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1

Ferromagnetic resonance of single-crystal YIG\\/gadolinium gallium garnet\\/YIG layers  

Microsoft Academic Search

We report on the microwave properties of single-crystal YIG\\/gadolinium gallium garnet\\/YIG grown in (110) layers, where YIG is yttrium iron garnet. The YIG layers were sufficiently thin so that single domain ferromagnetic resonance (FMR) was observed. FMR fields were measured as a function of field direction and magnitude and frequency. Bulk magnetic parameters deduced from FMR and vibrating-sample magnetometer measurements

Kunquan Sun; Carmine Vittoria; H. L. Glass; P. de Gasperis; R. Marcelli

1990-01-01

2

BRIEF COMMUNICATIONS: Mode locking in a neodymium laser with a gadolinium scandium gallium garnet switch  

NASA Astrophysics Data System (ADS)

A study was made of mode locking in a neodymium laser with a passive gadolinium scandium gallium garnet (GSGG) passive switch. When the transmission coefficient of GSGG was T= 20% and the length of the crystal was 1 cm, ultrashort pulses of minimum duration 80 psec and of energy of 0.5 mJ per pulse were generated.

Demchuk, M. I.; Zharikov, Evgeny V.; Zabaznov, A. M.; Manichev, I. A.; Mikha?lov, V. P.; Prokhorov, A. M.; Shkadarevich, A. P.; Chernyakovski?, A. F.; Shcherbakov, Ivan A.; Yumashev, K. V.

1987-02-01

3

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

4

A study of a strongly geometrically frustrated magnet: Gadolinium gallium garnet  

Microsoft Academic Search

Geometrically frustrated antiferromagnets are materials in which the geometry of the lattice results in frustration of the antiferromagnetic (AFM) exchange interactions. They are characterized by the absence of long-range order at temperatures well below the Curie-Weiss temperature (theta cw). One such material is Gd3Ga5O12 (gadolinium gallium garnet or GGG), in which the magnetic Gd ions are on three-dimensional (3D) corner-sharing

Yee-Kin Tsui

2000-01-01

5

Diode array side-pumped neodymium-doped gadolinium scandium gallium garnet rod and slab lasers  

NASA Astrophysics Data System (ADS)

Gadolinium scandium gallium garnet (GSGG) was studied as a high average power laser host material utilizing diode array side pumping. Maximum optical slope efficiencies of 41.5% for Nd:GSGG in the rod geometry and 32.5% for a Nd:Cr:GSGG zig-zag slab were obtained at 1.06 ?m. Nd:GSGG and Nd:YAG have similar fluorescence lifetimes while Nd:GSGG has better energy storage capabilities due to its smaller stimulated-emission cross section.

Caffey, David P.; Utano, Richard A.; Allik, Toomas H.

1990-02-01

6

Spectral and luminescence properties of gadolinium gallium garnet epitaxial films doped with terbium  

Microsoft Academic Search

Gadolinium gallium garnet single-crystal films containing terbium are grown through liquid-phase epitaxy from a supercooled\\u000a solution melt in the PbO-B2O3 system. The optical absorption spectra in the wavelength range 0.2–10.0 ?m and the luminescence spectra excited by synchrotron\\u000a radiation with energies in the range 3.5–30.0 eV are investigated at temperatures of 10 and 300 K. It is revealed that the

N. V. Vasil’eva; V. V. Randoshkin; V. N. Kolobanov; E. B. Kryukova; V. V. Mikha?lin; N. N. Petrovnin; V. G. Plotnichenko; Yu. N. Pyrkov; D. A. Spasski?; N. N. Sysoev

2007-01-01

7

Nd:Cr:GSGG (Gadolinium Scandium Gallium Garnet): Will it replace Nd:YAG (Yttrium Aluminum Garnet)?  

NASA Astrophysics Data System (ADS)

Gadolinium Scandium Gallium Garnet (GSGG) codoped with neodymium (Nd) and chromium (Cr) is a new laser material that can make more efficient lasers. It is compared to Nd-doped Yttrium Aluminum Garnet (YAG) for two types of systems: large zig-zag slab lasers and small rod lasers. Nd:Cr:GSGG has a significant advantage over Nd:YAG in large systems because of its high efficiency and availability in large sizes. In small rod systems, though, the larger thermal lensing and birefringence in Nd:Cr:GSGG make it less desirable than Nd:YAG from an optical standpoint, but its high efficiency means that laser system size and weight can be reduced. Progress in obtaining large Nd:Cr:GSGG slabs is reviewed. In this effort, Allied-Signal Corp. has successfully grown 5-inch diameter Nd:Cr:GSGG boules.

Stokowski, S. E.

1987-01-01

8

Structural and luminescence investigation on gadolinium gallium garnet nanocrystalline powders prepared by solution combustion synthesis  

NASA Astrophysics Data System (ADS)

Nanocrystalline powders of undoped and lanthanide (Pr3+, Tm3+)-doped gadolinium gallium garnet, Gd3Ga5O12 (GGG), were prepared by propellant synthesis and studied by x-ray powder diffraction (XRD), electron diffraction (ED), high-resolution electron microscopy (HREM) and luminescence spectroscopy. The x-ray diffraction patterns of the GGG samples were analysed using the Rietveld method. The Rietveld refinement reveals the existence of two garnet-type phases: both are cubic (space group Ia\\bar {3}d ) with a slightly different lattice parameter and probably a slightly different composition. Electron diffraction and electron microscopy measurements confirm the x-ray diffraction results. EDX measurements for lanthanide-doped samples show that stable solid solutions with composition Gd3-xLnxGa5O12, xap0.3 (Ln = Pr; Tm) have been obtained. The luminescence properties of the Tm3+-doped nanocrystalline GGG samples were measured and analysed.

Krsmanovi?, R.; Morozov, V. A.; Lebedev, O. I.; Polizzi, S.; Speghini, A.; Bettinelli, M.; Van Tendeloo, G.

2007-08-01

9

ACTIVE MEDIA. RESONATORS: Short-lived absorption in excited gadolinium scandium gallium garnet crystals activated with Cr and Nd  

NASA Astrophysics Data System (ADS)

An analysis is made of the possibility of reducing short-lived losses in a gadolinium scandium gallium garnet crystal activated with Cr and Nd when these losses are due to the short-wavelength component of the spectrum of the exciting radiation.

Zharikov, Evgeny V.; Nasel'ski?, S. P.; Ryabov, A. I.; Shcherbakov, Ivan A.

1987-04-01

10

Effects of impurities and atmosphere on the growth of Cr-doped gadolinium scandium gallium garnet. I  

NASA Astrophysics Data System (ADS)

The Czochralski growth technique was used to prepare crystals of Cr-doped gadolinium scandium gallium garnet. The concentrations of divalent and tetravalent dopants and the oxygen partial pressure in the growth atmosphere were varied to examine their effects on interface stability and growth morphology and on optical absorption at 1 ?m in the crystal.

Brandle, C. D.; Fratello, V. J.; Valentino, A. J.; Stokowski, S. E.

1987-11-01

11

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

12

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

NASA Astrophysics Data System (ADS)

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

Kim, Young Jin; Liu, Chen-Yu

2011-04-01

13

[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

14

Effects of impurities and atmosphere on the growth of Cr-doped gadolinium scandium gallium garnet. II  

NASA Astrophysics Data System (ADS)

A model is introduced that details the complexing between divalent and tetravalent species in garnet melts. This explains the phenomenon of interface instability in Czochralski crystal growth of gallium-containing garnets. Chromium may participate in this process when it is oxidized to its 4+ valence state. This model explains the effects of uncompensated divalent ions and growth atmosphere on absorption in the crystal.

Fratello, V. J.; Brandle, C. D.; Valentino, A. J.; Stokowski, S. E.

1987-11-01

15

Optical spectra, energy levels, and emission intensity calculations of trivalent thulium ions in gadolinium scandium gallium garnet  

NASA Astrophysics Data System (ADS)

Absorption spectra of trivalent thulium ions in gadolinium scandium gallium garnet are reported between 1.9 and 0.25 ?m at 4 K. Laser-induced fluorescence was observed at 4 K from the 1D2, 1G4, and 3H4 (4 and 300 K) manifolds. Site-selective excitation experiments reveal large fractions of thulium ions in both regular D2 sites and alternate sites. A crystal-field splitting calculation was carried out in which a parameterized Hamiltonian (including Coulombic, spin-orbit, and crystal-field terms in D2 symmetry) was diagonalized for all multiplet manifolds of the Tm3+ (4f12) configuration. The rms deviation between 56 experimental and calculated Stark levels was 10 cm-1. Calculations were carried out to predict branching ratios for emission from the 3H4 manifold to the 3H5, 3F4, and 3H6 manifolds, as well as line-to-line transition probabilities for transitions between the 3H4 manifold and the 3H5 manifold.

Seltzer, Michael D.; Gruber, John B.; Rosenblatt, Gregg H.; Morrison, Clyde A.; Filer, Elizabeth D.

1994-01-01

16

LETTER TO THE EDITOR: Pressure-induced amorphization in gadolinium scandium gallium garnet by x-ray diffraction and spectroscopic studies  

NASA Astrophysics Data System (ADS)

We report the first example of amorphization of garnets at high pressure and ambient temperature. Synchrotron x-ray diffraction and fluorescence spectroscopy at high pressure were performed on polycrystalline gadolinium scandium gallium garnet (GSGG) doped with 0953-8984/8/10/002/img1 and 0953-8984/8/10/002/img2. X-ray diffraction measurements reveal a loss of long-range order beginning at 0953-8984/8/10/002/img3 GPa. This is followed by a change in local environment for dopants at 70 GPa as indicated by the loss of fluorescence emission. The amorphous phase is retained at ambient conditions, after decompression. We present possible mechanisms for these two distinct transformations in GSGG.

Hua, Hong; Liu, Jun; Vohra, Yogesh K.

1996-03-01

17

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

18

LASERS: Spectral, luminescence, and lasing characteristics of gadolinium scandium aluminum garnet doped with chromium and neodymium  

NASA Astrophysics Data System (ADS)

An investigation was made of the spectral, luminescence, and lasing characteristics of gadolinium scandium aluminum garnet (GSAG) doped with chromium and neodymium. It was found that at the working activator concentrations, GSAG crystals are not inferior to gadolinium scandium gallium garnet crystals in terms of the efficiency of excitation energy transfer from the chromium to the neodymium ions. The maximum differential efficiency of 2.4% was obtained under free-running conditions.

Bolshakov, S. A.; Garmash, V. M.; Zhitnyuk, V. A.; Ermakova, L. A.; Okhrimchuk, A. G.; Raiskaya, L. N.; Syrtlanov, M. R.; Siyuchenko, O. G.; Tse?tlin, P. A.; Shestakov, A. V.

1988-04-01

19

A laser utilizing gadolinium-scandium-aluminum garnet doped with chromium and neodymium  

NASA Astrophysics Data System (ADS)

A repetitively pulsed laser is developed which utilizes a new active medium, namely, crystals of gadolinium-scandium-aluminum garnet doped with chromium and neodymium. Under single-pulse operation an absolute free-running efficiency of 3.4 percent has been achieved, the differential efficiency being 4.4 percent. Thermooptic effects in the new active medium are about 1.5 times weaker than in scandium-gallium garnet crystals.

Danilov, A. A.; Denisov, A. L.; Zharikov, E. V.; Zagumennyi, A. I.; Luts, G. B.

1988-09-01

20

Photorefractive effect in terbium gallium garnet  

Microsoft Academic Search

Terbium gallium garnet is an interesting representative of the family of rare-earth garnets. In these crystal we have observed a photorefractive effect. This effect is probably linked to the light-induced dichroitic and photochromic behavior of this crystal. Using Kramers-Kronig-relations an estimation shows that the light-induced absorption changes can explain the observed refractive index changes. The observation of holographic writing with

I. Amin; B. Sugg; Martin Fally; Romano A. Rupp

2002-01-01

21

Photochromism of doped terbium gallium garnet  

Microsoft Academic Search

In order to understand the photochromic effect in terbium gallium garnet doubly doped with calcium and cerium, the spectral characteristics of absorption changes induced by heating and irradiation are studied. Based on the findings we conclude that the photochromic band at 420nm originates from defects involving Tb4+ . Previously the band was attributed to Ce3+ . Two possible models are

H. Dachraoui; R. A. Rupp; K. Lengyel; M. A. Ellabban; M. Fally; G. Corradi; L. Kovács; L. Ackermann

2006-01-01

22

The photorefractive effect in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

A photorefractive effect in terbium gallium garnet with refractive index changes up to ?n = 5 × 10 -8 for elementary volume phase holograms is reported. The light-induced refractive index changes can directly be attributed via Kramers-Kronig relations to the observed photochromic and light-induced, linear dichroitic behavior. This can also explain the possibility of writing holograms with orthogonally polarized beams.

Sugg, B.; Nürge, H.; Faust, B.; Ruža, E.; Niehüser, R.; Reyher, H.-J.; Rupp, R. A.; Ackermann, L.

1995-01-01

23

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

Microsoft Academic Search

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

O. N. Budenkova; M. G. Vasiliev; V. S. Yuferev; I. A. Ivanov; A. M. Bul'Kanov; V. V. Kalaev

2008-01-01

24

PAPERS DEVOTED TO THE 90TH ANNIVERSARY OF A.M.PROKHOROV: Study of energy transfer in gadolinium—gallium garnet crystals doped with Yb3+ and Ho3+ ions  

NASA Astrophysics Data System (ADS)

The luminescence kinetics of Yb3+ donors and Ho3+ acceptors is quantitatively studied in gallium—gadolinium garnet (GGG) crystals doped with Yb3+ and Ho3+ ions. It is shown that the sensitisation of transitions in Ho3+ ions occurs due to migration-accelerated (hopping) energy transfer. The microparameters of donor—donor energy transfer are determined at 300 and 77 K. The microparameters of donor—acceptor energy transfer are found at the same temperatures at the first stage of successive sensitisation (resulting in the population of the 5I6 state of Ho3+ ions) and at the second stage of successive sensitisation of the 5S2, 5F4?5I8 transition in Ho3+ ions. At the second stage of sensitisation, the values of the microparameter of reverse energy transfer are also determined. The possibility of obtaining lasing at sensitised transitions in Ho3+ ions in Yb3+:Ho3+:GGG crystals pumped into the absorption band of Yb3+ ions is discussed.

Belovolov, A. M.; Belovolov, M. I.; Dianov, Evgenii M.; Ivanov, M. A.; Kochurikhin, V. V.; Randoshkin, V. V.

2006-08-01

25

Photorefractive effect in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

Terbium gallium garnet is an interesting representative of the family of rare-earth garnets. In these crystal we have observed a photorefractive effect. This effect is probably linked to the light-induced dichroitic and photochromic behavior of this crystal. Using Kramers-Kronig-relations an estimation shows that the light-induced absorption changes can explain the observed refractive index changes. The observation of holographic writing with orthogonally polarized beams may by attribute to orientationally non- equivalent centers, which become anisotropic by the absorption of light after illumination. Yet, the nature of these centers is unclear. Further studies are already under way to clarify this point.

Amin, I.; Sugg, B.; Fally, Martin; Rupp, Romano A.

2002-02-01

26

Terbium Gallium garnet for Faraday Effect Devices  

Microsoft Academic Search

The magneto-optic crystal terbium gallium garnet (TGG) has been grown by the Czochralski process. Boules of 2-3 cm diameter and 10-15 cm long were obtained core, strain, and defect free. The properties of TGG are ideal for Faraday effect devices such as modulators and isolators. The Verdet constant has been measured from 500-1060 nm with values ranging from 0.75-0.12 min

D. J. Dentz; R. C. Puttbach; R. F. Belt

1974-01-01

27

Terbium Gallium garnet for Faraday Effect Devices  

Microsoft Academic Search

The magneto-optic crystal terbium gallium garnet (TGG) has been grown by the Czochralski process. Boules of 2–3 cm diameter and 10–15 cm long were obtained core, strain, and defect free. The properties of TGG are ideal for Faraday effect devices such as modulators and isolators. The Verdet constant has been measured from 500–1060 nm with values ranging from 0.75–0.12 min

D. J. Dentz; R. C. Puttbach; R. F. Belt

1974-01-01

28

The photorefractive effect in terbium gallium garnet  

Microsoft Academic Search

A photorefractive effect in terbium gallium garnet with refractive index changes up to ?n = 5 × 10?8 for elementary volume phase holograms is reported. The light-induced refractive index changes can directly be attributed via Kramers-Kronig relations to the observed photochromic and light-induced, linear dichroitic behavior. This can also explain the possibility of writing holograms with orthogonally polarized beams.

L. Ackermann

1995-01-01

29

Photochromism of doped terbium gallium garnet  

NASA Astrophysics Data System (ADS)

In order to understand the photochromic effect in terbium gallium garnet doubly doped with calcium and cerium, the spectral characteristics of absorption changes induced by heating and irradiation are studied. Based on the findings we conclude that the photochromic band at 420nm originates from defects involving Tb4+ . Previously the band was attributed to Ce3+ . Two possible models are suggested and discussed, both of which are in agreement with the obtained experimental results.

Dachraoui, H.; Rupp, R. A.; Lengyel, K.; Ellabban, M. A.; Fally, M.; Corradi, G.; Kovács, L.; Ackermann, L.

2006-10-01

30

Nanocrystalline gadolinium iron garnet for circulator applications  

NASA Astrophysics Data System (ADS)

Due to high resistivity and low microwave losses, gadolinium iron garnets (GdIG) are useful materials for non-reciprocal devices such as circulators or isolators. Keeping the miniaturization and cost reduction in mind, the trend is to modify the conventional methods of preparation of samples. In this connection we have synthesized nanocystalline GdIG by using the Microwave Hydrothermal method at 160 °C/45 min. As synthesized powders were characterized by using X-ray diffraction (XRD), transmission electron microscopy and Fourier Transform Infrared Spectroscopy. XRD patterns show the formation of a garnet phase with crystallite size varying between 19 nm and 40 nm. Differential Thermal Analysis studies were also carried out on the nanopowders. The powders were densified at a lower sintering temperature of 1100 °C/45 min using a microwave sintering method. The sintered samples were characterized by XRD and atomic force microscopy. The frequency dependence of complex permittivity and ferromagnetic resonance were measured in the Ka band frequency (27-40 GHz). Magnetic properties were also measured at room temperature.

Ramesh, T.; Shinde, R. S.; Murthy, S. R.

2012-11-01

31

LASERS AND LASER AMPLIFIERS: Laser utilizing gadolinium scandium aluminum garnet activated with chromium and neodymium  

NASA Astrophysics Data System (ADS)

A pulse-periodic laser has been developed utilizing a new active medium, a gadolinium scandium aluminum garnet crystal activated with chromium and neodymium. An absolute free-running efficiency of 3.4% with a differential efficiency of 4.4% was obtained in the single-pulse regime. Thermooptic effects in the new active medium were approximately 1.5 times weaker than those in scandium gallium garnet crystals. The damage threshold for cylindrical active elements with a mat surface was approximately 500 W per centimeter of the active element.

Danilov, A. A.; Denisov, A. L.; Zharikov, Evgeny V.; Zagumenny?, A. I.; Lutts, G. B.; Nikol'ski?, M. Yu; Tsvetkov, V. B.; Shcherbakov, Ivan A.

1988-09-01

32

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

NASA Astrophysics Data System (ADS)

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.; Vasiliev, M. G.; Yuferev, V. S.; Ivanov, I. A.; Bul'Kanov, A. M.; Kalaev, V. V.

2008-12-01

33

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

34

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

E-print Network

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

Steve K. Lamoreaux

2007-01-17

35

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

NASA Astrophysics Data System (ADS)

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

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

1991-03-01

36

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

PubMed

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

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

2012-04-23

37

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

38

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

Microsoft Academic Search

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium\\u000a gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been\\u000a performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related\\u000a to their

O. N. Budenkova; M. G. Vasiliev; V. S. Yuferev; I. A. Ivanov; A. M. Bul’kanov; V. V. Kalaev

2008-01-01

39

Electronic Raman Spectra: Crystal Field in Terbium Aluminum Garnet and Europium Gallium Garnet  

Microsoft Academic Search

The crystal-field splittings of the 7F multiplet of Eu3+ and Tb3+ have been determined in europium gallium garnet (EuGaG) and terbium aluminum garnet (TbAlG) from light scattering, fluorescence, and absorption spectra. The data were used to derive a set of crystal-field parameters for the two garnet systems. In these calculations the Hamiltonian appropriate for the D2 symmetry of the rare-earth

D. Boal; P. Grunberg; J. A. Koningstein

1973-01-01

40

Growth of uniaxial magnetic garnet films by rf sputtering  

Microsoft Academic Search

Epitaxial films of gadolinium-gallium-substituted yttrium iron garnet (Gd : Ga : YIG) films have been grown by rf-sputtering techniques on ?111? gadolinium gallium garnet (GGG) substrates. The as-deposited films were annealed to yield crack-free epitaxial garnets, which exhibited movable magnetic (bubble) domains. Typical magnetic data for the sputtered Gd : Ga : YIG films are presented.

J. J. Cuomo; V. Sadagopan; J. Deluca; P. Chaudhari; R. Rosenberg

1972-01-01

41

Faraday effect in gadolinium iron garnet  

Microsoft Academic Search

The Faraday effect (FR) is investigated experimentally in GdIG (GdâFeâOââ) 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

J. Ostorero; H. Le Gall; M. Guillot; A. Marchand

1986-01-01

42

Terbium gallium garnet Verdet constant measurements with pulsed magnetic field  

Microsoft Academic Search

The dispersion of the Verdet constant of a single-crystal terbium gallium garnet (TGG) was measured using a pulsed magnetic field up to 70 KG. The data show a large Verdet constant for TGG throughout the visible region. The observed hysteresis effect is briefly discussed.

A. B. Villaverde; D. A. Donatti; D. G. Bozinis

1978-01-01

43

Room-temperature inverse Faraday effect in terbium gallium garnet  

Microsoft Academic Search

The inverse Faraday effect (IFE) in terbium gallium garnet (TGG) is observed at room temperature. A circularly polarized 532 nm optical pulse from a frequency doubled Nd:YAG laser traverses a TGG crystal, resulting in an induced voltage in a surrounding detection coil. Variation of laser intensity and polarization direction leads to changes in the induced voltage in accordance with Faraday’s

M. Yasin Akhtar Raja; David Allen; Wade Sisk

1995-01-01

44

Influence of Water on the Domain Structure of Epitaxy Films of Gadolinium Iron Garnet and Yttrium Iron Garnet  

Microsoft Academic Search

The effect of moisture on the magnetic domain patterns of single-crystal gadolinium iron garnet and yttrium iron garnet was observed. The change in magnetic domain structure and the disappearance of magnetic ``bubble'' domains is related to a reduction of surface stresses by water.

H. Lessoff; P. J. Coane; T. E. Everhart; H. Kanter; C. Wells

1971-01-01

45

Observation of dark dot splitting pattern in terbium gallium garnet  

Microsoft Academic Search

.   We have observed a new polarisation pattern in terbium gallium garnet which is both laser excited and mechanically stressed.\\u000a The pattern can be characterized by a splitting from a “one dot” structure to a “two dots” structure. We have found that the\\u000a new pattern is very sensitive to the orientation and the strength of the external forces applied to

X. Chen; A. Savary

1999-01-01

46

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

47

Observation of dark dot splitting pattern in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

We have observed a new polarisation pattern in terbium gallium garnet which is both laser excited and mechanically stressed. The pattern can be characterized by a splitting from a ``one dot'' structure to a ``two dots'' structure. We have found that the new pattern is very sensitive to the orientation and the strength of the external forces applied to the sample. Thanks to this sensitivity and to the image simplicity, this new effect may be used in a vectorial force sensor and actuator.

Chen, X.

48

Room-temperature inverse Faraday effect in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

The inverse Faraday effect (IFE) in terbium gallium garnet (TGG) is observed at room temperature. A circularly polarized 532 nm optical pulse from a frequency doubled Nd:YAG laser traverses a TGG crystal, resulting in an induced voltage in a surrounding detection coil. Variation of laser intensity and polarization direction leads to changes in the induced voltage in accordance with Faraday's law of induction. The IFE is attributed to the optical Stark effect.

Raja, M. Yasin Akhtar; Allen, David; Sisk, Wade

1995-10-01

49

Low-temperature thermal conductivity of terbium-gallium garnet  

Microsoft Academic Search

Thermal conductivity of paramagnetic Tb3Ga5O12 (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to\\u000a 3.25 T. A minimum is observed in the temperature dependence ?(T) of thermal conductivity at T\\u000a min = 0.52 K. This and other singularities on the ?(T) dependence are associated with scattering of phonons from terbium

A. V. Inyushkin; A. N. Taldenkov

2010-01-01

50

The magnetic susceptibilities of some rare-earth garnets  

Microsoft Academic Search

Measurements of the magnetic susceptibilities of gadolinium, terbium, dysprosium, holmium and erbium gallium garnet and of terbium and holmium aluminium garnet have been made between 0.6 °K and 4 2 °K. Antiferromagnetic transitions have been observed at 1.35 °K for terbium aluminium garnet, at 0.8 °K for holmium aluminium garnet and at 0.8 °K for erbium gallium garnet. The results

A H Cooke; T L Thorp; M R Wells

1967-01-01

51

Growth of Uniaxial Magnetic Garnet Films by a Simplified Method of Chemical Vapor Deposition  

Microsoft Academic Search

Epitaxial films of gallium-substituted yttrium iron garnet displaying magnetic domains have been grown on gadolinium gallium garnet and mixed gadolinium dysprosium gallium garnet substrates. The films grown on Dy: GGG were crack-free. A chemical-vapor-deposition (CVD) system using metal source materials and a simplified geometry was developed. Investigations were made of several different types of growth which occurred and of the

R. C. Taylor; V. Sadagopan

1971-01-01

52

Sol-gel synthesis and characterization of yttrium gallium garnets  

NASA Astrophysics Data System (ADS)

Precursor powders for yttrium gallium garnet (Y3Ga5O12, YGG) were prepared by a simple sol-gel method based on the formation of metal chelates in aqueous solvents. A systematic study of sol-gel technique synthesized YGG samples is presented using different complexing agents. Six high-purity organic substances were used as complexing agents, namely, tartaric acid, 1,2-ethanediol, citric acid, ethylene diamine tetra-acetic acid (EDTA), malonic acid, and oxalic acid. These agents were found to influence the characteristics of the end products, in particular their homogeneity. The phase purity, composition, and microstructure of the polycrystalline samples were studied by thermoanalytical methods (TGADTA), x-ray diffraction (XRD) analysis, IR spectroscopy, and scanning electron microscopy (SEM). From the typical XRD patterns of different synthesis products it is concluded that only the use tartaric acid, 1,2-ethanediol, citric acid, and EDTA yields a single YGG phase.

Leleckaite, Asta; Urbonaite, Sigita; Tõnsuaadu, Kaia; Kareiva, Aivaras

2005-08-01

53

Behavior of the Residual Magnetizations of Ferrite-Gadolinium Garnet Sublattices near the Compensation Temperature  

Microsoft Academic Search

It is demonstrated by the Mössbauer spectroscopy method that the residual magnetizations of ferrite-gadolinium garnet sublattices anomalously increase near the compensation temperature. Anomalies for a single-crystal sample are observed in a narrower temperature interval than for a polycrystalline sample. The detected phenomenon is explained by the rearrangement of the ferrite domain structure near the compensation temperature.

Sh. M. Aliev; I. K. Kamilov; M. M. Guseinov; Sh. O. Shakhshaev; A. Kh. Abduev

2004-01-01

54

Exchange Resonances in Gadolinium Iron Garnet near the Magnetic Compensation Temperature  

Microsoft Academic Search

The theory of ferrimagnetic resonance in a system of two sublattices is reviewed with emphasis upon the behavior near the compensation point. Experimental studies have been made on the gadolinium-iron garnet system in a temperature region of about 30°C which included the compensation point. The “normal” and “exchange” modes were observed and their field dependence upon temperature above and below

S. Geschwind; L. R. Walker

1959-01-01

55

Low-temperature thermal conductivity of terbium-gallium garnet  

SciTech Connect

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

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

2010-11-15

56

Low-temperature thermal conductivity of terbium-gallium garnet  

NASA Astrophysics Data System (ADS)

Thermal conductivity of paramagnetic Tb3Ga5O12 (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence ?( T) of thermal conductivity at T min = 0.52 K. This and other singularities on the ?( T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb3+ ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb3+ ion.

Inyushkin, A. V.; Taldenkov, A. N.

2010-11-01

57

Magnetic garnet film epitaxy on nonsingular faces (abstract)  

Microsoft Academic Search

The single crystal films of magnetic garnets are widely used in various microelectronics devices. The yttrium–iron and bismuth–gallium-substituted magnetic garnet films were grown by liquid phase epitaxy from supercooled solutions on the basis PbO+B2O3. As substrates for films the gadolinium–gallium garnet wafers crystallographically oriented in the range from (111)- to (110)-directions are used. In experiments such growth process parameters as

S. S. Gorelik; L. M. Letyuk; A. T. Morchenko

1996-01-01

58

Electronic Raman scattering from terbium gallium garnet excited with a picosecond laser  

NASA Astrophysics Data System (ADS)

The electronic Raman (ER) spectrum of terbium gallium garnet, recorded using picosecond radiation from the frequency-doubled output of a Nd:YAG laser is reported. The observed spectral bands with frequency shifts up to 6000 cm-1 are the result of the effect of a strong crystal field which causes J-mixing between the 7F 6,5,....,0 states. The site symmetry of Tb 3+ in the garnet can be confirmed from this spectroscopy.

Koningstein, J. A.; Lemaire, H.; Atkinson, G. H.

1987-09-01

59

Luminescence Properties of Praseodymium Doped Gadolinium Gallium Garnet (GGG) Nanocrystals  

Microsoft Academic Search

Significant strides have been achieved in recent years in the field of luminescence especially in the nanocrystalline domain. Nanocrystalline particles are of great interest as their optical properties can be varied greatly by tailoring the particle size. Rare-earths represent highly interesting dopant ions due to their intensely luminescent f-f electronic transitions. Praseodymium, in particular, can be employed as a probe

Rafik Naccache; Fiorenzo Vetrone; John-Christopher Boyer; John A. Capobianco; Adolfo Speghini; Marco Bettinelli

2004-01-01

60

Remanent magnetizations of gadolinium iron garnet sublattices near the compensation point  

NASA Astrophysics Data System (ADS)

Gadolinium iron garnet Gd3Fe5O12 has been studied near the compensation point T cm by Mössbauer spectroscopy. It has been shown that the remanent magnetizations of the ferrite sublattices abruptly increase near T cm. The phenomenon has been explained by the increase in the domain sizes in the ferrite with approaching T cm. The Mössbauer spectroscopy can be used to investigate the magnetization and magnetization reversal processes in individual sublattices of a ferrimagnet.

Aliev, Sh. M.; Kamilov, I. K.; Aliev, M. Sh.; Ibaev, Zh. G.

2014-06-01

61

Magnetic and magneto-optical properties of bismuth-substituted gadolinium iron garnets  

NASA Astrophysics Data System (ADS)

The Faraday Rotation (FR) and the magnetic properties of single crystals Gadolinium-Bismuth Iron Garnets are investigated in the temperature range covering the magnetic ordering domain. The temperature and Bi content dependences of FR are reported at 1. 15 micron wavelength. These results are compared to the FR induced by lighter rare earth (Ce Nd Pr) substitutions. At room temperature a large increasing of the M. O. efficiency is observed. I -

Guillot, M.; Le Gall, H.; Artinian, M.

1990-08-01

62

Self-focusing in Terbium Gallium Garnet using Z-scan  

Microsoft Academic Search

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

X. Chen; B. Lavorel; T. Dreier; N. Genetier; H. Misserey; X. Michaut

1998-01-01

63

Terbium gallium garnet for high average power Faraday isolators: modern aspects of growing and characterization  

Microsoft Academic Search

The growth and characterization of terbium gallium garnet (TGG) for high average Faraday isolators is reported. The main technique of TGG single crystals growing is Czochralski method. Key physical parameters of the grown crystals are measured: thermal conductivity, heat capacity, thermal expansion coefficient, refractive index thermal dependence, optical damage threshold and spectral function of Verdet constant.

I. Ivanov; A. Bulkanov; E. Khazanov; I. Mukhin; O. Palashov; V. Tsvetkov; P. Popov

2009-01-01

64

Rare earth scandium garnet - Materials science aspects  

NASA Astrophysics Data System (ADS)

The paper is concerned with various aspects of the crystal chemistry, structure, and growth of rare earth scandium garnets. Results of a precision X-ray diffraction analysis of gadolinium-scandium-gallium garnet are presented, and the structure and population of crystallographic sites are discussed as a function of the initial composition and isomorphic substitution. Particular attention is given to those properties of rare earth scandium garnets which significantly affect the growth of single crystals of these compounds.

Zharikov, E. V.

65

Iron whisker domain patterns imaged by garnet films  

Microsoft Academic Search

Bismuth doped yttrium iron garnet thin films formed on the surfaces of a gadolinium gallium garnet substrate are used as magneto-optical indicators for quantitative studies of the micromagnetics of an iron whisker. The method does not require image processing. A field applied perpendicular to the whisker axis splits a 180° domain wall into two 90° sections slightly separated by a

J.-G. Lee; S. A. Govorkov; A. S. Arrott

1996-01-01

66

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.

Chen, X.; Lavorel, B.; Dreier, T.; Genetier, N.; Misserey, H.; Michaut, X.

67

Self-focusing in Terbium Gallium Garnet using Z-scan  

Microsoft Academic Search

When illuminated near its resonance with an Ar ion laser beam (lambda=488 nm), laser induced thermal self-focusing is observed in Terbium Gallium Garnet. The crystal exhibits a strong intensity dependent refractive index change Deltan. The Z-scan technique is used to study the beam waist change due to Deltan. The refractive index is found to be well described by a quadratic

Chen Lavorel; Dreier Genetier; Misserey Michaut

1998-01-01

68

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

69

Erbium, chromium:yttrium–scandium–gallium–garnet laser-assisted sinus graft procedure  

Microsoft Academic Search

The possibility of using lasers in the field of dentistry has been a subject of investigation. There are few reports that\\u000a any laser systems have been used for bony window osteotomy by direct sinus grafting. In this study, erbium, chromium:yttrium–scandium–gallium–garnet\\u000a (Er,Cr:YSGG) laser of various laser systems was used for 12 sinus bone grafts in ten patients, and the efficiency of

Dong-Seok Sohn; Ji-Soo Lee; Kyung-Mi An; George E. Romanos

2009-01-01

70

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

71

Ultrafast inverse Faraday effect in a paramagnetic terbium gallium garnet crystal  

NASA Astrophysics Data System (ADS)

Conventional wisdom dictates that magneto-optical and optomagnetic phenomena are reciprocal and of equal strength. We test this assumption in a pump-probe experimental study of the ultrafast inverse Faraday effect in a terbium gallium garnet crystal. The thorough quantitative analysis of the observed polarization response unambiguously demonstrates a remarkable discrepancy of several orders of magnitude between the strengths of the direct and the inverse effects. This finding further questions the validity of standard magnetic models relying on the use of the static Verdet constant on subpicosecond time scales.

Mikhaylovskiy, R. V.; Hendry, E.; Kruglyak, V. V.

2012-09-01

72

Optical properties and Faraday effect of ceramic terbium gallium garnet for a room temperature Faraday rotator  

NASA Astrophysics Data System (ADS)

The optical properties, Faraday effect and Verdet constant of ceramic terbium gallium garnet (TGG) have been measured at 1064 nm, and were found to be similar to those of single crystal TGG at room temperature. Observed optical characteristics, laser induced bulk-damage threshold and optical scattering properties of ceramic TGG were compared with those of single crystal TGG. Ceramic TGG is a promising Faraday material for high-average-power YAG lasers, Yb fiber lasers and high-peak power glass lasers for inertial fusion energy drivers.

Yoshida, Hidetsugu; Tsubakimoto, Koji; Fujimoto, Yasushi; Mikami, Katsuhiro; Fujita, Hisanori; Miyanaga, Noriaki; Nozawa, Hoshiteru; Yagi, Hideki; Yanagitani, Takagimi; Nagata, Yutaka; Kinoshita, Hiroo

2011-08-01

73

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

74

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

Microsoft Academic Search

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

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

2001-01-01

75

Room temperature magnetoelectric control of micromagnetic structure in iron garnet films  

Microsoft Academic Search

The effect of magnetic domain wall motion induced by electric field is observed in epitaxial iron garnet films grown on (210) and (110) gadolinium-gallium garnet substrates. The displacement of the domain wall changes to the opposite at the reversal of electric field polarity, and it is independent of the magnetic polarity of the domains. Dynamic observation of the domain wall

A. S. Logginov; G. A. Meshkov; A. V. Nikolaev; E. P. Nikolaeva; A. P. Pyatakov; A. K. Zvezdin

2008-01-01

76

Electric Field Induced Transformation of Magnetic Domain Structure in Magnetoelectric Iron Garnet Films  

Microsoft Academic Search

The room temperature magnetoelectric effect was observed in epitaxial iron garnet films that appeared as magnetic domain wall motion induced by electric field. The films grown on gadolinium-gallium garnet substrates with various crystallographic orientations were examined. The effect was observed in (210) and (110) films and was not observed in (111) films. Dynamic observation of the domain wall motion in

A. P. Pyatakov; A. V. Nikolaev; G. A. Meshkov; E. P. Nikolaeva; A. S. Logginov; A. K. Zvezdin

2008-01-01

77

Optical rotary power at the resonance of the Terbium 7F 6 ? 5D 4 line in Terbium Gallium Garnet  

Microsoft Academic Search

The Tb3+ absorption line 7F6?5D4 of the Terbium Gallium Garnet crystal is excited with an Argon ion laser. The Verdet's constant has been determined and reported against 1\\/?2, showing no significant resonant behaviour at absorption resonance. The utility and the constraints of the crystal at this particular resonant wavelength are pointed out.

X. Chen; B. Lavorel; J. P. Boquillon; R. Saint-Loup; M. Jannin

1998-01-01

78

Optical rotary power at the resonance of the Terbium 7F 6? 5D 4 line in Terbium Gallium Garnet  

NASA Astrophysics Data System (ADS)

The Tb 3+ absorption line 7F 6? 5D 4 of the Terbium Gallium Garnet crystal is excited with an Argon ion laser. The Verdet's constant has been determined and reported against 1/ ?2, showing no significant resonant behaviour at absorption resonance. The utility and the constraints of the crystal at this particular resonant wavelength are pointed out.

Chen, X.; Lavorel, B.; Boquillon, J. P.; Saint-Loup, R.; Jannin, M.

1998-09-01

79

Measurement of the magnetostriction constant of bi-doped garnets by optical observation of stress-induced stripe domains  

Microsoft Academic Search

In this paper, we report on the optical investigation of magnetic microstructures in Bi substituted garnet thin films grown by epitaxial deposition on (111)-oriented gallium gadolinium garnet substrates. The specimens are magnetically diluted with Ga ions. By using a technique based on the bending of the thin film, the appearance of a straight stripe domain pattern is observed. The changes

I. Nistor; C. Krafft; R. Rojas; I. D. Mayergoyz

2004-01-01

80

A wideband electronically tunable microwave notch filter in yttrium iron garnet-gallium arsenide material structure  

NASA Astrophysics Data System (ADS)

A wideband electronically tunable microwave notch (band-stop) filter has been constructed in an yttrium iron garnet (YIG)/gallium arsenide (GaAs) material structure. An incident microwave propagating along the microstrip transmission line in the GaAs substrate is coupled into and to excite the magnetostatic surface waves in the YIG layer, which is laid upon the microstrip transmission line. Maximum coupling and thus the peak absorption of the output microwave power occur at the ferromagnetic resonance frequency in the YIG film as determined by a bias magnetic field. A tuning range as large as 2.5-23.0 GHz in the peak absorption frequency with the corresponding magnetic field tuning range of 290-7300 Oe has been accomplished. Peak absorption of 15-38 dB in the microwave output power has also been measured.

Tsai, Chen S.; Su, Jun

1999-04-01

81

Low-temperature time-domain terahertz spectroscopy of terbium gallium garnet crystals  

NASA Astrophysics Data System (ADS)

We report an experimental observation of high frequency magnetic excitations in terbium gallium garnet crystals using terahertz time-domain spectroscopy. We show that precessional modes of terbium magnetic sublattices can be excited by a magnetic field of a terahertz broadband pulse. We study and discuss the dependence of the observed resonances upon the temperature and the strength and orientation of the bias magnetic field. The behavior of the observed magnetic modes is in agreement with the theory of paramagnetic resonance in the multisublattice system. We also show that the illumination of the crystal with intense optical pulses destroys the magnetic ordering. Our results demonstrate that the time-domain terahertz spectroscopy can be a powerful tool by which to study high frequency properties of dielectric magnetic materials, with perceived extensions to studies in femtomagnetism and magnonics.

Mikhaylovskiy, R. V.; Hendry, E.; Ogrin, F. Y.; Kruglyak, V. V.

2013-03-01

82

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

Microsoft Academic Search

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

Hideo Kidoh; Hideyuki Yashima; Akiharu Morimoto; Tatsuo Shimizu

1994-01-01

83

Efficient eye-safe neodymium doped composite yttrium gallium garnet crystal laser.  

PubMed

We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 ?m with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 ?m was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 ?J, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers. PMID:24690782

Yu, Haohai; Wang, Shuxian; Han, Shuo; Wu, Kui; Su, Liangbi; Zhang, Huaijin; Wang, Zhengping; Xu, Jun; Wang, Jiyang

2014-03-15

84

Epitaxial liftoff of thin oxide layers: Yttrium iron garnets onto GaAs  

NASA Astrophysics Data System (ADS)

We report on the implementation of epitaxial liftoff in magnetic garnets. Deep-ion implantation is used to create a buried sacrificial layer in single-crystal yttrium iron garnet (YIG) and bismuth-substituted YIG epilayers grown on gadolinium gallium garnet. The damage generated by the implantation induces a large etch selectivity between the sacrificial layer and the rest of the garnet. 10-?m-thick films of excellent quality are lifted off and bonded to silicon and GaAs substrates. No noticeable degradation in magnetic coercivity due to domain pinning is observed. Stress-induced microfracturing in the thin oxide layers is also addressed.

Levy, M.; Osgood, R. M., Jr.; Kumar, A.; Bakhru, H.

1997-11-01

85

High-frequency domain wall excitations in magnetic garnet films with in-plane magnetization  

Microsoft Academic Search

Magnetic garnet films of compositions (YBi)3Fe5O12 and (LuBi)3Fe5O12 are grown by liquid-phase epitaxy on [110]- and [100]-oriented substrates of gadolinium gallium garnet, respectively. All films have in-plane magnetization. 180° and 90° domain walls in these films are studied by microwave technique. In addition to the known low-frequency mode of wall translation new multiple resonant modes of both 90° and 180°

V. T. Synogach; H. Doetsch

1996-01-01

86

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

Microsoft Academic Search

The magnetic behavior and domain structure of Fe films grown on yttrium-iron-garnet (YIG) underlayers were studied to elucidate their interlayer coupling, as a function of the Fe layer thickness, using magnetic force microscopy (MFM) and magneto-optic Kerr effect (MOKE). The YIG layer, grown by liquid phase epitaxy on single crystal gadolinium-gallium-garnet (GGG) substrates, showed a characteristic stripe domain structure in

Y. S. Chun; Kannan M. Krishnan

2004-01-01

87

High-frequency excitations of stripe-domain lattices in magnetic garnet films  

Microsoft Academic Search

Magnetic garnet films of composition (Y,Bi)3(Fe,Al)5O12 have been grown by liquid phase epitaxy on [111] and [110] oriented substrates of gadolinium gallium garnet. The domain wall resonance and the two branches of the domain resonance of periodic stripe domains are measured as function of the bias induction applied in the film plane parallel to the stripes. Resonance frequencies up to

B. Lührmann; H. Dötsch; S. Sure

1993-01-01

88

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

Microsoft Academic Search

The magnetic behavior and domain structure of Fe films grown on yttrium–iron–garnet (YIG) underlayers were studied to elucidate their interlayer coupling, as a function of the Fe layer thickness, using magnetic force microscopy (MFM) and magneto-optic Kerr effect (MOKE). The YIG layer, grown by liquid phase epitaxy on single crystal gadolinium–gallium–garnet (GGG) substrates, showed a characteristic stripe domain structure in

Y. S. Chun; Kannan M. Krishnan

2004-01-01

89

Epitaxial growth of terbium iron garnet thin films with out-of-plane axis of magnetization  

Microsoft Academic Search

We fabricate epitaxial terbium iron garnet (Tb3Fe5O12, TbIG) thin films on (110) gadolinium gallium garnet (Gd3Ga5O12, GGG) substrates using a pulsed laser deposition technique. High quality (110) oriented epitaxial growth of TbIG thin films has been revealed by ?–2? scans, ?-scans, rocking curves (?-scans), and reciprocal space mapping in high resolution X-ray diffraction. Magnetic and magneto-optic hysteresis loops, however, demonstrate

Naresh Kumar; N. G. Kim; Y. A. Park; N. Hur; J. H. Jung; K. J. Han; K. J. Yee

2008-01-01

90

Magnetic and fluorescence properties of cerium-doped yttrium gadolinium aluminum iron garnet crystals  

NASA Astrophysics Data System (ADS)

Magnetic and fluorescence properties of chemically synthesized Ce:Gd-YAIG (Ce0.05GdxY2.95?xAl5?yFeyO12) nanocrystals have been investigated. The structural characterization by X-ray diffraction (XRD) shows that a garnet phase has been identified in samples with 0 ? x ? 2.95 and 0 ? y ? 3.0. When y = 0, only garnet peaks are observed for 0 ? x ? 2.5, while both garnet and perovskite phases are present for x > 2.5. It is found from XRD Rietveld analyses that the site occupancy of Fe3+ at the tetrahedral and octahedral sites in the garnet is independent of the amount of Y3+ substituted by Ce3+ and Gd3+ at the dodecahedral sites. The saturation magnetization for the sample with x = 0 and y = 3.0 is 4.35 emu/g, while that with x = 2.5 and y = 3.0 is 87.5 emu/g. When the Fe3+ composition y is varied from 0 to 3.0 at x = 2.5, the intensity of fluorescence at the emission wavelength ?570 nm significantly decreases presumably due to absorption by Fe3+ that is increased in the crystal.

Aoki, Daichi; Shima, Mutsuhiro

2014-11-01

91

Features of the electron structure of gadolinium-scandium-gallium garnet  

NASA Astrophysics Data System (ADS)

Results of a high-precision X-ray diffraction study of a GSGG single crystal grown from a melt of Gd3Sc(1.6)Ga(3.4)O12 composition are presented. Particular attention is given to delta-rho distribution in GSGG, and it is found that the observed features of delta-rho can be explained by a linear combination of f and d wave functions.

Voloshina, I. V.; Tsirel'Son, V. G.; Zharikov, E. V.; Gerr, R. G.; Antipin, M. Iu.

92

Prospects for a new search for the electron electric-dipole moment in solid gadolinium-iron-garnet ceramics  

NASA Astrophysics Data System (ADS)

We address a number of issues regarding solid-state electron electric-dipole moment (EDM) experiments, focusing on gadolinium-iron garnet [(GdIG) chemical formula Gd3Fe5O12 ] as a possible sample material. GdIG maintains its high magnetic susceptibility down to 4.2 K, which enhances the EDM-induced magnetization of a sample placed in an electric field. We estimate that lattice polarizability gives rise to an EDM enhancement factor of approximately 20. We also calculate the effect of the demagnetizing field for various sample geometries and permeabilities. Measurements of intrinsic GdIG magnetization noise are presented, and the fluctuation-dissipation theorem is used to compare our data with the measurements of the imaginary part of GdIG permeability at 4.2 K, showing good agreement above frequencies of a few hertz. We also observe how the demagnetizing field suppresses the noise-induced magnetic flux, confirming our calculations. The statistical sensitivity of an EDM search based on a solid GdIG sample is estimated to be on the same level as the present experimental limit. Such a measurement would be valuable given the completely different methods and systematics involved. The most significant systematics in such an experiment are the magnetic hysteresis and the magnetoelectric effect. Our analysis shows that it should be possible to control these at the level of statistical sensitivity.

Sushkov, A. O.; Eckel, S.; Lamoreaux, S. K.

2009-02-01

93

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

NASA Astrophysics Data System (ADS)

We present a comprehensive and systematic investigation of the fundamental physical limitations of Faraday isolation performance at high average powers that are due to thermally induced birefringence. First, the operation of various Faraday isolator designs by use of arbitrary orientation of cubic magneto-optic crystals is studied theoretically. It is shown that, for different Faraday isolator designs, different crystal orientations can optimize the isolation ratio. Second, thermo-optic and photoelastic constants for terbium gallium garnet crystals grown by different manufacturers were measured. Measurements of self-induced depolarization are made for various orientations of crystallographic axes. The measurements are in good agreement with our theoretical predictions. Based on our results, it is possible to select a crystal orientation that optimizes isolation performance at high average powers, resulting in a 5-dB enhancement over nonoptimized orientations.

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

2002-01-01

94

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

95

Faraday rotation and the magnetocaloric effect in the Tb 3 Ga 5 O 12 terbium gallium garnet at low temperatures in strong magnetic fields  

Microsoft Academic Search

The magnetocaloric effect and the Faraday rotation in a paramagnetic cubic crystal of terbium gallium garnet in strong magnetic\\u000a fields oriented along different crystallographic directions are calculated theoretically. It is demonstrated that, in strong\\u000a magnetic fields, the magnetocaloric effect and the Faraday effect are characterized by strong anisotropy, which disappears\\u000a in weak magnetic fields.

V. I. Plis; A. I. Popov

2004-01-01

96

The effect of erbium, chromium:yttrium–scandium–gallium–garnet laser etching on marginal integrity of a resin-based fissure sealant in primary teeth  

Microsoft Academic Search

The aim of this in vitro study was to evaluate the effect of erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG)\\u000a laser pretreatment alone, or associated with acid etching, on the quality of marginal integrity (microleakage and marginal\\u000a gap) of a resin-based fissure sealant in primary teeth. Fifty sound primary molar teeth were randomly assigned to one of five\\u000a study groups, pretreated as follows: (1)

Elif Sungurtekin; Nurhan Özta?

2010-01-01

97

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

NASA Astrophysics Data System (ADS)

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

Mosca, S.; Canuel, B.; Karimi, E.; Piccirillo, B.; Marrucci, L.; de Rosa, R.; Genin, E.; Milano, L.; Santamato, E.

2010-10-01

98

High-pressure and high-temperature studies on oxide garnets  

NASA Astrophysics Data System (ADS)

We report high-pressure and high-temperature studies on a series of oxide garnets of chemical composition A3B2C3O12. The members of this family investigated are gadolinium scandium gallium garnet (GSGG), gadolinium gallium garnet (GGG), and yttrium aluminum garnet (YAG). The GSGG and GGG are doped with both neodymium and chromium while the YAG is doped only with neodymium. Photoluminescence, synchrotron x-ray-diffraction, and laser heating studies were carried out in a diamond-anvil cell. Variety of optical sensors (ruby, Sm-doped YAG) and x-ray pressure marker (copper) were employed for pressure measurement. Pressure-induced amorphization was observed in GSGG at 58+/-3 GPa and GGG at 84+/-4 GPa by x-ray-diffraction studies. The photoluminescence studies show only gradual broadening of emission bands through the amorphization transition. On increasing pressure beyond amorphization, very broad and featureless emission bands were observed in the fluorescence spectra at 77+/-2 GPa for GSGG and at 88+/-2 GPa for GGG. Laser heating of the pressure-induced amorphous phase in GSGG caused recrystallization to the stable cubic phase. High-pressure x-ray study on YAG shows that it retains cubic phase up to 101+/-4 GPa. A pressure-volume relation for each member of the oxide garnet at ambient temperatures is presented, structural transformation mechanisms, and application of oxide garnets as pressure sensors are also discussed.

Hua, Hong; Mirov, Sergey; Vohra, Yogesh K.

1996-09-01

99

Edge-cladding glasses for solid-state laser garnet crystals  

NASA Astrophysics Data System (ADS)

A range of glass compositions has been identified in the PbO-Bi2O3-CuO-Al2O3-SiO2 system which will be applied as absorbent claddings to Nd(3+) and Cr(3+) codoped gadolinium scandium gallium garnet and Nd(3+)-doped gadolinium gallium garnet crystal slabs for high-power laser applications. Coefficients of thermal expansion and refractive indices at 1.06 microns of the cladding match those of the crystals. Absorption coefficients are between 30 and 40/cm. Estimates of stress birefringence in the crystalline medium indicate that values below 10 nm/cm are achievable with cladding layers of 1-mm thickness and crystal slabs of 50-100-mm width.

Meissner, H. E.; Toratani, H.; Izumitani, T.; Stokowski, S. E.

1987-10-01

100

Gain in pulsed x-ray irradiated Cr,Nd:GdScGa-garnet  

NASA Astrophysics Data System (ADS)

The transmission properties of gadolinium scandium gallium garnet doped with chromium and neodymium have been studied during and after a 20 ns high-energy x-ray pulse. Gain is observed in the transmission which indicates a small signal gain of 0.175/cm. About 5% of the absorbed dose is converted to inversion, which is comparable to flash-lamp-pumped inversion. The small signal gain scales with dose.

Brannon, P. J.

1995-01-01

101

Electric Field Induced Transformation of Magnetic Domain Structure in Magnetoelectric Iron Garnet Films  

Microsoft Academic Search

The room temperature magnetoelectric effect was observed in epitaxial iron\\u000agarnet films that appeared as magnetic domain wall motion induced by electric\\u000afield. The films grown on gadolinium-gallium garnet substrates with various\\u000acrystallographic orientations were examined. The effect was observed in (210)\\u000aand (110) films and was not observed in (111) films. Dynamic observation of the\\u000adomain wall motion in

A. P. Pyatakov; G. A. Meshkov; A. V. Nikolaev; E. P. Nikolaeva; A. S. Logginov; A. K. Zvezdin

2008-01-01

102

Optical study of magnetostriction in (Bi, Ga)-substituted garnet thin films  

Microsoft Academic Search

The magnetostriction of magnetically diluted (Lu3-xBixFe5-yGayO12) (BiLuIG) thin films grown by epitaxial deposition on (111)-oriented gallium gadolinium garnet substrates was optically studied using the technique based on the bending of samples by an external applied pressure. The real-time optical observations of stripe magnetic domains and their evolution under external applied magnetic fields and applied stresses are reported. The observed changes

I. Nistor; I. D. Mayergoyz; R. Rojas; C. Krafft

2005-01-01

103

Room temperature magnetoelectric control of micromagnetic structure in iron garnet films  

NASA Astrophysics Data System (ADS)

The effect of magnetic domain wall motion induced by electric field is observed in epitaxial iron garnet films grown on (210) and (110) gadolinium-gallium garnet substrates. The displacement of the domain wall changes to the opposite at the reversal of electric field polarity, and it is independent of the magnetic polarity of the domains. Dynamic observation of the domain wall motion in 400 V electric pulses gives the domain wall velocity of about 50 m/s. The same velocity is achieved in a magnetic field pulse of about 50 Oe. This type of magnetoelectric effect is implemented in single phase material at room temperature.

Logginov, A. S.; Meshkov, G. A.; Nikolaev, A. V.; Nikolaeva, E. P.; Pyatakov, A. P.; Zvezdin, A. K.

2008-11-01

104

Crystal ion slicing of single-crystal magnetic garnet films  

NASA Astrophysics Data System (ADS)

Epitaxial liftoff has been used for achieving heterogeneous integration of many III-V and elemental semiconductor systems. However, it has been heretofore impossible to integrate devices of many other important material systems. A good example of this problem has been the integration of single-crystal transition metal oxides on semiconductor platforms, a system needed for on-chip thin film optical isolators. We report here an implementation of epitaxial liftoff in magnetic garnets. Deep ion implantation is used to create a buried sacrificial layer in single-crystal yttrium iron garnet (YIG) and bismuth-substituted YIG (Bi-YIG) epitaxial layers grown on gadolinium gallium garnet (GGG). The damage generated by the implantation induces a large etch selectivity between the sacrificial layer and the rest of the garnet. Ten-micron-thick films have been lifted off from the original GGG substrates by etching in phosphoric acid. Millimeter-size pieces of excellent quality have been transferred to the silicon and gallium arsenide substrates. Study of the magnetic domain structure in the detached epilayers by Faraday contrast shows no changes in film anisotropy. Optical insertion loss measurements are also presented.

Levy, M.; Osgood, R. M.; Kumar, A.; Bakhru, H.

1998-06-01

105

Low-temperature synthesis and characterization of yttrium-gallium garnet Y{sub 3}Ga{sub 5}O{sub 12} (YGG)  

SciTech Connect

To obtain yttrium-gallium garnet (Y{sub 3}Ga{sub 5}O{sub 12}, YGG) a simple 'chimie douce' method has been developed. This sol-gel method yielded excellent starting gel precursor for the fabrication of YGG phase, which could be used as host material for optical applications. The pattern of X-ray diffraction analysis of the ceramic sample sintered for 10 h at 1000 deg. C showed the formation of monophasic Y{sub 3}Ga{sub 5}O{sub 12} phase. The phase transformations, composition and micro-structural features in the gels and polycrystalline sample were studied by thermoanalytical methods (TGA/DTA), powder X-ray diffraction analysis (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The quality of the resulting products (homogeneity, crystallisation temperature, grain size, grain size distribution, etc.) is discussed.

Mathur, Sanjay [Leibniz Institute of New Materials, CVD Division, Im Stadtwald, D-66123 Saarbruecken (Germany); Shen Hao [Leibniz Institute of New Materials, CVD Division, Im Stadtwald, D-66123 Saarbruecken (Germany); Leleckaite, Asta [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03011 Vilnius (Lithuania); Beganskiene, Aldona [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03011 Vilnius (Lithuania); Kareiva, Aivaras [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03011 Vilnius (Lithuania)]. E-mail: aivaras.kareiva@chf.vu.lt

2005-03-08

106

Mode-locking in a neodymium laser with a shutter made of gadolinium-scandium-gallium garnet  

NASA Astrophysics Data System (ADS)

The mode-locking regime of a neodymium laser using shutters made of GSGG crystals is studied. With a GSGG transmission coefficient of 20 percent and a crystal length of 1 cm, ultrashort pulses with a minimum duration of 80 ns and an energy of 0.5 mJ are generated. It is shown that GSGG crystals can be used successfully as passive shutters for mode-locking in the NIR range (lambda = 1.06 microns). The advantages of these shutters over those utilizing polymethine dyes are discussed.

Demchuk, M. I.; Zharikov, E. V.; Zabaznov, A. M.; Manichev, I. A.; Mikhailov, V. P.

1987-02-01

107

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

PubMed

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

Seelert, W; Strauss, E

1987-10-01

108

BRIEF COMMUNICATIONS: Gadolinium scandium gallium garnet (GSGG:Cr:Nd) laser with a high specific output energy  

NASA Astrophysics Data System (ADS)

A comparison was made of different active materials such as GSGG:Cr:Nd, GSAG:Cr:Nd, YA:Nd, and YAG:Nd from the point of view of the attainable specific output energy. The best result, 150 W/cm3, was obtained for a GSGG:Cr:Nd active element 3 mm in diameter and 50 mm long.

Ostroumov, V. G.; Shcherbakov, Ivan A.

1989-12-01

109

Preparation of Nd-doped gadolinium-gallium garnet laser ceramic powder by sol-gel method  

NASA Astrophysics Data System (ADS)

Preparation of Nd3+: Gd3 Ga5 O12 polycrystalline material by sol-gel method was preparated in this paper. The structure and the pattern of the sample were analyzed by thermogravimetric analysis and differential thermal analysis (TG-DTA), Infrared spectrum, XRD, TEM and electron spectrum, which indicated that the powder with good characteristics of 70-100 nm can be obtained by sintering at 1 000°C. It was shown that the chemical composition of the sample was agreed with experimental requirements by electron spectrum analysis.

Yao, Yan-Ping; Liu, Jing-He

2006-07-01

110

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

PubMed

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

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

2013-01-01

111

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. PMID:24966726

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

2013-01-01

112

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

113

Mode locking in Nd-laser by means of Gd-Sc-Ga-garnet shutter  

NASA Astrophysics Data System (ADS)

The mode-locking regime of a neodymium laser using shutters made of GSGG (gadolinium scandium gallium garnet) crystals is studied. With a GSGG transmission coefficient of 20 percent and a crystal length of 1 cm, ultrashort pulses with a minimum duration of 80 ns and an energy of 0.5 mJ are generated. It is shown that GSGG crystals can be used successfully as passive shutters for mode-locking in the NIR range (lambda = 1.06 microns). The advantages of these shutters over those utilizing polymethine dyes are discussed.

Demchuk, M. I.; Zharikov, Ye. V.; Zabaznov, A. M.; Manichev, I. A.; Mikhaylov, V. P.; Prokhorov, A. M.; Shkadarevich, A. P.; Chernyakovskiy, A. F.; Shcherbakov, I. A.; Yumashev, K. V.

1987-10-01

114

Wideband tunable microwave devices using ferromagnetic film-gallium arsenide material structures  

NASA Astrophysics Data System (ADS)

Yittrium iron garnet (YIG)-gadolinium gallium garnet (GGG) and iron (Fe)-gallium arsenide (GaAs) layer structures have been used, respectively, to construct wideband tunable microwave bandstop filters of the flip-chip type and the integrated type. For the former, a frequency tuning range of 2.5-23.0 GHz was accomplished at a magnetic field tuning range of 290-7300 Oe. For the latter, a comparable tuning bandwidth but of significantly higher carrier frequencies of 10.7-32.5 GHz has been achieved at a much lower magnetic field tuning range, namely, 0-4500 Oe. The advantages associated with the Fe-film-based bandstop filters should also accompany other analog microwave devices.

Tsai, Chen S.

2000-01-01

115

Treatment outcome following use of the erbium, chromium:yttrium, scandium, gallium, garnet laser in the non-surgical management of peri-implantitis: a case series.  

PubMed

Aim To date there is no consensus on the appropriate usage of lasers in the management of peri-implantitis. Our aim was to conduct a retrospective clinical analysis of a case series of implants treated using an erbium, chromium:yttrium, scandium, gallium, garnet laser.Materials and methods Twenty-eight implants with peri-implantitis in 11 patients were treated with an Er,Cr:YSGG laser (68 sites >4 mm), using a 14 mm, 500 ?m diameter, 60° (85%) radial firing tip (1.5 W, 30 Hz, short (140 ?s) pulse, 50 mJ/pulse, 50% water, 40% air). Probing depths were recorded at baseline after 2 months and 6 months, along with the presence of bleeding on probing.Results The age range was 27-69 years (mean 55.9); mean pocket depth at baseline was 6.64 ± SD 1.48 mm (range 5-12 mm),with a mean residual depth of 3.29 ± 1.02 mm (range 1-6 mm) after 2 months, and 2.97 ± 0.7 mm (range 1-9 mm) at 6 months. Reductions from baseline to both 2 and 6 months were highly statistically significant (P <0.001). Patient level reduction in bleeding from baseline to both 2 and 6 months were statistically significant (P <0.001).Conclusion In view of the positive findings in this pilot study, well-designed randomised controlled trials of the use of Er,Cr:YSGG laser in the non-surgical management of peri-implantitis are required to validate our clinical findings. PMID:25342356

Al-Falaki, R; Cronshaw, M; Hughes, F J

2014-10-24

116

Erbium, chromium:yttrium scandium gallium garnet laser for caries removal: influence on bonding of a self-etching adhesive system.  

PubMed

This study evaluated the influence of the dental substrates obtained after the use of different caries removal techniques on bonding of a self-etching system. Forty, extracted, carious, human molars were ground to expose flat surfaces containing caries-infected dentine surrounded by sound dentine. The caries lesions of the specimens were removed or not (control--G1) either by round steel burs and water-cooled, low speed, handpiece (G2), or by irradiation with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser (2W, 20 Hz, 35.38 J/cm(2), fiber G4 handpiece with 0.2826 mm(2), non-contact mode at a 2 mm distance, 70% air/20% water--G3) or using a chemo-mechanical method (Carisolv--G4). Caries-infected, caries-affected and sound dentines were submitted to a bonding system followed by construction of a resin-based composite crown. Hour-glass shaped samples were obtained and submitted to a micro-tensile bond test. The bond strength data were compared by analysis of variance (ANOVA), complemented by Tukey's test (P

Tachibana, Arlene; Marques, Márcia Martins; Soler, Julia Maria Pavan; Matos, Adriana Bona

2008-10-01

117

Magnetic garnet film epitaxy on nonsingular faces (abstract)  

NASA Astrophysics Data System (ADS)

The single crystal films of magnetic garnets are widely used in various microelectronics devices. The yttrium-iron and bismuth-gallium-substituted magnetic garnet films were grown by liquid phase epitaxy from supercooled solutions on the basis PbO+B2O3. As substrates for films the gadolinium-gallium garnet wafers crystallographically oriented in the range from (111)- to (110)-directions are used. In experiments such growth process parameters as supercooling temperature and angular velocity of substrate rotation were varied too. The parameters to be examined were thickness, growth rate, crystallografic, magnetic, and magnetooptical characteristics of the as-grown films. To analyze the growth process kinetics it was developed the model, including the terms (supersaturation CL-CE) of the first and second orders for description of surface crystallization reaction. The following expression was derived for epitaxial growth rate: f=D/?? [(CL-CE)+k1?+D/2k2?-? (k1?+D)2+4k2?D(CL-CE)/2k2?], where D is diffusion coefficient, ? is diffusion boundary layer thickness on the solid-liquid interface, ? is film density, CL is concentration of garnet phase in the melted solution, CE is equilibrium concentration, km is surface reaction constant (kinetic coefficient) of order m in D ?C/?x (0,t)=km[C(0,t)-CE]m. A selected parameters are given for (YBi)3(FeGa)5O12 films grown under the same conditions: Orientatio-------0°(110) 30' 2° 30' 2° 30' 7° 30' 90° (111) Growth rate, ?m/min ... 0.1 0.075 0.08 0.16 0.26 Specific Faraday rotation, deg/cm...1526 1804 1713 1439 1953 The peculiarities of domain structure and properties of obtained films are discussed.

Gorelik, S. S.; Letyuk, L. M.; Morchenko, A. T.

1996-04-01

118

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

119

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

120

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

121

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

122

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

123

Garnet polycrystals  

NASA Astrophysics Data System (ADS)

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

Whitney, Donna; Seaton, Nca

2010-05-01

124

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

SciTech Connect

The Bi{sub x}Ce{sub 3-x}Fe{sub 5}O{sub 12} (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 Y{sub 3}Fe{sub 5}O{sub 12} 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 + H{sub 2}. 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. [Department of Physics and Astronomy, 1151, Richmond Street, Western University, London, Ontario N6A 3K7 (Canada)

2012-10-15

125

Magneto-optical study of holmium iron garnet Ho3Fe5O12  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

126

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

127

Microwave phonon attenuation in rare-earth garnets: Ion-phonon interactions  

Microsoft Academic Search

Significant deviations from the behavior usual for dielectrics are observed in the ultrasonic attenuation at gigahertz frequencies in Nd, Gd, and Tb garnets and are attributed to the rare-earth ions. Relaxation of low-lying electron states by Orbach processes satisfactorily explains attenuation peaks in neodymium gallium garnet and terbium scandium aluminum garnet near 60 K. Below 20 K the attenuation in

M. Dutoit; J. C. Walling; D. S. Boudreaux

1975-01-01

128

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

129

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

130

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

NASA Astrophysics Data System (ADS)

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

Lin, Tao; Tang, Chi; Shi, Jing

2013-03-01

131

Ferrimagnetic garnet thin films: Growth, structure and some magnetic properties  

Microsoft Academic Search

Ferrimagnetic garnet films, mainly gadolinium iron garnet, were deposited on fused-quartz substrates and subsequently heat-treated. They were studied by optical microscopy, X-ray analysis, and electron microscopy. Magnetic properties were measured and domains observed by employing the Faraday magneto-optic effect. Structure and properties were found to depend on growth parameters established in the heat-treatment step. The role of chemical factors in

M. Oron; I. Barlow; W. F. Traber

1969-01-01

132

Gallium and gallium arsenide  

SciTech Connect

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

Kramer, D.

1988-01-01

133

Gallium scan  

MedlinePLUS

... material called gallium and is a type of nuclear medicine exam. A related test is gallium scan of ... Segerman D, Miles KA. Radionuclide imaging: general principles. ... Diagnostic Radiology: A Textbook of Medical Imaging . 5th ed. New ...

134

Absorption spectra and energy levels of Gd(3+), Nd(3+) and Cr(3+) in the garnet Gd3Sc2Ga3O12  

NASA Astrophysics Data System (ADS)

Absorption spectra recorded between 0.3 and 6.7 microns are reported for trivalent gadolinium, trivalent neodymium, and trivalent chromium in single-crystal gadolinium scandium gallium garnet, Gd3Sc2Ga3O12, at liquid nitrogen and room temperatures. Crystalline electric-field-split energy levels are established from data between 1,5000 and 35,000/cm for Gd3+ (4f7), Nd3+ (4f3), and Cr3+ (3d3). The Gd3+ and Nd3+ ions occupy sites having D2 point symmetry; Cr3+ ions are found primarily in sites of C3i point symmetry. A Hamiltonian consisting of Coulombic, spin-orbit, and crystalline electric-field terms, having symmetry appropriate to each ion, is diagonalized to obtain theoretic energy levels. The rms deviation between calculated and observed levels for Nd3+ (with 45 levels) is 1.7/cm, for Gd3+ (with 14 levels) is 4/cm, and for Cr3+ (with 35 levels) is 87.7/cm. A lattice sum calculation is compared with the phenomenological parameters obtained from fitting the observed energy levels.

Gruber, John B.; Hills, Marian E.; Morrison, Clyde A.; Turner, Gregory A.; Kokta, Milar R.

1988-03-01

135

A study of isomorphism in rare earth scandium-aluminum garnets  

NASA Astrophysics Data System (ADS)

The problem of determining the congruently melting composition of rare earth scandium garnets is examined in relation to the complex nature of isomorphic substitution in these systems. In particular, a procedure for determining the congruently melting composition of gadolinium-scandium-aluminum and yttrium-scandium-aluminum garnets is described whereby the melt composition during Czochralski growth is updated in consecutive steps. The crystal composition is determined from experimental values of the elementary cell parameter and hydrostatic density.

Denisov, A. L.; Zharikov, E. V.; Zagumennyi, A. I.; Kozlikin, S. N.; Lavrishchev, S. V.; Lutts, G. B.; Samoilova, S. A.

136

Absorption spectra and energy levels of Gd3+, Nd3+, and Cr3+ in the garnet Gd3Sc2Ga3O12  

NASA Astrophysics Data System (ADS)

Absorption spectra measured between 0.3 and 6.7 ?m are reported for Gd3+, Nd3+, and Cr3+ in single-crystal gadolinium scandium gallium garnet, Gd3Sc2Ga3O12, at various temperatures. Energy levels split by the crystal field are identified between 1500 and 35 000 cm-1 for Gd3+(4f7), Nd3+(4f3), and Cr3+(3d3). The rare-earth ions occupy sites of D2 point-group symmetry, and chromium ions are found primarily in sites of C3i point-group symmetry. A Hamiltonian consisting of Coulombic, spin-orbit, and crystal-field terms is diagonalized to obtain theoretical energy levels for each symmetry. Empirical crystal-field parameters Bkm were determined by fitting calculated energy levels to observed levels through a variation of the Bkm; these were compared with a lattice-sum calculation. The rms deviations between calculated and observed levels are 1.7 cm-1 for Nd3+ (45 levels), 4.0 cm-1 for Gd3+ (14 levels), and 87.7 cm-1 for Cr3+ (35 levels).

Gruber, John B.; Hills, Marian E.; Morrison, Clyde A.; Turner, Gregory A.; Kokta, Milan R.

1988-05-01

137

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

138

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

139

Thermodynamic analysis and crystal-chemical modeling of the defect structure of calcium iron garnets  

Microsoft Academic Search

This paper presents detailed analysis of the phase equilibria and thermodynamic stability of CaO, Fe2O3, Gd2O3, Nd2O3, Pr2O3, ZrO2, NiO, and ThO2, and detect formation during high-temperature synthesis of gadolinium (yttrium) calcium and zirconium calcium iron garnets\\u000a doped with praseodymium, neodymium, nickel, cerium, thorium, and other oxides. The origin of point defects in each garnet\\u000a is discussed. Crystal-chemical modeling indicates

Yu. P. Vorobiov

2006-01-01

140

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

PubMed

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

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

2002-11-20

141

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

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

142

Mineral of the month: garnet  

USGS Publications Warehouse

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

Olson, Donald

2005-01-01

143

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

144

Are gadolinium contrast agents suitable for gadolinium neutron capture therapy?  

E-print Network

Are gadolinium contrast agents suitable for gadolinium neutron capture therapy? Gelsomina De Stasio Sacro Cuore, Largo A. Gemelli 8, I-00168 Roma, Italy Objective: Gadolinium neutron capture therapy (Gd compound; (2) tumor irradiation with thermal neutrons. The GdNC reaction can induce cell death provided

Gilbert, Pupa Gelsomina De Stasio

145

Laser-induced anisotropy in terbium-gallium garnet  

NASA Astrophysics Data System (ADS)

We observed that a Tb3Ga5O12 crystal when illuminated at the terbium ion resonance, becomes optically uniaxial. The optical axis is found to be along the beam-propagation axis. The origin of this symmetry breakdown is a thermal effect. Our observation of a conoscopic pattern is accounted for by a quadratic stress and refractive index distribution model. By spatial integration of the conoscopic pattern, the laser-induced stress birefringence variation as a function of the incident beam power is determined.

Chen, X.; Gonzalez, S.

1998-11-01

146

Laser-induced anisotropy in terbium-gallium garnet  

Microsoft Academic Search

3  Ga5O12 crystal when illuminated at the terbium ion resonance, becomes optically uniaxial. The optical axis is found to be along\\u000a the beam-propagation axis. The origin of this symmetry breakdown is a thermal effect. Our observation of a conoscopic pattern\\u000a is accounted for by a quadratic stress and refractive index distribution model. By spatial integration of the conoscopic pattern,\\u000a the laser-induced stress birefringence variation

X. Chen; S. Gonzalez

1998-01-01

147

Magnetothermal Measurements on Gadolinium  

Microsoft Academic Search

The small heat changes accompanying the magnetization of 99.9% pure gadolinium were measured on a rod specimen. The results are analysed, and the principal magnetization processes are identified. Domain wall movement which occurs in low fields is discussed in the light of a theory by Goodenough, and the coercivity which the theory predicts is found to agree fairly well with

L. F. Bates; A. J. Pacey

1961-01-01

148

Internal friction in gadolinium  

Microsoft Academic Search

The low-temperature internal friction spectrum of gadolinium consists of two peaks, labelled ? and ?. The former is independent and the latter dependent on, the strain amplitude. Domain wall motion, induced by the applied stress, is responsible for both peaks, which are not caused by a relaxation mechanism. The microeddy currents generated by changes in magnetization are responsible for the

C. F. Burdett

1968-01-01

149

Magnetic domains in gadolinium  

Microsoft Academic Search

The bitter patterns of ferromagnetic domains on a (1120) ; crystallographic plane of a gadolinium single crystal are presented. A ; suspension of magnetite particles in xylene, stabilized with a ten millimolar ; concentration of sodium di(ethylhexyl) sulfosuccinate was employed at -5 c- ; C. On the application of a magnetic field, the walls separating adjacent ; domains were observed

R. R. Birss; P. M. Wallis

1963-01-01

150

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

151

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

152

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

153

Radiation effects in ferrate garnet  

NASA Astrophysics Data System (ADS)

Radiation effects in four synthetic ferrate garnets (A 3B 2(XO 4) 3, Ia3 d, Z = 8) were examined by ion beam irradiations with in situ observation ( T = 298-873 K) using transmission electron microscopy (TEM) at the IVEM Tandem Facility at Argonne National Laboratory. The garnet compositions include: A = Ca, Gd, Th, and Ce; B = Zr, Fe. The critical amorphization temperatures ( Tc), the temperature above which the target material cannot be amorphized due to dynamic annealing, were between 820 and 870 K. The amorphization doses at room temperature are between 0.17 and 0.19 dpa (displacement per atom), which is similar to that of silicate- and aluminate-garnets. The small variations in the amorphization dose and Tc of the different compositions suggest that radiation effects in ferrate garnets are structurally constrained. Qualitative analyses of the valence states of Ce and Fe in garnet before and after irradiation were completed using electron energy-loss spectroscopy (EELS). The Ce and Fe in the unirradiated garnet were dominantly trivalent and divalent, respectively. The characteristic peaks of Ce 4+, at ˜5 eV higher energy for the M-edges, were present in unirradiated garnet as a minor peak, and the peaks did not disappear after complete amorphization, suggesting that the valence state did not change significantly. EELS analysis was conducted on a nearly pure andradite, Ca 3Fe 2Si 3O 12, which ideally contains only ferric iron. The andradite was amorphized at 0.18 dpa. EELS analysis revealed that some of ferric iron was converted to ferrous iron during the irradiation.

Utsunomiya, S.; Yudintsev, S.; Ewing, R. C.

2005-02-01

154

Crystal Growth And Characterization Of Oxides Host Crystals For Tunable Lasers  

NASA Astrophysics Data System (ADS)

Crystal growth of titanium doped sapphire crystals is described. Effects of growth atmosphere, titanium concentration, dopant oxidation state are described. Growth of garnet hosts gadolinium scandium gallium garnet and gadolinium scandium aluminum garnet doped with chromium is described. Effects of impurities on optical characteristics of chromium doped garnets are described, as well as approach leading to improvement of optical quality. Growth of magnesium and yttrium aluminates and their doping with titanium is described.

Kokta, Milan R.

1987-03-01

155

Properties of gallium arsenide  

SciTech Connect

Properties of Gallium Arsenide' is a handbook of evaluated numeric data and reviewed knowledge distilled by those working at the frontiers of gallium arsenide research. In addition to providing numeric data on basic physical, electronic and optical properties, the book covers many device-related aspects of gallium arsenide. Carrier attributes (ionisation coefficients, concentration, mobility, diffusion etc), deep levels and defects are surveyed and related to the various growth techniques such as MBE, VPE, and MOCVD. Sections on surface structure, oxidation, interfaces and etching are of particular relevance to integrated circuit research. Especially important in the race to achieve commercially usable samples is a state-of-the-art survey on the infra-red imaging of defects in semi-insulating gallium arsenide produced by the liquid-encapsulated Czochralski process.

Not Available

1985-01-01

156

Gallium interactions with Zircaloy  

E-print Network

: Nuclear Engineering GALLIUM INTERACTIONS WITH ZIRCALOY A Thesis by MICHAEL KEITH WEST Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Ron R.... Hart (Chair of Co ittee) Karl T. H g, (Me e Marvin L. Adams (Member) Alan E. Waltar (Head of Department) December 1998 Major Subject: Nuclear Engineering ABSTRACT Gallium Interactions with Zircaloy. (December 1998) Michael Keith West, B. S...

West, Michael Keith

2012-06-07

157

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

158

Integrated magneto-optic waveguide material structures and devices  

NASA Astrophysics Data System (ADS)

Recent advances in the preparation of B i- and Ce- substituted (doped) yttrium iron garnet (YIG) films on gadolinium gallium garnet (GGG) and semiconductor substrates such as gallium arsenide (GaAs), the design of hybrid material structures, and the construction of wideband integrated microwave and magnetooptic (MO) devices, and their potential applications are presented.

Tsai, Chen S.

2000-07-01

159

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

160

The relationship between garnet growth and MSWDs in garnet Lu-Hf dating  

Microsoft Academic Search

The advent of high-precision Lu-Hf analysis by MC-ICP-MS has led to unprecedented age resolution for garnet. Typical analytical uncertainties of ±0.005% in 176Hf\\/177Hf combined with a bulk 176Lu\\/177Hf ratio in metapelitic garnets of ~10 (±0.5% uncertainty) result in theoretical age uncertainties of only ±2 Myr and ±200 kyr for 400 and 30 Ma garnets respectively. Yet some garnet Lu-Hf isochrons

M. J. Kohn; S. L. Corrie; J. D. Vervoort

2007-01-01

161

New type of cylindrical magnetic domain in ferrite-garnet films  

Microsoft Academic Search

Cylindrical magnetic domain structures in nonimplanted epitaxial films of composition Y(0.9)Gd(1.1)Yb(0.7)Bi(0.3)Al(0.9)Ga(0.2)Fe(3.9)O(12), grown by recooling a solution melt on a gadolinium-gallium substrate with 111 axis normal to the substrate plane, were investigated. Besides Type I and II and transition domains, a Type III domain was observed, the diameter of which is an order of magnitude smaller than that of normal cylindrical

E. I. Iliashenko; S. N. Matveev

1977-01-01

162

Visualization of nonuniform magnetic fields by gadolinium-cobalt amorphous films  

NASA Astrophysics Data System (ADS)

Configurations of magnetic domain structure of gadolinium-cobalt amorphous films with a perpendicular anisotropy under the effect of spatially nonuniform magnetic stray fields produced by various miniature sources have been studied. The domain structure of the amorphous films has been shown to qualitatively and quantitatively reflect the symmetry and magnitude of the normal component of the nonuniform magnetic fields and, similar to iron garnets, can be used for topographying stray fields. New features of the domain structure have been found during the visualization of small-scale sources of stray fields, on the one hand, and fields characterized by a small gradient, on the other hand.

Ivanov, V. E.

2008-05-01

163

Design System for Locally Fabricated Gallium Arsenide  

E-print Network

Design System for Locally Fabricated Gallium Arsenide Digital Integrated Circuits by Anthony Edward, 26 November, 1990 © Anthony Parker 1990 Gallium Arsenide Digital Integrated Circuits Project System for Locally Fabricated Gallium Arsenide Digital Integrated Circuits A thesis submitted to Sydney

164

Designing Asynchronous Circuits in Gallium Arsenide  

E-print Network

Designing Asynchronous Circuits in Gallium Arsenide Jos'e A. Tierno Department of Computer Science.1 Asynchronous circuits : : : : : : : : : : : : : : : : : : : : : : : 4 1.2 Gallium Arsenide : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 6 1.5 Outline of this Thesis : : : : : : : : : : : : : : : : : : : : : : : 6 2 Gallium Arsenide

Martin, Alain

165

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

SciTech Connect

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

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

2011-12-15

166

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

167

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. PMID:22800370

Chitambar, Christopher R

2013-01-01

168

Magneto-optical recording on garnet films  

NASA Astrophysics Data System (ADS)

As next generation magneto-optical (MO) recording media, rare earth iron garnet films with the magnetization aligned perpendicular to the film surface are prepared by sputtering and pyrolysis on glass substrates. Compared to the current amorphous metal MO films the garnet films are high in corrosion resistance and strong in MO effect, especially when enhanced by Bi 3+ or Ce 3+ which substitutes for the rare earths. However, garnet films on glass substrates are obtained only in polycrystalline form, which causes an important problem yet to be fully solved, the problem of media noise generated at grain boundaries.

Abe, M.; Gomi, M.

1990-03-01

169

Rare Earth Garnet Selective Emitter  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

170

Gallium phosphide energy converters  

Microsoft Academic Search

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need

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

1995-01-01

171

[CANCER RESEARCH 61, 42724277, May 15, 2001] Gadolinium in Human Glioblastoma Cells for Gadolinium  

E-print Network

[CANCER RESEARCH 61, 4272­4277, May 15, 2001] Gadolinium in Human Glioblastoma Cells for Gadolinium is a noninvasive experimental therapy for malignant gliomas based on a binary approach. In the first step

Gilbert, Pupa Gelsomina De Stasio

172

Garnet Deformation Microstructures: TEM vs. EBSD  

NASA Astrophysics Data System (ADS)

The development of electron backscatter diffraction (EBSD) and orientation contrast (OC) analysis enable us to study the microstructure of minerals and to measure the orientation of all crystallographic axes in thin sections with resolution down to sub micrometer scale. One of the great advantages of this methods is that it is now possible to study cubic crystals, such as garnet, which are isotropic for light. The application of this new technique to the study of garnets revealed an unexpected wide variety of microstructures, which are not all related to the deformation of garnet. The orientation distribution analyses help to distinguish between brittle or plastic deformation, grain or subgrain boundaries and growth defects. Garnet microstructures related to plastic deformation are characterized by the development of rotation axes if a transect across several garnet subgrains is measured with small crystallographic mismatches (<3° ) across cell boundaries. Each specific rotation axis is directly related to the activated slip system. If more than one slip system is involved, the identification of individual is not always possible. In order to fully characterize the deformation microstructure additional transmission electron microscopical (TEM) work is needed. Here we present new data on garnet deformation microstructures characterized by EBSD and TEM techniques. In some cases a connection between cell boundary and chemical composition is observed by comparing OC, BSE and element mapping. The same area is studied by analytical TEM and shows subgrain boundaries as well as indications for brittle failure with subsequent refilling of a newly grown garnet. In the case of subgrain boundaries a higher diffusivity is expected along dislocation cores. In order to get a more general view about the net effect of microstructuring of garnet, bulk diffusion calculations were performed for homogeneously distributed defects and a network of subgrain boundaries. Assuming the same enhancement of diffusion by microstructuring as in metal, garnet remains an open system for homogeneously distributed defects below 600 to 650° C at strain rates in the order of 10-12 s-1. A closely spaced network of subgrain boundaries will affect bulk diffusion at even higher temperatures. Our data suggest that deformation microstructures in garnet are more frequent than previously assumed and that microstructures may significantly enhance bulk diffusion coefficients. As a consequence the microstructure of garnet must be considered when applying geo-chronological or thermo-barometrical techniques.

Brenker, F. E.; Prior, D. J.

2003-12-01

173

Gadolinium magnetic resonance imaging dacryocystography.  

PubMed

A 1:100 solution of 48% gadopentolate in liquid tear solution was used in magnetic resonance dacryocystography to image the canaliculi, nasolacrimal sac, and nasolacrimal duct. It was administered as an eyedrop, one drop every minute for five minutes, immediately before scanning in six normal and five abnormal nasolacrimal outflow systems. In cases of nasolacrimal obstruction, the dilute gadolinium solution was injected through the canaliculus immediately before scanning. A three-inch surface coil enhanced the detail of soft-tissue structures such as the canaliculi and lacrimal sac. In the evaluation of complex tearing disorders such as congenital, neoplastic, postsurgical, and posttraumatic nasolacrimal obstruction, gadolinium lacrimal contrast adds useful information to magnetic resonance images of the lacrimal outflow system. Because of the expense of the test, we do not recommend it as a routine examination. PMID:8506908

Goldberg, R A; Heinz, G W; Chiu, L

1993-06-15

174

Oxidative dissolution of gallium arsenide and separation of gallium from arsenic  

SciTech Connect

The method of dissociating gallium arsenide into a gallium-containing component and an arsenic-containing component, is described which comprises contacting the gallium arsenide with an oxidizing agent and a liquid comprising hydroxamic acid to convert the gallium to a gallium-hydroxamic acid complex and to oxidize the arsenic to a positive valence state.

Coleman, J.P.; Monzyk, B.F.

1988-07-26

175

Magnetic anisotropy and domain structure in gadolinium.  

E-print Network

??The magnetocrystalline anisotropy constants of high quality single crystals of gadolinium have been measured using torque magnetometry. The redetermination of the anisotropy constants was necessary… (more)

Smith, Ronald Leslie

1978-01-01

176

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

177

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

PubMed

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

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

2005-12-16

178

GADOLINIUM SOLUBILITY AND VOLATILITY DURING DWPF PROCESSING  

SciTech Connect

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

Reboul, S

2008-01-30

179

Rare earth garnet selective emitter  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

180

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

181

Gallium interstitial contributions to diffusion in gallium arsenide  

NASA Astrophysics Data System (ADS)

A new diffusion path is identified for gallium interstitials, which involves lower barriers than the barriers for previously identified diffusion paths [K. Levasseur-Smith and N. Mousseau, J. Appl. Phys. 103, 113502 (2008), P. A. Schultz and O. A. von Lilienfeld, Modelling and Simulation in Materials Science and Engineering 17, 084007 (2009)] for the charge states which dominate diffusion over most of the available range of Fermi energies. This path passes through the ?110? gallium-gallium split interstitial configuration, and has a particularly low diffusion barrier of 0.35 eV for diffusion in the neutral charge state. As a part of this work, the character of the charge states for the gallium interstitials which are most important for diffusion is investigated, and it is shown that the last electron bound to the neutral interstitial occupies a shallow hydrogenic bound state composed of conduction band states for the hexagonal interstitial and both tetrahedral interstitials. How to properly account for the contributions of such interstitials is discussed for density-functional calculations with a k-point mesh not including the conduction band edge point. Diffusion barriers for gallium interstitials are calculated in all the charge states which can be important for a Fermi level anywhere in the gap, q = 0, +1, +2, and +3, for diffusion via the ?110? gallium-gallium split interstitial configuration and via the hexagonal interstitial configuration. The lowest activation enthalpies over most of the available range of Fermi energies are found to correspond to diffusion in the neutral or singly positive state via the ?110? gallium-gallium split interstitial configuration. It is shown that several different charge states and diffusion paths contribute significantly for Fermi levels within 0.2 eV above the valence band edge, which may help to explain some of the difficulties [H. Bracht and S. Brotzmann, Phys. Rev. B 71, 115216 (2005)] which have been encountered in fitting experimental results for heavily p-type, Ga-rich gallium arsenide by simply extending a model for gallium interstitial diffusion which has been used for less p-doped material.

Schick, Joseph T.; Morgan, Caroline G.

2011-09-01

182

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

183

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

184

Magnetic volumetric hologram memory with magnetic garnet.  

PubMed

Holographic memory is a promising next-generation optical memory that has a higher recording density and a higher transfer rate than other types of memory. In holographic memory, magnetic garnet films can serve as rewritable holographic memory media by use of magneto-optical effect. We have now demonstrated that a magnetic hologram can be recorded volumetrically in a ferromagnetic garnet film and that the signal image can be reconstructed from it for the first time. In addition, multiplicity of the magnetic hologram was also confirmed; the image could be reconstructed from a spot overlapped by other spots. PMID:24977893

Nakamura, Yuichi; Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru

2014-06-30

185

GALLIUM--1997 29.1 By Deborah A. Kramer  

E-print Network

devices manufactured from gallium arsenide (GaAs) continued to be the principal use for gallium. Increased. These epitiaxial layers are normally gallium aluminum arsenide (GaAlAs), gallium arsenide phosphide (GaAsP), or indium gallium arsenide phosphide (InGaAsP), while the substrate material is either GaAs or gallium

186

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

187

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

188

Acta Physica Academiae Scientiarum Hungaricae, Tomus 47 (1-3), pp. 209-217 (1979) STRUCTURE OF PbO-B20, -Fe20, MELTS  

E-print Network

an important part of the technology of magnetic bubble domain based mass storage devices. The epitaxial growth for the PbO-B20,-Fe,O, system which is the preferred solvent for magnetic bubble storage technology. Electric of YIG-type mag- netic garnets on a nonmagnetic gallium-gadolinium-garnet (GGG)substrate takes place

Vertes, Akos

189

Magnetoacoustic SAW interaction in YIG films  

Microsoft Academic Search

The magnetoacoustic SAW interaction has been experimentally investigated for yttrium-iron garnet films placed on gallium gadolinium garnet substrates. In this paper, we propose a new approach to the analysis of hysteresis dependencies which consist of two branches for different directions of magnetic field variation. For each of the branches, even and odd portions were separated. The even portions were shown

Boris D. Zaitsev; Alexey V. Ermolenko; Vladimir A. Fedorenko

1998-01-01

190

Gallium localization in peritonitis. Two case reports  

SciTech Connect

Diffuse abdominal localization of gallium was found in two patients with peritonitis, one due to M. tuberculosis and the other presumably pyogenic. Gallium scanning may be useful in the diagnosis of peritonitis and perhaps of other serosal infections.

LaManna, M.M.; Saluk, P.H.; Zekavat, P.P.; Mobini, J.; Parker, J.A.

1984-01-01

191

Gadolinium sheet converter for neutron radiography.  

PubMed

This work describes a methodology developed for the confection of gadolinium sheet converter for neutron radiography using the gadolinium chloride (GdCl3) as material converter. Though manufactured at a relatively low cost, they are as good as the sheet converter on the market. Here, we present neutron radiography of the penetrameter, the edge spread function, the modulation transfer function and characteristic curves for each set sheet-AA400 Kodak film. PMID:17702586

Lima, C T S; Crispim, V R; Santos, W M S

2007-12-01

192

Simulating the Atomic Assembly of Gallium Arsenide  

E-print Network

Simulating the Atomic Assembly of Gallium Arsenide A Dissertation Presented to the Faculty with gallium-rich GaAs (001) surfaces indicate a high sticking probability for SW potentials. This is in good an orientation dependence. Atomic processes responsible for the formation of the gallium vacancy defects were

Wadley, Haydn

193

Progress in gallium arsenide semiconductors  

SciTech Connect

After almost 30 years as the technology of the future, gallium arsenide has begun to make a place for itself, not by supplanting silicon but by complementing it in new applications. The inherent advantages of the material lie in the speed with which electrons move through it, in weak-signal operations and in the generation and detection of light. These advantages suit it for roles in computing, television reception and the optoelectronic transmission of data through optical-fiber networks. Gallium arsenide light-emitting diodes and lasers used in visual-display technologies and audio-disk players already account for more than $1 billion in sales annually. Hundreds of thousands of satellite-receiving dishes that use gallium arsenide detectors are sold every year, and high-speed circuits using gallium arsenide transistors are projected to reach a similar turnover in a few years. In an economy and society that depend on the rapid exchange of information as well as on the processing of it, many silicon-dominated processors will require a considerable admixture of gallium arsenide components in order to do their jobs.

Brodsky, M.H. (IBM Thomas J. Watson Research Center, Yorktown Heights, NY (USA))

1990-02-01

194

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

195

Gallium phosphide energy converters  

SciTech Connect

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

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

1995-10-01

196

Gallium phosphide energy converters  

NASA Astrophysics Data System (ADS)

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

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

1995-10-01

197

Gallium in cancer treatment.  

PubMed

Gallium (Ga) is the second metal ion, after platinum, to be used in cancer treatment. Its activities are numerous and various. It modifies three-dimensional structure of DNA and inhibits its synthesis, modulates protein synthesis, inhibits the activity of a number of enzymes, such as ATPases, DNA polymerases, ribonucleotide reductase and tyrosine-specific protein phosphatase. Ga alters plasma membrane permeability and mitochondrial functions. Ga salts are taken up more efficiently and more specifically by tumour cells when orally administered. New compounds have been prepared: Ga maltolate, doxorubicin-Ga-transferrin conjugate and Tris(8-quinolinolato)Ga(III), which show interesting activities. Ga toxicity is well documented in vitro and in vivo in animals. In humans, the oral administration Ga is less toxic, and allows a chronic treatment, allowing an improvement of its bioavailability in tumours, by comparison with the parenteral use. The anticancer activity of Ga salts has been demonstrated but other effects have also been noted such as many bone effects that could be useful in bone metastatic patients. Its has also been shown that a long period of administration could induce tumour fibrosis. Ga is synergistic with other anticancer drugs. Although not as potent as platinum in vitro, the anticancer activity of Ga should not be ignored, but the schedule of administration still needs to be optimised and new compounds are now under clinical investigations. PMID:12050020

Collery, Philippe; Keppler, Bernhard; Madoulet, Claudie; Desoize, Bernard

2002-06-01

198

Medical Applications and Toxicities of Gallium Compounds  

PubMed Central

Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use. PMID:20623028

Chitambar, Christopher R.

2010-01-01

199

A FETISH for gallium arsenide  

SciTech Connect

An overview of the development of a new dielectric material, cubic-GaS, from the synthesis of new organometallic compounds to the fabrication of a new class of gallium arsenide based transistor is presented as a representative example of the possibility that inorganic chemistry can directly effect the development of new semiconductor devices. The gallium sulfido compound [({sup t}Bu)GaS]{sub 4}, readily prepared from tri-tert-butyl gallium, may be used as a precursor for the growth of GaS thin films by metal organic chemical vapor deposition (MOCVD). Photoluminescence and electronic measurements indicate that this material provides a passivation coating for GaAs. Furthermore, the insulating properties of cubic-GaS make it suitable as the insulating gate layer in a new class of GaAs transistor: a field effect transistor with a sulfide heterojunction (FETISH).

Barron, A.R. [Rice Univ., Houston, TX (United States)

1996-12-31

200

Nonequilibrium Excitations Generated by NEODYMIUM:YTTRIUM Aluminum Garnet Laser Radiation in Bulk Gallium-Arsenide  

NASA Astrophysics Data System (ADS)

Equilibrium and non-equilibrium excitations in various kinds of GaAs single crystals are probed by 90(DEGREES) Raman scattering. In semi-insulating (SI) material, at room temperature, we are able to separate the three normalized, independent symmetry components of the whole 2-phonon spectrum from 0 to 650 cm('-1) in GaAs single crystals. We identified 25 sharp phonon peaks in such spectra, which includes a few difference frequency combinations less than 100 cm(' -1) from the laser line. Our most striking discovery is the generation of non-equilibrium bound holes of concentration (TURN)10('15) cm('-3) on residual, minority, shallow acceptors at low temperatures by a weak, CW Nd:YAlG laser in undoped SI GaAs grown by liquid encapsulated Czochralski technique, but not in n-type or Cr-doped, SI GaAs. We observed sharp -line, well resolved electronic Raman (ER) spectra of these holes on carbon acceptors in some samples and on zinc acceptors in another. These sharp-line spectra are used to explore the various features of the ER spectrum in bulk GaAs and to characterize this technologically important material. We found that the native, mid-gap defects EL2 are responsible for the observation of the long-lived, non-equilibrium bound holes in this material. The combination of facts (1) the compensation between the EL2 defects and the residual, shallow acceptors in this material, and (2) the existence of the metastable state of the EL2 defects, explain the ease of generation of non-equilibrium bound holes by the sub-band gap, Nd:YAlG laser radiation. Under extremely intense, Q-switched YAlG laser illumination the amplitude of these ER spectra decreases due to 2-photon absorption processes, but non-equilibrium ER signals are generated in Cr-doped, SI and n-type materials. For Cr-doped, SI GaAs, we observed a broad peak at 150 cm('-1) which is attributed to the E line of carbon acceptors, broadened by the strong, internal electric fields. For n-type material, we showed that the previously observed non-equilibrium peaks are actually due to the ER scattering of residual, minority, zinc acceptors in n-type samples, instead of non-equilibrium zone boundary TA phonons.

Wan, Kam Hoi

201

Investigation of self-induced distortions of laser radiation in lithium niobate and terbium gallium garnet  

Microsoft Academic Search

Future large-scale interferometric gravitational wave detectors (such as those being developed by LIGO, VIRGO, GEO, TAMA, and ACIGA) will use frequency and amplitude stabilized, high-power (10 W) cw lasers for sensitive readout of the gravitational wave signal. Here, we investigate high-power propagation effects in these optical elements. All of our experiments used a 9-W cw Nd:YAG laser with a well-characterized

E. Khazanov; O. Kulagin; S. Yoshida; D. Reitze

1998-01-01

202

An investigation on the magneto-optic properties of terbium gallium garnet under high magnetic field  

Microsoft Academic Search

The superexchange interaction on a magnetic ion may be represented by an effective field Hm = lambdaM in some paramagnetic materials, here lambda is the coefficient of effective field and M = chiHe with chi being the magnetic susceptibility and He being the applied field. The variation of the equivalent lambdachi with the dynamic applied field is given and the

Guo Yang; Guo-Ying Zhang; Jiao Gao; Liu-Ping Xue; Tian Xia; Xue-Long Zhang

2011-01-01

203

Field-induced antiferromagnetism and competition in the metamagnetic state of terbium gallium garnet  

NASA Astrophysics Data System (ADS)

The magnetic properties of the hyperkagome system of Tb3Ga5O12 have been investigated by neutron scattering. Evidence of antiferromagnetic long-range order of the Tb moments at TN?0.35K in zero field is provided. With the application of magnetic field in the paramagnetic phase, ferromagnetic peaks initially appear at nuclear Bragg reflections. With the field higher than 3 Tesla, antiferromagnetic Bragg peaks appear as well indicating that the low-temperature magnetic phase extends well beyond the phase boundary, into the paramagnetic phase, with field. The new magnetic symmetry sets in at the metamagnetic transition in this system.

Kamazawa, K.; Louca, Despina; Morinaga, R.; Sato, T. J.; Huang, Q.; Copley, J. R. D.; Qiu, Y.

2008-08-01

204

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

Microsoft Academic Search

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

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

1999-01-01

205

Field-induced antiferromagnetism and competition in the metamagnetic state of terbium gallium garnet  

Microsoft Academic Search

The magnetic properties of the hyperkagome system of Tb3Ga5O12 have been investigated by neutron scattering. Evidence of antiferromagnetic long-range order of the Tb moments at TN<=0.35K in zero field is provided. With the application of magnetic field in the paramagnetic phase, ferromagnetic peaks initially appear at nuclear Bragg reflections. With the field higher than 3 Tesla, antiferromagnetic Bragg peaks appear

K. Kamazawa; Despina Louca; R. Morinaga; T. J. Sato; Q. Huang; J. R. D. Copley; Y. Qiu

2008-01-01

206

Thermally Induced Birefringence in Faraday Devices Made from Terbium Gallium Garnet-Polycrystalline Ceramics  

Microsoft Academic Search

We have developed a model that describes thermally induced birefringence in polycrystalline ceramics that are exposed to a magnetic field. Conditions under which traditional compensation techniques (for glass and single crystals) can be effective for ceramics have been found. It is shown that a ceramic is almost equivalent to a [111]-oriented crystal if the ratio of the rod length to

Mikhail A. Kagan; Efim A. Khazanov

2004-01-01

207

An investigation on the magneto-optic properties of terbium gallium garnet under high magnetic field  

NASA Astrophysics Data System (ADS)

The superexchange interaction on a magnetic ion may be represented by an effective field Hm = ?M in some paramagnetic materials, here ? is the coefficient of effective field and M = ?He with ? being the magnetic susceptibility and He being the applied field. The variation of the equivalent ?? with the dynamic applied field is given and the crystal field-splitting levels of the excited configuration 4f75d1 of the Tb3+ ion are calculated in the Tb3Ga5O12. By means of the effective field Hm and the applied field He, the Faraday rotation of Tb3Ga5O12 at 6 K and 41 K, under the high magnetic field and at 0.63 ?m wavelength, are presented. Our calculated results are in agreement with the experimental data.

Yang, Guo; Zhang, Guo-Ying; Gao, Jiao; Xue, Liu-Ping; Xia, Tian; Zhang, Xue-Long

2011-01-01

208

Thermally Induced Birefringence in Faraday Devices Made from Terbium Gallium Garnet-Polycrystalline Ceramics  

NASA Astrophysics Data System (ADS)

We have developed a model that describes thermally induced birefringence in polycrystalline ceramics that are exposed to a magnetic field. Conditions under which traditional compensation techniques (for glass and single crystals) can be effective for ceramics have been found. It is shown that a ceramic is almost equivalent to a [111]-oriented crystal if the ratio of the rod length to the grain size is ~300 or more. In particular, residual depolarization (after the compensation techniques are applied) is inversely proportional to this ratio, which is an important consequence of the random nature of thermally induced birefringence in ceramics.

Kagan, Mikhail A.; Khazanov, Efim A.

2004-11-01

209

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

210

Low-Temperature Metasomatic Garnets in Marine Sediments  

Microsoft Academic Search

The paragenesis of low-temperature metasomatic calcium-iron garnets or hydro-garnets in marine sediments is discussed. Oxygen isotope data indicate that the garnetiferous (micarb) chalk from DSDP site 251, southwest branch, Indian Ocean Ridge (gros52and40py6alm1.5sp0.5), formed at about 170 degrees C from circulating seawater hydrothermal solutions passing through the underlying altered basalts. Other possible examples of the hydrothermal metasomatic formation of garnets

A. J. Easton; D. R. C. Kempe; S. M. F. Sheppard

1977-01-01

211

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

212

GALLIUM--1999 29.1 By Deborah A. Kramer  

E-print Network

% of gallium consumed in the United States was in the form of gallium arsenide (GaAs). Analog integratedGALLIUM--1999 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. Gallium demand in the United States was satisfied by imports

213

GALLIUM--2001 29.1 By Deborah A. Kramer  

E-print Network

, a significant consumer of gallium arsenide (GaAs)-based devices. As the gallium demand declined during 2001GALLIUM--2001 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared in lower demand for gallium from the record-high levels that transpired in 2000. The largest factor

214

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

215

Interaction between copper and gallium  

NASA Astrophysics Data System (ADS)

The interaction between solid copper and liquid gallium is considered, which is the main process during the setting of diffusion-solidifying solders. The dependences of the process rate and the size characteristics on the phase composition of the initial mixture are found. The intermetallic compound CuGa2 is shown to be the product of the interaction in all cases.

Ancharov, A. I.; Grigoryeva, T. F.; Barinova, A. P.; Boldyrev, V. V.

2008-12-01

216

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

217

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

218

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

219

Gallium scintigraphy in acute panniculitis  

SciTech Connect

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

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

1981-11-01

220

Gallium nitride electronics  

NASA Astrophysics Data System (ADS)

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

Rajan, Siddharth; Jena, Debdeep

2013-07-01

221

Gallium Arsenide Integrated Circuits 1988 ANZAAS Congress, VLSI Section  

E-print Network

Gallium Arsenide Integrated Circuits 1988 ANZAAS Congress, VLSI Section Anthony E. Parker are collaborating to establish a local GaAs digital integrated design and fabrication capability. Gallium Arsenide Laboratory for Communication Science and Engineering, Sydney University Electrical Engineering Gallium

222

Subcellular SIMS imaging of gadolinium isotopes in human glioblastoma cells treated with a gadolinium containing MRI agent  

Microsoft Academic Search

Neutron capture therapy is an experimental binary radiotherapeutic modality for the treatment of brain tumors such as glioblastoma multiforme. Recently, neutron capture therapy with gadolinium-157 has gained attention, and techniques for studying the subcellular distribution of gadolinium-157 are needed. In this preliminary study, we have been able to image the subcellular distribution of gadolinium-157, as well as the other six

Duane R. Smith; Daniel R. Lorey; Subhash Chandra

2004-01-01

223

FMR doublet in two-layer iron garnet films  

Microsoft Academic Search

Multilayer epitaxial iron garnet films have been investigated very intensively in the recent past. The dipole and exchange couplings of spins lying in different layers results in the existence of new types of oscillations in these structures and give rise to the characteristic resonance properties of them. Resonance microwave absorption in two-layer iron garnet films, of which one layer is

A. M. Grishin; V. S. Dellalov; E. I. Nikolayev; V. F. Shkar; S. V. Yampolskii

1994-01-01

224

FMR doublet in two-layer iron garnet films (abstract)  

Microsoft Academic Search

Multilayer epitaxial iron garnet films have been investigated very intensively in the recent past. The dipole and exchange couplings of spins lying in different layers results in the existence of new types of oscillations in these structures and give rise to the characteristic resonance properties of them. Resonance microwave absorption in two-layer iron garnet films, of which one layer is

A. M. Grishin; V. S. Dellalov; E. I. Nikolayev; V. F. Shkar; S. V. Yampolskii

1994-01-01

225

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

226

Majorite Garnet and Lithosphere Evolution: Kaapvaal Craton  

NASA Astrophysics Data System (ADS)

The uppermost 50-70 km of the subcontinental lithospheric mantle (SCLM) beneath the Kaapvaal Craton (S. Africa) consists largely of highly-depleted chromite harzburgites. These rocks are understudied, mainly because of their uniformity and their lack of indicator minerals such as garnet and clinopyroxene (cpx). Kimberlite-borne xenoliths of these rocks contain rare volumes of cpx-spinel (modal 76/24) symplectite, with smooth grain boundaries; many studies have suggested that these might represent low-pressure breakdown products of garnet (majorite + olivine ? cpx + spinel). Our reconstruction of a suite of these grains, using element mapping and EMP analysis of constituent minerals, gives a majoritic garnet with mean composition 21.8% CaO, 15.8% Cr2O3, 9.22% Al2O3, Si=3.118, mg#=0.93. The majorite contents suggest formation at depths of 250-280 km. Ni contents imply temperatures ?1500 °C, but have large uncertainties related to the subtraction of olivine (ca 20%) during the reconstruction calculation. LAM-ICPMS analyses show strongly sinuous REE patterns with CN Dy/Lu <0.1 and Ce/Dy >100. Most analyses have negative Eu anomalies, consistent with chromite compositions that indicate strongly reducing conditions (?fO2(FMQ) = -4 to -5). Melt modeling suggests that the harzburgites are products of 30-40% melting of asthenospheric mantle at 250 km depth, leaving residues of ol+opx+chromite. The presence of the majorites and their overall LREE enrichment are ascribed to the introduction of carbonatitic metasomatic fluids, similar to those recorded by diamond-inclusions (subcalcic garnets), shortly after the depletion. We suggest that the melting, the metasomatism and the ultimate breakdown of the majorite track a process of mantle upwelling, with melt-extraction at depth providing the buoyancy that allowed the residual harzburgites to rise to shallow levels and stabilize the SCLM. Os-isotope analyses of sulfides associated with the majorites give TRD = 2.5-3.4 Ga, suggesting that this process was part of the major mantle overturn(s) that produced most of the world's cratonic SCLM [1]. [1] Griffin et al. 2013. Lithos (in press)

Griffin, W. L.; Tessalina, S.; O'Reilly, S. Y.

2013-12-01

227

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

228

Gadolinium: Central Metal of the Lanthanoids  

ERIC Educational Resources Information Center

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

Laing, Michael

2009-01-01

229

Impedance and initial magnetic permeability of gadolinium  

Microsoft Academic Search

In the present work we report on measurements of the complex impedance and the magnetoimpedance of a textured sample of gadolinium metal. The preferential c-axis orientation of the Gd hexagonal structure is perpendicular to the long axis of the sample. From the experimental data, the complex initial magnetic permeability, ?=??+i??, was obtained as a function of temperature and frequency of

G. L. F. Fraga; P. Pureur; L. P. Cardoso

2010-01-01

230

Impedance and initial magnetic permeability of gadolinium  

Microsoft Academic Search

In the present work we report on measurements of the complex impedance and the magnetoimpedance of a textured sample of gadolinium metal. The preferential c -axis orientation of the Gd hexagonal structure is perpendicular to the long axis of the sample. From the experimental data, the complex initial magnetic permeability, mu=mu'+imu'', was obtained as a function of temperature and frequency

G. L. F. Fraga; P. Pureur; L. P. Cardoso

2010-01-01

231

Resonance Parameter Measurements and Analysis of Gadolinium  

E-print Network

Resonance Parameter Measurements and Analysis of Gadolinium G Leinweber, DP Barry, MJ Trbovich, JA-matrix Bayesian code SAMMY was used to extract resonance parameters. The results of the thermal region analysis are significant. Resonance parameters for the low energy doublet, at 0.025 and 0.032 eV, are presented

Danon, Yaron

232

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

233

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

234

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

235

GALLIUM--2000 30.1 By Deborah A. Kramer  

E-print Network

in the United States was in the form of gallium arsenide (GaAs). Analog integrated circuits (ICs) wereGALLIUM--2000 30.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. By yearend, worldwide gallium supplies were insufficient to meet

236

Large grain gallium arsenide thin films  

SciTech Connect

Polycrystalline gallium arsenide films deposited on tungsten/graphite substrates have been used for the fabrication of thin film solar cells. Gallium arsenide films deposited on foreign substrates of 10 ..mu..m or less thickness exhibit, in most cases, pronounced shunting effects due to grain boundaries. MOS solar cells of 9 cm/sup 2/ area with an AMI efficiency of 8.5% and p/sup +//n/n/sup +/ homojunction solar cells of 1 cm/sup 2/ area with an AM1 efficiency of 8.8% have been prepared. However, in order to further improve the conversion efficiency before the development of effective passivation techniques, gallium arsenide films with large and uniform grain structure are necessary. The large grain gallium arsenide films have been prepared by using the arsine treatment of a thin layer of molten gallium on the substrate surface and the recrystallized germanium films on tungsten/graphite as substrates.

Chu, S.S.; Chen, W.J.; Chu, T.L.; Firouzi, H.; Han, Y.X.; Wang, Q.H.

1984-05-01

237

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

238

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

E-print Network

$11 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-07 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped64 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

239

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

E-print Network

$14 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-09 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

240

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

E-print Network

.S. gallium consumption, were valued at about $32 million. Gallium arsenide (GaAs) and gallium nitride (Ga Number Normal Trade Relations 12­31­12 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Gallium metal 8112.92.1000 3.0% ad val. Depletion Allowance

241

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

E-print Network

$23 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-08 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped60 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

242

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2004. One company in Utah  

E-print Network

$4 million, most of which was low-purity material. Gallium arsenide (GaAs) and gallium nitride (Ga. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 381864 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

243

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1999. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $11.2 million. Gallium arsenide (GaAs) components.91.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

244

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

E-print Network

.S. gallium consumption, were valued at about $16 million. Gallium arsenide (GaAs) and gallium nitride (Ga arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

245

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1996. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $7.9 million. Gallium arsenide (GaAs) components. 25.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. 25.0% ad val. Gallium62 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

246

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

247

Magnetic entropy in nanocomposite binary gadolinium alloys  

Microsoft Academic Search

Investigation on magnetocaloric effects, magnetic entropy, Curie temperature, and specific heat of nanocomposite binary gadolinium alloys Gd–Tb, Gd–Zn, and Gd–Y has been carried out with an applied magnetic field of 1 T and in a temperature range of 233–313 K. Compared with the respective bulk alloys, the as-prepared nanocomposite alloys were found to have higher specific heat and lower Curie

Yuanzhi Shao; Jinxiu Zhang; J. K. L. Lai; C. H. Shek

1996-01-01

248

Ferromagnetic Resonance of Single-Crystal Gadolinium  

Microsoft Academic Search

Gadolinium metal is a system of relative simplicity as far as exchange interactions and ionic states are concerned. The 8S7?2 state of Gd3+ is consistent with the observed 7?b?atom and the moment contributing f electrons are most likely exchange coupled via conduction electrons. The present work concerns the measurement of the ferromagnetic resonance behavior of a single crystal at frequencies

T. W. Moore; D. S. Rodbell

1964-01-01

249

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

SciTech Connect

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

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

2013-05-07

250

Sol–gel preparation and characterization of gadolinium aluminate  

Microsoft Academic Search

This paper reports on the results concerning the sol–gel preparation of nanocrystalline gadolinium aluminate (GdAlO3, GAP) using different starting materials. The gadolinium nitrate or gadolinium oxide as Gd raw compounds and aluminium nitrate as Al source were used in the sol–gel processing. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by

S. Cizauskaite; V. Reichlova; G. Nenartaviciene; A. Beganskiene; J. Pinkas; A. Kareiva

2007-01-01

251

Gadolinium and nephrogenic systemic fibrosis: an update.  

PubMed

Nephrogenic systemic fibrosis (NSF) is a multisystem disease seen exclusively in patients with renal impairment. It can be severely debilitating and sometimes fatal. There is a strong association with gadolinium-based contrast agents used in magnetic resonance imaging (MRI). Risk factors include renal impairment and proinflammatory conditions, e.g. major surgery and vascular events. Although there is no single effective treatment for NSF, the most successful outcomes are seen following restoration of renal function, either following recovery from acute kidney injury or following renal transplantation. There have been ten biopsy-proved pediatric cases of NSF, with no convincing evidence that children have a significantly altered risk compared with the adult population. After implementation of guidelines restricting the use of gadolinium-based contrast agents in at-risk patients, there has been a sharp reduction in new cases and no new reports in children. Continued vigilance is recommended: screening for renal impairment, use of more stable gadolinium chelates, consideration of non-contrast-enhanced MRI or alternative imaging modalities where appropriate. PMID:24146299

Weller, Alex; Barber, Joy L; Olsen, Oystein E

2014-10-01

252

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

253

Garnet polycrystals and the significance of clustered crystallization  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

254

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

255

Clinical Applications of Gallium-68  

PubMed Central

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

Banerjee, Sangeeta Ray; Pomper, Martin G.

2013-01-01

256

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

257

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

258

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

259

Magnetic Transitions in Alloys of Gadolinium and Dysprosium  

Microsoft Academic Search

Magnetic properties of alloys of gadolinium and dysprosium have been studied experimentally. As the temperature is lowered, pure gadolinium makes a transition from the paramagnetic state directly to the ferromagnetic state. Pure dysprosium transforms under somewhat similar circumstances from the randomly oriented spin structure to an ordered spin state, commonly referred to as a spiral structure. As the temperature is

Frederick Milstein; Lawrence Baylor Robinson

1967-01-01

260

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

261

Recovery of gallium from aluminum industry residues  

SciTech Connect

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

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

2000-01-01

262

Radiochemical separation of gallium by amalgam exchange  

USGS Publications Warehouse

An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

Ruch, R. R.

1969-01-01

263

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

264

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

265

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

266

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

267

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

268

Spectroscopic Analysis of Rock Mineral—Garnet of South Kerala  

NASA Astrophysics Data System (ADS)

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 is inferred from the XRF that the sample contains large concentration of Tungsten [WO3-22%] besides Silicon [SiO2-7-9%], Iron [Fe2O3-55%] etc.. IR spectra in the region 2800-3600 cm-1 indicates absorption pattern attributable to OH structurally bound within the Garnet. The spectral bands corresponding to the various elements present in the garnet sample such as Si, Al, Fe, Mg etc. have been identified from their Raman and IR spectra. The vibrational spectral analysis further confirms that the garnet under investigation has crystallographically non equivalent SiO2 tetrahedral.

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

2008-11-01

269

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

270

Ultramafic cumulates of oceanic affinity in an intracontinental subduction zone: UHP garnet peridotites from Pohorje (Eastern  

E-print Network

Ultramafic cumulates of oceanic affinity in an intracontinental subduction zone: UHP garnet depleted mantle of oceanic affinity. The metamorphic assemblage of the garnet peridotites consists similar to those of associated Pohorje eclogites of predominantly MORB affinity. The shallow level

271

Atomic and electronic structure of gadolinium oxide  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

272

Low Temperature Spin Structure of Gadolinium Titanate  

NASA Astrophysics Data System (ADS)

Many rare earth pyrochlore oxides exhibit exotic spin configurations at low temperatures due to frustration. The nearest neighbor coupling between spins on the corner-sharing tetrahedral network generate geometrical magnetic frustration. Among these materials, gadolinium titanate (Gd2Ti2O7) is of particular interest. Its low temperature ordered phases are not yet understood theoretically. Bulk thermal measurements such as specific heat and magnetic susceptibility measurements find two phase transitions in zero external field, in agreement with simple mean field calculations. However, recent neutron scattering experiments suggest a so-called 4-k spin structure for intermediate phase and a so called canted 4-k structure for lower temperature phase that does not agree with either mean-field theory or Monte Carlo simulation which find the 1-k state and Palmer-Chalker state respectively as the lowest free energy configuration for those phases. In our work, we study the 4-k structure in detail and present a new phase diagram for dipolar Heisenberg spins on a pyrochlore lattice, certain portions of which describe gadolinium titanate.

Javanparast, Behnam; McClarty, Paul; Gingras, Michel

2012-02-01

273

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2002. Two companies in  

E-print Network

. Gallium arsenide (GaAs) components represented about 98% of domestic gallium consumption. About 34 arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

274

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

E-print Network

$4 million, most of which was low-purity material. Gallium arsenide (GaAs) and gallium nitride (Ga Relations 12/31/03 Gallium metal 8112.92.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

275

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2001. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $29 million. Gallium arsenide (GaAs) components Relations 12/31/01 Gallium metal 8112.91.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

276

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2005. One company in Utah  

E-print Network

$4 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-05 Gallium metal 8112.92.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

277

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1997. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $7.0 million. Gallium arsenide (GaAs) components arsenide wafers, undoped 2851.00.0010 2.8% ad val. 25.0% ad val. Gallium arsenide wafers, doped 381862 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

278

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2000. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $15 million. Gallium arsenide (GaAs) components Relations 12/31/00 Gallium metal 8112.91.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

279

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2006. One company in Utah  

E-print Network

$5.5 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented Relations 12-31-06 Gallium metal 8112.92.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

280

Window structure for passivating solar cells based on gallium arsenide  

NASA Technical Reports Server (NTRS)

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

Barnett, Allen M. (Inventor)

1985-01-01

281

Window structure for passivating solar cells based on gallium arsenide  

SciTech Connect

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

Barnett, A. M.

1985-10-01

282

New Dual Mode Gadolinium Nanoparticle Contrast Agent for Magnetic Resonance Imaging  

Microsoft Academic Search

BackgroundLiposomal-based gadolinium (Gd) nanoparticles have elicited significant interest for use as blood pool and molecular magnetic resonance imaging (MRI) contrast agents. Previous generations of liposomal MR agents contained gadolinium-chelates either within the interior of liposomes (core-encapsulated gadolinium liposomes) or presented on the surface of liposomes (surface-conjugated gadolinium liposomes). We hypothesized that a liposomal agent that contained both core-encapsulated gadolinium and

Ketan B. Ghaghada; Murali Ravoori; Divya Sabapathy; James Bankson; Vikas Kundra; Ananth Annapragada; Shaolin Yang

2009-01-01

283

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

284

Magnetic resonance imaging using gadolinium-based contrast agents.  

PubMed

The purpose of this article was to review the basic properties of available gadolinium-based magnetic resonance contrast agents, discuss their fundamental differences, and explore common and evolving applications of gadolinium-based magnetic resonance contrast throughout the body excluding the central nervous system. A more specific aim of this article was to explore novel uses of these gadolinium-based contrast agents and applications where a particular agent has been demonstrated to behave differently or be better suited for certain applications than the other contrast agents in this class. PMID:24477166

Mitsumori, Lee M; Bhargava, Puneet; Essig, Marco; Maki, Jeffrey H

2014-02-01

285

INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation  

E-print Network

1 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation Submitted to the Graduate;2 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS Abstract by Sajid Kabeer In0.53Ga0.47As tunnel-type dopant, exhibited a backward diode behavior. #12;4 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS

286

GALLIUM--1998 29.1 By Deborah A. Kramer  

E-print Network

consumed in the United States was in the form of gallium arsenide (GaAs). Analog integrated circuits (ICGALLIUM--1998 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. Gallium demand in the United States was satisfied by imports

287

Photoelectron energy distribution and spin polarization from activated gallium arsenide  

E-print Network

L-1027 Photoelectron energy distribution and spin polarization from activated gallium arsenide H.90 1. Introduction. It has been shown [1-4] that a p-type gallium arsenide crystal activated ont été effectuées sur des photoélectrons émis par un cristal d'arséniure de gallium activé. Les

Paris-Sud XI, Université de

288

Cellular Domain Patterns in Magnetic Garnet Films.  

NASA Astrophysics Data System (ADS)

This thesis presents the first experimental study of two-dimensional cellular patterns of magnetic domains in garnet films. Room-temperature observations focused on a Bismuth-substituted film designed for magneto-optic device applications. Measurements of energies and statistical quantities were aided by computer analysis of digitized pattern images. An external bias field H_ B induces pattern evolution that is shown to be governed by three elemental domain structures: (i) Stripe segments that form the cell boundaries. Magnetic field and domain wall energies produce effective tension in the stripe segments that drives the domain motion. (ii) 3 -fold vertices that join the stripe segments. Cellular patterns saturate when the vertices are destroyed at the bias value H_{V} (= 0.79 times 4pi M = 150 Oe), the largest saturation field of all domain pattern topologies. (iii) Pentagonal bubble traps, 5-fold symmetric structures containing trapped magnetic bubble domains. Isolated bubble traps collapse at a critical bias field H_5 (= 0.54 times 4pi M = 103 Oe). A simple geometric model illustrates the energetic mechanism of bubble trap collapse. An analytic pattern model accounts for domain interactions so as to elucidate the bias and configuration dependence of the stripe tension and outline the energetic bias regimes. All stripe segments are under tension in the nonequilibrium regime H _{RI}

Babcock, Kenneth Lawrence

289

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

290

Experimental investigation of the nonreciprocal phase shift of a transverse electric mode in a magneto-optic rib waveguide  

Microsoft Academic Search

Magnetic garnet films of composition (Nd,Lu,Bi)3(Fe,Al,Ga)5O12 are grown by liquid-phase epitaxy on [111] oriented substrates of gadolinium gallium garnet. They have positive uniaxial anisoptropy and support lattices of parallel stripe domains. A monomode optical rib waveguide is prepared by photolithography and ion-beam etching parallel to the (112) direction, which is the preferred direction of the stripe domains. A magnetic domain

M. Fehndrich; A. Josef; L. Wilkens; J. Kleine-Börger; N. Bahlmann; M. Lohmeyer; P. Hertel; H. Dötsch

1999-01-01

291

Spectral-domain analysis of dispersion characteristics of open coupled microstrip lines on YIG\\/GGG structures  

Microsoft Academic Search

This paper is to study coupled microstrip lines on layered yttrium iron garnet\\/gadolinium gallium garnet (YIG\\/GGG) structures. The problem is formulated using the spectral-domain technique, and the spectral Galerkin's method is utilized to compute the dispersion characteristics. Numerical results are presented for various values of structural and physical parameters such as widths of strips, thicknesses of YIG and GGG, separation

Kunquan Sun; Yinchao Chen

1995-01-01

292

Reduction of tetravalent chromium induced optical loss in Nd:Cr:GSGG  

NASA Astrophysics Data System (ADS)

We report on methods for eliminating of optical absorption in neodymium, chromium doped gadolinium scandium gallium garnet (Nd;Cr:GSGG) due to tetravalent chromium at the laser wavelength. These methods include doping of the crystal melt with specific additive as well as post growth heat treatments.

Pertica, A. J.; Marion, J. E.; Stokowski, S. E.

1989-10-01

293

Large Nd,Cr:GSGG boule growth and quality  

NASA Astrophysics Data System (ADS)

Gadolinium scandium gallium garnet (GSGG) has been grown in boules of 13-cm diameter by 15 cm long. Three scale-up issues have been identified and progress made toward their solution. Large slabs of Nd,Cr:GSGG are now being fabricated for efficient, medium power lasers.

Stokowski, S. E.; Shinn, M. D.; Randles, M.; Dawes, D.

1987-09-01

294

SOLID-STATE AND LIQUID LASERS: Compact GSGG:Cr3+:Nd3+ laser with passive Q switching  

NASA Astrophysics Data System (ADS)

An experimental investigation was made of a compact gadolinium scandium gallium garnet (GSGG) laser activated with Cr3+ and Nd3+, and containing phototropic centers. The active element of this laser performed the function of a passive Q switch. Lasers of this kind were demonstrated to be capable of generating nanosecond pulses with an energy of up to 5 mJ per pulse.

Danilov, A. A.; Evstigneev, V. L.; Il'ichev, Nikolai N.; Malyutin, A. A.; Nikol'ski?, M. Yu; Umyskov, A. F.; Shcherbakov, Ivan A.

1987-05-01

295

An SBS mirror with a plasma shutter in a double-pass laser amplifier  

NASA Astrophysics Data System (ADS)

A gadolinium scandium gallium garnet: Cr (3+), Nd (3+) laser with an SBS mirror and plasma shutter is studied. The use of these lasers permits control of the radiation duration in a wide range. In the regime of SBS-compression of light pulses in CCl4, a Stokes pulse duration of about 5 ns is obtained which is close to the theoretical limit.

Natarov, S. Iu.; Pashinin, P. P.; Shklovskii, E. I.; Shcherbakov, I. A.

1987-03-01

296

UPb systematics of garnet: dating the growth of garnet in the late Archean Pikwitonei granulite domain at Cauchon and Natawahunan Lakes, Manitoba, Canada  

Microsoft Academic Search

This study considers the potential of using the U-Pb dating of garnet for determining quantitative P-T-t paths for the late Archean metamorphism in the Pikwitonei granulite domain. Garnets for U-Pb dating were selected mainly\\u000a from samples that also provide information on pressure and temperature. The garnets used for dating were clear and free of\\u000a any visible inclusions. Pb concentrations range

K. Mezger; G. N. Hanson; S. R. Bohlen

1989-01-01

297

[Gallium-67 scintigraphy in malignant lymphoma].  

PubMed

The presence of a residual mass is a frequent and difficult problem in the treatment of Hodgkin's or non-Hodgkin's lymphoma: since it is of major importance to determine whether the lesion is a fibrous mass or a still progressing tumour requiring additional therapy. Gallium-67 scanning, performed in a series of 52 patients, provides an answer to this question since there is an excellent correlation between gallium uptake by the tumoral masses and their progressiveness. Magnetic resonance imaging was carried out in half of our patients: the finding of a low-intensity signal on T2-weighted sequences proved that the residual mass was fibrous, whereas a high-intensity signal on T2-weighted sequences did not distinguish between fibrous and tumour masses. The priceless information provided by the simple and non invasive method that is gallium scanning is extremely useful to evaluate the extension of lymphomas and to determine whether residual masses are tumoral or fibrous. PMID:8511078

Cohen-Haguenauer, O; Brice, P; Gaci, M; Le Pailleur, A; Cheval, E; Bris, C; Frija, J; Gisselbrecht, C; Rain, J D; Najean, Y

1993-03-27

298

/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

299

Luminescence of isoelectronic impurities and antisite defects in garnets  

NASA Astrophysics Data System (ADS)

Luminescence centres formation due to the doped isoelectron impurities (II) and antisite defects in the garnets of A3B5O12 (A=Y, Lu, Gd; B=Al, Ga) formula is considered. Substitution of the Y- or Lu-cations by La3+ and Sc3+ II in dodecahedral {c}-sites and of the Al-cations by Y3+, Lu3+, Sc3+ II in octahedral (a)-sites of garnet lattice results in formation of new emission centers in the UV region. The factors that de-termine a capability of the II to form the luminescence centers are studied. These factors include the possibility of the II to occupy (a)- and {c}-positions in the garnet lattice, the difference in the ionic radii of II and regular cations (which has to be >0.12 Å) and the differences in their electron structure. The most effective garnet phosphors are shown to be Y3Al5O12 and Lu3Al5O12 doped with the La3+ and Sc3+ II.

Zorenko, Y.

2005-01-01

300

Thermodynamic consistencies and anomalies among end-member silicate garnets.  

PubMed

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

Glasser, Leslie

2014-09-01

301

Amorphous vapour-quenched gadolinium-silver alloys  

Microsoft Academic Search

The structure of vapour-quenched thin films of gadolinium-silver alloys has been examined by X-ray diffraction techniques. The films approximately 6000 AA thick were prepared on copper, sapphire and glass substrates held at 77K. Alloys containing between 88 and 86 atomic per cent gadolinium are found to have an amorphous structure consistent with a theoretical model suggested by Sadoc (1973) for

J. Popplewell; S. W. Charles; D. D. Jenkins

1975-01-01

302

Garnet Porphyroblasts and the Tectonic Evolution of Iberia  

NASA Astrophysics Data System (ADS)

Porphyroblast inclusion trails constitute an exceptionally detailed record of deformation histories undergone by metamorphic rocks. Their orientations have been shown to be remarkably consistent in mountain belts and to relate to large-scale orogenic processes. For example, vertical and horizontal preferred orientations are almost universally developed and resulted from multiple gravitational collapse stages that periodically interrupted plate-driven (horizontal) crustal shortening. Over the past 20 years, a large body of orientation data has become available for Foliation Intersection Axes (FIA) defined by inclusion trails in orogenic belts around the world. This data reveals that FIAs in metamorphic regions generally can be grouped into a discrete number of age sets with distinctive geographic trends. Such FIA sequences apparently track shifts in the direction of crustal shortening with time. Garnet is a particularly useful porphyroblastic mineral where it comes to linking deformation and metamorphic paths, due to a unique combination of properties: (1) lengthy growth histories along extended P-T paths and in rocks with variable bulk compositions, (2) sub-spherical crystal shapes and rigid behavior favoring the nucleation of tectonic foliations against garnet edges and their preservation in continued garnet-growth stage, (3) chemical compositions sensitive to changes in metamorphic conditions that can be modeled thermodynamically, (4) abundance of datable micro-inclusions, such as monazite, and (5) the possibility of dating garnet itself via the Sm-Nd or Lu-Hf methods. In Iberia, integrated microstructural and petrological analysis of garnet porphyroblasts in the Betic Cordillera (European Alpine belt) has recently established a sequence of 4 FIA sets. The successive geographic trends of these FIA (NE-SW, NW-SE, ENE-WSW, and NNW-SSE) remarkably correlate with known changes in relative Iberia-Africa plate motion from ca. 50-10Ma. In Hercynian Iberia (Iberian Massif) inclusion trails in garnet and other porphyroblastic minerals maintain consistent NE-SW trends over hundreds of km distance, despite highly variable regional-scale fold trends. This data has allowed the recent discovery of the "Central Iberian Arc", an oroclinal structure whose origin and relationship with the Ibero-Armorican Arc are uniquely indicated by the studied garnet porphyroblasts.

Aerden, D. G.

2013-12-01

303

Radiation damage of gallium arsenide production cells  

NASA Technical Reports Server (NTRS)

High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.

Mardesich, N.; Joslin, D.; Garlick, J.; Lillington, D.; Gillanders, M.; Cavicchi, B.; Scott-Monck, J.; Kachare, R.; Anspaugh, B.

1987-01-01

304

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

305

Method for Plutonium-Gallium Separation by Anodic Dissolution of a Solid Plutonium-Gallium Alloy  

SciTech Connect

Purified plutonium and gallium are efficiently recovered from a solid plutonium-gallium (Pu-Ga) alloy by using an electrorefining process. The solid Pu-Ga alloy is the cell anode, preferably placed in a moving basket within the electrolyte. As the surface of the Pu-Ga anode is depleted in plutonium by the electrotransport of the plutonium to a cathode, the temperature of the electrolyte is sufficient to liquify the surface, preferably at about 500 C, resulting in a liquid anode layer substantially comprised of gallium. The gallium drips from the liquified surface and is collected below the anode within the electrochemical cell. The transported plutonium is collected on the cathode surface and is recovered.

Miller, William E.; Tomczuk, Zygmunt

1998-12-08

306

Four Terminal Gallium Nitride MOSFETs  

NASA Astrophysics Data System (ADS)

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

Veety, Matthew Thomas

307

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

E-print Network

granulite formed by dehydration melting of metastable hornblende-gabbronorite (Jijal Complex, Kohistan by dehydration melting of hornblende- gabbronorite protoliths in the Jijal complex (Kohistan palaeo-island arc. Key words: amphibole dehydration-melting; EBSD; garnet; HP mafic granulite; Jijal complex; Kohistan

Tommasi, Andrea

308

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

Microsoft Academic Search

In this paper, we present experimental evidence of a third-order nonlinear optical process, self-induced spin-to-orbital conversion (SISTOC) of the photon angular momentum. This effect is the physical mechanism at the origin of the depolarization of very intense laser beams propagating in isotropic materials. The SISTOC process, like self-focusing, is triggered by laser heating leading to a radial temperature gradient in

S. Mosca; B. Canuel; E. Karimi; B. Piccirillo; L. Marrucci; R. de Rosa; E. Genin; L. Milano; E. Santamato

2010-01-01

309

Optically detected magnetic resonance via the magnetic circular dichroism of absorption of cerium impurities in bulk paramagnetic terbium gallium garnet  

Microsoft Academic Search

The paramagnetic resonance of dilute 0953-8984\\/9\\/42\\/020\\/img8 ions in the bulk paramagnetic host 0953-8984\\/9\\/42\\/020\\/img9 is separated from the host response by means of optically detected magnetic resonance (ODMR) using the magnetic circular dichroism (MCD) of the absorption. This result shows that it is possible in principle to extend by means of the ODMR of the absorption the regime of paramagnetic resonance

H.-J. Reyher; B. Faust; B. Sugg; R. Rupp; L. Ackermann

1997-01-01

310

Optically detected magnetic resonance via the magnetic circular dichroism of absorption of cerium impurities in bulk paramagnetic terbium gallium garnet  

NASA Astrophysics Data System (ADS)

The paramagnetic resonance of dilute 0953-8984/9/42/020/img8 ions in the bulk paramagnetic host 0953-8984/9/42/020/img9 is separated from the host response by means of optically detected magnetic resonance (ODMR) using the magnetic circular dichroism (MCD) of the absorption. This result shows that it is possible in principle to extend by means of the ODMR of the absorption the regime of paramagnetic resonance detection of impurity ions to magnetic hosts, which strongly interact with the microwave field and, hence, make the impurity signals unobservable by means of conventional EPR. The observed ODMR signals are attributed to 0953-8984/9/42/020/img10 and 0953-8984/9/42/020/img8 ions by correlation with the optical bands of these species. By means of ODMR via the Faraday effect it is shown that this effect is due to transitions between Tb levels. The identification of the observed magnetic resonance structures is confirmed by calculations based on known information on 0953-8984/9/42/020/img10 and 0953-8984/9/42/020/img8 in diamagnetic hosts. The role of molecular fields is discussed.

Reyher, H.-J.; Faust, B.; Sugg, B.; Rupp, R.; Ackermann, L.

1997-10-01

311

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

Microsoft Academic Search

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

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

2002-01-01

312

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

313

A Gallium Multiphase Equation of State  

Microsoft Academic Search

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

Scott D Crockett; Carl Greeff

2009-01-01

314

a Gallium Multiphase Equation of State  

Microsoft Academic Search

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

Scott D. Crockett; Carl W. Greeff

2009-01-01

315

A GALLIUM MULTIPHASE EQUATION OF STATE  

Microsoft Academic Search

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

Scott D. Crockett; Carl W. Greeff

2009-01-01

316

A Gallium Multiphase Equation of State  

NASA Astrophysics Data System (ADS)

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

Crockett, Scott; Greeff, Carl

2009-06-01

317

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

318

Anisotropy of the magnetic susceptibility of gallium  

USGS Publications Warehouse

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

Pankey, T., Jr.

1960-01-01

319

Thermodynamic binding constants for gallium transferrin  

SciTech Connect

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

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

1983-01-18

320

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

321

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

322

Gallium nitride ultraviolet optical modulators  

NASA Astrophysics Data System (ADS)

In narrower band gap semiconductors researchers have exploited the ability to manipulate the exciton resonance via the Quantum Confined Stark Effect to make a variety of different types of optical modulators at infrared wavelengths. In this thesis, the large exciton binding energy of Gallium Nitride is used as the basis for ultraviolet optical modulators without the need for quantum confinement. A 5 x 5 array of UV optical modulators at 360 nm was fabricated. The modulators operated in a transverse geometry and consisted of a GaN active layer surrounded by transparent AlGaN insulating and electrical contact layers. The typical thickness of the GaN layer was 0.4 um so the effects of the electric field on the exciton resonance could be directly observed. A hydrogenic model for the bulk exciton was assumed. The applied electric field opposed the attractive coulomb potential between the electron and hole and broadens the exciton resonance. This results in more or less light through the device depending on the spectral position. To understand the magnitude of the applied field within the device structure a 1D Poisson Solver was used. Spontaneous polarization and piezoelectric effects due to lattice strain between the AlGaN and GaN layers were included in the model and were found to have influence on the device at lower operating voltages. In the electric field modulated devices a contrast ratio of about 20 percent was obtained. In thermally modulated devices, at low frequencies less than 200 Hz large shifts in the band edge led to large contrast ratios as expected. The temperature dependence of the device followed the Varshni relationship and allowed the magnitude of the temperature shift to be quantified. At higher frequencies from 1 kHz to 120 kHz an optical modulation of ˜5 percent was readily observed and was attributed to electronic effects. The limitation of 100 kHz was equipment related and it is conjectured that the modulation bandwidth would extend into the MHz.

Oberhofer, Andrew Edward

323

Spectroscopic Characterization and 3-MICROMETER CW Laser Operation of ERBIUM(3+):GADOLINIUM(3) GALLIUM(5) OXYGEN(12) and ERBIUM(3+):YTTRIUM(3) SCANDIUM(2) GALLIUM(3) OXYGEN(12)  

NASA Astrophysics Data System (ADS)

The spectroscopic and 3-?m laser properties of rm Er^{3+ }{:}Gd_3Ga_5O_{12 } and rm Er^{3+} {:}Y_3Sc_2Ga_3O_{12 } are investigated. The Judd-Ofelt Theory is applied to calculate radiative lifetimes, branching ratios, and radiative quantum efficiencies. The results reveal radiative lifetimes significantly longer than those actually observed for the ^4I_ {11/2}, ^4I_{9/2} , and ^4S_{3/2 } states, which indicate that strong quenching processes operate in these media. Radiative quantum efficiencies of 24% and 32% are observed from the ^4I _{11/2} state for GGG and YSGG, respectively. The role of upconversion is examined in an experiment in which the luminescence which occurs from the ^4S_{3/2} and ^4I_{9/1} states following chopped, cw pumping is analyzed in two time domains: that resulting from direct excitation and that resulting following upconversion-induced excitation. The ratio of upconversion-induced luminescence to pump-induced luminscence is quantified and applied to a simplified rate model, from which values of the ^4I_ {13/2} and ^4I _{11/2} upconversion coefficients, alpha_1 and alpha _2, are calculated. The calculated alpha_1 is typically larger than the calculated alpha_2, which partially explains the mechanism by which cw laser oscillation occurs. The 3-?m laser properties of Er:GGG and Er:YSGG are investigated using monolithic laser resonators. The lasers are pumped directly into the ^4I_{11/2} upper state near 0.97 ?m by either a Ti:sapphire or InGaAs diode laser. Greater than 0.5-W of 2.79-?m laser emission and nearly 0.3-W of 2.82-?m emission are observed from diode-pumped Er:YSGG and Er:GGG, respectively. The efficiencies and properties of the two host materials are typically very similar, yet YSGG categorically operates more efficiently than GGG. The spectral and spatial characteristics of the emission are also observed. The lasers typically operate on four or five longitudinal modes. Tunable, single-frequency emission is demonstrated from Er:YAG at 2.94-mu m. TEM_{00}-mode operation from GGG and YSGG is observed under Ti:sapphire -pumped conditions; multimode operation is observed from the diode-pumped system.

Dinerman, Bradley Jay

324

Overstepping the garnet isograd: a comparison of QuiG barometry and thermodynamic modeling  

NASA Astrophysics Data System (ADS)

The consequences of overstepping the garnet isograd reaction have been investigated by comparing the composition of garnet formed at overstepped P-T conditions (the overstep or "OS" model) with the P-T conditions that would be inferred by assuming garnet nucleated in equilibrium with the matrix assemblage at the isograd (the equilibrium or "EQ" model). The garnet nucleus composition formed at overstepped conditions is calculated as the composition that produces the maximum decrease in Gibbs free energy from the equilibrated, garnet-absent, matrix assemblage for the bulk composition under study. Isopleths were then calculated for this garnet nucleus composition assuming equilibrium with the matrix assemblage (the EQ model). Comparison of the actual P-T conditions of nucleation (the OS model) with those inferred from the EQ model reveals considerable discrepancy between the two. In general, the inferred garnet nucleation P-T conditions (the EQ model) are at a lower temperature and higher or lower pressure (depending on the coexisting calcic phase(s)) than the actual (OS model) nucleation conditions. Moreover, the degree of discrepancy increases with the degree of overstepping. Independent estimates of the pressure of nucleation of garnet were made using the Raman shift of quartz inclusions in garnet (quartz-in-garnet or QuiG barometry). To test the validity of this method, an experimental synthesis of garnet containing quartz inclusions was made at 800 °C, 20 kbar, and the measured Raman shift reproduced the synthesis conditions to within 120 bars. Raman band shifts from three natural samples were then used to calculate an isochore along which garnet was presumed to have nucleated. Model calculations were made at several temperatures along this isochore (the OS model), and these P-T conditions were compared to those computed assuming equilibrium nucleation (the EQ model) to estimate the degree of overstepping displayed by these samples. A sample from the garnet isograd in eastern Vermont is consistent with overstepping of around 10 degrees and 0.6 kbar (affinities of around 2 kJ/mole garnet). A sample from the staurolite-kyanite zone in the same terrane requires overstepping of around 50 °C and 2-5 kbar (affinities of around 10-18 kJ/mole garnet). A similar amount of overstepping was inferred for a blueschist sample from Sifnos, Greece. These results indicate that overstepping of garnet nucleation reactions may be common and pronounced in regionally metamorphosed terranes, and that the P-T conditions and paths inferred from garnet zoning studies may be egregiously in error.

Spear, Frank S.; Thomas, Jay B.; Hallett, Benjamin W.

2014-09-01

325

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

326

X-ray spectroscopic identification of garnet from the placer deposits of the Taman peninsula  

NASA Astrophysics Data System (ADS)

Garnet from recent placer deposits of the Taman peninsula has been investigated by energy-dispersive X-ray fluorescence microanalysis and X-ray absorption near-edge structure (XANES) spectroscopy. Energy-dispersive X-ray fluorescence microanalysis showed that the chemical composition of the garnet under study corresponds to pyrope-almandine-spessartine series. The Fe K-edge X-ray absorption spectra of garnet have been recorded using a Rigaku R-XAS laboratory spectrometer. Iron K-edge XANES spectra for two iron-containing garnet minals (components), almandine and andradite, have been calculated using the full multiple-scattering and finite-difference methods. Based on a comparison of the experimental and theoretical Fe K-XANES spectra, it is concluded that recent magnetite-garnet placer deposits of the Taman peninsula contain garnet in the form of almandine.

Rodina, I. S.; Kravtsova, A. N.; Soldatov, A. V.; Yalovega, G. E.; Popov, Yu. V.; Boyko, N. I.

2013-12-01

327

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

328

OH and H2O of garnets in diamond-bearing and diamond-free garnet-clinopyroxene rocks from the Kumdy-kol area, Kokchetav Massif  

NASA Astrophysics Data System (ADS)

Garnet-clinopyroxene (Grt-Cpx) rocks consisting mainly of Grt + Na-poor Cpx + calcite with various proportions, occur in the Kumdy-kol area. Diamond-bearing Grt-Cpx rock was first reported by Sobolev and Shatsky (1990) and has been well-known as one of the Kokchetav diamond-bearing rocks. UHP evidence, e.g., coesite exsolution from supersilicic titanite, was discovered also in the diamond-free Grt-Cpx rock (Inoue and Ogasawara, 2003). Presence/lack of diamond in Grt-Cpx rocks is one of important features to understand the stability of diamond in the Kokchetav UHP calcsilicate and carbonate rocks. We focused on OH and H2O in garnets in two types of Grt-Cpx rock to clarify fluid conditions during UHP metamorphism. One of the samples, the diamond-bearing Grt-Cpx rock (sample no. 25018; provided by Prof. H.-P. Schertl) is composed of two monomineralic layers, Grt-layer and Cpx-layer, with minor amounts of rutile and calcite. Coarse-grained diamond (up to 0.15 mm across) is included in garnet. Another Grt-Cpx rock, diamond-free one (sample no. XX16) shows a glanoblastic texture, and consists of Grt (30 %) + Cpx (30 %) + calcite (30 %) × titanite (5 %) with exsolved coesite-needles and plates. The precursor supersilicic compositions of titanite indicate six-coordinated Si at UHP conditions (Ogasawara et al, 2002; Sakamaki and Ogasawara, IGR in press). To understand the fluid environments during the formation of these two calcsilicate rocks, we chose garnets and conducted micro FT-IR spectroscopy. IR spectra of garnets in the diamond-bearing Grt-Cpx rock showed OH bands at 3430 and 3570 cm-1, sometimes with a week band at 3675 cm-1. The absorption band at 3570 cm-1 is the strongest and is sharp, whereas the band at 3430 cm-1 is broad. IR spectra of garnets in diamond-free one show strong OH bands at 3400 and 3555 cm-1, sometimes with week bands at 3590 and 3640 cm-1. The OH band at 3555 cm-1 is the strongest and is sharp, whereas the band at 3400 cm-1 is broad. IR analyses of garnets in the Grt-Cpx rocks show bimodal spectra; the relatively sharp band at ~3550 cm-1 and the broad band at ~3400 cm-1. The former band is attributed to OH in garnet structure and the latter one molecular H2O. The similar bimodal spectra were obtained from garnet in diamond-bearing dolomite marble. When we regard the total absorption at the range of 3100-3750 cm-1 as structural OH, the garnets in diamond-bearing Grt-Cpx rock contain 797 to 2506 ppm wt. H2O, and those in the diamond-free Grt-Cpx rock contain 679 to 2169 ppm wt. H2O. To evaluate the absorption spectra of the garnets in the Grt-Cpx rocks, we analyzed the garnet of different origin, Cr- and pyrope-rich garnet in mantle peridotite from the Garnet Ridge, northern Arizona. This peridotitic garnet shows a single-modal absorption band of OH at 3575 cm-1. No molecular H2O band was detected. Such results suggest that the environment during Kokchetav UHP metamorphism of calcsilicate may be saturated in H2O in contrast with the peridotitic garnet from the Garnet Ridge. The molecular H2O in the garnets of the Kokchetav Grt-Cpx rocks probably is submicron fluid inclusions trapped during UHP metamorphism. We thank Prof. H.-P. Schertl for providing us a very precious sample, diamond-bearing garnet-clinopyroxene rock.

Sakamaki, K.; Ogasawara, Y.

2013-12-01

329

Magneto-optical imaging using a garnet indicator film prepared on glass substrates  

Microsoft Academic Search

We observed the magnetic domains of a magnetic card by using the bismuth-substituted yttrium iron garnet (Bi-YIG; Bi1Y2Fe5O12) thin films as the indicator films. The magnetic domains’ dependence on the preparation conditions of the garnet thin film crystals was visualized by using a magneto-optical microscope. Garnet thin films were fabricated on glass substrates using a metal-organic decomposition method (MOD). We

Hanju Lee; Taedong Kim; Songhui Kim; Youngwoon Yoon; Seungwhan Kim; Arsen Babajanyan; Takayuki Ishibashi; Barry Friedman; Kiejin Lee

2010-01-01

330

The depth of the spinel to garnet transition at the peridotite solidus  

Microsoft Academic Search

We have determined the pressure and temperature of the spinel–garnet transition close to the solidus of fertile and depleted peridotite from a combination of synthesis, sandwich and garnet-seeded experiments. Garnet is unstable in MORB-Pyrolite below 2.8 GPa (depths <85 km) at a solidus temperature of 1470°C. In Tinaquillo Lherzolite, which is related to MORB-Pyrolite by about 7% fractional melting, the

J. Andrew C. Robinson; Bernard J. Wood

1998-01-01

331

Structural, electronic, and dynamical properties of amorphous gallium arsenide: a comparison between two topological models  

E-print Network

Structural, electronic, and dynamical properties of amorphous gallium arsenide: a comparison of amorphous gallium arsenide. Using the recently­proposed ``activation­ relaxation technique'' and empirical

Lewis, Laurent J.

332

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

333

Targeting Gallium to Cancer Cells through the Folate Receptor  

Microsoft Academic Search

The development of gallium(III) compounds as anti-cancer agents for both treatment and diagnosis is a rapidly developing ! eld of research. Problems remain in exploring the full potential of gallium(III) as a safe and successful therapeutic agent or as an imaging agent. One of the major issues is that gallium(III) compounds have little tropism for cancer cells. We have combined

Nerissa Viola-Villegas; Anthony Vortherms; Robert P. Doyle

334

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

335

Solid-State Gadolinium-Magnesium Hydride Optical Switch R. Armitage  

E-print Network

Solid-State Gadolinium-Magnesium Hydride Optical Switch R. Armitage Lawrence Berkeley National The optical switching properties of gadolinium-magnesium hydride have been demonstrated in a solid and reflecting states. Keywords: gadolinium-magnesium; electrochromic hydride; optical switching device. 2 #12;A

336

The effect of demagnetization on the magnetocaloric properties of gadolinium  

NASA Astrophysics Data System (ADS)

Gadolinium displays a strong magnetocaloric effect at temperatures close to room temperature making it useful in the field of room temperature magnetic refrigeration. We discuss the importance of including the effects of the demagnetization field when considering the magnetocaloric properties of gadolinium. The adiabatic temperature change ?Tad of gadolinium sheets upon application of a magnetic field has been measured at a range of applied magnetic fields and sample orientations. A significant dependence of ?Tad on the sample orientation is observed. This can be accounted for by the demagnetization factor. Also, the temperature dependence of ?Tad has been measured experimentally and modeled by mean field theory. Corrections to mean field theory modeling due to the demagnetization field are proposed and discussed.

Bahl, C. R. H.; Nielsen, K. K.

2009-01-01

337

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

338

(Data in kilograms of gallium content, unless noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1995. Two companies in  

E-print Network

.S. gallium consumption, were valued at about $3.5 million. Gallium arsenide (GaAs) components represented (MFN) Non-MFN2 12/31/95 12/31/95 Gallium metal 8112.91.1000 3.7% ad val. 25.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. 25.0% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free

339

Ultrathin Iron (Fe) - Gallium Arsenide (GaAs) Layer Structures for Wideband Microwave Devices  

NASA Astrophysics Data System (ADS)

There has been increasing interest and activity in the preparation and device application of ultrathin Iron (Fe) films grown on compound semiconductor substrates such as gallium arsenide (GaAs) and zinc selenide (ZnSe). In this paper a brief review on the preparation and characterization of such Fe-GaAs layer structures using the MBE technique, and realization of wideband microwave band-stop filters is presented. The Fe film-based devices possess an important advantage over their yttrium iron garnet (YIG) film-based counterparts in that for a given operating carrier frequency the former requires a much lower bias magnetic field. This is so because the saturation magnetization of the Fe films is more than one order of magnitude larger than that of YIG films. Accordingly, a much higher device operating carrier frequency with large electronic tunability may be achieved more readily in practice using the Fe-GaAs layer structures. An integrated-type microwave band-stop filter was fabricated in such layer structure through a sequence of chemical etching processes to form a microstrip transmission line. A frequency tuning range as large as 10.0 to 33.0 GHz has been accomplished. The experimental results are shown to be in excellent agreement with the theoretical prediction.

Tsai, Chen S.; Lee, Chin C.; Wu, Wei

2001-04-01

340

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

341

Ohmic contacting schemes to gallium arsenide devices  

NASA Astrophysics Data System (ADS)

The goal of this project was to design ohmic contacting schemes to gallium arsenide that would sustain 400C for 1 hour and 600C for 15 minutes without significant degradation. Our approach uses a generic contacting scheme calling for two thin-film layers between the semiconducting substrate and the metal overlayer: (1) a contacting layer adjacent to the semiconductor that determines the electrical properties of the contact, and (2) a diffusion barrier layer adjacent to the metal overlayer that assures the thermal stability of the contact. A contact designed according to this scheme (silver overlayer, pure tungsten or tungsten-nitrogen layer as the diffusion barrier, and a magnesium-doped platinum film for the contacting layer to p-type gallium arsenide) changes little upon annealing at 550C for 5 hours. The contact resistivity is on the order of 1E-3 ohm sq cm or less.

1987-08-01

342

Photonuclear Reaction Cross Sections for Gallium Isotopes  

E-print Network

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

Serkan Akkoyun; Tuncay Bayram

2014-09-08

343

Graphene on gallium arsenide: Engineering the visibility  

Microsoft Academic Search

Graphene consists of single or few layers of crystalline ordered carbon atoms. Its visibility on oxidized silicon (Si\\/SiO2) enabled its discovery and spawned numerous studies of its unique electronic properties. The combination of graphene with the equally unique electronic material gallium arsenide (GaAs) has up to now lacked such easy visibility. Here we demonstrate that a deliberately tailored GaAs-aluminum arsenide

M. Friedemann; K. Pierz; R. Stosch; F. J. Ahlers

2009-01-01

344

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

345

a Gallium Multiphase Equation of State  

NASA Astrophysics Data System (ADS)

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

Crockett, Scott D.; Greeff, Carl W.

2009-12-01

346

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

347

Gallium Nitride Schottky betavoltaic nuclear batteries  

Microsoft Academic Search

Gallium Nitride (GaN) Schottky betavoltaic nuclear batteries (GNBB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN Schottky diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits ? particles, is loaded on the GaN Schottky diodes to

Min Lu; Guo-guang Zhang; Kai Fu; Guo-hao Yu; Dan Su; Ji-feng Hu

2011-01-01

348

Silicon solution for gallium arsenide IC's  

SciTech Connect

An analytical discussion is presented of the development of a new type of integrated circuit design. In this new technology, gallium arsenide is grown on silicon. The result is that the best characteristics of both semiconductors are combined. At the present time, the technology is still in the laboratory phase of development, but it appears likely that commercialization will be accomplished in the near future. 2 figures.

Robinson, A.L.

1986-05-16

349

Gallium-assisted transfer hydrogenation of alkenes.  

PubMed

We report a rare case of alkene transfer hydrogenation using a main-group compound instead of a transition-metal complex as catalyst. We disclosed that 1,4-cyclohexadiene can be used as H2 surrogate towards olefin reduction in the presence of [IPrGaCl2 ][SbF6 ]. Hydrogenative cyclizations have also been carried out because this cationic gallium complex is also a potent hydroarylation catalyst. PMID:25213294

Michelet, Bastien; Bour, Christophe; Gandon, Vincent

2014-10-27

350

Gallium arsenide for devices and integrated circuits  

SciTech Connect

Gallium Arsenide has long been hailed as the material of the future and it is only in recent years that the technology associated with its growth and processing has matured to the point where IC production can be contemplated at the industrial level. This point has now been reached and the electronics industries in Europe, the USA and Japan are actively moving from research activities into product development using this and related material. The text is divided into 15 chapters: Gallium Arsenide: Physical and Transport Properties; Liquid phase and Vapour Phase Epitaxy of GaAs and Related Compounds; Expitaxial Growth and GaAs: MBE and MOCVD; Characterization of GaAs I: Electrical Techniques; Characterization of GaAsII: Ion Beam Analysis; Ion Implantation; Wet and Dry Processing GaAs; Microwave and Millimetre - Wave Diodes; GaAs Mesfet's and High Electron Mobility Transistors (HEMT); Optoelectronic Devices and Components; Gallium Arsenide Monolithic Microwave Integrated Circuits; GaAs Digital Integrated Circuits; III-V Semiconductors for Solar Cells.

Morgan, D.V.; Thomas, H.

1986-01-01

351

One-dimensional zigzag gallium nitride nanostructures  

NASA Astrophysics Data System (ADS)

Two one-dimensional (1D) single-crystalline gallium nitride (GaN) nanostructures with periodic zigzag (type I) and diameter-modulated (type II) shapes have been synthesized by passing through ammonia over a mixture of gallium and gallium oxide (Ga2O3) powders held at elevated temperature. The process was catalyzed by the dispersion of thio-capped Au nanoparticles on the substrate onto which GaN nanostructures were condensed. The transformation between these two nanostructure morphologies was also observed. A possible growth model for the zigzag-shaped nanostructures is proposed, in which the formation of the zigzag nanostructures results from the construction of two different nanoscale unit cells. This work provides an avenue to a group of 1D nanostructures with a zigzag shape. The possibility to form 1D nanostructures yet to be discovered by changing the stacking direction of the (0001) plane will facilitate the fabrication of nanoscale functional devices as well as our understanding of the growth behavior of nanoscale crystallites.

Zhou, X. T.; Sham, T. K.; Shan, Y. Y.; Duan, X. F.; Lee, S. T.; Rosenberg, R. A.

2005-05-01

352

Crystallization of pegmatites: Insights from chemistry of garnet, Jacumba pegmatites, San Diego County, California  

NASA Astrophysics Data System (ADS)

Systematic mineral and textural variations from the border zone to the core of a zoned pegmatite sheet may reflect the kinetic or equilibrium fractionation processes that occurred during sequential crystallization of the pegmatite magma. Rhythmic layering, also named 'line rock', is a salient textural feature of world famous San Diego Co. pegmatites, that consists of alternating garnet × tourmaline layers and albite - quartz layers, mm's to cm's thick. Slowly diffusing, incompatible elements in the felsic magma including B, Fe, and Mn may become enriched in boundary layers formed ahead of rapidly crystallized quartzo-felspathic assemblages. This study explores whether the chemistry of garnet concentrated in the border and foot-wall zones and dispersed in the graphic feldspar, core, and pocket zones of Garnet Ledge pegmatite, Jacumba district, might fingerprint the diffusion-controlled oscillatory boundary layers. The lithium-cesium-tantalum (LCT) Jacumba pegmatite district, late product of the Eastern Peninsular Ranges Batholith, consists of numerous subparallel dikes, 3 to 7 m thick, intruding pre-batholitic metasedimentary rocks. The composite aplite-pegmatite dikes are texturally diverse. Comb-textured tourmaline, other unidirectional textures, garnet × tourmaline 'line rock', and coarse graphic K-feldspar crystals occur in the outer zones, followed by massive feldspar-quartz cores, vuggy cleavlandite- euhedral garnet, and miarolitic cavities. The Jacumba pegmatites have produced gem spodumene, beryl, and garnet from several open cuts such as the Beebe Hole and Pack Rat - Garnet Ledge workings. Systematic mineralogical and textural variations, and SEM-EDS garnet compositions were recorded from border to core at Garnet Ledge outcrop and thin section scale, focusing on continuous traverses across the line rock. Garnet from Garnet Ledge belongs to the spessartine-almandine series (Sp42 to Sp65) with minor contents of Mg, Ca, and Ti, consistent with garnet compositions reported worldwide from similar LCT pegmatites. On average, the core and pocket garnet has slightly higher Mn contents (Sp 54×4.5%) than 'line rock' garnet (Sp 49.4×1.2%), but the Mn increase is not continuous across pegmatite zones. Preliminary compositions of the 'line-rock' garnet suggest rhythmic oscillations of Mn/(Mn+Fe+Mg) values, that appear to correlate 1) positively with garnet+tourmaline abundance and grain size and 2) negatively with garnet:tourmaline abundance ratio. 'Line rock' garnet, that grew in an undersaturated liquid, tends to have Mn-rich cores and Fe-rich rims. However euhedral garnet from inner zones, that grew in the presence of an exsolved fluid phase, lacks internal zoning. In summary, the chemistry of magmatic garnet is a sensitive recorder of diffusion-controlled, mm-to-cm rhythmic changes occurring during rapid crystallization of an undersaturated granitic liquid. In contrast, less variable compositions of core-zone and pocket-zone garnets reflect equilibrium with a low density, fluid phase exsolved at late stages of crystallization.

Thompson, M.; Sirbescu, M. C.

2013-12-01

353

Experimental and computational study of copper-gadolinium alloy evaporation  

Microsoft Academic Search

We report an experimental study of the expansion of a gadolinium-copper atomic vapor mixture in vacuum and the comparison with a test-particle Monte Carlo simulation. This simulation gives a description of collision relaxation in the binary case, taking account of excited metastable levels. The metal alloy was evaporated by a focused electron gun. We measured the net mass flow rate,

S. Chatain; C. Gonella; P. Roblin

1998-01-01

354

Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes  

E-print Network

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

E. May; M. Thoennessen

2012-01-19

355

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

356

Gadolinium-enhanced magnetic resonance imaging in acute myocardial infarction  

Microsoft Academic Search

To investigate the clinical application of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) in the management of acute myocardial infarction (AMI), we examined 44 patients with AMI within 1 month after onset. Enhanced images were classified into 4 types: nontransmural (type 1), transmural and homogeneous (type 2), transmural and marginal (type 3), and no enhancement (type 4). Each enhancement

Chiaki Yokota; Hiroshi Nonogi; Shunichi Miyazaki; Yoichi Goto; Masakazu Maeno; Satoshi Daikoku; Akira Itoh; Kazuo Haze; Naoaki Yamada

1995-01-01

357

On the magnetomechanical damping in terbium, gadolinium, iron and nickel  

Microsoft Academic Search

The magnetomechanical behaviour of iron, nickel, gadolinium and terbium is reviewed and it is shown that the classification by Roberts and Barrand (1969) into iron-like or nickel-like materials is unsatisfactory. Magnetic damping is caused by the movement of 90° domain walls over internal stress barriers. Dislocations provide an obvious source of internal stress and a simple model of domain walls

C. P. Burdett

1970-01-01

358

The Elastic Constants of Gadolinium, Terbium and Erbium  

Microsoft Academic Search

The five single crystal elastic constants of gadolinium, terbium and erbium have been measured within the temperature range 4.2-300 K. Contributions to the elastic constants due to domain and spin rotation effects were reduced and in some cases eliminated altogether by applying a magnetic field of 2.5 T along the magnetic easy directions.

S. B. Palmer; E. W. Lee; M. N. Islam

1974-01-01

359

Solid-state gadolinium-magnesium hydride optical switch  

NASA Astrophysics Data System (ADS)

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

Armitage, R.; Rubin, M.; Richardson, T.; O'Brien, N.; Chen, Yong

1999-09-01

360

Gadolinium chloride pretreatment ameliorates acute cadmium-induced hepatotoxicity.  

PubMed

Cadmium is a known industrial and environmental pollutant. It causes hepatotoxicity upon acute administration. Features of cadmium-induced acute hepatoxicity encompass necrosis, apoptosis, peliosis and inflammatory infiltration. Gadolinium chloride (GdCl3) may prevent cadmium-induced hepatotoxicity by suppressing Kupffer cells. The effect of GdCl3 pretreatment on a model of acute cadmium-induced liver injury was investigated. Male Wistar rats 4-5 months old were injected intraperitoneally with normal saline followed by cadmium chloride (CdCl2; 6.5 mg/kg) or GdCl3 (10 mg/kg) followed by CdCl2 (6.5 mg/kg; groups I and II, respectively). Rats of both the groups were killed at 9, 12, 16, 24, 48 and 60 h after cadmium intoxication. Liver sections were analyzed for necrosis, apoptosis, peliosis and mitoses. Liver regeneration was also evaluated by tritiated thymidine incorporation into hepatic DNA. Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also determined. Hepatic necrosis, hepatocyte and nonparenchymal cell apoptosis and macroscopic and microscopic types of peliosis hepatis were minimized by gadolinium pretreatment. Serum levels of AST and ALT were also greatly diminished in rats of group II. Tritiated thymidine incorporation into hepatic DNA was increased in gadolinium pretreatment rats. Kupffer cell activation was minimal in both the groups of rats. Gadolinium pretreatment attenuates acute cadmium-induced liver injury in young Wistar rats, with mechanisms other than Kupffer cell elimination. PMID:22173957

Kyriakou, Loukas G; Tzirogiannis, Konstantinos N; Demonakou, Maria D; Kourentzi, Kalliopi T; Mykoniatis, Michael G; Panoutsopoulos, Georgios I

2013-08-01

361

Electronic Transport Characteristics of Gallium Nitride Nanowire-based Nanocircuits  

E-print Network

of gallium nitride based three terminal field effect transistors fabricated via electron beam lithography and drain contacts were patterned using electron beam lithography, with Ti/Au used for the conducting sourceElectronic Transport Characteristics of Gallium Nitride Nanowire-based Nanocircuits V.M. Ayres, B

Ayres, Virginia

362

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

363

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

364

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

365

Ultrahigh-Pressure Orogenic Garnet Peridotites: A Prospective View  

NASA Astrophysics Data System (ADS)

Mantle-derived garnet peridotites are a minor component in many ultrahigh-pressure (UHP) terranes that formed during continental subduction and collision. These mantle rocks contain trace amounts of zircon, and micron-size inclusions; the constituent minerals exhibit pre- and post-subduction microstructures including polymorphic transformation and mineral exsolution. Recent studies on orogenic peridotites have yielded numerous significant findings: (1) Many orogenic peridotites were derived from a depleted, metasomatized mantle or crustal cumulate, and were later subjected to subduction-zone UHP metamorphism. (2) Some peridotites preserve a record of ultradeep origin revealed by mineral exsolution and persistence of UHP polymorphs. (3) Several peridotites contain dense hydrous magnesian silicates that are stable only at mantle depths. (4) Some garnet peridotites and their host continental crust underwent coeval subduction-zone UHP metamorphism under P-T conditions characterized by low thermal gradients (< 5°C/km), based on SHRIMP U-Pb ages of zircon separates from both rock types. How we distinguish the petrochemical processes taking place in a mantle wedge setting from those deeply subducted ultramafic rocks of the continental lithosphere remains to be challenged. It requires detailed examination of micron-size minerals, exsolution textures and polymorphic transformations using novel techniques involving high spatial, temporal, and energy resolution. For example, garnet nodules in the Western Gneiss Region, Norway, formed prior to emplacement in the Caledonian subduction zone. Numerous lines of evidence suggest continental subduction depths > 200 km for some UHP terranes; these include the occurrence of supersilicic titanite in marble, exsolution lamellae of Qtz or K-fsp ± Phn in diopside from diamond-bearing marble and gneiss, and nanometric inclusions of aragonite and magnesite in microdiamonds from the Kokchetav massif, and ?- PbO2 - type TiO2 between multiple twinned rutile crystals in both diamond-bearing felsic rocks from the Erzgebirge and coesite-bearing Dabie eclogites.

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

2006-12-01

366

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

NASA Astrophysics Data System (ADS)

The radiation susceptibility of garnet structure types (A 3B 2(XO 4) 3, Ia3d, Z=8) has been examined by 1.0 MeV Kr 2+ irradiation with in situ transmission electron microscopy over the temperature range of 50-1070 K. The target garnets included five natural garnets: almandine, andradite, pyrope, grossular and spessartine, and five synthetic garnets incorporating various contents of actinides. The synthetic garnets were silicates (N-series) and ferrate-aluminates (G-series). The critical amorphization temperature ( Tc), above which amorphization does not occur, were determined to be 1050 K for N77, 1130 K for N56, 1100 K for G3, 890 K for G4 and 1030 K for andradite. Tc of the synthetic garnets increased with increasing mass density of the target and as the electronic-to-nuclear stopping power ratio decreased. During ion irradiation of the G3 garnet at a temperature of 1023 K near the Tc, nano-crystals were produced in which the unit-cell parameter of the original garnet was halved (˜0.64 nm) as a result of a radiation-induced recrystallization process, without evidence for ordering of the cations.

Utsunomiya, S.; Wang, L. M.; Yudintsev, S.; Ewing, R. C.

2002-06-01

367

Garnet Yield Strength at High Pressures and Implications for Upper Mantle and Transition Zone Rheology  

SciTech Connect

Garnet helps control the mechanical behavior of the Earth's crust, mantle, and transition zone. Here, measurements are presented suggesting that garnet, long considered to be a high-viscosity phase, is actually weaker than the other dominant components in the transition zone. The mechanical behavior of garnet at high pressures was examined using radial diffraction techniques in the diamond anvil cell. The yield strength of grossular garnet was inferred from synchrotron X-ray measurements of differential lattice strains. The differential stress was found to increase from 1.3 ({+-}0.6) GPa at a hydrostatic pressure 5.8 ({+-}1.1) GPa to 4.1 ({+-}0.4) GPa at 15.7 ({+-}1.0) GPa, where it was level to 19 GPa. The strength results are consistent with inferred strength values for majorite garnet from measurements in the diamond cell normal geometry, bolstering the idea that garnet-structured materials may all have similar strengths. In this low-temperature, high differential stress regime, garnet is shown to be significantly weaker than anhydrous ringwoodite and to have a strength similar to hydrous ringwoodite. This result suggests that the presence of water in the transition zone may not be required to explain a weak rheology, and therefore models of transition zone behavior built assuming that garnet is the high-strength phase may need to be revised.

Kavner,A.

2008-01-01

368

Atomistic Modeling of Native Point Defects in Yttrium Aluminum Garnet Crystals  

E-print Network

for the purpose of exploiting its potential in high-temperature applications.11­13 The diffusion and defectAtomistic Modeling of Native Point Defects in Yttrium Aluminum Garnet Crystals Maija M. Kuklja point defects in yttrium aluminum garnet (YAG) are studied in the framework of the pair

Pandey, Ravi

369

An Occurrence of Metastable Cristobalite in High-Pressure Garnet Granulite  

E-print Network

-Ming Chou, Robert J. Bodnar High-pressure (0.8 gigapascals) granulite facies garnet from Gore Mountain, New inside the large, almandine-pyrope garnets of the Barton Mine on the north slope of Gore Mountain, in the south-central Adirondack Highlands of New York. It occurs exclusively in mul- tiple solid inclusions

Bodnar, Robert J.

370

Computational modelling of Er(3+): Garnet laser materials  

NASA Technical Reports Server (NTRS)

The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host for 1.5 micron laser operation, GSGG or YSAG as the best host for a 2.8 micron operation, and LuGG as the best host for an upconversion material.

Spangler, Lee H.

1994-01-01

371

Enhanced spin pumping at yttrium iron garnet/Au interfaces  

SciTech Connect

Spin injection across the ferrimagnetic insulator yttrium iron garnet (YIG)/normal metal Au interface was studied using ferromagnetic resonance. The spin mixing conductance was determined by comparing the Gilbert damping parameter {alpha} in YIG/Au and YIG/Au/Fe heterostructures. The main purpose of this study was to correlate the spin pumping efficiency with chemical modifications of the YIG film surface using in situ etching and deposition techniques. By means of Ar{sup +} ion beam etching, one is able to increase the spin mixing conductance at the YIG/Au interface by a factor of 5 compared to the untreated YIG/Au interface.

Burrowes, C.; Heinrich, B.; Kardasz, B.; Montoya, E. A.; Girt, E. [Physics Department, Simon Fraser University, 8888 University Dr., Burnaby, British Columbia V5A 1S6 (Canada); Sun Yiyan; Song, Young-Yeal; Wu Mingzhong [Physics Department, Colorado State University, Fort Collins, Colorado 80523 (United States)

2012-02-27

372

Damping in Yttrium Iron Garnet Nanoscale Films Capped by Platinum  

NASA Astrophysics Data System (ADS)

Strong damping enhancement in nm-thick yttrium iron garnet (YIG) films due to Pt capping layers was observed. This damping is substantially larger than the expected damping due to conventional spin pumping, is accompanied by a shift in the ferromagnetic resonance field, and can be suppressed by the use of a Cu spacer in between the YIG and Pt films. The data indicate that such damping may originate from the ferromagnetic ordering in Pt atomic layers near the YIG/Pt interface and the dynamic exchange coupling between the ordered Pt spins and the spins in the YIG film.

Sun, Yiyan; Chang, Houchen; Kabatek, Michael; Song, Young-Yeal; Wang, Zihui; Jantz, Michael; Schneider, William; Wu, Mingzhong; Montoya, E.; Kardasz, B.; Heinrich, B.; te Velthuis, Suzanne G. E.; Schultheiss, Helmut; Hoffmann, Axel

2013-09-01

373

Low-field magnetodielectric effect in terbium iron garnets  

NASA Astrophysics Data System (ADS)

Materials exhibiting low-field magnetoelectric and magnetodielectric (MD) effects are necessary for utilization of these effects in multifunctional devices. Since large magnetic fields (H) or electric fields (E) are required to produce any significant effect in existing single-phase magnetoelectrics, recent efforts have been largely devoted to the investigation of laminates or thin film composites made of piezoelectric and magnetostrictive materials. In this work, we report large MD effect ??/?˜3% at remarkably low fields (H<2kOe) in a single-phase material, terbium iron garnet. Our results suggest a route towards future applications of the MD effect in advanced devices.

Hur, N.; Park, S.; Guha, S.; Borissov, A.; Kiryukhin, V.; Cheong, S.-W.

2005-07-01

374

GALLIUM--2003 28.1 References that include a section mark () are found in the Internet  

E-print Network

to propel the increase in gallium consumption. Gallium arsenide (GaAs) wafers, however, continuedGALLIUM--2003 28.1 1 References that include a section mark (§) are found in the Internet References Cited section. GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared

375

Microstructures of gallium nitride nanowires synthesized by oxide-assisted method  

E-print Network

), germanium (Ge), gallium arsenide (GaAs) and gallium phosphide (GaP). In the fabricating pro- cess, oxidesMicrostructures of gallium nitride nanowires synthesized by oxide-assisted method W.S. Shi, Y Received 10 March 2001; in ®nal form 3 August 2001 Abstract Gallium nitride (GaN) nanowires were

Zheng, Yufeng

376

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

377

Contrasting behaviour of anthropogenic gadolinium and natural rare earth elements in estuaries and the gadolinium input into the North Sea  

Microsoft Academic Search

All major rivers in northwestern Germany that flow into the North Sea, including the Weser River, display rare earth element (REE) patterns with large positive gadolinium (Gd) anomalies that indicate the presence of anthropogenic Gd derived from contrast agents used in magnetic resonance imaging. This microcontaminant cannot be removed by common sewage treatment technology and enters rivers and lakes with

Serkan Kulaksiz; Michael Bau

2007-01-01

378

The Preparation and Structural Characterization of Three Structural Types of Gallium Compounds Derived from Gallium (II) Chloride  

NASA Technical Reports Server (NTRS)

The three compounds Ga2Cl4(4-mepy)2 (1),[GaCl2(4-mepy)4]GaCl4x1/2(4-mepy); (2) and GaCl2(4-mepy)2(S2CNEt2); (3) (4-mepy= 4-methylpyridine) have been prepared from reactions of gallium (II) chloride in 4-methylpyridine and characterized by single-crystal X-ray analysis. Small variations in the reaction conditions for gallium(II) chloride can produce crystals with substantially different structural properties. The three compounds described here encompass a neutral gallium(II) dimer in which each gallium is four-coordinate, an ionic compound containing both anionic and cationic gallium complex ions with different coordination numbers and a neutral six-coordinate heteroleptic

Gordon, Edward M.; Hepp, Aloysius F.; Duraj. Stan A.; Habash, Tuhfeh S.; Fanwick, Phillip E.; Schupp, John D.; Eckles, William E.; Long, Shawn

1997-01-01

379

Magnetism in Mo-doped Yttrium Iron Garnet  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) is a synthetic garnet and ferrimagnetic, with chemical formula Y3Fe5O12. In YIG, five iron (III) ions occupy two octahedral and three tetrahedral sites, with the yttrium (III) ions coordinated by eight oxygen ions in an irregular cube. The iron ions in the two coordination sites exhibit different spins, resulting in magnetic behavior. Bulk YIG has been synthesized systematically by solid state reaction method. The formation of pure YIG have been investigated through X-ray diffraction (XRD) beginning from weighing in molar proportions of Y2O3 and Fe2O3, mixing and grinding, pre-sintering and final sintering at 1300 ^oC. XRD study shows that YIG exhibits cubic structure with lattice constant of about 12 å. Magnetization with varying field and temperature has been measured using a SQUID magnetometer. Magnetic measurement of Mo YIG has shown that magnetic moment increase initially and then decreases with Mo doping. Detailed results will be discussed in this presentation. This work is supported by National Science Foundation (Award Number DMR-0907037).

Khanra, S.; Kolekar, Y.; Langhoff, M.; Kahol, P.; Ghosh, K.

2013-03-01

380

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

381

Strong field processes inside gallium arsenide  

NASA Astrophysics Data System (ADS)

We demonstrated experimentally that the multiphoton ionization rate in gallium arsenide depends on the alignment of the laser polarization with respect to the crystal axis. We observed modulation in the ionization rate of a linearly-polarized 1900 nm laser beam directly by measuring its transmission while rotating the crystal, without Fourier analysis. We propose that the modulation in the ionization rate arises from periodic variation in the reduced carrier mass, as predicted by Keldysh theory. We show direct comparison of the experimental transmission modulation depth with Keldysh?s non-resonant ionization theory for solids. This opens up a novel method for non-invasive crystallography of semiconductor materials.

Golin, S. M.; Kirkwood, S. E.; Klug, D. D.; Villeneuve, D. M.; Rayner, D. M.; Trallero Herrero, C. A.; Corkum, P. B.

2014-10-01

382

Experimental study of the stability of cordierite and garnet in pelitic compositions at high pressures and temperatures  

Microsoft Academic Search

In pelitic rocks, under conditions of low fO2 and low fH2O, the stability of the mineral pair cordierite-garnet is limited by five univariant reactions. In sequence from high pressure and low temperature to high temperature and low pressure these are: cordierite+garnet? hypersthene+sillimanite+quartz, cordierite+garnet? hypersthene+sapphirine+quartz, cordierite+garnet? hypersthene+spinel+quartz and cordierite+garnet? olivine+spinel +quartz. In this sequence of reactions the Mg\\/Mg+Fe2+ ratio of all

B. J. Hensen; D. H. Green

1973-01-01

383

Compatibility of ITER candidate structural materials with static gallium  

SciTech Connect

Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400{degrees}C, corrosion rates are {approx}4.0, 0.5, and 0.03 mm/yr for type 316 SS, Inconel 625, and Nb-5 Mo- 1 Zr alloy, respectively. The pure metals react rapidly with gallium. In contrast to findings in earlier studies, pure iron shows greater corrosion than nickel. The corrosion rates at 400{degrees}C are {ge}88 and 18 mm/yr, respectively, for Armco iron and Nickel 270. The results indicate that at temperatures up to 400{degrees}C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The solubility data for pure metals and oxygen in gallium are reviewed. The physical, chemical, and radioactive properties of gallium are also presented. The supply and availability of gallium, as well as price predictions through the year 2020, are summarized.

Luebbers, P.R.; Michaud, W.F.; Chopra, O.K.

1993-12-01

384

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

385

Improved dissolution and chemical separation methods for Lu-Hf garnet chronometry  

NASA Astrophysics Data System (ADS)

Garnet-based Lu-Hf geochronology using conventional (HF-HNO3) dissolution methods may be compromised by full or partial digestion of Hf-rich zircon inclusions. This study integrates two complimentary methods to substantially reduce zircon digestion while assuring complete digestion of garnet and sample-spike equilibration. Handpicked garnet fractions are heat treated to >1000°C in an evacuated silica glass ampoule to anneal zircon inclusions and then dissolved with 12 M HCl at 210°C and cold 28 M HF. Analyses of heat-treated garnet (and their high-temperature breakdown products orthopyroxene-spinel-quartz) from Gore Mountain, New York, demonstrate the method is capable of complete dissolution of garnet and routinely achieving sample-spike equilibration. Independent analyses of annealed and unannealed zircons dissolved by HCl - cold HF demonstrate the benefit of heat treatment prior to dissolution. Analyses of zircon-rich garnets from peletic paragneisses of Labrador, Canada, show the potential of this method by returning Lu-Hf ratios commensurate with the degree of heat treatment. Finally, a complementary chemical separation method for Lu and Hf is presented that supports analysis of garnet by MC-ICP-MS.

Connelly, J. N.

2006-04-01

386

Lithospheric roots beneath western Laurentia: The geochemical signal in mantle garnets  

USGS Publications Warehouse

This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450??C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110-260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tEctonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.

Canil, D.; Schulze, D. J.; Hall, D.; Hearn, Jr. , B. C.; Milliken, S. M.

2003-01-01

387

Study of the provenance of Belgian Merovingian garnets by PIXE at IPNAS cyclotron  

NASA Astrophysics Data System (ADS)

Recent archaeological excavation in Belgium reveals one of the biggest Merovingian necropolis ever found in this country. This necropolis contains 436 tombs with a period of occupation of almost two centuries. Some of these tombs were very rich, especially two of them, and delivered an important funerary furniture. About 60 jewels inlaid with red garnets have been found, most of them of "cloisonné" style (namely about 450 garnets). The new extracted beam set-up of the IPNAS cyclotron (University of Liège, Belgium) has been improved in order to analyse by PIXE these garnets and try to determine their provenance. These analyses reveal that the garnets found in the necropolis of Grez-Doiceau are very homogeneous in composition (almandine garnets) and are coming almost from a unique source. These results have been compared to previous studies led in France during these past five years. This permits to identify the source of almandine garnet situated in India and to highlight differences in garnet supply between France and Belgium in Merovingian times.

Mathis, F.; Vrielynck, O.; Laclavetine, K.; Chêne, G.; Strivay, D.

2008-05-01

388

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

389

Characterization of semi-insulating gallium arsenide  

NASA Astrophysics Data System (ADS)

This project was established for the purpose of characterization of samples from melt grown single crystals of nominally undoped gallium arsenide, primarily such crystals as grown by the vertical zone melt (VZM) method at the Naval Research Laboratory. During this period electrical and optical samples were measured for 13 of these VZM-grown gallium arsenide. Measurements made at Western Washington University (WWU) under the terms of this project were in accordance with the Statement of Work provided at the project's outset: including near-infrared transmittance measurements for determination of neutral and ionized EL2 center concentrations, local vibrational mode (LVM) measurements in the mid-IR relative to carbon impurities, and measurements of dc electrical transport properties versus temperature. A program for growth of GaAs and other semiconductors by the VZM method began at NRL several years ago, and the practicality of this method for growing semi-insulating (SI) nominally undoped GaAs in a pBN crucible was demonstrated by Swiggard (1989) and in various subsequent papers.

Blakemore, John S.

1991-08-01

390

Ilmenite Exsolution in Xenolithic Garnets From the Hawaiian Hot Spot: Evidence for the Existance of High-titanium Garnets in the Earth's Mantle  

NASA Astrophysics Data System (ADS)

Oxide inclusions in a pyrope host were discovered in a single garnet clinopyroxenite xenolith (sample 115954-20 B; Jackson Collection, Smithsonian) from Salt Lake Crater, Oahu, Hawaii. These inclusions, ~ 5-6 ? m thick and 10 ? m long, appear to radiate from a point, rather than align along the <111> direction, as found previously by other authors (e.g., Haggerty, 1991b). In the same section there are other garnet grains that have ilmenite of the same morphology but along <111>. Electron microprobe analysis and Raman spectroscopy show that both types of inclusions are ilmenite (FeTiO3) with a large geikelite (MgTiO3) component, and minor amounts of Al3+, Cr3+, and Fe3+. Note that ilmenite does not occur as a discrete phase in the xenolith. Inclusions of ilmenite and rutile, have previously been found in host garnets from eclogitic and lherzolitic xenoliths in kimberlites and ultra-high pressure terrains. This is the first report of such occurrence from an oceanic hot spot source. Based on texture, we suggest that the ilmenite inclusions in garnet in the Hawaiian xenolith are of exsolution origin as opposed to an origin by epitaxal precipitation (as proposed by Wang et al, 1999). At the present time, because of the lack of appropriate experimental study it is difficult to speculate on the P,T conditions under which ilmenite exsolved from the garnet host. However, Van Roermund et al (2000) have hypothesized on crystal chemical grounds that such inclusions are the result of the break down of a high P,T `super-titanic' garnet to a lower P,T pyrope with exsolved ilmenite, in a similar fashion to the breakdown of `super-silicic' or majoritic garnet to pyrope with exsolved pyroxene.

Keshav, S.; Sowerby, J. R.; Sen, G.

2001-12-01

391

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

392

About a Gadolinium-doped Water Cherenkov LAGUNA Detector  

SciTech Connect

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

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

2010-11-24

393

Gadolinium-enhanced magnetic resonance angiography in brain death  

NASA Astrophysics Data System (ADS)

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

394

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

395

Ag enhances optical and switching properties of gadolinium hydride films  

Microsoft Academic Search

An improvement of the optical properties of switchable mirrors is obtained by incorporating of silver (Ag) into the palladium (Pd) cap layer of nanocrystalline gadolinium hydride system Gd\\/GdH3. Two methods for modification of Pd layer with Ag are employed. The first method is the forming of an AgPd binary alloy. The second method is the forming of Ag\\/Pd bilayer. In

E. Shalaan; A. A. Al-Ghamdi

2010-01-01

396

Motexafin gadolinium induces oxidative stress and apoptosis in hematologic malignancies  

Microsoft Academic Search

Opinion statement  Redox mechanisms have been shown to be important in malignant cell survival and are a system that may be modified for the\\u000a treatment of hematologic malignancies. Motexafin gadolinium (MGd) is a synthetic expanded porphyrin that selectively accumulates\\u000a in tumor cells and oxidizes various intracellular metabolites, including ascorbate, nicotinamide adenine dinucleotide phosphate,\\u000a glutathione, and protein thiols, to generate reactive oxygen

Andrew M. Evens; Lakshmi Balasubramanian; Leo I. Gordon

2005-01-01

397

Magnons as a Bose-Einstein Condensate in Nanocrystalline Gadolinium  

SciTech Connect

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

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

2011-06-17

398

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

399

Anomalous electrical and magnetic properties of gadolinium hexaboride  

Microsoft Academic Search

Gadolinium hexaboride undergoes an antiferromagnetic phase transition below TN&bartil;16 K. A second phase transition takes place below 11 K. We have studied both phases of GdB6 by experimental measurements of electrical resistivity, magnetoresistance, magnetic susceptibility, and Hall effect. The electrical resistivity data show a large thermal hysteresis associated with the lower-phase transition. Magnetoresistance data in the higher phase is isotropic

Naushad Ali

1988-01-01

400

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

401

Spinal cord tumors: gadolinium-DTPA-enhanced MR imaging  

Microsoft Academic Search

To assess the utility of gadolinium-DTPA (Gd) and of MR imaging in the evaluation of spinal cord tumors, ten consecutive patients were prospectively evaluated. T1-proton density-, and T2-weighted images were obtained in sagittal or axial planes. T1-weighted images were obtained before and after intravenous administration. Five tumors were within the cervical spinal cord; 3 neoplasms were within the thoracic cord;

M. C. Chamberlain; A. D. Sandy

1991-01-01

402

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

403

The safety of gadolinium in patients with stage 3 and 4 renal failure  

Microsoft Academic Search

Background. Although there is a well-documented risk of acute renal failure (ARF) with the iodinated contrast agents, intravenous gadolinium-based con- trast agents are considered non-nephrotoxic and have been widely used for magnetic resonance imaging (MRI). However, debate continues regarding the safety issue of gadolinium, especially in patients with kidney failure. Therefore, we aimed to evaluate the safety of gadolinium in

Ihsan Ergun; Kenan Keven; Irfan Uruc; Yakup Ekmekci; Basol Canbakan; Ilhan Erden; Oktay Karatan

2006-01-01

404

Aluminum depletion in komatiites and garnet fractionation in the early Archean mantle: Hafnium isotopic constraints  

SciTech Connect

Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3,450 Ma old Barberton greenstone belt, southern Africa. All samples have initial {var epsilon}{sub Hf} values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during the solidification of an ancient terrestrial magma ocean. The garnet fractionation observed in komatiites probably took place during the melting event.

Gruau, G. (Max Planck Institut fuer Chemie, Mainz (West Germany) Universite de Rennes (France)); Chauvel, C.; Arndt, N.T. (Max Planck Institut fuer Chemie, Mainz (West Germany)); Cornichet, J. (Universite de Rennes (France))

1990-11-01

405

Type of MRI contrast, tissue gadolinium, and fibrosis.  

PubMed

It has been presupposed that the thermodynamic stability constant (Ktherm) of gadolinium-based MRI chelates relate to the risk of precipitating nephrogenic systemic fibrosis. The present study compared low-Ktherm gadodiamide with high-Ktherm gadoteridol in cultured fibroblasts and rats with uninephrectomies. Gadolinium content was assessed using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy in paraffin-embedded tissues. In vitro, fibroblasts demonstrated dose-dependent fibronectin generation, transforming growth factor-? production, and expression of activated myofibroblast stress fiber protein ?-smooth muscle actin. There were negligible differences with respect to toxicity or proliferation between the two contrast agents. In the rodent model, gadodiamide treatment led to greater skin fibrosis and dermal cellularity than gadoteridol. In the kidney, both contrast agents led to proximal tubule vacuolization and increased fibronectin accumulation. Despite large detectable gadolinium signals in the spleen, skin, muscle, and liver from the gadodiamide-treated group, contrast-induced fibrosis appeared to be limited to the skin and kidney. These findings support the hypothesis that low-Ktherm chelates have a greater propensity to elicit nephrogenic systemic fibrosis and demonstrate that certain tissues are resistant to these effects. PMID:25100280

Do, Catherine; Barnes, Jeffrey L; Tan, Chunyan; Wagner, Brent

2014-10-01

406

Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy  

SciTech Connect

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

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

2009-04-19

407

Microstructural evidences of garnet plasticity in the continental crust. New example from south Madagascar  

NASA Astrophysics Data System (ADS)

Garnet mechanical behaviour is of great importance to understand the rheological evolution of rocks within the mantle and the lower crust. Well-constrained natural examples of plastically deformed garnets are scarce; consequently their identification and the physical parameters controlling their occurrence are still debated. In southern Madagascar, a granulitic metamorphic event has developed during a late Panafrican - Cambrian, east-west shortening (570 Ma). This has led to the development of vertical transpressive shear zones. Within these zones, we identified variations in garnet microstructure following the deformation sequence. In order to understand this evolution, we carried out a thorough microstructural description of samples using the following techniques: optical microscopy and SEM imaging, EBSD technique (localized lattice-preferred orientation), TEM for dislocation density, EMP for chemical analyses, as well as crystal size distribution, statistic grain boundary and shapes analyses (Lexa et al., 2005). The hand samples were quartzites or two-feldspars quartzo- feldsphatic rocks bearing 10 modal percent of garnet. As strain increases, various garnet textures were observed: Type 1) millimetre-sized rounded garnets bearing two types of inclusions, i.e. elongated quartz ribbons and well oriented sillimanite parallel to the lineation; Type 2) elliptic very elongated and lobed garnets (1 to 8 aspect ratio); Type 3) smaller elongated pinch and swell garnets (1 to 3 aspect ratio); and finally Type 4) rounded small garnets (300 microns in diameter). Type 1 textures are due to multiple nucleation garnets and coalescence controlled by aluminous aggregates (biotite and sillimanite). As strain increases, these large skeleton garnets start to re-crystallise preferentially at the tip of lenticular quartz inclusions, giving Type 2 very elongated garnets with unique CPO. The latter then continues to re-crystallise by sub-grain rotation as underlined by the CPO in situ measurements of new re-orientated grains (Type 3). In the type 4, few large garnets remain and only smaller-sized rounded garnets are left. In these highly deformed rocks, fine sillimanite needles are locally preserved and tilted with respect to the main foliation. All garnets from Type 2 to 4 textures are chemically homogeneous. Data from garnets, quartz, and feldspars are compared for each microstructural type and progressive deformation. The observed microstructures are in accordance with garnet ductility coeval with the deformation of quartz K-feldspar and plagioclase and showing mixing of all phases (random distribution) as well as constant grain size (average diameter 200 microns). Our analyses show that under the high-temperature and dry conditions (850°C) all phases are mechanically active. This indicates convergence of strength minerals marked by contrasting (laboratory derived) rheologies. Lexa, O., Štípská, P., Schulmann, K., Baratoux, L., Kröner, A., 2005. Contrasting textural record of two distinct metamorphic events of similar P-T conditions and different durations. Journal of Metamorphic Geology 23. 649-666. http://petrol.natur.cuni.cz/~ondro/polylx:home

Malamoud, Karim; Martelat, Jean-Emmanuel; Cordier, Patrick; Schulmann, Karel; Lardeaux, Jean-Marc

2010-05-01

408

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

NASA Astrophysics Data System (ADS)

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

Alur, Siddharth

409

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

PubMed

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 mass-spectrometry (ICP-MS) and it is reported that the arsenic content of the waste streams was related to the wafer thinning process, with slurries from wafer polishing having the highest dissolved arsenic content at over 1,900 mgL(-1). Lapping slurries had much lower dissolved arsenic (< 90 mgL(-1)) content, but higher particulate contents. It is demonstrated that significant percentage of GaAs becomes soluble during wafer lapping. Grinding slurries had the lowest dissolved arsenic content at 15 mgL(-1). All three waste streams are classified as hazardous waste, based on their solids content and dissolved arsenic levels and treatment is required before discharge or disposal. It is calculated that as much as 93% of material is discarded through the entire GaAs device manufacturing process, with limited recycling. Although gallium can be economically recovered from waste slurries, there is little incentive to recover arsenic, which is mostly landfilled. Options for treating GaAs processing waste streams are reviewed and some recommendations made for handling the waste. Therefore, although the quantities of hazardous waste generated are miniscule in comparison to other industries, sustainable manufacturing practices are needed to minimize the environmental impact of GaAs semiconductor device fabrication. PMID:20390892

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

2010-01-01

410

Radiative Performance of Rare Earth Garnet Thin Film Selective Emitters  

NASA Technical Reports Server (NTRS)

In this paper we present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I(sub 15/2)-(4)I(sub 13/2) at 1.5 microns, and Ho, (5)I(sub 7)-(5)I(sub 8) at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

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

1994-01-01

411

Ferromagnetic resonance of sputtered yttrium iron garnet nanometer films  

NASA Astrophysics Data System (ADS)

Growth of nm-thick yttrium iron garnet (YIG) films by sputtering and ferromagnetic resonance (FMR) properties in the films were studied. The FMR linewidth of the YIG film decreased as the film thickness was increased from several nanometers to about 100 nm. For films with very smooth surfaces, the linewidth increased linearly with frequency. In contrast, for films with big grains on the surface, the linewidth-frequency response was strongly nonlinear. Films in the 7-26 nm thickness range showed a surface roughness between 0.1 nm and 0.4 nm, a 9.48-GHz FMR linewidth in the 6-10 Oe range, and a damping constant of about 0.001.

Liu, Tao; Chang, Houchen; Vlaminck, Vincent; Sun, Yiyan; Kabatek, Michael; Hoffmann, Axel; Deng, Longjiang; Wu, Mingzhong

2014-05-01

412

An Excel spreadsheet to recast analyses of garnet into end-member components, and a synopsis of the crystal chemistry of natural silicate garnets  

NASA Astrophysics Data System (ADS)

A Microsoft Excel spreadsheet has been programmed that allows users to calculate with ease the molar proportions of garnet end-members from chemical analyses. Recent advances in the understanding of the crystal chemistry of natural garnets, especially of the Ti-bearing garnets, are used to evaluate 29 end-members (15 species and 14 hypothetical end-members) for each analysis. The amounts of Fe 2+ and Fe 3+ (and Mn 3+, if necessary) are calculated by stoichiometric constraints if these quantities have not been measured. The input data can include: SiO 2, TiO 2, ZrO 2, SnO 2, Y 2O 3, Al 2O 3, Sc 2O 3, Cr 2O 3, V 2O 3, FeO, Fe 2O 3, MnO, MgO, CaO, Na 2O, H 2O+ and F. The spreadsheet can be used with large data sets (up to 100 analyses at a time), and is accompanied by results calculated for 470 garnet analyses taken from the literature. The spreadsheet employs a simple scoring algorithm to measure the quality of a garnet analysis. The propagation of error from the input chemical data to the calculation of end-member proportions is also discussed briefly.

Locock, Andrew J.

2008-12-01

413

The dimeric nature of bonding in gallium: from small clusters to the ?-gallium phase.  

PubMed

We consider the structural similarity of small gallium clusters to the bulk structure of ?-gallium, which has been previously described as a molecular metal, via density functional theory-based computations. Previous calculations have shown that the tetramer, the hexamer, and the octamer of gallium are all structurally similar to the ?-phase. We perform an analysis of the bonding in these clusters in terms of the molecular orbitals and atoms in molecules description in order to assess whether we can see similarities at these sizes to the bonding pattern, which is ascribed to the co-existence of covalent and metallic bonding in the bulk. The singlet Ga4 and Ga8 clusters can be constructed in a singlet ground state from the Ga-dimers in the first excited triplet state of the Ga2-molecule, the (3)?g(-) state. Molecular orbital (MO) analysis confirms that the dimer is an essential building block of these small clusters. Comparison of the AIM characteristics of the bonds within the clusters to the bonds in the bulk ?-phase supports the identification of the covalent bond in the bulk as related to the (3)?g(-) state of the dimer. PMID:25294298

Tonner, Ralf; Gaston, Nicola

2014-10-21

414

Computer simulation of radiation damage in gallium arsenide  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

415

Ellipsometric study of silicon nitride on gallium arsenide  

NASA Technical Reports Server (NTRS)

A method for optimizing the sensitivity of ellipsometric measurements for thin dielectric films on semiconductors is described in simple physical terms. The technique is demonstrated for the case of sputtered silicon nitride films on gallium arsenide.

Alterovitz, S. A.; Bu-Abbud, G. H.; Woollam, J. A.; Liu, D.; Chung, Y.; Langer, D.

1982-01-01

416

Generator for ionic gallium-68 based on column chromatography  

DOEpatents

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

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

1981-01-01

417

X ray topography study of gallium phosphate crystals and resonators  

Microsoft Academic Search

Using the synchrotron radiation delivered by the DCI storage ring at LURE (Orsay, France), the X-ray topography technique was used to study the crystalline perfection of GaPO4 samples grown under different conditions. The growth of gallium phosphate on a berlinite seed is analyzed by X-ray section topography. The results obtained demonstrate the feasibility of gallium phosphate epitaxy on large berlinite

B. Capelle; A. Zarka; J. Schwartzel; J. Detaint; Y. Zheng; A. Ibanez; E. Philippot

1993-01-01

418

Complexometric determination of gallium with calcein blue as indicator  

USGS Publications Warehouse

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

Elsheimer, H. N.

1967-01-01

419

Complexometric determination of gallium with calcein blue as indicator.  

PubMed

A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1% and a relative standard deviation of about 0.4% for 10 mg of gallium. PMID:18960071

Elsheimer, H N

1967-01-01

420

Gallium67 citrate in human tumors: ultrastructural localization by autoradiography  

Microsoft Academic Search

The purpose of this study is to demonstrate the localization of carrier-free ⁶⁷gallium citrate in a variety of human tumors using electron microscopic autoradiography. Multiorgan surgical specimens were obtained from 76 patients with a variety of tumors 24 to 96 hours following intravenous administration of 45 microcuries per kilogram of body weight of carrier-free gallium-67. Specimens received for electron microscopy

O. L. Manfredi; L. R. Weiss

1978-01-01

421

Electrical contacts to ion cleaned n-type gallium arsenide.  

NASA Technical Reports Server (NTRS)

The electrical current through silver contacts evaporated onto n-type gallium arsenide is reported as a function of surface treatment. Contacts to untreated gallium arsenide exhibit the expected high resistance. Surface cleaning by argon ion bombardment reduces the resistance by three orders of magnitude. The electrical resistance beyond 850 eV increases rapidly with ion bombardment energy. The resistance minimum at 850 eV is explained semiquantitatively in terms of a balance between cleaning and surface damage.

Walker, G. H.; Conway, E. J.

1972-01-01

422

In-situ X-ray photoelectron spectroscopy study of supported gallium oxide  

NASA Astrophysics Data System (ADS)

In-situ XPS study of supported gallium oxide catalysts prepared by impregnation of different metal oxides supports (SiO 2, ?-Al 2O 3, TiO 2, and MgO) has been performed. It has been found that the formation of metallic gallium takes place upon high-temperature reduction of the catalysts in flowing hydrogen. Relative concentrations of metallic gallium were most high in the cases of alumina- and titania-supported catalysts. It was suggested that interaction of gallium oxide with a support surface favors the formation of metallic gallium upon high-temperature reduction. A possible mechanism of metallic gallium formation upon the reduction is discussed.

Serykh, Alexander I.; Amiridis, Michael D.

2010-06-01

423

Characterisation of bismuth-doped yttrium iron garnet layers prepared by sol-gel process  

NASA Astrophysics Data System (ADS)

Yttrium iron garnets and Bi-substituted yttrium iron garnets were prepared by two different sol-gel processes. We investigated the evolution with temperature of XRD patterns and of the magnetisation of powders issued from sol-gel solution decomposition. We prepared layers on silica glass by the spin- or dip-coating processes. XRD patterns on layers were also obtained. The dependency of the Faraday effect upon the light wavelength and Bi amount was shown. The main result is the possibility to prepare stable sol-gel solutions containing bismuth, yttrium and iron precursors which lead to garnet phase after annealing at low temperature. These bismuth-doped garnet phases give the expected magneto-optical properties. These processes are promising for the preparation of inexpensive magneto-optical recording media.

Rehspringer, J.-L. J.-L.; Bursik, J.; Niznansky, D.; Klarikova, A.

2000-03-01

424

Mineral inclusions in garnet crystals and their application in studies of high and ultrahigh pressure rocks  

NASA Astrophysics Data System (ADS)

Mineral inclusions in crystals like garnet, zircon or clinopyroxene play a key role in identifying ultrahigh-pressure (UHP) metamorphic rocks and in deciphering their metamorphic (P) - temperature (T) history. In this contribution, we address the questions related to the modification of garnet interiors mediated by H2O and/or CO2 fluids released either from the mineral inclusions or from the exterior source. The data presented are based on experimental studies of eclogitic garnets containing various mineral inclusions and on petrologic studies of natural rocks from several HP and UHP complexes. An experimental study on eclogitic garnets with different min¬eral inclusions (including hydrous phases and carbonates) from several subduction-related complexes reveals considerable modification of garnet interiors at temperatures of 700-1100?C and a pressure of 3-4 GPa, representative of different diamond-bearing metamorphic UHP terranes. Epidote, amphibole, and chlorite inclusions in the garnets underwent dehydration melting over the entire experimental PT range. In the presence of aqueous fluids, carbonate minerals in the inclusions began to melt at 800 °C and 3 GPa. Melting gave rise to new garnet, with the composition controlled by the chemistry of the primary inclusions and by PT run conditions. Garnet either grew directly from the melt or formed by metasomatic replacement of host garnet walls, leaving residual melt at the substitution front in the latter case. Partial melting of inclusions decreased the mechanical strength of the garnet host and led to local shearing. The following diagnostic criteria for melt in metamorphic garnet may be formulated on the basis of the experimental study: (1) (sub-) euhedral garnet grows within the inclusion and/or xenomorphic garnet replaces the garnet host; (2) newly formed garnet is characterized by a composition different from the garnet host; (3) the inclusion surface is features characteristic wedge-shaped ledges or radial wavy fractures filled by melt or products of its recrystallization. The increase of pressure and temperature during subduction will generally affect the P-V-T behaviour of the host and its inclusions in a significantly different way. A simple elastic model for various included minerals in garnet was used to show how the P-T trajectories of the spherical inclusions of different minerals deviate from the P-T path of the rock. Assuming only 5 % volume expansion due to the dehydration melting of the inclusion, the overpressure generated by the inclusion may reach 1.7 GPa. The increasing strain may finally rupture the host crystal, producing the radial cracks observed in the experimental runs. The experimental results were used to interpret observed features in the samples of a diamond-bearing and a diamond-free carbonate-silicate rock from the Kumdy-Kol deposit in the Kokchetav Massif and inclusions in garnet from the eclogite from Faro, Yukon-Tanana terrain, Canada. We also discuss origin of unusual inclusions in the garnet from the diamondiferous gneisses of Saxonian Erzgebirege which provide evidence on the both (1) presence of supercritical UHP liquid in the rock and (2) non precipitated origin of oriented lamellae in the garnet host. The studied dimondiferrous gneiss is composed of garnet, phengite (replaced by biotite), plagioclase and quartz as major rock-forming miner¬als. Garnet contains polyphase diamond-bearing inclusions consisting of quartz±phengite±phlogopite±rutile±titanite±apatite. We found two polyphase inclusions of 100-200 µm in diameter in a single garnet host show a tendency to negative crystal shape and surrounded by radial fractures of garnet around the inclusions. In addition, the inclusions are surrounded by halos consisting of numerous inclusions of size less than 1 µm. Morphology of the halos is identical to the well known decrepitation halos of melt and fluid inclusions in deep seated magmatic rocks suggesting similar mechanism of their formation. Most of garnet grains contain very tiny oriented needles (up to 2*200 µm) of rutile

Perchuk, Alexei

2010-05-01

425

The Soviet-American Gallium Experiment (SAGE)  

SciTech Connect

It is a great pleasure for me to have been asked by Louis Rosen to tell you about the Soviet-American Gallium Experiment (SAGE). This undertaking is a multi-institutional collaboration among scientists from the Institute for Nuclear Research, Moscow (INR), Los Alamos National Laboratory (LANL), and several US universities. Its purpose is to measure the number of low-energy electron neutrinos emitted from the Sun that arrive at this planet. As such, it is an extremely important experiment, touching on fundamental physics issues as well as solar dynamics. In contrast to the strategic overviews, plans, and hopes for international collaboration presented earlier today, SAGE is an ongoing working effort with high hopes of producing the first measurement of the Sun's low-energy neutrino flux. This paper reviews this experiment. 3 refs., 3 figs.

Garvey, G.T.

1989-01-01

426

The interaction of gold with gallium arsenide  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar-cell contact materials, are known to react readily with gallium arsenide. Experiments designed to identify the mechanisms involved in these GaAs-metal interactions have yielded several interesting results. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are also explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

427

Contact formation in gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar cell contact materials, are known to react readily with gallium arsenide. Experiments were performed to identify the mechanisms involved in these GaAs-metal interactions. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

428

Radiation damage of gallium arsenide production cells  

NASA Technical Reports Server (NTRS)

High-efficiency gallium arsenide cells, made by the liquid epitaxy method (LPE), have been irradiated with 1-MeV electrons up to fluences of 10 to the 16th e/sq cm. Measurements have been made of cell spectral response and dark and light-excited current-voltage characteristics and analyzed using computer-based models to determine underlying parameters such as damage coefficients. It is possible to use spectral response to sort out damage effects in the different cell component layers. Damage coefficients are similar to other reported in the literature for the emitter and buffer (base). However, there is also a damage effect in the window layer and possibly at the window emitter interface similar to that found for proton-irradiated liquid-phase epitaxy-grown cells. Depletion layer recombination is found to be less than theoretically expected at high fluence.

Mardesich, N.; Garlick, G. F. J.

1987-01-01

429

Gallium arsenide solar array subsystem study  

NASA Technical Reports Server (NTRS)

The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

Miller, F. Q.

1982-01-01

430

Liquid membrane processes for gallium recovery from alkaline solutions  

SciTech Connect

Gallium is an important material in the semiconductor industry. Intermetallic compounds with gallium have applications as high-temperature rectifiers and transistors, solar batteries, and other devices where the photovoltaic effect can be used. In this paper, the authors examine the possibility of using membrane extraction and supported liquid membranes to recover gallium from alkaline solutions. Membrane extraction proves to be an alternative process to recover gallium from such liquors. In order to maximize mass transfer, highly hydrophilic membranes should be used in both the membrane extraction and stripping processes. The optimum composition of the membrane extractant is 10--15% Kelex 100, 10% n-decanol, 5% Versatic 10, and kerosene (vol %). The highest gallium permeability was obtained when the feed solution contained about 1.5 mol/l sodium hydroxide. The supported liquid membrane used failed to transport gallium because of instability. The dominant mechanisms for failure are considered to be spontaneous formation of a water-in-oil emulsion and formation of precipitates, causing membrane pore obstruction.

Zha, F.F.; Fane, A.G.; Fell, C.J.D. [Univ. of New South Wales, Sydney, New South Wales (Australia). UNESCO Centre for Membrane Science and Technology

1995-05-01

431

Inhalation developmental toxicology studies: Gallium arsenide in mice and rats  

SciTech Connect

Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

1990-12-01

432

Ce-substituted yttrium iron garnet films prepared on Gd3Sc2Ga3O12 garnet substrates by sputter epitaxy  

NASA Astrophysics Data System (ADS)

Ce-substituted yttrium iron garnet films are epitaxially grown in situ on (111)-oriented substrates of Gd3Sc2Ga3O12 garnet by conventional rf diode sputtering for application to magneto-optic waveguide devices in optical communication systems. The lattice constant of the substrates is larger than that of the previously used (Gd,Ca)3(Ga,Mg,Zr)5O12 garnet substrates whose lattice constant is smaller than that of the films. The lowest ever reported propagation losses of 9.7 dB/cm in the TE mode and 5.8 dB/cm in the TM mode are obtained for a film thickness of 0.5 ?m at ?=1.55 ?m.

Shintaku, Toshihiro; Tate, Akiyuki; Mino, Shinji

1997-09-01

433

Oxidised Eclogites and Garnet-Blueschists from Oman: PT Path Modelling in the NCFMASHO System  

Microsoft Academic Search

Eclogites and garnet-blueschists exposed at the deepest structural levels of the Oman Mountains in north-eastern Saih Hatat, Oman, are evidence for the subduction of the Arabian continental margin. Their peak pressures have been a matter of debate for over a decade, with initial thermobarometric estimates in excess of 20 kbar, based on garnet-clinopyroxene-phengite barometry and the presence of radial cracks

C. J. Warren; D. J. Waters; M. P. Searle; R. R. Parrish

2004-01-01

434

TC\\/EA-MS online determination of hydrogen isotope composition and water concentration in eclogitic garnet  

Microsoft Academic Search

A continuous flow method, by a combination of thermal conversion elemental analyzer (TC\\/EA) with isotope ratio mass spectrometry\\u000a (MS), is presented for determination of both H isotope composition and H2O concentration of garnet from eclogite. Together with biotite NBS-30, the garnet was tested by preheating mineral grains\\u000a at different temperatures. Preheating at 90°C for 12 h was found to be capable

Bing Gong; Yong-Fei Zheng; Ren-Xu Chen

2007-01-01

435

Observation of a cubical-like microstructure of strontium iron garnet and yttrium iron garnet prepared via sol-gel technique.  

PubMed

This is our initial response towards preparation of nano-inductors garnet for high operating frequencies strontium iron garnet (Sr3Fe5O12) denoted as SrIG and yttrium iron garnet (Y3Fe5O12) denoted as YIG. The garnet nano crystals were prepared by novel sol-gel technique. The phase and crystal structure of the prepared samples were identified by using X-ray diffraction analysis. SEM images were done to reveal the surface morphology of the samples. Raman spectra was taken for yttrium iron garnet (Y3Fe5O12). The magnetic properties of the samples namely initial permeability (micro), relative loss factor (RLF) and quality factor (Q-Factor) were done by using LCR meter. From the XRD profile, both of the Y3Fe5O12 and Sr3Fe5O12 samples showed single phase garnet and crystallization had completely occurred at 900 degrees C for the SrIG and 950 degrees C for the YIG samples. The YIG sample showed extremely low RLF value (0.0082) and high density 4.623 g/cm3. Interesting however is the high Q factor (20-60) shown by the Sr3Fe5O12 sample from 20-100 MHz. This high performance magnetic property is attributed to the homogenous and cubical-like microstructure. The YIG particles were used as magnetic feeder for EM transmitter. It was observed that YIG magnetic feeder with the EM transmitter gave 39% higher magnetic field than without YIG magnetic feeder. PMID:21449424

Nasir, Nadeem; Yahya, Noorhana; Kashif, Muhammad; Daud, Hanita; Akhtar, Majid Niaz; Zaid, Hasnah Mohd; Shafie, Afza; Teng, Lee Chaw

2011-03-01

436

Ordre magnétique électronique induit par les interactions hyperfines dans les grenats de gallium-holmium et de gallium-terbium  

Microsoft Academic Search

2014 L'ordre magnétique observé dans les grenats de terbium-gallium et d'holmium- gallium à 0,25 et 0,19 K par mesure de susceptibilité et de chaleur spécifique est interprété dans un modèle à 2 singulets électroniques dans lequel on tient compte du couplage hyperfin et où les interactions magnétiques, essentiellement d'origine dipolaire, sont traitées dans l'approximation du champ moléculaire. Ce modèle se

J. HAMMANN; P. Manneville

1973-01-01

437

Genesis of garnet-bearing rocks at the Berezitovoe deposit, Upper Amur Region, Russia  

NASA Astrophysics Data System (ADS)

The geological position, composition of mineral assemblages, and typomorphism of major minerals from garnet-bearing rocks at the Berezitovoe gold-base-metal deposit in the Upper Amur Region have been studied in detail. These are ore-bearing metasomatic rocks and metamorphosed porphyritic dikes. The garnet-bearing metasomatic rocks reveal zoning, which is caused by various degrees of metasomatic transformation of the Paleozoic porphyritic granodiorite that hosts the ore zone. The metasomatic replacement of granodiorite was accompanied by loss of Na, Ca, Ba, Sr and gain of K, Mn, and Rb. Garnet-bearing metamorphosed intermediate dikes occur within the metasomatic zone. The PT conditions of metamorphism and metasomatism are similar and estimated at 3.9 kbar and 500°C from various mineral equilibria. The results of physicochemical simulation of garnet-bearing mineral assemblages carried out by minimizing the Gibbs free energy and the geological data show that garnet-bearing mineral assemblages arose at the Berezitovoe deposit as a result of local high-temperature thermal metamorphism of previously formed low-temperature metasomatic rocks close in composition to classic beresite. In this connection, we propose considering garnet-bearing metasomatic rocks as high-temperature metamorphosed beresites.

Avchenko, O. V.; Vakh, A. S.; Chudnenko, K. V.; Khudolozhkin, V. O.

2014-02-01

438

Irradiation of synthetic garnet by heavy ions and ?-decay of 244Cm  

NASA Astrophysics Data System (ADS)

Garnet, A 3B 2X 3O 12, has a structure that can incorporate actinides. Hence, the susceptibility of the garnet structure to radiation damage has been investigated by comparing the results of self-radiation damage from ?-decay of 244Cm and a 1 MeV Kr 2+ ion irradiation. Gradual amorphization with increasing fluence was observed by X-ray diffraction analysis and in situ transmission electron microscopy. The critical dose, D c, for an yttrium-aluminum garnet (Y 3Al 5O 12) doped with 3 wt.% 244Cm is calculated to be 0.4 displacements per atom (dpa). While the doses obtained by ion irradiation experiments of garnets with different compositions (Y 2.43Nd 0.57)(Al 4.43Si 0.44)O 12, (Ca 1.64Ce 0.41Nd 0.42La 0.18Pr 0.18Sm 0.14Gd 0.04)Zr 1.27Fe 3.71O 12, and (Ca 1.09Gd 1.23Ce 0.43)Sn 1.16Fe 3.84O 12, varied from 0.29 to 0.55 dpa at room temperature. The similarity in the amorphization dose at room temperature and critical temperature of the different garnet compositions suggest that the radiation response for the garnet structure is structurally constrained, rather than sensitive to composition, which is the case for the pyrochlore structure-type.

Zhang, Jiaming; Livshits, Tatiana S.; Lizin, Andrey A.; Hu, Qiaona; Ewing, Rodney C.

2010-12-01

439

REE Zonation in Garnet: new insights from combined Thermodynamic and Diffusion Modelling  

NASA Astrophysics Data System (ADS)

Compositional variation in garnet provides an excellent record of element transport within their host rocks, as it precisely reflects the interplay between thermodynamically-controlled nutrient demand and kinetically-constrained element availability during growth. Element availability is controlled by (1) the thermodynamically controlled element distribution among co-existing phases and (2) by matrix transport properties. Our task is to distinguish between factors controlling the availability of major- and trace-elements and to quantify their diffusion length scales but this is hindered by the fact that the interplay of different rate-limiting factors on garnet growth and composition are not fully understood. These processes comprise: (1) fractional garnet crystallisation, which continuously changes the effective, i.e. reacting, bulk rock chemistry (EBC), which in turn influences garnet proportion, growth rate and composition; (2) kinetically-controlled element availability, such that grain boundary diffusion in the host rock's interconnecting transport matrix (ITM) or surface processes in reacting phases cannot keep pace with the material required for garnet nucleation and growth in homogeneous thermodynamic equilibrium with the coexisting phase assemblage and (3) reaction-controlled trace element availability in the host rock, which is often reflected in discontinuous trace element zoning patterns in garnet. A 1D diffusion and reaction model was developed to investigate REE distribution patterns in garnet. It combines PERPLEX thermodynamic forward modelling for a bulk rock composition along a P-T-path with control of diffusion rates in the matrix fluid which acts as a transport medium in the intergranular space. Initial REE distribution is controlled by standard distribution coefficients. Reactant phases are the source of REE and product minerals fractionate REE from the transport medium. Thus the uptake of REE in garnet is regulated by: (1) thermodynamically-driven mineral decomposition and REE entry into the fluid; (2) diffusion-controlled transport of REE from reactant to product garnet; (3) the partition coefficient Kgrt-fluid and (4) the growth rate of the garnet. Model results show that the uptake of REE in garnet is controlled primarily by the thermodynamically-controlled delivery from reactant phases. Bell-shaped HREE peaks in garnet cores are the result of high distribution coefficient Kgrt-fluid and rapid depletion of the fluid in HREE. Secondary HREE peaks or shoulders outside garnet cores result from the final consumption of specific reactant phases. Bowl-shaped LREE pattern result from low Kgrt-fluid and breakdown of LREE phases. It is also shown that the position of such peaks depends on the volume of garnet already grown and the timing of the decomposition of reactant phases. Matrix diffusion rates control height and shape of the REE peaks, such that rapid matrix diffusion produces narrow high peaks whereas slower matrix diffusion results in flatter, broader peaks. Very low intergranular diffusion rates cause flattening of the HREE central peak resulting in similar, bowl-shaped patterns for all REE. The results will be discussed in relation to natural garnet REE zoning patterns.

Witte, C.; Konrad-Schmolke, M.

2013-12-01

440

Motexafin-Gadolinium Taken Up In vitro by at Least 90% of Glioblastoma Cell Nuclei  

E-print Network

Motexafin-Gadolinium Taken Up In vitro by at Least 90% of Glioblastoma Cell Nuclei Gelsomina De intranuclear uptake of motexafin gadolinium by glioblastoma multiforme cells, which could serve as a prelude radiotherapy (GdSSR), a new putative treatment for glioblastoma multiforme. Experimental Design

Gilbert, Pupa Gelsomina De Stasio

441

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

E-print Network

surprising since the magnetic fields associated with the magnetic domains might be expected to destroy of gadolinium Rajiv Misra, Arthur F. Hebard,* and Khandker A. Muttalib Department of Physics, University to the conductivity of thin ferromagnetic gadolinium films. In situ magnetotransport measurements were performed

Muttalib, Khandker

442

The magnetic domain structure of gadolinium between 230 and 293 K  

Microsoft Academic Search

The magnetic domain structure of gadolinium has been studied over the temperature range 230 K to 293 K. This temperature range includes the two magnetic phase transitions that exist in gadolinium, that at the Curie temperature, 291 K, and the change in the easy direction of magnetization at 240 K. A clear uniaxial type domain structure was observed to form

R. L. Smith; W. D. Corner; B. K. Tanner

1980-01-01

443

Myocardial biopsy findings and gadolinium enhanced cardiovascular magnetic resonance in dilated cardiomyopathyB  

Microsoft Academic Search

Background: In some patients suffering from dilated cardiomyopathy (DCM) magnetic resonance imaging (MRI) shows late gadolinium enhancement with variable distribution. Myocardial biopsies in DCM reveal a chronic myocardial inflammatory process in almost 50% and myocardial persistence of adenoviral or enteroviral genome in about 15% of the patients. Aims: We prospectively investigated whether the pattern of late gadolinium enhancement correlates with

Oliver Zimmermann; Olaf Grebe; Nico Merkle; Thorsten Nusser; Matthias Kochs; Magdalena Bienek-Ziolkowski; Vinzenz Hombach; Jan Torzewski

444

Relative Strength of the Pyrope–majorite Solid Solution and the Flow-law of Majorite Containing Garnets  

SciTech Connect

Even though the garnet phase is the second most abundant phase in the upper-mantle and transition-zone, no previous studies have directly measured the effect of majorite content on the strength of garnet under mantle conditions. Here we report the results of constant strain-rate and stress-relaxation experiments on garnets in the pyrope-majorite solid solution which constrain the strength of majoritic containing garnets relative to pyrope as a function of majorite content and temperature. We find that at temperatures below 650 C both pure pyrope and majoritic garnets have the same strength. Conversely, above 650 C we find that majoritic garnets are initially stronger than pure pyrope but weaken with increasing temperature and majorite content and with significant majorite contents are weaker than pyrope above approximately 800 C. We develop a flow law for the entire pyrope-majorite solid solution as a function of temperature and majorite content.

Hunt, S.; Dobson, D; Li, L; Weidner, D; Brodholt, J

2010-01-01

445

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

Code of Federal Regulations, 2011 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2011-07-01

446

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

Code of Federal Regulations, 2013 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2013-07-01

447

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

Code of Federal Regulations, 2012 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2012-07-01

448

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

Code of Federal Regulations, 2010 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2010-07-01

449

Samarium- and ytterbium-promoted oxidation of silicon and gallium arsenide surfaces  

SciTech Connect

A method is described for promoting oxidation of a silicon or gallium arsenide surface comprising: depositing a ytterbium overlayer on the silicon or gallium arsenide surface prior to the oxidation of the surface.

Franciosi, A.

1989-02-21

450

Bonding mechanism of a yttrium iron garnet film on Si without the use of an intermediate layer  

NASA Astrophysics Data System (ADS)

Direct bonding of yttrium iron garnet (YIG) on silicon without the use of an intermediate bonding layer is demonstrated and characterized using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy. During the bonding experiment, the garnet is reduced in the presence of oxide-free silicon. As a result, a 5 nm thick SiO2/amorphous-YIG bilayer is formed and welds the garnet to silicon.

Pantzas, Konstantinos; Patriarche, Gilles; Talneau, Anne; Youssef, Jamal Ben

2014-10-01

451

Thermodynamic properties of liquid alloys of gadolinium with silicon  

Microsoft Academic Search

Partial heats of mixing for gadolinium and silicon in the binary system Gd–Si are measured by means of a high-temperature\\u000a isoperibolic calorimeter in two concentration ranges: 0GdGd<1 at 1760 K. The integral enthalpies of mixing are calculated from partial enthalpies by the Darken method. Marked exothermic\\u000a values of\\u000a $$\\\\Delta \\\\bar H_{Gd(Si)} $$\\u000a and ?H were revealed for these binary alloys.

E. A. Beloborodova; N. V. Golovataya; T. N. Zinevich; N. V. Kotova

1999-01-01

452

Atomic Mass and Nuclear Binding Energy for Gd-171 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Gd-171 (Gadolinium, atomic number Z = 64, mass number A = 171).

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

453

Atomic Mass and Nuclear Binding Energy for Gd-227 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Gd-227 (Gadolinium, atomic number Z = 64, mass number A = 227).

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

454

Atomic Mass and Nuclear Binding Energy for Gd-119 (Gadolinium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Gd-119 (Gadolinium, atomic number Z = 64, mass number A = 119).

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

455

New chelation clean process for removing gallium from the focused-ion-beam repaired mask  

Microsoft Academic Search

Repairing mask defects with Focused Ion Beam (FIB) of gallium often results in a gallium-implanted area due to scan. This implanted layer reduces the light transmission by up to 10 ~ 30 percent, depending on the wavelength. This effect of localized transmission loss becomes printable at the extremes of focus-energy matrix of wafer printing. The existing methods for the gallium

Same-Ting Chen; Tzy-Ying Lin; Chue-San Yoo

2003-01-01

456

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption  

E-print Network

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption flat gallium arsenide solar cell, we show that it is possible to modify the flow of light and enhance material which directly contributes to the pho- tocurrent enhancement of the solar cell. Index Terms--Gallium

Grandidier, Jonathan

457

Pure silver ohmic contacts to N- and P- type gallium arsenide materials  

SciTech Connect

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, Stephen J. (Golden, CO)

1986-01-01

458

HOT CARRIER SPACE AND TIME DEPENDENT TRANSIENTS IN SHORT CHANNEL GALLIUM ARSENIDE DEVICES55  

E-print Network

HOT CARRIER SPACE AND TIME DEPENDENT TRANSIENTS IN SHORT CHANNEL GALLIUM ARSENIDE DEVICES55 Hr in gallium arsenide when the fields change temporally and spatially at a finite rate. For temporal changes gallium arsenide when f i e l d s change a t f i n i t e r a t e s and t o suggest the types

Paris-Sud XI, Université de

459

May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big  

E-print Network

optics.org NEWS May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big the technique for gallium arsenide (GaAs), the team hopes that its method will be equally applicable to other material systems such as gallium nitride and indium phosphide (Nature 465 329). "We can generate compound

Rogers, John A.

460

THE PREPARATION AND STUDY OF THE OPTICAL ABSORPTION EDGE OF THIN FILMS OF GALLIUM ARSENIDE  

E-print Network

212. THE PREPARATION AND STUDY OF THE OPTICAL ABSORPTION EDGE OF THIN FILMS OF GALLIUM ARSENIDE Par of gallium arsenide have been prepared by evaporation on to amorphous substrates. A simple and effective method of evaporating gallium arsenide, which would also be applicable to other III-V compounds

Boyer, Edmond