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1

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

2

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

3

[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

4

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

5

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

6

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

7

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

8

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

9

Bismuth and aluminum-substituted YIG single-crystal films on modified gadolinium gallium garnet single-crystal substrates  

Microsoft Academic Search

Bismuth- and aluminum-substituted yttrium iron garnet single-crystal films with the nominal composition of Y1.5Bi1.5Fe4.2Al0.8O12 (Bi,Al:YIG) were prepared by spin coating a gel on the (111) plane of (GdCa)3(GaMgZn)5O12 single-crystal garnet plates. Crystallinity of the films varies with temperature and time of heat treatment in air after gel coating. Single-crystal films were obtained at Ta=650 °C for 4 h. The onset

Koji Matsumoto; Satoshi Sasaki; Yasunori Yamanobe; Kazuhiro Yamaguchi; Toshitaka Fujii; Yousuke Asahara

1991-01-01

10

Thermal expansion of gallium garnets and Bi-substituted iron garnet epitaxial thick films  

NASA Astrophysics Data System (ADS)

Lattice constants and thermal expansion of several Bi-substituted rare-earth iron garnet epitaxial films (Bi-RIG; R=Gd, Dy, Yb+Tb) and Ca, Mg and Zr-doped and undoped gadolinium gallium garnet substrates (CaMgZr-GGG and GGG) were measured in the temperature range 300 to 1073 K. In the measurements on the films, the substrates have been removed to render the films free from strain. While CaMgZr-GGG exhibits thermal expansion similar to that of GGG, Bi-substitution in the RIG films increases their thermal expansion. Therefore, when the Bi-RIG films are lattice-matched to the CaMgZr-GGG substrates at room temperature, the lattice mismatch at the growth temperature, 1073 K, amounts to 0.1-0.2%.

Nakajima, K.; Machida, K.

1988-10-01

11

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

12

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

13

Faraday effect in gadolinium iron garnet  

SciTech Connect

The Faraday effect (FR) is investigated experimentally in GdIG (Gd/sub 3/Fe/sub 5/O/sub 12/) single crystals; the magnetic field up to 20 kOe was applied along the (111) direction at a wavelength of 1.15 micron. The 4.2-580 K temperature range covers all the magnetic ordering domain. The Faraday rotation reciprocal susceptibility differs strongly from that observed in other heavy rare earth garnets. In the spontaneous state the results are analyzed using the model where the Fe/sup 3+/ total contribution to FR is the same as that of YIG. At very low temperatures the Gd/sup 3+/ contribution originates from magnetic dipole contribution only; in the 25-425 K temperature range the electric dipole coefficient Ce/sup s/ presents a linear temperature dependence. At the Neel point the GdIg Faraday rotation is going to zero.

Ostorero, J.; Gall, H.L.; Guillot, M.; Marchand, A.

1986-09-01

14

Crystallization and thermal properties of rare earth gallium garnets  

Microsoft Academic Search

The density and thermal expansion of a number of rare earth gallium garnets were studied in the liquid and solid states in the regions of crystallization and melting by irradiating the samples with a narrow beam of gamma quanta. Volume changes on liquid-solid and solid-solid transitions were measured for equilibrium and nonequilibrium crystallization. The formulas for the estimation of the

S. V. Stankus; R. A. Khairulin; P. V. Tyagel'sky; I. A. Ivanov

1995-01-01

15

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

16

Investigation of Gadolinium Gallium Oxide using spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

Spectroscopic Ellipsometry (SE) is a non-destructive characterization technique used for determining film thickness, interfacial roughness and optical properties of single and multilayered materials. SE measures the change in the polarization state of the incident light upon reflection from these layers providing insight into the properties and composition of topmost and underlying materials. The Horiba Jobin Yvon - UVISEL located in the Angelo State Materials Characterization Lab is based on the principle of phase modulated spectroscopic ellipsometry. This tool has been used to successfully characterize a variety of semiconductor samples. We will detail results from semiconductor heterostructures containing Gadolinium Gallium Oxide (GdGaO3), a novel material with promise for application as a high-k dielectric in the design of compound semiconductor MOSFETs. Models for this unusual material have been developed and used to characterize various structures with success. We have obtained reasonable values for electrical and optical parameters for the GGO not found in current literature.

Bhatnagar, Kunal; Sauncy, Toni; Droopad, Ravi

2010-03-01

17

Effect of chemical composition on the thermophysical characteristics of gallium garnets  

NASA Astrophysics Data System (ADS)

The thermophysical characteristics of artificial gallium and germanium garnets are shown to be related in a simple fashion to the mean atomic weight, reflecting the cationic composition of the structure. The presence of a small additive of substitution lowers the thermal conductivity and thermal diffusivity of the garnets, and samples of intermediate composition (solid solutions) are distinguished by low values of these characteristics.

Osiko, V. V.; Petrunin, G. I.; Popov, V. G.; Timoshechkin, M. I.

18

Magnetization and FMR studies of crystal-ion-sliced narrow linewidth gallium-doped yttrium iron garnet  

NASA Astrophysics Data System (ADS)

Recent interest in employing single-crystal yttrium iron garnet (YIG) films for miniaturized microwave integrated circuit applications has prompted us to study detaching liquid phase epitaxy (LPE) grown YIG films from their gadolinium gallium garnet (GGG) substrates via crystal ion slicing (CIS). We report studies of magnetization and ferromagnetic resonance (FMR) of narrow linewidth gallium-doped YIG (GaYIG) films in various stages of separation from their <111> oriented GGG substrates. All samples were diced from the same three-inch wafer of Y3Fe4.6Ga0.4O12 with 4?Meff of 1070 G and 9.45 GHz FMR linewidth of 0.4+/-0.1 Oe. The CIS separation process involved (1) implantation with helium ions, (2) flash annealing to remove surface damage, and (3) chemical etching to detach the YIG at the implantation damaged layer. The starting films were 10.8-?m thick. Separation occurred 7 to 8 ?m from the front surface in the YIG. The implantation (5×1016 cm-2 dosage, 3.8 MeV bias) increased the uniaxial anisotropy of these films. A small cubic anisotropy (~5 G 60° in-plane periodicity) persisted in both implanted and unimplanted samples. Upon implantation the FMR linewidth increased from 0.4 to 3+/-0.5 Oe. The detached samples have linewidths ranging from 1.7 to 2.5 Oe. The temperature dependence of the linewidths is roughly exponential decreasing as the temperature is lowered for the unprocessed sample, increasing with reduced temperature for all processed samples. Post-detachment annealing restores the FMR linewidth to 0.55+/-0.5 Oe.

Rachford, F. J.; Levy, M.; Osgood, R. M.; Kumar, A.; Bakhru, H.

2000-05-01

19

A manifestation of magnetism of bismuth in iron garnet films  

Microsoft Academic Search

Bismuth iron garnet films prepared through electron-beam and laser-induced evaporation on (001)-oriented substrates of scandium\\u000a gallium gadolinium garnet are investigated using ferromagnetic resonance. It is assumed that the additional minima observed\\u000a in the angular dependence of the resonance field can be associated with the magnetic moment of bismuth ions.

V. F. Shkar’; V. P. Denisenkov; A. M. Grishin; A. A. Yalali; S. I. Khartsev; E. I. Nikolaev; V. N. Sayapin

2003-01-01

20

Self-focusing in Terbium Gallium Garnet using Z-scan  

NASA Astrophysics Data System (ADS)

When illuminated near its resonance with an Ar ion laser beam (?=488 nm), laser induced thermal self-focusing is observed in Terbium Gallium Garnet. The crystal exhibits a strong intensity dependent refractive index change ?n. The Z-scan technique is used to study the beam waist change due to ?n. The refractive index is found to be well described by a quadratic spatial distribution model. Both the sign and the distribution coefficient of ?n are determined.

Lavorel, Chen; Genetier, Dreier; Michaut, Misserey

1998-08-01

21

Evaluation of mineral content of dentin prepared by erbium, chromium:yttrium scandium gallium garnet laser  

Microsoft Academic Search

Laser etching has an effect on the mineral content of dentin. The aim of this study was to evaluate the mineral content of\\u000a dentin prepared at three different power settings with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser.\\u000a The enamel of five, lower, wisdom, molar teeth was removed to expose the dentin surface. Four dentin slabs were obtained,\\u000a then

Asli Secilmis; Subutayhan Altintas; Aslihan Usumez; Gizem Berk

2008-01-01

22

Processing of gadolinium-iron garnet under non-equilibrium conditions  

NASA Astrophysics Data System (ADS)

We have investigated the mechanosynthesis of gadolinium iron garnet (GdIG) by high-energy ball-milling of 3.(Gd2O3) + 10.( ?-Fe) followed by thermal annealing conducted at moderate temperatures (1100 °C). The samples were characterized by X-ray diffraction and Mössbauer spectroscopy in order to determine the influence of the milling time on the final products. For as-milled samples the results revealed the enlargement of the magnetic component belonging to iron and a discrete paramagnetic component. The formation of a garnet phase was observed in all as-annealed samples treated at 1100 °C for 6 h in quantities proportional to the time of grinding the precursors. Evidently, high-energy ball milling of Gd2O3 + ?-Fe powders is an important step in GdIG synthesis by a ceramic method. Single-phase garnet is observed for the samples milled for 12 and 24 h treated at 1100 °C for 6 h.

Zanatta, S. C.; Ivashita, F. F.; da Silva, K. L.; Machado, C. F. C.; Paesano, A.

2014-01-01

23

Paramagnetic Resonance of Fe3+ in Octahedral and Tetrahedral Sites in Yttrium Gallium Garnet (YGaG) and Anisotropy of Yttrium Iron Garnet (YIG)  

Microsoft Academic Search

The electron paramagnetic resonance spectrum of a small Fe3+ impurity which enters substitutionally for the gallium in single crystals of yttrium gallium garnet (chemical formula Y3Ga5O12) has been examined at 24 kMc\\/sec at 295°K and 1.6°K. Fe3+ is studied for the first time in tetrahedral coordination. The results for the crystal field parameters that appear in the usual spin Hamiltonian

S. Geschwind

1961-01-01

24

Linear birefringence control and magnetization in sputter-deposited magnetic garnet films  

Microsoft Academic Search

Birefringence control is essential in the fabrication of on-chip magnetooptic Faraday isolators. We report on film thickness and stress studies of birefringence in sputter-deposited single-layer bismuth-substituted iron garnet films and double-layer iron garnet films with gadolinium gallium garnet (GGG) covers. We examine compressively and tensilely strained films and analyze the photoelastic response of the sputter-deposited garnet films. We show that

H. C. Yang; M. Levy; R. Li; P. D. Moran; C. J. Gutierrez; A. K. Bandyopadhyay

2004-01-01

25

Defects in laser crystals of rare-earth aluminum and gallium garnets  

SciTech Connect

Using thermodynamic and crystallochemical analysis of garnets R{sub 3}Ga{sub 5}O{sub 12}(R=Sm - Lu, Y) and R{sub 3}Al{sub 5}O{sub 12} (R = Gd - Lu, Y) and their solid solutions, we characterized point defects present in their structure and, for the first time, estimated their contents. We showed that the garnets under consideration contain cationic defects and oxygen vacancies: (1) In aluminum garnets R{sub 3}Al{sub 5}O{sub 12}, improper-valence ions form at octahedral sites. (2) In gallium garnets R{sub 3}Ga{sub 5}O{sub 12} and Ga-containing solid solutions, there are Ga vacancies at octahedral sites. (3) In Dy{sub 3}(Ga{sub c}Al{sub 1-c}){sub 5}O{sub 12} solid solutions, in addition to the above-mentioned defects typical of gallium garnets, antistructural, substitutional defects (Ga{sup 3+}{sub IV}) are present. The Ga{sup 3+}ions occupy preferentially octahedra; that is, they exhibit a higher affinity for octahedral coordination than Alk{sup 3+} ions, in agreement with Goldschmidt`s crystallochemical approach. The refined solid-solution ranges for R{sub 3}Ga{sub c}Al{sub 1-c}{sub 5}O{sub 12}(R=Nd,Sm,Eu,Gd) are 0.75 {le}c{le} 1 for Nd, 0.5 {le}c{le} 1 for Sm, 0.4 {le}c{le} 1 for Eu, and 0.25 {le}c{le} 1 for Gd.

Vorob`ev, Yu.P.; Goncharov, O.Yu. [Physicotechnical Institute, Izhevsk (Russian Federation)

1994-12-01

26

Adhesion after erbium, chromium:yttrium-scandium-gallium-garnet laser application at three different irradiation conditions  

Microsoft Academic Search

The aim of this study was to investigate whether distinct cooling of low fluence erbium, chromium:yttrium-scandium-gallium-garnet\\u000a (Er,Cr:YSGG) laser irradiation would influence adhesion. Main factors tested were: substrates (two), irradiation conditions\\u000a (three), and adhesives (three). A 750 ?m diameter tip was used, for 50 s, 1 mm from the surface, with a 0.25 W power output,\\u000a 20 Hz, energy density of 2.8 J\\/cm2 with energy per pulse

Sérgio Brossi Botta; Patricia Aparecida da Ana; Denise Maria Zezell; John M. Powers; Adriana Bona Matos

2009-01-01

27

In vitro evaluation of erbium, chromium:yttrium–scandium–gallium–garnet laser-treated enamel demineralization  

Microsoft Academic Search

This study evaluated the effect of different parameters of erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser\\u000a irradiation on enamel mineral loss in a simulated caries model. Forty-five enamel samples obtained from third molar teeth\\u000a (3 mm×?3 mm) were randomly divided into five groups (n?=?9): G1—Er,Cr:YSGG laser at 0.25 W, 20 Hz, 2.8 J\\/cm2; G2—Er,Cr:YSGG laser at 0.50 W, 20 Hz, 5.7 J\\/cm2; G3—Er,Cr:YSGG laser at 0.75 W, 20 Hz, 8.5 J\\/cm2; G4—sodium fluoride (NaF)

Patrícia M. de Freitas; Marcia Rapozo-Hilo; Carlos de P. Eduardo; John D. B Featherstone

2010-01-01

28

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

29

Thin film sputtering of gadolinium and chromium-doped yttrium aluminum garnet  

NASA Astrophysics Data System (ADS)

In this work, rf magnetron reactive sputtering was used to synthesize yttrium aluminum garnet (YAG) thin films at relatively low temperature and short processing period. A combination of 80W for yttrium target, 130W for aluminum target, and a total pressure of 3 mTorr gas mixtures with 25 sccm argon and 1.4 sccm oxygen flow rate produced a Y3Al5 O12 stoichiometric thin film. Gadolinium and chromium-doped YAG thin films were synthesized in a combinatorial fashion. The combinatorial thin film sputtering technique rapidly determined the gadolinium and chromium concentration that yielded the optimum luminescence intensity to be ˜5.5 at% for YAG:Gd and ˜0.69 at% YAG:Cr films, respectively. The concentration quenching phenomena were discussed. A 23 full factorial design of experiments (DOE) was conducted to investigate the effects of substrate temperature, substrate bias, and oxygen flow rate on the luminescence properties and the crystallinity of YAG:Gd and YAG:Cr thin films, respectively. DOE results showed that increasing O2 flow rate decreases both luminescence intensity and film crystallinity, substrate temperature slightly improves luminescence and has a negligible effect on crystallinity, and substrate bias enhances luminescence but decreases crystallinity. The effects of the parameters were thoroughly interpreted by correlating the composition and morphology of the films. Single factor studies for each variable verified the DOE results. The optimum process condition consists if low O 2 flow rate and high substrate bias. The effect of total pressure of the Ar/O2 gas mixture on CL efficiency and XRD intensity was also investigated. The PL temperature dependence of YAG:Gd and YAG:Cr thin films were studied in a temperature range of 15-298 K. The thermal quenching phenomena were observed above ˜110K on both YAG:Gd and YAG:Cr films. Activation energies of 24.7 meV and 25.2 meV were estimated for YAG:Gd and YAG:Cr films, respectively. Both activation energies were attributed to electron-phonon coupling.

Deng, Yuepeng

30

Spinwave resonance spectra of inhomogeneous bubble garnet films  

Microsoft Academic Search

Spin-wave resonance at 10 GHz has been observed in thin (? 5 mum) garnet films of approximate composition Y2.85La0.15Fe3.75Ga1.25O12. The films were grown by LPE on [111]-oriented gadolinium gallium garnet substrates, both from a nonstirred melt (vertical mode of dipping) and a stirred melt (horizontal dipping, applying axial substrate rotation). The spectra exhibit large numbers of strongly excited modes with

B. Hoekstra; R. P. van Stapele; J. M. Robertson

1977-01-01

31

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

32

Adhesion after erbium, chromium:yttrium-scandium-gallium-garnet laser application at three different irradiation conditions.  

PubMed

The aim of this study was to investigate whether distinct cooling of low fluence erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation would influence adhesion. Main factors tested were: substrates (two), irradiation conditions (three), and adhesives (three). A 750 microm diameter tip was used, for 50 s, 1 mm from the surface, with a 0.25 W power output, 20 Hz, energy density of 2.8 J/cm(2) with energy per pulse of 12.5 mJ. When applied, water delivery rate was 11 ml/min. The analysis of variance (ANOVA) showed that laser conditioning significantly decreased the bond strength of all adhesive systems applied on enamel. On dentin, laser conditioning significantly reduced bond strength of etch-and-rinse and one-step self-etch systems; however, laser irradiation under water cooling did not alter bonding of two-step self-etching. It may be concluded that the irradiation with Er,Cr:YSGG laser at 2.8 J/cm(2) with water coolant was responsible for a better adhesion to dentin, while enamel irradiation reduced bond strength, irrespective of cooling conditions. PMID:18027064

Botta, Sérgio Brossi; da Ana, Patricia Aparecida; Zezell, Denise Maria; Powers, John M; Matos, Adriana Bona

2009-01-01

33

The study of spectroscopic and luminescence properties of disordered laser crystals calcium niobium gallium garnet doped with Er3+  

NASA Astrophysics Data System (ADS)

The results of spectroscopy of disordered Er-doped calcium-niobium- gallium garnets (CNGG: Er) are displayed. Based on the Judd-Ofelt theory, three intensity parameters ?t (t=2, 4, 6) for Er ions concentration from 6 at. % in these crystals were obtained. The oscillator strength for hypersensitivity transition 4I15/2-->2H11/2 and intensity parameter ?2 of Er3+ ions in CNGG: Er crystals are higher than corresponding values for other Er-doped garnets. These results we explain by the presence in these crystals of optical centers Er with the environment symmetry lower than D2. Gain crosssection for laser transition 4I13/2 --> 4I15/2 of Er3+ ions was obtained using absorption and emission cross-data for transition 4I15/2 --> 4I13/2 and 4I13/2 --> 4I15/2 respectively.

Ryabochkina, P. A.; Voronko, Yu. K.; Malov, A. V.; Marychev, M. O.; Sobol, A. A.; Ushakov, S. N.; Chuprunov, E. V.

2008-05-01

34

Evaluation of mineral content of dentin prepared by erbium, chromium:yttrium scandium gallium garnet laser.  

PubMed

Laser etching has an effect on the mineral content of dentin. The aim of this study was to evaluate the mineral content of dentin prepared at three different power settings with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser. The enamel of five, lower, wisdom, molar teeth was removed to expose the dentin surface. Four dentin slabs were obtained, then each tooth was randomly divided into four portions (groups 1 W, 2 W, 3 W and control) so that we could evaluate the effect of laser treatment. The Er,Cr:YSGG laser used for the study had a pulse duration of 140 micros, a pulse repetition rate of 20 Hz and a power output range of 0 W to 6 W. Laser energy was delivered through a fiberoptic system to a sapphire tip terminal 6 mm long and 600 microm in diameter, using a non-contact mode. The levels of five elements: magnesium (Mg), phosphorus (P), calcium (Ca), potassium (K), and sodium (Na), in each slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were significant differences between the groups (1 W, 2 W, 3 W and control) for Ca, Mg, Na, P and Ca/P ratio (P<0.05); however, there were no significant differences for K (P=0.43). Laser treatment at 1 W significantly affected the mean percentage weight of all element groups except K. Scanning electron microscopy (SEM) photographs indicated that the surface irregularities increased with increasing power setting. PMID:17952486

Secilmis, Asli; Altintas, Subutayhan; Usumez, Aslihan; Berk, Gizem

2008-10-01

35

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

36

Growth of terbium gallium garnet (TGG) magneto-optic crystals by edge-defined film-fed growth method  

NASA Astrophysics Data System (ADS)

Although terbium gallium garnet (TGG) single crystals suitable for practical applications have been grown by the Czochralski technique due to its congruent melting nature, the interface shape readily deteriorates to spiral growth when grown with a flat interface or facet formation when grown with a convex interface. The Edge-defined Film-fed Growth (EFG) method was used to grow TGG crystals for the first time. The influence of the raw material sintering temperature, growth atmosphere, growth rate and other growth conditions on the crystal quality were investigated. The Verdet constant of as-grown crystal was measured as 39 rad/T.m at 1064 nm by the extinction method, which was close to the literature value. The source of color centers in the crystals is also discussed.

Zhuang, Naifeng; Song, Caigen; Guo, Liwei; Wang, Rongfeng; Hu, Xiaolin; Zhao, Bin; Lin, Shukun; Chen, Jianzhong

2013-10-01

37

LPE growth of yttrium–lutetium, indium–gallium garnet films for optical waveguide formation on a GGG substrate  

Microsoft Academic Search

Yttrium–lutetium, indium–gallium garnet single-crystal films with a composition of {YxLu3?x}[Yy1Luy2Iny3Ga2?y1?y2?y3](Ga3)O12(0?x?3,y1=0.02x,y2=0.12?0.04x,y3=1.08?0.11x) were grown on ?111?- oriented GGG substrate by the LPE technique in order to fabricate a planar optical waveguide. The LPE growth results and optical properties of the films are reported. It was easy to control the composition of the film, because the distribution coefficients of the solutes showed gradual

Eishi Kubota; Makoto Shimokozono; Yujiro Katoh

1998-01-01

38

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

39

Dielectric constants of yttrium and rare-earth garnets, the polarizability of gallium oxide, and the oxide additivity rule  

Microsoft Academic Search

The dielectric constants (?’) and dielectric loss values of 10 rare-earth gallium garnets and 1 rare-earth aluminum garnet were measured at 1 MHz using a two-terminal method with empirically determined edge corrections. The results are: ?’(Dy3Al5O12)=11.07±0.05; ?’(Ho3Ga5O12) =12.38±0.05; ?’(Dy3Ga5O12)=12.36±0.06; ?’(Tb3Ga5O12) =12.40 ±0.03; ?’(Gd3Ga5O12) =12.18±0.10; ?’(Eu3Ga5O12) =12.46±0.05; ?’(Sm3Ga5O12) =12.55±0.03; ?’(Nd3Ga5O12) =12.59±0.12; ?’(Y3Sc2Ga3O12) =12.94±0.03; ?’(Sm3Sc2Ga3O12) =13.67±0.04; and ?’(La2.66Lu2.66Ga2.66O12) =14.40±0.03. The dielectric polarizability

R. D. Shannon; M. A. Subramanian; T. H. Allik; H. Kimura; M. R. Kokta; M. H. Randles; G. R. Rossman

1990-01-01

40

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

41

Influence of etching with erbium, chromium:yttrium-scandium-gallium-garnet laser on microleakage of class V restoration.  

PubMed

The aim of this in vitro study was to evaluate some parameters of dental etching when irradiated with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser. One-hundred sound human third molars were selected and randomly distributed into ten groups (n = 10). The class V cavities of group 1 (control) were prepared with a bur and etched with 37% phosphoric acid, while groups G2 to G10, were prepared with laser (5 W, 88.46 J/cm(2), 90/70% air/water) and etched with the following powers: G3 and G4, 0.25 W; G5 and G6, 0.5 W; G7 and G8, 0.75 W; G9 and G10, 1 W. Group G2 received no laser etching. Prior to restoration, G2, G4, G6, G8 and G10 received acid etching. After restoration, all samples were submitted to a microleakage test. According to statistical analysis (Kruskal-Wallis and Dunn's tests), G10 presented the lowest microleakage values (P<0.05). The other groups showed no differences between them. Etching with Er,Cr:YSGG laser (1 W) followed by phosphoric acid was effective in reducing the microleakage of class V restorations. PMID:19011950

Marotti, Juliana; Geraldo-Martins, Vinícius Rangel; Bello-Silva, Marina Stella; de Paula Eduardo, Carlos; Apel, Christian; Gutknecht, Norbert

2010-05-01

42

Multisite optical spectra and energy levels of trivalent thulium ions in yttrium scandium gallium garnet  

NASA Astrophysics Data System (ADS)

Intrinsic structural disorder in scandium-substituted garnets, attributed to mixed occupancy of certain sites in the crystal lattice by different cations, has direct consequences for the optical spectra of rare-earth activator ions dispersed over multiple sites. In trivalent thulium-doped Y-Sc-Ga garnet (Tm(3+):YSGG), site-selective laser excitation spectra reveal the presence of Tm(3+) ions in regular D2 sites, disturbed regular sites, and in octahedral C(3i) sites. Absorption spectra obtained at 4 K between 0.26 and 1.85 micron are broader than those observed in more ordered crystal hosts and include structure attributed to Tm(3+) ions in sites of other than D2 symmetry. A crystal-field splitting calculation was carried out in which a parametrized Hamiltonian (including Coulombic, spin-orbit, and crystal-field terms for Tm(3+) ions in D2 symmetry) was diagonalized for all manifolds of the Tm(3+) (4f exp 12) configuration. The rms deviation between 52 experimental and calculated Stark levels of Tm(3+) in regular D2 sites was 5/cm.

Seltzer, Michael D.; Gruber, John B.; Hills, Marian E.; Quarles, Gregory J.; Morrison, Clyde A.

1993-08-01

43

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

44

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

45

The effect of an erbium, chromium: yttrium-scandium-gallium-garnet laser on the microleakage and bond strength of silorane and micro-hybrid composite restorations  

PubMed Central

Objective: The aim of this in vitro study was to compare the microleakage and bond strength of Class V silorane-based and universal micro-hybrid composite restorations prepared either with diamond bur or with an erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr:YSGG) laser. Materials and Methods: A total of 160 molar teeth were used for microleakage assessment and shear bond strength (SBS) test. The specimens were prepared using either diamond bur or 3 W-, 4 W- and 5 W-20 Hz Er, Cr:YSGG laser irradiation. All specimens were subjected to thermocycling (500 times at 5 ± 2°C to 55 ± 2°C, dwell time 15 s and transfer time 10 s). Microleakage was assessed using a 0.5% basic-fuchsin solution. The bond strengths were determined using a microtensile tester at a crosshead speed of 0.5 mm/min. The Kruskal Wallis test was used for the analysis of microleakage and a one-way analysis of variance test was used to analyze the SBS (P < 0.05). Results: No statistically significant differences were found (P > 0.05) between Er, Cr:YSGG laser and bur preparation methods regarding microleakage and bond strength values. Conclusion: Irradiation with Er, Cr:YSGG laser was confirmed to be as effective as conventional methods for preparing cavities before adhesive restorations.

Korkmaz, Fatih Mehmet; Baygin, Ozgul; Tuzuner, Tamer; Bagis, Bora; Arslan, Ipek

2013-01-01

46

Passive mode locking in garnet lasers generating at a wavelength of 1.3 micron  

NASA Astrophysics Data System (ADS)

Passive mode locking has been demonstrated experimentally in a 1.3-micron-wavelength laser based on gadolinium-scandium-gallium garnet activated by Cr(3+) and Nd(3+) ions, which is characterized by the highest gain factor among the known Nd-containing media. Passive mode locking has been achieved through the use of phototropic centers absorbing at the wavelength of the more efficient transition (1.06 micron) and preventing the development of superluminescence. Two dyes, 4959 and 4877, are proposed for obtaining passive mode locking in lasers generating at 1.3 micron.

Demchuk, M. I.; Mikhailov, V. P.; Shkadarevich, A. P.; Manichev, I. A.; Iumashev, K. V.

1988-05-01

47

Magneto-Optical Characteristics of Bi-Substituted Rare-Earth Iron Garnet Films Prepared by Laser Ablation  

NASA Astrophysics Data System (ADS)

Bismuth substituted rare-earth iron garnet (Bi:RIG) films were prepared on (111) gadolinium gallium garnet (GGG) and glass substrates b laser ablation using the ArF excimer laser. Crystal structure of the garnet phase was obtained above the substrate temperature of about 500° C on GGG substrate without postdeposition annealing and on glass substrate with postdeposition rapid thermal annealing. Films with the easy magnetization axis normal to the film plane were obtained for Bi:DyIG and Ga- or Al-substituted Bi-YIG on GGG substrate. The Faraday hyster- esis loops and the magnetic domain were observed. On the other hand, the easy magnetization axis normal to the film plane was obtained for Bi:DyIG films on the glass substrate with postdeposition rapid thermal annealing.

Kidoh, Hideo; Yashima, Hideyuki; Morimoto, Akiharu; Shimizu, Tatsuo

1994-07-01

48

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

49

Use of the erbium, chromium:yttrium–scandium–gallium–garnet laser on human enamel tissues. Influence of the air–water spray on the laser–tissue interaction: scanning electron microscope evaluations  

Microsoft Academic Search

The study investigated the influence of varying amounts of air\\/water spray and the energy used by an erbium, chromium:yttrium–scandium–gallium–garnet\\u000a (Er,Cr:YSGG) 2,780 nm laser when treating dental tissues. The morphological effects produced by the laser interaction on healthy\\u000a human enamel were evaluated by scanning electron microscopy (SEM). The vestibular and lingual surfaces of ten molars were\\u000a treated with laser at different power

Giovanni Olivi; Francesca Angiero; Stefano Benedicenti; Giuseppe Iaria; Antonio Signore; Vassilios Kaitsas

2010-01-01

50

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

51

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

52

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

53

Effect of mechanical milling on the magnetic properties of garnets  

Microsoft Academic Search

Rare earth garnets after milling to nanosizes are found to decompose into rare earth orthoferrite and other rare earth and iron oxide phases. The magnetization for the yttrium iron garnet decreases in the nano state due to the formation of antiferromagnetic phases. But for the gadolinium iron garnet when milled up to 25h, the room temperature magnetization increases despite the

R. J. Joseyphus; A. Narayanasamy; A. K. Nigam; R. Krishnan

2006-01-01

54

Light-emitting diodes of 'Warm' white luminescence on the basis of p-n heterostructures of the InGaN/AlGaN/GaN type coated with phosphors made of yttrium-gadolinium garnets  

SciTech Connect

Electroluminescence spectra and color characteristics of light-emitting diodes of white luminescence based on p-n heterostructures of the InGaN/AlGaN/GaN type with blue emission ({lambda}{sub max} {approx} 455 nm) coated with phosphors of the type of aluminum-yttrium-gadolinium garnets activated with the Ce{sup 3+} ions are studied. The maximum in the excitation spectra of phosphors varies in the range 460-470 nm. The luminescence spectra of phosphors have the peaks from 530 to 590 nm and a width at half-maximum of intensity from 120 to 135 nm depending of the compound composition. The selection of intensities of blue and yellow-orange bands allows one to shift the coordinates of chromaticity of white light-emitting diodes to the region of 'warm' luminescence with a correlated color temperature to T{sub CC} = 3000 K and maximum luminous efficiency up to 50 lm/W.

Soshchin, N. P. [Research Institute 'Platan' (Russian Federation); Galchina, N. A.; Kogan, L. M. [Research and Production Center of Optoelectronic Devices 'OPTEL' (Russian Federation); Shirokov, S. S.; Yunovich, A. E. [Moscow State University, Physical Faculty (Russian Federation)], E-mail: yunovich@phys.msu.ru

2009-05-15

55

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

56

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

57

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

NASA Astrophysics Data System (ADS)

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 (less than 200 V). These materials may be considered alternatives to reduced zinc oxide as green-emitting phosphors.

Phillips, Mark L. F.; Shea, Lauren E.

58

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

59

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

60

Magnetic properties of some rare earth tellurate garnets  

NASA Astrophysics Data System (ADS)

The magnetic properties of the lanthanide tellurate garnets Ln3Te2Li3O12 for Ln=Pr, Nd, Gd Er, and Yb are found to exhibit similarities in many cases to the related aluminum or gallium garnet compounds. Magnetic exchange is also roughly comparable in magnitude, despite the systematic difference in exchange pathways.

Applegate, Ryan P.; Zong, Yuhua; Corruccini, L. R.

2007-09-01

61

Growth and characterization of Bi, Pr- and Bi, Sc-substituted lutetium iron garnet films with planar magnetization for magneto-optic visualization  

NASA Astrophysics Data System (ADS)

The series of epitaxial garnet films of general composition Lu3-x-yBixPryFe5- zAlzO12 and Lu3-xBixFe5-y- zScyAlzO12 were grown on (111) oriented GGG (gadolinium gallium garnet) substrates by the liquid phase epitaxy. Their magnetic and magneto-optical properties were studied using both experimental techniques and modelling. All obtained films demonstrated generally a magnetic anisotropy close to the easy-plane type. The Pr-containing films exhibited large negative uniaxial anisotropy and significant cubic anisotropy. The latter causes a distortion of magnetization curves in samples magnetized in a direction normal to the film plane, especially at low temperatures. The large negative uniaxial anisotropy of Pr-substituted iron garnets allows us to increase the saturation field up to 0.5 T at liquid nitrogen temperature. The Sc-doped films displayed small positive uniaxial anisotropy that did not exceed the shape anisotropy. The magnetization curves of these films did not show any distortion due to the cubic anisotropy. The suitability of Pr- and Sc-doped garnets that meet the requirements for indicator layers for magneto-optic visualization at liquid nitrogen temperature is discussed.

Syvorotka, Igor M.; Ubizskii, Sergii B.; Kucera, Miroslav; Kuhn, Marcus; Vértesy, Zofia

2001-04-01

62

Use of the erbium, chromium:yttrium-scandium-gallium-garnet laser on human enamel tissues. Influence of the air-water spray on the laser-tissue interaction: scanning electron microscope evaluations.  

PubMed

The study investigated the influence of varying amounts of air/water spray and the energy used by an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) 2,780 nm laser when treating dental tissues. The morphological effects produced by the laser interaction on healthy human enamel were evaluated by scanning electron microscopy (SEM). The vestibular and lingual surfaces of ten molars were treated with laser at different power settings; each surface was subdivided into cervical, median, and occlusal parts and treated with different proportions of water spray; the series contained 60 tooth portions. Treatment differed in terms of power setting and air/water percentage. All specimens were then subjected to dehydration and metallisation. At SEM evaluation, the classic aspect of laser-treated enamel was visible: grooves, flakes, shelves and sharp edges, indicative of micro-explosion rather than melting. Vaporisation of the tissue created a clear delimitation from surrounding healthy tissue, with partial respect to the prismatic structure of the treated enamel. The aspect of the enamel was rarely type 1 Silverstone but more frequently type 2 or 3, with prismatic structure not respected and/or completely disordered. These morphological differences appeared to be correlated with the inclination of the laser beam aimed at the enamel prisms and with the percentage of air/water used. The laser system analysed showed itself to be effective at removing human dental enamel. The results appeared to be closely correlated with the variation of the percentage of the laser's water-air spray. PMID:19548057

Olivi, Giovanni; Angiero, Francesca; Benedicenti, Stefano; Iaria, Giuseppe; Signore, Antonio; Kaitsas, Vassilios

2010-11-01

63

Pulsed laser ablation deposition of yttrium iron garnet and cerium-substituted YIG films  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) thin films were grown on gadolinium gallium garnet substrates using pulsed laser ablation deposition (PLAD) with a XeCl excimer laser. Films were grown up to over 2 ?m thick, however cracking proved to be a problem for films over 1 ?m thick. The lattice parameter(s) of the films and the substrates were measured and indicated that the film/substrate structure was bending to accommodate strain due to the lattice mismatch. The films had saturation magnetisation values close to that of bulk YIG and were isotropic in the film plane. The magnetisation data also indicate stress-induced uniaxial isotropy. The ablation conditions were varied to produce uncracked films with low droplet densities. YIG melts incongruently during the laser ablation process and cone-like structures form on the ablation target lowering the ablation rates. Cerium-substituted YIG films were also grown in both oxygen and argon atmospheres, substituting cerium into YIG increases the lattice parameter and hence reduces the strain. The Ce-YIG film grown in argon was greenish indicating that cerium was in the desired oxidation state.

Ibrahim, N. B.; Edwards, C.; Palmer, S. B.

2000-10-01

64

FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS): An Artificially Garnet Crystal Materials Using In Terahertz Waveguide  

NASA Astrophysics Data System (ADS)

A hypothesis is brought forward that the materials with low propagation loss in both optical and microwave band may exhibit good performance in terahertz (THz) band because THz wave band interspaces those two wave bands. For the purpose of exploring a kind of low-loss material for THz waveguide, Lu2.1Bi0.9Fe5O12 (LuBilG) garnet films are prepared by liquid phase epitaxy (LPE) method on a gadolinium gallium garnet (GGG) substrate from lead-free flux because of the good properties in both optical and microwave bands. In microwave band, the ferromagnetic resonance (FMR) linewidth of the film 2?H = 2.8-5.1 Oe; in optical band, the optical absorption coefficient is 600 cm-1 at visible range and about 100-170 cm-1 when the wavelength is longer than 800nm. In THz range, our hypothesis is well confirmed by a THz-TDS measurement which shows that the absorbance of the him for THz wave is 0.05-0.3 cm-1 and the minimum value appears at 2.3 THz. This artificial ferromagnetic material holds a great promise for magnetic held tunable THz devices such as waveguide, modulator or switch.

Yang, Qing-Hui; Zhang, Huai-Wu; Liu, Ying-Li; Wen, Qi-Ye; Zha, Jie

2008-11-01

65

Highly luminescent garnets for magneto-optical photonic crystals  

NASA Astrophysics Data System (ADS)

We compare luminescent properties of several Er-doped garnets as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals. Pulsed laser deposited La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, and rf-magnetron sputtered Bi3Fe5O12 were chosen to host Er3+ ions on dodecahedral lattice sites. Er substituents with the concentration of 0.5 at. % (0.1 garnet formula units) do not decrease giant Faraday rotation in Bi2.9Er0.1Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching almost 6 ms in Gd2.9Er0.1Ga5O12. We conclude Er substitution in gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.

Grishin, A. M.; Khartsev, S. I.

2009-09-01

66

Rare-earth garnets and perovskites for space-based ADR cooling at high T and low H  

NASA Astrophysics Data System (ADS)

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 ~30 K down to sub-Kelvin under low magnetic fields (H<=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, Gd3Ga5-XFeXO12, 0.00<=X<=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<=X<=5.00), temperature (2 K<=T<=30 K) and applied magnetic field (0 T<=H<=3 T). The magnetic entropy change (?Smag) between 0 T and 3 T was determined from the magnetization data. In the GGIG system, ?Smag was compositionally dependent; Fe3+ additions up to X<=2.44 increased ?Smag at T>5 K. For GAP, ?Smag was similar to that of GGIG, X=0.00, both in terms of magnitude and temperature dependence at T>10 K. However, the ?Smag of GAP at T<10 K was less than the endmember GGIG composition, X=0.00, and exhibited maximum ~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.

2002-05-01

67

Effect of mechanical milling on the magnetic properties of garnets  

NASA Astrophysics Data System (ADS)

Rare earth garnets after milling to nanosizes are found to decompose into rare earth orthoferrite and other rare earth and iron oxide phases. The magnetization for the yttrium iron garnet decreases in the nano state due to the formation of antiferromagnetic phases. But for the gadolinium iron garnet when milled up to 25 h, the room temperature magnetization increases despite the formation of antiferromagnetic and non-magnetic phases. This is attributed to the uncompensated moments of the sublattices because of the weakening of the superexchange interaction due to change in bond angles and the breaking of some superexchange bonds on account of the defects and oxygen vacancies introduced on milling. For the 10 h milled gadolinium iron garnet at 5 K, after correcting for the non-magnetic phases present, there is an increase in the magnetic moment of about 10% as compared to the value for the as-prepared garnet. The magnetic hyperfine fields corresponding to the various phases were measured using 57Fe Mössbauer spectroscopy at 16 K. The isomer shift values indicate the loss of oxygen for the samples milled for larger duration.

Joseyphus, R. J.; Narayanasamy, A.; Nigam, A. K.; Krishnan, R.

2006-01-01

68

Gadolinium neutron capture therapy  

Microsoft Academic Search

A computer study of the dose distribution for gadolinium neutron capture therapy is carried out to determine its feasibility. Gadolinium is a potential neutron capture therapy (NCT) agent that produces gamma radiation, conversion electrons, and Auger electrons. The dose distribution from neutrons, neutron-induced gammas, and the reaction products from neutron capture in gadolinium were modeled using the Los Alamos National

G. A. Jr. Miller; N. E. Hertel; B. W. Wehring; J. L. Horton

1993-01-01

69

Mechanochemical decomposition of Gd 3Fe 5O 12 garnet phase  

Microsoft Academic Search

Gadolinium iron garnet was milled in a high energy ball mill to study its magnetic properties in the nanocrystalline regime. XRD reveals the decomposition of the garnet phase into Gd-orthoferrite and Gd2O3 on milling. The variation of saturation magnetization and coercivity with milling is attributed to a possible shift in the compensation temperature on grain size reduction and an increase

R. Justin Joseyphus; A. Narayanasamy; N. Sivakumar; M. Guyot; R. Krishnan; N. Ponpandian; K. Chattopadhyay

2004-01-01

70

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

71

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

72

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

73

Gadolinium neutron capture therapy  

SciTech Connect

A computer study of the dose distribution for gadolinium neutron capture therapy is carried out to determine its feasibility. Gadolinium is a potential neutron capture therapy (NCT) agent that produces gamma radiation, conversion electrons, and Auger electrons. The dose distribution from neutrons, neutron-induced gammas, and the reaction products from neutron capture in gadolinium were modeled using the Los Alamos National Laboratory Monte Carlo neutron photon computer code. The results of these calculations are that gadolinium has promise as an NCT agent. Using two parallel opposed epithermal neutron beams for a tumor at an 8.0-cm depth with a gadolinium loading of 100[mu]g/g, the tumor to peak normal tissue dose was determined to be 1.48.

Miller, G.A. Jr. (Univ. of Austin, TX (United States). Biomedical Engineering); Hertel, N.E. (Georgia Inst. of Technology, Atlanta, GA (United States). Mechanical Engineering); Wehring, B.W. (Univ. of Texas, Austin, Tx (United States). Mechanical Engineering); Horton, J.L. (Univ. of Texas, Houston, TX (United States). M.D. Anderson Cancer Center)

1993-09-01

74

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

75

Radioactive Isotopes of Gadolinium  

Microsoft Academic Search

A 236-day neutron induced activity in gadolinium purified by ion exchange methods is assigned to Gd153. The activity decays by K-electron capture emitting a 106-kev gamma-ray giving rise to K- and L-electron groups. A 7.2+\\/-0.2 day and approximately 24-hour activity present in the neutron bombarded gadolinium were separated on an ion exchange column. The 7.2-day activity assigned to Tb161 decays

R. E. Hein; A. F. Voigt

1950-01-01

76

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

77

Structure property correlations in Ce-doped garnet phosphors for use in solid state lighting  

NASA Astrophysics Data System (ADS)

The discovery of inorganic phosphors that can be excited by GaN light emitting diodes in the wavelength range 380-460 nm is essential for improving the efficiency and light quality of solid state lighting devices. Garnets doped with Ce 3+ are of particular interest for this application. We have studied the luminescence of Ce 3+ in garnet phosphors and established a relationship between the excitation/emission wavelengths and the deviation from cubic symmetry around the rare-earth ion. Data are presented for both known yttrium aluminum and yttrium gallium garnet systems, as well as newly synthesized inverse garnets of the general formula Mg 3Y 2- yGd yGe 3- zSi zO 12:Ce (0 ? y ? 2, z = 0, 1).

Wu, Jennifer L.; Gundiah, Gautam; Cheetham, A. K.

2007-06-01

78

Mechanochemical decomposition of Gd 3Fe 5O 12 garnet phase  

NASA Astrophysics Data System (ADS)

Gadolinium iron garnet was milled in a high energy ball mill to study its magnetic properties in the nanocrystalline regime. XRD reveals the decomposition of the garnet phase into Gd-orthoferrite and Gd 2O 3 on milling. The variation of saturation magnetization and coercivity with milling is attributed to a possible shift in the compensation temperature on grain size reduction and an increase in the orthoferrite content. The Mössbauer spectrum at 16 K is characteristic of the magnetically ordered state corresponding to GdIG, GdFeO 3 and ?-Fe 2O 3 whereas at room temperature it is a superparamagnetic doublet.

Justin Joseyphus, R.; Narayanasamy, A.; Sivakumar, N.; Guyot, M.; Krishnan, R.; Ponpandian, N.; Chattopadhyay, K.

2004-05-01

79

Strained gallium nitride nanowires  

Microsoft Academic Search

Gallium nitride nanowires were synthesized on silicon substrates by chemical vapor deposition using the reaction of gallium and gallium nitride mixture with ammonia. Iron nanoparticles were used as catalysts. The diameter of nanowires is uniform as 25 nm and the lengths are 20-40 mum. The nanowires have single crystalline wurtzite structure with a few stacking faults. A careful examination into

Hee Won Seo; Seung Yong Bae; Hyunik Yang; Kwang Soo Park; Sangsig Kim

2002-01-01

80

Growth of epitaxial garnet film by LPE for application to integrated magneto-optic light switch arrays  

Microsoft Academic Search

We investigate the dependence of the properties of garnet films grown by liquid phase epitaxy (LPE) on the procedure and the temperature of growth to tailor magnetic properties of Bi, Gd, Ga:YIG film for application to integrated magneto-optic light switch arrays. Because the yttrium and gallium concentrations of the films decreased slightly and the bismuth, iron concentrations of the films

J. H. Park; J. K. Cho; K. Nishimura; H. Uchida; M. Inoue

2004-01-01

81

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

82

Gallium in cancer treatment.  

PubMed

The trivalent gallium cation is capable of inhibiting tumor growth, mainly because of its resemblance to ferric iron. It affects cellular acquisition of iron by binding to transferrin, and it interacts with the iron-dependent enzyme ribonucleotide reductase, resulting in reduced dNTP pools and inhibition of DNA synthesis. The abundance of transferrin receptors and the up-regulation of ribonucleotide reductase render tumor cells susceptible to the cytotoxicity of gallium. Remarkable clinical activity in lymphomas and bladder cancer has been documented in clinical studies employing intravenous gallium nitrate, which is currently being re-evaluated in non-Hodgkin's lymphoma. An improved therapeutic index is expected to result from prolonged exposure to low steady-state plasma gallium levels. Attempts to accomplish this by oral administration of gallium chloride failed because of insufficient intestinal absorption. Complexation of gallium with ligands, which stabilize gallium against hydrolysis and facilitate membrane permeation, has been recognized as a promising strategy for overcoming these limitations. Two such gallium complexes, namely tris(3-hydroxy-2-methyl-4H-pyran-4-onato)gallium(III) (gallium maltolate) and tris(8-quinolinolato)gallium(III) (KP46), which both exhibit high bioavailability when administered via the oral route, are currently being evaluated in the clinical setting. PMID:15579097

Jakupec, Michael A; Keppler, Bernhard K

2004-01-01

83

Compositional analysis of single crystals of flux-grown magnetic garnets by atomic absorption spectrophotometry.  

PubMed

A method of determining the chemical composition of single crystals of flux-grown magnetic garnets (R(1), R(2))(3)(Fe, Ga)(5)O(12) (R(1) and R(2) = Y, Eu, Gd, or Er) is described. Elements to be determined were rare earths, iron and gallium as main constituents, and lead as an impurity introduced from the flux. Lanthanum chloride was added to the samples and the standard solutions to remove the interference effects of concomitant foreign elements on the atomic-absorption measurement of the rare earths and to improve the measurement precision for iron, gallium and lead. The atomic-absorption measurements in the lanthanum chloride matrix are discussed. Finally, results for some garnets are presented and problems regarding the composition of the materials are described. PMID:18962267

Ametani, K

1978-06-01

84

Oxygen isotope zoning in garnet.  

PubMed

Oxygen isotope zoning was examined within garnet with the use of the stable isotope laser probe. Four metamorphic garnets from the regional metamorphic terrane in Vermont and the skarn deposit at Carr Fork, Utah, were examined and were found to be concentrically zoned in delta(18)O values. The largest variations in delta(18)O values were observed in the regional metamorphic garnets, where delta(18)O values change by 3 per mil from core to rim. These oxygen isotope zoning profiles reflect the changes in the delta(18)O values of the rocks during garnet growth, which are caused by infiltration of fluids and by dehydration reactions during metamorphism. PMID:17742227

Chamberlain, C P; Conrad, M E

1991-10-18

85

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

86

Gallium nitride optoelectronic devices  

NASA Technical Reports Server (NTRS)

The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.

Chu, T. L.; Chu, S. S.

1972-01-01

87

Zinc and gallium diffusion in gallium antimonide  

Microsoft Academic Search

Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. Accurate modeling of the experimental profiles by means of continuum theoretical calculations reveals that Zn diffusion proceeds via singly positively charged Zn interstitials (Zni+) . The changeover of Zni+ to substitutional gallium (Ga) sites, thereby

Kirsten Sunder; Hartmut Bracht; Samuel P. Nicols; Eugene E. Haller

2007-01-01

88

Uncompensated Garnet - A Magnetic Semiconductor.  

National Technical Information Service (NTIS)

Ca-substituted YIG single crystal films (Ca:YIG) show p-type conduction while Si or Ge doped YIG garnets (Si:YIG or Ge:YIG) have n-type conduction. Both garnet films maintain their superior magnetic properties of pure YIG, while their electrical resistanc...

P. E. Wigen

1998-01-01

89

Garnets and garnet films: Production and applications. (Latest citations from the US Patent database). Published Search  

SciTech Connect

The bibliography contains citations of selected patents concerning garnet and garnet film fabrication techniques and processes. Polishing and etching of single crystal garnets are described. Applications are discussed, including use of garnets and garnet films in lighting, visual display systems, magnetooptics, superconductors, lasers, bubble memory devices, jewelry, and electronic components. Epitaxial growth of garnets is discussed in a related bibliography. (Contains a minimum of 107 citations and includes a subject term index and title list.)

Not Available

1992-12-01

90

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

91

Epitaxial Garnets and Hexagonal Ferrites.  

National Technical Information Service (NTIS)

The objective of this research is to develop new and improved epitaxial ferrite materials for use in microwave and millimeter-wave signal processing devices. The major emphasis has been on multiple layer magnetic garnet structures for magnetostatic wave (...

H. L. Glass L. R. Adkins

1983-01-01

92

Temperature dependence of the enhanced excited state absorption in erbium-doped garnets  

NASA Astrophysics Data System (ADS)

Temperature dependence of an enhanced excited state absorption was investigated in erbium-doped garnet crystals using 787.3 and 787.8 nm laser diodes. The enhanced absorption was obtained at temperature ranges of 15-570 K, 15-420 K, and 15-1200 K in a yttrium aluminum garnet, a yttrium scandium gallium garnet, and a lutetium aluminum garnet, respectively. Absorption peaks corresponding to both the 4I15/2-4I9/2 and the 4I13/2-2H11/2 transitions of Er3+ in garnets were shifted from those for 300 K at high temperature. The enhanced absorption weakened at high temperature because an absorption cross section from the 4I13/2 level to the 2H11/2 level decreased due to the shift of the absorption peaks. It has been confirmed that a mechanism of the enhanced absorption can be explained by calculating the rate equations based on an analytical model for a five-level system of the Er3+ ion. It is suggested that the enhanced absorption weakened at temperatures lower than 12 K because the number of phonons decreased due to low temperature.

Maeda, Yoshinobu; Yamada, Toshikazu

1998-06-01

93

Gadolinium doped europium sulfide.  

PubMed

We have prepared gadolinium doped europium sulfides, Eu(1-x)Gd(x)S for a doping range of 0 ? x ? 0.1 by thermal decomposition of the precursors Eu(S(2)CNEt(2))(3)Phen/Gd(S(2)CNEt(2))(3)Phen with respective ratios. Electron doping provides indirect evidence for the magnetic coupling through carrier electrons in magnetic semiconductors. Based on the magnetic properties, we determined that the paramagnetic Curie temperature, ?p, varies with doping level, in a similar way to Eu(1-x)Gd(x)O exhibiting a significant increase at low doping levels. All materials have been characterized by X-ray powder diffraction, magnetic measurements, ICP-MS, and TEM. PMID:20853843

Kar, Srotoswini; Boncher, William L; Olszewski, Daniel; Dollahon, Norman; Ash, Richard; Stoll, Sarah L

2010-10-13

94

Gallium Arsenide Data Sheets.  

National Technical Information Service (NTIS)

These data sheets present a compilation of a wide range of electrical, optical and energy values for pure and variously-doped gallium arsenide in bulk and film form. Electrical properties include conductivity, resistivity, dielectric constant, Hall coeffi...

M. Neuberger

1965-01-01

95

GARNet, the Genomic Arabidopsis Resource Network.  

PubMed

GARNet, the Genomic Arabidopsis Resource Network, was created to establish UK-based facilities for functional genomic research on Arabidopsis thaliana. In addition, GARNet provides a platform for international Arabidopsis research and for research on other plant species. To use the GARNet facilities apply via the website: http://garnet.arabidopsis.org.uk. All GARNet services and resources are publicly available, and data created using the GARNet resources will be freely distributed via databases held at the Nottingham Arabidopsis Stock Centre and the John Innes Centre. PMID:11950604

Beale, Michael; Dupree, Paul; Lilley, Kathryn; Beynon, Jim; Trick, Martin; Clarke, Jonathan; Bevan, Michael; Bancroft, Ian; Jones, Jonathan; May, Sean; van de Sande, Karin; Leyser, Ottoline

2002-04-01

96

Thermodynamic properties of gadolinium disilicide  

Microsoft Academic Search

The purpose of this work was to determine the thermodynamic properties of gadolinium disilicide by the me~hod of measurement in the 830-960 K temperature range of the emf of the concentration galvanic element [GdSn3 + (Sn)L] I KCI -- NaC1 -- (BaCl~) + GdCI 8 [ [GdSi~ + Si], (1) where (Sn) L is a saturated solution of gadolinium in

G. M. Lukashenko; R. I. Polotskaya

1986-01-01

97

Amphoteric Impurities in Gallium Arsenide.  

National Technical Information Service (NTIS)

Gallium arsenide is already an important material for application in high frequency, low noise field effect transitors (FETs) and in optoelectronic devices, and future Gallium Arsenide (GaAs) high speed integrated circuits are expected to have a major imp...

G. E. Stillman

1987-01-01

98

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

99

Low thermal conductivity in garnets  

SciTech Connect

The thermal conductivity of dense, polycrystalline garnet ceramics with compositions of Y{sub 3}Al{sub x}Fe{sub 5{minus}x}O{sub 12} (x = 0.0, 0.7, 1.4, and 5.0) was measured in the temperature range 23 to 1,000 C. The high-temperature thermal conductivity of some of these garnets was found to be as low as 2.4 W{center_dot}m{sup {minus}1}{center_dot}K{sup {minus}1}. The effects of temperature and composition on the observed thermal conductivity are discussed with reference to established theories of thermal conduction. The potential use of yttrium aluminum garnet or YAG (Y{sub 3}Al{sub 5}O{sub 12}), in particular, for a specific application of advanced thermal barrier coatings (TBCs) with improved durability is considered.

Padture, N.P.; Klemens, P.G. [Univ. of Connecticut, Storrs, CT (United States). Inst. of Materials Science

1997-04-01

100

Gallium Phosphide and the Gallium Arsenide-Gallium Phosphide System, Data Sheets.  

National Technical Information Service (NTIS)

These data sheets present a compilation of a wide range of electrical, optical and energy values for gallium phosphide and the gallium arsenidegallium phosphide system in bulk and film form. Electrical properties include lifetime and thermoelectric effect...

M. Neuberger

1965-01-01

101

Laserspektroskopie Gadoliniums Fingerabdruck  

SciTech Connect

The minimum energy that is required to remove the first electron from e neutral atom, one call ionization energy E1. It is not only for every element of the periodic table but also even for every nuclide characteristic and therefore belongs to the most basic atomic properties. The ionization energy is important for the determination of a ‘row’ of properties, from the chemical reactivity to the color light absorbed and emitted from an atom. The value of E1 depends on the stationary state that the farthest electron originally occupies. If the electron finds itself, however, in the first excited stat, only 3.4 eV is required. Previously the ionization energy could be determined with high accuracy in the range of 10-8 by means of laser spectroscopy only for atoms with one or two valence electrons, whereby the most accurate to date result from measurements on Hydrogen. We could now, for the first time in a rare earth element, reach that kind of accuracy. Motivation for these investigations was the development of an analysis method for the ultra-trace detection of Gadolinium in tissue- and meteorite samples.

Blaum, Klaus; Bushaw, Bruce A.; Nortershauser, Wilfried

2003-05-31

102

Gadolinium Solubillty and Volatility During DWPF Processing.  

National Technical Information Service (NTIS)

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 ...

S. Reboul

2008-01-01

103

On the chemistry of gallium  

Microsoft Academic Search

The gallium subhalides Ga2Cl4·2dioxane and sonochemically prepared GaI were reacted with the carbonyl ferrate K[Cp(CO)2Fe] and the iron carbonyl dimer [Cp(CO)2Fe]2, respectively. In all the reactions performed, the gallium(I) and gallium(II) compounds disproportionated into elemental gallium and gallium(III) compounds. Several novel complexes containing Ga–FeCp(CO)2 fragments were isolated and characterized spectroscopically and by X-ray crystal structure analysis. These are compounds of

Gerald Linti; Guangming Li; Heinz Pritzkow

2001-01-01

104

Zinc and gallium diffusion in gallium antimonide  

NASA Astrophysics Data System (ADS)

Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. Accurate modeling of the experimental profiles by means of continuum theoretical calculations reveals that Zn diffusion proceeds via singly positively charged Zn interstitials (Zni+) . The changeover of Zni+ to substitutional gallium (Ga) sites, thereby forming the acceptor dopant ZnGa- , is concluded to be mainly mediated by neutral IGa0 and singly positively charged Ga interstitials IGa+ via the kick-out mechanism. Fitting of the Zn profiles provides the reduced Zni+ -mediated Zn diffusion coefficient and the relative contributions of IGa0 and IGa+ to Ga diffusion. These contributions to Ga diffusion are lower than the directly measured Ga diffusion coefficient, which indicates that Ga diffusion in GaSb is rather mediated by Ga vacancies than by Ga interstitials even under Ga-rich conditions. This finding supports the transformation reaction between native point defects in GaSb that was previously proposed to explain the Ga-vacancy-mediated diffusion of Ga in GaSb under Ga-rich conditions [H. Bracht Nature (London) 408, 69 (2000)].

Sunder, Kirsten; Bracht, Hartmut; Nicols, Samuel P.; Haller, Eugene E.

2007-06-01

105

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

106

Gallium-containing anticancer compounds  

PubMed Central

There is an ever pressing need to develop new drugs for the treatment of cancer. Gallium nitrate, a group IIIa metal salt, inhibits the proliferation of tumor cells in vitro and in vivo and has shown activity against non-Hodgkin’s lymphoma and bladder cancer in clinical trials. Gallium can function as an iron mimetic and perturb iron-dependent proliferation and other iron-related processes in tumor cells. Gallium nitrate lacks cross resistance with conventional chemotherapeutic drugs and is not myelosuppressive; it can be used when other drugs have failed or when the blood count is low. Given the therapeutic potential of gallium, newer generations of gallium compounds are now in various phases of preclinical and clinical development. These compounds hold the promise of greater anti-tumor activity against a broader spectrum of cancers. The development of gallium compounds for cancer treatment and their mechanisms of action will be discussed.

Chitambar, Christopher R

2013-01-01

107

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

108

Thermodynamic propoerties of gadolinium germanides  

Microsoft Academic Search

In this work the thermodynamic properties of gadolinium germanides were investigated by measurement of the emf of [GdSn s + (Sn)L)]Gd +3 concentration galvanic elements in molten salt\\/GdxGe1_ x in the 760-960 K temperature range. The auxiliary reference electrode, Gd-Sn alloy belonging to the heterogeneous [GdSn s + (Sn)L)] area, the thermodynamic characteristics of which were determined by measurement of

R. I. Polotskaya

1991-01-01

109

Gallium--A smart metal  

USGS Publications Warehouse

Gallium is a soft, silvery metallic element with an atomic number of 31 and the chemical symbol Ga. The French chemist Paul-Emile Lecoq de Boisbaudran discovered gallium in sphalerite (a zinc-sulfide mineral) in 1875 using spectroscopy. He named the element "gallia" after his native land of France (formerly Gaul; in Latin, Gallia). The existence of gallium had been predicted in 1871 by Dmitri Mendeleev, the Russian chemist who published the first periodic table of the elements. Mendeleev noted a gap in his table and named the missing element "eka-aluminum" because he determined that its location was one place away from aluminum in the table. Mendeleev thought that the missing element (gallium) would be very much like aluminum in its chemical properties, and he was right. Solid gallium has a low melting temperature (~29 degrees Celsius, or °C) and an unusually high boiling point (~2,204 °C). Because of these properties, the earliest uses of gallium were in high-temperature thermometers and in designing metal alloys that melt easily. The development of a gallium-based direct band-gap semiconductor in the 1960s led to what is now one of the most well-known applications for gallium-based products--the manufacture of smartphones and data-centric networks.

Foley, Nora; Jaskula, Brian

2013-01-01

110

Pyroxene-Garnet Transformation in Coorara Meteorite  

Microsoft Academic Search

Majorite is a new garnet in a veinlet of the Coorara meteorite. Its chemical composition is compatible with derivation mostly from original pyroxene, not from olivine as originally reported. Silicon is partly in sixfold coordination. Ringwoodite, a spinel of olivine composition, occurs as purple grains set in a matrix of fine-grained garnet. The similar mineralogy and texture of the Coorara

J. V. Smith; Brian Mason

1970-01-01

111

Methods of Fabricating Gallium Nitride Semiconductor Layers on Substrates Including Non-Gallium Nitride Posts, and Gallium Nitride Semiconductor Structures Fabricated Thereby.  

National Technical Information Service (NTIS)

A substrate includes non-gallium nitride posts that define trenches therebetween, wherein the non-gallium nitride posts include non-gallium nitride sidewalls and non-gallium nitride tops and the trenches include non-gallium floors. Gallium nitride is grow...

K. J. Linthicum R. F. Davis T. Gehrke

2005-01-01

112

Fundamental studies of the metallurgical, electrical, and optical properties of gallium phosphide and gallium phosphide alloys  

NASA Technical Reports Server (NTRS)

Abstracts, bibliographic data, oral presentations, and published papers on (1) Diffusion of Sulfur in Gallium Phosphide and Gallium Arsenide, and (2) Properties of Gallium Phosphide Schottky Barrier Rectifiers for Use at High Temperature are presented.

1972-01-01

113

Superconducting Gallium Antimonide.  

PubMed

A metallic phase of gallium antimonide, obtained by quenching at approximately 120 kilobars to 77 degrees K and then releasing pressure, is a superconductor. The transition temperature depends on the annealing conditions; for samples annealed at 250 degrees C under pressure before quenching, it is 4.24 degrees +/- 0.10 degrees K, and H(c2) (the critical field) equals 2640 gauss at 3.50 degrees K. This temperature is higher than the 2.1 degrees K reported for metallic indium antimonide. PMID:17776623

McWhan, D B; Hull, G W; McDonald, T R; Gregory, E

1965-03-19

114

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

115

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

116

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

117

Growth of epitaxial garnet film by LPE for application to integrated magneto-optic light switch arrays  

NASA Astrophysics Data System (ADS)

We investigate the dependence of the properties of garnet films grown by liquid phase epitaxy (LPE) on the procedure and the temperature of growth to tailor magnetic properties of Bi, Gd, Ga:YIG film for application to integrated magneto-optic light switch arrays. Because the yttrium and gallium concentrations of the films decreased slightly and the bismuth, iron concentrations of the films increased slightly with decreases of the growth temperature, the magnetic properties of the garnet film grown by LPE are very sensitive specially to a growth temperature. The decrease of Hsat with decreasing growth temperature indicates that the perpendicular magnetic anisotropy energy of the film decreases. The Bi, Gd, Ga:YIG film grown at around 730 °C have good magnetic properties, i.e., a low value of 4Ms of 120 G, a low value of saturation field Hsat of 168 Oe, and a low perpendicular magnetic anisotropy for application of the magneto-optic spatial light modulators.

Park, J. H.; Cho, J. K.; Nishimura, K.; Uchida, H.; Inoue, M.

2004-06-01

118

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

119

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

120

Dopant-host relationships in rare-earth oxides and garnets doped with trivalent rare-earth ions  

Microsoft Academic Search

The dopant-host interactions were considered in the Eu3+- and R3+-doped cubic C-type rare-earth oxides (R2O3) as well as in nondoped R3Ga5O12 and R3+-doped yttrium gallium garnets (Y3Ga5O12:R3+). The investigations were based mainly on the analyses of optical absorption and luminescence spectra using both new and previously published data. The concept of the crystal field (CF) strength parameter Nv was used

Elisabeth Antic-Fidancev; Jorma Hölsä; Mika Lastusaari; Aurelia Lupei

2001-01-01

121

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

122

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

123

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

124

Infrared Isolator Using Yttrium Iron Garnet.  

National Technical Information Service (NTIS)

Infrared isolators using the Faraday rotation in a single crystal Yttrium Iron Garnet (YIG) and calcite dichroic polarizers have been built. By using the YIG crystal with thorium fluoride antireflection coating the authors obtained isolation better than 3...

H. Gamo S. S. Chuang

1970-01-01

125

Magnetic Anneal Effects in Some Garnets.  

National Technical Information Service (NTIS)

Many properties of polycrystalline and reduced single crystal yttrium iron garnet (YIG) have been attributed to the presence of Fe(2+) ions which provide mobile electrons that can diffuse locally through the lattice. This electron-diffusion process was st...

R. P. Hunt

1965-01-01

127

The influence of Fe3+ on garnet-orthopyroxene and garnet-olivine geothermometers  

NASA Astrophysics Data System (ADS)

Applying Fe2+-Mg exchange geothermometers to natural samples may lead to incorrect temperature estimates if significant Fe3+ is present. In order to quantify this effect, high-pressure experiments were carried out in a belt apparatus in a natural system close to CFMAS at 5 GPa and 1,100-1,400 °C. The oxygen fugacity in the experiments was at or below the Re-ReO2 buffer. This is at significantly more oxidized conditions than in previous experiments, and, as consequence, higher Fe3+/Fe2+ ratios were generated. The Fe3+ content of garnet in the experiments was quantified by electron microprobe using the flank method. Making the usual assumption that Fetotal = Fe2+, the two-pyroxene thermometer of Brey and Köhler (J Pet 31:1353-1378, 1990) reproduced the experimental temperature to ±35 °C and the garnet-clinopyroxene Fe2+-Mg exchange thermometer of Krogh (Contrib Miner Pet 99:44-48, 1988) overestimated the temperatures on average by only 25 °C. On the other hand, application of the garnet-olivine (O'Neill and Wood in Contrib Miner Pet 70:59-70, 1979) and garnet-orthopyroxene (Harley in Contrib Miner Pet 86:359-373, 1984) exchange geothermometers yielded an underestimation in calculated temperatures of >200 °C. However, making explicit accounting for Fe3+ in garnet (i.e. using only measured Fe2+) leads to a vast improvement in the agreement between calculated and experimental temperatures, generally to within ±70 °C for the garnet-orthopyroxene geothermometer as well as noticeable improvement of calculated temperatures for the garnet-olivine geothermometer. Our results demonstrate that the two-pyroxene and garnet-clinopyroxene thermometers are rather insensitive to the presence of Fe3+ whilst direct accounting of Fe3+ in garnet is essential when applying the garnet-olivine and garnet-orthopyroxene thermometers.

Matjuschkin, Vladimir; Brey, Gerhard P.; Höfer, Heidi E.; Woodland, Alan B.

2014-02-01

128

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

NASA Astrophysics Data System (ADS)

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 magma which sampled and transported the xenocrysts. The "Ni thermometer" of Griffin et al. [1989], based on the strong temperature dependence of the partitioning of Ni between garnet and olivine, is refined using an expanded database. Pressure is calculated from garnet composition using an algorithm that combines a modification of the geobarometer of Nickel [1989], based on Cr solubility in coexisting garnet and orthopyroxene, with the composition of a hypothetical coexisting orthopyroxene. The orthopyroxene composition is estimated by inverting the geothermometry equations of Gasparik [1987], Brey and Köhler [1990], and Harley [1984], and combining these with empirical relationships describing Cr in orthopyroxene in Cr-saturated peridotite (chromite present). The derived pressure (PCr) gives the equilibration pressure of peridotic garnets provided they were in equilibrium with chromite; garnets from Cr-undersaturated rocks will produce underestimates of pressure. Therefore, the locus of maximum PCr at a given TNi defines the "garnet geotherm", and provides a method for the determination of paleogeotherms based solely on PIXE and EMP analyses of garnet grains in concentrates. The assumption of coexisting chromite is tested by comparing the temperature distributions of garnets and chromites from the same concentrate. Chromite equilibration temperature is estimated using the "Zn thermometer", based on the strong temperature dependence of the partitioning of Zn between chromite and olivine. This thermometer is calibrated against the new Ni thermometer using a suite of garnet-chromite intergrowths. The garnet geotherm technique provides an estimate of the geotherm with an accuracy comparable to xenolith-derived geotherms and provides a means of mapping the thermal state of the lithosphere where xenoliths are rare or absent.

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

1996-03-01

129

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

130

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

NASA Astrophysics Data System (ADS)

The Gd 3Fe 5O 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 Hr and the local magnetic anisotropy constant KL. 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.

Lassri, H.; Hlil, E. K.; Prasad, S.; Krishnan, R.

2011-12-01

131

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

132

Growth of Dislocation-Free Gallium Crystals.  

National Technical Information Service (NTIS)

Single crystals of gallium were grown with large portions free of dislocations detectable by anomalous transmission of x-rays. The crystals are grown by an unconstrained solidification technique. The very small supersaturation of vacancies in gallium at r...

S. H. McFarlane C. Elbaum

1965-01-01

133

Potential effects of gallium on cladding materials.  

National Technical Information Service (NTIS)

This paper identifies and examines issues concerning the incorporation of gallium in weapons derived plutonium in light water reactor (LWR) MOX fuels. Particular attention is given to the more likely effects of the gallium on the behavior of the cladding ...

D. F. Wilson E. C. Beahm T. M. Besmann J. H. DeVan J. R. DiStefano

1997-01-01

134

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

135

Pyroelectric Detection Properties of Gadolinium Molybdate (GMO).  

National Technical Information Service (NTIS)

The pyroelectric detection properties of gadolinium molybdate (GMO) crystals have been studied near and at its 159C ferroelectric transition temperature. Responsivity and detectivity figures of merit for TGS and SBN detectors. Since GMO does not exhibit a...

B. N. Ganguly F. G. Ullman J. R. Zeidler

1972-01-01

136

Status of gadolinium enrichment technology at LLNL.  

National Technical Information Service (NTIS)

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 resu...

C. Haynam B. Comaskey J. Conway J. Eggert J. Glaser

1993-01-01

137

NIST Realization of the Gallium Triple Point.  

National Technical Information Service (NTIS)

The gallium triple point (302.9166 K) instead of the gallium melting point (302.9146 K) is used at NIST in the realization of the International Temperature Scale of 1990 (ITS-90). Four different sources of gallium with purities of at least 99.999 995 wt. ...

G. F. Strouse

2008-01-01

138

Structure of dental gallium alloys.  

PubMed

The interest in gallium alloys as a replacement for amalgam has increased in recent years due to the risk of environmental pollution from amalgam. Alloy powders with compositions close to those for alloys of amalgam are mixed with a liquid gallium alloy. The mix is condensed into a prepared cavity in much the same way as for amalgam. The aim of the present work was to study the structure of: (1) two commercial alloy powders containing mainly silver, tin and copper, and (2) the phases formed by mixing these powders with a liquid alloy of gallium, indium and tin. One of the alloy powders contained 9 wt% palladium. Cross-sections of cylindrical specimens made by these gallium mixes were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Discrete grains of the following phases were found to be present in both gallium alloys: hexagonal Ag2Ga, tetragonal Cu(Pd)Ga2, cubic Ag9In4 and tetragonal beta-Sn. Indications of hexagonal or orthorhombic Ag2Sn were found in the remaining, unreacted alloy particles. In the palladium-containing alloy the X-ray reflections indicate a minor fraction of cubic Cu9Ga4 in addition to the Cu(Pd)Ga2 phase. Particles of beta-Sn are probably precipitated because Sn-Ga phases cannot be formed according to the binary phase diagram. PMID:8805980

Herø, H; Simensen, C J; Jørgensen, R B

1996-07-01

139

Synthesis and Crystal Chemistry of Oxysulfides with the Garnet Structure.  

National Technical Information Service (NTIS)

In a search for new ternary materials with potential suitability for 10.6 micrometer window applications, the sulfur analogs of the garnet structure were investigated. Pure sulfur end-member garnets cannot be synthesized under ambient pressures. A series ...

R. R. Neurgaonkar W. B. White

1973-01-01

140

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

141

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

142

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

143

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

144

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

145

Cost and Availability of Gadolinium for Nuclear Fuel Reprocessing Plants.  

National Technical Information Service (NTIS)

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 ...

O. H. Klepper

1985-01-01

146

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

147

Micro-Raman spectra of ugrandite garnet  

NASA Astrophysics Data System (ADS)

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 3Y 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.

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

2009-08-01

148

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

149

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

150

Tunable wideband microwave band-stop and band-pass filters using YIG\\/GGG-GaAs layer structures  

Microsoft Academic Search

Magnetically tunable wideband microwave bandstop and bandpass filters using ferromagnetic resonance absorption in yttrium iron garnet\\/gadolinium gallium garnet-gallium arsenide (YIG\\/GGG-GaAs) layer structures are reported. The measured characteristics of the bandstop filter, with nonuniform bias magnetic field distribution along the YIG\\/GGG film, shows a large absorption bandwidth of 1900 MHz at the stopband center frequency of 11.0 GHz, average peak absorption

C. S. Tsai; G. Qiu; H. Gao; L. W. Yang; G. P. Li; S. A. Nikitov; Y. Gulyaev

2005-01-01

151

Wideband Microwave Filters Using Ferromagnetic Resonance Tuning in Flip-Chip YIG-GaAs Layer Structures  

Microsoft Academic Search

In this paper the most recent advances on ferromagnetic resonance (FMR)-based wideband microwave band-stop and band-pass filters using flip-chip yttrium iron garnet (YIG)\\/gadolinium gallium garnet (GGG)- gallium arsenide (GaAs) layer structures are reported. Specifically, simultaneous enhancement in tunable bandwidths and peak absorption levels by utilizing the meander microstrip line with step-impedance low-pass filter design together with inhomogeneous magnetic field has

Chen S. Tsai; Gang Qiu

2009-01-01

152

Thermal expansion of gallium nitride  

Microsoft Academic Search

Lattice constants of gallium nitride (wurzite structure) have been measured at temperatures 294 - 753 K. The measurements were performed by using x-ray diffractometry. Two kinds of samples were used: (1) bulk monocrystal grown at pressure of 15 kbar, (2) epitaxial layer grown on a sapphire substrate. The latter had a smaller lattice constant in a direction parallel to the

M. Leszczynski; T. Suski; H. Teisseyre; P. Perlin; I. Grzegory; J. Jun; S. Porowski; T. D. Moustakas

1994-01-01

153

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

154

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

155

Chrome doped gallium arsenide evaluation  

Microsoft Academic Search

We received, for free, two sets of Chrome doped Gallium Arsenide (GaAs:Cr) wafers, one from Cominco Electronic Materials, Inc., and the other from Furakawa Electric Co., for the purpose of evaluation as potential material for high speed photoconductive detectors. In return for the free material we promised to give the two manufacturers feed back on our evaluation of these wafers.

M. D. Pocha; J. D. Morse; W. F. Brazes

1987-01-01

156

Gallium scan in intracerebral sarcoidosis  

SciTech Connect

Sarcoidosis involving the nervous system probably occurs in about 4% of patients. The usefulness of brain scintigraphy in these cases has been suggested. In this case of cerebral sarcoid granuloma, gallium imaging demonstrated the lesion before treatment and showed disappearance of the lesion after corticosteroid treatment, which correlated with the patient's clinical improvement.

Makhija, M.C.; Anayiotos, C.P.

1981-07-01

157

Synthesis of polycrystalline yttrium iron garnet and yttrium aluminium garnet from organic precursors  

Microsoft Academic Search

Polycrystalline Y3Fe5O12 (YIG) and Y3Al5O12 (YAG) garnets have been prepared by the organic solution technique using a novel organic precursor. The thermal decomposition of the precursor and subsequent formation of the garnet phases was studied by thermal analysis, X-ray diffraction and Fourier transform infra red spectroscopy (FTIR) including diffuse reflectance FTIR (DRIFT). The precursor of YIG decomposes to give the

C. D. Veitch

1991-01-01

158

40 CFR 721.10391 - Copper gallium indium selenide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Copper gallium indium selenide. 721.10391...Chemical Substances § 721.10391 Copper gallium indium selenide. (a) Chemical...The chemical substance identified as copper gallium indium selenide (PMN...

2013-07-01

159

Electronic and Magnetic Raman Effect in Garnets.  

National Technical Information Service (NTIS)

The report summarizes the results of research of the electronic and magnetic Raman effect in garnets. The principal results include the determination of Raman active phonons and electronic levels in DyAlG, DyGaG, YbAlG, YbGaG, and LuAlG. The experimental ...

R. K. Chang

1971-01-01

160

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

161

Source of fecal gallium--clinical implications: concise communication. [Gallium67 kinetics in rats  

Microsoft Academic Search

Bowel preparation before gallium-67 scanning often conists of cathartics, enemas, and a liquid or low-residue diet. Since human bile has approximately one-third the gallium concentration of the liver, the diet is presumably designed to minimize biliary excretion of gallium into the gut. To determine the actual biliary contribution to fecal gallium, the bile ducts of 15 rats were ligated and

A. Taylor; N. Chafetz; J. Hollenbeck; W. Hooser

1978-01-01

162

Hydrogen solubility in garnet at high pressures  

NASA Astrophysics Data System (ADS)

Garnet is the most important secondary mineral whose fraction ranges from ~ 20% in the shallow upper mantle for the pyrolite model to ~ 80% in the transition zone for the piclogite model. Therefore understanding the solubility and dissolution mechanisms of hydrogen in garnet is important for water budget as well as for understanding plastic properties of the mantle. However, there is little consensus on the solubility and dissolution mechanisms of hydrogen in garnet. For example, under deep upper mantle conditions (P>7 GPa), Withers et al. (1998) concluded virtually no hydrogen solubility in pyrope whereas Lu and Keppler (1997) showed small hydrogen solubility (~ 200 ppm wt of H2O). In order to address possible causes of such discrepancy, we have initiated a systematic study on hydrogen solubility under a broad range of pressure and controlled chemical environment. In contrast with the previous study, preliminary results indicate that natural garnet crystal surrounded by powder of olivine, orthopyroxene and clinopyroxene, could host around 1000 ppm wt of H2O at 9 GPa and 1100 °C conditions. Possible interpretation is that the enrichment of hydrogen is due to the increased Mg/Si ratio (activity of MgO) due to the coexistence of garnet with olivine. If hydrogarnet substitution (O4H4) is the dominant mechanism of hydrogen dissolution, then the increase in the activity of MgO will increase the hydrogen solubility. Further experiments are performed (i) to investigate the hydrogen solubility under deep upper mantle conditions (P=6-9 GPa T=1373-1573 K) where the previous results have a major discrepancy, and (ii) to investigate the kinetics and the influence of oxide buffer on hydrogen solubility.

Mookherjee, M.; Karato, S.-

2007-12-01

163

Measurement of arsenic and gallium content of gallium arsenide semiconductor waste streams by ICP-MS  

Microsoft Academic Search

The chemistry of semiconductor wafer processing liquid waste, contaminated by heavy metals, was investigated to determine arsenic content. Arsenic and gallium concentrations were determined for waste slurries collected from gallium arsenide (GaAs) wafer processing at three industrial sources and compared to slurries prepared under laboratory conditions. The arsenic and gallium content of waste slurries was analyzed using inductively coupled plasma

Keith W. Torrance; Helen E. Keenan; Andrew S. Hursthouse; David Stirling

2010-01-01

164

Gallium-Arsenide Point-Contact Diodes  

Microsoft Academic Search

This paper describes some of the work on gallium-arsenide point-contact diodes which is currently in progress at the Bell Telephone Laboratories, Holmdel, N. J. Gallium arsenide, one of the Group III-V intermetallic compounds, possesses properties which tend to make it superior to either silicon or germanium for many high-frequency diode applications. By controlling the resistivity of the gallium arsenide and

W. M. Sharpless

1961-01-01

165

Epitaxial Deposition Of Germanium Doped With Gallium  

NASA Technical Reports Server (NTRS)

Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

Huffman, James E.

1994-01-01

166

Superconductivity and structure of gallium under nanoconfinement  

Microsoft Academic Search

Superconductivity and crystalline structure were studied for two nanocomposites consisting of gallium loaded porous glasses with different pore sizes. The superconducting transition temperatures were found to differ from those in known bulk gallium modifications. The transition temperatures 7.1 and 6.7 K were ascribed to two new confined gallium structures, iota- and kappa-Ga, observed by synchrotron radiation x-ray powder diffraction. The

E. V. Charnaya; Cheng Tien; Min Kai Lee; Yu A. Kumzerov

2009-01-01

167

Superconductivity and structure of gallium under nanoconfinement  

Microsoft Academic Search

Superconductivity and crystalline structure were studied for two nanocomposites consisting of gallium loaded porous glasses with different pore sizes. The superconducting transition temperatures were found to differ from those in known bulk gallium modifications. The transition temperatures 7.1 and 6.7 K were ascribed to two new confined gallium structures, ?- and ?-Ga, observed by synchrotron radiation x-ray powder diffraction. The

E V Charnaya; Cheng Tien; Min Kai Lee; Yu A Kumzerov

2009-01-01

168

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

169

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

170

Pyroelectric detection properties of gadolinium molybdate (gmo)  

Microsoft Academic Search

The pyroelectric detection properties of gadolinium molybdate (GMO) crystals have been studied near and at its 159°C ferroelectric transition temperature. Responsivity and detectivity figures of merit are calculated from measurements of pyroelectric currents induced by white light irradiation and are compared with room temperature figures of merit for TGS and SBN detectors. Since GMO does not exhibit a dielectric anomaly,

F. G. Ullman; B. N. Ganguly; J. R. Zeidler

1972-01-01

171

Neutron Resonance Parameters for Gd-155 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-155 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

Sukhoruchkin, S. I.; Soroko, Z. N.

172

Neutron Resonance Parameters for Gd-158 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-158 (Gadolinium). Also included are spectra of gamma-rays from neutron resonance capture.

Sukhoruchkin, S. I.; Soroko, Z. N.

173

Neutron Resonance Parameters for Gd-152 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-152 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

Sukhoruchkin, S. I.; Soroko, Z. N.

174

Neutron Resonance Parameters for Gd-156 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-156 (Gadolinium).

Sukhoruchkin, S. I.; Soroko, Z. N.

175

Neutron Resonance Parameters for Gd-160 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-160 (Gadolinium).

Sukhoruchkin, S. I.; Soroko, Z. N.

176

Neutron Resonance Parameters for Gd-153 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-153 (Gadolinium).

Sukhoruchkin, S. I.; Soroko, Z. N.

177

Neutron Resonance Parameters for Gd-157 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-157 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

Sukhoruchkin, S. I.; Soroko, Z. N.

178

Neutron Resonance Parameters for Gd-154 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-154 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

Sukhoruchkin, S. I.; Soroko, Z. N.

179

Neutron Resonance Parameters for Gd158 (Gadolinium)  

Microsoft Academic Search

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-158 (Gadolinium). Also included are spectra of gamma-rays from neutron resonance capture.

S. I. Sukhoruchkin; Z. N. Soroko

2009-01-01

180

Resonance Parameter Measurements and Analysis of Gadolinium  

Microsoft Academic Search

The purpose of the present work is to measure the neutron cross sections of gadolinium accurately. Gd has the highest thermal absorption cross section of any natural element. Therefore it is an important element for thermal reactor applications Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute (RPI) LINAC facility using metallic and

G Leinweber; DP Barry; MJ Trbovich; JA Burke; NJ Drindak; HD Knox; RV Ballad; RC Block; Y Danon; LI Severnyak

2006-01-01

181

Neutron Resonance Parameters for Gd152 (Gadolinium)  

Microsoft Academic Search

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-152 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

S. I. Sukhoruchkin; Z. N. Soroko

2009-01-01

182

Neutron Resonance Parameters for Gd154 (Gadolinium)  

Microsoft Academic Search

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-154 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

S. I. Sukhoruchkin; Z. N. Soroko

2009-01-01

183

Neutron Resonance Parameters for Gd157 (Gadolinium)  

Microsoft Academic Search

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-157 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

S. I. Sukhoruchkin; Z. N. Soroko

2009-01-01

184

Neutron Resonance Parameters for Gd155 (Gadolinium)  

Microsoft Academic Search

This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Gd-155 (Gadolinium). Also included are spectra of direct gamma-rays from neutron resonance capture.

S. I. Sukhoruchkin; Z. N. Soroko

2009-01-01

185

Substrates for gallium nitride epitaxy  

Microsoft Academic Search

In this review, the structural, mechanical, thermal, and chemical properties of substrates used for gallium nitride (GaN) epitaxy are compiled, and the properties of GaN films deposited on these substrates are reviewed. Among semiconductors, GaN is unique; most of its applications uses thin GaN films deposited on foreign substrates (materials other than GaN); that is, heteroepitaxial thin films. As a

L. Liu; J. H. Edgar

2002-01-01

186

Ion Implantation in Gallium Arsenide  

Microsoft Academic Search

Ion implantation is a useful method to incorporate dopants into semiconductors. Understanding implantation processes is essential to the advancement of solid state technology. Because of its technical importance, gallium arsenide (GaAs) was chosen for this study. Hall effect, x-ray diffraction, and electrochemical capacitance-voltage (CV) profiling were used to study activation of silicon implants as functions of dose and annealing temperature

John Hamilton Madok

1993-01-01

187

Hepatocellular carcinoma detection by gallium scan and subsequent treatment by gallium maltolate: rationale and case study.  

PubMed

Gallium is antiproliferative to many types of cancer, due primarily to its ability to act as a non-functional mimic of ferric iron (Fe(3+)). Because Fe(3+) is needed for ribonucleotide reductase activity--and thus DNA synthesis--gallium can inhibit DNA production and cell division. Diagnostic gallium scans have shown that hepatocellular carcinoma (HCC) is commonly avid for gallium. Furthermore, in vitro studies have found that gallium nitrate, and particularly gallium maltolate (GaM), have dose-dependent antiproliferative activity against HCC cell lines. Rationale thus exists to use GaM, an orally active compound that has been well tolerated in Phase I clinical trials, to treat patients whose HCC is gallium-avid in a gallium scan. Because gallium absorbed from orally administered GaM is bound predominately to serum transferrin, which travels to all tissues in the body, GaM has the potential to treat even distant metastases. A patient with advanced HCC (20 × 10 cm primary tumor, ascites around liver and spleen, resistant to Nexavar(®) (sorafenib)), whose cancer was highly gallium-avid in a (67)Ga-scan, was treated with oral gallium maltolate at 1500 mg/day q.d. After four weeks of treatment, the patient had a large reduction in pain, with greatly increased mobility and quality of life, and significantly lowered serum bilirubin and inflammation-related liver enzymes. At eight weeks, CT scans showed apparent necrosis of the tumor. PMID:21554205

Bernstein, Lawrence R; van der Hoeven, Jacobus J M; Boer, Robbert O

2011-07-01

188

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

189

Fabrication of transparent yttrium aluminum garnet ceramic  

Microsoft Academic Search

In this paper, the synthesis of Nd-doped yttrium aluminum garnet (Nd:YAG) spherical nano-crystallites was investigated by using the solvothermal method, and the optimum processing conditions for processing the transparent ceramic preparation was determined. Powder consisting of nanosized particles obtained by the solvothermal method displays significantly less crystallite agglomeration, indicating a high degree of sinterability. The phase structure and the morphology

Xia Li

2009-01-01

190

Neutron Irradiation of LPE Bubble Domain Garnets  

Microsoft Academic Search

Five LPE iron garnets were irradiated in two steps to a total of 2 × 1015 n\\/cm2 (En > 10 keV). Samples included GdEr-, GdY-, GdYTm-, GdYYb- and GdYLa-IG's. Pre- and post-irradiation measurements were made of l, 4piMs, Ho, Hk and muw. A pre-irradiation simulation of ambient reactor conditions showed that the properties were not affected by these influences. Post-irradiation

R. S. Sery; H. R. Irons

1974-01-01

191

Induced striations in LPE garnet layers  

Microsoft Academic Search

At a given chemical composition of a solution the composition of the deposited material depends on the growth rate. Therefore\\u000a well defined changes of the growth rate can be used to prepare single crystals or LPE layers with defined changes of the composition.\\u000a In the case of garnet single crystals the growth rate has been modulated by the variation of

P. Gornert; S. Bornmann

1979-01-01

192

Neutron Irradiation of LPE Bubble Domain Garnets  

Microsoft Academic Search

Five LPE iron garnets were irradiated in two steps to a total of 2 × 1015 n?cm2 (En > 10 keV). Samples included GdEr-, GdY-, GdYTm-, GdYYb- and GdYLa-IG's. Pre- and post-irradiation measurements were made of ℓ, 4?Ms, Ho, Hk and ?w. A pre-irradiation simulation of ambient reactor conditions showed that the properties were not affected by these influences. Post-irradiation

R. S. Sery; H. R. Irons

1974-01-01

193

Ion implant profiles in garnet films  

Microsoft Academic Search

Chemical etch rate and magnetization profiles of neon implanted LPE garnet films were obtained by successively etching thin layers and measuring both weight loss and soft bubble collapse fields. Implant energies and doses in the ranges 60 to 160 keV and .5 to 10×1014 cm-2, respectively, were used. Etch rate profiles are similar in shape to typical implanted ion distributions

H. A. Washburn; G. Galli

1979-01-01

194

XPS investigation of LPE garnet films  

Microsoft Academic Search

XPS spectra of YIG, YIG:Bi, YIG:Ca and YIG:Co(Ge, Ca) epitaxial garnet films were measured at room temperature. The positions of the main iron, yttrium, oxygen, bismuth, cobalt and lead spectral lines were determined and their changes with the surface treatments were investigated. It was found that divalent and trivalent states of iron and cobalt ions can be resolved, the chemical

Z. šimša; J. Zemek

1990-01-01

195

Dynamic recrystallization of garnet and related diffusion processes  

Microsoft Academic Search

Electron backscatter diffraction and compositional data of Permian metapegmatite garnet from the Koralpe basement (Eastern Alps, Austria) show the evolution of distinct intracrystalline shear zones in c. 10mm sized almandine–spessartine garnet. Orientation maps reveal continuous distortion of the crystal lattice. New garnet grains (grain size 20–30?m) within intragranular deformation zones, oriented subparallel to the main foliation of the metapegmatite, have

Michel Bestmann; Gerlinde Habler; Florian Heidelbach; Martin Thöni

2008-01-01

196

Rare earth diffusion kinetics in garnet: Experimental studies and applications  

Microsoft Academic Search

We determined the diffusion coefficient of Sm in almandine garnet as function of temperature at 1 bar and fO2 corresponding to that of wüstite-iron buffer, and to a limited extent, that of a few other selected rare earth elements in almandine and pyrope garnets. Both garnets were demonstrated to have metastably survived the diffusion annealing at conditions beyond their stability

Massimiliano Tirone; Jibamitra Ganguly; Ralf Dohmen; Falko Langenhorst; Richard Hervig; Hans-Werner Becker

2005-01-01

197

Broad-band emission from chromium doped germanium garnets  

Microsoft Academic Search

By varying the composition of a series of germanium garnets, it is possible to change the lattice constant of the structure over a wide range, and thus the crystal field. Three Cr-doped germanium garnets (CaâAlâGeâthetaââ, CaYâMgâGeâthetaââ, and MgYâMgâGeâtheta ââ) have been grown as single crystals. Spectroscopic results show that in these garnets the broad-band emission at room temperature is so

H. P. Christensen; H. P. Jenssen

1982-01-01

198

Study of defects in reduced LPE bubble garnet films  

Microsoft Academic Search

Aluminum deposited on LPE bubble garnet films, which are then heated for 0.5 hour at 450°C, has been used to study reduction-associated defects in garnets. This treatment leaves the garnet darkened by magnetically unchanged. Subsequent heating at ?600°C with the A1 removed, causes a controllable reduction in magnetization due to Ga-Fe redistribution, accelerated by the defects introduced at 450°C. Defects

R. C. Lecraw; E. M. Gyorgy; R. Wolfe

1976-01-01

199

Study of defects in reduced LPE bubble garnet films  

Microsoft Academic Search

Aluminum deposited on LPE bubble garnet films, which are then heated for 0.5 hour at 450°C, has been used to study reduction-associated defects in garnets. This treatment leaves the garnet darkened by magnetically unchanged. Subsequent heating at &angupr;600°C with the A1 removed, causes a controllable reduction in magnetization due to Ga-Fe redistribution, accelerated by the defects introduced at 450°C. Defects

R. C. LeCraw; E. M. Gyorgy; R. Wolfe

1976-01-01

200

Gallium nitride growth using diethyl gallium chloride as an alternative gallium source  

NASA Astrophysics Data System (ADS)

Diethyl gallium chloride (DEGaCl) was employed as an alternative gallium precursor in the epitaxial growth of GaN for producing a hydride vapor-phase epitaxy (HVPE)-like growth chemistry in a metal-organic vapor-phase epitaxy (MOVPE) system. The standard 'two-step' GaN growth process was carried out using this Cl-containing precursor and compared to the conventional growth using trimethyl gallium (TMGa) source under identical reactor conditions. The growth rate during DEGaCl-based growth decreases with increasing temperature, indicating that the growth front may be close to local thermodynamic equilibrium. A direct comparison of materials properties associated with these precursors in various structural combinations of buffer and high-temperature GaN epilayers was performed. Improved material properties and a significant difference in the surface morphology were observed in the case of DEGaCl-based high-temperature growth, as determined by X-ray diffraction, capacitance-voltage, atomic force microscopy and photoluminescence measurements. We attributed the improved growth behavior to the 'nearer-to-equilibrium' growth front that could result from the presence of HCl-related etching reactions.

Zhang, L.; Gu, S. L.; Kuech, T. F.; Boleslawski, Marek P.

2000-05-01

201

Garnet phosphors prepared via hydrothermal synthesis  

SciTech Connect

This project studied hydrothermal synthesis as a route to producing green-emitting cathodoluminescent phosphorus isostructural with yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, or YAG). Aqueous precipitation of Y, Gd, Al, Ga, and Tb salts produced amorphous gels, which were heated with water at 600 C and 3,200 bar to produce crystalline YAG:Tb, Y{sub 3}Ga{sub 5}O{sub 12}:Tb, Y{sub 3}Al{sub 3}Ga{sub 2}O{sub 12}:Tb, and Gd{sub 3}Ga{sub 5}O{sub 12}:Tb powders. Process parameters were identified that yielded submicron YAG:Tb and Y{sub 3}Ga{sub 5}O{sub 12}:Tb powders without grinding. Cathodoluminescent efficiencies were measured as functions of power density at 600 V, using both the hydrothermal garnets and identical phosphor compositions synthesized at high temperatures. Saturation behavior was independent of synthetic technique, however, the hydrothermal phosphorus were less susceptible to damage (irreversible efficiency loss) at very high power densities (up to 0.1 W/cm{sup 2}). The fine grain sizes available with hydrothermal synthesis make it an attractive method for preparing garnet phosphorus for field emission, projection, and head-up displays.

Phillips, M.L.F.; Walko, R.J.; Shea, L.E.

1996-05-01

202

Determination of gallium by adsorptive stripping voltammetry.  

PubMed

A procedure for the determination of gallium by differential pulse adsorptive stripping voltammetry (DPADSV), using different complexing agents (ammonium pyrrolidine dithiocarbamate (APDC), pyrocatechol violet (PCV) and diethyldithiocarbamate (DDTC)), has been optimized. The selection of the experimental conditions was made using experimental design methodology. Under these conditions, the calibration was made and the detection limit was determined for each gallium-ligand complex. A robust regression method was applied which allowed the elimination of anomalous points. The detection limit, with alpha=beta=0.05, for gallium-APDC complex was 5.0x10(-8)moldm(-3), for gallium-PCV complex was 9.9x10(-9)moldm(-3), and the lowest detection limit (1.3x10(-9)moldm(-3)) was obtained with DDTC. For this reason, DDTC was selected for the determination of the gallium concentration in a certificate sample and in a spiked tap water sample. The linear dynamic range for gallium-APDC complex was from 5.0x10(-8) to 2.7x10(-7)moldm(-3), for gallium-PCV complex was from 5.0x10(-9) to 4.8x10(-7)moldm(-3), and for gallium-DDTC complex was from 1.0x10(-9) to 2.1x10(-7)moldm(-3). PMID:18969318

González, M Jesús Gómez; Renedo, Olga Dom? Nguez; Lomillo, M Asunción Alonso; Mart? Nez, M Julia Arcos

2004-02-27

203

Super-Si garnet exsolution kinetics denotes multistage mantle exhumation  

NASA Astrophysics Data System (ADS)

Previous decompression experiments have shown that super-Si garnet decomposes to normal garnet + pyroxene, which supports that natural analogues (found in mantle xenoliths, diamond inclusions, peridotite massifs) record up to several hundreds of kilometre exhumation, all proposed to apply to contrasting geological scenarios including mantle convection, kimberlite magmatism and plate tectonics. To verify this proposition we used glass powder with a 'pyrolite minus olivine' composition for polycrystalline dry super-Si garnet synthesis (18 GPa, 1600 °C, 2 1/3 h) and subsequent decompression (10 GPa, 1450 °C, 0-12 h). All samples recovered after decompression share a coronitic texture of new grains of garnet + pyroxene that surround relic super-Si garnet. Quantified XRD spectra show transformed volumes are similar, ~40 %, that mark a rapid decrease of the transformation rate within the first minutes of the decompression runs. Fitted kinetic data does not fulfil conditions for steady nucleation and growth. The Tschermak's component of corona clinopyroxene is four times higher than that of equilibrium clinopyroxene synthesised along with each decompression experiment. Element concentration profiles (TEM EDS) and element mapping (FE-SEM EDS) across the corona microstructure show steep but discontinuous Al concentration gradients at both relic and corona garnet grain margins. Transformation rate and mineral chemistry suggest that volume diffusion (1) exceeds decompression induced initial partial breakdown of super-Si garnet and (2) will be rate limiting for exsolution to reach equilibrium. Modelled Si-Al and Si-Al-Mg interdiffusion in garnet at different water contents in combination with geological cooling rates suggests that diffusion distances exceed metamorphic garnet grain sizes of ?1 cm within the amphibolit facies, unless dry conditions apply. In contrast, mantle garnet of 1-2 cm in size may allow for up to two types of pyroxene precipitiation, depending on the garnet origin. Exsolution of diamond inclusions occurred prior to lithosphere transit, but is sensitive to internal pressure and hence kinetically difficult to interpret. We suggest that the breakdown of natural super-Si garnet forms two distinct decomposition microstructures, a corona type and a lamellae type, depending on whether diffusion distances exceed the garnet grain size or not. Diffusion distances and statistics on natural occurrences of the lamellae type decomposition microstructure comply with an origin within the SCLM during secular cooling of the Earth. Given the affinity of super-Si garnet breakdown microstructure occurrence to Archaean areas at global scale, models for craton stabilisation require the inclusion of processes that allow garnet bearing SCLM growth in the garnet peridotite stability field. Preceeding shallower stages would have erased the microstructural record.

Spengler, Dirk; Nishihara, Yu; Fujino, Kiyoshi

2013-04-01

204

An unusual case of gallium scan mimicking a bone scan.  

PubMed

Gallium-67 localization is based on the fact that it binds to plasma proteins like transferrin and lactoferrin, which have iron-binding sites. Abnormal biodistribution of gallium-67 citrate can occur in iron-overload states. We report one such case of gallium scan mimicking a bone scan due to skeletal uptake of gallium. PMID:22616033

Puranik, Ameya; Luthra, Karuna; Lele, R D

2012-01-01

205

An Unusual Case of Gallium Scan Mimicking a Bone Scan  

PubMed Central

Gallium-67 localization is based on the fact that it binds to plasma proteins like transferrin and lactoferrin, which have iron-binding sites. Abnormal biodistribution of gallium-67 citrate can occur in iron-overload states. We report one such case of gallium scan mimicking a bone scan due to skeletal uptake of gallium.

Puranik, Ameya; Luthra, Karuna; Lele, R. D.

2012-01-01

206

Pilot installation of the gallium-germanium solar neutrino telescope  

Microsoft Academic Search

The advantages and disadvantages of using a metal gallium target in a gallium solar neutrino experiment are briefly reviewed, and a pilot gallium-germanium installation using 7 tons of gallium metal is described. In particular, attention is given to the chemical procedure, the counting system, and preliminary results of Ge-71 and Ge-69 yields from cosmic rays. Finally, the possibility of conducting

I. R. Barabanov; E. P. Veretenkin; V. N. Gavrin; S. N. Danshin; L. A. Eroshkina; G. T. Zatsepin; Y. I. Zakharov; S. A. Klimova; Y. B. Klimov; T. V. Knodel

1985-01-01

207

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

208

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

209

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

210

Synthesis of polycrystalline yttrium iron garnet and yttrium aluminium garnet from organic precursors  

Microsoft Academic Search

Polycrystalline Y3Fe5O12 (YIG) and Y3Al5O12 (YAG) garnets have been prepared by the organic solution technique using a novel organic precursor. The thermal decomposition\\u000a of the precursor and subsequent formation of the garnet phases was studied by thermal analysis, X-ray diffraction and Fourier\\u000a transform infra red spectroscopy (FTIR) including diffuse reflectance FTIR (DRIFT). The precursor of YIG decomposes to give\\u000a the

C. D. Veitch

1991-01-01

211

Method of separating and purifying gadolinium-153  

SciTech Connect

The present invention is an improvement to the method of separating and purifying gadolinium from a mixture of gadolinium and europium having the steps of (a) dissolving the mixture in an acid; (b) reducing europium+3 to europium+2; and (c) precipitating the europium+2 with a sulfate ion in a superstoichiometric amount; wherein the improvement is achieved by using one or more of the following: (i) the acid is an anoic acid; (ii) the reducing is with zinc metal in the absence of a second metal or with an amount of the second metal that is ineffective in the reducing; (iii) adding a group IIA element after step (c) for precipitating the excess sulfate prior to repeating step (c); (iv) the sulfate is a sulfate salt with a monovalent cation; (v) adding cold europium+3 prior to repeating step (c).

Bray, Lane A. (Richland, WA) [Richland, WA; Corneillie, Todd M. (Davis, CA) [Davis, CA

2001-01-01

212

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

213

Pyroelectric detection properties of gadolinium molybdate (gmo)  

Microsoft Academic Search

The pyroelectric detection properties of gadolinium molybdate (GMO) crystals have been studied near and at its 159?C ferroelectric\\u000a transition temperature. Responsivity and detectivity figures of merit are calculated from measurements of pyroelectric currents\\u000a induced by white light irradiation and are compared with room temperature figures of merit for TGS and SBN detectors. Since\\u000a GMO does not exhibit a dielectric anomaly,

F. G. Ullman; B. N. Ganguly; J. R. Zeidler

1972-01-01

214

Method of using gadolinium neutron capture to treat cancers  

US Patent & Trademark Office Database

Described is a method of using gadolinium-containing compounds as agents for neutron capture therapy to treat neoplastic cell growth. The subject is exposed to a gadolinium-containing compound for a time sufficient to allow the compound to accumulate in neoplastic cells. The subject is then exposed to a thermal and/or epithermal neutron flux, thereby initiating a neutron capture reaction in the gadolinium atoms that results in specific death of neoplastic cells.

2004-08-03

215

Preparation and Properties of Nitrate-Deficient Gadolinium Nitrate Solutions  

SciTech Connect

Because of the high neutron absorption cross sections of some gadolinium isotopes, gadolinium salts in solution are used to control nuclear reactivity in aqueous systems. The present studies concern the preparation and analysis of nitrate-deficient solutions, the effect of time and gamma radiation on their stability, and the determination of the solubility of gadolinium hydroxide in H2O and D2O.

Baumann, E.W.

2001-03-15

216

Atomistic simulation of trace element incorporation into garnets - comparison with experimental garnet-melt partitioning data  

NASA Astrophysics Data System (ADS)

We have studied the energetics of trace element incorporation into pure almandine (Alm), grossular (Gros), pyrope (Py) and spessartine (Spes) garnets (X 3Al 2Si 3O 12, with X = Fe, Ca, Mg, Mn respectively), by means of computer simulations of perfect and defective lattices in the static limit. The simulations use a consistent set of interatomic potentials to describe the non-Coulombic interactions between the ions, and take explicit account of lattice relaxation associated with trace element incorporation. The calculated relaxation (strain) energies Urel are compared to those obtained using the Brice (1975) model of lattice relaxation, and the results compared to experimental garnet-melt trace element partitioning data interpreted using the same model. Simulated Urel associated with a wide range of homovalent (Ni, Mg, Co, Fe, Mn, Ca, Eu, Sr, Ba) and charge-compensated heterovalent (Sc, Lu, Yb, Ho, Gd, Eu, Nd, La, Li, Na, K, Rb) substitutions onto the garnet X-sites show a near-parabolic dependence on trace element radius, in agreement with the Brice model. From application of the Brice model we derived apparent X-site Young's moduli EX(1+, 2+, 3+) and the 'ideal' ionic radii r0(1+, 2+, 3+), corresponding to the minima in plots of Urel vs. radius. For both homovalent and heterovalent substitutions r0 increases in the order Py-Alm-Spes-Gros, consistent with crystallographic data on the size of garnet X-sites and with the results of garnet-melt partitioning studies. Each end-member also shows a marked increase in both the apparent EX and r0 with increasing trace element charge ( Zc). The increase in EX is consistent with values obtained by fitting to the Brice model of experimental garnet-melt partitioning data. However, the increase in r0 with increasing Zc is contrary to experimental observation. To estimate the influence of melt on the energetics of trace element incorporation, solution energies ( Usol) were calculated for appropriate exchange reactions between garnet and melt, using binary and other oxides to simulate cation co-ordination environment in the melt. Usol also shows a parabolic dependence on trace element radius, with inter-garnet trends in EX and r0 similar to those found for relaxation energies. However, r0( i+) obtained from minima in plots of Usol vs. radius are located at markedly different positions, especially for heterovalent substitutions ( i = 1, 3). For each end-member garnet, r0 now decreases with increasing Zc, consistent with experiment. Furthermore, although different assumptions for trace element environment in the melt, e.g., REE 3+ (VI) vs. REE 3+ (VIII), lead to parabolae with differing curvatures and minima, relative differences between end-members are always preserved. We conclude that: 1. The simulated variation in r0 and EX between garnets is largely governed by the solid phase. This stresses the overriding influence of crystal local environment on trace element partitioning. 2. Simulations suggest r0 in garnets varies with trace element charge, as experimentally observed. 3. Absolute values of r0 and EX can be influenced by the presence and structure of a coexisting melt. Thus, quantitative relations between r0, E and crystal chemistry should be derived from well-constrained systematic mineral-melt partitioning studies, and cannot be predicted from crystal-structural data alone.

van Westrenen, W.; Allan, N. L.; Blundy, J. D.; Purton, J. A.; Wood, B. J.

2000-05-01

217

Gadolinium Solubility in Peraluminous Borosilicate Glasses  

SciTech Connect

This paper discussed the results of a study, using 18 peraluminous (Na/Al <1) borosilicate glasses, to understand the effect of glass composition on gadolinium solubility. Above Gd solubility, liquid-liquid phase separation occurs in some of the glasses; in others, sodium gadolinium silicate crystallizes. For the samples in which liquid-liquid phase separation occurs, Gd solubility is determined by the concentration of excess Al (i.e., [AlO1.5]-[NaO0.5]-0.2*[BO1.5]). Increasing excess Al increases Gd solubility. For the samples in which sodium gadolinium silicate crystallizes, Gd solubility is determined by the concentration of Na. Increasing Na decreases Gd solubility. When the Al concentration in the baseline glass is high, a minimum amount of Gd is needed to form a clear glass. Otherwise, mullite crystallizes. The minimum concentration of Gd is determined by the [AlO1.5]-[NaO0.5]-[BO1.5] value in the melt. The higher this value is, the more Gd is needed to form a clear glass. In general, the solution behavior of Gd in peraluminous borosilicate melt is similar to that in peralkaline borosilicate melt, and is mostly determined by the ratio of excess Al to equivalent B in the melt.

Li, Liyu; Li, Hong; Qian, Maoxu; Strachan, Denis M.

2001-03-05

218

Trace Element Zoning in Garnets - Retrospective and Prospective  

NASA Astrophysics Data System (ADS)

Deployment of the Cameca IMS-3f (Joy) at MIT enabled the first SIMS analyses of trace-element zoning in garnets. Moderate energy filtering (-35 to -90 Ev) allowed the determination of rare-earth element (REE) and many other trace elements’ (TE) zoning in natural garnets (and determination of element concentrations with appropriate standards) with sub-ppm detection limits for many elements. TE zoning is complementary to major element (ME) zoning and provides additional insights into geologic processes where ME are ambiguous. Key areas where TE zoning in garnet is potentially useful include: (1) investigating reaction histories (including melting) particularly those involving TE-rich phases; (2) examination of disequilibrium processes during petrogenesis; (3) investigating metasomatic events (both fluid induced and melt induced); (4) tracing pressure-temperature-time (P-T-t) paths; and (5) supporting and guiding radiogenic isotope investigations. Both early (1980s) and recent examples of such applications will be discussed - specific TE are useful to investigate specific processes. For area (1) Y and LREE increases indicate involvement of epidote in garnet forming reactions. For (2) and (4) buffered TE such as Ti are particularly useful, although applications of TE in garnets to (4) have not proved fruitful. For (3) a range of fluid-enriched and melt-enriched elements including LREE & MREE are useful. The relevant data (garnet/fluid and garnet/mineral partition coefficients as a function of P, T, & fluid/mineral composition) needed to quantitatively model TE zoning remain largely unavailable. New ion probe technologies (e.g. large-magnet, high-resolution Cameca IMS 1280) open up a plethora of new opportunities to pursue ultra-TE abundance and stable isotopic (SI) zoning in garnets; however development of appropriate matrix-matched standards remains a formidable challenge. Ion implanted standards may be useful for such applications. SI zoning in garnet (and SI in garnet inclusions) may facilitate direct determination of P-T-t paths from garnet zoning.

Hickmott, D.; Shimizu, N.; Spear, F. S.

2009-12-01

219

Review of the Role of Garnet in the Martian Mantle  

NASA Astrophysics Data System (ADS)

Minimum depth of a putative Mars magma ocean can be constrained using the garnet to majorite transition in Fe-rich systems combined with predicted garnet-melt trace-element partitioning. This analysis suggests a minimum depth of ~1200 km.

Draper, D. S.

2012-09-01

220

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

221

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

222

Noncubic magnetic anisotropies in bulk and thin-film garnets  

Microsoft Academic Search

Magnetic bubbles have been reported in bulk grown, chemical vapor deposition (CVD), and liquid phase epitaxy (LPE) garnets, implying the existence of noncubic anisotropies in all of these materials. Anisotropy magnitudes, directions, nonuniformities, and annealing behaviors and effects of strain relief on the anisotropies of several potentially useful garnet materials are presented and compared. These observations indicate that the noncubic

ARJEH J. KURTZIG; FRED B. HAGEDORN

1971-01-01

223

Garnet and pyroxene compositions in some diamondiferous eclogites  

Microsoft Academic Search

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.

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

1976-01-01

224

Optical Reading From Videotapes Using Magnetic Garnet Film  

Microsoft Academic Search

In order to greatly increase the speed at which videotapes are read, we propose an optical reading method using a magnetic garnet film. This method allows several data tracks to be read in parallel. In order to realize the optical reading of data, the magnetic garnet films need to have not only high enough resolution for all data to be

Masahiko Kishida; Naoto Hayashi; Katsuhiro Iwasaki; Hiromitsu Umezawa; Tatsuo Nomura

2008-01-01

225

Ion-beam etching of groove patterns into garnet films  

Microsoft Academic Search

The technique of ion-beam milling is applied to the structuring of garnet layers. Rf-sputtered titanium is found to be an appropriate masking material as its sputter etch rate is small and almost independent from the angle of incidence of the ion beam. In contrast, the garnet has a prominent etch rate angular dependence. The optimal conditions for the generation of

JENS-PETER KRUMME; HEINZ DIMIGEN

1973-01-01

226

Electrospun Gallium Nitride Nanofibers (abstract)  

NASA Astrophysics Data System (ADS)

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 NH3 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.

Meléndez, Anamaris; Morales, Kristle; Ramos, Idalia; Campo, Eva; Santiago, Jorge J.

2009-04-01

227

Clinical applications of Gallium-68.  

PubMed

Gallium-68 is a positron-emitting radioisotope that is produced from a (68)Ge/(68)Ga 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. (68)Ga-DOTATOC, (8)Ga-DOTATATE, (68)Ga-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 (68)Ga 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 (68)Ga-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 (68)Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

Banerjee, Sangeeta Ray; Pomper, Martin G

2013-06-01

228

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.

Banerjee, Sangeeta Ray; Pomper, Martin G.

2013-01-01

229

The Soviet American Gallium Experiment (SAGE)  

SciTech Connect

A radiochemical experiment using the reaction v/sub e/ = /sup 71/Ga + e/sup e/ to determine the integral flux of low-energy neutrinos from the sun is currently under preparation at the Baksan Neutrino Observatory in the USSR. Measurements are scheduled to commence by late 1988 using /approximately/30 tonnes of metallic gallium. With this amount of gallium it should be possible to obtain a fractional statistical accuracy of 12 to 15% after one year (assuming the standard solar model neutrino flux). While initial measurements are in progress, installation of the remaining 30 tonnes of gallium will proceed in order to perform the full 60 tonne experiment.

Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.P.; Avdeyev, A.V.; Belousko, Yu.I.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gayevsky, V.I.; Gavrin, V.N.; Grigorjev, A.M.; Kalikhov, A.V.; Kireyev, S.M.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentsevah, S.A.; Mirnov, I.N.; Ejikbosverpdze, Sh.M.; Ostrinsky, A.V.; Petukhov, V.V.; Pikhulya, O.E.; Pshukov, A.M.; Revzin, N.Ye.; Shikhin, A.A.; Shilo, Yu.I.; Slyusareva, Ye.D.; Strepanyuk, M.V.; Tikhonov, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Yants, V.E.; Zakhorov, Yu.I.; Zatsepin, G.T.; Cleveland, B.C.; Bowles, T.J.; Elliott, S.R.; O'Brien, H.A.; Wark, D.L.; Wilkerson, J.F.; Cherry, M.L.; Kouzes, R.T.

1988-01-01

230

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

231

Quantum magnetoelectric effect in iron garnet  

NASA Astrophysics Data System (ADS)

The magnetoelectric response and its quantum relaxation phenomenon have been investigated for a single crystal of yttrium iron garnet. The electric-dipole moments, built in by excess localized electrons forming Fe2+ sites, never freeze even at the lowest temperature and relax through a quantum tunneling process. Application of magnetic field enhances the dielectric relaxation strength and gives rise to a large magnetocapacitance effect ( ˜13% at 10 K with 0.5 T). We show that this magnetically tunable quantum paraelectricity is associated with the Fe2+ -based magnetoelectric centers in which the electric polarization depends on the magnetization vector via the spin-orbit coupling.

Yamasaki, Yuichi; Kohara, Yuki; Tokura, Yoshinori

2009-10-01

232

Very high-pressure orogenic garnet peridotites.  

PubMed

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

2007-05-29

233

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.

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

2007-01-01

234

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

235

System for Bulk Growth of Gallium Nitride. Vapor Phase Epitaxy of Gallium Nitride by Gallium Arc Evaporation.  

National Technical Information Service (NTIS)

A vapor phase growth system intended for the growth of bulk gallium nitride crystals was investigated. Potential advantages of the growth technique are cheap source materials of high purity, no corrosive gasses, and low operating and equipment costs. Ga c...

S. J. Heikman U. K. Mishra

2005-01-01

236

Gallium-67 activity in bronchoalveolar lavage fluid in sarcoidosis  

SciTech Connect

Roentgenograms and gallium-67 scans and gallium-67 counts of BAL fluid samples, together with differential cell counts, have proved to be useful in assessing activity and lung involvement in sarcoidosis. In active pulmonary sarcoidosis gallium-67 scans are usually positive. Quantitation of gallium-67 uptake in lung scans, however, may be difficult. Because gallium-67 uptake and cell counts in BAL fluid may be correlated, we set out to investigate gallium-67 activity in BAL fluid recovered from patient of different groups. Sixteen patients with recently diagnosed and untreated sarcoidosis, nine patients with healthy lungs, and five patients with CFA were studied. Gallium-67 uptake of the lung, gallium-67 activity in the lavage fluid, SACE and LACE levels, and alpha 1-AT activity were measured. Significantly more gallium-67 activity was found in BAL fluid from sarcoidosis patients than in that from CFA patients (alpha = .001) or patients with healthy lungs (alpha = .001). Gallium-67 activity in BAL fluid could be well correlated with the number of lymphocytes in BAL fluid, but poorly with the number of macrophages. Subjects with increased levels of SACE or serum alpha 1-AT showed higher lavage gallium-67 activity than did normals, but no correlation could be established. High gallium-67 activity in lavage fluid may be correlated with acute sarcoidosis or physiological deterioration; low activity denotes change for the better. The results show that gallium-67 counts in BAL fluid reflects the intensity of gallium-67 uptake and thus of activity of pulmonary sarcoidosis.

Trauth, H.A.; Heimes, K.; Schubotz, R.; von Wichert, P.

1986-01-01

237

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

238

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

239

Trace element zoning in pelitic garnet of the Black Hills, South Dakota  

Microsoft Academic Search

Trace element (REE, Cr, Ti, Y, Y, and Zr) analysis of garnet from the garnet, staurolite, and lower sillimanite zones of an aluminous schist of the Black Hills, South Dakota, indicates that REE zoning varies as a function of grade. Garnet-zone garnet has high concentrations of REEs, Cr, Ti, Y, Y, and Zr in the cores and low concentrations in

CRAIG S. SCHWANDT; JAMES J. PAPIKE

1996-01-01

240

Development of Gallium Arsenide for Infrared Windows.  

National Technical Information Service (NTIS)

This report describes methods for preparing high quality infrared transmitting gallium arsenide. The work is broadly divided into categories describing doping studies, vertical pulling techniques, liquid encapsulation, growth methods, horizontal Bridgman ...

H. C. Hafner G. R. Cronin

1975-01-01

241

LPE Garnet Films Without Hard Bubbles  

Microsoft Academic Search

In previous studies of hard bubbles, these anomalous domains were found to exist in all unimplanted single-layer LPE garnet films at room temperature. We have prepared five garnet film compositions in which it is not possible to generate hard bubbles at room temperature. These compositions are Y0.9Gd1.2Tm0.9Fe4.6Al0.1Ga0.3O12, Y0.9Gd1.5Yb0.6Fe4.5Al0.5O12, Y1.0Gd1.0Er1.0Fe4.5Al0.lGa0.4O12, Y1.5Eu0.75Gd0.75Fe4.4Al0.5Ga0.1O12 and Y2.0Tm1.0Fe4.1Ga0.9O12. All these films were prepared by standard LPE

A. B. Smith; M. Kestigian; W. R. Bekebrede

1974-01-01

242

Substitution of gadolinium ethylenediaminetetraacetate with phosphites: towards gadolinium deposit in nephrogenic systemic fibrosis.  

PubMed

In neutral media, reactions of gadolinium ethylenediaminetetraacetates with phosphorous acid result in the formation of the mixed-ligand polymeric complex K3n[Gd(EDTA)(HPO3)]n·7nH2O () and dimeric complex Na6[Gd2(EDTA)2(HPO3)2]·2.5NaCl·21H2O () (H4EDTA = ethylenediaminetetraacetic acid) in warm solution. Further substitution with citric acid gives the monomeric gadolinium citrate with EDTA (NH4)2Na[Gd(EDTA)(H2cit)]·4H2O (). The compounds were characterized by elemental analysis, single crystal X-ray diffraction, FT-IR, ESI-MS and thermogravimetric analysis. Structural analysis indicates that three coordinated water molecules in the gadolinium ethylenediaminetetraacetate trihydrates are replaced by phosphite ions (HPO3(2-)) in the compounds and . Gadolinium atoms are octa-coordinated by EDTA and the phosphite ion, the latter links adjacent Gd-EDTA units to generate an infinite one-dimensional chain in compound and a dimeric octatomic ring in . In complex , coordinated water molecules were substituted by the ?-hydroxy, ?-carboxy and ?-carboxy groups of citrate. Citrate is favourable for inhibiting the formation of Gd-EDTA phosphite. All the complexes are very easily soluble in water. The solution behavior of the isostructural lanthanum complexes was probed with (13)C and (31)P NMR spectra in D2O for comparison. ESI-MS analysis and recrystallization proved that complexes and dissociate to the monomeric unit of Gd-EDTA and free HPO3(2-) in aqueous solution. Substitutions of gadolinium ethylenediaminetetraacetates to and are attributed to be the cause of nephrogenic systemic fibrosis in some way. PMID:24132302

Gao, Song; Chen, Mao-Long; Zhou, Zhao-Hui

2014-01-14

243

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

244

Determination of the Universality Class of Gadolinium  

SciTech Connect

We resolve a long-standing puzzle for the static and dynamic critical behavior of gadolinium by a combined theoretical and experimental investigation. It is shown that the spin dynamics of a ferromagnet with hcp lattice structure and a spin-spin interaction given by both exchange and dipole-dipole interaction belongs to a new dynamic universality class, model J{sup {asterisk}} . Comparing results from mode coupling theory with results from three different hyperfine interaction probes we find quantitative agreement. {copyright} {ital 1997} {ital The American Physical Society}

Frey, E.; Schwabl, F.; Henneberger, S. [Institut fuer Theoretische Physik, Technische Universitaet Muenchen, D-85747 Garching (Germany)] [Institut fuer Theoretische Physik, Technische Universitaet Muenchen, D-85747 Garching (Germany); Henneberger, S.; Kratzer, A.; Kalvius, G.M. [Institut fuer Kernphysik and Nukleare Festkoerperphysik, Technische Universitaet Muenchen, D-85747 Garching (Germany)] [Institut fuer Kernphysik and Nukleare Festkoerperphysik, Technische Universitaet Muenchen, D-85747 Garching (Germany); Hartmann, O.; Waeppling, R. [Institute of Physics, Uppsala Universitet, S-75121 Uppsala (Sweden)] [Institute of Physics, Uppsala Universitet, S-75121 Uppsala (Sweden)

1997-12-01

245

Development of gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

The potential of ion implantation as a means of developing gallium arsenide solar cells with high efficiency performance was investigated. Computer calculations on gallium arsenide cell characteristics are presented to show the effects of surface recombination, junction space-charge recombination, and built-in fields produced by nonuniform doping of the surface region. The fabrication technology is summarized. Electrical and optical measurements on samples of solar cells are included.

1973-01-01

246

GALLIUM ARSENATE REMOVAL FROM WASTE WATERS  

Microsoft Academic Search

The aim of this paper is to study the loss of gallium (Ga) and arsenic (As) loss during the sedimentation of gallium arsenate (GaAsO4) from waste solutions of GaAs epitaxial production by chloride method. The solid wastes of this semiconductor manufacturing process are removed from technological equipment by dissolution in an acidic etching solution. In order to recover valuable Ga

S. Baranov; B. Cinic; J. Redwing; V. Stavila

2005-01-01

247

Thyroid uptake of gallium in Graves' disease.  

PubMed

A patient with hyperthyroid Graves' disease presented with ptosis, leading to a workup for myasthenia gravis. An enlarged thymus gland was noted on computed tomography. A scan with gallium-67 citrate showed prominent and diffuse thyroid gland activity as well as prominent lacrimal activity. This finding of thyroid uptake of gallium led to the correct diagnosis of Graves' disease. Such a finding has not been reported previously. The associated thymic, thyroid, and orbital findings in Graves' disease are discussed. PMID:3180616

Allard, J C; Lee, V W; Franklin, P

1988-09-01

248

Let there be light [gallium nitride LED  

Microsoft Academic Search

The incandescent light bulb rolled back the night around the start of the 20th century. The gallium nitride LED will light the way in the 21st. The development of the gallium nitride (GaN) LED, made it possible to get white light from a semiconductor. GaN LEDs are already quietly transforming specialized illumination, including architectural and stage lighting, indoor and outdoor

G. Zorpette

2002-01-01

249

Gallium poisoning: a rare case report.  

PubMed

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, vertigo, and unexpected black-outs. Had there been effective emergency medical care protocols, diagnostic testing, treatment and antidotes, the latent manifestations of irreversible cardiomyopathy may have been prevented. Given how quickly exposure led to morbidity, this article aims to raise an awareness of the toxic potential of gallium. This has particular relevance for workers involved in the production of semiconductors where there is a potential for accidental exposure to gallium by-products during device processing. It may also have implications for dentists who use gallium alloys to replace mercury containing amalgam. In the absence of threshold limit values and exposure limits for humans, as well as emergency medical guidelines for treatment of poisoning, the case calls on the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration to establish guidelines and medical management protocols specific for gallium. PMID:22024274

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

2012-02-01

250

Gallium nitride and related materials  

SciTech Connect

The first International Symposium on Gallium Nitride and related materials was held on November 27--December 1, 1995, in Boston, Massachusetts, US. The symposium reflected the large amount of work that has taken place since the field exploded about two years ago with the announcement of commercial blue light emitting devices. The topics covered crystal growth, molecular beam growth techniques, chemical vapor deposition, alloys and novel growth techniques, structural properties, electronic properties, optical properties, point defects, hydrogen, etching and other material processes, surfaces and metal contacts, and devices. These proceedings represent the current state of understanding in the field, reflecting about 75 percent of the work presented at the symposium. One hundred and twenty eight papers have been processed separately for inclusion on the data base.

Ponce, F.A. [ed.] [Xerox Palo Alto Research Center, CA (United States); Dupuis, R.D. [ed.] [Univ. of Texas, Austin, TX (United States); Nakamura, S. [ed.] [Nichia Chemical Industries, Tokushima (Japan); Edmond, J.A. [ed.] [Cree Research, Inc., Durham, NC (United States)

1996-11-01

251

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

252

Geothermobarometric history of subduction recorded by quartz inclusions in garnet  

NASA Astrophysics Data System (ADS)

Burial histories of subduction zone rocks are often difficult to accurately constrain, owing to a lack of robust mineral geobarometers applicable to high pressure mineral assemblages. Knowledge of the depth-histories of subduction is, however, required for our understanding of global geochemical cycles, subduction-related seismicity, and the evolution of destructive tectonic boundaries. The high spatial resolution of quartz inclusion geobarometry can be used to determine pressure evolution during metamorphic growth of individual garnet crystals. Quartz inclusions in garnet from Sifnos, Greece, preserve such a record of the pressure of garnet growth, allowing detailed reconstruction of the metamorphic evolution of these rocks. Pressure-dependent Raman spectra of quartz inclusions were combined with elastic modeling to infer the conditions at which they were trapped during garnet growth. All measured inclusions suggest that garnet growth occurred between 19 and 20.5 kbars, with little evidence for significant pressure variation during the garnet growth interval, which is interpreted to record ˜100°C of heating. Coupled with thermometry and geochronology, these results show that early, cold burial was followed by a phase of rapid heating, which immediately preceded exhumation. Garnet growth occurred primarily during this heating phase.

Ashley, Kyle T.; Caddick, Mark J.; Steele-MacInnis, Matthew J.; Bodnar, Robert J.; Dragovic, Besim

2014-02-01

253

Low stress deformation of garnet by incongruent dissolution precipitation creep  

NASA Astrophysics Data System (ADS)

Microstructures indicating incongruent dissolution precipitation creep of garnet in eclogite-facies graphitic micaschist (Tauern window, Eastern Alps) are investigated. Garnet dissolution is observed where garnet poikiloblasts grown at eclogite facies metamorphism approached each other as a consequence of progressive deformation during exhumation, with estimated P-T-conditions between 570 °C, 1.7 GPa and 470 °C, 0.9 GPa. The poikiloblasts are separated by a dissolution seam and flanked by strain shadows filled with quartz, white mica, and chlorite; there is no evidence for crystal plastic deformation of garnet. Two cases are investigated: (A) stylolitic contact zone, (B) smooth contact zone. In both cases, internal fabrics of the poikiloblasts and concentric chemical zoning are truncated. Material previously forming inclusions in the garnet poikiloblasts is now passively enriched in a dissolution seam, the original microstructure of fine-grained mica-graphite aggregates remaining preserved. Though microstructures suggest that garnet dissolution was driven by local stress concentration, the level of differential stress remained too low for plastic deformation of the fine-grained white mica-graphite aggregates set free from the stress supporting garnet. Incongruent dissolution precipitation creep appears to be a particularly effective deformation mechanism at low stress in a subduction channel.

Wassmann, Sara; Stöckhert, Bernhard

2013-01-01

254

Gallium Nitride Growth Using Diethylgallium Chloride as an Alternative Gallium Source.  

National Technical Information Service (NTIS)

Metal organic vapor phase epitaxy (MOVPE) of GaN has been carried out using diethyl gallium chloride (DEGaCl) and ammonia. The growth rate and efficiency of the DEGaCl-based growth decreases with increasing temperature when compared to trimethyl gallium (...

L. Zhang R. Zhang M. P. Bolelawski T. F. Kuech

1999-01-01

255

Modeling of zoning patterns in garnet: Thermodynamic and kinetic aspects  

NASA Astrophysics Data System (ADS)

Results from the modeling of compositional zoning patterns in garnet porphyroblasts from the medium-grade metapelitic schist of northern Ladoga area are considered. The P-T pseudosections in the model KMnFMASH system were calculated for this purpose using THERMOCALC software (Powell et al., 1998). Particular emphasis is placed upon the effect of garnet growth kinetics on the model zoning profiles for Mn (Gulbin, 2013). They fit the observed profiles if intergranular diffusion-controlled growth is assumed for porphyroblasts. Additionally, a model of metamorphic fractional crystallization is used to characterize the oscillations in both the garnet core and rim. Starting from the assumption that a reservoir, where garnet grows, consists of chlorite, and that this mineral is intensely replaced with biotite and staurolite at the onset of crystallization, a partial release of Mn from the chlorite structure and the concentration of this component in intergranular space is inferred. In terms of the model under consideration, the coefficient of the Mn partition between garnet and reservoir temporarily increases at the early stage of garnet growth, giving rise to the enrichment of the intermediate zone of porphyroblasts in Mn. In addition to the modeling of garnet growth zoning, its subsequent diffusion modification is estimated on the basis of intracrystalline diffusion profile simulation. The reverse zoned, Mn-rich and Mg-poor garnet rims are related to retrograde growth of garnet at the late stage of porphyroblast formation. The data obtained are used to constrain metamorphic evolution and the P-T-t path of staurolite-bearing rocks in the northern domain of the studied area.

Gulbin, Yu. L.

2013-12-01

256

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

257

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

258

Garnet: featured mineral group at the 1993 Tucson Show  

USGS Publications Warehouse

The garnets are a common but complex group of minerals. They are perhaps the mineral kingdom's best example of solid solution: a relationship in which minerals have chemical compositions that are intermediate between two or more ideal end-member species. In garnet, we deal with a complex group of solid-solution series between as many as 14 end-member minerals. The varying intergradations of solid solution between these different end-members help to explain the garnet group's variety of color, environment of occurrence, gem use, and variation in such physical properties as specific gravity, refractive index, and hardness. -from Author

Modreski, P. J.

1993-01-01

259

Broad-band emission from chromium doped germanium garnets  

Microsoft Academic Search

By varying the composition of a series of germanium garnets, it is possible to change the lattice constant of the structure over a wide range, and thus the crystal field. Three Cr-doped germanium garnets (Ca3Al2Ge3O12, CaY2Mg2Ge3O12, and MgY2Mg2Ge3O12) have been grown as single crystals. Spectroscopic results show that in these garnets the broadband emission at room temperature is so strong

H. P. Christensen; H. P. Jenssen

1982-01-01

260

Trace element zoning in garnet from the Kwoiek Area, British Columbia: disequilibrium partitioning during garnet growth?  

Microsoft Academic Search

Trace element zoning in garnets from two contact-metamorphosed rocks from the Kwoiek area, British Columbia (Hollister 1969a), was measured with an ion microprobe. Zoning profiles have three distinct parts with chemical breaks defined by co-variation of major and trace elements. Important features of the trace element zoning profiles are: (1) roughly ‘bell-shaped’ zoning profiles for Y and the HREEs, (2)

Donald D. Hickmott; Nobu Shimizu

1990-01-01

261

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

262

Multiple garnet growth in garnet-kyanite-staurolite gneiss, Pangong metamorphic complex, Ladakh Himalaya: New constraints on tectonic setting  

NASA Astrophysics Data System (ADS)

Garnet-kyanite-staurolite gneiss in the Pangong complex, Ladakh Himalaya, contains porphyroblastic euhedral garnets, blades of kyanite and resorbed staurolite surrounded by a fine-grained muscovite-biotite matrix associated with a leucogranite layer. Sillimanite is absent. The gneiss contains two generations of garnet in cores and rims that represent two stages of metamorphism. Garnet cores are extremely rich in Mn (X Sps = 0.35-0.38) and poor in Fe (X Alm = 0.40-0.45), whereas rims are relatively Mn-poor (X Sps = 0.07-0.08), and rich in Fe (X Alm = 0.75-0.77). We suggest that garnet cores formed during prograde metamorphism in a subduction zone followed by abrupt exhumation, during early collision of the Ladakh arc and Karakoram block. The subsequent India-Asia continental collision subducted the metamorphic rocks to a mid-crustal level, where the garnet rims overgrew the Mn-rich cores at ca. 680 °C and ca. 8.5 kbar. PT calculations were estimated from phase diagrams calculated using a calculated bulk chemical composition in the Mn-NCKFMASHT system for the garnet-kyanite-staurolite-bearing assemblage. Muscovites from the metamorphic rocks and associated leucogranites have consistent K-Ar ages ( ca. 10 Ma), closely related to activation of the Karakoram fault in the Pangong metamorphic complex. These ages indicate the contemporaneity of the exhumation of the metamorphic rocks and the cooling of the leucogranites.

Thanh, N. X.; Sajeev, K.; Itaya, T.; Windley, B. F.

2011-12-01

263

Structural features of solid gallium in microporous glass  

Microsoft Academic Search

An experimental Debye-Scherrer study of structural features of gallium in porous glass with pore diameter d=4 nm is reported. Gallium structures different from the known bulk modifications have been discovered.

I. G. Sorina; E. V. Charnaya; L. A. Smirnov; Yu. A. Kumzerov; C. Tien

1998-01-01

264

Optical microcharacterization of gallium nitride and indium gallium nitride alloys  

NASA Astrophysics Data System (ADS)

Gallium Nitride (GaN) and its alloys are attractive candidate materials for light-emitting applications in the visible and ultraviolet regions of the electromagnetic spectrum. The wide direct bandgap of the III-nitrides makes them very efficient light-emitters and their short bond length makes them extremely robust and durable. During the last decade, there have been rapid strides in the development of these materials and several devices based on them have already been commercialized. However, there are many issues with these materials that remain to be solved. This dissertation focuses on two main issues: one, the properties of Indium Gallium Nitride (InGaN) and two, the effect of dislocations on material properties. InGaN alloys are very difficult to grow, and a principal effort in the research community today is to achieve growth of high-quality films with high indium compositions. In order to overcome the problems associated with the growth of InGaN, it is important to gain an understanding of the basic nature of the material. In this work, the microstructure and electronic properties of thick InGaN epilayers has been studied. This enables investigation of material properties free of quantum confinement effects. The electronic properties of InGaN were observed to strongly vary with indium composition. Dislocations in the underlying GaN layer act as nucleation sites for phase separation and have a significant effect on material properties. The dislocation density was also found to play an important role in determining the strain relaxation mechanism in InGaN epilayers. The effect of dislocations on materials properties is an interesting problem that is being studied in great detail. In this study, it was found that the electronic properties in epitaxial lateral overgrowth of GaN are strongly dependent on the growth direction and unrelated to dislocation density. The properties appeared to be determined by point defects whose incorporation depends on the growth surface. Luminescence characteristics were studied across threading dislocations in semi-insulating GaN and were found to be closely related to the electrostatic potential measured by electron holography. This work has investigated important materials issues in GaN and InGaN and has contributed in developing a basic understanding of these materials.

Srinivasan, Sridhar

265

Comparative compressibilities of majorite-type garnets  

Microsoft Academic Search

Relative compressibilities of five silicate garnets were determined by single-crystal x-ray diffraction on crystals grouped in the same high-pressure mount. The specimens include a natural pyrope [(Mg2.84Fe0.10Ca0,06) Al2Si3O12], and four synthetic specimens with octahedrally-coordinated silicon: majorite [Mg3(MgSi)Si3O12], calcium-bearing majorite [(Ca0.49Mg2.51)(MgSi)Si3012], sodium majorite [(Na1.88Mgp0.12)(Mg0.06Si1.94)Si3O12], and an intermediate composition [(Na0.37Mg2.48)(Mg0.13Al1.07 Si080) Si3O12]. Small differences in the compressibilities of these crystals are revealed

R. M. HazenI; R. T. Downs; P. G. Conrad; L. W. Finger; T. Gasparik

1994-01-01

266

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

267

Microwave solitons in magnetic garnet films (invited)  

SciTech Connect

This work concerns some recent results on the excitation of solitons at microwave frequencies in planar magnetic films. In particular, yttrium iron garnet (YIG) possesses the intrinsic properties of dispersion and nonlinearity required for a system to support such a kind of waves. In this framework, experimental results on a novel nonlinear effect, related to the propagation at about 7 GHz of magnetostatic volume waves in YIG films having thicknesses ranging between a few microns to more than 100 ..mu..m, have been interpreted in terms of a solitonic excitation process. By starting from those findings, this paper presents an analysis of the experimental aspects as a function of the various parameters involved (i.e., thickness, frequency, wave vector, and so on) together with a concise discussion with respect to the presently available theoretical approaches.

De Gasperis, P.; Marcelli, R.; Miccoli, G.

1988-04-15

268

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

269

Optical transitions in Mn3+-doped garnets  

NASA Astrophysics Data System (ADS)

The optical spectra of Mn3+-doped garnet crystals reveal a large Jahn-Teller stabilization energy of about 1900 cm-1 for the 5E ground state, and smaller Jahn-Teller stabilization energies for the excited states, i.e., ~325 cm-1 for the 5T2, and ~180 cm-1 for the 1T2 level. The absorption spectra are dominated by the spin-allowed 5E-->5T2 transition. At low temperatures, the emission occurs from the 1T2 level to the Jahn-Teller-split ground state and the 3T1 intermediate level. With increasing temperature the 5T2 level becomes thermally populated and the emission spectrum is dominated by the spin-allowed 5T2-->5E transition. The emission lifetime is nearly independent of the detection wavelength, but strongly dependent of the temperature and the host lattice. At 12 K the lifetime is ~6 ms for all crystals, while at room temperature it is between 1.1 ms for Mn3+:Y3Al5O12 and <0.5 ?s for Mn3+:Gd3Sc2Ga3O12. The radiative lifetimes of the 1T2 and 5T2 levels were determined to be about 6 ms and 16 ?s, respectively. Both the radiative and the nonradiative rate are temperature dependent due to the coupling of odd-parity and totally-symmetric phonons, and the thermalization of the 5T2 level. The nonradiative decay is more pronounced for lower crystal-field strengths, because of the smaller 5T2-3T1 energy gap and the higher population of the 5T2 level. Excited-state absorption transitions arising from the energetically lower 1T2 in higher lying singlet levels cover the entire spectral range of the emission; therefore laser oscillation at room temperature is unlikely in Mn3+-doped garnets.

Kück, S.; Hartung, S.; Hurling, S.; Petermann, K.; Huber, G.

1998-01-01

270

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

271

Symplectites in garnet megacrysts captured by alkali mafic magma  

NASA Astrophysics Data System (ADS)

Megacrysts are widespread in Cenozoic alkali-basalts of many volcanic provinces of the world. Garnet megacrysts containing symplectites are the most interesting, as can be used for reconstruction of physical and chemical conditions in liquid basalt at the moment of garnet crystal capture. The collection of garnet megacrysts and garnet-pyroxene aggregates from Shavaryn-Tsaram (Hangaj plateau, Mongolia) and Bartoj (Dzhida basaltic field, Russia) paleovolcanoes has studied. Cenozoic alkali basaltic volcanism of these two spatially separated areas is considered to be related to a uniform process of lithosphere spreading in Baikal and related Central Asian rift systems. The studying of garnet-pyroxene aggregate and fragments of garnet megacrysts from these two paleovolcanoes revealed two mineral associations: primary and secondary. The former includes garnet and clinopyroxene, the letter (symplectite) is presented by products of garnet disintegration (clinopyroxene remain unaltered). At least two paragenesis can be allocated: 1) shpinel - plagioclase-olivine sometimes with gedrite and orthopyroxene; 2) olivine (with glass). Experimental modeling of decomposition process in garnet megacryst has been carried out with the help of 'Selector' softwear at various P-T parameters. Physical and chemical conditions of this paragenesis occurrence have also been estimated by up-to-date geothermometers and geobarometers (T 950-1000 C, P 4-4.5 kbar. Conclusions: 1. Garnet megacrysts are apparently in non-equilibrium with alkali-basalts. They were formed in conditions corresponding to zones of mantle plums at the bottom of crust, in magmatic chambers at constant infiltration of fluid. Subsequently megacrysts were captured by alkali-basalt magma and taken out to the surface. 2. Kelyphitic rims on garnet megacrysts is a result of partial melting of megacrysts on interaction with the hosting alkali basaltic rock. During melting garnet transforms with the formation of Na-K glass and Mg olivine. Presence of alkaline volcanic glass in the kelyphitic rim testifies that Na and K migrate from alkali-basalt melt. 3. Subisothermal decompression inside garnet crystal yields solid-phase decomposition to form symplectite. Paragenesis of the formed minerals depends on garnet composition, P-T conditions and water presence/absence: 1) at pressure over 10 kbar and temperature more than 1300 C, garnet steadily co-exists with clinopyroxene; 2) at pressure and temperatures decreasing (4-8 kbar, 900-1300 C),garnet decomposes as follows: Sp+Pl+Ol sometimes with Opx, in the presence of water - Sp+Pl+Ol with Opx and Amph; 3) at temperature 950-1000 C and pressure 4-4.5 kbar, the following association is formed Sp+Opx+Pl; 4) if temperatures makes up 700-800 C, at the same pressure P=4 kbar, Sp+Opx+Cpx paragenesis is formed.

Aseeva, Anna; Vysotskiy, Sergey; Karabtsov, Alexander; Alexandrov, Igor; Chashchin, Alexander

2014-05-01

272

A novel technique for microstructure characterization of garnet films  

Microsoft Academic Search

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

P. C. Wo; P. R. Munroe; Mikhail Vasiliev; Zonghan Xie; Kamal Alameh; V. A. Kotov

2009-01-01

273

Spectroscopic Analysis of Rock Mineral-Garnet of South Kerala  

Microsoft Academic Search

Spectroscopic techniques serve an important tool in the characteization of minerals. Garnet samples taken from the rocks of Vattapara, Kovalam, Mukkunnimala have been used. Spectral analysis of purified and dried garnet is carried out using FT-IR, FT-Raman, X-ray diffraction, X-ray Fluorescence techniques. Different d spacing values obtained from the XRD pattern fairly matches standard d spacing values of almandine. It

S. Vidya; S. L. Varun; T. Vijayakumar; I. Hubert Joe; V. S. Jayakumar

2008-01-01

274

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

275

Low-Lying Spectrum of Rare-Earth Iron Garnets  

Microsoft Academic Search

The spin-wave spectra of simplified two- and three-sublattice models of the rare-earth iron garnets are obtained, and shown to contain an iron spin-wave spectrum similar to that in ytrrium iron garnet, together with one and two optical branches, respectively. Intensities for optical excitation of k=0 spin waves are computed, and the effect of an external magnetic field on the resonant

M. Tinkham

1961-01-01

276

Optical properties of epitaxial iron garnet thin films  

Microsoft Academic Search

Optical absorption, derivative absorption, reflectivity, and derivative reflectivity data are presented for several iron garnet thin-film compositions grown by liquid-phase epitaxy. In the case of yttrium iron garnet (YIG), the real and imaginary parts of the dielectric response function ?=?1+i?2 are compared with previously published results for bulk crystals and shown to be substantially larger. Based on absorption and reflectivity

S. H. Wemple; S. L. Blank; J. A. Seman; W. A. Biolsi

1974-01-01

277

Epitaxial Bi-content ferrite-garnet film memory (abstract)  

Microsoft Academic Search

Memory conception in epitaxial ferrite-garnet films on a compensation wall has been developed in recent work.1 Further original solutions for memory element formation by heat treatment under Si layers have been found but this method has not been used in practice due to the difficulty of reproducing results. In this work the possibility of a memory matrix on the ferrite-garnet

E. I. Il’yashenko; V. P. Klin; A. D. Nickolsky; A. G. Solovjov

1994-01-01

278

Localized control of magnetization in LPE bubble garnet films  

Microsoft Academic Search

A new method of obtaining fine scale localized control of the magnetization,4piM, for defining bubble tracks in LPE garnet films is described. It involves the deposition of a thin film of silicon on the garnet surface and then annealing in oxygen, or inert gas, at moderate elevated temperatures. Under the silicon,4piMdecreases by large amounts upon annealing. These reductions in4piM, together

R. C. LE CRAW; P. A. BYRNES; W. A. JOHNSON; H. J. LEVINSTEIN; J. W. NIELSEN; R. K. SPIWAM; R. Wolfe

1973-01-01

279

Thickness dependence of coercivity in LPE garnet films  

Microsoft Academic Search

We have observed that thicker than normal LPE bubble garnet films (14–17 ?m) have lower coercivity than those of normal thickness (3–5 ?m). We have investigated this thickness dependence of 4 film compositions in the SmCaGe garnet system. In thin films, coercivity is dominated by a high coercivity region near the substrate. As the film thickness increases, the coercivity decreases

E. B. Moore; B. A. Calhoun; K. Lee

1978-01-01

280

Thickness dependence of coercivity in LPE garnet films  

Microsoft Academic Search

We have observed that thicker than normal LPE bubble garnet films (14-17 mum) have lower coercivity than those of normal thickness (3-5 mum). We have investigated this thickness dependence of 4 film compositions in the SmCaGe garnet system. In thin films, coercivity is dominated by a high coercivity region near the substrate. As the film thickness increases, the coercivity decreases

E. B. Moore; B. A. Calhoun; K. Lee

1978-01-01

281

Gallium Zeolites for Light Paraffin Aromatization  

SciTech Connect

The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.

Price, G.L.; Dooley, K.M.

1999-02-10

282

Production of gallium atoms by excimer laser photolysis of trimethyl gallium  

SciTech Connect

The gas phase kinetics of group III elements such as gallium are important in possible chemically driven energy transfer lasers and in chemical vapor deposition processes in the electronics industry. Excimer laser photodissociation of volatile gallium compounds via multiple photon process provides, in principle, a convenient room temperature source of gallium atoms for study using laser photolysis-laser induced fluorescence techniques. In this paper, we report preliminary results of the multiple photon dissociation of trimethyl gallium at 193 nm. Prompt emission from a number of excited gallium states (5 /sup 2/S, 4 /sup 2/D, 6 /sup 2/S, 6 /sup 2/P/sup 0/, 5 /sup 2/D, and 4 /sup 4/P) has been observed. The time histories of the ground state (4/sup 2/P/sup 0//sub 1/2/) and the metastable (4 /sup 2/P/sup 0//sub 3/2/) have been measured using laser induced fluorescence. The resulting time profiles are complicated even in the absence of a reactant gas by the apparent production of ground state gallium at relatively long times (approx. 10 ..mu..s) after the excimer laser pulse. Possible mechanisms for this (i.e., radical reactions to produce gallium, energy transfer cascading from high lying metastable states, ionic processes, etc.) are being investigated. These results indicate that the photodissociation of trimethyl gallium at 193 nm is complex. Photolysis studies at other wavelengths and with other precursors are in progress to find a cleaner source of gas phase atomic gallium for kinetic studies. 20 refs., 7 figs.

Baughcum, S.L.; Oldenborg, R.C.; Winn, K.R.; Hof, D.E.

1985-03-01

283

Nephrogenic systemic fibrosis: histology and gadolinium detection.  

PubMed

The association between gadolinium (Gd)-containing MR imaging contrast agents and the development of nephrogenic systemic fibrosis (NSF) is well recognized. The authors review the histopathologic features, methodology, and results of analysis of tissues for Gd in NSF. Scanning electron microscopy/energy dispersive x ray spectroscopy (SEM/EDS) provides sensitive detection of individual Gd-containing deposits in situ. Secondary ion mass spectroscopy has far greater sensitivity for detection of Gd than SEM/EDS and allows correlation at the cellular level. Inductively coupled plasma mass spectrometry is the recognized method for full quantitative analysis of Gd in tissues but requires destruction of the tissue and does not allow spatial correlation. In practice, the different analytic techniques provide complementary data and can be selected based on the information required. PMID:19744599

Thakral, Charu; Abraham, Jerrold L

2009-09-01

284

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

285

Single gallium nitride nanowire lasers  

NASA Astrophysics Data System (ADS)

There is much current interest in the optical properties of semiconductor nanowires, because the cylindrical geometry and strong two-dimensional confinement of electrons, holes and photons make them particularly attractive as potential building blocks for nanoscale electronics and optoelectronic devices, including lasersand nonlinear optical frequency converters. Gallium nitride (GaN) is a wide-bandgap semiconductor of much practical interest, because it is widely used in electrically pumped ultraviolet-blue light-emitting diodes, lasers and photodetectors. Recent progress in microfabrication techniques has allowed stimulated emission to be observed from a variety of GaN microstructures and films. Here we report the observation of ultraviolet-blue laser action in single monocrystalline GaN nanowires, using both near-field and far-field optical microscopy to characterize the waveguide mode structure and spectral properties of the radiation at room temperature. The optical microscope images reveal radiation patterns that correlate with axial Fabry-Perot modes (Q ~ 103) observed in the laser spectrum, which result from the cylindrical cavity geometry of the monocrystalline nanowires. A redshift that is strongly dependent on pump power (45 meV ?J cm-2) supports the idea that the electron-hole plasma mechanism is primarily responsible for the gain at room temperature. This study is a considerable advance towards the realization of electron-injected, nanowire-based ultraviolet-blue coherent light sources.

Johnson, Justin C.; Choi, Heon-Jin; Knutsen, Kelly P.; Schaller, Richard D.; Yang, Peidong; Saykally, Richard J.

2002-10-01

286

Chrome doped gallium arsenide evaluation  

SciTech Connect

We received, for free, two sets of Chrome doped Gallium Arsenide (GaAs:Cr) wafers, one from Cominco Electronic Materials, Inc., and the other from Furakawa Electric Co., for the purpose of evaluation as potential material for high speed photoconductive detectors. In return for the free material we promised to give the two manufacturers feed back on our evaluation of these wafers. The primary purpose of this report is to present the results of our evaluation of these wafers and conclusions regarding the usefulness of heavily doped GaAs:Cr for photoconductive detectors. We have found that response times of less than 100 ps (FWHM) are possible with GaAs:Cr detectors, but that there are several time constants to the decay which result in very long ''tails'' to the impulse response of these detectors. These long tails are unacceptable for most detector applications, but there may be some special cases where GaAs:Cr could be used. 5 figs., 1 tab.

Pocha, M.D.; Morse, J.D.; Brazes, W.F.

1987-10-10

287

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

288

New SMU Gallium Fixed-Point Cells  

NASA Astrophysics Data System (ADS)

In the framework of the European research project EURAMET 732, the Slovak Institute of Metrology (SMU) built three primary gallium fixed-point cells of different designs. The cells are designed for the calibration of the long-stem SPRT. In regard to the procedure commonly used at SMU when realizing the gallium point, the cells are designed for use in a stirred liquid bath. This article provides information about the cell designs, materials used, method of filling, and results of the performed experiments. The experiments were focused on the study of the cells' metrological characteristics, some effects that could influence the melting-point temperature and the effect of the melted metal fraction on the immersion profile. New cells were compared with the SMU reference gallium cell.

Ranostaj, Juraj; ?uriš, Stanislav; Knorová, Renáta; Kaskötö, Mariana; Vysko?ilová, Irena

2011-08-01

289

/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

290

Magneto-phonon contribution into the Young's modulus of gadolinium  

Microsoft Academic Search

:   Theoretical and experimental investigation has been made of the magnetic contribution to the Young's modulus of rare earth\\u000a ferromagnet gadolinium. Experimental study includes measurements of the Young's modulus as a function of temperature, magnetic\\u000a field and magnetization of gadolinium. Theoretical analysis is based on the account of phonon anharmonicity which gives rise\\u000a to the dependence of Debye temperature on

V. Yu. Bodriakov; A. A. Povzner; S. A. Nikitin

1998-01-01

291

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

292

Experimental results on a low-temperature magnetic refrigerator  

Microsoft Academic Search

A Carnot-cycle magnetic refrigerator has been designed, built, and tested in the temperature range of approx. 4 K to approx. 15 K. Gadolinium gallium garnet in the rim of a wheel is the refrigerant. The wheel rim rotates through a gap between two superconducting Helmholtz coils that produce a magnetic field of up to 6 T. Helium gas is used

J. A. Barclay; W. F. Stewart; W. C. Overton; R. J. Candler; O. D. Harkleroad

1985-01-01

293

Gallium nitride as a material for spintronics  

NASA Astrophysics Data System (ADS)

The literature on the magnetic properties of GaN doped with magnetic impurities: the transition metals (Mn, Cr, Fe, Ni, and V) and rare earth elements (Gd, Eu, and Sm), as well as gallium nitride containing high concentration of gallium vacancies and quantum dots is reviewed. The properties of GaN doped by ion implantation and during the MBE and MOVPE growth of layers are considered. The undoped GaN and GaN films doped with the transition metals and rare earth elements often retain ferromagnetic properties at room temperature.

Khludkov, S. S.; Prudaev, I. A.; ??lbanov, ?. P.

2013-01-01

294

Modeling of liquid encapsulated gallium melts  

NASA Astrophysics Data System (ADS)

Liquid encapsulation crystal growth from the melt plays an important role in space processing. Use of an encapsulant may avoid evaporation of volatile components and may control thermocapillary flow, which becomes important in microgravity. In the present work the fluid physics of encapsulated liquid gallium is studied analytically and numerically in preparation to forthcoming experiments. It is shown that flow in the viscous encapsulant is essentially negligible and that liquid encapsulation reduces flow velocities in the encapsulated electronic melt. Flow velocity in the gallium is the main parameter in the studies.

Campbell, T. A.; Koster, J. N.

1995-06-01

295

Fluid/mineral interaction in UHP garnet peridotite  

NASA Astrophysics Data System (ADS)

We present two case studies of metasomatised garnet peridotite from the Sulu (Zhimafang) and of garnet orthopyroxenite from the Dabie Shan (Maowu) ultrahigh-pressure terranes (Eastern China). The mantle-derived peridotite from Zhimafang shows two ultrahigh-pressure (UHP) mineral assemblages. The older one is made of porphyroclastic garnet rich in inclusions (Grt 1), coarse exsolved clinopyroxene (Cpx 1) and coarse phlogopite flakes (Phl 1). The younger paragenesis consists of fine-grained olivine + clinopyroxene (Cpx 2) + orthopyroxene ± magnesite ± Phl 2 equilibrated with neoblastic garnet (Grt 2). The inclusions inside porphyroclastic Grt 1 are polyphase secondary inclusions related to microfractures cutting the garnet core. They display irregular shapes and contain microcrystals of calcic-amphibole, chlorite, phlogopite and rare talc, associated with pyrite and/or spinel. The low Al 2O 3 content (< 0.2 wt.%) in orthopyroxene coexisting with garnets and clinopyroxenes indicates equilibration at P = 4.0-6.0 GPa and T = 700-1000 °C. The trace element composition of Cpx 1 and Phl 1 combined with the petrologic and isotopic data of Yang and Jahn [Yang, J.J., Jahn, B.M., 2000. Deep subduction of mantle-derived garnet peridotites from the Su-Lu UHP metamorphic terrane in China. Journal of Metamorphic Geology 18, 167-180.] suggests that the Zhimafang garnet peridotite experienced metasomatism by a melt with alkaline character at high-temperature conditions ( T ˜ 1000 °C and P > 5.0 GPa). The microtextural identification of pseudosecondary inclusions in the porphyroclastic garnet core and their geochemical characterisation indicate that an incompatible element- and silicate-rich fluid subsequently metasomatised the garnet peridotite and equilibrated with the newly formed Cpx 2 probably during Triassic UHP metamorphism. Ultramafic metasomatic layers at Maowu Ultramafic Complex (Dabie Shan) consist of layered websterite and orthopyroxenite which preserve an old olivine + orthopyroxene (Opx 1) + garnet (Grt 1) ± Ti-clinohumite paragenesis, overgrown by poikilitic Opx 2. Grt 2 is associated with Opx 2 + phlogopite along the foliation, and fine-grained idiomorphic clinopyroxene also occurs. Grt 2 cores contain disseminated primary polyphase inclusions. The textural and geochemical analyses of the primary polyphase inclusions indicate that they derive from a homogeneous fluid characterised by high LILE concentrations with spikes in Cs, Ba, Pb and high U/Th. These inclusions are interpreted as remnants of the LILE- and LREE-enriched residual fluid produced when a crust-derived Si-rich metasomatic agent reacted with a previous harzburgite to form garnet orthopyroxenite. The in-situ trace element analyses of the major phases garnet, clinopyroxene and phlogopite that formed at the same time as the polyphase inclusions at Maowu, permit the determination of empirical mineral/fluid partitioning at pressures relevant for element recycling in subduction zones. Our estimated DCpx/fluid suggests that all LILE are highly incompatible, Th and U are moderately incompatible, Pb is close to unity and Sr is moderately compatible. Phlogopite preferentially incorporates Rb and K with respect to Ba and Cs, and Th with respect to U. The similarity between the residual Maowu fluid with the secondary inclusions in the UHP wedge-type garnet peridotite from Sulu, indicates that the fluids produced from reactions at the slab-mantle interface may be effective metasomatic agents in the mantle wedge. Such reactions may produce phlogopite, which plays an important role in controlling the LILE characteristics of the slab-derived fluid in subduction zones.

Malaspina, Nadia; Hermann, Jörg; Scambelluri, Marco

2009-01-01

296

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

297

Two-Dimensional Modeling of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistor.  

National Technical Information Service (NTIS)

Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT's) are microwave power devices that have the performance characteristics to improve the capabilities of current and future Navy radar and communication systems. The Office of Naval Research (O...

K. L. Holmes

2002-01-01

298

Fluid-induced Deformation of Garnet in Eclogite  

NASA Astrophysics Data System (ADS)

The response of subducting rocks to differential stress is a fundamental parameter in determining the strength evolution of slabs and the distribution of strain in subduction systems. However, making robust predictions of tectonic processes associated with subduction is hampered, because the rheology of important high- and ultrahigh pressure minerals is not well understood. A large discrepancy between experimental and field-based observation exists in the case of eclogite. The role of garnet is particularly ambiguous, with some experimental studies suggesting ultimate rigidity and field studies reporting large strain accommodation by this mineral. To investigate this topic, we integrated optical microscopy, element mapping, and electron backscatter diffraction techniques to perform a textural and micro-structural investigation into garnet polycrystals from an eclogite mylonite. Undeformed garnet polycrystals occurring in a supercooled frictional melt at HP conditions were used as a textural reference. Although commonly expected to represent a rigid component in high- and ultrahigh pressure rocks, garnet in the mylonites accomodated significant strain. The polycrystals were strongly flattened parallel to the HP mylonitic foliation and individual grains showed an average 15% uniaxial shortening. No record of dislocation creep was found. This is remarkable considering that this mechanism is expected to dominate garnet deformation at subduction P-T conditions. Garnet grains show dissolution features, indicative of deformation by intergranular pressure solution. These observations provide compelling textural evidence for the role of fluids and syn-tectonic porosity in the weakening of garnet. Hence, they allow important insight into the feedback loop linking fluid ingress, metamorphism and deformation of rocks in subduction zones.

Smit, M.; Scherer, E. E.; John, T.; Janssen, A.

2011-12-01

299

Optical identification of the gallium vacancy in neutron-irradiated gallium arsenide  

Microsoft Academic Search

Gallium arsenide grown by the metallorganic-chemical-vapor-deposition method was irradiated at room temperature with fast neutrons in the fluence range 1012 to 3×1015 cm-2 (1.00 MeV equivalent fluence in gallium arsenide). The effects of neutron irradiation were studied by photoluminescence (PL) spectroscopy in the energy range 0.5-1.55 eV. In the samples irradiated to 3×1013 cm-2 and higher fluences, we observe a

Anouar Jorio; Aiguo Wang; Martin Parenteau; Cosmo Carlone; Nelson L. Rowell; Shyam M. Khanna

1994-01-01

300

Thermomagnetic Writing in Magnetic Garnet Films  

NASA Astrophysics Data System (ADS)

The authors have succeeded in the development of rare-earth iron garnet (RIG) films whose magnetic coercivity is high enough to be used for Curie point writing. Specimens were prepared by means of liquid-phase epitaxial growth, where the lattice constant mismatch was set to be ˜0.04 Å. Sm and Er were used as rare-earth components to increase the coercivity through the enhancement of uniaxial anisotropy, while some amount of Bi was substitutes for them to strengthen the Faraday rotation. Optical and magnetic properties as well as thermomagnetic recording characteristics in the visible region have extensively been investigated. The writing threshold powers of a 0.55 ?m thick film were found to be 51, 32 and 24 mW for wavelengths ?{=}514.5, 488.0 and 457.9 nm respectively, under laser irradiation for 10 ?s with a spot radius of 2.5 ?m. Analytical discussions are made based on the heat conduction in the recording medium.

Inoue, Fumio; Itoh, Akiyoshi; Kawanishi, Kenji

1980-11-01

301

Fabrication of transparent yttrium aluminum garnet ceramic  

NASA Astrophysics Data System (ADS)

In this paper, the synthesis of Nd-doped yttrium aluminum garnet (Nd:YAG) spherical nano-crystallites was investigated by using the solvothermal method, and the optimum processing conditions for processing the transparent ceramic preparation was determined. Powder consisting of nanosized particles obtained by the solvothermal method displays significantly less crystallite agglomeration, indicating a high degree of sinterability. The phase structure and the morphology of the YAG crystallites were depended on the reaction conditions, the optimum temperature is 300 centigrade for 1h, at which the pure phase of spherically shaped YAG nanoparticles can be obtained. Microstructure evolution at different sintering stages demonstrated that fully transparent YAG ceramic can be fabricated by vacuum sintering at 1750 centigrade for 5h by using the as-synthesized powders. The ceramic has a relative density of about 99.98% of the theoretical value, and an average grain size of about 3-5?m. The transmittance of the ceramic is 55% in the visible range, and 70% in the infrared range.

Li, Xia

2009-03-01

302

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

303

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.

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

2013-01-01

304

Fluid/mineral interaction in mantle wedge garnet peridotites  

NASA Astrophysics Data System (ADS)

We present two case studies of metasomatised garnet peridotite from the Sulu (Zhimafang) and of garnet orthopyroxenite from the Dabie Shan (Maowu) ultrahigh-pressure terranes (Eastern China). The mantle derived peridotite from Zhimafang shows two ultrahigh-pressure (UHP) mineral assemblages. The older one is made of porphyroclastic garnet rich in inclusions (Grt1), coarse exsolved clinopyroxene (Cpx1) and coarse phlogopite flakes (Phl1). The younger paragenesis consists of fine-grained olivine + clinopyroxene (Cpx2) + orthopyroxene ± magnesite ± Phl2 equilibrated with neoblastic garnet (Grt2). The inclusions inside porphyroclastic Grt1 are polyphase secondary inclusions related to microfractures cutting the garnet core. They display irregular shapes and contain microcrystals of calcic-amphibole, chlorite, phlogopite and rare talc, associated with pyrite and/or spinel. The low Al2O3 content (<0.2 wt.%) in orthopyroxene coexisting with garnets and clinopyroxenes indicates equilibration at P=4.0-6.0 GPa and T=700-1000 °C. The trace element composition of Cpx1 and Phl1 combined with previous petrologic and isotopic data suggests that the Zhimafang garnet peridotite experienced metasomatism by a melt with alkaline character at high-temperature conditions (T=1000 °C and P>5.0 GPa). The microtextural identification of pseudosecondary inclusions in the porphyroclastic garnet core and their geochemical characterisation indicate that an incompatible element- and silicate-rich fluid subsequently metasomatised the garnet peridotite and equilibrated with the newly formed Cpx2 probably during Triassic UHP metamorphism. Ultramafic metasomatic layers at Maowu Ultramafic Complex (Dabie Shan) consist of layered websterite and orthopyroxenite which preserve an old olivine + orthopyroxene (Opx1) + garnet (Grt1) ± Ti-clinohumite paragenesis, overgrown by poikilitic Opx2. Grt2 is associated with Opx2 + phlogopite along the foliation, together with fine-grained idiomorphic clinopyroxene. Grt2 cores contain disseminated primary polyphase inclusions. The textural and geochemical analyses of the primary polyphase inclusions indicate that they derive from a homogeneous fluid characterised by high LILE concentrations with spikes in Cs, Ba, Pb and high U/Th. These inclusions are interpreted as remnants of the LILE- and LREE-enriched residual fluid produced when a crust derived Si-rich metasomatic agent reacted with a previous harzburgite to form garnet orthopyroxenite. The in situ trace element analyses of the major phases garnet, clinopyroxene and phlogopite that formed at the same time as the polyphase inclusions at Maowu, permit the determination of empirical mineral/fluid partitioning at pressures relevant for element recycling in subduction zones. Our estimated D(Cpx/fluid) suggests that all LILE are highly incompatible, Th and U are moderately incompatible, Pb is close to unity and Sr is moderately compatible. Phlogopite preferentially incorporates Rb and K with respect to Ba and Cs, and Th with respect to U. The similarity between the residual Maowu fluid with the secondary inclusions in the UHP wedge-type garnet peridotite from Sulu, indicates that the fluids produced from reactions at the slab-mantle interface may be effective metasomatic agents in the mantle wedge. Such reactions may produce phlogopite, which plays an important role in controlling the LILE characteristics of the slab-derived fluid in subduction zones.

Malaspina, Nadia; Scambelluri, Marco; Hermann, Jörg

2010-05-01

305

Gadolinium-153 as a brachytherapy isotope  

NASA Astrophysics Data System (ADS)

The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical 153Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering 153Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to 192Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical 153Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of 153Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the 153Gd source. The simulated 153Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h-1, indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the 153Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The 153Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to 192Ir.

Enger, Shirin A.; Fisher, Darrell R.; Flynn, Ryan T.

2013-02-01

306

Gadolinium-153 as a brachytherapy isotope.  

PubMed

The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical (153)Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering (153)Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to (192)Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical (153)Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of (153)Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the (153)Gd source. The simulated (153)Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h(-1), indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the (153)Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The (153)Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to (192)Ir. PMID:23339848

Enger, Shirin A; Fisher, Darrell R; Flynn, Ryan T

2013-02-21

307

Creep of garnet in eclogite: Mechanisms and implications  

NASA Astrophysics Data System (ADS)

The rheological properties of subducting rocks represent a fundamental parameter in the dynamics of subduction zones. Making robust predictions about these properties and the general strength evolution of subducting plates is hampered by a relatively restricted understanding of the mechanisms by which rocks deform at high- and ultrahigh pressure. This uncertainty is relates to the discrepancy between experimental and field-based observations of eclogite deformation and, in particular, the role of garnet. To further investigate this important aspect, we performed a textural and micro-structural investigation, applying optical microscopy, element mapping, and electron backscatter diffraction on deformed garnet polycrystals from an eclogite mylonite. The results were compared to those from a study of undeformed polycrystals that formed from a supercooled frictional melt at HP conditions. The mylonites' polycrystals are flattened parallel to the main high-pressure foliation in the rock and individual grains were shortened by an average 15%. Although dislocation creep is commonly presumed to dominate garnet straining in eclogites, no record of this mechanism was found. Instead, the garnet grains have dissolution surfaces indicative of deformation by intergranular pressure solution. The observations provide compelling evidence for the role of fluids and syn-tectonic porosity in the weakening of garnet: a supposedly rigid eclogite component. Such weakening represents a crucial step in the fundamental feedback loop between fluid ingress, metamorphism and near-instantaneous competence loss in rocks undergoing deep subduction.

Smit, Matthijs A.; Scherer, Erik E.; John, Timm; Janssen, Arne

2011-11-01

308

Gallium: Thermal Conductivity; Supercooling; Negative Pressure  

Microsoft Academic Search

The thermal conductivity of liquid gallium does not appear to have heretofore been measured. The method employed involved a comparison with the known thermal conductivity of mercury. The two liquids were sealed in two thin-walled glass tubes (30 cm long, 10 mm bore), the upper ends being inserted vertically through the bottom of a boiler containing boiling water. The tubes

Lyman J. Briggs

1957-01-01

309

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, Jr. , T.

1960-01-01

310

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

311

Russian-American Gallium solar neutrino Experiment.  

National Technical Information Service (NTIS)

The Russian-American Gallium solar neutrino Experiment (SAGE) is described. The solar neutrino flux measured by 31 extractions through October, 1993 is presented. The result of 69 (+-) (10 to the -7th power) to the 5th power SNU is to be compared with a s...

S. R. Elliott J. N. Abdurashitov T. J. Bowles

1995-01-01

312

PSG masks for diffusions in gallium arsenide  

Microsoft Academic Search

This paper describes the use of phosphosilicate glass (PSG) films as an effective mask against zinc and tin diffusions in gallium arsenide. It is shown that films with a high phosphorus pentoxide content (as much as 30 percent by weight) can be used to obtain adequate crack-free masks against these dopants. Effective masking was obtained for diffusion depths (unmasked regions)

B. J. Baliga; S. K. Ghandhi

1972-01-01

313

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

314

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

315

Superconductivity of gallium in various confined geometries  

Microsoft Academic Search

The superconductivity of gallium in porous glasses with various pore sizes and in opals is studied using a superconducting quantum interference device magnetometer. The single and double superconducting phase transitions are observed for different samples. Magnetization hysteresis loops are also measured and found to be dependent on pore sizes and geometry. The changes in magnetization below about 6.4 K are

E. V. Charnaya; C. Tien; K. J. Lin; C. S. Wur; Yu. A. Kumzerov

1998-01-01

316

Electrohydrodynamic Spraying of Gallium-Indium Alloy.  

National Technical Information Service (NTIS)

The electrical atomization of a liquid eutectic alloy of Gallium and Indium was investigated in a vacuum. A time-of-flight mass spectrometer was used to determine the drop characteristics in the spray. The atomization, per se, results from the instability...

D. S. Swatik

1967-01-01

317

SPECT gallium imaging in abdominal lymphoma  

SciTech Connect

A case of non-Hodgkin's lymphoma of the abdomen studied by gallium SPECT imaging is reported. The tomographic slices accurately demonstrated the location of residual disease after chemotherapy in the region of the transverse mesocolon. Previous transmission CT had shown considerable persistent retroperitoneal lymphadenopathy, but was not helpful in determining the presence of viable lymphoma.

Adcock, K.A.; Friefeld, G.D.; Waldron, J.A. Jr.

1986-05-01

318

Dopant-host relationships in rare-earth oxides and garnets doped with trivalent rare-earth ions  

NASA Astrophysics Data System (ADS)

The dopant-host interactions were considered in the Eu3+- and R3+-doped cubic C-type rare-earth oxides (R2O3) as well as in nondoped R3Ga5O12 and R3+-doped yttrium gallium garnets (Y3Ga5O12:R3+). The investigations were based mainly on the analyses of optical absorption and luminescence spectra using both new and previously published data. The concept of the crystal field (CF) strength parameter Nv was used in the considerations. When a R3+ dopant different from the host cation is embedded into the host lattice, a decrease in the R3+ site symmetry, distortions, and/or stresses are usually introduced. These local effects were found to affect significantly the strength of the crystal field in both R3+-doped Y2O3 and Y3Ga5O12 when compared to nondoped R2O3 and R3Ga5O12. With increasing positive size mismatch between the dopant and the host cation, the CF effect was found to be enhanced. The origin of this effect may be of electrostatic or covalent nature due to the decrease in dopant-oxygen distances or the delocalization of the 4f electrons, respectively. High-pressure investigations on Eu3+-doped R2O3 support the present conclusions. The formation of neighbor R3+-R3+ pairs in doped garnets induces additional lines in the optical spectra. For large ions such as Pr3+ and Nd3+ in Y3Al5O12 or Gd3Ga5O12, the pair lines compared to isolated ions result from modifications in the CF effect due to local distortions. The superexchange interaction for near-neighbor Pr3+ and Nd3+ pairs is manifested in dynamical behavior.

Antic-Fidancev, Elisabeth; Hölsä, Jorma; Lastusaari, Mika; Lupei, Aurelia

2001-11-01

319

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

320

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

321

Gadolinium as a neutron capture therapy agent.  

PubMed

The clinical results of treating brain tumors with boron neutron capture therapy are very encouraging. Researchers around the world are once again making efforts to develop this therapeutic modality. Gadolinium-157 is one of the nuclides that holds interesting properties of being a neutron capture therapy agent. It is estimated that tumor concentrations of up to 300 micrograms 157 Gd/g tumor can be achieved in brain tumors with some MRI contrast agents such as Gd-DTPA and Gd-DOTA, and up to 800 micrograms 157 Gd/g tumor can be established in bone tumors with Gd-EDTMP. Monte Carlo calculations indicate that with 250 ppm of 157Gd in tumor, neutron capture therapy can deliver 2000 cGy to a tumor of 2-cm diameter or larger with 5 x 10(12) n/cm2 of thermal neutron fluence at the tumor. Dose measurements with films and TLDs in phantoms verified these calculations. More extended Monte Carlo calculations demonstrate that neutron capture therapy with Gd possesses comparable dose distribution to B neutron capture therapy. With 5 x 10(12) n/cm2 thermal neutrons at the tumor, Auger electrons from the Gd produced an optical density enhancement on films that is similar to the effect caused by about 300 cGy of Gd prompt gamma dose and may further enhance the therapeutic effects. PMID:1508113

Shih, J L; Brugger, R M

1992-01-01

322

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

Code of Federal Regulations, 2010 CFR

...and Secondary Germanium and Gallium Subcategory § 421.180 ...and secondary germanium and gallium subcategory. The provisions...discharges resulting from the production of germanium or gallium from primary and secondary...

2009-07-01

323

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

Code of Federal Regulations, 2010 CFR

...and Secondary Germanium and Gallium Subcategory § 421.180 ...and secondary germanium and gallium subcategory. The provisions...discharges resulting from the production of germanium or gallium from primary and secondary...

2010-07-01

324

Gallium nitride nanowire electromechanical resonators  

NASA Astrophysics Data System (ADS)

Nanoscale mechanical resonators are of great interest for high-resolution sensing applications, where the small resonator mass and high quality factor (Q, defined as resonance frequency f0 over full width at half maximum power) lead to unprecedented sensitivity. Here, we investigate gallium nitride (GaN) nanowire (NW) resonators. The single-crystal, c-axis NWs are 5 mum -- 20 mum long, with diameters from 50 nm -- 500 nm, and grow essentially free of defects. Our initial experiments involve measuring the resonances of as-grown NWs in a scanning electron microscope, where we observe exceptionally high Q values of 10 4 -- 105, one to two orders of magnitude higher than most NWs of comparable size. Using a single NW as a mass sensor, we then demonstrate a sub-attogram mass sensitivity. To provide a more flexible measurement technique that avoids electron-microscope detection, we fabricate doubly clamped NWs with an entirely electronic drive and readout scheme using a combination of lithographic patterning and dielectrophoresis. An electrostatic gate induces vibration, while readout utilizes the piezoresistivity of GaN. Observed resonances range from 9--36 MHz with Q values typically around 103 at room temperature and 10 -4 Pa. We use the behavior of f0 and Q to sense the NW's local environment, such as the additional sources of energy dissipation not present in the as-grown NWs. By cooling the device to 8 K, Q increases by an order of magnitude to above 104, with a highest value to date of 26,000 under vacuum. We explore additional NW properties through the thermal noise in the NW's mechanical motion and the exponential decay of mechanical motion in the presence of burst drive. Finally, we investigate the low-frequency 1/f parameter noise displayed by f0. We show that the noise in f0 is consistent with noise in the NW's resistance leading to temperature noise from local Joule heating, which in turn generates resonance frequency noise. For sensor applications, there will be optimal drive conditions that balance the f 0 noise with the signal-to-noise ratio of the system. With these insights, along with the simple drive and readout technique, these GaN-NW doubly clamped resonators have significant potential for high-resolution sensing applications.

Gray, Jason Michael

325

Ammonothermal Growth of Gallium Nitride  

NASA Astrophysics Data System (ADS)

Bulk, single crystal Gallium Nitride (GaN) crystals are essential for enabling high performance electronic and optoelectronic devices by providing arbitrarily oriented, high quality, large, single crystal GaN substrates. Methods of producing single crystals of sufficient size and quality at a rate that would enable successful commercialization has been a major focus for research groups and companies worldwide. Recent advances have demonstrated remarkable improvements, though high cost and lack of high volume production remain key challenges. Major investments in bulk GaN growth were made at UCSB with particular focus on the ammonothermal method. The existing lab was upgraded and a new facility was designed and built with improved experimental setups for ammonothermal growth of GaN. The facilities can simultaneously operate up to 15 reactors of differing designs and capabilities with the ability to grow crystals up to 2 inches in diameter. A novel in-situ technique was devised to investigate the growth chemistry which occurs at typical operating conditions of 3,000 atm and 600 °C. Improvements in ammonothermal GaN include improved growth rates for c-plane by a factor of four to 344 ?m/day with an overall record growth rate of 544 ?m/day achieved for the (112¯2) plane. Crystal qualities comparable to that of the seed crystal were achieved. Impurity concentrations for transition metals were consistently reduced by a factor of 100 to concentrations below 1017 atoms/cm3. Optical transparency was improved by significantly reducing the yellow coloration typically seen for ammonothermal GaN. Single crystal GaN was successfully grown on large seeds and a 1 inch x ½ inch x ½ inch GaN crystal was demonstrated. To better understand the growth chemistry, models were created for the decomposition of ammonia under growth conditions, with initial experiments performed using the designed in-situ setup to verify the model's accuracy. To investigate the surface morphology and stability of basic ammonothermal GaN, various off-oriented HVPE GaN seed crystals were grown on and analyzed for growth rate, crystal quality, impurity incorporation, optical absorption, and surface morphology. A natural tendency for m-plane to off-orient itself by 0.5-1.5° towards-c-plane was observed, along with a region of apparent surface stability ranging from m-plane to {101¯1¯}.

Pimputkar, Siddha

326

Ion Implantation in Gallium Arsenide  

NASA Astrophysics Data System (ADS)

Ion implantation is a useful method to incorporate dopants into semiconductors. Understanding implantation processes is essential to the advancement of solid state technology. Because of its technical importance, gallium arsenide (GaAs) was chosen for this study. Hall effect, x-ray diffraction, and electrochemical capacitance-voltage (CV) profiling were used to study activation of silicon implants as functions of dose and annealing temperature and time. The annealing of crystalline damage and activation of dopants proceeds in a definite sequence. Implantation damage is annealed at approximately 625^ circC, with activation taking place between 625 and 675^circC. The electron profiles arising from Si implantation into GaAs possess long tails. Increasing the annealing temperature to greater than 900^circC results in a shortening of the tail because of the formation of an unknown acceptor defect. This result is reproducible and was used to enhance the performance of GaAs JFETs. Co-implantation of In or Ga with C was investigated by Local Vibrational Mode Spectroscopy (LVM), Rutherford Backscattering (RBS), Particle-Induced X-Ray Emission (PIXE), Photoluminescence (PL), and Hall effect. The dose of the C was 5 times 10^ {14} cm^{-2} 27 keV, while the doses of In, 185 keV, or Ga, 160 keV, ranged from 5 times 10 ^{13} to 5 times 10^{15} cm ^{-2}. The data shows that 99% of the C, when implanted alone and annealed, is not located as isolated, substitutional atoms on either sublattice, but in non-substitutional, inactive sites. The co-implanted ion acts to increase both the concentration of C _{rm As} ((C_ {rm As})) and the sheet hole concentration. For co-implant doses of 5 times 10 ^{13} and 5 times 10^{14} cm ^{-2}, these values are in good agreement. A co-implant dose of 5 times 10^{15} cm ^{-2} results in a hole concentration that is 30% less than the (C_{rm As}) and the co-implanted ions begin to occupy non-substitutional sites. The reduction in the concentration of holes due to C_{rm As} appears to be caused by a compensating donor defect which limits the maximum sheet hole concentration obtainable by the co-implantation technique in GaAs.

Madok, John Hamilton

327

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

328

Garnet compositions and their use as indicators of peraluminous granitoid petrogenesis - southeastern Arabian Shield  

USGS Publications Warehouse

Garnet, an uncommon accessory mineral in igneous rocks, occurs in seven small peraluminous granitoid plutons in the southeastern Arabian Shield; textural equilibrium between garnet and other host granitoid minerals indicates that the garnets crystallized from their host magmas. Compositions of the garnets form three groups that reflect host-granitoid compositions, which in turn reflect source compositions and tectonic regimes in which the host magmas were generated. Garnets from the seven plutons have almandine-rich cores and spessartine-rich rims. This reverse zoning depicts host magma compositional evolution; i.e. rimward spessartine enrichment resulted from progressive, host-magma manganese enrichment. The garnets are heavy rare-earth element enriched; (Lu/La)N ranges from 13 to 355 and one of the garnets contains spectacularly elevated abundances of Y, Ta, Th, U, Zn, Zr, Hf, Sn, and Nb. Involvement of garnets with these trace element characteristics in magma genesis or evolution can have dramatic effects on trace element signatures of the resulting magmas. Other researchers suggest that Mn-enriched magmas are most conducive to garnet nucleation. Although the garnetiferous granitoids discussed here are slightly Mn enriched, other genetically similar peraluminous Arabian granitoids lack garnet; Mn enrichment alone does not guarantee garnet nucleation. The presence of excess alumina in the magma may be a prerequisite for garnet nucleation. ?? 1988 Springer-Verlag.

du, Bray, E. A.

1988-01-01

329

Anisotropy study of garnet films grown over substrates populated with gold nanoparticles  

NASA Astrophysics Data System (ADS)

Anisotropy of garnet films grown by liquid phase epitaxy (LPE) over (100)-oriented garnet substrates populated with gold nanoparticles is studied. The results of ferromagnetic resonance (FMR) and optical hysteresis loop measurements as well as optical images of domain structures of LPE-grown garnet films are presented and discussed.

Lang, G.; Bowen, D.; Hung, L.; Krafft, C.; Mayergoyz, I.

2012-04-01

330

First occurrence of the garnet-ilmenite transition in silicates.  

PubMed

Pyrope garnet (Mg(3)Al(2)Si(3)O(12)) has been found to transform to an ilmenite-type phase at a loading pressure between 240 and 250 kilobars and at about 1000 degrees to 1400 degrees C in a diamond-anvil press coupled with laser heating. The lattice parameters for the ilmenite-type phase of (Mg(.75) Al(.25))(Si(.75) Al(.25))O(3) are a(0) = 4.755 +/- 0.002 and c(0) = 13.360 +/- 0.005 angstroms. The zero-pressure volume change associated with the garnet-ilmenite transition is calculated to be -7.1 percent. This result verifies the prediction that pyrope garnet would transform to the ilmenite structure at high pressure first suggested in 1962 by Clark et al. and Ringwood. PMID:17735674

Liu, L G

1977-03-11

331

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

332

Experimental Determination of the Energy Released as a Result of Neutron Capture by Gadolinium  

Microsoft Academic Search

A method for performing direct measurements of the energy of the neutron-capture reaction on gadolinium is proposed and tested. Measurement of the absorbed dose is an important problem for gadolinium neutron-capture therapy.

S. A. Klykov; S. P. Kapchigashev; V. I. Potetnya; S. E. Ul'yanenko; E. S. Matusevich; Yu. A. Kurachenko

2001-01-01

333

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

334

Domain effects in Faraday effect sensors based on iron garnets.  

PubMed

Domain-induced diffraction effects produced by two iron garnet thick films and two bulk crystals are compared. The thick films, characterized by a serpentine magnetic domain structure, produced nonlinear response functions; this is in qualitative agreement with a one-dimensional diffraction model. Bulk iron garnet crystals, which exhibited a complex three-dimensional domain structure, produced qualitatively similar effects that diminished with increasing crystal length. Differential signal processing resulted in a linear signal for the thick films and a primarily sinusoidal response for the bulk crystals. PMID:20963165

Deeter, M N

1995-02-01

335

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

336

Gadolinium as marker for in-vivo \\/sup 10\\/B imaging in BNCT  

Microsoft Academic Search

Measurements have been carried out for inquiring the feasibility of utilizing gadolinium for achieving 2D and 3D images of the spatial distribution of 10B in boron neutron capture therapy (BNCT). The spatial distribution of boron can be obtained by detecting gadolinium images, if gadolinium and boron are bound to the same carrier. The isotope 157Gd has a very high cross

G. Gambarini; M. Carrara; M. Cortesi; U. Danesi; R. Rosa; G. Rosi

2005-01-01

337

Study of the Photon Strength Functions for Gadolinium Isotopes with the DANCE Array  

Microsoft Academic Search

The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation.

D. Dashdorj; G. E. Mitchell; B. Baramsai; R. Chankova; A. Chyzh; C. Walker; U. Agvaanluvsan; J. A. Becker; W. Parker; B. Sleaford; C. Y. Wu; T. A. Bredeweg; A. Couture; R. C. Haight; M. Jandel; R. S. Rundberg; J. L. Ullmann; D. J. Vieira; J. M. Wouters; F. Becvár

2009-01-01

338

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

339

Interactions of Zircaloy cladding with gallium: 1998 midyear status  

SciTech Connect

A program has been implemented to evaluate the effect of gallium in mixed-oxide (MOX) fuel derived from weapons-grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in a light-water reactor. The graded, four-phase experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of a series of tests for Phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests will determine corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge}300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Although continued migration of gallium into the initially formed intermetallic compound can result in large stresses that may lead to distortion, this was shown to be extremely unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

Wilson, D.F.; DiStefano, J.R.; Strizak, J.P.; King, J.F.; Manneschmidt, E.T.

1998-06-01

340

Interactions of zircaloy cladding with gallium -- 1997 status  

SciTech Connect

A four phase program has been implemented to evaluate the effect of gallium in mixed oxide (MOX) fuel derived from weapons grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in LWR. This graded, four phase experimental program will evaluate the performance of prototypic Zircaloy cladding materials against: (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of an initial series of tests for phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement (LME), and (3) corrosion mechanical. These tests are designed to determine the corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge} 300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (in parts per million) of gallium in the MOX fuel. While continued migration of gallium into the initially formed intermetallic compound results in large stresses that can lead to distortion, this is also highly unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

Wilson, D.F.; DiStefano, J.R.; King, J.F.; Manneschmidt, E.T.; Strizak, J.P.

1997-11-01

341

Surface photovoltage spectroscopy applied to gallium arsenide surfaces  

NASA Technical Reports Server (NTRS)

The experimental and theoretical basis for surface photovoltage spectroscopy is outlined. Results of this technique applied to gallium arsenide surfaces, are reviewed and discussed. The results suggest that in gallium arsenide the surface voltage may be due to deep bulk impurity acceptor states that are pinned at the Fermi level at the surface. Establishment of the validity of this model will indicate the direction to proceed to increase the efficiency of gallium arsenide solar cells.

Bynik, C. E.

1975-01-01

342

Effects of Gallium and Mercury Ions on Transport Systems  

Microsoft Academic Search

Mercury was previously shown to exert toxic effects by influencing ion channels and transporters in the kidney and brain. Gallium alloys were suggested as less toxic restorative materials. To compare the toxicity of gallium ions with those of mercury ions, we applied gallium nitrate Ga(NO3)3 (0.1-100 ?M and mercuric chloride (HgCl2) (0.001-10 ?M) to Xenopus oocytes expressing mammalian ion channels

I. Moschen; K. Schweizer; C. A. Wagner; J. Geis-Gerstorfer; F. Lang

2001-01-01

343

The physics and modeling of gallium arsenide solar cells  

Microsoft Academic Search

Gallium arsenide is a versatile semiconductor used in many devices. Due to its nearly ideal bandgap energy for solar energy conversion and its compatibility with AlGaAs, gallium arsenide's use in solar cells has been widespread and is growing. Only its chief rival, silicon, is more popular as a high-efficiency material. To continue gallium arsenide's growth, this research was conducted for

Paul David DeMoulin

1988-01-01

344

Survey of the market, supply and availability of gallium  

SciTech Connect

The objective of this study was to assess the present consumption and supply of gallium, its potential availability in the satellite power system (SPS) implementation time frame, and commercial and new processing methods for increasing the production of gallium. Findings are reported in detail. The findings strongly suggest that with proper long range planning adequate gallium would be available from free-enterprise world supplies of bauxite for SPS implementation.

Rosi, F.D.

1980-07-01

345

Measurement of the solar neutrino capture rate with gallium metal  

Microsoft Academic Search

The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is 67.2+7.2+3.5-7.0-3.0 SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted standard solar model rate of 129 SNU. All the experimental procedures, including extraction of germanium from gallium, counting

J. N. Abdurashitov; V. N. Gavrin; S. V. Girin; V. V. Gorbachev; T. V. Ibragimova; A. V. Kalikhov; N. G. Khairnasov; T. V. Knodel; I. N. Mirmov; A. A. Shikhin; E. P. Veretenkin; V. M. Vermul; V. E. Yants; G. T. Zatsepin; T. J. Bowles; W. A. Teasdale; D. L. Wark; M. L. Cherry; J. S. Nico; B. T. Cleveland; R. Davis; K. Lande; P. S. Wildenhain; S. R. Elliott; J. F. Wilkerson

1999-01-01

346

Development of gadolinium based nanoparticles having an affinity towards melanin.  

PubMed

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. PMID:23334308

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

2013-02-21

347

Czochralski growth of thulium gallium garnets: Tm 3(Tm xGa 2-x)Ga 3O 12  

NASA Astrophysics Data System (ADS)

Large, optically-clear single crystals of Tm 3(Tm xGa 2-x)Ga 3O 12 ( x=0.09-0.15) have been grown using the Czochralski meth od for the first time. The growth direction was [001]. X-ray topography and optical methods were used to check the quality of the single crystals. Lattice constants in comparison to the melt stoichiometry are discussed, spectrographic and refractive data are presented.

Baermann, A.; Guse, W.; Saalfeld, H.

1982-05-01

348

Raman Determination of Super 2 F Sub 7/2 Crystal Field Levels in Ytterbium Aluminum and Ytterbium Gallium Garnets.  

National Technical Information Service (NTIS)

Raman scattering from YbAlG and YbGaG at 80 K was investigated in order to obtain reliable crystal field levels of the Yb(3+)((2)F(7/2)) ground manifold. The (2)F(7/2) assignments for YbGaG (0,546,610, and 624 reciprocal cm) are complete (four levels pred...

B. F. Argyle R. K. Chang R. L. Wadsack

1971-01-01

349

Prograde garnet growth along complex P T t paths: results from numerical experiments on polyphase garnet from the Wölz Complex (Austroalpine basement)  

NASA Astrophysics Data System (ADS)

Garnet in metapelites from the Wölz Complex of the Austroalpine crystalline basement east of the Tauern Window characteristically consists of two growth phases, which preserve a comprehensive record of the geothermal history during polymetamorphism. From numerical modelling of garnet formation, detailed information on the pressure temperature time ( P T t) evolution during prograde metamorphism is obtained. In that respect, the combined influences of chemical fractionation associated with garnet growth, modification of the original growth zoning through intragranular diffusion and the nucleation history on the chemical zoning of garnet as P and T change during growth are considered. The concentric chemical zoning observed in garnet and the homogenous rock matrix, which is devoid of chemical segregation, render the simulation of garnet growth through successive equilibrium states reliable. Whereas the first growth phase of garnet was formed at isobaric conditions of ˜3.8 kbar at low heating/cooling rates, the second growth phase grew along a Barrovian P T path marked with a thermal peak of ˜625°C at ˜10 kbar and a maximum in P of ˜10.4 kbar at ˜610°C. For the heating rate during the growth of the second phase of garnet, average rates faster than 50°C Ma-1 are obtained. From geochronological investigations the first growth phase of garnet from the Wölz Complex pertains to the Permian metamorphic event. The second growth phase grew in the course of Eo-Alpine metamorphism during the Cretaceous.

Gaidies, F.; de Capitani, C.; Abart, R.; Schuster, R.

2008-06-01

350

An AEM study of garnet clinopyroxenite from the Sulu ultrahigh-pressure terrane: formation mechanisms of oriented ilmenite, spinel, magnetite, amphibole and garnet inclusions in clinopyroxene  

Microsoft Academic Search

Optical microscopy, secondary electron microscopy and analytical electron microscopy were used to characterize crystallographic\\u000a orientation relationships between oriented mineral inclusions and clinopyroxene (Cpx) host from the Hujialing garnet clinopyroxenite\\u000a within the Sulu ultrahigh-pressure (UHP) terrane, eastern China. One garnet clinopyroxenite sample (2HJ-2C) and one megacrystic\\u000a garnet-bearing garnet clinopyroxenite (RZ-11D) were studied. Porphyroblastic clinopyroxene from sample 2HJ-2C contains oriented\\u000a inclusions of

Shyh-Lung Hwang; Tzen-Fu Yui; Hao-Tsu Chu; Pouyan Shen; Ru-Yuan Zhang; Juhn G. Liou

2011-01-01

351

New gallium precursors for the formation of high purity gallium arsenide by metal organic vapor phase deposition  

NASA Astrophysics Data System (ADS)

The reduction of gallium trichloride monoammonia adduct with lithium hydride affords lithium trichlorohydrido gallate whereas the non-coordinated trichloride affords the known species, lithium tetrahydrido gallate. Attempts to prepare the ammonia adduct of gallane via lithium tetrahydrido gallate and ammonium chloride resulted in decomposition with hydrogen evolution. Exploratory investigation geared towards the formation of gallium perfluoroalkyls, via discharge reactions involving hexafluoroethane and trifluoroiodomethane, resulted in the gallium reduction of the pyrex reactors - construction of quartz reactors is therefore necessitated.

Schram, E. P.

1984-06-01

352

Gallium Scan in Diagnosing Ocular Sarcoidosis  

PubMed Central

A 40-year-old man presented with floaters and painless progressive blurring of vision in the right eye for one month duration. Visual acuity in the right eye was 6/24. There was mild anterior chamber reaction and vitritis. The optic disc was swollen and elevated with presence of granulomatous lesion in the optic disc head. Blood investigations were unremarkable. Serum angiotensin converting enzyme (ACE) was normal and conjunctival biopsy showed presence of inflammatory cells. B-Scan ultrasound revealed an echo-dense lesion in the optic nerve head. There was increased uptake of the right lacrimal gland and presence of ‘Panda sign’ with Gallium scan. A diagnosis of right ocular sarcoidosis was made base on the clinical features and Gallium scan.

Ismail, Shatriah; Embong, Zunaina; Hitam, Wan Hazabbah Wan

2005-01-01

353

Molecular-Field Coefficients of Rare-Earth Iron Garnets.  

National Technical Information Service (NTIS)

Molecular-field coefficients of several rare-earth iron garnets (Tb, Dy, Ho, Er, and Yb) have been determined by fitting calculated and experimental magnetic-moment-vs-temperature curves. For these compositions, spin canting appears to cause a significant...

G. F. Dionne

1976-01-01

354

Systematic ab initio study of the compressibility of silicate garnets.  

PubMed

The structural properties of the silicate garnets andradite, Ca(3)Fe(2)Si(3)O(12), uvarovite, Ca(3)Cr(2)Si(3)O(12), knorringite, Mg(3)Cr(2)Si(3)O(12), goldmanite, Ca(3)V(2)Si(3)O(12), blythite, Mn(2+)(3)Mn(3+)(2)Si(3)O(12), skiagite, Fe(2+)(3)Fe(3+)(2)Si(3)O(12), calderite, Mn(2+)(3)Fe(3+)(2)Si(3)O(12), and khoharite, Mg(3)Fe(3+)(2)Si(3)O(12), have been investigated with a quantum-mechanical model as a function of applied pressure. The study has been performed with the density functional theory code CASTEP, which uses pseudopotentials and a plane-wave basis set. All structural parameters have been optimized. The calculated static geometries (cell parameters, internal coordinates of atoms and bond lengths), bulk moduli and their pressure derivatives are in good agreement with the experimental data available. Predictions are made for those cases where no experimental data have been reported. The data clearly indicate that the elastic properties of all silicate garnets are dominated by the compressibility of the dodecahedral site. The compression mechanism is found to be based on a bending of the angle between the centers of the SiO(4) tetrahedra and the adjacent octahedra, as in the aluminosilicate garnets. An analysis of the relationship between ionic radii of the cations and the compressibility of silicate garnets is presented. PMID:11262431

Milman, V; Akhmatskaya, E V; Nobes, R H; Winkler, B; Pickard, C J; White, J A

2001-04-01

355

Magneto-optics of Ce 3+ doped garnets  

NASA Astrophysics Data System (ADS)

The spectra of the Faraday rotation and MCD were measured in different magnetic (YIG, GaYIG) and nonmagnetic (YAG) garnets doped by Ce 3+ ions. The intense paramagnetic band was induced by cerium ions and it was observed to be strongly dependent on the nature of the next-nearest neighbours.

Ku?era, M.

1991-10-01

356

Instantaneous radial wall velocities in magnetic garnet bubble domains  

Microsoft Academic Search

Using an optical sampling microscope with a sample time of 10 nsec, single-exposure photographs of the transient bubble-domain configuration resulting from a uniform pulse field applied parallel to the bias field has been recorded at known times with respect to the applied pulse field. In this way the actual dynamic domain configuration of the bubble was observed. Mixed LPE garnet

G. J. Zimmer; L. Ga´l; K. Vural; F. B. Humphrey

1975-01-01

357

Quantitative analysis of trace OH in garnet and pyroxenes  

Microsoft Academic Search

To calibrate infrared (IR) spectroscopy for quantitative analysis of trace structural OH in specific minerals, we have determined concentrations of H in pure separates of mantle- derived pyrope garnet (56 :t 6 ppm H20 by weight), augite (268 :t 8, ppm H20), and enstatite (217 :t 11 ppm H20) by manometry after heating the samples and extracting H2 gas under

DAVID R. BELL; PHILLIP D. IHINGER; GEORGE R. ROSSMAN

1995-01-01

358

Synthesis of yttrium iron garnet precursor particles by homogeneous precipitation  

Microsoft Academic Search

Yttrium iron garnet (YIG) precursor particles were obtained by homogeneous precipitation in a nitrate salt solution by a reaction involving the thermal decomposition of urea. Chemical analysis indicated that solid phases were initially precipitated with sequential iron ion content. The precipitate formed was an amorphous mixed iron oxide phase. The complex composition and the thermal decomposition of the precipitate were

Y. S. Ahn; M. H. Han; C. O. Kim

1996-01-01

359

Interaction of microwaves with ring domains in magnetic garnet films  

Microsoft Academic Search

Magnetic bubble and ring domains are generated in LPE garnet films by locally exciting spin precession near the ferrimagentic resonance frequency at high microwave power densities. Due to the spin precession, radial and azimuthal forces act on the bubbles. The radii of the ring domains vary with the microwave power and the bias field. The stability range of these domains

H. J. Schmitt

1974-01-01

360

Thermally induced substrate fracture in LPE garnet film growth  

Microsoft Academic Search

The cracking of substrates which may arise during the withdrawal of garnet films from the baffled vertical furnaces conventionally used is shown to be the result of blocking of the convection currents by the substrate when it is level with the baffle. Temperature differences of over 200 °C have been measured through the substrate thickness. When differences of this magnitude

B. F. Stein; T. F. Chen; A. P. Greifer

1978-01-01

361

Integration of Garnet Films by Using Laser Etching Techniques  

Microsoft Academic Search

A new four-stage technique for integrating multiple iron garnet films on a single substrate is presented. A film is first grown on a GGG substrate by LPE. Ar ion laser etching is used in the second stage to remove a section of this film. Etching terminates automatically at the film-substrate interface. A second film is grown following the contours of

K. Ando; N. Takeda; N. Koshizuka

1987-01-01

362

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

363

Synthesis and characterization of yttrium iron garnet nanoparticles  

SciTech Connect

Yttrium iron garnet (YIG) was synthesized from a citrate gel containing ethylene glycol. The conditions for obtaining the pure phase depending on the citric acid/ethylene glycol ratio were studied. The sizes of the obtained particles ranged from 20 to 500 nm with the annealing temperature. Particles exhibited a rounded surface morphology, without faceted borders.

Vaqueiro, P.; Lopez-Quintela, M.A. [Universidad de Santiago de Compostela (Spain)] [Universidad de Santiago de Compostela (Spain); Crosnier-Lopez, M.P. [Universite du Maine, Le Mans (France)] [Universite du Maine, Le Mans (France)

1996-11-01

364

Synthesis and characterization of gallium colloidal nanoparticles  

Microsoft Academic Search

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

M. F. Meléndrez; G. Cárdenas; J. Arbiol

2010-01-01

365

Growth and characterization of gallium nitride nanowire  

Microsoft Academic Search

The present-day trend towards the development of nanostructures has resulted in several interesting material systems with unique and, in some cases, novel properties. Gallium nitride nanowires and nanodimensional structures have been realized using a simpler approach of vapour phase-assisted deposition.GaN nanodimensional structures have been realized on (0001) sapphire substrates by suitable surface treatment procedure using ferrous salt. Growth has been

Vipul Srivastava; V. Sureshkumar; P. Puviarasu; K. Thangaraju; R. Thangavel; J. Kumar

2005-01-01

366

The Baksan gallium solar neutrino experiment  

SciTech Connect

A radiochemical /sup 71/Ga-/sup 71/Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. The experiment is being expanded with the addition of another 30 tonnes. The motivation, experimental procedures, and present status of this experiment are presented. 43 refs., 1 fig., 1 tab.

Gavrin, V.N.; Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.L.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gayevsky, V.I.; Girin, S.V.

1989-01-01

367

Gallium-67 imaging in muscular sarcoidosis  

SciTech Connect

A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

1984-07-01

368

Peculiarities of gallium crystallization in confined geometry  

Microsoft Academic Search

The freezing and melting phase transitions for gallium embedded into a porous glass with a pore size of about 8 nm were studied\\u000a using acoustic, NMR, and x-ray techniques. It was shown that the broadened solidification and melting transitions upon deep\\u000a cooling up to complete freezing at 165 K were due to the formation of ?-Ga within pores. The offset

B. F. Borisov; E. V. Charnaya; A. V. Gartvik; Cheng Tien; Yu. A. Kumzerov; V. K. Lavrentev

2004-01-01

369

Combined external-beam PIXE and /?-Raman characterisation of garnets used in Merovingian jewellery  

NASA Astrophysics Data System (ADS)

Red garnets were the dominant gemstones used for jewels in Europe during the Early Middle Ages. We have studied over 350 garnets set on 12 jewels unearthed in the royal necropolis of the Saint-Denis Basilica, close to Paris. This famous collection of "cloisonné" style artefacts dates from the Merovingian period (late fifth century AD to early seventh century AD). The archaeological issue addressed is the identification of the geographical origin of these garnets, in view to establish the gem trading routes during the Dark Ages. External beam PIXE was used to determine the major constituents (Mg, Al, Si, Ca, Mn, Fe), specifying the garnet type (composition in various mineralogical end-members, e.g. almandine, pyrope, spessartite, …), and the trace element content (Cr, Y). Three sorts of garnets were identified. Ten jewels are adorned with almandine garnets (Fe-rich). One jewel has intermediate almandine-pyrope garnets ("rhodolite"). The last and most recent jewel is inlaid with pyrope (Mg-rich) garnets. Trace element content and slight differences in major composition allowed to distinguish five different sources: two sources for pyrope garnets (with and without chromium), and two sources for almandine garnets (distinctive calcium, magnesium and yttrium contents). A preliminary comparison with literature data suggested that almandine garnets may have been mined from India while the "rhodolite" garnets may have been imported from Sri Lanka. The sources of pyrope garnets could be the Bohemian deposits (Czech republic). In addition, ?-Raman spectrometry was used to identify most of the mineral inclusions (apatite, zircon, ilmenite, monazite, calcite, quartz) present in almandine garnets. Even if two specific types of inclusions were not identified, due to the lack of corresponding reference spectra in our database, the Raman spectra collected provided an interesting inclusion fingerprint.

Calligaro, T.; Colinart, S.; Poirot, J.-P.; Sudres, C.

2002-04-01

370

A YIG\\/GGG\\/GaAs-Based Magnetically Tunable Wideband Microwave BandPass Filter Using Cascaded Band-Stop Filters  

Microsoft Academic Search

A yttrium iron garnet\\/gadolinium gallium garnet-gallium arsenide (YIG\\/GGG-GaAs)-based magnetically-tunable wideband microwave band-pass filter with large tuning ranges for the center frequency (5.90-17.80 GHz) and the bandwidth (1.27-2.08 GHz) in the pass-band using a pair of cascaded band-stop filters is reported. The design and numerical simulation of the band-pass filter that incorporates multisegment microstrip meander-lines and 2-D nonuniform bias magnetic fields

Gang Qiu; Chen S. Tsai; Bert S. T. Wang; Yun Zhu

2008-01-01

371

[A basic study on gallium alloys for dental restorations. Improvement of liquid gallium alloy].  

PubMed

This study was made to compare the physical and chemical properties of amalgam with those of gallium alloy in which the invented liquid alloy containing the three fundamental components of Ga-Sn-In or Ga-Sn-In-Ag were used instead of mercury. Experiment 1. The physical and chemical properties were investigated after the liquid gallium alloy and high copper amalgam powder were mixed. The following results were obtained; 1) The invented gallium alloy group showed expansion in dimensional changes immediately after mixing. This alloy group showed the same compressive and diametral tensile strength as those in amalgam after 7 days. 2) This alloy group showed slightly more corrosion weight loss in 0.05% HCl and 1% lactic acid solutions than that in amalgam, but this alloy group showed the same corrosion weight loss in 1% NaCl solution and artificial saliva as in amalgam. Also this alloy group showed more discoloration (delta E, NBS) in 0.1% Na2S solution than that in amalgam, but this showed the same degree of discoloration in artificial saliva. Experiment 2. The physical and chemical properties were investigated after the same liquid gallium alloy and Ag-Pd-Sn-Cu-Zn alloy powder were mixed. The following results were obtained; 1) The invented gallium alloy group showed expansion in dimensional changes immediately after mixing. This showed superior quality in compressive and diametral tensile strength as compared with those of amalgam. 2) The invented gallium alloy showed slightly more corrosion weight loss in 0.05% HCl and 1% lactic acid solutions than that in amalgam, but this alloy group showed the same corrosion weight loss in 1% NaCl solution and artificial saliva as in amalgam. Also this alloy group showed more discoloration (delta E, NBS) in 0.1% solution than that in amalgam, but it was the same in artificial saliva. PMID:2488904

Yada, I

1989-01-01

372

Structural studies on synthesised gallium nitride  

NASA Astrophysics Data System (ADS)

Gallium nitride (GaN) powder has been synthesised through reaction between metal gallium and ammonia (NH 3) in a resistively heated quartz reactor. Experiments have been performed for various reaction temperatures (range 900-950°C) and reaction periods (4-12 h). The optimised reaction temperature and period are 950°C and 8 h, respectively. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) studies have been carried out on the synthesised GaN powder for different growth conditions and the results have been correlated. XRD pattern reveals that the synthesised GaN is of a single-phase wurtzite structure. The calculated lattice parameter values are a=3.186 Å and c=5.174 Å. XRD pattern for the samples prepared for the reaction period of less than 8 h exhibit GaN peaks along with gallium oxide (Ga 2O 3) peaks. The change in the surface features with respect to the reaction period has been investigated using SEM.

Senthil Kumar, M.; Ramasamy, P.; Kumar, J.

2000-04-01

373

Calculation of the Energetics of Water Incorporation in Majorite Garnet  

NASA Astrophysics Data System (ADS)

Global-scale mantle processes, such as subduction and plume ascent, are linked to surface processes through plate tectonics. Subduction rates, plume buoyancy, and rheology are among the properties associated with a convective mantle that are strongly affected by the volatile budget of the Earth's upper mantle and transition zone (410 km - 660 km). Therefore understanding of the role of hydrogen in mantle minerals is of importance when modeling mantle convection throughout Earth history into the Hadean. Garnet is found in the Earth's upper mantle and transition zone (~60 km - 710 km) with majorite garnet accounting for as much as 40 percent of the rock volume at 500 km. Given the potential of nominally anhydrous minerals, including garnet, to store H2O in the form of OH defects, constraining the hydrogen incorporation mechanism in majorite is crucial to an accurate interpretation of mantle processes. The water storage capacity of majorite is controlled by pressure, temperature, composition and the mechanism by which it incorporates hydrogen. Estimates of the potential of mantle garnets to be major water storage minerals, as well as the mechanics of hydrogen incorporation in majorite, are variable based on experimental evidence. This study addresses the deep-Earth water budget by calculating the defect energetics associated with hydrogen incorporation into tetragonal MgSiO3 (majorite) garnet between 0 and 20 GPa using atomistic simulations. At the pressure conditions of the Earth's mantle, hydrogen is most likely to be associated with protonation of oxygen adjacent to cation vacancies. At both P = 10 GPa and P = 20 GPa, our calculations show that of the six distinct oxygen positions, only three are likely to be protonated. Hydroxyl groups are predicted to be bound to Mg vacancies as [VMg(OH)2]X defect complexes, where the Mg vacancies are located at both the octahedral and dodecahedral sites.

Pigott, J. S.; Wright, K.; Gale, J. D.; Panero, W. R.

2013-12-01

374

Compensation and Characterization of Gallium Arsenide  

NASA Astrophysics Data System (ADS)

The properties of transition metals in gallium arsenide have been previously investigated extensively with respect to activation energies, but little effort has been made to correlate processing parameters with electronic characteristics. Diffusion of copper in gallium arsenide is of technological importance due to the development of GaAs:Cu bistable photoconductive devices. Several techniques are demonstrated in this work to develop and characterize compensated gallium arsenide wafers. The material is created by the thermal diffusion of copper into silicon-doped GaAs. Transition metals generally form deep and shallow acceptors in GaAs, and therefore compensation is possible by material processing such that the shallow silicon donors are compensated by deep acceptors. Copper is an example of a transition metal that forms deep acceptors in GaAs, and therefore this work will focus on the compensation and characterization of GaAs:Si:Cu. The compensation of the material has shown that the lower diffusion temperatures (500-600^ circC) form primarily the well-known Cu _{rm B} centers whereas the higher temperature anneals (>750 ^circC) result in the formation of CU_{rm A}. Using compensation curves, the copper density is found by comparing the compensation temperature with copper solubility curves given by others. These curves also show that the formation of CU_{rm B}, EL2, and CU_{rm A} can be manipulated by varying processing parameters such as annealing temperature and arsenic pressure. The compensation results are confirmed using Temperature-Dependent Hall (TDH) measurements to detect the copper levels. Also, the photoconductive properties of the material under illumination from 1.06 and 2.1 ?m wavelength laser pulses have been used to demonstrate the effects of the different processing procedures. The persistent photoconductivity inherent to these devices under illumination from the 1.06 ?m laser pulse is used to predict the concentration of the Cu_ {rm B}<=vel, and the fast hole capture times of the various acceptors are found through the response to a 140 ps (FWHM), 2.1 ?m laser pulse. Finally, the physical distribution of the copper atoms in the gallium arsenide wafer is examined using Glow Discharge and Secondary Ion Mass Spectroscopy (GDMS and SIMS). These techniques have been used to show that the copper diffusion in gallium arsenide is non-uniform with respect to depth and surface position.

Roush, Randy Allen

1995-01-01

375

Photochemical quenching of luminescence in uranium (VI), gadolinium, and terbium  

Microsoft Academic Search

Many of the problems associated with the photochemistry of uranium and in particular with the rare-earth elements remain unresolved. Three aspects are normally studied: the effect of photochemical processes on the luminescence properties of uranyl solutions [1, 2] and of gadolinium [3], the elucidation of the role of radiation in the oxidation of quadrivalent uranium to the hexavalent state [4],

T. S. Dobrolyubskaya; L. I. Anikina

1970-01-01

376

Nuclear Orientation of sup 149 Pm in Gadolinium Host.  

National Technical Information Service (NTIS)

The temperature dependence of the anisotropy of the 285.9 keV gamma-ray following the decay of oriented sup 149 Pm was measured. The sup 149 Pm parent nuclei were oriented at low temperatures between 14 and 80 mK in a gadolinium host containing 1 At.% of ...

N. G. Badzhelidze L. Ehn Z. Janout M. Finger N. A. Lebedev

1983-01-01

377

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

378

Effect of gadolinium oxysulfide filter disks in panoramic radiography  

Microsoft Academic Search

This study was designed to measure the absorbed radiation dose at fifteen sites in the head and neck of a tissue-equivalent phantom with primary interest in the dose delivered to the bone marrow, ocular lens, and the thyroid gland. The objectives were to quantify the dose reduction potential of gadolinium oxysulfide filtration in rare-earth imaging compared to the more conventional

Willbrand

1986-01-01

379

Optical properties of gadolinium-doped lead telluride  

Microsoft Academic Search

Some characteristics of the investigated crystals are given in Table i, and spectral dependences of the absorption coefficient are shown in Fig. I. As is evident from Table i, doping by gadolinium from the starting mixture during growth of PbTe crystals led to a complex type of change of their electrophysical parameters. At the same time, the electron concentration and

D. M. Zayachuk; V. I. Mikityuk

1991-01-01

380

Neutron Detection Utilizing Gadolinium Doped Hafnium Oxide Films.  

National Technical Information Service (NTIS)

Gadolinium (Gd) doped hafnium oxide (HfO2) was deposited onto a silicon substrate using pulsed laser deposition. Synchrotron radiation was used to perform Gd L3-edge extended X-ray absorption fine structure (EXAFS) measurements on 3%, 10%, and 15% doped H...

B. D. Blasy

2008-01-01

381

A NEW ISOTOPE OF GADOLINIUM VERY DEFICIENT IN NEUTRONS  

Microsoft Academic Search

BS>An isotope of gadolinium was obtained from ( alpha , ) reactions ; on Sm-144. The half-life is measured to be 24 plus or minus 1 min. It decays ; by electron capture and beta \\/sup +\\/emission. The branching ratio beta \\/sup +\\/; X\\/sub k\\/ is 35%. Betaenergy, determined by absorption method, indicates that E \\/; sub max\\/ = 2.5

J. Olkowsky; M. Le Pape; I. Gratot; L. Cohen

1959-01-01

382

Updates for Gadolinium neutron capture measurements at DANCE  

Microsoft Academic Search

Neutron capture reactions for several isotopes of Gadolinium have been measured at DANCE array in Los Alamos Neutron Science Center. Progress on the analysis is discussed. The detector response function of DANCE array is presented in connection with the statistical gamma-ray decay cascade simulation. In the region of separated neutron resonances, the statistical gamma-ray decay cascade is simulated using the

Dugersuren Dashdorj; G. E. Mitchell; B. Baramsai; R. Chankova; A. Chyzh; C. Walker; U. Agvaanluvsan; J. A. Becker; W. Parker; C. Y. Wu; T. Bredeweg; A. Couture; R. Haight; M. Jandel; J. O'Donnell; R. Rundberg; J. Wouters; J. Ullmann; D. Vieira; F. Becvar; M. Krticka

2007-01-01

383

Effect of Gallium Nitrate on Experimental Autoimmune Uveitis  

Microsoft Academic Search

Gallium nitrate (GN) has been shown to inhibit T cell-mediated inflammatory disease. The purpose of our study was to test the effect of gallium nitrate (GN) on experimental autoimmune uveitis (EAU). Experimental autoimmune uveitis was induced in male Lewis rats immunized with retinal S-antigen. Rats received subcutaneous injections of GN or saline one day prior to immunization and 1, 4,

MARK C. LOBANOFF; ALEXANDER T. KOZHICH; DANIEL I. MULLET; NICHOLAS GERBER; IGAL GERY; CHI-CHAO CHAN; SCOTT M. WHITCUP

1997-01-01

384

Adsorption of Gallium with N503 Levextrel Resin.  

National Technical Information Service (NTIS)

The adsorptivity of N503 (N, N-di(sec-octyl)acetamide) levextrel resin to gallium in the HCl medium was studied. The absorption rate and absorption isotherm of the resin to gallium were measured. The results show that the absorption of the resin to galliu...

J. R. Chen J. Hu C. Peng

1995-01-01

385

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

386

First results from the Soviet-American Gallium Experiment.  

National Technical Information Service (NTIS)

The Soviet-American Gallium Experiment is the first experiment able to measure the dominant flux of low energy p-p solar neutrinos. Four extractions made during January to May 1990 from 30 tons of gallium have been counted and indicate that the flux is co...

A. I. Abazov D. N. Abdurashitov O. L. Anosov L. A. Eroshkina E. L. Faizov

1990-01-01

387

Gallium alloy films investigated for use as boundary lubricants  

NASA Technical Reports Server (NTRS)

Gallium alloyed with other low melting point metals has excellent lubricant properties of fluidity and low vapor pressure for high temperature or vacuum environments. The addition of other soft metals reduces the corrosivity and formation of undesirable alloys normally found with gallium.

1966-01-01

388

Myopericarditis in acquired immunodeficiency syndrome diagnosed by gallium scintigraphy  

SciTech Connect

Myocarditis is among the cardiac complications of acquired immunodeficiency syndrome and, yet, is often not discovered until autopsy. Gallium scintigraphy has been employed in diagnosing this entity, but few data are available about its diagnostic accuracy and value. Here, the authors report two cases of myopericarditis as diagnosed by gallium scan.

Cregler, L.L.; Sosa, I.; Ducey, S.; Abbey, L. (Bronx VA Medical Center, NY (USA))

1990-07-01

389

Behavior of pure gallium in water and various saline solutions.  

PubMed

This study investigated the chemical stability of pure gallium in water and saline solutions in order to obtain fundamental knowledge about the corrosion mechanism of gallium-based alloys. A pure gallium plate (99.999%) was suspended in 50 mL of deionized water, 0.01%, 0.1% or 1% NaCl solution at 24 +/- 2 degrees C for 1, 7, or 28 days. The amounts of gallium released into the solutions were determined by atomic absorption spectrophotometry. The surfaces of the specimens were examined after immersion by x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). In the solutions containing 0.1% or more NaCl, the release of gallium ions into the solution was lowered when compared to deionized water after 28-day immersion. Gallium oxide monohydroxide was found by XRD on the specimens immersed in deionized water after 28-day immersion. XPS indicated the formation of gallium oxide/hydroxide on the specimens immersed in water or 0.01% NaCl solution. The chemical stability of pure solid gallium was strongly affected by the presence of Cl- ions in the aqueous solution. PMID:9555258

Horasawa, N; Nakajima, H; Takahashi, S; Okabe, T

1997-12-01

390

Two octanuclear gallium metallamacrocycles of topologically different connectivities.  

PubMed

Two topologically different metallamacrocycles--S8 symmetric octanuclear gallium(III) metalladiazamacrocycle and pseudo-D4 symmetric octanuclear gallium(III) metalladiazamacrocycle--could be prepared using two similar heteroditopic bridging ligands having asymmetrical tridentate-bidentate binding residues. PMID:18026590

Park, Mira; John, Rohith P; Moon, Dohyun; Lee, Kyungjin; Kim, Ghyung Hwa; Lah, Myoung Soo

2007-12-14

391

Early Gallium-67 abdominal imaging: pitfalls due to bowel activity  

SciTech Connect

In gallium scanning for abdominal inflammatory disease, early imaging has been advocated so physiological activity within the bowel will not be confused with pathologic uptake. The normal physiologic pattern of bowel uptake is not desribed in the literature. Our study was undertaken to evaluate the frequency and patterns of gallium-67 bowel activity which may occur when early imaging is performed.

Perkins, P.J.

1981-05-01

392

NEUTRON-ACTIVATION STUDY OF GALLIUM ARSENIDE CONTAMINATION BY QUARTZ  

Microsoft Academic Search

Gallium arsenide crystals were synthesized by the horizontal Bridgman ; method in neutron-activated boats of natural and synthetic fused quartz. ; lnstrumental radiochemical techniques were applied to determine the silicon ; concentrations from Si³¹ radioactivity measurements and to identify other ; trace elements transferred to the gallium arsenide during the process. All ; crystals were found completely enveloped in an

Werner Kern

1962-01-01

393

Indium Gallium Nitride Multijunction Solar Cell Simulation Using Silvaco Atlas.  

National Technical Information Service (NTIS)

This thesis investigates the potential use of wurtzite Indium Gallium Nitride as photovoltaic material. Silvaco Atlas was used to simulate a quad-junction solar cell. Each of the junctions was made up of Indium Gallium Nitride. The band gap of each juncti...

B. Garcia

2007-01-01

394

The duration of prograde garnet crystallization in the UHP eclogites at Lago di Cignana, Italy  

NASA Astrophysics Data System (ADS)

The distinct core-to-rim zonation of different REEs in garnet in metamorphic rocks, specifically Sm relative to Lu, suggests that Sm-Nd and Lu-Hf isochron ages will record different times along a prograde garnet growth history. Therefore, REE zonations in garnet must be measured in order to correctly interpret the isochron ages in terms of the garnet growth interval, which could span several m.y. New REE profiles, garnet crystal size distributions, and garnet growth modeling, combined with previously published Sm-Nd and Lu-Hf geochronology on a UHP eclogite of the Zermatt-Saas Fee (ZSF) ophiolite, Lago di Cignana (Italy), demonstrate that prograde garnet growth of this sample occurred over a ~ 30 to 40 m.y. interval. Relative to peak metamorphism at 38 to 40 Ma, garnet growth is estimated to have begun at ~ 11 to 14 kbar pressure at ~ 70 to 80 Ma. Although such a protracted garnet growth interval is surprising, this is supported by plate tectonic reconstructions which suggest that subduction of the Liguro-Piemont ocean occurred through slow and oblique convergence. These results demonstrate that REE zonations in garnet, coupled to crystal size distributions, provide a powerful means for understanding prograde metamorphic paths when combined with Sm-Nd and Lu-Hf geochronology.

Skora, Susanne; Lapen, Thomas J.; Baumgartner, Lukas P.; Johnson, Clark M.; Hellebrand, Eric; Mahlen, Nancy J.

2009-10-01

395

Laser photochemistry of gallium-containing compounds. [Trimethylgallium  

SciTech Connect

The production of gas-phase gallium atoms in the photolysis of trimethylgallium has been investigated at 193 nm and at other laser wavelengths. Ground state (4 /sup 2/P/sup 0//sub 1/2) and metastable (4 /sup 2/P/sup 0//sub 3/2/) gallium atoms are detected using laser-induced fluorescence techniques. Our results indicate that gallium atoms continue to be produced at long times after the laser pulse. The observed dependence on photolysis laser fluence, trimethylgallium pressure, and buffer gas pressure are consistent with a mechanism in which highly excited gallium methyl radicals undergo unimolecular decomposition to produce gallium atoms. Since this process is observed to happen on the time scale of hundreds of microseconds, these results have important implications for studies of metal deposition and direct laser writing by laser photolysis of organometallic compounds. 31 refs., 5 figs.

Baughcum, S.L.; Oldenborg, R.C.

1986-01-01

396

On the Formation Kinetics of Gallium Spinels . Zur Bildungskinetik von Gallium-Spinellen.  

National Technical Information Service (NTIS)

The reaction mechanism for gallium spinel formation is studied through interactions between NiO, MgO or CoO with Ga2O3 at 1230 to 1550 C. X-ray and phase transformation observations show that: (1) NiGa2O2 is formed by the transport of Ni(2+) and O(2-) thr...

W. Laqua

1971-01-01

397

Magnetic and magneto-optical properties of Y{sub 3}Fe{sub 5}O{sub 12}/Eu{sub 1}Bi{sub 2}Fe{sub 5}O{sub 12} heterostructures  

SciTech Connect

Superlattice heterostructures consisting of alternating single crystalline ferrimagnetic yttrium-iron-garnet (YIG) and Eu-substituted-bismuth-iron garnet (EBIG) thin films, deposited on [111] oriented single crystalline gadolinium-gallium-garnet substrates, show an increase in coercivity and Kerr rotation with the thickness ratio between the EBIG and the YIG layers. The substitution of one Eu{sup +3} ion per unit formula also induces the change in easy magnetization direction from in-plane to out-of-plane for all the EBIG/YIG films.

Simion, B.M.; Thomas, G. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering] [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; [Lawrence Berkeley Lab., CA (United States). Materials Science Div.; Ramesh, R. [Univ. of Maryland, College Park, MD (United States)] [Univ. of Maryland, College Park, MD (United States)

1995-11-01

398

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

399

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

400

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

401

Intracrystalline nucleation during the post-garnet transformation under large overpressure conditions in deep subducting slabs  

NASA Astrophysics Data System (ADS)

The mechanism of the post-garnet transformation in natural single-crystalline pyropic garnet has been examined under large overpressure conditions of ˜31-43 GPa using the multianvil apparatus with sintered diamond anvils. Intracrystalline nucleation was found to be dominant above 35-38 GPa, while only grain-boundary nucleation is responsible at lower pressures. In addition, natural pyropic garnet transformed to a single phase of perovskite without decomposing to multiple phases above 38 GPa. Both intracrystalline nucleation and polymorphic growth of the post-garnet transformation under large overpressure conditions would strongly enhance the transformation kinetics. Consequently, the post-garnet transformation may pwroceed rapidly in the subducting slab at depths near ˜950 km, which would cause substantial rheological weakening of the subducting slab. The metastable post-garnet transformation may also cause the seismic discontinuities at a depth of 900-1080 km depth, which is indeed observed beneath some subduction zones.

Nishi, Masayuki; Irifune, Tetsuo; Ohfuji, Hiroaki; Tange, Yoshinori

2012-12-01

402

Micro-Raman spectroscopy as a routine tool for garnet analysis.  

PubMed

A rapid system to obtain molar compositions of minerals belonging to the garnet group by means of Raman spectroscopy is illustrated here. A series of standard garnets, whose composition was determined by means of Wavelength Dispersive System (WDS) electron microprobe measurements, was used to correlate the wavenumbers of the different Raman peaks with chemical composition. A simple software routine was then developed in order to obtain garnet molar composition starting from the Raman spectrum, based on the assumption that in a solid solution belonging to the garnet family the Raman wavenumbers are linear combinations of end member wavenumbers, weighted by their molar fraction. The choice of the Raman bands used for the calculations and their behaviour are also discussed. The method, called MIRAGEM (Micro-Raman Garnets Evaluation Method), was then tested on a second series of garnets with satisfactory results. PMID:19144562

Bersani, Danilo; Andò, Sergio; Vignola, Pietro; Moltifiori, Gaia; Marino, Iari-Gabriel; Lottici, Pier Paolo; Diella, Valeria

2009-08-01

403

Microwave excitations in Bi-doped garnet films  

NASA Astrophysics Data System (ADS)

Garnet films of the series (Bi,Lu) 3(Fe,Mg) 5O 12, with Bi contents of 0.85/f.u., have been investigated using microwave techniques. The samples were 1.7-10 ?m thick, and were grown under different conditions. The uniaxial anisotropy and the resonance linewidths were evaluated over the temperature range 4.2-300 K. The magnetostatic wave propagation losses in the interval 3-6 GHz were measured and correlated with the resonance linewidths and the sample growth conditions. For these samples the resonance linewidth maxima occurred at about 50 K. The minima of the propagation loss and the resonance linewidth were obtained for the film growth velocity ? = 0.88 ?m/min. The processes of microwave soliton formation and propagation have been observed experimentally in these Bi-doped garnet films. Under the continuous-wave regime modulation instability was observed.

Gieniusz, R.; Desvignes, J. M.; Jab?o?ski, R.

1996-02-01

404

Ferromagnetic resonance in epitaxial iron-garnet magnetically coupled layers  

NASA Astrophysics Data System (ADS)

We present results of ferromagnetic resonance investigations of the double-layer magnetic films. The epitaxial structures examined are formed by a layer of doped garnet (YEuTmCa) 3(FeGe) 5O 12 with the easy axis along the surface normal and a sub-layer of pure yttrium-iron garnet Y 3Fe 5O 12 with easy plane anisotropy. Peculiarities are revealed in the dependences of the FMR resonance fields and the line width on the angle between magnetic field and the surface plane. These features are due to the interlayer magnetic coupling. The temperature range is determined in which the coupling effects in high-frequency features of these films can be studied.

Ustinov, V. V.; Kobelev, A. V.; Perepelkina, M. V.; Romanyukha, A. A.

1992-07-01

405

Compositional zoning in garnet and kinetics of metamorphic crystallization  

NASA Astrophysics Data System (ADS)

The kinetics of zoned garnet porphyroblast growth is exemplified in a sample of garnet-staurolite-biotite schist from the northern Ladoga region. The diffusion-controlled porphyroblast growth was accompanied by a decrease in the kinetic coefficient during phase reactions. Even at insignificant (1-2°C) thermal overstepping, the leading role of diffusion as a factor that controls kinetics of porphyroblast growth in medium-grade metapelites is consistent with the parameters of metamorphic crystallization: T = 500-650°C, t = 1 Ma; D {A1/app} = 10-14 cm2/s, L = 0.2-0.6 cm, r = 1-3 mm, ? C Al = 1.5 × 10-4-1.5 × 10-3 mol/cm3.

Gulbin, Yu. L.

2013-12-01

406

Production of high-purity gadolinium-153. 2. Removal of samarium, terbium, and microamounts of europium from gadolinium by extraction chromatography  

SciTech Connect

Extraction and extraction-chromatographic behavior of Sm, Eu, Gd, and Tb in the system di-2-ethylhexyl hydrogen phosphate (DEHP)-decane-nitric acid has been studied at various concentrations of nitric acid and lanthanide in aqueous phase. The optimal range of nitric acid concentrations for extraction-chromatographic separation of samarium, europium, gadolinium, and terbium has been determined. The influence of gadolinium concentration on distribution of europium and terbium has been examined. At gadolinium content in solution below 50% of the dynamic exchange capacity of the column, the gadolinium distribution coefficient slightly decreases with increasing gadolinium concentration in the initial solution, the distribution factors of the impurity lanthanides remaining virtually unchanged. With further increase in gadolinium content in the initial solution, the gadolinium distribution factor drastically decreases, and {open_quotes}tails{close_quotes} are formed at the expense of increasing fraction of the extracted complex form GdA{sub 3}. These data allowed a conclusion that composition of extracted complexes is different for Sm, Eu, Gd, and Tb. Conditions proposed for extraction-chromatographic purification of gadolinium in the system DEHP-decane-nitric acid provide for removal of impurity lanthanides (samarium, terbium, and microamounts of europium) with the purification factors greater than 100 (Sm, Tb) and about 2 (Eu) at the column charge of up to 50%.

Mel`nik, M.I.; Karelin, E.A.; Filimonov, V.T. [Research Inst. of Atomic Reactors, Dimitrovgrad (Russian Federation)

1995-03-01

407

Patterned gallium surfaces as molecular mirrors.  

PubMed

An entirely new means of printing molecular information on a planar film, involving casting nanoscale impressions of the template protein molecules in molten gallium, is presented here for the first time. The metallic imprints not only replicate the shape and size of the proteins used as template. They also show specific binding for the template species. Such a simple approach to the creation of antibody-like properties in metallic mirrors can lead to applications in separations, microfluidic devices, and the development of new optical and electronic sensors, and will be of interest to chemists, materials scientists, analytical specialists, and electronic engineers. PMID:17689239

Bossi, Alessandra; Rivetti, Claudio; Mangiarotti, Laura; Whitcombe, Michael J; Turner, Anthony P F; Piletsky, Sergey A

2007-09-30

408

Gallium-67 imaging in muscular sarcoidosis  

SciTech Connect

A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid muscle disease but is consistent with the rarity of clinical evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

1984-07-01

409

GARNET: A Graphical Attack Graph and Reachability Network Evaluation Tool  

Microsoft Academic Search

Attack graphs enable computation of important network security metrics by revealing potential attack paths an adversary could\\u000a use to gain control of network assets. This paper presents GARNET (Graphical Attack graph and Reachability Network Evaluation\\u000a Tool), an interactive visualization tool that facilitates attack graph analysis. It provides a simplified view of critical\\u000a steps that can be taken by an attacker

Leevar Williams; Richard Lippmann; Kyle Ingols

2008-01-01

410

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

411

A mixed domain structure in ferrite-garnet films  

Microsoft Academic Search

A stable static mixed domain structure consisting of strip domains and a cylindrical magnetic domain (CMD) is obtained in\\u000a (Bi0.7Lu0.3)3 (Fe0.8Ga0.2)5 O12 ferrite-garnet films. An analytic theory of the mixed domain structure is constructed. An analytic solution is obtained for\\u000a the shape of a distorted strip domain, which is in good agreement with experimental results.

M. L. Akimov; P. A. Polyakov; N. N. Usmanov

2002-01-01

412

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

413

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

414

Vibrations produced during erbium:yttrium–aluminum–garnet laser irradiation  

Microsoft Academic Search

The purpose of this study was to evaluate vibrations induced by an erbium:yttrium–aluminum–garnet (Er:YAG) laser in the non-contact\\u000a mode and compare the vibrations with different pulse durations and energy parameters. The experiment was conducted on an extracted\\u000a tooth built up in silicone impression material. The vibrations were measured by piezoelectric accelerometer for a super-short\\u000a pulse (SSP), a very short pulse

Ivica Anic; Ivana Miletic; Silvana Jukic Krmek; Josipa Borcic; Sonja Pezelj-Ribaric

2009-01-01

415

Experimental determination of cation diffusivities in aluminosilicate garnets  

Microsoft Academic Search

Data from experimentally-induced diffusion profiles at approximately 40 Kbar, 1,300–1,500° C in spessartine-almandine couples and a pyrope-almandine couple at ~ 40 Kbar, 1,440° C, described in Part I, were used to derive tracer diffusion coefficients (D*) of Fe, Mn and Mg in garnet. The experimental data were fitted by numerical simulations that model multicomponent, compositionally-dependent difussion, including the effects of

Timothy P. Loomis; Jibamitra Ganguly; Stephen C. Elphick

1985-01-01

416

Viscosity and mixing in molten (Ca, Mg) pyroxenes and garnets  

Microsoft Academic Search

A creep apparatus has been built to measure, with inaccuracies of less than 0.04 log poise, viscosities of supercooled silicate melts in the range 10 9 -10 14 poises. Measurements on seven pyroxene and five garnet supercooled liquid compositions along the joins MgSiO 3 -CaSiO 3 and Mg 3 Al 2 Si 3 O 12 Ca 3 Al 2 Si

Daniel R. Neuville; Pascal Richet

1991-01-01

417

Magnetoacoustic Effects in Rare-Earth Iron Garnets  

Microsoft Academic Search

We have used the techniques of linear magnetoacoustic birefringence and transverse ferroacoustic resonance to measure the real and imaginary parts of the index of refraction of soundwaves in the rare-earth iron garnets. The sound waves act as a probe to study the magnetoelastic coupling and the large rare-earth ion relaxation effects in concentrated samples. We investigated YbIG, DyIG and TbIG

Judy R. Franz; Bruno Luethi

1967-01-01

418

Local control of uniaxial anisotropy in LPE bubble garnet films  

Microsoft Academic Search

Local control of the growth-induced anisotropy in LPE bubble garnet films can be obtained by masking part of the film with a layer of epitaxial Gd3Ga5O12 and annealing at elevated temperatures (? 1200 °C) in a nitrogen atmosphere for approximately 1 h. In the regions exposed to nitrogen, the introduction of oxygen vacancies accelerates the reduction of Ku by the

E. M. Gyorgy; R. C. LeCraw; S. L. Blank; R. Wolfe

1974-01-01

419

Local control of uniaxial anisotropy in LPE bubble garnet films  

Microsoft Academic Search

Local control of the growth-induced anisotropy in LPE bubble garnet films can be obtained by masking part of the film with a layer of epitaxial Gd3Ga5O12 and annealing at elevated temperatures (~ 1200 °C) in a nitrogen atmosphere for approximately 1 h. In the regions exposed to nitrogen, the introduction of oxygen vacancies accelerates the reduction of Ku by the

E. M. Gyorgy; R. C. Lecraw; S. L. Blank; R. Wolfe

1974-01-01

420

Growth and characterization of (1 0 0) garnets for imaging  

NASA Astrophysics Data System (ADS)

Single crystalline films of garnets have been grown by liquid phase epitaxy (LPE) on (1 0 0) oriented substrates. The growth parameters are controlled to obtain films with in-plane magnetization and parameters that makes them excellently suited for magneto-optic imaging. The Faraday sensitivity of the film is easily tuned by altering the chemical composition. Here, we report on growth conditions needed to grow films with high sensitivity, up to almost 80°/A.

Hansen, R. W.; Helseth, L. E.; Solovyev, A.; Il'Yashenko, E.; Johansen, T. H.

2004-05-01

421

Yield and cost analysis of bubble devices on LPE garnets  

Microsoft Academic Search

Existing data for wafer processing of magnetic bubble devices on LPE garnet substrates indicates that high production yields will be obtained for memory chips of several thousand bits capacity. Conventional processing techniques can be used to obtain bit densities of 106-4×106 bits\\/in.2 at a manufacturing cost of under 50 millicents\\/bit. Several applications for bubble memories justify complete development of the

R. B. Clover

1974-01-01

422

Integrating magneto-optical garnet isolators on semiconductor substrates  

NASA Astrophysics Data System (ADS)

In optical communications, laser sources need to be protected from unwanted reflected light, a challenge best act by magneto-optical isolators. For integrating magneto-optical isolators with semiconductor devices, including most of these laser sources, it is necessary to develop film fabrication methods that are friendly to batch semiconductor processes. Integrated magneto-optical isolators each consist of a magnetic film layer, optical cladding layers, and a magneto-optical waveguide layer. Traditionally yttrium iron garnet (YIG) films, which are the active layers in magneto-optic isolators, have been grown by thermal deposition process, such as Liquid phase epitaxy (LPE) on garnet substrates. Such thermal processes could damage semiconductor substrates and other semiconductor devices during the deposition, and garnet substrates are difficult to integrate with semiconductor devices. In this work, YIG films were grown by low-temperature RF sputtering onto non-garnet substrates, MgO, fused quartz, and more importantly Si and InP. Two different sputtering methods were used, one involved single target sputtering and the other was multi-target sputtering with a partial pressure differential. After deposition, either post thermal annealing by a conventional tube furnace or a rapid thermal annealing (RTA) was done. To improve the optical characteristics of YIG films, Bi or Ce was substituted into the films. Next, SmCo thin magnetic films were investigated for biasing the active layer. These were grown by RF sputtering. All deposited films were characterized with Energy Dispersive X-ray Spectroscopy (EDS), and X-Ray Diffractometry (XRD), to find atomic composition and crystal structures. Vibrating Sample Magnetometry (VSM) was done for magnetic characterization. Together with integrated photonic crystal polarizer, fully integrated optical isolator can be achieved. Finally, photonic integrated circuits (PIC) and optoelectric integrated circuits (OEIC) can be realized with semiconductor integrated laser diode, fully integrated optical isolator and other integrated optical components such as modulators, amplifiers, detectors, and switches.

Sung, Sang-Yeob

423

Dielectric properties and electrical conduction in yttrium iron garnet (YIG)  

Microsoft Academic Search

The dielectric properties (dielectric constant and loss) of a single crystal of yttrium iron garnet (Y3Fe5O12) were measured in the temperature range 77–725 K and in the frequency range 100 Hz-1 MHz. AC conductivity was derived from\\u000a dielectric constant and loss. DC conductivity was measured in the temperature range 30–725 K. Thermoelectric power (TEP) was\\u000a measured from 77–800 K. On

Lalitha Sirdeshmukh; K Krishna Kumar; S Bal Laxman; A Rama Krishna; G Sathaiah

1998-01-01

424

Genesis of monazite and Y zoning in garnet from the Black Hills, South Dakota  

Microsoft Academic Search

The paragenesis of monazite in metapelitic rocks from the contact aureole of the Harney Peak Granite, Black Hills, South Dakota, was investigated using zoning patterns of monazite and garnet, electron microprobe dating of monazite, bulk-rock compositions, and major phase mineral equilibria. The area is characterized by low-pressure and high-temperature metamorphism with metamorphic zones ranging from garnet to sillimanite zones. Garnet

Panseok Yang; David Pattison

2006-01-01

425

Deposition of gold nanoparticles on liquid phase epitaxy grown garnet films and Faraday rotation enhancement  

NASA Astrophysics Data System (ADS)

Plasmon resonance induced Faraday rotation enhancement in liquid phase epitaxy grown garnet films with gold nanoparticles on their surfaces is discussed. Experimental results are presented, which reveal stronger Faraday rotation enhancement for gold nanoparticles obtained by the annealing of thicker gold films evaporated on garnet film surfaces. This stronger Faraday rotation enhancement can be attributed to larger dimensions and separations of gold nanoparticles, which increase the extent of penetration of plasmon resonance induced electric fields into garnet films.

Lang, G. S.; Bowen, D.; Krafft, C.; Mayergoyz, I. D.

2013-05-01

426

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

427

The genetic relationship of the deformed peridotites and garnet megacrysts from kimberlites with asthenospheric melts  

Microsoft Academic Search

New data on geochemistry of incompatible trace elements (Nb, Zr, Hf, Ti, Y, REE) in garnets (Ga) and clinopyroxenes (Cpx) from deformed high-temperature garnet lherzolites, harzburgites, and garnet megacrysts from the Udachnaya pipe are presented. According to textures and petrographic composition, the deformed Ga-bearing peridotites are subdivided into coarse- and fine-porphyroclastic. Rocks of the first type (Ga-lherzolites) are enriched in

L. V. Solov’eva; Yu. G. Lavrent’ev; K. N. Egorov; S. I. Kostrovitskii; V. N. Korolyuk; L. F. Suvorova

2008-01-01

428

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

429

Gallium induces the production of virulence factors in Pseudomonas aeruginosa.  

PubMed

The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by competing with iron, we hypothesized that it ultimately will lead cells to an iron deficiency status. As iron deficiency promotes the expression of virulence factors in vitro and promotes the pathogenicity of P. aeruginosa in animal models, it is anticipated that treatment with gallium will also promote the production of virulence factors. To test this hypothesis, the reference strain PA14 and two clinical isolates from patients with cystic fibrosis were exposed to gallium, and their production of pyocyanin, rhamnolipids, elastase, alkaline protease, alginate, pyoverdine, and biofilm was determined. Gallium treatment induced the production of all the virulence factors tested in the three strains except for pyoverdine. In addition, as the Ga-induced virulence factors are quorum sensing controlled, co-administration of Ga and the quorum quencher brominated furanone C-30 was assayed, and it was found that C-30 alleviated growth inhibition from gallium. Hence, adding both C-30 and gallium may be more effective in the treatment of P. aeruginosa infections. PMID:24151196

García-Contreras, Rodolfo; Pérez-Eretza, Berenice; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Coria-Jiménez, Rafael; Rangel-Vega, Adrián; Maeda, Toshinari; Wood, Thomas K

2014-02-01

430

Assessment of gallium-67 scanning in pulmonary and extrapulmonary sarcoidosis  

SciTech Connect

Gallium-67 scans have been widely employed in patients with sarcoidosis as a means of indicating alveolitis and the need for corticosteroid therapy. Observation of 32 patients followed 3 or more years after gallium scans showed no correlation between findings and later course: of 10 patients with pulmonary uptake, 7 recovered with minor residuals; of 18 patients with mediastinal of extrathoracic uptake, 10 had persistent or progressive disease; of 4 patients with negative initial scans, 2 had later progression. The value of gallium-67 scans as an aid to diagnosis was studied in 40 patients with extrapulmonary sarcoidosis. In 12 patients, abnormal lacrimal, nodal, or pulmonary uptake aided in selection of biopsy sites. Gallium-67 scans and serum ACE levels were compared in 97 patients as indices of clinical activity. Abnormal gallium-67 uptake was observed in 96.3% of the tests in active disease, and ACE level elevation occurred in 56.3%. In 24 patients with inactive or recovered disease, abnormal gallium-67 uptake occurred in 62.5% and ACE level elevation in 37.5%. Gallium-67 scans have a limited but valuable role in the diagnosis and management of sarcoidosis.

Israel, H.L.; Gushue, G.F.; Park, C.H.

1986-01-01

431

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

432

Doped gallium oxide nanowires for photonics  

NASA Astrophysics Data System (ADS)

Monoclinic gallium oxide, ?-Ga2O3, is a transparent conducting oxide (TCO) that presents one of the widest band gaps among this family of materials. Its characteristics make it highly interesting for applications in UV - visible - IR optoelectronic and photonic devices. On the other hand, the morphology of nanowires made of this oxide presents specific advantages for light emitting nanodevices, waveguides and gas sensors. Control of doping of the nanostructures is of the utmost importance in order to tailor the behavior of these devices. In this work, the growth of the nanowires is based on the vapor-solid (VS) mechanism during thermal annealing treatment while the doping process was carried out in three different ways. In one of the cases, doping was obtained during the growth of the wires. A second method was based on thermal diffusion of the dopants after the growth of undoped nanowires, while the third method used ion implantation to introduce optically active ions into previously grown nanowires. The study of the influence of the different dopants on the luminescence properties of gallium oxide nanowires is presented. In particular, transition metals and rare earths such as Cr, Gd, Er or Eu were used as optically active dopants that allowed selection of the luminescence wavelength, spanning from the UV to the IR ranges. The benefits and drawbacks of the three different doping methods are analyzed. The waveguiding behavior of the doped nanowires has been studied by room temperature micro-photoluminescence.

Nogales, E.; López, I.; Méndez, B.; Piqueras, J.; Lorenz, K.; Alves, E.; García, J. A.

2012-02-01

433

About a Gadolinium-doped Water Cherenkov LAGUNA Detector  

NASA Astrophysics Data System (ADS)

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&D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

Labarga, Luis

2010-11-01

434

Method for Removing Gadolinium from Used Heavy Water Reactor Moderator  

SciTech Connect

A novel process is described that treats used heavy water moderator (D{sub 2}O) contaminated with high concentrations of the neutron poison gadolinium nitrate, Gd(NO{sub 3}){sub 3}. Gadolinium is removed by precipitation. The resultant precipitate, GdPO{sub 4}.6H{sub 2}O, represents an extremely rare compound of considerable potential value. The resultant supernatant consisting of residual nitrate, NaNO{sub 3} or KNO{sub 3}, is less toxic and easier to process than the original waste. Thus, the alkali metal waste handling can be done with considerably less environmental concern. This waste can potentially be treated by a combination of electrochemical and biological methods.

Wilde, Edward W. [Westinghouse Savannah River Company (United States); Berry, Christopher J. [Westinghouse Savannah River Company (United States); Goli, Mudlagiri B. [Mississippi Valley State University (United States)

2003-10-15

435

An organic electroluminescent device made from a gadolinium complex  

NASA Astrophysics Data System (ADS)

A gadolinium ternary complex, tris(1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone) (phenanthroline) gadolinium [Gd(PMIP) 3(Phen)] was synthesized and used as a light emitting material in the organic electroluminescent (EL) devices. The triple layer device with a structure of indium tin oxide (ITO)/ N, N'-diphenyl- N, N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) (20 nm)/Gd(PMIP) 3(Phen) (80 nm)/2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (bathocuproine or BCP) (20 nm)/Mg: Ag(200 nm)/Ag(100 nm) exhibited green emission peaking at 535 nm. A maximum luminance of 230 cd/m 2 at 17 V and a peak power efficiency of 0.02 lm/w at 9 V were obtained.

Gao, D.-Q.; Huang, C.-H.; Ibrahim, K.; Liu, F.-Q.

2002-01-01

436

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.

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

2014-01-01

437

Modeling and Design of a Gadolinium Based Neutron Detector  

NASA Astrophysics Data System (ADS)

The goal is to measure the partial cross sections for (?, xn) and (?, f) on the actinides with the ultimate objective of developing and refining a method for the ?-ray interrogation of fissionable material. These measurements require the construction of a highly segmented neutron detector to record multiple neutrons emitted following photodisintegration and fission. Each detector segment will use a gadolinium-loaded liquid organic scintillator optically coupled to a photomultiplier tube. Gadolinium has one of the highest thermal neutron capture cross sections (49 kb), therefore its presence in the detector will greatly enhance neutron detection efficiency. A prototype detector of 3 L volume has been constructed and modeled using Geant4, a Monte Carlo based program. The detector model and conclusions developed from it along with the results from testing the prototype detector will be presented. S.Agostinelli et al., Nucl. Instr. and Meth. A506, 250, (2003).

Ticehurst, David; Tompkins, Jeromy; Karwowski, Hugon

2008-10-01

438

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.

Frydrychowicz, Alex; Lubner, Meghan G.; Brown, Jeffrey J.; Merkle, Elmar M.; Nagle, Scott K.; Rofsky, Neil M.; Reeder, Scott B.

2011-01-01

439

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

440

Novel gallium(III) phthalocyanine derivatives – Synthesis, photophysics and photochemistry  

Microsoft Academic Search

The syntheses of gallium(III) chloride phthalocyanine {(Cl)GaPc}, octaphenoxyphthalocyaninato gallium(III) chloride {(Cl)GaOPPc} and octakis(4-tert-butylphenoxy)phthalocyaninato gallium(III) chloride {(Cl)GaOTBPPc}; as well as their photophysical and photochemical parameters are hereby presented. Fluorescence quantum yields do not vary much among the three metallophthalocyanines (MPcs); therefore it was concluded that the effect of the substituents is not significant amongst (Cl)GaPc, (Cl)GaOPPc and (Cl)GaOTBPPc. Solvents effects, however,

Vongani Chauke; Abimbola Ogunsipe; Mahmut Durmu?; Tebello Nyokong

2007-01-01

441

Measurement of the solar neutrino capture rate with gallium metal  

SciTech Connect

The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is 67.2{sub {minus}7.0{minus}3.0}{sup +7.2+3.5} SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted standard solar model rate of 129 SNU. All the experimental procedures, including extraction of germanium from gallium, counting of {sup 71}Ge, and data analysis, are discussed in detail. {copyright} {ital 1999} {ital The American Physical Society}

SAGE Collaboration

1999-11-01

442

Solid-state gadolinium{endash}magnesium hydride optical switch  

SciTech Connect

The optical switching properties of gadolinium{endash}magnesium hydride have been demonstrated in a solid-state electrochromic device. With positive polarization of the hydride electrode, the visible reflectance approaches 35{percent} with virtually zero transmission, while with negative polarization, the visible transmission exceeds 25{percent} at 650 nm. The switching is reversible, with intermediate optical properties between the transparent and reflecting states. {copyright} {ital 1999 American Institute of Physics.}

Armitage, R. [Lawrence Berkeley National Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States); Rubin, M.; Richardson, T. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); OBrien, N. [Optical Coating Laboratory, Inc., 2789 Northpoint Parkway, Santa Rosa, California 95407 (United States)] [Optical Coating Laboratory, Inc., 2789 Northpoint Parkway, Santa Rosa, California 95407 (United States); Chen, Y. [Hewlett-Packard Laboratories, 3500 Deer Creek Road, Palo Alto, California 94304 (United States)] [Hewlett-Packard Laboratories, 3500 Deer Creek Road, Palo Alto, California 94304 (United States)

1999-09-01

443

Gadolinium oxide high- k gate dielectrics prepared by anodic oxidation  

Microsoft Academic Search

The growth and properties of gadolinium oxide (Gd2O3) films prepared by anodic oxidation were investigated. Uniform Gd2O3 thin film with good oxide quality was obtained. The X-ray diffraction (XRD) pattern of the Gd2O3 films showed that they had a poly-crystalline structure. The dielectric constants of Gd2O3 films oxidized at 30 and 60V are 9.4 and 12.2, respectively. The equivalent oxide

P. Y. Kuei; C. C. Hu

2008-01-01

444

Properties of Thermal Gadolinium Oxide Films on Silicon  

Microsoft Academic Search

The formation and electrical characteristics of thermal gadolinium (Gd) oxide films were investigated. A good uniform interface formed by proper treatment was observed by transmission electron microscopy (TEM) examination. The dielectric constant of the thermal Gd oxide films was approximately 10 from capacitance-voltage measurements. The X-ray diffraction (XRD) pattern of the thermal Gd oxide (Gd2O3) films showed that they had

Hong-Hsi Ko; Liann-Be Chang; Ming-Jer Jeng; Ping-Yu Kuei; Kuo-Yang Horng

2005-01-01

445

Gadolinium and nephrogenic systemic fibrosis: time to tighten practice  

Microsoft Academic Search

Nephrogenic systemic fibrosis (NSF) is a relatively new entity, first described in 1997. Few cases have been reported, but\\u000a the disease has high morbidity and mortality. To date it has been seen exclusively in patients with renal dysfunction. There\\u000a is an emerging link with intravenous injection of gadolinium contrast agents, which has been suggested as a main triggering\\u000a factor, with

Iosif A. Mendichovszky; Stephen D. Marks; Clare M. Simcock; Øystein E. Olsen

2008-01-01

446

Late gadolinium enhancement: precursor to cardiomyopathy in Duchenne muscular dystrophy?  

Microsoft Academic Search

Background Progressive cardiomyopathy is a common cause of death in Duchenne muscular dystrophy (DMD), presumably secondary to fibrosis\\u000a of the myocardium. The posterobasal and left lateral free wall of the left ventricle (LV) are initial sites of myocardial\\u000a fibrosis pathologically. The purposes of this study were to assess whether cardiac magnetic resonance imaging (CMRI), utilizing\\u000a late gadolinium enhancement (LGE), could

Michael D. Puchalski; Richard V. Williams; Bojana Askovich; C. Todd Sower; Kan H. Hor; Jason T. Su; Nathan Pack; Edward Dibella; William M. Gottliebson

2009-01-01

447

Gadolinium dimeglumine: an alternative contrast agent for digital subtraction angiography  

Microsoft Academic Search

.   The aim of this study was to evaluate gadolinium diethylenetriaminepenta-acetic acid (Gd-DTPA) as an alternative contrast\\u000a agent for digital subtraction angiography (DSA) in patients with renal insufficiency or previous anaphylactic reaction to\\u000a iodinated contrast agents. We performed 34 DSAs in 31 patients by use of the commercially available 0.5-M Gd-DTPA solution (Magnevist, Schering, Berlin, Germany). The contrast material was

F. D. Hammer; P. P. Goffette; J. Malaise; P. Mathurin

1999-01-01

448

Inadvertent intraosseous gadolinium injection during pediatric shoulder MR arthrography  

Microsoft Academic Search

A variety of problems can arise while performing MR arthrography of the shoulder. These have been well documented in the literature\\u000a and range from improper patient selection to errors in technique or in the choice of imaging sequences. We present a rare\\u000a case of inadvertent, painless intraosseous injection of dilute gadolinium into the proximal humeral epiphysis of a 13-year-old\\u000a male

Jason R. Pack; Martin I. Jordanov; John J. Block

2008-01-01

449

Slow neutron capture gamma rays from samarium and gadolinium  

Microsoft Academic Search

Slow neutron capture gamma rays in the energy region below 1.5 MeV from samarium oxide and gadolinium oxide have been studied, employing a simple technique comprising a 2 curie polonium-beryllium neutron source and a single crystal scintillation spectrometer. The energies of the observed gamma components are estimated and compared with the values obtained by previous authors who have used reactors

D. L. Sastry; S. Jnanananda

1964-01-01

450

Understanding garnet variability: Application of geometallurgy to diamonds and exploration  

NASA Astrophysics Data System (ADS)

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 indicator of diamond prospectivity, on the basis of comparison with garnet compositions known to be in some degree of equilibrium with diamonds. For mantle xenoliths and kimberlites, optical microscopy, electron microprobe analysis (EPMA), and scanning electron microscopy (SEM) are the main tools used for understanding key mineralogical and textural variability relationships. Mineralogy and texture reflect diamond genesis, metasomatic alteration, fluid migration and manifestation, volcanological processes, peridotite disaggregation, and other manifestations of mantle processes that are observable, describable, and applicable in exploration and mining. Mineralogy and texture studies lead to further questions that are better addressed by higher resolution chemical analysis of isotopes and rare earth elements, or luminescence. Understanding mineralogical and textural variability is the primary geological input for geometallurgy (geomet), the field integrating the earth sciences with the extractive industries. The framework for geomet encompasses geology, mineralogy, deposit modeling and extraction methods for the optimum value return of resources, and it relies on the fact that the mineralogy and texture of rocks influence subsequent interpretation and downstream applications. Developments in this area have been made possible by the new generation of high-speed SEM-based quantitative mineralogical instruments, enabling the statistical assessment of thousands of grains or particles, or samples, and their application to models for exploration, ore deposits, or geomet. For diamonds, this means identification and quantification of large mineralogical and textural data sets, and gives the geologist more involvement in model development. In this study, peridotitic and eclogitic garnets were examined in situ and as xenocrysts to gain understanding of the mineralogical and textural variability of the grains using SEM-based quantitative mineralogy. For concentrate garnets, the new technology presented here is the development of mineral definitions that reflect SEM counts and correlate with EPMA data. Internal compositional variability is mapped across individual grains as compared to EPMA spot analysis; designations of G10-G9 compositions, for example, are more complex when viewed in terms of individual internal grain compositional variability. The new mineral lists based on percentages of Ca-Cr count rates are compared to unknown garnets from exploration samples, and digitally categorized into bins reflecting potential diamond prospectivity or secondary alteration, as desired. The high analysis rate (approx. 150 determinations/second) means the SEM-based technique can be faster and produce more statistical information for the geologist who is making the model assessment in the field. Combined with new nontoxic mineral separation methodology in the field and software on the geologist's laptop, a great deal of interpretation can be accommodated in the field, at a reduced cost for shipping large volumes of samples to a central laboratory. Geomet for diamonds provides the mechanism for thinking of the entirety of a project, and using the geological and mineralogical information to predict process implications.

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

2009-05-01

451

An Electron Microprobe Study of Synthetic Aluminosilicate Garnets  

NASA Astrophysics Data System (ADS)

The aluminosilicate garnets represent an important mineral group. Common end-members are given by E3Al2Si3O12, where E=Fe2+ (almandine), Mn2+ (spessartine), Mg (pyrope), and Ca (grossular). End-members have been synthesized, but their exact compositions and stoichiometries are generally unknown. Synthetic aluminosilicate garnet can possibly contain minor Fe3+, Mn3+, F- and OH- and possibly vacancies. Slight atomic disorder over the 3 different cation sites may also occur. Natural crystals are considerably more complex. Electron probe microanalysis (EPMA) provides a method to determine garnet chemistry and stoichiometry. However, accurate determinations are not always a simple matter and uncertainties exist. We have started a study on well-characterized synthetic aluminosilicate garnets in order to i) determine more exactly their compositions and stoichiometries and ii) better understand possible complications in EPMA. Synthetic almandine, spessartine, pyrope, and grossular samples were synthesized under varying conditions both hydrothermally and dry and with different starting materials. A closed thermodynamic system was present and the bulk starting material composition represented the exact stoichiometric end-member garnet that was desired. IR, Raman and Mössbauer spectroscopy in some cases and X-ray diffraction were used to characterize the samples. Synthetic pyrope has been investigated with a SX51 with simple oxide/silicate standards (Fo90 olivine for Mg, wollastonite for Si, and both Al2O3 and kyanite for Al). Previously observed problems were reproduced: low stoichiometry for Al and high for Si and Mg. Fournelle (2007, AGU Fall Mtg) noted chemical peak shifts for Al and Mg Ka in garnets; this effect was eliminated here by proper peaking. Earlier suggestions for issues with mass absorption coefficients were not seen, and Probe for EPMA software demonstrated there was not much difference between the most recent FFAST values vs. the older Heinrich values. Similarly, a matrix correction based on CITZAF was compared with PAP, with little difference in Al (both low) and Mg values (both high), though PAP had higher Si values and CITZAF had lower ones. An assumption in EPMA is that the intensity of a single peak channel is representative of the integral of all x-ray counts under the total peak. It is known that this is not true for “light elements” (Be-F). We performed detailed wavescans of the complete peaks of Si, Al and Mg Ka of both standards and pyrope. Mg and Si peak scans showed little or no difference between pyrope and standard, but the Al scans had reproducible differences of 3% between the Al2O3 standard and unknown. This yielded an “area peak factor” correction of 1.03, which brings the Mg closer, but not all the way, to a stoichiometry of 2, Si to almost 3, and Mg closer to 3 but still too high. One possibility to be evaluated is whether there may be solid solution between pyrope and a minor majorite (Mg3(Mg,Si)Si3O12) component involving coupled substitution 2Al = Mg,Si at the octahedral site. In summary: Is this an EPMA analytical issue (peak fine structure differences), or an issue regarding a small amount of an unforseen component (majorite) in the garnet?

Fournelle, J.; Geiger, C. A.

2010-12-01

452

Interactions of Zircaloy Cladding with Gallium: Final Report  

SciTech Connect

The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional MOX fhel, on cladding material performance. Three previous repmts"3 identified several compatibility issues relating to the presence of gallium in MOX fuel and its possible reaction with fiel cladding. Gallium initially present in weapons-grade (WG) plutonium is largely removed during processing to produce MOX fhel. After blending the plutonium with uranium, only 1 to 10 ppm gallium is expected in the sintered MOX fuel. Gallium present as gallium oxide (G~OJ could be evolved as the suboxide (G~O). Migration of the evolved G~O and diffusion of gallium in the MOX matrix along thermal gradients could lead to locally higher concentrations of G~03. Thus, while an extremely low concentration of gallium in MOX fiel almost ensures a lack of significant interaction of gallium whh Zircaloy fhel cladding, there remains a small probability that corrosion effects will not be negligible. General corrosion in the form of surface alloying resulting from formation of intermetallic compounds between Zircaloy and gallium should be ma& limited and, therefore, superficial because of the expected low ratio of gallium to the surface area or volume of the Zircaloy cladding. Although the expected concentration of gallium is low and there is very limited volubility of gallium in zirconium, especially at temperatures below 700 "C,4 grain boundary penetration and liquid metal embrittlement (LME) are forms of localized corrosion that were also considered. One fuel system darnage mechanism, pellet clad interaction, has led to some failure of the Zircaloy cladding in light-water reactors (LWRS). This has been attributed to stresses in the cladding and one or more aggressive fission products. Stress corrosion cracking by iodines' 6 and LME by cadmium7>8 have been reported, and it is known that Zircaloy can be embrittled by some low-melting metals, (e.g., mercury).g LME is a form of environmentally induced embrittlement that can induce cracking or loss of ductility. LME requties wetting and a tensile stress, but it does not require corrosion penetration. Experimentally, it has been demonstrated that gallium can cause embrittlement of some alloys (e.g., aluminum) at low temperatures,'"' ] ] but experiments relative to LME of zirconium by gallium have been limited and inconclusive.*2 This report describes a series of tests designed to establish the effects of low levels of residual gallium in WG-MOX fhel on its compatibility with Zircaloy. In addition, to establish damage mechanisms it was important to understand types of cladding interactions and available stiety margins with respect to gallium concentration.

D.F. Wilson; E.T. Manneschmidt; J.F. King; J.P. Strizak; J.R. DiStefano

1998-09-01

453

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

454

[Kidney and iodinated and gadolinium-based contrast agents].  

PubMed

In patients with renal failure, iodinated contrast agents may cause acute deterioration of the renal function and gadolinium-based contrast agents (GBCAs) may cause nephrogenic systemic fibrosis (NSF). The administration of a contrast agent must thus be reviewed for each patient and evaluation of renal function is paramount even though its estimation using formulas derived from the creatinine level may fluctuate. For iodinated contrast agents, contrast induced nephropathy is reduced by hydratation, preferably intravenous, when the GFR is less than 60 ml/min. The risk for intravenous injections is less than the risk for arterial injections, and the GFR threshold may be reduced to 45 ml/min. For gadolinium-based contrast agents, patients at risk for NSF are those with end-stage renal disease and patients undergoing dialysis. In such cases, the injection of a gadolinium-based contrast agent is only considered after a risk-benefit analysis has been completed, an alternate linear or macrocyclic agent issued and the dose limited to 0,1 mmol Gd/kg. Recently, recommendations from US and European agencies have converged. Learning objectives: to be familiar with the risk factors of CIN with iodinated contrast agents; to be familiar with hydration procedures for patients at risk of CIN; to be familiar with the diagnostic criteria of NSF; to be familiar with the classification of GBCA with regards to the risk of NSF; to be familiar with the contraindications of the different groups of GBCA. PMID:21549885

Clément, O; Faye, N; Fournier, L; Siauve, N; Frija, G

2011-04-01

455

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

456

Combination of boron and gadolinium compounds for neutron capture therapy. An in vitro study.  

PubMed

In neutron capture therapy, the therapeutic effect of the boron compound is based on alpha particles produced by the B(n, alpha) reaction while with the gadolinium compound the main radiation effect is from gamma rays derived from the Gd(n, gamma) reaction. The uptake and distribution within the tumor may be different among these compounds. Thus, the combination of the boron and gadolinium compounds may be beneficial for enhancing the radiation dose to the tumor. Chinese hamster fibroblast V79 cells were used. For the neutron targeting compounds, 10B (BSH) at 0, 5, 10, and 15 ppm, and 157Gd (Gd-BOPTA) at 0, 800, 1600, 2400, 3200, and 4800 ppm, were combined. The neutron irradiation was performed with thermal neutrons for 30 min. (neutron flux: 0.84 x 10(8) n/cm2/s in free air). The combination of the boron and gadolinium compounds showed an additive effect when the gadolinium concentration was lower than 1600 ppm. This additive effect decreased as a function of gadolinium concentration at 2400 ppm and resulted in no additive effect at more than 3200 ppm of gadolinium. In conclusion, the combination of the boron and gadolinium compounds can enhance the therapeutic effect with an optimum concentration ratio. When the gadolinium concentration is too high, it may weaken the boron neutron capture reaction due to the high cross-section of gadolinium compound against neutrons. PMID:15943038

Matsumura, A; Zhang, T; Nakai, K; Endo, K; Kumada, H; Yamamoto, T; Yoshida, F; Sakurai, Y; Yamamoto, K; Nose, T

2005-03-01

457

High efficiency luminescent gallium nitride powders by direct synthesis from gallium metal and ammonia.  

NASA Astrophysics Data System (ADS)

High quality as-synthesized gallium nitride (GaN) powders have been obtained by a complete reaction between high purity gallium metal and ultra high purity ammonia in a horizontal quartz tube reactor at 1100 ºC. Elemental analysis showed that the powders obtained by this method have a stoichiometric nitrogen concentration (16.73 weight hexagonal crystalline structure of the GaN synthesized. Electron microscopy showed that the powders are formed by at least two kinds of particles, small size platelets and large size needles. The GaN powders obtained by this method are light gray and produce high ultra-violet luminescence around 370 nm (3.35 eV, near band-edge emission) when they are excited by accelerated electrons (cathodoluminescence) or by high energy photons (photoluminescence) at room temperature.

Garcia, Rafael; Bell, Abigail; Stevens, Michael; Ponce, Fernando

2003-10-01

458

Infrared Response of Impurity Doped Silicon MOSFET's (IRFET's): Fabrication and Characterization of the Gallium Doped Infrared Sensing MOSFET.  

National Technical Information Service (NTIS)

Fabrication and characterization of the gallium doped infrared sensing MOSFET is described. Gallium doped MOSFET device structures have been fabricated by diffusion of gallium from doped oxide sources into n-channel MOSFET's fabricated on a normal boron p...

L. Forbes

1976-01-01

459

Characteristics of Gallium-Substituted Hexagonal Mesoporous Silica: Effects of Gallium Content  

Microsoft Academic Search

Gallium-substituted hexagonal mesoporous silicas (Ga-HMS) with various Si\\/Ga ratios in the range of 15 and 200 were prepared at ambient temperature by neutral surfanctant templating pathway. The materials were synthesized by using dodecylamine as a template and tetraethylorthosilicate as a silicon source. They were characterized by energy dispersive X-ray spectroscopy, powder X-ray diffraction (XRD), N2 adsorption-desorption, thermogravimetric analysis, differential scanning

Hsin-Yu Lin; Yu-Lin Pan; Yu-Wen Chen

2005-01-01

460

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 en