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1

Gadolinium Gallium Garnet at Multi-Megabar Pressures  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

2

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

Microsoft Academic Search

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

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

1986-01-01

3

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

4

Tunable laser utilizing an electronic--vibrational transition in chromium in a gadolinium scandium gallium garnet crystal  

SciTech Connect

A laser continuously tunable in the range 766--820 nm was constructed. It utilizes an electronic--vibrational transition in chromium in a gadolinium scandium gallium garnet crystal kept at room temperature and subjected to nonselective flashlamp pumping.

Zharikov, E.V.; Il'ichev, N.N.; Kalitin, S.P.; Laptev, V.V.; Malyutin, A.A.; Osiko, V.V.; Ostroumov, V.G.; Pashinin, P.P.; Prokhorov, A.M.; Smirnov, V.A.

1983-09-01

5

Output characteristics of a gadolinium scandium gallium garnet laser operating in the pulse-periodic regime  

SciTech Connect

A pulse-periodic neodymium laser was made from a new crystal, which was gadolinium scandium gallium garnet activated with chromium and neodymium ions (GSGG:Cr/sup 3 +/: Nd/sup 3 +/). When the pump energy was 7.3 J per pulse, the output energy in the free-running regime was 255 mJ, i.e., the absolute efficiency was 3.5%. At the maximum pulse repetition frequency (20 Hz), which was limited by the nature of the power supply unit, the average output power was 5 W when the pump power was 145 W. The differential efficiency was 4.5%, which was 2.4 times higher than for an YAG:Nd/sup 3 +/ crystal operated under similar conditions. The diameter of the GSGG active element was 5 mm and its length was 50 mm. The differential efficiency in the Q-switched regime was 3% when the pump energy was in the range 3--7 J.

Zharikov, E.V.; Zhitkova, M.B.; Zverev, G.M.; Isaev, M.P.; Kalitin, S.P.; Kuratev, I.I.; Kusnir, V.R.; Laptev, V.V.; Osiko, V.V.; Pashkov, V.A.

1983-10-01

6

Amplification of single pulses in a gadolinium scandium gallium garnet crystal activated with Cr/sup 3 +/ and Nd/sup 3 +/  

SciTech Connect

The gain Nsigma = 0.7 cm/sup -1/ was determined for an active element in the form of a gadolinium scandium gallium garnet (GSGG) crystal activated with Cr/sup 3 +/ and Nd/sup 3 +/. The total gain exceeded 10/sup 3/ in a two-pass compact GSGG:Cr/sup 3 +/:Nd/sup 3 +/ laser amplifier.

Zharikov, E.V.; Laptev, V.V.; Natarov, S.Y.; Osiko, V.V.; Pashinin, P.P.; Prokhorov, A.M.; Shklovskii, E.I.; Shcherbakov, I.A.

1985-11-01

7

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

8

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

SciTech Connect

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

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

2014-04-24

9

Investigation of a new laser active medium in the form of gadolinium scandium gallium garnet crystals activated with chromium and neodymium  

SciTech Connect

A general method is proposed for calculating the populations of excited acceptor states when they interact with energy donors under conditions of nonradiative losses in the acceptor subsystem. The method is suitable for dealing with continuous and pulsed pumping and no restrictions are imposed on the shape of the pump pulses. A study is made of the time dependence of the population of the upper active level /sup 4/F/sub 3//sub ///sub 2/ of Nd/sup 3 +/ in gadolinium scandium gallium garnet (GSGG) crystals containing chromium and neodymium. An allowance is made for energy migration in the donor subsystem in the case of low and high Nd/sup 3 +/ ion concentrations when, in the latter case, concentration self-quenching of Nd/sup 3 +/ is observed. A quantitative agreement is obtained between the calculated and experimental results and an increase in the population of the /sup 4/F/sub 3//sub ///sub 2/ level of Nd/sup 3 +/ because of sensitization of the Nd/sup 3 +/ luminescence by Cr/sup 3 +/ ions is found. The proposed calculation method is used to determine the optimal concentrations of Nd/sup 3 +/ in GSGG:Cr:Nd crystals under continuous and pulsed lasing conditions.

Zharikov, E.V.; Laptev, V.V.; Ostroumov, V.G.; Privis, Y.S.; Smirnov, V.A.; Shcherbakov, I.A.

1984-08-01

10

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

Microsoft Academic Search

Recent interest in employing single-crystal yttrium iron garnet (YIG) films for miniaturized microwave integrated circuit applications has prompted us to study detaching liquid phase epitaxy (LPE) grown YIG films from their gadolinium gallium garnet (GGG) substrates via crystal ion slicing (CIS). We report studies of magnetization and ferromagnetic resonance (FMR) of narrow linewidth gallium-doped YIG (GaYIG) films in various stages

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

2000-01-01

11

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

SciTech Connect

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

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

2008-12-15

12

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

SciTech Connect

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

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

2006-04-15

13

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

E-print Network

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

Steve K. Lamoreaux

2007-03-16

14

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

E-print Network

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

Lamoreaux, S K

2007-01-01

15

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

16

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

SciTech Connect

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

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

2008-04-15

17

Thermo-optic properties of gadolinium garnet laser crystals  

SciTech Connect

The indices of refraction, thermal variations of refractive indices, and thermal expansion coefficients were measured for the gadolinium garnets Gd/sub 3/Sc/sub 2/Ga/sub 3/O/sub 12/ (GSGG) and Gd/sub 3/Sc/sub 2/Al/sub 3/O/sub 12/. The variation of these properties with trivalent chromium doping was investigated for GSGG. The refractive indices were determined by the minimum-deviation technique, with indices fitted to a five-parameter Sellmeier formula. The thermal coefficients were measured by an interferometric technique using simultaneous Twyman--Green and Fizeau interferometry.

Hoefer, C.S.; Kirby, K.W.; DeShazer, L.G.

1988-11-01

18

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

19

Magnetization and coercivity of nanocrystalline gadolinium iron garnet  

NASA Astrophysics Data System (ADS)

Gadolinium iron garnet (GdIG) nanoparticles with mean particle size of about 37 nm have been synthesized by citrate precursor gel formation followed by annealing at 800 °C for 2 hours. Magnetic behavior of clustered GdIG nanoparticles was studied in temperature range from 5 K to above Curie temperature. The sample shows a magnetization compensation temperature Tcomp˜286.5 K and a Curie temperature TC˜560 K. In comparison with the bulk saturation magnetization, the sample exhibits lower spontaneous magnetization in the temperature region from 5 K to Tcomp whereas higher spontaneous magnetization is observed at higher temperatures up to near the Curie point. The magnetization curves show a differential susceptibility in high fields which increases sharply below 50 K. At very low temperatures, irreversibility was observed in the magnetization loops, enduring in the fields up to ˜12.5 kOe. The spontaneous magnetization, high-field susceptibility and low-temperature irreversible effect were discussed based on a model for the interacting particles consisting of ferrimagnetically aligned core spins and disordered spins in surface layer which become frozen at low temperatures. We proposed a mechanism for the enhancement of the spontaneous magnetization above Tcomp in which the Gd and Fe spins in the surface layer are largely decoupled at high temperatures and the surface Fe spins realign to the magnetic moment of the core. The magnetic coercivity Hc at low temperatures is governed by the effective anisotropy whereas in the vicinity of the compensation point a peak in the coercive force shows up as a result of the so-called paraprocess with the maximum value of 1.2 kOe at Tcomp and by further increasing temperature the coercivity decreases and eventually vanishes at about 500 K. The interparticle interactions were found to play an important role in the hysteresis behavior of the sample.

Nguyet, Dao Thi Thuy; Duong, Nguyen Phuc; Satoh, Takuya; Anh, Luong Ngoc; Hien, Than Duc

2013-04-01

20

Synthesis and characterisation of chromium lutetium gallium garnet solid solution  

SciTech Connect

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

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

2007-03-22

21

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

22

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

E-print Network

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

Krishnan, Kannan M.

23

Investigation of magnetic structure and magnetization process of yttrium iron garnet film by Lorentz microscopy and electron holography  

E-print Network

Investigation of magnetic structure and magnetization process of yttrium iron garnet film American Institute of Physics. doi:10.1063/1.3524273 I. INTRODUCTION Garnets are widely used materials in optical disks and microwave devices.1,2 In particular Y3Fe5O12 YIG films deposited on gadolinium-gallium-garnet

Krishnan, Kannan M.

24

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

E-print Network

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

Paris-Sud XI, Université de

25

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

26

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

E-print Network

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

Marrucci, Lorenzo

27

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

PubMed

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

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

2014-03-01

28

Stabilization of cubic lithium-stuffed garnets of the type “Li7La3Zr2O12” by addition of gallium  

NASA Astrophysics Data System (ADS)

Cubic lithium-stuffed garnets of the type Li7La3Zr2O12 have been successfully stabilized by incorporation of gallium. The materials have been prepared by a sol-gel procedure with final calcination at 1085 °C for 6 h. Under the applied synthesis conditions, 0.3 mole of gallium ions (per mole of Li7La3Zr2O12) were sufficient to fully stabilize the cubic garnet-type phase. Increasing the fraction of gallium led to significant improvement of sinterability and lithium ion conductivity. Excess gallium ions, in the form of LiGaO2, act as a sintering aid and reside exclusively at the grain boundaries. The gallium-modified garnets showed conductivities up to 5.4 × 10-4 S cm-1 at 20 °C, and activation energies in the range 0.32-0.37 eV.

El Shinawi, Hany; Janek, Jürgen

2013-03-01

29

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

SciTech Connect

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

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

2010-08-03

30

Bismuth-doped yttrium iron garnet guided-wave magnetooptic Bragg cells and applications  

Microsoft Academic Search

Superior performance figures obtained with guided-wave magnetooptic Bragg cells using magnetostatic forward volume waves (MSFVWs) in bismuth-doped yttrium iron garnet-gadolinium gallium garnet (YIG-GGG) waveguides operating at an optical wavelength of 1.303 ?m are reported. The figures include a center-frequency tuning range of 3.7 to 12.0 GHz, a diffraction efficiency of 12% at a MSFVW power of 56 mW and a

D. Young; C. S. Tsai

1989-01-01

31

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

32

Field induced magnetic order in the frustrated magnet gadolinium gallium garnet  

Microsoft Academic Search

Gd3Ga5O12, (GGG), has an extraordinary magnetic phase diagram, where no long range order is found down to 25 mK despite ?CW ?2 K. However, long range order is induced by an applied field of around 1 T. Motivated by recent theoretical developments and the experimental results for a closely related hyperkagome system, we have performed neutron diffraction measurements on a

O. A. Petrenko; G. Balakrishnan; D. McK Paul; M. Yethiraj; G. J. McIntyre; A. S. Wills

2009-01-01

33

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

E-print Network

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

Sushkov, A O; Lamoreaux, S K

2008-01-01

34

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

35

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

36

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

SciTech Connect

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

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

2010-10-15

37

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

38

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

NASA Astrophysics Data System (ADS)

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 in the magnetic domain structure are used to infer the magnetostriction coefficient ?111 of garnet films.

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

2005-10-01

39

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  

Microsoft Academic Search

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 (?max ? 455 nm) coated with phosphors of the type of aluminum-yttrium-gadolinium garnets activated with the Ce3+ ions are studied. The maximum in the excitation spectra of phosphors varies in the range 460–470 nm. The luminescence spectra\\u000a of

N. P. Soshchin; N. A. Galchina; L. M. Kogan; S. S. Shirokov; A. E. Yunovich

2009-01-01

40

Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium–scandium–gallium garnet  

NASA Astrophysics Data System (ADS)

Spectroscopic investigation of the radiation-resistant Nd:GSGG crystals and ceramics reported in this paper evidences that the absorption line at 883 nm corresponding to the unusual situation of quasi-degenerate absorption transitions 4I9/2(2) ?4F3/2(1) and 4I9/2(3) ?4F3/2(2) can be used for efficient direct diode laser pumping of this material, with stable absorption over an extended temperature range. It is inferred that the reduction of the quantum defect at this wavelength of pump compared to the traditional 807 nm pumping could improve the laser parameters and reduce drastically the heat generation, leading to a considerable extension of the power scalability. This possibility is demonstrated for the first time in the case of the 1061 nm laser emission in a continuous-wave and in the repetitive active acousto-optic and passive Q-switched laser emission. In all regimes this manifests in the reduction of the laser threshold, increase of slope efficiency and extension of the average power range. Additionally, in the active Q-switching this enables increased pulse energy and reduced pulse duration. The direct pumping could revitalize the utilization of Nd:GSGG for construction of lasers with storage of population inversion or working in an ionizing radiation environment.

Lupei, V.; Pavel, N.; Lupei, A.

2014-04-01

41

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

NASA Technical Reports Server (NTRS)

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

Gadi, Jagannath; Yalamanchili, Raj; Shahid, Mohammad

1995-01-01

42

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

SciTech Connect

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

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

2012-07-15

43

Chromium-doped scandium gallium garnet crystals as active media of lasers utilizing Ho/sup 3 +/ and Tm/sup 3 +/ infrared transitions  

SciTech Connect

An investigation was made of the luminescence spectra of yttrium scandium gallium garnet crystals activated with Cr/sup 3 +/, Ho/sup 3 +/, and Tm/sup 3 +/ ions. Measurements were made of the excited state lifetime of Ho/sup 3 +/ and Tm/sup 3 +/. Efficient Cr..-->..Ho and Cr..-->..Tm nonradiative energy transfer was observed. The existence of energy transfer mechanisms having a shorter range than the dipole--dipole one was established. The microscopic constants of dipole--dipole interaction were determined. It is concluded that efficient Cr..-->..Ho and Cr..-->..Tm energy transfer suggests that efficient room-temperature lasers may be developed utilizing infrared transitions in these rare-earth ions.

Zharikov, E.V.; Kalitin, S.P.; Laptev, V.V.; Ostroumov, V.G.; Saidov, Z.S.; Smirnov, V.A.; Shcherbakov, I.A.

1986-01-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

45

Effects of an interaction of magnetostatic and elastic waves in structures with a tangentially magnetized submicron-thickness film of yttrium iron garnet  

NASA Astrophysics Data System (ADS)

The first observation of a resonant electrostrictive interaction of magnetostatic waves with Lamb elastic waves in structures that include a tangentially saturation-magnetized YIG film of submicron thickness on a substrate of gadolinium-gallium garnet is reported. Also reported are distinctive features of the propagation of a magnetostatic-wave pulse in such structures as the result of magnetoelastic coupling. A sweep-frequency generator tunable over the 2-4 GHz range was used for measurements in the continuous mode.

Andreev, A. S.; Zilberman, P. E.; Kravchenko, V. B.; Ogrin, Iu. F.; Temiriazev, A. G.; Filimonova, L. M.

1984-01-01

46

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

47

Developmental competence of mouse embryos following zona drilling using a non-contact holmium:yttrium scandian gallium garnet (Ho:YSGG) laser system.  

PubMed

The purpose of this study was to assess the efficacy of the holmium:yttrium scandian gallium garnet (Ho:YSGG) laser, operating in a pipette-free, non-contact mode, to assist hatching and sustain normal embryonic development. Two-cell mouse embryos were recovered and assigned to laser-assisted hatching (LAH) treatment or control human tubal fluid (HTF) culture with or without serum (HTF-s, HTF-o) or with late serum supplementation (HTF-o/s). The basic experimental apparatus for LAH consisted of a stationary 2.1 microns Ho:YSGG laser beam directed through a mechanical shutter into an input port of a Zeiss Axiomat inverted microscope. Fewer (P < 0.05) embryos developed to the blastocyst stage in the HTF-s group (81%) than in the LAH (90%), HTF-o (94%) and HTF-o/s (92%) groups. The level of hatching was significantly increased (P < 0.01) after the LAH treatment (57%) compared to HTF-o/s (32%), HTF-s (18%) or HTF-o (5%). Implantation rates were not significantly impaired following the LAH treatment (21%). These data demonstrate that LAH using the Ho:YSGG laser is a simple, accurate and effective procedure for assisted hatching. PMID:8582989

Schiewe, M C; Neev, J; Hazeleger, N L; Balmaceda, J P; Berns, M W; Tadir, Y

1995-07-01

48

Crystal Field in Dysprosium Garnets  

Microsoft Academic Search

The crystal-field splittings of the 6H and 6F multiplets of Dy3+ in yttrium gallium garnet and yttrium aluminum garnet have been determined from absorption and emission spectra. In addition, the g factors of some crystal-field levels have been determined from Zeeman-effect measurements. All these experimental data are used to derive a set of crystal-field parameters for the two garnet systems.

P. Grünberg; S. Hüfner; E. Orlich; J. Schmitt

1969-01-01

49

Optical waveguides of single-crystal garnet films  

NASA Astrophysics Data System (ADS)

We report light-wave propagation experiments in single-crystal epitaxially grown garnet films. The discussion includes refractive index and lattice constant considerations for various garnets, and also the use of iron garnet films on gallium garnet substrates as magneto-optical waveguides useful in integrated optics.

Tien, P. K.; Martin, R. J.; Blank, S. L.; Wemple, S. H.; Varnerin, L. J.

1972-09-01

50

Implant Bed Preparation with an Erbium, Chromium Doped Yttrium Scandium Gallium Garnet (Er,Cr: YSGG) Laser Using Stereolithographic Surgical Guide  

PubMed Central

Background: Implant bed preparation with laser is taken into consideration owing to the increased interest in use of lasers in hard tissue surgery. The purpose of this study is to determine the deviations in the position and inclination between the planned and prepared implant beds with Erbium, Chromium doped Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser using stereolithographic (SLA) surgical guides. Methods: After 3-dimensional (3D) imaging of six sheep lower jaws, computed tomography (CT) images were transformed into 3D models. Locations of implant beds were determined on these models. Two implant beds in each half jaw were prepared with an Er,Cr:YSGG laser system and a conventional drilling method using a total of 12 SLA surgical guides. A new CT was taken to analyze the deviation values between planned and prepared implant beds. Finally, a software program was used to superimpose the images on 3D models, then the laser and conventional drilling groups were compared. Results: Differences of mean angular deviations between the planned and prepared implant beds were 5.17±4.91° in the laser group and 2.02±1.94° in the conventional drilling group.The mean coronal deviation values were found to be 0.48±0.25 mm and 0.23±0.14 mm in the laser group and conventional drilling group, respectively. While the mean deviation at the apex between the planned and prepared implant beds were 0.70±0.26 mm and 0.26±0.08 ,the mean vertical deviations were 0.06±0.15 mm and 0.02±0.05 mm for the laser group and the conventional drilling group, respectively. Conclusion: It is possible to prepare an implant bed properly with the aid of Er,Cr:YSGGlaser by using SLA surgical guide.

Seymen, Gülin; Turgut, Zeynep; Berk, Gizem; Bodur, Ay?en

2013-01-01

51

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

52

Phase stable rare earth garnets  

DOEpatents

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

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

2013-06-11

53

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

54

Low-temperature ferromagnetic resonance in epitaxial garnet films on paramagnetic substrates  

NASA Astrophysics Data System (ADS)

The temperature dependence (4.2 300 K) of ferromagnetic resonance (FMR) in the 3-cm range in films of yttrium-iron garnet (YIG)1.7 3 ?m thick, epitaxially grown on a paramagnetic gadolinium-gallium garnet (GGG) paramagnetic substrate is studied. It is found that with decrease in temperature, beginning at T ? 70 K, the temperature dependences of the resonant FMR fields{res/?} and{res/?} for magnetic fields applied parallel and perpendicular to the normal to the film deviate from similar dependences for a free thin YIG plate, which approach the value of ?/? for YIG. This deviation increases approximately in proportion to T-1, reaching hundreds of Oe at T=4.2 K. It is established that the given effect is related to the additional static magnetic field ?Hp created in the YIG film by the paramagnetic substrate, and is dependent on the form of the latter.

Danilov, V. V.; Lyfar', D. L.; Lyubon'ko, Yu. V.; Nechiporuk, A. Yu.; Ryabchenko, S. M.

1989-04-01

55

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

56

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

SciTech Connect

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

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

2012-09-15

57

High energy resolution with transparent ceramic garnet scintillators  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

58

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

SciTech Connect

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

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

2014-10-01

59

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

60

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

E-print Network

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

61

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2001-01-01

62

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

SciTech Connect

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

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

2007-07-30

63

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

64

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

65

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2013-01-01

66

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

PubMed

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

Oitmaa, J; Falk, Thomas

2009-03-25

67

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

SciTech Connect

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

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

2012-06-15

68

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2011-01-01

69

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2010-01-01

70

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2012-01-01

71

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2006-01-01

72

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

E-print Network

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

Lin, Jung-Fu "Afu"

73

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2000-01-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

75

Industrial garnet  

USGS Publications Warehouse

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

Olson, D.W.

2007-01-01

76

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

E-print Network

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

77

MTAMAGNTI SME DU GRENAT D'ERBIUM ET DE GALLIUM  

E-print Network

281 M�TAMAGN�TI SME DU GRENAT D'ERBIUM ET DE GALLIUM J. P. REDOULES, P. CARRARA, A. R. FERT, M. C gallate d'erbium suivant les trois directions [001], [011] et [111], à une température voisine de 0,080 °K modèle d'Ising. Abstract. 2014 Experimental study of the metamagnetism of erbium gallium garnet along

Paris-Sud XI, Université de

78

Nonlinear characteristics of magnetooptic Bragg diffraction in bismuth substituted yttrium iron garnet films  

NASA Astrophysics Data System (ADS)

In this article, the nonlinear characteristics of magnetostatic forward volume wave (MSFVW)-based guided-wave magnetooptic Bragg cell modulators in bismuth-substituted yttrium iron garnet-gadolinium gallium garnet waveguides using nonuniform bias magnetic field are reported. First, the dispersion characteristics of the MSFVW under nonuniform bias magnetic field are analyzed, and the explicit expression for its bandwidth is determined. The transmission measurements of the MSFVW show that owing to the nonuniform magnetic field, the bandwidth is significantly increased. Next, the results of noncollinear magnetooptic (MO) Bragg diffraction experiments using the MSFVW in the frequency range from 2.0 to 4.0 GHz are presented. Two types of nonlinear process, namely, the four-magnon decay and modulation instabilities, are observed. However, the MO experiments at the carrier frequency of 2.85, 3.10, and 3.25 GHz suggest that the decay instabilities did not play a significant role in the MO interaction because of the larger degree of phase mismatch induced by the satellite waves generated during the nonlinear processes. We find that despite the presence of the decay instabilities, the MO Bragg diffraction characteristics still comply with that predicted by the coupled-mode theory before the nonlinear processes evolve into the modulation instabilities. Once the four-magnon modulation instabilities set in at the threshold powers, the MO Bragg diffraction will incur a drop in diffraction efficiency by as much as 9%. This feature results from perturbation of the satellite waves of smaller wave numbers induced in the modulation instabilities that lead to the MO phase mismatch. A model is established to describe the combined contributions of the initial MSFVW and the excited satellite waves associated with the modulation instabilities to the MO Bragg diffraction characteristics.

Su, Jun; Tsai, Chen S.

2000-02-01

79

Gallium complexes and solvent extraction of gallium  

SciTech Connect

This patent describes a process for recovering gallium from aqueous solutions containing gallium which comprises contacting such a solution with an organic solvent containing at least 2% by weight of a water-insoluble N-organo hydroxamic acid having at least about 8 carbon atoms to extract gallium, and separating the gallium loaded organic solvent phase from the aqueous phase.

Coleman, J.P.; Graham, C.R.; Monzyk, B.F.

1988-05-03

80

NUMEX GARNET PAPRIKA  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

81

Electrospun cellulose acetate-garnet nanocomposite magnetic fibers for bioseparations.  

PubMed

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

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

2014-01-01

82

Molecular Structure of Garnet  

NSDL National Science Digital Library

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

2002-09-06

83

Garnets as hydrochronometers  

SciTech Connect

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

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

1992-01-01

84

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

85

Magnetostriction of Dilute Dysprosium Iron and of Gadolinium Iron Garnets  

Microsoft Academic Search

??,2 and ?&egr;,2 have been measured on a series of partially substituted DyxY1?xIG single crystals between 4.2° and 300°K and in fields up to 110 kOe. Because of the ground-state configuration of the Dy3+ ion (6H15?2) in the crystal field, DyIG has a large magnetostriction. However, since the exchange field on the rare-earth ion is small (Hex ≈ 300 kOe),

A. E. Clark; J. J. Rhyne; E. R. Callen

1968-01-01

86

Faraday rotation spectra of bismuth-substituted ferrite garnet films with in-plane magnetization L. E. Helseth, R. W. Hansen, E. I. Il'yashenko, M. Baziljevich, and T. H. Johansen  

E-print Network

Faraday rotation spectra of bismuth-substituted ferrite garnet films with in-plane magnetization L 2 October 2001 Single crystal films of bismuth-substituted ferrite garnets have been synthesized changes significantly with the amount of substituted gallium and bismuth. Furthermore, the experimental

Johansen, Tom Henning

87

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

E-print Network

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

Johansen, Tom Henning

88

Short communication Gallium and oxygen accumulations on gallium nitride surfaces  

E-print Network

Short communication Gallium and oxygen accumulations on gallium nitride surfaces following argon Available online 17 April 2004 Abstract Metallic gallium was observed on the surfaces of GaN commercial rights reserved. Keywords: Gallium nitride; Argon ion milling; Ultra-high vacuum 1. Introduction Gallium

Timmers, Heiko

89

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

90

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

91

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

PubMed

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

Ametani, K

1978-06-01

92

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

93

Preventing Supercooling Of Gallium  

NASA Technical Reports Server (NTRS)

Principle of heterogeneous nucleation exploited to prevent gallium from supercooling, enabling its use as heat-storage material that crystallizes reproducibly at its freezing or melting temperature of 29 to 30 degrees C. In original intended application, gallium used as heat-storage material in gloves of space suits. Terrestrial application lies in preparation of freezing-temperature reference samples for laboratories. Principle of heterogeneous nucleation also exploited similarly in heat pipes filled with sodium.

Massucco, Arthur A.; Wenghoefer, Hans M.; Wilkins, Ronnie

1994-01-01

94

Laserspektroskopie Gadoliniums Fingerabdruck  

SciTech Connect

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

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

2003-05-31

95

Garnet-clinopyroxene geothermometer  

Microsoft Academic Search

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

S. K. Saxena

1979-01-01

96

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

Microsoft Academic Search

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

N. Shimizu

1975-01-01

97

Zinc and gallium diffusion in gallium antimonide  

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

98

Crystal Chemistry of Melanite Garnet  

NASA Technical Reports Server (NTRS)

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

Nguyen, Dawn Marie

1999-01-01

99

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

100

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

101

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

102

Tumor growth suppression by gadolinium-neutron capture therapy using gadolinium-entrapped liposome as gadolinium delivery agent.  

PubMed

Neutron capture therapy (NCT) is a promising non-invasive cancer therapy approach and some recent NCT research has focused on using compounds containing gadolinium as an alternative to currently used boron-10 considering several advantages that gadolinium offers compared to those of boron. In this study, we evaluated gadolinium-entrapped liposome compound as neutron capture therapy agent by in vivo experiment on colon-26 tumor-bearing mice. Gadolinium compound were injected intravenously via tail vein and allowed to accumulate into tumor site. Tumor samples were taken for quantitative analysis by ICP-MS at 2, 12, and 24 h after gadolinium compound injection. Highest gadolinium concentration was observed at about 2 h after gadolinium compound injection with an average of 40.3 ?g/g of wet tumor tissue. We performed neutron irradiation at JRR-4 reactor facility of Japan Atomic Energy Research Institute in Tokaimura with average neutron fluence of 2×10¹² n/cm². The experimental results showed that the tumor growth suppression of gadolinium-injected irradiated group was revealed until about four times higher compared to the control group, and no significant weight loss were observed after treatment suggesting low systemic toxicity of this compound. The gadolinium-entrapped liposome will become one of the candidates for Gd delivery system on NCT. PMID:23743325

Dewi, Novriana; Yanagie, Hironobu; Zhu, Haito; Demachi, Kazuyuki; Shinohara, Atsuko; Yokoyama, Kazuhito; Sekino, Masaki; Sakurai, Yuriko; Morishita, Yasuyuki; Iyomoto, Naoko; Nagasaki, Takeshi; Horiguchi, Yukichi; Nagasaki, Yukio; Nakajima, Jun; Ono, Minoru; Kakimi, Kazuhiro; Takahashi, Hiroyuki

2013-07-01

103

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

PubMed

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

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

2014-09-15

104

Garnet Random-Access Memory  

NASA Technical Reports Server (NTRS)

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

Katti, Romney R.

1995-01-01

105

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

106

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

107

Effect of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium  

E-print Network

Effect of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium Qin of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium Qin Xu,1 Nikolai by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium

Brown, Eric

108

Gallium--A smart metal  

USGS Publications Warehouse

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

Foley, Nora; Jaskula, Brian

2013-01-01

109

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

E-print Network

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

Tommasi, Andrea

110

Magneto-optic properties of rare earth iron garnet crystals in the wavelength range 1.1-1.7 micron and their use in device fabrication  

NASA Astrophysics Data System (ADS)

The wavelength and temperature dependence of the Faraday rotation together with the optical loss spectra of yttrium, gadolinium, terbium, dysprosium, holmium, erbium and ytterbium iron garnets are reported for wavelengths in the range 1.1-1.7 micron. It is demonstrated that the Faraday rotation of all the iron garnets decreases with increasing wavelength with the exception of ytterbium iron garnet which, for wavelengths in excess of 1.3 micron, possesses a wavelength independent Faraday rotation of 5.7 + or - 0.3 deg/mm. The performance of magneto-optic switches, isolators, modulators and deflectors constructed using each of these materials is discussed with particular emphasis on their operation at 1.3 micron and 1.55 micron, the wavelengths of interest in current optical fiber systems. It is concluded that whilst yttrium iron garnet or holmium iron garnet are best suited to the fabrication of devices operating at a single wavelength, for broadband operation ytterbium iron garnet is to be preferred.

Booth, R. C.; White, E. A. D.

1984-03-01

111

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

NASA Technical Reports Server (NTRS)

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

1972-01-01

112

Solar Abundance of Gallium  

PubMed Central

The spectral region around the ?4172 Å resonance line of gallium has been synthesized at disk positions ? = 1.0, 0.5, and 0.3. The center-limb variation can be reproduced by Elste's semiempirical model if a macroturbulent smearing of the emergent spectrum due to mass motions with mean velocity decreasing with altitude are introduced. The abundance of Ga derived from disk position ? = 1 is found to be log [N(Ga)/N(H)] + 12 = 2.80. PMID:16578709

Ross, John; Aller, Lawrence

1970-01-01

113

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

114

Gallium Arsenide Domino Circuit  

NASA Technical Reports Server (NTRS)

Advantages include reduced power and high speed. Experimental gallium arsenide field-effect-transistor (FET) domino circuit replicated in large numbers for use in dynamic-logic systems. Name of circuit denotes mode of operation, which logic signals propagate from each stage to next when successive stages operated at slightly staggered clock cycles, in manner reminiscent of dominoes falling in a row. Building block of domino circuit includes input, inverter, and level-shifting substages. Combinational logic executed in input substage. During low half of clock cycle, result of logic operation transmitted to following stage.

Yang, Long; Long, Stephen I.

1990-01-01

115

The rhetoric of Henry Highland Garnet.  

E-print Network

??In the nineteenth century Henry Highland Garnet employed important rhetorical strategies to the abolition, colonization, and civil rights movements. His religious and patriotic appeals complemented… (more)

Winkelman, Diana Michelle.

2007-01-01

116

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

117

GALLIUM--1997 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--1997 29.1 GALLIUM By Deborah A. Kramer Gallium demand in the United States was supplied by imports, primarily high-purity gallium from France and low-purity material from Russia. Optoelectronic devices manufactured from gallium arsenide (GaAs) continued to be the principal use for gallium. Increased

118

Gallium Safety in the Laboratory  

SciTech Connect

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

Cadwallader, L.C.

2003-05-07

119

Gallium Safety in the Laboratory  

SciTech Connect

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

Lee C. Cadwallader

2003-06-01

120

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

NASA Astrophysics Data System (ADS)

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

Koga, I.; Ogasawara, Y.

2012-12-01

121

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

NASA Astrophysics Data System (ADS)

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 5×10-24ecm, which is a factor of 40 below the limit obtained from the only previous solid-state EDM experiment. The result is limited by the imperfect discrimination of an unexpectedly large voltage that is even upon the reversal of the sample magnetization.

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

2005-12-01

122

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

123

Pyroxene solid solution in garnets included in diamond  

Microsoft Academic Search

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

R. O. Moore; John J. Gurney

1985-01-01

124

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

125

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

126

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

127

Gallium and Reactor Neutrino Anomalies  

NASA Astrophysics Data System (ADS)

The observed deficit in the Gallium radioactive source experiments may be interpreted as a possible indication of active-sterile ? mixing. In the effective framework of two-neutrino mixing we obtain sin2??0.03 and ?m?0.1 eV. The compatibility of this result with the data of the Bugey reactor ? disappearance experiments is studied. It is found that the Bugey data present a hint of neutrino oscillations with 0.02?sin2??0.08 and ?m?1.8 eV, which is compatible with the Gallium allowed region of the mixing parameters. This hint persists in the combined analysis of Gallium, Bugey, and Chooz data.

Acero, M. A.; Giunti, C.; Laveder, M.

2009-03-01

128

Mineral resource of the month: gallium  

USGS Publications Warehouse

The metal element gallium occurs in very small concentrations in rocks and ores of other metals — native gallium is not known. As society gets more and more high-tech, gallium becomes more useful. Gallium is one of only five metals that are liquid at or close to room temperature. It has one of the longest liquid ranges of any metal (29.8 degrees Celsius to 2204 degrees Celsius) and has a low vapor pressure even at high temperatures. Ultra-pure gallium has a brilliant silvery appearance, and the solid metal exhibits conchoidal fracture similar to glass.

Jaskula, Brian

2009-01-01

129

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

130

Structural, optical and magnetic properties of gadolinium sesquioxide nanobars synthesized via thermal decomposition of gadolinium oxalate  

SciTech Connect

Graphical abstract: - Highlights: • The cubic Gd{sub 2}O{sub 3} nanobars are synthesized by decomposition of C{sub 6}H{sub 20}Gd{sub 2}O{sub 22}. • The nanoparticles are rectangular bar shape with high porous surface. • The combination of magnetic and optical properties within a single particle. • The Gd{sub 2}O{sub 3} nanobars have tailorable nanostructure, wide bandgap and are paramagnetic. - Abstract: Gadolinium oxide nanobars were obtained by thermal decomposition of gadolinium oxalate, which was synthesized by the chemical precipitation method along with glycerol. The functional group analysis and formation of gadolinium oxide from gadolinium oxalate were characterized by the Fourier transform infrared spectroscopy and thermo gravimetric analyzer. The crystal structure, average crystallite size, and lattice parameter were analyzed by X-ray diffraction technique. Moreover, Raman shifts, elemental composition and morphology of the gadolinium oxide was widely investigated by the laser Raman microscope, X-ray photoelectron spectroscopy, FE-SEM-EDAX and HR-TEM, respectively. Furthermore, the optical properties like band gap, absorbance measurement of the gadolinium oxide were extensively examined. In addition, the paramagnetic property of gadolinium oxide nanobars was explored by the vibrating sample magnetometer.

Manigandan, R.; Giribabu, K.; Suresh, R. [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu (India); Vijayalakshmi, L. [Annai Veilankanni's College for Women (Arts and Science), Saidapet, Chennai 600015, Tamil Nadu (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu (India); Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu (India)

2013-10-15

131

Potential effects of gallium on cladding materials  

SciTech Connect

This paper identifies and examines issues concerning the incorporation of gallium in weapons derived plutonium in light water reactor (LWR) MOX fuels. Particular attention is given to the more likely effects of the gallium on the behavior of the cladding material. The chemistry of weapons grade (WG) MOX, including possible consequences of gallium within plutonium agglomerates, was assessed. Based on the calculated oxidation potentials of MOX fuel, the effect that gallium may have on reactions involving fission products and possible impact on cladding performance were postulated. Gallium transport mechanisms are discussed. With an understanding of oxidation potentials and assumptions of mechanisms for gallium transport, possible effects of gallium on corrosion of cladding were evaluated. Potential and unresolved issues and suggested research and development (R and D) required to provide missing information are presented.

Wilson, D.F.; Beahm, E.C.; Besmann, T.M.; DeVan, J.H.; DiStefano, J.R.; Gat, U.; Greene, S.R.; Rittenhouse, P.L.; Worley, B.A.

1997-10-01

132

Renal amyloidosis. Evaluation by gallium imaging  

SciTech Connect

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

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

1986-09-01

133

Mg self-diffusion in pyrope garnet  

Microsoft Academic Search

Mg self-diffusion coefficients were experimentally determined for natural pyrope-alman- dine garnet in a I atm CO-C02 gas-mixing furnace at temperatures of 800-1000 DC. Diffusion couples consist of polished garnet crystals covered with a thin film of enriched stable-isotope oxide produced by high-vacuum thermal evaporation of 25MgO. Experi- ments conducted at quartz + fayalite + magnetite f02 provide 25Mgdiffusion coefficients as

CRAIG S. ScHWANDT; HENRY R. WESTRICH

134

GALLIUM--1999 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--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% of gallium consumed in the United States was in the form of gallium arsenide (GaAs). Analog integrated

135

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

136

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

137

Liquid gallium rotary electric contract  

NASA Technical Reports Server (NTRS)

Due to its low vapor pressure, gallium, when substituted for mercury in a liquid slip ring system, transmits substantial amounts of electrical current to rotating components in an ultrahigh vacuum. It features low electrical loss, little or no wear, and long maintenance-free life.

Przybyszewski, J. S.

1969-01-01

138

(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

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally, primary gallium gallium from imported primary gallium metal and new scrap. Imports of gallium, which supplied most of U

139

Intercomparison of garnet barometers and implications for garnet mixing models  

SciTech Connect

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

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

1985-01-01

140

Accepted Manuscript Title: Isolation and characterization of Gallium resistant  

E-print Network

Accepted Manuscript Title: Isolation and characterization of Gallium resistant Pseudomonas of Gallium resistant Pseudomonas aeruginosa mutants, International Journal of Medical Microbiology (2013 Accepted M anuscript Isolation and characterization of Gallium resistant Pseudomonas aeruginosa mutants

Wood, Thomas K.

141

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

142

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

143

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

NASA Astrophysics Data System (ADS)

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 naturally abundant isotopes of gadolinium, with SIMS ion microscopy. T98G human glioblastoma cells were treated for 24 h with 25 mg/ml of the metal ion complex diethylenetriaminepentaacetic acid Gd(III) dihydrogen salt hydrate (Gd-DTPA). Gd-DTPA is a contrast enhancing agent used for MRI of brain tumors, blood-brain barrier impairment, diseases of the central nervous system, etc. A highly heterogeneous subcellular distribution was observed for gadolinium-157. The nuclei in each cell were distinctly lower in gadolinium-157 than in the cytoplasm. Even within the cytoplasm the gadolinium-157 was heterogeneously distributed. The other six naturally abundant isotopes of gadolinium were imaged from the same cells and exhibited a subcellular distribution consistent with that observed for gadolinium-157. These observations indicate that SIMS ion microscopy may be a viable approach for subcellular studies of gadolinium containing neutron capture therapy drugs and may even play a major role in the development and validation of new gadolinium contrast enhancing agents for diagnostic MRI applications.

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

2004-06-01

144

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

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

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

145

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

Microsoft Academic Search

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

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

2010-01-01

146

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

E-print Network

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

147

Modelling of compound semiconductors: Analytical bondorder potential for gallium, nitrogen and gallium  

E-print Network

Modelling of compound semiconductors: Analytical bond­order potential for gallium, nitrogen and gallium nitride J Nordy, K Albez, P Erhartzand K Nordlundy y University of Helsinki, Accelerator.20.Ja,61.72.Bb 1. Introduction Gallium nitride is a semiconducting compound material of high

Nordlund, Kai

148

Epitaxial Deposition Of Germanium Doped With Gallium  

NASA Technical Reports Server (NTRS)

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

Huffman, James E.

1994-01-01

149

The Geoscience Affec-ve Research NETwork (GARNET) Project  

E-print Network

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

Elser, Jim

150

Radiation effects in ferrate garnet S. Utsunomiya a  

E-print Network

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

Utsunomiya, Satoshi

151

Petrogenesis of garnet lherzolite, Cima di Gagnone, Lepontine Alps  

Microsoft Academic Search

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

Bernard W. Evans; Volkmar Trommsdorff

1978-01-01

152

Garnet: Comprehensive Support for Graphical, Highly Interactive User Interfaces  

Microsoft Academic Search

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

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

1990-01-01

153

Structural relaxation around substitutional Cr3+ in pyrope garnet  

E-print Network

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

154

The Prototype-Instance Object Systems in Amulet and Garnet  

E-print Network

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

Myers, Brad A.

155

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

E-print Network

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

Skemer, Philip

156

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

157

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

E-print Network

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

Paris-Sud XI, Université de

158

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

SciTech Connect

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

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

2014-02-07

159

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

160

Substrates for gallium nitride epitaxy  

Microsoft Academic Search

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

L. Liu; J. H. Edgar

2002-01-01

161

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

Microsoft Academic Search

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

Georg Hoinkes

1986-01-01

162

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

163

Method of separating and purifying gadolinium-153  

DOEpatents

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

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

2001-01-01

164

Micro-Raman Determination of the Composition of Ugrandite Garnets  

NASA Astrophysics Data System (ADS)

A fast method to obtain the molar composition of garnets starting from their Raman spectra was recently proposed. The method, called MIRAGEM—MIcro-RAman Garnets Evaluation Method is based on the assumption that in a garnet solid-solution the Raman wavenumbers are linear combinations of end-member wavenumbers, weighted by their molar fraction. In this work, the application of the MIRAGEM method to garnets belonging to the ugrandite family is discussed in detail, showing very good correspondence with electron-microscope-microprobe results in the grossular-andradite series. Unexpected two-mode behavior of a Raman peak in garnets with large amount of uvarovite is found.

Bersani, D.; Andò, S.; Vignola, P.; Marino, I.-G.; Lottici, P. P.

2009-08-01

165

Energy loss of silver ions in gadolinium  

NASA Astrophysics Data System (ADS)

The energy loss of silver ions in metallic gadolinium foil at low velocities (2.7-4.3)v0, where v0 is the Bohr velocity, was measured with the Doppler shift technique. The results are about 20% smaller than the predictions of a semiempirical formulation [J. F. Ziegler, J. P. Biersack, and U. L. Littmark, in The Stopping and Ranges of Ions in Solids, edited by J. F. Ziegler (Pergamon, New York, 1985), Vol. 1] for the electronic stopping power.

Ribas, R. V.; Medina, N. H.; Rao, M. N.; Cybulska, E. W.; Seale, W. A.

1995-03-01

166

Determination of gallium by adsorptive stripping voltammetry.  

PubMed

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

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

2004-02-27

167

Thermodynamic binding constants for gallium transferrin  

Microsoft Academic Search

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.

Wesley R. Harris; Vincent L. Pecoraro

1983-01-01

168

Polarization properties of garnet and groove films on garnet in the transmission and reflection modes.  

PubMed

Stokes polarimeters are most commonly used to measure the state of polarization of optical wave. Dependence of Stokes parameters, degree of polarization on external magnetic field are presented for garnet and groove films on garnet in the transmission and reflection modes. The Stokes parameters S1, S2, S3 of different modes show different tendency and asymmetrically change when the external magnetic field change, while the degree of polarization basically unchange. PMID:24515174

Jiao, Xinbing; Ma, Yue; Ma, Lixin; Gao, Jun; Lei, Wenfeng; Chen, Lin; Nguyen, Truong Giang

2014-01-27

169

GALLIUM--1998 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--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, primarily high-purity material from France and low- purity material from Russia. More than 95% of gallium

170

GALLIUM--2001 29.1 By Deborah A. Kramer  

E-print Network

GALLIUM--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 influencing domestic gallium demand was the decline in the purchase of new cellular telephone products

171

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2010. One company in Utah  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2010. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

172

(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

60 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

173

(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

64 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

174

(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

62 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

175

(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

66 GALLIUM (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 Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

176

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1998. Two companies in  

E-print Network

66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1998. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

177

(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

62 GALLIUM (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 Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

178

(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

58 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most of U

179

(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

62 GALLIUM (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 Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

180

(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

62 GALLIUM (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 Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

181

(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

66 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

182

(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

64 GALLIUM (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 Oklahoma recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

183

(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

64 GALLIUM (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 Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

184

(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

66 GALLIUM (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 Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most

185

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2011. One company in Utah  

E-print Network

58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2011. One company in Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most of U

186

(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

64 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

187

(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

60 GALLIUM (Data in kilograms of gallium content, unless noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1995. Two companies in Oklahoma and Utah recovered and refined gallium from scrap and impure gallium metal. Imports of gallium, which supplied most of U

188

(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

58 GALLIUM (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 recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from

189

Domain Collapse in Grooved Magnetic Garnet Material  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

191

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

192

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

193

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

194

The surface tension of liquid gallium  

NASA Technical Reports Server (NTRS)

The surface tension of liquid gallium has been measured using the sessile drop technique in an Auger spectrometer. The experimental method is described. The surface tension in mJ/sq m is found to decrease linearly with increasing temperature and may be represented as 708-0.66(T-29.8), where T is the temperature in centigrade. This result is of interest because gallium has been suggested as a model fluid for Marangoni flow experiments. In addition, the surface tension is of technological significance in the processing of compound semiconductors involving gallium.

Hardy, S. C.

1985-01-01

195

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

196

Garnets from the Camafuca-Camazambo kimberlite (Angola).  

PubMed

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

Correia, Eugénio A; Laiginhas, Fernando A T P

2006-06-01

197

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

E-print Network

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

198

Electron probe microanalysis of epitaxial garnet films  

NASA Astrophysics Data System (ADS)

The capability of computer controlled wavelength dispersive microprobe instrumentation was tested by application to quantitative analysis of multi-element garnet layers. The depth of X-ray production and influence of substrate were studied on films with thickness ranging from 0.7 to 15 ?m. Test analyses of well-defined bulk garnet materials using selected polycrystalline and single crystal calibration standards showed the systematic error not exceed a value of ±0.3 wt% element, bringing it close to the limits imposed by the reproducibility of the measurements. The time required for a non-destructive analysis by automatic data acquisition and on-line matrix correction is about 200 s (9 elements) which is acceptable for routine analysis of large series of samples. This includes the measurement of concentrations <1 wt% with a reproducibility of about 15%.

Willich, P.; Tolksdorf, W.; Obertop, D.

1981-06-01

199

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

200

Super-Si garnet exsolution kinetics denotes multistage mantle exhumation  

NASA Astrophysics Data System (ADS)

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

Spengler, Dirk; Nishihara, Yu; Fujino, Kiyoshi

2013-04-01

201

Symmetry and magnetoelectric effects in garnet crystals and films  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

202

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

203

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

204

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

205

Generator for gallium-68 and compositions obtained therefrom  

DOEpatents

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

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

1981-01-01

206

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

207

Gallium: the backbone of the electronics industry  

Microsoft Academic Search

Gallium is a silvery blue and soft metallic element that enjoys vast application in optoelectronics (e.g., LED’s), telecommunication, aerospace, and many commercial and household items such as alloys, computers and DVD’s. Albeit that gallium represents a small annual tonnage of material, its important impact as the backbone of the worldwide electronics sector goes unnoticed by the popularity of key base

R. R. Moskalyk

2003-01-01

208

High-dose gallium imaging in lymphoma  

Microsoft Academic Search

The role of gallium-67 imaging in the management of patients with lymphoma, traditionally assessed using low tracer doses and the rectilinear scanner, was assessed when using larger doses (7 to 10 mCi) and a triple-peak Anger camera. Gallium scan results in 51 patients with non-Hodgkin's lymphoma and 21 patients with Hodgkin's disease were compared with simultaneous radiologic, clinical, and histopathologic

Kenneth C. Anderson; Robert C. F. Leonard; George P. Canellos; Arthur T. Skarin; William D. Kaplan

1983-01-01

209

Use of gallium-67 in pulmonary disorders  

Microsoft Academic Search

Imaging of the chest cage with gallium-67 (⁶⁷Ga) citrate is relatively easier to perform and interpret than imaging of the abdomen, because normally pulmonary concentration is low after 48 hr and physiologic accumulation in bones and breast can be recognized by its distribution. Modern scintillation detectors, particularly large field cameras with multiple pulse-height analyzers, give substantially better gallium images than

J. K. Siemsen; S. F. Grebe; A. D. Waxman

1978-01-01

210

Ultrasonic Doppler velocimetry in liquid gallium  

Microsoft Academic Search

For the first time, flow velocity is measured in a vortex of liquid gallium, using the pulsed Doppler shift ultrasonic method.\\u000a At the top of a copper cylinder filled with liquid gallium, we spin a disk and create a turbulent vortex with a dominant nearly\\u000a axisymmetric velocity field with little variation in the axial direction. The velocity profiles are shown

Daniel Brito; Henri-Claude Nataf; Philippe Cardin; Julien Aubert; Jean-Paul Masson

2001-01-01

211

Crystallization of metamorphic garnet : nucleation mechanisms and yttrium and rare-earth-element uptake.  

E-print Network

??This dissertation focuses on two areas of garnet porphyroblast crystallization that have until now remained largely uninvestigated: epitaxial nucleation of garnet porphyroblasts and yttrium and… (more)

Moore, Stephanie Jean

2014-01-01

212

Polycrystalline Garnet Porphyroblasts, an EBSD Study  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

213

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

Microsoft Academic Search

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

M. P. Atherton

1968-01-01

214

Metal Contacts to Gallium Arsenide.  

NASA Astrophysics Data System (ADS)

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

Ren, Fan

1991-07-01

215

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

216

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

217

Au-free Ohmic Contacts to Gallium Nitride and Graphene  

E-print Network

This work deals with Au-free contact metallization schemes for gallium nitride (GaN) and graphene semiconductors. Graphene and gallium nitride are promising materials that can potentially be integrated together in the near future for high frequency...

Ravikirthi, Pradhyumna

2014-08-10

218

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

Microsoft Academic Search

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

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

1996-01-01

219

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

Microsoft Academic Search

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

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

1996-01-01

220

Garnet and pyroxene compositions in some diamondiferous eclogites  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

221

Imaging Domains In Magnetic Garnets By Use Of TSMFM  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

222

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

223

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

224

Synthesis of gadolinium oxide magnetoliposomes for magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

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

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

2000-05-01

225

Very high-pressure orogenic garnet peridotites  

PubMed Central

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

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

2007-01-01

226

Elastic moduli of pyrope rich garnets  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

227

Quantum magnetoelectric effect in iron garnet  

NASA Astrophysics Data System (ADS)

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

Yamasaki, Yuichi; Kohara, Yuki; Tokura, Yoshinori

2009-10-01

228

Submicron bubble garnets with nearly isotropic magnetostriction  

NASA Astrophysics Data System (ADS)

Magnetic garnet films with large, negative and nearly equal magnetostriction coefficients along [111] and [100], supporting submicrometer diameter bubbles were grown using the liquid-phase epitaxy technique. Such isotropic magnetostriction was achieved by incorporating dysprosium ions in the dodecahedral sites. Bismuth was also included in these films to provide the essential uniaxial anisotropy and fine tuning of the magnetostriction coefficients. The effect of growth conditions such as the growth temperature and the melt composition on the magnetostriction coefficients is discussed. Ion-implanted contiguous disk devices fabricated using such films are shown to exhibit similar margins for the ``good'' and ``bad'' propagation directions.

Ramesh, M.; Jo, Soonchul; Campbell, R. O.; Kryder, M. H.

1989-09-01

229

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

230

Standard Reference Material 1751: Gallium Melting-Point Standard  

E-print Network

Standard Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse NIST Special Publication 260-157 #12;#12;NIST Special Publication 260-157 XXXX Standard Reference Material 1751: Gallium Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse National Institute of Standards

231

An Asynchronous Microprocessor in Gallium Jose A. Tierno  

E-print Network

An Asynchronous Microprocessor in Gallium Arsenide Jose A. Tierno Alain J. Martin Dralen Borkovic Asynchronous Microprocessor in Gallium Arsenide Jose A. Tierno Alain J. Martin Drazen Borkovic Tak Kwan Lee Abstract In this paper, several techniques for designing asynchronous circuits in Gallium Arsenide

Martin, Alain

232

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 ont été effectuées sur des photoélectrons émis par un cristal d'arséniure de gallium activé. Les.90 1. Introduction. It has been shown [1-4] that a p-type gallium arsenide crystal activated

Paris-Sud XI, Université de

233

Research papers High precision microsampling and preparation of zoned garnet porphyroblasts for  

E-print Network

Research papers High precision microsampling and preparation of zoned garnet porphyroblasts for Sm December 2010 Editor: R.L. Rudnick Keywords: Garnet Geochronology Microsampling Sm/Nd Zoned garnet, and geochronologic analysis of zoned garnets, which have limited the progress and application of this potentially

Baxter, Ethan F.

234

Accommodation of Uranium into the Garnet Structure Sergey V.Yudintsev1  

E-print Network

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

Utsunomiya, Satoshi

235

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

E-print Network

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

Baxter, Ethan F.

236

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

E-print Network

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

Tomislav Ivezic

2010-06-14

237

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

E-print Network

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

Ivezic, Tomislav

2010-01-01

238

Spontaneous formation of quantum height manganese gallium islands and atomic chains on N-polar gallium nitride(0001)  

E-print Network

Spontaneous formation of quantum height manganese gallium islands and atomic chains on N-polar gallium nitride(0001) Abhijit Chinchore, Kangkang Wang,a) Meng Shi, Yinghao Liu,b) and Arthur R. Smithc) Deposition of manganese onto the gallium-rich, nitrogen-polar GaN(0001) surface results in the formation

239

Colloidal transport on magnetic garnet films.  

PubMed

This article reports several recent discoveries related to the controlled transport of paramagnetic colloidal particles above magnetic garnet films. The garnet films are thin uniaxial ferromagnetic films in which ferromagnetic domains can be organized into symmetric patterns consisting of stripes or bubbles and generate strong local magnetic field gradients. Application of an external homogeneous magnetic field on a larger scale compared to the spatial periodicity of the magnetic pattern in the film modulates the potential generated at its surface and induces the controlled motion of colloidal particles placed above the film. Several novel dynamical regimes are observed and reported, from localized trajectories to direct particle transport, depending on the geometry of the underlying magnetic pattern and on the parameters, which control the external driving field, such as frequency, strength and direction. Moreover, we show that this strategy allows separation and sorting of bi-disperse particle systems based on the particle size as well as the transport of chemical or biological cargoes attached to the colloidal carriers. Controlled transport of micro-sized cargoes (chemical or biological) by colloidal particle carriers in a microfluidic environment can bring significant contributions in several fields from targeted drug delivery to the realization of precise fluid-based micro-scale devices. PMID:19851538

Tierno, Pietro; Sagués, Francesc; Johansen, Tom H; Fischer, Thomas M

2009-11-14

240

ESCA studies of yttrium aluminum garnets  

SciTech Connect

X-ray photoelectron spectroscopy (XPS/ESCA) has been employed to investigate pure single crystals and powdered samples of yttrium aluminum garnet, Y{sub 3}Al{sub 5}O{sub 12} (YAG), and YAG crystals doped with several rare earth elements (Ln = Pr, Er, Ho, Tm) and a transition metal (Cr). Core level XPS peak shapes of the main elements forming the garnet structure can be rationalized due to different structural environments of particular ions modified by doping. The change of dopant oxidation state also results in variation of XPS peaks and helps to identify the sites in which it takes place. Single-crystal and powder samples give different XPS spectra. Possible sources of these differences are discussed. Similarities and differences between simple and mixed oxides are shown. The structure of YAG suggests the presence of only one independent oxygen ion; however the O(1s) spectra of all YAG systems exhibit two readily discerned peaks. An explanation for this dichotomy is discussed, involving the possible polarization of the oxygen valence electron density between the aluminum and yttrium. Alternative explanations are also considered.

Pawlak, D.A. [Univ. of Warsaw, Warszawa (Poland). Dept. of Chemistry] [Univ. of Warsaw, Warszawa (Poland). Dept. of Chemistry; [Inst. of Electronic Materials Technology, Warszawa (Poland); Wozniak, K. [Univ. of Warsaw, Warszawa (Poland). Dept. of Chemistry] [Univ. of Warsaw, Warszawa (Poland). Dept. of Chemistry; Frukacz, Z. [Inst. of Electronic Materials Technology, Warszawa (Poland)] [Inst. of Electronic Materials Technology, Warszawa (Poland); Barr, T.L.; Fiorentino, D. [Univ. of Wisconsin, Milwaukee, WI (United States)] [Univ. of Wisconsin, Milwaukee, WI (United States); Seal, S. [Univ. of Central Florida, Orlando, FL (United States)] [Univ. of Central Florida, Orlando, FL (United States)

1999-03-04

241

New SMU Gallium Fixed-Point Cells  

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

242

/sup 67/Gallium lung scans in progressive systemic sclerosis  

SciTech Connect

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

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

1983-08-01

243

Garnet-spinel transition in the upper mantle: Review and interpretation  

Microsoft Academic Search

This study carried out a comprehensive review of mantle-derived garnet peridotites on the basis of their garnet-spinel compositional\\u000a relationships. The P-T estimates of the garnet peridotites of both orogenic and xenolithic derivations confirm previously established two garnet-spinel\\u000a transition (GST) zones. Results of natural samples and experimental studies of all the garnet peridotites plot below the first\\u000a GST at low P

Benxun Su; Hongfu Zhang; Sakyi Patrick Asamoah; Kezhang Qin; Yanjie Tang; Jifeng Ying; Yan Xiao

2010-01-01

244

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

245

Modeling of zoning patterns in garnet: Thermodynamic and kinetic aspects  

NASA Astrophysics Data System (ADS)

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

Gulbin, Yu. L.

2013-12-01

246

Preparation and characterization of nanodispersions of yttria, yttrium aluminium garnet and lutetium aluminium garnet.  

PubMed

Refractory and chemically inert nanoparticulate solids like yttria, yttrium aluminium garnet or lutetium aluminium garnet are notoriously difficult to disperse in aqueous solution, although such dispersions might prove useful for 2D- and 3D-printing, deposition of films or other shaping procedures for ceramic green bodies. This work reports on experiments to prepare such dispersions from nanopowders, using a range of selected carboxylic acids as ligands for electrostatic charging and stabilization of the various nanomaterials. The assessment of the system properties achieved combines ?-potential and viscosity (flow curve) measurements in the resulting colloidal systems. Calculations of the molecular electrostatic potential of the ligands were used to correlate the molecular structure of the ligands and their capability to dock to the surface of the solid particles. The colloid chemical data received have then been interpreted on this background; citric acid and polyacrylic acid have been identified as the most attractive dispersants. PMID:23643249

Bredol, Michael; Micior, Joanna

2013-07-15

247

Experimental investigation and application of garnet granulite equilibria  

Microsoft Academic Search

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

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

1983-01-01

248

Thermodynamic properties of almandine-grossular garnet solid solutions  

Microsoft Academic Search

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

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

1978-01-01

249

The origin of garnet and clinopyroxene in ''depleted'' Kaapvaal peridotites  

NASA Astrophysics Data System (ADS)

A detailed petrographic, major and trace element and isotope (Re-Os) study is presented on 18 xenoliths from Northern Lesotho kimberlites. The samples represent typical coarse, low-temperature garnet and spinel peridotites and span a P- T range from ˜60 to 150 km depth. With the exception of one sample (that belongs to the ilmenite-rutile-phlogopite-sulphide suite (IRPS) suite first described by [B. Harte, P.A. Winterburn, J.J. Gurney, Metasomatic and enrichment phenomena in garnet peridotite facies mantle xenoliths from the Matsoku kimberlite pipe, Lesotho. In: Menzies, M. (Ed.), Mantle metsasomatism. Academic Press, London 1987, 145-220.]), all samples considered here have high Mg# and show strong depletion in CaO and Al 2O 3. They have bulk rock Re depletion ages ( TRD) >2.5 Ga and are therefore interpreted as residua from large volume melting in the Archaean. A characteristic of Kaapvaal xenoliths, however, is their high SiO 2 concentrations, and hence, modal orthopyroxene contents that are inconsistent with a simple residual origin of these samples. Moreover, trace element signatures show strong overall incompatible element enrichment and REE disequilibrium between garnet and clinopyroxene. Textural and subtle major element disequilibria were also observed. We therefore conclude that garnet and clinopyroxene are not co-genetic and suggest that (most) clinopyroxene in the Archaean Kaapvaal peridotite xenoliths is of metasomatic origin and crystallized relatively recently, possibly from a melt precursory to the kimberlite. Possible explanations for the origin of garnet are exsolution from a high-temperature, Al- and Ca-rich orthopyroxene (indicating primary melt extraction at shallow levels) or a majorite phase (primary melting at >6 GPa). Mass balance calculations, however, show that not all garnet observed in the samples today is of a simple exsolution origin. The extreme LREE enrichment (sigmoidal REE pattern in all garnet cores) is also inconsistent with exsolution from a residual orthopyroxene. Therefore, extensive metasomatism and probably re-crystallization of the lithosphere after melt-depletion and garnet exsolution is required to obtain the present textural and compositional features of the xenoliths. The metasomatic agent that modified or perhaps even precipitated garnet was a highly fractionated melt or fluid that might have been derived from the asthenosphere or from recycled oceanic crust. Since, to date, partitioning of trace elements between orthopyroxene and garnet/clinopyroxene is poorly constrained, it was impossible to assess if orthopyroxene is in chemical equilibrium with garnet or clinopyroxene. Therefore, further trace element and isotopic studies are required to constrain the timing of garnet introduction/modification and its possible link with the SiO 2 enrichment of the Kaapvaal lithosphere.

Simon, Nina S. C.; Irvine, Gordon J.; Davies, Gareth R.; Pearson, D. Graham; Carlson, Richard W.

2003-12-01

250

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

Microsoft Academic Search

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

Marc M. Hirschmann; Edward M. Stolper

1996-01-01

251

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

252

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

253

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

254

PARTITIONING OF GADOLINIUM IN THE CHEMICAL PROCESSING CELL  

SciTech Connect

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

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

2011-04-27

255

Coercivity contributions in epitaxial garnet layers  

NASA Astrophysics Data System (ADS)

Various mechanisms leading to coercivity phenomena in near-perfect single crystalline epitaxial magnetic garnet layers with 180° Bloch walls were investigated. It was shown that the contributions from the statistical fluctuations of exchange and anisotropy energies are negligibly small. Due to the very low dislocation density ( <10 cm -2) their summarized effect on the coercive force ( Hc) is very small, too. Non-magnetic inclusions have a very low volume fraction, their effect is in the 10 -4 Oe range. The transition layer between substrate and epitaxy can cause significant coercivity increase due to magnetostrictive stresses. The as-grown surface relief of the crystals has a definite dependence on composition, giving a surface contribution to Hc up to some Oe. Coercivity changes caused by chemical and mechanical treatment of the surface are discussed.

Pardavi-Horváth, M.; Balaskó, M.; Vértesy, G.

1984-02-01

256

Magnetoelastic properties of dysprosium aluminum garnet: Theory  

NASA Astrophysics Data System (ADS)

Expressions are derived for the first- and second-order magnetoelastic-energy terms for the Ising-like antiferromagnet dysprosium aluminum garnet. The first-order terms are used to interpret the field dependence of the magnetostriction, and the second-order terms for a similar analysis of recent measurements of magnetoacoustic effects. The agreement is generally satisfactory. The theory also predicts some unusual piezomagnetic effects, one of which may explain the anomalous neutron scattering near the phase boundary in fields parallel to [001] and [110]. The results of this work suggest that magnetoelastic effects may be important for the detailed understanding of large classes of magnetic materials, characterized by an antiferromagnetic structure which does not enlarge the unit cell.

Wolf, W. P.; Huan, C. H. A.

1988-02-01

257

Garnet melt viscosity, surface tension and drainage  

NASA Technical Reports Server (NTRS)

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

Luther, L. C.

1986-01-01

258

Terbium photoluminescence in yttrium aluminum garnet xerogels  

SciTech Connect

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

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

2009-02-15

259

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

260

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

261

Pulmonary gallium-67 uptake in amiodarone pneumonitis  

SciTech Connect

Three patients are presented suffering from interstitial pneumonitis caused by amiodarone. Pulmonary Ga-67 uptake occurred in all three. There appeared to be a discrepancy between the scintigraphic and radiographic findings in two patients. Gallium-67 lung scintigraphy may offer an early, sensitive indicator for amiodarone pneumonitis.

van Rooij, W.J.; van der Meer, S.C.; van Royen, E.A.; van Zandwijk, N.; Darmanata, J.I.

1984-02-01

262

Pulmonary gallium-67 uptake in amiodarone pneumonitis  

Microsoft Academic Search

Three patients are presented suffering from interstitial pneumonitis caused by amiodarone. Pulmonary Ga-67 uptake occurred in all three. There appeared to be a discrepancy between the scintigraphic and radiographic findings in two patients. Gallium-67 lung scintigraphy may offer an early, sensitive indicator for amiodarone pneumonitis.

W. J. van Rooij; S. C. van der Meer; E. A. van Royen; N. van Zandwijk; J. I. Darmanata

1984-01-01

263

Gallium-positive Lyme disease myocarditis  

SciTech Connect

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

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

1985-09-01

264

Development of gallium aluminum phosphide electroluminescent diodes  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

265

Effect of melt composition on Bi incorporation in iron garnets  

NASA Astrophysics Data System (ADS)

The saturation temperature, the growth rate and the crystal composition of rare-earth iron garnet films grown from a PbO?Bi 2O 3?B 2O 3 flux were investigated. The concentrations of the garnet component oxides, the proportions of the flux oxides, B 2O 3 and Bi 2O 3, and the ratio Fe 2O 3/RE 2O 3 in the melt were systematically varied to determine their effect. The melts generally obey Van Erk's theory of solubility and growth rate. However, an increase of either the B or Bi concentration in the melt linearly decreases the rare earth activity, which results in an increase in both the garnet solubility and the effective segregation coefficient of Bi into growing garnet films. Using the rare earth activity calculated from solubility data, a Bi segregation coefficient of 0.0010 is observed that is independent of melt composition and growth temperature.

Fratello, V. J.; Licht, S. J.; Norelli, M. P.

1989-10-01

266

Magneto-Optical Experiments on Rare Earth Garnet Films.  

ERIC Educational Resources Information Center

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

Tanner, B. K.

1980-01-01

267

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

268

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

269

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

Microsoft Academic Search

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

Edward D. Ghent; Mavis Z. Stout

1981-01-01

270

Geochemistry of transition elements in garnet lherzolite nodules in kimberlites  

Microsoft Academic Search

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

N. Shimizu; C. J. Allègre

1978-01-01

271

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

USGS Publications Warehouse

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

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

2006-01-01

272

Torque Measurements on Rare-Earth Doped Yttrium Iron Garnet  

Microsoft Academic Search

This paper describes torque measurements made at 4.2 and 1.5°K on yttrium iron garnet crystals containing small rare-earth ion dopings kindly supplied by Dr. J. F. Dillon, Jr., and Dr. J. W. Nielson of the Bell Telephone Laboratories. Resonance measurements by Dillon (1959) showed that the giant anisotropy peaks observed in yttrium iron garnet at 4.2°K were due to the

R. F. Pearson; R. W. Cooper

1961-01-01

273

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

274

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

275

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

276

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

277

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

278

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

279

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

E-print Network

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

Zack, Thomas

280

Impedance and initial magnetic permeability of gadolinium  

NASA Astrophysics Data System (ADS)

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 the ac exciting current. We have found that the results for ?'(T) below the spin reorientation temperature may be described as a power law of the reduced temperature t =1-T/TSR, where TSR is the spin reorientation temperature. This behavior suggests that a genuine phase transition occurs at TSR. Although the impedance displays a weak anomaly at the Curie temperature, TC, magnetic measurements indicate that the ferromagnetic response of Gd extends up to this critical point. Thus, two different phases characterizes the cooperative magnetic state of this metal. The frequency dependent results for ?' and ?? were fitted to a modified Debye formula and the obtained parameters allow us to discriminate between the contributions from domain-wall motion and from magnetization rotation. We obtain that the dynamical properties of the domain walls in Gd are governed by a broad distribution of frequencies whose average value diverge at TSR. The isothermal magnetoimpedance measurements in temperatures smaller than TSR show an interesting plateau at low dc applied fields. This plateau is limited by a characteristic field HK whose magnitude decreases rapidly to nearly zero at TSR, giving further support for the phase transition scenario at this temperature.

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

2010-03-01

281

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

E-print Network

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

Bascou, Jérôme

282

Laser-induced magnetization dynamics in a cobalt/garnet heterostructure  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

283

Gadolinium-enhanced MRI in central nervous system Behçet's disease.  

PubMed

Two cases of central nervous system Behçet's disease, studied by gadolinium-enhanced MRI, are presented. In one patient, whose clinical picture was dominated by a brain syndrome, the gadolinium enhancement resolved with clinical improvement, although the hyperintense areas in the mesencephalon on T2-weighted images persisted. In the second, who had a pseudobulbar palsy and a mild right hemiparesis, there were many abnormal areas, but an enhancing focus in the posterior limb of the left internal capsule was probably the lesion responsible for the hemiparesis. PMID:8433790

Erdem, E; Carlier, R; Idir, A B; Masnou, P O; Moulonguet, A; Adams, D; Doyon, D

1993-01-01

284

Indium gallium nitride/gallium nitride quantum wells grown on polar and nonpolar gallium nitride substrates  

NASA Astrophysics Data System (ADS)

Nonpolar (m-plane or a-plane) gallium nitride (GaN) is predicted to be a potential substrate material to improve luminous efficiencies of nitride-based quantum wells (QWs). Numerical calculations indicated that the spontaneous emission rate in a single In0.15Ga0.85N/GaN QW could be improved by ˜2.2 times if the polarization-induced internal field was avoided by epitaxial deposition on nonpolar substrates. A challenge for nonpolar GaN is the limited size (less than 10x10 mm2) of substrates, which was addressed by expansion during the regrowth by Hydride Vapor Phase Epitaxy (HVPE). Subsurface damage in GaN substrates were reduced by annealing with NH3 and N2 at 950°C for 60 minutes. It was additionally found that the variation of m-plane QWs' emission properties was significantly increased when the substrate miscut toward a-axis was increased from 0° to 0.1°. InGaN/GaN QWs were grown by Metalorganic Chemical Vapor Deposition (MOCVD) on c-plane and m-plane GaN substrates. The QWs were studied by cathodoluminescence spectroscopy with different incident electron beam probe currents (0.1 nA ˜ 1000 nA). Lower emission intensities and longer peak wavelengths from c-plane QWs were attributed to the Quantum-confined Stark Effect (QCSE). The emission intensity ratios of m-plane QWs to c-plane QWs decreased from 3.04 at 1 nA to 1.53 at 1000 nA. This was identified as the stronger screening effects of QCSE at higher current densities in c-plane QWs. To further investigate these effects in a fabricated structure, biased photoluminescence measurements were performed on m-plane InGaN/GaN QWs. The purpose was to detect the possible internal fields induced by the dot-like structure in the InGaN layer through the response of these internal fields under externally applied fields. No energy shifts of the QWs were observed, which was attributed to strong surface leakage currents.

Lai, Kun-Yu

285

Inflammatory pseudotumor: A gallium-avid mobile mesenteric mass  

SciTech Connect

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

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

1991-08-01

286

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

287

Far-infrared lattice absorption in gallium phosphide B. Pdr (*)  

E-print Network

737 Far-infrared lattice absorption in gallium phosphide B. Pödör (*) Research Laboratory de phosphure de gallium a été mesurée en utilisant un spectromètre à transformée de Fourier à 300 et-infrared lattice absorption in gallium phosphide was measured using a Fourier-transform spectrometer at 300 and 100

Paris-Sud XI, Université de

288

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

289

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

NASA Astrophysics Data System (ADS)

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

Park, Joong-Mok

290

Magnetic Order and Spin Reorientations of R-Gallium (R = gadolinium, dysprosium, holmium and erbium) Intermetallic Compounds  

NASA Astrophysics Data System (ADS)

The magnetic structures and spin reorientations of RGa (R = Gd, Dy, Ho and Er) intermetallic compounds have been investigated using neutron powder diffraction and rare earth Mössbauer spectroscopy. The aim has been to determine the magnetic structures of these compounds before and after their spin reorientation transitions and to understand the role of the crystal field and exchange interactions in the spin reorientation mechanism. The results have been compared with those found from previous single-crystal susceptibility measurements on RGa and the recent 119Sn Mössbauer spectroscopy work on Sn-doped RGa compounds. The magnetic structures obtained at low temperatures are a simple collinear ferromagnetic in DyGa, canted ferromagnetic in HoGa and a non-collinear ferromagnetic in GdGa. The spin reorientation in ErGa was also observed by 166Er Mössbauer spectroscopy. These results show that both the crystal field and exchange interactions play an important role in the reorientation mechanism.

Susilo, Resta

291

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

292

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

293

Gadolinium in water Cherenkov detectors improves detection of supernova ?e  

NASA Astrophysics Data System (ADS)

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

Laha, Ranjan; Beacom, John F.

2014-03-01

294

Thermophysical Properties of Sulfides of Lanthanum, Praseodymium, Gadolinium, and Dysprosium  

Microsoft Academic Search

The temperature dependence of the thermal conductivity, electrical conductivity, thermoelectromotive force, and thermal expansion coefficient for sulfides of lanthanum, gadolinium, praseodymium and dysprosium of the composition Ln3 – xVxS4 is investigated in the temperature range from 300 to 1200 K. It is shown that the transfer phenomena and thermoelectrical properties of the investigated compositions depend on the concentration of current

G. G. Gadzhiev; Sh. M. Ismailov; M. M. Khamidov; Kh. Kh. Abdullaev; V. V. Sokolov

2000-01-01

295

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

296

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

297

Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes  

E-print Network

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

May, E

2012-01-01

298

Gallium arsenide photo-field emission  

Microsoft Academic Search

The development of monochromatic ultrafast electron sources with high brightness and high coherence is increasingly important in both time-resolved and energy-resolved electron microscopy. This work details the fabrication of intrinsic Gallium-Arsenide photo-field emitters and their evaluation as potential source candidates. The emitters were prepared via chemical etching and vacuum heat cleansing of cleaved wafer shards that had been mounted in

Theodore Vecchione

2009-01-01

299

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

300

Gallium arsenide - Solar panel assembly technology  

Microsoft Academic Search

Gallium arsenide (GaAs) solar cell devices are maturing at 18 percent AM0 efficiencies for liquid phase epitaxy (LPE) technology, and efforts must be intensified placing necessary focus on the development of panel assembly techniques, and ultimately panel manufacturing methods capable of maintaining these high efficiencies for on-panel operation. Key problems and solutions are described which were experienced during the assembly

D. Zemmrich; N. Mardesich; B. Macfarlane; R. Loo

1984-01-01

301

Magnetoelastic and optoelastic coupling in (111)- and (110)-oriented bismuth-iron garnet films prepared by sputter epitaxy  

NASA Astrophysics Data System (ADS)

High-quality iron-garnet films of composition Gd3-vBivFe5-w-x-yGdw GaxAlyO12-zArz with 1.02?v?1.45, 0.01?w?0.36, 0.22?x?0.24, 0.26?y?0.38, and 0.002?z?0.014 have been grown epitaxially on (111)- and (110)-oriented gallium garnet substrates with the lattice constant in the range 1.2475?a0(nm)?1.2553 by rf magnetron sputtering in argon plasma. For the study of the optoelastic and magnetoelastic properties of these sputter-epitaxial films the lattice mismatch ?a?=as-a?f has been varied in the range -1.7

Krumme, J.-P.; Doormann, V.; Strocka, B.; Witter, K.; Hemme, H.

1987-11-01

302

Dating Subduction Zone Metamorphism with Garnet and Lawsonite Geochronology  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

303

The effects of rare earth doping on gallium nitride thin films  

NASA Astrophysics Data System (ADS)

The thermal neutron capture cross section of the rare earth (RE) metal isotope Gd-157 is the largest of all known natural elements, which distinguishes the material as a logical candidate for neutron detection. To address an incomplete understanding of rare earth doped Gallium Nitride (GaN) materials, investigations of the surface electronic structure and interface properties of GaN thin films doped with rare earths (Yb, Er, Gd) were undertaken. Lattice ion occupation, bonding, rare earth 4f occupation, and gold Schottky barrier formation were examined using synchrotron photoemission spectroscopy. Measured Debye temperatures indicate substitutional occupation of Ga sites by RE ions. The occupied RE 4f levels, deep within the valence band, suggest that intra-atomic f-f transitions may be more 'blue' than predicted by theoretical models. Thin layers of gold did not wet and uniformly cover the GaN surface, even with rare earth doping of the GaN. The resultant Schottky barrier heights for GaN:Yb, GaN:Er, and GaN:Gd, are 25--55% larger than those reported at the gold to undoped GaN interface. The utility of gadolinium as a neutron detection material was examined via fundamental nuclear and semiconductor physics. Low charge production and the large range of internal conversion electrons limits charge collection efficiency.

McHale, Stephen R.

304

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

E-print Network

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

Utsunomiya, Satoshi

305

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

E-print Network

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

Paris-Sud XI, Université de

306

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

E-print Network

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

Collins, Gary S.

307

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

E-print Network

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

Paris-Sud XI, Université de

308

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

E-print Network

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

Ganguly, Jibamitra

309

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

E-print Network

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

Ganguly, Jibamitra

310

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

E-print Network

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

311

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

E-print Network

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

Ganguly, Jibamitra

312

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

E-print Network

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

313

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

E-print Network

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

Lee, Cin-Ty Aeolus

314

Atomistic Modeling of Native Point Defects in Yttrium Aluminum Garnet Crystals  

E-print Network

Atomistic 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 ALUMINUM GARNET (YAG) is an important material whose technological applications range from lasers

Pandey, Ravi

315

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

E-print Network

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

Andersen, Torgeir Bjørge

316

MITT.STERR.MINER.GES. 150 (2005) VARIETY IN CHEMICAL ZONATION OF GARNET IN ECLOGITE  

E-print Network

MITT.�STERR.MINER.GES. 150 (2005) VARIETY IN CHEMICAL ZONATION OF GARNET IN ECLOGITE FROM NOV�@kueps.kyoto-u.ac.jp Garnet-peridotite body associated with eclogite in Nové Dvory, Czech Republic, belongs to the Gföhl Unit of the Bohemian Massif, and compositional zoning of garnet in eclogite from this body was analyzed. Previous works

Nakamura, Daisuke

317

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

E-print Network

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

318

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

E-print Network

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

Mcdonough, William F.

319

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

E-print Network

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

Hirschmann, Marc

320

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

E-print Network

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

Kolner, Brian H.

321

Joseph M. Pyle Frank S. Spear An empirical garnet (YAG) xenotime thermometer  

E-print Network

concentration in garnet ([Y]Grt) and tem- perature has been observed in xenotime (YPO4)-bearing metapelites from in garnet ([Y]Grt) in xenotime (YPO4)-bearing pe- lites. The assumption made throughout this paper is that the presence of xenotime assures a buered value of aYPO4, and that equilibrium garnet growth during a period

Spear, Frank S.

322

The discovery of garnets closely related to diamonds in the Finsch pipe, South Africa  

Microsoft Academic Search

Magnesium-rich, calcium-poor, lilac coloured garnets have been found in the heavy mineral concentrate of the Finsch kimberlite pipe. Some of these garnets contain sufficient chromium to place them within the compositional field of the garnets previously only reported as inclusions in diamonds.

J. J. Gurney; G. S. Switzer

1973-01-01

323

Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

324

Repurposing of gallium-based drugs for antibacterial therapy.  

PubMed

While the occurrence and spread of antibiotic resistance in bacterial pathogens is vanishing current anti-infective therapies, the antibiotic discovery pipeline is drying up. In the last years, the repurposing of existing drugs for new clinical applications has become a major research area in drug discovery, also in the field of anti-infectives. This review discusses the potential of repurposing previously approved gallium formulations in antibacterial chemotherapy. Gallium has no proven function in biological systems, but it can act as an iron-mimetic in both prokaryotic and eukaryotic cells. The activity of gallium mostly relies on its ability to replace iron in redox enzymes, thus impairing their function and ultimately hampering cell growth. Cancer cells and bacteria are preferential gallium targets due to their active metabolism and fast growth. The wealth of knowledge on the pharmacological properties of gallium has opened the door to the repurposing of gallium-based drugs for the treatment of infections sustained by antibiotic-resistant bacterial pathogens, such as Acinetobacter baumannii or Pseudomonas aeruginosa, and for suppression of Mycobacterium tuberculosis growth. The promising antibacterial activity of gallium both in vitro and in different animal models of infection raises the hope that gallium will confirm its efficacy in clinical trials, and will become a valuable therapeutic option to cure otherwise untreatable bacterial infections. PMID:24532037

Bonchi, Carlo; Imperi, Francesco; Minandri, Fabrizia; Visca, Paolo; Frangipani, Emanuela

2014-01-01

325

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

326

Gallium scintigraphy in bone infarction. Correlation with bone imaging  

SciTech Connect

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

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

1984-01-01

327

Automated realization of the gallium melting and triple points  

NASA Astrophysics Data System (ADS)

In order to improve the automation and convenience of the process involved in realizing the gallium fixed points, an automated apparatus, based on thermoelectric and heat pipe technologies, was designed and developed. This paper describes the apparatus design and procedures for freezing gallium mantles and realizing gallium melting and triple points. Also, investigations on the melting behavior of a gallium melting point cell and of gallium triple point cells were carried out while controlling the temperature outside the gallium point cells at 30 °C, 30.5 °C, 31 °C, and 31.5 °C. The obtained melting plateau curves show dentate temperature oscillations on the melting plateaus for the gallium point cells when thermal couplings occurred between the outer and inner liquid-solid interfaces. The maximum amplitude of the temperature fluctuations was about 1.5 mK. Therefore, the temperature oscillations can be used to indicate the ending of the equilibrium phase transitions. The duration and amplitude of such temperature oscillations depend on the temperature difference between the setting temperature and the gallium point temperature; the smaller the temperature difference, the longer the duration of both the melting plateaus and the temperature fluctuations.

Yan, X.; Duan, Y.; Zhang, J. T.; Wang, W.

2013-09-01

328

Role of gallium-67 in the clinical evaluation of cancer  

Microsoft Academic Search

This review is based primarily on historic data, and it examines the indications for and limitations of gallium-67 scanning in the evaluation of patients with neoplasms. The use of gallium-67 scans is discussed according to tumor type, and data from the most representative and comprehensive studies are included. The results described, some of which were obtained primarily with older imaging

C. Bekerman; P. B. Hoffer; J. D. Bitran

1984-01-01

329

Iso Observations of Ceres: Evidence For Garnet?  

NASA Astrophysics Data System (ADS)

Thermal IR spectra of Ceres have been obtained by ISO in 1997. These data have been compared with various laboratory spectra by [1], but no close match was found. However, there is one salient spectral feature in the ISO data, which consists in a sharp slope and a maximum located at 9.7aµm. We interpret this signature as a Christiansen feature located at particularly long wavelength. Other asteroids observed by ISO have similar signatures located at much shorter wavelength, ranging from 8.0 to 9.0aµm. Only Fe-rich olivine and garnets are known to exhibit a Christiansen feature at such long wavelength. The best candidate mineral is actually andradite, which appears in rocks such as serpentine, eclogite and peridotite, all formed by general metamorphism under pressure and temperature consistent with the interior of a 1000 km-diameter body. Therefore, this material would have form deep inside Ceres, and would have subsequently been exposed at the surface, perhaps in relation with the Piazzi region recently observed by HST [2]. The Christiansen maximum is located at shorter wave- length in the KAO spectra of Ceres [3], which are actually composited from different observations. This difference may be related to the orientation of Ceres and to the visi- bility of the Piazzi region at the time of observations. The presence of material formed in high pressure and temperature is consistent with observations from [4]. [1]Dotto et al. (2000) A&A358, 697-702 [2]Parker et al. (2002) Astron. J. [3]Cohen et al. (1998) Astron. J. 115, 1671-1679. [4]Witteborn et al. (2000) ASP Conf. Ser. 196, 197-200.

Erard, S.; Le Bras, A.

330

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

331

Measurement of pressure changes during laser-activated irrigant by an erbium, chromium: yttrium, scandium, gallium, garnet laser.  

PubMed

The use of Er,Cr:YSGG laser to activate irrigants results in the creation of vapour bubbles and shockwaves. The present study evaluated the magnitude of pressure changes in the root canal during laser-activated irrigation. The root canal of a single extracted maxillary canine was enlarged to a size 40/0.06 file. A pressure sensor was inserted apically into the root canal. The tooth was processed as follows. In the EDTA condition, the tooth was irrigated with 17 % EDTA; in the NaOCl condition, the tooth was irrigated with 3 % NaOCl. In all conditions, the irrigants were activated at 0.75 and 1.75 W for 60 s using RFT2 and MZ2 tips; to analyse the effect of tip placement, the tip was activated at the orifice and after inserting the tip 5 mm deeper than the orifice. Data showed no significant difference between irrigation regimens (p?>?0.05). There were no significant differences of the pressure between RFT2 and MZ2 tips (p?>?0.05). The placement of tips closer to the apex resulted in significantly higher pressure than at the orifice (p?

Peeters, Harry Huiz; De Moor, Roeland J G

2014-06-01

332

A receptor-based bioassay for quantitative detection of gallium.  

PubMed

The detection of gallium in biological samples is required due to its role in the diagnosis of tumor and for possible treatment of malignancies. However, the use of purely instrumental techniques is unsuitable for detection of low levels of gallium in biological matrixes. We have synthesized new protein conjugates based on 4-(2-pyridylazo) ligands. The conjugates were successfully employed for the detection of gallium in biological matrixes using a nonantibody-based sandwich assay format. The recovery level obtained was between 97 and 101.3 with a relative standard deviation of less than 5%. The assay resulted in a detection limit of 5 x 10(-8) M and a remarkable selectivity for gallium(III) relative to other metals investigated. The new method provided adequate accuracy for gallium applicable for animal physiology and clinical toxicology. PMID:10596209

Xu, H; Lee, E; Sadik, O A; Bakhtiar, R; Drader, J; Hendrikson, C

1999-12-01

333

Domain effects in Faraday effect sensors based on iron garnets.  

PubMed

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

Deeter, M N

1995-02-01

334

Transformation of enstatite — diopside — jadeite pyroxenes to garnet  

Microsoft Academic Search

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

Tibor Gasparik

1989-01-01

335

Solid-state gallium-69 and gallium-71 nuclear magnetic resonance spectroscopic studies of gallium analogue zeolites and related systems  

Microsoft Academic Search

The authors have obtained solid-state 11.7-T ⁶⁹Ga and ⁷¹Ga nuclear magnetic resonance (NMR) spectra of a series of gallosilicates (gallium analogues of zeolites Na-X, Na-Y, Na-sodalite, and Na-natrolite). From the apparent ⁶⁹Ga and ⁷¹Ga chemical shifts, values of the nuclear quadrupole coupling constants (e²qQ\\/h) and the true, isotropic chemical shifts (delta\\/sub i) have been deduced for the framework, tetrahedral, Ga(OSi)â

Hye Kyung C. Timken; Eric Oldfield

1987-01-01

336

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

E-print Network

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

Duffy, Thomas S.

337

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

E-print Network

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

Kidd, William S. F.

338

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

NASA Technical Reports Server (NTRS)

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

Wang, H.; Simmons, G.

1974-01-01

339

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

340

Gallium scintigraphic pattern in lung CMV infections  

SciTech Connect

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

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

1994-05-01

341

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

342

Oxide formation during etching of gallium arsenide  

Microsoft Academic Search

Characterisation of n-type GaAs, etched in a 5:1:1 mixture of H2SO4:H2O2:H2O, was performed using X-ray photoelectron spectroscopy (XPS) and electrochemical AC impedance. Quantitative XPS analysis of GaAs indicated that the as-received wafers had a gallium-rich native oxide which was not affected by solvent degreasing treatments. Subsequent, oxidative etching formed a thinner arsenic-rich oxide. It is suggested that etching causes initial

D. Ghidaoui; S. B. Lyon; G. E. Thompson; J. Walton

2002-01-01

343

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

344

Accumulation of MRI contrast agents in malignant fibrous histiocytoma for gadolinium neutron capture therapy  

Microsoft Academic Search

Neutron-capture therapy with gadolinium (Gd-NCT) has therapeutic potential, especially that gadolinium is generally used as a contrast medium in magnetic resonance imaging (MRI). The accumulation of gadolinium in a human sarcoma cell line, malignant fibrosis histiocytoma (MFH) Nara-H, was visualized by the MRI system. The commercially available MRI contrast medium Gd-DTPA (Magnevist®, dimeglumine gadopentetate aqueous solution) and the biodegradable and

T. Fujimoto; H. Ichikawa; T. Akisue; I. Fujita; K. Kishimoto; H. Hara; M. Imabori; H. Kawamitsu; P. Sharma; S. C. Brown; B. M. Moudgil; M. Fujii; T. Yamamoto; M. Kurosaka; Y. Fukumori

2009-01-01

345

Determination of the optical anisotropy of magnetic garnet films.  

PubMed

We show that the application of isotropic coupling prisms instead of birefringent prisms permits the precise determination of the optical anisotropy of magnetic garnet films; these measurements are essential for phase matching and conversion of optical modes. Using this technique, the anisotropy of a (211)-oriented film was measured with silicon prisms. PMID:19741925

Hemme, H; Dötsch, H; Middelberg, J; Kappelt, R; Tolksdorf, W

1987-11-01

346

Diffusion of divalent cations in garnet: multi-couple experiments  

NASA Astrophysics Data System (ADS)

We demonstrate the possibility of studying several diffusion couples in a single run, i.e. under almost similar P- T- t- f_{{{text{O}}_{ 2} }} conditions, allowing direct comparison of the diffusion rates in different diffusion couples. Thus the duration of experimental study and the risk of failure of expensive experimental equipment can be decreased considerably. The diffusion experiments were carried out in piston-cylinder apparatus. Gem-quality garnets of almandine, spessartine and grossular compositions together with inclusion-rich eclogitic garnets were embedded in a powder of natural pyrope and annealed together under dry conditions at P = 1.9-3.2 GPa and T = 1,070-1,400°C. Diffusion profiles were measured by electron microprobe and fitted numerically on the basis of multicomponent diffusion theory. The datasets derived from different diffusion couples yields parameters of the Arrhenius equation for Ca, Mg and Fe in natural eclogitic garnets and Mg, Mn and Fe in gem-quality garnets. We have also studied the effect of grain-boundary diffusion in the sintered pyrope matrix on interdiffusion on the basis of 2D modeling. Under conditions analogous to those of our experimental runs, we show that observed irregularities in some measured diffusion profiles (not applied for the diffusion modeling) can be directly related to the superposition of local grain-boundary diffusion on dominant volume diffusion.

Perchuk, A. L.; Burchard, M.; Schertl, H.-P.; Maresch, W. V.; Gerya, T. V.; Bernhardt, H.-J.; Vidal, O.

2009-05-01

347

Ion irradiation effects in natural garnets: Comparison with zircon  

E-print Network

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

Utsunomiya, Satoshi

348

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

349

Origin of iridescence in garnet: An optical interference study  

Microsoft Academic Search

The optical interference phenomenon of an iridescent grandite garnet was examined by using white light and laser light on the analogy of the X-ray diffraction method. A kinematical interpretation was also made for the observed angle and intensity of interference light. The regularly stratified layers which cause iridescence are deduced to be periodic twins oriented parallel to the growth layers

Hisako Hirai; Hiromoto Nakazawa

1982-01-01

350

Magnetoelastic behaviour in very high magnetic susceptibility garnets  

NASA Astrophysics Data System (ADS)

Effects of compressive stresses applied parallel to the magnetization direction have been investigated on ring-shaped high susceptibility garnets in which the sign of the saturation magnetostriction has been changed by rare earth ion substitutions. The results are consistent and agree with the expression E ? = - {3}/{2}? s? cos2? .

Le Floc'h, M.; Pascard, H.; du Trémolet de Lacheisserie, E.

1995-02-01

351

Photomagnetic Anneal Properties of Silicon-Doped Yttrium Iron Garnet  

Microsoft Academic Search

Torque measurements have been made at 4.2°K on crystals of silicon-doped yttrium iron garnet which were irradiated with infrared light. The radiation caused large photomagnetic anneal effects which were found to depend on the plane of polarization of the light.

R. F. Pearson; A. D. Annis; P. Kompfner

1968-01-01

352

Ferromagnetic Resonance in Terbium-Doped Yttrium Iron Garnet  

Microsoft Academic Search

Calculations have been made on a specific model of a terbium-doped yttrium iron garnet system to determine its behavior in ferrimagnetic resonance. Good qualitative agreement has been found with the experiments of Dillon. Quantitative agreement is probably as good as can be expected in view of the fact that the crystal field has to be determined empirically in the course

L. R. Walker

1962-01-01

353

Isomorphism of actinides and REE in synthetic ferrite garnets  

NASA Astrophysics Data System (ADS)

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

Livshits, T. S.

2010-02-01

354

Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy (abstract)  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

355

Synthesis of nanocrystals of gadolinium carbonate by reaction crystallization.  

PubMed

The formation of nano-sized crystals of gadolinium carbonate via reaction crystallization was studied in a semi-batch crystallizer using gadolinium chloride and ammonium hydrogen carbonate as the reactants. The gadolinium carbonate crystals were formed by the aggregation of primary particles sized about 5 nm. Thereby, the crystallization parameters acting directly on the aggregation of the primary particles, such as the reactant concentrations, non-stoichiometry of the reactants, solution pH, acoustic energy, and agitation speed, were mechanistically investigated. As such, increasing the reactant concentrations enhanced the crystal size due to higher nucleation of the primary particles for the aggregation. Non-stoichiometric reactant concentrations resulted in a significant reduction of the crystal size, due to the adsorption of the excess species on the primary particles. Similarly, the surface charge of the primary particles depended on the solution pH. Thus, the crystal size was reduced when the pH deviated from the neutral point. The acoustic cavitation of the ultrasound was much more effective than the turbulent fluid motion of the agitation in inhibiting the primary particle aggregation. Thus, the crystal size was remarkably reduced, even at a low acoustic energy of 6 watts. PMID:22755060

He, Xin-Kuai; Shin, Dongmin; Kim, Woo-Sik

2012-03-01

356

Homoleptic gadolinium amidinates as precursors for MOCVD of oriented gadolinium nitride (GdN) thin films.  

PubMed

Five new homoleptic gadolinium tris-amidinate complexes are reported, which were synthesized via the salt-elimination reaction of GdCl(3) with 3 equiv of lithiated symmetric and asymmetric amidinates at ambient temperature. The Gd-tris-amidinates [Gd{(N(i)Pr)(2)CR}(3)] [R = Me (1), Et (2), (t)Bu (3), (n)Bu (4)] and [Gd{(NEt)(N(t)Bu)CMe}(3)] (5) are solids at room temperature and sublime at temperatures of about 125 °C (6 × 10(-2) mbar) with the exception of compound 4, which is a viscous liquid at room temperature. According to X-ray diffraction analysis of 3 and 5 as representative examples of the series, the complexes adopt a distorted octahedral structure in the solid state. Mass spectrometric (MS) data confirmed the monomeric structure in the gas phase, and high-resolution MS allowed the identification of characteristic fragments, such as [{(N(i)Pr)(2)CR}GdCH(3)](+) and [{(N(i)Pr)(2)CR}GdNH](+). The alkyl substitution patterns of the amidinate ligands clearly show an influence on the thermal properties, and specifically, the introduction of the asymmetric carbodiimide leads to a lowering of the onset of volatilization and decomposition. Compound 5, which is the first Gd complex with an asymmetric amidinate ligand system to be reported, was, therefore, tested for the MOCVD of GdN thin films. The as-deposited GdN films were capped with Cu in a subsequent MOCVD process to prevent postdeposition oxidation of the films. Cubic GdN on Si(100) substrates with a preferred orientation in the (200) direction were grown at 750 °C under an ammonia atmosphere and exhibited a columnar morphology and low levels of C or O impurities according to scanning electron microscopy, Rutherford backscattering, and nuclear reaction analysis. PMID:23231638

Krasnopolski, Michael; Hrib, Cristian G; Seidel, Rüdiger W; Winter, Manuela; Becker, Hans-Werner; Rogalla, Detlef; Fischer, Roland A; Edelmann, Frank T; Devi, Anjana

2013-01-01

357

Behavior of Zircaloy Cladding in the Presence of Gallium  

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 fuel, on cladding material performance. An experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium, and (2) various concentrations of G~03. Three types of tests were performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests were to determine corrosion mechanisms, thresholds for temperature and concentration of gallium that delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Results have generally been favorable for the use of weapons-grade (WG) MOX fhel. The Zircaloy cladding does react with gallium to form intermetallic compounds at >3000 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. Furthermore, no evidence for grain boundary penetration by gallium or liquid metal embrittlement was observed.

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

1998-09-28

358

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

359

Mechanism of gallium-67 accumulation in tumors  

SciTech Connect

Neoplasms are characterized by increased perfusion, increased permeability of their capillary beds to macromolecules, and a delay in new lymphatic vessel growth. These lead to the increased entry and residency time of macromolecules in the interstitial space of tumors. Multiple factors contribute to the localization of /sup 67/Ga in tumors. Adequate blood supply is essential; at areas with no blood supply such as the necrotic center of a large tumor, there is no /sup 67/Ga accumulation. Gallium-67, mainly in the form of transferrin-67Ga complex, is delivered to the tumor through capillaries with increased permeability. In tumors, some /sup 67/Ga is taken up by tumor cells; some may also be taken up by inflammatory cells when they are present. Gallium-67 binding proteins, such as lactoferrin or ferritin, may also contribute to the accumulation and retention of /sup 67/Ga in tumors; however, their roles are less clear. The intensity of these various factors determine their relative contribution and the degree of /sup 67/Ga accumulation in tumors.56 references.

Tsan, M.F.; Scheffel, U.

1986-07-01

360

Measurement of the solar neutrino capture rate with gallium metal  

SciTech Connect

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

SAGE Collaboration

1999-11-01

361

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

362

Garnet growth interruptions during high- and ultra high-pressure metamorphism constrained by thermodynamic forward models  

NASA Astrophysics Data System (ADS)

Growth and chemical composition of garnet in metamorphic rocks excellently reflect thermodynamic as well kinetic properties of the host rock during garnet growth. This valuable information can be extracted from preserved compositional growth zoning patterns in garnet. However, metamorphic rocks often contain multiple garnet generations that commonly develop as corona textures with distinct compositional core-overgrowth features. This circumstance can lead to a misinterpretation of information extracted from such grains if the age- and metamorphic relations between different garnet generations are unclear. Especially garnets from high-pressure (HP) and ultra high-pressure (UHP) rocks often preserve textures that show multiple growth stages reflected in core-overgrowth differences both in main and trace element composition and in the inclusion assemblage. Distinct growth zones often have sharp boundaries with strong compositional gradients and/or inclusion- and trace-element-enriched zones. Such growth patterns indicate episodic garnet growth as well as growth interruptions during the garnet evolution. A quantitative understanding of these distinct growth pulses enables the relationship between reaction path, age determinations in spatially controlled garnet domains or temperature-time constraints to be fully characterised. In this study we apply thermodynamic forward models to simulate garnet growth along a series of HP and UHP P-T paths, representative for subducted oceanic crust. We study garnet growth in different basaltic rock compositions and under different element fractionation scenarios in order to detect path-dependent P-T regions of limited or ceased garnet growth. Modeled data along P-T trajectories involving fractional crystallisation are assembled in P-T diagrams reflecting garnet growth in a changing bulk rock composition. Our models show that in all investigated rock compositions garnet growth along most P-T trajectories is discontinuous, pulse-like and triggered by relatively discrete mineral reactions under homogeneous as well as fractional equilibrium crystallisation conditions. The effect on the positions of the garnet-forming reactions of fractional crystallisation is limited, whereas garnet mode and composition are influenced at UHP conditions by element fractionation along the P-T trajectories. In water saturated homogeneous equilibrium models a medium- to high-pressure garnet stability field reaching from 350-650°C and 1.2-2.5 GPa is clearly separated from a UHP field above 700°C and 2.7 GPa. Between the two fields the thermodynamically calculated garnet mode decreases, enabling garnet resorption. Fractional garnet crystallisation along the P-T trajectories influences position and shape of this growth interruption but never eliminates it. Our results indicate that multiple garnet growth stages are likely to occur along a single prograde HP P-T path. As garnet formation mostly involves dehydration reactions, episodic garnet growth indicates pulse-like rather than continuous water release from the oceanic crust in subduction zones. Further, it is evident from our results that numerical models must consider non-linear garnet growth rate laws to reflect garnet evolution in HP rocks.

Konrad-Schmolke, M.; Schildhauer, H.

2013-12-01

363

Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

364

GALLIUM--2000 30.1 By Deborah A. Kramer  

E-print Network

devices (LEDs, laser diodes, photodetectors, and solar cells) and ICs. Analog ICs were the largest end consumption rates. Free market gallium prices skyrocketed to reach $1,500 to $2,000 per kilogram, a level

365

Gallium accumulation in early pulmonary Pneumocystis carinii infection  

SciTech Connect

The accumulation of gallium 67 citrate in pulmonary Pneumocystis carinii is well known. The sensitivity of gallium uptake in detecting early inflammatory processes, even when conventional roentgenograms are normal, would seem to make it possible in immunocompromised patients to make a presumptive diagnosis of this serious infection early in its course without using invasive techniques to demonstrate the organism. However, the presence of gallium uptake in radiation pneumonitis, pulmonary drug toxicity, and other processes that also occur in this group limit its usefulness. In our two patients--a young woman with Hodgkin's disease and an elderly woman with small cell lung cancer--this technique proved helpful. Although the latter patient was successfully treated empirically, such empiric treatment should be reserved for patients unable or unwilling to undergo invasive tests. Pulmonary gallium uptake in patients with respiratory symptoms, even with a normal chest film, should prompt attempts to directly demonstrate the organism.

Stevens, D.A.; Allegra, J.C.

1986-09-01

366

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

367

Gallium complexes with ?-diimine and phenazine in various reduced states.  

PubMed

Reaction of ?-diimine-stabilized "digallane" [Ga2L2] with phenazine (Phz) leads to gallium complexes in which Phz and ?-diimine show different reduced forms, demonstrating their noninnocence and diverse coordination modes. PMID:25472501

Zhao, Yanxia; Liu, Yanyan; Wang, Zeyi; Xu, Wenhua; Liu, Bin; Su, Ji-Hu; Wu, Biao; Yang, Xiao-Juan

2014-12-23

368

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

369

Timing and duration of garnet granulite metamorphism in magmatic arc crust, Fiordland, New Zealand  

USGS Publications Warehouse

Pembroke Granulite from Fiordland, New Zealand provides a window into the mid- to lower crust of magmatic arcs. Garnet Sm-Nd and zircon U-Pb ages constrain the timing and duration of high-P partial melting that produced trondhjemitic high Sr/Y magma. Trace element zoning in large, euhedral garnet is compatible with little post growth modification and supports the interpretation that garnet Sm-Nd ages of 126.1??2.0 and 122.6??2.0. Ma date crystal growth. Integration of the garnet ages with U-Pb zircon ages elucidates a history of intrusion(?) and a protracted period of high-temperature metamorphism and partial melting. The oldest zircon ages of 163 to 150. Ma reflect inheritance or intrusion and a cluster of zircon ages ca. 134. Ma date orthopyroxene-bearing mineral assemblages that may be magmatic or metamorphic in origin. Zircon and garnet ages from unmelted gneiss and garnet reaction zones record garnet granulite facies metamorphism at 128 to 126. Ma. Peritectic garnet and additional zircon ages from trondhjemite veins and garnet reaction zones indicate that garnet growth and partial melting lasted until ca. 123. Ma. Two single fraction garnet ages and young zircon ages suggest continued high-temperature re-equilibration until ca. 95. Ma. Phase diagram sections constrain orthopyroxene assemblages to <0.6 GPa @ 650??C, peak garnet granulite facies metamorphic conditions to 680-815??C @ 1.1-1.4. GPa, and a P-T path with a P increase of???0.5. GPa. These sections are compatible with water contents???0.28wt.%, local dehydration during garnet granulite metamorphism, and <0.3. GPa P increases during garnet growth. Results demonstrate the utility of integrated U-Pb zircon and Sm-Nd garnet ages, and phase diagram sections for understanding the nature, duration, and conditions of deep crustal metamorphism and melting. Geochronologic and thermobarometric data for garnet granulite indicate that thickening of arc crust, which caused high-pressure metamorphism in northern Fiordland, must have occurred prior to 126. Ma, that loading occurred at a rate of ca. 0.06. GPa/m.y., and that garnet granulite metamorphism lasted 3-7m.y. Locally-derived partial melts formed and crystallized in considerably less than 10 and perhaps as little as 3m.y. ?? 2010 Elsevier B.V.

Stowell, H.; Tulloch, A.; Zuluaga, C.; Koenig, A.

2010-01-01

370

Gallium uptake by transferrin and interaction with receptor 1.  

PubMed

The kinetics and thermodynamics of Ga(III) exchange between gallium mononitrilotriacetate and human serum transferrin as well as those of the interaction between gallium-loaded transferrin and the transferrin receptor 1 were investigated in neutral media. Gallium is exchanged between the chelate and the C-site of human serum apotransferrin in interaction with bicarbonate in about 50 s to yield an intermediate complex with an equilibrium constant K (1) = (3.9 +/- 1.2) x 10(-2), a direct second-order rate constant k (1) = 425 +/- 50 M(-1) s(-1) and a reverse second-order rate constant k (-1) = (1.1 +/- 3) x 10(4) M(-1) s(-1). The intermediate complex loses a single proton with proton dissociation constant K (1a) = 80 +/- 40 nM to yield a first kinetic product. This product then undergoes a modification in its conformation which lasts about 500 s to produce a second kinetic intermediate, which in turn undergoes a final extremely slow (several hours) modification in its conformation to yield the gallium-saturated transferrin in its final state. The mechanism of gallium uptake differs from that of iron and does not involve the same transitions in conformation reported during iron uptake. The interaction of gallium-loaded transferrin with the transferrin receptor occurs in a single very fast kinetic step with a dissociation constant K (d) = 1.10 +/- 0.12 microM and a second-order rate constant k (d) = (1.15 +/- 0.3) x 10(10) M(-1) s(-1). This mechanism is different from that observed with the ferric holotransferrin and suggests that the interaction between the receptor and gallium-loaded transferrin probably takes place on the helical domain of the receptor which is specific for the C-site of transferrin and HFE. The relevance of gallium incorporation by the transferrin receptor-mediated iron-acquisition pathway is discussed. PMID:16988841

Chikh, Zohra; Ha-Duong, Nguyêt-Thanh; Miquel, Geneviève; El Hage Chahine, Jean-Michel

2007-01-01

371

The effect of copper and gallium compounds on ribonucleotide reductase  

SciTech Connect

The mode of action of copper complexes (CuL and CuKTS) and gallium compounds (gallium nitrate and citrate) in cytotoxicity was studied. The effects of these agents on the enzyme ribonucleotide reductase was investigated by monitoring the tyrosyl free radical present in the active site of the enzyme through electron spin resonance (ESR) spectroscopy. Ribonucleotide reductase, a key enzyme in cellular proliferation, consists of two subunits. M1, a dimer of molecular weight 170,000 contains the substrate and effector binding sites. M2, a dimer of molecular weight 88,000, contains non-heme iron and tyrosyl free radical essential for the activity of the enzyme. In studies using copper complexes, the cellular oxidative chemistry was examined by ESR studies on adduct formation with membranes, and oxidation of thiols. Membrane thiols were oxidized through the reduction of the ESR signal of the thiol adduct and the analysis of sulfhydryl content. Using the radiolabel [sup 59]Fe, the inhibitory action of copper thiosemicarbazones on cellular iron uptake was shown. The inhibitory action of CuL on ribonucleotide reductase was shown by the quenching of the tyrosyl free radical on the M2 subunit. The hypothesis that gallium directly interacts with the M2 subunit of the enzyme and displaces the iron from it was proven. The tyrosyl free radical signal from cell lysates was inhibited by the direct addition of gallium compounds. Gallium content in the cells was measured by a fluorimetric method, to ensure the presence of sufficient amounts of gallium to compete with the iron in the M2 subunit. The enzyme activity, measured by the conversion of [sup 14]C-CDP to the labeled deoxy CDP, was inhibited by the addition of gallium nitrate in a cell free assay system. The immunoprecipitation studies of the [sup 59]Fe labeled M2 protein using the monoclonal antibody directed against this subunit suggested that gallium releases iron from the M2 subunit.

Narasimhan, J.

1992-01-01

372

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

373

Mechanism of gallium-67 accumulation in inflammatory lesions  

Microsoft Academic Search

Multiple factors contribute to the accumulation and retention of gallium-67 in inflammatory lesions. Adequate blood supply is essential. Gallium-67, mainly in the form of transferrin-Ga-67 complex, is delivered to the inflammatory lesions through capillaries with increased permeability. At the site of inflammation, some Ga-67 is taken up by leukocytes and bacteria when they are present. In addition, Ga-67 may also

Min-Fu Tsan

1985-01-01

374

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

375

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

E-print Network

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

Raghavan, Srinivasa

376

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

377

Method of fabricating germanium and gallium arsenide devices  

NASA Technical Reports Server (NTRS)

A method of semiconductor diode fabrication is disclosed which relies on the epitaxial growth of a precisely doped thickness layer of gallium arsenide or germanium on a semi-insulating or intrinsic substrate, respectively, of gallium arsenide or germanium by either molecular beam epitaxy (MBE) or by metal-organic chemical vapor deposition (MOCVD). The method involves: depositing a layer of doped or undoped silicon dioxide on a germanium or gallium arsenide wafer or substrate, selectively removing the silicon dioxide layer to define one or more surface regions for a device to be fabricated thereon, growing a matched epitaxial layer of doped germanium or gallium arsenide of an appropriate thickness using MBE or MOCVD techniques on both the silicon dioxide layer and the defined one or more regions; and etching the silicon dioxide and the epitaxial material on top of the silicon dioxide to leave a matched epitaxial layer of germanium or gallium arsenide on the germanium or gallium arsenide substrate, respectively, and upon which a field effect device can thereafter be formed.

Jhabvala, Murzban (inventor)

1990-01-01

378

Fluid-aided incorporation of Y into almandine-pyrope garnet via coupled dissolution-reprecipitation  

NASA Astrophysics Data System (ADS)

In nature almandine-pyrope garnet is a well-known host for a variety of trace elements including (Y+HREE), Sr, HFSE, as well as LREE such as Sm and Nd; all of which have important roles with regard to various geological processes (Kohn, 2009, GCA, 73, 170). For example, Y exchange between xenotime and garnet has been empirically calibrated as a geothermometer (Pyle and Spear, 2000, CMP, 138, 51). Sm/Nd and Lu/Hf dating, using garnet, is a well-known geochronometer (Thöni et al., 2008, Chem Geol, 254, 216). In general, REE + HFSE + Sr have been used to chart garnet growth and subsequently the evolution of the host rock (Konrad-Schmolke et al., 2008, EPSL, 272, 488). Incorporation of Y into garnet is probably the most widely studied trace element. These studies range from stress-induced redistribution of Y in garnet (Røhr et al, 2007, Am Mineral, 92, 1276) to Y zoning during garnet growth (Zeh, 2005, J Petrol, 47, 2335). While the incorporation of Y into garnet has generally been thought to occur either via diffusion or during garnet growth, more recent workers have suggested that incorporation of Y could also be fluid-aided. Fluid-aided incorporation of Y into garnet has been tested in the piston-cylinder apparatus (CaF2 assemblies, cylindrical graphite ovens) at 1000 MPa and 900 °C (8 days duration). Here, 10 mg of 50-200 µm size, inclusion-free, gem quality, fragments of the Gore Mountain garnet (Alm40-49, Py37-43, Gr13-16, Sp1) plus 5 mg 2N NaOH and 2 mg Y2O3 were loaded into a 3 mm diameter, 1 cm long, Au capsule that was then arc-welded shut and placed vertically in the CaF2 assembly such that the NiCr thermocouple tip came halfway up along the Au capsule length. Examination of the garnet fragments after the experiment indicates both high Y mobility and the partial alteration of the garnet in the form of a remobilized Y3Al5O12 component enriching those areas of the garnet along the grain rim. The enriched areas take the form of a series of intergrowths with sharp compositional boundaries, which appear to be defined by specific lattice planes as determined by the crystallographic axes of the garnet. These textures are the result of coupled dissolution-reprecipitation (Putnis, 2002, Min Mag, 66, 689), which essentially has resulted in the pseudomorphic partial replacement of a portion of the original garnet by a re-precipitated garnet now enriched in Y. The result from this study suggest that Y may be incorporated into garnet by the aid of fluids, which are both reactive with garnet and in which Y is mobile. In general, this result has strong implications with respect to incorporation of REE (and more specifically HREE) into garnet. It provides a mechanism by which garnet and other Y-bearing minerals, such as xenotime, may equilibrate hence enhancing their use as geothermometers. It also indicates that with respect to both Sm/Nd and Lu/Hf dating, the garnet geochronometer can be reset. More importantly, it implies that diffusion after or inclusion during garnet growth is not the only way by which trace elements may be incorporated into garnet.

Harlov, D. E.

2009-12-01

379

Merits of gallium nitride based power conversion  

NASA Astrophysics Data System (ADS)

Gallium nitride (GaN) based power electronics devices are actively being evaluated to determine if their theoretical advantages over silicon (Si) based switches can translate into improved performance of existing hardware as well as open the doors to new types of applications, such as high temperature implementations, or very high frequency power conversion. The following paper presents an overview of this activity. A brief summary about power electronics and the requirements of semiconductor devices used in this field is provided. Detailed analysis of the advantages and the challenges of using GaN devices is included along with a survey of demonstrations. This work also presents the test results from the evaluation of GaN devices from Efficient Power Conversion (EPC) and Transphorm. Included is a demonstration of EPC’s devices in a high frequency, high efficiency, switched-capacitor voltage doubler. This circuit achieves an output of 480 W at a switching frequency of 893 kHz.

Scott, Mark J.; Fu, Lixing; Zhang, Xuan; Li, Jinzhu; Yao, Chengcheng; Sievers, Markus; Wang, Jin

2013-07-01

380

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

381

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

382

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

383

Gallium-68 lipophilic complexes for labeling platelets  

SciTech Connect

Generator produced 68Ga-labeled platelets could be useful for positron emission tomographic (PET) studies of thrombosis or atherosclerosis. To label platelets with 68Ga, we have studied the effects of trace metals in elutions of 68Ga from 68Ge. Studies were conducted on the formation of lipophilic 68Ga complexes 8-hydroxyquinoline, tropolone, and mercaptopyridine-N-oxide (MPO). Parameters such as pH, buffers, concentration of ligand, and stability with time were investigated. High performance liquid chromatography and instant thin layer chromatography were used to quantitate formation of the 68Ga complex. Platelets from human, dog, and rabbit plasma were incubated with the 68Ga complexes and the percent labeling determined. Accumulation of platelets in the catheter scraped aorta of the rabbit was determined by PET imaging, tissue counting, and autoradiography. Gallium-68 MPO gave 40-60% labeling of rabbit platelets with higher accumulation in the scraped aorta compared to the normal.

Yano, Y.; Budinger, T.F.; Ebbe, S.N.; Mathis, C.A.; Singh, M.; Brennan, K.M.; Moyer, B.R.

1985-12-01

384

Direct Band Gap Wurtzite Gallium Phosphide Nanowires  

PubMed Central

The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

2013-01-01

385

Gallium Arsenide solar cell radiation damage experiment  

NASA Technical Reports Server (NTRS)

Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

1991-01-01

386

Cavity optomechanics in gallium phosphide microdisks  

SciTech Connect

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8?×?10{sup 5} and mode volumes <10(?/n){sup 3}, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0?×?10{sup 4} intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5??m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2??30?kHz for the fundamental mechanical radial breathing mode at 488?MHz.

Mitchell, Matthew; Barclay, Paul E., E-mail: pbarclay@ucalgary.ca [Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada); Hryciw, Aaron C. [National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada)

2014-04-07

387

Cavity optomechanics in gallium phosphide microdisks  

E-print Network

Gallium phosphide microdisk optical microcavities with intrinsic quality factors > 280,000 and mode volumes < (10 lambda/n)^3 are demonstrated, and their nonlinear and optomechanical properties are studied. For optical intensities up to 350,000 intracavity photons, optical loss within the microcavity is observed to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two photon absorption is not significant. Optomechanical coupling between several mechanical resonances and the optical modes of the microdisk is observed, and an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g_0~80 kHz is measured for the 488 MHz mechanical fundamental radial breathing mode.

Mitchell, Matthew; Barclay, Paul E

2013-01-01

388

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

389

Cavity optomechanics in gallium phosphide microdisks  

E-print Network

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors $ > 2.8\\times10^{5}$ and mode volumes $< 10 (\\lambda/n)^3$, and study their nonlinear and optomechanical properties. For optical intensities up to $8.0\\times10^4$ intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 $\\mu$m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate $g_0/2\\pi \\sim 30$ kHz for the fundamental mechanical radial breathing mode at 488 MHz.

Matthew Mitchell; Aaron C. Hryciw; Paul E. Barclay

2014-05-29

390

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

391

Detached growth of gallium doped germanium  

NASA Astrophysics Data System (ADS)

Detached Bridgman growth of gallium-doped germanium itself as well as the transition from detached to attached growth was observed in-situ for the first time, using a quartz-glass ampoule in a mirror furnace. Crystal diameter was 9 mm, the growth length 41 mm, and the growth velocity 0.5 mm/min. Undoped 1 1 1-oriented germanium served as seed material; the melt was doped with gallium ( C0=8.2×10 18 at/cm 3). Detachment took place after a growth length of 7 mm and continued for 27 mm; the remaining 7 mm grew with wall contact again. The wall-free growth could be observed around the entire circumference except for some small bridges (width: a few tens of micrometers, length: some hundreds of micrometers), where the crystal grew in contact with the wall. In the detached-grown part of the crystal, the 1 1 1-related growth lines are clearly visible. The transition from attached to detached growth and vice versa did not take place along a straight line but transitioned as islands over a length of about 1 mm. The gap between the growing crystal and the container wall varied between 10 and 80 ?m, as measured by a profilometer. The etch pit density is greatly reduced in the part of the crystal that grew free of the wall. An increase in the EPD is seen in the area where the crystal had contact with the ampoule wall by the bridges described above.

Dold, P.; Szofran, F. R.; Benz, K. W.

2002-01-01

392

Radiation induced synthesis of powder yttrium aluminium garnet  

NASA Astrophysics Data System (ADS)

Yttrium-aluminium garnet powders were prepared from aqueous solutions containing yttrium nitrate and aluminium chloride or nitrate via irradiation with accelerated electrons or UV light and via consequent calcination of formed solid phase. UV light seems to be more convenient for yttrium-aluminium garnet preparation; both types of irradiation yield crystalline Y 3Al 5O 12 phase after 1 h calcination at 1000 °C in air, but some amounts of yttrium oxide and aluminium oxide were also detected in calcinated solid phase formed under accelerated electrons irradiation. Preliminary radioluminescence and thermoluminescence measurements were performed to further evaluate prepared materials. Intensive radioluminescence typical for Ce 3+ doped structure was observed; thermoluminescence glow curves show distinctive peaks at 135-140 and 240-250 °C.

?uba, Václav; Indrei, Jakub; Mú?ka, Viliam; Nikl, Martin; Beitlerová, Alena; Pospíšil, Milan; Jakubec, Ivo

2011-09-01

393

Studies of MRI relaxivities of gadolinium-labeled dendrons  

NASA Astrophysics Data System (ADS)

In cancer detection, imaging techniques have a great importance in early diagnosis. The more sensitive the imaging technique and the earlier the tumor can be detected. Contrast agents have the capability to increase the sensitivity in imaging techniques such as magnetic resonance imaging (MRI). Until now, gadolinium-based contrast agents are mainly used for MRI, and show good enhancement. But improvement is needed for detection of smaller tumors at the earliest stage possible. The dendrons complexed with Gd(DOTA) were synthesized and evaluated as a new MRI contrast agent. The longitudinal and transverse relaxation effects were tested and compared with commercial drug Magnevist, Gd(DTPA).

Pan, Hongmu; Daniel, Marie-Christine

2011-05-01

394

Ascorbate and endocytosed Motexafin gadolinium induce lysosomal rupture.  

PubMed

Motexafin gadolinium (MGd) sensitizes malignant cells to ionizing radiation, although the underlying mechanisms for uptake and sensitization are both unclear. Here we show that MGd is endocytosed by the clathrin-dependent pathway with ensuing lysosomal membrane permeabilization, most likely via formation of reactive oxygen species involving redox-active metabolites, such as ascorbate. We propose that subsequent apoptosis is a synergistic effect of irradiation and high MGd concentrations in malignant cells due to their pronounced endocytic activity. The results provide novel insights into the mode of action of this promising anti-cancer drug, which is currently under clinical trials. PMID:21492999

Berndt, Carsten; Kurz, Tino; Bannenberg, Sarah; Jacob, Ralf; Holmgren, Arne; Brunk, Ulf T

2011-08-28

395

Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles  

SciTech Connect

Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

Mukherjee, A., E-mail: soumen.basu@phy.nitdgp.ac.in; Banerjee, M., E-mail: soumen.basu@phy.nitdgp.ac.in; Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur-713209 (India); Pal, M. [CSIR-Central Mechanical Engineering Research Institute, Durgapur-713209 (India)

2014-04-24

396

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

397

Garnet-biotite geothermometry revised: New Margules parameters and a natural specimen data set from Maine  

Microsoft Academic Search

The garnet-biotite geothermometer has been recalibrated using recently obtained Mar- gules parameters for iron-magnesium-calcium garnet, Mn interactions in garnet, and Al interactions in biotite, as well as the Fe oxidation state of both minerals. Fe-Mg and DWAl Margules parameters for biotite have been retrieved by combining experimental results on (6) Al-free and (6) Al-bearing biotite using statistical methods. Margules parameters,

M. J. HOLDAWAY; BISWAJIT MUKHOPADHYAY; M. D. DYAR; C. V. GUIDOTTI; B. L. DUTROW

1997-01-01

398

A detailed isotopic and petrological study of a single garnet from the Gassetts Schist, Vermont  

Microsoft Academic Search

Garnets, up to 1.2 cm across, from a metapelite in the Acadian metamorphic terrain of eastern Vermont have been analysed for major elements and segregated into different fractions for isotopic analysis. The garnets preserve abundant inclusions of minerals present during garnet growth which allow a nearly complete reaction history to be established. The Sm-Nd and U-Pb isotopic analyses yield concordant

Derek Vance; Tim Holland

1993-01-01

399

Zoned minerals in garnet peridotite nodules from the Colorado Plateau: implications for mantle metasomatism and kinetics  

Microsoft Academic Search

Some garnet peridotite nodules from The Thumb, a minette neck on the Colorado Plateau in the southwestern United States, contain\\u000a zoned minerals. Zoning does not exceed 1.5 wt.% for any oxide, but some relative changes are large: in one garnet TiO2 and Cr2O3 ranges are 0.05–0.65 and 3.5–5.0 wt.%, respectively. In two porphyroclastic nodules, garnet rims are depleted in Mg

Douglas Smith; Stephen N. Ehrenberg

1984-01-01

400

Martian mantle primary melts - An experimental study of iron-rich garnet lherzolite minimum melt composition  

NASA Technical Reports Server (NTRS)

The minimum melt composition in equilibrium with an iron-rich garnet lherzolite assemblage is ascertained from a study of the liquidus relations of iron-rich basaltic compositions at 23 kb. The experimentally determined primary melt composition and its calculated sodium content reveal that Martian garnet lherzolite minimum melts are picritic alkali olivine basalts. Martian primary melts are found to be more picritic than terrestrial garnet lherzolite primary melts.

Bertka, Constance M.; Holloway, John R.

1988-01-01

401

Optical isolator based on mode conversion in magnetic garnet films.  

PubMed

Calculations are presented describing a novel optical isolator which works by complete TE(0)-TM(0) mode conversion in magnetic garnet films caused by stress-induced optical anisotropy (50%) and by Faraday rotation (50%). These conversions take place along two different, perpendicular light paths in the same crystal that are connected by an integrated mirror. Possible tolerances of the film parameters are given so that a 30-dB isolation is still guaranteed. PMID:20490145

Hemme, H; Dötsch, H; Menzler, H P

1987-09-15

402

Coherency matrix polarization measurements: application to magnetooptic garnet films.  

PubMed

A method of completely determining the polarization of light is described. An algorithm that allows a fast numerical evaluation of the coherency matrix based on the results of four nonequivalent polarization measurements is presented. The method has been applied to determine the degree of polarization, ellipticity, and orientation of the major axis of light transmitted through a magnetooptic thin film on a garnet substrate as a function of magnetic field. Representative results are given. PMID:20700350

Engstrom, H

1991-05-01

403

Measurement of magnetostriction coefficients of epitaxial garnet films.  

PubMed

A technique for measuring the magnetostriction coefficients of epitaxial garnet films on 50-mm-diam wafers is described. The measurement is based on the shift of the microwave ferrimagnetic resonance produced by stressing the film, which is achieved by supporting the wafer around its circumference and reducing the atmospheric pressure on one side. A simple, nonresonant transmission microwave spectrometer which is well suited for measurements on large wafers is also described. PMID:18699683

Vella-Coleiro, G P

1979-09-01

404

Intercalibration of FTIR and SIMS for Hydrogen Measurements in Garnets  

NASA Astrophysics Data System (ADS)

The importance of understanding the hydrogen incorporated in nominally anhydrous minerals (NAMs) that influences their physical and chemical properties significantly is well accepted, however, quantitatively experimental constraints between hydrogen concentration and physical and chemical properties are only meaningful if hydrogen concentration can be accurately determined. Fourier Transform Infrared Spectroscopy (FTIR) may be the most powerful technique since it provides information about both bulk concentration and local bonding environments, while Secondary Ion Mass Spec-trometry (SIMS) has held promise as an ideal method for hydrogen analyses for its advantages of high spatial resolution and insensitivity to crystal orientation. Great efforts have been made to establish experimental standards for these two techniques since they have no rigorous self-calibration. We here present new Fourier Transform Infrared Spectroscopy (FTIR) and Secondary Ion Mass Spectrometry (SIMS) analyses of 1H in 11 natural garnets (grossular, spessartite and pyrope). This set of garnets extends to a wider range of H2O contents (~4 to 6790 wt. ppm H2O) than previous studies and can be more reliable if more garnets can be investigated. We routinely achieve a less than 5 ppm by weight H2O with high vacuum quality, the use of a Cs+ primary beam, and carefully prepared samples using a resin-free mounting technique (described in Aubaud C. et al., 2007. Intercalibration of FTIR and SIMS for hydrogen measurements in glasses and nominally anhydrous minerals. American Mineralogist, 92, 811-828). Although some scatter is observed, the straight line with a slope of 0.0722 defined by all garnets in a plot of (H)FTIR vs. (H+/Si+)SIMS* (SiO2)EMP suggests small matrix effects, while some previous efforts demonstrated the existence of such matrix effects. Discrepancies between FTIR and SIMS measurements can be partially distributed to the impurities, which have different hydrogen concentration as the host crystals, because much larger volume is sampled by FTIR than SIMS.

Huang, Y.; Rossman, G.; Guan, Y.; Ma, C.

2008-12-01

405

Molecular field coefficients of terbium, dysprosium and holmium iron garnets  

Microsoft Academic Search

Molecular field coefficients related to the rare earth iron interactions are determined in rare earth iron garnets TbIG, DyIG, HoIG. An analysis of the temperature dependences of the single crystals magnetization and of the susceptibilities shows that these parameters are temperature dependent in 70-300K range. Discontinuities of nacand ndcoccuring at the compensation temperature are found. Nevertheless, the molecular field acting

M. Guillot; P. Feldmann; H. Le Gall; M. Fadly

1978-01-01

406

Calcium-poor garnet in relation to metamorphism  

Microsoft Academic Search

1. (1) The writer has carried out a systematic study of pyralspites (calcium-poor garnets) in pelitic metamorphic rocks of the Gosaisyo-Takanuki district. With the increase in metamorphic grade of their host-rocks, the MnO content of the pyralspites decreases, while the FeO content increases. Accompanying the variations in composition, the edge length of the unit cell of the minerals shortens and

Akiho Miyashiro

1953-01-01

407

Charnockite geobarometers based on coexisting garnet-pyroxene-plagioclase-quartz  

Microsoft Academic Search

Numerous geothermometers based on compositions of coexisting minerals have been calibrated experimentally or theoretically during the past 10 yr. In contrast, few continuous-reaction geobarometers exist which have had wide application. One, based on the reaction of cordierite to garnet, sillimanite and quartz, is limited by a relatively narrow pressure range of application and also by conflicting calibrations1,2 because the mixing

D. Perkins; R. C. Newton

1981-01-01

408

Nonlinear dynamic magnetization regimes in (100) ferrite-garnet films  

SciTech Connect

To study the nonlinear dynamics of a uniformly precessing magnetization in perpendicularly magnetized (100) ferrite-garnet films, equations of motion are numerically solved over a wide ac field frequency range. Bifurcation changes in the magnetization precession and the states of dynamic bistability have been detected. The conditions of high-amplitude regular and stochastic dynamic regimes are revealed, and the possibilities of controlling these precession regimes by applied magnetic fields are shown.

Shutyi, A. M., E-mail: shuty@mail.ru; Sementsov, D. I. [Ul'yanovsk State University (Russian Federation)], E-mail: sementsovdi@ulsu.ru

2007-05-15

409

The solubility of alumina in orthopyroxene coexisting with garnet  

Microsoft Academic Search

The solubility of alumina in complex orthopyroxenes crystallised in equilibrium with garnet has been determined over the pressure-temperature range 8–30 Kb and 800–1250° C. The results are in good agreement with predictions made using the simple thermodynamic model of Wood and Banno (1973). The model has been refined using a combination of the new data on orthopyroxenes of about En60Fs40

Bernard J. Wood

1974-01-01

410

Ferrite phase shifters using stress-insensitive garnet materials  

NASA Astrophysics Data System (ADS)

Stable hysteresis characteristics of ferrimagnetic materials are critical to the RF performance of microwave ferrite toroidal phasers. Particularly troublesome are the magnetostrictive characteristics where the hysteresis properties are altered by stress. This paper presents the results of a study addressing Mn(sup + 3) substitutions in garnets to improve the resultant magnetostrictive characteristics in order to achieve stress-insensitive performance in waveguide toroidal phasers.

Vaughn, J. Todd; Cox, Paul R.; Rodrigue, G. P.; Harrison, Gordon R.

1995-05-01

411

Magnetoelastic interaction in an epitaxial yttrium iron garnet film  

NASA Astrophysics Data System (ADS)

Experiments are reported in which hypersound was generated by a magnetostrictive transducer based on an epitaxial single-crystal yttrium iron garnet film. The thickness of the film was equal to half the wavelength of the generated acoustic wave. The principal characteristics of the transducer, measured by the echo method, are presented. A widening of the ferromagnetic resonance line due to a coupling between magnetostatic and elastic modes was observed.

Tychinskii, A. V.

1985-08-01

412

Photomagnetism in Ca2+Fe4+-doped yttrium iron garnet  

Microsoft Academic Search

The temperature and time dependence of the initial susceptibility of the optical magnetization curve has been measured on epitaxial films of nominally pure yttrium iron garnet (YIG) and Ca: YIG, during illumination with white light after cooling in the dark. Depending on sample composition, the maximum temperature for the occurrence of the light-induced effects on the susceptibility is 100 K

M. Pardavi-Horva´th; P. E. Wigen; G. Ve´rtesy

1988-01-01

413

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

414

Lattice and Magnetic Effects on Multiferroic Transitions in Garnets  

NASA Astrophysics Data System (ADS)

The possible presence of ferroelectricity in a magnetically ordered state has attracted considerable attention particularly in ABO3 and AB2O5 systems with B = Mn. Evidence for strong coupling of the two order parameters has been provided in the so-called multiferroics, where the field-induced polarization leads to a giant magnetoelectric effect and a magneto-dielectric effect. It was recently shown that the ferrimagnetic garnet crystal of Tb3Fe5O12 exhibits a large magnetodielectric response as well when a very small magnetic field is applied (1). To understand the origin of the high sensitivity of the dielectric effect in garnets, we investigated the crystal and magnetic structures of Tb3(Fe/Ga)5O12 using pulsed neutron diffraction. The garnet crystal appears to be very close to a lattice instability and high-resolution diffraction showed that the lattice gradually changes symmetry from cubic to rhombohedral with cooling over a wide temperature range. At the same time, magnetic diffuse scattering is observed that goes away by 15 K. The role of the lattice and of local distortions in the magnetic polarization and the coupling of the magnetostriction to the dielectric effect will be discussed. (1) N. Hur et al, Appl. Phys. Lett. 87, 042901 (2005).

Louca, Despina; Kamazawa, K.; Proffen, T.

2007-03-01

415

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

416

High performance magneto-optic garnet materials for integrated optics and photonics.  

E-print Network

??This work explores the preparation, characteristics and properties of highly bismuth (Bi) substituted, metal doped, iron garnet compounds and investigates their potential for various emerging… (more)

Alam, Mohammad

2012-01-01

417

Solution properties of almandine-pyrope garnet as determined by phase equilibrium experiments  

USGS Publications Warehouse

The thermodynamic mixing properties of almandine-pyrope garnet were derived from phase equilibrium experiments at temperatures of 900 and 1000??C and pressures from 8 to 14 kbar. Almandine has essentially ideal behavior in almandine-pyrope garnet over the composition range Alm89-Alm61 at the above experimental conditions. In all experimental products a systematic partitioning of Fe and Mg between garnet and ilmenite was seen with ln Kd ??? 1.59 which was not temperature sensitive. The results support the use of garnet mixing models that incorporate ideal or nearly ideal Fe-Mg parameters. -from Authors

Koziol, A.M.; Bohlen, S.R.

1992-01-01

418

Magnetic Behavior of Cobalt in Garnets. II. Magnetocrystalline Anisotropy and Ferrimagnetic Resonance of Cobalt-Doped Yttrium Iron Garnet  

Microsoft Academic Search

Measurements on single crystals of yttrium iron garnet (YIG) doped with cobalt, some counterdoped with silicon or calcium, show that the magnetocrystalline anisotropy is dominated by octahedral Co2+ and tetrahedral Co3+. Both are present in uncompensated material. We calculate the single-ion anisotropy of ions of the (3d)n series (n=4-9), incorporated into the various sites of YIG. We find qualitative agreement

M. D. Sturge; E. M. Gyorgy; R. C. Lecraw; J. P. Remeika

1969-01-01

419

An Asynchronous Microprocessor in Gallium Jos'e A. Tierno Alain J. Martin Drazen Borkovic  

E-print Network

An Asynchronous Microprocessor in Gallium Arsenide Jos'e A. Tierno Alain J. Martin Drazen Borkovic November 9, 1993 Abstract In this paper, several techniques for designing asynchronous circuits in Gallium

Martin, Alain

420

Some interesting features of the Tb3+ magnetooptics in the paramagnetic garnets  

NASA Astrophysics Data System (ADS)

The spectra of the absorption, luminescence, magnetic circular dichroism (MCD) and magnetic circular polarization of luminescence (MCPL) in the terbium-yttrium gallium garnet Tb3+:Y3Ga5O12 (Tb:YGG) have been studied within the visible and near ultraviolet (UV) spectral range for temperatures T = 85 and 300 K. The MCD spectrum observed within the UV absorption band for Tb:YGG is associated with spin- and parity-allowed electric-dipole 4f ? 5d transitions occurring between levels of the ground 7F6 multiplet and the 7D state of the excited 4f(7)5d configuration of the Tb3+ ion. Analysis of the spectral and the temperature dependences of the magnetooptical and optical spectra has made it possible to identify magneto-optically-active 4f ? 4f transitions occurring between Stark sublevels of the 5D4 and 7F5 multiplets in Tb3+:YGG. Quantum mechanical "mixing" of the three lowest energy Stark singlets in the excited 5D4 multiplet by an external magnetic field H leads to the change of the circularly polarized luminescence line intensities. The Zeeman effect in the UV absorption band 7F6 ? 5L10 of Tb3+:YGG at T = 85 K was also studied. The magnetic field dependence of the Zeeman splitting of some absorption lines is found to exhibit unusual behavior: as the magnetic field increases, the band splitting decreases rather than increases. A parameterized Hamiltonian defined to operate within the entire 4f(8) ground electronic configuration of Tb3+ was used to model the experimental Stark levels, their irreducible representations (irreps.) and wave functions. The crystal-field parameters were determined using a Monte-Carlo method in which nine independent crystal-field parameters, were given random initial values and optimized using standard least-squares fitting between calculated and experimental levels. The final fitting standard deviation between 101 calculated and experimental Stark levels is 16.7 cm-1.

Valiev, Uygun V.; Gruber, John B.; Burdick, Gary W.; Mukhammadiev, Anvar K.; Fu, Dejun; Pelenovich, Vasiliy O.

2014-05-01

421

Lithium-gadolinium-borate as a neutron dosemeter.  

PubMed

Lithium-gadolinium-borate (LGB) dispersed as microcrystals within the plastic scintillator BC-490 is a promising material for accurate neutron dosimetry in mixed n/gamma fields. Spectral information > 1 MeV is obtained by capture gating proton recoil events in the plastic scintillator to subsequent capture in (6)Li. Below 1 MeV, isolated capture events in either gadolinium or (6)Li give energy information in this region. Discrimination based on capture gating is used to reject false coincidences due to gamma rays or incorrectly gated neutron events. A detailed Monte Carlo model has been created in MCNPX that predicts the energy response of the LGB spectrometer in the capture-gated mode of operation. X-ray microtomography has been performed on the detector in order to obtain the LGB microcrystal distribution within the plastic scintillator, and this is incorporated into the model. The way in which the calculated response functions can be included in an unfolding procedure is outlined. PMID:17578875

Lewis, D V; Spyrou, N M; Williams, A M; Beeley, P A

2007-01-01

422

An Electron Microprobe Study of Synthetic Aluminosilicate Garnets  

NASA Astrophysics Data System (ADS)

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

Fournelle, J.; Geiger, C. A.

2010-12-01

423

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

424

Electronic behavior of calcined material obtained from a gallium-N-phenylene-N hybrid copolymer  

SciTech Connect

Calcination of a gallium-N-phenylene-N hybrid copolymer under an argon atmosphere gave nano-sized gallium nitride-carbon cluster composite material. ESR spectral examinations of the calcined materials reveals the possibility of an electron transfer in the process of gallium nitride {yields} carbon clusters with an oxidation site at gallium nitride particles and a reduction site at carbon clusters. The calcined material was found to reduce methylene blue under visible light irradiation.

Matsui, H. [Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Yamamoto, S. [Taki Chemical Co. Ltd., 64-1, Nishiwaki, Befu-cho, Kakogawa, Hyogo 675-0125 (Japan); Hama, T. [Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Karuppuchamy, S. [Molecular Engineering Institute, Kinki University, 11-6, Kayanomori, Iizuka, Fukuoka 820-8555 (Japan)], E-mail: chamy@me-henkel.fuk.kindai.ac.jp; Yoshihara, M. [Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Molecular Engineering Institute, Kinki University, 11-6, Kayanomori, Iizuka, Fukuoka 820-8555 (Japan)

2008-01-08

425

Laser-Induced Forward Transfer-printing of pre-machined crystalline magneto-optic garnet discs  

E-print Network

Laser-Induced Forward Transfer-printing of pre-machined crystalline magneto-optic garnet discs-optic Yttrium Iron Garnet films. Debris-free circular micro-discs with smooth edges and surface uniformity have

Sóbester, András

426

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

DOEpatents

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

Hogan, Stephen J. (Golden, CO)

1986-01-01

427

Journal of Crystal Growth 286 (2006) 197204 Low-temperature atomic assembly of stoichiometric gallium arsenide  

E-print Network

gallium arsenide from equiatomic vapor D.A. MurdickÃ?, X.W. Zhou, H.N.G. Wadley Department of Materials amorphous structure. The atomic assembly mechanisms of arsenic dimer incorporation, as well as gallium. Atomic processes responsible for the formation of the gallium vacancy defects were observed

Wadley, Haydn

428

SHOCK HUGONIOT AND MELT CURVE FOR A MODIFIED EMBEDDED ATOM METHOD MODEL OF GALLIUM  

E-print Network

SHOCK HUGONIOT AND MELT CURVE FOR A MODIFIED EMBEDDED ATOM METHOD MODEL OF GALLIUM F. J. Cherne. Molecular dynamics (MD) simulations have been performed on the complex material gallium us- ing a literature be obtained through a slight modification of the MEAM parameters. INTRODUCTION Gallium is a complex element

Duisburg-Essen, Universität

429

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy  

E-print Network

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy D. C. Law March 2000 The surface roughness of gallium arsenide 001 films produced by metalorganic vapor for gallium surface diffusion has been estimated: Ed 1.35 0.1 eV. © 2000 American Institute of Physics. S0021

Li, Lian

430

COUCHES PITAXIALES D'ARSNIURE DE GALLIUM OBTENUES PAR LA TECHNIQUE DE TRANSPORT EN PHASE VAPEUR  

E-print Network

161. COUCHES �PITAXIALES D'ARS�NIURE DE GALLIUM OBTENUES PAR LA TECHNIQUE DE TRANSPORT EN PHASE gallium sur des supports de germanium réalisée par la technique de transport en phase vapeur. Cette étude mobilité. Abstract. 2014 We have studied the epitaxy of gallium arsenide deposited by the vapor phase

Paris-Sud XI, Université de

431

Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires  

E-print Network

Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires Zheng. In this article, we show that the large size (5-50 µm in diameter), low melting point gallium droplets can be used. Unlike any previously observed results using gold or iron as catalyst, the gallium-catalyzed VLS growth

Wang, Zhong L.

432

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

E-print Network

#12;Unusual strategies for using indium gallium nitride grown on silicon (111) for solid with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements and scal- able means to integrate these devices in modules for white light generation. gallium nitride

Rogers, John A.

433

Terahertz Kerr effect in gallium phosphide crystal M. Cornet,1,2  

E-print Network

Terahertz Kerr effect in gallium phosphide crystal M. Cornet,1,2 J. Degert,1,2, * E. Abraham,1 of the Kerr effect induced by an intense terahertz pulse in a h100i gallium phosphide crystal. The temporal in lithium niobate [5] and bulk n-GaAs [6]. Hereafter we report on the observation of TKE in a gallium

434

Spectral Data for Gallium: Ga I through Ga XXXI T. Shiraia...  

E-print Network

Spectral Data for Gallium: Ga I through Ga XXXI T. Shiraia... Naka Fusion Research Establishment April 2006; published online 23 May 2007 The energy levels and spectral lines of gallium atom in all spectral lines; emission spectra; Ga; gallium ions; ground states; ionization potentials; multiply charged

Magee, Joseph W.

435

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

E-print Network

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements and scal- able means to integrate these devices in modules for white light generation. gallium nitride

Choquette, Kent

436

Gallium phosphide photonic crystal nanocavities in the visible Kelley Rivoire,a  

E-print Network

Gallium phosphide photonic crystal nanocavities in the visible Kelley Rivoire,a Andrei Faraon at visible wavelengths are fabricated in a high refractive index n 3.2 gallium phosphide membrane fabrication proce- dures for semiconductors such as silicon and gallium ars- enide, which have band gaps

Faraon, Andrei

437

Oxide-assisted growth and optical characterization of gallium-arsenide nanowires  

E-print Network

Oxide-assisted growth and optical characterization of gallium-arsenide nanowires W. S. Shi, Y. FAs nanowires. © 2001 American Institute of Physics. DOI: 10.1063/1.1371966 Gallium arsenide GaAs , as a direct mol % gallium oxide Ga2O3 at room temperature. The target and a polished silicon 100 substrate were

Zheng, Yufeng

438

Title of Document: GALLIUM NITRIDE NANOWIRE BASED ELECTRONIC AND OPTICAL DEVICES.  

E-print Network

ABSTRACT Title of Document: GALLIUM NITRIDE NANOWIRE BASED ELECTRONIC AND OPTICAL DEVICES. Abhishek and Computer Engineering Gallium nitride nanowires have significant potential for developing nanoscale emitters nm electroluminescence with a full width half maximum of 25 nm at 300 K. #12;GALLIUM NITRIDE NANOWIRE

Anlage, Steven

439

Gallium and Indium Complexes for Ring-Opening Polymerization of Cyclic Ethers, Esters and Carbonates  

E-print Network

1 Gallium and Indium Complexes for Ring-Opening Polymerization of Cyclic Ethers, Esters-francois.carpentier@univ-rennes1.fr Contents 1. Introduction 2. Gallium-based initiators/catalysts for the ROP of cyclic ethers, esters and carbonates: synthesis, characterization and catalytic performance 2.1. Gallium complexes

Paris-Sud XI, Université de

440

PHNOMNES DE RELAXATION DANS LES STRUCTURES PLANES PITAXIALES A L'ARSNIURE DE GALLIUM  

E-print Network

1679 PH�NOM�NES DE RELAXATION DANS LES STRUCTURES PLANES �PITAXIALES A L'ARS�NIURE DE GALLIUM P fréquences dans les structures planes épitaxiales, avec ou sans grille, en arséniure de gallium sur substrat place on both gated and ungated gallium arsenide planar epitaxial structure are discussed. The voltage

Paris-Sud XI, Université de

441

Cross-Section High Resolution Transmission Electron Microscopy Investigation of Internal Structures of Gallium Nitride Nanowires  

E-print Network

of Gallium Nitride Nanowires Benjamin W. Jacobs1 , Kaylee McElroy2 , Raed Al-Duhaileb3 , Martin A Crimp4 Michigan State University, East Lansing, Michigan, USA e-mail: ayresv@msu.edu Abstract-Gallium nitride blocks with properties enhanced by their small size and large aspect ratios. Gallium nitride (Ga

Ayres, Virginia

442

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells  

E-print Network

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with a larger number of vacancies, that facilitates indium and gallium diffusion, in the sodium free films

Rockett, Angus

443

GALLIUM--2002 29.1 References that include a section mark () are found in the Internet  

E-print Network

GALLIUM--2002 29.1 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 two large high-grade zones of gallium mineralization with average grades in excess of 100 grams per

444

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 phénomènes transitoires de transport dans l'arseniure de gallium lorsque les champs varient dans le temps et

Paris-Sud XI, Université de

445

LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM  

E-print Network

703 LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM LINES, accepte Ie 19 fivrier 1987) Résumé : Les élargissements Stark de raies du gallium et de l'indium neutre cathode liquide utilisant un mélange sodium-indium ou potassium-gallium, la densité electronique pouvant

Paris-Sud XI, Université de

446

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.

447

Theoretical study of sequential oxidation of clusters of gallium oxide: Ga3On (n: 48)  

E-print Network

Theoretical study of sequential oxidation of clusters of gallium oxide: Ga3On (n: 4­8) S. Gowtham of gallium oxide clusters from Ga3O4 to Ga3O8. These results, based on density functional theory calculations clusters of gallium oxide can be taken as a model to understand the physics and chemistry of nanostructures

Pandey, Ravi

448

Surface reconstructions of cubic gallium nitride ,,001... grown by radio frequency nitrogen plasma molecular beam epitaxy  

E-print Network

Surface reconstructions of cubic gallium nitride ,,001... grown by radio frequency nitrogen plasma molecular beam epitaxy under gallium-rich conditions Muhammad B. Haider, Rong Yang, Costel Constantin; published online 27 October 2006 Cubic GaN has been grown under gallium Ga -rich growth conditions using

449

Nanoporous gallium nitride square microtubes Yucheng Lan Hui Wang Feng Lin  

E-print Network

Nanoporous gallium nitride square microtubes Yucheng Lan · Hui Wang · Feng Lin · Yalin Lu · Yang Li / Published online: 23 July 2013 � Springer Science+Business Media New York 2013 Abstract Porous gallium nitride microtubes were self- fabricated from gallium nitride submicron irregular struc- tures

Bao, Jiming

450

Experimental and numerical study of anomalous thermocapillary convection in liquid gallium  

E-print Network

Experimental and numerical study of anomalous thermocapillary convection in liquid gallium Janis 1998; accepted 2 August 1999 Thermocapillary Marangoni convection of liquid gallium was studied of the liquid gallium for a very long time. The convective flow at the free surface was found to be directed

Gelfgat, Alexander

451

Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers in aqueous electrolytes  

E-print Network

Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers-assembled monolayers of octadecylthiol ODT were reconstituted on freshly etched gallium arsenide (n on electro-optical devices.1,2 Among various semiconductors, gallium arsenide GaAs is a promising material

Deutschmann, Rainer

452

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

453

Gallium solar neutrino experiments: Absorption cross sections, neutrino spectra, and predicted event rates  

E-print Network

Gallium solar neutrino experiments: Absorption cross sections, neutrino spectra, and predicted that a spline fit determines accurately the event rates in a gallium detector even if new physics changes number s : 26.65. t, 12.15.Ff, 14.60.Pq, 96.60.Jw I. INTRODUCTION Gallium solar neutrino experiments are

Bahcall, John

454

Physica B 338 (2003) 159164 Fabrication and properties of gallium metallic  

E-print Network

Physica B 338 (2003) 159­164 Fabrication and properties of gallium metallic photonic crystals V City, UT 84112, USA Abstract Gallium metallic photonic crystals with 100% filling factor have been fabricated via infiltration of liquid gallium into opals of 300-nm silica spheres using a novel high pressure

Kozhevnikov, Vladimir

455

THE RAMAN SPECTRUM OF GALLIUM PHOSPHIDE By R. S. KRISHNAN and N. KRISHNAMURTHY,  

E-print Network

630. THE RAMAN SPECTRUM OF GALLIUM PHOSPHIDE By R. S. KRISHNAN and N. KRISHNAMURTHY, Department ordre du phosphure de gallium, récemment enre- gistrés par Russell et Hobden en utilisant un laser He of gallium phosphide recorded recently by Russell and Hobden using a He-Ne laser source, are discussed

Boyer, Edmond

456

Catalyst-Free Gallium Nitride Nanowire Nucleation Faculty Advisor: Dr. Virginia M. Ayres  

E-print Network

Catalyst-Free Gallium Nitride Nanowire Nucleation Faculty Advisor: Dr. Virginia M. Ayres Friday catalyst particles are not desirable. This thesis deals exclusively with gallium nitride catalyst free Investigation of Gallium Nitride Nanowires," International Journal of Nanomanufacturing, in press 2009. B. W

Ayres, Virginia

457

Solid-state gallium-69 and gallium-71 nuclear magnetic resonance spectroscopic studies of gallium analogue zeolites and related systems  

SciTech Connect

The authors have obtained solid-state 11.7-T /sup 69/Ga and /sup 71/Ga nuclear magnetic resonance (NMR) spectra of a series of gallosilicates (gallium analogues of zeolites Na-X, Na-Y, Na-sodalite, and Na-natrolite). From the apparent /sup 69/Ga and /sup 71/Ga chemical shifts, values of the nuclear quadrupole coupling constants (e/sup 2/qQ/h) and the true, isotropic chemical shifts (delta/sub i) have been deduced for the framework, tetrahedral, Ga(OSi)/sub 4/ sites. The e/sup 2/qQ/h values are in the range 1.9-2.7 MHz for /sup 69/Ga and 1.2-1.7 MHz for /sup 71/Ga. The isotropic chemical shifts are all in the range 171-186 ppm downfield from an external standard of 1 M Ga(NO/sub 3/)/sub 3/. Their results indicate that measurement of the apparent (second-order shifted) chemical shifts for pairs of isotopes of nonintegral spin quadrupolar nuclei in solids at one magnetic field strength is a useful new approach for determination of both isotropic chemical shifts and nuclear quadrupole coupling constant values.

Timken, H.K.; Oldfield, E.

1987-12-09

458

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

459

Simulation assisted design of a gallium phosphide np photovoltaic junction Charles R. Allen, Jong-Hyeok Jeon , Jerry M. Woodall  

E-print Network

Simulation assisted design of a gallium phosphide n­p photovoltaic junction Charles R. Allen, Jong February 2010 Keywords: Gallium phosphide Solar cell Multi-junction CPV Simulation a b s t r a c t A gallium phosphide photovoltaic junction is reported. Using a n­p structure, a gallium phosphide junction

Woodall, Jerry M.

460

Journal of Crystal Growth 310 (2008) 579583 Red shift in the photoluminescence of indium gallium arsenide nitride  

E-print Network

Journal of Crystal Growth 310 (2008) 579­583 Red shift in the photoluminescence of indium gallium gallium arsenide nitride (InGaAsN) in 1.0 � 10�6 Torr of nitrogen trifluoride (NF3) has been studied-phase epitaxy; B1. Nitrogen trifluoride; B2. Indium gallium arsenide nitride 1. Introduction Indium gallium

Hicks, Robert F.

461

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

E-print Network

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium properties of liquid gallium and eutectic gallium-indium Phys. Fluids 24, 063101 (2012); 10); 10.1063/1.3670048 Evaluation of gallium-indium alloy as an acoustic couplant for high-impedance, high

Deseri, Luca

462

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

E-print Network

peridotites from Pohorje (Eastern Alps, Slovenia) Jan C.M. De Hoog 1,* Marian Janák 2 Mirijam Vrabec 3 Keiko H Garnet peridotites from the Slovenska Bistrica Ultramafic Complex (SBUC) in the Pohorje Mts., Eastern depleted mantle of oceanic affinity. The metamorphic assemblage of the garnet peridotites consists

463

Transformation of two-pyroxene hornblende granulite to garnet granulite involving simultaneous melting and fracturing of  

E-print Network

and planar garnet reaction zones in rectilinear patterns. In gabbroic gneiss, narrow dykes of anorthositic that recrystallization was mostly isochemical. The anorthositic veins cut contacts between gabbroic gneiss and dioritic gneiss, but change in morphology at the contacts, from the anorthositic vein surrounded by a garnet

Daczko, Nathan

464

Effects of water and iron content on the rheological contrast between garnet and olivine  

NASA Astrophysics Data System (ADS)

The effects of water and iron content on the relative creep strengths of garnet and olivine were investigated by shear deformation experiments. Garnet and olivine samples were sandwiched together between alumina pistons in a simple shear geometry and were deformed at P = 1-2 GPa, T = 1473 K and strain rates ranging from 10 -5 to 10 -3 s -1 using a Griggs-type solid-medium apparatus. The stress- and strain-rate relation, as well as the deformation microstructures including lattice-preferred orientation and dynamic recrystallization, indicates that the deformation by dislocation creep. The creep tests show that the Fe-rich garnet (Alm 67Prp 29Grs 3) was slightly weaker than olivine (Fo90), whereas the Mg-rich garnet (Alm 19Prp 68Grs 12) was significantly stronger than olivine under dry conditions. The wet experiments show that the creep rate of the Mg-rich garnet is more sensitive to water than olivine; the water fugacity exponent on strain rate was estimated to be ˜2.4 for garnet and ˜1.2 for olivine, and the Mg-rich garnet becomes weaker than olivine in a water-rich environment. The experimental results show that the rheological contrast between garnet and olivine depends strongly on water content and to a lesser degree on Fe content. Consequently, the geodynamic behavior of geochemical reservoirs can be sensitive to their chemical environments in the upper mantle.

Katayama, Ikuo; Karato, Shun-Ichiro

2008-01-01

465

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

466

Influence of powerful laser irradiation on electromagneto-optical dependences of yttrium iron garnets  

SciTech Connect

Electromagneto-optical properties of yttrium iron garnets have been investigated in a longitudinal geometry by using optical polarimetry method. It is revealed that irradiation of yttrium iron garnet films by powerful laser impulse leads to essential increase in the electromagneto-optical effect value, which can be due to the elimination of the local mechanical strain or nonuniform pressure in them.

Koronovskyy, V. E. [Department of Radiophysics, Taras Shevchenko Kiev National University, 2 Prospekt Glushkova Street, 03127 Kiev (Ukraine)

2009-09-15

467

Chrome-rich garnets from the kimberlites of yakutia and their parageneses  

Microsoft Academic Search

The chrome-rich magnesian garnets (6.6–18.9% Cr2O3) of kimberlitic concentrates and some peridotite xenoliths contain variable admixtures of CaO: from 0.69 to 26.0% (1.7–72% Ca-component). All the garnets both in respect of Ca and Cr-contents make up a continuous series.

N. V. Sobolev; Yu. G. Lavrent'ev; N. P. Pokhilenko; L. V. Usova

1973-01-01

468

REE and Trace-Element Diffusivities in Garnet Determined From Resorption-Induced Stranded Diffusion Profiles  

Microsoft Academic Search

Resorption of garnet at very high temperatures may produce stranded diffusion profiles for trace elements; these can be exploited by measurement and modeling to yield quantitative estimates of diffusion coefficients for species that often defy definitive experimental determination of diffusion rates. Knowledge of intracrystalline diffusion rates in garnet for major and trace components provides vital constraints on the rates and

W. D. Carlson

2003-01-01

469

Magnetic Force Microscopy Images of Magnetic Garnet With Thin-Film Magnetic Tip  

NASA Technical Reports Server (NTRS)

We present magnetic force microscopy images of YGdTmGa/YSmTmGa magnetic garnet, usinga thin Fe film deposited on Si_3N_5 tips. We have found correlations between the topography andthe magnetic domain structure. We have observed the domain wall contrast with a iron thin-film tip. We report on domain wall imaging of garnet with magnetic force microscopy.

Wadas, A.; Moreland, J.; Rice, P.; Katti, R.

1993-01-01

470

Stephan Klemme Hugh StC. O'Neill The near-solidus transition from garnet lherzolite to spinel lherzolite  

E-print Network

Stephan Klemme á Hugh StC. O'Neill The near-solidus transition from garnet lherzolite to spinel spinel lherzolite to garnet lherzolite in the system CaO-MgO-Al2O3-SiO2 (CMAS) has been determined in the upper mantle changes from plagioclase to spinel to garnet. The transition from spinel lherzolite

471

Growth and ferromagnetic resonance of yttrium iron garnet thin films on Yiyan Sun, Young-Yeal Song, and Mingzhong Wu  

E-print Network

Growth and ferromagnetic resonance of yttrium iron garnet thin films on metals Yiyan Sun, Young://apl.aip.org/about/rights_and_permissions #12;Growth and ferromagnetic resonance of yttrium iron garnet thin films on metals Yiyan Sun, Young-quality yttrium iron garnet (YIG) thin films were grown on a sandwich structure that consisted of a thick Cu layer

472

Trace element partitioning between majoritic garnet and silicate melt at 1017 GPa: Implications for deep mantle processes  

E-print Network

Trace element partitioning between majoritic garnet and silicate melt at 10­17 GPa: Implications June 2012 Keywords: Garnet Majorite Trace elements Komatiites Diamonds Mars Melting experiments were performed on a silica-rich peridotite composition at 10­17 GPa to determine majoritic garnet­melt partition

Minarik, William

473

PII S0016-7037(00)00336-7 Atomistic simulation of trace element incorporation into garnets--comparison with  

E-print Network

PII S0016-7037(00)00336-7 Atomistic simulation of trace element incorporation into garnets--comparison with experimental garnet-melt partitioning data W. VAN WESTRENEN,1, * N. L. ALLAN,2 J. D. BLUNDY,1 J. A. PURTON,3 into pure almandine (Alm), grossular (Gros), pyrope (Py) and spessartine (Spes) garnets (X3Al2Si3O12, with X

van Westrenen, Wim

474

A new formulation of garnet-clinopyroxene thermometer using large number of experimental data with graphite capsules  

E-print Network

A new formulation of garnet-clinopyroxene thermometer using large number of experimental data University, Kyoto 606-8502, Japan. kyec8@goo.jp Previous experimental data including garnet and clinopyroxene as run products are accumulated, and a new formulation of garnet-clinopyroxene thermometer is created

Nakamura, Daisuke

475

Single antidot as a passive way to create caustic spin-wave beams in yttrium iron garnet films  

E-print Network

Single antidot as a passive way to create caustic spin-wave beams in yttrium iron garnet films R://apl.aip.org/about/rights_and_permissions #12;Single antidot as a passive way to create caustic spin-wave beams in yttrium iron garnet films R in yttrium iron garnet film. Diffraction of surface magnetostatic spin waves from such antidot

Demokritov, S.O.

476

American Mineralogist, Volume 75, pages 859-873,1990 Fluorian garnets from the host rocks of the Skaergaard intrusion  

E-print Network

American Mineralogist, Volume 75, pages 859-873,1990 Fluorian garnets from the host rocks-deficient, calcic garnets containing up to 5 mol% F substitution for 0 formed during contact metamorphism of basalts by the Skaergaard intrusion in East Greenland. Fluorian calcic garnets occur as a retrograde alteration of prograde

Manning, Craig

477

Local order and magnetic behavior of amorphous and nanocrystalline yttrium iron garnet produced by swift heavy ion irradiations  

E-print Network

Local order and magnetic behavior of amorphous and nanocrystalline yttrium iron garnet produced-doped and undoped yttrium iron garnet Y3Fe5O12 or YIG on nonmagnetic Gd3Ga5O12 substrates were irradiated with swift of the fivefold-coordinated pyramidal sites and/or ii a probable decomposition of the garnet into orthoferrite

Paris-Sud XI, Université de

478

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

E-print Network

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

Qin Xu; Nikolai Qudalov; Qiti Guo; Heinrich Jaeger; Eric Brown

2012-01-23

479

Energy deposition in gallium arsenide. Final report  

SciTech Connect

This report pertains to the single-event-upset phenomena in microelectronic circuits with emphasis on those resulting from nuclear reactions induced by energetic protons. The goal is to understand the detailed physical mechanisms leading to SEUs sufficiently to put calculating SEUs on a sound quantitative basis. The author previously had considerable success in predicting the charge generation in well defined slabs of silicon. The purpose of this contract was to try extending the model and the associated simulation codes to GaAs and to begin the experimental measurements necessary to test them. The Clarkson Nuclear Reaction models were modified to handle proton-induced nuclear reactions in gallium arsenide. The codes were immediately useful in analyzing the significance that the edge-effect phenomena, discovered in microbeam studies of GaAs gates, would play in increasing the SEU rates for GaAs memories. Techniques were developed using these codes for calculating SEU rates for select circuits flown in space. Two of these circuits, the 2901B and the 93L422, are responsible for SEU problems aboard US satellites. Charge-collection Measurements were carried out using the GaAs Fat-FET test structures from the Rockwell memories.

McNulty, P.J.

1985-11-12

480

Gallium arsenide photo-field emission  

NASA Astrophysics Data System (ADS)

The development of monochromatic ultrafast electron sources with high brightness and high coherence is increasingly important in both time-resolved and energy-resolved electron microscopy. This work details the fabrication of intrinsic Gallium-Arsenide photo-field emitters and their evaluation as potential source candidates. The emitters were prepared via chemical etching and vacuum heat cleansing of cleaved wafer shards that had been mounted in refractory metal holders. Data were recorded in the form of field emission images, current-voltage characteristic curves and energy distribution curves under several different thermal and illumination conditions. As expected, illumination increased emission by 3 orders of magnitude. However a much larger than expected energy distribution of 0.76 eV was observed. This result invalidated presumptions that the band structure would produce a maximum energy width equal to the energy bandgap minus the photon energy. Following the experiment a Spicer-like 3-step model was used to explain this discrepancy. In the model the energy broadening is attributed to a combination of bulk thermal effects and surface band bending. Using this model, predictions are made as to the performance of a similar photo-field emitter that should better fulfill the needs of both time-resolved and energy-resolved electron microscopy.

Vecchione, Theodore

481

Reactive ion etching of gallium nitride films  

NASA Astrophysics Data System (ADS)

Reactive ion etching (RIE) was performed on gallium nitride (GaN) films grown by electron cyclotron resonance (ECR) plasma assisted molecular beam epitaxy (MBE). Etching was carried out using trifluoromethane (CHF3) and chloropentafluoroethane (C2ClF5) plasmas with Ar gas. A conventional rf plasma discharge RIE system without ECR or Ar ion gun was used. The effects of chamber pressure, plasma power, and gas flow rate on the etch rates were investigated. The etch rate increased linearly with the ratio of plasma power to chamber pressure. The etching rate varied between 60 and 500Å/min, with plasma power of 100 to 500W, chamber pressure of 60 to 300 mTorr, and gas flow rate of 20 to 50 seem. Single crystalline GaN films on sapphire showed a slightly lower etch rate than domain-structured GaN films on GaAs. The surface morphology quality after etching was examined by atomic force microscopy and scanning electron microscopy.

Lee, Heon; Oberman, David B.; Harris, James S.

1996-05-01

482

Antibacterial effect of gallium and silver on Pseudomonas aeruginosa treated with gallium-silver-phosphate-based glasses.  

PubMed

Gallium and silver incorporated phosphate-based glasses were evaluated for antibacterial effect on the growth of Pseudomonas aeruginosa, which is a leading cause of opportunistic infections. The glasses were produced by conventional melt quenching methods at 1100°C for 1 h. Glass degradation studies were conducted by weight loss method. Disc diffusion assay and cell viability assay displayed statistically significant (p ? 0.0005) effect on P. aeruginosa growth which increased with decreasing calcium content in the glasses. The gallium ion release rates (1.83, 0.69 and 0.48 ppm·h(-1)) and silver ion release rates (2.97, 2.84 and 2.47 ppm·h(-1)) were found to account for this variation. Constant depth film fermentor was used to evaluate the anti-biofilm properties of the glasses. Both gallium and silver in the glass contributed to biofilm growth inhibitory effect on P. aeruginosa (up to 2.68 reduction in log?10 values of the viable counts compared with controls). The glasses were found to deliver gallium and silver in a controlled way and exerted cumulative antibacterial action on planktonic and biofilm growth of P. aeruginosa. The antibacterial, especially anti-biofilm, properties of the gallium and silver incorporated phosphate-based glasses make them a potential candidate to combat infections caused by P. aeruginosa. PMID:24840197

Valappil, Sabeel P; Higham, Susan M

2014-01-01

483

Pressure-controlled formation of asymmetric chemical zoning in garnet  

NASA Astrophysics Data System (ADS)

Chemical zoning in garnet reflects variations in pressure (P) and temperature (T) along the path which the rock experienced. Such a zoning can be preserved in situations where diffusional homogenization and metasomatism is absent. Traditional inverse growth zoning models can only predict and explain symmetrical zoning. However, asymmetrical zoning is often observed in nature as well. In this contribution, we therefore focus on a prograde asymmetrical zoning in garnets that happens under fluid saturated conditions. In such examples, it is assumed that the surrounding fluid homogenizes its chemical composition rapidly and that it is in chemical equilibrium with rims of adjacent minerals. Therefore, a possibility of zoning caused by a local fluid chemical heterogeneity is ruled out. However, it has been proved that fluid pressure varies along the grain boundaries, in particular, during pressure solution processes. Hence, the asymmetrical zoning may be controlled by the variations in fluid pressure if the local equilibrium is satisfied. In this study, the influence of fluid pressure variation on chemical zoning is investigated using thermodynamic calculation with PerpleX implemented into a Matlab script to simulate the formation of asymmetrical chemical zoning caused by different pressure gradient along the grain boundaries. The possibility of comparing the thermodynamic calculation with numerical simulation is feasible, as the process of brute-force computational method using PerpleX can be segmented taking into account the varying pressure. In contrast to the traditional point of view of the prograde growth zoning in garnet, it is proved that grain scale fluid pressure variation, even on the order of 0.1 GPa, can be a reason for the development of the asymmetric zoning. Future work will focus on the relation between grain scale chemistry and mechanics using numerical and analytical techniques. This work was supported by ERC starting grant 335577 to Lucie Tajcmanova.

Zhong, Xin; Vrijmoed, Johannes; Tajcmanova, Lucie

2014-05-01

484

Magnetic field rotation in the screw gallium flow  

NASA Astrophysics Data System (ADS)

The magnetic field induced by the nonstationary screw flow of gallium in a toroidal channel has been investigated experimentally using a gallium prototype of the sodium apparatus developed in the frame of the experimental dynamo program at the Institute of Continuous Media Mechanics, Perm, Russia. The experimental set-up is a rapidly rotating toroidal channel subjected to abrupt braking. The screw flow is initiated by inertial forces pushing liquid gallium through diverters. The regular structure of the induced magnetic field is generated about 0.1 s after the stop of the channel and persists up to 1 s. The induced field is measured by sensors placed outside the channel. The inductive effects observed are attributed to the mean screw flow. The decay laws of the induced regular magnetic field and turbulent magnetic fluctuations are studied.

Noskov, V.; Denisov, S.; Frick, P.; Khripchenko, S.; Sokoloff, D.; Stepanov, R.

2004-10-01

485

The Soviet-American gallium experiment at Baksan  

SciTech Connect

A gallium solar neutrino detector is sensitive to the full range of the solar neutrino spectrum, including the low-energy neutrinos from the fundamental proton-proton fusion reaction. If neutrino oscillations in the solar interior are responsible for the suppressed {sup 8}B flux measured by the Homestake {sup 37}Cl experiment and the Kamiokande water Cherenkov detector, then a comparison of the gallium, chlorine, and water results may make possible a determination of the neutrino mass difference and mixing angle. A 30-ton gallium detector is currently operating in the Baksan laboratory in the Soviet Union, with a ratio of expected solar signal to measured background (during the first one to two {sup 71}Ge half lives) of approximately one. 28 refs.

Abazov, A. I.; Abdurashitov, D. N.; Anosov, O. L.; Danshin, S. N.; Eroshkina, L. A.; Faizov, E. L.; Gavrin, V. N.; Kalikhov, A. V.; Knodel, T. V.; Knyshenko, I. I.; Kornoukhov, V. N.; Mezentseva, S. A.; Mirmov, I. N.; Ostrinsky, A. I.; Petukhov, V. V; Pshukov, A. M.; Revzin, N. Ye; Shikhin, A. A.; Slyusareva, Ye. D.; Timofeyev, P. V.; Veretenkin, E. P.; Vermul, V. M.; Yantz, V. E.; Zakharov, Yu.; Zatsepin, G. T.; Zhandarov, V. I. [AN SSSR, Mosco

1990-01-01

486

Effect of bronchoscopy on localization of gallium-67 citrate  

SciTech Connect

Bronchoscopy, bronchoalveolar lavage (BAL), and 67Ga lung scans are frequently performed for diagnosis or follow-up of patients with sarcoidosis, interstitial pneumonitis, lymphoma, infections, and bronchogenic carcinoma. Because many patients undergo all 3 of these procedures, it is important to determine what effects bronchoscopy and/or BAL may have on gallium imaging. Because 67Ga accumulates in neutrophils at the site of an inflammatory lesion as well as in those circulating in the vascular compartment, it seems reasonable to postulate that bronchoscopy could cause migration of labeled neutrophils into the lung, resulting in false positive gallium scans. To test this hypothesis, we studied 5 patients with varying chronologic relationships of 67Ga injection, gallium scanning, and bronchoscopy with BAL. In all patients, the repeat 67Ga lung scans remained normal or showed no change after bronchoscopy and BAL. We conclude that bronchoscopy with or without BAL does not cause increased 67Ga uptake by the lung.

Phillips, B.A.; Cooper, K.R.; Fratkin, M.J.

1983-03-01

487

Dipeptide-assisted growth of uniform gallium oxohydroxide spindles  

NASA Astrophysics Data System (ADS)

The catalytic dipeptide His-Ser was used as an additive in mineralizing gallium ions to form GaOOH, a solid precursor of Ga 2O 3. This dipeptide was chosen to mimic the enzyme structure of silicatein, similar to the well-known catalytic triad of chymotrypsin. The dipeptide promoted formation of spindle-structured GaOOH under acidic conditions by behaving as a heterogeneous nucleation seed. In contrast, no well-defined, structured gallium species were produced in the absence of dipeptide. The catalytic function of the dipeptide was most pronounced at pH values in the range 3-5, which are lower than the pKa of imidazole in the His side chain. These results suggest that the catalytic role of dipeptide influences the gallium hydroxide conversion and growth. This study suggests that a designed peptide with active functionality can be further exploited to produce inorganic compounds with controlled nucleation and growth.

Lee, Inho; Kwak, Jinyoung; Haam, Seungjoo; Lee, Sang-Yup

2010-07-01

488

Extremely-efficient, miniaturized, long-lived alpha-voltaic power source using liquid gallium  

NASA Technical Reports Server (NTRS)

A power source converts .alpha.-particle energy to electricity for use in electrical systems. Liquid gallium or other liquid medium is subjected to .alpha.-particle emissions. Electrons are freed by collision from neutral gallium atoms to provide gallium ions. The electrons migrate to a cathode while the gallium ions migrate to an anode. A current and/or voltage difference then arises between the cathode and anode because of the work function difference of the cathode and anode. Gallium atoms are re