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1

Optical properties of gadolinium gallium garnet.  

PubMed

The refractive index, the temperature coefficient of the refractive index, and the optical transparency of gadolinium gallium garnet are reported as a function of wavelength from the near UV to the middle IR. The materialis transparent enough for good optical components between 0.36 and 6.0 microm, and the refractive index ranges from 2.0 at the UV end to 1.8 at the IR end of the spectrum. The wavelength dependence of index is expressed as a three-term Sellmeier formula with agreement better than two parts in the fourth decimal between calculated and experimental values. Variations in composition depending on growth from various melts (e.g., stoichiometric vs congruent) have no effect on the optical parameters at this level of precision. PMID:20567472

Wood, D L; Nassau, K

1990-09-01

2

Gadolinium Gallium Garnet at Multi-Megabar Pressures  

NASA Astrophysics Data System (ADS)

Gadolinium gallium oxide Gd3Ga5O12, which crystallizes in the garnet structure, has recently attracted strong interest due to shock-wave experiments revealing a highly incompressible high-pressure phase above 1 Mbar [1]. In addition, recent diamond-cell x-ray diffraction experiments provide evidence for a phase transition from garnet to double-perovskite structures around 1 Mbar [2]. We present the results of laser-driven shock experiments on gadolinium gallium garnet (GGG) at pressures of 3 to more than 20 Mbar, obtained at the Omega-LLE and Jupiter-LLNL facilities, and compare these with the results of ab-initio molecular dynamic simulations. Velocimetry (VISAR) and pyrometry (SOP) diagnostics, and an impedance match analysis with quartz standards, provide data on the equation of state, temperature and optical reflectivity at 532 nm. No obvious phase transition is detected in the explored pressure range, but the data indicate that GGG remains surprisingly stiff up to more than 20 Mbar. We observe metallic-like reflectivity in the ultra-high pressure (possibly liquid) regime. This study could be relevant for planetary interior modeling, as many Earth and super-Earth minerals adopt the garnet and perovskite structures, and may exhibit transition to metallic and highly incompressible behavior.

Millot, M.; Ali, S. J.; Militzer, B.; Barrios, M. A.; Boehly, T.; Eggert, J. H.; Collins, G.; Jeanloz, R.

2011-12-01

3

Spectroscopic, optical, and thermomechanical properties of neodymium- and chromium-doped gadolinium scandium gallium garnet  

Microsoft Academic Search

Spectroscopic, optical, and thermomechanical properties of gadolinium scandium gallium garnet doped with trivalent neodymium and\\/or chromium are reported for use in the design of high-power solid-state lasers.

W. F. Krupke; M. D. Shinn; J. E. Marion; J. A. Caird; S. E. Stokowski

1986-01-01

4

Electromagnetic excitation of ultrasonic oscillations by yttrium iron garnet films on gallium gadolinium garnet substrates  

NASA Astrophysics Data System (ADS)

We have studied the phenomenon of contactless excitation of ultrasonic oscillations by thin yttrium iron garnet (YIG) films on gallium gadolinium garnet (GGG) substrates upon application of the superposition of a constant magnetic bias field and alternating magnetic field. Dimensional resonance effects that cannot be explained in the framework of existing theoretical notions have been discovered, in particular, in dependences of the amplitude of excited longitudinal oscillations on the YIG film thickness, frequency of ultrasound, and degree of homogeneity and strength of the magnetic bias field. It is suggested that the observed phenomenon is caused by resonant participation of the intrinsic oscillations of domain walls in the excitation of ultrasound.

Sarnatskii, V. M.; Mavlonazarov, I. O.; Lutsev, L. V.

2014-07-01

5

Optical absorption of Ni2+ and Ni3+ ions in gadolinium gallium garnet epitaxial films  

NASA Astrophysics Data System (ADS)

Single-crystal Ni-doped gadolinium gallium garnet films were grown for the first time from supercooled Bi2O3-B2O3-based melt solutions by liquid-phase epitaxy. Optical absorption bands due to Ni2+, Ni3+ and Bi3+ ions were observed in those films. Interpretation and tabulation of all absorption bands of nickel ions occupying octahedral and tetrahedral sites in the garnet lattice are presented.

Vasileva, N. V.; Gerus, P. A.; Sokolov, V. O.; Plotnichenko, V. G.

2012-12-01

6

Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet  

SciTech Connect

Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

Murphy, R.W.

1994-12-01

7

Light-induced phase and amplitude gratings in centrosymmetric Gadolinium Gallium garnet doped with calcium.  

PubMed

The photosensitive properties of a centrosymmetric gadolinium gallium garnet crystal doped with calcium are investigated at room temperature. Elementary holograms can be recorded over a wide range of wavelengths in the visible spectral range. The photosensitive properties are studied experimentally using beam coupling and angular response experiments. Mixed absorption and refractive-index gratings are observed and their amplitudes and relative phases determined. Moreover, the candidate centers that are responsible for the photorefractive effect are discussed. PMID:19503376

Ellabban, Mostafa A; Fally, Martin; Rupp, Romano A; Kovács, László

2006-01-23

8

Modification of the crystal structure of gadolinium gallium garnet by helium ion irradiation  

NASA Astrophysics Data System (ADS)

The structure of gadolinium gallium garnet (GGG) single crystals before and after implantation by He+ ions has been investigated using high-resolution X-ray diffraction methods and the generalized dynamic theory of X-ray scattering. The main types of growth defects in GGG single crystals and radiation-induced defects in the ion-implanted layer have been determined. It is established that the concentration of dislocation loops in the GGG surface layer modified by ion implantation increases and their radius decreases with an increase in the implantation dose.

Ostafiychuk, B. K.; Yaremiy, I. P.; Yaremiy, S. I.; Fedoriv, V. D.; Tomyn, U. O.; Umantsiv, M. M.; Fodchuk, I. M.; Kladko, V. P.

2013-12-01

9

Spectroscopy of gadolinium gallium garnet crystals doped with Y b3 + revisited  

NASA Astrophysics Data System (ADS)

The optical spectroscopy measurements of gadolinium gallium garnet (GGG) crystals doped with Yb show evidence of the presence of non-equivalent optical centers with very similar radiative decay rates. The energy level schemes of those centers have been determined on the basis of optical absorption, luminescence and Raman experiments. Crystal field fitting resulted in two sets of slightly different crystal field parameters for two non-equivalent Yb centers. Both sets of parameters describe perfectly the experimentally detected Y b3 + energy levels. Correlation between systematic trends in the experimental energy level schemes and crystal field parameters is discussed.

Kami?ska, A.; Brik, M. G.; Boulon, G.; Karbowiak, M.; Suchocki, A.

2010-06-01

10

Effects of doping on the geometrically frustrated Heisenberg antiferromagnet Gadolinium Gallium Garnet  

NASA Astrophysics Data System (ADS)

Geometric frustration in the Heisenberg antiferromagnet Gadolinium Gallium Garnet (GGG) gives rise to a set of quantum protectorates where clusters of spins decouple from the overall spin liquid state. At 110 mK, there is a partial transition to an ordered AF state. Here, we examine the effect of lightly doping GGG with Nd ions, which partially alleviates the underlying frustration. We examine the size and binding energy of the spin clusters as a function of doping and temperature, and also characterize the suppression of the Neel temperature as the dopant concentration is increased.

Silevitch, D. M.; Schmidt, M. A.; Ghosh, S.; Aeppli, G.; Rosenbaum, T. F.

2011-03-01

11

Spectroscopy of gadolinium gallium garnet crystals doped with Yb(3+) revisited.  

PubMed

The optical spectroscopy measurements of gadolinium gallium garnet (GGG) crystals doped with Yb show evidence of the presence of non-equivalent optical centers with very similar radiative decay rates. The energy level schemes of those centers have been determined on the basis of optical absorption, luminescence and Raman experiments. Crystal field fitting resulted in two sets of slightly different crystal field parameters for two non-equivalent Yb centers. Both sets of parameters describe perfectly the experimentally detected Yb(3+) energy levels. Correlation between systematic trends in the experimental energy level schemes and crystal field parameters is discussed. PMID:21393800

Kami?ska, A; Brik, M G; Boulon, G; Karbowiak, M; Suchocki, A

2010-06-30

12

Spectral Signature of Neodymium Dopants in Frustrated Gadolinium Gallium Garnet Lattice  

NASA Astrophysics Data System (ADS)

We investigate the spectral emission of Nd3+ dopant ions (1% at. wt) in the frustrated magnet Gadolinium gallium Garnet (GGG) as a function of temperature and magnetic field. We concentrate on the low energy excitations centered at 1064 nm and 935 nm, which show a multiplet structure at room temperature. As temperature decreases the emission spectra demonstrate changes in relative intensities that undergo a cross-over at 122 K under zero field cooled conditions. This cross-over is magnetic field dependent and changes as we field-cool the sample. Typically, with decreasing temperature the line widths of the spectral peaks decrease, as is expected. However, when cooled below 10 K selective peaks start exhibiting broadening, even when zero-field cooled. We follow this line broadening as a function of magnetic field and dopant concentration and speculate it is a result of the dopant ions coupling to the internal magnetic fields of the host lattice.

Ferri, Christopher; Tennenbaum, Michael; Ghosh, Sayantani

2012-02-01

13

An experimental search for the electron Electric Dipole Moment in Gadolinium Gallium Garnet  

NASA Astrophysics Data System (ADS)

A discovery of a permanent electric dipole moment of the electron (eEDM) would provide crucial information about the nature of T-violation and imply new sources of CP-violation beyond the Standard Model. While the leading experimental technique used to measure EDM is based on the nuclear magnetic resonance, we are pursuing research that would improve the present experimental limit of the eEDM using a new technique in solid-state systems at low temperatures. The experiment uses a paramagnetic insulator Gadolinium Gallium Garnet with a large magnetic response. The presence of the eEDM leads to a finite magnetization when the garnet sample is subjected to a strong electric field. The resulting magnetization can be measured using the Superconducting Quantum Interference Device (SQUID) as a sensitive magnetometer. In this talk, we will discuss the progress to control the systematic effects and improve the sensitivity. The major efforts include the design and implementation of a 24-bit data acquisition system with ultra-low level of channel crosstalk, and the control of the high voltage drift from the supply. With these considerable progresses, we report our first background-free experimental limit of the eEDM on the order of 10-24 e.cm .

Kim, Young Jin; Liu, Chen-Yu

2011-04-01

14

Epitaxial Growth of Atomically Flat Yttrium Iron Garnet Thin Films on Gadolinium Gallium Garnet by Pulse Laser Deposition  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) is a ferrimagnetic insulator which is useful for magneto-optical, microwave, and more recently spintronic devices. Pulsed laser deposition (PLD) has emerged as a preferred technique to deposit complex oxide thin films, heterostructures, and superlattices with high quality. Deposition of YIG films using PLD has been reported by several groups. The layer-by-layer growth mode has been achieved with a high laser repetition rate. No details about surface morphology were discussed. Here we report our approach to grow YIG films with thickness ranging from 10 to 100 nm on (110)- and (111)-oriented gadolinium gallium garnet (GGG) substrates. In both orientations, we have successfully grown epitaxial YIG thin films confirmed by the patterns of the reflection high-energy electron diffraction. The magnetic properties are measured by a vibrating sample magnetometer. The in-plane easy-axis coercivity is less than 1 Oe, while the perpendicular saturation field is ˜ 2000 Oe. For both orientations, the atomic force microscopy images show that the YIG surface is extremely flat with roughness ˜ 0.6å. Flat terraces are found with the atomic step height in films with both orientations. This work paves the way to engineering anisotropy of the thin films for YIG-based magnetic devices.

Lin, Tao; Tang, Chi; Shi, Jing

2013-03-01

15

[Optical and spectral parameters in Ce3+ -doped gadolinium gallium aluminum garnet glass-ceramics].  

PubMed

The crystalline phases of Ce3+ -doped gadolinium gallium aluminum garnet (GGAG) glass-ceramics were investigated by X-ray diffraction, and the fluorescence spectra were recorded under the pumping of blue light-emitting diode (LED) using an integrating sphere of 10-inch in diameter, which connected to a CCD detector. The spectral power distribution of the glass-ceramics was obtained from the measured spectra first, and then the quantum yield was derived based on the photon distribution. The quantum yield of Ce3+ emission in GGAG glass-ceramics is 29.2%, meanwhile, the color coordinates and the correlated color temperature (CCT) of combined white light were proved to be x = 0.319, y = 0.349 and 6086 K, respectively. Although the quantum yield is a little smaller than the value in Ce3+ -doped YAG glass-ceramics, the CCT of the combined white light is much smaller than that in the latter. The optical behavior of GGAG glass-ceramics provides new vision for developing comfortable LED lighting devices. PMID:20302098

Gong, Hua; Zhao, Xin; Yu, Xiao-bo; Setsuhisa, Tanabe; Lin, Hai

2010-01-01

16

Visible upconversion emission of Pr3+ doped gadolinium gallium garnet nanocrystals.  

PubMed

The luminescence properties of a Pr3+-doped gadolinium gallium garnet (GGG, Gd3Ga5O12) nanocrystalline host were investigated. Dominant blue/green emission was observed emanating from the 3P0 --> 3H4 transition after excitation using a wavelength of 457.9 nm. Continuous wave excitation into the 1D2 level of the Pr3+ ion at 606.9 nm transition produced blue upconversion luminescence spectra, ascribed to emission from the 3P1 --> 3H4 and 3P0 --> 3H4 transitions. The increase in the decay times of the observed transitions following excitation with 606.9 nm is indicative of the dominance of an energy transfer upconversion (ETU) mechanism relative to excited state absorption (ESA). Furthermore, blue, green and red upconversion emission was observed from the 3P0, 3P1 and 1D2 states following excitation into the 1G4 energy level with 980 nm. No change in the decay times of the emitting states was observed following excitation with a wavelength of 980 or 457.9 nm; hence, upconversion was determined to primarily occur through ESA. The luminescence properties of the nanocrystals are compared to a single crystal of GGG:Pr3+ (bulk) with an identical Pr3+ concentration (1%). PMID:15656197

Naccache, R; Vetrone, F; Boyer, J C; Capobianco, J A; Speghini, A; Bettinelli, M

2004-11-01

17

A diode-pumped Nd3+-doped gadolinium gallium garnet quasi-three-level laser at 933 nm  

NASA Astrophysics Data System (ADS)

We report for the first time a Nd3+-doped gadolinium gallium garnet (Nd:GGG) laser operating on a quasi-three-level laser at 933 nm, based on the 4F3/2–4I9/2 transition. Continuous wave 691 mW output power at 933 nm is obtained under 10.2 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a blue power of 89 mW by using a LiB3O5 (LBO) nonlinear crystal.

Liu, J. H.; Han, Y. H.; Zhao, Y. D.

2013-11-01

18

Enhancement of the electron electric dipole moment in gadolinium garnets  

Microsoft Academic Search

Effects caused by the electron electric dipole moment (EDM) in gadolinium garnets are considered. Experimental studies of these effects could improve the current upper limit on the electron EDM by several orders of magnitude. We suggest a consistent theoretical model and perform calculations of observable effects in gadolinium gallium garnet and gadolinium iron garnet. Our calculation accounts for both direct

T. N. Mukhamedjanov; V. A. Dzuba; O. P. Sushkov

2003-01-01

19

Enhancement of the electron electric dipole moment in gadolinium garnets  

SciTech Connect

Effects caused by the electron electric dipole moment (EDM) in gadolinium garnets are considered. Experimental studies of these effects could improve the current upper limit on the electron EDM by several orders of magnitude. We suggest a consistent theoretical model and perform calculations of observable effects in gadolinium gallium garnet and gadolinium iron garnet. Our calculation accounts for both direct and exchange diagrams.

Mukhamedjanov, T.N.; Dzuba, V.A.; Sushkov, O.P. [School of Physics, University of New South Wales, Sydney 2052 (Australia)

2003-10-01

20

Enhancement of the electron electric dipole moment in gadolinium garnets  

E-print Network

Effects caused by the electron electric dipole moment (EDM) in gadolinium garnets are considered. Experimental studies of these effects could improve current upper limit on the electron EDM by several orders of magnitude. We suggest a consistent theoretical model and perform calculations of observable effects in gadolinium gallium garnet and gadolinium iron garnet. Our calculation accounts for both direct and exchange diagrams.

T. N. Mukhamedjanov; V. A. Dzuba; O. P. Sushkov

2003-01-10

21

Evidence of multicenter structure of cerium ions in gadolinium gallium garnet crystals studied by infrared absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Low temperature, infrared absorption spectra of gadolinium gallium garnet crystals doped with Ce are presented. In the region of intraconfigurational 4f-4f transitions the spectra exhibit existence of at least two different, major Ce3+ related centers in the GGG crystals and also some other centers at lower concentration. The spectrum of 4f-4f intrashell transitions of Ce3+ ions extends up to about 3700 cm-1 due to the large splitting of the 2F7/2 excited state. In the visible region the absorption spectrum shows influence of symmetry-related selection rules. The absorption coefficient changes in the region of 4f1-5d1 transitions due to thermal population of the second level, belonging to the 2F5/2 ground state. This suggests that the symmetry of the site occupied by Ce3+ ions, which substitute Gd3+, is higher than D2 expected for garnet hosts.

Przybyli?ska, H.; Ma, Chong-Geng; Brik, M. G.; Kami?ska, A.; Szczepkowski, J.; Sybilski, P.; Wittlin, A.; Berkowski, M.; Jastrz?bski, W.; Suchocki, A.

2013-01-01

22

Thermal, spectroscopic and laser properties of Nd3+ in gadolinium scandium gallium garnet crystal produced by optical floating zone method  

NASA Astrophysics Data System (ADS)

A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of ? 5 × 20 mm2 has been grown by means of optical floating zone (OFZ). X-ray powder diffraction (XRPD) result shows that the as-grown Nd:GSGG crystal possesses a cubic structure with space group Ia3d and a cell parameter of a = 1.2561 nm. Effective elemental segregation coefficients of the Nd:GSGG as-grown crystal were calculated by using X-ray fluorescence (XRF). The thermal properties of the Nd:GSGG crystal were systematically studied by measuring the specific heat, thermal expansion and thermal diffusion coefficient, and the thermal conductivity of this crystal was calculated. The absorption and luminescence spectra of Nd:GSGG were measured at room temperature (RT). By using the Judd-Ofelt (J-O) theory, the theoretical radiative lifetime was calculated and compared with the experimental result. Continuous wave (CW) laser performance was achieved with the Nd:GSGG at the wavelength of 1062 nm when it was pumped by a laser diode (LD). A maximum output power of 0.792 W at 1062 nm was obtained with a slope efficiency of 11.89% under a pump power of 7.36 W, and an optical-optical conversion efficiency of 11.72%.

Tian, Li; Wang, Shuxian; Wu, Kui; Wang, Baolin; Yu, Haohai; Zhang, Huaijin; Cai, Huaqiang; Huang, Hui

2013-12-01

23

Merging of the 4F3/2 level states of Nd3+ ions in the photoluminescence spectra of gadolinium-gallium garnets under high pressure  

NASA Astrophysics Data System (ADS)

The 4F3/2 state of Nd3+ dopant ions is split due to the crystal field at orthorhombic D2 symmetry sites in several members of the garnet family of crystals. In the gadolinium-gallium garnet crystal this splitting is found to almost disappear under hydrostatic pressures between 8 and 11 GPa created in the diamond-anvil cell. This pressure is much lower than that required for the phase transition to the so called high-pressure phase. This effect is explained with help of x-ray diffraction, optical spectroscopy, and ab initio calculations as an effect of accidental near-degeneracy arising from a particular lattice structure of garnets.

Kaminska, A.; Buczko, R.; Paszkowicz, W.; Przybyli?ska, H.; Werner-Malento, E.; Suchocki, A.; Brik, M.; Durygin, A.; Drozd, V.; Saxena, S.

2011-08-01

24

A magnetically- and electrically-tunable microwave phase shifter using yttrium iron garnet/gadolinium gallium garnet thin film  

NASA Astrophysics Data System (ADS)

A new type of tunable microwave phase shifter that combines ferromagnetic resonance (FMR)-based magnetic tuning in a yttrium iron garnet-thin-film and DC electrical tuning in a varactor-loaded composite band-pass filter is reported. For the frequency range of 10.37 to 10.87 GHz, a phase shift of 147.5 to 280° was first obtained by applying a reversed bias voltage from 6 to 18 V, and the total phase shift was subsequently increased to 406.5° by varying the bias magnetic field from 2700 to 3450 Oe. The corresponding insertion loss variation measured ±1.5 dB. Similar performance figures could also be obtained for other frequency ranges by varying the bias magnetic field and the corresponding FMR frequency. Thus, the composite phase shifter has clearly demonstrated its capability for a large and continuously tunable phase shift with a moderate insertion loss variation over a wide range of operating frequencies.

Zhu, Yun; Qiu, Gang; Tsai, Chen S.

2012-04-01

25

Band-gap modulation via gallium substitution in cerium doped gadolinium aluminum garnet using a mixed fuel combustion approach  

NASA Astrophysics Data System (ADS)

Cerium doped Gadolinium garnets (Gd3AlxGa5-xO12 where 0?x?5) are synthesized via combustion synthesis using mixture of urea and glycine fuels. A 4h Post annealing at 1400 oC is found to be necessary for pure phase formation. Lattice spacing variation as a result of partial or total Ga substitution at Al site was mapped by X-ray diffraction. Photoluminescence emission of Ce shifts as a consequence of Ga substitution and therefore suggests a local re-adjustment of crystal field around activator site.

Tyagi, Mohit; Pitale, Shreyas S.; Ghosh, Manoranjan; Shinde, Seema

2014-04-01

26

Band-gap modulation via gallium substitution in cerium doped gadolinium aluminum garnet using a mixed fuel combustion approach  

SciTech Connect

Cerium doped Gadolinium garnets (Gd{sub 3}Al{sub x}Ga{sub 5?x}O{sub 12} where 0?x?5) are synthesized via combustion synthesis using mixture of urea and glycine fuels. A 4h Post annealing at 1400 oC is found to be necessary for pure phase formation. Lattice spacing variation as a result of partial or total Ga substitution at Al site was mapped by X-ray diffraction. Photoluminescence emission of Ce shifts as a consequence of Ga substitution and therefore suggests a local re-adjustment of crystal field around activator site.

Tyagi, Mohit; Pitale, Shreyas S.; Ghosh, Manoranjan; Shinde, Seema [Crystal Technology Section, Technical Physics Division, Bhabha Atomic Research Centre, Mumbai- 400085 (India)

2014-04-24

27

Static contribution to thermal shifts of spectral lines in gadolinium gallium garnet Gd3Ga5O12:Nd3+ laser crystal  

NASA Astrophysics Data System (ADS)

The static contribution due to lattice thermal expansion and the vibrational contribution due to electron-phonon interaction to the thermal shifts of the spectral lines E1(R1 ? Z5) and E2 (R2 ? Z5) in the high-power laser crystal gadolinium gallium garnet Gd3Ga5O12 (GGG):Nd3+ are studied by analyzing the observed pressure- and temperature-dependence of these spectral lines. It is found that the static contribution due to thermal expansion in magnitude is greater than, and it in sign is opposite to the vibrational contribution due to electron-phonon interaction. So for the theoretical study of thermal shifts of the spectral lines in GGG:Nd3+ and other similar "hard" crystals, the neglect of the contribution due to the lattice thermal expansion suggested in the previous papers is unsuitable.

Zheng, W. C.; Su, P.; Liu, H. G.

2011-03-01

28

Magnetocaloric Effect, Specific Heat, and Entropy of Iron-Substituted Gadolinium Gallium Garnets Gd3(Ga1-xFex)5O12  

NASA Astrophysics Data System (ADS)

A series of Gd3(Ga1-xFex)5O12 (GGIG) compounds for magnetic refrigerants were characterized by magnetization and specific heat measurements. For comparison, the base compound gadolinium gallium garnet (GGG) was also measured. From the magnetization measurements, the entropy change by external magnetic field was confirmed to be enhanced by the addition of iron, as previously reported by the National Institute of Standards and Technology (NIST) group. The specific heat data obtained in various magnetic fields enabled the establishment of temperature entropy (T-S) diagrams, which are essential for thermal cycle analysis. It has been shown that GGIGs with high iron content have a large specific heat in zero field, and are suitable for regenerative thermal cycle.

Matsumoto, Koichi; Matsuzaki, Ayumi; Kamiya, Koji; Numazawa, Takenori

2009-11-01

29

Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method  

SciTech Connect

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

Budenkova, O. N., E-mail: olganb@mail.ioffe.ru; Vasiliev, M. G.; Yuferev, V. S. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Ivanov, I. A.; Bul'kanov, A. M. [ZAO Research Institute of Materials Science (Russian Federation); Kalaev, V. V. [OOO Soft Impakt (Russian Federation)

2008-12-15

30

Growth of epitaxial bismuth and gallium substituted lutetium iron garnet films by pulsed laser deposition  

SciTech Connect

Epitaxial bismuth and gallium substituted lutetium iron garnet thin films have been grown on (100) oriented gadolinium gallium garnet Gd{sub 3}Ga{sub 5}O{sub 12} substrates by pulsed laser deposition. The films have been studied using x-ray diffraction, high resolution x-ray diffraction, Rutherford backscattering spectroscopy, transmission electron microscopy, and electron diffraction. We obtained smooth films with thicknesses between 0.3 and 1.0 {mu}m showing good crystalline quality and epitaxial growth.

Leitenmeier, Stephan; Heinrich, Andreas; Lindner, Joerg K. N.; Stritzker, Bernd [Institut fuer Physik, Universitaet Augsburg, D-86135 Augsburg (Germany)

2006-04-15

31

Gadolinium Iron Garnet as a Solid State Material for an Electron Electric Dipole Moment Search  

E-print Network

The possibility of a solid state electron electric dipole moment (EDM) experiment based on Gadolinium Iron Garnet (GdIG) is investigated. GdIG appears to exhibit superparamagnetism and this effect can be used to enhance the electric-field-induced EDM signal at relatively a high temperatures, as compared to a simple paramagnetic system such as Gadolinium Gallium Garnet. The sensitivity of a GdIG based experiment might be large enough that an improvement by over three orders of magnitude, compared to the existing electron EDM limit, could be obtained at a modest temperature of 4 K, assuming that the superparamagnetic effect is not suppressed at this temperature, and that the spin relaxation time remains sufficiently rapid.

Steve K. Lamoreaux

2007-03-16

32

Gadolinium Iron Garnet as a Solid State Material for an Electron Electric Dipole Moment Search  

E-print Network

The possibility of a solid state electron electric dipole moment (EDM) experiment based on Gadolinium Iron Garnet (GdIG) is investigated. GdIG appears to exhibit superparamagnetism and this effect can be used to enhance the electric-field-induced EDM signal at relatively a high temperatures, as compared to a simple paramagnetic system such as Gadolinium Gallium Garnet. The sensitivity of a GdIG based experiment might be large enough that an improvement by over three orders of magnitude, compared to the existing electron EDM limit, could be obtained at a modest temperature of 4 K, assuming that the superparamagnetic effect is not suppressed at this temperature, and that the spin relaxation time remains sufficiently rapid.

Lamoreaux, S K

2007-01-01

33

Optical pressure and temperature sensor based on the luminescence properties of Nd3+ ion in a gadolinium scandium gallium garnet crystal.  

PubMed

Hypersensitivity to pressure and temperature is observed in the near-infrared emission lines of the Nd(3+) ion in a Cr(3+),Nd(3+):Gd(3)Sc(2)Ga(3)O(12) crystal, associated to the R(1,2)((4)F(3/2))?Z(5)((4)I(9/2)) and R(1,2)((4)F(3/2))?Z(1)((4)I(9/2)) transitions. The former emissions show large linear pressure coefficients of -11.3 cm(-1)/GPa and -8.8 cm(-1)/GPa, while the latter show high thermal sensitivity in the low temperature range. Thus this garnet crystal can be considered a potential optical pressure and/or temperature sensor in high pressure and temperature experiments up to 12 GPa and below room temperature, used in diamond anvil cells and excited with different UV and visible commercial laser due to the multiple Cr(3+) and Nd(3+) absorption bands. PMID:22535129

León-Luis, S F; Muñoz-Santiuste, J E; Lavín, V; Rodríguez-Mendoza, U R

2012-04-23

34

Thermal effects on cavity stability of chromium- and neodymium-doped gadolinium scandium gallium garnet laser under solar-simulator pumping  

NASA Technical Reports Server (NTRS)

Results are presented on testing a Cr- and Nd-codoped Gd-Sc-Ga-garnet (Cr:Nd:GSGG) crystal and a Nd:YAG crystal (both of 3.2 mm diam and 76-mm long) for pulsed and CW laser operations using a flashlamp and solar simulator as pumping sources. Results from experiments with the flashlamp show that, at pulse lengths of 0.11, 0.28, and 0.90 ms, the slope efficiency of the Cd:Nd:GSGG crystal was higher than that of the Nd:YAG crystal and increased with pulse width. With the solar simulator, however, the CW laser operation of the Cr:Nd:GSGG crystal was limited to intensities not greater than 1500 solar constants, while the Nd:YAG laser successfully performed for all pump beam intensities available. It was found that the exposure for several minutes of the Cr:Nd:GSGG crystal to pump beam intensity of 3000 solar constants led to its damage by thermal cracking, indicating that a better solar-pumped CW laser performance may be difficult to realize with rod geometry.

Kim, Kyong H.; Venable, Demetrius D.; Brown, Lamarr A.; Lee, Ja H.

1991-01-01

35

Origin of color centers in the flux-grown europium gallium garnet  

SciTech Connect

Europium gallium garnet (EuGG) single crystals were grown from fluxes with various contents. Optical absorption spectra of EuGG grown from a flux containing calcium show an additional band in the ultraviolet and blue regions of the spectra as compared to the case of a calcium-free flux. Moessbauer spectra of the samples grown from the fluxes with different additives show no signs of other valence states of the europium ions except for 3+. However, they indicate changes in the crystal field due to the entrance of additive ions. The nature of the additional absorption must be the same as that for calcium-doped gadolinium gallium garnet, i.e., anion vacancies. Moessbauer isotope shifts and quadrupole splitting for EuGG are determined.

Aleksandrovsky, A. S.; Arkhipkin, V. G.; Bezmaternykh, L. N.; Gudim, I. A.; Krylov, A. S. [L. V. Kirensky Institute of Physics, Akademgorodok, Krasnoyarsk 660036, Russia and Siberian Federal University, Krasnoyarsk 660079 (Russian Federation); Vagizov, F. [Department of Physics, Texas A and M University, College Station, Texas 77840 (United States)

2008-04-15

36

Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

We report an experimental observation of terahertz Cherenkov radiation from a moving magnetic moment produced in terbium gallium garnet by a circularly polarized femtosecond laser pulse via the inverse Faraday effect. Contrary to some existing theoretical predictions, the polarity of the observed radiation unambiguously demonstrates the paramagnetic, rather than diamagnetic, nature of the ultrafast inverse Faraday effect. From measurements of the radiation field, the Verdet constant in the subpicosecond regime is ˜3-10 times smaller than its table quasistatic value.

Gorelov, S. D.; Mashkovich, E. A.; Tsarev, M. V.; Bakunov, M. I.

2013-12-01

37

Improving Scintillation Performance of Ce-doped Garnet Crystals  

Microsoft Academic Search

The Center for Materials Research has developed a new mixed garnet scintillator host material -- Yttrium Gadolinium Gallium Aluminum Garnet (YGGAG). In addition to high thermal and chemical stability and radiation hardness found in garnet crystals it offers high neutron sensitivity due to presence of Gd atoms, has about 100 C lower melting temperature than standard yttrium aluminum garnet host

Denys Solodovnikov; Marc Weber; David Bahr; Grant Norton; Drew Haven; Jalal Nawash; Romit Dhar; Kelvin Lynn

2010-01-01

38

Structural and thermal investigation of gadolinium gallium mixed oxides obtained by coprecipitation: Observation of a new metastable phase  

SciTech Connect

Polycrystalline gadolinium gallium mixed oxides were prepared by coprecipitation and annealing at various temperatures below 1000 deg. C. The oxide materials appear to be X-ray amorphous after a heat treatment at 500 deg. C for 30 h, but after 30 h at 800 and 900 deg. C a major, unreported, hexagonal phase, isostructural with TAlO{sub 3} compounds (where T=Y, Eu, Gd, Tb, Dy, Ho, Er) appears to crystallize. On the other hand, a highly energetic mechanical treatment of the amorphous powder previously annealed at 500 deg. C changes considerably the shape and position of exothermal events occurring in the range from 700 up to 900 deg. C. Subsequent annealing at 900 deg. C of the mechanically treated powder gives rise to the complete formation of the Gd{sub 3}Ga{sub 5}O{sub 12} garnet structure at the expense of the hexagonal phase and of the minor Gd{sub 4}Ga{sub 2}O{sub 9} oxide phase. However, a 7.0 wt% contamination is found to be due to tetragonal zirconia coming from vials and balls colliding media. The garnet phase may have strong deviations from the nominal stoichiometry of the garnet, as suggested by the refined lattice parameter obtained from the powder diffraction patterns and by the remarkable absence of intensity relative to the (220) Bragg peak position.

Bazzoni, Marco [Dipartimento di Chimica, Universita di Sassari, via Vienna n. 2, I-07100 Sassari (Italy); Bettinelli, Marco [Dipartimento Scientifico e Tecnologico, Universita di Verona, Ca' Vignal 1, strada le Grazie 15, I-37134 Verona (Italy); Daldosso, Matteo [Dipartimento Scientifico e Tecnologico, Universita di Verona, Ca' Vignal 1, strada le Grazie 15, I-37134 Verona (Italy); Enzo, Stefano [Dipartimento di Chimica, Universita di Sassari, via Vienna n. 2, I-07100 Sassari (Italy)]. E-mail: enzo@uniss.it; Serra, Filomena [Dipartimento di Chimica, Universita di Sassari, via Vienna n. 2, I-07100 Sassari (Italy); Speghini, Adolfo [Dipartimento Scientifico e Tecnologico, Universita di Verona, Ca' Vignal 1, strada le Grazie 15, I-37134 Verona (Italy)

2005-07-15

39

Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions––effective laser media  

Microsoft Academic Search

The results of spectroscopy and laser action of disordered calcium niobium gallium (CNGG) and calcium lithium niobium gallium (CLNGG) garnets doped with Nd3+, Eu3+, Er3+, Ho3+ and Tm3+ were displayed. The structure and some optical and physical properties of CNGG and CLNGG-crystals were studied. Activator centers construction and the mechanism of inhomogeneous broadening and splitting of spectral lines of rare

Yu. K Voronko; A. A Sobol; A. Ya Karasik; N. A Eskov; P. A Rabochkina; S. N Ushakov

2002-01-01

40

Synthesis and characterisation of chromium lutetium gallium garnet solid solution  

SciTech Connect

The chromium lutetium gallium garnet system has been studied. Samples with 2xCaOxCr{sub 2}O{sub 3}(3 - 2x)Lu{sub 2}O{sub 3}5Ga{sub 2}O{sub 3} (x = 0.025, 0.05, 0.075, 0.1, 0.2 and 0.3,) and xCr{sub 2}O{sub 3}(3 - x)Lu{sub 2}O{sub 3}5Ga{sub 2}O{sub 3} (x = 0, 0.05, 0.075 and 0.3) compositions have been prepared in Ca,Cr:LGG and Cr:LGG systems, respectively. Samples were prepared by ceramic method, fired at 1250 deg. C/6 h and characterised by XRD, lattice parameters, UV-vis-NIR spectroscopy, CIE L * a * b * measurements and SEM/EDX. Results indicate that Ca,Cr:LGG and Cr:LGG solid solutions are obtained. In Cr:LGG system only Cr(III) is stabilised in octahedral positions substituting for Lu(III) and Ga(III). Both Cr(III) and Cr(IV) are present in Ca,Cr:LGG. The calcium is a charge compensator to stabilise Cr(IV) and this is the predominant oxidation state up to x = 0.075 composition. From this composition, Cr(III) becomes more stabilised in garnet lattice. Cr(IV) occupies generally tetrahedral and dodecahedral sites substituting for Ga(III) and Lu(III), while Cr(III) is in octahedral site substituting for Ga(III)

Galindo, R. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Badenes, J.A. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain)]. E-mail: jbadenes@qio.uji.es; Llusar, M. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Tena, M.A. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Monros, G. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain)

2007-03-22

41

Low-temperature thermal conductivity of terbium-gallium garnet  

SciTech Connect

Thermal conductivity of paramagnetic Tb{sub 3}Ga{sub 5}O{sub 12} (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence {kappa}(T) of thermal conductivity at T{sub min} = 0.52 K. This and other singularities on the {kappa}(T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb{sup 3+} ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb{sup 3+} ion.

Inyushkin, A. V., E-mail: inyushkin@imp.kiae.ru; Taldenkov, A. N. [Kurchatov Institute, Russian Research Centre (Russian Federation)

2010-11-15

42

Interlayer perpendicular domain coupling between thin Fe films and garnet single-crystal underlayers  

E-print Network

Interlayer perpendicular domain coupling between thin Fe films and garnet single of Fe films grown on yttrium­iron­garnet YIG underlayers were studied to elucidate their interlayer-optic Kerr effect MOKE . The YIG layer, grown by liquid phase epitaxy on single crystal gadolinium­gallium­garnet

Krishnan, Kannan M.

43

Plasmon resonance enhancement of Faraday rotation in thin garnet films  

NASA Astrophysics Data System (ADS)

Garnet films have been grown over (100)-oriented substituted gadolinium gallium garnet substrates partially populated with gold nanoparticles in order to study plasmon resonance enhancement of magneto-optic effects. The results of measurements of light transmission through these films as well as Faraday rotation are reported.

Tkachuk, S.; Lang, G.; Krafft, C.; Rabin, O.; Mayergoyz, I.

2011-04-01

44

EXCHANGE RESONANCES IN GADOLINIUM IRON GARNET AT 24.000 MHz By S. GESCHWIND, L. R. WALKER and D. F. LINN,  

E-print Network

344 EXCHANGE RESONANCES IN GADOLINIUM IRON GARNET AT 24.000 MHz By S. GESCHWIND, L. R. WALKER and D garnet at 24 000 Mc in the vicinity of the magnetic compensation point at Tc = + 13 °C. The two modes, FÉVRIER-MARS 1959, Introduction. - The rare earth iron garnets are, strictly, systems with three

Paris-Sud XI, Université de

45

PHYSICAL REVIEW A 82, 043806 (2010) Photon self-induced spin-to-orbital conversion in a terbium-gallium-garnet crystal  

E-print Network

PHYSICAL REVIEW A 82, 043806 (2010) Photon self-induced spin-to-orbital conversion in a terbium gradient in the medium. In this work we tested the occurrence of SISTOC in a terbium-gallium-garnet rod in the FI is terbium-gallium-garnet (TGG) which has a relatively high absorption (generally higher than 1000

Marrucci, Lorenzo

46

Faraday rotation spectra of bismuth-substituted ferrite garnet films with in-plane magnetization  

Microsoft Academic Search

Single crystal films of bismuth-substituted ferrite garnets have been synthesized by the liquid phase epitaxy method where gadolinium gallium garnet substrates are dipped into the flux. The growth parameters are controlled to obtain films with in-plane magnetization and virtually no domain activity, which makes them excellently suited for magnetooptic imaging. The Faraday rotation spectra were measured across the visible range

L. E. Helseth; R. W. Hansen; E. I. Il'yashenko; M. Baziljevich; T. H. Johansen

2001-01-01

47

Microstrip lines using yttrium iron garnet film  

Microsoft Academic Search

The spectral-domain technique is used to compute the dispersion characteristics and the transverse field distributions of microstrip lines using a yttrium-iron-garnet (YIG) film on a gadolinium-gallium-garnet (GGG) substrate. Numerical results are presented to show a sharp cutoff characteristic for a large thickness of GGG (which is caused by the reduction in the negative permeability range), and to show the effect

M. Tsutsumi; T. Asahara

1990-01-01

48

Structural, elastic and vibrational properties of nanocrystalline lutetium gallium garnet under high pressure.  

PubMed

An ab initio study of the structural, elastic and vibrational properties of the lutetium gallium garnet (Lu3Ga5O12) under pressure has been performed in the framework of the density functional theory, up to 95 GPa. Pressure dependence of the elastic constants and the mechanical stability are analyzed, showing that the garnet structure is mechanically unstable above 87 GPa. Lattice-dynamics calculations in bulk at different pressures have been performed and compared with Raman scattering measurements of the nanocrystalline Tm(3+)-doped Lu3Ga5O12 up to 60 GPa. The theoretical frequencies and pressure coefficients of the Raman active modes for bulk Lu3Ga5O12 are in good agreement with the experimental data measured for the nano-crystals. The contributions of the different atoms to the vibrational modes have been analyzed based on the calculated total and partial phonon density of states. The vibrational modes have been discussed in relation to the internal and external modes of the GaO4 tetrahedron and the GaO6 octahedron. The calculated infrared modes and their pressure dependence are also reported. Our results show that with this nano-garnet size the sample has essentially bulk properties. PMID:25767835

Monteseguro, V; Rodríguez-Hernández, P; Ortiz, H M; Venkatramu, V; Manjón, F J; Jayasankar, C K; Lavín, V; Muñoz, A

2015-04-14

49

Structural and thermal investigation of gadolinium gallium mixed oxides obtained by coprecipitation: Observation of a new metastable phase  

Microsoft Academic Search

Polycrystalline gadolinium gallium mixed oxides were prepared by coprecipitation and annealing at various temperatures below 1000°C. The oxide materials appear to be X-ray amorphous after a heat treatment at 500°C for 30h, but after 30h at 800 and 900°C a major, unreported, hexagonal phase, isostructural with TAlO3 compounds (where T=Y, Eu, Gd, Tb, Dy, Ho, Er) appears to crystallize. On

Marco Bazzoni; Marco Bettinelli; Matteo Daldosso; Stefano. Enzo; Filomena Serra; Adolfo Speghini

2005-01-01

50

Terbium gallium garnet ceramic Faraday rotator for high-power laser application.  

PubMed

A terbium gallium garnet (TGG) ceramic Faraday rotator (FR) with an isolation ratio of 33 dB was demonstrated at a laser radiation power of 257 W. This FR can be equipped with a large optical aperture by using ceramics technology to prevent laser damage at high-energy pulse operation. The thermal lens of a 257 W laser with a beam diameter of 2.6 mm had a focal length of 9.5 m, which is easily corrected using a spherical lens to suppress the undesirable effects of thermal lensing. The rotation angle of the FR was stabilized by water cooling. The results indicate that the TGG-ceramic-based FR is suitable for high-energy laser systems with high repetition rates. PMID:24690692

Yasuhara, Ryo; Snetkov, Ilya; Starobor, Alexey; Zheleznov, Dmitry; Palashov, Oleg; Khazanov, Efim; Nozawa, Hoshiteru; Yanagitani, Takagimi

2014-03-01

51

Fabrication and characterization of cerium-doped terbium gallium garnet with high magneto-optical properties.  

PubMed

High optical quality (Tb(1-x)Cex)3Ga5O12 (TCGG) single crystal has been grown by the Czochralski method. The optical and magneto-optical properties of the TCGG are analyzed in detail and the Verdet constant (V) of TCGG is compared with that of undoped terbium gallium garnet (TGG) crystal. TCGG presents a very high transmittance, particularly in the visible-near infrared (VIS-NIR) region, and its V is obviously larger than that of TGG in the VIS-NIR region. The figure of merit and optical features point out the superior characteristics of TCGG with respect to TGG. PMID:25723441

Chen, Zhe; Hang, Yin; Yang, Lei; Wang, Jun; Wang, Xiangyong; Hong, Jiaqi; Zhang, Peixiong; Shi, Chunjun; Wang, Yaqi

2015-03-01

52

Interaction of Er{sup 3+} ions in Er-doped calcium - niobium - gallium garnet crystals  

SciTech Connect

The processes of nonradiative energy transfer in calcium - niobium - gallium garnet (CNGG) crystals doped with Er{sup 3+} ions are studied. It is found that the energy of erbium ions in the Er:CNGG crystal with the erbium atomic concentrations C{sub Er}=6% and 11% is transferred via the nonradiative co-operative processes {sup 4}I{sub 11/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 11/2{yields}} {sup 4}F{sub 7/2}, {sup 4}I{sub 11/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 13/2{yields}} {sup 4}F{sub 9/2}; and {sup 4}I{sub 13/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 13/2{yields}} {sup 4}I{sub 9/2}, whose efficiency increases with increasing intensity of exciting radiation. It is shown that the cross-relaxation processes {sup 4}S{sub 3/2{yields}}{sup 4}I{sub 9/2}, {sup 4}I{sub 15/2{yields}}{sup 4}I{sub 13/2}, whose intensity depends on the concentration of Er{sup 3+} ions, are characteristic for Er:CNGG crystals with the Er atomic concentration above 1%. (active media)

Malov, A V [N.P. Ogarev Mordovian State University, Saransk (Russian Federation); Popov, A V [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Ryabochkina, P A; Bol'shakov, E V

2010-08-03

53

Recent progress in advanced optical materials based on gadolinium aluminate garnet (Gd3Al5O12)  

NASA Astrophysics Data System (ADS)

This review article summarizes the recent achievements in stabilization of the metastable lattice of gadolinium aluminate garnet (Gd3Al5O12, GAG) and the related developments of advanced optical materials, including down-conversion phosphors, up-conversion phosphors, transparent ceramics, and single crystals. Whenever possible, the materials are compared with their better known YAG and LuAG counterparts to demonstrate the merits of the GAG host. It is shown that novel emission features and significantly improved luminescence can be attained for a number of phosphor systems with the more covalent GAG lattice and the efficient energy transfer from Gd3+ to the activator. Ce3+ doped GAG-based single crystals and transparent ceramics are also shown to simultaneously possess the advantages of high theoretical density, fast scintillation decay, and high light yields, and hold great potential as scintillators for a wide range of applications. The unresolved issues are also pointed out.

Li, Ji-Guang; Sakka, Yoshio

2015-02-01

54

Single crystal Ce doped scintillator material with garnet structure sensitive to gamma ray and neutron radiation  

NASA Astrophysics Data System (ADS)

A mixed garnet scintillator host material is obtained from the melt—Yttrium Gadolinium Gallium Aluminum Garnet (YGGAG). In addition to the high thermal and chemical stability and radiation hardness found in garnet crystals, it offers sensitivity to neutrons due to the presence of Gd atoms, has lower melting temperature than yttrium aluminum garnet, and similar crystallization behavior suitable for growth of large volume crystals. Crystals of YGGAG doped with Ce of 10×10×10 mm3 have already demonstrated energy resolution of 10% at 662 keV.

Solodovnikov, D.; Weber, M. H.; Haven, D. T.; Lynn, K. G.

2012-08-01

55

Faraday rotation and sensitivity of (100) bismuth-substituted ferrite garnet films  

Microsoft Academic Search

We have investigated the Faraday rotation of in-plane magnetized bismuth-substituted ferrite garnet films grown by liquid phase epitaxy on (100) oriented gadolinium gallium garnet substrates. The Faraday spectra were measured for photon energies between 1.7 and 2.6 eV. To interpret the spectra, we use a model based on two electric dipole transitions: one tetrahedral and one octahedral. Furthermore, the Faraday

L. E. Helseth; A. G. Solovyev; R. W. Hansen; E. I. Il'Yashenko; M. Baziljevich; T. H. Johansen

2002-01-01

56

Faraday rotation and sensitivity of (100) bismuth-substituted ferrite garnet films  

Microsoft Academic Search

We have investigated the Faraday rotation of in-plane magnetized bismuth -\\u000asubstituted ferrite garnet films grown by liquid phase epitaxy on (100)\\u000aoriented gadolinium gallium garnet substrates. The Faraday spectra were\\u000ameasured for photon energies between 1.7 - 2.6 eV. To interprete the spectra,\\u000awe use a model based on two electric dipole transitions, one tetrahedral and\\u000aone octahedral. Furthermore,

L. E. Helseth; A. G. Solovyev; R. W. Hansen; M. Baziljevich; T. H. Johansen

2002-01-01

57

Pressure-induced luminescence of cerium-doped gadolinium gallium garnet crystal  

NASA Astrophysics Data System (ADS)

Studies of the spectroscopic properties of Ce3+ dopant in bulk Gd3Ga5O12:Ce crystal under pressure are presented. In spite of strong intershell 4f?5d absorption bands at ambient pressure, the cerium luminescence in Gd3Ga5O12 is entirely quenched even at low temperature. It has been shown that applying pressure allows for recovery of the 5d?4f radiative transitions. Further increase of pressure improves the emission efficiency. This effect is analyzed in terms of two possible phenomena: (i) by pressure-induced electronic crossover of the excited 5d energy level of the Ce3+ with the conduction band bottom of the host crystal, and (ii) by decrease of electron-lattice coupling with increasing pressure, resulting in reduction of the Stokes shift and nonradiative transitions between the low vibrational levels of the 5d state and high vibrational levels of the ground 4f state. The results of high-pressure absorption and luminescence measurements point out that the ambient-pressure luminescence quenching is caused by the donor-like charge transfer processes due to the resonant location of the Ce3+ 5d electronic levels with respect to the host conduction band. In such a situation, the ionization of Ce3+ to Ce4+ occurs, accompanied by large lattice relaxation, which enables the nonradiative recombination to the Ce 4f state. The pressure-induced approach of the conduction-band bottom of the host crystal by the excited 5d energy level of the Ce3+ results in mixing between conduction band states and the 5d state, and the broadband luminescence from this mixed state is observed at pressures from 30 up to about 60 kbar. Then, for pressures exceeding 60 kbar, this luminescence is replaced by the classic Ce3+5d?4f transitions. Using a simple anticrossing model and configuration coordinate model in the appropriate pressure range, quantitative description of the system has been carried out, and the pressure-induced decrease of electron-lattice coupling has been shown.

Kaminska, A.; Duzynska, A.; Berkowski, M.; Trushkin, S.; Suchocki, A.

2012-04-01

58

The prospects for a new search for the electron electric dipole moment in solid Gadolinium iron garnet ceramics  

E-print Network

We address a number of issues regarding solid state electron electric dipole moment (EDM) experiments, focusing on gadolinium iron garnet (abbreviated GdIG, chemical formula Gd$_3$Fe$_5$O$_{12}$) as a possible sample material. GdIG maintains its high magnetic susceptibility down to 4.2 K, which enhances the EDM-induced magnetization of a sample placed in an electric field. We estimate that lattice polarizability gives rise to an EDM enhancement factor of approximately 20. We also calculate the effect of the demagnetizing field for various sample geometries and permeabilities. Measurements of intrinsic GdIG magnetization noise are presented, and the fluctuation-dissipation theorem is used to compare our data with the measurements of the imaginary part of GdIG permeability at 4.2 K, showing good agreement above frequencies of a few hertz. We also observe how the demagnetizing field suppresses the noise-induced magnetic flux, confirming our calculations. The statistical sensitivity of an EDM search based on a so...

Sushkov, A O; Lamoreaux, S K

2008-01-01

59

Characteristics of epitaxial garnets grown by CVD using single metal alloy sources. [Chemical Vapor Deposition  

NASA Technical Reports Server (NTRS)

Single metal alloys have been explored as the cation source in the chemical vapor deposition (CVD) of iron garnets. Growth of good quality single crystal garnet films containing as many as five different cations has been achieved over a wide range of deposition conditions. The relationship of film composition to alloy compositions and deposition conditions has been determined for several materials. By proper choice of the alloy composition and the deposition conditions, uncrazed deposits were grown on (111) gadolinium gallium garnet (GGG) substrates. Data on physical, magnetic and optical properties of representative films is presented and discussed.

Besser, P. J.; Hamilton, T. N.; Mee, J. E.; Stermer, R. L.

1974-01-01

60

Growth of codoped garnet crystals  

NASA Astrophysics Data System (ADS)

The formation of codoped (Cr, Nd) scandium, calcium, magnesium, zirconium, and aluminum substituted gadolinium gallium garnet (GGG) crystals is investigated. For the growth of the codoped GSGG a slope efficiency of about 7 percent was obtained and this value correlates well with the slope efficiency of Nd:YAG. The absorption band overlapping the 1.06 micron laser output and the temperature-induced striations that occur during GSGG crystal growth are analyzed. The relation between site selection in the garnets and the ionic radius is studied. The performance of Ca, Mg, and Zr substituted GGG crystals codoped with Cr and Nd is evaluated; a slope efficiency of 1 percent for up to 100 J input is obtained for the crystals. The effect of lattice defect structure on the growth of the crystals is examined.

Uhrin, R.; Belt, R. F.

61

Paramagnetic Resonance of Fe3+ in Yttrium Aluminum, Lutetium Aluminum, and Lutetium Gallium Garnets  

Microsoft Academic Search

The spin-Hamiltonian parameters have been determined for the Fe3+ ion when present as substitutional impurity in the series of isomorphous diamagnetic garnets. Most of the parameters vary rather slowly from host to host. It is shown that the dependence of the cubic field splitting in the octahedral sites on lattice parameters as obtained from the present results is consistent with

L. Rimai; T. Kushida

1966-01-01

62

Improving Scintillation Performance of Ce-doped Garnet Crystals  

NASA Astrophysics Data System (ADS)

The Center for Materials Research has developed a new mixed garnet scintillator host material -- Yttrium Gadolinium Gallium Aluminum Garnet (YGGAG). In addition to high thermal and chemical stability and radiation hardness found in garnet crystals it offers high neutron sensitivity due to presence of Gd atoms, has about 100 C lower melting temperature than standard yttrium aluminum garnet host and similar crystallization behavior suitable for growth of large volume crystals. Crystals of YGGAG doped with Ce and Tb of 10x10x10 mm in size already demonstrated energy resolution of 10% at 662keV. Our group demonstrated strong correlation between scintillation performance and deferent types of defects in Ce:Er:YAG scintillators. Work on further improving YGGAG performance by eliminating defects is currently in progress.

Solodovnikov, Denys; Weber, Marc; Bahr, David; Norton, Grant; Haven, Drew; Nawash, Jalal; Dhar, Romit; Lynn, Kelvin

2010-03-01

63

Photon self-induced spin-to-orbital conversion in a terbium-gallium-garnet crystal at high laser power  

SciTech Connect

In this paper, we present experimental evidence of a third-order nonlinear optical process, self-induced spin-to-orbital conversion (SISTOC) of the photon angular momentum. This effect is the physical mechanism at the origin of the depolarization of very intense laser beams propagating in isotropic materials. The SISTOC process, like self-focusing, is triggered by laser heating leading to a radial temperature gradient in the medium. In this work we tested the occurrence of SISTOC in a terbium-gallium-garnet rod for an impinging laser power of about 100 W. To study the SISTOC process we used different techniques: polarization analysis, interferometry, and tomography of the photon orbital angular momentum. Our results confirm, in particular, that the apparent depolarization of the beam is due to the occurrence of maximal entanglement between the spin and orbital angular momentum of the photons undergoing the SISTOC process. This explanation of the true nature of the depolarization mechanism could be of some help in finding novel methods to reduce or to compensate for this usually unwanted depolarization effect in all cases where very high laser power and good beam quality are required.

Mosca, S.; De Rosa, R.; Milano, L. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Complesso Universitario di Monte S. Angelo, 80126 Napoli (Italy); INFN Sezione di Napoli, Complesso Universitario di Monte S. Angelo, 80126 Napoli (Italy); Canuel, B.; Genin, E. [EGO, European Gravitational Observatory, Via E. Amaldi, 56021 S. Stefano a Macerata, Cascina (Italy); Karimi, E. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Complesso Universitario di Monte S. Angelo, 80126 Napoli (Italy); Piccirillo, B.; Santamato, E. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Complesso Universitario di Monte S. Angelo, 80126 Napoli (Italy); CNISM-Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Napoli (Italy); Marrucci, L. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Complesso Universitario di Monte S. Angelo, 80126 Napoli (Italy); CNR-INFM Coherentia, Complesso Universitario di Monte S. Angelo, 80126 Napoli (Italy)

2010-10-15

64

High-temperature terahertz absorption band in rare-earth gallium garnet  

NASA Astrophysics Data System (ADS)

In addition to the absorption due to known optical phonons, we found a temperature-dependent absorption band at 2 THz in garnet-type H o3G a5O12 , at temperatures in the range of 450-540 K. The optical and electrical properties reveal that the absorption band at 2 THz is not produced by mechanisms related to soft phonons, rattling phonons, impurities, or charge density waves, but rather to polaron conduction. Our analysis of the scattering rates and optical mobility shows that electron transport via the intermediate polaron is significant in this absorption band. Electrical measurements also support the existence of polarons in H o3G a5O12 . This paper facilitates a method to investigate charge carrier transport from an optical point of view using terahertz time-domain spectroscopy, which we demonstrate using H o3G a5O12 .

Adachi, Masaki; Matsui, Hiroaki; Seki, Munetoshi; Yamahara, Hiroyasu; Tabata, Hitoshi

2015-02-01

65

Growth and ferromagnetic resonance properties of nanometer-thick yttrium iron garnet films  

NASA Astrophysics Data System (ADS)

Growth of nm-thick yttrium iron garnet films and ferromagnetic resonance (FMR) linewidth properties in the films are reported. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition (PLD). Films in the 5-35 nm thickness range showed a (111) orientation and a surface roughness between 0.1 and 0.3 nm. The 10 nm films showed a 10 GHz FMR linewidth of about 6 Oe and a damping constant of 3.2 × 10-4. The FMR linewidth increases with both the surface roughness and the surface Fe deficiency. Thicker films exhibit a smaller FMR linewidth and a lower damping constant.

Sun, Yiyan; Song, Young-Yeal; Chang, Houchen; Kabatek, Michael; Jantz, Michael; Schneider, William; Wu, Mingzhong; Schultheiss, Helmut; Hoffmann, Axel

2012-10-01

66

Magnetic anisotropies in ultrathin bismuth iron garnet films  

NASA Astrophysics Data System (ADS)

Ultrathin bismuth iron garnet Bi3Fe5O12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi3Fe5O12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization.

Popova, Elena; Franco Galeano, Andres Felipe; Deb, Marwan; Warot-Fonrose, Bénédicte; Kachkachi, Hamid; Gendron, François; Ott, Frédéric; Berini, Bruno; Keller, Niels

2013-06-01

67

Absolute excited-state absorption cross section and fluorescence quantum efficiency of Cr(3+):gadolinium scandium gallium garnet.  

PubMed

Excited-state properties of the laser material Cr(3+):Gd(3)Sc(2)(GaO(4))(3) were determined by a photocaloric technique. The excited-state absorption cross section at 650 nm is (3.6 +/- 0.6) 10(-20) cm(2), and the fluorescence quantum efficiency at ambient temperature is (91 +/- 1)%. PMID:19741876

Seelert, W; Strauss, E

1987-10-01

68

Coupling Single-Mode Fiber to Uniform and Symmetrically Tapered Thin-Film Waveguide Structures Using Gadolinium Gallium Garnet  

NASA Technical Reports Server (NTRS)

The need for high efficiency components has grown significantly due to the expanding role of fiber optic communications for various applications. Integrated optics is in a state of metamorphosis and there are many problems awaiting solutions. One of the main problems being the lack of a simple and efficient method of coupling single-mode fibers to thin-film devices for integrated optics. In this paper, optical coupling between a single-mode fiber and a uniform and tapered thin-film waveguide is theoretically modeled and analyzed. A novel tapered structure presented in this paper is shown to produce perfect match for power transfer.

Gadi, Jagannath; Yalamanchili, Raj; Shahid, Mohammad

1995-01-01

69

Synthesis and characterization of nanocrystalline Nd{sup 3+}-doped gadolinium scandium aluminum garnet powders by a gel-combustion method  

SciTech Connect

Graphical abstract: The graph shows the emission spectra (?{sub ex} = 808 nm) of 1 at.% Nd:GSAG powders sintered at different temperatures for 3 h. Compared with the powder sintered at 900 °C, the PL intensity of the powder sintered at 1000 °C decreased significantly. The changes in the PL intensity should mainly due to the crystallinity and dispersion of the powders. Highlights: ? We synthesized Nd:GSAG nano-powders by gel-combustion method successfully. ? We analyzed the structure and the morphology of the heat-treated products. ? We studied the optical characteristics of Nd:GSAG nano-powders. -- Abstract: Nd{sup 3+}-doped gadolinium scandium aluminum garnet (Nd:GSAG) precursor was synthesized by a gel combustion method using metal nitrates and citric acid as raw materials. The structure and morphology of the precursor and the sintered powders were studied by means of X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). The results showed that the precursor transformed into pure GSAG polycrystalline phase at about 800 °C, and the powders sintered at 800–1000 °C were well-dispersed with average particle sizes in the range of 30–80 nm. Optical properties of Nd:GSAG nano-powders were characterized by using photoluminescence spectroscopy. The highest photoluminescence intensity was achieved for the powder sintered at 900 °C.

Su, Jing, E-mail: zlj007@126.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)] [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Miao, Ju-hong; Xu, Lin-hua; Ji, Yu-qing; Wang, Chu-qin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)] [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

2012-07-15

70

Terbium gallium garnet ceramic-based Faraday isolator with compensation of thermally induced depolarization for high-energy pulsed lasers with kilowatt average power  

NASA Astrophysics Data System (ADS)

A scalable aperture Faraday isolator for high-energy pulsed lasers with kW-level average power was demonstrated using terbium gallium garnet ceramics with water cooling and compensation of thermally induced depolarization in a magnetic field. An isolation ratio of 35 dB (depolarization ratio ? of 3.4 × 10-4) was experimentally observed at a maximum laser power of 740 W. By using this result, we estimated that this isolator maintains an isolation ratio of 30 dB for laser powers of up to 2.7 kW. Our results provide the solution for achieving optical isolation in high-energy (100 J to kJ) laser systems with a repetition rate greater than 10 Hz.

Yasuhara, Ryo; Snetkov, Ilya; Starobor, Alexey; Palashov, Oleg

2014-12-01

71

Juxtaposition of spin freezing and long range order in a series of geometrically frustrated antiferromagnetic gadolinium garnets  

NASA Astrophysics Data System (ADS)

Specific heat measurements in zero magnetic field are presented on a homologous series of geometrically frustrated antiferromagnetic Heisenberg garnet systems. Measurements of Gd3Ga5O12, grown with isotopically pure Gd, agree well with previous results on samples with naturally abundant Gd, showing no ordering features. In contrast, samples of Gd3Te2Li3O12 and Gd3Al5O12 are found to exhibit clear ordering transitions at 243 and 175 mK, respectively. The effects of low level disorder are studied through dilution of Gd3+ with nonmagnetic Y3+ in Gd3Te2Li3O12. A thorough structural characterization, using x-ray diffraction, is performed on all of the samples studied. We discuss possible explanations for such diverse behavior in very similar systems.

Quilliam, J. A.; Meng, S.; Craig, H. A.; Corruccini, L. R.; Balakrishnan, G.; Petrenko, O. A.; Gomez, A.; Kycia, S. W.; Gingras, M. J. P.; Kycia, J. B.

2013-05-01

72

Garnet-to-perovskite transition in Gd3Sc2Ga3O12 at high pressure and high temperature.  

PubMed

The structural phase transition of gadolinium-scandium-gallium garnet (Gd(3)Sc(2)Ga(3)O(12), GSGG) has been studied at high pressure and high temperature using the synchrotron X-ray diffraction technique in a laser-heated diamond anvil cell. The GSGG garnet transformed to an orthorhombic perovskite structure at approximately 24 GPa after laser heating to 1500-2000 K. The garnet-to-perovskite phase transition is associated with an ?8% volume reduction and an increase in the coordination number of the Ga(3+) or Sc(3+) ion. The orthorhombic perovskite GSGG has bulk modulus B(0) = 194(15) GPa with B(0)' = 5.3(8), exhibiting slightly less compression than the cubic garnet structure of GSGG with B(0) = 157(15) GPa and B(0)' = 6.5(10). Upon compression at room temperature, the cubic GSGG garnet became amorphous at ?65 GPa. Coupled with the amorphous-to-perovskite phase transition in Y(3)Fe(5)O(12) and Gd(3)Ga(5)O(12) at high-pressure-temperature conditions, we conclude that amorphization should represent a new thermodynamic state resulting from hindrance of the garnet-to-perovskite phase transition, whereas the garnet-to-amorphous transition in rare-earth garnets should be kinetically hindered at room temperature. PMID:23240758

Lin, Chuanlong; Liu, Jing; Lin, Jung-Fu; Li, Xiaodong; Li, Yanchun; Zhang, Qingli; Xiong, Lun; Li, Rui

2013-01-01

73

ON THE MAGNETIC PROPERTIES OF OXIDES OF GADOLINIUM  

Microsoft Academic Search

The temperature dependence of the magnetic properties of gadolinium ; ferrites with garnet and perovskite structures and also of gadolinium manganate ; was measured. It is found that at the compensation point and the Curie point ; there is an anomalous growth of the coercive force and a very small paraprocess ; in garnet ferrite. There is also an anomaly

K. P. Belov; M. A. Zaitseva; A. V. Pedko

1959-01-01

74

Inverse spin Hall effect in nanometer-thick yttrium iron garnet/Pt system  

NASA Astrophysics Data System (ADS)

High quality nanometer-thick (20 nm, 7 nm, and 4 nm) epitaxial Yttrium Iron Garnet (YIG) films have been grown on gadolinium gallium garnet substrates using pulsed laser deposition. The Gilbert damping coefficient for the 20 nm thick films is 2.3 × 10-4 which is the lowest value reported for sub-micrometric thick films. We demonstrate Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. The amplitude and the lineshape of the ISHE voltage correlate well to the increase of the Gilbert damping when decreasing thickness of YIG. Spin Hall effect based loss-compensation experiments have been conducted but no change in the magnetization dynamics could be detected.

d'Allivy Kelly, O.; Anane, A.; Bernard, R.; Ben Youssef, J.; Hahn, C.; Molpeceres, A. H.; Carrétéro, C.; Jacquet, E.; Deranlot, C.; Bortolotti, P.; Lebourgeois, R.; Mage, J.-C.; de Loubens, G.; Klein, O.; Cros, V.; Fert, A.

2013-08-01

75

Growth of High-Quality Yttrium Iron Garnet Thin Films on Metallic Thin Layers  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) is one type of ferrite materials that has the lowest loss at microwave frequencies. One typically grows YIG on gadolinium gallium garnet (GGG) substrates, and this is typical mainly because of the perfect matching between the YIG and GGG lattice constants. For applications in monolithic devices, however, one needs to grow YIG films on metallic conductors or electrodes. This presentation reports the deposition of YIG thin films on metallic thin layers and the optimization of the deposition procedures. The metallic and YIG films were deposited by pulsed laser deposition and magnetron sputtering techniques and were characterized by scanning electron microscopy, x-ray diffraction, and ferromagnetic resonance measurements. The work shows rather clearly the critical roles of the selection of metallic materials, the thickness of the metallic layers, the deposition temperature, and the use of buffer layers on the deposition of high-quality YIG films.

Sun, Yiyan; Song, Young-Yeal; Wu, Mingzhong

2009-10-01

76

Phase stable rare earth garnets  

DOEpatents

A transparent ceramic according to one embodiment includes a rare earth garnet comprising A.sub.hB.sub.iC.sub.jO.sub.12, where h is 3.+-.10%, i is 2.+-.10%, and j is 3.+-.10%. A includes a rare earth element or a mixture of rare earth elements, B includes at least one of aluminum, gallium and scandium, and C includes at least one of aluminum, gallium and scandium, where A is at a dodecahedral site of the garnet, B is at an octahedral site of the garnet, and C is at a tetrahedral site of the garnet. In one embodiment, the rare earth garment has scintillation properties. A radiation detector in one embodiment includes a transparent ceramic as described above and a photo detector optically coupled to the rare earth garnet.

Kuntz, Joshua D.; Cherepy, Nerine J.; Roberts, Jeffery J.; Payne, Stephen A.

2013-06-11

77

Site-selective couplings in x-ray-detected magnetic resonance spectra of rare-earth-substituted yttrium iron garnets  

NASA Astrophysics Data System (ADS)

Site-selective x-ray detected magnetic resonance (XDMR) spectra were recorded in transverse detection geometry on two iron garnet thin films grown by liquid phase epitaxy (LPE) on oriented gadolinium gallium garnet (GGG) substrates: whereas the stoichiometry of the first film corresponded to pure yttrium iron garnet (1 = YIG) used as reference, yttrium was partly substituted with lanthanum and lutetium in the second film (2 = La-Lu-YIG). Surprisingly, the XDMR spectra of film 2 recorded at either the Fe K-edge or the La L3-edge revealed well-resolved structures that had fairly different relative intensity depending on whether we probed the tetrahedral ( {S}_{4} ) sites of iron or the dodecahedral ( {D}_{2} ) sites of lanthanum. The narrow XDMR lines measured at the Fe K-edge also contrast with the broad, foldover distorted lineshapes of the ferrimagnetic resonance spectra measured in the same scan. Further XDMR experiments were carried out with a thin, disc-shaped, single crystal of gadolinium iron garnet (3 = GdIG). At temperatures slightly above the gadolinium ordering temperature (T > TB = 69 K), the Gd L2-edge XDMR spectra were dominated by two well-resolved lines of nearly equal intensities. Similarly, the Fe K-edge XDMR spectra recorded under identical conditions did also split into several narrow lines but of strongly unequal intensity. These results suggest that, in the exchange-enhanced paramagnetic regime, spins precessing at the dodecahedral ( {D}_{2} ) sites of gadolinium do not couple in the same way with spins precessing at either the tetrahedral ( {S}_{4} ) or octahedral ( {S}_{6} ) sites of iron. On the other hand, destructive interferences between modes of opposite helicities were also observed in Fe K-edge XDMR spectra recorded far above the compensation temperature (T ? Tcp = 290 K). This looks like a typical signature of nonlinear four-magnon scattering processes at a very high pumping power.

Goulon, J.; Rogalev, A.; Wilhelm, F.; Goujon, G.; Yaresko, A.; Brouder, Ch; Ben Youssef, J.

2012-06-01

78

Crystal field disorder effects in the optical spectra of Nd3+ and Yb3+-doped calcium lithium niobium gallium garnets laser crystals and ceramics  

NASA Astrophysics Data System (ADS)

The optical spectroscopic properties of RE3+ (Nd, 1 at. % or Yb, 1 to 10 at. %)-doped calcium-lithium-niobium-gallium garnet (CLNGG) single crystals and ceramics in the 10 K-300 K range are analyzed. In these compositionally disordered materials, RE3+ substitute Ca2+ in dodecahedral sites and the charge compensation is accomplished by adjusting the proportion of Li+, Nb5+, and Ga3+ to the doping concentration. The crystals and ceramics show similar optical spectra, with broad and structured (especially at low temperatures) bands whose shape depends on temperature and doping concentration. At 10 K, the Nd3+ 4I9/2 ? 4F3/2, 5/2 and Yb3+ 2F7/2 ? 2F5/2 absorption bands, which show prospect for diode laser pumping, can be decomposed in several lines that can be attributed to centers with large differences in the crystal field. The positions of these components are the same, but the relative intensity depends on the doping concentration and two main centers dominate the spectra. Non-selective excitation evidences broad emission bands, of prospect for short-pulse laser emission, whereas the selective excitation reveals the particular emission spectra of the various centers. The modeling reveals that the nonequivalent centers correspond to RE3+ ions with different cationic combinations in the nearest octahedral and tetrahedral coordination spheres, and the most abundant two centers have 4Nb and, respectively, 3Nb1Li in the nearest octahedral sphere. At 300 K, the spectral resolution is lost. It is then inferred that the observed optical bands are envelopes of the spectra of various structural centers, whose resolution is determined by the relative contribution of the temperature-dependent homogeneous broadening and the effects of crystal field disordering (multicenter structure, inhomogeneous broadening). The relevance of spectroscopic properties for selection of pumping conditions and of laser design that would enable utilization of the broad optical bands for efficient laser emission and reduced heat generation is discussed.

Lupei, V.; Lupei, A.; Gheorghe, C.; Gheorghe, L.; Achim, A.; Ikesue, A.

2012-09-01

79

Crystal field disorder effects in the optical spectra of Nd{sup 3+} and Yb{sup 3+}-doped calcium lithium niobium gallium garnets laser crystals and ceramics  

SciTech Connect

The optical spectroscopic properties of RE{sup 3+} (Nd, 1 at. % or Yb, 1 to 10 at. %)-doped calcium-lithium-niobium-gallium garnet (CLNGG) single crystals and ceramics in the 10 K-300 K range are analyzed. In these compositionally disordered materials, RE{sup 3+} substitute Ca{sup 2+} in dodecahedral sites and the charge compensation is accomplished by adjusting the proportion of Li{sup +}, Nb{sup 5+}, and Ga{sup 3+} to the doping concentration. The crystals and ceramics show similar optical spectra, with broad and structured (especially at low temperatures) bands whose shape depends on temperature and doping concentration. At 10 K, the Nd{sup 3+4}I{sub 9/2}{yields}{sup 4}F{sub 3/2,5/2} and Yb{sup 3+2}F{sub 7/2}{yields}{sup 2}F{sub 5/2} absorption bands, which show prospect for diode laser pumping, can be decomposed in several lines that can be attributed to centers with large differences in the crystal field. The positions of these components are the same, but the relative intensity depends on the doping concentration and two main centers dominate the spectra. Non-selective excitation evidences broad emission bands, of prospect for short-pulse laser emission, whereas the selective excitation reveals the particular emission spectra of the various centers. The modeling reveals that the nonequivalent centers correspond to RE{sup 3+} ions with different cationic combinations in the nearest octahedral and tetrahedral coordination spheres, and the most abundant two centers have 4Nb and, respectively, 3Nb1Li in the nearest octahedral sphere. At 300 K, the spectral resolution is lost. It is then inferred that the observed optical bands are envelopes of the spectra of various structural centers, whose resolution is determined by the relative contribution of the temperature-dependent homogeneous broadening and the effects of crystal field disordering (multicenter structure, inhomogeneous broadening). The relevance of spectroscopic properties for selection of pumping conditions and of laser design that would enable utilization of the broad optical bands for efficient laser emission and reduced heat generation is discussed.

Lupei, V.; Lupei, A.; Gheorghe, C.; Gheorghe, L.; Achim, A. [National Institute for Lasers, Plasma and Radiation Physics, Lab. ECS, Bucharest (Romania); Ikesue, A. [World-Lab Co. Ltd., Atsuta-ku, Nagoya 456-8587 (Japan)

2012-09-15

80

High energy resolution with transparent ceramic garnet scintillators  

NASA Astrophysics Data System (ADS)

Breakthrough energy resolution, R(662keV) < 4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce). Transparent ceramic GYGAG(Ce), has a peak emission wavelength of 550 nm that is better matched to Silicon photodetectors than to standard PMTs. We are therefore developing a spectrometer based on pixelated GYGAG(Ce) on a Silicon photodiode array that can provide R(662 keV) = 3.6%. In comparison, with large 1-2 in3 size GYGAG(Ce) ceramics we obtain R(662 keV) = 4.6% with PMT readout. We find that ceramic GYGAG(Ce) of a given stoichiometric chemical composition can exhibit very different scintillation properties, depending on sintering conditions and post-anneal treatments. Among the characteristics of transparent ceramic garnet scintillators that can be controlled by fabrication conditions are: scintillation decay components and their amplitudes, intensity and duration of afterglow, thermoluminescence glow curve peak positions and amplitudes, integrated light yield, light yield non-proportionality - as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI), and energy resolution for gamma spectroscopy. Garnet samples exhibiting a significant fraction of Cerium dopant in the tetravalent valence also exhibit: faster overall scintillation decay, very low afterglow, high light yield, but poor light yield proportionality and degraded energy resolution.

Cherepy, N. J.; Seeley, Z. M.; Payne, S. A.; Beck, P. R.; Swanberg, E. L.; Hunter, S.; Ahle, L.; Fisher, S. E.; Melcher, C.; Wei, H.; Stefanik, T.; Chung, Y.-S.; Kindem, J.

2014-09-01

81

Electronic sputtering of Gd 3Ga 5O 12 and Y 3Fe 5O 12 garnets: Yield, stoichiometry and comparison to track formation  

NASA Astrophysics Data System (ADS)

The results of present paper have shown that sputtering of yttrium iron garnet (Y 3Fe 5O 12) under swift heavy ions in the electronic energy loss regime is non-stoichiometric. Here we are presenting additional experimental results for gadolinium gallium garnet (Gd 3Ga 5O 12) as target. The irradiations were performed with different ions ( 50Cr (589 MeV), 86Kr (195 MeV) and 181Ta (400 MeV)) impinging perpendicularly to the surface. As earlier, the sputtering yield was determined by collecting the emitted gadolinium and gallium atoms on a thin aluminium foil, placed upstream above the target and analyzing the Al catcher by Rutherford backscattering. Also for Gd 3Ga 5O 12, the emission of Gd and Ga is non-stoichiometric. Sputtering appears above a critical electronic stopping power of S th = 11.6 ± 1.5 keV/nm, which is larger than the threshold for track formation, in agreement with other amorphisable materials. In addition, the angular distribution of the sputtered species was measured for Y 3Fe 5O 12 and Gd 3Ga 5O 12 using 200 MeV Au ions impinging the surface at 20° relatively to the surface. For the two garnets the ratio of Y/Fe (and Gd/Ga) varies with the angle of emitted species and the stoichiometry seems to be preserved only for an emission perpendicular to the surface.

Meftah, A.; Assmann, W.; Khalfaoui, N.; Stoquert, J. P.; Studer, F.; Toulemonde, M.; Trautmann, C.; Voss, K.-O.

2011-05-01

82

Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization  

SciTech Connect

Yttrium iron garnet (YIG, Y {sub 3}Fe{sub 5}O{sub 12}) films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd{sub 3}Ga{sub 5}O{sub 12}) substrates with (100) orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe), near-bulk room temperature saturation moments (?135 emu cm{sup ?3}), in-plane easy axis, and damping parameters as low as 2.2 × 10{sup ?4}. These high quality YIG thin films are useful in the investigation of the origins of novel magnetic phenomena and magnetization dynamics.

Onbasli, M. C., E-mail: onbasli@mit.edu; Kim, D. H.; Ross, C. A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Kehlberger, A. [Institute of Physics, Johannes Gutenberg-University of Mainz, 55099 Mainz (Germany); Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz (Germany); Jakob, G.; Kläui, M. [Institute of Physics, Johannes Gutenberg-University of Mainz, 55099 Mainz (Germany); Chumak, A. V.; Hillebrands, B. [Fachbereich Physik and Landesforschungszentrum, OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany)

2014-10-01

83

Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG, Y 3Fe5O12) films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd3Ga5O12) substrates with (100) orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe), near-bulk room temperature saturation moments (˜135 emu cm-3), in-plane easy axis, and damping parameters as low as 2.2 × 10-4. These high quality YIG thin films are useful in the investigation of the origins of novel magnetic phenomena and magnetization dynamics.

Onbasli, M. C.; Kehlberger, A.; Kim, D. H.; Jakob, G.; Kläui, M.; Chumak, A. V.; Hillebrands, B.; Ross, C. A.

2014-10-01

84

April 1, 1993 / Vol. 18, No. 7 / OPTICS LETTERS 511 Monolithic self-Q-switched Cr,Nd:YAGlaser  

E-print Network

, such as gadolinium scandium gallium garnet, forsterite, and yttrium aluminum garnet (YAG) were found to exhibit switching and mode locking in Nd:YAG lasers.2 When YAG and gadolinium scandium gallium garnet host crystals

85

Industrial garnet  

USGS Publications Warehouse

A general overview of the industrial garnet industry is provided. About 20 percent of global industrial garnet production takes place in the U.S. During 2000, an estimated 300 kt of industrial garnets were produced worldwide. The U.S. is the world's largest consumer of industrial garnet, consuming 56.9 kt in 2000.

Olson, D.W.

2001-01-01

86

RBS and XRD Characterization of Yttrium Iron Garnet Thin Films  

NASA Astrophysics Data System (ADS)

Magnetic materials such as yttrium iron garnet (YIG or Y3Fe5O12) present a great importance for their magneto-optic properties. They are potential materials used for applications in the domain of optical telecommunications for example. In this work, we have investigated YIG thin films deposited on substrates of quartz and GGG (gadolinium gallium garnet or Gd3Ga5O12). Using Rutherford backscattering spectrometry (RBS) we characterized the performed layers (thickness and stoichiometry) in order to correlate the films preparation conditions with the quality of the final material. We determined the optimal energy of the alpha particles beam used for RBS measurements and we fitted the experimental spectra using the SIMNRA simulated code. Our RBS results showed that the films have a stoichiometry close to that of the starting material. In addition, we found that the film thickness is proportional to deposition time but inversely proportional to the substrate temperature. Moreover, using x-ray diffraction (XRD) we determined the annealing effect on the structure of the profile of our thin films.

Mansour, M.; Roumie, M.; Abdel Samad, B.; Basma, H.; Korek, M.

2015-03-01

87

Ce-doped single crystal and ceramic garnets for ?y ray detection  

SciTech Connect

Ceramic and single crystal Lutetium Aluminum Garnet scintillators exhibit energy resolution with bialkali photomultiplier tube detection as good as 8.6% at 662 keV. Ceramic fabrication allows production of garnets that cannot easily be grown as single crystals, such as Gadolinium Aluminum Garnet and Terbium Aluminum Garnet. Measured scintillation light yields of Cerium-doped ceramic garnets indicate prospects for high energy resolution.

Hull, G; Roberts, J; Kuntz, J; Fisher, S; Sanner, R; Tillotson, T; Drobshoff, A; Payne, S; Cherepy, N

2007-07-30

88

Transparent garnet ceramic scintillators for gamma-ray detection  

NASA Astrophysics Data System (ADS)

Lanthanide gallium/aluminum-based garnets have a great potential as host structures for scintillation materials for medical imaging. Particularly attractive features are their high density, chemical radiation stability and more importantly, their cubic structure and isotropic optical properties, which allow them to be fabricated into fully transparent, highperformance polycrystalline optical ceramics. Lutetium/gadolinium aluminum/gallium garnets (described by formulas ((Gd,Lu)3(Al,Ga)5O12:Ce, Gd3(Al,Ga)5O12:Ce and Lu3Al5O12:Pr)) feature high effective atomic number and good scintillation properties, which make them particularly attractive for Positron Emission Tomography (PET) and other ?- ray detection applications. The ceramic processing route offers an attractive alternative to single crystal growth for obtaining scintillator materials at relatively low temperatures and at a reasonable cost, with flexibility in dimension control as well as activator concentration adjustment. In this study, optically transparent polycrystalline ceramics mentioned above were prepared by the sintering-HIP approach, employing nano-sized starting powders. The properties and microstructures of the ceramics were controlled by varying the processing parameters during consolidation. Single-phase, high-density, transparent specimens were obtained after sintering followed by a pressure-assisted densification process, i.e. hot-isostatic-pressing. The transparent ceramics displayed high contact and distance transparency as well as high light yield as high as 60,000-65,000 ph/MeV under gamma-ray excitation, which is about 2 times that of a LSO:Ce single crystal. The excellent scintillation and optical properties make these materials promising candidates for medical imaging and ?-ray detection applications.

Wang, Yimin; Baldoni, Gary; Rhodes, William H.; Brecher, Charles; Shah, Ananya; Shirwadkar, Urmila; Glodo, Jarek; Cherepy, Nerine; Payne, Stephen

2012-10-01

89

Effects of processing on the low-voltage performance of cathodoluminescent garnet phosphors  

SciTech Connect

Field emission flat panel displays place new demands on the performance of cathodoluminescent phosphors. In particular, such phosphors must be efficient at lower voltages (ca. 100-1000 V), and must withstand higher current densities than are present on cathode ray tube screens. ZnO:Zn has been studied extensively as a low-voltage phosphor, but problems such as poor chromatic saturation and temperature sensitivity of emission remain. In this work the use of terbium-doped garnet phases such as yttrium aluminum garnet (YAG) and gadolinium gallium garnet (GGG) as low voltage green-emitting phosphors is evaluated. Hydrothermal synthesis yields well-faceted YAG grains with particle diameters of less than 1 {mu}m. Cathodoluminescent efficiency at a particular voltage was not affected by synthetic route, though the hydrothermally synthesized material was less susceptible to damage at high power densities. An efficiency of 3.5 lm/W was observed for GGG:Tb at 800 V. Deposition of the phosphors onto conducting screens increased their efficiencies at very low voltages (< 200 V). These materials may be considered alternatives to reduced zinc oxide as green-emitting phosphors.

Phillips, M.L.F.; Shea, L.E.

1995-08-01

90

Growth of High-Quality Yttrium Iron Garnet Thin Films on Metallic Electrodes  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) is a magnetic garnet and shows extremely low loss at microwave frequencies. One typically grows YIG on single-crystal gadolinium gallium garnet (GGG) substrates. For some monolithic on-chip device applications, however, one needs to grow YIG films on metallic electrodes. This is challenging due to problems with the oxidation, diffusion, and breakup of metallic electrodes during the deposition of YIG films at high temperatures. This presentation reports on the development of new sandwich-type bottom electrodes and the growth of low-loss YIG thin films on such electrodes. The new electrodes consist of a thick metallic layer sandwiched between two thin cladding layers. The thick layer is a high-conductivity metal. The thin cladding layers are materials with high oxidation resistance and good thermal stability. The electrodes were deposited at room temperature by magnetron sputtering, while the YIG films were deposited at 650 C by pulsed laser deposition. Scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy measurements confirmed the structure of the YIG films Static magnetic measurements indicated a saturation induction of about 1471 G, which was 16% smaller than that for a YIG bulk. Ferromagnetic resonance measurements yielded a peak-to-peak linewidth of about 0.8 Oe at 9.45 GHz.

Sun, Yiyan; Song, Young-Yeal; Wu, Mingzhong

2011-10-01

91

Magneto-optical study of holmium iron garnet Ho3Fe5O12  

NASA Astrophysics Data System (ADS)

Bulk holmium iron garnet Ho3Fe5O12 is a cubic ferrimagnet with Curie temperature TC = 567 K and magnetization compensation point in the range 130-140 K. The magneto-optical data are presented for a holmium iron garnet Ho3Fe5O12 film, ˜10 ?m thick, epitaxially grown on a (111)-type gadolinium-gallium garnet Gd3Ga5O12 substrate. A specific feature of this structure is that the parameters of the bulk material, from which the film was grown, closely match the substrate ones. The temperature and field dependences of Faraday rotation as well as the temperature dependence of the domain structure in zero field were investigated. The compensation point of the structure was found to be Tcomp = 127 K. It was shown that the temperature dependence of the characteristic size of domain structure diverges at this point. Based on the obtained results we established that the magnetic anisotropy of the material is determined by both uniaxial and cubic contributions, each characterized by different temperature dependence. A complex shape of hysteresis loops and sharp changes of the domain pattern with temperature indicate the presence of collinear-noncollinear phase transitions. Study of the optical second harmonic generation was carried out using 100 fs laser pulses with central photon energy E = 1.55 eV. The electric dipole contribution (both crystallographic and magnetic) to the second harmonic generation was observed with high reliability despite a small mismatch of the film and substrate parameters.

Kalashnikova, A. M.; Pavlov, V. V.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Pisarev, R. V.

2012-09-01

92

Fabrication and characterization of Bismuth-Cerium composite iron garnet epitaxial films for magneto optical applications  

NASA Astrophysics Data System (ADS)

The BixCe3-xFe5O12 (x = 0.8) epitaxial films of high quality were grown by means of pulsed laser deposition on paramagnetic substrates of Gadolinium Gallium Garnet. We study the modifications of substitutions in the parent garnet Y3Fe5O12 that produces a higher magneto-optical response at communication wavelengths. These films displayed a strong in plane textures which are treated in argon as well as reduced atmosphere conditions. The elemental constituents of these films were confirmed by energy dispersive-X ray analysis, elastic recoil detection system, Rutherford backscattering spectroscopy, and X-ray photoelectron spectroscopy measurements. The transmittance spectra were measured and found these films exhibit good transmittance values. The transmittance-spectra were fitted with the theoretical model and the optical constants such as refractive index and absorption edge were evaluated. The highest (negative) Faraday rotation was found for these films treated in the environment of Ar + H2. A density matrix theory has been developed for the Faraday rotation and a good agreement between the theory and experiment is found. These epitaxial garnet films can be used in a wide range of frequencies from visible to infrared spectra making them ideal for many magneto optical applications. Therefore, these films may overcome many issues in fabricating all optical isolators which is the viable solution for integrated photonics.

Chandra Sekhar, M.; Singh, Mahi R.

2012-10-01

93

Ferrimagnetism in the rare-earth iron garnets: a Monte Carlo study.  

PubMed

We investigate classical vector spin models of the rare-earth iron garnet ferrimagnets yttrium iron garnet (YIG) and gadolinium iron garnet (GdIG) using Monte Carlo simulations. Critical temperatures agree well with experiment. A compensation point is observed in GdIG, again in good agreement with experiment. PMID:21817454

Oitmaa, J; Falk, Thomas

2009-03-25

94

Industrial garnet  

USGS Publications Warehouse

Garnet has been used as a gemstone since the Bronze Age. However, garnet’s angular fractures, relatively high hardness and specific gravity, chemical inertness and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

Olson, D.W.

2013-01-01

95

Gallium and gallium arsenide  

SciTech Connect

As part of the Nation's growing concern with the competitiveness of U.S. firms in the world economy, especially with respect to advanced materials, the Bureau of Mines assessed the actual and potential recovery and manufacturing capabilities for gallium and gallium arsenide (GaAs). GaAs has advanced from a laboratory curiosity to a material with important high-tech applications within only the last few years, and although protected North American gallium supplies are currently considered adequate, consumption could grow to the point that this assessment would need reevaluation.

Kramer, D.

1988-01-01

96

Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties  

SciTech Connect

Graphical abstract: Faraday hysteresis loops for Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} film on glass-ceramic substrate (a), Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} film on gallium–gadolinium garnet (b) and for glass-ceramic/SiO{sub 2}/Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12}/Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} structure (c). Highlights: ? Bismuth-substituted iron garnet films as magneto-optical layers in magneto-photonic crystals. ? It is impossible to crystallize the films with high Bi content on amorphous substrates. ? The crystallization of the films can be achieved by their deposition on buffer layer with low bismuth content. -- Abstract: The crystallization processes in Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12}, Bi{sub 2.5}Gd{sub 0.5}Fe{sub 3.8}Al{sub 1.2}O{sub 12}, Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12} and Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} garnet films deposited by reactive ion beam sputtering on (1 1 1) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO{sub 2} films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO{sub 2} films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/?m for the visible optical spectrum).

Shaposhnikov, A.N.; Karavainikov, A.V.; Prokopov, A.R.; Berzhansky, V.N. [Taurida National V.I. Vernadsky University, Vernadsky Av., 4, 95007 Simferopol (Ukraine)] [Taurida National V.I. Vernadsky University, Vernadsky Av., 4, 95007 Simferopol (Ukraine); Salyuk, O.Y., E-mail: olga-saliuk@yandex.ru [Institute of Magnetizm NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine)

2012-06-15

97

Garnet polycrystals  

NASA Astrophysics Data System (ADS)

Electron backscattered diffraction (EBSD) studies have revealed complex microstructures in garnet, including features developed during crystal growth and/or deformation. New data show that garnets commonly grow as clusters of grains (polycrystals) juxtaposed by high-angle boundaries. Garnet polycrystals may form at any stage of metamorphism following nucleation of garnet: polycrystals may form early as a result of close spacing of nuclei, or later via impingement of larger grains. EBSD analysis of garnets in metamorphic rocks from 9 localities in the US, Canada, Turkey, Iran, and Colombia detected polycrystals at every site. Evidence for internal deformation of garnet was observed in only one sample, a calc-pelite dominated by plagioclase; all other samples are mica schists. Three sites displayed garnet shape-preferred orientation, but none had a crystallographic preferred orientation of garnet. In some samples, polycrystals comprise ~20-30% of garnets analyzed. Some early-coalescing polycrystals exhibit growth zoning concentric about the geometric center of the polycrystal; i.e., zoning is unrelated to the location of internal grain boundaries. In other polycrystals, Fe-Mn-Mg zoning has a different pattern than that of Ca. Some polycrystals are characterized by high-angle misorientation boundaries in special orientations, indicating that these polycrystals are not random clusters of grains. Special boundaries were detected in 0-60% of garnets analyzed. Polycrystal formation may relate to the presence of chemical or textural heterogeneities (e.g. precursor phases, deformation features) that allowed close spacing of garnet nuclei. It is important to recognize polycrystals because internal grain boundaries may affect diffusion pathways and length scales and may facilitate communication of garnet interiors with matrix phases, thereby influencing reaction history and garnet composition and zoning.

Whitney, Donna; Seaton, Nca

2010-05-01

98

Industrial garnet  

USGS Publications Warehouse

Garnet has been used as a gemstone since the Bronze Age. However, garnet's angular fractures, relatively high hardness and specific gravity, chemical inertness and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

Olson, D.W.

2011-01-01

99

Industrial garnet  

USGS Publications Warehouse

In 2009, U.S. production of crude garnet concentrate for industrial use was estimated to be 56.5 kt (62,300 st), valued at about $8.85 million. This was a 10-percent decrease in quantity compared with 2008 production. Refined garnet material sold or used was 28 kt (31,000 st) valued at $7.96 million.

Olson, D.W.

2010-01-01

100

Industrial garnet  

USGS Publications Warehouse

Garnet has been used as a gemstone since the Bronze Age. However, garnet's angular fractures, relatively high hardness and specific gravity, chemical inertness, and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

Olson, D.W.

2012-01-01

101

Induced Magneto-transport Effects in Non-magnetic Metals on Yttrium Iron Garnet  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) was called ``spin Seebeck insulator,'' for it supports heat-generated pure spin currents. Pt thin film, with strong spin-orbit interaction, is used as a spin current generator or detector based on the spin Hall effect or the inverse spin Hall effect. The combination of these two materials plays a very important role in spintronics. A recent magnetotransport study shows strong evidence of a magnetic proximity effect in thin Pt films deposited on YIG. Here, we present a magneto-transport study of several non-magnetic (NM) metal films (e.g. Pt, Pd) on YIG films grown on gadolinium gallium garnet substrates with laser molecular beam epitaxy. The anisotropic magnetoresistance (AMR) and anomalous Hall effect (AHE) reveal clear ferromagnetic characteristics in NM films. The magnitude of the AHE angle ? in Pd/YIG structure increases with decreasing temperature, while ? in Pt/YIG structure has a sign reversal at an intermediate temperature. Both AMR and AHE have been investigated as the NM film thickness is varied and an optimal effective thickness is identified. The effect of annealing has also been studied and the results are consistent with the observed thickness dependence. In thin NM films, a ln(T) temperature dependence with a resistivity minimum is observed at low temperatures, suggesting that the Kondo effect may be relevant. Detailed discussions about the origin of these effects will be presented.

Lin, Tao; Tang, Chi; Shi, Jing

2013-03-01

102

Industrial garnet  

USGS Publications Warehouse

In 2005, US production of crude garnet concentrate for industrial use was 28.4 kt valued at $3.05 million. Refined garnet material sold or used was 30.4 kt valued at $10 million. For the year, the US was one of the world's leading consumers of industrial garnet. Domestic values for crude concentrates for different applications ranged from about $53 to $120/t. In the short term, excess production capacity, combined with suppliers that vary in quality, grain size and mineral type, will keep prices down.

Olson, D.W.

2006-01-01

103

Garnet-to-Perovskite Transition in Gd3Sc2Ga3O12 at High Pressure and High Temperature  

E-print Network

Garnet-to-Perovskite Transition in Gd3Sc2Ga3O12 at High Pressure and High Temperature Chuanlong Lin-scandium-gallium garnet (Gd3Sc2Ga3O12, GSGG) has been studied at high pressure and high temperature using the synchrotron X-ray diffraction technique in a laser-heated diamond anvil cell. The GSGG garnet transformed

Lin, Jung-Fu "Afu"

104

Industrial garnet  

USGS Publications Warehouse

The state of the global industrial garnet industry in 1999 is discussed. Industrial garnet mined in the U.S., which accounts for approximately one-third of the world's total, is usually a solid-solution of almandine and pyrope. The U.S. is the largest consumer of industrial garnet, using an estimated 47,800 st in 1999 as an abrasive and as a filtration medium in the petroleum industry, filtration plants, aircraft and motor vehicle manufacture, shipbuilding, wood furniture finishing operations, electronic component manufacture, ceramics manufacture, and glass production. Prices for crude concentrates ranged from approximately $50 to $110/st and refined garnet from $50 to $215/st in 1999, depending on type, source, quantity purchased, quality, and application.

Olson, D.W.

2000-01-01

105

Electrically and magnetically tunable phase shifters based on a barium strontium titanate-yttrium iron garnet layered structure  

NASA Astrophysics Data System (ADS)

We report on the tuning of permittivity and permeability of a ferroelectric/ferromagnetic bilayer structure which can be used as a microwave phase shifter with two degrees of tuning freedom. The structure was prepared by the growth of a yttrium iron garnet (YIG) layer on a gadolinium gallium garnet substrate by liquid phase epitaxy, the growth of a barium strontium titanate (BST) layer on the YIG layer through pulsed laser deposition, and then the fabrication of a coplanar waveguide on the top of BST through e-beam evaporation and trilayer liftoff techniques. The phase shifters exhibit a differential phase shift of 38°/cm at 6 GHz through permittivity tuning under an applied electric field of ˜75 kV/cm and a static magnetic field of 1700 Oe. By tuning the permeability through the applied magnetic field we increase the differential phase shift to 52°/cm and simultaneously obtain a better match to the zero applied electric field condition, resulting in an improvement in the return loss from 22.4 to 24.9 dB. Additionally, we demonstrate the use of a lead magnesium niobate-lead titanate (PMN-PT) layer to tune the permeability of the YIG layer. This tuning relies on the piezoelectric and magnetostrictive effects of PMN-PT and YIG, respectively. Tuning of the ferromagnetic response through strain and magnetostriction as opposed to applied magnetic field can potentially pave the way for low power consumption, continuously and rapidly tunable, impedance matched phase shifters.

Leach, J. H.; Liu, H.; Avrutin, V.; Rowe, E.; Özgür, Ü.; Morkoç, H.; Song, Y.-Y.; Wu, M.

2010-09-01

106

Control of Ferromagnetic Relaxation in Magnetic Thin Films through Thermally Induced Interfacial Spin Transfer  

E-print Network

for the first time. The experiments used a trilayered structure that consisted of an yttrium iron garnet (YIG) thin film grown on a gadolinium gallium garnet substrate and capped with a nanometer- thick Pt layer of a micron-thick yttrium iron garnet (YIG) film grown on a submillimeter-thick gadolinium gallium garnet (GGG

107

Industrial garnet  

USGS Publications Warehouse

World production of industrial garnet was about 326 kt in 2006, with the U.S. producing about 11 percent of this total. U.S. consumption, imports, and exports were estimated at 74.3 kt, 52.3 kt, and 13.2 kt, respectively. The most important exporters are Australia, China, and India. Although demand is expected to rise over the next 5 years, prices are expected to remain low in the short term.

Olson, D.W.

2007-01-01

108

NUMEX GARNET PAPRIKA  

Technology Transfer Automated Retrieval System (TEKTRAN)

'NuMex Garnet' is an open-pollinated, high extractable color, low pungency, paprika-type chile pepper (Capsicum annuum L.). The high extractable color, high percent dry matter, and low pungency of 'NuMex Garnet' makes this cultivar particularly suited for pigment extraction. 'NuMex Garnet' originat...

109

Gadolinium photoionization process  

DOEpatents

A method is provided for selective photoionization of the odd-numbered atomic mass gadolinium isotopes 155 and 157. The selective photoionization is accomplished by circular or linear parallel polarized laser beam energy effecting a three-step photoionization pathway.

Paisner, J.A.; Comaskey, B.J.; Haynam, C.A.; Eggert, J.H.

1993-04-13

110

Gadolinium photoionization process  

DOEpatents

A method is provided for selective photoionization of the odd-numbered atomic mass gadolinium isotopes 155 and 157. The selective photoionization is accomplished by circular or linear parallel polarized laser beam energy effecting a three-step photoionization pathway.

Paisner, Jeffrey A. (San Ramon, CA); Comaskey, Brian J. (Stockton, CA); Haynam, Christopher A. (Pleasanton, CA); Eggert, Jon H. (Pleasanton, CA)

1993-01-01

111

Electrospun cellulose acetate-garnet nanocomposite magnetic fibers for bioseparations.  

PubMed

Cellulose acetate fibers with magnetic properties have recently attracted much attention because of their potential novel applications in biomedicine such as for cell and protein separations, magnetic resonance imaging contrast agents, and magnetic filters. In this work, as synthesized yttrium iron garnet and gadolinium substituted yttrium iron garnet nanoparticles have been used to generate magnetic filter paper. Garnet nanoparticles dispersed in cellulose acetate polymer solutions were electrospun as free-standing nonwoven fiber mats as well as on cellulose filter paper substrates resulting in magnetic filter papers. The magnetic fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and superconducting quantum interference device (SQUID) magnetic property measurements. The resulting magnetic polymer nanocomposites can be easily picked up by an external magnet from a liquid medium. Fluorescein isothiocyanate (FITC) labeled bovine serum albumin (BSA) was separated from solution by using the magnetic filter paper. PMID:24341636

Munaweera, Imalka; Aliev, Ali; Balkus, Kenneth J

2014-01-01

112

Molecular Structure of Garnet  

NSDL National Science Digital Library

Garnet has been used in gemstones for many thousands of years. The Koran states that the fourth heaven is composed of carbuncle, which is another name given to the beautiful gem. Garnet is a very abundant gem and can easily be found in many places around the world. Application: Garnet is a silicate mineral and is the birthstone of January. It is also used for many abrasive purposes, and is the symbolic gemstone for the 18th wedding anniversary.

2002-09-06

113

Rare-Earth Garnets and Perovskites for Space-Based ADR Cooling at High T and Low H  

NASA Technical Reports Server (NTRS)

Future NASA satellite detector systems must be cooled to the 0.1 K temperature range to meet the stringent energy resolution and sensitivity requirements demanded by mid-term astronomy missions. The development of adiabatic demagnetization refrigeration (ADR) materials that can efficiently cool from the passive radiative cooling limit of approx. 30 K down to sub-Kelvin under low magnetic fields (H less than or equal to 3 T) would represent a significant improvement in space-based cooling technology. Governed by these engineering goals, our efforts have focused on quantifying the change in magnetic entropy of rare-earth garnets and perovskites. Various compositions within the gadolinium gallium iron garnet solid solution series (GGIG, Gd3Ga(5-x)Fe(x)O12, 0.00 less than or equal to X less than or equal to 5.00) and gadolinium aluminum perovskite (GAP, GdAlO3) have been synthesized via an organometallic complex approach and confirmed with powder x-ray diffraction. The magnetization of the GGIG and GAP materials has been measured as a function of composition (0.00 less than or equal to X less than or equal to 5.00), temperature (2 K less than or equal to T less than or equal to 30 K) and applied magnetic field (0 T less than or equal to H less than or equal to 3 T). The magnetic entropy change (DeltaS(sub mag)) between 0 T and 3 T was determined from the magnetization data. In the GGIG system, DeltaS(sub mag) was compositionally dependent; Fe(sup 3+) additions up to X less than or equal to 2.44 increased DeltaS(sub mag) at T > 5 K. For GAP, DeltaS(sub mag) was similar to that of GGIG, X = 0.00, both in terms of magnitude and temperature dependence at T > 10 K. However, the DeltaS(sub mag) of GAP at T < 10 K was less than the endmember GGIG composition, X = 0.00, and exhibited maximum approx. 5 K.

King, T. T.; Rowlett, B. A.; Ramirez, R. A.; Shirron, P. J.; Canavan, E. R.; DiPirro, M. J.; Panek, J. S.; Tuttle, J. G.; Shull, R. D.; Fry, R. A.; Brodeur, Stephen J. (Technical Monitor)

2001-01-01

114

Garnets as hydrochronometers  

SciTech Connect

This study examines oxygen isotope zoning in garnets from a Barrovian metamorphic terrane in eastern Vermont. Previous Sr isotopic and structural studies of these garnets have shown that they grew over an approximately 10 myr interval during thrusting and nappe emplacement. These studies show that the garnets are strongly zoned in delta O-18. This zoning is the result of equilibration of garnet with water derived from dehydration of subjacent pelites during nappe stage deformation. The magnitude of delta O-18 zoning depends upon the garnet's location in the outcrop studied. The garnets come from an isotopically light delta O-18 felsic schist that is adjacent a relatively heavy delta O-18 schist. Garnets from the felsic schists within 10 meters of the contact with the isotopically heavier schists have nearly homogeneous dealt O-18 values around 9.5[per thousand]. Garnet in the felsic schists 85 meters from the contact are more strongly zoned, with delta O-18 ranging from a low of ca 6.0[per thousand] in the cores to a high of ca 9.0[per thousand] at the rims. These zoning patterns were produced by continuous infiltration of relatively heavy delta O-18 waters, derived from the subjacent schists into the felsic schists during garnet grade metamorphism. It is possible to determine the time integrated fluid fluxes by comparison of observed zoning profiles in garnet with those calculated from the equation describing combined advective-diffusive of a tracer. Using this method, the authors calculate time integrated fluid fluxes of 1.5 [times] 10[sup 4] cm[sup 3]/cm[sup 2]. Fluxes of this magnitude could have been produced by dewatering of 1.5 km of schist during garnet grade metamorphism.

Chamberlain, C.P. (Dartmouth Univ., Hanover, NH (United States). Dept. of Earth Sciences); Conrad, M.E. (Lawrence Berkeley Lab., Berkeley, CA (United States))

1992-01-01

115

Temperature Dependent Fluorescence Ce-doped Garnets for Use as Thermographic Phosphors  

E-print Network

emission is most likely due to Cr3+ contamination. Emission characteristics such as multiexponential decay Characterization Conclusions Oil Bath Oscilloscope and Computer Monochromator Select Wavelength Select Slit Width+ contamination. Cerium- and gallium-doped garnets were made by preparing an aqueous solution containing

Walker, D. Greg

116

Temperature dependence of the 1.06-microm stimulated emission cross section of neodymium in YAG and in GSGG.  

PubMed

A linear temperature dependence between -70 degrees C and +70 degrees C is reported for the peak stimulated emission cross section of Nd3+ ions in both yttrium aluminum garnet (YAG) and gadolinium scandium gallium garnet (GSGG). PMID:12463252

Rapaport, Alexandra; Zhao, Shengzhi; Xiao, Guohua; Howard, Andrew; Bass, Michael

2002-11-20

117

Paramagnetic beads surfing on domain walls L. E. Helseth* and T. M. Fischer  

E-print Network

garnet films grown by liquid phase epitaxy on 0.5 mm thick 100 gadolinium gallium garnet substrates to generate the DWs. For details about the garnet films, see Ref. 13 . In the current paper we report studies applying two garnet films, both of thickness 4 m. Due to the low uniaxial anisotropy, these garnet films

Johansen, Tom Henning

118

Nonlinear effects in magnetic garnet films and nonreciprocal optical Bloch oscillations in waveguide arrays  

NASA Astrophysics Data System (ADS)

This dissertation presents detailed experimental and theoretical investigations of nonlinear and nonreciprocal effects in magnetic garnet films. The dissertation thus comprises two major sections. The first section concentrates on the study of a new class of nonlinear magneto-optic thin film materials possessing strong higher order magnetic susceptibility for nonlinear optical applications. The focus was on enlarging the nonlinear performance of ferrite garnet films by strain generation and compositional gradients in the sputter-deposition growth of these films. Under this project several bismuth-substituted yttrium iron garnet (Bi,Y)3(Fe,Ga)5O12 (acronym as Bi:YIG) films have been sputter-deposited over gadolinium gallium garnet (Gd 3Ga5O12) substrates and characterized for their nonlinear optical response. One of the important findings of this work is that lattice mismatch strain drives the second harmonic (SH) signal in the Bi:YIG films, in agreement with theoretical predictions; whereas micro-strain was found not to correlate significantly with SH signal at the micro-strain levels present in these films. This study also elaborates on the role of the film's constitutive elements and their concentration gradients in nonlinear response of the films. Ultrahigh sensitivity delivered by second harmonic generation provides a new exciting tool for studying magnetized surfaces and buried interfaces, making this work important from both a fundamental and application point of view. The second part of the dissertation addresses an important technological need; namely the development of an on-chip optical isolator for use in photonic integrated circuits. It is based on two related novel effects, nonreciprocal and unidirectional optical Bloch oscillations (BOs), recently proposed and developed by Professor Miguel Levy and myself. This dissertation work has established a comprehensive theoretical background for the implementation of these effects in magneto-optic waveguide arrays. The model systems we developed consist of photonic lattices in the form of one-dimensional waveguide arrays where an optical force is introduced into the array through geometrical design turning the beam sideways. Laterally displaced photons are periodically returned to a central guide by photonic crystal action. The effect leads to a novel oscillatory optical phenomenon that can be magnetically controlled and rendered unidirectional. An on-chip optical isolator was designed based on the unidirectionality of the magneto-opticBloch oscillatory motion. The proposed device delivers an isolation ratio as high as 36 dB that remains above 30 dB in a 0.7 nm wavelength bandwidth, at the telecommunication wavelength 1.55 mum. Slight modifications in isolator design allow one to achieve an even more impressive isolation ratio ~ 55 dB, but at the expense of smaller bandwidth. Moreover, the device allows multifunctionality, such as optical switching with a simultaneous isolation function, well suited for photonic integrated circuits.

Kumar, Pradeep

119

Gadolinium induces macrophage apoptosis  

Microsoft Academic Search

Gadolinium (Gd) suppresses reticuloen- dothelial functions in vivo by unknown mechanisms. In vitro exposure of rat alveolar macrophages to GdC136H2O caused cell death, as measured by try- pan blue permeability, in both dose- and time-de- pendent fashions. Even a 10-mm exposure to Gd caused significant cell death by 24 h. The morphol- ogy of Gd-treated cells, pyknosis and karyorrhexis prior

Joseph P. Mizgerd; Ramon M. Molina; Rebecca C. Stearns; Joseph D. Brain; Angeline E. Warner

1996-01-01

120

Investigations in gallium removal  

SciTech Connect

Gallium present in weapons plutonium must be removed before it can be used for the production of mixed-oxide (MOX) nuclear reactor fuel. The main goal of the preliminary studies conducted at Texas A and M University was to assist in the development of a thermal process to remove gallium from a gallium oxide/plutonium oxide matrix. This effort is being conducted in close consultation with the Los Alamos National Laboratory (LANL) personnel involved in the development of this process for the US Department of Energy (DOE). Simple experiments were performed on gallium oxide, and cerium-oxide/gallium-oxide mixtures, heated to temperatures ranging from 700--900 C in a reducing environment, and a method for collecting the gallium vapors under these conditions was demonstrated.

Philip, C.V.; Pitt, W.W. [Texas A and M Univ., College Station, TX (United States); Beard, C.A. [Amarillo National Resource Center for Plutonium, TX (United States)

1997-11-01

121

Bulk cubic gallium nitride  

SciTech Connect

Bulk cubic gallium nitride is made by charging into a reaction vessel to a fill of 25--95% having a temperature difference between its ends of at least 1 deg C a gallium precursor, sufficient amount of an acid mineralizer to form product zinc blende gallium nitride, and sufficient amount of ammonia to at least solubilize the precursor; sealing the reaction vessel; heating contents of the reaction vessel to at least 150 deg C while autogenously pressurizing contents of the reaction vessel to at least 500 psi for a duration sufficient to form the product zinc blende gallium nitride; cooling contents of the reaction vessel; and removing from the reaction vessel the product zinc blende gallium nitride.

Purdy, A.P.

1999-01-01

122

Hydroxyl in garnets from Garnet Ridge, northern Arizona  

NASA Astrophysics Data System (ADS)

Various kinds of garnets and garnet-bearing rocks occur in Garnet Ridge, northern Arizona. These garnets have diverse origins such as mantle peridotite, subducted oceanic slab and crustal level metasomatic products (Koga & Ogasawara, 2012, AGU Fall Meeting Abstract). A typical garnet from Garnet Ridge, called "Navajo Ruby" is Cr-bearing pyrope-rich garnet that could be of the mantle peridotite origin, and another interesting garnet occurs in eclogite xenoliths of subducted slab origin, probably of Farallon plate origin (Usui et al., 2003). To understand the water behavior underneath the Colorado Plateau, we measured micro FT-IR spectra for several kinds of garnets from Garnet Ridge. The samples for micro FT-IR analyses are thick sections (50 - 500 micrometer in thickness). The size of analyzed areas is 50 x 50 ?m square. We detected significant amounts of OH in "Navajo Ruby" garnets and in other types of garnets; however, OH in the garnet in eclogite xenolith was negligible or below detection limit. The peridotitic garnets (up to 2 cm across) look purplish to red brownish and are rich in pyrope component (up to 78 mol%) with significant amounts of Cr2O3 (up to 5.9 wt%) without chemical zonation. The inclusions of olivine, clinopyroxene, orthopyroxene and apatite were confirmed by laser Raman spectroscopy. The representative FT-IR absorption spectra of this type garnet are: 1) grain A (Pyp52 Alm29 Sps1 Grs14 And2 Uv2) shows two very strong IR absorption bands by OH centered at 3575 and 3660 cm-1, 2) grain B (Pyp63 Alm14 Sps0 Grs12 And1 Uv10) shows a very strong IR absorption at 3575 cm-1, and 3) grain C (Pyp62 Alm20 Sps1 Grs12 And0 Uv5) did not show IR absorption by OH. No heterogeneity of IR absorption by OH was detected in a single grain. The garnets in eclogite xenolith show clear prograde chemical zonation; core (Pyp6 Alm54 Sps1 Grs34 And5 Uv0) to rim (Pyp21 Alm64 Sps2 Grs15 And1 Uv0). The well developed rim of this garnet has no IR absorption band by OH although very weak IR absorption band was detected in the core. Judging from our micro FT-IR spectra, OH content of eclogitic garnet is very low or below the detection limit. We also measured IR spectra of other garnets. Garnet megacrysts (up to 8 cm in diameter) and garnet aggregates are plotted at almost center of Grs-Alm-Pyp triangle, and their IR spectra (the representative grain: Pyp41 Alm28 Sps1 Grs30 And1 Uv0) show two very strong IR absorption bands of OH at 3565 and 3680 cm-1. In a strange rock like skarn, a metasomatic product at crustal level, the garnet (Pyp2 Alm35 Sps1 Grs56 And5 Uv0) has very strong IR absorption bands at 3563, 3590 and 3638 cm-1. Significant amounts of OH in the peridotitic garnets, "Navajo Ruby" suggest that the pyrope-rich garnet was a water reservoir in the mantle peridotites and no other phase could store water. On the other hand, in the eclogites subducted underneath the Colorado Plateau, omphacite could play a role of a water reservoir instead of garnet. References: Koga, I., Ogasawara, Y. (2012) AGU Fall Meeting Abstracts, V052. Usui, T., Nakamura, E., Kobayashi, K. Maruyama, S., Helmstaedt, H. (2003) Geology, 31, 589-592.

Ogasawara, Y.; Sakamaki, K.; Koga, I.

2012-12-01

123

Mineral of the month: garnet  

USGS Publications Warehouse

Garnet is the general name given to a group of complex silicate minerals, all with isometric crystal structure, similar properties and chemical compositions. Garnet occurs in every color of the spectrum except blue, but it is most commonly red, purple, brown and green. Garnet necklaces dating from the Bronze Age have been found in graves and also among the ornaments adorning the oldest Egyptian mummies.

Olson, Donald

2005-01-01

124

Garnet-clinopyroxene geothermometer  

Microsoft Academic Search

A garnet-clinopyroxene geothermometer based on the available experimental data on compositions of coexisting phases in the system MgO-FeO-MnO-Al2O3-Na2O-SiO2 is as follows: \\u000a$$T({\\\\text{}}K) = \\\\frac{{8288 + 0.0276 P {\\\\text{(bar)}} + Q1 - Q2}}{{1.987 \\\\ln K_{\\\\text{D}} + 2.4083}}$$\\u000a where P is pressure, and Q1, Q2, and KD are given by the following equations \\u000a$$Q1 = 2,710{\\\\text{(}}X_{{\\\\text{Fe}}} - X_{{\\\\text{Mg}}} {\\\\text{)}} + 3,150{\\\\text{ }}X_{{\\\\text{Ca}}}

S. K. Saxena

1979-01-01

125

HoFe - Garnet soft XMCD measurements below and above the compensation temperature.  

PubMed

We have investigated the magnetism of Holmium-Iron-Garnet (Ho3Fe5O12) at the Ho M4,5 - the Fe L2,3 - and the O K - edges. As expected switching of the sub-lattice magnetization is observed at the compensation temperature. We will give detailed analysis ofthe Ho and Fe XMCD signals, using sum rules. Fe dichroism is analyzed in terms of 3d ground state moments and compared to Gadolinium-Iron-Garnet (Gd3Fe5O12). Contributions of octahedral and tetrahedral Fe sites could be separated and analyzed quantitatively. At the oxygen K edge two different structures are observable. Those structures show different temperature dependencies. Therefore we address these features separately to Fe and Rare Earth contributions. PMID:11512801

Goering, E; Gold, S; Schütz, G

2001-03-01

126

Rare earth elements in garnets and clinopyroxenes from garnet lherzolite nodules in kimberlites  

Microsoft Academic Search

Six pairs of coexisting garnets and clinopyroxenes were separated from the sheared and granular garnet lherzolite nodules in kimberlites and analyzed for rare earth elements (REE). The sheared and granular nodules can be distinguished in terms of REE pattern of both clinopyroxene and garnet. However, there are no significant differences in REE partitioning between clinopyroxene and garnet, indicating that the

N. Shimizu

1975-01-01

127

Gallium interactions with Zircaloy  

SciTech Connect

This study focuses on the effects of gallium ion implantation into zircaloy cladding material to investigate the effects that gallium may have in a reactor. High fluence ion implantation of Ga ions was conducted on heated Zircaloy-4 in the range of 10{sup 16}--10{sup 18} Ga ions/cm2. Surface effects were studied using SEM and electron microprobe analysis. The depth profile of Ga in the Zircaloy was characterized with Rutherford backscattering and SIMS techniques. Results indicate that the Zirc-4 is little affected up to a fluence of 10{sup 17} Ga ions/cm{sup 2}. After implantation of 10{sup 18} Ga ions/cm{sup 2}, sub-grain features on the order of 2 {micro}m were observed which may be due to intermetallic compound formation between Ga and Zr. For the highest fluence implant, Ga content in the Zirc-4 reached a saturation value of between 30 and 40 atomic %; significant enhanced diffusion was observed but gallium was not seen to concentrate at grain boundaries.

Woods, A.L. [ed.; West, M.K. [Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

1999-01-01

128

Crystal Chemistry of Melanite Garnet  

NASA Technical Reports Server (NTRS)

This original project resulted in a detailed crystal chemical data map of a titanium rich garnet (melanite) suite that originates from the Crowsnest Volcanics of Alberta Canada. Garnet is typically present during the partial melting of the earth's mantle to produce basalt. Prior studies conducted at Youngstown State University have yielded questions as to the crystal structure of the melanite. In the Studies conducted at Youngstown State University, through the use of single crystal x-ray diffraction, the c-axis appears to be distorted creating a tetragonal crystal instead of the typical cubic crystal of garnets. The micro probe was used on the same suite of titanium rich garnets as used in the single crystal x-ray diffraction. The combination of the single crystal x-ray research and the detailed microprobe research will allow us to determine the exact crystal chemical structure of the melanite garnet. The crystal chemical data was gathered through the utilization of the SX100 Electron Probe Micro Analyzer. Determination of the exact chemical nature may prove useful in modeling the ultramafic source rock responsible for the formation of the titanium rich lunar basalts.

Nguyen, Dawn Marie

1999-01-01

129

GADOLINIUM SOLUBILITY AND VOLATILITY DURING DWPF PROCESSING  

SciTech Connect

Understanding of gadolinium behavior, as it relates to potential neutron poisoning applications at the DWPF, has increased over the past several years as process specific data have been generated. Of primary importance are phenomena related to gadolinium solubility and volatility, which introduce the potential for gadolinium to be separated from fissile materials during Chemical Process Cell (CPC) and Melter operations. Existing data indicate that gadolinium solubilities under moderately low pH conditions can vary over several orders of magnitude, depending on the quantities of other constituents that are present. With respect to sludge batching processes, the gadolinium solubility appears to be highly affected by iron. In cases where the mass ratio of Fe:Gd is 300 or more, the gadolinium solubility has been observed to be low, one milligram per liter or less. In contrast, when the ratio of Fe:Gd is 20 or less, the gadolinium solubility has been found to be relatively high, several thousands of milligrams per liter. For gadolinium to serve as an effective neutron poison in CPC operations, the solubility needs to be limited to approximately 100 mg/L. Unfortunately, the Fe:Gd ratio that corresponds to this solubility limit has not been identified. Existing data suggest gadolinium and plutonium are not volatile during melter operations. However, the data are subject to inherent uncertainties preventing definitive conclusions on this matter. In order to determine if gadolinium offers a practical means of poisoning waste in DWPF operations, generation of additional data is recommended. This includes: Gd solubility testing under conditions where the Fe:Gd ratio varies from 50 to 150; and Gd and Pu volatility studies tailored to quantifying high temperature partitioning. Additional tests focusing on crystal aging of Gd/Pu precipitates should be pursued if receipt of gadolinium-poisoned waste into the Tank Farm becomes routine.

Reboul, S

2008-01-30

130

Toxicity of Gadolinium to Some Aquatic Microbes  

Microsoft Academic Search

The toxicity of gadolinium to algae and bacteria was determined as part of an effort to develop a biological process to purify drums containing spent nuclear reactor heavy water moderator (D2O). This water was contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS) near

2001-01-01

131

New perspective in garnet phosphor: low temperature synthesis, nanostructures, and observation of multimodal luminescence.  

PubMed

Herein, we report a new concept for garnet materials in terms of the synthesis of nanocrystalline structure at low temperatures and its multimodal luminescence processes. Terbium- and ytterbium-ion-codoped yttrium gallium garnet nanophosphors have been synthesized via solution combustion technique; nearly pure phase nanophosphor samples were obtained. The synthesized nanophosphor shows efficient multimodal upconversion (UC), downshifting (DS), and quantum cutting (QC)/downconversion (DC) luminescence, which is a new paradigm in garnet material. The garnet nanophosphor shows strong green emission through DS and UC processes both. Furthermore, cooperative energy transfer (CET) has been described in detail, and a possible mechanism for the QC process is also proposed. A UV/blue photon absorbed by Tb(3+) ion splits into two near-infrared photons (wavelength range 900-1040 nm), emitted by a Yb(3+) ion pair, with an efficiency of more than 100%. The Yb(3+) concentration dependent ET from Tb(3+) to Yb(3+) has been verified using time domain analysis. An ET efficiency as high as 28% and a corresponding QC efficiency of about 128% (for 15 mol % of Yb(3+) concentration) have been attained. Such a multimode emitting nanophosphor could be very useful in display devices and for enhancing the conversion efficiency of next generation solar cells via spectral modification etc. PMID:25162917

Mishra, Kavita; Singh, Sunil Kumar; Singh, Akhilesh Kumar; Rai, Monika; Gupta, Bipin Kumar; Rai, Shyam Bahadur

2014-09-15

132

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

1996-01-01

133

Garnet Random-Access Memory  

NASA Technical Reports Server (NTRS)

Random-access memory (RAM) devices of proposed type exploit magneto-optical properties of magnetic garnets exhibiting perpendicular anisotropy. Magnetic writing and optical readout used. Provides nonvolatile storage and resists damage by ionizing radiation. Because of basic architecture and pinout requirements, most likely useful as small-capacity memory devices.

Katti, Romney R.

1995-01-01

134

Electrospun Gallium Nitride Nanofibers  

SciTech Connect

The high thermal conductivity and wide bandgap of gallium nitride (GaN) are desirable characteristics in optoelectronics and sensing applications. In comparison to thin films and powders, in the nanofiber morphology the sensitivity of GaN is expected to increase as the exposed area (proportional to the length) increases. In this work we present electrospinning as a novel technique in the fabrication of GaN nanofibers. Electrospinning, invented in the 1930s, is a simple, inexpensive, and rapid technique to produce microscopically long ultrafine fibers. GaN nanofibers are produced using gallium nitrate and dimethyl-acetamide as precursors. After electrospinning, thermal decomposition under an inert atmosphere is used to pyrolyze the polymer. To complete the preparation, the nanofibers are sintered in a tube furnace under a NH{sub 3} flow. Both scanning electron microscopy and profilometry show that the process produces continuous and uniform fibers with diameters ranging from 20 to a few hundred nanometers, and lengths of up to a few centimeters. X-ray diffraction (XRD) analysis shows the development of GaN nanofibers with hexagonal wurtzite structure. Future work includes additional characterization using transmission electron microscopy and XRD to understand the role of precursors and nitridation in nanofiber synthesis, and the use of single nanofibers for the construction of optical and gas sensing devices.

Melendez, Anamaris; Morales, Kristle; Ramos, Idalia [University of Puerto Rico at Humacao, Humacao (Puerto Rico); Campo, Eva [Centre Nacional de Microelectronica, Barcelona (Spain); Santiago, Jorge J. [University of Pennsylvania, Philadelphia (United States)

2009-04-19

135

Toxicity of Gadolinium to Some Aquatic Microbes  

SciTech Connect

The toxicity of gadolinium to algae and bacteria was determined as part of an effort to develop a biological process to purify drums containing spent nuclear reactor heavy water moderator (D2O). This water was contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS) near Aiken, SC. Nuclear reactors were operated for approximately 30 years at the SRS to produce nuclear weapons materials for national defense. Throughout this period, a heavy water solution of gadolinium nitrate was utilized in a standby emergency shutdown system that could inject this chemical into the reactor moderator coolant water. The chemical was used for this purpose because the high neutron absorption cross sections of some gadolinium isotopes make gadolinium salts such as GdNO3 effective in controlling nuclear activity in aqueous systems (Gilbert et al. 1985; Rodenas et al. 1990). The use of this practice resulted in a large inventory of this degraded heavy water containing gadolinium nitrate. Microbiological and chemical studies were initiated to evaluate the potential use of bacteria and algae for water purification of the drums. Since metals are often toxic to microbes when present at concentrations substantially higher than natural environmental levels, it was hypothesized that Gd may be toxic to selected microorganisms (algae and bacteria) at the very high concentrations (average 80,000 mg/L, maximum 259,000 mg/L) present in most of the drums. Two principal components of the study included: (1) chemical and microbiological characterization of representative drums, and (2) an evaluation of the toxicity of gadolinium to selected species of algae. In addition to wastewater from nuclear production reactor operations, gadolinium waste is also generated from medical applications, especially MRI, and various electronic components including CD disks. Despite growing and widespread usage of this rare element, there is a paucity of information on the toxicity of gadolinium.

Wilde, E.W.

2001-01-24

136

Status of gadolinium enrichment technology at LLNL  

SciTech Connect

A method based on,polarization selectivity and three step laser photoionization is presented for separation of the odd isotopes of gadolinium. Measurements of the spectroscopic parameters needed to quantify the excitation pathway are discussed. Model results are presented for the efficiency of photoionization. The vapor properties of electron beam vaporized gadolinium are presented which show dramatic cooling during the expansion of the hot dense vapor into a vacuum. This results in a significant increase in the efficiency of conversion of natural feed into enriched product in the AVLIS process. Production of enriched gadolinium for use in commercial power reactors appears to be economically viable using technology in use at LLNL.

Haynam, C.; Comaskey, B.; Conway, J.; Eggert, J.; Glaser, J.; Ng, E.; Paisner, J.; Solarz, R.; Worden, E.

1993-01-01

137

Chemical characterization of garnets from Garnet Ridge, northern Arizona in the Colorado Plateau  

NASA Astrophysics Data System (ADS)

Garnet crystals with diverse chemistries and their origins have occurred at Garnet Ridge in northern Arizona, Colorado Plateau. The garnet grains occur as small grains (2-5mm ?) scattering on weathered late Jurassic red mudstone, very large grained single crystal (1 to several cm), and major constituent minerals of eclogite and other garnet-bearing xenoliths in kimberlitic diatreme. The important discovery of coesite-bearing lawsonite eclogite, which is one of the source rocks of garnets, has been reported by Usui et al. (2005), and their zircon ages (81 to 33 Ma) suggest that the lawsonite eclogite was a product of subduction of the Fallaron plate underneath the Colorado Plateau. We collected several kinds of garnet grains with various origins and of xenoliths, and clarified the chemical characteristics of these garnets with an electron microprobe (JXA-8900 WDS mode). The garnet samples were classified into 6 groups: (A) scattered grains of reddish to purplish garnet (2-5 mm ?), (B) large-grained reddish brown garnet, (C) garnet in an eclogite xenolith. (D) garnet in unknown xenolith A, (E) garnet in unknown xenolith B, (F) garnet in garnet-clinopyroxene rock xenolith (strongly altered). The results of microprobe analyses showed the large difference in each garnet type on Prp-Alm-Grs triangular diagram. The garnet chemistries were as follows: (1) Type A garnets were relatively Prp-rich but have a wide range in Prp component. The Cr2O3 contents (max. 4 wt.%) divided this type into two groups. (2) Type-B garnets were plotted near the center of the triangle and did not show clear chemical zonation. (3) Type-C garnets have Alm-rich composition and were low in Prp. They show chemical zonation of Pyr and Grs components (MgO:1.4 to 5.4 wt.%, and CaO: 14.0 to 5.6 wt.% both from core to rim). Clinopyroxene is omphacite. (4) Type D garnets were plotted on Alm-Grs join (Grs61-71Alm23-35And5-7). (5) Type E garnets are characterized by very low Grs-components and were plotted on Alm-rich composition near Alm-Prp join. (6) Type-F garnets were plotted on Alm-rich area. Prp contents were variable; 4.8 to 9.5 wt.% in MgO from core to rim. The core of Type-F was plotted near the rim of Type-C garnet. The chemical compositions of garnets from Garnet Ridge gave us the information about the different conditions of garnet formation and their host rocks. The garnet chemistry at Garnet Ridge suggests the diverse features of subducted oceanic crusts, mantle peridotites and various metasomatic rocks underneath the Colorado Plateau. We reported the microprobe data on Na2O compositions of Type-C garnet as Na2O: 0.5-0.7 wt.% at AOGS2011 Meeting (Koga and Ogasawara, 2011). After the analyses with JEOL-8900 (WDS mode), however, the previous Na2O contents were within errors because of the low precision by EDS mode. Acknowledgements: The authors are grateful to Mrs. Pauline Deswudt for her kind permission for us to collect garnet and rocks near Garnet Ridge. Also, we purchased several rocks and garnet grains from her for the present study.

Itaru, K.; Ogasawara, Y.

2011-12-01

138

Oriented growth of garnet by topotactic reactions and epitaxy in high-pressure, mafic garnet granulite formed by dehydration  

E-print Network

Oriented growth of garnet by topotactic reactions and epitaxy in high-pressure, mafic garnet, Shakarparian, 44000 Islamabad, Pakistan ABSTRACT Garnet growth in high-pressure, mafic garnet granulites formed samples preserve a sharp transition in which the low-pressure precursor is replaced by garnet through

Tommasi, Andrea

139

Nuclear data for gadolinium production  

SciTech Connect

There has been a marked increase in requests for neutron cross-section data of the rare-earth isotopes, /sup 152/Gd, /sup 153/Gd, /sup 151/Eu, /sup 152/Eu, /sup 153/Eu, /sup 154/Eu, and /sup 155/Eu because of the use of natural europium-oxide in reactor production of /sup 153/Gd. This gadolinium isotope is needed because of its use as the working ingredient in an advanced medical scanning machine that can detect loss of bone minerals such as calcium, a possible cause of the disease osteoporosis. Hanford's Fast Flux Test Facility plans to begin production of several /sup 153/Gd specimens during this autumn's operating cycle. An analysis of various experiments led to recommended values for the cross sections and resonance integrals, which are displayed and compared with the ENDF/B-V values. The detailed data underlying these recommendations are presented.

Holden, N.E.

1986-01-01

140

Gallium Safety in the Laboratory  

SciTech Connect

A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

Lee C. Cadwallader

2003-06-01

141

Gallium Safety in the Laboratory  

SciTech Connect

A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

Cadwallader, L.C.

2003-05-07

142

Experimental tests of garnet peridotite oxygen barometry  

Microsoft Academic Search

We have performed experiments aimed at testing the calibration of oxygen barometers for the garnet peridotite [garnet (Gt)-olivine\\u000a (Ol)-orthopyroxene (Opx)] phase assemblage. These involved equilibrating a thin layer of garnet sandwiched between layers\\u000a of olivine and orthopyroxene at 1300C and 23–35 kbar for 1–7 days. Oxygen fugacity was controlled (but not buffered) by using\\u000a inner capsules of Fe?Pt alloy or

G. Gudmundsson; B. J. Wood

1995-01-01

143

Garnets recording deep crustal earthquakes  

Microsoft Academic Search

Syn-eclogite facies pseudotachylytes of the Bergen Arcs, western Norway, were formed during co-seismic faulting at a depth of 60 km during Caledonian continent collision, concurrent with fluid-induced partial eclogitization of Precambrian anorthositic granulites. The pseudotachylytes contain the high-pressure assemblage omphacite, garnet and kyanite and formed in the metastable granulites at the border of eclogitized areas. Rock volumes corresponding to outcrops

Håkon Austrheim; Muriel Erambert; Theresa M. Boundy

1996-01-01

144

Magnetic and electronic properties of nanocrystalline Gd{sub 3}Fe{sub 5}O{sub 12} garnet  

SciTech Connect

The Gd{sub 3}Fe{sub 5}O{sub 12} nanocrystalline Gadolinium Iron Garnet (GdIG) obtained from a sintered block was milled in a high energy ball mill. We measured the magnetization at 5 K under applied fields up to 12 T. We report here our study of approach to saturation magnetization. The results have been interpreted within the framework of random anisotropy model. From an analysis of the approach to saturation magnetization some fundamental parameters have been extracted. We have determined the anisotropy field H{sub r} and the local magnetic anisotropy constant K{sub L}. In addition, first-principles spin-density functional calculations, using the Full potential Linear Augmented Plane Waves (FLAPW) method are performed to investigate electronic and magnetic structures. All computed parameters are discussed and compared to available experimental data. - Graphical abstract: Random anisotropy fields, random anisotropy constant, substantial interstitial magnetism as well as magnetic quadrupolar feature on oxygen are determined from magnetization, theoretical random magnetic anisotropy model and FLAPW calculations in nanocrystalline Gadolinium Iron Garnet (GdIG). Highlights: Black-Right-Pointing-Pointer Nanocrystalline Gadolinium Iron Garnet (GdIG) prepared by a high energy ball mill. Black-Right-Pointing-Pointer Random magnetic anisotropy model developed for amorphous is used for Nanocrystalline GdIG. Black-Right-Pointing-Pointer Random anisotropy fields and random anisotropy constant are determined. Black-Right-Pointing-Pointer FLAPW calculations performed to investigate both magnetic and electronic structures. Black-Right-Pointing-Pointer Substantial interstitial magnetism and magnetic quadrupolar feature on oxygen are revealed.

Lassri, H. [LPMMAT, Universite Hassan II-Ain Chock, Faculte des Sciences, B.P. 5366, Maarif, Casablanca (Morocco); Hlil, E.K., E-mail: hlil@grenoble.cnrs.fr [Institut Neel, CNRS et Universite Joseph Fourier, BP 166, F-38042, Grenoble cedex 9 (France); Prasad, S. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Krishnan, R. [Groupe d'etude de la Matiere Condensee, CNRS/Universite de Versailles-St-Quentin, 45, avenue des Etats-Unis, 78035 Versailles Cedex (France)

2011-12-15

145

Limit on the electron electric dipole moment in gadolinium-iron garnet.  

PubMed

A new method for the detection of the electron electric dipole moment (EDM) using a solid is described. The method involves the measurement of a voltage induced across the solid by the alignment of the sample's magnetic dipoles in an applied magnetic field, H. A first application of the method to GdIG has resulted in a limit on the electron EDM of 5 x 10(-24)e cm, which is a factor of 40 below the limit obtained from the only previous solid-state EDM experiment. The result is limited by the imperfect discrimination of an unexpectedly large voltage that is even upon the reversal of the sample magnetization. PMID:16384457

Heidenreich, B J; Elliott, O T; Charney, N D; Virgien, K A; Bridges, A W; McKeon, M A; Peck, S K; Krause, D; Gordon, J E; Hunter, L R; Lamoreaux, S K

2005-12-16

146

Limit on the Electron Electric Dipole Moment in Gadolinium-Iron Garnet  

Microsoft Academic Search

A new method for the detection of the electron electric dipole moment (EDM) using a solid is described. The method involves the measurement of a voltage induced across the solid by the alignment of the sample's magnetic dipoles in an applied magnetic field, H. A first application of the method to GdIG has resulted in a limit on the electron

B. J. Heidenreich; O. T. Elliott; N. D. Charney; K. A. Virgien; A. W. Bridges; M. A. McKeon; S. K. Peck; D. Krause Jr.; J. E. Gordon; L. R. Hunter; S. K. Lamoreaux

2005-01-01

147

Limit on the Electron Electric Dipole Moment in Gadolinium-Iron Garnet  

SciTech Connect

A new method for the detection of the electron electric dipole moment (EDM) using a solid is described. The method involves the measurement of a voltage induced across the solid by the alignment of the sample's magnetic dipoles in an applied magnetic field, H. A first application of the method to GdIG has resulted in a limit on the electron EDM of 5x10{sup -24}e cm, which is a factor of 40 below the limit obtained from the only previous solid-state EDM experiment. The result is limited by the imperfect discrimination of an unexpectedly large voltage that is even upon the reversal of the sample magnetization.

Heidenreich, B.J.; Elliott, O.T.; Charney, N.D.; Virgien, K.A.; Bridges, A.W.; McKeon, M.A.; Peck, S.K.; Krause, D. Jr.; Gordon, J.E.; Hunter, L.R.; Lamoreaux, S.K. [Physics Department, Amherst College, Amherst, Massachusetts 01002 (United States); Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2005-12-16

148

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

1995-01-01

149

Natural weathering mechanisms of almandine garnet  

NASA Astrophysics Data System (ADS)

The weathering of almandine garnet in the oxidized, vadose zone of saprolite near Otto, North Carolina, begins at grain boundaries and along fractures traversing the garnet grains. Radially oriented fibrous intergrowths of gibbsite and goethite form layers of uniform thickness, which grow by centripetal replacement as weathering proceeds. The contact between the garnet surface and the layer of weathering products is sharp and smooth, and garnet corners are rounded. Large, well-defined etch pits are absent on the underlying garnet surface. These observations suggest that diffusion (transport) of reactants and/or products through the gibbsite-goethite layer is the rate-limiting step in the weathering of almandine garnet in the oxidizing environment of the saprolite. In soils overlying the saprolite, garnet surfaces are directly exposed to weathering solutions without the intervening surface layer. Such “unprotected” grains in soils (and stream sediments) exhibit numerous large, well-developed etch pits. Surface-reaction control, rather than transport control, prevails during weathering of almandine garnet in the absence of protective surface layers of weathering products. Biochemical or biological processes in the soil apparently prevent the gibbsite-goethite layer from forming or persisting. Soil solutions can therefore react directly with the garnet surface, rather than requiring reactants or products to diffuse through the gibbsite-goethite coating as in the saprolite. The mechanism, and rate-limiting step, of almandine garnet weathering is apparently strongly dependent on the chemical environment in which weathering occurs. *Present address: Department of Geological Sciences, Michigan State University, East Lansing, Michigan 48824-1115

Velbel, Michael Anthony

1984-10-01

150

Chemical properties of Garnets from Garnet Ridge, Navajo volcanic field in the Colorado Plateau  

NASA Astrophysics Data System (ADS)

Significant amounts of garnet crystals have derived from kimberlitic diatremes at Garnet Ridge in northern Arizona. These garnets are chemically diverse and their origins have been still controversial. The diatremes at Garnet Ridge were dated at 30Ma (Smith et al., 2004). Coesite-bearing lawsonite eclogite reported by Usui et al., (2003) is important evidence for subduction of the Fallaron Plate below the Colorado plateau. This study characterized various kinds of garnets with several origins by petrographical observations and electron microprobe analyses (JXA-8900 WDS mode and JXA-733 EDS mode). On the basis of the chemical compositions and other features, the garnets were classified into the following 8 groups (A to H). Inclusions and exsolved phases were identified by laser Raman spectroscopy. (A) Garnet crystals (5-8 mm) with purple color are called ''Navajo Ruby''. A significant amount of Cr2O3 is a typical feature (up to ~5.9 wt. %). These garnet were rich in pyrope (66-78 mol. %). Olivine, Cpx, and exsolved lamellae of rutile were contained. (B) Reddish brown garnets were Pyp-rich (60-75 mol. %), and contained a minor amount of Cr2O3 (less than ~1 wt. %). The inclusions were rod-shaped rutile , Cpx, Opx, zircon, olivine and exsolved lamellae of apatite. (C) Garnet megacrysts (8-12 cm) were plotted near the center of Prp-Alm-Grs triangle (Pyp30-35 Alm28-33 Grs29-35). Exsolved apatite lamellae were confirmed. (D) Some of reddish brown garnets were plotted on same area as the Type-C. (E) Garnets in eclogite have Alm-rich composition (Pyp6-22 Alm52-65 Grs16-42). They clearly showed prograde chemical zonation; MgO: 1.4 to 5.4 wt. %, CaO: 14.0 to 5.6 wt. % both from core to rim. (F) Garnets in altered or metasomatized eclogite had a wide range of chemical composition (Pyp7-38 Alm52-69 Grs4-31) with similar prograde zonation. The cores were plotted near the rim of Type-E garnet. (G) Garnets in unidentified rock (strongly altered) had Alm-rich composition near Alm-Prp join. Euhedral quartz and zircon were included in the garnet. (H) Garnets in skarn-like rock of metasomatism origin at crustal level were plotted on Alm-Grs join and have no Prp component. Titanite, zoisite and fluid inclusion were identified in this garnet. Among the garnets described above, one of the typical garnets from Garnet Ridge is Cr-bearing Pyp-rich garnet, "Navajo Ruby", of peridotite origin at great depths, and another typical one is garnet in eclogite probably of subducted Farallon Plate origin. These two rocks having strong contrast each other were mixed underneath the Colorado Plateau. The chemical characteristics and petrographical features of the garnets from Garnet Ridge will give us very important information on complex petrochemical processes and related environments underneath the Colorado Plateau. Acknowledgements: The authors are grateful to Mrs. Pauline Deswudt who sold us various kinds of garnet grains and their host rocks for the present study. References: D. Smith, James N. Connelly, Kathryn Manser, Desmond E. Moser, Todd B. Housh, Fred W. McDowell, and Lawrence E. Mack., Vol. 5, Number 4. (2004) Geochemistry Geophysics Geosystems Usui, T., Nakamura, E., Kobayashi, K., Maruyama, S. and Helmstaedt, H. (2003) Geology, 31.

Koga, I.; Ogasawara, Y.

2012-12-01

151

DTECTION DE PHOTONEUTRONS AVEC UN SCINTILLATEUR LIQUIDE CHARG AU GADOLINIUM  

E-print Network

249. DÉTECTION DE PHOTONEUTRONS AVEC UN SCINTILLATEUR LIQUIDE CHARGÉ AU GADOLINIUM H. BEIL, R scintillateur liquide chargé au gadolinium (0,5 % en poids) et employé récemment à Saclay comme détecteur de par porte de 25 03BCs. Abstract. - The essential characteristics of a large, gadolinium loaded (0

Paris-Sud XI, Université de

152

Pyroxene solid solution in garnets included in diamond  

Microsoft Academic Search

Garnets included in diamonds from the Monastery Mine kimberlite pipe in South Africa which have a unique range of compositions are described. These garnets are interpreted as representing the first natural occurrence of garnet hosting a component of pyroxene in solid solution. Their discovery fulfills predictions based on successful laboratory experiments in which pyroxene was dissolved in garnet at very

R. O. Moore; John J. Gurney

1985-01-01

153

Renal amyloidosis. Evaluation by gallium imaging  

SciTech Connect

A study has been performed to evaluate the efficacy of gallium imaging in the detection of renal amyloidosis. Ten of the 11 patients who had biopsy-proven renal amyloidosis demonstrated marked uptake in both kidneys. One patient revealed moderate gallium uptake in his kidneys. None of the patients had underlying renal or extrarenal pathology other than amyloidosis, which could account for renal gallium uptake (renal infection, neoplasm, hepatic failure or frequent blood transfusions). Four patients also had extrarenal foci of abnormal gallium uptake, suggesting other sites of amyloid deposits. Our data strongly suggest that gallium imaging has a high sensitivity for detection of renal amyloidosis. Its specificity is enhanced significantly by careful review of the clinical history to exclude other known causes of renal gallium uptake. Potentially, gallium imaging may be used to monitor the progress of patients under experimental therapy.

Lee, V.W.; Skinner, M.; Cohen, A.S.; Ngai, S.; Peng, T.T.

1986-09-01

154

Gitterpositionsbestimmung von Fremdatomen in Granaten mit Hilfe des Channeling  

NASA Astrophysics Data System (ADS)

Mit Hilfe der Gitterführung geladener Teilchen wurden die Gitterpositionen von Magnesium und Zirkon (oktaedrische Plätze) in Gadolinium Gallium Granat (GGG) und von Wismut und Blei (dodekaedrische Plätze) in Bi-substituiertem Yttrium Eisen Granat (YIG) bestimmt. Zum Vergleich wurde das Channelingverhalten von Protonen in undotiertem GGG untersucht.Translated AbstractForeign Atom Location in Garnets Using the Channeling TechniqueUsing the particle channeling technique the lattice sites of Magnesium and Zircon (octahedral sites) in Gadolinium Gallium Garnet (GGG) and the lattice sites of Bismuth and Lead (dodecahedral sites) in Bi-substituted Yttrium Iron Garnet (YIG) were determined. In comparison the channeling behavior of protons in undoped GGG has been investigated.

Timm, A.; Zimmermann, W.

155

Experimental search for the electron Electric Dipole Moment using solid state techniques  

Microsoft Academic Search

We report results of an experimental search for the permanent Electric Dipole Moment (EDM) of the electron using a solid state system. The experiment uses a paramagnetic insulator (gadolinium gallium garnet) with a large magnetic response at low temperatures. The presence of the electron EDM leads to a finite magnetization when the garnet sample is subjected to a strong electric

Y. J. Kim; C.-Y. Liu; S. K. Lamoreaux; G. Reddy

2011-01-01

156

One-dimensional bigyrotropic magnetic photonic crystals  

Microsoft Academic Search

Electromagnetic wave propagation in a one-dimensional magnetic photonic crystal (MPC) made of bigyrotropic magnetic yttrium-iron garnet and nonmagnetic gadolinium-gallium garnet is theoretically investigated using the 4×4 transfer matrix method. Band gaps in the electromagnetic spectrum are numerically obtained and appear to depend on the helicity and direction of light propagation through the MPC.

I. L. Lyubchanskii; N. N. Dadoenkova; M. I. Lyubchanskii; E. A. Shapovalov; A. Lakhtakia; T. H. M. Rasing

2004-01-01

157

Raman spectroscopy of garnet-group minerals  

USGS Publications Warehouse

The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site. The stretch and rotatory Alg modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series, owing to the cations residing in the X site connected with SiO4 tetrahedra by sharing the two edges. The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series. ?? 1994 Institute of Geochemistry, Chinese Academy of Sciences.

Mingsheng, P.; Mao, H.-K.; Dien, L.; Chao, E.C.T.

1994-01-01

158

Three-dimensional patterns of garnet nucleation and growth  

Microsoft Academic Search

Three-dimensional compositional zoning patterns in garnet-zone garnets from Harpswell Neck, Maine, United States, suggest complex patterns of nucleation and growth. Compositional zoning is often asymmetric, and core compositions do not always coincide with the geometric center of the garnet. In detail, garnet zoning patterns show multiple, isolated, high-MnO areas that we interpret as sites of garnet nucleation. If it is

Christopher G. Daniel; Frank S. Spear

1998-01-01

159

Clash of garnets - Mechanical interaction of porphyroblasts  

NASA Astrophysics Data System (ADS)

The presence of porphyroblasts in metamorphic rocks has a strong influence on the microstructures that develop during deformation. Valuable as gauges for the sense of shear, single isolated porphyroblasts and -clasts have attracted enormous attention and vigorous discussion in the geological community. However, nature does not always provide samples fulfilling this criterion, therefore the understanding of multi-porphyroblast interaction is of great significance. We use amphibolite-facies garnet mica schists from the Upper Austroalpine Wölz Complex for a case study. The microstructure of mm-cm sized, densely distributed garnet porphyroblasts indicates interference of the blasts. Microstructural and chemical investigation have been performed using optical and electron microscopy as well as an electron microprobe. The observed finite deformation is compatible with general shear. Blasts are subjected to convergence parallel to the instantaneous shortening axis, causing (i) accumulation and deformation of strain caps, (ii) fracturing of the garnets and (iii) dissolution at garnet-garnet interfaces. Parallel to the instantaneous stretching axis, (i) wedge-shaped strain shadows are linked between neighbouring garnets and (ii) separation of garnet clusters occurs preferably. Despite the existence of a non-coaxial strain component, strain shadows do not develop a monoclinic symmetry, owing to the interference of adjacent blasts. The proximity of garnets determines (i) the formation of microstructures dependant on the direction of the instantaneous stretching axes, as well as (ii) the disturbance of these fabrics. Thus, dense populations of stronger objects in a weaker deforming matrix cause complex heterogeneous strain patterns, which demand a thorough investigation of the deformation history of a rock. Finally, when they are close enough, garnets interact and deform, and thus cannot be considered as rigid.

Bender, Hagen; Huet, Benjamin; Grasemann, Bernhard; Schuster, Ralf

2014-05-01

160

P-type gallium nitride  

DOEpatents

Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

1997-08-12

161

Gallium scintigraphy in acute panniculitis  

SciTech Connect

Gallium scintigraphy was performed in a 27-yr-old female in search of a possible occult focus of infection; it showed an unusual diffuse superficial accumulation in the thighs and buttocks. Biopsy of an area of abnormal uptake showed lobular panniculitis which, in the clinical context, led to the diagnosis of Weber-Christian syndrome.

Choy, D. (Prince of Wales Hospital, Randwick, Australia); Murray, I.P.C.; Ford, J.C.

1981-11-01

162

P-type gallium nitride  

DOEpatents

Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5.times.10.sup.11 /cm.sup.3 and hole mobilities of about 500 cm.sup.2 /V-sec, measured at 250.degree. K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al.

Rubin, Michael (Berkeley, CA); Newman, Nathan (Montara, CA); Fu, Tracy (Berkeley, CA); Ross, Jennifer (Pleasanton, CA); Chan, James (Berkeley, CA)

1997-01-01

163

Gallium nitride electronics  

NASA Astrophysics Data System (ADS)

In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it an excellent reference for newcomers and experienced researchers in this field for several years. We thank Alice Malhador at IOP Publishing for her constant encouragement and guidance in putting together this special issue on GaN electronics.

Rajan, Siddharth; Jena, Debdeep

2013-07-01

164

Spectroscopic analysis of proton induced fluorescence from cerium doped yttrium aluminum garnet  

NASA Astrophysics Data System (ADS)

We have determined the effect of proton induced damage on relative scintillation efficiency for yttrium aluminum garnet doped with cerium (YAG:Ce). The YAG:Ce phosphor samples were exposed to a 3 MeV proton beam, and substrate temperature was limited to control heating damage. Real time in situ measurements of the fluorescence spectra permitted observation of the spectral characteristics of scintillator deterioration due to particle induced damage. Fluorescence from YAG:Ce is relatively dim when compared to other rare earth oxysulfide compounds and the light intensity drops rapidly with dose. Spectra from proton irradiated YAG:Ce exhibit a broad fluorescence peak that is much wider than is typical in other yttrium and gadolinium phosphor compounds. The physical processes in YAG:Ce are very different from other bright-line phosphors as shown by the large difference in the observed fluorescence peak width. Light intensity decreases with dose, following the Birks and Black empirical model.

Fisher, J. H.; Hollerman, W. A.; Shelby, G. A.; Holland, L. R.; Jenkins, G. M.

1993-06-01

165

Evaluation of garnet discrimination diagrams using geochemical data of garnets derived from various host rocks  

NASA Astrophysics Data System (ADS)

This work is an attempt to evaluate six different garnet discrimination diagrams (one binary diagram and five ternary diagrams) commonly used by many researchers. The mineral chemistry of detrital garnet is a useful tool in sedimentary provenance studies, yet there is no clear-cut understanding of what garnet type originates from which host lithology. Several discrimination diagrams exist for garnet showing distinct compositional fields, separated by strict boundaries that are thought to reflect specific types of source rocks. For this study, a large dataset was compiled (N = 3532) encompassing major element compositions of garnets derived from various host lithologies, including metamorphic, igneous, and mantle-derived rocks, in order to test the applicability of the various discrimination schemes. The dataset contains mineral chemical data collected from the literature complemented with some new data (N = 530) from garnet-bearing metamorphic and ultramafic rocks in Austria and Norway. Discrimination of the tested diagrams only works for a small group of garnets derived from mantle rocks, granulite-facies metasedimentary rocks, and felsic igneous rocks. For other garnet types, the assignment to a certain type of host rock remains ambiguous. This is considered insufficient and therefore the evaluated diagrams should be used with great care. We further apply compositional biplot analysis to derive some hints towards future perspectives in detrital garnet discrimination.

Krippner, Anne; Meinhold, Guido; Morton, Andrew C.; von Eynatten, Hilmar

2014-06-01

166

Dielectronic recombination of Pd-like gadolinium  

NASA Astrophysics Data System (ADS)

As research and development of extreme ultraviolet lithography (EUVL) sources at 6.7 nm (which will be based on emission from ionized gadolinium) has already begun, reliable atomic data are required in order to determine the optimum plasma conditions. However, the complexity of the atomic structure means that ab initio level-resolved dielectronic recombination (DR) calculations are currently unavailable for the ions of interest. Here we report the first detailed calculation of the DR rate coefficients for the ground state and first excited states of Pd-like gadolinium. Energy levels, radiative transition probabilities, and autoionization rates of Ag-like gadolinium for [Kr]4d94fnl, [Kr]4p54d104fnl, [Kr]4d95l'nl, and [Kr]4d96l'nl (n ? 18) complexes were calculated using the flexible atomic code (FAC). It was found that inclusion of 4p54d104fnl configurations has significant influence on the total DR rate coefficient. The DR rate coefficients obtained here are compared with radiative recombination and three-body recombination coeffcients. The results show that the DR rate coefficient is almost an order of magnitude higher than the coefficients for the other two recombination processes combined at plasma electron temperatures around 110 eV, which suggests that the DR process should be included in theoretical modeling for Pd-like gadolinium in EUVL source plasmas.

Li, B. W.; O'Sullivan, G.; Fu, Y. B.; Dong, C. Z.

2012-01-01

167

A toxicological study of gadolinium nitrate  

SciTech Connect

The sensitization study in the guinea pig did not show gadolinium nitrate to have potential sensitizing properties. Skin application studies in the rabbit demonstrated that it was cutaneously a severe irritant. This material was considered an irritant in the rabbit eye application studies. 3 refs., 1 tab.

London, J.E.

1988-05-01

168

Gadolinium: Central Metal of the Lanthanoids  

ERIC Educational Resources Information Center

The physical and chemical properties of gadolinium are compared with those of the other lanthanoids. Some properties are intermediate between those of lanthanum and lutetium; some between those of barium and hafnium; and others (unexpectedly) between those of ytterbium and lutetium. Both the remarkably high molar heat capacity of the metal and the…

Laing, Michael

2009-01-01

169

Rare Earth Garnet Selective Emitter  

NASA Technical Reports Server (NTRS)

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional impurities, in the development of solid state laser crystals. Doping, dependent on the particular ion and crystal structure, may be as high as 100 at. % (complete substitution of yttrium ion with the rare earth ion). These materials have high melting points, 1940 C for YAG (Yttrium Aluminum Garnet), and low emissivity in the near infrared making them excellent candidates for a thin film selective emitter. As previously stated, the spectral emittance of a rare earth emitter is characterized by one or more well defined emission bands. Outside the emission band the emittance(absorptance) is much lower. Therefore, it is expected that emission outside the band for a thin film selective emitter will be dominated by the emitter substrate. For an efficient emitter (power in the emission band/total emitted power) the substrate must have low emittance, epsilon(sub S). This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium(Ho) and erbium (Er) doped YAG thin film selective emitters at (1500 K), and compares those results with the theoretical spectral emittance.

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

170

40 CFR 721.10391 - Copper gallium indium selenide.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Copper gallium indium selenide. 721.10391 Section 721...Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance...substance identified as copper gallium indium selenide (PMN P-10-424; CAS...

2012-07-01

171

40 CFR 721.10391 - Copper gallium indium selenide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Copper gallium indium selenide. 721.10391 Section 721...Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance...substance identified as copper gallium indium selenide (PMN P-10-424; CAS...

2013-07-01

172

40 CFR 721.10391 - Copper gallium indium selenide.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Copper gallium indium selenide. 721.10391 Section 721...Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance...substance identified as copper gallium indium selenide (PMN P-10-424; CAS...

2014-07-01

173

Ferric iron in mantle-derived garnets  

Microsoft Academic Search

The oxidation state of a mantle assemblage may be defined by heterogeneous reactions between oxygen and iron-bearing minerals. In spinel lherzolites, the presence of Fe3+ in spinel allows use of the assemblage olivine-orthopyroxene-spinel to define fO2 at fixed T and P. As a first step towards establishing an analogous reaction for garnet lherzolites, garnets from mantle-derived xenoliths from South Africa

Robert W. Luth; David Virgo; Francis R. Boyd; Bernard J. Wood

1990-01-01

174

Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system  

E-print Network

Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system Kangkang, University of Michigan, Ann Arbor, MI 48109, U.S.A. ABSTRACT Ferromagnetic delta-phase manganese gallium to their potential for novel spintronics applications such as spin light-emitting diodes[1] . Delta phase manganese

175

Water contents of garnets from the Garnet Ridge, northern Arizona: H2O behavior underneath the Colorado Plateau  

NASA Astrophysics Data System (ADS)

Kimberlitic volcanism at the Garnet Ridge delivered a wide variety of garnets and garnet-associated rocks in large vertical range from the deep mantle to shallow depths underneath the Colorado Plateau (Smith et al., 2004). Koga and Ogasawara (2012) classified the garnets at the Garnet Ridge into the following nine groups; (a) Cr and pyrope-rich garnet, (b) pyrope-rich reddish brown garnet, (c) reddish brown garnet, (d) garnet in eclogite, (e) garnet in metasomatized eclogite, (f) garnet aggregate, (g) garnet megacryst, (h) garnet in metasomatic rock I, (i) garnet in metasomatic rock II. They regarded these garnets as the four origins: mantle peridotite (a, b), subducted oceanic crust (d, e), high-pressure metasomatism (c, f, g), low-pressure metasomatism (h, i). On the garnets (a, b, d), Sakamaki et al. (2012) preliminary reported OH qualitatively using micro FT-IR spectroscopy. In garnets (a, b), OH was detected clearly, but in garnet (d) OH was below detection limit because the thickness of a doubly polished section of garnet (d) was too small (thickness: ~70 ?m) and the concentration was too low. Using micro FT-IR method, this study conducted the quantitative analysis of H2O for 20 grains of group (a), 18 grains of group (b) and 6 grains of group (d). The garnet samples were prepared as doubly polished thick sections (thicknesses of 0.1-1.3 mm). An IR absorption coefficient of 8770 L/mol/cm2 (Katayama et al., 2005) for garnets was used. Significant amounts of hydroxyl were detected in garnets (a, b, d); clear OH bands were identified in garnets (a, b), but very week and extremely broad OH bands in garnet (d). In the analyzed garnets, no zonal distribution of OH was identified. Garnet (a): the IR spectra have a main OH band at 3575 cm-1 and often with a week band at 3675 cm-1. The resultant H2O contents range from the below detection limit to 119 ppm wt. and are distributed at 0~10 and at ca. 100 ppm wt., bimodally. Garnet (b): the IR spectra have a main OH band at 3575 cm-1, similar to the main OH band of garnet (a), and sometimes with a week band at 3661 cm-1. The obtained H2O contents are 5-177 ppm wt. and are distributed at 30 and at 70 ppm wt., biomdally. Garnet (d): The IR spectra have a main OH band at 3550 cm-1 and often with a week band at 3650 cm-1. H2O contents are 25-58 ppm wt. H2O concentrations in garnet could be controlled mainly by (1) coexisting phases, (2) bulk water amounts in a host rock and (3) P conditions. The peridotitic garnet contains higher amounts of OH than the eclogitic garnet although the bulk water amounts in mantle peridotite are much lower than in hydrated subducting slab. This may have been caused both by the difference in coexisting phases and P condition. The origins of water could be (1) dehydration of subducted slab for garnet (d) and (2) hydrated mantle peridotites at much deeper level for garnets (a, b). Water in the garnets from the Garnet Ridge is the key to clarify the water behavior from shallow level to the deep mantle underneath the Colorado Plateau.

Ogasawara, Y.; Sakamaki, K.; Sato, Y.

2013-12-01

176

Intercomparison of garnet barometers and implications for garnet mixing models  

SciTech Connect

Several well-calibrated barometers are available in the system Ca-Fe-Ti-Al-Si-O, including: Alm+3Ru-3Ilm+Sil+2Qtz (GRAIL), 2Alm+Grreverse arrow6Ru=6Ilm+3An+3Qtz (GRIPS); 2Alm+Gr=3Fa+3An (FAG); 3AnGr+Ky+Qtz (GASP); 2Fs-Fa+Qtz (FFQ); and Gr+Qtz=An+2Wo (WAGS). GRIPS, GRAIL and GASP form a linearly dependent set such that any two should yield the third given an a/X model for the grossular/almandine solid-solution. Application to barometry of garnet granulite assemblages from the Grenville in Ontario yields average pressures 0.1 kb lower for GRIPS and 0.4 kb higher for FAGS using our mixing model. Results from Parry Island, Ontario, yield 8.7 kb from GRAIL as opposed to 9.1 kb using Ganguly and Saxena's model. For GASP, Parry Island assemblages yield 8.4 kb with the authors calibration. Ganguly and Saxena's model gives 5.4 kb using Gasparik's reversals and 8.1 kb using the position of GASP calculated from GRIPS and GRAIL. These corrections allow GRIPS, GRAIL, GASP and FAGS to yield consistent pressures to +/- 0.5 kb in regional metamorphic terranes. Application of their mixing model outside of the fitted range 700-1000 K is not encouraged as extrapolation may yield erroneous results.

Anovitz, L.M.; Essene, E.J.

1985-01-01

177

Photoconductivity of Yttrium Neodymium Gadolinium Oxalate Crystals  

NASA Astrophysics Data System (ADS)

Crystals are pillars of modern technology..Yttrium Neodymium Gadolinium oxalate (YNdGaOx) crystals were grown by gel method by the diffusion of Yttrium Chloride, Neodymium Chloride, and Gadolinium Chloride into the set gel containing Oxalic acid. Silica gel method is capable of yielding crystals of high optical perfection and wide morphology. The growing crystals are held in the gel medium in a strain free manner and at the same time nucleation and super saturation are well controlled. Photo conductivity studies of these crystals revealed negative photoconductivity nature. The photocurrent is found to be less than the dark current at every applied electric field. Rare Earth compounds are known for their interesting electric, magnetic and luminescent properties. Recent investigations on the fluorescence of some rare earth oxalates suggest their potentiality for their optical applications. Rare Earth oxalates evoked greater attention because of their ionic conduction.

Kuryan, Soosy; Abraham, Rosalin; Isac, Jayakumari

2007-03-01

178

Rare earth garnet selective emitter  

NASA Technical Reports Server (NTRS)

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

179

19. General view showing garneting machine number eight on right, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. General view showing garneting machine number eight on right, and garneting machines numbers four through seven on left in background - Norfolk Manufacturing Company Cotton Mill, 90 Milton Street, Dedham, Norfolk County, MA

180

Gallium poisoning: A rare case report  

Microsoft Academic Search

The authors present a case of a college student who suffered acute gallium poisoning as a result of accidental exposure to gallium halide complexes. This is extremely rare and has never been reported in the literature. Acute symptoms after the incident, which initially presented as dermatitis and appeared relatively not life-threatening, rapidly progressed to dangerous episodes of tachycardia, tremors, dyspnea,

Chris S. Ivanoff; Athena E. Ivanoff; Timothy L. Hottel

181

Growth and characterization of (Y[sub 3]Fe[sub 5]O[sub 12]--Bi[sub 3]Fe[sub 5]O[sub 12]) heterostructures by pulsed laser deposition  

SciTech Connect

Superlattice heterostructures consisting of alternating single crystalline ferrimagnetic yttrium--iron--garnet (YIG) and bismuth--iron--garnet (BIG) thin film layers on gadolinium--gallium--garnet substrates show an increased saturation magnetization with respect to that of the monolayered structures grown under the same conditions. The observed effect is attributed to the distortions introduced in the YIG layers by the adjacent BIG layers. In this letter, we report our growth approach, by pulsed laser deposition, of these unusually performing thin film heterostructures.

Simion, B.M.; Thomas, G. (Department of Materials Science and Engineering, University of California at Berkeley and Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Ramesh, R.; Keramidas, V.G. (Bell Communications Research, Red Bank, New Jersey 07701 (United States)); Pfeffer, R.L. (U.S. Army Research Laboratory, Ft. Monmouth, New Jersey 07701 (United States))

1995-02-13

182

Processing to obtain high-purity gallium  

NASA Astrophysics Data System (ADS)

Gallium has become increasingly popular as a substrate material for electronic devices. Aside from ore, gallium can be obtained from such industrial sources as the Bayer process caustic liquor that is a byproduct of bauxite processing, flue dust removed from the fume-collection system in plants that produce aluminum by the electrolytic process, zinc refinery residues, gallium scrap materials, and coal fly ash. The purification process for gallium can start with solvent-extraction processes where the concentrations of impurities, especially metals, are reduced to the ppm range. This article describes how ultra-purification techniques can be employed to reduce the undesirable impurities to the low ppb range. The various procedures described give an idea as to the extent of work needed to obtain and prepare high-purity gallium for electronic application.

Bautista, Renato G.

2003-03-01

183

Gallium Electromagnetic (GEM) Thrustor Concept and Design  

NASA Technical Reports Server (NTRS)

We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

Polzin, Kurt A.; Markusic, Thomas E.

2006-01-01

184

Investigation of self-induced depolarization of laser radiation in terbium gallium garnet  

Microsoft Academic Search

Absorption of laser radiation in magnetooptical materials results in a temperature gradient which induces depolarization due to both the temperature dependence of the Verdet constant and the photoelastic effect of thermal strains. This results in a limitation of the isolation ratio of Faraday isolators in high average power lasers. Here, we derive expressions for the isolation ratio as a function

Efim A. Khazanov; Oleg V. Kulagin; Sanichiro Yoshida; David B. Tanner; David H. Reitze

1999-01-01

185

Understanding garnet variability: Application of geometallurgy to diamonds and exploration  

Microsoft Academic Search

Peridotitic and eclogitic garnets are a fundamental component in understanding mantle petrology, diamond petrogenesis, and the ascent of mantle materials in kimberlites. They are also critical in exploration programs, as the presence of mantle garnets at the earth's surface provides an indication of dispersion from a deeply derived magmatic carrier. The composition of these garnets further is used as an

K. O. Hoal; S. K. Appleby; J. G. Stammer

2009-01-01

186

The Geoscience Affec-ve Research NETwork (GARNET) Project  

E-print Network

The Geoscience Affec-ve Research NETwork (GARNET) Project: What do we know in STEM #12;GARNET:GeoscienceAffectiveResearchNetwork 3h_p://serc.carleton.edu/NAGTWorkshops/affec-ve/workshop07/ GARNET (Geoscience Affective Research Network)3 Goal: project developed

Elser, Jim

187

The Prototype-Instance Object Systems in Amulet and Garnet  

E-print Network

The Prototype-Instance Object Systems in Amulet and Garnet Brad A. Myers, Rich McDaniel, Rob Miller Software Project has been investigating prototype-based programming in two large-scale systems: Garnet in Amulet and Garnet - 1 1. Introduction We have built two user interface development environments that use

Myers, Brad A.

188

ORIGINAL PAPER Melts of garnet lherzolite: experiments, models and comparison  

E-print Network

ORIGINAL PAPER Melts of garnet lherzolite: experiments, models and comparison to melts and 1,380­1,480 °C. The experiments-produced liquids multi- ply saturated with spinel and garnet lherzolite phase assemblages (olivine, orthopyroxene, clinopyroxene and spinel ± garnet) under nominally

Skemer, Philip

189

Petrogenesis of garnet lherzolite, Cima di Gagnone, Lepontine Alps  

Microsoft Academic Search

Garnet lherzolite at Cima di Gagnone has chemical and mineralogical properties similar to those of other garnet lherzolites in the lower Pennine Adula\\/Cima Lunga Nappe (Alpe Arami, Monte Duria). The Cima di Gagnone occurrence encloses mafic boudins that belong to an eclogite-metarodingite suite common in the numerous neighboring ultramafic lenses. The ultramafic rocks at Cima di Gagnone, including the garnet

Bernard W. Evans; Volkmar Trommsdorff

1978-01-01

190

Structural relaxation around substitutional Cr3+ in pyrope garnet  

E-print Network

1 Structural relaxation around substitutional Cr3+ in pyrope garnet Amélie Juhin,1, Georges Calas,1 barometry (see e.g., Grütter et al. 2006). The presence of Cr in the garnet lattice shifts significantly the spinel- garnet transformation -a major phase boundary in the Earth's upper mantle- to pressures as high

191

Garnet: Comprehensive Support for Graphical, Highly Interactive User Interfaces  

Microsoft Academic Search

The Garnet research project, which is creating a set of tools to aid the design and implementation of highly interactive, graphical, direct-manipulation user interfaces, is discussed. Garnet also helps designers rapidly develop prototypes for different interfaces and explore various user-interface metaphors during early product design. It emphasizes easy specification of object behavior, often by demonstration and without programming. Garnet contains

Brad A. Myers; Dario A. Giuse; Roger B. Dannenberg; Brad T. Vander Zanden; David S. Kosbie; Edward Pervin; Andrew Mickish; Philippe Marchal

1990-01-01

192

OPTICAL FARADAY ROTATION IN FERRIMAGNETIC GARNETS By A. M. CLOGSTON,  

E-print Network

151 OPTICAL FARADAY ROTATION IN FERRIMAGNETIC GARNETS By A. M. CLOGSTON, Bell Telephone garnets exhibit a large optical Faraday rotation. The transi- tions involved are both spin and parity recently reported that the ferrimagnetic garnets are suffi- ciently transparent in the visible region

Paris-Sud XI, Université de

193

Activity-composition relationships for pyrope-grossular garnet  

Microsoft Academic Search

Activity coefficients (?) for grossular in pyrope-grossular garnet have been determined experimentally using the divariant assemblage garnet-anorthite-sillimanite (kyanite)-quartz. Values of ? for garnets with 10–12 mole % grossular have been obtained at 1000 °, 1100 °, 1200 ° and 1300 ° C at pressures between 15 and 21 Kb. The data are consistent with a symmetrical regular solid model for

B. J. Hensen; R. Schmid; B. J. Wood

1975-01-01

194

Radiation effects in ferrate garnet S. Utsunomiya a  

E-print Network

Radiation effects in ferrate garnet S. Utsunomiya a , S. Yudintsev b , R.C. Ewing a,* a Department garnets (A3B2(XO4)3, Ia3d, Z = 8) were examined by ion beam irradiations with in situ observation (T = 298 Laboratory. The garnet compositions include: A = Ca, Gd, Th, and Ce; B = Zr, Fe. The critical amorphization

Utsunomiya, Satoshi

195

Combinatorial pulsed laser deposition of doped yttrium iron garnet films on yttrium aluminium garnet  

NASA Astrophysics Data System (ADS)

We investigate the crystalline growth of yttrium iron garnet (YIG) films doped with bismuth (Bi) and cerium (Ce) by combinatorial pulsed laser deposition, co-ablating a YIG target and either a Bi2O3 or a CeO2 target, for applications in microwave and optical communications. Substrate temperature is critical for crystalline growth of YIG with simultaneous inclusion of Bi in the garnet lattice, whereas Ce is not incorporated in the garnet structure, but forms a separate CeO2 phase.

Sposito, A.; Gregory, S. A.; de Groot, P. A. J.; Eason, R. W.

2014-02-01

196

Combinatorial pulsed laser deposition of doped yttrium iron garnet films on yttrium aluminium garnet  

SciTech Connect

We investigate the crystalline growth of yttrium iron garnet (YIG) films doped with bismuth (Bi) and cerium (Ce) by combinatorial pulsed laser deposition, co-ablating a YIG target and either a Bi{sub 2}O{sub 3} or a CeO{sub 2} target, for applications in microwave and optical communications. Substrate temperature is critical for crystalline growth of YIG with simultaneous inclusion of Bi in the garnet lattice, whereas Ce is not incorporated in the garnet structure, but forms a separate CeO{sub 2} phase.

Sposito, A., E-mail: as11g10@orc.soton.ac.uk; Eason, R. W. [Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom); Gregory, S. A.; Groot, P. A. J. de [Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)

2014-02-07

197

Microstructural characterization of sputtered garnet materials and all-garnet magnetic heterostructures: establishing the technology for magnetic photonic crystal fabrication  

Microsoft Academic Search

We have established a set of technologies for the deposition and annealing of magneto-optic ferrite and paramagnetic garnets, as well as multilayer nanostructures which are based on these materials, for use in magnetic photonic crystals. Transmission electron microscope analysis has been performed to investigate the structure of both amorphous and crystallized garnet layers, nanocrystallites and layer interfaces within all-garnet heterostructures.

Mikhail Vasiliev; P. C. Wo; Kamal Alameh; Paul Munroe; Zonghan Xie; V. A. Kotov; V. I. Burkov

2009-01-01

198

Microstructural characterization of sputtered garnet materials and all-garnet magnetic heterostructures: establishing the technology for magnetic photonic crystal fabrication  

NASA Astrophysics Data System (ADS)

We have established a set of technologies for the deposition and annealing of magneto-optic ferrite and paramagnetic garnets, as well as multilayer nanostructures which are based on these materials, for use in magnetic photonic crystals. Transmission electron microscope analysis has been performed to investigate the structure of both amorphous and crystallized garnet layers, nanocrystallites and layer interfaces within all-garnet heterostructures.

Vasiliev, M.; Wo, P. C.; Alameh, K.; Munroe, P.; Xie, Z.; Kotov, V. A.; Burkov, V. I.

2009-07-01

199

Effect of grossular-content in garnet on the partitioning of Fe and Mg between garnet and biotite  

Microsoft Academic Search

In contrast to Ferry (1980) (XCa)-values in garnet even lower than 0.1 have a significant effect on the calculated equilibrium temperature using the experimental calibration of the Fe and Mg paritioning between garnet and biotite. Garnet compositions and Mg\\/Fe — distribution coefficients from samples of the Eoalpine staurolite — in zone in the southern Ötztal are related by the quadratic

Georg Hoinkes

1986-01-01

200

Micro-Raman spectra of ugrandite garnet.  

PubMed

The natural garnets from chromite ores associated with pegmatoid pyroxenites of Sangalyk area (Uchaly ore district, southern Urals, Russia) were studied by means of micro-Raman spectroscopy. The compositions of these garnets were close to ugrandite, an isomorphous intermediate group of uvarovite-grossularite-andradite, X(3)Y(2)(SiO(4))(3), X = Ca(2+), Y = Al(3+), Fe(3+), Cr(3+), according to Raman spectra and X-ray microprobe analyses. An assignment of most of the observed bands in visible and near infrared Raman spectra is reported. PMID:19084471

Moroz, T; Ragozin, A; Salikhov, D; Belikova, G; Puchkov, V; Kagi, H

2009-08-01

201

Cost and availability of gadolinium for nuclear fuel reprocessing plants  

Microsoft Academic Search

Gadolinium is currently planned for use as a soluble neutron poison in nuclear fuel reprocessing plants to prevent criticality of solutions of spent fuel. Gadolinium is relatively rare and expensive. The present study was undertaken therefore to estimate whether this material is likely to be available in quantities sufficient for fuel reprocessing and at reasonable prices. It was found that

Klepper

1985-01-01

202

Extraction-chromatographic affinage in gadolinium-153 preparation production technology  

SciTech Connect

The gadolinium 153 preparation is used for production of medical gamma-sources which are applicable in bone densimeters for early diagnostics of osteoporosis. This preparation must meet strict requirements with respect to the content of europium radionuclides and specific activity. In The Research Institute of Atomic Reactors (RIAR) the gadolinium 153 is produced by neutron irradiation of Europium 151. This process is described.

Melnik, M.I.; Karelin, E.A.; Kuznetsov, R.A. [and others

1993-12-31

203

Clinical Applications of Gallium-68  

PubMed Central

Gallium-68 is a positron-emitting radioisotope that is produced from a 68Ge/68Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. 68Ga-DOTATOC, 8Ga-DOTATATE, 68Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with 68Ga over the past few years around the world, including within the United States. An estimated ~10,000 scans are being performed yearly in Europe at about 100 centers utilizing 68Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied 68Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

Banerjee, Sangeeta Ray; Pomper, Martin G.

2013-01-01

204

Liver cysteine proteinases in macrophage depression induced by gadolinium chloride.  

PubMed

Liver lysosomal enzymes during macrophage depression (gadolinium chloride, 7 mg/kg, intravenously) and macrophage stimulation (zymosan, 100 mg/kg, intravenously) have been studied. It was shown that gadolinium chloride treatment of rats reduced the rate of carbon particles phagocytosis at 24 and 48 h after the single administration. Decreased endocytic capacity of Kupffer cells was confirmed also by electron microscopy. Gadolinium chloride induced labilization of liver lysosomes (increased free activity of cathepsins B and L); there was no changes of specific activity of liver cysteine proteinases (24 h). Gadolinium chloride prevented death of rats after administration of non-sonicated particular zymosan particles, resulting to 70% survival, compare with the 17% survival in group with zymosan alone. We can summarize that macrophages depression by gadolinium chloride abolish symptoms of inflammation in zymosan-model, influencing on cysteine proteinases of Kupffer cells. PMID:9330713

Korolenko, T; Svechnikova, I; Urazgaliyev, K; Vakulin, G; Djanaeva, S

1997-01-01

205

Light deflection in gadolinium molybdate ferroelastic crystals  

NASA Astrophysics Data System (ADS)

The deflection of a He-Ne light beam by polydomain gadolinium molybdate (GMO) crystals has been studied with respect to incidence angle icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> i on the sample at room temperature. The A and B deflected beams do not cross each other during the icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> i variation, in contrast to results and calculations previously published. The model using the Fresnel equation confirms this result. The model presented is more accurate for numerical calculation than that using the Huygens construction.

Staniorowski, Piotr; Bornarel, Jean

2000-02-01

206

Gadolinium study for a water Cherenkov detector  

E-print Network

Modification of large water Cherenkov detectors by addition of gadolinium has been proposed. The large cross section for neutron capture on Gd will greatly improve the sensitivity to antielectron neutrinos from supernovae and reactors. A five-year project to build and develop a prototype detector based on Super-Kamiokande (SK) has started. We are performing various studies, including a material soak test in Gd solution, light attenuation length measurements, purification system development, and neutron tagging efficiency measurements using SK data and a Geant4-based simulation. We present an overview of the project and the recent R&D results.

Kibayashi, Atsuko

2009-01-01

207

Status of gallium-67 in tumor detector  

SciTech Connect

The efficacy of gallium-67 citrate in detecting specific tumors is discussed. Tumors in which gallium-67 imaging is useful as a diagnostic tool include Hodgkin's disease, histiocystic lymphoma, Burkitt's lymphoma, hepatoma melanoma, and leukemia. It has not been found to be effective in diagnosing head and neck tumors, gastrointestinal tumors, genitourinary tract tumors, breast tumors, and pediatric tumors. Gallium may be useful in the evaluation of non-Hodgkin's lymphoma, testicular carcinoma, mesothelioma, and carcinoma of the lung. It may also be useful for determining response to treatment and prognosis in some neoplasms.

Hoffer, P.

1980-04-01

208

Domain Collapse in Grooved Magnetic Garnet Material  

NASA Technical Reports Server (NTRS)

Domain collapse fields in grooved garnet material were investigated by experimental observation and numerical simulation. The results indicate that the change in domain collapse field is largely due to magnetostatic effects produced by the groove edge. A simplified model based on the effective field produced at a groove edge, and local changes in the material thickness explain the observed trends very well.!.

Peredo, J.; Fedyunin, Y.; Patterson, G.

1995-01-01

209

The effects of binding type on luminescence LED phosphor based on GGG/Ce3+  

NASA Astrophysics Data System (ADS)

Luminescence and reflectance spectra of coatings based on gadolinium gallium garnet doped by cerium (GGG/Ce3+) with silicone resin or potassium liquid glass compound were analyzed depending on concentration. It was established that the maximum emissions of the coatings at 75 wt.% compound concentration have luminescence band at 570 nm and absorption band at 470 nm. Both bands were detected by absorption or emission of cerium ions in gadolinium gallium garnet. Ce3+ ion transition into Ce4+ ion was observed upon quantum absorption, and the reverse transition was observed upon quantum emission.

Mikhailov, M. M.; Neshchimenko, V. V.; Shavlyuk, V. V.

2014-12-01

210

Synthetic studies of aluminum and lanthanide complexes and the chemical vapor deposition of gadolinium oxide films  

NASA Astrophysics Data System (ADS)

The synthesis of homoleptic gallium and indium alkanethiolate complexes (M(SR)3) were reported by Suh and Hoffman but the analogous aluminum alkanethiolate complexes have never been prepared. Synthetic studies to complete the group 13 series were performed resulting in the preparation of Al(SR) 3 where R = t-Bu or i-Pr. Stable amine adducts Al(SR)3(R'NMe2) where R = i-Pr or t-Bu and R' = H or Et were also synthesized. X-Ray crystallographic studies show that the homoleptic thiolates are dimeric in the solid state. Homoleptic metal amide complexes, such as M(NR2)4 (M = Zr, Si or Sn) and Ta(NMe2)5, have been shown to be excellent precursors for the chemical vapor deposition of metal oxide films. With this as background, an attempt was made to synthesize new cerium amides for use as precursors to cerium oxide thin films. The reaction of CeCl 3(THF)2 with LiN-t-BuSiMe3 yielded Ce(N-t-BuSiMe3)3, but the complex was not thermally stable. Attempts to prepare bulky TMP derivatives (TMP = 2,2,6,6-tetramethylpiperidide) resulted in the isolation of the alkoxide-bridged dimer [Ce(TMP)2(mu-OCH=CH 2)]2 and Ce(TMP)3. A synthetic route to gadolinium and samarium cyclopentadienyl alkoxides was developed and gadolinium oxide films were prepared from one of the new complexes by chemical vapor deposition. Reactions of Ln(Cp)3 (Ln = Gd or Sm) with i-PrMe2COH yielded Sm2(OCMe 2-i-Pr)3Cp3, [Sm(OCMe2- i-Pr)2(Cp)]2, and [Gd(OCMe2- i-Pr)2(Cp)]2. Gadolinium oxide films were deposited at 300--500°C in a low-pressure chemical vapor deposition process from [Gd(OCMe2-i-Pr)2(Cp)]2 and O2 precursors. The films were characterized by X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry.

Daniel, Sherrika Detrice

211

Atomic and electronic structure of gadolinium oxide  

NASA Astrophysics Data System (ADS)

Rare earth gadolinium oxide film has been studied by X-ray absorption fine structure (XAFS) at Gd L3-edge and energy electron loss spectroscopy (EELS) spectroscopies. XAFS data showed that the nearest Gd coordination shells consist of six oxygen atoms at ~2.308(2) Å and six gadolinium atoms at ~3.57(2) Å corresponding to Gd2O3 with a space group of Ia-3. EELS analysis of the film revealed excitations at the energies of 14.2, 19.9 eV which are due to electron transition from the valence band to the conductive one; excitations at the energies of 22.2-23.5 eV originated from valence electrons plasmon oscillations (bulk plasmons); and the excitation at 5.5 eV resulted from the electron transition at defects. When the photon energy changed from 1.5 to 5.0 eV the refractive index increased from 1.92 to 2.15.

Viktorovich Perevalov, Timofey; Evgenievich Dolbak, Andrey; Aleksandrovich Shvets, Vasilii; Alekseevich Gritsenko, Vladimir; Ivanovna Asanova, Tatijana; Borisovich Erenburg, Simon

2014-01-01

212

Recovery of gallium from aluminum industry residues  

SciTech Connect

A procedure is proposed to recover gallium from flue dust aluminum residues produced in plants by using solid-phase extraction with a commercial polyether-type polyurethane foam (PUF). Gallium can be separated from high concentrations of aluminum, iron, nickel, titanium, vanadium, copper, zinc, sulfate, fluoride, and chloride by extraction with PUF from 3 M sulfuric acid and 3 M sodium chloride concentration medium with at least a 92% efficiency. Gallium backextraction was fast and quantitative with ethanol solution. In all recovery steps commercial-grade reagents could be used, including tap water. The recovered gallium was precipitated with sodium hydroxide solution, purified by dissolution and precipitation, calcinated, and the final oxide was 98.6% pure.

Carvalho, M.S.; Neto, K.C.M.; Nobrega, A.W.; Medeiros, J.A.

2000-01-01

213

49 CFR 173.162 - Gallium.  

Code of Federal Regulations, 2011 CFR

...Regulations Relating to Transportation PIPELINE AND HAZARDOUS...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...performance level for transportation by aircraft, and...transport gallium at low temperatures in...permit the release of carbon dioxide gas....

2011-10-01

214

49 CFR 173.162 - Gallium.  

Code of Federal Regulations, 2012 CFR

...Regulations Relating to Transportation PIPELINE AND HAZARDOUS...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...performance level for transportation by aircraft, and...transport gallium at low temperatures in...permit the release of carbon dioxide gas....

2012-10-01

215

49 CFR 173.162 - Gallium.  

Code of Federal Regulations, 2010 CFR

...Regulations Relating to Transportation PIPELINE AND HAZARDOUS...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...performance level for transportation by aircraft, and...transport gallium at low temperatures in...permit the release of carbon dioxide gas....

2010-10-01

216

Gallium arsenide passivation through nitridation with hydrazine  

NASA Astrophysics Data System (ADS)

Passivating films were grown on gallium arsenide by direct nitridation with hydrazine at 300-400 °C. Auger electron spectroscopy and x-ray photoelectron spectroscopy analysis show that the films are primarily gallium nitride with an oxide impurity. The oxide content is a function of the surface pretreatment, reaction temperature, and water concentration in the hydrazine. Improvements in the band gap photoluminescence with nitridation indicate a lower surface state density and reflect an improvement in the termination of the semiconductor lattice.

Vogt, Kirkland W.; Kohl, Paul A.

1993-11-01

217

Three-dimensional patterns of garnet nucleation and growth  

NASA Astrophysics Data System (ADS)

Three-dimensional compositional zoning patterns in garnet-zone garnets from Harpswell Neck, Maine, United States, suggest complex patterns of nucleation and growth. Compositional zoning is often asymmetric, and core compositions do not always coincide with the geometric center of the garnet. In detail, garnet zoning patterns show multiple, isolated, high-MnO areas that we interpret as sites of garnet nucleation. If it is assumed that garnet growth is close to equilibrium and the Mn zoning is not significantly modified by diffusion, then the MnO contours or isosurfaces can serve as a proxy for patterns of garnet nucleation and growth. Computer-generated, three-dimensional animations of these patchwork MnO zoning patterns reveal that many garnets contain multiple nuclei that grew and coalesced to form a single crystal. New nuclei often appeared next to preexisting porphyroblasts and became incorporated into the growing crystal. Contrary to the widely held idea that garnets grow radially outward from a single nucleus, we propose that many of the garnets examined in this study grew by the coalescence of multiple nuclei.

Daniel, Christopher G.; Spear, Frank S.

1998-06-01

218

Gallium Arsenide wafer scale integration  

NASA Astrophysics Data System (ADS)

Gallium Arsenide (GaAs) digital MESFET technology has recently begun to appear in the semiconductor marketplace. The initial commercial offerings are at the small to medium scale integration levels. The high speed of these parts would seem to be very attractive for designers of high performance signal processing equipment. Persistent yield problems, however, have prevented the appearance of large scale integrated circuits. As a result, intrapackage and interpackage signal propagation problems such as coupling, parasitics and delay are likely to negate much of the benefits of the fast MESFET logic devices for large systems constructed with such small scale building blocks. An early packaging concept, Wafer Scale Integration (WSI), which could possibly be used to address some of these limitations is reexamined.

McDonald, J. F.; Taylor, G.; Steinvorth, R.; Donlan, B.; Bergendahl, A. S.

1985-08-01

219

Generator for gallium-68 and compositions obtained therefrom  

DOEpatents

A generator for obtaining radioactive gallium-68 from germanium-68 bound in a resin containing unsubstituted phenolic hydroxyl groups. The germanium-68 is loaded into the resin from an aqueous solution of the germanium-68. A physiologically acceptable solution of gallium-68 having an activity of 0.1 to 50 millicuries per milliliter of gallium-68 solution is obtained. The solution is obtained from the bound germanium-68 which forms gallium-68 in situ by eluting the column with a hydrochloric acid solution to form an acidic solution of gallium-68. The acidic solution of gallium-68 can be neutralized.

Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

1981-01-01

220

Metal Contacts to Gallium Arsenide.  

NASA Astrophysics Data System (ADS)

While various high performance devices fabricated from the gallium arsenide (GaAs) and related materials have generated considerable interest, metallization are fundamental components to all semiconductor devices and integrated circuits. The essential roles of metallization systems are providing the desired electrical paths between the active region of the semiconductor and the external circuits through the metal interconnections and contacts. In this work, in-situ clean of native oxide, high temperature n-type, low temperature n-type and low temperature p-type ohmic metal systems have been studied. Argon ion mill was used to remove the native oxide prior to metal deposition. For high temperature process n-type GaAs ohmic contacts, Tungsten (W) and Tungsten Silicide (WSi) were used with an epitaxial grown graded Indium Gallium Arsenide (InGaAs) layer (0.2 eV) on GaAs. In addition, refractory metals, Molybdenum (Mo), was incorporated in the Gold-Germanium (AuGe) based on n-type GaAs ohmic contacts to replace conventional silver as barrier to prevent the reaction between ohmic metal and chlorine based plasma as well as the ohmic metallization intermixing which degrades the device performance. Finally, Indium/Gold-Beryllium (In/Au-Be) alloy has been developed as an ohmic contact for p-type GaAs to reduce the contact resistance. The Fermi-level pinning of GaAs has been dominated by the surface states. The Schottky barrier height of metal contacts are about 0.8 V regardless of the metal systems. By using p-n junction approach, barrier height of pulsed C-doped layers was achieved as high as 1.4 V. Arsenic implantation into GaAs method was also used to enhance the barrier height of 1.6 V.

Ren, Fan

1991-07-01

221

Gallium arsenide recycle chemistry and metallurgy  

SciTech Connect

Research was successfully conducted on a smelting approach to separate gallium from arsenic using a liquid copper alloy to collect arsenic while oxidizing the gallium into a soda-silica slag. The slag and copper form two immiscible liquid phases. With GaAs in powder form, smelting at 1150 to 1220{degree}C yields 98% of the gallium in the slag and at least 96% of the arsenic in the copper. The gallium concentration in this slag is, relative to other sources, very high, and it can be processed further to obtain crude gallium. The effect of chemical oxidizers on arsenic and gallium distribution between slag and copper was determined. The solidified copper-arsenic alloy is environmentally inert. However, any precious metals present with the electronic scrap will nearly completely collect in the copper. Commercial copper refineries are capable of recovering precious metals from the copper-arsenic alloy, and are equipped to handle large amounts of arsenic when compared with the amount of arsenic used in GaAs devices, even with many fold future expansions.

Bartlett, R.W.

1987-03-23

222

Garnets from the Camafuca-Camazambo kimberlite (Angola).  

PubMed

This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004) and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10) and Ca-saturated (G9) garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa). The occurrence of diamond stability field garnets (G10D) is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue. PMID:16710568

Correia, Eugénio A; Laiginhas, Fernando A T P

2006-06-01

223

Author's personal copy Corundum-bearing garnet peridotite from northern Dominican Republic  

E-print Network

Author's personal copy Corundum-bearing garnet peridotite from northern Dominican Republic October 2009 Available online 21 October 2009 Keywords: Garnet peridotite Mantle flow Arc cumulates Subduction channel Corundum Ultra-high pressure metamorphism Caribbean arc Garnet peridotite in oceanic

224

Removal of gadolinium nitrate from heavy water  

SciTech Connect

Work was conducted to develop a cost-effective process to purify 181 55-gallon drums containing spent heavy water moderator (D2O) contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS). These drums also contain low level radioactive contamination, including tritium, which complicates treatment options. Presently, the drums of degraded moderator are being stored on site. It was suggested that a process utilizing biological mechanisms could potentially lower the total cost of heavy water purification by allowing the use of smaller equipment with less product loss and a reduction in the quantity of secondary waste materials produced by the current baseline process (ion exchange).

Wilde, E.W.

2000-03-22

225

Terbium–yttrium–iron garnet revisited  

Microsoft Academic Search

An investigation was made into the synthesis and magnetic properties of Tb(3?x)YxFe5O12 garnet ferrite synthesized by coprecipitation from hydrated chlorides of rare-earth elements and ferrous sulfate. The mixed hydroxide coprecipitate was calcined at 1000°C. Ring-shaped compacts were obtained by dry pressing of finely milled calcined coprecipitate powder to which an aqueous solution containing 15wt% of PVA was added. The compacts

Sandra da Silva Marins; Tsuneharu Ogasawara; Angélica Soares Ogasawara

2007-01-01

226

Spontaneous phase transitions in ferrite garnet films  

NASA Astrophysics Data System (ADS)

Spontaneous phase transitions in ferrite garnet films have been studied. It has been shown that, with variations in the temperature, domain walls undergo phase transitions which cause spontaneous phase transitions in the lattice of cylindrical magnetic domains. The phase transition in a domain wall causes a spin-reorientation phase transition over the whole sample near the magnetic compensation point. The character of the phase transition in the domain wall determines the mechanism of the spin-reorientation phase transition.

Siryuk, Yu. A.; Bezus, A. V.

2013-03-01

227

Window structure for passivating solar cells based on gallium arsenide  

NASA Technical Reports Server (NTRS)

Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

Barnett, Allen M. (Inventor)

1985-01-01

228

GALLIUM--2001 29.1 By Deborah A. Kramer  

E-print Network

capacity expansions, very few additional expansions were announced in 2001. Because gallium nitride (GaN-emitting diodes (LEDs)] as the second largest end use. World production of virgin gallium was estimated to be 81

229

Nd3+-doped Ca3Ga2Ge3O12 garnet: A new optical pressure sensor  

NASA Astrophysics Data System (ADS)

A pressure-induced shift of the emission spectrum corresponding to the near infrared 4F3/2 ? 4I9/2 transition of Nd3+ ions in a calcium gadolinium germanium garnet was obtained in the interval from ambient conditions up to 23 GPa in order to test its suitability as an optical pressure sensor. Although several Nd3+ non-equivalent centers are present in this garnet, which complicates the assignation of the optical transitions, the R1,R2 ? Z5 transitions are unequivocally characterised and fit the requirements of an ideal optical pressure sensor. Results obtained for these emission peaks indicate large pressure coefficients of -8.8 and -10.8 cm-1 GPa-1; meanwhile, the rest of the R1,R2 ? Z1-4 emissions remain almost unchanged under pressure. This behaviour is ascribed to the influence of the crystal-field at high pressure on the Z5 Stark level of the ground state and can be easily reproduced exclusively by varying the cubic term of fourth rank of the crystal-field Hamiltonian, which accounts for the Nd3+ ions and is related to medium Nd3+-oxygen distances. These coefficients are larger than those found for the R-lines of Cr3+ in ruby, -7.56 cm-1 GPa-1, suggesting that this system may be a good candidate for a luminescence pressure sensor.

Rodríguez-Mendoza, U. R.; León-Luis, S. F.; Muñoz-Santiuste, J. E.; Jaque, D.; Lavín, V.

2013-06-01

230

Symmetry and magnetoelectric effects in garnet crystals and films  

NASA Astrophysics Data System (ADS)

The magnetoelectricity of garnets is considered by means of a symmetry and quantum mechanical combined analysis. It is shown that the magnetoelectric effect is not realized in most garnets although the necessary condition of the crystal magnetic structure antisymmetry in them is held at low temperatures. Nevertheless, the effect can be observed in some garnets as well as other odd effects, namely, the piezomagnetic effect, the magnetic field evoked piezoelectric one, etc. It is also discovered that magnetic fields can induce specific antiferroelectric structures in garnet crystals and produce electric polarization in epitaxial films. The polarization can also be caused in a bulk crystal by an inhomogeneous magnetic field.

Popov, A. I.; Plokhov, D. I.; Zvezdin, A. K.

2014-12-01

231

Inclusion/lamella mineralogy and chemical characteristics of garnets from the Garnet Ridge in the Colorado Plateau, northern Arizona  

NASA Astrophysics Data System (ADS)

A wide variety of garnets as xenocrysts and those in xenoliths, come from kimberlitic diatreme (Smith et al. 2004), occurs at the Garnet Ridge. Koga and Ogasawara (2012) classified these garnets into 9 groups: (a) Cr and pyrope-rich garnet, (b) pyrope-rich reddish brown garnet, (c) reddish brown garnet, (d) garnet in eclogite, (e) garnet in metasomatized eclogite, (f) garnet aggregate, (g) garnet megacryst, (h) garnet in metasomatic rock I, (i) garnet in metasomatic rock II. They divided genetically these groups into four: mantle peridotite (a, b), subducted oceanic crust (d, e), high-pressure metasomatism (c, f, g), low-pressure metasomatism (h, i).In this study, the following 4 groups (a, b, f, g) were chose for inclusion mineralogy by laser Raman spectroscopy. Groups (a) and (b): pyrope-rich garnets (a: 45-82, b: 61-80 Prp mol%) both Cr-rich and Cr-poor (a: 1.0-5.9, b: 0.0-1.0 wt.% Cr2O3) are Ca-poor (1.5-7.0 wt.% CaO) and single-crystals of 5-15 mm in diameter. Group (a) is identical to chrome-pyrope based on the classification of kimberlitic garnets by Dawson and Stephens (1975). CaO-Cr2O3 ratio of (a, b) indicates lherzorite origin (Turkin and Sobolev 2009). Wang et al. (1999) have reported the detailed inclusion and lamella mineralogy of pyrope-rich garnets from the Garnet Ridge. We identified inclusions of Chl (OH: 3450, 3582, 3679 cm-1), Amp (OH: 3685, 3711 cm-1), Ol, Opx, Cpx, Rt (OH: 3295 cm-1), Mgs, Dol, Cal, sulfides, fluid (OH: 3445 cm-1) and spherical composite inclusions of Amp, Ap, Dol, Mgs, Rt and sulfides, and oriented lamellae (presumable exsolution) of Qz, Ol, Opx, Cpx, Amp, Chl, Rt, Ilm, crichtonite (6-7 Peaks at 120-820 cm-1), carmichaelite (710-782 cm-1, OH: 3340 cm-1), Ap (OH: 3570 cm-1) and Ti-Chn (OH: 3404, 3527, 3564 cm-1) adjacent to the oriented Ol. The mineral assemblages of the inclusion and lamella show a correlation with the host garnet compositions; inclusions: (a, b) Ol + Opx + Cpx × composite, (b, low Mg) Opx + Cpx + Amp, oriented lamellae: (a) Rt + Cr-bearing titanates + Ol, (b) Rt + titanates + Px or Ol, (b, low Mg) Rt + Ilm + Amp + Chl. Groups (f) and (g): aggregate (f) and megacryst (g) are rich in Alm, Grs and Pyp; almost 1:1:1. The chemistries of the garnets fall into pyrope-grossular almandine by Dawson and Stephens (1975). Both garnets contain Cpx, Zrn, sulfides, and oriented Ap and Rt rods. Chl, Cpx, Rt and Ilm grains occur near grain boundaries of (f). A significant variation of hydroxyls was detected in the garnets from the Garnet Ridge (Ogasawara et al. 2012); hydroxyls in garnets (c, f, g) and (a, b), but no hydroxyls in garnet (d).Detected hydroxyls in the host garnet and in identified inclusion/lamella and their assemblages may lead to clarify the volatile environments of the metasomatic processes in peridotites and subducted materials underneath the Colorado Plateau. References Turkin, A.I., Sobolev, N.V. (2009) Russ. J. Geol. Geophys., 50, 1169-1182. Smith, D. et al. (2004) Geochem. Geophys. Geosyst., 5, 4. Dawson, J. B., Stephens, W. E. (1975) J. Geol., 83, 589-607. Koga, I., Ogasawara, Y. (2012) AGU Fall Meeting, V43A-2824. Wang, L. et al., (1999) Contrib. Mineral. Petrol., 135, 164-178. Ogasawara, Y., Sakamaki, K. and Koga, I. (2012) AGU Fall Meeting, V43A-2821.

Sato, Y.; Ogasawara, Y.

2013-12-01

232

Synthesis of gadolinium oxide magnetoliposomes for magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

A method for the synthesis of gadolinium oxide magnetoliposomes, i.e., nanosized gadolinium oxide magnetic particles coated by a phospholipid membrane, is presented. Magnetoliposomes were prepared by reacting lauric acid coated gadolinium oxide nanoparticles with dimyristoylphosphatidylcholine liposomes prepared using a direct injection method. The gadolinium oxide magnetoliposomes were characterized using transmission electron microscopy imaging, x-ray diffraction, and fluorescence. The magnetic properties of the magnetoliposomes were investigated with a superconducting quantum interference device magnetometer and nuclear magnetic resonance (NMR) spectrometry. Our results indicate that the magnetoliposomes contain approximately spherical nanoparticles averaging 20 nm in diameter. The occurrence of a phospholipid bilayer surrounding the magnetic particles is confirmed both by transmission electron micrographs of samples negatively stained with uranyl acetate and by digital fluorescence imaging microscopy measurements of magnetoliposomes labeled with fluorescein. The particles are paramagnetic at room temperature. NMR measurements show that the ratio between the relaxivities of the particles depends largely on their preparation.

Roberts, Danielle; Zhu, Weibe L.; Frommen, Christoph M.; Rosenzweig, Zeev

2000-05-01

233

A comparison of three gadolinium based approaches to cancer therapy  

E-print Network

Some recent neutron capture therapy (NCT) research has focused on using compounds containing the element gadolinium (Gd), which produces internal conversion and Auger cascade electrons upon absorbing thermal neutrons. The ...

Goorley, John Timothy, 1974-

2002-01-01

234

In vivo detection of gadolinium by prompt gamma neutron activation analysis: An investigation of the potential toxicity of gadolinium-based contrast agents used in MRI  

Microsoft Academic Search

This thesis describes the development of a method to measure in vivo gadolinium (Gd) content by prompt gamma neutron activation analysis (PGNAA). PGNAA is a quantitative measurement technique that is completely non-invasive. Gadolinium has the highest thermal neutron capture cross section of all the stable elements. Gadolinium-based contrast agents are widely used in magnetic resonance imaging (MRI). The primary intention

James L Gräfe

2012-01-01

235

Gadolinium-DTPA enhancement of lung radiation fibrosis  

SciTech Connect

Gadolinium-diethylenetriamine pentaacetic acid (DTPA) enhancement of radiation-induced apical pulmonary fibrosis was observed in two patients previously treated for breast cancer. In one case the fibrosis was biopsied twice, with no change in its CT appearance over 3 years. Gadolinium-DTPA may enhance benign apical fibrosis after radiation therapy and should not, in and of itself, be used as evidence of recurrent malignancy.

Werthmuller, W.C.; Schiebler, M.L.; Whaley, R.A.; Mauro, M.A.; McCartney, W.H. (Univ. of North Carolina, Chapel Hill (USA))

1989-11-01

236

Polycrystalline Garnet Porphyroblasts, an EBSD Study  

NASA Astrophysics Data System (ADS)

Polycrystalline garnet porphyroblasts (PGP's) are significant because their formation provides information about metamorphic crystalline mechanisms, in particular during early stages of crystal growth, which may differ from those governing later stages; and because their existence may affect the chemical and structural evolution of metamorphic rocks. For example, the extent of element exchange between the garnet interior and the matrix may be affected by the presence of grain boundaries within PGP's. There have been several previous studies of PGP's but important questions about them remain; e.g. whether early coalescence is a common method by which garnets crystallize, whether grains rotate during growth to attain an energetically favorable grain-grain contact, and whether deformation and/or precursor minerals or other chemical or mechanical heterogeneities influence the formation of PGP's. PGP's have been detected by us in several different localities including; micaschist from SE Vermont (USA), including locality S35j of Rosenfeld (1968); the Solitude Range (British Columbia, Canada); the Southern Menderes Massif (Turkey); and three zones (garnet, staurolite, kyanite) from the Dutchess County Barrovian sequence in NY (USA). We have identified two types of PGP: cryptic and morphologically distinct. Cryptic PGP have no obvious morphological expression of the high angle boundaries within them and appear to be a single crystal. Morphologically distinct PGP have an obvious depression in the outer grain boundary where it is intersected by the internal grain boundary. Most PGP's contain inclusion trails and the high angle grain boundaries crosscut the trend of these as well as the inclusions themselves. PGP also show major element growth zoning that is not influenced by the internal grain boundaries except in rare cases. PGP's comprise ~ 5-35% of the garnet populations analyzed. More than 95% of the PGP's we have analyzed are comprised of 2-3 domains; the rest contain 4-16 domains. The prevalence of low- energy boundaries within the PGP's analyzed thus far is 20 ± 2%, slightly greater than the 15% predicted for a random disrtibution in cubic minerals.

Seaton, N. C.; Whitney, D. L.; Anderson, C.; Alpert, A.

2008-12-01

237

The variation in garnet, biotite and chlorite composition in medium grade pelitic rocks from the Dalradian, Scotland, with particular reference to the zonation in garnet  

Microsoft Academic Search

Garnet, biotite and host rock have been analysed along a traverse from the garnet isograd to the kyanite zone in the Dalradian of Central Perthshire, Scotland. FeO and MgO increase and MnO and CaO decrease in the garnet with increasing grade. Microprobe analyses of the garnets reveal zoning, which indicates that a garnet crystal as a whole does not equilibrate

M. P. Atherton

1968-01-01

238

Proportional counter response calculations for gallium solar neutrino detectors  

Microsoft Academic Search

Gallium-based solar neutrino detectors are sensitive to the primary pp reaction in the sun. Two experiments using gallium, SAGE in the Soviet Union and GALLEX in Europe, are under construction and are scheduled to produce data by 1989. The radioactive 71Ge produced by neutrinos interacting with the gallium detector material is chemically extracted and counted in miniature proportional counters. A

R. T. Kouzes; D. Reynolds

1989-01-01

239

Mineralogical controls on garnet composition in the cratonic mantle  

NASA Astrophysics Data System (ADS)

Garnet concentrates are a rich source of geochemical information on the mantle, but the mineralogical implications of wide ranging garnet compositions are poorly understood. We model chemical reactions between mantle minerals that may buffer the Ca-Cr lherzolitic garnet trend common in the lithospheric mantle. A harzburgitic trend of garnet compositions featuring a lower increase in Cr with Ca relative to the conventional lherzolitic trend is reported for the first time. Representation of garnet chemistry in terms of additive and exchange components in the Thompson space shows that the lherzolitic and harzburgitic trends are controlled by the cation exchanges MgFeAl ? Ca2Cr and MgFeAl4 ? Ca2Cr4, respectively. Various equilibrium reactions are presented to explain the trends assuming a closed or open system mantle. The compositional variability of the natural garnets from the Canastra 8 kimberlite (Brazil) is modeled by a linear system of mass balance equations. The solution returns the reaction coefficients of products (positive values) and reactants (negative values), which are then evaluated against the observed mantle mineralogy. In the isochemical mantle, the lherzolitic trend can form in the absence of clinopyroxene, but requires the presence of spinel and reflects the thickness of the spinel-garnet transition zone. This requirement contradicts observations on natural occurrences of the trend and the thermobarometry of the host peridotites. In the preferred model of a variably depleted mantle, the lherzolitic trend critically depends on the presence of clinopyroxene. The occurrence of lherzolitic garnet compositions in harzburgite can be explained by exhaustion of clinopyroxene as a result of garnet buffering. The open system behavior of the peridotitic mantle also provides a better explanation for the harzburgitic trend in garnet compositions. In an isochemical mantle, the trend can be controlled by many possible reactions, and no single mineral is essential. In the variably depleted mantle, spinel is required to make the harzburgitic trend garnet.

Hill, P. J. A.; Kopylova, M.; Russell, J. K.; Cookenboo, H.

2015-02-01

240

Synthesis and characterization of charge-substituted garnets YCaLnGa{sub 5}O{sub 12} (Ln = Ce,Pr,Tb)  

SciTech Connect

A low temperature method is described for the preparation of the new garnet compounds YCaLnGa{sub 5}O{sub l2} (Ln=Ce, Pr, Th). In this set of compounds (Ca{sup 2+} + Ln{sup 4+}) replaces 2 Y{sup 3+} in the parent gallium based garnet Y{sub 3}Ga{sub 5}O{sub l2} in order to stabilize as effectively as possible the Ln{sup 4+} species in the eight-coordinate ``A`` site of the garnet structure. Characterization of the oxides by x-ray powder diffraction and thermogravimetric analysis is discussed with regard to the structural relationship of the substituted compound to the parent material. The tetravalent ions Pr{sup 4+} and Tb{sup 4+} exhibit increased thermal stability in reducing conditions as compared to the Ln{sup 4+} states in the fluorite (LnO{sub 2}) and perovskite (BaLnO{sub 3}) type structures. This result is discussed with reference to the complex crystal chemistry of these systems.

Gramsch, S.A. [Argonne National Lab., IL (United States)]|[Chicago Univ., IL (United States). Dept. of Chemistry; Morss, L.R. [Argonne National Lab., IL (United States)

1993-09-01

241

Gallium uptake in myositis ossificans. Potential pitfalls in diagnosis  

SciTech Connect

Seven cases of gallium uptake in myositis ossificans are described. Gallium scans are done frequently in paraplegics, quadriplegics, and comatose patients to look for occult infection. It is important to be aware of possible gallium uptake in myositis ossificans, particularly in the extremities, which is frequent in these patients. Gallium uptake may be present prior to any abnormalities seen on plain films or CT scans. It is important to correlate roentgenograms with abnormal gallium scans, particularly in the extremities, to avoid potential pitfalls in diagnosis and prevent unnecessary antibiotic treatment. A bone scan should be obtained whenever possible, particularly when roentgenograms are negative, to confirm the diagnosis.

Salzman, L.; Lee, V.W.; Grant, P.

1987-04-01

242

/sup 67/Gallium lung scans in progressive systemic sclerosis  

SciTech Connect

/sup 67/Gallium lung scans were performed in 19 patients with progressive systemic sclerosis (scleroderma). Results were expressed quantitatively as the /sup 67/Gallium Uptake Index. The mean total pulmonary /sup 67/Gallium Uptake Index in patients was significantly higher than that in controls (41 versus 25), and 4 patients (21%) fell outside the normal range. There were no clinical or laboratory variables that correlated with the /sup 56/Gallium uptake. Increased pulmonary /sup 67/Gallium uptake in scleroderma may prove useful as an index of pulmonary disease activity.

Baron, M.; Feiglin, D.; Hyland, R.; Urowitz, M.B.; Shiff, B.

1983-08-01

243

Garnet geotherms: Pressure-temperature data from Cr-pyrope garnet xenocrysts in volcanic rocks  

Microsoft Academic Search

The temperatures and pressures of equilibration of single peridotitic garnet xenocrysts are estimated using a combination of major- and trace-element data, determined using electron microprobe (EMP) and proton induced X ray emission (PIXE). This new method enables the use of xenocrysts found in kimberlites and other volcanic rocks to determine the local paleogeotherm at the time of eruption of the

Chris G. Ryan; William L. Griffin; Norman J. Pearson

1996-01-01

244

Garnet geotherms: Pressure-temperature data from Cr-pyrope garnet xenocrysts in volcanic rocks  

Microsoft Academic Search

The temperatures and pressures of equilibration of single peridotitic garnet xenocrysts are estimated using a combination of major- and trace-element data, determined using electron mi- croprobe (EMP) and proton induced X ray emission (PIXE). This new method enables the use of xenocrysts found in kimberlites and other volcanic rocks to determine the local paleogeotherm at the time of eruption of

Chris G. Ryan; William L. Griffin; Norman J. Pearson

1996-01-01

245

Garnet and pyroxene compositions in some diamondiferous eclogites  

NASA Technical Reports Server (NTRS)

Analyses are reported for garnet and pyroxene from 17 eclogites that contain diamond. The garnets contain small but significant contents of Na, Ti and P and the pyroxenes contain traces of K. The diamond-bearing eclogites do not constitute a unique compositional group but show a range of mineral compositions consistent with a very high P-T environment.

Reid, A. M.; Brown, R. W.; Dawson, J. B.; Whitfield, G. G.; Siebert, J. C.

1976-01-01

246

Imaging Domains In Magnetic Garnets By Use Of TSMFM  

NASA Technical Reports Server (NTRS)

Tunneling-stabilized magnetic-force microscopy (TSMFM) demonstrated to yield images of magnetic domains in low-coercivity magnetic garnets with perpendicular anisotropy. Ability to generate images of domain walls and minute vertical Bloch lines aids study of vertical-Bloch-line magnetic memory devices that contain garnets. TSMFM provides desired resolution because its resolution not limited by diffraction.

Katti, Romney R.; Wu, Jiin-Chuan; Stadler, Henry L.; Rice, Paul

1994-01-01

247

An oxygen barometer with the assemblage garnet-epidote  

NASA Astrophysics Data System (ADS)

An oxygen barometer has been developed using garnet-epidote equilibria and the latest available thermodynamic data via the reaction: 2 Ca 2FeAl 2Si 3O 12(OH)= 2 Ca 2FeAl 2Si 3O 12+ H 2O+1/2 O 2epidote (Ps 33Czo 67) garnet (Alm 33Grs 67) fluidwhere epidote (Ps 33Czo 67) reacts to form (Alm 33Grs 67), water and oxygen. The garnet-epidote oxybarometer has been applied to a wide variety of metamorphic rocks including low to medium-pressure greenschists and amphibolites, as well as high-pressure eclogites. Results indicate that this equation represents a sensitive oxygen monitor with only a minor dependence on pressure. Andradite solid solution of less than 15 mol% has only minor influence in the locus of the curve in fO 2/ T space. Garnet-epidote equilibria may also provide a thermometer when combined with an independent oxygen buffer. The garnet-epidote oxythermobarometer is a reliable oxygen sensor that can be applied to many low through medium-grade metamorphic rocks. The extensive solid solution found in both garnet and epidote allows this equation to be applied to mineral pairs with a wide range of compositions. The garnet-epidote oxythermobarometer is potentially applicable to any rocks that contain the equilibrium assemblage garnet+epidote.

Donohue, Casey L.; Essene, Eric J.

2000-09-01

248

The Garnet to Majorite Transformation in Mafic Compositions  

NASA Technical Reports Server (NTRS)

The garnet to majorite transformation in mafic compositions is controlled by bulk composition and the presence of silicate melt, clinopyroxene, and silicate perovskite as well as pressure. Thus, the use of empirical geobarometers based on garnet Si(4+) and/or [Al(3+) +/- Cr(3+)] (p.f.u) seems unjustified. Additional information is contained in the original extended abstract.

Xirouchakis, D.; Draper, David S.; Agee, C. B.

2002-01-01

249

Comment on "Limit on the Electron Electric Dipole Moment in Gadolinium-Iron Garnet" [arXiv:physics/0509106  

E-print Network

In the paper being commented on it is proposed a new method for the detection of the electron EDM using the solid GdIG. There, it is argued that a sample electric polarization appears when the sample is magnetized; the common belief is that the electron EDM must be collinear with its magnetic moment. All this is objected and it is suggested that the polarization of the sample can be explained by the direct, Lorentz covariant, interaction between B^{a} and an EDM d^{a}.

Tomislav Ivezic

2010-06-14

250

Comment on "Limit on the Electron Electric Dipole Moment in Gadolinium-Iron Garnet" [arXiv:physics/0509106  

E-print Network

In the paper being commented on it is proposed a new method for the detection of the electron EDM using the solid GdIG. There, it is argued that a sample electric polarization appears when the sample is magnetized; the common belief is that the electron EDM must be collinear with its magnetic moment. All this is objected and it is suggested that the polarization of the sample can be explained by the direct, Lorentz covariant, interaction between B^{a} and an EDM d^{a}.

Ivezic, Tomislav

2010-01-01

251

Use of a Mixture of Gadolinium and Iodinated Contrast for Angiography  

SciTech Connect

The purpose of this study was to determine if the image quality of gadolinium digital subtraction angiography (DSA) can be improved by the addition of small quantities of iodinated contrast to gadolinium. The optical density (OD) of a mixture of four parts gadolinium-based contrast to one part iodinated contrast was measured through a phantom study and compared to that of full-strength gadolinium, full strength iodinated contrast, and a 20% solution of iodinated contrast. We also compared the clinical image quality of the mixture of gadolinium-based contrast and iodinated contrast relative to full-strength gadolinium and full strength iodinated contrast during DSA. The DSA image quality of the gadolinium-iodinated contrast mixture was significantly improved relative to images obtained with full-strength gadolinium and compared favorably to that obtained with full-strength iodinated contrast. The phantom data showed that the OD of the gadolinium-iodinated contrast mixture was much greater than that of full strength gadolinium and the 20% iodinated contrast solution. The increase in OD was greater than that expected from a simple additive effect of the OD of the contrast agents. Adding a small amount of iodinated contrast to gadolinium results in a significant improvement in the radiographic density and DSA image quality of gadolinium. This simple technique appears to overcome one of the major limitations of gadolinium-based angiography-poor radiographic density-while continuing to minimize the volume of administered iodinated contrast.

Badiola, Carlos M. [Bristol Hospital, Bristol, CT 06011, Department of Diagnostic Imaging (United States)], E-mail: carlioso@yahoo.com

2004-03-15

252

Chemistry and mineralogy of garnet pyroxenites from Sabah, Malaysia  

USGS Publications Warehouse

Garnet pyroxenites and corundum-garnet amphibolites from the Dent peninsula of eastern Sabah (North Borneo) occur as blocks in a slump breccia deposit of late Miocene age. The earliest formed minerals include pyrope-almandine garnet, tschermakitic augite, pargasite, and rutile. Cumulate textures are present in two of the six specimens studied. The earlier fabric has been extensively brecciated and partly replaced by plagioclase, ilmenite, and a fibrous amphibole. The bulk composition and mineralogy of these rocks are similar to those of garnet pyroxenite lenses within ultramafic rocks. Estimated temperature and pressure for the origin of the Sabah garnet pyroxenites is 850??150?? C and 19??4 kbar. ?? 1974 Springer-Verlag.

Morgan, B.A.

1974-01-01

253

Four Terminal Gallium Nitride MOSFETs  

NASA Astrophysics Data System (ADS)

All reported gallium nitride (GaN) transistors to date have been three-terminal devices with source, drain, and gate electrodes. In the case of GaN MOSFETs, this leaves the bulk of the device at a floating potential which can impact device threshold voltage. In more traditional silicon-based MOSFET fabrication a bulk contact can be made on the back side of the silicon wafer. For GaN grown on sapphire substrates, however, this is not possible and an alternate, front-side bulk contact must be investigated. GaN is a III-V, wide band gap semiconductor that as promising material parameters for use in high frequency and high power applications. Possible applications are in the 1 to 10 GHz frequency band and power inverters for next generation grid solid state transformers and inverters. GaN has seen significant academic and commercial research for use in Heterojunction Field Effect Transistors (HFETs). These devices however are depletion-mode, meaning the device is considered "on" at zero gate bias. A MOSFET structure allows for enhancement mode operation, which is normally off. This mode is preferrable in high power applications as the device has lower off-state power consumption and is easier to implement in circuits. Proper surface passivation of seminconductor surface interface states is an important processing step for any device. Preliminary research on surface treatments using GaN wet etches and depletion-mode GaN devices utilizing this process are discussed. Devices pretreated with potassium pursulfate prior to gate dielectric deposition show significant device improvements. This process can be applied to any current GaN FET. Enhancement-mode GaN MOSFETs were fabricated on magnesium doped p-type Wurtzite gallium nitride grown by Metal Organic Chemical Vapor Deposition (MOCVD) on c-plane sapphire substrates. Devices utilized ion implant source and drain which was activated under NH3 overpressure in MOCVD. Also, devices were fabricated with a SiO2 gate dielectric and metal gate. Preliminary devices exhibited high GaN-oxide interface state density, Dit, on the order of 1013 cm-2· eV-1. Additional experiments and device fabrication was focused on improving device performance through optimization of the ion implantation activation anneal as well as incorporation of a bulk p-type ohmic contact and migration to a thicker, lower defect density, HVPE-grown template substrate. The first reported MOSFET on HVPE grown GaN substrates (templates) is reported with peak measured drain current of 1.05 mA/mm and a normalized transconductance of 57 muS/mm. Fabricated devices exhibited large (greater than 1 muA) source-to-drain junction leakage which is attributed to low activated doping density in the MOCVD-grown p-type bulk. MOSFETs fabricated on template substrates show more than twice the measured drain current as similar devices fabricated on traditional MOCVD GaN on sapphire substrates for the same bias conditions. Also, template MOSFETs have decreased gate leakage which allowed for a much greater range of operation. This performance increase is attributed to a more than doubled effective channel mobility on template GaN MOSFETs due to decreased crystal defect scattering when compared to a MOCVD-grown GaN-on-sapphire MOSFET. Fabricated MOSFETs also exhibit decreased interface state density with lower bound of 2.2x1011 cm-2·eV-1 when compared to prelimary MOSFETs. This decrease is associated with the use of a sacrificial oxide cap during source/drain activation. Suggested work for continued research is also presented which includes experiments to improve source/drain ion implantation profile, utilization of selective area growth for the active area, improved n- and p-type ohmic contact resistance and investigation of alternate oxides.

Veety, Matthew Thomas

254

Distribution profile of gadolinium in gadolinium chelate-treated renally-impaired rats: Role of pharmaceutical formulation.  

PubMed

While not acutely toxic, chronic hepatic effect of certain gadolinium chelates (GC), used as contrast agent for magnetic resonance imaging, might represent a risk in renally-impaired patients due to free gadolinium accumulation in the liver. To answer this question, this study investigated the consequences of the presence of small amounts of either a soluble gadolinium salt ("free" Gd) or low-stability chelating impurity in the pharmaceutical solution of gadoteric acid, a macrocyclic GC with high thermodynamic and kinetic stabilities, were investigated in renally-impaired rats. Renal failure was induced by adding 0.75% adenine in the diet for three weeks. The pharmaceutical and commercial solution of gadoteric acid was administered (5 daily intravenous injections of 2.5mmolGd/kg) either alone or after being spiked with either "free" gadolinium (i.e., 0.04% w/v) or low-stability impurity (i.e., 0.06 w/v). Another GC, gadodiamide (low thermodynamic and kinetic stabilities) was given as its commercial solution at a similar dose. Non-chelated gadolinium was tested at two doses (0.005 and 0.01mmolGd/kg) as acetate salt. Gadodiamide induced systemic toxicity (mortality, severe epidermal and dermal lesions) and substantial tissue Gd retention. The addition of very low amounts of "free", non-chelated gadolinium or low thermodynamic stability impurity to the pharmaceutical solution of the thermodynamically stable GC gadoteric acid resulted in substantial capture of metal by the liver, similar to what was observed in "free" gadolinium salt-treated rats. Relaxometry studies strongly suggested the presence of free and soluble gadolinium in the liver. Electron microscopy examinations revealed the presence of free and insoluble gadolinium deposits in hepatocytes and Kupffer cells of rats treated with gadoteric acid solution spiked with low-stability impurity, free gadolinium and gadodiamide, but not in rats treated with the pharmaceutical solution of gadoteric acid. The presence of impurities in the GC pharmaceutical solution may have long-term biological consequences. PMID:25736527

Fretellier, Nathalie; Salhi, Mariem; Schroeder, Josef; Siegmund, Heiko; Chevalier, Thibaut; Bruneval, Patrick; Jestin-Mayer, Gaëlle; Delaloge, Francette; Factor, Cécile; Mayer, Jean-François; Fabicki, Jean-Michel; Robic, Caroline; Bonnemain, Bruno; Idée, Jean-Marc; Corot, Claire

2015-05-25

255

Elastic moduli of pyrope rich garnets  

NASA Astrophysics Data System (ADS)

The elastic properties of minerals depend on its composition, crystal structure, temperature and level of defects. The elastic parameters are important for the interpretation of the structure and composition of the garnet rich family. In present work we have calculated the elastic moduli such as isothermal bulk modulus, Young's modulus and Shear modulus over a wide range of temperature from 300 K to 1000 K by using Birch EOS and Poirrier Tarantola equation of state. The obtained results are compared with the experimental results obtained by measuring the elastic moduli of single crystal. The calculated results show that the logarithmic isothermal EOS does not cooperate well with experimental results.

Pandey, B. K.; Pandey, A. K.; Singh, C. K.

2013-06-01

256

Very high-pressure orogenic garnet peridotites  

PubMed Central

Mantle-derived garnet peridotites are a minor component in many very high-pressure metamorphic terranes that formed during continental subduction and collision. Some of these mantle rocks contain trace amounts of zircon and micrometer-sized inclusions. The constituent minerals exhibit pre- and postsubduction microstructures, including polymorphic transformation and mineral exsolution. Experimental, mineralogical, petrochemical, and geochronological characterizations using novel techniques with high spatial, temporal, and energy resolutions are resulting in unexpected discoveries of new phases, providing better constraints on deep mantle processes. PMID:17519341

Liou, J. G.; Zhang, R. Y.; Ernst, W. G.

2007-01-01

257

Studies of narrow autoionizing resonances in gadolinium  

SciTech Connect

The autoionization (AI) spectrum of gadolinium between the first and second limits has been investigated by triple-resonance excitation with high-resolution cw lasers. A large number of narrow AI resonances have been observed and assigned total angular momentum J values. The resonances are further divided into members of AI Rydberg series converging to the second limit or other ''interloping'' levels. Fine structure in the Rydberg series has been identified and interpreted in terms of Jc j coupling. A number of detailed studies have been performed on the interloping resonances: These include lifetime determination by lineshape analysis, isotope shifts, hyperfine structure, and photoionization saturation parameters. The electronic structure of the interloping levels is discussed in terms of these studies. Linewidths generally decrease with increasing total angular momentum and the J = 7 resonances are extremely narrow with Lorentzian widths ranging from < 1 MHz up to 157 MHz. The strongest resonances are found to have cross-sections of {approx}10-12 cm{sup 2} and photoionization can be saturated with powers available from cw diode lasers.

Bushaw, Bruce A.; Nortershauser, W.; Blaum, K.; Wendt, Klaus

2003-06-30

258

On the formation of surface gallium hydride species in supported gallium catalysts  

NASA Astrophysics Data System (ADS)

Molecular hydrogen is dissociatively adsorbed at elevated temperatures on Ga3+ surface sites of supported gallium catalysts. Both the amount of hydrogen absorbed by the catalysts and Gasbnd H vibration frequencies of surface gallium hydrides formed upon dissociative hydrogen adsorption depend on the nature of the support. The surface sites, active in the dissociative adsorption of hydrogen, most probably are Ga3+ cations bonded to the support surface.

Serykh, Alexander I.

2012-10-01

259

Polyphase growth of garnet in eclogite from the Hong'an orogen: Constraints from garnet zoning and phase equilibrium  

NASA Astrophysics Data System (ADS)

Major and trace element profiles as well as mineral inclusions were analyzed in garnets from massive and foliated eclogites from the low-T/high-P eclogite-facies zone in the Hong'an orogen, China. Garnets in the two types of eclogites show different core-rim zoning and mineral inclusions. At least two stages of garnet growth are evident for most garnet grains. Garnets in the massive eclogite contain abundant mineral inclusions such as quartz, chlorite, amphibole, rutile and phengite in cores, but only a few mineral inclusions such as quartz, rutile and titanite in rims. These garnet grains exhibit increasing MgO but decreasing CaO and REE contents from core to rim. Together with pseudosection calculations it is suggested that hydrous minerals such as chlorite, epidote and amphibole were probably the major reactants for the growth of garnet cores during prograde subduction, whereas the growth of garnet rims involves amphibole breakdown and/or dissolution of previously formed garnet. On the other hand, garnets in the foliated eclogite exhibit nearly constant MgO, decreasing MnO but increasing CaO and heavy REE contents (HREE) from core to rim. Along with pseudosection calculations it is inferred that the decomposition of epidote would consistently contribute to the growth of garnet core and rim. This is also supported by epidote zoning in matrix, with the occurrence of low-jadeite omphacite inclusions in the core and a few rutile inclusions in the rim. The enrichment of light REE (LREE) and depletion of HREE in the epidote rim relative to the core indicate that the epidote rim was recrystallized in equilibrium with the garnet rims. For protolith compositions, the foliated eclogite shows higher SiO2, Na2O, K2O and MgO contents but lower Al2O3, Fe2O3 and TiO2 contents than the massive eclogite. Along with phase equilibrium modeling, it is concluded that the differences in the protolith compositions of eclogites primarily dictate the differences in the garnet zoning patterns and the mineral assemblages of matrix and inclusions. The decomposition of hydrous minerals such as chlorite, amphibole and epidote is necessary for garnet growth during subduction-zone metamorphism.

Zhou, Li-Gang; Xia, Qiong-Xia; Zheng, Yong-Fei; Hu, Zhaochu

2014-10-01

260

PARTITIONING OF GADOLINIUM IN THE CHEMICAL PROCESSING CELL  

SciTech Connect

A combination of short-term beaker tests and longer-duration Sludge Receipt and Adjustment Tank (SRAT) simulations were performed to investigate the relative partitioning behaviors of gadolinium and iron under conditions applicable to the Chemical Processing Cell (CPC). The testing was performed utilizing non-radioactive simple Fe-Gd slurries, non-radioactive Sludge Batch 6 simulant slurries, and a radioactive real-waste slurry representative of Sludge Batch 7 material. The testing focused on the following range of conditions: (a) Fe:Gd ratios of 25-100; (b) pH values of 2-6; (c) acidification via addition of nitric, formic, and glycolic acids; (d) temperatures of {approx}93 C and {approx}22 C; and (e) oxalate concentrations of <100 mg/kg and {approx}10,000 mg/kg. The purpose of the testing was to provide data for assessing the potential use of gadolinium as a supplemental neutron poison when dispositioning excess plutonium. Understanding of the partitioning behavior of gadolinium in the CPC was the first step in assessing gadolinium's potential applicability. Significant fractions of gadolinium partitioned to the liquid-phase at pH values of 4.0 and below, regardless of the Fe:Gd ratio. In SRAT simulations targeting nitric and formic acid additions of 150% acid stoichiometry, the pH dropped to a minimum of 3.5-4.0, and the maximum fractions of gadolinium and iron partitioning to solution were both {approx}20%. In contrast, in a SRAT simulation utilizing a nitric and formic acid addition under atypical conditions (due to an anomalously low insoluble solids content), the pH dropped to a minimum of 3.7, and the maximum fractions of gadolinium and iron partitioning to solution were {approx}60% and {approx}70%, respectively. When glycolic acid was used in combination with nitric and formic acids at 100% acid stoichiometry, the pH dropped to a minimum of 3.6-4.0, and the maximum fractions of gadolinium and iron partitioning to solution were 60-80% and 3-5%, respectively. Thus, the presence of glycolic acid increased dissolution of gadolinium, but decreased dissolution of iron. In beaker tests, the fractions of gadolinium partitioning to solution were all less than the minimum detection limits at pH 6, on the order of a few percent at pH 4, and ranging from 70-90% at pH 2. In contrast, the fractions of iron partitioning to solution were all less than the minimum detection limits at pH 6, {le} 0.04% at pH 4, and {le} 0.9% at pH 2. A possible explanation for the small magnitude of these fractions (as compared to the fractions observed in the SRAT simulations) was incomplete equilibrium, due to the short duration (30 minutes) of the beaker tests. As demonstrated by the SRAT simulations, the typical partitioning equilibration time was on the order of hours. The Fe:Gd ratio appeared to impact the extent of liquid-phase conditions under certain conditions, although the exact relationship was not clear. Temperature impacts on the liquid-phase gadolinium concentrations were modest, with liquid phase concentrations typically increasing about 25% as temperatures rose from {approx}22 C to {approx}93 C. The presence of high concentrations of oxalate did not appear to change the liquid-phase gadolinium concentrations - however, it did increase the liquid-phase iron concentrations (from being undetectable to being detectable but still minor). Additional gadolinium partitioning testing is recommended. Of greatest usefulness will be SRAT simulations focusing on a wider range of acid addition scenarios and alternate sludge compositions, particularly those specific to future sludge batches where addition of excess plutonium is being considered.

Reboul, S.; Best, D.; Stone, M.; Click, D.

2011-04-27

261

Synchrotron X-Ray Fluorescence Microscopy of Gallium in Bladder Tissue following Gallium Maltolate Administration during Urinary Tract Infection  

PubMed Central

A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 ?g/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli. PMID:23877680

Sampieri, Francesca; Chirino, Manuel; Hamilton, Don L.; Blyth, Robert I. R.; Sham, Tsun-Kong; Dowling, Patricia M.; Thompson, Julie

2013-01-01

262

TUDE DILATOMTRIQUE DES COEFFICIENTS PIZOLECTRIQUES ET LECTROSTRICTIFS DU MOLYBDATE DE GADOLINIUM  

E-print Network

GADOLINIUM AU VOISINAGE DE LA TRANSITION FERROÉLASTIQUE E. DU TRÉMOLET DE LACHEISSERIE Laboratoire de'un cristal monodoinaine de molybdate de gadolinium (GMO). Nos mesures ont donne la valeur des coefficients pi

Paris-Sud XI, Université de

263

Cardiac Imaging Dark Regions of No-Reflow on Late Gadolinium  

E-print Network

Cardiac Imaging Dark Regions of No-Reflow on Late Gadolinium Enhancement Magnetic Resonance Imaging on late gadolinium enhancement (LGE) mag- netic resonance imaging (MRI) immediately post-ablation (IPA

Prastawa, Marcel

264

Research paper Using garnet to constrain the duration and rate of water-releasing metamorphic  

E-print Network

Research paper Using garnet to constrain the duration and rate of water-releasing metamorphic. Mezger Keywords: Garnet Dehydration Subduction Sifnos Cyclades Sm­Nd We present a method to reconstruct the dehydration flux associated with garnet-forming reactions during subduction. Garnet-bearing blueschists from

Baxter, Ethan F.

265

Accommodation of Uranium into the Garnet Structure Sergey V.Yudintsev1  

E-print Network

Accommodation of Uranium into the Garnet Structure Sergey V.Yudintsev1 , Marya I. Lapina1 is garnet-type phases of general formula AVIII 3BVI 2[XO4]3. To determine the isomorphic capacity of garnet performed in air medium at 1400 ­ 1500 °C and 1 atm. The garnets have high capacity for Gd and Zr, while in

Utsunomiya, Satoshi

266

High Pressure Solution Growth of Gallium Nitride  

NASA Astrophysics Data System (ADS)

State-of-the-art high pressure solution (HPS) growth of gallium nitride is presented in this chapter. The spontaneous crystallization and seeded growth are described in detail from the technological point of view. Two classes of pressure-grown crystals and their use as substrates for blue laser diodes (LDs) are demonstrated.

Bo?kowski, Michal; Str?k, Pawel; Grzegory, Izabella; Porowski, Sylwester

267

Thermodynamic binding constants for gallium transferrin  

SciTech Connect

Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga/sup 3 +/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants. Therefore, thermodynamic binding constants for gallium complexation at the two specific metal binding sites of human serum transferrin at pH 7.4 and 5 mM NaHCO/sub 3/ have been determined by UV difference spectroscopy. The conditional constants calculated for 27 mM NaHCO/sub 3/ are log K/sub 1/* = 20.3 and log K/sub 2/* = 19.3. These results are discussed in relation to the thermodynamics of transferrin binding of Fe/sup 3 +/ and to previous reports on gallium binding. The strength of transferrin complexation is also compared to that of a series of low molecular weight ligands by using calculated pM values (pM = -log (Ga(H/sub 2/O)/sub 6/)) to express the effective binding strength at pH 7.4.

Harris, W.R.; Pecoraro, V.L.

1983-01-18

268

Extrapulmonary localization of gallium in sarcoidosis  

SciTech Connect

This paper describes the spectrum of extrapulmonary localization of gallium in patients with sarcoidosis. The usefulness of Ga-67 scintiscans in detecting clinically occult lesions, in directing clinicians to accessible sites for biopsy, and in following the course of extrapulmonary sites of involvement with therapy is emphasized.

Rohatgi, P.K.; Singh, R.; Vieras, F.

1987-01-01

269

A Gallium Multiphase Equation of State  

NASA Astrophysics Data System (ADS)

A new SESAME multiphase gallium equation of state (EOS) has been developed. The equation of state includes two of the solid phases (Ga I, Ga III) and a fluid phase. The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We will also explore refreezing via isentropic release and compression.

Crockett, Scott; Greeff, Carl

2009-06-01

270

Gallium nitride junction field-effect transistor  

DOEpatents

An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

Zolper, John C. (Albuquerque, NM); Shul, Randy J. (Albuquerque, NM)

1999-01-01

271

Gallium nitride junction field-effect transistor  

DOEpatents

An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

Zolper, J.C.; Shul, R.J.

1999-02-02

272

Development of gallium aluminum phosphide electroluminescent diodes  

NASA Technical Reports Server (NTRS)

Work done on the development of gallium aluminum phosphide alloys for electroluminescent light sources is described. The preparation of this wide band gap semiconductor alloy, its physical properties (particularly the band structure, the electrical characteristics, and the light emitting properties) and work done on the fabrication of diode structures from these alloys are broadly covered.

Chicotka, R. J.; Lorenz, M. R.; Nethercot, A. H.; Pettit, G. D.

1972-01-01

273

Gallium-positive Lyme disease myocarditis  

SciTech Connect

In the course of a work-up for fever of unknown origin associated with intermittent arrhythmias, a gallium scan was performed which revealed diffuse myocardial uptake. The diagnosis of Lyme disease myocarditis subsequently was confirmed by serologic titers. One month following recovery from the acute illness, the abnormal myocardial uptake completely resolved.

Alpert, L.I.; Welch, P.; Fisher, N.

1985-09-01

274

Gallium Electromagnetic (GEM) Thruster Performance Measurements  

NASA Technical Reports Server (NTRS)

Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

2009-01-01

275

Anisotropy of the magnetic susceptibility of gallium  

USGS Publications Warehouse

The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25??C. The following anisotropic diamagnetic susceptibilities were found: a axis (-0.119??0. 001)??10-6 emu/g, b axis (-0.416??0.002)??10 -6 emu/g, and c axis (-0.229??0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (-0.257??0.003)??10-6 emu/g at 25??C, and (-0.299??0.003)??10-6 emu/g at -196??C. The susceptibility of liquid gallium was (0.0031??0.001) ??10-6 emu/g at 30??C and 100??C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi-energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state. ?? 1960 The American Institute of Physics.

Pankey, T., Jr.

1960-01-01

276

49 CFR 173.162 - Gallium.  

Code of Federal Regulations, 2014 CFR

...performance level for transportation by aircraft, and...transport gallium at low temperatures in order...impact resistance at the low temperatures of the...permit the release of carbon dioxide gas. (c...this subchapter. For transportation by aircraft, such...

2014-10-01

277

49 CFR 173.162 - Gallium.  

Code of Federal Regulations, 2013 CFR

...performance level for transportation by aircraft, and...transport gallium at low temperatures in order...impact resistance at the low temperatures of the...permit the release of carbon dioxide gas. (c...this subchapter. For transportation by aircraft, such...

2013-10-01

278

Spectra of bigyrotropic magnetic photonic crystals  

Microsoft Academic Search

We calculated the photonic band gap spectra of a one-dimensional magnetic photonic crystal made of alternating layers of bigyrotropic magnetic yttrium-iron garnet and nonmagnetic gadolinium gallium garnet. The forbidden regimes or band gaps in the electromagnetic wave spectrum were numerically obtained for the transversal magneto-optical configuration and compared with those for the polar and longitudinal magneto-optical configurations.

I. L. Lyubchanskii; N. N. Dadoenkova; M. I. Lyubchanskii; E. A. Shapovalov; A. Lakhtakia; T. H. M. Rasing

2004-01-01

279

Experiment and Simulations of Ablatively Driven Shock Waves in Gadolinium Metal  

Microsoft Academic Search

Lanthanides are fascinating metals to study because they exhibit physical properties that vary with 4f occupancy. Specifically Gadolinium is interesting because there are multiple structural phase transitions accessible below 100 GPa. Experiments were performed on Gadolinium metal in which shock waves were driven in Gadolinium foils through direct laser ablation. The velocity at the opposite surface of the drive beam

Richard Kraus; Eric Loomis; Shengnian Luo; Achim Seifter; Damian Swift

2007-01-01

280

Occurrence du gadolinium anthropique dans les eaux destines la consommation humaine , A. GARNIER(1)  

E-print Network

Occurrence du gadolinium anthropique dans les eaux destinées à la consommation humaine JS. PY(1 Leclerc, 94701 MAISONS-ALFORT Mots clés : Gadolinium, eaux de consommation, médicament, Gd anthropique en gadolinium anthropique dans les eaux brutes et les eaux traitées de 285 sites français. L

Paris-Sud XI, Université de

281

PHYSICAL REVIEW B 86, 075433 (2012) Effect of gadolinium adatoms on the transport properties of graphene  

E-print Network

PHYSICAL REVIEW B 86, 075433 (2012) Effect of gadolinium adatoms on the transport properties of graphene doped with gadolinium (Gd) adatoms have been measured. The gate voltage dependence on graphene electrical transport of dilute quantities of gadolinium (Gd). Gd (4f 7 5d1 6s2 ) is a rare

Hellman, Frances

2012-01-01

282

Neutron Capture and Total Cross-Section Measurements and Resonance Parameters of Gadolinium  

E-print Network

Neutron Capture and Total Cross-Section Measurements and Resonance Parameters of Gadolinium G to the understanding of gadolinium cross sections is presented, particularly above 180 eV where the ENDF resolved sections of gadolinium accurately. Gado- linium has the highest thermal cross section of any nat- ural

Danon, Yaron

283

QUATION MAGNTIQUE D'TAT DU GADOLINIUM AU VOISINAGE DU POINT DE CURIE  

E-print Network

319 ÉQUATION MAGNÉTIQUE D'ÉTAT DU GADOLINIUM AU VOISINAGE DU POINT DE CURIE Par M. N. DESCHIZEAUX'étude expérimentale de la variation d'aimantation d'un monocristal de gadolinium en fonction du champ et de la temperature experimental study of a gadolinium monocristal near the Curie point we determine the critical

Paris-Sud XI, Université de

284

Internalization pathways into cancer cells of gadolinium-based radiosensitizing nanoparticles Wael Rima a  

E-print Network

Internalization pathways into cancer cells of gadolinium-based radiosensitizing nanoparticles Wael Rima a , Lucie elimination, therapeutic potential and contrast properties. In this context, we developed sub-5 nm gadolinium towards a particle-assisted radiotherapy using lower radiation doses. Keywords: gadolinium

Boyer, Edmond

285

Chitosan modified with gadolinium diethylenetriaminepentaacetic acid for magnetic resonance imaging of DNA/chitosan nanoparticles  

E-print Network

Chitosan modified with gadolinium diethylenetriaminepentaacetic acid for magnetic resonance imaging online 22 January 2010 Keywords: Chitosan DTPA Gadolinium Covalent bonding DNA pEGFPLuc Gene delivery STEM SEM ITC NMR a b s t r a c t We have prepared chitosan (CH)­gadolinium (Gd

Buschmann, Michael

286

Spin-wave-mediated quantum corrections to the conductivity of thin ferromagnetic films of gadolinium  

E-print Network

of gadolinium Rajiv Misra, Arthur F. Hebard,* and Khandker A. Muttalib Department of Physics, University to the conductivity of thin ferromagnetic gadolinium films. In situ magnetotransport measurements were performed is gadolinium Gd , with a spin-wave gap of about 30 mK and a Curie temperature of 293 K.6,7 We have carried out

Muttalib, Khandker

287

Gallium 67 scintigraphy in glomerular disease  

SciTech Connect

To evaluate the diagnostic usefulness of gallium 67 scintigraphy in glomerular disease, 45 patients with various glomerulopathies, excluding lupus nephritis and renal vasculitis, were studied. Persistent renal visualization 48 hours after the gallium injection, a positive scintigram, was graded as + (less than), ++ (equal to), and +++ (greater than) the hepatic uptake. Positive scintigrams were seen in ten of 16 cases of focal segmental glomerulosclerosis, six of 11 cases of proliferative glomerulonephritis, and one case of minimal change, and one of two cases of membranous nephropathy; also in three of six cases of sickle glomerulopathy, two cases of diabetic neuropathy, one of two cases of amyloidosis, and one case of mild chronic allograft rejection. The 25 patients with positive scans were younger than the 20 with negative scans (31 +/- 12 v 42 +/- 17 years; P less than 0.01), and exhibited greater proteinuria (8.19 +/- 7.96 v 2.9 +/- 2.3 S/d; P less than 0.01) and lower serum creatinine values (2 +/- 2 v 4.1 +/- 2.8 mg/dL; P less than 0.01). The amount of proteinuria correlated directly with the intensity grade of the gallium image (P less than 0.02), but there was no correlation between the biopsy diagnosis and the outcome of the gallium scan. It was concluded that gallium scintigraphy is not useful in the differential diagnosis of the glomerular diseases under discussion. Younger patients with good renal function and heavy proteinuria are likely to have a positive renal scintigram regardless of the underlying glomerulopathy.

Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.; Rhee, H.L.; Dunea, G.

1988-12-01

288

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2010 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2010-07-01

289

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2014 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2014-07-01

290

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2013 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2013-07-01

291

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2012 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2012-07-01

292

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2011 CFR

...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

2011-07-01

293

Experimental investigation and application of garnet granulite equilibria  

Microsoft Academic Search

Two mineralogic geobarometers based on the assemblages olivine-plagioclase-garnet and orthopyroxeneplagioclase-garnet-quartz have been calibrated from the reaction (1) fayalite+anorthite?garnet (Gr1Alm2). The reaction boundary has been determined to within 0.2 kbar using piston-cylinder apparatus. It is located at 4.7, 5.1, 5.5, 5.8, 6.2, 6.6, and 7.0 kbar at 750, 800, 850, 900, 950, 1,000, and 1,050° C, respectively. Summation of ?G for

S. R. Bohlen; V. J. Wall; A. L. Boettcher

1983-01-01

294

Thermodynamic properties of almandine-grossular garnet solid solutions  

Microsoft Academic Search

The mixing properties of Fe3Al2Si3O12-Ca3Al2Si3O12 garnet solid solutions have been studied in the temperature range 850–1100° C. The experimental method involves measuring the composition of garnet in equilibrium with an assemblage in which the activity of the Ca3Al2Si3O12 component is fixed. Experiments on the assemblage garnet solid solution, anorthite, Al2SiO5 polymorph and quartz at known pressure and temperature fix the

G. Cressey; R. Schmid; B. J. Wood

1978-01-01

295

A possible role for garnet pyroxenite in the origin of the “garnet signature” in MORB  

Microsoft Academic Search

Geochemical data have been interpreted as requiring that a significant fraction of the melting in MORB source regions takes\\u000a place in the garnet peridotite field, an inference that places the onset of melting at ?80?km. However, if melting begins\\u000a at such great depths, most models for melting of the suboceanic mantle predict substantially more melting than that required\\u000a to produce

Marc M. Hirschmann; Edward M. Stolper

1996-01-01

296

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2007. One company in Utah  

E-print Network

as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $11 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about the gallium recycler-refiner in Utah and a gallium recycler in the United Kingdom jointly purchased

297

Vacuum annealed cerium-substituted yttrium iron garnet films on non-garnet substrates for integrated optical circuits  

NASA Astrophysics Data System (ADS)

Polycrystalline cerium-substituted yttrium iron garnet (CeYIG) showing large Faraday rotation (FR) in the near-IR region was grown on non-garnet (synthetic fused silica, Si, and Si-on-insulator) substrates by sputtering followed by thermal annealing in vacuum. The FR of the films is comparable to the single crystal value. Structural characterization, magnetic properties, refractive index, extinction coefficient, surface topography, and FR vs. wavelength were measured and the magnetooptical figure of merit was compared with that of CeYIG films on garnet substrates.

Goto, Taichi; Eto, Yu; Kobayashi, Keiichi; Haga, Yoji; Inoue, Mitsuteru; Ross, C. A.

2013-05-01

298

Vacuum annealed cerium-substituted yttrium iron garnet films on non-garnet substrates for integrated optical circuits  

SciTech Connect

Polycrystalline cerium-substituted yttrium iron garnet (CeYIG) showing large Faraday rotation (FR) in the near-IR region was grown on non-garnet (synthetic fused silica, Si, and Si-on-insulator) substrates by sputtering followed by thermal annealing in vacuum. The FR of the films is comparable to the single crystal value. Structural characterization, magnetic properties, refractive index, extinction coefficient, surface topography, and FR vs. wavelength were measured and the magnetooptical figure of merit was compared with that of CeYIG films on garnet substrates.

Goto, Taichi; Ross, C. A. [Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Eto, Yu; Kobayashi, Keiichi; Haga, Yoji; Inoue, Mitsuteru [Toyohashi University of Technology, Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan)

2013-05-07

299

Garnet melt viscosity, surface tension and drainage  

NASA Technical Reports Server (NTRS)

Good surface morphology and layer uniformity of LPE-grown Bi YIG films are favored by fast melt removal after growth. Three flux modifying oxides: MoO3, V2O3, and WO3 are compared with respect to their effect on viscosity, surface tension and melt drainage. All three oxides increased the viscosities of Bi-garnet melts, but the viscosities and drainage times of V2O3 and MoO3 modified melts were smaller than those of WO3 modified melts. The liquid-gas surface tension was found to be temperature independent. The drainage process was strongly temperature dependent, 40 to 60 kcal/mol, whereas the viscosities of melts had activation energies of 11 to 16 kcal/mol. Contact angles of 16 + or - 2 deg were measured on frozen melt drops.

Luther, L. C.

1986-01-01

300

An empirical garnet (YAG) – xenotime thermometer  

Microsoft Academic Search

A pronounced negative correlation between the yttrium concentration in garnet ([Y]Grt) and temperature has been observed in xenotime (YPO4)-bearing metapelites from central New England, USA. The [Y]Grt decreases roughly two orders of magnitude (?5500 to less than 100?ppm Y) over a 150?C interval. A regression of ln([Y]Grt) against estimated reciprocal temperature yields the following relationship:\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a with R2?=?0.97. The decrease in

Joseph M. Pyle; Frank S. Spear

2000-01-01

301

Inflammatory pseudotumor: A gallium-avid mobile mesenteric mass  

SciTech Connect

An 8-yr-old boy with a 1-mo history of culture-negative fever and anemia underwent gallium, ultrasound, and computed tomography studies as part of the evaluation of a fever of unknown origin. These studies revealed a mobile gallium-avid solid abdominal mass subsequently proven to be an inflammatory pseudotumor of the mesentery, a rare benign mass. This report documents the gallium-avid nature of this rare lesion and discusses associated characteristic clinical, pathologic, and radiographic features.

Auringer, S.T.; Scott, M.D.; Sumner, T.E. (Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC (USA))

1991-08-01

302

Thermochromism in yttrium iron garnet compounds.  

PubMed

Polycrystalline yttrium iron garnet (Y3Fe5O12, hereafter labeled YIG) has been synthesized by solid-state reaction, characterized by X-ray diffraction, Mössbauer spectroscopy, and UV-vis-NIR diffuse reflectance spectroscopy, and its optical properties from room temperature (RT) to 300 °C are discussed. Namely, its greenish color at RT is assigned to an O(2-) ? Fe(3+) ligand-to-metal charge transfer at 2.57 eV coupled with d-d transitions peaking at 1.35 and 2.04 eV. When the temperature is raised, YIG displays a marked thermochromic effect; i.e., the color changes continuously from greenish to brownish, which offers opportunities for potential application as a temperature indicator for everyday uses. The origin of the observed thermochromism is assigned to a gradual red shift of the ligand-to-metal charge transfer with temperature while the positioning in energy of the d-d transitions is almost unaltered. Attempts to achieve more saturated colors via doping (e.g., Al(3+), Ga(3+), Mn(3+), ...) remained unsuccessful except for chromium. Indeed, Y3Fe5O12:Cr samples exhibit at RT the same color than the undoped garnet at 200 °C. The introduction of Cr(3+) ions strongly impacts the color of the Y3Fe5O12 parent either by an inductive effect or, more probably, by a direct effect on the electronic structure of the undoped material with formation of a midgap state. PMID:25382733

Serier-Brault, Hélène; Thibault, Lucile; Legrain, Magalie; Deniard, Philippe; Rocquefelte, Xavier; Leone, Philippe; Perillon, Jean-Luc; Le Bris, Stéphanie; Waku, Jean; Jobic, Stéphane

2014-12-01

303

Terbium photoluminescence in yttrium aluminum garnet xerogels  

SciTech Connect

Based on a colloidal solution containing terbium, yttrium, and aluminum metal ions, a powder was synthesized and films of terbium-doped yttrium aluminum garnet Tb{sub 0.15}Y{sub 2.85}Al{sub 5}O{sub 12} were grown on single-crystal silicon and porous anodic alumina. Annealing of the sample in a temperature range from 200-1100 deg. C results in an increase in the photoluminescence intensity in the wavelength range from 480-640 nm, which is caused by Tb{sup 3+} ion intra-atomic transitions {sup 5}D{sub 4}{sup {yields}}{sup 7}F{sub j} (j = 3, 4, 5, 6). Annealing at 900 deg. C and higher temperatures gives rise to low-intensity photoluminescence bands in the region of 667 and 681 nm, which correspond to transitions {sup 5}D{sub 4}{sup {yields}}{sup 7}F{sub 0}, {sup 5}D{sub 4}{sup {yields}}{sup 7}F{sub 1}, and room-temperature Stark term splitting, which suggests the existence of a crystalline environment of Tb{sup 3+} ions. The FWHM of spectral lines in the region of 543 nm decreases from {approx}10 to {approx}(2-3) nm as the xerogel annealing temperature is increased from 700 to 900 deg. C and higher. Three bands with maxima at 280, 330, and 376 nm, which correspond to Tb{sup 3+} ion transitions {sup 7}F{sub 6}{sup {yields}}{sup 5}I{sub 8}, {sup 5}L{sub 6}, {sup 5}G{sub 6}, {sup 5}D{sub 3}, are observed in the photoluminescence excitation spectra of the studied structures for the emission wavelength at 543 nm. X-ray diffraction detected the formation of a crystalline phase for a terbium-doped yttrium aluminum garnet powder after annealing at 1100 deg. C.

Maliarevich, G. K.; Gaponenko, N. V., E-mail: nik@nano.bsuir.edu.ru; Mudryi, A. V. [Belarussian State University of Informatics and Radioelectronics (Belarus); Drozdov, Yu. N.; Stepikhova, M. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Stepanova, E. A. [Belarussian State University of Informatics and Radioelectronics (Belarus)

2009-02-15

304

Doped iron garnet materials for magnetic photonic crystals  

Microsoft Academic Search

We have established a set of technologies for the deposition and annealing of magneto-optic garnets for use in photonic crystals. Devices for sensing magnetic fields and polarisation control using reconfigurable photonic crystals are being developed.

Mikhail Vasiliev; Kamal Alameh; Viatcheslav Kotov

2008-01-01

305

Magneto-Optical Experiments on Rare Earth Garnet Films.  

ERIC Educational Resources Information Center

Describes experiments in which inexpensive or standard laboratory equipment is used to measure several macroscopic magnetic properties of thin rare earth garnet films used in the manufacture of magnetic bubble devices. (Author/CS)

Tanner, B. K.

1980-01-01

306

Optical and magneto-optic Kerr effects of magnesium-bismuth, nickel-manganese-gallium, and gadolinium-silicon-germanium  

NASA Astrophysics Data System (ADS)

The magneto-optic Kerr angle spectrum of a single crystal of MnBi was measured at room temperature and also calculated with the TB-LMTO methods including the spin-orbit interaction. Previously measured Kerr spectra with thin films had two negative peaks, except for one film grown in ultra high vacuum. The later had a first peak and a shoulder at the second peak position, indicating the second originated from oxygen in the other films. Comparing first-principles calculations and previous thin-film results with our single crystal data indicated that the second peak originated from the combination of a weak intrinsic MnBi peak and oxygen in the sample. The complex dielectric constants and magneto-optic Kerr spectra of electro-polished (100), (110), and (111) planes Ni2MnGa were measured. Also optical and magneto-optical spectra were calculated with the TB-LMTO methods including the spin-orbit interaction. Measured Kerr and optical spectra with three surfaces at room temperature had the same peak positions, but different amplitudes. The difference between (100) and (110) surfaces are probably due to the polishing process, not intrinsic bulk properties. Angle-dependent reflectance difference spectroscopy of (100), (010), and (001) planes Gd5Si2Ge2, and (100) plane Tb5Si2.2Ge1.8, which are optically anisotropic materials, were measured with the Kerr spectrometer by rotating the samples. The replacing the rare earth Gd to Tb atoms and 10% changing Ge to Si atoms did not change the spectra much. The complex dielectric constants of (100) and (001) planes Gd5Si2Ge2 were measured by the spectroscopic ellipsometer. Two reflectance differences, measured by the Kerr spectrometer at near normal incidence and converted from the dielectric constants measured by ellipsometer at oblique incidence, agreed well.

Park, Joong-Mok

307

Limiting pump intensity for sulfur-doped gallium selenide crystals  

NASA Astrophysics Data System (ADS)

High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium?selenide).

Guo, J.; Li, D.-J.; Xie, J.-J.; Zhang, L.-M.; Feng, Z.-S.; Andreev, Yu M.; Kokh, K. A.; Lanskii, G. V.; Potekaev, A. I.; Shaiduko, A. V.; Svetlichnyi, V. A.

2014-05-01

308

Sublattice Magnetization in Yttrium and Lutetium Iron Garnets  

Microsoft Academic Search

The temperature dependence of the a and d sublattice magnetization in yttrium iron garnet (YIG) and lutetium iron garnet (LuIG) has been observed by means of the NMR of Fe57 between 4 and 373°K, with special emphasis on the temperature range where the spin-wave theory is expected to hold. An analysis of these results in terms of the spin reversals

Roland Gonano; Earle Hunt; Horst Meyer

1967-01-01

309

Geochemistry of transition elements in garnet lherzolite nodules in kimberlites  

Microsoft Academic Search

The clinopyroxenes and garnets from garnet lherzolite nodules in kimberlites were analyzed for the major and trace elements (Sc, Ti, V, Cr, Mn, Co, Sr, and Zr) with the secondary ion mass spectrometry (SIMS) techniques using an ion-microprobe. The concentration ranges for clinopyroxenes are: 12–90 ppm Sc, 60–2540 ppm Ti, 110–350 ppm V, 2400 ppm-1.68% Cr, 470–1100 ppm Mn, 18–70

N. Shimizu; C. J. Allègre

1978-01-01

310

Garnet--An Essential Industrial Mineral and January's Birthstone  

USGS Publications Warehouse

Garnet is one of the most common minerals in the world. Occurring in almost any color, it is most widely known for its beauty as a gem stone. Because of its hardness and other properties, garnet is also an essential industrial mineral used in abrasive products, non-slip surfaces, and filtration. To help manage our Nation's resources of such essential minerals, the U.S. Geological Survey (USGS) provides crucial data and scientific information to industry, policymakers, and the public.

Evans, James G.; Moyle, Phillip R.; Frank, David G.; Olson, Donald W.

2006-01-01

311

Geobarometry and geothermometry of plagioclase-biotite-garnet-muscovite assemblages  

Microsoft Academic Search

The assemblage, plagioclase-biotite-garnet-muscovite is widespread in garnet to lower sillimanite zone metasedimentary rocks. The equilibria, (1) pyr+gr+mu=3an+phl and (2) alm+gr+mu=3an+ann, involve a change in Al coordination from 6 to 4 and in Mg-Fe coordination from 8 to 6 and should be strongly pressure dependent. Using an ionic solution model we can define solid activity products for (1) and (2). Using

Edward D. Ghent; Mavis Z. Stout

1981-01-01

312

Garnet polycrystals and the significance of clustered crystallization  

NASA Astrophysics Data System (ADS)

Polycrystalline garnets are common in metamorphic rocks and may form as a result of close spacing of nuclei (if clustering is early) or impingement of larger grains (if clustering occurs later in the growth history). The timing of clustering relative to garnet growth is relevant to understanding the formation and evolution of porphyroblasts and evaluating the significance (if any) of clustering. Electron backscattered diffraction (EBSD) analysis of garnet-bearing metamorphic rocks reveals the presence of polycrystalline garnet in nine localities examined in this study: the northern Appalachians (Vermont, Maine, New York, USA); North American Cordillera (North Cascades Range, Washington; Snake Range, Nevada, USA); western Rocky Mountains (British Columbia, Canada); southern Menderes Massif (Turkey); Santander Massif (Colombia); and the Sanandaj-Sirjan zone (Hamadan, Iran). In some samples, polycrystals comprise ~20-30% of garnets analyzed, and chemical and textural evidence suggests that early coalescence of garnet polycrystals is common. Some early-coalescing polycrystals exhibit growth zoning that is concentric about the geometric center of the polycrystal. In thin section, these garnets may be undetectable as polycrystals based on morphology or zoning. In some polycrystals, zoning is unrelated to the location of internal grain boundaries; in others, Fe-Mn-Mg zoning has a different pattern than that of Ca; zoning patterns may vary on the scale of a single thin section. In addition, some polycrystals are characterized by high-angle misorientation boundaries that may be in special (non-random) orientations, an observation that indicates that these polycrystals are not random clusters of grains. The presence of internal grain boundaries may affect diffusion pathways and length scales, and may facilitate communication of porphyroblast interiors with matrix phases, thereby influencing reaction history of the rock and the composition/zoning of garnet.

Whitney, Donna L.; Seaton, Nicholas C. A.

2010-10-01

313

Photonuclear Reaction Cross Sections for Gallium Isotopes  

E-print Network

The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron ({\\gamma},xn)) and proton (photo-proton ({\\gamma},xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. According to the results, we have seen that the calculations are in harmony in the limited literature values. Furthermore, the pre-equilibrium and compound process contributions to the total cross-section have been investigated.

Serkan Akkoyun; Tuncay Bayram

2014-09-08

314

Researches on Laser Isotope Separation of Gadolinium and Boron  

Microsoft Academic Search

Laser isotope separation experiments of Gd and B by atomic and molecular methods, respectively, have been per- formed. Gadolinium-157 was selectively photoionized by means of three linearly polarized dye lasers, the excitation process of which is based on the polarization selection rules. The effect of magnetic field on isotopic selectivity was discussed. 10BCl3 was selectively photodissociated through IR multiphoton dissociation

Yasukazu IZAWA; Changhwan LIM; Hiroharu OHARA; Hideaki NIKI; Masaki HASHIDA

2002-01-01

315

Researches on Laser Isotope Separation of Gadolinium and Boron  

Microsoft Academic Search

Laser isotope separation experiments of Gd and B by atomic and molecular methods, respectively, have been performed. Gadolinium-157 was selectively photoionized by means of three linearly polarized dye lasers, the excitation process of which is based on the polarization selection rules. The effect of magnetic field on isotopic selectivity was discussed. BCl3 was selectively photodissociated through IR multiphoton dissociation by

Yasukazu IZAWA; Changhwan LIM; Hiroharu OHARA; Hideaki NIKI; Masaki HASHIDA

2002-01-01

316

Gadolinium in water Cherenkov detectors improves detection of supernova ?e  

NASA Astrophysics Data System (ADS)

Detecting supernova ?e is essential for testing supernova and neutrino physics, but the yields are small and the backgrounds from other channels large, e.g., ˜ 102 and ˜ 104 events, respectively, in Super-Kamiokande. We develop a new way to isolate supernova ?e, using gadolinium-loaded water Cherenkov detectors. The forward-peaked nature of ?e+e-??e+e- allows an angular cut that contains the majority of events. Even in a narrow cone, near-isotropic inverse beta events, ?¯e+p?e++n, are a large background. With neutron detection by radiative capture on gadolinium, these background events can be individually identified with high efficiency. The remaining backgrounds are smaller and can be measured separately, so they can be statistically subtracted. Super-Kamiokande with gadolinium could measure the total and average energy of supernova ?e with ˜ 20% precision or better each (90% C.L.). Hyper-Kamiokande with gadolinium could improve this by a factor of ˜ 5. This precision will allow powerful tests of supernova neutrino emission, neutrino mixing, and exotic physics. Unless very large liquid argon or liquid scintillator detectors are built, this is the only way to guarantee precise measurements of supernova ?e.

Laha, Ranjan; Beacom, John F.

2014-03-01

317

Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes  

E-print Network

Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E

2012-01-01

318

Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes  

E-print Network

Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

E. May; M. Thoennessen

2012-01-19

319

Discovery of samarium, europium, gadolinium, and terbium isotopes  

SciTech Connect

Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2013-01-15

320

Development of gadolinium based nanoparticles having an affinity towards melanin  

NASA Astrophysics Data System (ADS)

Small Rigid Platforms (SRPs) are sub-5 nanometre gadolinium based nanoparticles that have been developed for multimodal imaging and theranostic applications. They are composed of a polysiloxane network surrounded by gadolinium chelates. A covalent coupling with quinoxaline derivatives has been performed. Such derivatives have proven their affinity for melanin frequently expressed in primary melanoma cases. Three different quinoxaline derivatives have been synthesised and coupled to the nanoparticles. The affinity of the grafted nanoparticles for melanin has then been shown in vitro by surface plasmon resonance on a homemade melanin grafted gold chip.Small Rigid Platforms (SRPs) are sub-5 nanometre gadolinium based nanoparticles that have been developed for multimodal imaging and theranostic applications. They are composed of a polysiloxane network surrounded by gadolinium chelates. A covalent coupling with quinoxaline derivatives has been performed. Such derivatives have proven their affinity for melanin frequently expressed in primary melanoma cases. Three different quinoxaline derivatives have been synthesised and coupled to the nanoparticles. The affinity of the grafted nanoparticles for melanin has then been shown in vitro by surface plasmon resonance on a homemade melanin grafted gold chip. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr33457g

Morlieras, Jessica; Chezal, Jean-Michel; Miot-Noirault, Elisabeth; Roux, Amandine; Heinrich-Balard, Laurence; Cohen, Richard; Tarrit, Sébastien; Truillet, Charles; Mignot, Anna; Hachani, Roxanne; Kryza, David; Antoine, Rodolphe; Dugourd, Philippe; Perriat, Pascal; Janier, Marc; Sancey, Lucie; Lux, François; Tillement, Olivier

2013-01-01

321

Standard specification for sintered gadolinium oxide-uranium dioxide pellets  

E-print Network

1.1 This specification is for finished sintered gadolinium oxide-uranium dioxide pellets for use in light-water reactors. It applies to gadolinium oxide-uranium dioxide pellets containing uranium of any 235U concentration and any concentration of gadolinium oxide. 1.2 This specification recognizes the presence of reprocessed uranium in the fuel cycle and consequently defines isotopic limits for gadolinium oxide-uranium dioxide pellets made from commercial grade UO2. Such commercial grade UO2 is defined so that, regarding fuel design and manufacture, the product is essentially equivalent to that made from unirradiated uranium. UO2 falling outside these limits cannot necessarily be regarded as equivalent and may thus need special provisions at the fuel fabrication plant or in the fuel design. 1.3 This specification does not include (1) provisions for preventing criticality accidents or (2) requirements for health and safety. Observance of this specification does not relieve the user of the obligation to be aw...

American Society for Testing and Materials. Philadelphia

2008-01-01

322

Purification of cerium, neodymium and gadolinium for low background experiments  

NASA Astrophysics Data System (ADS)

Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0?2? search), 136Ce (2?+ candidate with one of the highest Q2?). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2? experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides) was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

2014-01-01

323

Gallium-67 radionuclide imaging in acute pyelonephritis  

SciTech Connect

The symptoms and clinical course of patients with acute pyelonephritis are variable; likewise, urinalysis, blood cultures, and excretory urography may be normal or equivocal. The ability of gallium-67 to accumulate in areas of active inflammation was useful in the diagnosis of acute pyelonephritis in 12 cases. A multiplane tomographic scanner was used for imaging four of these patients. Initial experience with this scanner is also discussed.

Mendez, G.; Morillo, G.; Alonso, M.; Isikoff, M.B.

1980-01-01

324

Porous gallium arsenide with arsenic clusters  

Microsoft Academic Search

It is for the first time that the possibility is demonstrated of preparing gallium arsenide with arsenic clusters under conditions\\u000a of annealing of its porous layers obtained by electrochemical etching. It is found that the clusters are concentrated in porous\\u000a layer barriers, their size ranges from 1 to 10 nm, and the density reaches 41018 cm?3. Under conditions of annealing

Yu. N. Buzynin; S. A. Gusev; Yu. N. Drozdov; A. V. Murel

2000-01-01

325

A Gallium multiphase equation of state  

SciTech Connect

A new SESAME multiphase Gallium equation of state (EOS) has been developed. The equation of state includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniol data. We also explore the possibility of re-freezing via dynamic means such as isentropic and shock compression.

Crockett, Scott D [Los Alamos National Laboratory; Greeff, Carl [Los Alamos National Laboratory

2009-01-01

326

Combined thermodynamic and rare earth element modelling of garnet growth during subduction: Examples from ultrahigh-pressure eclogite of the Western Gneiss  

E-print Network

Combined thermodynamic and rare earth element modelling of garnet growth during subduction Keywords ultrahigh-pressure metamorphism garnet trace elements Western Gneiss Region thermodynamic modeling garnets from the Western Gneiss Region (Norway). All investigated garnets show multiple growth zones

Zack, Thomas

327

High-dose gallium imaging in lymphoma  

SciTech Connect

The role of gallium-67 imaging in the management of patients with lymphoma, traditionally assessed using low tracer doses and the rectilinear scanner, was assessed when using larger doses (7 to 10 mCi) and a triple-peak Anger camera. Gallium scan results in 51 patients with non-Hodgkin's lymphoma and 21 patients with Hodgkin's disease were compared with simultaneous radiologic, clinical, and histopathologic reports. Subsequent disease course was also evaluated in light of radionuclide findings. Sensitivity and specificity of the scans were 0.90 or greater for both non-Hodgkin's lymphoma and Hodgkin's disease, and overall accuracy by site was 96 percent. Although there are insufficient numbers of pretreatment scans to allow any conclusions, our data suggest that newer approaches to gallium scanning in treated patients are (1) highly specific in all lymphomas and most sensitive in high-grade non-Hodgkin's lymphoma and Hodgkin's disease; (2) valuable in assessing the mediastinum in both non-Hodgkin's lymphoma and Hodgkin's disease; and (3) helpful adjuncts to computed tomographic scanning and ultrasonography in assessing abdominal node disease.

Anderson, K.C.; Leonard, R.C.; Canellos, G.P.; Skarin, A.T.; Kaplan, W.D.

1983-08-01

328

Crystal preferred orientations of garnet: comparison between numerical simulations and electron back-scattered diffraction (EBSD) measurements  

E-print Network

Crystal preferred orientations of garnet: comparison between numerical simulations and electron support plastic deformation of garnet in laboratory experiments and naturally deformed eclogites. To evaluate the crystal preferred orientations (CPO) of garnet formed in axial shortening, pure shear

Bascou, Jérôme

329

Laser-induced magnetization dynamics in a cobalt/garnet heterostructure  

NASA Astrophysics Data System (ADS)

We report on magnetization dynamics triggered in a Co/garnet heterostructure by femtosecond laser pulses. Although laser excitation of a bare Co-doped yttrium iron garnet leads to magnetization precession, the phase of which strongly depends on the linear polarization of the light pulses, the deposition of an ultrathin Co layer on a top of a garnet film results in substantial changes of the laser-induced dynamics. The precession in the garnet is shown to lose its sensitivity to the polarization. Instead, light triggers polarization insensitive precession in both the magnetostatically coupled Co layer and the garnet film at two distinct frequencies typical for Co and garnet layers.

Pashkevich, M.; Stupakiewicz, A.; Kimel, A.; Kirilyuk, A.; Stognij, A.; Novitskii, N.; Maziewski, A.; Rasing, Th.

2014-01-01

330

Structure-Entropy Relationships in Aluminosilicate Garnets (Invited)  

NASA Astrophysics Data System (ADS)

Aluminosilicate garnet (X3Al2Si3O12) is a key rock-forming mineral whose geological occurrence is widespread. Various petrologic, geochemical and geophysical processes can be best interpreted if garnet's structure and thermodynamic properties are understood. Extensive research has been done on garnet's crystal-chemical properties using diffraction and spectroscopic measurements as well as computational methods. The level of understanding is, in general, good. In terms of macroscopic thermodynamic properties, there has also been much work done over the years. Here, however, the level of understanding is less. Consider the crystal chemistry and entropy behavior of two binary solid solutions, namely pyrope-grossular (Py-Gr) [(MgxCa1-x)3Al2Si3O12] and almandine-spessartine (Al-Sp) [(FexMn1-x)3Al2Si3O12]. The heat capacity, Cp, of a series of well characterized natural and synthetic almandine-spessartine garnets was recently measured between 3 and 300 K (Dachs et al., submitted). All garnets show a ?-type anomaly at low temperatures resulting from a paramagnetic-antiferromagnetic phase transition. The lattice heat capacity, Cp,vib, was calculated for each garnet member by applying the phonon dispersion model of Komada and Westrum (1997). This allows a decomposition of S298 into its vibrational (Svib) and magnetic (Smag) contributions. A full analysis shows that the Al-Sp binary is entropically ideal with ?Sex ? 0 at 298 K. Previously published calorimetric work on Py-Gr garnets shows, in contrast, substantial positive ?Sex across the join at 298 K (Dachs and Geiger, 2006). Why the difference? The vibrational behavior of the divalent X cations plays an important role in affecting macroscopic Cp,vib and Svib in aluminosilicate garnets. X-ray single-crystal diffraction and XAFS measurements show that the mean square amplitudes of vibration for Fe2+ in Al and Mn2+ in Sp are similar and, moreover, they do not vary significantly in magnitude as a function of composition across the Al-Sp binary. Vibrational modes in IR and Raman spectra of Al-Sp garnets show mostly continuous and linear variation in wavenumber across the binary. These results are fully consistent with the calorimetric work indicating ?Sex ? 0 at 298 K. In contrast, the mean square amplitudes of vibration of Mg and Ca in Py-Gr garnets are substantially different from each other. The behavior of IR and Raman modes in spectra of Py-Gr garnets are also quite different than the spectra of Al-Sp garnets. Low energy modes related to Ca and especially Mg do not shift linearly in energy across the Py-Gr join but soften in intermediate compositions. This behavior is considered to be the cause of the large positive ?Sex behavior. Al-Sp garnets differ, of course, from Py-Gr garnets because of their magnetic and electronic contributions to Cp and S.

Geiger, C. A.; Dachs, E.

2013-12-01

331

P-n junctions formed in gallium antimonide  

NASA Technical Reports Server (NTRS)

Vapor phase deposition process forms a heavily doped n-region on a melt-grown p-type gallium antimonide substrate. HCl transports gallium to the reaction zone, where it combines with antimony hydride and the dopant carrier, hydrogen telluride. Temperatures as low as 400 degrees C are required.

Clough, R.; Richman, D.; Tietjen, J.

1970-01-01

332

Standard Reference Material 1751: Gallium Melting-Point Standard  

E-print Network

Standard Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse NIST Special Publication 260-157 #12;#12;NIST Special Publication 260-157 XXXX Standard Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse Chemical Science and Technology Laboratory Process Measurements

333

Gallium scintigraphy in bone infarction. Correlation with bone imaging  

SciTech Connect

The appearance of gallium-67 images in bone infarction was studied in nine patients with sickle cell disease and correlated with the bone scan findings. Gallium uptake in acute infarction was decreased or absent with a variable bone scan uptake, and normal in healing infarcts, which showed increased uptake on bone scan. The significance of these findings is discussed.

Armas, R.R.; Goldsmith, S.J.

1984-01-01

334

Evaluation of thermobarometers for garnet peridotites  

NASA Technical Reports Server (NTRS)

Twenty-one geothermometers and six geobarometers are evaluated for accuracy and precision for garnet lherzolites, with a suite of well-equilibrated xenoliths from kimberlites of northern Lesotho. Accuracy was tested by comparison of P-T estimates for a diamond-bearing and a graphite-bearing xenolith with the experimentally determined diamond-graphite univariant curve and by comparison of P-T estimates for phlogopite-bearing xenoliths to the high-temperature stability limit of phlogopite. Precision was evaluated by measuring the scatter of P-T estimates for each of four xenoliths from a wide range of P and T when many point analyses of the constituent minerals are used for P-T estimation. Most satisfactory is a thermobarometer composed of the uncorrected diopside-enstatite miscibility gap of Lindsley and Dixon (1976), combined with the uncorrected isopleths for aluminum in enstatite coexisting with pyrope of MacGregor (1974). The inflection observed in the northern Lesotho paleogeotherm cannot be an artifact of the method of temperature estimation.

Finnerty, A. A.; Boyd, F. R.

1984-01-01

335

Dating Subduction Zone Metamorphism with Garnet and Lawsonite Geochronology  

NASA Astrophysics Data System (ADS)

Lawsonite [CaAl2Si2O7(OH)2 H2O] is a critical index mineral for high- to ultrahigh-pressure metamorphism associated with subduction. Lawsonite is an important carrier of water into the mantle, a likely contributor to subduction zone seismicity, and a bearer of trace elements that link metamorphism to arc magmatism. Due to its limited pressure-temperature stability, lawsonite can serve as a powerful petrogenetic indicator of specific metamorphic events. Lu-Hf dating of lawsonite, therefore provides a potentially powerful new tool for constraining subduction zone processes in a pressure-temperature window where few successful geochronometers exist. Broad application of lawsonite Lu-Hf geochronology requires constraining the role of pressure-temperature path, lawsonite forming reactions, and the Lu and Hf systematics within lawsonite and other blueschist facies minerals. We are working to address the role of the metamorphic path on the applicability of lawsonite Lu-Hf geochronology within the Franciscan Complex of California. The Franciscan Complex preserves mafic high-grade exotic blocks in melange that underwent a counterclockwise pressure-temperature path wherein garnet, which strongly partitions heavy rare-earth elements, formed prior to lawsonite. Coherent mafic rocks within the Franciscan Complex, however, underwent a clockwise pressure-temperature path and lawsonite growth occurred prior to garnet. We sampled exotic blocks of garnet-hornblendite, garnet-epidote amphibolite, garnet-epidote blueschist, and lawsonite blueschist from the Berkeley Hills and Tiburon Peninsula of California. We collected four samples from coherent lawsonite blueschist across the lawsonite-pumpellyite-epidote isograds in Ward Creek, near Cazadero California. High-grade blocks give ages similar to existing Franciscan geochronology: multi-stage garnet in hornblendite gives the following ages: 171×1.3 Ma (MSWD 2.8) for the core and 159.4×0.9 Ma (MSWD 2.0) for the corresponding rim; 166×0.9 Ma (MSWD 1.0) for garnet-epidote amphibolite; and 156.2×1.0 Ma (MSWD 0.35) for garnet-epidote blueschist. Samples from retrograde exotic blocks contain lawsonite formed by garnet breakdown reactions and exhibit elevated Lu concentrations (?0.5-1.3 ppm) and 176Lu/177 Hf ratios (?2.2). Two samples we dated from the Berkeley Hills and Tiburon, respectively, gave lawsonite-whole rock ages of 129.2×1.2 Ma (MSWD 1.0) and 144.9×1.2 Ma (MSWD 0.64) . In the younger sample, garnet replaced by lawsonite is dated at 149.2×1.6 Ma. Lawsonite from Ward Creek that formed by prograde reactions involving plagioclase minerals, in contrast, have low Lu concentrations (?0.3 ppm) and low 176Lu/177 Hf ratios (?0.45). A garnet age of 151.6×1.3 Ma (MSWD 12.7) was obtained from garnet-epidote blueschist. While the ages from retrograde lawsonite within exotic blocks are similar to existing ages from the Franciscan Complex, no meaningful lawsonite ages were obtained from prograde coherent blocks of Ward Creek. The results suggest that lawsonite formed from the breakdown of garnet along a retrograde path provides meaningful Lu-Hf ages, while the very-low temperature lawsonite formed along a prograde path is not well suited for geochronology. This may be due to factors such as non-equilibrium at low metamorphic grades, low bulk rock Lu content, and the prevalence of micro-zircon within these samples.

Mulcahy, S. R.; Vervoort, J. D.

2013-12-01

336

REE Zoning in Garnet as a Record of Pressure Changes During Growth  

NASA Astrophysics Data System (ADS)

Radial variations in the concentrations of rare-earth elements (REE) in garnets from metamorphic rocks of the Llano Uplift of central Texas display systematic patterns that indicate that the REE may be sensitive recorders of changes in pressure during growth. LA-ICP-MS analysis of REE concentrations was performed at interior and rim positions of centered sections through garnets from garnet-clinopyroxenites at Whitt Ranch (WR) and from garnet-clinopyroxenites (PHM) and pelitic gneisses (PHP) at Purdy Hill. REE-abundance curves are flatter for PHM garnets than for WR garnets. Curves for WR garnets flatten towards rims; curves for PHM garnets steepen towards rims; and curves for PHP garnets first steepen in HREE toward rims, and then flatten, with negative slopes in HREE for some rim analyses. WR garnets contain negative Eu anomalies in interiors that disappear towards rims; PHM garnets contain small positive Eu anomalies throughout; and PHP garnets contain small negative Eu anomalies in both interiors and rims. Garnet-inclusion suites document that PH garnets formed at higher pressures than WR garnets, which suggests that flatter REE-abundance curves reflect higher pressures, corroborating the observations of Bea et al. (1997, Geostds Newsltr 21:253). Flattening of curves from interiors to rims suggests that WR garnets grew as pressure increased, which is supported by the distribution of inclusions in garnet: interiors contain plagioclase inclusions but rims do not, accounting for the rimward loss of negative Eu anomalies. Conversely, steepening of curves in PHM garnets may imply that they grew during decompression, although positive Eu anomalies suggest breakdown of plagioclase during garnet growth. Relative depletion of HREE in the rims of PHP garnets may record the growth of xenotime. Application of the Gd/Dy-in-garnet barometer of Bea et al. to PHP samples yielded pressures of 0.4-0.5 GPa, inconsistent with their eclogite-facies origin and with prior grt-opx barometry at PH of 1.5-2.1 GPa. Thus, although the shapes of the REE-abundance curves for the Llano garnets change systematically with pressure in a manner similar to the pattern described by Bea et al., the ratio of Gd/Dy alone fails to capture the complex behavior of the REE over the full range of pressure commonly experienced by crustal metamorphic rocks.

Lane, E. D.; Carlson, W. D.

2003-12-01

337

Effect of terbium gallium garnet crystal orientation on the isolation ratio of a Faraday isolator at high average power  

Microsoft Academic Search

We present a comprehensive and systematic investigation of the fundamental physical limitations of Faraday isolation performance at high average powers that are due to thermally induced birefringence. First, the operation of various Faraday isolator designs by use of arbitrary orientation of cubic magneto-optic crystals is studied theoretically. It is shown that, for different Faraday isolator designs, different crystal orientations can

Efim Khazanov; Nicolay Andreev; Oleg Palashov; Anatoly Poteomkin; Alexander Sergeev; Oliver Mehl; David H. Reitze

2002-01-01

338

Gadolinium-enhanced magnetic resonance angiography in brain death  

PubMed Central

Confirmatory tests for the diagnosis of brain death in addition to clinical findings may shorten observation time required in some countries and may add certainty to the diagnosis under specific circumstances. The practicability of Gadolinium-enhanced magnetic resonance angiography to confirm cerebral circulatory arrest was assessed after the diagnosis of brain death in 15 patients using a 1.5 Tesla MRI scanner. In all 15 patients extracranial blood flow distal to the external carotid arteries was undisturbed. In 14 patients no contrast medium was noted within intracerebral vessels above the proximal level of the intracerebral arteries. In one patient more distal segments of the anterior and middle cerebral arteries (A3 and M3) were filled with contrast medium. Gadolinium-enhanced MRA may be considered conclusive evidence of cerebral circulatory arrest, when major intracranial vessels fail to fill with contrast medium while extracranial vessels show normal blood flow. PMID:24413880

Luchtmann, M.; Beuing, O.; Skalej, M.; Kohl, J.; Serowy, S.; Bernarding, J.; Firsching, R.

2014-01-01

339

About a Gadolinium-doped Water Cherenkov LAGUNA Detector  

SciTech Connect

Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R and D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

Labarga, Luis [Department of Theoretical Physics, University Autonoma Madrid, 28049 Madrid (Spain)

2010-11-24

340

The formation of garnet in olivine-bearing metagabbros from the Adirondacks  

Microsoft Academic Search

A regional study of olivine-bearing metagabbros in the Adirondacks has permitted testing of the P(pressure)-T(temperature)-X(composition) dependence of garnet-forming reactions as well as providing additional regional metamorphic pressure data. Six phases, olivine, orthopyroxene, clinopyroxene, garnet, plagioclase and spinel, which can be related by the reactions: orthopyroxene+clinopyroxene+spinel +anorthite=garnet, and forsterite+anorthite=garnet occur together both in coronal and in equant textures indicative of equilibrium.

Craig A. Johnson; Eric J. Essene

1982-01-01

341

Gallium scintigraphic pattern in lung CMV infections  

SciTech Connect

Due to extensive use of prophylactic therapy for Pneumonitis Carinii Pneumonia (PCP), Cytomegalic Viral (CMV) infection may now be the most common lung infection in AIDS patients. This study was performed to determine Gallium-67 patterns in AIDS patients with CMV. Pathology reports were reviewed in AIDS patients who had a dose of 5 to 10 mCi of Gallium-67 citrate. Analysis of images were obtained 48-72 hours later of the entire body was performed. Gallium-67 scans in 14 AIDS patients with biopsy proven CMV, were evaluated for eye, colon, adrenal, lung and renal uptake. These were compared to 40 AIDS patients without CMV. These controls had infections including PCP, Mycobacterial infections, and lymphocytic interstitial pneumonitis. 100% of CMV patients had bowel uptake greater than or equal to liver. Similar bowel activity was seen in 50% of AIDS patients without CMV. 71% had intense eye uptake which was seen in only 10% of patients without CMV. 50% of CMV patients had renal uptake compared to 5% of non-CMV cases. Adrenal uptake was suggested in 50%, however, SPECT imaging is needed for confirmation. 85% had low grade lung uptake. The low grade lung had perihilar prominence. The remaining 15% had high grade lung uptake (greater than sternum) due to superimposed PCP infection. Colon uptake is very sensitive indicator for CMV infection. However, observing eye, renal, and or adrenal uptake improved the diagnostic specificity. SPECT imaging is needed to confirm renal or adrenal abnormalities due to intense bowel activity present in 100% of cases. When high grade lung uptake is seen superimposed PCP is suggested.

Ganz, W.I.; Cohen, D.; Mallin, W. [Univ. of Miami School of Medicine, FL (United States)] [and others

1994-05-01

342

Nanopipes in gallium nitride nanowires and rods.  

PubMed

Gallium nitride nanowires and rods synthesized by a catalyst-free vapor-solid growth method were analyzed with cross section high-resolution transmission electron microscopy. The cross section studies revealed hollow core screw dislocations, or nanopipes, in the nanowires and rods. The hollow cores were located at or near the center of the nanowires and rods, along the axis of a screw dislocation. The formation of the hollow cores is consistent with effect of screw dislocations with giant Burgers vector predicted by Frank. PMID:19367802

Jacobs, Benjamin W; Crimp, Martin A; McElroy, Kaylee; Ayres, Virginia M

2008-12-01

343

Electric-field gradients in ionic gadolinium compounds  

Microsoft Academic Search

The calculation of the electric-field gradients (EFGs) in a number of ionic gadolinium compounds is considered. The lattice EFGs at the sites of Gd3+ ions have been evaluated by means of a point-charge model. Comparison of the results with quadrupole-splitting data yields a value of -75+or-2 for the Sternheimer antishielding factor gamma infinity for the Gd3+ ion. The accuracy of

W. A. Barton; J. D. Cashion

1979-01-01

344

Magnons as a Bose-Einstein Condensate in Nanocrystalline Gadolinium  

SciTech Connect

The recent observation [S. P. Mathew et al., J. Phys. Conf. Ser. 200, 072047 (2010)] of the anomalous softening of spin-wave modes at low temperatures in nanocrystalline gadolinium is interpreted as a Bose-Einstein condensation (BEC) of magnons. A self-consistent calculation, based on the BEC picture, is shown to closely reproduce the observed temperature variations of magnetization and specific heat at constant magnetic fields.

Kaul, S. N.; Mathew, S. P. [School of Physics, University of Hyderabad, Central University P.O., Hyderabad-500 046 (India)

2011-06-17

345

Validation of Injection Parameters for Catheter-Directed Intraarterial Gadolinium-Enhanced MR Angiography  

Microsoft Academic Search

Rationale and ObjectivesCatheter-directed intraarterial (IA) injections of gadolinium contrast agents may be used during endovascular interventions with magnetic resonance (MR) imaging guidance. Injection protocols require further validation. Using a flow phantom and swine, the authors aimed to (a) measure the optimal arterial gadolinium concentration ([Gd]) required for MR angiography and (b) validate a proposed IA injection protocol for gadolinium-enhanced MR

Reed A. Omary; Kevin P. Henseler; Orhan Unal; Randall J. Smith; Robert K. Ryu; Scott A. Resnick; Mark B. Saker; Howard B. Chrisman; Richard Frayne; J. Paul Finn; Debiao Li; Thomas M. Grist

2002-01-01

346

Ion irradiation-induced amorphization and nano-crystal formation in garnets  

E-print Network

Ion irradiation-induced amorphization and nano-crystal formation in garnets S. Utsunomiya a , L ion irradiation of the G3 garnet at a temperature of 1023 K near the Tc, nano-crystals were produced, particularly yttrium aluminum garnet (YAG), Y3Al5O12, and YAG doped by other ions for use in laser systems

Utsunomiya, Satoshi

347

On-chip Optical Isolators Based on a Ring Resonator with Bismuth-iron-garnet Overcladding  

E-print Network

On-chip Optical Isolators Based on a Ring Resonator with Bismuth-iron-garnet Overcladding Kuanping@ucdavis.edu Abstract: This paper discusses on-chip optical isolators with bismuth-iron-garnet (BIG) overcladding wavelength regime [1, 2]. On the other hand, bismuth iron garnet (Bi3Fe5O12) has a wide optical transmission

Kolner, Brian H.

348

Examining the Temperature Range Suitable for Quartz-in-Garnet Geoba-Raman-Try  

NASA Astrophysics Data System (ADS)

P's were calculated using quartz inclusions in garnet over a wide range of P-T conditions. Data suggests quartz-in-garnet geoba-Raman-try may be accurate up to the granulite facies. P may also be retrieved for multiple stages of garnet growth.

Walters, J. B.; Kohn, M. J.

2014-06-01

349

Growth and ferromagnetic resonance properties of nanometer-thick yttrium iron garnet films  

E-print Network

Growth and ferromagnetic resonance properties of nanometer-thick yttrium iron garnet films Yiyan and ferromagnetic resonance properties of nanometer-thick yttrium iron garnet films Yiyan Sun,1 Young-Yeal Song,1-thick yttrium iron garnet films and ferromagnetic resonance (FMR) linewidth properties in the films are reported

350

Reaction texture and Fe-Mg zoning in granulite garnet from Sstrene Island, Antarctica: Modeling and  

E-print Network

Reaction texture and Fe-Mg zoning in granulite garnet from Søstrene Island, Antarctica: Modeling Department of Applied Geology, University of New South Wales, Kensington, NSW 2033, Australia. Garnets from collapse. Reaction-diffusion modeling of the compositional zoning of garnet associated with the development

Ganguly, Jibamitra

351

REVUE DE PHYSIQUE APPLIQUE Stress-and growth-induced anisotropic birefringences in garnet films  

E-print Network

753 REVUE DE PHYSIQUE APPLIQUÉE Stress- and growth-induced anisotropic birefringences in garnet. 2014 From optical wave-guide experiment in rare-earth and bismuth-substituted iron garnet films in the garnet which changes their content and therefore the lattice mismatch between the films

Paris-Sud XI, Université de

352

Experimental determination of trace element partitioning between garnet and silica-rich liquid during anhydrous  

E-print Network

Experimental determination of trace element partitioning between garnet and silica-rich liquid determined trace element partition coefficients for nine garnet/melt and two clinopyroxene/melt pairs at 2 at these conditions: garnets with 16­25% grossular component and 0.4­ 2.0 wt % TiO2 coexist with siliceous partial

Hirschmann, Marc

353

Ultramafic cumulates of oceanic mantle affinity in a continental subduction zone: UHP garnet  

E-print Network

Ultramafic cumulates of oceanic mantle affinity in a continental subduction zone: UHP garnet of Ljubljana, Slovenia 4 Dept. of Earth Sciences, University of Ottawa, Canada Rare UHP garnet peridotites have,2]. Peak P-T conditions of the garnet peridotites reached up to 4 GPa and 900°C [1]. The UHP metamorphic

354

Solubility of water in pyrope-rich garnet at high pressures and temperature  

E-print Network

Solubility of water in pyrope-rich garnet at high pressures and temperature Mainak Mookherjee1; published 12 February 2010. [1] The water solubility in pyrope-rich garnet was determined between pressures expected in the Earth's upper mantle. We found that pyrope-rich garnet has substantial water solubility up

355

Meltperidotite interactions: Links between garnet pyroxenite and high-Mg# signature of continental crust  

E-print Network

Melt­peridotite interactions: Links between garnet pyroxenite and high-Mg# signature of continental lherzolite, garnet pyroxenite and granulite xenoliths are found in the Neogene Hannuoba basalt of the North China craton. Garnet pyroxenites generally occur as veins/layers in spinel lherzolites

Lee, Cin-Ty Aeolus

356

Sm^Nd dating of spatially controlled domains of garnet single crystals: a new method of  

E-print Network

Sm^Nd dating of spatially controlled domains of garnet single crystals: a new method of high of the method using the core and bulk ages of garnet single crystals, according to the Sm^Nd decay system exposure of the Salinian terrane, California. We have micro-sampled the garnet crystals over specific

Ganguly, Jibamitra

357

Temperature Dependent Fluorescence of Ce-doped Garnets For Use as Thermographic Phosphors  

E-print Network

Temperature Dependent Fluorescence of Ce-doped Garnets For Use as Thermographic Phosphors R emission at a longer wavelengths. 2 Introduction Cerium-doped yttrium aluminum garnet (Y3Al5O12:Ce, YAG distortions in smaller particles [13]. Similarly, the quenching temperature of bulk yttrium aluminum garnet

Walker, D. Greg

358

OPTICAL ABSORPTIONS AND ROTATIONS IN THE FERRIMAGNETIC GARNETS By J. F. DILLON, Jr.,  

E-print Network

374 OPTICAL ABSORPTIONS AND ROTATIONS IN THE FERRIMAGNETIC GARNETS By J. F. DILLON, Jr., Bell of the ferrimagnetic garnets have been measured. There are several maxima in the absorption below an absorption edge. - The properties of the recently discovered ferrimagnetic garnets [1], [2] (FMG) have been the subject of a very

Paris-Sud XI, Université de

359

MINERALOGICAL MAGAZINE, MARCH 1984, VOL. 48, PP. 21 6 Inclusion patterns in zoned garnets from  

E-print Network

MINERALOGICAL MAGAZINE, MARCH 1984, VOL. 48, PP. 21 6 Inclusion patterns in zoned garnets from ABSTRACT. Garnet porphyroblasts in metasediments from Mageroy crystallized during static metamorphism and represent recrystallized quartz grains concen- trated along defects in the garnet lattice. The defects

Andersen, Torgeir Bjørge

360

Study of exciton dynamics in garnets by low temperature thermo-luminescence  

E-print Network

Study of exciton dynamics in garnets by low temperature thermo- luminescence D. T. Mackay, C. R://jap.aip.org/about/rights_and_permissions #12;Study of exciton dynamics in garnets by low temperature thermo-luminescence D. T. Mackay, C. R July 2012) Shallow traps that affect exciton dynamics in undoped and Ce doped yttrium aluminum garnet

Collins, Gary S.

361

Author's personal copy Trace element partitioning between majoritic garnet and silicate melt at 1017 GPa  

E-print Network

Author's personal copy Trace element partitioning between majoritic garnet and silicate melt at 10 online 18 June 2012 Keywords: Garnet Majorite Trace elements Komatiites Diamonds Mars Melting experiments were performed on a silica-rich peridotite composition at 10­17 GPa to determine majoritic garnet

Mcdonough, William F.

362

Jibamitra Ganguly Weiji Cheng Sumit Chakraborty Cation diffusion in aluminosilicate garnets: experimental determination  

E-print Network

Jibamitra Ganguly á Weiji Cheng á Sumit Chakraborty Cation diffusion in aluminosilicate garnets 1997 Abstract Diusion couples made from homogeneous gem quality natural pyrope and almandine garnets interdiusion coecient or D matrix elements for the purpose of modeling of diusion processes in natural garnets

Ganguly, Jibamitra

363

Progress in the use of gadolinium for NCT.  

PubMed

The evaluation of possible improvement in the use of Gd in cancer therapy, in reference to gadolinium in cancer therapy (GdNCT), has been analysed. At first the problem of the gadolinium compounds toxicity was reviewed identifying the Motexafin Gadolinium as the best. Afterwards, the spectrum of IC and Auger electrons was calculated using a special method. Afterwards, this electron source has been used as input of the PENELOPE code and the energy deposit in DNA was well defined. Taking into account that the electron yield and energy distribution are related to the neutron beam spectrum and intensity, the shaping assembly architecture was optimised through computational investigations. Finally the study of GdNCT was performed from two different points of view: macrodosimetry using MCNPX, with calculation of absorbed doses both in tumour and healthy tissues, and microdosimetry using PENELOPE, with the determination of electron RBE through the energy deposit. The equivalent doses were determined combining these two kinds of data, introducing specific figures of merit to be used in treatment planning system (TPS). According to these results, the GdNCT appears to be a fairly possible tumour therapy. PMID:19410468

Cerullo, N; Bufalino, D; Daquino, G

2009-07-01

364

Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy (abstract)  

NASA Astrophysics Data System (ADS)

The penetration property of the terahertz electromagnetic (THz) wave is relevant to its use. We used the THz wave spectroscopy system which easily penetrates some materials that do not contain water, e.g., plastic and ceramics. The system has been developed for several purposes, including measuring the properties of semiconductors and bio-materials, and detecting plastic bombs and ceramic knives at airports. It is also used for medical imaging systems, such as magnetic resonance imaging (MRI), at some research institutes. It can show not only the difference in amplitude, but also the difference of the phase of each point of sample. MRI technology usually uses contrast agents to enhance the quality of the image. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), made with a heavy metal ion, is commonly used as a clinical MRI contrast agent. Gadolinium oxide (Gd2O3) nanoparticle is a new contrast agent. It serves to equip the core of each particle with antibodies or ligands. It can freely circulate in blood vessels without amassing in the liver or lungs. This study shows the characteristics of gadolinium oxide nanoparticles to further advance terahertz medical imaging.

Lee, Dongkyu; Maeng, Inhee; Oh, Seung Jae; Kim, Taekhoon; Cho, Byung Kyu; Lee, Kwangyeol; Son, Joo-Hiuk

2009-04-01

365

Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy  

SciTech Connect

The penetration property of the terahertz electromagnetic (THz) wave is relevant to its use. We used the THz wave spectroscopy system which easily penetrates some materials that do not contain water, e.g., plastic and ceramics. The system has been developed for several purposes, including measuring the properties of semiconductors and bio-materials, and detecting plastic bombs and ceramic knives at airports. It is also used for medical imaging systems, such as magnetic resonance imaging (MRI), at some research institutes. It can show not only the difference in amplitude, but also the difference of the phase of each point of sample. MRI technology usually uses contrast agents to enhance the quality of the image. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), made with a heavy metal ion, is commonly used as a clinical MRI contrast agent. Gadolinium oxide (Gd{sub 2}O{sub 3}) nanoparticle is a new contrast agent. It serves to equip the core of each particle with antibodies or ligands. It can freely circulate in blood vessels without amassing in the liver or lungs. This study shows the characteristics of gadolinium oxide nanoparticles to further advance terahertz medical imaging.

Lee, Dongkyu; Maeng, Inhee; Son, Joo-Hiuk [Department of Physics, University of Seoul, Seoul (Korea, Republic of); Oh, Seung Jae [Brain Korea 21 Project for Medical Science, Yonsei University, Seoul (Korea, Republic of); Kim, Taekhoon; Cho, Byung Kyu; Lee, Kwangyeol [Department of Chemistry, Korea University, Seoul (Korea, Republic of)

2009-04-19

366

Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters  

NASA Technical Reports Server (NTRS)

As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

1999-01-01

367

A novel technique for microstructure characterization of garnet films  

NASA Astrophysics Data System (ADS)

Bismuth-substituted iron garnet exhibits remarkable magneto-optical properties in magnetic photonic crystal (MPC) structures, and has the potential to improve performance in optical integrated circuits for communication networks and optical sensing applications. The microstructure and thickness of these garnet films has a strong influence over their optical, magnetic and magneto-optic (MO) properties. The thickness of these films has been measured indirectly via optical interference and ellipsometry, which are unable to map thickness variations due to surface roughness of both the film and the substrate. However, little direct observation has been carried out to provide detailed information about the microstructure of the garnet films, especially in cross-section. All these have resulted in a lack of understanding of processing-microstructure-MO property relationship, which in turn impedes the development of high-performance garnet films. The combined use of focused ion beam (FIB) milling and transmission electron microscopy (TEM), described as the FIB-TEM method hereafter, provides a reliable, direct means of characterization of site-specific micron-sized regions of a specimen within a reasonable length of time. A sound understanding of processing-microstructure-MO property relationship enabled by FIB-TEM method is crucial in the design of the manufacturing processes for such functional films as well as nanostructures that have garnet layers. This paper reports the experimental procedures of FIB-TEM technique for characterization of these films and discusses the strength and issues associated with its application on (Bi, Dy) 3(Fe, Ga) 5O 12 garnet films.

Wo, P. C.; Munroe, P. R.; Vasiliev, M.; Xie, Z. H.; Alameh, K.; Kotov, V.

2009-12-01

368

Evidence for structural changes in garnet caused by calcium substitution  

NASA Astrophysics Data System (ADS)

Recent work on the pyrope-grossular and almandine grossular solid solution series has shown that at concentrations of Ca up to 15mol.% the garnets show negative excess volumes and negative excess free energies of mixing. It has been suggested that this results from a change in structure caused by Ca ordering. This note describes a preliminary X-ray study of such a garnet and concludes that there is a structural change, possibly to space group I 213, caused by Ca substitution and that further work must be done to see if this is caused by ordering.

Dempsey, M. J.

1980-01-01

369

Analysis of garnets from the archaeological sites in Slovenia  

NASA Astrophysics Data System (ADS)

Garnets (62 individual stones) originating from the Migration Period cemeteries and hilltop settlements in Slovenia were analyzed by the combined PIXE/PIGE method for their chemical composition. Typologically, the analyzed stones may be classified as almandines originating from the sites in India, belonging to types I and II according to Calligaro. A smaller group of pyraldines intermediate between almandines and pyropes was also determined; identified as type III, their source is most likely in Sri Lanka. No garnets from Bohemia (Czech Republic) have been discovered, which may be related to important political changes in the 7th c. AD, induced by Slavic and Avaric migrations.

Šmit, Ž.; Fajfar, H.; Jeršek, M.; Knific, T.; Lux, J.

2014-06-01

370

Transformation of enstatite — diopside — jadeite pyroxenes to garnet  

Microsoft Academic Search

The high-pressure stability of enstatite(En)-diopside(Di)-jadeite(Jd) pyroxenes has been investigated experimentally with a split-sphere anvil apparatus (USSA-2000). On the enstatite-pyrope join, the compositions of garnet coexisting with enstatite were determined at 100–165 kbar and 1450–1850° C. The results indicate complete solubility between enstatite and pyrope. In the system CaO-MgO-Al2O3-SiO2 (CMAS), the compositions of coexisting pyroxenes and garnet were determined at 100–165

Tibor Gasparik

1989-01-01

371

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2008. One company in Utah  

E-print Network

as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $23 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about

372

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2009. One company in Utah  

E-print Network

as a percentage of reported consumption 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $14 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about

373

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2003. One company in  

E-print Network

$4 million, most of which was low-purity material. Gallium arsenide (GaAs) and gallium nitride (GaN in optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes, photodetectors, and solar cells

374

Gallium scanning in lymphoid interstitial pneumonitis of children with AIDS  

SciTech Connect

Lymphoid interstitial pneumonitis (LIP) is a frequent pulmonary complication in the child with the acquired immune deficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection. We report the gallium scan findings in two children with AIDS and LIP. Gallium scintigraphy in both children demonstrated increased radionuclide concentration throughout the lungs, a pattern indistinguishable scintigraphically from that of Pneumocystis carinii pneumonia (PCP). This should alert nuclear medicine practitioners and referring physicians to another cause of diffusely increased gallium uptake in the lungs of patients with AIDS.

Schiff, R.G.; Kabat, L.; Kamani, N.

1987-12-01

375

File DR1. Garnet dissolution calculations following Kohn and Spear (2000) Measurements and calculations for sample GP-5  

E-print Network

File DR1. Garnet dissolution calculations following Kohn and Spear (2000) Measurements and calculations for sample GP-5 Garnet mode = 10% Biotite mode = 20% Biotite Fe/(Fe + Mg) (matrix) = 1 of analyzed garnet: 3.8 mm2 Present volume of analyzed garnet (assuming spherical geometry): 5.6 mm3 Radius

Kidd, William S. F.

2000-01-01

376

Single-crystal elasticity of grossular-and almandine-rich garnets to 11 GPa by Brillouin  

E-print Network

Single-crystal elasticity of grossular- and almandine-rich garnets to 11 GPa by Brillouin- rich Alm72Pyp20Sps3Grs3And2 natural garnet single crystals were determined by Brillouin scattering.1 for the almandine-rich garnet. Both individual and aggregate elastic moduli of the two garnets define nearly linear

Duffy, Thomas S.

377

Sub-Microsecond Decay Time Phosphors for Pressure Sensitive Paint Applications  

SciTech Connect

The results suggest that garnet phosphors can be engineered to function thermographically over desired temperature ranges by adjusting gallium content. Substituting gadolinium for the yttrium in the host matrix also has an effect but it is not as large. A silicate phosphor showed the greatest temperature dependence though it could not be excited to fluoresce by a blue LED. All the garnet phosphors could be excited with such a blue source. Two phosphors tested showed an increase in intensity with temperature. Other garnet and silicate materials as mentioned above will be tested in the future. In addition, some perovskite phosphors, such as GdAlO{sub 3}:Ce, will also be investigated.

Allison, S.W.

2001-03-22

378

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2012. One company in Utah  

E-print Network

­4908, bjaskula@usgs.gov] #12;59 GALLIUM In 2012, the worldwide LED market, a significant driver for GaN.S. gallium consumption, were valued at about $32 million. Gallium arsenide (GaAs) and gallium nitride (GaN conditions continued to improve for GaAs- and GaN-based products in 2012. GaAs demand, while still driven

379

Petrological constraints on the cooling history of high-temperature garnet peridotite massifs in lower Austria  

Microsoft Academic Search

High-temperature peridotite massifs occur as lensoid bodies with high-pressure granulites in the southern Bohemian massif.\\u000a In lower Austria the peridotites comprise garnet lherzolites lacking primary spinel, rare garnet and garnet-spinel harzburgites,\\u000a and harzburgites containing Cr-rich primary spinel instead of garnet. These phase assemblages suggest initial high-pressure\\u000a equilibration and are consistent with results from garnet-orthopyroxene geobarometry indicating equilibration at around 3–3.5?GPa.

Harry Becker

1997-01-01

380

Elasticity of some mantle crystals structures. III - Spessartite-almandine garnet  

NASA Technical Reports Server (NTRS)

Measurements of the pressure dependence of the elastic constants of spessartite-almandine garnet are given. The basis for velocity systematics among the available natural and synthetic garnet data is then examined. As for any dense oxide, the natural anion in garnet is dominant in size. The ionic sizes of the cations in the various sites are used to determine the extent to which it might be expected that garnets of different chemical formulas are analogous in elastic properties. The results are used to predict that the elastic velocities in garnet-transformed MgSiO3 are the same as those in pyrope (Mg3Al2Si3O12).

Wang, H.; Simmons, G.

1974-01-01

381

Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium  

E-print Network

Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-...

Xu, Qin; Guo, Qiti; Jaeger, Heinrich; Brown, Eric

2012-01-01

382

Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing  

NASA Astrophysics Data System (ADS)

Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

Alur, Siddharth

383

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally,  

E-print Network

of a strong LED-based backlighting market, which failed to materialize. Global demand for GaAs- and GaN.S. gallium consumption, were valued at about $16 million. Gallium arsenide (GaAs) and gallium nitride (GaN to the large power-handling capabilities, high-switching frequencies, and higher voltage capabilities of GaN

384

Closure temperatures of the Sm-Nd system in metamorphic garnets  

NASA Astrophysics Data System (ADS)

Garnet-whole rock and garnet-mineral isochrons were determined on granulite facies gneisses and amphibolites from the Archean Pikwitonei Granulite Domain of the Superior Province, and the Proterozoic Central Gneiss Belt and Adirondack Highlands of the Grenville orogen. The Sm-Nd ages obtained from Archean garnets 0.1-0.5 cm in length are 30-110 Ma younger than the U-Pb ages obtained on the same garnets and also younger than the time of the last regional metamorphism, as determined by the growth ages of the youngest metamorphic garnets and zircons. Similarly, the Sm-Nd ages obtained from Proterozoic garnets with a diameter of 0.1-5 cm are younger than the time of the last regional metamorphism and similar or younger than cooling ages obtained on sphenes from the same sample or from the same geologic setting. Only the core of a garnet with a diameter of ca. 30 cm and without abundant inclusions may record the time of garnet growth. Comparison of the Sm-Nd ages with other geochronologic data and temperature estimates leads to the conclusion that the closure temperature for the Sm-Nd system in garnets analyzed in this study is ca. 600 +/- 30 C. Only garnets with radii much larger than 5 cm may record Sm-Nd growth ages in upper amphibolite facies rocks from slowly cooled terranes. Garnets from higher grade terranes yield cooling ages that define the retrograde history of metamorphic terranes.

Mezger, K.; Essene, E. J.; Halliday, A. N.

1992-10-01

385

Effect of grossular on garnet-biotite, Fe–Mg exchange reactions: evidence from garnet with mixed growth and diffusion zoning  

Microsoft Academic Search

Garnets that exhibit mixed growth and diffusion zoning are used to evaluate the effect of grossular content on garnet Fe–Mg\\u000a exchange reactions. These garnets from the uppermost amphibolite-facies to granulite-facies gneiss of the Wissahickon Group,\\u000a southeastern Pennsylvania, show variation in grossular content (0.035X\\u000a CaX\\u000a Mg\\/(X\\u000a Mg+X\\u000a Fe) and X\\u000a Mn through the interior indicating re-equilibration of garnet and matrix minerals

J. Alcock

1996-01-01

386

All-optical modulation in gallium arsenide integrated optical waveguides  

SciTech Connect

We have investigated all-optical modulators in gallium arsenide integrated optical waveguides; these modulators use electron-hole pair generation to alter the propagation characteristics of a guided light beam. 6 refs., 6 figs.

McWright, G.; Ross, B.; Guthreau, W.; Lafaw, D.; Lowry, M.; Tindall, W.

1988-01-27

387

Computer simulation of radiation damage in gallium arsenide  

NASA Technical Reports Server (NTRS)

A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.

Stith, John J.; Davenport, James C.; Copeland, Randolph L.

1989-01-01

388

Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster  

NASA Technical Reports Server (NTRS)

A low-energy gallium plasma source is used to perform a spatially and temporally broad spectroscopic survey in the 220-520 nm range. Neutral, singly, and doubly ionized gallium are present in a 20 J, 1.8 kA (peak) arc discharge operating with a central cathode. When the polarity of the inner electrode is reversed the discharge current and arc voltage waveforms remain similar. Utilizing a central anode configuration, multiple Ga lines are absent in the 270-340 nm range. In addition, neutral and singly ionized Fe spectral lines are present, indicating erosion of the outer electrode. With graphite present on the insulator to facilitate breakdown, line emission from the gallium species is further reduced and while emissions from singly and doubly ionized carbon atoms and molecular carbon (C2) radicals are observed. These data indicate that a significant fraction of energy is shifted from the gallium and deposited into the various carbon species.

Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

2007-01-01

389

Nonlinear precession dynamics of magnetization in (111) garnet ferrite films  

NASA Astrophysics Data System (ADS)

The nonlinear dynamics of magnetization precession in perpendicular-magnetized (111) garnet ferrite films is studied by numerically solving the equations of motion of magnetization. Bifurcational changes in the magnetization precession and dynamic-bistability states are detected. The conditions are found under which both regular and stochastic large-amplitude dynamic regimes arise.

Shuty?, A. M.; Sementsov, D. I.

2007-09-01

390

Ion irradiation effects in natural garnets: Comparison with zircon  

E-print Network

Ion irradiation effects in natural garnets: Comparison with zircon S. Utsunomiya, L.M. Wang, R ; Z ¼ 8) under ion-beam irradiation was investigated in order to compare its radiation susceptibility during the ion irradiation at high temperature. This behavior may be related to the phase relations

Utsunomiya, Satoshi

391

Isomorphism of actinides and REE in synthetic ferrite garnets  

NASA Astrophysics Data System (ADS)

The reprocessing of spent nuclear fuel (SNF) is accompanied by the formation of liquid high-level radioactive waste (HLW). To increase the safety of handling HLW, it is proposed to extract actinide isotopes (An) and REE from them. These elements may be incorporated into crystalline matrices, e.g., based on ferrites with garnet structure, and then disposed in a geologic repository. The actinide-REE fraction is characterized by a complex composition. In addition to major components (An and REE), Al, Si, Na, and Sn occur therein in small amounts (a few wt %). Possible incorporation of the admixtures into ferrite garnets, as well as their effect on the phase composition of matrices and Th, Ce, Gd, and La contents were studied. It was shown that admixtures enter into garnet by means of isomorphic replacement. The properties of samples change only when admixtures are added in amounts exceeding their concentrations in HLW. The ability of ferrite garnets to accumulate significant amounts of An, REE, and admixture elements makes them suitable for use as matrices in immobilizing actinide-REE HLW of complex composition.

Livshits, T. S.

2010-02-01

392

Thermodynamic consistencies and anomalies among end-member silicate garnets.  

PubMed

Materials with the garnet crystal structure include silicate minerals of importance both in geology, on account of their use in geothermobarometry, and industrially as abrasives. As a consequence of the former, there is considerable published thermodynamic information concerning them. We here examine this thermodynamic information for end-member silicate garnets (some of which are synthetic since not all occur in nature) for consistencies and anomalies, using thermodynamic relations between thermodynamic properties that we have established over recent years. The principal properties of interest are formula volume, heat capacity, entropy, formation enthalpy (from which the Gibbs energy may be obtained), and isothermal compressibility. A significant observation is that the ambient-temperature heat capacities of the silicate garnets are rather similar, whereas their ambient-temperature entropies are roughly proportional to their formula volumes. Evaluation of their Debye temperatures implies that their vibrational contributions to heat capacity are fully excited at ambient temperatures. The relatively small isothermal compressibilities of these garnets is related to the rigidity of their constituent silicate tetrahedra. We here establish additive single-ion values for each of the thermodynamic properties, which may be applied in estimating corresponding values for related materials. PMID:25115951

Glasser, Leslie

2014-09-01

393

Experimental Evaluation of GarnetClinopyroxene Thermometer Daisuke NAKAMURA  

E-print Network

Experimental Evaluation of Garnet­Clinopyroxene Thermometer Daisuke NAKAMURA 1 , Takao HIRAJIMA 1(Grt)­clinopyroxene(Cpx) thermometer have been proposed and widely applied to natural rocks for estimating metamorphic temperature (T), but a serious controversy exists on this thermometer. Pattison & Newton (1989) (PN89) performed reversal

Nakamura, Daisuke

394

Synthesis of yttrium aluminum garnet by reverse strike precipitation  

Microsoft Academic Search

Yttrium aluminum garnet (YAG) powders were synthesized by normal and reverse strike precipitation from a mixed solution containing aluminum and yttrium nitrates. The precipitates were characterized by FTIR, DTA, and TGA techniques. The amorphous precipitates were crystallized under various atmospheres (air, argon, hydrogen) at different temperatures and the product analyzed by X-ray diffraction. Only reverse strike precipitation followed by crystallization

Prasad Apte; Harry Burke; Helen Pickup

1992-01-01

395

Reverse self-assembly of lipid onions induced by gadolinium and calcium ions  

E-print Network

Reverse self-assembly of lipid onions induced by gadolinium and calcium ions Hee-Young Lee,a Kaname multilamellar vesicles ("onions") in cyclohexane and toluene by combining the saturated phospholipid, 1+ ) or gadolinium (Gd3+ ) in the absence of water. DMPC­Gd3+ onions can be seen by a transmission electron

Raghavan, Srinivasa

396

Use of Gadolinium as a Primary Criticality Control in Disposing Waste Containing Plutonium at SRS  

SciTech Connect

Use of gadolinium as a neutron poison has been proposed for disposing of several metric tons of excess plutonium at the Savannah River Site (SRS). The plutonium will first be dissolved in nitric acid in small batches. Gadolinium nitrate will then be added to the plutonium nitrate solution. The Gd-poisoned plutonium solution will be neutralized and transferred to large under-ground tanks. The pH of small batches of neutralized plutonium solution will be adjusted prior to addition of the glass frit for eventual production as glass logs. The use of gadolinium as the neutron poison would minimize the number of glass logs generated from this disposition. The primary criticality safety concerns regarding the disposal process are: (1) maintaining neutron moderation under all processing conditions since gadolinium has a very large absorption cross section for thermal neutrons, (2) characteristics of plutonium and gadolinium precipitation during the neutralization process, (3) mixing characteristics of the precipitate to ensure that plutonium would remain homogeneously mixed with gadolinium, and (4) potential separation of plutonium and gadolinium during nitric and formic acids addition. A number of experiments were conducted at the Savannah River National Laboratory to study the behavior of plutonium and gadolinium at various stages of the disposition process.

Andrew, Vincent

2005-01-04

397

Gadolinium-DTPA-enhanced magnetic resonance imaging of musculoskeletal infectious processes  

Microsoft Academic Search

The purpose of this study was to assess whether gadolinium-enhanced magnetic resonance imaging (MRI) provides diagnostic information beyond that given by nonenhanced imaging in the evaluation of musculoskeletal infectious processes and whether it can be used for differentiating infectious from noninfectious inflammatory lesions. Magnetic resonance images performed with and without intravenous gadolinium-DTPA in 34 cases in which musculoskeletal infection had

Katharine L. Hopkins; King C. P. Li; Gabrielle Bergman

1995-01-01

398

Nephrogenic systemic fibrosis after exposure to gadolinium in patients with renal failure  

Microsoft Academic Search

Background. Nephrogenic systemic fibrosis is a debil- itating disease occurring exclusively in patients with renal failure. The aetiology of nephrogenic systemic fibrosis is unclear, but recent reports suggest that exposure to gadolinium for enhancement of magnetic resonance imaging may play a role. In the present study, we assessed the association of exposure to gadolinium with the development of nephrogenic systemic

Jennifer B. Othersen; John C. Maize; Robert F. Woolson; Milos N. Budisavljevic

399

Raman spectroscopic study of synthesized Na-bearing majoritic garnets  

NASA Astrophysics Data System (ADS)

Majoritic garnets in diamond have been considered as the sample from mantle transition zone (e.g. Moore and Gurney, 1985). For non-destructive, in-situ Raman analysis, Gillet et al. (2002) systematically checked chemistry and Raman peak of various majoritic garnets in diamond. They treated majoritic component as number of excess-silica than 3.0 per formula unit. However, in the basaltic system, majorite garnets also have significant amounts of Na. Na substitution is coupled with Si and Ti as follows; Na +Ti = Ca +Al (Ringwood and Lovering, 1970), Na +Si = Ca + Al (Sobolev and Labrentav, 1971; Ringwood and Major, 1971) or Na + Si = Mg + Al (Gasparik, 1989). Each component in garnet is defined as follows; Mj (majorite) component = ((Si-3)-Na)/2), NaSi (Na2MSi5O12 where M= Ca, Mg, Fe2+) component = (Na-T)/2, and NaTi component = Ti/2. Okamoto and Maruyama (2003) conducted UHP experiments in the MORB + H2O system (KNCFMATSH) at 10-19 GPa. They show that 1) Mj and NaTi component are constant and lower than 0.1 at T = 900 \\deg C, and 2) NaSi component increases drastically above 15 GPa although it is neglibly small at P<15 GPa. Raman spectra was newly analyzed using Okamoto and Maruyama (2003)'s run charges. Above 15 GPa, there is a characteristic sharp peak at 910 cm-1 and broad shoulder between 800 and 900 cm-1 as well as broad band near 960 cm-1. Gillet et at (2002) concluded that the former peak at 910cm-1 is the only reliable signature for the majoritic garnet (Si>3). They also implied that the latter two broad peaks are diagnostic feature for Ti rich garnet (> 1wt% of TiO2) as well as peak at 1030 cm-1. However, in all P range (10-19 GPa) of the present study, TiO2 is higher than 1wt%, and there is a peak at 1030 cm-1. Additional Ti-free experiment at 16 GPa, 1200 \\deg C clearly revealed that Na-bearing majoritic garnet has a significant shoulder at 800-900 cm-1. Ref; Gasparik (1989) CMP, 102,389, Gillet et al. (2002) Am.Min., 87, 312, Moore and Gurney (1985)Nature, 318, 553, Okamoto and Maruyama (2003)PEPI, in press, Ringwood and Lovering (1970) EPSL, 7, 371, Ringwood and Major (1971)EPSL, 12, 411, Sobolev and Labrentav (1971)CMP, 31, 1.

Okamoto, K.

2003-12-01

400

“Bull's-eye” sign on gadolinium-enhanced magnetic resonance venography determines thrombus presence and age: A preliminary study  

Microsoft Academic Search

Purpose: Venous thrombosis is associated with a significant inflammatory response, which can be visualized by gadolinium magnetic resonance venography (MRV). Gadolinium extravasates into tissue during inflammation, producing perithrombus enhancement on magnetic resonance scanning. This study determines (1) whether gadolinium enhancement occurs during deep venous thrombosis (DVT); and (2) whether this enhancement changes with time and can therefore establish the age

James B. Froehlich; Martin R. Prince; Lazar J. Greenfield; L. Joseph Downing; Nikhil L. Shah; Thomas W. Wakefield

1997-01-01

401

Gallium-cooled liquid metallic-fueled fast reactor  

Microsoft Academic Search

We have examined the effects on core characteristics of using two different types of Pu-based metallic alloy fuels in the gallium-cooled fast reactor core. In the proposed concept, the liquid metal fast nuclear reactor uses metallic fuel in the liquid phase and gallium coolant at high temperature (inlet 1700K, outlet 1900K). The liquid fuel is continuously supplied to the reactor

T. Sawada; A. Netchaev; H. Ninokata; H. Endo

2000-01-01

402

Generator for ionic gallium-68 based on column chromatography  

DOEpatents

A physiologically acceptable solution of gallium-68 fluorides, having an activity of 0.1 to 50 millicuries per milliliter of solution is provided. The solution is obtained from a generator comprising germanium-68 hexafluoride bound to a column of an anion exchange resin which forms gallium-68 in situ by eluting the column with an acid solution to form a solution containing .sup.68 Ga-fluorides. The solution then is neutralized prior to administration.

Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

1981-01-01

403

Complexometric determination of gallium with calcein blue as indicator  

USGS Publications Warehouse

A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1 % and a relative standard deviation of about 0.4% for 10 mg of gallium. ?? 1967.

Elsheimer, H.N.

1967-01-01

404

Applying Lu-Hf garnet geochronology and inverse phase equilibria modeling to migmatites  

NASA Astrophysics Data System (ADS)

Garnet-bearing assemblages are common in HT metamorphic rocks and are widely used to determine P-T conditions. Garnet is also a host for accessory minerals that may be used to determine the timing of garnet growth or breakdown. However, using accessory minerals to date garnet in HT metamorphic rocks may produce ambiguous or erroneous age results if these minerals were grown or modified subsequently due to fluid or melt infiltration along microfractures. Direct dating of garnet using the Sm-Nd and/or Lu-Hf isotope systems potentially avoids these problems. However, at temperatures above the solidus, the Sm-Nd isotope composition of garnet may become homogenized during post-peak cooling and evidence of prograde growth may be removed. The Lu-Hf isotope system in garnet is more robust and less susceptible to diffusion-controlled re-equilibration. Therefore, Lu-Hf dating of garnet has the potential to constrain the period of prograde garnet growth in HT metamorphic rocks. In the Fosdick migmatite-granite complex of West Antarctica, two episodes of HT garnet growth have been proposed based on U-Pb monazite ages from garnet-bearing migmatitic paragneisses and orthogneisses and U-Pb zircon ages from spatially associated peraluminous granites. Cores of monazite inclusions in garnet yield Carboniferous ages whereas the rims yield Cretaceous ages, and the garnet itself records Cretaceous Sm-Nd ages. The Sm-Nd ages were interpreted to represent diffusional resetting during the Cretaceous of garnet that grew in the Carboniferous. In this study, Lu-Hf garnet geochronology is used to test the hypothesis that garnet in the migmatitic paragneisses and orthogneisses is Carboniferous in age. We also assess the utility of the Lu-Hf system for dating garnet growth in rocks that have experienced superimposed HT metamorphic events. In addition, inverse phase equilibria modeling of open system melting is used to constrain the P-T conditions of garnet growth in migmatitic paragneisses and orthogneisses. In inverse modeling, melt is reintegrated into a residual bulk chemical composition in a stepwise fashion along a credible prograde P-T path to generate a plausible sub-solidus composition. This procedure generates a series of P-T pseudosections that may be used to constrain the P-T conditions of garnet growth. Garnet from across the Fosdick complex yields Lu-Hf ages of 115 to 111 Ma. The melt-reintegrated pseudosections show the onset of garnet growth at ~800°C between 0.6 and 1.0 GPa, with garnet growth continuing to the estimated peak P-T of 830-870°C at 0.6-0.75 GPa. Sm-Nd garnet ages of 102-99 Ma determined from a subset of the same samples overlap the range of U-Pb monazite ages (111 to 96 Ma) retrieved from these rocks. We interpret the monazite ages to date growth as trapped melt crystallized during cooling to the solidus whereas we interpret the Sm-Nd garnet ages to record diffusion-controlled re-equilibration during cooling. The results of this study demonstrate that: 1) Lu-Hf garnet geochronology can be used to successfully date garnet growth in deep crustal migmatites; and 2) garnet growth in the Fosdick complex occurred during the Cretaceous, which implies lower peak P-T conditions for the Carboniferous event than previously believed.

Yakymchuk, C.; Brown, M.; Vervoort, J. D.

2013-12-01

405

Wafer bonding of gallium arsenide on sapphire  

NASA Astrophysics Data System (ADS)

Three-inch (100) gallium arsenide wafers were bonded to ( 1/line{1} 02) sapphire in a micro-cleanroom at room temperature under hydrophilic or hydrophobic surface conditions. Subsequent heating up to 500 °C increased the bond energy of the GaAs-on-sapphire (GOS) wafer pair close to the fracture energy of the bulk material. The bond energy was measured as a function of the temperature. Since the thermal expansion coefficients of GaAs and sapphire are close to each other, the bonded wafer pair is stable against thermal treatment and quenching in liquid nitrogen. During heating in different gas atmospheres, macroscopic interface bubbles and microscopic imperfections were formed within the bonding interface, which were analysed by transmission electron microscopy (TEM). These interface bubbles can be prevented by hydrophobic bonding in a hydrogen atmosphere.

Kopperschmidt, P.; Kästner, G.; Senz, S.; Hesse, D.; Gösele, U.

406

Cavity optomechanics in gallium phosphide microdisks  

SciTech Connect

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8?×?10{sup 5} and mode volumes <10(?/n){sup 3}, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0?×?10{sup 4} intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5??m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2??30?kHz for the fundamental mechanical radial breathing mode at 488?MHz.

Mitchell, Matthew; Barclay, Paul E., E-mail: pbarclay@ucalgary.ca [Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada); Hryciw, Aaron C. [National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada)

2014-04-07

407

Direct band gap wurtzite gallium phosphide nanowires.  

PubMed

The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

Assali, S; Zardo, I; Plissard, S; Kriegner, D; Verheijen, M A; Bauer, G; Meijerink, A; Belabbes, A; Bechstedt, F; Haverkort, J E M; Bakkers, E P A M

2013-04-10

408

Direct Band Gap Wurtzite Gallium Phosphide Nanowires  

PubMed Central

The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

2013-01-01

409

Cathodoluminescence spectra of gallium nitride nanorods  

PubMed Central

Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896

2011-01-01

410

Gallium arsenide solar array subsystem study  

NASA Technical Reports Server (NTRS)

The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

Miller, F. Q.

1982-01-01

411

In-situ X-ray photoelectron spectroscopy study of supported gallium oxide  

NASA Astrophysics Data System (ADS)

In-situ XPS study of supported gallium oxide catalysts prepared by impregnation of different metal oxides supports (SiO 2, ?-Al 2O 3, TiO 2, and MgO) has been performed. It has been found that the formation of metallic gallium takes place upon high-temperature reduction of the catalysts in flowing hydrogen. Relative concentrations of metallic gallium were most high in the cases of alumina- and titania-supported catalysts. It was suggested that interaction of gallium oxide with a support surface favors the formation of metallic gallium upon high-temperature reduction. A possible mechanism of metallic gallium formation upon the reduction is discussed.

Serykh, Alexander I.; Amiridis, Michael D.

2010-06-01

412

Gadolinium Thin Foils in a Plasma Panel Sensor as an Alternative to 3He  

SciTech Connect

Gadolinium has long been investigated as a detector for neutrons. It has a thermal neutron capture cross-section that is unparalleled among stable elements, because of the isotopes $^{155,157}$Gd. As a replacement for $^3$He, gadolinium has a significant defect, it produces many gamma-rays with an energy sum of 8 MeV. It also produces conversion electrons, mostly 29 keV in energy. The key to replacing $^3$He with gadolinium is using a gamma-blind electron detector to detect the conversion electrons. We suggest that coupling a layer of gadolinium to a Plasma Panel Sensor (PPS) can provide highly efficient, nearly gamma-blind detection of the conversion. The PPS is a proposed detector under development as a dense array of avalanche counters based on plasma display technology. We will present simulations of the response of prototypes of this detector and considerations of the use of gadolinium in the PPS.

Varner Jr, Robert L [ORNL; Beene, James R [ORNL; Friedman, Dr. Peter S. [Integrated Sensors, LLC

2010-01-01

413

Inhalation developmental toxicology studies: Gallium arsenide in mice and rats  

SciTech Connect

Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

1990-12-01

414

Role of the gallium scan in Hodgkin's disease  

SciTech Connect

The reports of 240 gallium scans on 165 patients with Hodgkin's disease were reviewed to compare results with higher doses with those in earlier studies that employed lower doses. Tracer concentrations in specific sites were correlated with radiologic and pathologic reports and with the clinical courses of the patients studied. There were no significant differences in overall results between newer and older gallium scanning techniques. For untreated patients, the overall sensitivity was only 64%, but the overall specificity was 98%. For untreated patients and for patients with relapsing disease, the presence of gallium concentration in a specific site was highly predictive of active Hodgkin's disease at that site. However, for routine follow-up of treated patients, 95% of unsuspected relapses were missed by the scan, indicating the limited usefulness of negative scan results in this setting. For patients with residual abnormalities after therapy, demonstrated by other radiographic means, increased uptake of gallium in abdominal or peripheral lymph nodes also indicated active disease, although lack of uptake was reliable only in the mediastinum. Based on these results, it appears that the higher doses used in this study have not substantially improved the role of gallium scanning in this disease. Although it is potentially useful in providing confirmatory data at diagnosis or in patients with new or residual objective abnormalities after treatment, routine use of gallium scanning in Hodgkin's disease is not recommended.

Hagemeister, F.B.; Fesus, S.M.; Lamki, L.M.; Haynie, T.P. (Univ. of Texas, M.D. Anderson Cancer Center, Houston (USA))

1990-03-01

415

Studies of MRI relaxivities of gadolinium-labeled dendrons  

NASA Astrophysics Data System (ADS)

In cancer detection, imaging techniques have a great importance in early diagnosis. The more sensitive the imaging technique and the earlier the tumor can be detected. Contrast agents have the capability to increase the sensitivity in imaging techniques such as magnetic resonance imaging (MRI). Until now, gadolinium-based contrast agents are mainly used for MRI, and show good enhancement. But improvement is needed for detection of smaller tumors at the earliest stage possible. The dendrons complexed with Gd(DOTA) were synthesized and evaluated as a new MRI contrast agent. The longitudinal and transverse relaxation effects were tested and compared with commercial drug Magnevist, Gd(DTPA).

Pan, Hongmu; Daniel, Marie-Christine

2011-05-01

416

Magnetoresistance of polycrystalline gadolinium with varying grain size  

NASA Astrophysics Data System (ADS)

In this paper, we report a study of evolution of low field magnetoresistance (MR) of Gadolinium as the grain size in the sample is changed from few microns (˜4 ?m) to the nanoscopic regime (˜35 nm). The low field MR has a clear effect on varying grain size. In large grain sample (few ?m), the magnetic domains are controlled by local anisotropy field determined mainly by the magnetocrystalline anisotropy. The low field MR clearly reflects the temperature dependence of the magnetocrystalline anisotropy. For decreasing gain size, the contribution of spin disorder at the grain boundary increases and enhances the local anisotropy field.

Chakravorty, Manotosh; Raychaudhuri, A. K.

2015-01-01

417

Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles  

SciTech Connect

Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

Mukherjee, A., E-mail: soumen.basu@phy.nitdgp.ac.in; Banerjee, M., E-mail: soumen.basu@phy.nitdgp.ac.in; Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur-713209 (India); Pal, M. [CSIR-Central Mechanical Engineering Research Institute, Durgapur-713209 (India)

2014-04-24

418

Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

Mukherjee, A.; Banerjee, M.; Basu, S.; Pal, M.

2014-04-01

419

Dual-Energy X-Radiography With Gadolinium Filter  

NASA Technical Reports Server (NTRS)

Image resolution increased, and cost reduced. Proposed dual-energy x-ray imaging system, continuous bremsstrahlung spectrum from x-ray tube filtered by foil of nonradioactive gadolinium or another rare-earth metal to form two-peaked energy spectrum. After passing through patient or object under examination, filtered radiation detected by array of energy-discriminating, photon-counting detectors. Detector outputs processed to form x-ray image for each peak and possibly enhanced image based on data taken at both peaks.

Rutt, Brian

1987-01-01

420

The effect of free gallium and gallium in liposomes on cytokine and nitric oxide secretion from macrophage-like cells in vitro.  

PubMed

The aim of this study was to evaluate the effect of gallium nitrate, gallium-nitrilotriacetate (NTA) complex, and liposomal gallium-NTA on IL-6, TNF alpha, and nitric oxide (NO) release from activated macrophages. In addition, the expression of the inducible nitric oxide synthase (iNOS) was determined. Gallium inhibited dose-dependently the secretion of IL-6, TNF alpha, and NO from the LPS-induced macrophage-like RAW 264 cells. Encapsulation of gallium in negatively charged DSPG-liposomes increased its potency 10-50 times and 7-11 times compared to free gallium nitrate and gallium-NTA, respectively. Neither non-loaded liposomes nor NTA alone inhibited cytokine or NO secretion, demonstrating that the observed effects originated from gallium. Liposomal gallium-NTA inhibited the expression of iNOS by the macrophages, while other formulations of gallium had no effect. Thus, gallium, when delivered properly, suppresses macrophage functions by inhibiting the release of inflammatory mediators from the cells. PMID:8788232

Makkonen, N; Hirvonen, M R; Savolainen, K; Lapinjoki, S; Mönkkönen, J

1995-12-01

421

Gadolinium-hydrogen ion exchange of zirconium phosphate  

NASA Technical Reports Server (NTRS)

The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.

Liu, D. C.; Power, J. L.

1972-01-01

422

Observation of Neutrons with a Gadolinium Doped Water Cerenkov Detector  

E-print Network

Spontaneous and induced fission in Special Nuclear Material (SNM) such as 235U and 239Pu results in the emission of neutrons and high energy gamma-rays. The multiplicities of and time correlations between these particles are both powerful indicators of the presence of fissile material. Detectors sensitive to these signatures are consequently useful for nuclear material monitoring, search, and characterization. In this article, we demonstrate sensitivity to both high energy gamma-rays and neutrons with a water Cerenkov based detector. Electrons in the detector medium, scattered by gamma-ray interactions, are detected by their Cerenkov light emission. Sensitivity to neutrons is enhanced by the addition of a gadolinium compound to the water in low concentrations. Cerenkov light is similarly produced by an 8 MeV gamma-ray cascade following neutron capture on the gadolinium. The large solid angle coverage and high intrinsic efficiency of this detection approach can provide robust and low cost neutron and gamma-ray detection with a single device.

S. Dazeley; A. Bernstein; N. S. Bowden; R. Svoboda

2008-08-02

423

Hepatobiliary MR Imaging with Gadolinium Based Contrast Agents  

PubMed Central

The advent of gadolinium-based “hepatobiliary” contrast agents offers new opportunities for diagnostic MRI and has triggered a great interest for innovative imaging approaches to the liver and bile ducts. In this review article we will discuss the imaging properties of the two gadolinium-based hepatobiliary contrast agents currently available in the USA, gadobenate dimeglumine and gadoxetic acid, as well as important pharmacokinetic differences that affect their diagnostic performance. We will review potential applications, protocol optimization strategies, as well as diagnostic pitfalls. A variety of illustrative case examples will be used to demonstrate the role of these agents in detection and characterization of liver lesions as well as for imaging the biliary system. Changes in MR protocols geared towards optimizing workflow and imaging quality will also be discussed. It is our aim that the information provided in this article will facilitate the optimal utilization of these agents, and will stimulate the reader‘s pursuit of new applications for future benefit. PMID:22334493

Frydrychowicz, Alex; Lubner, Meghan G.; Brown, Jeffrey J.; Merkle, Elmar M.; Nagle, Scott K.; Rofsky, Neil M.; Reeder, Scott B.

2011-01-01

424

Gadolinium dose enhancement studies in microbeam radiation therapy.  

PubMed

Microbeam radiation therapy (MRT) is an innovative technique to treat brain tumors. The synchrotron generated x-ray beam, used for the treatment, is collimated and delivered in an array of narrow micrometer-sized planar rectangular fields. Several preclinical experiments performed at the Brookhaven National Laboratory (BNL) and at the European Synchrotron Radiation Facility (ESRF) have shown the sparing effect of the healthy tissue and the ablation of tumors in several animal models. It has also been determined that MRT yields a higher therapeutic index than nonsegmented beams of the same energy. This therapeutic index could be greatly improved by loading the tumor with high atomic number (Z) contrast agents. In this work, the dose enhancement factors and the peak to valley dose ratios (PVDRs) are assessed for different gadolinium (Z = 64) concentrations in the tumor and different microbeam energies by using Monte Carlo simulations (PENELOPE 2006 code). A significant decrease in the PVDR values in the tumor, and therefore a relevant increase in the dose deposition, is found in the presence of gadolinium. The optimum energy for the dose deposition in the tumor while keeping a high PVDR in the healthy tissues, which guaranties their sparing, has been investigated. PMID:19746791

Prezado, Y; Fois, G; Le Duc, G; Bravin, A

2009-08-01

425

Observation of Neutrons with a Gadolinium Doped Water Cerenkov Detector  

E-print Network

Spontaneous and induced fission in Special Nuclear Material (SNM) such as 235U and 239Pu results in the emission of neutrons and high energy gamma-rays. The multiplicities of and time correlations between these particles are both powerful indicators of the presence of fissile material. Detectors sensitive to these signatures are consequently useful for nuclear material monitoring, search, and characterization. In this article, we demonstrate sensitivity to both high energy gamma-rays and neutrons with a water Cerenkov based detector. Electrons in the detector medium, scattered by gamma-ray interactions, are detected by their Cerenkov light emission. Sensitivity to neutrons is enhanced by the addition of a gadolinium compound to the water in low concentrations. Cerenkov light is similarly produced by an 8 MeV gamma-ray cascade following neutron capture on the gadolinium. The large solid angle coverage and high intrinsic efficiency of this detection approach can provide robust and low cost neutron and gamma-ray...

Dazeley, S; Bowden, N S; Svoboda, R

2008-01-01

426

Dielectric and magnetic properties of some gadolinium silica nanoceramics  

SciTech Connect

Some nanostructure gadolinium silica glass-ceramics were obtained undergoing a sol gel method and a heat-treatment at 1000°C about two hours. The magnetic and dielectric properties of these samples were studied. The magnetic properties were evidenced performing susceptibility measurements in the 80-300K temperature range. A Curie-Weiss behavior has acquired. The values estimated for paramagnetic Curie temperature being small and positive suggest the presence of weak ferromagnetic interactions between Gd{sup 3+} ions. The dielectric properties were evaluated from dielectric permittivity (?{sub r}) and dielectric loss (tan?) measurements at the frequency 1 kHz, 10 kHz and 100 kHz, in the 25-225°C temperature range and dielectric dispersion at room temperature for 79.5 kHz - 1GHz frequency area. The dielectric properties suggest that the main polarization mechanism corresponds to interfacial polarization, characteristic for polycrystalline-structured dielectrics. The polycrystalline structure of the samples is due to the polymorphous transformations of the nanostructure silica crystallites in the presence of gadolinium oxide. They were highlighted by SEM micrographs.

Coroiu, I., E-mail: coroiu@phys.utcluj.ro; Pascuta, P., E-mail: coroiu@phys.utcluj.ro; Bosca, M., E-mail: coroiu@phys.utcluj.ro; Culea, E., E-mail: coroiu@phys.utcluj.ro [Technical University, Chemical and Physics Department, 28, Memorandumului, 400114, Cluj-Napoca (Romania)

2013-11-13

427

Annealing behaviour of P-type layers formed by ion-implantation of gallium in silicon  

Microsoft Academic Search

The number of charge carriers in gallium implanted as a function of annealing temperature is related to the formation of neutral complexes. Corresponding differences in penetration depth of gallium atoms are noted.

K. Bulthuis; R. Tree

1969-01-01

428

Application of ultrasound in solvent extraction of nickel and gallium  

SciTech Connect

The effects of ultrasound on the rate of solvent extraction of nickel with Lix 65N and Lix 70, and gallium with Kelex 100 were investigated. These solvent extraction systems are noted by their sluggish nature. Low frequency (20 kHz) ultrasound increased the rates of extraction of nickel by factors of four to seven. The ultrasound had no effect on the final chemical equilibrium. Gallium extraction rates were enhanced with the use of ultrasound by as much as a factor of 15. Again, the ultrasound had no effect on extraction equilibrium. For both nickel and gallium, the enhanced rates were attributed to increased interfacial surface area associated with ultrasonically induced cavitation and microdroplet formation. The stability of the microdroplets permitted intermittent application of ultrasound with corresponding decreases in ultrasonic energy requirements. The lowest energy consumption was observed with short (0.25 to 5 s) bursts of high power (41 to 61 W) ultrasonic inputs. The study also provided insight into the factors that affect the complex extraction of gallium from sodium aluminate solutions. The rate controlling step was found to be the dehydration of the gallate ion, Ga(OH)4, and the first complex formation between gallium and Kelex 100. Sodium was found to enhance the extraction rate up to a point, beyond which increased concentration was detrimental. Increasing aluminum concentration was found to slow extraction rates. Modifiers and diluents were shown to markedly affect extraction rates even without ultrasound. Ketone modifiers, particularly 2-undecanone, when used with Kermac 470B or Escaid 200 diluents enhanced extraction rates of gallium to the point that the use of ultrasound provided no additional benefits. The positive effects of ketone modifiers for the solvent extraction of gallium had not been previously reported.

Pesic, B.

1996-07-01

429

Timing and duration of garnet granulite metamorphism in magmatic arc crust, Fiordland, New Zealand  

USGS Publications Warehouse

Pembroke Granulite from Fiordland, New Zealand provides a window into the mid- to lower crust of magmatic arcs. Garnet Sm-Nd and zircon U-Pb ages constrain the timing and duration of high-P partial melting that produced trondhjemitic high Sr/Y magma. Trace element zoning in large, euhedral garnet is compatible with little post growth modification and supports the interpretation that garnet Sm-Nd ages of 126.1??2.0 and 122.6??2.0. Ma date crystal growth. Integration of the garnet ages with U-Pb zircon ages elucidates a history of intrusion(?) and a protracted period of high-temperature metamorphism and partial melting. The oldest zircon ages of 163 to 150. Ma reflect inheritance or intrusion and a cluster of zircon ages ca. 134. Ma date orthopyroxene-bearing mineral assemblages that may be magmatic or metamorphic in origin. Zircon and garnet ages from unmelted gneiss and garnet reaction zones record garnet granulite facies metamorphism at 128 to 126. Ma. Peritectic garnet and additional zircon ages from trondhjemite veins and garnet reaction zones indicate that garnet growth and partial melting lasted until ca. 123. Ma. Two single fraction garnet ages and young zircon ages suggest continued high-temperature re-equilibration until ca. 95. Ma. Phase diagram sections constrain orthopyroxene assemblages to <0.6 GPa @ 650??C, peak garnet granulite facies metamorphic conditions to 680-815??C @ 1.1-1.4. GPa, and a P-T path with a P increase of???0.5. GPa. These sections are compatible with water contents???0.28wt.%, local dehydration during garnet granulite metamorphism, and <0.3. GPa P increases during garnet growth. Results demonstrate the utility of integrated U-Pb zircon and Sm-Nd garnet ages, and phase diagram sections for understanding the nature, duration, and conditions of deep crustal metamorphism and melting. Geochronologic and thermobarometric data for garnet granulite indicate that thickening of arc crust, which caused high-pressure metamorphism in northern Fiordland, must have occurred prior to 126. Ma, that loading occurred at a rate of ca. 0.06. GPa/m.y., and that garnet granulite metamorphism lasted 3-7m.y. Locally-derived partial melts formed and crystallized in considerably less than 10 and perhaps as little as 3m.y. ?? 2010 Elsevier B.V.

Stowell, H.; Tulloch, A.; Zuluaga, C.; Koenig, A.

2010-01-01

430

Gallium a unique anti-resorptive agent in bone: Preclinical studies on its mechanisms of action  

SciTech Connect

The discovery of gallium as a new and unique agent for the treatment of metabolic bone disorders was in part fortuitous. Gallium is an exciting new therapeutic agent for the treatment of pathologic states characterized by accelerated bone resorption. Compared to other therapeutic metal compounds containing platinum or germanium, gallium affects its antiresorptive action without any evidence of a cytotoxic effect on bone cells. Gallium is unique amongst all therapeutically available antiresorptive agents in that it favors bone formation. 18 refs., 1 fig.

Bockman, R.; Adelman, R.; Donnelly, R.; Brody, L.; Warrell, R. (Hospital for Special Surgery, New York, NY (USA)); Jones, K.W. (Brookhaven National Lab., Upton, NY (USA))

1990-01-01

431

X-ray spectroscopic identification of garnet from the placer deposits of the Taman peninsula  

NASA Astrophysics Data System (ADS)

Garnet from recent placer deposits of the Taman peninsula has been investigated by energy-dispersive X-ray fluorescence microanalysis and X-ray absorption near-edge structure (XANES) spectroscopy. Energy-dispersive X-ray fluorescence microanalysis showed that the chemical composition of the garnet under study corresponds to pyrope-almandine-spessartine series. The Fe K-edge X-ray absorption spectra of garnet have been recorded using a Rigaku R-XAS laboratory spectrometer. Iron K-edge XANES spectra for two iron-containing garnet minals (components), almandine and andradite, have been calculated using the full multiple-scattering and finite-difference methods. Based on a comparison of the experimental and theoretical Fe K-XANES spectra, it is concluded that recent magnetite-garnet placer deposits of the Taman peninsula contain garnet in the form of almandine.

Rodina, I. S.; Kravtsova, A. N.; Soldatov, A. V.; Yalovega, G. E.; Popov, Yu. V.; Boyko, N. I.

2013-12-01

432

Fluid-aided incorporation of Y into almandine-pyrope garnet via coupled dissolution-reprecipitation  

NASA Astrophysics Data System (ADS)

In nature almandine-pyrope garnet is a well-known host for a variety of trace elements including (Y+HREE), Sr, HFSE, as well as LREE such as Sm and Nd; all of which have important roles with regard to various geological processes (Kohn, 2009, GCA, 73, 170). For example, Y exchange between xenotime and garnet has been empirically calibrated as a geothermometer (Pyle and Spear, 2000, CMP, 138, 51). Sm/Nd and Lu/Hf dating, using garnet, is a well-known geochronometer (Thöni et al., 2008, Chem Geol, 254, 216). In general, REE + HFSE + Sr have been used to chart garnet growth and subsequently the evolution of the host rock (Konrad-Schmolke et al., 2008, EPSL, 272, 488). Incorporation of Y into garnet is probably the most widely studied trace element. These studies range from stress-induced redistribution of Y in garnet (Røhr et al, 2007, Am Mineral, 92, 1276) to Y zoning during garnet growth (Zeh, 2005, J Petrol, 47, 2335). While the incorporation of Y into garnet has generally been thought to occur either via diffusion or during garnet growth, more recent workers have suggested that incorporation of Y could also be fluid-aided. Fluid-aided incorporation of Y into garnet has been tested in the piston-cylinder apparatus (CaF2 assemblies, cylindrical graphite ovens) at 1000 MPa and 900 °C (8 days duration). Here, 10 mg of 50-200 µm size, inclusion-free, gem quality, fragments of the Gore Mountain garnet (Alm40-49, Py37-43, Gr13-16, Sp1) plus 5 mg 2N NaOH and 2 mg Y2O3 were loaded into a 3 mm diameter, 1 cm long, Au capsule that was then arc-welded shut and placed vertically in the CaF2 assembly such that the NiCr thermocouple tip came halfway up along the Au capsule length. Examination of the garnet fragments after the experiment indicates both high Y mobility and the partial alteration of the garnet in the form of a remobilized Y3Al5O12 component enriching those areas of the garnet along the grain rim. The enriched areas take the form of a series of intergrowths with sharp compositional boundaries, which appear to be defined by specific lattice planes as determined by the crystallographic axes of the garnet. These textures are the result of coupled dissolution-reprecipitation (Putnis, 2002, Min Mag, 66, 689), which essentially has resulted in the pseudomorphic partial replacement of a portion of the original garnet by a re-precipitated garnet now enriched in Y. The result from this study suggest that Y may be incorporated into garnet by the aid of fluids, which are both reactive with garnet and in which Y is mobile. In general, this result has strong implications with respect to incorporation of REE (and more specifically HREE) into garnet. It provides a mechanism by which garnet and other Y-bearing minerals, such as xenotime, may equilibrate hence enhancing their use as geothermometers. It also indicates that with respect to both Sm/Nd and Lu/Hf dating, the garnet geochronometer can be reset. More importantly, it implies that diffusion after or inclusion during garnet growth is not the only way by which trace elements may be incorporated into garnet.

Harlov, D. E.

2009-12-01

433

Gallium based low-interaction anions  

DOEpatents

The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

King, Wayne A. (Santa Fe, NM); Kubas, Gregory J. (Santa Fe, NM)

2000-01-01

434

Optical absorption coefficient of magneto-optic garnet films  

SciTech Connect

This paper analyzes various factors contributing to optical attenuation in magneto-optic garnet films and derives expressions for the optical absorption and scattering coefficients ..cap alpha.. and ..gamma... The values of ..cap alpha.. and ..gamma.. for (BiTm)/sub 3/(FeGa)/sub 5/O/sub 12/ films were measured in a magneto-optic modulation device by comparing the magneto-optic rotations. Compared with other methods, this technique has two advantages: (1) absorption in the substrate is eliminated, and the measured values ..cap alpha.. are not affected by reflection at the film/substrate interface; (2) the optical scattering coefficient ..gamma.. can be separated from the optical absorption ..cap alpha.., so that the measured value ..cap alpha.. closely approximates the true optical absorption coefficient for magneto-optic garnet film materials.

Liu Gong-qiang; Yu Zhi-qiang; Liu Xianglin

1986-02-01

435

OH and H2O of garnets in diamond-bearing and diamond-free garnet-clinopyroxene rocks from the Kumdy-kol area, Kokchetav Massif  

NASA Astrophysics Data System (ADS)

Garnet-clinopyroxene (Grt-Cpx) rocks consisting mainly of Grt + Na-poor Cpx + calcite with various proportions, occur in the Kumdy-kol area. Diamond-bearing Grt-Cpx rock was first reported by Sobolev and Shatsky (1990) and has been well-known as one of the Kokchetav diamond-bearing rocks. UHP evidence, e.g., coesite exsolution from supersilicic titanite, was discovered also in the diamond-free Grt-Cpx rock (Inoue and Ogasawara, 2003). Presence/lack of diamond in Grt-Cpx rocks is one of important features to understand the stability of diamond in the Kokchetav UHP calcsilicate and carbonate rocks. We focused on OH and H2O in garnets in two types of Grt-Cpx rock to clarify fluid conditions during UHP metamorphism. One of the samples, the diamond-bearing Grt-Cpx rock (sample no. 25018; provided by Prof. H.-P. Schertl) is composed of two monomineralic layers, Grt-layer and Cpx-layer, with minor amounts of rutile and calcite. Coarse-grained diamond (up to 0.15 mm across) is included in garnet. Another Grt-Cpx rock, diamond-free one (sample no. XX16) shows a glanoblastic texture, and consists of Grt (30 %) + Cpx (30 %) + calcite (30 %) × titanite (5 %) with exsolved coesite-needles and plates. The precursor supersilicic compositions of titanite indicate six-coordinated Si at UHP conditions (Ogasawara et al, 2002; Sakamaki and Ogasawara, IGR in press). To understand the fluid environments during the formation of these two calcsilicate rocks, we chose garnets and conducted micro FT-IR spectroscopy. IR spectra of garnets in the diamond-bearing Grt-Cpx rock showed OH bands at 3430 and 3570 cm-1, sometimes with a week band at 3675 cm-1. The absorption band at 3570 cm-1 is the strongest and is sharp, whereas the band at 3430 cm-1 is broad. IR spectra of garnets in diamond-free one show strong OH bands at 3400 and 3555 cm-1, sometimes with week bands at 3590 and 3640 cm-1. The OH band at 3555 cm-1 is the strongest and is sharp, whereas the band at 3400 cm-1 is broad. IR analyses of garnets in the Grt-Cpx rocks show bimodal spectra; the relatively sharp band at ~3550 cm-1 and the broad band at ~3400 cm-1. The former band is attributed to OH in garnet structure and the latter one molecular H2O. The similar bimodal spectra were obtained from garnet in diamond-bearing dolomite marble. When we regard the total absorption at the range of 3100-3750 cm-1 as structural OH, the garnets in diamond-bearing Grt-Cpx rock contain 797 to 2506 ppm wt. H2O, and those in the diamond-free Grt-Cpx rock contain 679 to 2169 ppm wt. H2O. To evaluate the absorption spectra of the garnets in the Grt-Cpx rocks, we analyzed the garnet of different origin, Cr- and pyrope-rich garnet in mantle peridotite from the Garnet Ridge, northern Arizona. This peridotitic garnet shows a single-modal absorption band of OH at 3575 cm-1. No molecular H2O band was detected. Such results suggest that the environment during Kokchetav UHP metamorphism of calcsilicate may be saturated in H2O in contrast with the peridotitic garnet from the Garnet Ridge. The molecular H2O in the garnets of the Kokchetav Grt-Cpx rocks probably is submicron fluid inclusions trapped during UHP metamorphism. We thank Prof. H.-P. Schertl for providing us a very precious sample, diamond-bearing garnet-clinopyroxene rock.

Sakamaki, K.; Ogasawara, Y.

2013-12-01

436

Pure silver ohmic contacts to N- and P- type gallium arsenide materials  

DOEpatents

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, Stephen J. (Golden, CO)

1986-01-01

437

Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials  

DOEpatents

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, S.J.

1983-03-13

438

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

E-print Network

#12;Unusual strategies for using indium gallium nitride grown on silicon (111) for solid with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements solid-state lighting transfer printing Indium gallium nitride-based (InGaN) blue light emitting diodes

Rogers, John A.

439

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

E-print Network

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements solid-state lighting transfer printing Indium gallium nitride-based (InGaN) blue light emitting diodes

Choquette, Kent

440

LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM  

E-print Network

703 LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM LINES, accepte Ie 19 fivrier 1987) Résumé : Les élargissements Stark de raies du gallium et de l'indium neutre cathode liquide utilisant un mélange sodium-indium ou potassium-gallium, la densité electronique pouvant

Paris-Sud XI, Université de

441

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells  

E-print Network

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with a larger number of vacancies, that facilitates indium and gallium diffusion, in the sodium free films

Rockett, Angus

442

Fabrication of Large-Area Graphene Using Liquid Gallium and Its Electrical Properties  

Microsoft Academic Search

We demonstrated a new process for synthesizing a graphene sheet at the interface between solid amorphous carbon and liquid gallium. The insolubility of carbon in gallium strongly restricted the depth of graphitization, but a multilayered graphene sheet having four to six layers of graphene was produced over the entire area of the interface immediately beneath the liquid gallium. We also

Jun-ichi Fujita; Yosuke Miyazawa; Ryuichi Ueki; Mio Sasaki; Takeshi Saito

2010-01-01

443

Optical phenomena in bismuth-substituted ferrite-garnet films in external electric field  

Microsoft Academic Search

Magneto-electric properties of bismuth-substituted ferrite-garnet epitaxial films and yttrium ferrite-garnet films have been investigated by using optical polarimetry method, electromagneto-optical (EMO) effect. The EMO effect in the transverse electric ( E) field was measured. In the yttrium ferrite-garnet films, the EMO effect in the specified geometry is not registered, though in a longitudinal E-field, it was observed by us. The

V. E. Koronovskyy

2009-01-01

444

Martian mantle primary melts - An experimental study of iron-rich garnet lherzolite minimum melt composition  

NASA Technical Reports Server (NTRS)

The minimum melt composition in equilibrium with an iron-rich garnet lherzolite assemblage is ascertained from a study of the liquidus relations of iron-rich basaltic compositions at 23 kb. The experimentally determined primary melt composition and its calculated sodium content reveal that Martian garnet lherzolite minimum melts are picritic alkali olivine basalts. Martian primary melts are found to be more picritic than terrestrial garnet lherzolite primary melts.

Bertka, Constance M.; Holloway, John R.

1988-01-01

445

Improved dissolution and chemical separation methods for Lu-Hf garnet chronometry  

Microsoft Academic Search

Garnet-based Lu-Hf geochronology using conventional (HF-HNO3) dissolution methods may be compromised by full or partial digestion of Hf-rich zircon inclusions. This study integrates two complimentary methods to substantially reduce zircon digestion while assuring complete digestion of garnet and sample-spike equilibration. Handpicked garnet fractions are heat treated to >1000°C in an evacuated silica glass ampoule to anneal zircon inclusions and then

J. N. Connelly

2006-01-01

446

Anisotropic magnetic properties of dysprosium iron garnet (DyIG)  

Microsoft Academic Search

The magnetic properties of dysprosium iron garnet (DyIG) have been studied by performing high resolution powder neutron diffraction experiments and high dc fields magnetizations on single crystals. Among all the reflections (hkl) indexed in the nuclear cubic space group (CSG) Ia bar 3 d with h+k+l=2n and k=[000], the superstructure lines (hkl)* forbidden by the symmetry (222)* and (622)* are

M. Lahoubi; W. Younsi; M.-L. Soltani; B. Ouladdiaf

2010-01-01

447

Calcium-poor garnet in relation to metamorphism  

Microsoft Academic Search

1. (1) The writer has carried out a systematic study of pyralspites (calcium-poor garnets) in pelitic metamorphic rocks of the Gosaisyo-Takanuki district. With the increase in metamorphic grade of their host-rocks, the MnO content of the pyralspites decreases, while the FeO content increases. Accompanying the variations in composition, the edge length of the unit cell of the minerals shortens and

Akiho Miyashiro

1953-01-01

448

Nuclear Bragg diffraction of synchrotron radiation in yttrium iron garnet  

Microsoft Academic Search

Monochromatization of synchrotron radiation down to about 10 neV at an energy of 14.4 keV has been achieved by double nuclear Bragg diffraction from (Fe-57)-yttrium iron garnet single-crystal films set for the electronically forbidden 200 plane-type reflection. The monochromatized gamma quanta have been analyzed with respect to time delay and capability of resonance absorption. By setting appropriate energy and time

E. Gerdau; R. Rueffer; H. Winkler; W. Tolksdorf; C. P. Klages; J. P. Hannon

1985-01-01

449

Magnetooptical effects in bismuth-containing ferrite-garnet films  

Microsoft Academic Search

We present results of magnetooptical investigations of bismuth-containing ferrite-garnet films with the easy axis of magnetization parallel to the specimen surface. Measurements were conducted for incident light with energies in the range 1.5–3.2 eV for transverse [equatorial Kerr effect (EKE)] and for longitudinal [meridional intensity effect (MIE)] magnetizations of thin-layer specimens. It is shown that the EKE differs from zero

G. S. Krinchik; E. E. Chepurova; I. M. Kuznetsova; N. V. Pronina

1989-01-01

450

The solubility of alumina in orthopyroxene coexisting with garnet  

Microsoft Academic Search

The solubility of alumina in complex orthopyroxenes crystallised in equilibrium with garnet has been determined over the pressure-temperature range 8–30 Kb and 800–1250° C. The results are in good agreement with predictions made using the simple thermodynamic model of Wood and Banno (1973). The model has been refined using a combination of the new data on orthopyroxenes of about En60Fs40

Bernard J. Wood

1974-01-01

451

Charnockite geobarometers based on coexisting garnet-pyroxene-plagioclase-quartz  

Microsoft Academic Search

Numerous geothermometers based on compositions of coexisting minerals have been calibrated experimentally or theoretically during the past 10 yr. In contrast, few continuous-reaction geobarometers exist which have had wide application. One, based on the reaction of cordierite to garnet, sillimanite and quartz, is limited by a relatively narrow pressure range of application and also by conflicting calibrations1,2 because the mixing

D. Perkins; R. C. Newton

1981-01-01

452

Nonlinear dynamic magnetization regimes in (100) ferrite-garnet films  

SciTech Connect

To study the nonlinear dynamics of a uniformly precessing magnetization in perpendicularly magnetized (100) ferrite-garnet films, equations of motion are numerically solved over a wide ac field frequency range. Bifurcation changes in the magnetization precession and the states of dynamic bistability have been detected. The conditions of high-amplitude regular and stochastic dynamic regimes are revealed, and the possibilities of controlling these precession regimes by applied magnetic fields are shown.

Shutyi, A. M., E-mail: shuty@mail.ru; Sementsov, D. I. [Ul'yanovsk State University (Russian Federation)], E-mail: sementsovdi@ulsu.ru

2007-05-15

453

Realization of the Gallium Triple Point at NMIJ/AIST  

NASA Astrophysics Data System (ADS)

The triple point of gallium has been realized by a calorimetric method using capsule-type standard platinum resistance thermometers (CSPRTs) and a small glass cell containing about 97 mmol (6.8 g) of gallium with a nominal purity of 99.99999%. The melting curve shows a very flat and relatively linear dependence on 1/ F in the region from 1/ F = 1 to 1/ F = 20 with a narrow width of the melting curve within 0.1 mK. Also, a large gallium triple-point cell was fabricated for the calibration of client-owned CSPRTs. The gallium triple-point cell consists of a PTFE crucible and a PTFE cap with a re-entrant well and a small vent. The PTFE cell contains 780 g of gallium from the same source as used for the small glass cell. The PTFE cell is completely covered by a stainless-steel jacket with a valve to enable evacuation of the cell. The melting curve of the large cell shows a flat plateau that remains within 0.03 mK over 10 days and that is reproducible within 0.05 mK over 8 months. The calibrated value of a CSPRT obtained using the large cell agrees with that obtained using the small glass cell within the uncertainties of the calibrations.

Nakano, T.; Tamura, O.; Sakurai, H.

2008-02-01

454

Preliminary Spectroscopic Measurements for a Gallium Electromagnetic (GEM) Thruster  

NASA Technical Reports Server (NTRS)

As a propellant option for electromagnetic thrusters, liquid ,gallium appears to have several advantages relative to other propellants. The merits of using gallium in an electromagnetic thruster (EMT) are discussed and estimates of discharge current levels and mass flow rates yielding efficient operation are given. The gallium atomic weight of 70 predicts high efficiency in the 1500-2000 s specific impulse range, making it ideal for higher-thrust, near-Earth missions. A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma and estimate electron temperature. The spectra show that neutral, singly, and doubly ionized gallium species are present in a 20 J, 1.8 kA (peak) are discharge. With graphite present on the insulator to facilitate breakdown, singly and doubly ionized carbon atoms are also present, and emission is observed from molecular carbon (CZ) radicals. A determination of the electron temperature was attempted using relative emission line data, and while the spatially and temporally averaged, spectra don't fit well to single temperatures, the data and presence of doubly ionized gallium are consistent with distributions in the 1-3 eV range.

Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

2007-01-01

455

Sublattice Magnetic Relaxation in Rare Earth Iron Garnets  

SciTech Connect

The magnetic properties of rare earth garnets make them attractive materials for applications ranging from optical communications to magnetic refrigeration. The purpose of this research was to determine the AC magnetic properties of several rare earth garnets, in order to ascertain the contributions of various sublattices. Gd3Fe5O¬12, Gd3Ga5O12, Tb3Fe5O12, Tb3Ga5O12, and Y3Fe5O12 were synthesized by a solid state reaction of their oxides and verified by x-ray diffraction. Frequency-dependent AC susceptibility and DC magnetization were measured versus temperature (10 – 340 K). Field cooling had little effect on AC susceptibility, but large effect on DC magnetization, increasing magnetization at the lowest temperature and shifting the compensation point to lower temperatures. Data suggest that interaction of the two iron lattices results in the two frequency dependent magnetic relaxations in the iron garnets, which were fit using the Vogel-Fulcher and Arrhenius laws.

McCloy, John S.; Walsh, Brian

2013-07-08

456

Garnet geochemistry of tungsten-mineralized Xihuashan granites in South China  

NASA Astrophysics Data System (ADS)

The Xihuashan complex intrusion in South China, which is emplaced at ca. 154 Ma, mainly comprises medium-grained porphyritic biotite granite, medium-grained biotite granite, and fine-grained two-mica granite. Medium-grained biotite and fine-grained two-mica granites are important tungsten-bearing granites and contain an unusual amount of garnet. Garnets from this intrusion are dominated by almandine and spessartine, which constitute 94% to 99% of the total molecular composition of the garnet. These garnets display unusual compositional zoning. The cores of these garnets are rich in heavy rare earth element (HREE), Y, Ca, and contain abundant HREE- and Y-rich mineral inclusions. Their rims are free of mineral inclusions and have low of these elements. Two types of fluorite inclusions exist in garnet: Y fluorite and Y-poor fluorite. Garnet exhibits specific Mn zoning with a relatively Mn-poor core but a relatively Mn-rich rim, thus constituting a specific “spessartine inverse bell-shaped profile” that belongs to typical magmatic garnets. All analyzed garnets have high REE content and exhibit HREE-enriched and LREE-depleted patterns with strong negative Eu anomalies. The incorporation of REE into garnet is in part controlled by its crystal chemistry, with REE3 + following a coupled substitution of the type [Fe2 +,Mn2 +]- 1VIII[REE3 +]+ 1VIII[Si4 +]- 1IV[Z3 +]+ 1IV. The texture and compositional zoning of garnet suggest that garnet growth is largely controlled by the pressure-temperature-composition condition of magmatic evolution, internal crystal-chemical parameters, and kinetics during mineral growth. The garnet core grows in near equilibrium with magmatic melt under a relatively high pressure-temperature (P-T) condition. By contrast, the garnet rim grows rapidly by the coexisting melt-fluid phase and CO2-rich volatile environment under a relatively low P-T condition, which is virtually unfavorable for the incorporation of REE into the magmatic garnet structure. Garnet fingerprints the magmatic-hydrothermal transition during crystallization of these granites.

Yang, Jie-hua; Peng, Jian-tang; Hu, Rui-zhong; Bi, Xian-wu; Zhao, Jun-hong; Fu, Ya-zhou; Shen, Neng-Ping

2013-09-01

457

Self-Diffusion in gallium arsenide  

NASA Astrophysics Data System (ADS)

The self-diffusion of arsenic in gallium arsenide has been studied over the temperature range 1000 to 1075?C using radiotracer techniques.76As was diffused into GaAs samples at known arsenic pressures in sealed capsules. After diffusion, layers were removed from the surface using anodic oxidation followed by oxide dissolution. Diffusion profiles were obtained by measuring the76As concentration in each sectioned layer by ?-radiation counting. Diffusion coefficients at PAs 2 = 0.75 atm and over the temperature range 1000 to 1050?C were found to be 5.2 × 10-16cm2s-1 to 1.5 × 10-15 cm2s-1, leading to an activation energy of the order of 3.0± 0.04 eV and a pre-exponential factor of 5.5 × l0-4 ± 2.4 × 10-4 cm2s-1. Diffusion coefficients at PAs 2 =3.0 atm were found to be 5.5 × 10-15 and 9.8 × 10-16 cm2 s-1 at 1050 and 1075?C, respectively. Results are discussed in terms of native point defect equilibria with the arsenic gaseous phase, and with respect to other work. It is deduced from our observed arsenic pressure dependence of the arsenic diffusivity that the most likely diffusion mechanism

Palfrey, H. D.; Brown, M.; Willoughby, A. F. W.

1983-09-01

458

Gallium arsenide photo-field emission  

NASA Astrophysics Data System (ADS)

The development of monochromatic ultrafast electron sources with high brightness and high coherence is increasingly important in both time-resolved and energy-resolved electron microscopy. This work details the fabrication of intrinsic Gallium-Arsenide photo-field emitters and their evaluation as potential source candidates. The emitters were prepared via chemical etching and vacuum heat cleansing of cleaved wafer shards that had been mounted in refractory metal holders. Data were recorded in the form of field emission images, current-voltage characteristic curves and energy distribution curves under several different thermal and illumination conditions. As expected, illumination increased emission by 3 orders of magnitude. However a much larger than expected energy distribution of 0.76 eV was observed. This result invalidated presumptions that the band structure would produce a maximum energy width equal to the energy bandgap minus the photon energy. Following the experiment a Spicer-like 3-step model was used to explain this discrepancy. In the model the energy broadening is attributed to a combination of bulk thermal effects and surface band bending. Using this model, predictions are made as to the performance of a similar photo-field emitter that should better fulfill the needs of both time-resolved and energy-resolved electron microscopy.

Vecchione, Theodore

459

Synthesis and characterization of gallium colloidal nanoparticles.  

PubMed

In this work, gallium colloidal nanoparticles (Ga-Nps) were synthesized by chemical liquid deposition (CLD). This method involved the deposition of metallic atoms with organic solvents (THF, acetone and 2-propanol) in a freezing matrix of the solvent at 77K, in order to obtain core-shell Ga-Nps which were characterized by: FT-IR, UV-Vis, TEM, SAED and electrophoretic mobility measurements. TEM images revealed a wide distribution of the apparent size of the particles and apparent average size of 5.65, 8.11 and 13.87 nm for Ga-Nps obtained with 2-propanol, THF and acetone, respectively. UV spectra showed absorption bands of metal plasmons, interesting quantum size effects and plasmon absorption bands of particles aggregated to lambda(280) and lambda(325). Electrophoretic mobility allowed to evidence that nanoparticles had a negative charge as well as to observe that the zeta potential of the colloidal dispersions decreased over time, showing a significant tendency to the aggregation of Ga-Nps. The importance of the functionalization of metal nanoparticles with high dielectric constant solvents in the stabilization of colloidal systems was also observed. FT-IR spectroscopy revealed that the interaction of Ga surface with the solvent possibly produces a (GaC) bond. Experimental details, structural and thermal stability studies were also analyzed in this work. PMID:20378122

Meléndrez, M F; Cárdenas, G; Arbiol, J

2010-06-15

460

Gallium nitride micromechanical resonators for IR detection  

NASA Astrophysics Data System (ADS)

This paper reports on a novel technology for low-noise un-cooled detection of infrared (IR) radiation using a combination of piezoelectric, pyroelectric, electrostrictive, and resonant effects. The architecture consists of a parallel array of high-Q gallium nitride (GaN) micro-mechanical resonators coated with an IR absorbing nanocomposite. The nanocomposite absorber converts the IR energy into heat with high efficiency. The generated heat causes a shift in frequency characteristics of the GaN resonators because of pyroelectric effect. IR detection is achieved by sensing the shift in the resonance frequency and amplitude of the exposed GaN resonator as compared to a reference resonator that is included in the array. This architecture offers improved signal to noise ratio compared with conventional pyroelectric detectors as the resonant effect reduces the background noise and improves sensitivity, enabling IR detection with NEDTs below 5 mK at room temperature. GaN is chosen as the resonant material as it possesses high pyroelectric, electrostrictive, and piezoelectric coefficients and can be grown on silicon substrates for low-cost batch fabrication. Measured results of a GaN IR detector prototype and a thin-film nanocomposite IR absorber are presented in this paper.

Rais-Zadeh, Mina

2012-06-01

461

Photoluminescence study of gallium vacancy defects in gallium arsenide irradiated by relativistic protons  

SciTech Connect

Epitaxially grown n-type gallium arsenide films, doped with silicon to concentrations of 2 {times} 10{sup 15} and 2 {times} 10{sup 16} cm{sup {minus}3} were exposed at room temperature to 200, 350, and 500 MeV proton irradiation at fluences of 3 {times} 10{sup 11}, 10{sup 12}, 10{sup 13}, 3 {times} 10{sup 13}, 10{sup 14} and 10{sup 15} cm{sup {minus}2}. The effects of the irradiation were determined through low temperature continuous photoluminescence spectroscopy. Two radiation-induced donor-to-acceptor transitions were observed. The one at 1.476 eV has been associated to the gallium vacancy acceptor (V{sub Ga}) and the other at 1.482 eV to the silicon at the arsenic site acceptor (Si{sub As}). The relative introduction rate of these two defects has been measured in the irradiated samples before and after annealing at 550 C for 30 minutes. The introduction rates are higher than those predicted by relativistic elastic scattering cross-section theory in the energy range studied here. The authors conclude that inelastic scattering contributes to the cross-section. The introduction rates are lower than nonionizing energy loss (NIEL) calculations in the 200 to 500 MeV energy range. They suggest that the proton inelastic scattering parameter used in NIEL needs revision. The relativistic inelastic scattering formula is closer to experiment than present NIEL calculations.

Carlone, C.; Parenteau, M. [Univ. de Sherbrooke, Quebec (Canada). Dept. de Physique] [Univ. de Sherbrooke, Quebec (Canada). Dept. de Physique; Houdayer, A.; Hinrichsen, P. [Univ. de Montreal, Quebec (Canada). Dept. de Physique] [Univ. de Montreal, Quebec (Canada). Dept. de Physique; Vincent, J. [TRIUMF, Vancouver, British Columbia (Canada)] [TRIUMF, Vancouver, British Columbia (Canada)

1997-12-01

462

Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium  

E-print Network

Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-like to liquid behavior at the same critical acid concentration, thereby quantitatively confirming that the wettability of these liquid metals is due to the oxide skin.

Qin Xu; Nikolai Qudalov; Qiti Guo; Heinrich Jaeger; Eric Brown

2012-01-23

463

Gallium plasmonics: deep subwavelength spectroscopic imaging of single and interacting gallium nanoparticles.  

PubMed

Gallium has recently been demonstrated as a phase-change plasmonic material offering UV tunability, facile synthesis, and a remarkable stability due to its thin, self-terminating native oxide. However, the dense irregular nanoparticle (NP) ensembles fabricated by molecular-beam epitaxy make optical measurements of individual particles challenging. Here we employ hyperspectral cathodoluminescence (CL) microscopy to characterize the response of single Ga NPs of various sizes within an irregular ensemble by spatially and spectrally resolving both in-plane and out-of-plane plasmonic modes. These modes, which include hybridized dipolar and higher-order terms due to phase retardation and substrate interactions, are correlated with finite difference time domain (FDTD) electrodynamics calculations that consider the Ga NP contact angle, substrate, and native Ga/Si surface oxidation. This study experimentally confirms previous theoretical predictions of plasmonic size-tunability in single Ga NPs and demonstrates that the plasmonic modes of interacting Ga nanoparticles can hybridize to produce strong hot spots in the ultraviolet. The controlled, robust UV plasmonic resonances of gallium nanoparticles are applicable to energy- and phase-specific applications such as optical memory, environmental remediation, and simultaneous fluorescence and surface-enhanced Raman spectroscopies. PMID:25629392

Knight, Mark W; Coenen, Toon; Yang, Yang; Brenny, Benjamin J M; Losurdo, Maria; Brown, April S; Everitt, Henry O; Polman, Albert

2015-02-24

464

Native gallium adatoms discovered on atomically-smooth gallium nitride surfaces at low temperature.  

PubMed

In advanced compound semiconductor devices, such as in quantum dot and quantum well systems, detailed atomic configurations at the growth surfaces are vital in determining the structural and electronic properties. Therefore, it is important to investigate the surface reconstructions in order to make further technological advancements. Usually, conventional semiconductor surfaces (e.g., arsenides, phosphides, and antimonides) are highly reactive due to the existence of a high density of group V (anion) surface dangling bonds. However, in the case of nitrides, group III rich growth conditions in molecular beam epitaxy are usually preferred leading to group III (Ga)-rich surfaces. Here, we use low-temperature scanning tunneling microscopy to reveal a uniform distribution of native gallium adatoms with a density of 0.3%-0.5% of a monolayer on the clean, as-grown surface of nitrogen polar GaN(0001?) having the centered 6 × 12 reconstruction. Unseen at room temperature, these Ga adatoms are strongly bound to the surface but move with an extremely low surface diffusion barrier and a high density saturation coverage in thermodynamic equilibrium with Ga droplets. Furthermore, the Ga adatoms reveal an intrinsic surface chirality and an asymmetric site occupation. These observations can have important impacts in the understanding of gallium nitride surfaces. PMID:25656811

Alam, Khan; Foley, Andrew; Smith, Arthur R

2015-03-11

465

Some interesting features of the Tb3+ magnetooptics in the paramagnetic garnets  

NASA Astrophysics Data System (ADS)

The spectra of the absorption, luminescence, magnetic circular dichroism (MCD) and magnetic circular polarization of luminescence (MCPL) in the terbium-yttrium gallium garnet Tb3+:Y3Ga5O12 (Tb:YGG) have been studied within the visible and near ultraviolet (UV) spectral range for temperatures T = 85 and 300 K. The MCD spectrum observed within the UV absorption band for Tb:YGG is associated with spin- and parity-allowed electric-dipole 4f ? 5d transitions occurring between levels of the ground 7F6 multiplet and the 7D state of the excited 4f(7)5d configuration of the Tb3+ ion. Analysis of the spectral and the temperature dependences of the magnetooptical and optical spectra has made it possible to identify magneto-optically-active 4f ? 4f transitions occurring between Stark sublevels of the 5D4 and 7F5 multiplets in Tb3+:YGG. Quantum mechanical "mixing" of the three lowest energy Stark singlets in the excited 5D4 multiplet by an external magnetic field H leads to the change of the circularly polarized luminescence line intensities. The Zeeman effect in the UV absorption band 7F6 ? 5L10 of Tb3+:YGG at T = 85 K was also studied. The magnetic field dependence of the Zeeman splitting of some absorption lines is found to exhibit unusual behavior: as the magnetic field increases, the band splitting decreases rather than increases. A parameterized Hamiltonian defined to operate within the entire 4f(8) ground electronic configuration of Tb3+ was used to model the experimental Stark levels, their irreducible representations (irreps.) and wave functions. The crystal-field parameters were determined using a Monte-Carlo method in which nine independent crystal-field parameters, were given random initial values and optimized using standard least-squares fitting between calculated and experimental levels. The final fitting standard deviation between 101 calculated and experimental Stark levels is 16.7 cm-1.

Valiev, Uygun V.; Gruber, John B.; Burdick, Gary W.; Mukhammadiev, Anvar K.; Fu, Dejun; Pelenovich, Vasiliy O.

2014-05-01

466

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

E-print Network

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium properties of liquid gallium and eutectic gallium-indium Phys. Fluids 24, 063101 (2012); 10); 10.1063/1.3670048 Evaluation of gallium-indium alloy as an acoustic couplant for high-impedance, high

Deseri, Luca

467

Elastic scattering of electrons by gadolinium and barium atoms  

NASA Astrophysics Data System (ADS)

Total and differential cross-sections for elastic scattering of electrons from gadolinium and barium atoms in a wide energy range were calculated. In the low- and intermediate-energy regions, the phase theory of elastic scattering was used. At low incident energies (<10 eV), an additional polarization potential was introduced. At high incident energies, the Born approximation (keV range) and the Rutherford formula (MeV range) were applied. Our results are in rather good agreement with experimental data of Romanyuk et al. (Pis'ma Zh. Eksp. Teor. Fiz. 32 (1980) 472) for elastic scattering of very-low-energy electrons from barium atoms which confirm its reliability. This agreement is important because these experimental results are in serious disagreement with theoretical calculations of Szmytkowski and Sienkiewicz (Phys. Rev. A 50 (1994) 4007).

Miloshevsky, G. V.; Tolkach, V. I.; Rozin, S.; Shani, G.

2000-08-01

468

Mechanism of inhibition of ribonucleotide reductase with motexafin gadolinium (MGd)  

SciTech Connect

Motexafin gadolinium (MGd) is an expanded porphyrin anticancer agent which selectively targets tumor cells and works as a radiation enhancer, with promising results in clinical trials. Its mechanism of action is oxidation of intracellular reducing molecules and acting as a direct inhibitor of mammalian ribonucleotide reductase (RNR). This paper focuses on the mechanism of inhibition of RNR by MGd. Our experimental data present at least two pathways for inhibition of RNR; one precluding subunits oligomerization and the other direct inhibition of the large catalytic subunit of the enzyme. Co-localization of MGd and RNR in the cytoplasm particularly in the S-phase may account for its inhibitory properties. These data can elucidate an important effect of MGd on the cancer cells with overproduction of RNR and its efficacy as an anticancer agent and not only as a general radiosensitizer.

Zahedi Avval, Farnaz; Berndt, Carsten; Pramanik, Aladdin [Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-17177 Stockholm (Sweden); Holmgren, Arne [Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-17177 Stockholm (Sweden)], E-mail: arne.holmgren@ki.se

2009-02-13

469

Luminescence and photosensitivity of gadolinium labeled hematoporphyrin monomethyl ether.  

PubMed

Photodynamic therapy for deep-lying lesions needs an appropriate imaging modality, precise evaluation of tissue oxygen and an effective photosensitizer. Gadolinium based metalloporphyrins Gd(III)-HMME is proposed in this study as a potential multifunctional theranostic agent, as photosensitizer, ratiometric oxygen sensor and MRI contrast agent. The time resolved spectroscopy revealed the luminescence peak of Gd(III)-HMME at 710 and 779 nm with a lifetime of 64 ?s in oxygen-free methanol to be phosphorescent. This phosphorescence is strongly dependent on dissolved oxygen concentration. Its intensity in oxygen saturated methanol solution is 21% of that in deoxygenated solution. The singlet oxygen quantum yields ?? of HMME and Gd(III)-HMME in air saturated methanol solution were determined to be 0.79 and 0.40 respectively using comparative spectra method. These phenomena indicate that the oxygen sensibility and production of singlet oxygen of Gd(III)-HMME can fulfill the requirement of PDT treatment. PMID:24663532

Wang, Peng; Qin, Feng; Wang, Li; Li, Fajun; Zheng, Yangdong; Song, Yunfei; Zhang, Zhiguo; Cao, Wenwu

2014-02-10

470

SWI enhances vein detection using gadolinium in multiple sclerosis  

PubMed Central

Susceptibility weighted imaging (SWI) combined with the FLAIR sequence provides the ability to depict in vivo the perivenous location of inflammatory demyelinating lesions – one of the most specific pathologic features of multiple sclerosis (MS). In addition, in MS white matter (WM) lesions, gadolinium-based contrast media (CM) can increase vein signal loss on SWI. This report focuses on two cases of WM inflammatory lesions enhancing on SWI images after CM injection. In these lesions in fact the CM increased the contrast between the parenchyma and the central vein allowing as well, in one of the two cases, the detection of a vein not visible on the same SWI sequence acquired before CM injection.

Mazzoni, Lorenzo N; Moretti, Marco; Grammatico, Matteo; Chiti, Stefano; Massacesi, Luca

2015-01-01

471

Gadolinium chloride-induced shifts in intrahepatic distributions of liposomes.  

PubMed

Intravenously administered gadolinium chloride caused only a slight decrease in the rate of elimination of small unilamellar liposomes from the blood and had no influence on the total hepatic uptake of these vesicles, but did alter their intrahepatic distribution substantially. Uptake by the non-parenchymal cells was substantially decreased, whereas uptake by the parenchymal cells showed a concomitant increase. Our earlier observations (Roerdink et al. (1981) Biochim. Biophys. Acta 677, 79-89) on the effect of lanthanides on the in vivo distribution of multilamellar liposomes have been extended, in that we demonstrate, in addition to the drop in elimination rate from the blood and in the over-all hepatic uptake, a shift of liposome distribution within the Kupffer cell population. While the larger Kupffer cells, which normally take up a major fraction of an injected liposome dose, were strongly inhibited in liposome uptake, the more numerous small macrophages showed a 3-4-fold increase in uptake. PMID:2713404

Lázár, G; van Galen, M; Scherphof, G L

1989-05-10

472

High concentration of gadolinium ion modifying isolated rice mitochondrial biogenesis.  

PubMed

Mitochondria play an important role in plant growth and development, cooperating with the endoplasmic reticulum and nucleus. Gadolinium, one of the rare earth elements, is an inhibitor of stretch-activated calcium channels located on the endoplasmic reticulum and plasma membrane and has no effect on nuclear calcium variation in plant cells. We analyzed the effects of Gd3+ on mitochondria function by monitoring mitochondrial swelling, changes of membrane fluidity, and transmembrane potential collapse and by observing mitochondrial ultrastructure. We found that high concentration of Gd3+ induces rice mitochondrial dysfunction through mitochondrial permeability transition (MPT). The protection of DTT and EDTA demonstrate that Gd3+ blocks the inner membrane ion channel through thiol chelation. PMID:24078325

Zhao, Jie; Jin, Jian-Cheng; Zhou, Zhi-Qiang; Xia, Cai-Fen; Yang, Xiao-Gang; Jiang, Feng-Lei; Dai, Jie; Liu, Yi

2013-12-01

473

Strategies for the preparation of bifunctional gadolinium(III) chelators  

PubMed Central

The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications. PMID:22375102

Frullano, Luca; Caravan, Peter

2012-01-01

474

Defect induced mobility enhancement: Gadolinium oxide (100) on Si(100)  

SciTech Connect

Growth of predominantly single crystal (100)-oriented gadolinium oxide (Gd{sub 2}O{sub 3}) on a p-type Si(100) and growth of a polycrystal with a predominant Gd{sub 2}O{sub 3}(100) crystallite on a n-type Si(100) was performed using molecular beam epitaxy. Despite a poorer crystal structure than Gd{sub 2}O{sub 3}(110), an enhancement in carrier mobility can be found only from the Gd{sub 2}O{sub 3}(100)/n-type Si(100) interface. The mobility of 1715-1780 cm{sup 2}/V {center_dot} s was observed at room temperature, for carrier concentration >10{sup 20} cm{sup -3}. This accumulation of the electrons and the mobility enhancement may arise from the two-dimensional confinement due to charge transfer across the interface similar to transfer doping.

Sitaputra, W. [Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223 (United States); Tsu, R. [Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223 (United States); Department of Electrical and Computer Engineering, University of North Carolina at Charlotte, Charlotte, North Carolina 28223 (United States)

2012-11-26

475

SWI enhances vein detection using gadolinium in multiple sclerosis.  

PubMed

Susceptibility weighted imaging (SWI) combined with the FLAIR sequence provides the ability to depict in vivo the perivenous location of inflammatory demyelinating lesions - one of the most specific pathologic features of multiple sclerosis (MS). In addition, in MS white matter (WM) lesions, gadolinium-based contrast media (CM) can increase vein signal loss on SWI. This report focuses on two cases of WM inflammatory lesions enhancing on SWI images after CM injection. In these lesions in fact the CM increased the contrast between the parenchyma and the central vein allowing as well, in one of the two cases, the detection of a vein not visible on the same SWI sequence acquired before CM injection. PMID:25815209

Maggi, Pietro; Mazzoni, Lorenzo N; Moretti, Marco; Grammatico, Matteo; Chiti, Stefano; Massacesi, Luca

2015-03-01

476

Endogenous contrast MRI of cardiac fibrosis: Beyond late gadolinium enhancement.  

PubMed

The aim of this review is to provide an overview of detection of cardiac fibrosis with MRI using current standards and novel endogenous MRI techniques. Assessment of cardiac fibrosis is important for diagnosis, prediction of prognosis and follow-up after therapy. During the past years, progress has been made in fibrosis detection using MRI. Cardiac infarct size can be assessed noninvasively with late gadolinium enhancement. Several methods for fibrosis detection using endogenous contrast have been developed, such as native T1 -mapping, T1? -mapping, Magnetization transfer imaging, and T2 *-mapping. Each of these methods will be described, providing the basic methodology, showing potential applications from applied studies, and discussing the potential and challenges or pitfalls. We will also identify future steps and developments that are needed for bringing these methods to the clinical practice. J. Magn. Reson. Imaging 2015;41:1181-1189. © 20