio; Arancibia, Jony Roger Hans; Alfonso, Pura; Garcia-Valles, Maite; Parcerisa, David; Martinez, Salvador

2014-05-01

Bolivia has large tailings as a result of the historic and present-day Sn mining activity developed extensively in that country. Tailings produced in these mining activities have an appropriate composition to reprocess them and make silicate glass and glass-ceramics, obtaining the valorization of wastes and reducing the visual and chemical impact. Reprocessing the wastes to make glass and glass-ceramics prevents the leaching of heavy metals from those wastes because they are retained in the structure of the glass. Furthermore, an option to increase the economic value of these glasses is the introduction of boron and other additives to produce borosilicate glass. In this study a characterization of the Rio Grande borate deposit for its use in the manufacture of borosilicate glass is presented. Mineralogy was determined by X-ray diffraction (XRD), and Fourier transforms infrared spectroscopy (FTIR); textures were observed by scanning electron microscopy (SEM) and chemical composition was determined by inductively coupled plasma mass spectrometry (ICP-MS). The Rio Grande borate deposit is located in an area of about 50 km2 close to the south of the Salar of Uyuni, in the Río Grande de Lípez Delta. Borates occur in the contact between fluvio-deltaic and lacustrine sediments from water raising the surface by capillarity. The borates crop out in an extent area but towards the west they are covered by fluvio-deltaic sediments, which can be up to 2 m thick. These borates occur as lenses 50-100 m in diameter and layers up to 1 m thick. They usually form brittle nodules with a cotton-ball texture. Chemical composition of the Rio Grande borates is CaO, 11.82-13.83 wt%; Na2O, 13.50-19.35 wt%; K2O, 0.05- 1.04 wt%; MgO, 0.42-1.46 wt%; B2O3, 36.21-42.60 wt%; SiO2, up to 0.53 wt% and SO2, up to 0.60 wt%. Trace elements are low: Sr content is between 151-786 ppm, Al 12-676 ppm, Mn between 1-17 ppm, As 2-10 ppm and Fe between 9-376 ppm. The most abundant borate mineral in this deposit is ulexite (NaCaB5.5H20), halite can reach up to 17 wt% and gypsum up to 1.2 wt.%. Calcite occurs in minor contents. Ulexite exhibits a fibrous morphology with fibers oriented parallel each other. Purity of borates from the Rio Grande deposits makes them suitable for the most restrictive applications. Chemistry of these borates is in accordance with the necessary composition for obtaining borosilicate glasses. Acknowledgements: This work was partly financed by the project AECID: A3/042750/11, and the SGR 2009SGR-00444.

Crystallization of Sr0.5Ba0.5Nb2O6 Thin Films on LaNiO3 Electrodes by RF Magnetron Reactive Sputtering

NASA Astrophysics Data System (ADS)

Jong, Chao-An; Gan, Jon-Yiew

2000-02-01

Strontium barium niobium (Sr0.5Ba0.5Nb2O6) (SBN) thin films are prepared on conductive-oxide LNO (LaNiO3) electrodes by the rf magnetron sputtering system. Instead of conventional furnace annealing, SBN thin films are crystallized by rapid thermal annealing (RTA) above 700°C for 5 min. The textured SBN films are crystallized with two orientations: one is the (001) or (310) direction, and the other is the (002) or (620) direction. Films compositions measured by the electron spectroscopy of chemical analysis (ESCA) quantitative analysis method show nearly the same stoichiometric ratio as the target. The depth profiles of SBN films and the target are examined by secondary ion mass spectrometer (SIMS). The concentrations of the films are quite uniform. After being heat treated at 800°C for 5 min by RTA, La and Ni diffuse into the SBN film. The diffusion coefficient of La in SBN films is also calculated.

Epitaxial growth of 100-μm thick M-type hexaferrite crystals on wide bandgap semiconductor GaN/Al{sub 2}O{sub 3} substrates

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

Hu, Bolin; Su, Zhijuan; Bennett, Steve

2014-05-07

Thick barium hexaferrite BaFe{sub 12}O{sub 19} (BaM) films having thicknesses of ∼100 μm were epitaxially grown on GaN/Al{sub 2}O{sub 3} substrates from a molten-salt solution by vaporizing the solvent. X-ray diffraction measurement verified the growth of BaM (001) textured growth of thick films. Saturation magnetization, 4πM{sub s}, was measured for as-grown films to be 4.6 ± 0.2 kG and ferromagnetic resonance measurements revealed a microwave linewidth of ∼100 Oe at X-band. Scanning electron microscopy indicated clear hexagonal crystals distributed on the semiconductor substrate. These results demonstrate feasibility of growing M-type hexaferrite crystal films on wide bandgap semiconductor substrates by using a simplemore » powder melting method. It also presents a potential pathway for the integration of ferrite microwave passive devices with active semiconductor circuit elements creating system-on-a-wafer architectures.« less

The influence of the concentration of Sr ions on the crystal and magnetic structures of Ba{sub 2} –{sub x}Sr{sub x}FeMoO{sub 6} double perovskites (x = 0–1.6)

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

Turchenko, V. A., E-mail: turchenko@jinr.ru; Kalanda, N. A.; Kovalev, L. V.

2017-01-15

The crystal and magnetic structures of a solid solution of double perovskite Ba{sub 2–} {sub x}Sr{sub x}FeMoO{sub 6} (x = 0–1.6) have been investigated by neutron diffraction. The high-resolution diffraction patterns have provided precise information about the changes in the crystal and magnetic structures with an increase in the strontium content and data on the behavior of the sample microstructure. Replacement of barium with strontium leads to a change in the lattice symmetry from cubic (x = 0, sp. gr. Fm3̄m)) to tetragonal (x = 0.4, sp. gr. I4/m). At x = 1.0, the symmetry is either tetragonal (sp. gr.more » I4/m) or orthorhombic (sp. gr. Fmmm), and at x = 1.6 the symmetry becomes again tetragonal (sp. gr. I4/m). The values of the Curie temperature and microstrain increase with an increase in the strontium content.« less

Barium toxicosis in a dog.

PubMed

Adam, Fiona H; Noble, Peter J M; Swift, Simon T; Higgins, Brent M; Sieniawska, Christine E

2010-09-01

A 2-year-old 14.9-kg (32.8-lb) neutered female Shetland Sheepdog was admitted to the University of Liverpool Small Animal Teaching Hospital for evaluation of acute collapse. At admission, the dog was tachypneic and had reduced limb reflexes and muscle tone in all limbs consistent with diffuse lower motor neuron dysfunction. The dog was severely hypokalemic (1.7 mEq/L; reference range, 3.5 to 5.8 mEq/L). Clinical status of the dog deteriorated; there was muscle twitching, flaccid paralysis, and respiratory failure, which was considered a result of respiratory muscle weakness. Ventricular arrhythmias and severe acidemia (pH, 7.18; reference range, 7.35 to 7.45) developed. Intoxication was suspected, and plasma and urine samples submitted for barium analysis had barium concentrations comparable with those reported in humans with barium toxicosis. Analysis of barium concentrations in 5 control dogs supported the diagnosis of barium toxicosis in the dog. Fluids and potassium supplementation were administered IV. The dog recovered rapidly. Electrolyte concentrations measured after recovery were consistently unremarkable. Quantification of plasma barium concentration 56 days after the presumed episode of intoxication revealed a large decrease; however, the plasma barium concentration remained elevated, compared with that in control dogs. To our knowledge, this case represented the first description of barium toxicosis in the veterinary literature. Barium toxicosis can cause life-threatening hypokalemia; however, prompt supportive treatment can yield excellent outcomes. Barium toxicosis is a rare but important differential diagnosis in animals with hypokalemia and appropriate clinical signs.

Tetraarylborate polymer networks as single-ion conducting solid electrolytes

DOE PAGES

Van Humbeck, Jeffrey F.; Aubrey, Michael L.; Alsbaiee, Alaaeddin; ...

2015-06-23

A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10 -4 S cm -1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to t Li+ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting designmore » parameters for further development of this new class of solid electrolytes.« less

Effect of Borates and Silicates on Wearing Properties of Mao Coatings

NASA Astrophysics Data System (ADS)

Zhang, Yu; Zhao, Yan-Wei; Xiang, Nan; Song, Ren-Guo

In the present study, microarc oxidation (MAO) coatings were formed on ZL101A aluminum alloy in an electrolytic bath containing 3g/L KOH + 2g/L Na2WO4+ 4g/L KF. The morphology and wearing behavior were investigated. In both electrolytes, the additives were borates (Na2B4O718g/L) and silicates (Na2SiO3 18g/L), respectively. It was found that the coating formed in borates-containing electrolyte was of compact and smooth structure than that of the one formed in silicates-containing electrolyte at the optimum treatment time. It was found that all the coatings were composed of á-Al2O3 and ã-Al2O3. The microhardness and wear tests proved that the coating formed in borates-containing electrolyte was having better mechanical properties than those of the coating formed in silicates-containing electrolyte.

Barium determination in gastric contents, blood and urine by inductively coupled plasma mass spectrometry in the case of oral barium chloride poisoning.

PubMed

Łukasik-Głębocka, Magdalena; Sommerfeld, Karina; Hanć, Anetta; Grzegorowski, Adam; Barałkiewicz, Danuta; Gaca, Michał; Zielińska-Psuja, Barbara

2014-01-01

A serious case of barium intoxication from suicidal ingestion is reported. Oral barium chloride poisoning with hypokalemia, neuromuscular and cardiac toxicity, treated with intravenous potassium supplementation and hemodialysis, was confirmed by the determination of barium concentrations in gastric contents, blood, serum and urine using the inductively coupled plasma mass spectrometry method. Barium concentrations in the analyzed specimens were 20.45 µg/L in serum, 150 µg/L in blood, 10,500 µg/L in urine and 63,500 µg/L in gastric contents. Results were compared with barium levels obtained from a non-intoxicated person. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Gamma-ray shielding effect of Gd3+ doped lead barium borate glasses

NASA Astrophysics Data System (ADS)

Kummathi, Harshitha; Naveen Kumar, P.; Vedavathi T., C.; Abhiram, J.; Rajaramakrishna, R.

2018-05-01

The glasses of the batch xPbO: 10BaO: (90-x)B2O3: 0.2Gd2O3 (x = 40,45,50 mol %) were prepared by melt-quench technique. The work emphasizes on gamma ray shielding effect on doped lead glasses. The role of Boron is significant as it acts as better neutron attenuator as compared with any other materials, as the thermal neutron cross-sections are high for Gadolinium, 0.2 mol% is chosen as the optimum concentration for this matrix, as higher the concentration may lead to further increase as it produces secondary γ rays due to inelastic neutron scattering. Shielding effects were studied using Sodium Iodide (NaI) - Scintillation Gamma ray spectrometer. It was found that at higher concentration of lead oxide (PbO) in the matrix, higher the attenuation which can be co-related with density. Infra-red (I.R.) spectra reveals that the conversion of Lose triangles to tight tetrahedral structure results in enhancement of shielding properties. The Differential Scanning Calorimeter (D.S.C.) study also reveals that the increase in glass forming range increases the stability which in-turn results in inter-conversion of BO3 to BO4 units such that the density of glass increases with increase in PbO content, resulting in much stable and efficient gamma ray shielding glasses.

Femtosecond optical parametric amplification in BBO and KTA driven by a Ti:sapphire laser for LIDT testing and diagnostic development

NASA Astrophysics Data System (ADS)

Meadows, Alexander R.; Cupal, Josef; Hříbek, Petr; Durák, Michal; Kramer, Daniel; Rus, Bedřich

2017-05-01

We present the design of a collinear femtosecond optical parametric amplification (OPA) system producing a tunable output at wavelengths between 1030 nm and 1080 nm from a Ti:Sapphire pump laser at a wavelength of 795 nm. Generation of a supercontinuum seed pulse is followed by one stage of amplification in Beta Barium Borate (BBO) and two stages of amplification in Potassium Titanyle Arsenate (KTA), resulting in a 225 μJ output pulse with a duration of 90 fs. The output of the system has been measured by self-referenced spectral interferometry to yield the complete spectrum and spectral phase of the pulse. When compared to KTP, the greater transparency of KTA in the spectral range from 3 - 4 μm allows for reduced idler absorption and enhanced gain from the OPA process when it is pumped by the fundamental frequency of a Ti:sapphire laser. In turn, the use of the Ti:sapphire fundamental at 795 nm as a pump improves the efficiency with which light can be converted to wavelengths between 1030 nm and 1080 nm and subsequently used to test components for Nd-based laser systems. This OPA system is operated at 1 kHz for diagnostic development and laser-induced damage threshold testing of optical components for the ELI-Beamlines project.

Binding and Leakage of Barium in Alginate Microbeads

PubMed Central

Mørch, Yrr A.; Qi, Meirigeng; Gundersen, Per Ole M.; Formo, Kjetil; Lacik, Igor; Skjåk-Bræk, Gudmund; Oberholzer, Jose; Strand, Berit L.

2013-01-01

Microbeads of alginate cross-linked with Ca2+ and/or Ba2+ are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared to high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. In order to reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. PMID:22700168

Binding and leakage of barium in alginate microbeads.

PubMed

Mørch, Yrr A; Qi, Meirigeng; Gundersen, Per Ole M; Formo, Kjetil; Lacik, Igor; Skjåk-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L

2012-11-01

Microbeads of alginate crosslinked with Ca(2+) and/or Ba(2+) are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared with high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. To reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. Copyright © 2012 Wiley Periodicals, Inc.

The diagnosis of gastro-esophageal reflux disease cannot be made with barium esophagograms.

PubMed

Saleh, C M G; Smout, A J P M; Bredenoord, A J

2015-02-01

For over 50 years, barium studies have been used to diagnose gastro-esophageal reflux disease (GERD), but the value of this test is controversial. Our study aimed to determine if barium esophagograms can be used to diagnose GERD. Barium esophagograms and pH-impedance measurement were performed in 20 subjects with reflux symptoms. pH-impedance measurements were used as gold standard for the diagnosis of GERD. Gastro-esophageal reflux measured with the barium study was defined as a positive outcome. 50% of patients presented gastro-esophageal reflux on the barium esophagogram. No significant differences were observed in acid exposure time between subjects with (median: 7.4%; interquartile range, IQR: 8.4%) or without reflux at barium esophagography (median: 5.95%; IQR: 13.05%; p > 0.05). Nor did we find differences in median proximal extent of reflux measured with impedance monitoring between patients with a positive (median: 6.7%; IQR: 1.95%) and negative barium study (median: 7.1%; IQR: 0.68%; p > 0.05). Patients with reflux on barium esophagogram did not have a positive symptom association probability more often than those who did not have reflux at barium esophagography. Lastly, there were no differences in numbers of acid, weakly acidic or total reflux episodes between those with positive or negative barium esophagogram (p > 0.05). No correlations were found between the maximum proximal extent of gastro-esophageal reflux during esophagography and pH-impedance parameters. Presence or absence of gastro-esophageal reflux during barium esophagography does not correlate with incidence or extent of reflux observed during 24-h pH-impedance monitoring and is not of value for the diagnosis of GERD. © 2014 John Wiley & Sons Ltd.

A review of the health impacts of barium from natural and anthropogenic exposure.

PubMed

Kravchenko, Julia; Darrah, Thomas H; Miller, Richard K; Lyerly, H Kim; Vengosh, Avner

2014-08-01

There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food.

Alteration of the fast excitatory postsynaptic current by barium in voltage-clamped amphibian sympathetic ganglion cells.

PubMed Central

Connor, E. A.; Parsons, R. L.

1984-01-01

Barium-induced alterations in fast excitatory postsynaptic currents (e.p.s.cs) have been studied in voltage-clamped bullfrog sympathetic ganglion B cells. In the presence of 2-8 mM barium, e.p.s.c. decay was prolonged and in many cells the e.p.s.c. decay phase deviated from a single exponential function. The decay phase in these cases was more accurately described as the sum of two exponential functions. The frequency of occurrence of a complex decay increased both with increasing barium concentration and with hyperpolarization. Miniature e.p.s.c. decay also was prolonged in barium-treated cells. E.p.s.c. amplitude was not markedly affected by barium (2-8 mM) in cells voltage-clamped to -50 mV whereas at -90 mV there was a progressive increase in peak size with increasing barium concentration. In control cells the e.p.s.c.-voltage relationship was linear between -20 and -100 mV; however, this relationship became progressively non-linear with membrane hyperpolarization in barium-treated cells. The e.p.s.c. reversal potential was shifted to a more negative value in the presence of barium. There was a voltage-dependent increase in charge movement during the e.p.s.c. in barium-treated cells which was not present in control cells. We conclude that the voltage-dependent alteration in e.p.s.c. decay time course, peak amplitude and charge movement in barium-treated cells is due to a direct postsynaptic action of barium on the kinetics of receptor-channel gating in postganglionic sympathetic neurones. PMID:6333261

Hertzsprung-Russell diagram and mass distribution of barium stars

NASA Astrophysics Data System (ADS)

Escorza, A.; Boffin, H. M. J.; Jorissen, A.; Van Eck, S.; Siess, L.; Van Winckel, H.; Karinkuzhi, D.; Shetye, S.; Pourbaix, D.

2017-12-01

With the availability of parallaxes provided by the Tycho-Gaia Astrometric Solution, it is possible to construct the Hertzsprung-Russell diagram (HRD) of barium and related stars with unprecedented accuracy. A direct result from the derived HRD is that subgiant CH stars occupy the same region as barium dwarfs, contrary to what their designations imply. By comparing the position of barium stars in the HRD with STAREVOL evolutionary tracks, it is possible to evaluate their masses, provided the metallicity is known. We used an average metallicity [Fe/H] = -0.25 and derived the mass distribution of barium giants. The distribution peaks around 2.5 M⊙ with a tail at higher masses up to 4.5 M⊙. This peak is also seen in the mass distribution of a sample of normal K and M giants used for comparison and is associated with stars located in the red clump. When we compare these mass distributions, we see a deficit of low-mass (1 - 2 M⊙) barium giants. This is probably because low-mass stars reach large radii at the tip of the red giant branch, which may have resulted in an early binary interaction. Among barium giants, the high-mass tail is however dominated by stars with barium indices of less than unity, based on a visual inspection of the barium spectral line; that is, these stars have a very moderate barium line strength. We believe that these stars are not genuine barium giants, but rather bright giants, or supergiants, where the barium lines are strengthened because of a positive luminosity effect. Moreover, contrary to previous claims, we do not see differences between the mass distributions of mild and strong barium giants. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A100

Magnesium and zinc borate enhance osteoblastic differentiation of stem cells from human exfoliated deciduous teeth in vitro.

PubMed

Liu, Yao-Jen; Su, Wen-Ta; Chen, Po-Hung

2018-01-01

Various biocompatible and biodegradable scaffolds blended with biochemical signal molecules with adequate osteoinductive and osteoconductive properties have attracted significant interest in hard tissue engineering regeneration. We evaluated the distinct effects of magnesium borate, zinc borate, and boric acid blended into chitosan scaffold for osteogenic differentiation of stem cells from exfoliated deciduous teeth. Stem cells from exfoliated deciduous teeth cells are a potential source of functional osteoblasts for applications in bone tissue engineering, but the efficiency of osteoblastic differentiation is low, thereby significantly limiting their clinical applications. Divalent metal borates have potential function in bone remodeling because they can simulate bone formation and decrease bone resorption. These magnesium, zinc, and B ions can gradually be released into the culture medium from the scaffold and induce advanced osteoblastic differentiation from stem cells from exfoliated deciduous teeth. Stem cells from exfoliated deciduous teeth with magnesium borate or zinc borate as inducer demonstrated more osteoblastic differentiation after 21 days of culture. Differentiated cells exhibited activity of alkaline phosphatase, bone-related gene expression of collagen type I, runt-related transcription factor 2, osteopontin, osteocalcin, vascular endothelial growth factor, and angiopoietin-1, as noted via real-time polymerase chain reaction analysis, as well as significant deposits of calcium minerals. Divalent mental magnesium and zinc and nonmetal boron can be an effective inducer of osteogenesis for stem cells from exfoliated deciduous teeth. This experiment might provide useful inducers for osteoblastic differentiation of stem cells from exfoliated deciduous teeth for tissue engineering and bone repair.

Surface studies of thermionic cathodes and the mechanism of operation of an impregnated tungsten cathode

NASA Technical Reports Server (NTRS)

Forman, R.

1976-01-01

The surface properties of conventional impregnated cathodes were investigated by the use of Auger spectroscopy and work function measurements, and these were compared with a synthesized barium or barium oxide coated tungsten surface. The barium and barium oxide coated surfaces were prepared by evaporating barium onto a tungsten surface that can be heated to elevated temperatures. Multilayer or monolayer coverages can be investigated using this technique. The results of this study show that the surface of an impregnated tungsten cathode is identical to that observed for a synthesized monolayer or partial monolayer of barium on partially oxidized tungsten, using the criteria of identical Auger patterns and work functions. Desorption measurements of barium from a tungsten surface were also made. These results in conjunction with Auger and work function data were interpreted to show that throughout most of its life an impregnated cathode operating in the range of 1100 C has a partial monolayer rather than a monolayer of barium on its surface.

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions

PubMed Central

Tanti, N.C.; Jones, L.; Sheardown, H.

2010-01-01

Purpose Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. Methods An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate  (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Results Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of β1 and α3 integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Conclusions Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells. PMID:20169012

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions.

PubMed

Gorbet, M B; Tanti, N C; Jones, L; Sheardown, H

2010-02-19

Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of beta(1) and alpha(3) integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells.

Status of barium studies in the present era of oncology: Are they a history?

PubMed Central

Mahajan, Abhishek; Desai, Subash; Sable, Nilesh Pandurang; Thakur, Meenakshi Haresh

2016-01-01

With the advent of the modern imaging technologies, the present era of oncology is seeing steady decline in requests for barium studies due to the many reasons. It is prudent to mention here, that, barium examinations cannot be made obsolete! Our aim to preserve the age old technique of barium studies not only to keep it going on but also for the betterment and appropriate management of the patient. Our goal is not to “save” barium studies simply to keep this technology alive, per se, but rather to preserve barium radiology for the quality in patient care. PMID:28144086

40 CFR 721.10011 - Barium calcium manganese strontium oxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

40 CFR 721.10011 - Barium calcium manganese strontium oxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

Barium ferrite thin-film recording media

NASA Astrophysics Data System (ADS)

Sui, Xiaoyu; Scherge, Matthias; Kryder, Mark H.; Snyder, John E.; Harris, Vincent G.; Koon, Norman C.

1996-03-01

Both longitudinal and perpendicular barium ferrite thin films are being pursued as overcoatless magnetic recording media. In this paper, prior research on thin-film Ba ferrite is reviewed and the most recent results are presented. Self-textured high-coercivity longitudinal Ba ferrite thin films have been achieved using conventional rf diode sputtering. Microstructural studies show that c-axis in-plane oriented grains have a characteristic acicular shape, while c-axis perpendicularly oriented grains have a platelet shape. Extended X-ray absorption fine structure (EXAFS) measurements indicate that the crystal orientations are predetermined by the structural anisotropy in the as-sputtered 'amorphous' state. Recording tests on 1500 Oe coercivity longitudinal Ba ferrite disks show performance comparable with that of a 1900 Oe Co alloy disk. To further improve the recording performance, both grain size and aspect ratio need to be reduced. Initial tribological tests indicate high hardness of Ba ferrite thin films. However, surface roughness needs to be reduced. For future ultrahigh-density contact recording, it is believed that perpendicular recording may be used. A thin Pt underlayer has been found to be capable of producing Ba ferrite thin films with excellent c-axis perpendicular orientation.

Fabrication of barium titanate doped strontium using co-precipitation method

NASA Astrophysics Data System (ADS)

Iriani, Y.; Yasin, M. A.; Suryana, R.

2018-03-01

Fabrication of barium titanate (BaTiO3/BT) doped strontium (Sr) using co-precipitation method has been successfully conducted. The research aim is to get the best of mole variation of Sr doping to ferroelectric material properties. Doping Sr was varied at 1%, 2%, 3%, 4% and 5% in BaTiO3. Each sample was sintered at temperature of 1100°C with holding time for 6 h and temperature rate at 10°C/min. They were then characterized by XRD instrument to investigate the crystal structure, LCR meter to measure the dielectric constant, and Sawyer Tower circuit to reveal the hysteresis curve. The peaks of XRD shift towards larger angle when mole doping Sr increase. The crystallinity of all samples is above 90% and the crystallite size is in the range of 27 nm to 34 nm. Hysteresis curve from Sawyer Tower testing confirms that all samples are ferroelectric material. The RLC measurement results reveal that the less frequency leads to the higher dielectric constant while the highest dielectric constant belongs to the BT doped 3% of Sr. Therefore, it is the best variation obtained in this research.

Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water.

PubMed

Kato, Masashi; Kumasaka, Mayuko Y; Ohnuma, Shoko; Furuta, Akio; Kato, Yoko; Shekhar, Hossain U; Kojima, Michiyo; Koike, Yasuko; Dinh Thang, Nguyen; Ohgami, Nobutaka; Ly, Thuy Bich; Jia, Xiaofang; Yetti, Husna; Naito, Hisao; Ichihara, Gaku; Yajima, Ichiro

2013-01-01

Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L) and coexposure to barium (137 µg/L) and arsenic (225 µg/L). The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L) and barium (700 µg/L), but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium), in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system.

Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water

PubMed Central

Kato, Masashi; Kumasaka, Mayuko Y.; Ohnuma, Shoko; Furuta, Akio; Kato, Yoko; Shekhar, Hossain U.; Kojima, Michiyo; Koike, Yasuko; Dinh Thang, Nguyen; Ohgami, Nobutaka; Ly, Thuy Bich; Jia, Xiaofang; Yetti, Husna; Naito, Hisao; Ichihara, Gaku; Yajima, Ichiro

2013-01-01

Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L) and coexposure to barium (137 µg/L) and arsenic (225 µg/L). The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L) and barium (700 µg/L), but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium), in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system. PMID:23805262

Effects of chemesthetic stimuli mixtures with barium on swallowing apnea duration.

PubMed

Todd, J Tee; Butler, Susan G; Plonk, Drew P; Grace-Martin, Karen; Pelletier, Cathy A

2012-10-01

This study tested the hypotheses that swallowing apnea duration (SAD) will increase given barium versus water, chemesthetic stimuli (i.e., water < ethanol, acid, and carbonation) mixed with barium, age (older > younger), and genetic taste differences (supertasters > nontasters). Prospective group design. University Medical Center. Eighty healthy women were identified as nontasters and supertasters, equally comprising two age groups: 18 to 35 years and 60+ years. The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL barium, 2.7% w/v citric acid with barium, carbonation with barium, and 50:50 diluted ethanol with barium. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures. Significant main effects of age (P = .012) and chemesthetic stimuli (P = .014) were found, as well as a significant interaction between chemesthetic stimuli and age (P = .028). Older women had a significantly longer SAD than younger women. Post hoc analyses revealed that barium mixed with ethanol elicited a significantly longer SAD than other bolus conditions, regardless of age group. There were no significant differences in SAD between barium and water conditions, and no significant effect of chemesthetic perception (P > .05). Ethanol added to barium elicited longer SAD compared to plain barium, but not the other chemesthetic conditions. Older women had a longer SAD than younger women in all conditions. These findings may influence design of future studies examining effects of various stimuli on SAD. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

Tungsten and Barium Transport in the Internal Plasma of Hollow Cathodes

NASA Technical Reports Server (NTRS)

Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

2008-01-01

The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushedback to the emitter surface by the electric field and drag from the xenon ion flow. Thisbarium ion flux is sufficient to maintain a barium surface coverage at the downstream endgreater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length,so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollowcathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

Barium titanate nanocrystals and nanocrystal thin films: Synthesis, ferroelectricity, and dielectric properties

NASA Astrophysics Data System (ADS)

Huang, Limin; Chen, Zhuoying; Wilson, James D.; Banerjee, Sarbajit; Robinson, Richard D.; Herman, Irving P.; Laibowitz, Robert; O'Brien, Stephen

2006-08-01

Advanced applications for high k dielectric and ferroelectric materials in the electronics industry continues to demand an understanding of the underlying physics in decreasing dimensions into the nanoscale. We report the synthesis, processing, and electrical characterization of thin (<100nm thick) nanostructured thin films of barium titanate (BaTiO3) built from uniform nanoparticles (<20nm in diameter). We introduce a form of processing as a step toward the ability to prepare textured films based on assembly of nanoparticles. Essential to this approach is an understanding of the nanoparticle as a building block, combined with an ability to integrate them into thin films that have uniform and characteristic electrical properties. Our method offers a versatile means of preparing BaTiO3 nanocrystals, which can be used as a basis for micropatterned or continuous BaTiO3 nanocrystal thin films. We observe the BaTiO3 nanocrystals crystallize with evidence of tetragonality. We investigated the preparation of well-isolated BaTiO3 nanocrystals smaller than 10nm with control over aggregation and crystal densities on various substrates such as Si, Si /SiO2, Si3N4/Si, and Pt-coated Si substrates. BaTiO3 nanocrystal thin films were then prepared, resulting in films with a uniform nanocrystalline grain texture. Electric field dependent polarization measurements show spontaneous polarization and hysteresis, indicating ferroelectric behavior for the BaTiO3 nanocrystalline films with grain sizes in the range of 10-30nm. Dielectric measurements of the films show dielectic constants in the range of 85-90 over the 1KHz -100KHz, with low loss. We present nanocrystals as initial building blocks for the preparation of thin films which exhibit highly uniform nanostructured texture and grain sizes.

Crystallization of MgFe2O4 from a glass in the system K2O/B2O3/MgO/P2O5/Fe2O3

NASA Astrophysics Data System (ADS)

El Shabrawy, Samha; Bocker, Christian; Rüssel, Christian

2016-10-01

Spherical magnetic Mg-Fe-O nanoparticles were successfully prepared by the crystallization of glass in the system K2O/B2O3/MgO/P2O5/Fe2O3. The magnetic glass ceramics were prepared by melting the raw materials using the conventional melt quenching technique followed by a thermal treatment at temperatures in the range 560-700 °C for a time ranging from 2 to 8 h. The studies of the X-ray diffraction, electron microscopy and FTIR spectra confirmed the precipitation of finely dispersed spherical (Mg, Fe) based spinel nanoparticles with a minor quantity of hematite (α-Fe2O3) in the glass matrix. The average size of the magnetic nano crystals increases slightly with temperature and time from 9 to 15 nm as determined by the line broadening from the XRD patterns. XRD studies show that annealing the glass samples for long periods of time at temperature ≥604 °C results in an increase of the precipitated hematite concentration, dissolution of the spinel phase and the formation of magnesium di-borate phase (Mg2B2O5). For electron microscopy, the particles were extracted by two methods; (i) replica extraction technique and (ii) dissolution of the glass matrix by diluted acetic acid. An agglomeration of the nano crystals to larger particles (25-35 nm) was observed.

Passive safety injection system using borated water

DOEpatents

Conway, Lawrence E.; Schulz, Terry L.

1993-01-01

A passive safety injection system relies on differences in water density to induce natural circulatory flow patterns which help maintain prescribed concentrations of boric acid in borated water, and prevents boron from accumulating in the reactor vessel and possibly preventing heat transfer.

Boric Acid Corrosion of Concrete Rebar

NASA Astrophysics Data System (ADS)

Pabalan, R. T.; Yang, L.; Chiang, K.–T.

2013-07-01

Borated water leakage through spent fuel pools (SFPs) at pressurized water reactors is a concern because it could cause corrosion of reinforcement steel in the concrete structure and compromise the integrity of the structure. Because corrosion rate of carbon steel in concrete in the presence of boric acid is lacking in published literature and available data are equivocal on the effect of boric acid on rebar corrosion, corrosion rate measurements were conducted in this study using several test methods. Rebar corrosion rates were measured in (i) borated water flowing in a simulated concrete crack, (ii) borated water flowing over a concrete surface, (iii) borated water that has reacted with concrete, and (iv) 2,400 ppm boric acid solutions with pH adjusted to a range of 6.0 to 7.7. The corrosion rates were measured using coupled multielectrode array sensor (CMAS) and linear polarization resistance (LPR) probes, both made using carbon steel. The results indicate that rebar corrosion rates are low (~1 μm/yr or less)when the solution pH is ~7.1 or higher. Below pH ~7.1, the corrosion rate increases with decreasing pH and can reach ~100 μm/yr in solutions with pH less than ~6.7. The threshold pH for carbon steel corrosion in borated solution is between 6.8 and 7.3.

Geochemical characteristics of Kırka (Sarıkaya) borate deposit, northwestern Anatolia, Turkey

NASA Astrophysics Data System (ADS)

Koçak, İ.; Koç, Ş.

2016-02-01

The Kırka borate deposit was deposited in a Miocene lacustrine basin which is closely associated with volcanic activity which lasted from Paleogene to the beginning of Quaternary. Borate mineralization alternates with claystone, mudstone, tuff and fine-layered limestone and mostly shows a lenticular structure. The mineral paragenesis is composed of borax, tincalconite, ulexite, kurnakovite, probertite, tunellite, colemanite, dolomite, smectite group minerals, illite and some firstly reported minerals for the Kırka deposit including hydrochloroborite, brianroulstonite, hilgardite-4M and searlesite minerals. In comparison to average values of earth crust, concentrations of Cs, Sr, Li, As and Se were significantly enriched with respective rates of 21, 15, 14, 3 and 188 folds. Regarding KY, KS1 and KS2 locations, there are differences in both element abundances and their geochemical tendencies which are attributed to variations in discharge regime and physico-chemical conditions of the depositional environment. Independent behaviour of B2O3 might indicate that boron is not associated with clays and carbonates and, therefore, most part of boron must be derived from volcanic activity (hydrothermal solutions, gases). REE data indicate that the Kırka borate deposit was formed in a sedimentary environment where highly alkaline (high pH) hydrothermal solutions also took part in borate precipitation process.

Treatment of cells with alkaline borate buffer extends the capability of interphase FISH mapping.

PubMed

Yokota, H; van den Engh, G; Mostert, M; Trask, B J

1995-01-20

Interphase fluorescence in situ hybridization (FISH) has been shown to be a means to map DNA sequences relative to each other in the 100 kb to 1-2 Mb genomic-separation range. At distances below 0.1 Mb, probe sites are infrequently resolved in interphase chromatin. In the 0.1- to 1-Mb range, interphase chromatin can be modeled as a freely flexible chain. The mean square interphase distance between two probes is proportional to the genomic separation between the probes on the linear DNA molecule. Above 1-2 Mb, the relationship between interphase distance and genomic separation changes abruptly and appears to level off. We have used alkaline-borate treatment to expand the capability of interphase FISH mapping. We show here that alkaline-borate treatment increases nuclear diameter, the interphase distance between probes on homologous chromosomes, and the distance between probes on the same chromosome. We also show that the mean square distance between hybridization sites in borate-treated nuclei is proportional to genomic separation up to 4 Mb. Thus, alkaline-borate treatment enhances the capability of interphase FISH mapping by increasing the absolute distance between probes and extending the range of the simple relationship between interphase distance and genomic separation.

Treatment of cells with alkaline borate buffer extends the capability of interphase FISH mapping

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

Yokota, H.; Van Den Engh, G.; Mostert, M.

1995-01-20

Interphase fluorescence in situ hybridization (FISH) has been shown to be a means to map DNA sequences relative to each other in the 100 kb to 1-2 Mb genomic-separation range. At distances below 0.1 Mb, probe sites are infrequently resolved in interphase chromatin. In the 0.1- to 1-Mb range, interphase chromatin can be modeled as a freely flexible chain. The mean square interphase distance between two probes is proportional to the genomic separation between the probes on the linear DNA molecule. Above 1-2 Mb, the relationship between interphase distance and genomic separation changes abruptly and appears to level off. Wemore » have used alkaline-borate treatment to expand the capability of interphase FISH mapping. We show here that alkaline-borate treatment increases nuclear diameter, the interphase distance between probes on homologous chromosomes, and the distance between probes on the same chromosome. We also show that the mean square distance between hybridization sites in borate-treated nuclei is proportional to genomic separation up to 4 Mb. Thus, alkaline-borate treatment enhances the capability of interphase FISH mapping by increasing the absolute distance between probes and extending the range of the simple relationship between interphase distance and genomic separation. 31 refs., 5 figs.« less

A novel injectable borate bioactive glass cement for local delivery of vancomycin to cure osteomyelitis and regenerate bone.

PubMed

Cui, Xu; Zhao, Cunju; Gu, Yifei; Li, Le; Wang, Hui; Huang, Wenhai; Zhou, Nai; Wang, Deping; Zhu, Yi; Xu, Jun; Luo, Shihua; Zhang, Changqing; Rahaman, Mohamed N

2014-03-01

Osteomyelitis (bone infection) is often difficult to cure. The commonly-used treatment of surgical debridement to remove the infected bone combined with prolonged systemic and local antibiotic treatment has limitations. In the present study, an injectable borate bioactive glass cement was developed as a carrier for the antibiotic vancomycin, characterized in vitro, and evaluated for its capacity to cure osteomyelitis in a rabbit tibial model. The cement (initial setting time = 5.8 ± 0.6 min; compressive strength = 25.6 ± 0.3 MPa) released vancomycin over ~25 days in phosphate-buffered saline, during which time the borate glass converted to hydroxyapatite (HA). When implanted in rabbit tibial defects infected with methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis, the vancomycin-loaded cement converted to HA and supported new bone formation in the defects within 8 weeks. Osteomyelitis was cured in 87 % of the defects implanted with the vancomycin-loaded borate glass cement, compared to 71 % for the defects implanted with vancomycin-loaded calcium sulfate cement. The injectable borate bioactive glass cement developed in this study is a promising treatment for curing osteomyelitis and for regenerating bone in the defects following cure of the infection.

In vitro bioactivity, cytocompatibility, and antibiotic release profile of gentamicin sulfate-loaded borate bioactive glass/chitosan composites.

PubMed

Cui, Xu; Gu, Yifei; Li, Le; Wang, Hui; Xie, Zhongping; Luo, Shihua; Zhou, Nai; Huang, Wenhai; Rahaman, Mohamed N

2013-10-01

Borate bioactive glass-based composites have been attracting interest recently as an osteoconductive carrier material for local antibiotic delivery. In the present study, composites composed of borate bioactive glass particles bonded with a chitosan matrix were prepared and evaluated in vitro as a carrier for gentamicin sulfate. The bioactivity, degradation, drug release profile, and compressive strength of the composite carrier system were studied as a function of immersion time in phosphate-buffered saline at 37 °C. The cytocompatibility of the gentamicin sulfate-loaded composite carrier was evaluated using assays of cell proliferation and alkaline phosphatase activity of osteogenic MC3T3-E1 cells. Sustained release of gentamicin sulfate occurred over ~28 days in PBS, while the bioactive glass converted continuously to hydroxyapatite. The compressive strength of the composite loaded with gentamicin sulfate decreased from the as-fabricated value of 24 ± 3 MPa to ~8 MPa after immersion for 14 days in PBS. Extracts of the soluble ionic products of the borate glass/chitosan composites enhanced the proliferation and alkaline phosphatase activity of MC3T3-E1 cells. These results indicate that the gentamicin sulfate-loaded composite composed of chitosan-bonded borate bioactive glass particles could be useful clinically as an osteoconductive carrier material for treating bone infection.

Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

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

Melo, B. M. G.; Graça, M. P. F., E-mail: mpfg@ua.pt; Prezas, P. R.

2016-08-07

In this work, phosphate-borate based glasses with molar composition 20.7P{sub 2}O{sub 5}–17.2Nb{sub 2}O{sub 5}–13.8WO{sub 3}–34.5A{sub 2}O–13.8B{sub 2}O{sub 3}, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric,more » and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σ{sub ac} and σ{sub dc}, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz–1 MHz.« less

Nano crystalline Bi{sub 2}(VO{sub 5}) phases in lithium bismuth borate glasses containing mixed vanadium-nickel oxides

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

Yadav, Arti, E-mail: artidabhur@gmail.com; Khasa, S.; Dahiya, M. S.

2016-05-23

Glass composition 7V{sub 2}O{sub 5}·23Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} and x(2NiO·V{sub 2}O{sub 5})·(30-x)Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3}, x=0, 2, 5, 7 and 10, were produced by conventional melt quenching technique. The quenched amorphous glass samples were annealed at temperatures 400°C and 500°C for 6 hours. The Bi{sub 2}(VO{sub 5}) crystallite were grown in all prepared glass matrix. Tn vanadium lithium bismuth borate glass (annealed), the some phrase of V{sub 2}O{sub 5}-crystal were observed along with the nano crystalline Bi{sub 2}(VO{sub 5}) phase. The sharp peaks in FTTR spectra of all annealed compositions were also compatible with the XRDmore » diffraction peaks of the system under investigation. Average crystalline size (D) of the Bi{sub 2}(VO{sub 5}) nano-crystallite was ~30 nm for samples annealed at 400°C and ~42 nm for samples annealed at 500°C. Lattice parameter and the lattice strain for all the samples was also calculated corresponding to the (113) plane of Bi{sub 2}(VO{sub 5}) crystallite.« less

Life Model of Hollow Cathodes Using a Barium Calcium Aluminate Impregnated Tungsten Emitter

NASA Technical Reports Server (NTRS)

Kovaleski, S. D.; Burke, Tom (Technical Monitor)

2001-01-01

Hollow cathodes with barium calcium aluminate impregnated tungsten emitters for thermionic emission are widely used in electric propulsion. These high current, low power cathodes are employed in ion thrusters, Hall thrusters, and on the International Space Station in plasma contactors. The requirements on hollow cathode life are growing more stringent with the increasing use of electric propulsion technology. The life limiting mechanism that determines the entitlement lifetime of a barium impregnated thermionic emission cathode is the evolution and transport of barium away from the emitter surface. A model is being developed to study the process of barium transport and loss from the emitter insert in hollow cathodes. The model accounts for the production of barium through analysis of the relevant impregnate chemistry. Transport of barium through the approximately static gas is also being treated. Finally, the effect of temperature gradients within the cathode are considered.

Nanoparticles of barium induce apoptosis in human phagocytes

PubMed Central

Mores, Luana; França, Eduardo Luzia; Silva, Núbia Andrade; Suchara, Eliane Aparecida; Honorio-França, Adenilda Cristina

2015-01-01

Purpose Nutrients and immunological factors of breast milk are essential for newborn growth and the development of their immune system, but this secretion can contain organic and inorganic toxins such as barium. Colostrum contamination with barium is an important issue to investigate because this naturally occurring element is also associated with human activity and industrial pollution. The study evaluated the administration of barium nanoparticles to colostrum, assessing the viability and functional activity of colostral mononuclear phagocytes. Methods Colostrum was collected from 24 clinically healthy women (aged 18–35 years). Cell viability, superoxide release, intracellular Ca2+ release, and phagocyte apoptosis were analyzed in the samples. Results Treatment with barium lowered mononuclear phagocyte viability, increased superoxide release, and reduced intracellular calcium release. In addition, barium increased cell death by apoptosis. Conclusion These data suggest that nanoparticles of barium in colostrum are toxic to cells, showing the importance of avoiding exposure to this element. PMID:26451108

Nanoparticles of barium induce apoptosis in human phagocytes.

PubMed

Mores, Luana; França, Eduardo Luzia; Silva, Núbia Andrade; Suchara, Eliane Aparecida; Honorio-França, Adenilda Cristina

2015-01-01

Nutrients and immunological factors of breast milk are essential for newborn growth and the development of their immune system, but this secretion can contain organic and inorganic toxins such as barium. Colostrum contamination with barium is an important issue to investigate because this naturally occurring element is also associated with human activity and industrial pollution. The study evaluated the administration of barium nanoparticles to colostrum, assessing the viability and functional activity of colostral mononuclear phagocytes. Colostrum was collected from 24 clinically healthy women (aged 18-35 years). Cell viability, superoxide release, intracellular Ca(2+) release, and phagocyte apoptosis were analyzed in the samples. Treatment with barium lowered mononuclear phagocyte viability, increased superoxide release, and reduced intracellular calcium release. In addition, barium increased cell death by apoptosis. These data suggest that nanoparticles of barium in colostrum are toxic to cells, showing the importance of avoiding exposure to this element.

Crystal structure, phase transition and structural deformations in iron borate (Y0.95Bi0.05)Fe3(BO3)4 in the temperature range 90-500 K.

PubMed

Smirnova, Ekaterina S; Alekseeva, Olga A; Dudka, Alexander P; Artemov, Vladimir V; Zubavichus, Yan V; Gudim, Irina A; Bezmaterhykh, Leonard N; Frolov, Kirill V; Lyubutin, Igor S

2018-04-01

An accurate X-ray diffraction study of (Y 0.95 Bi 0.05 )Fe 3 (BO 3 ) 4 single crystals in the temperature range 90-500 K was performed on a laboratory diffractometer and used synchrotron radiation. It was established that the crystal undergoes a diffuse structural phase transition in the temperature range 350-380 K. The complexity of localization of such a transition over temperature was overcome by means of special analysis of systematic extinction reflections by symmetry. The transition temperature can be considered to be T str ≃ 370 K. The crystal has a trigonal structure in the space group P3 1 21 at temperatures of 90-370 K, and it has a trigonal structure in the space group R32 at 375-500 K. There is one type of chain formed by the FeO 6 octahedra along the c axis in the R32 phase. When going into the P3 1 21 phase, two types of nonequivalent chains arise, in which Fe atoms are separated from the Y atoms by a different distance. Upon lowering the temperature from 500 to 90 K, a distortion of the Y(Bi)O 6 , FeO 6 , B(2,3)O 3 coordination polyhedra is observed. The distances between atoms in helical Fe chains and Fe-O-Fe angles change non-uniformly. A sharp jump in the equivalent isotropic displacement parameters of O1 and O2 atoms within the Fe-Fe chains and fluctuations of the equivalent isotropic displacement parameters of B2 and B3 atoms were observed in the region of structural transition as well as noticeable elongation of O1, O2, B2, B3, Fe1, Fe2 atomic displacement ellipsoids. It was established that the helices of electron density formed by Fe, O1 and O2 atoms may be structural elements determining chirality, optical activity and multiferroicity of rare-earth iron borates. Compression and stretching of these helices account for the symmetry change and for the manifestation of a number of properties, whose geometry is controlled by an indirect exchange interaction between iron cations that compete with the thermal motion of atoms in the structure. Structural analysis detected these changes as variations of a number of structural characteristics in the c unit-cell direction, that is, the direction of the helices. Structural results for the local surrounding of the atoms in (Y 0.95 Bi 0.05 )Fe 3 (BO 3 ) 4 were confirmed by EXAFS and Mössbauer spectroscopies.

Residual glass and crystalline phases in a barium disilicate glass–ceramic

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

Araujo, Marcel C.C.; Botta, Walter J.; Kaufmann, Michael J.

2015-12-15

Investigations about the presence of residual glass are scarce, despite its fundamental role in the crystallization kinetics and luminescent properties of barium disilicate glass–ceramics (BaO·2SiO{sub 2}–BS{sub 2}) with a quasi-stoichiometric composition. Non-isothermal (DTA/DSC) experiments have demonstrated that BS{sub 2} presents a polymorphic transformation, where the h-BS{sub 2} (monoclinic structure) phase is completely transformed in l-BS{sub 2} (orthorhombic structure) at temperatures higher than 1020 °C (10 °C/min). In this study, BS{sub 2} monolithic samples were heat-treated at 1000 °C (BS2-10) and 1100 °C (BS2-11) in a DSC furnace at a heating rate of 10 °C/min. In addition, the crystalline and amorphousmore » phases were characterized and quantified by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) experiments, respectively. Although the complete polymorphic transformation from h-BS2 to l-BS2 was achieved at 1100 °C, our results demonstrated that BS2-11 contains a minor, albeit not negligible, amount of residual glass. - Highlights: • The crystalline and amorphous phases in a barium disilicate glass were characterized and quantified by XRD and TEM. • The BS2-10 sample was constituted by two main crystalline phases, which consists of 2 polymorphic forms: h-BS2 and l-BS2. • The orthorhombic BS2 phase (l-BS2) was predominant at 1100 °C. • The complete polymorphic transformation from h-BS2 to l-BS2 was achieved at 1100 °C. • Nevertheless, our XRD and TEM results demonstrated that BS2-11 contains a minor amount of residual glass.« less

Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

PubMed

Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

2016-03-30

A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Do all barium stars have a white dwarf companion?

NASA Technical Reports Server (NTRS)

Dominy, J. F.; Lambert, D. L.

1983-01-01

International Ultraviolet Explorer short-wavelength, low-dispersion spectra were analyzed for four barium, two mild barium, and one R-type carbon star in order to test the hypothesis that the barium and related giants are produced by mass transfer from a companion now present as a white dwarf. An earlier tentative identification of a white dwarf companion to the mild barium star Zeta Cyg is confirmed. For the other stars, no ultraviolet excess attributable to a white dwarf is seen. Limits are set on the bolometric magnitude and age of a possible white dwarf companion. Since the barium stars do not have obvious progenitors among main-sequence and subgiant stars, mass transfer must be presumed to occur when the mass-gaining star is already on the giant branch. This restriction, and the white dwarf's minimum age, which is greater than 8 x 10 to the 8th yr, determined for several stars, effectively eliminates the hypothesis that mass transfer from an asymptotic giant branch star creates a barium star. Speculations are presented on alternative methods of producing a barium star in a binary system.

Barium versus nonbarium stimuli: differences in taste intensity, chemesthesis, and swallowing behavior in healthy adult women.

PubMed

Nagy, Ahmed; Steele, Catriona M; Pelletier, Cathy A

2014-06-01

The authors examined the impact of barium on the perceived taste intensity of 7 different liquid tastant stimuli and the modulatory effect that these differences in perceived taste intensity have on swallowing behaviors. Participants were 80 healthy women, stratified by age group (<40; >60) and genetic taste status (supertasters; nontasters). Perceived taste intensity and chemesthetic properties (fizziness; burning-stinging) were rated for 7 tastant solutions (each prepared with and without barium) using the general Labeled Magnitude Scale. Tongue-palate pressures and submental surface electromyography (sEMG) were simultaneously measured during swallowing of these same randomized liquids. Path analysis differentiated the effects of stimulus, genetic taste status, age, barium condition, taste intensity, and an effortful saliva swallow strength covariate on swallowing. Barium stimuli were rated as having reduced taste intensity compared with nonbarium stimuli. Barium also dampened fizziness but did not influence burning-stinging sensation. The amplitudes of tongue-palate pressure or submental sEMG did not differ when swallowing barium versus nonbarium stimuli. Despite impacting taste intensity, the addition of barium to liquid stimuli does not appear to alter behavioral parameters of swallowing. Barium solutions can be considered to elicit behaviors that are similar to those used with nonbarium liquids outside the assessment situation.

Barium Peritonitis in Small Animals

PubMed Central

KO, Jae Jin; MANN, F. A. (Tony)

2014-01-01

ABSTRACT Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions. PMID:24430662

Endotrophic Calcium, Strontium, and Barium Spores of Bacillus megaterium and Bacillus cereus1

PubMed Central

Foerster, Harold F.; Foster, J. W.

1966-01-01

Foerster, Harold F. (The University of Texas, Austin), and J. W. Foster. Endotrophic calcium, strontium, and barium spores of Bacillus megaterium and Bacillus cereus. J. Bacteriol. 91:1333–1345. 1966.—Spores were produced by washed vegetative cells suspended in deionized water supplemented with CaCl2, SrCl2, or BaCl2. Normal, refractile spores were produced in each case; a portion of the barium spores lost refractility and darkened. Thin-section electron micrographs revealed no apparent anatomical differences among the three types of spores. Analyses revealed that the different spore types were enriched specifically in the metal to which they were exposed during sporogenesis. The calcium content of the strontium and the barium spores was very small. From binary equimolar mixtures of the metal salts, endotrophic spores accumulated both metals to nearly the same extent. Viability of the barium spores was considerably less than that of the other two types. Strontium and barium spores were heat-resistant; however, calcium was essential for maximal heat resistance. Significant differences existed in the rates of germination; calcium spores germinated fastest, strontium spores were slower, and barium spores were slowest. Calcium-barium and calcium-strontium spores germinated readily. Endotrophic calcium and strontium spores germinated without the prior heat activation essential for growth spores. Chemical germination of the different metal-type spores with n-dodecylamine took place at the same relative rates as physiological germination. Heat-induced release of dipicolinic acid occurred much faster with barium and strontium spores than with calcium spores. The washed “coat fraction” from disrupted spores contained little of the spore calcium but most of the spore barium. The metal in this fraction was released by dilute acid. The demineralized coats reabsorbed calcium and barium at neutral pH. Images PMID:4956334

Hematological, biochemical, and histopathological impacts of barium chloride and barium carbonate accumulation in soft tissues of male Sprague-Dawley rats.

PubMed

Mohammed, Amany Tharwat; Ismail, Hager Tarek H

2017-12-01

The present study was designed to investigate the hematotoxicity, sero-biochemical and histological changes due to the accumulation of BaCl 2 and BaCO 3 , the most important barium salts in our daily lives, in different soft tissues including the liver, kidney, heart, and spleen of adult rats after an oral exposure for 30 consecutive days, and to explain the different mechanisms by which this metal can exert these impacts. For this purpose, adult male rats were divided into three main groups of 15 animals each: group I, serving as controls, group II, receiving BaCl 2 orally in a dose of 179 mg barium/kg b.wt, and group III, receiving BaCO 3 orally in a dose of 418 mg barium/kg b.wt. for 30 consecutive days. Obviously, normocytic normochromic anemia was evident in both barium groups. Serum biochemical analysis revealed significant declines in glutathione peroxidase, catalase, superoxide dismutase, and urea with significant elevations in malondialdehyde, lactate dehydrogenase, and creatine kinase levels. Hyperphosphatemia, hypokalemia, hypocalcemia, and hypochloremia were also evident in both barium groups. Besides, residual analysis of both barium salts in different body organs revealed significantly abundant barium residues in the liver, spleen, heart, and kidney, respectively in both barium salts groups. Moreover, splenic tissue showed hemosiderosis, peritubular congestion, and necrotic glomeruli with intratubular hemorrhage. Sever subepicardial congestion with intramuscular edema was evident in the heart. In conclusion, BaCl 2 and BaCO 3 were able to deliver mortalities, antioxidant enzymes exhaustion, and a sort of normocytic normochromic anemia, as well as marked disturbances in cardiac, hepatic, and renal functions due to the accumulation of these two salts in the soft tissues. Therefore, these results demonstrate the unrecognized toxicity of those two barium salts due to their accumulation in various soft tissues of the body and so, this needs to reconsider about barium exposure.

UV-emitting phosphors: synthesis, photoluminescence and applications

NASA Astrophysics Data System (ADS)

Thakare, D. S.; Omanwar, S. K.; Muthal, P. L.; Dhopte, S. M.; Kondawar, V. K.; Moharil, S. V.

2004-02-01

UV-emitting phosphors find uses in various applications, such as photocopying, phototherapy, sun tanning, etc. The phosphor requirements for these applications vary. Simple methods for preparing different UV-emitting phosphors are described. Novel syntheses for some borates (SrB4O7:Eu, CeMgB5O10:Gd, GdBO3:Pr, LaB3O6:Ce,Bi, LaB3O6:Gd,Bi, LaB3O6:Ce, Ba2B5O9Cl:Eu), a silicate (Ba2SiO5:Pb), phosphates (Sr2-xMgxP2O7:Eu) and a sulphate (CaSO4:Eu) are reported. Photoluminescence spectra of the phosphors so prepared are presented and discussed in the context of applications like phototherapy and photocopying lamps, photoluminescent liquid crystal displays, radiophotoluminescence, etc.

Unusual stoichiometry control in the atomic layer deposition of manganese borate films from manganese bis(tris(pyrazolyl)borate) and ozone

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

Klesko, Joseph P.; Bellow, James A.; Saly, Mark J.

The atomic layer deposition (ALD) of films with the approximate compositions Mn{sub 3}(BO{sub 3}){sub 2} and CoB{sub 2}O{sub 4} is described using MnTp{sub 2} or CoTp{sub 2} [Tp = tris(pyrazolyl)borate] with ozone. The solid state decomposition temperatures of MnTp{sub 2} and CoTp{sub 2} are ∼370 and ∼340 °C, respectively. Preparative-scale sublimations of MnTp{sub 2} and CoTp{sub 2} at 210 °C/0.05 Torr afforded >99% recoveries with <0.1% nonvolatile residues. Self-limited ALD growth was demonstrated at 325 °C for MnTp{sub 2} or CoTp{sub 2} with ozone as the coreactant. The growth rate for the manganese borate process was 0.19 Å/cycle within the ALD window of 300–350 °C. The growth ratemore » for the cobalt borate process was 0.39–0.42 Å/cycle at 325 °C. X-ray diffraction of the as-deposited films indicated that they were amorphous. Atomic force microscopy of 35–36 nm thick manganese borate films grown within the 300–350 °C ALD window showed root mean square surface roughnesses of 0.4–0.6 nm. Film stoichiometries were assessed by x-ray photoelectron spectroscopy and time of flight-elastic recoil detection analysis. The differing film stoichiometries obtained from the very similar precursors MnTp{sub 2} and CoTp{sub 2} are proposed to arise from the oxidizing ability of the intermediate high valent manganese oxide layers and lack thereof for cobalt.« less

Optical absorption and photoluminescence properties of Er3+ doped mixed alkali borate glasses.

PubMed

Ratnakaram, Y C; Kumar, A Vijaya; Naidu, D Tirupathi; Rao, J L

2005-07-01

An investigations of the optical absorption and fluorescence spectra of 0.2 mol% Er2O3 in mixed alkali borate glasses of the type 67.8B2O3 x xLi2O(32-x)Na2O, 67.8B2O3 x xLi2O(32-x)K2O and 67.8B2O3 x xNa2O(32-x)K2O (where x = 8, 12, 16, 20 and 24) are presented. The glasses were obtained by quenching melts consisting of H3BO3, Li2CO3, Na2CO3, K2CO3 and Er2O3 (950-1100 degrees C, 1.5-2 h) between two brass plates. Spectroscopic parameters like Racah (E1, E2 and E3), spin-orbit (xi(4f)) and configuration interaction (alpha) parameters are deduced as function of x. Using Judd-Ofelt theory, Judd-Ofelt intensity parameters (omega2, omega4 and omega6) are obtained. Radiative and non-radiative transition rates (A(T) and W(MPR)), radiative lifetimes (tauR), branching ratios (beta) and integrated absorption cross-sections (sigma) have been computed for certain excited states of Er3+ in these mixed alkali borate glasses. Emission spectra have been studied for all the three Er3+ doped mixed alkali borate glasses. The present paper throws light on the trends observed in the intensity parameters, radiative lifetimes, branching ratios and emission cross-sections as a function of x in these borate glasses, keeping in view the effect of mixed alkalies in borate glasses.

Postprandial fullness correlates with rapid inflow of gastric content into duodenum but not with chronic gastritis

PubMed Central

2011-01-01

Background The aim of this study is evaluating the correlation of postprandial fullness with chronic gastritis or rapid inflow of gastric content into duodenum, based on double-contrast barium X-ray imaging. Methods 253 healthy subjects who underwent upper gastrointestinal barium X-ray examination were analyzed. Chronic gastritis was judged from mucosal atrophy and hypertrophic thickened folds on barium X-ray images. For the gastric excretion, the tips of barium flow on the single-contrast frontal barium X-ray images of the stomach were classified into four categories; V type (all the barium remained in the stomach), V-H type (some barium had flowed into the duodenum but the tip of barium remained in the proximal half of the duodenal bulb), H-V type (some barium had flowed into the duodenum and the tip of barium was in the distal half of duodenal the bulb, but no barium was observed in the descending part of the duodenum), and H type (some barium had flowed into the descending part of the duodenum). The chi-square test and Cochran-Mantel-Haenzel test were used for evaluation. Results Chronic gastritis was observed in 72 subjects, among which 21 subjects (29.2%) presented with postprandial fullness. For the remaining 181 subjects without chronic gastritis, 53 subjects (29.3%) complained of postprandial fullness. There is no significant correlation between chronic gastritis and postprandial fullness (p = 0.973). For the rapid flow of gastric content into duodenum, all the 253 subjects comprised 136 subjects with V type (in the stomach), 40 subjects with V-H type (in the proximal half of the duodenal bulb), 21 subjects with H-V type (in the distal half of the duodenal bulb), and 56 subjects with H type (in the descending part of the duodenum). Postprandial fullness was present in 30 subjects with V type (22.1%), 9 subjects with V-H type (22.5%), 8 subjects with H-V type (38.1%), and 27 subjects with H type (48.2%). There is a distinct correlation between postprandial fullness and gastric barium excretion on barium X-ray imaging (p = 0.002). Conclusions Bothersome postprandial fullness correlates with rapid inflow of gastric content into duodenum, but not with chronic gastritis. PMID:22189089

Barium enema

MedlinePlus

Lower gastrointestinal series; Lower GI series; Colorectal cancer - lower GI series; Colorectal cancer - barium enema; Crohn disease - lower GI series; Crohn disease - barium enema; Intestinal blockage - lower GI series; Intestinal ...

21 CFR 201.304 - Tannic acid and barium enema preparations.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished liver...

21 CFR 201.304 - Tannic acid and barium enema preparations.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished liver...

21 CFR 201.304 - Tannic acid and barium enema preparations.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished liver...

49 CFR 173.182 - Barium azide-50 percent or more water wet.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 2 2013-10-01 2013-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or more...

Barium release system

NASA Technical Reports Server (NTRS)

Lewis, B. W.; Stokes, C. S.; Smith, E. W.; Murphy, W. J. (Inventor)

1973-01-01

A chemical system is described for releasing a good yield of free barium neutral atoms and barium ions in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium. The barium is released in the vapor phase so that it can be ionized by solar radiation and also be excited to emit resonance radiation in the visible range. The ionized luminous cloud of barium becomes a visible indication of magnetic and electrical characteristics in space and allows determination of these properties over relatively large areas at a given time.

Dosimetric properties of dysprosium doped lithium borate glass irradiated by 6 MV photons

NASA Astrophysics Data System (ADS)

Ab Rasid, A.; Wagiran, H.; Hashim, S.; Ibrahim, Z.; Ali, H.

2015-07-01

Undoped and dysprosium doped lithium borate glass system with empirical formula (70-x) B2O3-30 Li2O-(x) Dy2O3 (x=0.1, 0.3, 0.5, 0.7, 1.0 mol%) were prepared using the melt-quenching technique. The dosimetric measurements were performed by irradiating the samples to 6 MV photon beam using linear accelerator (LINAC) over a dose range of 0.5-5.0 Gy. The glass series of dysprosium doped lithium borate glass produced the best thermoluminescence (TL) glow curve with the highest intensity peak from sample with 1.0 mol% Dy2O3 concentration. Minimum detectable dose was detected at 2.24 mGy, good linearity of regression coefficient, high reproducibility and high sensitivity compared to the undoped glass are from 1.0 mol% dysprosium doped lithium borate glass. The results indicated that the series of dysprosium doped lithium glasses have a great potential to be considered as a thermoluminescence dosimetry (TLD).

Reliability of Monte Carlo simulations in modeling neutron yields from a shielded fission source

NASA Astrophysics Data System (ADS)

McArthur, Matthew S.; Rees, Lawrence B.; Czirr, J. Bart

2016-08-01

Using the combination of a neutron-sensitive 6Li glass scintillator detector with a neutron-insensitive 7Li glass scintillator detector, we are able to make an accurate measurement of the capture rate of fission neutrons on 6Li. We used this detector with a 252Cf neutron source to measure the effects of both non-borated polyethylene and 5% borated polyethylene shielding on detection rates over a range of shielding thicknesses. Both of these measurements were compared with MCNP calculations to determine how well the calculations reproduced the measurements. When the source is highly shielded, the number of interactions experienced by each neutron prior to arriving at the detector is large, so it is important to compare Monte Carlo modeling with actual experimental measurements. MCNP reproduces the data fairly well, but it does generally underestimate detector efficiency both with and without polyethylene shielding. For non-borated polyethylene it underestimates the measured value by an average of 8%. This increases to an average of 11% for borated polyethylene.

Borate cross-linking chitosan/graphene oxide films: Toward the simultaneous enhancement of gases barrier and mechanical properties

NASA Astrophysics Data System (ADS)

Yan, Ning; Capezzuto, Filomena; Buonocore, Giovanna G.; Tescione, Fabiana; Lavorgna, Marino; Xia, Hesheng; Ambrosio, Luigi

2015-12-01

Borate adducts, originated from hydrolysis of sodium tetraborate decahydrate (borax), have been used to crosslink chitosan (CS) and graphene oxide (GO) nanosheets for the production of innovative composite sustainable materials. CS/GO film consisting of 10wt% borax and 1wt% GO exhibits a significant improvement of both toughness and oxygen barrier properties in comparison to pristine chitosan. In particular the tensile strength increases by about 100% and 150% after thermal annealing of samples at 90°C for 50min whereas the oxygen permeability reduces of about 90% compared to pristine chitosan. The enhancement of both mechanical and barrier properties is ascribed to the formation of a resistant network due to the chemical crosslinking, including borate orthoester bonds and hydroxyl moieties complexes, formed among borate ions, chitosan, and GO nanoplatelets. The crosslinked graphene-based chitosan material with its enhanced mechanical and barrier properties may significantly broad the range of applications of chitosan based-materials which presently are very limited and addressed only to packaging.

D-Tagatose production in the presence of borate by resting Lactococcus lactis cells harboring Bifidobacterium longum L-arabinose isomerase.

PubMed

Salonen, Noora; Salonen, Kalle; Leisola, Matti; Nyyssölä, Antti

2013-04-01

Bifidobacterium longum NRRL B-41409 L-arabinose isomerase (L-AI) was overexpressed in Lactococcus lactis using a phosphate depletion inducible expression system. The resting L. lactis cells harboring the B. longum L-AI were used for production of D-tagatose from D-galactose in the presence of borate buffer. Multivariable analysis suggested that high pH, temperature and borate concentration favoured the conversion of D-galactose to D-tagatose. Almost quantitative conversion (92 %) was achieved at 20 g L⁻¹ substrate and at 37.5 °C after 5 days. The D-tagatose production rate of 185 g L⁻¹ day ⁻¹ was obtained at 300 g L⁻¹ galactose, at 1.15 M borate, and at 41 °C during 10 days when the production medium was changed every 24 h. There was no significant loss in productivity during ten sequential 24 h batches. The initial D-tagatose production rate was 290 g L⁻¹ day⁻¹ under these conditions.

Vibrational spectroscopy of the borate mineral kotoite Mg₃(BO₃)₂.

PubMed

Frost, Ray L; Xi, Yunfei

2013-02-15

Vibrational spectroscopy has been used to assess the structure of kotoite a borate mineral of magnesium which is isostructural with jimboite. The mineral is orthorhombic with point group: 2/m 2/m 2/m. The mineral has the potential as a new memory insulator material. The mineral has been characterised by a combination of Raman and infrared spectroscopy. The Raman spectrum is dominated by a very intense band at 835 cm(-1), assigned to the symmetric stretching mode of tetrahedral boron. Raman bands at 919, 985 and 1015 cm(-1) are attributed to the antisymmetric stretching modes of tetrahedral boron. Kotoite is strictly an hydrous borate mineral. An intense Raman band observed at 3559 cm(-1) is attributed to the stretching vibration of hydroxyl units, more likely to be associated with the borate mineral hydroxyborate. The lack of observation of water bending modes proves the absence of water in the kotoite structure. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation of passive films formed on the surface of alloy 690 in borate buffer solution

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Wenli, Guo

2015-10-01

The passive film formed on the surface of the alloy 690 in borate buffer solution was studied by potentiodynamic curves and electrochemical impedance spectroscopy. With the increasing of the passivation potential, the corrosion resistance of the alloy 690 reduced. Moreover, the corrosion resistance of the passive film was the lowest in the vicinity of 0.6 VSCE. These results were supported by XPS and Mott-Schottky analyses. The corrosion resistance of the alloy 690 increased with the increasing of passivated potential in borate buffer solution with chloride ion. The chloride ion decreased corrosion resistance of the alloy 690 according to point defect model.

[Investigations of the efficacy and bio-availability of different pilocarpine eye drops].

PubMed

Tapasztó, I; Boross, F

1982-01-01

The efficacy of three pilocarpine preparations in different concentrations (pilocarpine borate 0.5%, 1%, 2%; pilocarpine hydrochloride 0.5%, 1%, 2%; pilocarpine nitrate 1%, 2%) was investigated in 57 glaucomatous patients. Pilocarpine borate reduced intraocular pressure more effectively than either of the other pilocarpine solutions. The 2% concentration had a particularly prolonged effect. This finding corresponded well with pilocarpine levels in the aqueous humour of rabbits, as determined by spectrophotometric analysis. Pilocarpine borate 2% revealed an almost two-fold amount of drug compared to the 2% hydrochloride and nitrate solutions, and a detectable pilocarpine level was present for a longer period as well.

Molecular ferroelectrics: where electronics meet biology.

PubMed

Li, Jiangyu; Liu, Yuanming; Zhang, Yanhang; Cai, Hong-Ling; Xiong, Ren-Gen

2013-12-28

In the last several years, we have witnessed significant advances in molecular ferroelectrics, with the ferroelectric properties of molecular crystals approaching those of barium titanate. In addition, ferroelectricity has been observed in biological systems, filling an important missing link in bioelectric phenomena. In this perspective, we will present short historical notes on ferroelectrics, followed by an overview of the fundamentals of ferroelectricity. The latest developments in molecular ferroelectrics and biological ferroelectricity will then be highlighted, and their implications and potential applications will be discussed. We close by noting molecular ferroelectric as an exciting frontier between electronics and biology, and a number of challenges ahead are also described.

Enhancing the detector for advanced neutron capture experiments

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

Couture, A.; Mosby, S.; Baramsai, B.

2015-05-28

The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We, thus, report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. Furthermore, the upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

Understanding the photoluminescence characteristics of Eu{sup 3+}-doped double-perovskite by electronic structure calculation

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

Ghosh, Binita; Halder, Saswata; Sinha, T. P.

2016-05-23

Europium-doped luminescent barium samarium tantalum oxide Ba{sub 2}SmTaO{sub 6} (BST) has been investigated by first-principles calculation, and the crystal structure, electronic structure, and optical properties of pure BST and Eu-doped BST have been examined and compared. Based on the calculated results, the luminescence properties and mechanism of Eu-doped BST has been discussed. In the case of Eu-doped BST, there is an impurity energy band at the Fermi level, which is formed by seven spin up energy levels of Eu and act as the luminescent centre, which is evident from the band structure calculations.

Radio frequency surface resistance of Tl-Ba-Ca-Cu-O films on metal and single-crystal substrates

NASA Astrophysics Data System (ADS)

Arendt, P. N.; Reeves, G. A.; Elliott, N. E.; Cooke, D. W.; Gray, E. R.; Houlton, R. J.; Brown, D. R.

1990-01-01

Films of Tl-Ba-Ca-Cu were dc magnetron sputtered from a single multielement target. The films were deposited onto substrates of: (1) magnesium oxide, (2) a silver based alloy (Consil 995), (3) a nickel based alloy (Haynes 230), and (4) buffer layers of barium fluoride or copper oxide on Consil. To form superconducting phases, post-deposition anneals were made on these films using an alumina crucible with an over pressure of thallium and flowing oxygen. After annealing, the film phases were determined using x-ray diffraction. The film surface resistances (Rs) were measured at 22 GHz in a TE011 cavity.

Microgravity

NASA Image and Video Library

1998-02-05

Sections of ZBLAN fibers pulled in a conventional 1-g process (left) and in experiments aboard NASA's KC-135 low-gravity aircraft. The rough surface of the 1-g fiber indicates surface defects that would scatter an optical signal and greatly degrade its quality. ZBLAN is part of the family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium). NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. ZBLAN is a heavy-metal fluoride glass that shows exceptional promise for high-throughput communications with infrared lasers. Photo credit: NASA/Marshall Space Flight Center

Molecular ferroelectrics: where electronics meet biology

PubMed Central

Li, Jiangyu; Liu, Yuanming; Zhang, Yanhang; Cai, Hong-Ling; Xiong, Ren-Gen

2013-01-01

In the last several years, we have witnessed significant advances in molecular ferroelectrics, with ferroelectric properties of molecular crystals approaching those of barium titanate. In addition, ferroelectricity has been observed in biological systems, filling an important missing link in bioelectric phenomena. In this perspective, we will present short historical notes on ferroelectrics, followed by overview on the fundamentals of ferroelectricity. Latest development in molecular ferroelectrics and biological ferroelectricity will then be highlighted, and their implications and potential applications will be discussed. We close by noting molecular ferroelectric as an exciting frontier between electronics and biology, and a number of challenges ahead are also noted. PMID:24018952