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

PubMed

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

2011-08-01

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

Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

PubMed

Maeda, Y

1994-01-10

Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

Optical and Magnetic Resonance Investigations of 3d Ions in Single Crystal Hosts: Candidates for Tunable Solid-State Lasers

DTIC Science & Technology

1994-04-25

Resonance Spectroscopy of Chromium-Doped Lanthanum Lutetium Gallium Garnet, M. H. Whitmore and D.J. Singel 8. 51V modulation of Mn5+ electron spin echoes in...Doped Lanthanum Lutetium Gallium Garnet Chapter 9 Characterization of Optical Centers in Mn.Ba3(VO4)2 178 by Spin-Echo EPR Spectroscopy I I ! I ii I i I I...previously unpublished EPR results on Cr:gehlenites (Chapter 6) and Cr:LLGG (lanthanum lutetium gallium garnet) (Chapter 8). The gehlenite spectra do

Optical and scintillation properties of Nd-doped complex garnet

NASA Astrophysics Data System (ADS)

Yanagida, Takayuki; Sato, Hiroki

2014-12-01

Nd 1% doped complex garnet scintillators were prepared by Furukawa and their optical and scintillation properties were investigated on a comparison with previously reported Nd-doped YAG. Chemical compositions of newly developed complex garnets were Lu2Y1Al5O12, Lu2Y1Ga3Al2O12, Lu2Gd1Al5O12, Lu2Gd1Ga3Al2O12, Gd1Y2Al5O12, Gd1Y2Ga3Al2O12, and Gd3Ga3Al2O12. They all showed 50-80% transmittance from ultraviolet to near infrared wavelengths with several absorption bands due to Gd3+ or Nd3+ 4f-4f transition. In X-ray induced radioluminescence spectra, all samples exhibited intense lines at 310 nm due to Gd3+ or 400 nm due to Nd3+ depending on their chemical composition. Among them, the highest scintillation light yield was achieved by Lu2Y1Al5O12. Typical scintillation decay times of them resulted 1.5-3 μs. Thermally stimulated glow curve after 1 Gy exposure and X-ray induced afterglow were also investigated.

Tunable Microwave Transversal Filters and Dispersive Delay Lines Based on Oblique Incidence Reflection of Magnetostatic Wave Propagating in Epitaxial Garnets.

DTIC Science & Technology

1986-09-30

surface. Ferromagnetic resonance measurements on Ion implanted garnet films (2.18, 2.19) have confirmed that the principal effects of ion implantation...Yttrium Iro Garnet (Y 3FesO1 2 ) films used in the experiments were grown or one Inch polished [111] oriented Gadolinium Gallium Garnet (GGG) wafers, by...Yttrium Iron Garnet ) films grown on 0.5mm thick substrate of GGG (Gadolinium Gallium Garnet ). Samples were angle lapped to optimize coupling into and

High energy resolution with transparent ceramic garnet scintillators

NASA Astrophysics Data System (ADS)

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

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.

Electronic transport properties of graphene doped by gallium.

PubMed

Mach, J; Procházka, P; Bartošík, M; Nezval, D; Piastek, J; Hulva, J; Švarc, V; Konečný, M; Kormoš, L; Šikola, T

2017-10-13

In this work we present the effect of low dose gallium (Ga) deposition (<4 ML) performed in UHV (10 -7 Pa) on the electronic doping and charge carrier scattering in graphene grown by chemical vapor deposition. In situ graphene transport measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.

Electronic transport properties of graphene doped by gallium

NASA Astrophysics Data System (ADS)

Mach, J.; Procházka, P.; Bartošík, M.; Nezval, D.; Piastek, J.; Hulva, J.; Švarc, V.; Konečný, M.; Kormoš, L.; Šikola, T.

2017-10-01

In this work we present the effect of low dose gallium (Ga) deposition (<4 ML) performed in UHV (10-7 Pa) on the electronic doping and charge carrier scattering in graphene grown by chemical vapor deposition. In situ graphene transport measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.

Spray deposited gallium doped tin oxide thinfilm for acetone sensor application

NASA Astrophysics Data System (ADS)

Preethi, M. S.; Bharath, S. P.; Bangera, Kasturi V.

2018-04-01

Undoped and gallium doped (1 at.%, 2 at.% and 3 at.%) tin oxide thin films were prepared using spray pyrolysis technique by optimising the deposition conditions such as precursor concentration, substrate temperature and spraying rate. X-ray diffraction analysis revealed formation of tetragonally structured polycrystalline films. The SEM micrographs of Ga doped films showed microstructures. The electrical resistivity of the doped films was found to be more than that of the undoped films. The Ga-doped tin oxide thin films were characterised for gas sensors. 1 at.% Ga doped thin films were found to be better acetone gas sensor, showed 68% sensitivity at 350°C temperature.

Cr3+-Doped Yb3Ga5O12 Nanophosphor: Synthesis, Optical, EPR, Studies

NASA Astrophysics Data System (ADS)

Singh, Vijay; Sivaramaiah, G.; Rao, J. L.; Singh, N.; Pathak, M. S.; Jirimali, H. D.; Singh, Pramod K.; Srivastava, Anoop K.; Dhoble, S. J.; Mohapatra, M.

2016-08-01

Gallium garnets of lanthanides are multifunctional materials especially known for their complicated structure and magnetic properties. In addition, with a suitable transition metal dopant ion, these matrices have been proved to be excellent materials for lasers. In particular, gallium garnet of ytterbium (Yb3Ga5O12) is known to possess excellent properties with regards to these applications. In this connection, Yb3Ga5O12 doped with Cr3+ nanophosphors were synthesized by a solution combustion route. The synthesized material was characterized by powder x-ray diffraction and scanning electron microscopy for phase purity and homogenous morphology. In order to ascertain the oxidation state of the doped ion, diffuse reflectance (DRF), photoluminescence (PL) and electron paramagnetic resonance (EPR) experiments were performed on the sample. The DRF and PL data suggested the stabilisation of the trivalent Cr ion in the matrix. The EPR spectra exhibited two resonance signals with effective g values at g ≈ 7.6 and 4. The EPR data corroborated the DRF and PL results, suggesting the stabilisation of Cr3+ in the matrix at octahedral-type geometries.

Damage induced in garnets by heavy ion irradiations: a study by optical spectroscopies

NASA Astrophysics Data System (ADS)

Costantini, Jean-Marc; Miro, Sandrine; Lelong, Gérald; Guillaumet, Maxime; Toulemonde, Marcel

2018-02-01

The damage induced by heavy-ion irradiation has been studied in yttrium iron garnet (Y3Fe5O12 or YIG) films, doped with Ca, Tb and Tm, grown by liquid-phase epitaxy on gadolinium gallium garnet (Gd3Ga5O12 or GGG) substrates. Irradiations of doped-YIG epitaxial films and GGG substrates with 36-MeV 183W and 12-MeV 197Au ions were applied for fluences between 1 × 1013 and 3 × 1015 cm-2 near room temperature. The radiation damage was monitored by micro-Raman spectroscopy and UV-visible optical absorption spectroscopy. Raman spectra revealed that amorphisation was achieved in YIG for both ions, whereas a high lattice disorder was induced in GGG without reaching amorphisation for the Au ion irradiation. Raman spectra also showed that a major damage of the tetrahedral sites was induced in GGG, as previously found for YIG. It is concluded that with such ions reaching the stopping power threshold of track formation in YIG and GGG the observed rate of amorphisation may result from a combination of electronic and nuclear energy losses as calculated using the unified thermal spike model.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of Φ 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%.

Gallium-doped germanium, evaluation of photoconductors, part 1

NASA Technical Reports Server (NTRS)

Moore, W. J.

1979-01-01

Gallium-doped germanium far infrared detectors were evaluated at low temperatures and low background simulating the space environment. Signal and noise characteristics were determined for detector temperatures in the 2K to 4K range. Optimum performance occurs at about 2.5K for all devices tested. The minimum average NEP in the 40-130 micron region was found to be approximately 4 x 10 to the minus 17th power watt Hz(-1/2) at a frequency of 1 Hz.

Origin of high Li⁺ conduction in doped Li₇La₃Zr₂O₁₂ garnets

DOE PAGES

Chen, Yan; Rangasamy, Ezhiylmurugan; Liang, Chengdu; ...

2015-08-06

Substitution of a native ion in the crystals with a foreign ion that differs in valence ( aliovalent doping) has been widely attempted to upgrade solid-state ionic conductors for various charge carriers including O²⁻, H⁺, Li⁺, Na⁺, etc. The doping helps promote the high-conductive framework and dredge the tunnel for fast ion transport. The garnet-type Li₇La₃Zr₂O₁₂ (LLZO) is a fast Li⁺ solid conductor, which received much attention as an electrolyte candidate for all-solid-state lithium ion batteries, showing great potential to offer high energy density and minimize battery safety concerns to meet extensive applications in large energy storage systems such asmore » those for electric vehicles and aerospace. In the Li-stuffed garnet framework of LLZO, the 3D pathway formed by the incompletely occupied tetrahedral sites bridged by a single octahedron enables the superior Li⁺ conductivity. For optimal performance, many aliovalent-doping efforts have been made throughout metal elements (Al³⁺, Ta⁵⁺) and metalloid elements (Ga³⁺, Te⁶⁺) in the periodic table with various valences to stabilize the high-conductive phase and increase the Li vacancy concentration.« less

Effects of an erbium, chromium: yttrium, scandium, gallium, garnet laser on mucocutanous soft tissues.

PubMed

Rizoiu, I M; Eversole, L R; Kimmel, A I

1996-10-01

Lasers are effective tools for soft tissue surgery. The erbium, chromium: yttrium, scandium, gallium, garnet laser is a new system that incorporates an air-water spray. This study evaluates the cutting margins of this laser and compares healing with laser and conventional scalpel and punch biopsy-induced wounds. New Zealand white rabbits were divided into serial sacrifice groups; the tissues were grossly and microscopically analyzed after laser and convential steel surgical wounding. Wound margins were found to show minimal edge coagulation artifact and were 20 to 40 mm in width. Laser wounds showed minimal to no hemorrhage and re-epithelialization and collagenization were found to occur by day 7 in both laser and conventional groups. The new laser system is an effective soft tissue surgical device; wound healing is comparable to that associated with surgical steel wounds. The minimal edge artifact observed with this laser system should allow for the procurement of diagnostic biopsy specimens.

Spin polarized first principles study of Mn doped gallium nitride monolayer nanosheet

NASA Astrophysics Data System (ADS)

Sharma, Venus; Kaur, Sumandeep; Srivastava, Sunita; Kumar, Tankeshwar

2017-05-01

The structural, electronic and magnetic properties of gallium nitride nanosheet (GaNs) doped with Mn atoms have been studied using spin polarized density functional theory. The binding energy per atom, Energy Band gap, Fermi energy, magnetic moment, electric dipole moment have been found. The doped nanosheet is found to be more stable than pure GaN monolayer nanosheet. Adsorption of Mn atom has been done at four different sites on GaNs which affects the fermi level position. It is found that depending on the doping site, Mn can behave both like p-type semiconductor and also as n-type semiconductor. Also, it is ascertained that Mn doped GaNs (GaNs-Mn) exhibits ferromagnetic behavior.

Effects of erbium-and chromium-doped yttrium scandium gallium garnet and diode lasers on the surfaces of restorative dental materials: a scanning electron microscope study.

PubMed

Hatipoglu, M; Barutcigil, C

2015-01-01

The aim of this study is to evaluate the potential effects of laser irradiation, which is commonly performed in periodontal surgery, on the surfaces of restorative materials. Five different restorative dental materials were used in this study, as follows: (1) Resin composite, (2) poly acid-modified resin composite (compomer), (3) conventional glass ionomer cement (GIC), (4) resin-modified glass ionomer cement (RMGIC), and (5) amalgam. Four cylindrical samples (8 mm diameter, 2 mm height) were prepared for each restorative material. In addition, four freshly extracted, sound human incisors teeth were selected. Two different laser systems commonly used in periodontal surgery were examined in this study: A 810 nm diode laser at a setting of 1 W with continuous-phase laser irradiation for 10 s, and an erbium-and chromium-doped yttrium scandium gallium garnet (Er, Cr: YSGG) laser at settings of 2.5 W, 3.25 W, and 4 W with 25 Hz laser irradiation for 10 s. Scanning electron microscopy (SEM) analysis was performed to evaluate the morphology and surface deformation of the restorative materials and tooth surfaces. According to the SEM images, the Er, Cr: YSGG laser causes irradiation markings that appear as demineralized surfaces on tooth samples. The Er, Cr: YSGG laser also caused deep defects on composite, compomer, and RMGIC surfaces because of its high power, and the ablation was deeper for these samples. High-magnification SEM images of GIC samples showed the melting and combustion effects of the Er, Cr: YSGG laser, which increased as the laser power was increased. In amalgam samples, neither laser left significant harmful effects at the lowest power setting. The diode laser did cause irradiation markings, but they were insignificant compared with those left by the Er, Cr: YSGG laser on the surfaces of the different materials and teeth. Within the limitations of this study, it can be concluded that Er, Cr: YSGG laser irradiation could cause distortions of the surfaces

Heat capacity of rare-earth cuprates, orthovanadates, and aluminum garnets, gallium garnets, and iron garnets

NASA Astrophysics Data System (ADS)

Denisova, L. T.; Kargin, Yu. F.; Denisov, V. M.

2015-08-01

The correlation between the heat capacities of rare-earth cuprates, orthovanadates, and garnets with ionic radius R 3+ has been analyzed. It has been shown that the values of C {/p 0} change consistently depending on the radius R 3+ within the corresponding tetrads (La-Nd, Pm-Gd, Gd-Ho, Eu-Lu).

Complete Stokes polarimetry of magneto-optical Faraday effect in a terbium gallium garnet crystal at cryogenic temperatures.

PubMed

Majeed, Hassaan; Shaheen, Amrozia; Anwar, Muhammad Sabieh

2013-10-21

We report the complete determination of the polarization changes caused in linearly polarized incident light due to propagation in a magneto-optically active terbium gallium garnet (TGG) single crystal, at temperatures ranging from 6.3 to 300 K. A 28-fold increase in the Verdet constant of the TGG crystal is seen as its temperature decreases to 6.3 K. In contrast with polarimetry of light emerging from a Faraday material at room temperature, polarimetry at cryogenic temperatures cannot be carried out using the conventional fixed polarizer-analyzer technique because the assumption that ellipticity is negligible becomes increasingly invalid as temperature is lowered. It is shown that complete determination of light polarization in such a case requires the determination of its Stokes parameters, otherwise inaccurate measurements will result with negative implications for practical devices.

Radiation stability of visible and near-infrared optical and magneto-optical properties of terbium gallium garnet crystals.

PubMed

Geist, Brian; Ronningen, Reginald; Stolz, Andreas; Bollen, Georg; Kochergin, Vladimir

2015-04-01

Perspectives of terbium gallium garnet, Tb₃Ga₅O₁₂ (TGG), for the use of radiation-resistant high magnetic field sensing are studied. Long-term radiation stability of the TGG crystals was analyzed by comparing the optical and magneto-optical properties of a radiation-exposed TGG crystal (equivalent neutron dose 6.3×10¹³ n/cm²) to the properties of TGG control samples. Simulations were also performed to predict radiation damage mechanisms in the TGG crystal. Radiation-induced increase in the absorbance at shorter wavelengths was observed as well as a reduction in the Faraday effect while no degradation of magneto-optical effect was observed when at wavelengths above 600 nm. This suggests that TGG crystal would be a good candidate for use in magneto-optical radiation-resistant magnetic field sensors.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Picosecond laser with active mode locking and calcium lithium niobium gallium disordered Nd3+-activated garnet

NASA Astrophysics Data System (ADS)

Basiev, Tasoltan T.; Grudinin, A. B.; Karasik, Aleksandr Ya; Senatorov, A. K.; Sobol, A. A.; Fedorov, V. V.; Shubochkin, R. L.

1994-01-01

A laser was constructed in which the active medium was a crystal of calcium lithium niobium gallium garnet activated with Nd3+ ions. An acoustooptic modulator made of an LiNbO3 crystal and a passive LiF switch with F2 colour centres were used in this laser. The combination of active mode locking and Q switching made it possible to generate laser pulses of 10-15 ps duration at the wavelength λ = 1061.2 nm with a peak power of about 15 MW.

The effect of silver or gallium doped titanium against the multidrug resistant Acinetobacter baumannii.

PubMed

Cochis, A; Azzimonti, B; Della Valle, C; De Giglio, E; Bloise, N; Visai, L; Cometa, S; Rimondini, L; Chiesa, R

2016-02-01

Implant-related infection of biomaterials is one of the main causes of arthroplasty and osteosynthesis failure. Bacteria, such as the rapidly-emerging Multi Drug Resistant (MDR) pathogen Acinetobacter Baumannii, initiate the infection by adhering to biomaterials and forming a biofilm. Since the implant surface plays a crucial role in early bacterial adhesion phases, titanium was electrochemically modified by an Anodic Spark Deposition (ASD) treatment, developed previously and thought to provide osseo-integrative properties. In this study, the treatment was modified to insert gallium or silver onto the titanium surface, to provide antibacterial properties. The material was characterized morphologically, chemically, and mechanically; biological properties were investigated by direct cytocompatibility assay, Alkaline Phosphatase (ALP) activity, Scanning Electron Microscopy (SEM), and Immunofluorescent (IF) analysis; antibacterial activity was determined by counting Colony Forming Units, and viability assay. The various ASD-treated surfaces showed similar morphology, micrometric pore size, and uniform pore distribution. Of the treatments studied, gallium-doped specimens showed the best ALP synthesis and antibacterial properties. This study demonstrates the possibility of successfully doping the surface of titanium with gallium or silver, using the ASD technique; this approach can provide antibacterial properties and maintain high osseo-integrative potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

Efficacy of Erbium, Chromium-doped:Yttrium, Scandium, Gallium, and Garnet Laser Irradiation Combined with Resin-based Tricalcium Silicate and Calcium Hydroxide on Direct Pulp Capping: A Randomized Clinical Trial.

PubMed

Cengiz, Esra; Yilmaz, Hasan Guney

2016-03-01

The purpose of this randomized clinical study was to evaluate the efficiency of erbium, chromium-doped:yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser irradiation combined with a resin-based tricalcium silicate material and calcium hydroxide in direct pulp capping for a 6-month follow-up period. A total of 60 teeth of 60 patients between the ages of 18 and 41 years were recruited for this study. Sixty permanent vital teeth without symptoms and radiographic changes were randomly assigned to the following 4 groups (n = 15): Gr CH, the exposed area was sealed with calcium hydroxide (CH) paste; Gr laser CH, the treated area was sealed with CH paste after Er,Cr:YSGG laser irradiation at an energy level of 0.5 W without water and with 45% air; Gr TheraCal, TheraCal LC (Bisco, Schaumburg, IL) was applied directly to the exposed pulp; and Gr Laser TheraCal, TheraCal LC was applied after irradiation with an Er,Cr:YSGG laser. At the 1-week and 1-, 3-, and 6-month recall examinations, the loss of vitality, spontaneous pain, reactions to thermal stimuli and percussion, and radiographic changes were considered as failure. The success rates in the CH and TheraCal groups were 73.3% and 66.6%, respectively. These rates did not reveal any significant difference. In both laser groups, success rates were 100%. The Er,Cr:YSGG laser-irradiated TheraCal and Er,Cr:YSGG laser-irradiated CH groups showed statistically higher success rates than the TheraCal and CH groups, respectively. Er,Cr:YSGG laser irradiation at 0.5 W without water combined with pulp capping agents can be recommended for direct pulp therapy. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Precision calibration of the silicon doping level in gallium arsenide epitaxial layers

NASA Astrophysics Data System (ADS)

Mokhov, D. V.; Berezovskaya, T. N.; Kuzmenkov, A. G.; Maleev, N. A.; Timoshnev, S. N.; Ustinov, V. M.

2017-10-01

An approach to precision calibration of the silicon doping level in gallium arsenide epitaxial layers is discussed that is based on studying the dependence of the carrier density in the test GaAs layer on the silicon- source temperature using the Hall-effect and CV profiling techniques. The parameters are measured by standard or certified measuring techniques and approved measuring instruments. It is demonstrated that the use of CV profiling for controlling the carrier density in the test GaAs layer at the thorough optimization of the measuring procedure ensures the highest accuracy and reliability of doping level calibration in the epitaxial layers with a relative error of no larger than 2.5%.

P-type gallium nitride

DOEpatents

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

1997-08-12

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.

P-type gallium nitride

DOEpatents

Rubin, Michael; Newman, Nathan; Fu, Tracy; Ross, Jennifer; Chan, James

1997-01-01

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.

Laser ceramic materials for subpicosecond solid-state lasers using Nd3+-doped mixed scandium garnets.

PubMed

Okada, Hajime; Tanaka, Momoko; Kiriyama, Hiromitsu; Nakai, Yoshiki; Ochi, Yoshihiro; Sugiyama, Akira; Daido, Hiroyuki; Kimura, Toyoaki; Yanagitani, Takagimi; Yagi, Hideki; Meichin, Noriyuki

2010-09-15

We have successfully developed and demonstrated broadband emission Nd-doped mixed scandium garnets based on laser ceramic technology. The inhomogeneous broadening of Nd(3+) fluorescence lines results in a bandwidth above 5 nm that is significantly broader than that for Nd:YAG and enables subpicosecond mode-locked pulse durations. We have also found the emission cross section of 7.8 × 10(-20) cm(2) to be adequate for efficient energy extraction and thermal conductivity of 4.7 W/mK from these new Nd-doped laser ceramics. The new laser ceramics are good candidates for laser host material in a diode-pumped subpicosecond laser system with high efficiency and high repetition rate.

Method of fabricating germanium and gallium arsenide devices

NASA Technical Reports Server (NTRS)

Jhabvala, Murzban (Inventor)

1990-01-01

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.

Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

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

Podhorodecki, A.; Banski, M.; Misiewicz, J.

Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samplesmore » that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.« less

High power single-frequency and frequency-doubled laser with active compensation for the thermal lens effect of terbium gallium garnet crystal.

PubMed

Yin, Qiwei; Lu, Huadong; Su, Jing; Peng, Kunchi

2016-05-01

The thermal lens effect of terbium gallium garnet (TGG) crystal in a high power single-frequency laser severely limits the output power and the beam quality of the laser. By inserting a potassium dideuterium phosphate (DKDP) slice with negative thermo-optical coefficient into the laser resonator, the harmful influence of the thermal lens effect of the TGG crystal can be effectively mitigated. Using this method, the stable range of the laser is broadened, the bistability phenomenon of the laser during the process of changing the pump power is completely eliminated, the highest output power of an all-solid-state continuous-wave intracavity-frequency-doubling single-frequency laser at 532 nm is enhanced to 30.2 W, and the beam quality of the laser is significantly improved.

Enhanced solar-blind responsivity of photodetectors based on cubic MgZnO films via gallium doping.

PubMed

Xie, Xiuhua; Zhang, Zhenzhong; Li, Binghui; Wang, Shuangpeng; Jiang, Mingming; Shan, Chongxin; Zhao, Dongxu; Chen, Hongyu; Shen, Dezhen

2014-01-13

We report on gallium (Ga) doped cubic MgZnO films, which have been grown by metal organic chemical vapor deposition. It was demonstrated that Ga doping improves the n-type conduction of the cubic MgZnO films. A two-orders of magnitude enhancement in lateral n-type conduction have been achieved for the cubic MgZnO films. The responsivity of the cubic MgZnO-based photodetector has been also enhanced. Depletion region electric field intensity enhanced model was adopted to explain the improvement of quantum efficiency in Ga doped MgZnO-based detectors.

Growth of rare-earth doped single crystal yttrium aluminum garnet fibers

NASA Astrophysics Data System (ADS)

Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Cheng, Long; Rand, Stephen C.; Li, Yuan; Johnson, Eric G.

2018-02-01

Rare-earth doped single crystal (SC) yttrium aluminum garnet (YAG) fibers have great potential as high-power laser gain media. SC fibers combine the superior material properties of crystals with the advantages of a fiber geometry. Improving processing techniques, growth of low-loss YAG SC fibers have been reported. A low-cost technique that allows for the growth of optical quality Ho:YAG single crystal (SC) fibers with different dopant concentrations have been developed and discussed. This technique is a low-cost sol-gel based method which offers greater flexibility in terms of dopant concentration. Self-segregation of Nd ions in YAG SC fibers have been observed. Such a phenomenon can be utilized to fabricate monolithic SC fibers with graded index.

High-resolution structural characterization and magnetic properties of epitaxial Ce-doped yttrium iron garnet thin films

NASA Astrophysics Data System (ADS)

Li, Zhong; Vikram Singh, Amit; Rastogi, Ankur; Gazquez, Jaume; Borisevich, Albina Y.; Mishra, Rohan; Gupta, Arunava

2017-07-01

Thin films of magnetic garnet materials, e.g. yttrium iron garnet (Y3Fe5O12, YIG), are useful for a variety of applications including microwave integrated circuits and spintronics. Substitution of rare earth ions, such as cerium, is known to enhance the magneto-optic Kerr effect (MOKE) as compared to pure YIG. Thin films of Ce0.75Y2.25Fe5O12 (Ce:YIG) have been grown using the pulsed laser deposition (PLD) technique and their crystal structure examined using high resolution scanning transmission electron microscopy. Homogeneous substitution of Ce in YIG, without oxidation to form a separate CeO2 phase, can be realized in a narrow process window with resulting enhancement of the MOKE signal. The thermally generated signal due to spin Seebeck effect for the optimally doped Ce:YIG films has also been investigated.

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

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.

Sodium enhances indium-gallium interdiffusion in copper indium gallium diselenide photovoltaic absorbers.

PubMed

Colombara, Diego; Werner, Florian; Schwarz, Torsten; Cañero Infante, Ingrid; Fleming, Yves; Valle, Nathalie; Spindler, Conrad; Vacchieri, Erica; Rey, Germain; Guennou, Mael; Bouttemy, Muriel; Manjón, Alba Garzón; Peral Alonso, Inmaculada; Melchiorre, Michele; El Adib, Brahime; Gault, Baptiste; Raabe, Dierk; Dale, Phillip J; Siebentritt, Susanne

2018-02-26

Copper indium gallium diselenide-based technology provides the most efficient solar energy conversion among all thin-film photovoltaic devices. This is possible due to engineered gallium depth gradients and alkali extrinsic doping. Sodium is well known to impede interdiffusion of indium and gallium in polycrystalline Cu(In,Ga)Se 2 films, thus influencing the gallium depth distribution. Here, however, sodium is shown to have the opposite effect in monocrystalline gallium-free CuInSe 2 grown on GaAs substrates. Gallium in-diffusion from the substrates is enhanced when sodium is incorporated into the film, leading to Cu(In,Ga)Se 2 and Cu(In,Ga) 3 Se 5 phase formation. These results show that sodium does not decrease per se indium and gallium interdiffusion. Instead, it is suggested that sodium promotes indium and gallium intragrain diffusion, while it hinders intergrain diffusion by segregating at grain boundaries. The deeper understanding of dopant-mediated atomic diffusion mechanisms should lead to more effective chemical and electrical passivation strategies, and more efficient solar cells.

Current German Laser and Quantum Optics Research Reviewed at the 50th Annual Meeting of the Physikalische Gesellschaft.

DTIC Science & Technology

1986-04-23

Physics, Munster In the area of generating useable University) studied an interesting de- coherent high-frequency radiation, I vice, a silicon Fabry ...has a substantial crys- tingen) described studies with Cr- plus tal growing capability. One paper from Nd-doped gadolinium -scandium-gallium the Hamburg...institute, read by J. Drube, garnets (GSGG), and also with Cr-doped reported on Xe-flashlamp-pumped Cr:CSA(; % gadolinium -scandium-aluminum garnets

Excitation of the three principal spin waves in yttrium iron garnet using a wavelength-specific multi-element antenna

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

Bang, Wonbae; Jungfleisch, Matthias B.; Lim, Jinho

We report systematic measurements of the dispersion of long wavelength spin waves for the magnetic field along the three principal directions (supporting the forward volume, backward volume and Damon-Eshbach modes) of a 3.05 um thick yttrium iron garnet film on a lattice-matched (111) gadolinium gallium garnet substrate obtained using a lithographically patterned, multi-element, 50 um spatially-resonant, antenna.

Excitation of the three principal spin waves in yttrium iron garnet using a wavelength-specific multi-element antenna

DOE PAGES

Bang, Wonbae; Jungfleisch, Matthias B.; Lim, Jinho; ...

2017-12-22

We report systematic measurements of the dispersion of long wavelength spin waves for the magnetic field along the three principal directions (supporting the forward volume, backward volume and Damon-Eshbach modes) of a 3.05 um thick yttrium iron garnet film on a lattice-matched (111) gadolinium gallium garnet substrate obtained using a lithographically patterned, multi-element, 50 um spatially-resonant, antenna.

Coupling Ocean Models and Satellite Derived Optical Fields to Estimate LIDAR Penetration and Detection Performance

DTIC Science & Technology

2012-01-01

34Laser oscillations in nd-doped yttrium aluminum , yttrium gallium and gadolinium garnets ," Applied Physics Letters (10): 182. doi:10.1063/1.1753928...Aluminium Garnet ) Nd:YAG lasers, and inherent of this material is its fundamental 1064nm frequency that is frequency doubled to 532 nm to penetrate

Excitation of the three principal spin waves in yttrium iron garnet using a wavelength-specific multi-element antenna

NASA Astrophysics Data System (ADS)

Bang, Wonbae; Jungfleisch, Matthias B.; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Hoffmann, Axel; Ketterson, John B.

2018-05-01

We report systematic measurements of the dispersion of long wavelength spin waves for the magnetic field along the three principal directions (supporting the forward volume, backward volume and Damon-Eshbach modes) of a 3.05 μm thick yttrium iron garnet film on a lattice-matched (111) gadolinium gallium garnet substrate obtained using a lithographically patterned, multi-element, 50 μm spatially-resonant, antenna.

Magnetic properties of manganites doped with gallium, iron, and chromium ions

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

Troyanchuk, I. O., E-mail: troyan@physics.by; Bushinsky, M. V.; Tereshko, N. V.

The magnetization and the crystal structure of the La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}M{sub x}O{sub 3} (M = Ga, Fe, Cr; x ≤ 0.3) systems are studied. The substitution of gallium and chromium is shown to cause phase separation into antiferromagnetic and ferromagnetic phases, whereas the substitution of iron for manganese stabilizes a spinglass state. The ferromagnetic phase in the chromium-substituted compositions is much more stable than that in the case of substitution by iron ions or diamagnetic gallium ions. The magnetic properties are explained in terms of the model of superexchange interactions and the localization of most e{sub g} electrons ofmore » manganese. The stabilization of ferromagnetism in the chromium-substituted compositions can be caused by the fact that the positive and negative contributions to the superexchange interaction between Mn{sup 3+} and Cr{sup 3+} ions are close to each other but the antiferromagnetic part of the exchange is predominant. Moreover, some chromium ions are in the tetravalent state, which maintains the optimum doping conditions.« less

P-n junctions formed in gallium antimonide

NASA Technical Reports Server (NTRS)

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

1970-01-01

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

Solution epitaxy of gallium-doped ZnO on p-GaN for heterojunction light-emitting diodes

NASA Astrophysics Data System (ADS)

Le, H. Q.; Lim, S. K.; Goh, G. K. L.; Chua, S. J.; Ang, N. S. S.; Liu, W.

2010-09-01

We report white light emission from a Ga-doped ZnO/p-GaN heterojunction light-emitting diode which was fabricated by growing gallium-doped ZnO film on the p-GaN in water at 90°C. As determined from Ga-doped ZnO films grown on (111) oriented MgAl2O4 spinel single crystal substrates, thermal treatment at 600°C in nitrogen ambient leads to a carrier concentration of 3.1×1020 cm-3 (and carrier mobility of 28 cm2/Vs) which is two orders of magnitude higher than that of the undoped films. Electroluminescence emissions at wavelengths of 393 nm (3.155 eV) and 529.5 nm (2.4 eV) were observed under forward bias in the heterojunction diode and white light could be visibly observed. The high concentration of electrons supplied from the Ga-doped ZnO films helped to enhance the carrier recombination and increase the light-emitting efficiency of the heterojunction diode.

Development of scintillating screens based on the single crystalline films of Ce doped (Gd,Y)3(Al,Ga,Sc)5O12 multi-component garnets

NASA Astrophysics Data System (ADS)

Zorenko, Yuriy; Gorbenko, Vitaliy; Savchyn, Volodymyr; Zorenko, Tanya; Fedorov, Alexander; Sidletskiy, Oleg

2014-09-01

The paper is dedicated to development of scintillators based on single crystalline films of Ce doped (Gd,Y)3(Al,Ga,Sc)5O12 multi-component garnets onto Gd3Ga5O12 substrates using the liquid phase epitaxy method.

Co-Precipitation Synthesis of Gadolinium Aluminum Gallium Oxide (GAGG) via Different Precipitants

NASA Astrophysics Data System (ADS)

Sun, Yan; Yang, Shenghui; Zhang, Ye; Jiang, Jun; Jiang, Haochuan

2014-02-01

In order to obtain a uniform transparent ceramic scintillator, well-dispersed fine starting powders with high-purity, small grain size, spherical morphology and high sinter-ability are necessary. In this study, Ce3+ doped gadolinium aluminum gallium garnet Gd3Al3Ga2O12 (GAGG) powders were synthesized by the co-precipitation method. NH4OH, NH4HCO3 and the mixed solution of NH4OH and NH4HCO3 were used as precipitants, respectively. The precursor composition, phase formation process, microstructure, morphology, particle size distribution and luminescent properties of obtained GAGG powders were measured. The results show that powders prepared using the mixed precipitant exhibit the best microstructural morphology, good sinter-ability and highest luminescent intensity. Pure GAGG polycrystalline powders could be obtained at about 950°C for 1.5 h and the average size of the particles is about 50 nm. The photoluminescence spectrum shows a strong green-yellow emission near 540 nm.

The temperature dependence of thermooptical properties of magnetooptical TAG ceramics doped with silicon and titanium

NASA Astrophysics Data System (ADS)

Starobor, Aleksey; Palashov, Oleg

2018-04-01

Thermal effects in terbium aluminum garnet (TAG) ceramics (thermal lens and thermally induced depolarization) doped with silicon and titanium were investigated in temperature range of 79-293K. Samples with low dopant concentrations shows decreasing of negative thermal effects with cooling to 79 K. However for most part of samples thermal depolarization starts increasing after initial decreasing with cooling. Apparently it is connected with defects in media. Best sample (0.4 at% of Si) as pure TAG shows monotonous decreasing of thermally induced depolarization and 3.5 times Verdet constant increasing with cooling to 79 K, that leads to 1.8-times advantage over common magnetooptical media - terbium gallium garnet. It allows to provide an isolation of 30 dB at a radiation power of more than 6 kW as estimated. However, the procedure for creating ceramics samples obviously needs improvement because of the large scatter in the quality of the samples.

Controlled delivery of antimicrobial gallium ions from phosphate-based glasses.

PubMed

Valappil, S P; Ready, D; Abou Neel, E A; Pickup, D M; O'Dell, L A; Chrzanowski, W; Pratten, J; Newport, R J; Smith, M E; Wilson, M; Knowles, J C

2009-05-01

Gallium-doped phosphate-based glasses (PBGs) have been recently shown to have antibacterial activity. However, the delivery of gallium ions from these glasses can be improved by altering the calcium ion concentration to control the degradation rate of the glasses. In the present study, the effect of increasing calcium content in novel gallium (Ga2O3)-doped PBGs on the susceptibility of Pseudomonas aeruginosa is examined. The lack of new antibiotics in development makes gallium-doped PBG potentially a highly promising new therapeutic agent. The results show that an increase in calcium content (14, 15 and 16 mol.% CaO) cause a decrease in degradation rate (17.6, 13.5 and 7.3 microg mm(-2) h(-1)), gallium ion release and antimicrobial activity against planktonic P. aeruginosa. The most potent glass composition (containing 14 mol.% CaO) was then evaluated for its ability to prevent the growth of biofilms of P. aeruginosa. Gallium release was found to reduce biofilm growth of P. aeruginosa with a maximum effect (0.86 log(10) CFU reduction compared to Ga2O3-free glasses) after 48 h. Analysis of the biofilms by confocal microscopy confirmed the anti-biofilm effect of these glasses as it showed both viable and non-viable bacteria on the glass surface. Results of the solubility and ion release studies show that this glass system is suitable for controlled delivery of Ga3+. 71Ga NMR and Ga K-edge XANES measurements indicate that the gallium is octahedrally coordinated by oxygen atoms in all samples. The results presented here suggest that PBGs may be useful in controlled drug delivery applications, to deliver gallium ions in order to prevent infections due to P. aeruginosa biofilms.

Growth of high quality yttrium iron garnet films using standard pulsed laser deposition technique

NASA Astrophysics Data System (ADS)

Zaki, Aliaa M.; Blythe, Harry J.; Heald, Steve M.; Fox, A. Mark; Gehring, Gillian A.

2018-05-01

Thin films with properties comparable to bulk single crystals were grown by pulsed laser deposition using a substrate temperature of only 500 °C. This was achieved by a careful choice of both the oxygen pressure in the deposition chamber and the temperature of the air anneal. The best films were grown on gadolinium gallium garnet substrates but we also report data for films grown on the diamagnetic substrate yttrium aluminium garnet. The films were analysed using X-ray diffraction, near edge X-ray absorption and magnetometry. Our best films had a magnetisation of 143 emu/cm3 and a coercive field of ∼1 Oe.

A study of suppressed formation of low-conductivity phases in doped Li 7La 3Zr 2O 12 garnets by in situ neutron diffraction

DOE PAGES

Chen, Yan; Rangasamy, Ezhiylmurugan; dela Cruz, Clarina R.; ...

2015-09-28

Doped Li 7La 3Zr 2O 12 garnets, oxide-based solids with good Li + conductivity and compatibility, show great potential as leading electrolyte material candidates for all-solid-state lithium ion batteries. Still yet, the conductive bulk usually suffers from the presence of secondary phases and the transition towards a low-conductivity tetragonal phase during synthesis. Dopants are designed to stabilize the high-conductive cubic phase and suppress the formation of the low-conductivity phases. In situ neutron diffraction enables a direct observation of the doping effects by monitoring the phase evolutions during garnet synthesis. It reveals the reaction mechanism involving the temporary presence of intermediatemore » phases. The off-stoichiometry due to the liquid Li 2CO 3 evaporation leads to the residual of the low-conductivity intermediate phase in the as-synthesized bulk. Appropriate doping of an active element may alter the component of the intermediate phases and promote the completion of the reaction. While the dopants aid to stabilize most of the cubic phase, a small amount of tetragonal phase tends to form under a diffusion process. Lastly, the in situ observations provide the guideline of process optimization to suppress the formation of unwanted low-conductivity phases.« less

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

Chen, Zhe, E-mail: zhenzhe1201@sina.com; Yang, Lei; Hang, Yin

Highly transparent Dy{sup 3+}-doped terbium gallium garnet (TGG) single crystal was grown by Czochralski (Cz) method. Phase composition of the crystal was tested by XRD measurements. The distribution coefficient of Dy{sup 3+} in the crystal was obtained. The optical and magneto-optical properties were analyzed in detail, and magnetic properties of the Dy{sup 3+}-TGG crystal were studied. The paramagnetic behavior is observed down to 10 K. The as-grown crystal exhibited high optical transmittance, particularly in the visible region. The Faraday rotation was investigated over visible and near-infrared regions (VIS–NIR) at room temperature. The Verdet constants increase at measured wavelengths and highmore » thermal stability was found in Dy{sup 3+}-doped TGG, as compared to the properties of pure TGG, indicating that Dy{sup 3+}-doped crystals are preferable for magneto-active materials used in Faraday devices at VIS–NIR wavelengths. - Graphical abstract: Highly transparent Dy{sup 3+}-doped terbium gallium garnet (TGG) and pure TGG single crystals were grown by Czochralski method. The Dy{sup 3+}-doped TGG possesses 20–30% higher Verdet values in reference to TGG independently on wavelength.« less

Fabrication and microstructure of cerium doped lutetium aluminum garnet (Ce:LuAG) transparent ceramics by solid-state reaction method

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

Li, Junlang, E-mail: lijunlangx@163.com; Xu, Jian, E-mail: xu.jian.57z@st.kyoto-u.ac.jp; Graduate School of Human and Environmental Studies, Division of Materials Function, Kyoto University, Kyoto 606-8501

2014-07-01

Highlights: • We fabricate Ce doped lutetium aluminum garnet ceramics by solid-state method. • The raw materials include Lu{sub 2}O{sub 3} nanopowders synthesized by co-precipitation method. • The density of the transparent ceramics reach 99.7% of the theoretical value. • The optical transmittance of the bulk ceramic at 550 nm was 57.48%. • Some scattering centers decrease the optical characteristic of the ceramic. - Abstract: Polycrystalline Ce{sup 3+} doped lutetium aluminum garnet (Ce:LuAG) transparent ceramics fabricated by one step solid-state reaction method using synthetic nano-sized Lu{sub 2}O{sub 3}, commercial α-Al{sub 2}O{sub 3} and CeO{sub 2} powders were investigated in thismore » paper. The green compacts shaped by the mixed powders were successfully densified into Ce:LuAG transparent ceramics after vacuum sintering at 1750 °C for 10 h. The in-line optical transmittance of the Ce:LuAG ceramic made by home-made Lu{sub 2}O{sub 3} powders could reach 57.48% at 550 nm, which was higher than that of the ceramic made by commercial Lu{sub 2}O{sub 3} powders (22.96%). The microstructure observation showed that light scattering centers caused by micro-pores, aluminum segregation and refraction index inhomogeneities induced the decrease of optical transparency of the Ce:LuAG ceramics, which should be removed and optimized in the future work.« less

Mid-Infrared Spectroscopy Analysis of the Effects of Erbium, Chromium:Yattrium-Scandium-Gallium-Garnet (Er,Cr:YSGG) Laser Irradiation on Bone Mineral and Organic Components.

PubMed

Benetti, Carolina; Ana, Patricia Aparecida; Bachmann, Luciano; Zezell, Denise Maria

2015-12-01

The effects of varying the energy density of a high-intensity erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser on the mineral and organic components of bone tissue were evaluated using Fourier transform infrared spectroscopy. Bone samples obtained from the tibias of rabbits were irradiated with five energy densities (3, 6, 8, 12, and 15 J/cm(2)), and the effects on the carbonate to phosphate ratio and in the organic components were compared with those of nonirradiated samples. The increased temperature during the laser irradiation was also measured using infrared thermography to relate the observed spectral changes to the laser thermal effects. The analyses of the infrared spectra suggests that the irradiation with Er,Cr:YSGG promoted changes in bone tissue in both the mineral and organic components that depend on the laser energy density, pointing to the importance of using the proper energy density in clinical procedures.

Simple Hydrogen Plasma Doping Process of Amorphous Indium Gallium Zinc Oxide-Based Phototransistors for Visible Light Detection.

PubMed

Kang, Byung Ha; Kim, Won-Gi; Chung, Jusung; Lee, Jin Hyeok; Kim, Hyun Jae

2018-02-28

A homojunction-structured amorphous indium gallium zinc oxide (a-IGZO) phototransistor that can detect visible light is reported. The key element of this technology is an absorption layer composed of hydrogen-doped a-IGZO. This absorption layer is fabricated by simple hydrogen plasma doping, and subgap states are induced by increasing the amount of hydrogen impurities. These subgap states, which lead to a higher number of photoexcited carriers and aggravate the instability under negative bias illumination stress, enabled the detection of a wide range of visible light (400-700 nm). The optimal condition of the hydrogen-doped absorption layer (HAL) is fabricated at a hydrogen partial pressure ratio of 2%. As a result, the optimized a-IGZO phototransistor with the HAL exhibits a high photoresponsivity of 1932.6 A/W, a photosensitivity of 3.85 × 10 6 , and a detectivity of 6.93 × 10 11 Jones under 635 nm light illumination.

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

DOEpatents

Hogan, Stephen J.

1986-01-01

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.

Luminescent down shifting effect of Ce-doped yttrium aluminum garnet thin films on solar cells

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

Shao, Guojian; Lou, Chaogang; Kang, Jian

2015-12-21

Ce-doped yttrium aluminum garnet (YAG:Ce) thin films as luminescent down shifting (LDS) materials are introduced into the module of crystalline silicon solar cells. The films are deposited by RF magnetron sputtering on the lower surface of the quartz glass. They convert ultraviolet and blue light into yellow light. Experiments show that the introduction of YAG:Ce films improves the conversion efficiency from 18.45% of the cells to 19.27% of the module. The increasing efficiency is attributed to LDS effect of YAG:Ce films and the reduced reflection of short wavelength photons. Two intentionally selected samples with similar reflectivities are used to evaluatemore » roughly the effect of LDS alone on the solar cells, which leads to a relative increase by 2.68% in the conversion efficiency.« less

An experimental study of the local electronic structure of B-site gallium doped bismuth ferrite powders

NASA Astrophysics Data System (ADS)

Gholam, Turghunjan; Ablat, Abduleziz; Mamat, Mamatrishat; Wu, Rong; Aimidula, Aimierding; Bake, Muhammad Ali; Zheng, Lirong; Wang, Jiaou; Qian, Haijie; Wu, Rui; Ibrahim, Kurash

2017-08-01

The un-doped and gallium (Ga) doped multiferroic bismuth ferrite (BiFeO3) compounds were successfully synthesized by the hydrothermal technique. This is then followed by a series of detailed investigations into the influence of Ga doping on the structural, morphological, optical and magnetic properties of BiFe1 - xGaxO3 (0 ≤ x ≤ 0.15). X-ray diffraction (XRD) analyses reveal that B-site doping of Ga may lead to the transformation of its crystal structure from a rhombohedral with a space group of R3c to an orthorhombic with a space group of Pbnm phase. The scanning electron microscope (SEM) images show that doping with Ga causes a significant reduction in particle size, when compared to un-doped BiFeO3. X-ray absorption near-edge structure (XANES) spectra have also shown that as the substitution of Ga increases, the Fe K and Bi LIII-edge absorption spectra shift towards higher energy site. It also implies that doping of Ga affects the local structures of both Bi and Fe atoms. Distinct transmission band fluctuations, as shown by Fourier transform infrared (FT-IR) spectra, can provide significant evidence for a transformation in crystal structure, following the increase of Ga concentration. The magnetization hysteresis measurements show that the magnetization decreases when Ga content is x ≥ 0.05. Such a phenomenon mainly stems from the substitution of Fe for an excessive amount of Ga, resulting in reduction of both valence fluctuations and the magnetization in the BiFe1 - xGaxO3 system.

Transparent garnet ceramic scintillators for gamma-ray detection

NASA Astrophysics Data System (ADS)

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

2012-10-01

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

Enhancement of the nonreciprocal magneto-optic effect of TM modes using iron garnet double layers with opposite Faraday rotation

NASA Astrophysics Data System (ADS)

Wallenhorst, M.; Niemöller, M.; Dötsch, H.; Hertel, P.; Gerhardt, R.; Gather, B.

1995-04-01

Garnet films of composition Lu3-xBixFe5-yGayO12 are grown by liquid-phase epitaxy on [111]-oriented substrates of gadolinium gallium garnet. Faraday rotation and saturation magnetization are measured as a function of substitution levels, which range up to x=1.4 and y=1.8, respectively. Nonreciprocal propagation of the TM0 is studied at a wavelength of 1.3 μm. It is shown that the difference between forward and backward propagation constants can be optimized using double layers with opposite sign of the Faraday rotation. Agreement between experiments and calculations is excellent.

Rare-Earth Doping and Co-Doping of GaN for Magnetic and Luminescent Applications

DTIC Science & Technology

2010-08-16

The main focus of this project is the study of Gadolinium doped Gallium Nitride. Calculations were carried out to elucidate the origin of the reported...Ga vacancies in the triple negative charge state, which is the most likely charge state in semi-insulating samples, 1. REPORT DATE (DD-MM-YYYY) 4...applications Report Title ABSTRACT The main focus of this project is the study of Gadolinium doped Gallium Nitride. Calculations were carried out to

Luminescence properties and electronic structure of Ce{sup 3+}-doped gadolinium aluminum garnet

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

Dotsenko, V.P., E-mail: ssclab@ukr.net; Berezovskaya, I.V.; Voloshinovskii, A.S.

2015-04-15

Highlights: • The luminescence properties of Ce{sup 3+} ions in (Y, Gd){sub 3}Al{sub 5}O{sub 12} are analyzed. • The Gd{sup 3+} → Y{sup 3+} substitution leads to increasing of Ce{sup 3+} noncubic crystal field splitting parameter. • The excitation spectra for the Ce{sup 3+} emission in GdAG contain bands at 6.67, 7.75, and 9.76 eV. • These features are due to the Ce{sup 3+}-bound exciton formation and O 2p → Al 3s, 3p transitions. • Contributions from Al atoms to the conduction-band density of states are quite essential. - Abstract: Yttrium-gadolinium aluminum garnets (YGdAG) doped with Ce{sup 3+} ions havemore » been prepared by co-precipitation method. The luminescent properties of Ce{sup 3+} ions in Gd{sub 3(1−x)}Ce{sub 3x}Al{sub 5}O{sub 12} (x = 0.01) have been studied upon excitation in the 2–20 eV region. The substitution of Gd{sup 3+} for Y{sup 3+} in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f → 5d excitation bands of Ce{sup 3+} ions, the excitation spectra for the Ce{sup 3+} emission contain bands at 6.67, 7.75, and 9.76 eV. These bands are attributed to the Ce{sup 3+}-bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. Although gadolinium states dominate near the bottom of the conduction band of Gd{sub 3}Al{sub 5}O{sub 12}, contributions from Al{sub tetr} and Al{sub oct} atoms to the conduction-band density of states are evaluated as quite essential.« less

Synergistic effect of indium and gallium co-doping on the properties of RF sputtered ZnO thin films

NASA Astrophysics Data System (ADS)

Shaheera, M.; Girija, K. G.; Kaur, Manmeet; Geetha, V.; Debnath, A. K.; Karri, Malvika; Thota, Manoj Kumar; Vatsa, R. K.; Muthe, K. P.; Gadkari, S. C.

2018-04-01

ZnO thin films were synthesized using RF magnetron sputtering, with simultaneous incorporation of Indium (In) and Gallium (Ga). The structural, optical, chemical composition and surface morphology of the pure and co-doped (IGZO) thin films were characterized by X-Ray diffraction (XRD), UV-visible spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Raman spectroscopy. XRD revealed that these films were oriented along c-axis with hexagonal wurtzite structure. The (002) diffraction peak in the co-doped sample was observed at 33.76° with a slight shift towards lower 2θ values as compared to pure ZnO. The surface morphology of the two thin films was observed to differ. For pure ZnO films, round grains were observed and for IGZO thin films round as well as rod type grains were observed. All thin films synthesized show excellent optical properties with more than 90% transmission in the visible region and band gap of the films is observed to decrease with co-doping. The co doping of In and Ga is therefore expected to provide a broad range optical and physical properties of ZnO thin films for a variety of optoelectronic applications.

Low-cost growth of magnesium doped gallium nitride thin films by sol-gel spin coating method

NASA Astrophysics Data System (ADS)

Amin, N. Mohd; Ng, S. S.

2018-01-01

Low-cost sol-gel spin coating growth of magnesium (Mg) doped gallium nitride (GaN) thin films with different concentrations of Mg was reported. The effects of the Mg concentration on the structural, surface morphology, elemental compositions, lattice vibrational, and electrical properties of the deposited films were investigated. X-ray diffraction results show that the Mg-doped samples have wurtzite structure with preferred orientation of GaN(002). The crystallite size decreases and the surface of the films with pits/pores were formed, while the crystalline quality of the films degraded as the Mg concentration increases from 2% to 6. %. All the Raman active phonon modes of the wurtzite GaN were observed while a broad peak attributed to the Mg-related lattice vibrational mode was detected at 669 cm-1. Hall effect results show that the resistivity of the thin films decreases while the hole concentration and hall mobility of thin films increases as the concentration of the Mg increases.

Scintillation properties of the Ce-doped multicomponent garnet epitaxial films

NASA Astrophysics Data System (ADS)

Prusa, P.; Kucera, M.; Mares, J. A.; Hanus, M.; Beitlerova, A.; Onderisinova, Z.; Nikl, M.

2013-10-01

(Lu,Y,Gd)3(Al,Ga)5O12:Ce garnet scintillator single crystalline films were grown onto LuAG, YAG and GGG substrates by liquid phase epitaxy method. Absorption, radioluminescence spectra and photoluminescence excitation, emission spectra, and decay kinetics were measured. Photoelectron yield, its dependence on amplifier shaping time and energy resolution were determined to evaluate scintillation performance. Most of the samples exhibited strong UV emission caused by trapped excitons and/or Gd3+ 4f-4f transition. However, emission spectrum of the best performing Gd2YAl5O12:Ce is dominated by the Ce3+ fast 5d-4f luminescence. This sample has outperformed photoelectron yield of all the garnet films studied so far.

Enhanced, robust light-driven H 2 generation by gallium-doped titania nanoparticles

DOE PAGES

Luo, Si; Nguyen-Phan, Thuy-Duong; Vovchok, Dimitriy; ...

2017-12-14

The splitting of water into molecular hydrogen and oxygen with the use of renewable solar energy is considered one of the most promising routes to yield sustainable fuel. In this paper, we report the H 2 evolution performance of gallium doped TiO 2 photocatalysts with varying degrees of Ga dopant. The gallium(III) ions induced significant changes in the structural, textural and electronic properties of TiO 2 nanoparticles, resulting in remarkably enhanced photocatalytic activity and good stability for H 2 production. Ga 3+ ions can act as hole traps that enable a large number of excited electrons to migrate towards themore » TiO 2 surface, thereby facilitating electron transfer and charge separation. Additionally, the cationic dopant and its induced defects might introduce a mid-gap state, promoting electron migration and prolonging the lifetime of charge carrier pairs. We have discovered that the optimal Ga dopant concentration was 3.125 at% and that the incorporation of platinum (0.5 wt%) as a co-catalyst further improved the H 2 evolution rate up to 5722 μmol g -1 h -1. Pt not only acts as an electron sink, drastically increasing the electron/hole pair lifetime, but it also creates an intimate contact at the heterojunction between Pt and Ga-TiO 2, thus improving the interfacial electron transfer process. Finally, these catalyst design strategies provide new ways of designing transition metal photocatalysts that improve green fuel production from renewable solar energy and water.« less

Potential use of gallium-doped phosphate-based glass material for periodontitis treatment.

PubMed

Sahdev, Rohan; Ansari, Tahera I; Higham, Susan M; Valappil, Sabeel P

2015-07-01

This study aimed at evaluating the potential effect of gallium-incorporated phosphate-based glasses towards periodontitis-associated bacteria, Porphyromonas gingivalis, and matrix metalloproteinase-13. Periodontitis describes a group of inflammatory diseases of the gingiva and supporting structures of the periodontium. They are initiated by the accumulation of plaque bacteria, such as the putative periodontal pathogen Porphyromonas gingivalis, but the host immune response such as elevated matrix metalloproteinases are the major contributing factor for destruction of periodontal tissues. Antibacterial assays of gallium-incorporated phosphate-based glasses were conducted on Porphyromonas gingivalis ATCC 33277 using disc diffusion assay on fastidious anaerobe agar and liquid broth assay in a modified tryptic soy broth. In vitro study investigated the effect of gallium on purified recombinant human matrix metalloproteinase-13 activity using matrix metalloproteinase assay kit. In vivo biocompatibility of gallium-incorporated phosphate-based glass was evaluated in rats as subcutaneous implants. Antibacterial assay of gallium displayed activity against Porphyromonas gingivalis (inhibition zone of 22 ± 0.5 mm compared with 0 mm for control glass, c-PBG). Gallium in the glass contributed to growth inhibitory effect on Porphyromonas gingivalis (up to 1.30 reductions in log 10 values of the viable counts compared with control) in a modified tryptic soy broth. In vitro study showed gallium-incorporated phosphate-based glasses inhibited matrix metalloproteinase activity significantly (p ≤ 0.01) compared with c-PBG. Evaluation of in vivo biocompatibility of gallium-incorporated phosphate-based glasses in rats showed a non-toxic and foreign body response after 2 weeks of implantation. The results indicate that gallium ions might act on multiple targets of biological mechanisms underlying periodontal disease. Moreover, gallium-incorporated phosphate-based glasses

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

NASA Astrophysics Data System (ADS)

Yadav, Satyesh K.; Uberuaga, Blas P.; Nikl, Martin; Jiang, Chao; Stanek, Christopher R.

2015-11-01

Complex doping schemes in R3 Al5 O12 (where R is the rare-earth element) garnet compounds have recently led to pronounced improvements in scintillator performance. Specifically, by admixing lutetium and yttrium aluminate garnets with gallium and gadolinium, the band gap is altered in a manner that facilitates the removal of deleterious electron trapping associated with cation antisite defects. Here, we expand upon this initial work to systematically investigate the effect of substitutional admixing on the energy levels of band edges. Density-functional theory and hybrid density-functional theory (HDFT) are used to survey potential admixing candidates that modify either the conduction-band minimum (CBM) or valence-band maximum (VBM). We consider two sets of compositions based on Lu3 B5O12 where B is Al, Ga, In, As, and Sb, and R3Al5 O12 , where R is Lu, Gd, Dy, and Er. We find that admixing with various R cations does not appreciably affect the band gap or band edges. In contrast, substituting Al with cations of dissimilar ionic radii has a profound impact on the band structure. We further show that certain dopants can be used to selectively modify only the CBM or the VBM. Specifically, Ga and In decrease the band gap by lowering the CBM, while As and Sb decrease the band gap by raising the VBM, the relative change in band gap is quantitatively validated by HDFT. These results demonstrate a powerful approach to quickly screen the impact of dopants on the electronic structure of scintillator compounds, identifying those dopants which alter the band edges in very specific ways to eliminate both electron and hole traps responsible for performance limitations. This approach should be broadly applicable for the optimization of electronic and optical performance for a wide range of compounds by tuning the VBM and CBM.

Synergistic effect of Indium and Gallium co-doping on growth behavior and physical properties of hydrothermally grown ZnO nanorods.

PubMed

Lim, Jun Hyung; Lee, Seung Muk; Kim, Hyun-Suk; Kim, Hyun You; Park, Jozeph; Jung, Seung-Boo; Park, Geun Chul; Kim, Jungho; Joo, Jinho

2017-02-03

We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In 3+ ) and smaller (Ga 3+ ) than the host Zn 2+ cations. Red shifts in the ultraviolet emission peaks were observed in all doped NRs, owing to the combined effects of NR size, band gap renormalization, and the presence of stacking faults created by the dopant-induced lattice distortions. In addition, the NR/p-GaN diodes using co-doped NRs exhibited superior electrical conductivity compared to the other specimens due to the increase in the charge carrier density of NRs and the relatively large effective contact area of (001) planes. The simultaneous doping of In and Ga is therefore anticipated to provide a broader range of optical, physical, and electrical properties of ZnO NRs for a variety of opto-electronic applications.

Synergistic effect of Indium and Gallium co-doping on growth behavior and physical properties of hydrothermally grown ZnO nanorods

NASA Astrophysics Data System (ADS)

Lim, Jun Hyung; Lee, Seung Muk; Kim, Hyun-Suk; Kim, Hyun You; Park, Jozeph; Jung, Seung-Boo; Park, Geun Chul; Kim, Jungho; Joo, Jinho

2017-02-01

We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In3+) and smaller (Ga3+) than the host Zn2+ cations. Red shifts in the ultraviolet emission peaks were observed in all doped NRs, owing to the combined effects of NR size, band gap renormalization, and the presence of stacking faults created by the dopant-induced lattice distortions. In addition, the NR/p-GaN diodes using co-doped NRs exhibited superior electrical conductivity compared to the other specimens due to the increase in the charge carrier density of NRs and the relatively large effective contact area of (001) planes. The simultaneous doping of In and Ga is therefore anticipated to provide a broader range of optical, physical, and electrical properties of ZnO NRs for a variety of opto-electronic applications.

Synergistic effect of Indium and Gallium co-doping on growth behavior and physical properties of hydrothermally grown ZnO nanorods

PubMed Central

Lim, Jun Hyung; Lee, Seung Muk; Kim, Hyun-Suk; Kim, Hyun You; Park, Jozeph; Jung, Seung-Boo; Park, Geun Chul; Kim, Jungho; Joo, Jinho

2017-01-01

We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In3+) and smaller (Ga3+) than the host Zn2+ cations. Red shifts in the ultraviolet emission peaks were observed in all doped NRs, owing to the combined effects of NR size, band gap renormalization, and the presence of stacking faults created by the dopant-induced lattice distortions. In addition, the NR/p-GaN diodes using co-doped NRs exhibited superior electrical conductivity compared to the other specimens due to the increase in the charge carrier density of NRs and the relatively large effective contact area of (001) planes. The simultaneous doping of In and Ga is therefore anticipated to provide a broader range of optical, physical, and electrical properties of ZnO NRs for a variety of opto-electronic applications. PMID:28155879

Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials

DOEpatents

Hogan, S.J.

1983-03-13

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

Solid-State Laser Cooling of Ytterbium-Doped Tungstate Crystals

DTIC Science & Technology

2001-01-01

namely the heavy metal fluoride glass ZBLAN and yttrium aluminum garnet . Favorable properties of the ytterbium-tungstates include exceptionally high...Optical refrigeration in Nd-doped yttrium aluminum garnet ,” Phys. Rev. Lett. 21, 1172 (1968). 2M.S. Chang, S.S. Elliott, T.K. Gustafson, C. Hu, and...idea gained experimental feasibility. Even with this tool, early failures to optically cool condensed media such as Nd3+ doped in yttrium aluminum

Application of reflectance confocal microscopy to evaluate skin damage after irradiation with an yttrium-scandium-gallium-garnet (YSGG) laser.

PubMed

Yue, Xueping; Wang, Hongwei; Li, Qing; Li, Linfeng

2017-02-01

The objective of this study was to observe the characteristics of the skin after irradiation with a 2790-nm yttrium-scandium-gallium-garnet (YSGG) laser using reflectance confocal microscopy (RCM). A 2790-nm YSGG laser was used to irradiate fresh foreskin (four doses, at spot density 3) in vitro. The characteristics of microscopic ablative columns (MAC), thermal coagulation zone (TCZ), and microscopic treatment zones (MTZ) were observed immediately after irradiation using digital microscope and RCM. The characteristics of MAC, TCZ, and MTZ with variations in pulse energy were comparatively analyzed. After irradiation, MAC, TCZ, and MTZ characteristics and undamaged skin between MTZs can be observed by RCM. The depth and width of MTZ obviously increased with the increase in pulse energy. At 80, 120, and 160 mJ/microbeam (MB), the MTZ actual area and proportion were about two times that of the theoretical value and three times at 200 mJ/MB. With increases in depth, the single MAC gradually decreased in a fingertip-shaped model, with TCZ slowly increasing, and MTZ slightly decreasing in a columnar shape. RCM was able to determine the characteristics of thermal injury on the skin after the 2790-nm YSGG laser irradiation with different pulse energies. Pulse energy higher than 200 mJ/MB may have much larger thermal injury and side effect. RCM could be used in the clinic in future.

Intrinsic and metal-doped gallium oxide based high-temperature oxygen sensors for combustion processes

NASA Astrophysics Data System (ADS)

Rubio, Ernesto Javier

Currently, there is enormous interest in research, development and optimization of the combustion processes for energy harvesting. Recent statistical and economic analyses estimated that by improving the coal-based firing/combustion processes in the power plants, savings up to $450-500 million yearly can be achieved. Advanced sensors and controls capable of withstanding extreme environments such as high temperatures, highly corrosive atmospheres, and high pressures are critical to such efficiency enhancement and cost savings. For instance, optimization of the combustion processes in power generation systems can be achieved by sensing, monitoring and control of oxygen, which is a measure of the completeness of the process and can lead to enhanced efficiency and reduced greenhouse gas emissions. However, despite the fact that there exists a very high demand for advanced sensors, the existing technologies suffer from poor 'response and recovery times' and 'long-term stability.' Motivated by the aforementioned technological challenges, the present work was focused on high-temperature (≥700 °C) oxygen sensors for application in power generation systems. The objective of the present work is to investigate nanostructured gallium oxide (2O3) based sensors for oxygen sensing, where we propose to conduct in-depth exploration of the role of refractory metal (tungsten, W, in this case) doping into 2O 3 to enhance the sensitivity, selectivity, stability ("3S" criteria) and reliability of such sensors while keeping cost economical. Tungsten (W) doped gallium oxide (2O3) thin films were deposited via rf-magnetron co-sputtering of W-metal and Ga2O3-ceramic targets. Films were produced by varying the sputtering power applied to the W-target in order to achieve variable W content into 2O3 films while substrate temperature was kept constant at 500 °C. Chemical composition, chemical valence states, microstructure and crystal structure of as-grown and post-annealed W-doped 2O3

Plasmon resonance and perfect light absorption in subwavelength trench arrays etched in gallium-doped zinc oxide film

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

Hendrickson, Joshua R., E-mail: joshua.hendrickson.4@us.af.mil; Leedy, Kevin; Cleary, Justin W.

Near-perfect light absorption in subwavelength trench arrays etched in highly conductive gallium-doped zinc oxide films was experimentally observed in the mid infrared regime. At wavelengths corresponding to the resonant excitation of surface plasmons, up to 99% of impinging light is efficiently trapped and absorbed in the periodic trenches. Scattering cross sectional calculations reveal that each individual trench acts like a vertical split ring resonator with a broad plasmon resonance spectrum. The coupling of these individual plasmon resonators in the grating structure leads to enhanced photon absorption and significant resonant spectral linewidth narrowing. Ellipsometry measurements taken before and after device fabricationmore » result in different permittivity values for the doped zinc oxide material, indicating that localized annealing occurred during the plasma etching process due to surface heating. Simulations, which incorporate a 50 nm annealed region at the zinc oxide surface, are in a good agreement with the experimental results.« less

Electrical properties of epitaxial yttrium iron garnet ultrathin films at high temperatures

NASA Astrophysics Data System (ADS)

Thiery, N.; Naletov, V. V.; Vila, L.; Marty, A.; Brenac, A.; Jacquot, J.-F.; de Loubens, G.; Viret, M.; Anane, A.; Cros, V.; Ben Youssef, J.; Beaulieu, N.; Demidov, V. E.; Divinskiy, B.; Demokritov, S. O.; Klein, O.

2018-02-01

We report a study on the electrical properties of 19-nm-thick yttrium iron garnet (YIG) films grown by liquid phase epitaxy on gadolinium gallium garnet single crystal. The electrical conductivity and Hall coefficient are measured in the high-temperature range [300,400] K using a Van der Pauw four-point probe technique. We find that the electrical resistivity decreases exponentially with increasing temperature following an activated behavior corresponding to a band gap of Eg≈2 eV. It drops to values about 5 ×103Ω cm at T =400 K, thus indicating that epitaxial YIG ultrathin films behave as large gap semiconductors. We also infer the Hall mobility, which is found to be positive (p type) at 5 cm2V-1sec-1 and almost independent of temperature. We discuss the consequence for nonlocal spin transport experiments performed on YIG at room temperature and demonstrate the existence of electrical offset voltages to be disentangled from pure spin effects.

On the photon annealing of silicon-implanted gallium-nitride layers

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

Seleznev, B. I., E-mail: Boris.Seleznev@novsu.ru; Moskalev, G. Ya.; Fedorov, D. G.

2016-06-15

The conditions for the formation of ion-doped layers in gallium nitride upon the incorporation of silicon ions followed by photon annealing in the presence of silicon dioxide and nitride coatings are analyzed. The conditions of the formation of ion-doped layers with a high degree of impurity activation are established. The temperature dependences of the surface concentration and mobility of charge carriers in ion-doped GaN layers annealed at different temperatures are studied.

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

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.

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

NASA Astrophysics Data System (ADS)

Aoki, Daichi; Shima, Mutsuhiro

2014-11-01

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.

A boron and gallium co-doped ZnO intermediate layer for ZnO/Si heterojunction diodes

NASA Astrophysics Data System (ADS)

Lu, Yuanxi; Huang, Jian; Li, Bing; Tang, Ke; Ma, Yuncheng; Cao, Meng; Wang, Lin; Wang, Linjun

2018-01-01

ZnO (Zinc oxide)/Si (Silicon) heterojunctions were prepared by depositing n-type ZnO films on p-type single crystal Si substrates using magnetron sputtering. A boron and gallium co-doped ZnO (BGZO) high conductivity intermediate layer was deposited between aurum (Au) electrodes and ZnO films. The influence of the BGZO layer on the properties of Au/ZnO contacts and the performance of ZnO/Si heterojunctions was investigated. The results show an improvement in contact resistance by introducing the BGZO layer. Compared with the ZnO/Si heterojunction, the BGZO/ZnO/Si heterojunction exhibits a larger forward current, a smaller turn-on voltage and higher ratio of ultraviolet (UV) photo current/dark current.

Optimization of Sm3+ fluorescence in Sm-doped yttrium aluminum garnet: Application to pressure calibration in diamond-anvil cell at high temperature

NASA Astrophysics Data System (ADS)

Sanchez-Valle, Carmen; Daniel, Isabelle; Reynard, Bruno; Abraham, Robert; Goutaudier, Christelle

2002-10-01

Sm3+ concentration in Sm-doped yttrium aluminum garnet (Sm3+):YAG has been optimized for fluorescence yield and synthesis procedure for the production of strain-free small grain-size powder established. Concentration of 0.5 wt % Sm3+ displays an optimal fluorescence signal, three to five times stronger than the generally proposed concentration (4 wt %). The fluorescence of the samples has been studied as a function of temperature (300-873 K) and pressure (0-15 GPa). A comparison with standard pressure scales shows that the pressure evolution of Sm3+:YAG fluorescence is insensitive to the doping rate, and that temperature has only a limited effect on the pressure scale established at 300 K. The present results indicate that pressure can be determined from the Y1 line of 0.5 wt % Sm-doped YAG, with temperature correction for pi at room pressure and constant pressure shift, within the 300-873 K and 10-4-15 GPa pressure-temperature range, through the linear relation: P (GPa)=0.127 x([pi0-0.018 xDelta]T)-[pi] where pi0 corresponds to the Y1 frequency value at ambient conditions (16 185 cm-1).

Contributions from gallium vacancies and carbon-related defects to the ``yellow luminescence'' in GaN

NASA Astrophysics Data System (ADS)

Armitage, R.; Hong, William; Yang, Qing; Feick, H.; Gebauer, J.; Weber, E. R.; Hautakangas, S.; Saarinen, K.

2003-05-01

Carbon-doped GaN layers grown by molecular-beam epitaxy are studied with photoluminescence and positron annihilation spectroscopy. Semi-insulating layers doped with >1018 cm-3 carbon show a strong luminescence band centered at ˜2.2 eV (yellow luminescence). The absolute intensity of the 2.2 eV band is compared with the gallium vacancy concentration determined by positron annihilation spectroscopy. The results indicate that a high concentration of gallium vacancies is not necessary for yellow luminescence and that there is in fact a causal relationship between carbon and the 2.2 eV band. Markedly different deep-level ionization energies are found for the high-temperature quenching of the 2.2 eV photoluminescence in carbon-doped and reference samples. We propose that while the model of Neugebauer and Van de Walle [Appl. Phys. Lett. 69, 503 (1996)] applies for GaN of low carbon concentration, a different yellow luminescence mechanism is involved when the interstitial carbon concentration is comparable to or exceeds the gallium vacancy concentration.

Synthesis and luminescent properties of Gd3Ga2Al3O12 phosphors doped with Eu3+ or Ce3+

NASA Astrophysics Data System (ADS)

Oh, M. J.; Kim, H. J.

2016-09-01

Eu3+-or Ce3+-doped gadolinium gallium aluminum garnet (GGAG), Gd3Ga2Al3O12, phosphors are fabricated using solid-state reactions with Gd2O3, Ga2O3, Al2O3, CeO2 and Eu2O3 powders. The Eu3+-or Ce3+-doped Gd3Ga2Al3O12 phosphors are sintered at 1300 °C or 1600 °C for 5 hours by using an electric furnace under normal atmosphere. X-ray diffraction and field-emission scanning electron microscopy studies are carried out in order to analyze the physical properties of these materials, and their luminescence properties are also measured by using UV and X-ray sources. The Eu3+-or Ce3+-doped Gd3Ga2Al3O12 phosphors show higher light yields in comparison to commercial phosphors such as Gd2O2S:Tb (gadox). This indicates that Gd3Ga2Al3O12:Eu3+ phosphors are promising materials for use in X-ray imaging and dose monitoring at proton beamlines.

Effect of the Pr3+ → Gd3+ energy transfer in multicomponent garnet single crystal scintillators

NASA Astrophysics Data System (ADS)

Babin, V.; Nikl, M.; Kamada, K.; Beitlerova, A.; Yoshikawa, A.

2013-09-01

Luminescence processes in the undoped and Pr3+-doped (Gd,RE)3(Ga,Al)5O12, RE = Lu,Y, multicomponent garnets are studied by time-resolved photoluminescence spectroscopy. Energy transfer processes between Pr3+ and Gd3+ causing significant deterioration of the scintillation performance are considered in detail. As is shown in current work, an overlap of the 5d1-3H4 emission transition of Pr3+ and 8S-6Px absorption transition of Gd3+ results in unwanted depletion of Pr3+ 5d1 excited state and is further intensified by the concentration quenching in the Gd3+-sublattice. This process explains a drastic decrease of light yield in Pr3+-doped Gd3+-containing multicomponent garnets observed in a previous work.

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2000-01-01

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.

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

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

Onbasli, M. C., E-mail: onbasli@mit.edu; Kim, D. H.; Ross, C. A.

2014-10-01

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 ofmore » the origins of novel magnetic phenomena and magnetization dynamics.« less

Effect of nitrogen doping on the structural, optical and electrical properties of indium tin oxide films prepared by magnetron sputtering for gallium nitride light emitting diodes

NASA Astrophysics Data System (ADS)

Tian, Lifei; Cheng, Guoan; Wang, Hougong; Wu, Yulong; Zheng, Ruiting; Ding, Peijun

2017-01-01

The indium tin oxide (ITO) films are prepared by the direct current magnetron sputtering technology with an ITO target in a mixture of argon and nitrogen gas at room temperature. The blue transmittance at 455 nm rises from 63% to 83% after nitrogen doping. The resistivity of the ITO film reduces from 4.6 × 10-3 (undoped film) to 5.7 × 10-4 Ω cm (N-doped film). The X-ray photoelectron spectroscopy data imply that the binding energy of the In3d5/2 peak is declined 0.05 eV after nitrogen doping. The high resolution transmission electron microscope images show that the nitrogen loss density of the GaN/ITO interface with N-doped ITO film is smaller than that of the GaN/ITO interface with undoped ITO film. The forward turn-on voltage of gallium nitride light emitting diode reduces by 0.5 V after nitrogen doping. The fabrication of the N-doped ITO film is conducive to modify the N component of the interface between GaN and ITO layer.

Homoepitaxial n-core: p-shell gallium nitride nanowires: HVPE overgrowth on MBE nanowires.

PubMed

Sanders, Aric; Blanchard, Paul; Bertness, Kris; Brubaker, Matthew; Dodson, Christopher; Harvey, Todd; Herrero, Andrew; Rourke, Devin; Schlager, John; Sanford, Norman; Chiaramonti, Ann N; Davydov, Albert; Motayed, Abhishek; Tsvetkov, Denis

2011-11-18

We present the homoepitaxial growth of p-type, magnesium doped gallium nitride shells by use of halide vapor phase epitaxy (HVPE) on n-type gallium nitride nanowires grown by plasma-assisted molecular beam epitaxy (MBE). Scanning electron microscopy shows clear dopant contrast between the core and shell of the nanowire. The growth of magnesium doped nanowire shells shows little or no effect on the lattice parameters of the underlying nanowires, as measured by x-ray diffraction (XRD). Photoluminescence measurements of the nanowires show the appearance of sub-bandgap features in the blue and the ultraviolet, indicating the presence of acceptors. Finally, electrical measurements confirm the presence of electrically active holes in the nanowires.

Optical properties and refractive indices of Gd3Al2Ga3O12:Ce3+ crystals

NASA Astrophysics Data System (ADS)

Kozlova, N. S.; Busanov, O. A.; Zabelina, E. V.; Kozlova, A. P.; Kasimova, V. M.

2016-05-01

Crystals of cerium-doped gadolinium-gallium-aluminum garnet have been grown by the Czochralski method. The transmission and reflection spectra of these crystals in the wavelength range of 250-800 nm have been obtained by optical spectroscopy. Refractive indices are calculated based on the measured Brewster angles, the experimental results are approximated using the Cauchy equation, and a dispersion dependence is obtained.

Band-gap and band-edge engineering of multicomponent garnet scintillators from first principles

DOE PAGES

Yadav, Satyesh K.; Uberuaga, Blas P.; Nikl, Martin; ...

2015-11-24

Complex doping schemes in R 3Al 5O 12 (where R is the rare-earth element) garnet compounds have recently led to pronounced improvements in scintillator performance. Specifically, by admixing lutetium and yttrium aluminate garnets with gallium and gadolinium, the band gap is altered in a manner that facilitates the removal of deleterious electron trapping associated with cation antisite defects. Here, we expand upon this initial work to systematically investigate the effect of substitutional admixing on the energy levels of band edges. Density-functional theory and hybrid density-functional theory (HDFT) are used to survey potential admixing candidates that modify either the conduction-band minimummore » (CBM) or valence-band maximum (VBM). We consider two sets of compositions based on Lu 3B 5O 12 where B is Al, Ga, In, As, and Sb, and R 3Al 5O 12, where R is Lu, Gd, Dy, and Er. We find that admixing with various R cations does not appreciably affect the band gap or band edges. In contrast, substituting Al with cations of dissimilar ionic radii has a profound impact on the band structure. We further show that certain dopants can be used to selectively modify only the CBM or the VBM. Specifically, Ga and In decrease the band gap by lowering the CBM, while As and Sb decrease the band gap by raising the VBM, the relative change in band gap is quantitatively validated by HDFT. These results demonstrate a powerful approach to quickly screen the impact of dopants on the electronic structure of scintillator compounds, identifying those dopants which alter the band edges in very specific ways to eliminate both electron and hole traps responsible for performance limitations. Furthermore, this approach should be broadly applicable for the optimization of electronic and optical performance for a wide range of compounds by tuning the VBM and CBM.« less

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

NASA Astrophysics Data System (ADS)

Koga, I.; Ogasawara, Y.

2012-12-01

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

Epitaxial gallium arsenide wafers

NASA Technical Reports Server (NTRS)

Black, J. F.; Robinson, L. B.

1971-01-01

The preparation of GaAs epitaxial layers by a vapor transport process using AsCl3, Ga and H2 was pursued to provide epitaxial wafers suitable for the fabrication of transferred electron oscillators and amplifiers operating in the subcritical region. Both n-n(+) structures, and n(++)-n-n(+) sandwich structures were grown using n(+) (Si-doped) GaAs substrates. Process variables such as the input AsCl3 concentration, gallium temperature, and substrate temperature and temperature gradient and their effects on properties are presented and discussed.

Identification of New Potential Scientific and Technology Areas for DoD Application. Summary of Activities

DTIC Science & Technology

1983-08-02

laser, a Cr3+-Nd 3 + gadolinium-scandium- gallium- garnet (GSGG) crystal, reputedly having three 15 times the slope efficiency of an equivalent... garnet , lithium gallium garnet , and lanthium-lutetium gallium garnet . Dr. Cooper asked for an indication of what it might take to put a program together in...Langmuir-Blodgett films , a subject mostly pursued in the U. K. Two groups, one at the University of California, San Diego (UCSD) (contact: Professor W

Rare-Earth Ion-Host Lattice Interactions: 15. Analysis of the Spectra of Nd3+ in Gd3Sc2Ga3O12.

DTIC Science & Technology

1984-05-01

Luminescence of Cr3+ Ions in Gadolinium Gallium and Gadolinium Scandium Gallium Garnet CT’stals, Soy. J. Quant. Electron. 12 (1982), 1124. 6M. Dutoit, J. C...Shcherbakov, Absolute Quantum Efficiency of the Luminescence of Cr3+ Ions in Gadolinium Gallium and Gadolinium Scandium Gallium Garnet Crystals, Soy. J...HDL Project: 324332 19. KEY WORDS (Continue on reverse side it necessary end Identify by block number) Rare earth Mixed garnet Spectra Laser Judd-Ofelt

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2006-01-01

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.

Positive hysteresis of Ce-doped GAGG scintillator

NASA Astrophysics Data System (ADS)

Yanagida, Takayuki; Fujimoto, Yutaka; Koshimizu, Masanori; Watanabe, Kenichi; Sato, Hiroki; Yagi, Hideki; Yanagitani, Takagimi

2014-10-01

Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 1% and 3% doped Gd3(Al, Ga)5O12 (Ce:GAGG) crystal scintillator on comparison with other garnet scintillators such Ce:YAG, Ce:LuAG, Pr:LuAG, and ceramic Ce:GAGG. When they were irradiated by several Gy 60Co γ-rays, Ce 1% doped GAGG crystal exhibited ∼20% light yield enhancement (positive hysteresis). This is the first time to observe positive hysteresis in Ce doped GAGG. On the other hand, other garnet materials did not show the positive hysteresis and their light yields were stable after 800 Gy irradiation except Pr:LuAG. The light yield of Pr:LuAG decreased largely. When irradiated Ce:GAGG which showed positive hysteresis was evaluated in Synchrotron facility (UVSOR), new excitation band was created around 60 nm.

Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications.

PubMed

Verma, Mahesh; Kumari, Pooja; Gupta, Rekha; Gill, Shubhra; Gupta, Ankur

2015-01-01

Erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser has been successfully used in the ablation of dental hard and soft tissues. It has been reported that this system is also useful for preparing tooth surfaces and etching, but no consensus exist in the literature regarding the advantage of lasers over conventional tooth preparation technique. Labial surfaces of 25 extracted human maxillary central incisors were divided into two halves. Right half was prepared with diamond bur and left half with Er, Cr; YSGG laser and a reduction of 0.3-0.5 mm was carried out. Topography of prepared surfaces of five teeth were examined under scanning electron microscope (SEM). The remaining samples were divided into 4 groups of 10 specimens each based on the surface treatment received: One group was acid etched and other was nonetched. Composite resin cylinders were bonded on prepared surfaces and shear bond strength was assessed using a universal testing machine. The SEM observation revealed that the laser prepared surfaces were clean, highly irregular and devoid of a smear layer. Bur prepared surfaces were relatively smooth but covered with smear layer. Highest bond strength was shown by laser prepared acid etched group, followed by bur prepared the acid etched group. The bur prepared nonacid etched group showed least bond strength. Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.

Coplanar amorphous-indium-gallium-zinc-oxide thin film transistor with He plasma treated heavily doped layer

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

Jeong, Ho-young; LG Display R and D Center, 245 Lg-ro, Wollong-myeon, Paju-si, Gyeonggi-do 413-811; Lee, Bok-young

We report thermally stable coplanar amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with heavily doped n{sup +} a-IGZO source/drain regions. Doping is through He plasma treatment in which the resistivity of the a-IGZO decreases from 2.98 Ω cm to 2.79 × 10{sup −3} Ω cm after treatment, and then it increases to 7.92 × 10{sup −2} Ω cm after annealing at 300 °C. From the analysis of X-ray photoelectron spectroscopy, the concentration of oxygen vacancies in He plasma treated n{sup +}a-IGZO does not change much after thermal annealing at 300 °C, indicating thermally stable n{sup +} a-IGZO, even for TFTs with channel length L = 4 μm. Field-effect mobility of the coplanar a-IGZO TFTsmore » with He plasma treatment changes from 10.7 to 9.2 cm{sup 2}/V s after annealing at 300 °C, but the performance of the a-IGZO TFT with Ar or H{sub 2} plasma treatment degrades significantly after 300 °C annealing.« less

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2012-01-01

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.

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2011-01-01

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.

Synthesis of crystalline Ce-activated garnet phosphor powders and technique to characterize their scintillation light yield

NASA Astrophysics Data System (ADS)

Gordienko, E.; Fedorov, A.; Radiuk, E.; Mechinsky, V.; Dosovitskiy, G.; Vashchenkova, E.; Kuznetsova, D.; Retivov, V.; Dosovitskiy, A.; Korjik, M.; Sandu, R.

2018-04-01

This work reports on a process of preparation of garnet phosphor powders and a technique for light yield evaluation of strongly light scattering samples. Powders of scintillation compounds could be used as individual materials or as samples for express tests of scintillation properties. However, estimation of their light yield (LY) is complicated by strong light scattering of this kind of materials. Ce3+-activated yttrium-aluminum and gallium-gadolinium-aluminum garnet phosphor powders, Y3Al5O12 (YAG:Ce) and Gd3Ga3Al2O12 (GGAG:Ce), were obtained using a modified coprecipitation technique. Ga tends to residue in mother liquor in ammonia media, but the modification allows to avoid the loss of components. We propose an approach for sample preparation and LY measurement setup with alpha particles excitation, allowing to decrease light scattering influence and to estimate a light yield of powder samples. This approach is used to evaluate the obtained powders.

Rare Earth Garnet Selective Emitter

NASA Technical Reports Server (NTRS)

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

1994-01-01

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.

Gallium

USGS Publications Warehouse

Foley, Nora K.; Jaskula, Brian W.; Kimball, Bryn E.; Schulte, Ruth F.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Gallium is a soft, silvery metallic element with an atomic number of 31 and the chemical symbol Ga. Gallium is used in a wide variety of products that have microelectronic components containing either gallium arsenide (GaAs) or gallium nitride (GaN). GaAs is able to change electricity directly into laser light and is used in the manufacture of optoelectronic devices (laser diodes, light-emitting diodes [LEDs], photo detectors, and solar cells), which are important for aerospace and telecommunications applications and industrial and medical equipment. GaAs is also used in the production of highly specialized integrated circuits, semiconductors, and transistors; these are necessary for defense applications and high-performance computers. For example, cell phones with advanced personal computer-like functionality (smartphones) use GaAs-rich semiconductor components. GaN is used principally in the manufacture of LEDs and laser diodes, power electronics, and radio-frequency electronics. Because GaN power transistors operate at higher voltages and with a higher power density than GaAs devices, the uses for advanced GaN-based products are expected to increase in the future. Gallium technologies also have large power-handling capabilities and are used for cable television transmission, commercial wireless infrastructure, power electronics, and satellites. Gallium is also used for such familiar applications as screen backlighting for computer notebooks, flat-screen televisions, and desktop computer monitors.Gallium is dispersed in small amounts in many minerals and rocks where it substitutes for elements of similar size and charge, such as aluminum and zinc. For example, gallium is found in small amounts (about 50 parts per million) in such aluminum-bearing minerals as diaspore-boehmite and gibbsite, which form bauxite deposits, and in the zinc-sulfide mineral sphalerite, which is found in many mineral deposits. At the present time, gallium metal is derived mainly as a

Timing capabilities of garnet crystals for detection of high energy charged particles

NASA Astrophysics Data System (ADS)

Lucchini, M. T.; Gundacker, S.; Lecoq, P.; Benaglia, A.; Nikl, M.; Kamada, K.; Yoshikawa, A.; Auffray, E.

2017-04-01

Particle detectors at future collider experiments will operate at high collision rates and thus will have to face high pile up and a harsh radiation environment. Precision timing capabilities can help in the reconstruction of physics events by mitigating pile up effects. In this context, radiation tolerant, scintillating crystals coupled to silicon photomultipliers (SiPMs) can provide a flexible and compact option for the implementation of a precision timing layer inside large particle detectors. In this paper, we compare the timing performance of aluminum garnet crystals (YAG: Ce, LuAG: Ce, GAGG: Ce) and the improvements of their time resolution by means of codoping with Mg2+ ions. The crystals were read out using SiPMs from Hamamatsu glued to the rear end of the scintillator and their timing performance was evaluated by measuring the coincidence time resolution (CTR) of 150 GeV charged pions traversing a pair of crystals. The influence of crystal properties, such as density, light yield and decay kinetics on the timing performance is discussed. The best single detector time resolutions are in the range of 23-30 ps (sigma) and only achieved by codoping the garnet crystals with divalent ions, such as Mg2+. The much faster scintillation decay in the co-doped samples as compared to non co-doped garnets explains the higher timing performance. Samples of LSO: Ce, Ca and LYSO:Ce crystals have also been used as reference time device and showed a time resolution at the level of 17 ps, in agreement with previous results.

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

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

2013-01-01

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

Evaluation of microtensile and tensile bond strength tests determining effects of erbium, chromium: yttrium-scandium-gallium-garnet laser pulse frequency on resin-enamel bonding.

PubMed

Yildirim, T; Ayar, M K; Yesilyurt, C; Kilic, S

2016-01-01

The aim of the present study was to compare two different bond strength test methods (tensile and microtensile) in investing the influence of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser pulse frequency on resin-enamel bonding. One-hundred and twenty-five bovine incisors were used in the present study. Two test methods were used: Tensile bond strength (TBS; n = 20) and micro-TBS (μTBS; n = 5). Those two groups were further split into three subgroups according to Er, Cr: YSGG laser frequency (20, 35, and 50 Hz). Following adhesive procedures, microhybrid composite was placed in a custom-made bonding jig for TBS testing and incrementally for μTBS testing. TBS and μTBS tests were carried out using a universal testing machine and a microtensile tester, respectively. Analysis of TBS results showed that means were not significantly different. For μTBS, the Laser-50 Hz group showed the highest bond strength (P < 0.05), and increasing frequency significantly increased bond strength (P < 0.05). Comparing the two tests, the μTBS results showed higher means and lower standard deviations. It was demonstrated that increasing μTBS pulse frequency significantly improved immediate bond strength while TBS showed no significant effect. It can, therefore, be concluded that test method may play a significant role in determining optimum laser parameters for resin bonding.

Effect of gallium environment on infrared emission in Er3+-doped gallium– antimony– sulfur glasses

PubMed Central

Jiao, Qing; Li, Ge; Li, Lini; Lin, Changgui; Wang, Guoxiang; Liu, Zijun; Dai, Shixun; Xu, Tiefeng; Zhang, Qinyuan

2017-01-01

Gallium-based Ga–Sb–S sulfide glasses was elaborated and studied. A relationship between the structure, composition, and optical properties of the glass has been established. The effects of the introduction of Ga on the structure using infrared and Raman spectroscopies and on the Er3+-doped IR emission have been discussed. The results show that incorporation of Ga induced the dissociation of [SbS3] pyramids units and the formation of tetrahedral [GaS4] units. The dissolved rare earth ions are separated around the Ga–S bonding and the infrared emission quenching are controlled. Moreover, continuous introduction of Er ions into the glass forms more Er–S bonds through the further aggregation surrounding the [GaS4] units. In return, the infrared emission intensity decreased with excessive Er ion addition. This phenomenon is correlated with the recurrence concentration quenching effect induced by the increase of [GaS4] units. PMID:28106143

Gallium hole traps in irradiated KTiOPO{sub 4}:Ga crystals

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

Grachev, V.; Meyer, M.; Malovichko, G.

2014-12-07

Nominally pure and gallium doped single crystals of potassium titanyl phosphate (KTiOPO{sub 4}) have been studied by Electron Paramagnetic Resonance at low temperatures before and after irradiation. Irradiation with 20 MeV electrons performed at room temperature and liquid nitrogen temperature caused an appearance of electrons and holes. Gallium impurities act as hole traps in KTiOPO{sub 4} creating Ga{sup 4+} centers. Two different Ga{sup 4+} centers were observed, Ga1 and Ga2. The Ga1 centers are dominant in Ga-doped samples. For the Ga1 center, a superhyperfine structure with one nucleus with nuclear spin ½ was registered and attributed to the interaction of galliummore » electrons with a phosphorus nucleus or proton in its surrounding. In both Ga1 and Ga2 centers, Ga{sup 4+} ions substitute for Ti{sup 4+} ions, but with a preference to one of two electrically distinct crystallographic positions (site selective substitution). The Ga doping eliminates one of the shortcomings of KTP crystals—ionic conductivity of bulk crystals. However, this does not improve significantly the resistance of the crystals to electron and γ-radiation.« less

The effect of sub-oxide phases on the transparency of tin-doped gallium oxide

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

Lim, K.; Schelhas, L. T.; Siah, S. C.

2016-10-03

There have been a number of studies on the fabrication of Sn-doped gallium oxide (Ga 2O 3:Sn) films with both conductive and transparent properties using a variety of deposition methods. However, often, synthesis results in films that are not transparent. In this paper, we examine the mechanisms underlying these results in Ga 2O 3:Sn thin films prepared at various growth temperatures, Sn concentrations, and oxygen partial pressures. With X-ray absorption spectroscopy, transmission electron microscopy and energy dispersive spectroscopy, we find that when films are grown under the oxygen deficient conditions there are Ga sub-oxide and SnOx phases in the Gamore » 2O 3:Sn thin film. These Ga sub-oxide phases are only found in non-transparent films, and so we infer that the Ga sub-oxide is responsible for the non-transparency. These observations suggest that to obtain transparent Ga 2O 3:Sn, films deposition or subsequent annealing must be carefully controlled in both temperature and oxygen partial pressure to avoid the formation of Ga sub-oxide phases.« less

New possibilities for Cr/sup 3 +/ ions as activators of the active media of solid-state lasers

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

Zharikov, E.V.; Lavrishchev, S.V.; Laptev, V.V.

An analysis is made of the relationship between the excited-state lifetime of chromium and the ratio of the luminescence intensities in the /sup 4/T/sub 2/--/sup 4/A/sub 2/ and /sup 2/E--/sup 4/A/sub 2/ channels, on one hand, and the Cr/sup 3 +/..-->..acceptor energy transfer efficiency, on the other. A method is proposed for determination of the energy gap ..delta..E between the /sup 2/E and /sup 4/T/sub 2/ levels of Cr/sup 3 +/ from the temperature dependence of the Cr/sup 3 +/..-->..acceptor nonradiative transfer efficiency. Two independent methods were used to determine ..delta..E for gadolinium gallium garnet (GGG) crystals doped with chromiummore » and with chromium and neodymium. The probabilities of Cr/sup 3 +/ intracenter relaxation and typical parameters of the Cr/sup 3 +/--Nd/sup 3 +/ energy transfer process were also determined. It was found that the values of ..delta..E in gadolinium scandium gallium (GdScGaG) and lanthanum lutetium gallium garnet crystals are comparable with the values of kT at liquid helium temperature. It is shown that the high efficiency of the Cr/sup 3 +/..-->..Nd/sup 3 +/ nonradiative transfer in GGG and GdScGaG crystals doped with chromium and neodymium at room temperature is due to the relatively low value of ..delta..E. It is noted that there are many crystals having the garnet structure and low values of ..delta..E that are potentially suitable for developing lasers utilizing the /sup 4/T/sub 2/--/sup 4/A/sub 2/ electronic--vibrational transition in Cr/sup 3 +/ and having an emission frequency continuously tunable over a wide spectral range.« less

Removal of Dental Implants Using the Erbium,Chromium:Yttrium-Scandium-Gallium-Garnet Laser and the Conventional Trephine Bur: An in Vitro Comparative Study.

PubMed

Hajji, Mohammad; Franzen, Rene; Grümer, Stefan; Modabber, Ali; Nasher, Riman; Prescher, Andreas; Gutknecht, Norbert

2016-02-01

The purpose of this study was to compare the conventional trephine bur and the Erbium,chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing implants in terms of the volume of removed bone, duration of the procedure, and morphological changes on the bone surface. Three human mandibles were utilized, and four implants were inserted in each mandible using a drilling handpiece and burs. The implants were divided into two groups (n = 6) in which two implants from each mandible were removed using a trephine bur running at 1200 rounds per minute (rpm) with water irrigation. The remaining implants (n = 6) were removed with Er,Cr:YSGG laser (power 6 W, frequency 20 Hz, pulse duration 50 μs, water 60, air 30). The volume of bone loss was calculated by filling the holes with mercury and measuring its volume. The preparation time was measured with a digital stopwatch and the postoperative bone surfaces were examined under a scanning electron microscope (SEM). The laser group exhibited a smaller amount of bone loss than the trephine bur group, whereas the latter required a shorter time of preparation. SEM revealed empty trabecular spaces with no signs of carbonization and well-defined edges in the laser group, whereas the trephine group displayed a surface covered with a smear layer and microcracks. The Er,Cr:YSGG laser provides superior results over the trephine bur in terms of bone preservation, thermal damage, and cutting efficiency.

Platinum nanoparticles on gallium nitride surfaces: effect of semiconductor doping on nanoparticle reactivity.

PubMed

Schäfer, Susanne; Wyrzgol, Sonja A; Caterino, Roberta; Jentys, Andreas; Schoell, Sebastian J; Hävecker, Michael; Knop-Gericke, Axel; Lercher, Johannes A; Sharp, Ian D; Stutzmann, Martin

2012-08-01

Platinum nanoparticles supported on n- and p-type gallium nitride (GaN) are investigated as novel hybrid systems for the electronic control of catalytic activity via electronic interactions with the semiconductor support. In situ oxidation and reduction were studied with high pressure photoemission spectroscopy. The experiments revealed that the underlying wide-band-gap semiconductor has a large influence on the chemical composition and oxygen affinity of supported nanoparticles under X-ray irradiation. For as-deposited Pt cuboctahedra supported on n-type GaN, a higher fraction of oxidized surface atoms was observed compared to cuboctahedral particles supported on p-type GaN. Under an oxygen atmosphere, immediate oxidation was recorded for nanoparticles on n-type GaN, whereas little oxidation was observed for nanoparticles on p-type GaN. Together, these results indicate that changes in the Pt chemical state under X-ray irradiation depend on the type of GaN doping. The strong interaction between the nanoparticles and the support is consistent with charge transfer of X-ray photogenerated free carriers at the semiconductor-nanoparticle interface and suggests that GaN is a promising wide-band-gap support material for photocatalysis and electronic control of catalysis.

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

NASA Astrophysics Data System (ADS)

Chandra Sekhar, M.; Singh, Mahi R.

2012-10-01

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

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2010-01-01

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.

Quantum Electronics in the UK. A National-Survey Conference.

DTIC Science & Technology

1985-10-30

flashlamp pumped chromium action, including transitions in dopants doped gadolinium /scandium/gallium garnet which have not previously shown laser lasers...frac- factors that limit performance. They ture. The Southampton scientists fabri - concluded that excited state absorption, cated the fibers by a...topics such as transverse power on the long wavelength side of a switching waves and cross-talk of bista- Fabry -Perot resonance peak at 844 nm, ble

Chapter L: U.S. Industrial Garnet

USGS Publications Warehouse

Evans, James G.; Moyle, Phillip R.

2006-01-01

The United States presently consumes about 16 percent of global production of industrial garnet for use in abrasive airblasting, abrasive coatings, filtration media, waterjet cutting, and grinding. As of 2005, domestic garnet production has decreased from a high of 74,000 t in 1998, and imports have increased to the extent that as much as 60 percent of the garnet used in the United States in 2003 was imported, mainly from India, China, and Australia; Canada joined the list of suppliers in 2005. The principal type of garnet used is almandite (almandine), because of its specific gravity and hardness; andradite is also extensively used, although it is not as hard or dense as almandite. Most industrial-grade garnet is obtained from gneiss, amphibolite, schist, skarn, and igneous rocks and from alluvium derived from weathering and erosion of these rocks. Garnet mines and occurrences are located in 21 States, but the only presently active (2006) mines are in northern Idaho (garnet placers; one mine), southeastern Montana (garnet placers; one mine), and eastern New York (unweathered bedrock; two mines). In Idaho, garnet is mined from Tertiary and (or) Quaternary sedimentary deposits adjacent to garnetiferous metapelites that are correlated with the Wallace Formation of the Proterozoic Belt Supergroup. In New York, garnet is mined from crystalline rocks of the Adirondack Mountains that are part of the Proterozoic Grenville province, and from the southern Taconic Range that is part of the northern Appalachian Mountains. In Montana, sources of garnet in placers include amphibolite, mica schist, and gneiss of Archean age and younger granite. Two mines that were active in the recent past in southwestern Montana produced garnet from gold dredge tailings and saprolite. In this report, we review the history of garnet mining and production and describe some garnet occurrences in most of the Eastern States along the Appalachian Mountains and in some of the Western States where

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

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

Shaposhnikov, A.N.; Karavainikov, A.V.; Prokopov, A.R.

2012-06-15

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{submore » 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°/μm for the visible optical spectrum).« less

Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

NASA Astrophysics Data System (ADS)

Kryshtal, R. G.; Medved, A. V.

2015-12-01

Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW - magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW - magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW - magnonic crystals are promising for signal processing in the GHz range.

Magneto-optical study of holmium iron garnet Ho3Fe5O12

NASA Astrophysics Data System (ADS)

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

2012-09-01

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 μm 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.

Significance of hydrous silicate lamellae in pyrope-rich garnets from the Garnet Ridge in the Colorado Plateau

NASA Astrophysics Data System (ADS)

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

2014-12-01

Pyrope-rich garnets originated from the upper mantle underneath the Colorado Plateau occur at the Garnet Ridge. These garnets contain the following lamellae of hydrous and anhydrous minerals; Rt, Ilm, crichtonites, Cr-Spl, Amp, Cpx, Chl, rarely Apt, srilankite and carmichealite. The origin of these lamellae in the garnets is controversial; exsolved origin or epitaxial growth. We emphasize here the close relations between the presence of hydrous lamellae and the OH concentrations in the host garnets. Lamella phases were identified with a standard-less quantitative EDS system and a laser Raman spectrometer with Ar+ laser (514.5 nm). OH concentrations in garnets were quantitated on the basis of IR absorption spectra of garnet by micro FT-IR method using IR absorption coefficient (8770 L/mol/cm2, Katayama et al., 2006). Pyrope-rich reddish brown garnet (group B by Sato et al., AGU2014F) has large variations of major chemical compositions (Prp: 49-76, Alm: 6-43, Grs: 6-26 mol%), and OH contents (2-177 ppm wt. H2O). Among this group garnets, Ca-rich ones (Prp: 49-66; Alm: 18-28; Grs: 16-26 mol%) have lamellae of both hydrous (Amp and Chl) and anhydrous (Rt, Ilm, and Cpx) minerals. Amp and Chl lamellae are pargasitic amphibole and clinochlore, respectively, and their host garnets contain significantly low amounts of OH (2-42 ppm). Cr and pyrope-rich garnet (group A by Sato et al., AGU2014F) has chemical compositions of Prp: 67-74, Alm: 13-18, Grs: 7-11 mol% with Cr2O3 up to 5.9 wt.%, and contains lamellae of anhydrous minerals (Rt, Ilm, crichtonites, and Cr-Spl). The host garnet with these anhydrous lamellae contains a little higher OH ranging 24 to 115 ppm. Summarizing the present results, the OH contents of the host garnets depend on the presence of hydrous silicate lamella phase; OH in the garnet with hydrous silicate lamellae is lower than that in the garnet with anhydrous lamellae. The precursor OH incorporated in the host garnet structure was exsolved as hydrous

Isoelectronic Traps in Gallium Phosphide

NASA Astrophysics Data System (ADS)

Christian, Theresa; Alberi, Kirstin; Beaton, Daniel; Fluegel, Brian; Mascarenhas, Angelo

2015-03-01

Isoelectronic substitutional dopants can result in strongly localized exciton traps within a host bandstructure such as gallium arsenide (GaAs) or gallium phosphide (GaP). These traps have received great attention for their role in the anomalous bandgap bowing of nitrogen or bismuth-doped GaAs, creating the dramatic bandgap tunability of these unusual dilute alloys. In the wider, indirect-bandgap host material GaP, these same isoelectronic dopants create bound states within the gap that can have very high radiative efficiency and a wealth of discrete spectral transitions illuminating the symmetry of the localized excitonic trap state. We will present a comparative study of nitrogen and bismuth isoelectronic traps in GaP. Research was supported by the U. S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division under contract DE-AC36-08GO28308 and by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under contract no. DE-AC05-06OR23100.

The effect of sub-oxide phases on the transparency of tin-doped gallium oxide

DOE PAGES

Lim, K.; Schelhas, L. T.; Siah, S. C.; ...

2016-10-07

There have been a number of studies on the fabrication of Sn-doped gallium oxide (Ga 2O 3:Sn) films with both conductive and transparent properties using a variety of deposition methods. However, often, synthesis results in films that are not transparent. In this paper, we examine the mechanisms underlying these results in Ga 2O 3:Sn thin films prepared at various growth temperatures, Sn concentrations, and oxygen partial pressures. With X-ray absorption spectroscopy, transmission electron microscopy and energy dispersive spectroscopy, we find that when films are grown under the oxygen deficient conditions there are Ga sub-oxide and SnO x phases in themore » Ga 2O 3:Sn thin film. These Ga sub-oxide phases are only found in non-transparent films, and so we infer that the Ga sub-oxide is responsible for the non-transparency. Furthermore, these observations suggest that to obtain transparent Ga 2O 3:Sn, films deposition or subsequent annealing must be carefully controlled in both temperature and oxygen partial pressure to avoid the formation of Ga sub-oxide phases.« less

IRAC test report. Gallium doped silicon band 2: Read noise and dark current

NASA Technical Reports Server (NTRS)

Lamb, Gerald; Shu, Peter; Mather, John; Ewin, Audrey; Bowser, Jeffrey

1987-01-01

A direct readout infrared detector array, a candidate for the Space Infrared Telescope Facility (SIRTF) Infrared Array Camera (IRAC), has been tested. The array has a detector surface of gallium doped silicon, bump bonded to a 58x62 pixel MOSFET multiplexer on a separate chip. Although this chip and system do not meet all the SIRTF requirements, the critically important read noise is within a factor of 3 of the requirement. Significant accomplishments of this study include: (1) development of a low noise correlated double sampling readout system with a readout noise of 127 to 164 electrons (based on the detector integrator capacitance of 0.1 pF); (2) measurement of the readout noise of the detector itself, ranging from 123 to 214 electrons with bias only (best to worst pixel), and 256 to 424 electrons with full clocking in normal operation at 5.4 K where dark current is small. Thirty percent smaller read noises are obtained at a temperature of 15K; (3) measurement of the detector response versus integration time, showing significant nonlinear behavior for large signals, well below the saturation level; and (4) development of a custom computer interface and suitable software for collection, analysis and display of data.

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

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

Chandra Sekhar, M.; Singh, Mahi R.

2012-10-15

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 weremore » 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.« less

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

NASA Astrophysics Data System (ADS)

Sato, Y.; Ogasawara, Y.

2013-12-01

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

Propagation of magnetostatic spin waves in an yttrium iron garnet film for out-of-plane magnetic fields

NASA Astrophysics Data System (ADS)

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Ketterson, John B.

2018-06-01

We have observed the propagation of spin waves across a thin yttrium iron garnet film on (1 1 1) gadolinium gallium garnet for magnetic fields inclined with respect to the film plane. Two principle planes were studied: that for H in the plane defined by the wave vector k and the plane normal, n, with limiting forms corresponding to the Backward Volume and Forward Volume modes, and that for H in the plane perpendicular to k, with limiting forms corresponding to the Damon-Eshbach and Forward Volume modes. By exciting the wave at one edge of the film and observing the field dependence of the phase of the received signal at the opposing edge we determined the frequency vs. wavevector relation, ω = ω (k), of various propagating modes in the film. Avoided crossings are observed in the Damon-Eshbach and Forward Volume regimes when the propagating mode intersects the higher, exchange split, volume modes, leading to an extinction of the propagating mode; analysis of the resulting behavior allows a determination of the exchange parameter. The experimental results are compared with theoretical simulations.

Gallium scan

MedlinePlus

... material called gallium and is a type of nuclear medicine exam. A related test is gallium scan ... Brown ML, Forstrom LA, et al. Society of nuclear medicine procedure guideline for gallium scintigraphy in inflammation. ...

Magnetic properties of epitaxial bismuth ferrite-garnet mono- and bilayers

NASA Astrophysics Data System (ADS)

Semuk, E. Yu.; Berzhansky, V. N.; Prokopov, A. R.; Shaposhnikov, A. N.; Karavainikov, A. V.; Salyuk, O. Yu.; Golub, V. O.

2015-11-01

Magnetic properties of Bi1.5Gd1.5Fe4.5Al0.5O12 (84 nm) and Bi2.8Y0.2Fe5O12 (180 nm) films epitaxially grown on gallium-gadolinium garnet (GGG) single crystal (111) substrate as well as Bi1.5Gd1.5Fe4.5Al0.5O12/Bi2.8Y0.2Fe5O12 bilayer were investigated using ferromagnetic resonance technique. The mismatch of the lattice parameters of substrate and magnetic layers leads to formation of adaptive layers which affect on the high order anisotropy constant of the films but practically do not affect on uniaxial perpendicular magnetic anisotropy The magnetic properties of the bilayer film were explained in supposition of strong exchange coupling between magnetic layers taking into account film-film and film-substrate elastic interaction.

Hydrous Na-garnet from Garnet Ridge; products of mantle metasomatism underneath the Colorado Plateau

NASA Astrophysics Data System (ADS)

Sakamaki, Kunihiko; Sato, Yuto; Ogasawara, Yoshihide

2016-12-01

This is the first report on amphibole exsolution in pyrope from the Colorado Plateau. Pyrope crystals delivered from mantle depths underneath the Colorado Plateau by kimberlitic volcanism at 30 Ma were collected at Garnet Ridge, northern Arizona. The garnet grains analyzed in this study occur as discrete crystals (without adjacent rock matrix) and are classified into two major groups, Cr-rich pyrope and Cr-poor pyrope. The Cr-poor pyrope group is divided into four subgroups based on exsolved phases: amphibole lamella type, ilmenite lamella type, dense lamellae type, and clinopyroxene/amphibole lamellae type. Exsolved amphibole occurs in amphibole lamella type, dense lamellae type, and clinopyroxene/amphibole lamellae type of Cr-poor pyrope. The amphibole crystals tend to have preferred orientations in their garnet hosts and occur as monomineralic hexagonal or rhombic prisms and tablets, and as multimineralic needles or blades with other exsolved phases. Exsolved amphibole has pargasitic compositions (Na2O up to 1.6 apfu based on 23 oxygen). Garnet host crystals that have undergone amphibole exsolution have low OH contents (2-42 ppmw H2O) compared to garnets that do not have amphibole lamellae (up to 115 ppmw H2O). The low OH contents of garnets hosting amphibole lamellae suggest loss of OH from garnet during amphibole exsolution. Amphibole exsolution from pyrope resulted from breakdown of a precursor "hydrous Na-garnet" composition (Mg,Na+ x)3(Al2 - x, Mgx)2Si3O12 - 2x(OH)2x. Exsolution of amphibole and other phases probably occurred during exhumation to depths shallower than 100 km prior to volcanic eruption.

Light-induced degradation in gallium-doped silicon

NASA Astrophysics Data System (ADS)

Lindroos, Jeanette; Yli-Koski, Marko; Haarahiltunen, Antti; Schubert, Martin C.; Savin, Hele

2012-02-01

Light-induced degradation (LID) is a lifetime-decreasing effect in silicon solar cells attributed to the formation of B-O defect complexes during illumination [1-2]. However, Savin et al. [3] have recently observed degradation similar to LID in B- and P-doped Si contaminated with Cu, suggesting that Cu might be the cause of LID. Since Ga-doped Si is considered a degradation-free option to conventional B-doped Si [2], lifetime stability should also be studied in Cu-contaminated Ga-Si. Hence, in this paper, we intentionally contaminated high-oxygen 0.41 and 10.1 φcm Ga-doped Cz-Si with Cu and subjected the material to illumination. No lifetime degradation was measured with μ-PCD in clean Ga-Si or at low Cu levels, which is in agreement with the previously reported LID-free behavior of Ga-Si [2]. However, at higher Cu levels (20 ppb), a clear lifetime degradation was observed in Ga-Si. This lifetime degradation increased with increasing Cu concentration or with increasing wafer resistivity. [1] J. Schmidt, A.G. Aberle and R. Hezel, 26th IEEE PVSC, Anaheim, CA, USA, p.13-18 (1997). [2] S.W. Glunz, S. Rein, W. Warta, J. Knobloch and W. Wettling. Sol. Energ. Mat. Sol. C. 65, 219-229 (2001). [3] H. Savin, M. Yli-Koski and A. Haarahiltunen. Appl. Phys. Lett. 95, 152111 (2009).

Measuring Nanoscale Heat Transfer for Gold-(Gallium Oxide)-Gallium Nitride Interfaces as a Function

NASA Astrophysics Data System (ADS)

Szwejkowski, Chester; Sun, Kai; Constantin, Costel; Giri, Ashutosh; Saltonstall, Christopher; Hopkins, Patrick; NanoSynCh Team; Exsite Team

2014-03-01

Gallium nitride (GaN) is considered the most important semiconductor after the discovery of Silicon. Understanding the properties of GaN is imperative in determining the utility and applicability of this class of materials to devices. We present results of time domain thermoreflectance (TDTR) measurements as a function of surface root mean square (RMS) roughness. We used commercially available 5mm x 5mm, single-side polished GaN (3-7 μm)/Sapphire (430 μm) substrates that have a Wurtzite crystal structure and are slightly n-type doped. The GaN substrates were annealed in the open atmosphere for 10 minutes (900-1000 °C). This high-temperature treatment produced RMS values from 1-60 nm and growth of gallium oxide (GaO) as measured with an atomic force microscopy and transmission electron microscopy respectively. A gold film (80nm) was deposited on the GaN surface using electron beam physical vapor deposition which was verified using ellipsometry and profilometry. The TDTR measurements suggest that the thermal conductivity decays exponentially with RMS roughness and that there is a minimum value for thermal boundary conductance at a roughness of 15nm.

Computational discovery of lanthanide doped and Co-doped Y{sub 3}Al{sub 5}O{sub 12} for optoelectronic applications

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

Choudhary, Kamal; Chernatynskiy, Aleksandr; Phillpot, Simon R.

2015-09-14

We systematically elucidate the optoelectronic properties of rare-earth doped and Ce co-doped yttrium aluminum garnet (YAG) using hybrid exchange-correlation functional based density functional theory. The predicted optical transitions agree with the experimental observations for single doped Ce:YAG, Pr:YAG, and co-doped Er,Ce:YAG. We find that co-doping of Ce-doped YAG with any lanthanide except Eu and Lu lowers the transition energies; we attribute this behavior to the lanthanide-induced change in bonding environment of the dopant atoms. Furthermore, we find infrared transitions only in case of the Er, Tb, and Tm co-doped Ce:YAG and suggest Tm,Ce:YAG and Tb,Ce:YAG as possible functional materials formore » efficient spectral up-conversion devices.« less

Luminescence and luminescence quenching in Gd3(Ga,Al)5O12 scintillators doped with Ce3+.

PubMed

Ogiegło, Joanna M; Katelnikovas, Arturas; Zych, Aleksander; Jüstel, Thomas; Meijerink, Andries; Ronda, Cees R

2013-03-28

The optical properties of gadolinium gallium aluminum garnet, Gd3(Ga,Al)5O12, doped with Ce(3+) are investigated as a function of the Ga/Al ratio, aimed at an improved understanding of the energy flow and luminescence quenching in these materials. A decrease of both the crystal field strength and band gap with increasing content of Ga(3+) is observed and explained by the geometrical influence of Ga(3+) on the crystal field splitting of the 5d level in line with theoretical work of Muñoz-García et al. ( uñoz-García, A. B.; Seijo, L. Phys. Rev. B 2010, 82, 184118 ). Thermal quenching results in shorter decay times as well as reduced emission intensities for all samples in the temperature range from 100 to 500 K. An activation energy for emission quenching is calculated from the data. The band gap of the host is measured upon Ga substitution and the decrease in band gap is related to Ga(3+) substitution into tetrahedral sites after all octahedral sites are occupied in the garnet material. Based on the change in band gap and crystal field splitting, band diagrams can be constructed explaining the low thermal quenching temperatures in the samples with high Ga content. The highest luminescence intensity is found for Gd3(Ga,Al)5O12 with 40% of Al(3+) replaced by Ga(3+).

Composition engineering of single crystalline films based on the multicomponent garnet compounds

NASA Astrophysics Data System (ADS)

Zorenko, Yuriy; Gorbenko, Vitalii; Zorenko, Tetiana; Paprocki, Kazimierz; Bilski, Paweł; Twardak, Anna; Voznyak, Taras; Sidletskiy, Oleg; Gerasimov, Yaroslav; Gryniov, Boris; Fedorov, Alexandr

2016-11-01

The paper demonstrates our last achievement in development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped multicomponent garnets using the Liquid Phase Epitaxy (LPE) method. We report in this work the optimized content and excellent scintillation properties of SCF of Lu3-xGdxAl5-yGayO12, Lu3-xTbxAl5-yGayO12 and TbxGdxAl5-yGayO12 garnet compounds grown by the LPE method from PbOsbnd B2O3 based melt-solution onto Gd3Al2.5Ga2.5O12 and YAG substrates. We also show that the Tb1.5Gd1.5Al2.5Ga2.5O12:Ce SCF possess the highest light yield (LY) in comparison with all ever grown garnet SCF scintillators. Namely, the LY of these SCF exceeds by 3.8 and 1.85 times the LY values of the best samples of YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCF samples of the mentioned compounds show low thermoluminescence in the above room temperature range and relatively fast scintillation decay time t1/e in the 180-200 ns range.

Research in LPE of Doped LiNbO3 and LiTaO3 Thin Films.

DTIC Science & Technology

1981-06-01

garnet films grown on single crystal garnet substrates by the LPE technique for magnetic bubble applica- tions. The choice of substrate and film are...AD-Al07 686 ROCKWELL INTERNATIONAL THOUSAND OAKS CA ELECTRONICS -EUTC F/G 2RESEARCH IN LPE OF DOPED LINBO3 AND LITA03 THIN FILMS .(U JUN Al R R NEUR...Research in LPE of Doped LiNbO3 and LiTa03 Final Report Thin Films 04/01/77 through 03/31/81 6. PERFORMING ORG. REPORT NUM9ER ERC41004.11FR 7. AUTNOR

Investigation of Magnetostatic Surface Waves for Anisotropic Effects.

DTIC Science & Technology

1986-06-01

inves- tigate the effect of launching magnetostatic surface waves at different angles on a yttrium-iron- garnet (YIG) single crystal film . Many...propagation indeed could be achieved on a YIG thin film ring grown on a gadolinium-gallium- garnet (GGG) substrate (Sethares, 1975) (see Figure 1.1). The use of...thin films grown on a gadolinium-gallium- garnet substrate. The films were 27

Raman spectroscopy of garnet-group minerals

USGS Publications Warehouse

Mingsheng, P.; Mao, Ho-kwang; Dien, L.; Chao, E.C.T.

1994-01-01

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

Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses

NASA Astrophysics Data System (ADS)

Dubs, Carsten; Surzhenko, Oleksii; Linke, Ralf; Danilewsky, Andreas; Brückner, Uwe; Dellith, Jan

2017-05-01

Using a liquid phase epitaxy (LPE) technique (1 1 1) yttrium iron garnet (YIG) films with thicknesses of  ≈100 nm and surface roughnesses as low as 0.3 nm have been grown on (1 1 1) gadolinium gallium garnet (GGG) substrates as a basic material for spin-wave propagation experiments in microstructured waveguides. The continuously strained films exhibit nearly perfect crystallinity without significant mosaicity and with effective lattice misfits of Δ {{a}\\bot}/{{a}s}≈ {{10}-4} and below. The film/substrate interface is extremely sharp without broad interdiffusion layer formation. All LPE films exhibit a nearly bulk-like saturation magnetization of (1800+/- 20 ) Gs and an ‘easy cone’ anisotropy type with extremely small in-plane coercive fields  <0.2 Oe. There is a rather weak in-plane magnetic anisotropy with a pronounced six-fold symmetry observed for the saturation field  <1.5 Oe. No significant out-of-plane anisotropy is observed, but a weak dependence of the effective magnetization on the lattice misfit is detected. The narrowest ferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is the lowest value reported so far for YIG films of 100 nm thicknesses and below. The Gilbert damping coefficient for investigated LPE films is estimated to be close to 1× {{10}-4} .

Revised calibration of the Sm:SrB{sub 4}O{sub 7} pressure sensor using the Sm-doped yttrium-aluminum garnet primary pressure scale

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

Rashchenko, Sergey V., E-mail: rashchenko@igm.nsc.ru; Litasov, Konstantin D.; Novosibirsk State University, 630090 Novosibirsk

2015-04-14

The pressure-induced shift of Sm:SrB{sub 4}O{sub 7} fluorescence was calibrated in a quasi-hydrostatic helium medium up to 60 GPa using the recent Sm-doped yttrium-aluminum garnet primary pressure scale as a reference. The resulting calibration can be written as P = −2836/14.3 [(1 + Δλ/685.51){sup −14.3 }− 1]. Previous calibrations based on the internally inconsistent primary scales are revised, and, after appropriate correction, found to agree with the proposed one. The calibration extended to 120 GPa was also performed using corrected previous data and can be written as P = 4.20 Δλ (1 + 0.020 Δλ)/(1 + 0.036 Δλ)

Clinical and Histopathologic Assessment of Facial Melasma After Low-Fluence Q-Switched Neodymium-Doped Yttrium Aluminium Garnet Laser.

PubMed

Hofbauer Parra, Camila Anna; Careta, Mariana Figueroa; Valente, Neusa Yuriko Sakai; de Sanches Osório, Nuno Eduardo Guimaraes; Torezan, Luis Antonio Ribeiro

2016-04-01

Melasma is a frequent and difficult to treat skin disorder. Results of laser therapy are inconsistent. To determine the safety and efficacy of low-fluence Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser for melasma treatment and assess recurrence rates and histopathologic findings before and after treatment. Twenty patients were treated with 10 weekly sessions of low-fluence 1064-nm QS Nd:YAG laser at 1-week intervals. The modified Melasma Area and Severity Index (mMASI) score was evaluated at baseline; 1 week; and 1, 3, and 6 months after treatment. Epidermal melanin quantification was performed on 10 biopsy samples and compared before and after treatment. All patients showed improvement by mMASI scores, range (21%-75%) compared with that at baseline. No permanent side effects occurred. The recurrence rate was 81%. By histopathology, a slight, nonsignificant (p = .305) decrease in melanin deposition was seen in all layers of the epidermis 1 week after the laser treatments ended. The results confirm the safety and effectiveness of low-fluence QS Nd:YAG laser for treating melasma; however, the high recurrence suggests poor long-term results when the laser is used as a monotherapy.

Rare Earth Doped High Temperature Ceramic Selective Emitters

NASA Technical Reports Server (NTRS)

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

1999-01-01

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 develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

Petrogenetic evolution of the Mesoproterozoic garnet-bearing granitoids of Dumka, Eastern India: Implication of garnet and biotite composition

NASA Astrophysics Data System (ADS)

Roy, P.; Goswami, B.; Ghosal, A.; Nanda, J.; Basak, A.; Bhattacharyya, C.

2017-12-01

Garnet is a petrologically significant accessory mineral of igneous rocks. Granite, tonalite, charnoenderbite and enderbite are prominent facies of 1450 Ma old Dumka Granitoids, Jharkhand district, India. Interestingly all the facies of Dumka granitoids contain good amount of garnet and biotite. Sphene, magnetite, ilmenite, zircon, monazite, allanite and rare hornblende present as accessory minerals. The garnets are mainly solid solutions between almandine, pyrope and grossular. Garnets contain 70.5-75.8 mol% of the almandine, 12.8-17.5 mol% of pyrope, 8-11 mol% of grossular and 0.6-2.9 mol% of spessartine. Composition of garnets fit well in the compositional range of igneous garnets suggested by Miller and Stoddard (1981). High MgO and CaO contents together with very low MnO of these garnets suggest that these have been crystallized from granitoid magma under high pressure in the lower crust. No compositional zoning is found in the analyzed garnets. Biotites of the granitoids are rich in Mg [Mg/(Fe+Mg) ratio > 0.4]. Biotites plot in Abdel-Rahman's (1994) field for biotites of calc-alkaline granites. The matrix biotites in these granitoids have higher Ti content than biotites coexist with garnets. Biotites coexisting with garnet are richer in Mg/Fe ratio than matrix biotites. Mg/Fe distribution coefficients between garnet core and matrix biotite (KD= (Mg/Fe)grt/(Mg/Fe)bt) for the Dumka enderbite and tonalite are 0.275 to 0.280 while for the granites the KD varies from 0.189 to 0.264. These KD values are higher than the values obtained from high-grade metamorphic rocks and are consistent with the values of igneous granitoids as shown by Lyons and Morse (1970). Absence of zoning in magmatic garnets in Dumka Granitoids indicate that these have crystallized above 700 °C, whereas absence of "spessartine bell-shaped profile" of the garnets of present study refute their metamorphic origin or that these crystallized below 700 °C (Dahlquist et al., 2007). Geothermobaric

Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) Nanorods Superlattice (SL)

DTIC Science & Technology

2006-03-29

Final Report (Technical) 3. DATES COVERED 29-03-2005 to 29-05-2006 4. TITLE AND SUBTITLE Indium Gallium Nitride/ Gallium Nitride (InGaN/GaN...Institution: Quantum functional Semiconductor Research Center (QSRC), Dongguk University - Title of project: Indium Gallium Nitride/ Gallium Nitride...Accepted with minor revision Indium Gallium Nitride / Gallium Nitride (InGaN/ GaN) Nanorods Superlattice (SL) Abstract The growth condition, electrical

Epitaxial Garnets and Hexagonal Ferrites.

DTIC Science & Technology

1980-02-28

shaped LPE garnet samples with 31.5um film thickness. We were informed that initial evalu- ation showed acceptably low insertion loss and that the material...frequencies above 25 GHz. c. Furnish up to eight (8) liquid phase epitaxy yttrium iron garnet films to RADC/EEA for testing and evaluation. These tasks...a "Method for Controlling Resonance Frequency of Yttrium Iron Garnet Films ." A patent, "Epitaxial Growth of M-type Hexagonal Ferrite Films on Spinel

Dramatic impact of the giant local magnetic fields on spin-dependent recombination processes in gadolinium based garnets

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

Romanov, N. G., E-mail: nikolai.romanov@mail.ioffe.ru; Tolmachev, D. O.; Gurin, A. S.

2015-06-29

A giant magnetic field effect on spin-dependent recombination of the radiation-induced defects has been found in cerium doped gadolinium based garnet crystals and ceramics, promising materials for scintillator applications. A sharp and strong increase in the afterglow intensity stimulated by external magnetic field and an evidence of the magnetic field memory have been discovered. The effect was ascribed to huge Gd-induced internal magnetic fields, which suppress the recombination, and cross-relaxation with Gd{sup 3+} ions leading to reorientation of the spins of the electron and hole centers. Thus, the spin system of radiation-induced defects in gadolinium garnet based scintillator materials wasmore » shown to accumulate significant energy which can be released in external magnetic fields.« less

Mineral resource of the month: garnet

USGS Publications Warehouse

Olson, Donald W.

2011-01-01

Garnet, the birthstone for the month of January, has been used as a gemstone for centuries. Garnet necklaces dating from the Bronze Age have been found in graves, and garnet is found among the ornaments adorning the oldest Egyptian mummies. However, garnet’s characteristics, such as its relatively high hardness and chemical inertness, make it ideal for many industrial applications.

Longitudinal spin Seebeck effect in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} prepared on gadolinium gallium garnet (001) by metal organic decomposition method

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

Asada, H., E-mail: asada@yamaguchi-u.ac.jp; Kuwahara, A.; Sakata, N.

2015-05-07

Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films with the Ga composition x = 0, 0.5, and 1.0 are prepared on (001) oriented gadolinium gallium garnet substrates by a metal organic decomposition method. Only (001) peaks are observed in x-ray diffraction patterns for all the films, suggesting that the highly oriented Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films were formed. Increasing Ga composition, the saturation magnetization decreases, and the perpendicular easy axis is enhanced due to the decrease of the shape anisotropy. Longitudinal spin Seebeck effects (LSSEs) in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films with a Pt layer of 10 nm in thicknessmore » were investigated. Magnetic field dependence of the thermoelectric voltage caused by the LSSE in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} films indicates the hysteresis loop with the small coercivity reflecting the magnetization curve. The decrease of LSSE voltage in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} is clearly observed with the decrease of Fe composition.« less

Experimental Studies of Lateral Electron Transport in Gallium Arsenide-Aluminum Gallium Arsenide Heterostructures.

DTIC Science & Technology

1982-12-01

AD-A125 858 EXPERIMENTAL STUDIES OF LATERAL ELECTRON TRANSPORT IN 1/3 GALLIUM ARSENIDE-RL..(U) ILLINOIS UNIV AT URBANA COORDINATED SCIENCE LAB N R...EXPERIMENTAL STUDIES OF LATERALXILECTRON TRANSPORT ,:g IN GALLIUM ARSENIDE -ALUMINUM GALLIUM ARSENIDE- -HETEROSTRUCTURES APRVE O PUBLICRLEAS.DSRBUINULMTE. 2...EXPERIMENTAL STUDIES OF LATERAL ELECTRON TRANSPORT IN GALLIUM ARSENIDE-ALUMINUM GALLIUM ARSENIDE Technical Report R-975 HETEROSTRUCTURES 6. PERFORMING ONG

Tunable Microwave Transversal Filters.

DTIC Science & Technology

1984-05-01

magnetostatic waves MSW propagating at microwave frequency in magnetically biased, liquid phase epitaxial films of yttrium iron garnet (YIG) grown on...25 uM-thick 3 mm-wide and 15 mm-long YIG film grown by liquid phase epitaxy On a 500 uM-thick ( ) gadolinium gallium garnet (GGG) substrate was used...obtained. The delay line material was prepared by growing YIG films on one inch diameter gallium gadolinium garnet (GGG) wafers using the liquid

Gallium interstitial in irradiated germanium: Deep level transient spectroscopy

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

Kolkovsky, Vl.; Petersen, M. Christian; Larsen, A. Nylandsted

Two electronic levels at 0.34 eV above the valence band and 0.32 eV below the conduction band, in gallium doped, p-type Ge irradiated with 2 MeV electrons have been studied by deep level transient spectroscopy (DLTS) with both majority- and minority-carrier injections, and Laplace DLTS spectroscopy. It is concluded that these levels, having donor and acceptor characters, respectively, are correlated with interstitial Ga atoms, formed by the Watkins-replacement mechanism via self-interstitials.

Gallium interstitial in irradiated germanium: Deep level transient spectroscopy

NASA Astrophysics Data System (ADS)

Kolkovsky, Vl.; Petersen, M. Christian; Mesli, A.; van Gheluwe, J.; Clauws, P.; Larsen, A. Nylandsted

2008-12-01

Two electronic levels at 0.34 eV above the valence band and 0.32 eV below the conduction band, in gallium doped, p -type Ge irradiated with 2 MeV electrons have been studied by deep level transient spectroscopy (DLTS) with both majority- and minority-carrier injections, and Laplace DLTS spectroscopy. It is concluded that these levels, having donor and acceptor characters, respectively, are correlated with interstitial Ga atoms, formed by the Watkins-replacement mechanism via self-interstitials.

Using Garnet to Reconstruct Subduction Zone Dehydration Flux

NASA Astrophysics Data System (ADS)

Baxter, E. F.; Dragovic, B.; Samanta, L. M.; Selverstone, J.; Caddick, M. J.

2011-12-01

Coupled geodynamic-thermodynamic models make predictions about the progressive dehydration flux from subducted lithologies. However, it has been difficult to test or confirm these predictions through direct petrologic assessment of natural systems. We have developed a method that may be used to reconstruct the rate, timing, and flux of dehydration from diverse lithologies within subduction zones. Here, we summarize the fundamentals of the method and highlight data from two blueschist facies lithologies from the island of Sifnos, Greece. The data indicate that garnet growth and related dehydration from individual lithologies can be focused into relatively brief (100,000s of years) pulses. In general, most garnet forming reactions (in initially hydrous lithologies) also involve the consumption of hydrous minerals (including chlorite, biotite, chloritoid, amphibole, epidote, lawsonite) and the consequent liberation of water. Depending on the exact reaction and on the pressure and temperature vector over which the reaction occurs, the stoichiometric (i.e. molar) ratio between garnet produced and water produced can vary. If this stoichiometry can be constrained via thermodynamic and textural reaction analysis, then garnet may be used as a direct monitor of the progressive dehydration of the rock for the P-T-t span over which garnet grew. To a first order, rocks with greater modal proportion of garnet have released greater amounts of water. Modern techniques are available to directly date the span of garnet growth from single crystals larger than about 5mm diameter. Sm-Nd geochronology of chemically contoured microsampled prograde garnet growth zones from single crystals can produce constraints on garnet growth duration at better than 1 million year resolution. Integration of zoned garnet geochronology and thermodynamic reaction analysis permits reconstruction of the dehydration rate and duration from individual samples. Recent studies of contrasting lithologies on

Presumed Multiple Metasomatism underneath the Colorado Plateau; Decoding from Chemistry and Inclusion/Lamella Mineralogy of Diverse Garnets from the Garnet Ridge, Northern Arizona

NASA Astrophysics Data System (ADS)

Sato, Y.; Ogasawara, Y.

2015-12-01

Various garnets containing the information on mantle petrology and related metasomatism occur at the Garnet Ridge, Colorado Plateau. The origins of garnets range from deep mantle to shallow continental crust. These garnets were delivered by kimberlitic diatreme of 30 Ma (Smith et al. 2004). We have classified the garnets into 10 groups (A to J, see figure) by naked eye observation, major chemistry, minor Na-Ti-P, inclusion/lamella mineralogy. Among them, groups A to D are of mantle origin, E to G of subducted oceanic crust origin, and H to J of continental crust origin. We summarized results as in the followings. A: Cr and pyrope-rich garnet has Cr2O3(0.8-6.3 wt.%) and inclusions of Ol, Cpx, Opx, Ti-Chu/Chn and carbonates, indicating carbonated garnet lherzolites as host. Cr contents negatively correlates with Na-Ti-P contents and occurrence of exsolved Rt, Ilm and crichtonite. This indicates Cr-rich end-member is the most "primitive" mantle garnet before metasomatism. B: Pyrope-rich reddish brown garnet of peridotitic origins was subdivided into 4 subgroups (B1 to B4, see figure). Compositional range in Ca-Mg-Fe triangle expands to Fe-rich side from group A. Exsolved Na-bearing amphibole and inclusions of Ap, carbonates and fluid were identified. These indicate metasomatism of group A. C: Garnet megacryst is coarse-grained garnet (2-10 cm across) with crystal faces. This garnet has wide chemical variation plotted in the center area of Ca-Mg-Fe triangle. D: Garnet aggregate has similar chemistry of group C and is composed of several grains. Grain boundaries of garnet were recognized by Rt, Ilm and other minerals and oscillatory zonings of Ca, Mg, Fe and Na-Ti-P. Fluid inclusions of groups C and D suggest these garnets might crystalized from fluid. E: Garnet in eclogite and F: Garnet in metasomatized eclogite are xenolith samples (the Fallaron Plate origin?). Aggregate of Zo+Ab contained in group E indicates decomposed precursor lawsonite inclusion. G: Quartz

Gallium-Doped Poly-Si:Ga/SiO 2 Passivated Emitters to n-Cz Wafers With iV oc >730 mV

DOE PAGES

Young, David L.; Lee, Benjamin G.; Fogel, Derek; ...

2017-09-26

Here, we form gallium-doped poly-Si:Ga/SiO 2 passivated contacts on n-type Czochralski (n-Cz) wafers using ion implantation of Ga and Ga-containing spin-on dopants. After annealing and passivation with Al 2O 3, the contacts exhibit i Voc values of >730 mV with corresponding Joe values of <5 fA/cm 2. These are among the best-reported values for p-type poly-Si/SiO 2 contacts. Secondary ion mass spectroscopic depth profile data show that, in contrast to B, Ga does not pileup at the SiO 2 interface in agreement with its known high diffusivity in SiO 2. This lack of Ga pileup may imply fewer dopant-related defectsmore » in the SiO 2, compared with B dopants, and account for the excellent passivation.« less

Laser and thermal properties of Nd:YGd2Sc2Al2GaO12 garnet ceramic Laser and thermal properties of Nd:YSGG garnet ceramic

NASA Astrophysics Data System (ADS)

Brenier, A.; Alombert-Goget, G.; Guyot, Y.; Boulon, G.

2012-10-01

The absorption and fluorescence properties of the Nd-doped YGd2Sc2Al2GaO12 mixed garnet ceramics have been measured at different temperatures. Under laser diode pumping an efficient laser emission has been demonstrated with 45% slope efficiency. The emission is constituted by two lines at 1058.6 and 1061.3 nm, subjected to a red shift and a variable relative intensity versus pump power. The role of the temperature has been investigated playing with the cavity parameters. The thermal conductivity of the 1% Nd-doped material has been determined (3.2 W/m/K) measuring the radial temperature distribution of the exit face of the sample including the axial heat flow in the analysis. The M2 beam quality factor and the dioptric power of the thermal lens have been investigated versus the pump power. The thermo-optic coefficient χ was determined as 44.4×10-6 K-1.

Picosecond 532-nm neodymium-doped yttrium aluminium garnet laser-a novel and promising modality for the treatment of café-au-lait macules.

PubMed

Artzi, Ofir; Mehrabi, Joseph N; Koren, Amir; Niv, Roni; Lapidoth, Moshe; Levi, Assi

2018-05-01

Café-au-lait macules (CALMs) present as benign hyperpigmented, well-circumscribed spots on the skin for which many patients seek treatment for aesthetic reasons. The objective of this study is to report our experience in treating CALMs using a picosecond 532-nm neodymium-doped yttrium aluminium garnet (PS 532 nm) laser. This is a retrospective case series of 16 patients with CALMs who were treated by a PS 532-nm laser (1-4 treatments, 4-8 weeks apart). Response as seen on clinical photographs was assessed by two independent dermatologists and graded on a scale of 0 (exacerbation) to 5 (95-100% improvement). Patient satisfaction and tolerance were documented at final visit. The results of 15 patients demonstrated significant improvement (average 3.43), and their satisfaction and tolerance levels were high. One patient had no response whatsoever to treatment. The PS 532-nm laser is a promising novel modality for the treatment of CALMs.

Gallium nitride optoelectronic devices

NASA Technical Reports Server (NTRS)

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

1972-01-01

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.

Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

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

Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel

This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of themore » phenomenon is demonstrated.« less

Long-Pulsed 532-Nm Neodymium-Doped Yttrium Aluminium Garnet Laser for Treatment of Facial Plane Warts in 160 Yemeni Patients.

PubMed

Alshami, Mohammad Ali; Mohana, Mona Jameel; Alshami, Ahlam Mohammad

2016-11-01

Warts in general and plane warts in particular pose a therapeutic challenge for dermatologists. Many treatment modalities exist, with variable success rates, side effect profiles, and precautions. The long-pulsed 532-nm neodymium-doped yttrium aluminium garnet (LP Nd:YAG) laser has not been previously used for this indication. This study was conducted to assess the efficacy and safety of the LP Nd:YAG laser for treating facial plane warts. A total of 160 Yemeni patients (62 women, 98 men; age range, 5-55 years) were exposed to 1 laser treatment session with the following parameters: wavelength, 532 nm; pulse duration, 20 millisecond; spot size, 2 to 3 mm; and fluence, 25 J/cm. The end point was graying or whitening of the lesion. Color photographs were taken before and immediately after treatment and at follow-up visits 1, 4, and 16 weeks after the laser session. An overall clearance rate of 92% after only one session was achieved, with minimal and transient side effects. The LP Nd:YAG laser is safe and effective for treating facial plane warts, with a success rate of 92% after only one session.

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

NASA Astrophysics Data System (ADS)

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

2000-05-01

We have studied the energetics of trace element incorporation into pure almandine (Alm), grossular (Gros), pyrope (Py) and spessartine (Spes) garnets (X 3Al 2Si 3O 12, with X = Fe, Ca, Mg, Mn respectively), by means of computer simulations of perfect and defective lattices in the static limit. The simulations use a consistent set of interatomic potentials to describe the non-Coulombic interactions between the ions, and take explicit account of lattice relaxation associated with trace element incorporation. The calculated relaxation (strain) energies Urel are compared to those obtained using the Brice (1975) model of lattice relaxation, and the results compared to experimental garnet-melt trace element partitioning data interpreted using the same model. Simulated Urel associated with a wide range of homovalent (Ni, Mg, Co, Fe, Mn, Ca, Eu, Sr, Ba) and charge-compensated heterovalent (Sc, Lu, Yb, Ho, Gd, Eu, Nd, La, Li, Na, K, Rb) substitutions onto the garnet X-sites show a near-parabolic dependence on trace element radius, in agreement with the Brice model. From application of the Brice model we derived apparent X-site Young's moduli EX(1+, 2+, 3+) and the 'ideal' ionic radii r0(1+, 2+, 3+), corresponding to the minima in plots of Urel vs. radius. For both homovalent and heterovalent substitutions r0 increases in the order Py-Alm-Spes-Gros, consistent with crystallographic data on the size of garnet X-sites and with the results of garnet-melt partitioning studies. Each end-member also shows a marked increase in both the apparent EX and r0 with increasing trace element charge ( Zc). The increase in EX is consistent with values obtained by fitting to the Brice model of experimental garnet-melt partitioning data. However, the increase in r0 with increasing Zc is contrary to experimental observation. To estimate the influence of melt on the energetics of trace element incorporation, solution energies ( Usol) were calculated for appropriate exchange reactions between

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

NASA Technical Reports Server (NTRS)

Spangler, Lee H.

1994-01-01

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

Comparison of the efficacy of different types of lasers for the treatment of peri-implantitis: a systematic review.

PubMed

Natto, Zuhair S; Aladmawy, Majdi; Levi, Paul A; Wang, Hom-Lay

2015-01-01

To evaluate the efficacy of various types of lasers (neodymium-doped yttrium-aluminum-garnet [Nd:YAG], carbon dioxide [CO2], diode, erbium/chromium-doped yttrium-scandium-gallium-garnet [Er,Cr:YSGG], and erbium-doped yttrium-aluminum-garnet [Er:YAG]) in the treatment of peri-implantitis and their use in surgical and nonsurgical procedures. Human studies for the treatment of peri-implantitis with laser therapy, published between 2002 and January 2014, were collected utilizing the electronic databases PubMed, Ovid, MEDLINE, Cochrane, and Google Scholar. Two reviewers conducted the study selection, data collection, and validity assessment. Eight hundred twelve studies were selected in the initial title search; 13 studies were then chosen for this review. No human studies evaluated the effect of the Nd:YAG laser on peri-implantitis. The CO2 laser is reported to be safe and able to enhance bone regeneration. The diode laser (980 nm) seems to be effective in its bactericidal effect without changing the implant surface pattern. The Er,Cr:YSGG laser was reported to obtain bone regeneration around a failing implant in one case, while the Er:YAG laser exhibits a strong bactericidal effect against periodontopathic bacteria at a low energy level. Although lasers have shown promising results in reducing clinical signs of peri-implantitis, because of the limited sample sizes and short follow-up periods, no firm conclusion can be drawn at this moment. Hence, there is a need for more well-designed, longitudinal, randomized controlled clinical trials.

Swift heavy ion-beam induced amorphization and recrystallization of yttrium iron garnet.

PubMed

Costantini, Jean-Marc; Miro, Sandrine; Beuneu, François; Toulemonde, Marcel

2015-12-16

Pure and (Ca and Si)-substituted yttrium iron garnet (Y3Fe5O12 or YIG) epitaxial layers and amorphous films on gadolinium gallium garnet (Gd3Ga5O12, or GGG) single crystal substrates were irradiated by 50 MeV (32)Si and 50 MeV (or 60 MeV) (63)Cu ions for electronic stopping powers larger than the threshold value (~4 MeV μm(-1)) for amorphous track formation in YIG crystals. Conductivity data of crystalline samples in a broad ion fluence range (10(11)-10(16) cm(-2)) are modeled with a set of rate equations corresponding to the amorphization and recrystallization induced in ion tracks by electronic excitations. The data for amorphous layers confirm that a recrystallization process takes place above ~10(14) cm(-2). Cross sections for both processes deduced from this analysis are discussed in comparison to previous determinations with reference to the inelastic thermal-spike model of track formation. Micro-Raman spectroscopy was also used to follow the related structural modifications. Raman spectra show the progressive vanishing and randomization of crystal phonon modes in relation to the ion-induced damage. For crystalline samples irradiated at high fluences (⩾10(14) cm(-2)), only two prominent broad bands remain like for amorphous films, thereby reflecting the phonon density of states of the disordered solid, regardless of samples and irradiation conditions. The main band peaked at ~660 cm(-1) is assigned to vibration modes of randomized bonds in tetrahedral (FeO4) units.

Gallium--A smart metal

USGS Publications Warehouse

Foley, Nora; Jaskula, Brian W.

2013-01-01

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.

Diode-pumped mode-locked femtosecond Tm:CLNGG disordered crystal laser.

PubMed

Ma, J; Xie, G Q; Gao, W L; Yuan, P; Qian, L J; Yu, H H; Zhang, H J; Wang, J Y

2012-04-15

A diode-end-pumped passively mode-locked femtosecond Tm-doped calcium lithium niobium gallium garnet (Tm:CLNGG) disordered crystal laser was demonstrated for the first time to our knowledge. With a 790 nm laser diode pumping, stable CW mode-locking operation was obtained by using a semiconductor saturable absorber mirror. The disordered crystal laser generated mode-locked pulses as short as 479 fs, with an average output power of 288 mW, and repetition rate of 99 MHz in 2 μm spectral region. © 2012 Optical Society of America

Fractional erbium-doped yttrium aluminum garnet laser-assisted drug delivery of hydroquinone in the treatment of melasma

PubMed Central

Badawi, Ashraf M; Osman, Mai Abdelraouf

2018-01-01

Background Melasma is a difficult-to-treat hyperpigmentary disorder. Ablative fractional laser (AFL)-assisted delivery of topically applied drugs to varied targets in the skin has been an area of ongoing study and research. Objective The objective of this study was to evaluate the efficacy and safety of fractional erbium-doped yttrium aluminum garnet (Er:YAG) laser as an assisted drug delivery for enhancing topical hydroquinone (HQ) permeation into the skin of melasma patients. Patients and methods Thirty female patients with bilateral melasma were randomly treated in a split-face controlled manner with a fractional Er:YAG laser followed by 4% HQ cream on one side and 4% HQ cream alone on the other side. All patients received six laser sessions with a 2-week interval. The efficacy of treatments was determined through photographs, dermoscopic photomicrographs and Melasma Area Severity Index (MASI) score, all performed at baseline and at 12 weeks of starting therapy. The patient’s level of satisfaction was also recorded. Results Er:YAG laser + HQ showed significantly better results (p<0.005) with regard to decrease in the degree of pigmentation as assessed on the 4-point scale than HQ alone. There was a significant decrease in MASI scores on Er:YAG laser + HQ side vs HQ side. Minor reversible side effects were observed on both sides. Conclusion AFL-assisted delivery of HQ is a safe and effective method for the treatment of melasma. PMID:29379308

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass.

PubMed

Emmer, Hal; Chen, Christopher T; Saive, Rebecca; Friedrich, Dennis; Horie, Yu; Arbabi, Amir; Faraon, Andrei; Atwater, Harry A

2017-07-05

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF 2 vapor etch. The resulting GaP films have surface roughnesses below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10 17  cm -3 that exhibited mobilities as high as 16 cm 2 V -1 s -1 . Due to their unique optical properties, these films hold much promise for use in advanced optical devices.

Gallium-containing anticancer compounds.

PubMed

Chitambar, Christopher R

2012-06-01

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 crossresistance 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.

Paramagnetic Ce3 + optical emitters in garnets: Optically detected magnetic resonance study and evidence of Gd-Ce cross-relaxation effects

NASA Astrophysics Data System (ADS)

Tolmachev, D. O.; Gurin, A. S.; Uspenskaya, Yu. A.; Asatryan, G. R.; Badalyan, A. G.; Romanov, N. G.; Petrosyan, A. G.; Baranov, P. G.; Wieczorek, H.; Ronda, C.

2017-06-01

Paramagnetic Ce3 +optical emitters have been studied by means of optically detected magnetic resonance (ODMR) via Ce3 + spin-dependent emission in cerium-doped garnet crystals which were both gadolinium free and contain gadolinium in a concentration from the lowest (0.1%) to 100%, i.e., to the superparamagnetic state. It has been shown that the intensity of photoluminescence excited by circularly polarized light into Ce3 + absorption bands can be used for selective monitoring the population of the Ce3 + ground-state spin sublevels. Direct evidence of the cross-relaxation effects in garnet crystals containing two electron spin systems, i.e., the simplest one of Ce3 + ions with the effective spin S =1/2 and the system of Gd3 + ions with the maximum spin S =7/2 , has been demonstrated. Magnetic resonance of Gd3 + has been found by monitoring Ce3 + emission in cerium-doped garnet crystals with gadolinium concentrations of 0.1 at. %, 4%-8%, and 100%, which implies the impact of the Gd3 + spin polarization on the optical properties of Ce3 +. Strong internal magnetic fields in superparamagnetic crystals were shown to modify the processes of recombination between UV-radiation-induced electron and hole centers that lead to the recombination-induced Ce3 + emission. Observation of spikes and subsequent decay in the cross-relaxation-induced ODMR signals under pulsed microwave excitation is suggested to be an informative method to investigate transient processes in the many-spin system of Ce3 +, Gd3 +, and electron and hole radiation-induced centers.

DFT study on the adsorption of diethyl, ethyl methyl, and dimethyl ethers on the surface of gallium doped graphene

NASA Astrophysics Data System (ADS)

Shokuhi Rad, Ali; Sani, Emad; Binaeian, Ehsan; Peyravi, Majid; Jahanshahi, Mohsen

2017-04-01

In this study, we used density functional theory (DFT) to search on the adsorption properties of three important compounds of ether family; diethyl ether (DEE), ethyl methyl ether (EME), and dimethyl ether (DME) on the surface of Gallium doped graphene (GaG). We used three functionals (B3LYP, wb97xd, and MPW1PW91) for optimization and calculation of adsorption energy. After fully optimization, we scrutinized on the charge allocations on the adsorbed ethers as well as GaG (at the area of interaction) based on natural bond orbitals (NBO). Besides, we have calculated the amount of charge transfer upon adsorption of each analyte. We revel that GaG is an ideal adsorbent for chemisorption of all above-mentioned ethers. There is a little difference between the values of adsorption; -123.5, -120, and -118.3 kJ/mol (based on wb97xd) for DEE, EME, and DME, respectively. We found significant changes in the electronic structure of both adsorbent and adsorbate upon adsorption. Moreover, results of charge analyses confirm GaG is a p-type semiconductor.

Scintillation properties of Pr 3+-doped lutetium and yttrium aluminum garnets: Comparison with Ce 3+-doped ones

NASA Astrophysics Data System (ADS)

Mares, Jiri A.; Nikl, Martin; Beitlerova, Alena; Blazek, Karel; Horodysky, Petr; Nejezchleb, Karel; D'Ambrosio, Carmelo

2011-12-01

Scintillation properties of Pr 3+-doped LuAG and YAG crystals were investigated and compared with those of Ce 3+-doped ones. The highest L.Y.'s were observed with the longest shaping time 10 μs. They can reach up to ˜16,000 ph/MeV or ˜23,500 ph/MeV for LuAG:Pr and LuAG:Ce, respectively. Energy resolutions (FWHM) are a bit better with LuAG:Pr than those of LuAG:Ce, e.g. at 662 keV FWHM are around 6% and between 8-12%, respectively. There were observed no large changes in proportionality of Pr 3+- or Ce 3+-doped LuAG or YAG crystals but the best proportionality has YAP:Ce crystal. Pr 3+- or Ce 3+-doped LuAG crystals exhibit slow decay components in the time range 1.5-3.5 μs while those of YAG ones have shorter decay components between 0.3-1.7 μs.

New method for revealing dislocations in garnet: premelting decoration

NASA Astrophysics Data System (ADS)

Liu, Xiangwen; Xie, Zhanjun; Jin, Zhenmin; Li, Zhuoyue; Ao, Ping; Wu, Yikun

2018-05-01

Premelting decoration (PMD) of dislocation experiments was carried out on garnets at 1 atmosphere pressure and temperatures of 800-1000 °C. Numerous decorated lines were observed on the polished surface of heat-treated garnet grains. The results of scanning electron microscopy, laser Raman spectroscopy and transmission electron microscopy (TEM) analyses indicate that these decorated lines were generated by premelting reaction along the dislocation lines and subgrain boundaries. The constituents of decorated lines on the polished surface of garnet are hematite, magnetite, and melt. While, in the interior of garnet, their constituents changed to Al-bearing magnetite and melt. The dislocation density of a gem-quality megacrystal garnet grain by means of the PMD is similar to that obtained by TEM, which confirms that the PMD is a new reliable method for revealing dislocations in garnet. This method greatly reduces the cost and time involved in the observation of dislocation microstructures in deformed garnet.

Cathodoluminescence on the Effects of Te Implantation and Laser Annealing in Gallium Arsenide.

DTIC Science & Technology

1978-12-01

With the intentional addition of impurity ions (doping) into the lattice of a crystal , the semiconductor gallium arse- nide (GaAs ) should have... lattice structure with respect to Te ion positions and the presence of native defects. The experimental technique of cathodoluminescence is used to...the band—gap are caused by excitons , impurity atoms , or lattice imperfections. The first transition in Figure 1 is the recombination of a free

Gallium-containing anticancer compounds

PubMed Central

Chitambar, Christopher R

2013-01-01

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

A detrital garnet fingerprint of the Central Swiss Alps

NASA Astrophysics Data System (ADS)

Stutenbecker, Laura; Berger, Alfons; Schlunegger, Fritz

2017-04-01

Detrital garnet is a promising candidate to reliably fingerprint sediment sources in the Alps, which has so far been complicated by the wide range and similarity of some of the lithologies. Garnet is present in most Alpine sediments, is easy to identify, is fairly stable and, most importantly, reflects the type and the metamorphic grade of its source rock in its chemical composition. This study aims to establish fingerprints based on detrital garnet composition for the most important tectonic units of the Central Alps, including European, Penninic and Adriatic basement rocks and their respective meta-sedimentary cover. Sediments collected from modern rivers, which drain representative portions of the individual tectonic units, contain a natural mixture of the various garnet populations present in each unit. We selected six catchments in southwestern Switzerland draining the External Massifs, Helvetic sediments and the Penninic nappe stack at the transition of Alpine greenschist- to amphibolite-facies metamorphism in order to test the variability of Alpine garnets and the role of inherited (pre-Alpine) garnets. Extraordinary grossular- and spessartine-rich garnets of the External massifs, which experienced greenschist facies metamorphism, are clearly distinguishable from generally almandine-rich garnets supplied by the higher-grade metamorphic Penninic nappe stack. The variable pyrope-, grossular- and spessartine-components of these almandine-rich garnets can be used to further distinguish pre-Alpine, Alpine eclogite-facies and low-grade metasedimentary garnets. This fingerprint has the potential to be used for reconstructing sediment sources, transport and dispersal patterns in a variety of settings throughout the Alpine sedimentary record.

Electric Field Tunable Microwave and MM-wave Ferrite Devices

DTIC Science & Technology

2010-04-30

xm thick YIG film grown by liquid-phase epitaxy on a (111) gadolinium gallium garnet was used. A PZT plate with the dimensions 4x1x0.5 mm3 was...of width ~ 150 micron and length 20 mm. An YIG film , 6 u.m thick, 0.5 mm in width and 2.5 mm long, grown on a 0.5 mm thick gadolinium gallium garnet ...yttrium iron garnet film and a ceramic barium strontium titanate slab. The electrical tunability of the differential phase shift Acp is achieved through

Epitaxial Garnet Investigation; Technical Report, Foreign Travel

DTIC Science & Technology

1988-10-25

Pure yttrium iron garnet (YIG) films are grown on GGG substrates by * liquid phase epitaxy ( LPE ) in production lots. In addition, one or two...epitaxial garnet films for Philips Dr. Krumme * Dr. Doormann 3-6-87 Thomson - CSF Research Center, Orsay, France Dr. J. P. Castera Dr. P. L. Meunier all...research physicists who grow, characterize, Dr. J. Y. Beguin or use epitaxial garnet films for Thomson CSF. Dr. J. L. Rolland Dr. P. Friez The

Chemistry and mineralogy of garnet pyroxenites from Sabah, Malaysia

USGS Publications Warehouse

Morgan, B.A.

1974-01-01

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

Spectral and angular-selective thermal emission from gallium-doped zinc oxide thin film structures

NASA Astrophysics Data System (ADS)

Sakr, Enas; Bermel, Peter

2017-02-01

Simultaneously controlling both the spectral and angular emission of thermal photons can qualitatively change the nature of thermal radiation, and offers a great potential to improve a broad range of applications, including infrared light sources and thermophotovoltaic (TPV) conversion of waste heat to electricity. For TPV in particular, frequency-selective emission is necessary for spectral matching with a photovoltaic converter, while directional emission is needed to maximize the fraction of emission reaching the receiver at large separation distances. This can allow the photovoltaics to be moved outside vacuum encapsulation. In this work, we demonstrate both directionally and spectrally-selective thermal emission for p-polarization, using a combination of an epsilon-near-zero (ENZ) thin film backed by a metal reflector, a high contrast grating, and an omnidirectional mirror. Gallium-doped zinc oxide is selected as an ENZ material, with cross-over frequency in the near-infrared. The proposed structure relies on coupling guided modes (instead of plasmonic modes) to the ENZ thin film using the high contrast grating. The angular width is thus controlled by the choice of grating period. Other off-directional modes are then filtered out using the omnidirectional mirror, thus enhancing frequency selectivity. Our emitter design maintains both a high view factor and high frequency selectivity, leading to a factor of 8.85 enhancement over a typical blackbody emitter, through a combination of a 22.26% increase in view factor and a 6.88x enhancement in frequency selectivity. This calculation assumes a PV converter five widths away from the same width emitter in 2D at 1573 K.

A gallium phosphide high-temperature bipolar junction transistor

NASA Technical Reports Server (NTRS)

Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

1981-01-01

Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

Garnet Electrolyte with an Ultralow Interfacial Resistance for Li-Metal Batteries.

PubMed

Li, Yutao; Chen, Xi; Dolocan, Andrei; Cui, Zhiming; Xin, Sen; Xue, Leigang; Xu, Henghui; Park, Kyusung; Goodenough, John B

2018-05-23

Garnet-structured Li 7 La 3 Zr 2 O 12 is a promising solid Li-ion electrolyte for all-solid-state Li-metal batteries and Li-redox-flow batteries owing to its high Li-ion conductivity at room temperature and good electrochemical stability with Li metal. However, there are still three major challenges unsolved: (1) the controversial electrochemical window of garnet, (2) the impractically large resistance at a garnet/electrode interface and the fast lithium-dendrite growth along the grain boundaries of the garnet pellet, and (3) the fast degradation during storage. We have found that these challenges are closely related to a thick Li 2 CO 3 layer and the Li-Al-O glass phase on the surface of garnet materials. Here we introduce a simple method to remove Li 2 CO 3 and the protons in the garnet framework by reacting garnet with carbon at 700 °C; moreover, the amount of the Li-Al-O glass phase with a low Li-ion conductivity in the grain boundary on the garnet surface was also reduced. The surface of the carbon-treated garnet pellets is free of Li 2 CO 3 and is wet by a metallic lithium anode, an organic electrolyte, and a solid composite cathode. The carbon post-treatment has reduced significantly the interfacial resistances to 28, 92 (at 65 °C), and 45 Ω cm 2 at Li/garnet, garnet/LiFePO 4 , and garnet/organic-liquid interfaces, respectively. A symmetric Li/garnet/Li, an all-solid-state Li/garnet/LiFePO 4 , and a hybrid Li-S cell show small overpotentials, high Coulombic efficiencies, and stable cycling performance.

Efficacy and safety of erbium-doped yttrium aluminium garnet fractional resurfacing laser for treatment of facial acne scars.

PubMed

Nirmal, Balakrishnan; Pai, Sathish B; Sripathi, Handattu; Rao, Raghavendra; Prabhu, Smitha; Kudur, Mohan H; Nayak, Sudhir U K

2013-01-01

Treatment of acne scars with ablative fractional laser resurfacing has given good improvement. But, data on Indian skin are limited. A study comparing qualitative, quantitative, and subjective assessments is also lacking. Our aim was to assess the improvement of facial acne scars with Erbium-doped Yttrium Aluminium Garnet (Er:YAG) 2940 nm fractional laser resurfacing and its adverse effects in 25 patients at a tertiary care teaching hospital. All 25 patients received four treatment sessions with Er:YAG fractional laser at 1-month interval. The laser parameters were kept constant for each of the four sittings in all patients. Qualitative and quantitative assessments were done using Goodman and Barron grading. Subjective assessment in percentage of improvement was also documented 1 month after each session. Photographs were taken before each treatment session and 1 month after the final session. Two unbiased dermatologists performed independent clinical assessments by comparing the photographs. The kappa statistics was used to monitor the agreement between the dermatologists and patients. Most patients (96%) showed atleast fair improvement. Rolling and superficial box scars showed higher significant improvement when compared with ice pick and deep box scars. Patient's satisfaction of improvement was higher when compared to physician's observations. No serious adverse effects were noted with exacerbation of acne lesions forming the majority. Ablative fractional photothermolysis is both effective and safe treatment for atrophic acne scars in Indian skin.Precise evaluation of acne scar treatment can be done by taking consistent digital photographs.

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2013-01-01

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.

Rare earth garnet selective emitter

NASA Technical Reports Server (NTRS)

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

1994-01-01

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.

A Comparative Histological Study of Bone Healing in Rat Calvarial Defect Using the Erbium-Doped Yttrium Aluminum Garnet Laser and Rotary Instruments

NASA Astrophysics Data System (ADS)

Jung, Mi-Kyung; Kim, Su-Gwan; Oh, Ji-Su; Jin, Seung-Chan; Lee, Sook-Young; Jang, Eun-Sook; Piao, Zheng-Gang; Lim, Sung-Chul; Jeong, Mi-Ae

2012-01-01

Erbium-doped yttrium aluminum garnet (Er:YAG) lasers have been used in dentistry for cutting bone and removal of caries. The purpose of this study was to evaluate the bone healing in a skull defect prepared in rats using various instruments including Er:YAG laser. The 7 mm calvarial defects were created in 45 rats and 45 rats were divided into three groups (n = 15): a high-speed rotation engine with carbide round bur (2-mm diameter), a low-speed rotation engine with carbide round bur (2-mm diameter), and an Er:YAG laser. Specimens obtained after 3 days or 4 or 8 weeks were submitted for histological analysis. Three days after surgery, no bone formation had occurred in any of the groups. Four weeks after surgery, 90 ±8.16% new bone formation was observed in the high-speed group, and 8 weeks after surgery, 100 ±0% new bone formation was observed in the low- and high-speed groups. There were significant differences among the periods after surgery, but no significant differences were observed among final results with in different device groups.

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

PubMed

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

2010-11-01

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

Infrared absorption study of neutron-transmutation-doped germanium

NASA Technical Reports Server (NTRS)

Park, I. S.; Haller, E. E.

1988-01-01

Using high-resolution far-infrared Fourier transform absorption spectroscopy and Hall effect measurements, the evolution of the shallow acceptor and donor impurity levels in germanium during and after the neutron transmutation doping process was studied. The results show unambiguously that the gallium acceptor level concentration equals the concentration of transmutated Ge-70 atoms during the whole process indicating that neither recoil during transmutation nor gallium-defect complex formation play significant roles. The arsenic donor levels appear at full concentration only after annealing for 1 h at 450 C. It is shown that this is due to donor-radiation-defect complex formation. Again, recoil does not play a significant role.

Scintillating Screens Based on the Single Crystalline Films of Multicomponent Garnets: New Achievements and Possibilities

NASA Astrophysics Data System (ADS)

Zorenko, Yuriy; Gorbenko, Vitalii; Zorenko, Tetiana; Paprocki, Kazimierz; Nikl, Martin; Mares, Jiri A.; Bilski, Pawel; Twardak, Anna; Sidletskiy, Oleg; Gerasymov, Iaroslav; Grinyov, Boris; Fedorov, Alexandr

2016-04-01

The paper is dedicated to development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped Lu3 - xTbxAl5 - yGayO12 multicomponent garnets at x = 2 - 3 and y = 0 - 2.5 onto Y3Al5O12 (YAG) and Gd3Al2.5Ga2.5O12 (GAGG) substrates using the liquid phase epitaxy (LPE) method. We report the optimized content and high scintillation figure of merit of SCF of these garnets grown by the LPE method with using PbO based flux. Namely, the Tb3Al2.5Ga2.5O12:Ce SCFs possess the highest values of light yield (LY) compared to all earlier investigated SCF samples, with their LY exceeding by 2.35 and 1.15 times the LY values for YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCFs of the mentioned compounds show very lower thermoluminescence in the above room temperature range and relatively fast scintillation decay.

Epitaxial Garnets and Hexagonal Ferrites.

DTIC Science & Technology

1983-12-01

operating at frequencies between 1 GHz and 25 GHz. 2. Investigate LPE growth of lithium ferrite with the objective of preparing low-loss, large area films ...and hexagonal ferrites when the series of contracts began in 1975. At that time the liquid phase epitaxy method for growth of magnetic garnet films ...principal interest in epitaxial garnets was for magnetic bubble memories. For this Uapplication the films had to be about 3pm thick with low defect density

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass

DOE PAGES

Emmer, Hal; Chen, Christopher T.; Saive, Rebecca; ...

2017-07-05

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF 2 vapor etch. The resulting GaP films have surface roughnessesmore » below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10 17 cm -3 that exhibited mobilities as high as 16 cm 2V -1s -1. Therefore, due to their unique optical properties, these films hold much promise for use in advanced optical devices.« less

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass

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

Emmer, Hal; Chen, Christopher T.; Saive, Rebecca

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF 2 vapor etch. The resulting GaP films have surface roughnessesmore » below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10 17 cm -3 that exhibited mobilities as high as 16 cm 2V -1s -1. Therefore, due to their unique optical properties, these films hold much promise for use in advanced optical devices.« less

Growth and characterization of manganese doped gallium nitride nanowires.

PubMed

Kumar, V Suresh; Kesavamoorthy, R; Kumar, J

2008-08-01

Manganese doped GaN nanowires have been grown by chemical vapour transport method on sapphire (0001) substrates in the temperature range of 800-1050 degrees C. The surface features of nanowires have been investigated using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDAX), Raman scattering studies and Electron Paramagnetic Resonance (EPR). SEM images showed that the morphology of the one dimensional materials included straight nanorods and nanowires around 70-80 nm. Raman spectrum showed the GaMnN vibrational modes at 380, 432 and 445 cm(-1). EPR measurements were performed on Mn doped GaN nanowires in order to evaluate the magnetic behaviour.

Crystal growth of HVPE-GaN doped with germanium

NASA Astrophysics Data System (ADS)

Iwinska, M.; Takekawa, N.; Ivanov, V. Yu.; Amilusik, M.; Kruszewski, P.; Piotrzkowski, R.; Litwin-Staszewska, E.; Lucznik, B.; Fijalkowski, M.; Sochacki, T.; Teisseyre, H.; Murakami, H.; Bockowski, M.

2017-12-01

Crystallization by hydride vapor phase epitaxy method of gallium nitride single crystals doped with germanium and properties of the obtained material are described in this paper. Growth was performed in hydrogen and nitrogen carrier gas. The results were studied and compared. Influence of different flows of germanium tetrachloride, precursor of germanium, on the grown crystals was investigated. Ammonothermal GaN substrates were used as seeds for crystallization. Structural, electrical, and optical properties of HVPE-GaN doped with germanium are presented and discussed in detail. They were compared to properties of HVPE-GaN doped with silicon and also grown on native seeds of high quality.

Empirical calibration of the clinopyroxene-garnet magnesium isotope geothermometer and implications

NASA Astrophysics Data System (ADS)

Li, Wang-Ye; Teng, Fang-Zhen; Xiao, Yilin; Gu, Hai-Ou; Zha, Xiang-Ping; Huang, Jian

2016-07-01

The large equilibrium Mg isotope fractionation between clinopyroxene and garnet observed in eclogites makes it a potential high-precision geothermometer, but calibration of this thermometer by natural samples is still limited. Here, we report Mg isotopic compositions of eclogite whole rocks as well as Mg and O isotopic compositions of clinopyroxene and garnet separates from 16 eclogites that formed at different temperatures from the Dabie orogen, China. The whole-rock δ26Mg values vary from -1.20 to +0.10 ‰. Among them, 11 samples display limited δ26Mg variations from -0.36 to -0.17 ‰, similar to those of their protoliths. The mineral separates exhibit very different δ26Mg values, from -0.39 to +0.39 ‰ for clinopyroxenes and from -1.94 to -0.81 ‰ for garnets. The clinopyroxene-garnet Mg isotope fractionation (Δ26Mgclinopyroxene-garnet = δ26Mgclinopyroxene-δ26Mggarnet) varies from 1.05 to 2.15 ‰. The clinopyroxene-garnet O isotope fractionation (Δ18Oclinopyroxene-garnet = δ18Oclinopyroxene-δ18Ogarnet) varies from -1.01 to +0.98 ‰. Equilibrium Mg isotope fractionation between clinopyroxene and garnet in the investigated samples is selected based on both the δ26Mgclinopyroxene versus δ26Mggarnet plot and the state of O isotope equilibrium between clinopyroxene and garnet. The equilibrium Δ26Mgclinopyroxene-garnet and corresponding temperature data obtained in this study, together with those available so far in literatures for natural eclogites, are used to calibrate the clinopyroxene-garnet Mg isotope thermometer. This yields a function of Δ26Mgclinopyroxene-garnet = (0.99 ± 0.06) × 106/ T 2, where T is temperature in Kelvin. The refined function not only provides the best empirically calibrated clinopyroxene-garnet Mg isotope thermometer for precise constraints of temperatures of clinopyroxene- and garnet-bearing rocks, but also has potential applications in high-temperature Mg isotope geochemistry.

The sensitivity of the electron transport within bulk zinc-blende gallium nitride to variations in the crystal temperature, the doping concentration, and the non-parabolicity coefficient associated with the lowest energy conduction band valley

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

Siddiqua, Poppy; O'Leary, Stephen K., E-mail: stephen.oleary@ubc.ca

2016-09-07

Within the framework of a semi-classical three-valley Monte Carlo simulation approach, we analyze the steady-state and transient electron transport that occurs within bulk zinc-blende gallium nitride. In particular, we examine how the steady-state and transient electron transport that occurs within this material changes in response to variations in the crystal temperature, the doping concentration, and the non-parabolicity coefficient associated with the lowest energy conduction band valley. These results are then contrasted with those corresponding to a number of other compound semiconductors of interest.

Passively Q-switched and mode-locked dual-wavelength Nd:GGG laser with Cr4+:YAG as a saturable absorber

NASA Astrophysics Data System (ADS)

Chu, Hongwei; Zhao, Shengzhi; Li, Yufei; Yang, Kejian; Li, Guiqiu; Li, Dechun; Zhao, Jia; Qiao, Wenchao; Li, Tao; Feng, Chuansheng; Zhang, Haijuan

2014-03-01

By using neodymium-doped gadolinium gallium garnet (Nd:GGG) as a laser medium, a simultaneously passively Q-switched and mode-locked (QML) dual-wavelength laser with Cr4+:YAG as a saturable absorber is presented. The laser simultaneously oscillated at 1061 nm and 1063 nm, corresponding to a frequency difference of 0.53 THz. QML pulses with nearly 100% modulation depth were observed. The mode-locked pulse duration underneath the Q-switched envelope was estimated to be about 908 ps. The experimental results indicated that the dual-wavelength QML Nd:GGG laser can be an excellent candidate for the generation of THz waves.

Effective lattice stabilization of gadolinium aluminate garnet (GdAG) via Lu3+ doping and development of highly efficient (Gd,Lu)AG:Eu3+ red phosphors

PubMed Central

Li, Jinkai; Li, Ji-Guang; Zhang, Zhongjie; Wu, Xiaoli; Liu, Shaohong; Li, Xiaodong; Sun, Xudong; Sakka, Yoshio

2012-01-01

The metastable garnet lattice of Gd3Al5O12 is stabilized by doping with smaller Lu3+, which then allows an effective incorporation of larger Eu3+ activators. The [(Gd1−xLux)1−yEuy]3Al5O12 (x = 0.1–0.5, y = 0.01–0.09) garnet solid solutions, calcined from their precursors synthesized via carbonate coprecipitation, exhibit strong luminescence at 591 nm (the 5D0 → 7F1 magnetic dipole transition of Eu3+) upon UV excitation into the charge transfer band (CTB) at ∼239 nm, with CIE chromaticity coordinates of x = 0.620 and y = 0.380 (orange-red). The quenching concentration of Eu3+ was estimated at ∼5 at.% (y = 0.05), and the quenching was attributed to exchange interactions. Partial replacement of Gd3+ with Lu3+ up to 50 at.% (x = 0.5) while keeping Eu3+ at the optimal content of 5 at.% does not significantly alter the peak positions of the CTB and 5D0 → 7F1 emission bands but slightly weakens both bands owing to the higher electronegativity of Lu3+. The effects of processing temperature (1000–1500 °C) and Lu/Eu contents on the intensity, quantum efficiency, lifetime and asymmetry factor of luminescence were thoroughly investigated. The [(Gd0.7Lu0.3)0.95Eu0.05]3Al5O12 phosphor processed at 1500 °C exhibits a high internal quantum efficiency of ∼83.2% under 239 nm excitation, which, in combination with the high theoretical density, favors its use as a new type of photoluminescent and scintillation material. PMID:27877495

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

NASA Technical Reports Server (NTRS)

1972-01-01

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.

Renal amyloidosis. Evaluation by gallium imaging

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

Lee, V.W.; Skinner, M.; Cohen, A.S.

1986-09-01

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 formore » 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.« less

Promise and Pitfalls of Lu/Hf-Sm/Nd Garnet Geochronology

NASA Astrophysics Data System (ADS)

King, R. L.; Vervoort, J. D.; Kohn, M. J.; Zirakparvar, N. A.; Hart, G. L.; Corrie, S. L.; Cheng, H.

2007-12-01

Our ability to routinely measure Lu-Hf and Sm-Nd isotopes in garnet allows broad new applications in geochronology, petrology, and tectonics. However, applications of these data can be limited by challenges in interpreting the petrologic record and preparing garnets for analysis. Here, we examine petrologic and chemical pitfalls encountered in garnet geochronology. Petrologic factors influencing trace element compositions in garnet include reactions that modify REE availability and partitioning (1,2), kinetically limited transfer of REEs to garnet (3), and bulk compositional heterogeneities (4). Interpreting the effects of these processes on Sm/Nd and Lu/Hf ages requires characterizing REE zonation prior to isotope analysis and age interpretation. Because garnet fractions are traditionally picked from crushed samples without regard to intracrystalline origins or chemistries, isochrons will represent mixtures derived to varying degrees from all periods of garnet growth. While measured zoning might generally indicate what garnet portion dominates the Lu/Hf or Sm/Nd budget, traditional mineral separation will rarely realize the chronologic potential afforded by high precision Hf and Nd isotope measurements. The potential use of alternative techniques, such as microsampling, necessitates selective digestion and/or leaching to eliminate inclusions within garnet. For Sm/Nd geochronology, H2SO4 leaching removes LREE-rich phosphates (e.g. apatite), but not silicates (e.g. epidote), precluding Sm-Nd dating of some rocks. For Lu/Hf geochronology, ubiquitous zircon microinclusions (c. 1 μm) can significantly disrupt age determinations. Microinclusions cannot be detected optically or separated physically, requiring selective chemical digestion. If complete digestion methods, such as bomb digestion, are used for garnet fractions, then "common Hf" from zircon will be contained in final solutions. These mixed analyses are of dubious utility and will fall into one of two

A study of doping influences on transmission of large-diameter gallium antimonide substrates for long-wave (LWIR) to very long wavelength (VLWIR) infra-red applications

NASA Astrophysics Data System (ADS)

Martinez, Rebecca; Tybjerg, Marius; Smith, Brian; Mowbray, Andrew; Furlong, Mark J.

2015-06-01

Gallium antimonide (GaSb) is an important Group III-V compound semiconductor for infra-red (IR) photodetectors used in sensing and imaging applications. Operating in the mid (3-5 μm) to long wavelength region (8-12 μm) of the IR spectrum, the application of GaSb detectors is extensive, encompassing military, industrial, medical and environmental uses. A significant developing technology for GaSb based detectors are those effective in the very long wavelength (VLWIR) infra-red region (13 μm and beyond) which are advantageous in space and stealth based applications which necessitate high operating temperatures. In this study different doping levels of GaSb are considered and the IR transmission spectra examined by Fourier Transform IR analysis. GaSb n-type doped material consistent in delivering long to very long wavelength transmission is demonstrated which is preferable to p-type material which requires backside thinning for IR transmission. Czochralski (Cz) grown GaSb wafers are assessed for electrical quality and uniformity results, on Hall mobility, resistivity and carrier level reported. Results of this work will establish the carrier concentration that ultimately results in high transparency substrates. In summary enhancements in IR transmission will be shown to be achieved in GaSb bulk crystals by tellurium (Te) compensation.

Developing New Methods for Microsampling and Sm/Nd Dating of Zoned Garnet

NASA Astrophysics Data System (ADS)

Pollington, A. D.; Baxter, E. F.

2007-12-01

Garnets provide one of the Earth Science community's most useful tools for studying rates, duration and timing of crustal processes. In this study we describe new techniques for fine sampling of multiple growth zones of garnet and Sm/Nd dating of each individual zone. We test these techniques on large (>5cm) garnets from a shear zone in the Tauern Window of Austria where we seek to quantify the growth history of garnet in a manner similar to dating tree rings. Microsampling permits a more precise quantification of duration, episodicity and kinetics of metamorphic reactions. Past studies of garnet growth duration - based on core and rim garnet ages - have been limited by sampling methods for extracting discrete, and accurate, growth zones. Modeling of radial growth symmetry in garnet shows that previous studies may underestimate garnet growth duration by as much as 50%. We are able to dramatically improve microsampling by using microdrilling guided by chemical maps of the garnet composition. This provides much improved precision and accuracy in sampling. By using chemical mapping of the garnet we can be sure that we are correctly sampling narrow (~500 micron wide) growth (i.e. age) zones rather than smearing and averaging multiple growth zones together. In principle, tens of growth zones (and ages) spanning the entire interval of garnet growth may be sampled and resolved. Microdrilled domains, the results of which are an ultrafine powder, are drilled and collected in water. Due to the adverse geochronological effect of unavoidable micro-inclusions in garnet, we have tested several partial dissolution techniques to cleanse the garnet of inclusions and yield higher 147Sm/144Nd and hence, more precise ages. Analysis of a finely crushed bulk Tauern Window garnet sample after HF/HClO3 cleansing indicates that 147Sm/144Nd at least as high as 0.89 is attainable in this particular sample, but cleansing efforts on microdrilled powders have thus far failed to yield such high

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

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

Su, Jing, E-mail: zlj007@126.com; Miao, Ju-hong; Xu, Lin-hua

2012-07-15

Graphical abstract: The graph shows the emission spectra (λ{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 aluminummore » 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.« less

Long-chain amine-templated synthesis of gallium sulfide and gallium selenide nanotubes

NASA Astrophysics Data System (ADS)

Seral-Ascaso, A.; Metel, S.; Pokle, A.; Backes, C.; Zhang, C. J.; Nerl, H. C.; Rode, K.; Berner, N. C.; Downing, C.; McEvoy, N.; Muñoz, E.; Harvey, A.; Gholamvand, Z.; Duesberg, G. S.; Coleman, J. N.; Nicolosi, V.

2016-06-01

We describe the soft chemistry synthesis of amine-templated gallium chalcogenide nanotubes through the reaction of gallium(iii) acetylacetonate and the chalcogen (sulfur, selenium) using a mixture of long-chain amines (hexadecylamine and dodecylamine) as a solvent. Beyond their role as solvent, the amines also act as a template, directing the growth of discrete units with a one-dimensional multilayer tubular nanostructure. These new materials, which broaden the family of amine-stabilized gallium chalcogenides, can be tentatively classified as direct large band gap semiconductors. Their preliminary performance as active material for electrodes in lithium ion batteries has also been tested, demonstrating great potential in energy storage field even without optimization.We describe the soft chemistry synthesis of amine-templated gallium chalcogenide nanotubes through the reaction of gallium(iii) acetylacetonate and the chalcogen (sulfur, selenium) using a mixture of long-chain amines (hexadecylamine and dodecylamine) as a solvent. Beyond their role as solvent, the amines also act as a template, directing the growth of discrete units with a one-dimensional multilayer tubular nanostructure. These new materials, which broaden the family of amine-stabilized gallium chalcogenides, can be tentatively classified as direct large band gap semiconductors. Their preliminary performance as active material for electrodes in lithium ion batteries has also been tested, demonstrating great potential in energy storage field even without optimization. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01663d

49 CFR 173.162 - Gallium.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 2 2014-10-01 2014-10-01 false Gallium. 173.162 Section 173.162 Transportation... PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.162 Gallium. (a) Except when packaged in cylinders or steel flasks, gallium must be packaged in packagings which meet the...

49 CFR 173.162 - Gallium.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 2 2012-10-01 2012-10-01 false Gallium. 173.162 Section 173.162 Transportation... PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.162 Gallium. (a) Except when packaged in cylinders or steel flasks, gallium must be packaged in packagings which meet the...

49 CFR 173.162 - Gallium.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 2 2013-10-01 2013-10-01 false Gallium. 173.162 Section 173.162 Transportation... PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.162 Gallium. (a) Except when packaged in cylinders or steel flasks, gallium must be packaged in packagings which meet the...

Structure and thermodynamics of uranium-containing iron garnets

DOE PAGES

Guo, Xiaofeng; Navrotsky, Alexandra; Kukkadapu, Ravi K.; ...

2016-09-15

Use of crystalline garnet as a waste form phase appears to be advantageous for accommodating actinides from nuclear waste. Previous studies show that large amounts of uranium (U) and its analogues such as cerium (Ce) and thorium (Th) can be incorporated into the garnet structure. In this study, we synthesized U loaded garnet phases, Ca 3U xZr 2–xFe 3O 12 (x = 0.5–0.7), along with the endmember phase, Ca 3(Zr 2)SiFe 3+ 2O 12, for comparison. The oxidation states of U were determined by X-ray photoelectron and absorption spectroscopies, revealing the presence of mixed pentavalent and hexavalent uranium in themore » phases with x = 0.6 and 0.7. The oxidation states and coordination environments of Fe were measured using transmission 57Fe-Mössbauer spectroscopy, which shows that all iron is tetrahedrally coordinated Fe 3+. U substitution had a significant effect on local environments, the extent of U substitution within this range had a minimal effect on the structure, and unlike in the x = 0 sample, Fe exists in two different environments in the substituted garnets. The enthalpies of formation of garnet phases from constituent oxides and elements were first time determined by high temperature oxide melt solution calorimetry. The results indicate that these substituted garnets are thermodynamically stable under reducing conditions. Furthermore, our structural and thermodynamic analysis further provides explanation for the formation of natural uranium garnet, elbrusite-(Zr), and supports the potential use of Ca 3U xZr 2–xFe 3O 12 as viable waste form phases for U and other actinides.« less

Structure and thermodynamics of uranium-containing iron garnets

NASA Astrophysics Data System (ADS)

Guo, Xiaofeng; Navrotsky, Alexandra; Kukkadapu, Ravi K.; Engelhard, Mark H.; Lanzirotti, Antonio; Newville, Matthew; Ilton, Eugene S.; Sutton, Stephen R.; Xu, Hongwu

2016-09-01

Use of crystalline garnet as a waste form phase appears to be advantageous for accommodating actinides from nuclear waste. Previous studies show that large amounts of uranium (U) and its analogues such as cerium (Ce) and thorium (Th) can be incorporated into the garnet structure. In this study, we synthesized U loaded garnet phases, Ca3UxZr2-xFe3O12 (x = 0.5-0.7), along with the endmember phase, Ca3(Zr2)SiFe3+2O12, for comparison. The oxidation states of U were determined by X-ray photoelectron and absorption spectroscopies, revealing the presence of mixed pentavalent and hexavalent uranium in the phases with x = 0.6 and 0.7. The oxidation states and coordination environments of Fe were measured using transmission 57Fe-Mössbauer spectroscopy, which shows that all iron is tetrahedrally coordinated Fe3+. U substitution had a significant effect on local environments, the extent of U substitution within this range had a minimal effect on the structure, and unlike in the x = 0 sample, Fe exists in two different environments in the substituted garnets. The enthalpies of formation of garnet phases from constituent oxides and elements were first time determined by high temperature oxide melt solution calorimetry. The results indicate that these substituted garnets are thermodynamically stable under reducing conditions. Our structural and thermodynamic analysis further provides explanation for the formation of natural uranium garnet, elbrusite-(Zr), and supports the potential use of Ca3UxZr2-xFe3O12 as viable waste form phases for U and other actinides.

Application of gallium nitride nanostructures and nitrogen doped carbon spheres as supports for the hydrogenation of cinnamaldehyde.

PubMed

Kente, Thobeka; Dube, Sibongile M A; Coville, Neil J; Mhlanga, Sabelo D

2013-07-01

This paper reports on the synthesis and use of nanostructures of gallium nitride (GaN NSs) and nitrogen doped carbon spheres (NCSs) as support materials for the hydrogenation of cinnamaldehyde. This study provides the first investigation of GaN as a catalyst support in hydrogenation reactions. The GaN NSs were synthesized via chemical vapour deposition (CVD) in a double stage furnace (750 degrees C) while NCSs were made by CVD in a single stage furnace (950 degrees C) respectively. TEM analysis revealed that the GaN NSs were rod-like with average diameters of 200 nm, while the NCSs were solid with smoother surfaces, and with diameters of 450 nm. Pd nanoparticles (1 and 3% loadings) were uniformly dispersed on acid functionalized GaN NSs and NCS. The Pd nanoparticles had average diameters that were influenced by the type of support material used. The GaN NSs and NCSs were tested for the selective hydrogenation of cinnamaldehyde in isopropanol at 40 and 60 degrees C under atmospheric pressure. A comparative study of the activity of the nanostructured materials revealed that the order of catalyst activity was 3% Pd/GaN > 3% Pd/NCSs > 1% Pd/NCSs > 1% Pd/GaN. However, 100% selectivity to hydrocinnamaldehyde (HCALD) was obtained with 1% Pd/GaN at reasonable conversion rates.

Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control.

PubMed

Sarkar, Sujoy; Sampath, S

2016-05-11

A ternary, ionically conducting, deep eutectic solvent based on acetamide, urea and gallium nitrate is reported for the electrodeposition of gallium nitride/gallium indium nitride under ambient conditions; blue and white light emitting photoluminescent deposits are obtained under potential control.

Temperature-dependent relaxation of dipole-exchange magnons in yttrium iron garnet films

NASA Astrophysics Data System (ADS)

Mihalceanu, Laura; Vasyuchka, Vitaliy I.; Bozhko, Dmytro A.; Langner, Thomas; Nechiporuk, Alexey Yu.; Romanyuk, Vladyslav F.; Hillebrands, Burkard; Serga, Alexander A.

2018-06-01

Low-energy consumption enabled by charge-free information transport, which is free from Joule heating, and the ability to process phase-encoded data through the use of nanometer-sized interference devices operating at GHz and THz frequencies are just a few benefits of spin-wave-based technologies. Moreover, when approaching cryogenic temperatures, quantum phenomena in spin-wave systems pave the path towards quantum information processing. In view of these applications, the lifetime of magnons—spin-wave quanta—is of high relevance for the fields of magnonics, magnon spintronics, and quantum computing. Here, the relaxation behavior of parametrically excited magnons having wave numbers from zero up to 6 ×105rad cm-1 was experimentally investigated in the temperature range from 20 to 340 K in single-crystal yttrium iron garnet (YIG) films of different thickness epitaxially grown on gallium gadolinium garnet (GGG) substrates as well as in a bulk YIG crystal—the magnonic materials featuring the lowest magnetic damping thus far known. Due to magnon-magnon interactions, the relaxation rate of the parametric magnons increases with an increase of their wave numbers. In the thinner samples, this increase is less pronounced, which can be associated with a stronger quantization of their magnon spectra. For the YIG films, we have found a significant increase in the magnon relaxation rate below 150 K—up to eight times the reference value at 340 K—in the entire range of probed wave numbers, which is in direct opposition to that in ultrapure YIG crystals. This increase is related to rare-earth impurities contaminating the YIG samples with a slight contribution caused by the coupling of spin waves to the spin system of the paramagnetic GGG substrate at the lowest temperatures.

Mineral resource of the month: gallium

USGS Publications Warehouse

Jaskula, Brian W.

2009-01-01

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.

Stabilization of cubic Li7La3Hf2O12 by Al-doping

NASA Astrophysics Data System (ADS)

Baklanova, Yana V.; Tyutyunnik, Alexander P.; Tarakina, Nadezda V.; Fortes, A. Dominic; Maksimova, Lidiya G.; Korona, Daniil V.; Denisova, Tatyana A.

2018-07-01

In this paper we report on the stabilization of cubic Li7La3Hf2O12 by Al3+ doping and present a detailed crystal structure study and lithium ion conductivity measurements of the obtained compound. Polycrystalline Al-doped Li7La3Hf2O12 was prepared by a modified solid state method. The compound consists of micrometer size grains encapsulated by a glassy phase, which helps preventing the volatilization of lithium during annealing. Al-doped Li7La3Hf2O12 crystallizes in the garnet-related structure with a cubic unit cell (sp. gr. Ia 3 bar d (230)). A structural refinement using X-ray and neutron powder diffraction data showed that the Al3+ ions occupy only tetrahedral Li+ sites in the structure. The presence of overextended leading edges of the peaks on the XRD and NPD data is described by the introduction of an additional phase with rhombohedral distortion that occurs through a stretching of the cubic phase along the body diagonal. The activation energy as well as the total conductivity at room temperature are close to values obtained for un-doped cubic Li7La3Zr2O12 and Li7La3Hf2O12 garnets, which make Al-doped Li7La3Hf2O12 a potential candidate for the application as solid electrolyte in solid-state rechargeable lithium-ion batteries.

Investigation of the growth of garnet films by liquid phase epitaxy

NASA Technical Reports Server (NTRS)

Moody, J. W.; Shaw, R. W.; Sandfort, R. M.

1974-01-01

Liquid phase expitaxy was investigated to determine its applicability to fabricating magnetic rare earth garnet films for spacecraft data recording systems. Two mixed garnet systems were investigated in detail: (1) Gd-Y and (2) Eu-Yb-Y. All films were deposited on Gd3Ga5012 substrates. The uniaxial anisotropy of the Gd-Y garnets is primarily stress-induced. These garnets are characterized by high-domain wall mobility, low coercivity and modest anisotropy. Characteristic length was found to be relatively sensitive to temperature. The Eu-Yb-Y garnets exhibit acceptable mobilities, good temperature stability and reasonable quality factors. The uniaxial anisotropy of these garnets is primarily growth-induced. The system is well suited for compositional "tailoring" to optimize specific desirable properties. Liquid phase epitaxy can be used to deposit Gd3Ga5012 spacing layers on magnetic garnet films and this arrangement possesses certain advantages over more conventional magnetic filmspacing layer combinations. However, it cannot be used if the magnetic film is to be ion implanted.

Controlled Electrochemical Deformation of Liquid-Phase Gallium.

PubMed

Chrimes, Adam F; Berean, Kyle J; Mitchell, Arnan; Rosengarten, Gary; Kalantar-zadeh, Kourosh

2016-02-17

Pure gallium is a soft metal with a low temperature melting point of 29.8 °C. This low melting temperature can potentially be employed for creating optical components with changeable configurations on demand by manipulating gallium in its liquid state. Gallium is a smooth and highly reflective metal that can be readily maneuvered using electric fields. These features allow gallium to be used as a reconfigurable optical reflector. This work demonstrates the use of gallium for creating reconfigurable optical reflectors manipulated through the use of electric fields when gallium is in a liquid state. The use of gallium allows the formed structures to be frozen and preserved as long as the temperature of the metal remains below its melting temperature. The lens can be readily reshaped by raising the temperature above the melting point and reapplying an electric field to produce a different curvature of the gallium reflector.

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

PubMed Central

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

2013-01-01

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

Development of a gallium-doped germanium far-infrared photoconductor direct hybrid two-dimensional array.

PubMed

Fujiwara, Mikio; Hirao, Takanori; Kawada, Mitsunobu; Shibai, Hiroshi; Matsuura, Shuji; Kaneda, Hidehiro; Patrashin, Mikhail; Nakagawa, Takao

2003-04-20

To our knowledge, we are the first to successfully report a direct hybrid two-dimensional (2D) detector array in the far-infrared region. Gallium-doped germanium (Ge:Ga) has been used extensively to produce sensitive far-infrared detectors with a cutoff wavelength of approximately equal to 110 microm (2.7 THz). It is widely used in the fields of astronomy and molecular and solid spectroscopy. However, Ge:Ga photoconductors must be cooled below 4.2 K to reduce thermal noise, and this operating condition makes it difficult to develop a large format array because of the need for a warm amplifier. Development of Ge:Ga photoconductor arrays to take 2D terahertz images is now an important target in such research fields as space astronomy. We present the design of a 20 x 3 Ge:Ga far-infrared photoconductor array directly hybridized to a Si p-type metal-oxide-semiconductor readout integrated circuit using indium-bump technology. The main obstacles in creating this 2D array were (1) fabricating a monolithic Ge:Ga 2D array with a longitudinal configuration, (2) developing a cryogenic capacitive transimpedance amplifer, and (3) developing a technology for connecting the detector to the electronics. With this technology, a prototype Ge:Ga photoconductor with a direct hybrid structure has shown a responsivity as high as 14.6 A/W and a minimum detectable power of 5.6 x 10(-17) W for an integration time of 0.14 s when it was cooled to 2.1 K. Its noise is limited by the readout circuit with 20 microV/Hz(1/2) at 1 Hz. Vibration and cooling tests demonstrated that this direct hybrid structure is strong enough for spaceborne instruments. This detector array will be installed on the Japanese infrared satellite ASTRO-F.

Resistless lithography - selective etching of silicon with gallium doping regions

NASA Astrophysics Data System (ADS)

Abdullaev, D.; Milovanov, R.; Zubov, D.

2016-12-01

This paper presents the results for used of resistless lithography with a further reactive-ion etching (RIE) in various chemistry after local (Ga+) implantation of silicon with different doping dose and different size doped regions. We describe the different etching regimes for pattern transfer of FIB implanted Ga masks in silicon. The paper studied the influence of the implantation dose on the silicon surface, the masking effect and the mask resistance to erosion at dry etching. Based on these results we conclude about the possibility of using this method to create micro-and nanoscale silicon structures.

Effects of the substitution of gallium with boron on the physical and mechanical properties of Ni-Mn-Ga shape memory alloys

NASA Astrophysics Data System (ADS)

Aydogdu, Yildirim; Turabi, Ali Sadi; Kok, Mediha; Aydogdu, Ayse; Tobe, Hirobumi; Karaca, Haluk Ersin

2014-12-01

The effects of the substitution of gallium with boron on the physical, mechanical and magnetic shape memory properties of Ni51Mn28.5Ga20.5- xBx (at.%) ( x = 0, 1, 2, 3) polycrystalline alloys are investigated. It has been found that transformation temperatures are decreasing while hardness is increasing with boron addition. B-doping of NiMnGa alloys results in the formation of a second phase that increases its ductility and strength in compression. Moreover, saturation magnetization of austenite is decreasing, while Curie temperature of austenite is increasing with B-doping.

Experimental study of quartz inclusions in garnet at pressures up to 3.0 GPa: evaluating validity of the quartz-in-garnet inclusion elastic thermobarometer

NASA Astrophysics Data System (ADS)

Thomas, Jay B.; Spear, Frank S.

2018-05-01

Garnet crystals with quartz inclusions were hydrothermally crystallized from oxide starting materials in piston-cylinder apparatuses at pressures from 0.5 to 3 GPa and temperatures ranging from 700 to 800 °C to study how entrapment conditions affect remnant pressures of quartz inclusions used for quartz-in-garnet (QuiG) elastic thermobarometry. Systematic changes of the 128, 206 and 464 cm-1 Raman band frequencies of quartz were used to determine pressures of quartz inclusions in garnet using Raman spectroscopy calibrations that describe the P-T dependencies of Raman band shifts for quartz under hydrostatic pressure. Within analytical uncertainties, inclusion pressures calculated for each of the three Raman band frequencies are equivalent, which suggests that non-hydrostatic stress effects caused by elastic anisotropy in quartz are smaller than measurement errors. The experimental quartz inclusions have pressures ranging from - 0.351 to 1.247 GPa that span the range of values observed for quartz inclusions in garnets from natural rocks. Quartz inclusion pressures were used to model P-T conditions at which the inclusions could have been trapped. The accuracy of QuiG thermobarometry was evaluated by considering the differences between pressures measured during experiments and pressures calculated using published equation of state parameters for quartz and garnet. Our experimental results demonstrate that Raman measurements performed at room temperature can be used without corrections to estimate garnet crystallization pressures. Calculated entrapment pressures for quartz inclusions in garnet are less than 10% different from pressures measured during the experiments. Because the method is simple to apply with reasonable accuracy, we expect widespread usage of QuiG thermobarometry to estimate crystallization conditions for garnet-bearing silicic rocks.

Manufacturing issues and optical properties of rare-earth (Y, Lu, Sc, Nd) aluminate garnets composite transparent ceramics

NASA Astrophysics Data System (ADS)

Bonnet, Loïck; Boulesteix, Rémy; Maître, Alexandre; Sallé, Christian; Couderc, Vincent; Brenier, Alain

2015-12-01

In this work, a comparative study of reactive sintering and optical properties of three laser composite transparent ceramics doped with neodymium: Nd:YAG/Nd:YS1AG, Nd:YAG/Nd:LuAG and Nd:YS1AG/Nd:LuAG has been achieved. Samples were manufactured thanks to pressureless co-sintering under vacuum of bilayer powder compacts. The reaction sequence from primary oxides to final garnet phases has been investigated. Similar dilatometric behavior was observed during reactive-sintering for each composition. Differential shrinkage can be thus accommodated to some extent. Second, this work has shown that the intermediate zone at composites interface is composed of single-phased garnet solid-solution with continuous evolution from one side to the other. The thickness of the interdiffusion zone was found to be limited to about 100 μm in all cases and appeared to be well described by classical diffusion laws of Fick and Whipple-Le Claire. The analyses of spectroscopic properties of transparent ceramics composites have finally shown that composite ceramics should be suitable to produce dual wavelength emission for terahertz generation.

Controlling laser-induced magnetization reversal dynamics in a rare-earth iron garnet across the magnetization compensation point

NASA Astrophysics Data System (ADS)

Deb, Marwan; Molho, Pierre; Barbara, Bernard; Bigot, Jean-Yves

2018-04-01

In this work we explore the ultrafast magnetization dynamics induced by femtosecond laser pulses in a doped film of gadolinium iron garnet over a broad temperature range including the magnetization compensation point TM. By exciting the phonon-assisted 6S→4G and 6S→4P electronic d -d transitions simultaneously by one- and two-photon absorption processes, we find out that the transfer of heat energy from the lattice to the spin has, at a temperature slightly below TM, a large influence on the magnetization dynamics. In particular, we show that the speed and the amplitude of the magnetization dynamics can be strongly increased when increasing either the external magnetic field or the laser energy density. The obtained results are explained by a magnetization reversal process across TM. Furthermore, we find that the dynamics has unusual characteristics which can be understood by considering the weak spin-phonon coupling in magnetic garnets. These results open new perspectives for controlling the magnetic state of magnetic dielectrics using an ultrashort optically induced heat pulse.

Zinc diffusion in gallium arsenide and the properties of gallium interstitials

NASA Astrophysics Data System (ADS)

Bracht, H.; Brotzmann, S.

2005-03-01

We have performed zinc diffusion experiments in gallium arsenide at temperatures between 620°C and 870°C with a dilute Ga-Zn source. The low Zn partial pressure established during annealing realizes Zn surface concentrations of ⩽2×1019cm-3 , which lead to the formation of characteristic S-shaped diffusion profiles. Accurate modeling of the Zn profiles, which were measured by means of secondary ion mass spectroscopy, shows that Zn diffusion under the particular doping conditions is mainly mediated by neutral and singly positively charged Ga interstitials via the kick-out mechanism. We determined the temperature dependence of the individual contributions of neutral and positively charged Ga interstitials to Ga diffusion for electronically intrinsic conditions. The data are lower than the total Ga self-diffusion coefficient and hence consistent with the general interpretation that Ga diffusion under intrinsic conditions is mainly mediated by Ga vacancies. Our results disprove the general accepted interpretation of Zn diffusion in GaAs via doubly and triply positively charged Ga interstitials and solves the inconsistency related to the electrical compensation of the acceptor dopant Zn by the multiply charged Ga interstitials.

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

NASA Technical Reports Server (NTRS)

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

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

Comparison of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet laser for treatment of cosmetic tattoos containing titanium and iron in an animal model.

PubMed

Wang, Chia-Chen; Huang, Chuen-Lin; Yang, An-Hang; Chen, Chih-Kang; Lee, Shao-Chen; Leu, Fur-Jiang

2010-11-01

Cosmetic tattoos contain titanium and ferric oxide and darken through reduction after Q-switched laser irradiation. The optimal treatment for removing these pigments remains unknown. To compare the effects of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet (SP Er:YAG) laser to remove cosmetic tattoos in an animal model. Rats were tattooed using white, flesh-colored, and brown inks (4 bands of each color) on their backs. For each color, one band was left untreated, and one each was treated with a Q-switched neodymium-doped YAG laser, a Q-switched alexandrite laser, and a SP Er:YAG laser every 3 weeks until the pigments were clear. The two Q-switched lasers were equally effective; all three pigments darkened initially and then resolved gradually. Up to 20, 18, and 10 sessions were required to remove white, flesh-colored, and brown tattoos, respectively. Only six sessions were required with the SP Er:YAG laser. Minimal scarring was observed with all lasers. Skin biopsies confirmed pigment granule fragmentation after Q-switched laser treatment and a decrease in the amount of pigment after SP Er:YAG laser treatment. The SP Er:YAG laser was superior to the Q-switched lasers for removing cosmetic tattoos. © 2010 by the American Society for Dermatologic Surgery, Inc.

Construction of Gallium Point at NMIJ

NASA Astrophysics Data System (ADS)

Widiatmo, J. V.; Saito, I.; Yamazawa, K.

2017-03-01

Two open-type gallium point cells were fabricated using ingots whose nominal purities are 7N. Measurement systems for the realization of the melting point of gallium using these cells were built. The melting point of gallium is repeatedly realized by means of the measurement systems for evaluating the repeatability. Measurements for evaluating the effect of hydrostatic pressure coming from the molten gallium existing during the melting process and the effect of gas pressure that fills the cell were also performed. Direct cell comparisons between those cells were conducted. This comparison was aimed to evaluate the consistency of each cell, especially related to the nominal purity. Direct cell comparison between the open-type and the sealed-type gallium point cell was also conducted. Chemical analysis was conducted using samples extracted from ingots used in both the newly built open-type gallium point cells, from which the effect of impurities in the ingot was evaluated.

Quantification of water in majoritic garnet

DOE PAGES

Thomas, Sylvia -Monique; Wilson, Kathryn; Koch-Muller, Monika; ...

2015-05-01

Majoritic garnet, characterized by an excess of silicon (>3 Si per formula unit), is considered one of the major phases of the Earth’s transition zone from 410-660 km depth. Quantifying the H 2O content of nominally anhydrous mantle minerals is necessary to evaluate their water storage capacity from experiments and modeling the Earth’s deep water cycle. We present mineral-specific infrared absorption coefficients for the purpose of quantifying the amount of water incorporated into majorite as hydroxyl point defects. A suite of majoritic garnet samples with varying proportions of Si, Fe, Al, Cr and H 2O was synthesized at conditions ofmore » 18-19 GPa and 1500-1800°C. Single-crystals were characterized using X-ray diffraction, electron microprobe analysis, secondary Ion Mass spectrometry (SIMS), IR, Raman and Mössbauer spectroscopy. We utilize SIMS and Raman spectroscopy in combination with IR spectroscopy to provide IR absorption coefficients for water in majoritic garnets with the general mineral formula (Mg,Fe) 3(Si,Mg,Fe,Al,Cr) 2[SiO4] 3. Furthermore, the IR absorption coefficient for majoritic garnet in the OH stretching region is frequency-dependent and ranges from 10 470 ± 3100 Lmol-1cm-2 to 23 400 ± 2300 Lmol -1cm -2.« less

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

NASA Astrophysics Data System (ADS)

Harlov, D. E.

2009-12-01

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

The Friningen Garnet Peridotite (central Swedish Caledonides). A good example of the characteristic PTt path of a cold mantle wedge garnet peridotite

NASA Astrophysics Data System (ADS)

Gilio, Mattia; Clos, Frediano; van Roermund, Herman L. M.

2015-08-01

We present pseudosections of Cr-bearing garnet peridotite that together with new mineral-chemical data allow quantification of the early PT conditions of the original lithospheric mantle assemblage (M1) of the Friningen Garnet Peridotite (FGP) located in the central/middle belt of the Seve Nappe Complex in central Sweden. Results indicate that the early, coarse grained, olivine + orthopyroxene + clinopyroxene + "high Cr" garnet assemblage (M1a) was formed at 1100 ± 100 °C and 5.0 ± 0.5 GPa. These metamorphic conditions were followed by an inferred late Proterozoic exhumation event down to 850-900 °C and 1.5 GPa (M1b). The latter PT estimate is based on the breakdown of high-Cr M1a garnet (Cr# = 0.065) + olivine into an orthopyroxene + clinopyroxene + spinel (Cr# = 0.15-0.25) ± pargasite kelyphite (M1b) and the exsolution of garnet from Al-rich orthopyroxene and clinopyroxene. The M1b kelyphite is overprinted by an early-Caledonian UHPM mineral assemblage (M2; T = 800 °C and P = 3.0 GPa), equivalent to the earlier discovered UHP assemblage within an eclogitic dyke that cross-cuts FGP. In the garnet peridotite M2 is displayed by low-Cr garnet (Cr# = 0.030) growing together with spinel (Cr# = 0.35-0.45), both these minerals form part of the olivine + orthopyroxene + clinopyroxene + garnet + spinel + pargasite M2 assemblage. The formation of plagioclase + diopside symplectites after omphacite and breakdown of kyanite to sapphirine + albite in internal eclogite and the breakdown of M2 olivine + garnet to amphibole + orthopyroxene + spinel assemblages (M3) in garnet peridotite indicate post-UHP isothermal decompression down to 750-800 °C and 0.8-1.0 GPa (= M3). Multiphase solid-and fluid inclusion assemblages composed of Sr-bearing magnesite, dolomite or carbon decorate linear defect structures within M1a-b minerals and/or form subordinate local assemblages together with M2 minerals. The latter are interpreted as evidence for infiltration of early-Caledonian COH

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

PubMed

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

2002-11-20

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

Characterizations of Pr-doped Yb3Al5O12 single crystals for scintillator applications

NASA Astrophysics Data System (ADS)

Yoshida, Yasuki; Shinozaki, Kenji; Igashira, Takuya; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-04-01

Yb3Al5O12 (YbAG) single crystals doped with different concentrations of Pr were synthesized by the Floating Zone (FZ) method. Then, we evaluated their basic optical and scintillation properties. All the samples showed photoluminescence (PL) with two emission bands appeared approximately 300-500 nm and 550-600 nm due to the charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. A PL decay profile of each sample was approximated by a sum of two exponential decay functions, and the obtained decay times were 1 ns and 3-4 ns. In the scintillation spectra, we observed emission peaks in the ranges from 300 to 400 nm and from 450 to 550 nm for all the samples. The origins of these emissions were attributed to charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. The scintillation decay times became longer with increasing the Pr concentrations. Among the present samples, the 0.1% Pr-doped sample showed the lowest scintillation afterglow level. In addition, pulse height spectrum of 5.5 MeV α-rays was demonstrated using the Pr-doped YbAG, and we confirmed that all the samples showed a full energy deposited peak. Above all, the 0.1% Pr-doped sample showed the highest light yield with a value of 14 ph/MeV under α-rays excitation.

Efficient channel-waveguide laser in Nd:GGG at 1.062 μm wavelength

NASA Astrophysics Data System (ADS)

Gerhardt, R.; Kleine-Börger, J.; Beilschmidt, L.; Frommeyer, M.; Dötsch, H.; Gather, B.

1999-08-01

Channel waveguide lasers in crystals of neodymium-doped gadolinium-gallium-garnet are realized. They are based on single-mode rib waveguides prepared by liquid phase epitaxy. By this growth technique the incorporation of certain impurities, which may cause severe quenching, is inevitable. The dominant quenching process could be identified and eliminated. Channel waveguides with extremely low losses, down to 0.25 dB/cm for both TE and TM modes, are fabricated by ion-beam etching. As a result, low thresholds of 5 mW and high slope efficiencies of 48% at the laser wavelength of 1.062 μm could be achieved when pumping at a wavelength of 807 nm.

Doping of epitaxial III-V semiconductors for optoelectronic and magnetoelectronic applications

NASA Astrophysics Data System (ADS)

Overberg, Mark Eddy

Doped III-V semiconducting materials were studied in this dissertation for use in optoelectronic and magnetoelectronic applications. The specific areas of use are emitters for fiber optic communication and room temperature ferromagnetic layers for spintronic devices. The general requirement for both application areas is the ability to heavily dope (or alloy) the III-Vs with the intended active element, while still maintaining good crystallinity and semiconducting properties. Four dopant/semiconductor systems were investigated: erbium in gallium nitride (GaN:Er), europium in gallium nitride (GaN:Eu), manganese in gallium nitride (GaMnN), and manganese in gallium phosphide (GaMnP). These materials were fabricated using variants of the molecular beam epitaxy (MBE) technique, where beams of the constituent elements are produced in a high vacuum environment. The technique allows for a wide variety of parameters to be adjusted during the material preparation. The materials were deposited on sapphire, gallium nitride, and gallium phosphide surfaces; with particular emphasis on the correlation between growth conditions and the final chemical, structural, morphological, electronic, optical, and magnetic properties. The materials were characterized using a variety of techniques. Results with the GaN:Er material indicated that several percent of Er could be successfully incorporated into the material, and that the optical emission could be increased by incorporating C impurities into the film. These impurities were found to increase the overall emission and decrease the quenching of the emission with temperature. Optical emission results for GaN:Eu indicated that this material produced a visible red emission that was brighter under optical excitation than the AlGaAs used in commercial red emitting devices. The dilute magnetic semiconductors n-GaMnN and p-GaMnP were produced for the first time by the MBE technique. The SQUID magnetometry and magnetotransport results for n

Development of a Multi-layer Anti-reflective Coating for Gallium Arsenide/Aluminum Gallium Arsenide Solar Cells

DTIC Science & Technology

2015-07-01

optical loss mechanism, which limits the efficiency of the PV device.1 Photon absorption needs to occur inside the solar cell active region (near the...Aluminum Gallium Arsenide Solar Cells by Kimberley A Olver Approved for public release; distribution unlimited...Development of a Multi-layer Anti-reflective Coating for Gallium Arsenide/Aluminum Gallium Arsenide Solar Cells by Kimberley A Olver

Silicate garnet studies at high pressures: A view into the Earth's mantle

NASA Astrophysics Data System (ADS)

Conrad, Pamela Gales

Silicate garnets are an abundant component in the Earth's upper mantle and transition zone. Therefore, an understanding of garnet behavior under the pressure and temperature conditions of the mantle is critical to the development of models for mantle mineralogy and dynamics. Work from three projects is presented in this report. Each investigation explores an aspect of silicate garnet behavior under high pressures. Moreover, each investigation was made possible by state-of-the-art methods that have previously been unavailable. Brillouin scattering was used to determine the elastic constants and aggregate elastic moduli of three end-member garnets at high pressures in a diamond anvil cell. These are the first high-pressure measurements of the elastic constants of end-member silicate garnets by direct measurement of acoustic velocities. The results indicate that the pressure dependence of silicate garnet elastic constants varies with composition. Therefore, extrapolation from measurements on mixed composition garnets is not possible. A new method of laser heating minerals in a diamond anvil cell has made possible the determination of the high-pressure and high-temperature stability of almandine garnet. This garnet does not transform to a silicate perovskite phase as does pyrope garnet, but it decomposes to its constituent oxides: FeO, Alsb2Osb3, and SiOsb2. These results disprove an earlier prediction that ferrous iron may expand the stability field of garnet to the lower mantle. The present results demonstrate that this is not the case. The third topic is a presentation of the results of a new technique for studying inclusions in mantle xenoliths with synchrotron X-ray microdiffraction. The results demonstrate the importance of obtaining structural as well as chemical information on inclusions within diamonds and other high-pressure minerals. An unusual phase with garnet composition is investigated and several other phases are identified from a suite of natural

Phase-controllable spin wave generation in iron garnet by linearly polarized light pulses

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

Yoshimine, Isao; Iida, Ryugo; Shimura, Tsutomu

A phase-controlled spin wave was non-thermally generated in bismuth-doped rare-earth iron garnet by linearly polarized light pulses. We controlled the initial phase of the spin wave continuously within a range of 180° by changing the polarization azimuth of the excitation light. The azimuth dependences of the initial phase and amplitude of the spin wave were attributed to a combination of the inverse Cotton-Mouton effect and photoinduced magnetic anisotropy. Temporally and spatially resolved spin wave propagation was observed with a CCD camera, and the waveform was in good agreement with calculations. A nonlinear effect of the spin excitation was observed formore » excitation fluences higher than 100 mJ/cm{sup 2}.« less

Generator for gallium-68 and compositions obtained therefrom

DOEpatents

Neirinckx, Rudi D.; Davis, Michael A.

1981-01-01

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.

Effect of Gallium Doping on the Characteristic Properties of Polycrystalline Cadmium Telluride Thin Film

NASA Astrophysics Data System (ADS)

Ojo, A. A.; Dharmadasa, I. M.

2017-08-01

Ga-doped CdTe polycrystalline thin films were successfully electrodeposited on glass/fluorine doped tin oxide substrates from aqueous electrolytes containing cadmium nitrate (Cd(NO3)2·4H2O) and tellurium oxide (TeO2). The effects of different Ga-doping concentrations on the CdTe:Ga coupled with different post-growth treatments were studied by analysing the structural, optical, morphological and electronic properties of the deposited layers using x-ray diffraction (XRD), ultraviolet-visible spectrophotometry, scanning electron microscopy, photoelectrochemical cell measurement and direct-current conductivity test respectively. XRD results show diminishing (111)C CdTe peak above 20 ppm Ga-doping and the appearance of (301)M GaTe diffraction above 50 ppm Ga-doping indicating the formation of two phases; CdTe and GaTe. Although, reductions in the absorption edge slopes were observed above 20 ppm Ga-doping for the as-deposited CdTe:Ga layer, no obvious influence on the energy gap of CdTe films with Ga-doping were detected. Morphologically, reductions in grain size were observed at 50 ppm Ga-doping and above with high pinhole density within the layer. For the as-deposited CdTe:Ga layers, conduction type change from n- to p- were observed at 50 ppm, while the n-type conductivity were retained after post-growth treatment. Highest conductivity was observed at 20 ppm Ga-doping of CdTe. These results are systematically reported in this paper.

Antitumor effect of novel gallium compounds and efficacy of nanoparticle-mediated gallium delivery in lung cancer.

PubMed

Wehrung, Daniel; Oyewumi, Moses O

2012-02-01

The widespread application of gallium (Ga) in cancer therapy has been greatly hampered by lack of specificity resulting in poor tumor accumulation and retention. To address the challenge, two lipophilic gallium (III) compounds (gallium hexanedione; GaH and gallium acetylacetonate; GaAcAc) were synthesized and antitumor studies were conducted in human lung adenocarcinoma (A549) cells. Nanoparticles (NPs) containing various concentrations of the Ga compounds were prepared using a binary mixture of Gelucire 44/14 and cetyl alcohol as matrix materials. NPs were characterized based on size, morphology, stability and biocompatibility. Antitumor effects of free or NP-loaded Ga compounds were investigated based on cell viability, production of reactive oxygen species and reduction of mitochondrial potential. Compared to free Ga compounds, cytotoxicity of NP-loaded Ga (5-150 microg/ml) was less dependent on concentration and incubation time (exposure) with A549 cells. NP-mediated delivery (5-150 microg Ga/ml) enhanced antitumor effects of Ga compounds and the effect was pronounced at: (i) shorter incubation times; and (ii) at low concentrations of gallium (approximately 50 microg/ml) (p < 0.0006). Additional studies showed that NP-mediated Ga delivery was not dependent on transferrin receptor uptake mechanism (p > 0.13) suggesting the potential in overcoming gallium resistance in some tumors. In general, preparation of stable and biocompatible NPs that facilitated Ga tumor uptake and antitumor effects could be effective in gallium-based cancer therapy.

Heterojunction solar cell with 6% efficiency based on an n-type aluminum-gallium-oxide thin film and p-type sodium-doped Cu2O sheet

NASA Astrophysics Data System (ADS)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2015-02-01

In this paper, we describe efforts to enhance the efficiency of Cu2O-based heterojunction solar cells fabricated with an aluminum-gallium-oxide (Al-Ga-O) thin film as the n-type layer and a p-type sodium (Na)-doped Cu2O (Cu2O:Na) sheet prepared by thermally oxidizing copper sheets. The optimal Al content [X; Al/(Ga + Al) atomic ratio] of an AlX-Ga1-X-O thin-film n-type layer was found to be approximately 2.5 at. %. The optimized resistivity was approximately 15 Ω cm for n-type AlX-Ga1-X-O/p-type Cu2O:Na heterojunction solar cells. A MgF2/AZO/Al0.025-Ga0.975-O/Cu2O:Na heterojunction solar cell with 6.1% efficiency was fabricated using a 60-nm-thick n-type oxide thin-film layer and a 0.2-mm-thick Cu2O:Na sheet with the optimized resistivity.

A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminium garnet laser for the treatment of café-au-lait macules.

PubMed

Kim, Hyeong-Rae; Ha, Jeong-Min; Park, Min-Soo; Lee, Young; Seo, Young-Joon; Kim, Chang-Deok; Lee, Jeung-Hoon; Im, Myung

2015-09-01

Café-au-lait macules (CALMs) are a common pigmentary disorder. Although a variety of laser modalities have been used to treat CALMs, their efficacies vary and dyspigmentation may develop. We evaluated the clinical efficacy and safety of a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminium garnet (Nd:YAG) laser for the treatment of CALMs. In a preliminary investigation, 6 patients underwent a split-lesion comparative study with 532- and 1064-nm Q-switched Nd:YAG laser treatment. In total, 32 patients with 39 CALMs were enrolled in a subsequent prospective trial to evaluate the treatment with a low-fluence 1064-nm Q-switched Nd:YAG laser. In the preliminary study, the 1064-nm treatment group had a more favorable response and a shorter recovery time. In a subsequent prospective trial of a 1064-nm laser, 74.4% of the lesions showed a clinical response with clearance of ≥50.0%. The treatment regimen was well tolerated; 15.4% of patients experienced adverse events. The study participants were followed for 6 months, and there were no relevant treatment controls in the prospective trial group. Low-fluence 1064-nm Q-switched Nd:YAG laser therapy afforded good clinical improvement for treating CALMs. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2002-04-01

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

On fabrication procedures of Li-ion conducting garnets

NASA Astrophysics Data System (ADS)

Hanc, Emil; Zając, Wojciech; Lu, Li; Yan, Binggong; Kotobuki, Masashi; Ziąbka, Magdalena; Molenda, Janina

2017-04-01

Ceramic oxides exhibiting high lithium-ion mobility at room temperature receive broad attention as candidate electrolytes for lithium batteries. Lithium-stuffed garnets from the Li7La3Zr2O12 group seem to be especially promising because of their high ionic conductivity at room temperature and their electrochemical stability. In this work, we discuss factors that affect formation of the garnet in its bulk form or in the form of thick and thin films. We demonstrate that zinc oxide can be applied as a sintering aid that facilitate the formation of the highly conducting cubic Li7La3Zr2O12 garnet phase in a single-step sintering procedure. Based on our experience with the single-step sintering experiments, we successfully fabricated a thick-film membrane consisting of a garnet solid electrolyte using the tape casting technique. In order to reduce the thickness of the electrolyte even further we investigated the fabrication of a thin-film Li7La3Zr2O12 electrolyte by means of the pulsed laser deposition technique.

Gallium-67 activity in bronchoalveolar lavage fluid in sarcoidosis

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

Trauth, H.A.; Heimes, K.; Schubotz, R.

1986-01-01

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

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2007-01-01

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.

Unraveling the history of complex zoned garnets from the North Motagua Mélange (Guatemala)

NASA Astrophysics Data System (ADS)

Barickman, M. H.; Martin, C.; Flores, K. E.; Harlow, G. E.; Bonnet, G.

2016-12-01

The Guatemala Suture Zone (GSZ) is situated in central Guatemala, between the North American and Caribbean plates. Two serpentinite mélanges straddle the Motagua Fault system: the North Motagua Mélange (NMM) and the South Motagua Mélange (SMM). In this study, chemically zoned garnet grains from four eclogite blocks from the NMM were analyzed by EMPA for major elements and LA-ICP-MS for trace elements to unravel the geological history of the eclogites. These eclogites typically consist of euhedral to subhedral garnets, partly retrogressed omphacite grains, and accessory minerals such as phengite and epidote as inclusions in garnet. EBSD was employed to examine apparent garnet inclusions in garnet. The garnet grains in NMM eclogites display complex chemical zonations: all grains roughly show a spessartine-rich core, an almandine-rich core and/or intermediate zone, and a pyrope and grossular-rich rim. Additionally, crystal resorption can be observed between the different zones, and the pyrope-grossular rim can display oscillatory zoning. Finally, grossular-rich zones (crystallographically syntactic) within garnet are present in all studied samples. REE and spider diagrams do not show any significant difference in the patterns of the different zones within the garnet, or indicating that the chemical environment from which each garnet zone grew was broadly the same. The lack of significant variation in LILE content indicates that a fluid influx during garnet growth is unlikely. Consequently, we interpret that garnet grains grew in a largely closed system; however, the presence of the grossular-rich zones, argues for occasional excursions into conditions when either two garnets crystallized or Ca-rich overgrowths that were largely resorbed prior to subsequent continued garnet growth.

A Program of Research on Microfabrication Techniques for VLSI Magnetic Devices.

DTIC Science & Technology

1982-10-01

contribution to the implantation- induced uniaxial anisotropy field change. BACKGROUND Magnetic garnet films are grown by liquid phase epitaxy ( LPE ) on non...a single crystal, non-magnetic garnet substrate by the liquid phase epitaxy ( LPE ) method. These thin films , usually one to three microns in thickness...microscopy. Experimental Procedures Films of (SmYGdTm)3Ca0a.Fe4.6012 garnet were grown by liquid phase epitaxy ( LPE ) on gadolinium-gallium garnet (GGG

The Garnet to Majorite Transformation in Mafic Compositions

NASA Technical Reports Server (NTRS)

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

2002-01-01

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.

Different origins of garnet in high pressure to ultrahigh pressure metamorphic rocks

NASA Astrophysics Data System (ADS)

Xia, Qiong-Xia; Zhou, Li-Gang

2017-09-01

Garnet in high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks in subduction zone commonly shows considerable zonation in major and trace elements as well as mineral inclusions, which bears information on its growth mechanism via metamorphic or peritectic reactions in coexistence with relic minerals and metamorphic fluids or anatectic melts at subduction-zone conditions. It provides an important target to retrieve physicochemical changes in subduction-zone processes, including those not only in pressure and temperature but also in the durations of metamorphism and anatexis. Garnet from different compositions of HP to UHP metamorphic rocks may show different types of major and trace element zonation, as well as mineral inclusions. Discrimination between the different origins of garnet provides important constraints on pressure and temperature and the evolution history for the HP to UHP metamorphic rocks. Magmatic garnet may occur as relics in granitic gneisses despite metamorphic modification at subduction-zone conditions, with spessartine-increasing or flat major element profiles from inner to outer core and exceptionally higher contents of trace elements than metamorphic mantle and rim. Metamorphic garnet can grow at different metamorphic stages during prograde subduction and retrograde exhumation, with spessartine-decreasing from core to rim if the intracrystalline diffusion is not too fast. The compositional profiles of metamorphic garnet in the abundances of grossular, almandine and pyrope are variable depending on the composition of host rocks and co-existing minerals. Peritectic garnet grows through peritectic reactions during partial melting of HP to UHP rocks, with the composition of major elements to be controlled by anatectic P-T conditions and the compositions of parental rocks and anatectic melts. Trace element profiles in garnet with different origins are also variable depending on the coexisting mineral assemblages, the garnet

Pulmonary Laser Metastasectomy by 1318-nm Neodymium-Doped Yttrium-Aluminum Garnet Laser: A Retrospective Study About Laser Metastasectomy of the Lung.

PubMed

Porrello, Calogero; Gullo, Roberto; Vaglica, Antonino; Scerrino, Gregorio; Salamone, Giuseppe; Licari, Leo; Raspanti, Cristina; Gulotta, Eliana; Gulotta, Gaspare; Cocorullo, Gianfranco

2018-04-01

The lungs are among the first organ affected by remote metastases from many primary tumors. The surgical resection of isolated pulmonary metastases represents an important and effective element of therapy. This is a retrospective study about our entire experience with pulmonary resection for metastatic cancer using 1318-nm neodymium-doped yttrium-aluminum garnet laser. In this single-institution study, we retrospectively analyzed a group of 209 patients previously treated for primary malignant solid tumors. We excluded 103 patients. The number and location of lesions in the lungs was determined using chest computed tomography and positron emission tomography-computed tomography. Disseminated malignancy was excluded. All pulmonary laser resections are performed via an anteroaxillary muscle-sparing thoracotomy. All lesions were routinely removed by laser with a small (5-10 mm) margin of the healthy lung. Patients received systematic lymph node sampling with intraoperative smear cytology of sampled lymph nodes. Mortality at 2 years from the first surgery is around 20% (10% annually). This value increases to 45% in the third year. The estimated median survival for patients who underwent the first surgery is reported to be approximately 42 months. Our results show that laser resection of lung metastases can achieve good result, in terms of radical resection and survival, as conventional surgical metastasectomy. The great advantage is the possibility of limiting the damage to the lung. Stapler resection of a high number of metastases would mutilate the lung.

Mixed Messages from Garnet Lu-Hf and Sm-Nd Geochronology

NASA Astrophysics Data System (ADS)

Vervoort, J. D.; Wang, D.; Johnson, T. A.

2017-12-01

Garnet geochronology provides important information on the timing and conditions of metamorphism. As a major indicator mineral formed during metamorphism, its direct dating can not only help establish the timing of metamorphism, provide the "t" for P-T-t paths, but also, if the dated garnet can be placed in a textural context, can provide information on the timing of deformational features. With advances in chemistry and mass spectrometry, garnet Lu-Hf and Sm-Nd geochronology has become an important geochronological tool and we can now reliably (if not routinely) date a wide variety of garnet compositions formed under diverse conditions. In the course of dating a variety of lithologies using both Lu-Hf and Sm-Nd isotope systems, however, some intriguing results have emerged. Although there are many examples where the Lu-Hf and Sm-Nd systems give the same date within uncertainty, there are also many cases where these systems yield significantly different dates, and the differences between these dates can be considerable—many 10's of Ma of and even 100's of Ma. For example, in garnet-bearing Mesoproterozoic gneisses from across the Blue Ridge Province in Virginia, both Lu-Hf and Sm-Nd analyses (determined on the same solutions) define narrow time spans, but with the Sm-Nd dates systematically younger (for orthogneisses Lu-Hf dates are 1032 to 1019 Ma whereas Sm-Nd dates are 965 to 949 Ma—a difference of 67 to 80 Ma). There are many other examples of systematically younger Sm-Nd garnet dates in both the literature and with our ongoing research. Potential explanations for these differences include: 1) strong partitioning of Lu into garnet during growth yielding ages weighted toward the beginning of growth; 2) faster Lu diffusion from high Lu regions after garnet formation, potentially leading to isochron rotation and anomalously old Lu-Hf dates; and 3) differences in closure temperatures of the two isotope systems. We will review several examples of divergent Lu

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

USGS Publications Warehouse

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

2010-01-01

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

Aging Effects on the Structural and Magnetic Properties of Terbium-Aluminium Co-doping of Yttrium Iron Garnet Films Prepared Using the Sol-Gel Method

NASA Astrophysics Data System (ADS)

Aldbea, Ftema W.; Yusrianto, Efil; Ibrahim, N. B.

2018-06-01

The terbium-aluminium co-doped yttrium iron garnet (Tb0.2Y2.8Al1Fe4O12) nanoparticles films, prepared via a sol-gel method, were aged variously for 2 days, 3 days, 4 days and 5 days. The films were deposited on quartz substrates using a spin coating technique then annealed at 900°C in air for 2 h. The microstructural and magnetic properties of the films were measured using an x-ray diffractometer (XRD), a field emission scanning electron microscope and a vibrating sample magnetometer. The XRD results showed that all the resultant films were a single phase regardless of aging time. A change in the lattice parameter's behavior was observed at the longer aging times. At an aging time of 5 days, the films became highly agglomerated and exhibited the greatest thickness value of 458.9 nm. The saturation magnetization, M s, of the films decreased from 31 kA/m to 6 kA/m as the aging time was increased from 2 days to 5 days, due to the increasing Fe-O bond length resulting from larger grain sizes. The increase in aging time to 5 days caused a reduction in the coercivity, H c, of films due to the multi-domain formation.

Garnet: featured mineral group at the 1993 Tucson Show

USGS Publications Warehouse

Modreski, P.J.

1993-01-01

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

Low-temperature processed Ga-doped ZnO coatings from colloidal inks.

PubMed

Della Gaspera, Enrico; Bersani, Marco; Cittadini, Michela; Guglielmi, Massimo; Pagani, Diego; Noriega, Rodrigo; Mehra, Saahil; Salleo, Alberto; Martucci, Alessandro

2013-03-06

We present a new colloidal synthesis of gallium-doped zinc oxide nanocrystals that are transparent in the visible and absorb in the near-infrared. Thermal decomposition of zinc stearate and gallium nitrate after hot injection of the precursors in a mixture of organic amines leads to nanocrystals with tunable properties according to gallium amount. Substitutional Ga(3+) ions trigger a plasmonic resonance in the infrared region resulting from an increase in the free electrons concentration. These nanocrystals can be deposited by spin coating, drop casting, and spray coating resulting in homogeneous and high-quality thin films. The optical transmission of the Ga-ZnO nanoparticle assemblies in the visible is greater than 90%, and at the same time, the near-infrared absorption of the nanocrystals is maintained in the films as well. Several strategies to improve the films electrical and optical properties have been presented, such as UV treatments to remove the organic compounds responsible for the observed interparticle resistance and reducing atmosphere treatments on both colloidal solutions and thin films to increase the free carriers concentration, enhancing electrical conductivity and infrared absorption. The electrical resistance of the nanoparticle assemblies is about 30 kΩ/sq for the as-deposited, UV-exposed films, and it drops down to 300 Ω/sq after annealing in forming gas at 450 °C, comparable with state of the art tin-doped indium oxide coatings deposited from nanocrystal inks.

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

Carbon nanothermometer containing gallium.

PubMed

Gao, Yihua; Bando, Yoshio

2002-02-07

Many applications have been found for carbon nanotubes, and we can now add a role as a 'nanothermometer' to this list. We describe how the height of a continuous, unidimensional column of liquid gallium inside a carbon nanotube (up to about 10 micrometres long and about 75 nanometres in diameter) varies linearly and reproducibly in the temperature range 50-500 degrees C, with an expansion coefficient that is the same as for gallium in the macroscopic state. We chose gallium as our thermal indicator because it has one of the greatest liquid ranges of any metal (29.78-2,403 degrees C) and a low vapour pressure even at high temperatures. This nanothermometer should be suitable for use in a wide variety of microenvironments.

Gallium Electromagnetic (GEM) Thrustor Concept and Design

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Markusic, Thomas E.

2006-01-01

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

Insights into the mantle geochemistry of scandium from a meta-analysis of garnet data

NASA Astrophysics Data System (ADS)

Chassé, Mathieu; Griffin, William L.; Alard, Olivier; O'Reilly, Suzanne Y.; Calas, Georges

2018-06-01

The meta-analysis of about 13,000 analyses of scandium content in garnet grains shows that, below the spinel-garnet transition, this phase carries about three-quarters of the Sc budget of the mantle, indicating its control on Sc mobility. The Sc content of garnets in mafic rocks is low, due to a dilution effect resulting from their high modal content in garnet. Garnets from ultramafic rocks exhibit a wider range of Sc concentrations. We assess the relative influence of thermobarometry, crystal chemistry and fluid-related events on the distribution of Sc in garnet from such rocks to improve the tracking of geochemical processes in the mantle. Pressure and temperature of equilibration in the mantle are second-order factors influencing the Sc content of garnet, while crystal chemistry, in particular Cr/Cr+Al and Ca/Ca+Mg, is the main parameter controlling the compatibility of Sc. Scandium is incorporated in both X and Y sites of Cr-Ca-rich garnets, resulting in a behaviour intermediate between rare-earth elements, incorporated in the X site, and trivalent transition elements, occupying the Y site. This affinity for both sites results in a mild compatibility of Sc in the garnet stability field of the mantle; hence Sc concentration in garnet increases with melt extraction and can be reduced by silicate-melt metasomatism. In contrast, metasomatism by volatile-rich fluids increases the Sc concentration in garnet. The control of garnet on the compatibility of Sc in deep lithospheric rocks demonstrates the potential of using Sc to track the conditions of formation of magmas and their residual rocks, as well as the origin and nature of metasomatic fluids.

Study of the thermoelectric properties of lead selenide doped with boron, gallium, indium, or thallium.

PubMed

Zhang, Qian; Cao, Feng; Lukas, Kevin; Liu, Weishu; Esfarjani, Keivan; Opeil, Cyril; Broido, David; Parker, David; Singh, David J; Chen, Gang; Ren, Zhifeng

2012-10-24

Group IIIA elements (B, Ga, In, and Tl) have been doped into PbSe for enhancement of thermoelectric properties. The electrical conductivity, Seebeck coefficient, and thermal conductivity were systematically studied. Room-temperature Hall measurements showed an effective increase in the electron concentration upon both Ga and In doping and the hole concentration upon Tl doping to ~7 × 10(19) cm(-3). No resonant doping phenomenon was observed when PbSe was doped with B, Ga, or In. The highest room-temperature power factor ~2.5 × 10(-3) W m(-1) K(-2) was obtained for PbSe doped with 2 atom % B. However, the power factor in B-doped samples decreased with increasing temperature, opposite to the trend for the other dopants. A figure of merit (ZT) of ~1.2 at ~873 K was achieved in PbSe doped with 0.5 atom % Ga or In. With Tl doping, modification of the band structure around the Fermi level helped to increase the Seebeck coefficient, and the lattice thermal conductivity decreased, probably as a result of effective phonon scattering by both the heavy Tl(3+) ions and the increased grain boundary density after ball milling. The highest p-type ZT value was ~1.0 at ~723 K.

Ultra-low power fiber-coupled gallium arsenide photonic crystal cavity electro-optic modulator.

PubMed

Shambat, Gary; Ellis, Bryan; Mayer, Marie A; Majumdar, Arka; Haller, Eugene E; Vučković, Jelena

2011-04-11

We demonstrate a gallium arsenide photonic crystal cavity injection-based electro-optic modulator coupled to a fiber taper waveguide. The fiber taper serves as a convenient and tunable waveguide for cavity coupling with minimal loss. Localized electrical injection of carriers into the cavity region via a laterally doped p-i-n diode combined with the small mode volume of the cavity enable ultra-low energy modulation at sub-fJ/bit levels. Speeds of up to 1 GHz are demonstrated with photoluminescence lifetime measurements revealing that the ultimate limit goes well into the tens of GHz. © 2011 Optical Society of America

Gallium poisoning: a rare case report.

PubMed

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

2012-02-01

The authors present a case of a college student who suffered acute gallium poisoning as a result of accidental exposure to gallium halide complexes. This is extremely rare and has never been reported in the literature. Acute symptoms after the incident, which initially presented as dermatitis and appeared relatively not life-threatening, rapidly progressed to dangerous episodes of tachycardia, tremors, dyspnea, vertigo, and unexpected black-outs. Had there been effective emergency medical care protocols, diagnostic testing, treatment and antidotes, the latent manifestations of irreversible cardiomyopathy may have been prevented. Given how quickly exposure led to morbidity, this article aims to raise an awareness of the toxic potential of gallium. This has particular relevance for workers involved in the production of semiconductors where there is a potential for accidental exposure to gallium by-products during device processing. It may also have implications for dentists who use gallium alloys to replace mercury containing amalgam. In the absence of threshold limit values and exposure limits for humans, as well as emergency medical guidelines for treatment of poisoning, the case calls on the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration to establish guidelines and medical management protocols specific for gallium. Copyright © 2011 Elsevier Ltd. All rights reserved.

Dual doped monolayer and bilayer graphene: The case of 4p and 2p elements

NASA Astrophysics Data System (ADS)

Denis, Pablo A.; Iribarne, Federico

2016-08-01

4p/2p dual-doped monolayer and bilayer graphene were studied via first principle calculations. Generally, dopants prefer to be agglomerated. A second dopant significantly reduces formation energies. Thus, partially reduced graphene oxide would favor substitutional doping by facilitating the introduction of the 4p dopants. Dual-doping can tune the band gap from 0.1 to 0.8 eV. For bilayer graphene, large atomic radii elements (Gallium and Germanium) form interlayer bonds with the undoped sheet. For some dual-doped graphenes, interlayer GaC and GeC bonds were formed, increasing the chemical reactivity of the undoped layer and affecting its electronic structure, with metallic or semiconducting characters observed.

Determination of the ferrimagnetic precession cone of in-plane magnetized garnet films using optical modulation technique

NASA Astrophysics Data System (ADS)

Bahlmann, N.; Gerhardt, R.; Wallenhorst, M.; Dötsch, H.

1996-10-01

Magnetic garnet films of composition (A, Bi)3(Fe, B)5 O12 are grown by liquid phase epitaxy on [111] oriented substrates of Gd3 Ga5 O12, where A=yttrium or lutetium and B=aluminum or gallium. The ferrimagnetic resonance (FMR) of in-plane magnetized films is studied by analyzing the modulation of light, which passes the film parallel to the film normal. Modulation efficiencies up to 1.8% at 2.9 GHz are observed at a wavelength of 0.633 μm. From the measured modulation intensities the precession angles of the FMR are derived. The dependence of the precession cone on the excitation frequency or on the external induction shows a foldover effect which, however, is smaller than for the FMR of perpendicularly magnetized films. Maximum precession angles up to 14° are achieved and the experiments indicate that saturation occurs. Light modulation is also observed at the first harmonic frequency, but the intensity is about 300 times weaker than at the fundamental frequency.

Gallium-based anti-infectives: targeting microbial iron-uptake mechanisms.

PubMed

Kelson, Andrew B; Carnevali, Maia; Truong-Le, Vu

2013-10-01

Microbes have evolved elaborate iron-acquisition systems to sequester iron from the host environment using siderophores and heme uptake systems. Gallium(III) is structurally similar to iron(III), except that it cannot be reduced under physiological conditions, therefore gallium has the potential to serve as an iron analog, and thus an anti-microbial. Because Ga(III) can bind to virtually any complex that binds Fe(III), simple gallium salts as well as more complex siderophores and hemes are potential carriers to deliver Ga(III) to the microbes. These gallium complexes represent a new class of anti-infectives that is different in mechanism of action from conventional antibiotics. Simple gallium salts such as gallium nitrate, maltolate, and simple gallium siderophore complexes such as gallium citrate have shown good antibacterial activities. The most studied complex has been gallium citrate, which exhibits broad activity against many Gram negative bacteria at ∼1-5μg/ml MICs, strong biofilm activity, low drug resistance, and efficacy in vivo. Using the structural features of specific siderophore and heme made by pathogenic bacteria and fungi, researchers have begun to evaluate new gallium complexes to target key pathogens. This review will summarize potential iron-acquisition system targets and recent research on gallium-based anti-infectives. Copyright © 2013 Elsevier Ltd. All rights reserved.

Distribution of garnet grain sizes and morphologies across the Moine Supergroup, northern Scottish Caledonides

NASA Astrophysics Data System (ADS)

Ashley, Kyle T.; Thigpen, J. Ryan; Law, Richard D.

2016-04-01

Garnet is used in a wide range of geologic studies due to its important physical and chemical characteristics. While the mineral is useful for thermobarometry and geochronology constraints and can often be correlated to deformation and fabric development, difficulties remain in making meaningful interpretations of such data. In this study, we characterize garnet grain sizes and crystal morphologies from 141 garnet-bearing metasedimentary rock samples collected from the northern part of the Moine Supergroup in the Scottish Caledonides. Larger, euhedral crystals are indicative of prograde metamorphic growth and are typically associated with the most recent phase of orogenesis (Scandian, ˜430 Ma). Small, rounded ("pin-head") garnets are interpreted as detrital in origin. A subhedral classification is more subjective and is used when garnets contains portions of straight boundaries but have rounded edges or rims that have been altered through retrograde metamorphic reactions. From our collection, 88 samples contain anhedral garnets (maximum measured grain size d = 0.46 ± 0.21 mm), 34 bear subhedral garnets (d = 2.0 ± 1.0 mm), and the remaining 19 samples contain garnets with euhedral grains (d = 4.4 ± 2.6 mm). Plotting the distribution of garnets relative to the mapped thrust contacts reveals an abrupt change in morphology and grain size when traced from the Moine thrust sheet across the Ben Hope and Sgurr Beag thrusts into the higher-grade, more hinterland-positioned thrust sheets. The dominance of anhedral garnets in the Moine thrust sheet suggests that these grains should not be used for peak P - T estimation associated with relatively low temperature (<500 ° C) Scandian metamorphism, as they are likely detrital in origin and contain protolith chemical signatures that would not have been reset due to sluggish diffusivities at greenschist facies temperatures. However, chemical and isotopic data from these grains may provide information into the provenance of

Large Screen Display Technology Survey.

DTIC Science & Technology

1984-07-01

gadolinium gallium garnet ). The film is etched to form small light sensitive cells. The area between the cells is covered with a metal film to block the light...Failures MTTR - Mean-Time-To-Repair Nd:YAG - Noedymium: Yttrium Aluminum Garnet Nematic - A term used to describe one of the states of certain liquid...valve within a display, projection or optical processing system. It uses garnet films grown on non-magnetic substrates (Figure 10). The garnet films can

An inverse modeling strategy and a computer program to model garnet growth and resorption

NASA Astrophysics Data System (ADS)

Lanari, Pierre; Giuntoli, Francesco

2017-04-01

GrtMod is a computer program that allows numerical simulation of the pressure-temperature (P-T) evolution of garnet porphyroblasts based on the composition of successive growth zones preserved in natural samples. For each garnet growth stage, a new reactive bulk composition is optimized, allowing for resorption and/or fractionation of the previously crystalized garnet. The successive minimizations are performed using a heuristic search method and an objective function that quantify the amount by which the predicted garnet composition deviates from the measured values. The automated strategy of GrtMod includes a two stages optimization and one refinement stage. In this contribution, we will present several application examples. The new strategy provides quantitative estimates of the optimal P-T conditions whereas it was generally derived in a qualitatively way by using garnet isopleth intersections in equilibrium phase diagrams. GrtMod can also be used to model the evolution of the reactive bulk composition along any P-T trajectories. The results for typical MORB and metapelite compositions demonstrate that fractional crystallization models are required to derive accurate P-T information from garnet compositional zoning. GrtMod can also be used to retrieve complex garnet histories involving several stages of resorption. For instance, it has been used to model the P-T condition of garnet growth in grains from the Sesia Zone (Western Alps). The compositional variability of successive growth zones is characterized using standardized X-ray maps and the program XMapTools. Permian garnet cores crystalized under granulite facies conditions (T > 800°C and P = 6 kbar), whereas Alpine garnet rims grew at eclogite facies conditions (650°C and 16 kbar) involving several successive episodes of resorption. The model predicts that up to 50 vol% of garnet was dissolved before a new episode of garnet growth.

Growth-induced anisotropy in bismuth - Rare-earth iron garnets

NASA Technical Reports Server (NTRS)

Fratello, V. J.; Slusky, S. E. G.; Brandle, C. D.; Norelli, M. P.

1986-01-01

The bismuth-doped rare-earth iron garnets, (R3-x-yBixPby)Fe5O12 (Bi:RIG, R = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), were prepared under constant growth conditions to investigate the influence of ionic species on the bismuth-based growth-induced uniaxial anisotropy K(u) exp g. The effect of ionic species on growth-induced anisotropy in Bi:RIG was not consistent with the ionic size model of site ordering. In particular, Bi:SmIG, Bi:EuIG, and Bi:TbIG displayed high growth-induced anisotropies, up to 331,000 erg/cu cm at room temperature for x of about 0.5. The temperature dependence of these K(u) exp gs was somewhat higher than that of the well studied Bi:YIG. The site ordering of Bi can be modeled by assuming that small, low-oxygen-coordination BiOw exp +3-2 w melt complexes have a strong site selectivity for small, high-oxygen coordination sites at the growth interface.

Correction: Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control.

PubMed

Sarkar, Sujoy; Sampath, S

2016-05-28

Correction for 'Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control' by Sujoy Sarkar et al., Chem. Commun., 2016, 52, 6407-6410.

Studies on gallium nitride doped ferrite-polypyrrole nanocomposites

NASA Astrophysics Data System (ADS)

Indrakanti, Rajani; Brahmaji Rao, V.; Udaya Kiran, C.

2018-06-01

This communication reports the synthesis and characterisation of two novel Intrinsic conducting polymer nano composites (ICPN s) with the formulae Ga (2x+2) N Fe 2(49-x) O3—PPY synthesized using Impregnation technique. The Gallium nitride ferrite nano particles were synthesized for x = 1 and x = 5 using the above stichiometric equation earlier by Sol—Gel route. The chemical composition in the assembly of the ICPNs were Ga4NFe96O3-3%,10%,30% Polypyrrole, Ga12NFe88O3-3%,10%,30% Polypyrrole by weight. The Sci-Finder software failed to trace any earlier articles or reviews related to these ICNPs synthesised by us in the literature. X-ray Diffractometric (Structural), Morphological, EDAX SAED, IR spectroscopic characterizations were done on the synthesized nanocomposites. Structural studies reveal the semi-crystalline nature of composites. The average crystallite size of nano composites is decreased when compared with nano ferrites. SEM findings reveal that the shape for higher percentage of PPY is nano rods; for lower percentage it is globular. TEM reveals good dispersion and average particle size from histograms are calculated. The FT- IR bands of PPY and GaNFe2O3 are observed which show strong interaction between PPY- GaNFe2O3. Also there is a shift of bands in GaNFe2O3-PPY nano composites when compared to the bands of PPY.

Revised neutrino-gallium cross section and prospects of BEST in resolving the gallium anomaly

NASA Astrophysics Data System (ADS)

Barinov, Vladislav; Cleveland, Bruce; Gavrin, Vladimir; Gorbunov, Dmitry; Ibragimova, Tatiana

2018-04-01

O (1 )eV sterile neutrino can be responsible for a number of anomalous results of neutrino oscillation experiments. This hypothesis may be tested at short base line neutrino oscillation experiments, several of which are either ongoing or under construction. Here, we concentrate on the so-called gallium anomaly, found by SAGE and GALLEX experiments, and its foreseeable future tests with BEST experiment at Baksan Neutrino Observatory. We start with a revision of the neutrino-gallium cross section that is performed by utilizing the recent measurements of the nuclear final state spectra. We accordingly correct the parameters of gallium anomaly and refine the BEST prospects in testing it and searching for sterile neutrinos. We further evolve the previously proposed idea to investigate the anomaly with 65Zn artificial neutrino source as a next option available at BEST and estimate its sensitivity to the sterile neutrino model parameters following the Bayesian approach. We show that after the two stages of operation BEST will make 5 σ discovery of the sterile neutrinos, if they are behind the gallium anomaly.

A high open-circuit voltage gallium nitride betavoltaic microbattery

NASA Astrophysics Data System (ADS)

Cheng, Zaijun; Chen, Xuyuan; San, Haisheng; Feng, Zhihong; Liu, Bo

2012-07-01

A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p-i-n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63Ni source with activity of 0.5 mCi, the open-circuit voltage of the fabricated microbattery with 2 × 2 mm2 area reaches as much as 1.64 V, which is the record value reported for betavoltaic batteries with 63Ni source, the short-circuit current was measured as 568 pA and the conversion effective of 0.98% was obtained. The experimental results suggest that GaN is a high-potential candidate for developing the betavoltaic microbattery.

A I-V analysis of irradiated Gallium Arsenide solar cells

NASA Technical Reports Server (NTRS)

Heulenberg, A.; Maurer, R. H.; Kinnison, J. D.

1991-01-01

A computer program was used to analyze the illuminated I-V characteristics of four sets of gallium arsenide (GaAs) solar cells irradiated with 1-MeV electrons and 10-MeV protons. It was concluded that junction regions (J sub r) dominate nearly all GaAs cells tested, except for irradiated Mitsubishi cells, which appear to have a different doping profile. Irradiation maintains or increases the dominance by J sub r. Proton irradiation increases J sub r more than does electron irradiation. The U.S. cells were optimized for beginning of life (BOL) and the Japanese for end of life (EOL). I-V analysis indicates ways of improving both the BOL and EOL performance of GaAs solar cells.

Serum and tissue concentrations of gallium after oral administration of gallium nitrate and gallium maltolate to neonatal calves.

PubMed

Monk, Caroline S; Sweeney, Raymond W; Bernstein, Lawrence R; Fecteau, Marie-Eve

2016-02-01

To determine serum and tissue concentrations of gallium (Ga) after oral administration of gallium nitrate (GaN) and gallium maltolate (GaM) to neonatal calves. 8 healthy neonatal calves. Calves were assigned to 1 of 2 groups (4 calves/group). Gallium (50 mg/kg) was administered as GaN or GaM (equivalent to 13.15 mg of Ga/kg for GaN and 7.85 mg of Ga/kg for GaM) by oral gavage once daily for 5 days. Blood samples were collected 0, 0.25, 0.5, 1, 2, 4, 8, 12, and 24 hours after Ga administration on day 1; 4 and 24 hours after Ga administration on days 2, 3, and 4; and 4, 12, and 24 hours after Ga administration on day 5. On day 6, calves were euthanized and tissue samples were obtained. Serum and tissue Ga concentrations were measured by use of mass spectrometry. Data were adjusted for total Ga dose, and comparisons were made between the 2 groups. Calves receiving GaM had a significantly higher dose-adjusted area under the curve and dose-adjusted maximum serum Ga concentration than did calves receiving GaN. Despite receiving less Ga per dose, calves receiving GaM had tissue Ga concentrations similar to those for calves receiving GaN. In this study, calves receiving GaM had significantly higher Ga absorption than did calves receiving GaN. These findings suggested that GaM might be useful as a prophylactic agent against Mycobacterium avium subsp paratuberculosis infection in neonatal calves.

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

USGS Publications Warehouse

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

1992-01-01

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

Garnet Random-Access Memory

NASA Technical Reports Server (NTRS)

Katti, Romney R.

1995-01-01

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.

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

NASA Astrophysics Data System (ADS)

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

2009-10-01

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

Structure of dental gallium alloys.

PubMed

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

1996-07-01

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

Melanogenesis inhibition in mice using a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser: a pilot study.

PubMed

Nam, Jae-Hui; Min, Joon Hong; Kim, Wang-Kyun; Yim, Sunmin; Kim, Won-Serk

2017-07-01

A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, or laser toning, has yielded favorable outcomes in various benign pigmented disorders. However, the exact mechanism of action of laser toning has not been fully elucidated. We sought to determine the inhibitory effect of laser toning on melanogenesis and to assess how laser passes influence the outcomes. To produce perceptible pigmentation, nine HRM-2 melanin-possessing hairless mice were treated with ultraviolet (UV) B radiation on the dorsal skin. This was followed by zero, two, four, or six passes of laser toning twice in 2 weeks on each designated quadrant. The spectrophotometric values and pigmentation-related protein expressions were measured. Pigment changes were found in the mice skin using the Fontana-Masson stain for histopathological analysis. Four- and six-pass laser toning significantly improved the lightness compared to that in the unirradiated control (p < 0.002). The Fontana-Masson stain showed that melanin was considerably decreased in laser-irradiated skin. As the number of laser passes increased, the expression of tyrosinase decreased (p < 0.008). The following parameters also decreased in proportion to the number of laser passes: MITF, TRP-1, TRP-2, p-ERK, and p-Akt. In contrast, TGF-β increased in proportion to the number of laser passes. However, the changes in these six proteins were not statistically significant. Our study demonstrates that laser toning improves skin pigmentation with increased number of passes in a dose-dependent manner. This effect is mediated by tyrosinase inhibition.

The potential of detrital garnet as a provenance proxy in the Central Swiss Alps

NASA Astrophysics Data System (ADS)

Stutenbecker, Laura; Berger, Alfons; Schlunegger, Fritz

2017-04-01

Detrital garnet is a promising candidate to reliably fingerprint sediment sources in the Alps, which has so far been complicated by the wide range and similarity of some of the lithologies. Garnet is present in most Alpine sediments, is easy to identify, is fairly stable and, most importantly, reflects the type and the metamorphic grade of its source rock in its chemical composition. This study aims to establish fingerprints based on detrital garnet composition for the most important tectonic units of the Central Alps, including European, Penninic and Adriatic basement rocks and their respective metasedimentary covers. Sediments collected from modern rivers, which drain representative portions of the individual tectonic units, contain a natural mixture of the various garnet populations present in each unit. We selected six catchments in southwestern Switzerland draining the External massifs, Helvetic sediments and the Penninic nappe stack at the transition of Alpine greenschist- to amphibolite-facies metamorphism in order to test the variability of Alpine garnets and the role of inherited (pre-Alpine) garnets. Extraordinary grossular- and spessartine-rich garnets of the External massifs, which experienced greenschist facies metamorphism, are clearly distinguishable from generally almandine-rich garnets supplied by the higher-grade metamorphic Penninic nappe stack. The variable pyrope, grossular and spessartine components of these almandine-rich garnets can be used to further distinguish pre-Alpine, Alpine eclogite-facies and low-grade metasedimentary garnets. This provenance proxy has the potential to be used for reconstructing sediment sources, transport and dispersal patterns in a variety of settings throughout the Alpine sedimentary record.

Ultrafast electronic dynamics in unipolar n-doped indium gallium arsenide/gallium arsenide self-assembled quantum dots

NASA Astrophysics Data System (ADS)

Wu, Zong-Kwei J.

2006-12-01

Photodetectors based on intraband infrared absorption in the quantum dots have demonstrated improved performance over its quantum well counterpart by lower dark current, relative temperature insensitivity, and its ability for normal incidence operation. Various scattering processes, including phonon emission/absorption and carrier-carrier scattering, are critical in understanding device operation on the fundamental level. In previous studies, our group has investigated carrier dynamics in both low- and high-density regime. Ultrafast electron-hole scattering and the predicted phonon bottleneck effect in intrinsic quantum dots have been observed. Further examination on electron dynamics in unipolar structures is presented in this thesis. We used n-doped quantum dot in mid-infrared photodetector device structure to study the electron dynamics in unipolar structure. Differential transmission spectroscopy with mid-infrared intraband pump and optical interband probe was implemented to measure the electron dynamics directly without creating extra electron-hole pair, Electron relaxation after excitation was measured under various density and temperature conditions. Rapid capture into quantum dot within ˜ 10 ps was observed due to Auger-type electron-electron scattering. Intradot relaxation from the quantum dot excited state to the ground state was also observed on the time scale of 100 ps. With highly doped electron density in the structure, the inter-sublevel relaxation is dominated by Auger-type electron-electron scattering and the phonon bottleneck effect is circumvented. Nanosecond-scale recovery in larger-sized quantum dots was observed, not intrinsic to electron dynamics but due to band-bending and built-in voltage drift. An ensemble Monte Carlo simulation was also established to model the dynamics in quantum dots and in goad agreement with the experimental results. We presented a comprehensive picture of electron dynamics in the unipolar quantum dot structure

Gallium and its competing roles with iron in biological systems.

PubMed

Chitambar, Christopher R

2016-08-01

Gallium, a group IIIa metal, shares chemical properties with iron. Studies have shown that gallium-based compounds have potential therapeutic activity against certain cancers and infectious microorganisms. By functioning as an iron mimetic, gallium perturbs iron-dependent proliferation processes in tumor cells. Gallium's action on iron homeostasis leads to disruption of ribonucleotide reductase, mitochondrial function, and the regulation of transferrin receptor and ferritin. In addition, gallium nitrate stimulates an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Gallium's anti-infective activity against bacteria and fungi results from disruption of microbial iron utilization through mechanisms which include gallium binding to siderophores and downregulation of bacterial iron uptake. Gallium compounds lack cross-resistance to conventional chemotherapeutic drugs and antibiotics thus making them attractive agents for drug development. This review will focus on the mechanisms of action of gallium with emphasis on its interaction with iron and iron proteins. Copyright © 2016 Elsevier B.V. All rights reserved.

Preventing Supercooling Of Gallium

NASA Technical Reports Server (NTRS)

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

1994-01-01

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.

Repurposing of gallium-based drugs for antibacterial therapy.

PubMed

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

2014-01-01

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. © 2014 International Union of Biochemistry and Molecular Biology.

NIM Realization of the Gallium Triple Point

NASA Astrophysics Data System (ADS)

Xiaoke, Yan; Ping, Qiu; Yuning, Duan; Yongmei, Qu

2003-09-01

In the last three years (1999 to 2001), the gallium triple-point cell has been successfully developed, and much corresponding research has been carried out at the National Institute of Metrology (NIM), Beijing, China. This paper presents the cell design, apparatus and procedure for realizing the gallium triple point, and presents studies on the different freezing methods. The reproducibility is 0.03 mK, and the expanded uncertainty of realization of the gallium triple point is evaluated to be 0.17 mK (p=0.99, k=2.9). Also, the reproducibility of the gallium triple point was compared with that of the triple point of water.

Boron codoping of Czochralski grown lutetium aluminum garnet and the effect on scintillation properties

NASA Astrophysics Data System (ADS)

Foster, Camera; Koschan, Merry; Wu, Yuntao; Melcher, Charles L.

2018-03-01

Many single crystal scintillators, such as Lu3Al5O12, have intrinsic defects that impede their performance. In addition to doping with activators such as cerium, codoping can be used to improve the scintillation properties of a variety of scintillators. In particular, boron has been shown to improve the light yield, energy resolution, and self-absorption of other garnet scintillators, such as GGAG, when incorporated into the lattice via codoping. In this study, single crystals of LuAG: 0.2 at.% Ce codoped with varying concentrations of boron were grown via the Czochralski method at a rate of 1.2 mm/h. Results will show the effect boron codoping has on the scintillation properties of LuAG: Ce, including light yield, decay time, and self-absorption.

Metastable garnet in oceanic crust at the top of the lower mantle.

PubMed

Kubo, Tomoaki; Ohtani, Eiji; Kondo, Tadashi; Kato, Takumi; Toma, Motomasa; Hosoya, Tomofumi; Sano, Asami; Kikegawa, Takumi; Nagase, Toshiro

As oceanic tectonic plates descend into the Earth's lower mantle, garnet (in the basaltic crust) and silicate spinel (in the underlying peridotite layer) each decompose to form silicate perovskite-the 'post-garnet' and 'post-spinel' transformations, respectively. Recent phase equilibrium studies have shown that the post-garnet transformation occurs in the shallow lower mantle in a cold slab, rather than at approximately 800 km depth as earlier studies indicated, with the implication that the subducted basaltic crust is unlikely to become buoyant enough to delaminate as it enters the lower mantle. But here we report results of a kinetic study of the post-garnet transformation, obtained from in situ X-ray observations using sintered diamond anvils, which show that the kinetics of the post-garnet transformation are significantly slower than for the post-spinel transformation. Although metastable spinel quickly breaks down at a temperature of 1,000 K, we estimate that metastable garnet should survive of the order of 10 Myr even at 1,600 K. Accordingly, the expectation of where the subducted oceanic crust would be buoyant spans a much wider depth range at the top of the lower mantle, when transformation kinetics are taken into account.

Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

PubMed Central

Nur-E-Alam, Mohammad; Vasiliev, Mikhail; Kotov, Viacheslav A.; Balabanov, Dmitry; Akimov, Ilya; Alameh, Kamal

2015-01-01

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed. PMID:28788043

The surface tension of liquid gallium

NASA Technical Reports Server (NTRS)

Hardy, S. C.

1985-01-01

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.

40 CFR 721.10391 - Copper gallium indium selenide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN P-10...

40 CFR 721.10391 - Copper gallium indium selenide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN P-10...

40 CFR 721.10391 - Copper gallium indium selenide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN P-10...

Experimental investigation of Fe3+-rich majoritic garnet and its effect on majorite geobarometer

NASA Astrophysics Data System (ADS)

Tao, Renbiao; Fei, Yingwei; Bullock, Emma S.; Xu, Cheng; Zhang, Lifei

2018-03-01

Majoritic garnet [(Ca, Mg, Fe2+)3(Fe3+, Al, Si)2(SiO4)3] is one of the predominant and important constituents of upper mantle peridotite and ultra-deep subducted slabs. Majoritic substitution in garnet depends on pressure, and it has been used to estimate the formation pressure of natural majoritic garnet. Ferric iron (Fe3+) substitution occurs in natural majoritic garnets from mantle diamonds and shocked meteorites. However, available majorite geobarometers were developed without considering the effect of Fe3+ substitution in the structure. In this study, we systematically synthesized Fe3+- bearing majoritic garnets from 6.5 GPa to 15 GPa to evaluate the effect of Fe3+ on the majorite geobarometer. The Fe3+ contents of synthetic majoritic garnets were analyzed using the "Flank method" with the electron probe microanalyzer (EPMA). The results were compared with those based on the charge balance calculations. From the known synthesis pressures and measured Fe3+ contents, we developed a new majorite geobarometer for Fe3+-bearing majoritic garnets. Our results show that the existing majorite geobarometer, which does not take into account the Fe3+ substitution, could underestimate the formation pressure of majoritic garnets, especially for samples with a high majoritic component.

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

USGS Publications Warehouse

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

2006-01-01

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.

Effect of annealing temperature on surface morphology and ultralow ferromagnetic resonance linewidth of yttrium iron garnet thin film grown by rf sputtering

NASA Astrophysics Data System (ADS)

Cao Van, Phuoc; Surabhi, Srivathsava; Dongquoc, Viet; Kuchi, Rambabu; Yoon, Soon-Gil; Jeong, Jong-Ryul

2018-03-01

We report high-quality yttrium-iron-garnet (YIG; Y3Fe5O12) ultrathin films grown on {111} gadolinium-gallium-garnet (GGG; Gd3Ga5O12) substrates using RF sputtering deposition on an off-stoichiometric target and optimized thermal treatments. We measured a narrow peak-to-peak ferromagnetic resonance linewidth (ΔH) whose minimum value was 1.9 Oe at 9.43 GHz for a 60-nm-thick YIG film. This value is comparable to the most recently published value for a YIG thin film grown by pulsed laser deposition. The temperature dependence of the ΔH was investigated systematically, the optimal annealing condition for our growing condition was 875 °C. Structural analysis revealed that surface roughness and crystallinity played an important role in the observed ΔH broadening. Furthermore, the thickness dependence of the ΔH, which indicated that 60 nm thickness was optimal to obtain narrow ΔH YIG films, was also investigated. The thickness dependence of ΔH was understood on the basis of contributions of surface-associated magnon scattering and magnetic inhomogeneities to the ΔH broadening. Other techniques such as transmission electron microscopy, scanning electron microscopy, and X-ray diffraction were used to study the crystalline structure of the YIG films. The high quality of the films in terms of their magnetic properties was expressed through a very low coercivity and high saturation magnetization measured using a vibration sample magnetometer.

Automated realization of the gallium melting and triple points

NASA Astrophysics Data System (ADS)

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

2013-09-01

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.

Gallium-mediated growth of multiwall carbon nanotubes

NASA Astrophysics Data System (ADS)

Pan, Zheng Wei; Dai, Sheng; Beach, David B.; Evans, Neal D.; Lowndes, Douglas H.

2003-03-01

Liquid gallium was used as a viable and effective solvent and template for high-yield growth of multiwall carbon nanotubes. The gallium-mediated nanotubes thus obtained differ morphologically from nanotubes obtained by using transition metals as catalysts. The nanotubes have a pin-like morphology, generally composed of an oval-shaped tip filled with liquid gallium and a tapered hollow body. The inner diameter of the tube is so large that the inner/outer diameter ratio is usually larger than 0.9. The tubes are naturally opened at both ends. These gallium-filled nanotubes may be used as a nanothermometer in the temperature range of 30 to 550 °C. This study opens an interesting route for carbon nanotube synthesis.

Radiochemical separation of gallium by amalgam exchange

USGS Publications Warehouse

Ruch, R.R.

1969-01-01

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.

GARNET--gene set analysis with exploration of annotation relations.

PubMed

Rho, Kyoohyoung; Kim, Bumjin; Jang, Youngjun; Lee, Sanghyun; Bae, Taejeong; Seo, Jihae; Seo, Chaehwa; Lee, Jihyun; Kang, Hyunjung; Yu, Ungsik; Kim, Sunghoon; Lee, Sanghyuk; Kim, Wan Kyu

2011-02-15

Gene set analysis is a powerful method of deducing biological meaning for an a priori defined set of genes. Numerous tools have been developed to test statistical enrichment or depletion in specific pathways or gene ontology (GO) terms. Major difficulties towards biological interpretation are integrating diverse types of annotation categories and exploring the relationships between annotation terms of similar information. GARNET (Gene Annotation Relationship NEtwork Tools) is an integrative platform for gene set analysis with many novel features. It includes tools for retrieval of genes from annotation database, statistical analysis & visualization of annotation relationships, and managing gene sets. In an effort to allow access to a full spectrum of amassed biological knowledge, we have integrated a variety of annotation data that include the GO, domain, disease, drug, chromosomal location, and custom-defined annotations. Diverse types of molecular networks (pathways, transcription and microRNA regulations, protein-protein interaction) are also included. The pair-wise relationship between annotation gene sets was calculated using kappa statistics. GARNET consists of three modules--gene set manager, gene set analysis and gene set retrieval, which are tightly integrated to provide virtually automatic analysis for gene sets. A dedicated viewer for annotation network has been developed to facilitate exploration of the related annotations. GARNET (gene annotation relationship network tools) is an integrative platform for diverse types of gene set analysis, where complex relationships among gene annotations can be easily explored with an intuitive network visualization tool (http://garnet.isysbio.org/ or http://ercsb.ewha.ac.kr/garnet/).

Enhanced Thermoelectric Properties of Cu 2ZnSnSe 4 with Ga-doping

DOE PAGES

Wei, Kaya; Beauchemin, Laura; Wang, Hsin; ...

2015-08-10

Gallium doped Cu 2ZnSnSe 4 quaternary chalcogenides with and without excess Cu were synthesized by elemental reaction and densified using hot pressing in order to investigate their high temperature thermoelectric properties. The resistivity, , and Seebeck coefficient, S, for these materials decrease with increased Ga-doping while both mobility and effective mass increase with Ga doping. The power factor (S 2/ρ) therefore increases with Ga-doping. The highest thermoelectric figure of merit (ZT = 0.39 at 700 K) was obtained for the composition that had the lowest thermal conductivity. Our results suggest an approach to achieving optimized thermoelectric properties and are partmore » of the continuing effort to explore different quaternary chalcogenide compositions and structure types, as this class of materials continues to be of interest for thermoelectrics applications.« less

The origin of garnet in the anorthosite-charnockite suite of the Adirondacks

USGS Publications Warehouse

McLelland, J.M.; Whitney, P.R.

1977-01-01

Detailed analysis of textural and chemical criteria in rocks of the anorthosite-charnockite suite of the Adirondack Highlands suggests that development of garnet in silica-saturated rocks of the suite occurs according to the reaction: {Mathematical expression}, where ?? is a function of the distribution of Fe and Mg between the several coexisting ferromagnesian phases. Depending upon the relative amounts of Fe and Mg present, quartz may be either a reactant or a product. Using an aluminum-fixed reference frame, this reaction can be restated in terms of a set of balanced partial reactions describing the processes occurring in spatially separated domains within the rock. The fact that garnet invariably replaces plagioclase as opposed to the other reactant phases indicates that the aluminum-fixed model is valid as a first approximation. This reaction is univariant and produces unzoned garnet. It differs from a similar equation proposed by de Waard (1965) for the origin of garnet in Adirondack metabasic rocks, i.e. 6 Orthopyroxene+2 Anorthite = Clinopyroxene+Garnet+2 Quartz, the principle difference being that iron oxides (ilmenite and/or magnetite) are essential reactant phases in the present reactions. The product assemblage (garnet+clinopyroxene+plagioclase ?? orthopyroxene ?? quartz) is characteristic of the clinopyroxene-almandine subfacies of the granulite facies. ?? 1977 Springer-Verlag.

Shock wave experiments on gallium

NASA Astrophysics Data System (ADS)

Jensen, Brian; Branch, Brittany; Cherne, Frank

2017-06-01

Gallium exhibits a complex phase diagram with multiple solid phases, an anomalous melt boundary, and a low-temperature melt transition making it a suitable material for shock wave studies focused on multiphase properties including kinetics and strength. Apart from high-pressure shock wave data that exists for the liquid phase, there is a clear lack of data in the low-pressure regime where much of the complexity in the phase diagram exists. In this work, a series of shock wave experiments were performed to begin examining the low-pressure region of the phase diagram. Additional data on a gallium alloy, which remains liquid at room temperature, will be presented and compared to data available for pure gallium (LA-UR-17-21449).

Trace elements in garnet reveal multiple fluid pulses in eclogite, Ring Mountain, CA

NASA Astrophysics Data System (ADS)

Cruz-Uribe, A. M.; Page, F. Z.; Lozier, E.; Feineman, M. D.; Zack, T.; Mertz-Kraus, R.

2017-12-01

Garnetite veins in a hornblende-eclogite block from Ring Mountain, CA, offer a unique opportunity to investigate the chemical composition of fluid interactions during mélange formation in subduction zones. Garnet occurs as matrix porphyroblasts (2-5 mm) and in 1-5 cm garnetite veins that are laterally continuous up to 10 m across the outcrop. Garnet at the vein edges is slightly larger (300-600 µm) than within the veins (5-50 µm), and records a protracted history of vein garnet growth. Major and trace element concentrations in garnet were determined using EPMA and LA-ICP-MS, respectively. Detailed rim-to-rim trace element traverses were performed using 12 µm spots at 15 µm spacing across one matrix garnet (2 mm) and three vein edge garnet grains (375-570 µm). Zoning in Mn, Ca, and rare earth elements (REE) reveal 5 distinct garnet growth zones. Zone 1, found only in matrix garnet cores, is characterized by decreasing Mn and increasing Ca and is interpreted to reflect prograde zoning. Zones 2-5 are found in the mantles and rims of matrix garnet, and comprise the entirety of vein garnet. Garnet growth in Zones 2-5 is likely heavily influenced by internally- and externally-derived fluids, based on texture and chemistry. One key fluid-related texture of Zones 2-5 is oscillatory birefringence zoning, likely the result of incorporation of small amounts of water into the garnet structure (i.e., hydrogrossular). Zones 2 and 3 are characterized by progressive enrichment in heavy to middle REE from Zone 2 outward into Zone 3. We attribute this to diffusion-limited uptake of REE, wherein the heaviest REE are incorporated first, followed by progressively lighter REE. Zone 3 is also characterized by a high-Mn annulus that appears decoupled from the trace elements. Zone 4 is characterized by a sudden drop in Ca and enrichment in MREE, particularly Dy and Tb, possibly due to epidote breakdown. Zone 5 is characterized by strong enrichment in Mn+REE, with high-HREE and high

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

PubMed

Valappil, Sabeel P; Higham, Susan M

2014-01-01

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.

Optical properties of bulk gallium nitride single crystals grown by chloride-hydride vapor-phase epitaxy

NASA Astrophysics Data System (ADS)

Agyekyan, V. F.; Borisov, E. V.; Serov, A. Yu.; Filosofov, N. G.

2017-12-01

A gallium nitride crystal 5 mm in thickness was grown by chloride-hydride vapor-phase epitaxy on a sapphire substrate, from which the crystal separated during cooling. At an early stage, a three-dimensional growth mode was implemented, followed by a switch to a two-dimensional mode. Spectra of exciton reflection, exciton luminescence, and Raman scattering are studied in several regions characteristic of the sample. Analysis of these spectra and comparison with previously obtained data for thin epitaxial GaN layers with a wide range of silicon doping enabled conclusions about the quality of the crystal lattice in these characteristic regions.

Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors.

PubMed

Santos, Lídia; Nunes, Daniela; Calmeiro, Tomás; Branquinho, Rita; Salgueiro, Daniela; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

2015-01-14

Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 × 10(6), threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm(2)/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping.

Thermal Plasma Synthesis of Crystalline Gallium Nitride Nanopowder from Gallium Nitrate Hydrate and Melamine

PubMed Central

Kim, Tae-Hee; Choi, Sooseok; Park, Dong-Wha

2016-01-01

Gallium nitride (GaN) nanopowder used as a blue fluorescent material was synthesized by using a direct current (DC) non-transferred arc plasma. Gallium nitrate hydrate (Ga(NO3)3∙xH2O) was used as a raw material and NH3 gas was used as a nitridation source. Additionally, melamine (C3H6N6) powder was injected into the plasma flame to prevent the oxidation of gallium to gallium oxide (Ga2O3). Argon thermal plasma was applied to synthesize GaN nanopowder. The synthesized GaN nanopowder by thermal plasma has low crystallinity and purity. It was improved to relatively high crystallinity and purity by annealing. The crystallinity is enhanced by the thermal treatment and the purity was increased by the elimination of residual C3H6N6. The combined process of thermal plasma and annealing was appropriate for synthesizing crystalline GaN nanopowder. The annealing process after the plasma synthesis of GaN nanopowder eliminated residual contamination and enhanced the crystallinity of GaN nanopowder. As a result, crystalline GaN nanopowder which has an average particle size of 30 nm was synthesized by the combination of thermal plasma treatment and annealing. PMID:28344295

Raman imaging of fluid inclusions in garnet from UHPM rocks (Kokchetav massif, Northern Kazakhstan).

PubMed

Korsakov, Andrey V; Dieing, Thomas; Golovin, Aleksandr V; Toporski, Jan

2011-10-01

Confocal Raman imaging of fluid inclusions in garnet porphyroblasts from diamond-grade metamorphic calc-silicate rocks from the Kumdy-Kol microdiamond deposit (Kokchetav Massif, Northern Kazakhstan) reveals that these fluid inclusions consist of almost pure water with different step-daughter phases (e.g., calcite, mica and rare quartz). These fluid inclusions are characterized by negative crystal shape of the host-garnet and they exclusively occur within the core of garnet porphyroblasts. These observations are consistent with their primary origin, most likely at ultrahigh-pressure (UHP) metamorphic conditions. The euhedral newly formed garnet, different in color and composition, was found to be associated with these fluid inclusions. It is proposed that newly formed garnet and water fluid inclusions appear by reaction between the hydrous fluid and the garnet-host. These fluid inclusions provide an unequivocal record of almost pure H(2)O fluids, indicating water-saturated conditions within subducted continental crust during prograde stage and/or ultrahigh-P metamorphism. Copyright © 2011 Elsevier B.V. All rights reserved.

Nonlinear behaviour of reflectivity of gallium - Silica interface & its applications

NASA Astrophysics Data System (ADS)

Naruka, Preeti; Bissa, Shivangi

2018-05-01

In this paper Optical properties and nonlinear behaviour of Gallium-Silica Interface is studied. Change in reflectivity of gallium film is explained as a function of thickness of metallic layer and intensity of incident light by using non-thermal mechanism. Here variation of dielectric constant of gallium with temperature is also explained on considering Binary nanoshell model of gallium nanoparticles of spherical shape. In the present paper application of structural phase transformation of gallium is explained as a Grating assisted coupler.

Dating high-grade metamorphism: constraints from zircon and garnet REE compositions

NASA Astrophysics Data System (ADS)

Whitehouse, M. J.; Platt, J. P.

2001-12-01

We present high spatial resolution ion microprobe REE analyses of zircon and garnet from pelitic granulite adjacent to the Ronda peridotite, Betic Cordillera, southern Spain. The zircons exhibit polyphase growth, with thick structureless (in cathodoluminescence) overgrowths over detrital cores. These overgrowths yield a U-Pb age of 21.3 +/- 0.3 Ma [1, unpublished data] which we intepret as dating an episode of zircon growth during the Alpine orogeny. REE analyses of the dated portions of these zircons reveal profound differences between cores and rims. Cores show patterns typical of magmatic zircon (steep upward slopes from La to Lu with marked positive Ce anomaly), while the overgrowths are characterised by flat or even negatively sloping HREE profiles (Gd - Lu). Garnet, which occupies ca. 30 % by volume of the rock, is the most likely phase to host the HREEs in the rock and has been the subject of further ion-microprobe REE, textural and trace element investigations. The garnets are themselves zoned, with dominant central regions that are relatively free of inclusions overgrown by inclusion-rich, more calcic rims. Inclusions of kyanite +rutile in the central regions and sillimanite +ilmenite in the rims suggests that the garnets grew during decompression, and the Ca-enrichment in the rims suggests that their growth coincided with the initiation of partial melting. The presence of rimmed zircons only in the garnet rims and the matrix further suggests that the zircons also grew during this late decompressional history. An REE traverse of the garnet from core to rim reveals marked HREE depletion in the rims relative to the cores which we suggest is consistent with the textural evidence and probably results from early garnet core growth strongly depleting the HREEs available to subsequent growth. This mechanism can also be invoked to explain depletion in the zircon rims and more closely ties their formation to this stage of garnet growth. We therefore interpret the

Ab initio study of (Fe, Ni) doped GaAs: Magnetic, electronic properties and Faraday rotation

NASA Astrophysics Data System (ADS)

Sbai, Y.; Ait Raiss, A.; Bahmad, L.; Benyoussef, A.

2017-06-01

The interesting diluted magnetic semiconductor (DMS), Gallium Arsenide (GaAs), was doped with the transition metals magnetic impurities: iron (Fe) and Nickel (Ni), in one hand to study the magnetic and magneto-optical properties of the material Ga(Fe, Ni) As, in the other hand to investigate the effect of the doping on the properties of this material, the calculations were performed within the spin polarized density functional theory (DFT) and generalized gradient approximation (GGA) with AKAI KKR-CPA method, the density of states (DOS) for different doping concentrations were calculated, giving the electronical properties, as well as the magnetic state and magnetic states energy, also the effect of these magnetic impurities on the Faraday rotation as magneto-optical property. Furthermore, we found the stable magnetic state for our doped material GaAs.

Garnet zoning and metamorphism of the Barrovian type area, Scotland

NASA Astrophysics Data System (ADS)

Dempster, T. J.

1985-03-01

A microprobe investigation of the high grade metamorphic zones from the Barrovian type area in Angus, Scotland, shows the importance of local zones of retrograde cation exchange between garnet, staurolite and biotite. The interpretation of this zoning, established during a slow cooling history, is critical to any study of metamorphic reactions or conditions. The extent and intensity of these diffusion effects are dependent on a number of parameters including grainsize, fabric orientation, heating and cooling history, and the modal abundance of the phases. Increasing diffusion within garnets with metamorphic grade, and the subsequent retrograde effects are modelled using Temperature-Time-Transformation diagrams and provide information on the activation energy for Fe-Mg diffusion in garnet.

Characterization of GAGG:Ce scintillators with various Al-to-Ga ratio

NASA Astrophysics Data System (ADS)

Sibczynski, Pawel; Iwanowska-Hanke, Joanna; Moszyński, Marek; Swiderski, Lukasz; Szawłowski, Marek; Grodzicka, Martyna; Szczęśniak, Tomasz; Kamada, Kei; Yoshikawa, Akira

2015-02-01

We have studied the scintillation properties of cerium doped gadolinium aluminum gallium garnet (GAGG:Ce) scintillators with various Al-to-Ga ratio. Having many advantages, like high density (6.63 g/cm3), high light output, fair energy resolution and quite fast decay time, the scintillators are an excellent solution for gamma rays detection. In this paper performance of the GAGG:1%Ce crystals with different Al-to-Ga ratios is presented. The study covered measurements of emission spectra, light output, energy resolution and non-proportionality for each crystal. It was observed that the light output of the recently obtainable crystals varies from 40,000 to 55,000 ph/MeV. Maximum emission wavelength of about 520 nm promotes silicon based photodetectors for use with these scintillators. The best energy resolution of 3.7% at 662 keV, measured with Hamamatsu S8664-1010 APD, was obtained for the sample with the minimum gallium content. This result is close to these obtained with the group of scintillators retaining very good energy resolution, like LaCl3 and CeBr3.

Fragmentation of wall rock garnets during deep crustal earthquakes

PubMed Central

Austrheim, Håkon; Dunkel, Kristina G.; Plümper, Oliver; Ildefonse, Benoit; Liu, Yang; Jamtveit, Bjørn

2017-01-01

Fractures and faults riddle the Earth’s crust on all scales, and the deformation associated with them is presumed to have had significant effects on its petrological and structural evolution. However, despite the abundance of directly observable earthquake activity, unequivocal evidence for seismic slip rates along ancient faults is rare and usually related to frictional melting and the formation of pseudotachylites. We report novel microstructures from garnet crystals in the immediate vicinity of seismic slip planes that transected lower crustal granulites during intermediate-depth earthquakes in the Bergen Arcs area, western Norway, some 420 million years ago. Seismic loading caused massive dislocation formations and fragmentation of wall rock garnets. Microfracturing and the injection of sulfide melts occurred during an early stage of loading. Subsequent dilation caused pervasive transport of fluids into the garnets along a network of microfractures, dislocations, and subgrain and grain boundaries, leading to the growth of abundant mineral inclusions inside the fragmented garnets. Recrystallization by grain boundary migration closed most of the pores and fractures generated by the seismic event. This wall rock alteration represents the initial stages of an earthquake-triggered metamorphic transformation process that ultimately led to reworking of the lower crust on a regional scale. PMID:28261660

Olivine Lamellae and Interstitial Blebs of Diopside and Enstatite Exsolved from Majoritic Garnet during Decompression in Multianvil Apparatus

NASA Astrophysics Data System (ADS)

Dobrzhinetskaya, L. F.; Green, H. W.

2003-12-01

We present preliminary experimental data on the decompression of majoritic garnet primarily synthesized from a mineral mix of garnet peridotite bulk chemistry showing exsolution from majoritic garnet of olivine (Ol) in the form of oriented plates and pyroxenes as interstitial blebs. Experiments conducted at 14GPa/1673K demonstrate that all enstatite (En) and about 85% of diopside (Di) were dissolved into garnet yielding run products of approximately 40% Ol + 55% Grt + 5% Di. Garnet was found to be supersilicic with Si=3.17-3.31 p.f.u. Repeat of such experiments followed immediately by re-annealing at 13 and 12 GPa yielded exsolution of both Di and Ol. Olivine exsolved as micron-size plates nucleated within garnet on low-angle boundaries. In contrast, diopside exsolved abundantly as tiny blebs at garnet grain boundaries, exhibiting no typical exsolution microstructures. Similarly, in specimens annealed at 5 GPa after previous equilibration at 8GPa/1673K, En exsolved as small blebs at garnet boundaries. Under conditions similar to the latter experiments, interstitial blebs of natural enstatite also occur at garnet grain boundaries (Van Roermund et al., 2001) in Norwegian deep-seated (>200 km) subduction zone grt-peridotite. Our experiments show that Ol as well as En and Di may exsolve during decompression of majoritic garnets in the course of Grt peridotite exhumation. Examples of preservation of pyroxene exsolution lamellae in former majoritic garnets come from both xenoliths in kimberlites (Haggerty and Sautter, 1990; Sautter et al., 1991) as well as from very large garnets in subduction-zone peridotites (van Roermund and Drury, 1998). However, many other garnet peridotites from subduction zones contain Di, En, and/or Ol along grain boundaries within larger polycrystalline garnets and within embayments at the margins of smaller amoeboid garnets (e.g. Dobrzhinetskaya et al, 1996, Green and Dobrzhinetskaya, 2003). Such garnets also may contain rounded non

Paired-pulse facilitation achieved in protonic/electronic hybrid indium gallium zinc oxide synaptic transistors

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

Guo, Li Qiang, E-mail: guoliqiang@ujs.edu.cn; Ding, Jian Ning; Huang, Yu Kai

2015-08-15

Neuromorphic devices with paired pulse facilitation emulating that of biological synapses are the key to develop artificial neural networks. Here, phosphorus-doped nanogranular SiO{sub 2} electrolyte is used as gate dielectric for protonic/electronic hybrid indium gallium zinc oxide (IGZO) synaptic transistor. In such synaptic transistors, protons within the SiO{sub 2} electrolyte are deemed as neurotransmitters of biological synapses. Paired-pulse facilitation (PPF) behaviors for the analogous information were mimicked. The temperature dependent PPF behaviors were also investigated systematically. The results indicate that the protonic/electronic hybrid IGZO synaptic transistors would be promising candidates for inorganic synapses in artificial neural network applications.

Gallium nitrate ameliorates type II collagen-induced arthritis in mice.

PubMed

Choi, Jae-Hyeog; Lee, Jong-Hwan; Roh, Kug-Hwan; Seo, Su-Kil; Choi, Il-Whan; Park, Sae-Gwang; Lim, Jun-Goo; Lee, Won-Jin; Kim, Myoung-Hun; Cho, Kwang-rae; Kim, Young-Jae

2014-05-01

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease. Gallium nitrate has been reported to reserve immunosuppressive activities. Therefore, we assessed the therapeutic effects of gallium nitrate in the mouse model of developed type II collagen-induced arthritis (CIA). CIA was induced by bovine type II collagen with Complete Freund's adjuvant. CIA mice were intraperitoneally treated from day 36 to day 49 after immunization with 3.5mg/kg/day, 7mg/kg/day gallium nitrate or vehicle. Gallium nitrate ameliorated the progression of mice with CIA. The clinical symptoms of collagen-induced arthritis did not progress after treatment with gallium nitrate. Gallium nitrate inhibited the increase of CD4(+) T cell populations (p<0.05) and also inhibited the type II collagen-specific IgG2a-isotype autoantibodies (p<0.05). Gallium nitrate reduced the serum levels of TNF-α, IL-6 and IFN-γ (p<0.05) and the mRNA expression levels of these cytokine and MMPs (MMP2 and MMP9) in joint tissues. Western blotting of members of the NF-κB signaling pathway revealed that gallium nitrate inhibits the activation of NF-κB by blocking IκB degradation. These data suggest that gallium nitrate is a potential therapeutic agent for autoimmune inflammatory arthritis through its inhibition of the NF-κB pathway, and these results may help to elucidate gallium nitrate-mediated mechanisms of immunosuppression in patients with RA. Copyright © 2014 Elsevier B.V. All rights reserved.

Mixed garnet laser crystals for water vapour DIAL transmitter

NASA Astrophysics Data System (ADS)

Treichel, Rainer; Czeranowsky, Christoph; Ileri, Bilge; Petermann, Klaus; Huber, Günter

2017-11-01

There are more or less well established technologies such as the optical-parametric-oscillator (OPO), the Raman-laser, and the Ti-Sapphire laser, which are able to emit laser light in the region of the water vapour absorption lines. For WALES the regions of about 935 nm, 942 nm, and 944 nm have been identified as the most suitable wavelength ranges. However, each of these laser designs is highly sophisticated. Current baseline for WALES is the Ti-Sapphire laser. A fourth possibility to achieve these wavelength ranges is to shift the groundstate laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing Aluminium and Yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. Such lasers have the great potential to fulfil the requirements and to become the preferred transmitter concept for WALES as well as for follow up missions. Within a ESA study several crystal compositions have been grown, spectrally characterised and analysed. Absorbed space radiation energy in the crystal lattice causes colour centres, which can reabsorb the pump and laser wavelength and consequently reduce the laser gain considerably. Co-dopants such as Chromium and Cerium are able to suppress the colour centres and are candidates for effective radiation hardening. The results of the crystal tuning, the co-doping with different radiation hardeners and the radiation tests will be presented. There applicability for a space based water vapour DIAL transmitter will be discussed.

Strongly localized donor level in oxygen doped gallium nitride

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

Wetzel, C.; Suski, T.; Ager, J.W. III

1996-08-01

A classification in terms of localization of donor defects in GaN is performed by Raman spectroscopy under large hydrostatic pressure. We observe a significant decrease of free carrier concentration in highly O doped GaN epitaxial films at 22 GPa, indicating the presence of a strongly localized donor defect at large pressure. Monitoring the phonon plasmon coupled mode, we find similarities with results on highly n-type bulk crystals. We refine the model of localized defects in GaN and transfer it to the AlGaN system.

The comparison between gallium arsenide and indium gallium arsenide as materials for solar cell performance using Silvaco application

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

Zahari, Suhaila Mohd; Norizan, Mohd Natashah; Mohamad, Ili Salwani

2015-05-15

The work presented in this paper is about the development of single and multilayer solar cells using GaAs and InGaAs in AM1.5 condition. The study includes the modeling structure and simulation of the device using Silvaco applications. The performance in term of efficiency of Indium Gallium Arsenide (InGaAs) and GaAs material was studied by modification of the doping concentration and thickness of material in solar cells. The efficiency of the GaAs solar cell was higher than InGaAs solar cell for single layer solar cell. Single layer GaAs achieved an efficiency about 25% compared to InGaAs which is only 2.65% ofmore » efficiency. For multilayer which includes both GaAs and InGaAs, the output power, P{sub max} was 8.91nW/cm² with the efficiency only 8.51%. GaAs is one of the best materials to be used in solar cell as a based compared to InGaAs.« less

Variations in Ti coordination and concentration in garnet in response to temperature, pressure and composition

NASA Astrophysics Data System (ADS)

Ackerson, M. R.; Tailby, N.; Watson, E. B.; Spear, F. S.

2013-12-01

Titanium concentrations in garnet vary over several orders of magnitude in natural systems-- from trace-element levels in continental metamorphic systems to several weight percent in garnets from mantle xenoliths. Broadly speaking the wide range of concentrations is due to crystallization from diverse environments. Understanding the crystallographic site and Ti-substitution mechanism in garnet is crucial to deciphering concentration trends and how these relate to the petrogenetic history. This study uses XANES spectroscopy to measure Ti coordination in natural and synthetic garnets known to crystallize over a wide range of conditions to investigate whether changes in Ti coordination and concentration correlate with changes T, P and bulk composition. Ti XANES spectroscopy utilizes shifts in the 1s-3d pre-edge feature, which shows systematic shifts in intensity and energy with coordination. Natural and synthetic garnets grown at >800 oC and >1 GPa incorporate Ti almost entirely on the octahedral site in garnet. It is possible that a small amount of Ti substitutes on the tetrahedral site in these garnets, but the concentration is too low to be observed in the spectra. The most feasible mechanism for octahedral substitution involves charge-balanced coupled substitution with an M2+ cation (where M2+=Mg, Fe, Ca, or Mn) resulting in a net loss of two Al for every Ti gained. Substitution of Al onto the tetrahedral site and Ti on the octahedral site is an other feasible mechanism, although the stoichiometric deficit of Al in experimental garnets suggests this mechanism could only account for a small percentage of Ti. Increases in Ti concentration correlate best with increasing Ca content in experimental garnets. Ti solubility also changes in response to T and P. These observations suggest that Ti incorporation on the octahedral site is dependent on the activities of Ti, Al and other M2+ cation system components. This helps to explain some of the differences in Ti

Role of gallium and silver from phosphate-based glasses on in vitro dual species oral biofilm models of Porphyromonas gingivalis and Streptococcus gordonii.

PubMed

Valappil, Sabeel P; Coombes, Marc; Wright, Lucy; Owens, Gareth J; Lynch, Richard J M; Hope, Christopher K; Higham, Susan M

2012-05-01

Phosphate-based glasses (PBGs) are excellent controlled delivery agents for antibacterial ions such as silver and gallium. The aim of this study was to assess the potential utility of novel PBGs combining both gallium and silver for use in periodontal therapy. To this end, an in vitro biofilm model with the putative periodontal pathogen, Porphyromonas gingivalis, and an initial colonizer, Streptococcus gordonii, was established. The effect of increasing calcium content in gallium-silver-doped PBG on the susceptibility of P. gingivalis was examined. A decrease in degradation rates (30.34, 25.19, 21.40 μg mm(-2) h(-1)) with increasing PBG calciumcontent (10, 11, 12 mol.% respectively) was observed, correlating well with gallium and silver ion release and antimicrobial activity against planktonic P. gingivalis (approximately 5.4log(10) colony-forming units (CFU) reduction after 24h by the C10 glass compared with controls) and S. gordonii (total growth inhibition after 32h by C10, C11 and C12 glasses compared with controls). The most potent PBG (C10) was evaluated for its ability to inhibit the biofilm growth of P. gingivalis in a newly established constant-depth film fermentor model. The simultaneous release of silver and gallium from the glass reduced P. gingivalis biofilm growth with a maximum effect (1.92log(10) CFU reduction) after 168 h. Given the emergence of antibiotic-resistant bacteria and dearth of new antibiotics in development, the glasses, especially C10, would offer effective alternatives to antibiotics or may complement current therapies through controlled, localized delivery of gallium and silver ions at infected sites in the oral cavity. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Behavior of pure gallium in water and various saline solutions.

PubMed

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

1997-12-01

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

High-pressure crystallization vs. recrystallization origin of garnet pyroxenite-eclogite within subduction related lithologies

NASA Astrophysics Data System (ADS)

Faryad, S. W.; Jedlicka, R.; Hauzenberger, C.; Racek, M.

2018-03-01

Mafic layers displaying transition between clinopyroxenite and eclogite within peridotite from felsic granulite in the Bohemian Massif (Lower Austria) have been investigated. The mafic-ultramafic bodies shared a common granulite facies metamorphism with its hosting felsic rocks, but they still preserve evidence of eclogite facies metamorphism. The selected mafic layer for this study is represented by garnet with omphacite in the core of coarse-grained clinopyroxene, while fine-grained clinopyroxene in the matrix is diopside. In addition, garnet contains inclusions of omphacite, alkali feldspars, hydrous and other phases with halogens and/or CO2. Textural relations along with compositional zoning in garnet from the clinopyroxenite-eclogite layers favour solid-state recrystallization of the precursor minerals in the inclusions and formation of garnet and omphacite during subduction. Textures and major and trace element distribution in garnet indicate two stages of garnet growth that record eclogite facies and subsequent granulite facies overprint. The possible model explaining the textural and compositional changes of minerals is that the granulite facies overprint occurred after formation and exhumation of the eclogite facies rocks.

PTR, PCR and Energy Resolution Study of GAGG:Ce Scintillator

NASA Astrophysics Data System (ADS)

Limkitjaroenporn, Pruittipol; Hongtong, Wiraporn; Kim, Hong Joo; Kaewkhao, Jakrapong

2018-03-01

In this paper, the peak to total ratio (PTR), the peak to Compton ratio (PCR) and the energy resolution of cerium doped gadolinium aluminium gallium garnet (GAGG:Ce) scintillator are measured in the range of energy from 511 keV to 1332 keV using the radioactive source Na-22, Cs-137 and Co-60. The crystal is coupled with the PMT number R1306 and analyzed by the nuclear instrument module (NIM). The results found that the PTR and PCR of GAGG:Ce scintillator decrease with the increasing of energy. The results of energy resolution show the trend is decrease with the increasing of energy which corresponding to the higher energy resolution at higher energy. Moreover the energy resolution found to be linearly with.

Raman spectroscopic study of synthesized Na-bearing majoritic garnets

NASA Astrophysics Data System (ADS)

Okamoto, K.

2003-12-01

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

Magneto-Optic Laser Beam Steering

DTIC Science & Technology

1975-10-01

Thin Substrates 16 1. Substrate Thinning 16 2. LPE on TMn Substrates 18 3. Statics of BRIG Crystal Films on Thin Substrates... 19 4. Results...6 Garnet Etch Rate 17 7 Thin Substrate: Film Both Sides 20 8 Thin Substrate: Film One Side 21 9 Film with Substrate Both Sides 23 10 Ratio...Robbins et al reported that iron garnet films could be grown on gallium garnet sub- strates by using a coprecipitated slurry. This technique was

Garnet from diamondiferous metamorphic rocks of Kokchetav massif, Kazakhstan as a peak pressure recorder

NASA Astrophysics Data System (ADS)

Sobolev, N. V.; Palyanov, Y. N.; Shatsky, V. S.; Sokol, A. G.; Tomilenko, A. A.

2003-12-01

Garnet is a key mineral coexisting with diamond both in kimberlite (as xenocrysts, in diamondiferous garnet peridotites and eclogites, as inclusions in diamond) and in UHP metamorphic rocks of Kokchetav massif (diamondiferous gneisses, garnet-pyroxene rocks, dolomitic marbles and diamond facies eclogites). In UHPM rocks garnets are of particular importance as inclusions in zircons protected from retrograde metamorphism. Diamond formation conditions in eclogitic (E-type) upper mantle environment are estimated based upon Grt-Cpx thermometry and coesite barometry (e.g. Sobolev et al., PNAS, 2000, 97:11875) at P=5.5-6.0 GPa and T=1000-1300° C. These data are supported by diamond synthesis in carbonate-silicate fluid (e.g. Palyanov et al., Nature, 1999, 400: 417). E-type garnet may dissolve up to 0.3 wt.% Na2O (Sobolev, Lavrentyev, Contr. Min. Petr., 1971, 31:1) depending on pressure and Na2O contents in coexisting pyroxene and melts (fluids). Majorite component (pyroxene solid solution) was reported in rare garnets from diamonds (e.g. Moore, Gurney, Nature, 1985, 318:553) and UHP conditions were experimentally confirmed for such garnets (Irifune, Phys. Eart. Pl. Int., 1987, 45:324; Gasparik, Phys. Chem. Min., 2002, 29:170; Luth, Am. Miner., 1997, 82:1198). Garnets from Kokchetav diamondiferous metamorphic rocks demonstrate considerably lower Na2O solubility (up to 0.2 wt.% in rare samples) and absence of majorite component. However, coexisting pyroxenes may contain up to 50 mol.% jadeite. Several UHP experiments performed with Kokchetav eclogites and dolomitic marbles using a split-sphere apparatus resulted in detection of up to 0.3-0.4 wt.% Na2O in newly formed eclogitic garnets at P=5.7 and 7.0 GPa, T=1400 and 1700° C respectively. Majorite component was also determined in newly formed garnets reaching about 5% with Si (pfu)=3.05-3.06. Similar garnets without Na2O were also obtained in UHP experiments with diamondiferous dolomitic marbles (e.g. Palyanov et al

LA-ICP-MS trace element mapping: insights into the crystallisation history of a metamorphic garnet population

NASA Astrophysics Data System (ADS)

George, Freya; Gaidies, Fred

2017-04-01

In comparison to our understanding of major element zoning, relatively little is known about the incorporation of trace elements into metamorphic garnet. Given their extremely slow diffusivities and sensitivity to changing mineral assemblages, the analysis of the distribution of trace elements in garnet has the potential to yield a wealth of information pertaining to interfacial attachment mechanisms during garnet crystallisation, the mobility of trace elements in both garnet and the matrix, and trace element geochronology. Due to advances in the spatial resolution and analytical precision of modern microbeam techniques, small-scale trace element variations can increasingly be documented and used to inform models of metamorphic crystallisation. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in particular, can be used to rapidly quantify a wide range of elemental masses as a series of laser rasters, producing large volumes of spatially constrained trace element data. In this study, we present LA-ICP-MS maps of trace element concentrations from numerous centrally-sectioned garnets representative of the crystal size-distribution of a single sample's population. The study sample originates from the garnet-grade Barrovian zone of the Lesser Himalayan Sequence in Sikkim, northeast India, and has been shown to have crystallised garnet within a single assemblage between 515 ˚C and 565˚C, with no evidence for accessory phase reaction over the duration of garnet growth. Previous models have indicated that the duration of garnet crystallisation was extremely rapid (<1 Myr), with negligible diffusional homogenisation of major divalent cations. Consequently, the trace element record likely documents the primary zonation generated during garnet growth. In spite of straightforward (i.e. concentrically-zoned) major element garnet zonation, trace elements maps are characterised by significant complexity and variability. Y and the heavy rare earth elements

Surface photovoltage spectroscopy applied to gallium arsenide surfaces

NASA Technical Reports Server (NTRS)

Bynik, C. E.

1975-01-01

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.

A FETISH for gallium arsenide

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

Barron, A.R.

1996-12-31

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

Magnesium acceptor in gallium nitride. II. Koopmans-tuned Heyd-Scuseria-Ernzerhof hybrid functional calculations of its dual nature and optical properties

NASA Astrophysics Data System (ADS)

Demchenko, D. O.; Diallo, I. C.; Reshchikov, M. A.

2018-05-01

The problem of magnesium acceptor in gallium nitride is that experimental photoluminescence measurements clearly reveal a shallow defect state, while most theoretical predictions favor a localized polaronic defect state. To resolve this contradiction, we calculate properties of magnesium acceptor using the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional, tuned to fulfill the generalized Koopmans condition. We test Koopmans tuning of HSE for defect calculations in GaN using two contrasting test cases: a deep state of gallium vacancy and a shallow state of magnesium acceptor. The obtained parametrization of HSE allows calculations of optical properties of acceptors using neutral defect-state eigenvalues, without relying on corrections due to charged defects in periodic supercells. Optical transitions and vibrational properties of M gGa defect are analyzed to bring the dual (shallow and deep) nature of this defect into accord with experimental photoluminescence measurements of the ultraviolet band in Mg-doped GaN samples.

Combined vitamin C sonophoresis and neodymium-doped yttrium aluminum garnet (NdYAG) laser for facial hyperpigmentation: An outcome observation study in Asian patients.

PubMed

Chen, Yu-Tsung; Chang, Chang-Cheng; Hsu, Cherng-Ru; Shen, Jen-Hsiang; Shih, Chao-Jen; Lin, Bor-Shyh

2016-01-01

The neodymium-doped yttrium aluminum garnet (NdYAG) laser therapy has been a popular technique for facial rejuvenation but certain adverse effects like post-inflammatory hyperpigmentation are issues of concern to Asian patients. To assess the outcome following combined treatment with vitamin C sonophoresis and NdYAG laser, in selected cases of facial hyperpigmentation. Twenty three women with dyschromia or melasma who had undergone five sessions of Q-switched NdYAG laser therapy followed by transdermal delivery of vitamin C via sonophoresis were selected after a retrospective review of case records. The objective and subjective clinical outcomes and the side effects, including erythema, scaling, pruritus, dryness and post-inflammatory hyperpigmentation were evaluated. In both objective or subjective outcomes, 91.3% (21/23) of the patients showed an excellent or better outcome, while 8.7% (2/23) showed no change. A majority of the patients (73.9%, 17/23) experienced no post-inflammatory hyperpigmentation or had slight post-inflammatory hyperpigmentation which quickly resolved within 1 week. Only one (4.3%) patient had extreme post-inflammatory hyperpigmentation which lasted for over a month. This was a retrospective study without a control group; a comparative study with a control group (patients treated with the laser alone, without vitamin C sonopheresis) is needed to determine the difference in the outcome. The use of vitamin C sonophoresis along with NdYAG laser may reduce the incidence of adverse effects in Asian patients. Patients experienced obvious improvement in hyperpigmentation and had lower chances of experiencing extreme or severe post-inflammatory hyperpigmentation.

Crystallization of high-Ca chromium garnet upon interaction of serpentine, chromite, and Ca-bearing hydrous fluid

NASA Astrophysics Data System (ADS)

Chepurov, A. A.; Turkin, A. I.; Pokhilenko, N. P.

2017-10-01

The results of experimental modeling of the conditions of crystallization of high-Ca chromium garnets in the system serpentine-chromite-Ca-Cr-bearing hydrous fluid at a pressure of 5 GPa and temperature of 1300°C are reported. The mineral association including quantitatively predominant high-Mg olivine and diopside-rich clinopyroxene, bright-green garnet, and newly formed chrome spinel was formed. Garnet mostly crystallized around primary chromite grains and was characterized by a high concentration of CaO and Cr2O3. According to the chemical composition, garnets obtained are close to the uvarovite-pyrope varieties, which enter the composition of relatively rare natural paragenesis of garnet wehrlite. The experimental data obtained clearly show that high-Ca chromium garnets are formed in the reaction of chromite-bearing peridotite and Ca-rich fluid at high P-T parameters.

Conversion between hexagonal GaN and beta-Ga(2)O(3) nanowires and their electrical transport properties.

PubMed

Li, Jianye; An, Lei; Lu, Chenguang; Liu, Jie

2006-02-01

We have observed that the hexagonal GaN nanowires grown from a simple chemical vapor deposition method using gallium metal and ammonia gas are usually gallium-doped. By annealing in air, the gallium-doped hexagonal GaN nanowires could be completely converted to beta-Ga(2)O(3) nanowires. Annealing the beta-Ga(2)O(3) nanowires in ammonia could convert them back to undoped hexagonal GaN nanowires. Field effect transistors based on these three kinds of nanowires were fabricated, and their performances were studied. Because of gallium doping, the as-grown GaN nanowires show a weak gating effect. Through the conversion process of GaN nanowires (gallium-doped) --> Ga(2)O(3) nanowires --> GaN nanowires (undoped) via annealing, the final undoped GaN nanowires display different electrical properties than the initial gallium-doped GaN nanowires, show a pronounced n-type gating effect, and can be completely turned off.

Evidence of mantle metasomatism in garnet peridotites from V. Grib kimberlite pipe (Arkhangelsk region, Russia)

NASA Astrophysics Data System (ADS)

Shchukina, Elena; Agashev, Alexey; Golovin, Nikolai; Pokhilenko, Nikolai

2013-04-01

We have studied 26 samples of garnet peridotite xenoliths from V.Grib pipe and 17 of them are phlogopite bearing. Studied peridotites have features of two types of modal metasomatism: low-temperature (˜ 1100 C°) and high-temperature (˜ 1100 C°). Low-temperature modal metasomatism: 17 samples contain modal phlogopite, which is present in the form of tabular grains (to 3 mm in size) and rims around pyrope grains. Chemical composition of minerals from phlogopite-garnet peridotites and phlogopite free peridotites is distinctly different. Olivine, garnet, orthopyroxene and clinopyroxene have higher concentration of FeO relative to these minerals in phlogopite free peridotites. Occurrence of phlogopite in peridotites indicates the influence of melt enriched in K2O, H2O, FeO and other incompatible elements. Two types of phlogopite have difference in chemical composition that indicates two different sources. High-temperature modal metasomatism: Reconstructed V.Grib pipe peridotite whole-rocks composition and high Mg# of peridotite olivines indicates that these samples are residues after 30-40 % partial melting of primitive mantle. At those high degree of partial melting all clinopyroxene and probably all garnet should be exhausted from residue. Character of REE patterns in garnets and clinopyroxenes indicates that the most garnets and all clinopyroxene in studied peridotites are of metasomatic origin. We used the method of geochemical modeling of fractional crystallization to establish the source's composition for garnets and clinopyroxenes. For geochemical modeling we used the composition of tholeitic basalts, picrites and carbonatites which occurred in Arkhangelsk diamondiferous province (ADP) and have emplacement ages similar to that of kimberlites. Modeling result indicates that garnets could be crystallized from alkali picrite and tholeite basalts compositions. Peridotites containing garnets equilibrated with picritic melt have a different position in lithospheric

A hetero-homogeneous investigation of chemical bath deposited Ga-doped ZnO nanorods

NASA Astrophysics Data System (ADS)

Rakhsha, Amir Hosein; Abdizadeh, Hossein; Pourshaban, Erfan; Golobostanfard, Mohammad Reza

2018-01-01

One-dimensional nanostructures of zinc oxide (ZnO) have been in the center of attention, mostly for electronic applications due to their distinctive properties such as high electron mobility (100 cm2V-1s-1) and crystallinity. Thanks to its high density of vacancies and interstitial sites, wurtzite lattice of ZnO is a suitable host for gallium (Ga) as a dopant element. Herein, ZnO nanorod arrays (NRAs) are synthesized by a low-temperature chemical bath deposition (CBD) method with various concentrations of gallium nitrate hydrate as a dopant precursor. Structural and morphological analyses confirm that optimum properties of gallium-doped ZnO (GZO) are obtained at 1% (Ga to Zn molar ratio). Owing to the replacement of smaller Ga3+ ions with Zn2+ ions in the GZO structure, a slight shift of (002) peak to higher angles could be observed in XRD pattern of GZO NRAs. The scanning electron microscope images demonstrate a proliferation in the ZnO NRAs length from 650 nm for undoped ZnO (UZO) to 1200 nm for GZO-1%. However, increasing the dopant concentration above 2.5% results in formation of homogeneous zinc gallium oxide in the bulk solution, which is a sign of inefficient process of doping in GZO NRAs. Furthermore, photoluminescence spectroscopy is used to characterize the band-gap variation of the samples, which demonstrates a small red-shift in the UV emission peak and a decrease in visible emission peak intensity with introducing Ga in ZnO lattice. Lower resistivity for GZO-1% (1.1 MΩ) sample compared to UZO (1.4 MΩ) is recorded, which is compelling evidence for the presence of Ga3+ in ZnO lattice. The results suggest that incorporating Ga into ZnO lattice using CBD method is an easy and effective technique to improve the electrical properties of ZnO NRAs that is an essential factor for a broad range of devices.

Histological Evaluation of Retina after Photo Disruption for Vitreous Humor by Q-Switched Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser

PubMed Central

Kameel Ghaly, Sally; Foad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Medhat Abdel-Salam, Ahmed

2013-01-01

Introduction: Rabbits’ eyes were exposed to vitreous humor liquefaction with Q - switched (sometimes called “ giant pulses”) Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser using two different energy protocols (5 mJ X 100 pulse and 10 mJ X 50 pulse)with and without vitamin C administration. The histological changes in the retina were investigated to evaluate the protective role of vitamin C. Methods: The rabbits were divided into four main groups (n= 12 each). The first group was divided into three subgroups (n=4) and then treated with 5 mJ X 100 pulse (X means times) delivered to the anterior, middle and posterior vitreous humor respectively. The second group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the first group.The third group was divided into three subgroups (n=4) and then treated with 10 mJ X 50 pulse delivered to the anterior, middle and posterior vitreous respectively. The fourth group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the third group. After two weeks, rabbits were decapitated and histological examination for the retina was performed. Results: The results showed that, the anterior vitreous group exposed to 5mJX100 pulse and supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups showed alteration in retina’s tissues histology after laser. Conclusion: Application of Q-switched Nd: YAG laser in vitreous humor liquefaction induces changes in retina’s layers. Although there were some sorts of improvements in retinas supplemented with vitamin C, it cannot protect them against laser oxidative damage. PMID:25606329

Study of Y and Lu iron garnets using Bethe-Peierls-Weiss method

NASA Astrophysics Data System (ADS)

Goveas, Neena; Mukhopadhyay, G.; Mukhopadhyay, P.

1994-11-01

We study here the magnetic properties of Y- and Lu- Iron Garnets using the Bethe- Peierls-Weiss method modified to suit complex systems like these Garnets. We consider these Garnets as described by Heisenberg Hamiltonian with two sublattices (a,d) and determine the exchange interaction parameters Jad, Jaa and Jdd by matching the exerimental susceptibility curves. We find Jaa and Jdd to be much smaller than those determined by Néel theory, and consistent with those obtained by the study of spin wave spectra; the spin wave dispersion relation constant obtained using these parameters gives good agreement with the experimental values.

Mg,Ce co-doped Lu2Gd1(Ga,Al)5O12 by micro-pulling down method and their luminescence properties

NASA Astrophysics Data System (ADS)

Kamada, Kei; Yamaguchi, Hiroaki; Yoshino, Masao; Kurosawa, Shunsuke; Shoji, Yasuhiro; Yokota, Yuui; Ohashi, Yuji; Pejchal, Jan; Nikl, Martin; Yoshikawa, Akira

2018-04-01

The effects of Mg co-doping on the scintillation properties of Ce:Lu2Gd1(Ga,Al)5O12 (LGGAG) single crystals with different Ga/Al ratios were investigated. Mg co-doped and non co-doped Ce:LGGAG single crystals were grown by the micro-pulling down (µ-PD) method and then cut, polished and annealed for each measurement. Absorption spectra, radioluminescence (RL) spectra, pulse height spectra, and scintillation decay were measured to reveal the effect of Mg co-doping. Ce4+ charge transfer (CT) absorption band peaking at ∼260 nm was observed in Mg co-doped samples, which is in good agreement with previous reports for the Ce4+ CT absorption band in other garnet-based crystals. The scintillation decay time tended to be accelerated and the light yield tended to be decreased by Mg co-doping at higher Ga concentrations.

Gallium 67 scintigraphy in glomerular disease

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

Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.

1988-12-01

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 diabeticmore » 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.« less

Assessment of gallium-67 scanning in pulmonary and extrapulmonary sarcoidosis

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

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

1986-01-01

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

Properties of transparent (Gd,Lu)3(Al,Ga)5O12:Ce ceramic with Mg, Ca and Ce co-dopants

NASA Astrophysics Data System (ADS)

Wang, Yimin; Baldoni, Gary; Brecher, Charles; Rhodes, William H.; Shirwadkar, Urmila; Glodo, Jarek; Shah, Ishaan; Ji, Chuncheng

2015-08-01

Cerium activated mixed lutetium/gadolinium- and aluminum/gallium-based garnets have great potential as host scintillators for medical imaging applications. (Gd,Lu)3(Al,Ga)5O12:Ce and denoted as GLuGAG feature high effective atomic number and good light yield, which make it particularly attractive for Positron Emission Tomography (PET) and other γ-ray detection applications. For PET application, rapid decay and good timing resolution are extremely important. Most Ce-doped mixed garnet materials such as GLuGAG:Ce, have their main decay component at around 80 ns. However, it has been reported that the decays of some single crystal scintillators (e.g., LSO and GGAG) can be effectively accelerated by codoping with selected additives such as Ca, Mg and B. In this study, transparent polycrystalline (Gd,Lu)3(Al,Ga)5O12:Ce ceramics codoped with Ca or Mg or additional Ce, were fabricated by the sinter-HIP approach. It was found the transmission of the ceramics are closely related to the microstructure of the ceramics. As the co-dopant levels increase, 2nd phase occurs in the ceramic and thus transparency of the ceramic decreases. Ca and Mg co-doping in GLuGAG:Ce ceramic effectively accelerate decays of GLuGAG:Ce ceramics at a cost of light output. However, additional Ce doping in the GLuGAG:Ce has no benefit on improving decay time but, on the other hand, reduces transmission, light output. The mechanism under the different scintillation behaviors with Mg, Ca and Ce dopants are discussed. The results suggest that decay time of GLuGAG:Ce ceramics can be effectively tailored by co-doping GLuGAG:Ce ceramic with Mg and Ca for applications with optimal timing resolution.

Periodontal and peri-implant wound healing following laser therapy.

PubMed

Aoki, Akira; Mizutani, Koji; Schwarz, Frank; Sculean, Anton; Yukna, Raymond A; Takasaki, Aristeo A; Romanos, Georgios E; Taniguchi, Yoichi; Sasaki, Katia M; Zeredo, Jorge L; Koshy, Geena; Coluzzi, Donald J; White, Joel M; Abiko, Yoshimitsu; Ishikawa, Isao; Izumi, Yuichi

2015-06-01

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2 , neodymium-doped yttrium-aluminium-garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er:YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal

Gallium-67 uptake by the thyroid associated with progressive systemic sclerosis

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

Sjoberg, R.J.; Blue, P.W.; Kidd, G.S.

1989-01-01

Although thyroidal uptake of gallium-67 has been described in several thyroid disorders, gallium-67 scanning is not commonly used in the evaluation of thyroid disease. Thyroidal gallium-67 uptake has been reported to occur frequently with subacute thyroiditis, anaplastic thyroid carcinoma, and thyroid lymphoma, and occasionally with Hashimoto's thyroiditis and follicular thyroid carcinoma. A patient is described with progressive systemic sclerosis who, while being scanned for possible active pulmonary involvement, was found incidentally to have abnormal gallium-67 uptake only in the thyroid gland. Fine needle aspiration cytology of the thyroid revealed Hashimoto's thyroiditis. Although Hashimoto's thyroiditis occurs with increased frequency in patientsmore » with progressive systemic sclerosis, thyroidal uptake of gallium-67 associated with progressive systemic sclerosis has not, to our knowledge, been previously described. Since aggressive thyroid malignancies frequently are imaged by gallium-67 scintigraphy, fine needle aspiration cytology of the thyroid often is essential in the evaluation of thyroidal gallium-67 uptake.« less

Correlation by Rb-Sr geochronology of garnet growth histories from different structural levels within the Tauern Window, Eastern Alps

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

Christensen, John N.; Selverstone, Jane; Rosenfeld, John L.

1993-06-01

In order to evaluate rates of tectonometamorphic processes, growth rates of garnets from metamorphic rocks of the Tauern Window, Eastern Alps were measured using Rb-Sr isotopes. The garnet growth rates were determined from Rb-Sr isotopic zonation of single garnet crystals and the Rb-Sr isotopic compositions of their associated rock matrices. Garnets were analyzed from the Upper Schieferhulle (USH) and Lower Schieferhulle (LSH) within the Tauern Window. Two garnets from the USH grew at rates of 0.67(-0.13)+0.19 mm/million years and 0.88(-0.19)+0.34 mm/million years, respectively, indicating an average growth duration of 5.4 +- 1.7 million years. The duration of growth coupled withmore » the amount of rotation recorded by inclusion trails in the USH garnets yields an average shear-strain rate during garnet growth of 2.7(-0.7)+1.2 x 10(-14) s-1 . Garnet growth in the sample from the USH occurred between 35.4 +- 0.6 and 30 +- 0.8 Ma. The garnet from the LSH grew at a rate of 0.23 +- 0.015 mm/mil lion years, between 62 +- 1.5 Ma and 30.2 +- 1.5 Ma. Contemporaneous cessation of garnet growth in both units at approximately 30 Ma is in accord with previous dating of the thermal peak of metamorphism in the Tauern Window. Correlation with previously published pressure-temperature paths for garnets from the USH and LSH yields approximate rates of burial, exhumation and heating during garnet growth. Assuming that these P - T paths are applicable to the garnets in this study, the contemporaneous exhumation rates recorded by garnet in the USH and LSH were approximately 4(-2)+3 mm/year and 2 +- 1 mm/year, respectively. [References: 34]« less

Internal photopumping of Nd3+ (2H9/2, 4F5/2) states in yttrium aluminum garnet by excitation transfer from oxygen deficiency centers and Fe3+ continuum emission

NASA Astrophysics Data System (ADS)

Hewitt, J. D.; Spinka, T. M.; Senin, A. A.; Eden, J. G.

2011-07-01

Photoexcitation of Nd3+ (2H9/2, 4F5/2) states by the broad (˜70 nm FWHM), near-infrared continuum provided by Fe3+ has been observed at 300 K in bulk yttrium aluminum garnet (YAG) crystals doped with trace concentrations (<50 ppm) of Fe, Cr, and Eu. Irradiation of YAG at 248 nm with a KrF laser, which excites the oxygen deficiency center (ODC) in YAG having peak absorption at ˜240 nm, culminates in ODC→Fe3+ excitation transfer and subsequent Fe3+ emission. This internal optical pumping mechanism for rare earth ions is unencumbered by the requirement for donor-acceptor proximity that constrains conventional Förster-Dexter excitation transfer in co-doped crystals.

Construction of an electrode modified with gallium(III) for voltammetric detection of ovalbumin.

PubMed

Sugawara, Kazuharu; Okusawa, Makoto; Takano, Yusaku; Kadoya, Toshihiko

2014-01-01

Electrodes modified with gallium(III) complexes were constructed to detect ovalbumin (OVA). For immobilization of a gallium(III)-nitrilotriacetate (NTA) complex, the electrode was first covered with collagen film. After the amino groups of the film had reacted with isothiocyanobenzyl-NTA, the gallium(III) was then able to combine with the NTA moieties. Another design featured an electrode cast with a gallium(III)-acetylacetonate (AA) complex. The amount of gallium(III) in the NTA complex was equivalent to one-quarter of the gallium(III) that could be utilized from an AA complex. However, the calibration curves of OVA using gallium(III)-NTA and gallium(III)-AA complexes were linear in the ranges of 7.0 × 10(-11) - 3.0 × 10(-9) M and 5.0 × 10(-10) - 8.0 × 10(-9) M, respectively. The gallium(III) on the electrode with NTA complex had high flexibility due to the existence of a spacer between the NTA and the collagen film, and, therefore, the reactivity of the gallium(III) to OVA was superior to that of the gallium(III)-AA complex with no spacer.

Guided-Wave Optic Devices for Integrated Optic Information Processing.

DTIC Science & Technology

1984-08-08

Modulation and switching of light waves in Yttrium iron garnet (YIG)- Gadolinium gallium garnet (GGG) waveguides using Farady rotation , and light...switch, an electrooptic analog-to-digital converter using a Fabry -Perot modula- tor array, and a noncollinear magnetooptic modulator using magnetostatic...data routing in electronic computer networks. ELECTROOPTIC ANALOG-TO-DIGITAL CONVERTER USING CHANNEL WAVEGUIDE FABRY -PEROT MODULATOR ARRAY One of the

Sensitizing effects of gallium citrate on hyperthermic cell killing in vitro.

PubMed

Miyazaki, N; Nakano, H; Kawakami, N; Kugotani, M; Nishihara, K; Aoki, Y; Shinohara, K

2000-01-01

The lethal effects of gallium citrate in combination with heat were studied using four cell lines, L5178Y, FM3A, P388 and HeLa. Cells were incubated with different concentrations (0.2 2 mM) of gallium citrate at 37 degrees C for 24 h and heated at a range of temperatures from 40-44 degrees C for various time periods up to 6 h in the absence of gallium citrate. Survival and cell viability were determined by clonogenic assay and the dye-exclusion test, respectively. All of the cell lines tested were insensitive to heat below 41 degrees C, but were very sensitive to heat above 43 degrees C. Gallium citrate was cytotoxic to these cell lines at different levels: P388 and HeLa were far more sensitive than L5178Y and FM3A. The killing effects of heat at 41 degrees C were greatly enhanced by gallium citrate in L5178Y and P388 cells. The Arrhenius analysis for the lethal effect of heat, determined by clonogenic assay, in L5178Y cells showed that the transition temperature was remarkably decreased for the gallium-treated cells from approximately 43 degrees C to 41 degrees C. The mechanism for this decrease in the transition temperature may be attributable to the additional effects of gallium citrate on energy metabolism. Preincubation with 0.05 mM gallium citrate at 37 degrees C for 7 days also enhanced heat sensitization at 41 degrees C in L5178Y. This preincubation condition may correspond to the condition for the continuous infusion of gallium that is clinically used for cancer treatment. In contrast, treatment with gallium did not greatly enhance the sensitivity of FM3A or HeLa cells to heat at 41 degrees C, but the effects of gallium were significant.

Direct determination of gallium on polyurethane foam by X-ray fluorescence.

PubMed

Carvalho, M S; Medeiros, J A; Nóbrega, A W; Mantovano, J L; Rocha, V P

1995-01-01

Gallium chloride is easily extracted from 6M HCl by comminuted polyether-type polyurethane foam. After the extraction step, the gallium absorbed by the PU foam can be quantitatively determined by X-ray fluorescence. A procedure for the direct determination of gallium absorbed by PU foam by XRFS is thus described. Gallium is determined at levels as low as 60 ng/ml (C(L)), with a calibration sensitivity of 424 cps ml/mug, within a linear range 0.1-2.30 mug/ml. The procedure investigated was successfully applied to determination of gallium in aluminum alloys, bauxite and industrial residue samples.

Challenges for critical raw material recovery from WEEE - The case study of gallium.

PubMed

Ueberschaar, Maximilian; Otto, Sarah Julie; Rotter, Vera Susanne

2017-02-01

Gallium and gallium compounds are more frequently used in future oriented technologies such as photovoltaics, light diodes and semiconductor technology. In the long term the supply risk is estimated to be critical. Germany is one of the major primary gallium producer, recycler of gallium from new scrap and GaAs wafer producer. Therefore, new concepts for a resource saving handling of gallium and appropriate recycling strategies have to be designed. This study focus on options for a possible recycling of gallium from waste electric and electronic equipment. To identify first starting points, a substance flow analysis was carried out for gallium applied in integrated circuits applied on printed circuit boards and for LEDs used for background lighting in Germany in 2012. Moreover, integrated circuits (radio amplifier chips) were investigated in detail to deduce first approaches for a recycling of such components. An analysis of recycling barriers was carried out in order to investigate general opportunities and risks for the recycling of gallium from chips and LEDs. Results show, that significant gallium losses arose in primary production and in waste management. 93±11%, equivalent to 43,000±4700kg of the total gallium potential was lost over the whole primary production process until applied in electronic goods. The largest share of 14,000±2300kggallium was lost in the production process of primary raw materials. The subsequent refining process was related to additional 6900±3700kg and the chip and wafer production to 21,700±3200kg lost gallium. Results for the waste management revealed only low collection rates for related end-of-life devices. Not collected devices held 300 ± 200 kg gallium. Due to the fact, that current waste management processes do not recover gallium, further 80 ± 10 kg gallium were lost. A thermal pre-treatment of the chips, followed by a manual separation allowed an isolation of gallium rich fractions, with gallium mass fractions up to

High-Throughput Continuous Hydrothermal Synthesis of Transparent Conducting Aluminum and Gallium Co-doped Zinc Oxides.

PubMed

Howard, Dougal P; Marchand, Peter; McCafferty, Liam; Carmalt, Claire J; Parkin, Ivan P; Darr, Jawwad A

2017-04-10

High-throughput continuous hydrothermal flow synthesis was used to generate a library of aluminum and gallium-codoped zinc oxide nanoparticles of specific atomic ratios. Resistivities of the materials were determined by Hall Effect measurements on heat-treated pressed discs and the results collated into a conductivity-composition map. Optimal resistivities of ∼9 × 10 -3 Ω cm were reproducibly achieved for several samples, for example, codoped ZnO with 2 at% Ga and 1 at% Al. The optimum sample on balance of performance and cost was deemed to be ZnO codoped with 3 at% Al and 1 at% Ga.

The CaGeO3 Ca3Fe2Ge3O12 garnet join: an experimental study

NASA Astrophysics Data System (ADS)

Iezzi, Gianluca; Boffa-Ballaran, Tiziana; McCammon, Catherine; Langenhorst, Falko

2005-06-01

Germanate garnets are often used as isostructural analogues of silicate garnets to provide insight into the crystal chemistry and symmetry of the less accessible natural garnet solid solutions. We synthesised two series of germanate garnets at 3 GPa along the joinVIIICa3VI(CaGe)IVGe3O12 VIIICa3VIFe2IVGe3O12 at 900 °C and 1,100 °C. Samples with compositions close to the CaGeO3 end-member consist of tetragonal garnet with a small amount of triclinic CaGe2O5. Samples with nominal compositions between XFe=0.4 and 1.0 consist of a mixture of tetragonal and cubic garnets; whereas, single-phase cubic garnets were obtained for compositions with XFe>1.2 (XFe gives the iron content expressed in atoms per formula unit, and varies between 0 and 2 along the join). Run products which were primarily single-phase garnet were investigated using Mössbauer spectroscopy. Spectra from samples synthesised at 1,100°C consist of one well-resolved doublet that can be assigned to Fe3+ in the octahedral site of the garnet structure. A second doublet, present primarily in samples synthesised at 900°C, can be assigned to Fe2+ at the octahedral sites of the garnet structure. The relative abundance of Fe2+ decreases with increasing iron content. Transmission electron microscopy analyses confirm this tendency and show that the garnets are essentially defect-free. The unit-cell parameters of tetragonal VIIICa3VI(CaGe)IVGe3O3 garnet decrease with increasing synthesis temperature, and the deviation from cubic symmetry becomes smaller. Cubic garnets show a linear decrease of unit-cell parameter with increasing iron content. The results are discussed in the context of iron incorporation into VIIIMg3VI(MgSi)IVSi3O3 majorite.

Nuclear microprobe imaging of gallium nitrate in cancer cells

NASA Astrophysics Data System (ADS)

Ortega, Richard; Suda, Asami; Devès, Guillaume

2003-09-01

Gallium nitrate is used in clinical oncology as treatment for hypercalcemia and for cancer that has spread to the bone. Its mechanism of antitumor action has not been fully elucidated yet. The knowledge of the intracellular distribution of anticancer drugs is of particular interest in oncology to better understand their cellular pharmacology. In addition, most metal-based anticancer compounds interact with endogenous trace elements in cells, altering their metabolism. The purpose of this experiment was to examine, by use of nuclear microprobe analysis, the cellular distribution of gallium and endogenous trace elements within cancer cells exposed to gallium nitrate. In a majority of cellular analyses, gallium was found homogeneously distributed in cells following the distribution of carbon. In a smaller number of cells, however, gallium appeared concentrated together with P, Ca and Fe within round structures of about 2-5 μm diameter located in the perinuclear region. These intracellular structures are typical of lysosomial material.

Gallium uptake by transferrin and interaction with receptor 1.

PubMed

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

2007-01-01

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.

The gallium melting-point standard: a determination of the liquid-solid equilibrium temperature of pure gallium on the International Practical Temperature Scale of 1968.

PubMed

Thornton, D D

1977-01-01

The sharpness and reproducibility of the gallium melting point were studied and the melting temperature of gallium in terms of IPTS-68 was determined. Small melting-point cells designed for use with thermistors are described. Nine gallium cells including three levels of purity were used in 68 separate determinations fo the melting point. The melting point of 99.99999% pure gallium in terms of IPTS-68 is found to be 29.771(4) +/- 0.001(4) degree C; the melting range is less than 0.0005 degree C and is reproducible to +/- 0.0004 degree C.

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

NASA Technical Reports Server (NTRS)

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.;

Extremely dense microstructure and enhanced ionic conductivity in hot-isostatic pressing treated cubic garnet-type solid electrolyte of Ga2O3-doped Li7La3Zr2O12

NASA Astrophysics Data System (ADS)

Qin, Shiying; Zhu, Xiaohong; Jiang, Yue; Ling, Ming’En; Hu, Zhiwei; Zhu, Jiliang

A large number of pores and a low relative density that are frequently observed in solid electrolytes reduce severely their ionic conductivity and thus limit their applicability. Here, we report on the use of hot isostatic pressing (HIP) for ameliorating the garnet-type lithium-ion conducting solid electrolyte of Ga2O3-doped Li7La3Zr2O12 (Ga-LLZO) with nominal composition of Li6.55Ga0.15La3Zr2O12. The Ga-LLZO pellets were conventionally sintered at 1075∘C for 12h, and then were followed by HIP treatment at 120MPa and 1160∘C under an Ar atmosphere. It is found that the HIP-treated Ga-LLZO shows an extremely dense microstructure and a significantly enhanced ionic conductivity. Coherent with the increase in relative density from 90.5% (untreated) to 97.5% (HIP-treated), the ionic conductivity of the HIP-treated Ga-LLZO reaches as high as 1.13×10‑3S/cm at room temperature (25∘C), being two times higher than that of 4.58×10‑4S/cm for the untreated one.

Composition of the core from gallium metal–silicate partitioning experiments

DOE PAGES

Blanchard, I.; Badro, J.; Siebert, J.; ...

2015-07-24

We present gallium concentration (normalized to CI chondrites) in the mantle is at the same level as that of lithophile elements with similar volatility, implying that there must be little to no gallium in Earth's core. Metal-silicate partitioning experiments, however, have shown that gallium is a moderately siderophile element and should be therefore depleted in the mantle by core formation. Moreover, gallium concentrations in the mantle (4 ppm) are too high to be only brought by the late veneer; and neither pressure, nor temperature, nor silicate composition has a large enough effect on gallium partitioning to make it lithophile. Wemore » therefore systematically investigated the effect of core composition (light element content) on the partitioning of gallium by carrying out metal–silicate partitioning experiments in a piston–cylinder press at 2 GPa between 1673 K and 2073 K. Four light elements (Si, O, S, C) were considered, and their effect was found to be sufficiently strong to make gallium lithophile. The partitioning of gallium was then modeled and parameterized as a function of pressure, temperature, redox and core composition. A continuous core formation model was used to track the evolution of gallium partitioning during core formation, for various magma ocean depths, geotherms, core light element contents, and magma ocean composition (redox) during accretion. The only model for which the final gallium concentration in the silicate Earth matched the observed value is the one involving a light-element rich core equilibrating in a FeO-rich deep magma ocean (>1300 km) with a final pressure of at least 50 GPa. More specifically, the incorporation of S and C in the core provided successful models only for concentrations that lie far beyond their allowable cosmochemical or geophysical limits, whereas realistic O and Si amounts (less than 5 wt.%) in the core provided successful models for magma oceans deeper that 1300 km. In conclusion, these results

Graphical representations of the chemistry of garnets in a three-dimensional MATLAB based provenance plot

NASA Astrophysics Data System (ADS)

Knierzinger, Wolfgang; Palzer, Markus; Wagreich, Michael; Meszar, Maria; Gier, Susanne

2016-04-01

A newly developed, MATLAB based garnet provenance plot allows a three-dimensional tetrahedral representation of the chemistry of garnets for the endmembers almandine, pyrope, spessartine and grossular. Based on a freely accessible database of Suggate & Hall (2013) and additional EPMA-data on the internet, the chemistry of more than 2500 garnets was evaluated and used to create various subfields that correspond to different facies conditions of metapelitic, metasomatic and metaigneous rocks as well as granitic rocks. These triangulated subfields act as reference structures within the tetrahedron, facilitating assignments of garnet chemistries to different lithologies. In comparison with conventional tenary garnet discrimination diagrams by Mange & Morton (2007), Wright/Preston et al. (1938/2002) and Aubrecht et al. (2009), this tetrahedral provenance plot enables a better assessment of the conditions of formation of garnets by reducing the overlapping of certain subfields. In particular, a clearer distinction between greenschist facies rocks, amphibolite facies rocks and granitic rocks can be achieved. First applications of the tetrahedral garnet plot provided new insights on sedimentary processes during the Lower Miocene in the pre-Alpine Molasse basin. Bibliography Aubrecht, R., Meres, S., Sykora, M., Mikus, T. (2009). Provenance of the detrital garnets and spinels from the Albian sediments of the Czorsztyn Unit (Pieniny Klippen Belt , Western Carpathians, Slovakia). In: Geologica Carpathica, Dec. 2009, 60, 6, pp. 463-483. Mange, M.A., Morton, A.C. (2007). Geochemistry of Heavy Minerals. In: Mange, M.A. & Wright, D.T.(2007).Heavy Minerals in Use, Amsterdam, pp. 345-391. Preston, J., Hartley, A., Mange-Rajetzky, M., Hole, M., May, G., Buck, S., Vaughan, L. (2002). The provenance of Triassic continental sandstones from the Beryl Field, northern North Sea: Mineralogical, geochemical and sedimentological constraints. In: Journal of Sedimentary Research, 72, pp. 18

Lu-Hf Garnet Geochronology Reveals the Tectonic History of Precambrian Rocks in the Southern Rocky Mountains

NASA Astrophysics Data System (ADS)

Aronoff, R.; Andronicos, C.; Vervoort, J. D.; Hunter, R. A.

2014-12-01

Lu-Hf garnet dating of Proterozoic rocks of the southwestern United States provides constraints on the timing and geographic extent of metamorphism associated with the Yavapai, Mazatzal, and newly recognized Picuris orogenies. Prior work focusing on U-Pb dating of plutons and Ar geochronology has left the timing of prograde metamorphism ambiguous, particularly in northern New Mexico and southern Colorado. Because the Lu-Hf system dates the onset of garnet growth, it can constrain the timing of the prograde P-T path. Garnet schist samples from central and northern New Mexico exhibit garnet growth restricted to the time period between ~1460 and 1400 Ma. In the Picuris and Manzano mountains, the oldest Lu-Hf garnet ages predate the U-Pb ages of ~1.4 Ga plutons located near the dated samples. This implies that garnet growth, and therefore the onset of amphibolite facies metamorphism, cannot be driven by contact metamorphism, as has been previously inferred. Garnet-bearing samples from the Needle and Wet Mountains in southern Colorado display a range of garnet ages between ~1750 and 1470 Ma. A garnet gneiss from the Needle Mountains in southwestern Colorado yields an age of 1748 Ma, which is consistent with the Yavapai orogeny. This Lu-Hf garnet age has not been reset by contact metamorphism associated with the emplacement of the ~1.4 Ga Eolus batholith. Anatectic garnet in an orthogneiss from the northern Wet Mountains yields an age of 1601 Ma and is interpreted to date partial melting at the close of the Mazatzal orogeny. A 1476 Ma garnet age from the aureole of the 1440 Ma Oak Creek pluton is interpreted to date upper amphibolite facies metamorphism. The age distribution of these samples shows that rocks in Colorado underwent a complex, poly-metamorphic history, while rocks in New Mexico underwent a single progressive metamorphic event. This contrast implies that the boundary between rocks deformed and metamorphosed during the ~1800-1600 Ma Yavapai and Mazatzal

Mixed garnet laser for a water vapour DIAL

NASA Astrophysics Data System (ADS)

Treichel, Rainer; Strohmaier, Stephan; Nikolov, Susanne; Eichler, Hans-Joachim; Murphy, Eamonn

2017-11-01

For the water vapour DIAL "WALES" the wavelength regions around 935 nm, 942 nm and 944 nm have been identified as the most suitable wavelength ranges. These wavelengths can be obtained using opticalparametric-oscillators (OPOs), stimulated Raman shifters and the Ti-Sapphire laser but none of these systems could deliver all the needed parameters like beam quality, efficiency, pulse length and energy yet. Also these systems are comparably big and heavy making them less suitable for a satellite based application. A fourth possibility to achieve these wavelength ranges is to shift the quasi-3-level laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing aluminium and yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals or special pump lasers are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. In a first phase such mixed garnet crystals had been grown and characterised. The outcome was the selection of the gadolinium-scandium garnet for the most suitable laser crystal. During a second phase the complete laser system with output energy about 18 mJ in single 20 ns pulses and up to 8 mJ in free running mode with a combined pulse width of 250 μs at 942 nm have been demonstrated. The results of the first laser operation and the achieved performance parameter are reported.

Isotopic composition of Mg and Fe in garnet peridotites from the Kaapvaal and Siberian cratons

NASA Astrophysics Data System (ADS)

An, Yajun; Huang, Jin-Xiang; Griffin, W. L.; Liu, Chuanzhou; Huang, Fang

2017-03-01

We present Mg and Fe isotopic data for whole rocks and separated minerals (olivine, clinopyroxene, orthopyroxene, garnet, and phlogopite) of garnet peridotites that equilibrated at depths of 134-186 km beneath the Kaapvaal and Siberian cratons. There is no clear difference in δ26Mg and δ56Fe of garnet peridotites from these two cratons. δ26Mg of whole rocks varies from -0.243‰ to -0.204‰ with an average of -0.225 ± 0.037‰ (2σ, n = 19), and δ56Fe from -0.038‰ to 0.060‰ with an average of -0.003 ± 0.068‰ (2σ, n = 19). Both values are indistinguishable from the fertile upper mantle, indicating that there is no significant Mg-Fe isotopic difference between the shallow and deep upper mantle. The garnet peridotites from ancient cratons show δ26Mg similar to komatiites and basalts, further suggesting that there is no obvious Mg isotopic fractionation during different degrees of partial melting of deep mantle peridotites and komatiite formation. The precision of the Mg and Fe isotope data (⩽±0.05‰ for δ26Mg and δ56Fe, 2σ) allows us to distinguish inter-mineral isotopic fractionations. Olivines are in equilibrium with opx in terms of Mg and Fe isotopes. Garnets have the lowest δ26Mg and δ56Fe among the coexisting mantle minerals, suggesting the dominant control of crystal structure on the Mg-Fe isotopic compositions of garnets. Elemental compositions and mineralogy suggest that clinopyroxene and garnet were produced by later metasomatic processes as they are not in chemical equilibrium with olivine or orthopyroxene. This is consistent with the isotopic disequilibrium of Mg and Fe isotopes between orthopyroxene/olivine and garnet/clinopyroxene. Combined with one sample showing slightly heavy δ26Mg and much lighter δ56Fe, these disequilibrium features in the garnet peridotites reveal kinetic isotopic fractionation due to Fe-Mg inter-diffusion during reaction between peridotites and percolating melts in the Kaapvaal craton.

Microbiologic results after non-surgical erbium-doped:yttrium, aluminum, and garnet laser or air-abrasive treatment of peri-implantitis: a randomized clinical trial.

PubMed

Persson, G Rutger; Roos-Jansåker, Ann-Marie; Lindahl, Christel; Renvert, Stefan

2011-09-01

The purpose of this study is to assess clinical and microbiologic effects of the non-surgical treatment of peri-implantitis lesions using either an erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser or an air-abrasive subgingival polishing method. In a 6-month clinical trial, 42 patients with peri-implantitis were treated at one time with an Er:YAG laser or an air-abrasive device. Routine clinical methods were used to monitor clinical conditions. Baseline and 6-month intraoral radiographs were assessed with a software program. The checkerboard DNA-DNA hybridization method was used to assess 74 bacterial species from the site with the deepest probing depth (PD) at the implant. Non-parametric tests were applied to microbiology data. PD reductions (mean ± SD) were 0.9 ± 0.8 mm and 0.8 ± 0.5 mm in the laser and air-abrasive groups, respectively (not significant). No baseline differences in bacterial counts between groups were found. In the air-abrasive group, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus anaerobius were found at lower counts at 1 month after therapy (P <0.001) and with lower counts in the laser group for Fusobacterium nucleatum naviforme (P = 0.002), and Fusobacterium nucleatum nucleatum (P = 0.002). Both treatments failed to reduce bacterial counts at 6 months. Porphyromonas gingivalis counts were higher in cases with progressive peri-implantitis (P <0.001). At 1 month, P. aeruginosa, S. aureus, and S. anaerobius were reduced in the air-abrasive group, and Fusobacterium spp. were reduced in the laser group. Six-month data demonstrated that both methods failed to reduce bacterial counts. Clinical improvements were limited.

Two chain gallium fluorodiphosphates: synthesis, structure solution, and their transient presence during the hydrothermal crystallisation of a microporous gallium fluorophosphate.

PubMed

Millange, Franck; Walton, Richard I; Guillou, Nathalie; Loiseau, Thierry; O'Hare, Dermot; Férey, Gérard

2002-04-21

Two novel gallium fluorodiphosphates have been isolated and their structures solved ab initio from powder X-ray diffraction data; the materials readily interconvert under hydrothermal conditions, and are metastable with respect to an open-framework zeolitic gallium fluorophosphate, during the synthesis of which they are present as transient intermediates.

Mesoproterozoic syntectonic garnet within Belt Supergroup metamorphic tectonites: Evidence of Grenville-age metamorphism and deformation along northwest Laurentia

USGS Publications Warehouse

Nesheim, T.O.; Vervoort, J.D.; McClelland, W.C.; Gilotti, J.A.; Lang, H.M.

2012-01-01

Northern Idaho contains Belt-Purcell Supergroup equivalent metamorphic tectonites that underwent two regional deformational and metamorphic events during the Mesoproterozoic. Garnet-bearing pelitic schists from the Snow Peak area of northern Idaho yield Lu-Hf garnet-whole rock ages of 1085??2. Ma, 1198??79. Ma, 1207??8. Ma, 1255??28. Ma, and 1314??2. Ma. Garnet from one sample, collected from the Clarkia area, was micro-drilled to obtain separate core and rim material that produced ages of 1347??10. Ma and 1102??47. Ma. The core versus rim ages from the micro-drilled sample along with the textural and spatial evidence of the other Lu-Hf garnet ages indicate two metamorphic garnet growth events at ~. 1330. Ma (M1) and ~. 1080. Ma (M2) with the intermediate ages representing mixed ages. Some garnet likely nucleated and grew M1 garnet cores that were later overgrown by younger M2 garnet rims. Most garnet throughout the Clarkia and Snow Peak areas are syntectonic with a regional penetrative deformational fabric, preserved as a strong preferred orientation of metamorphic matrix minerals (e.g., muscovite and biotite). The syntectonic garnets are interpreted to represent one regional, coeval metamorphic and deformation event at ~. 1080. Ma, which overlaps in time with the Grenville Orogeny. The older ~. 1330. Ma ages may represent an extension of the East Kootenay Orogeny described in western Canada. These deformational and metamorphic events indicate that western Laurentia (North America) was tectonically active in the Mesoproterozoic and during the assembly of the supercontinent Rodinia. ?? 2011 Elsevier B.V.

Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

PubMed Central

Fu, Kun (Kelvin); Gong, Yunhui; Liu, Boyang; Zhu, Yizhou; Xu, Shaomao; Yao, Yonggang; Luo, Wei; Wang, Chengwei; Lacey, Steven D.; Dai, Jiaqi; Chen, Yanan; Mo, Yifei; Wachsman, Eric; Hu, Liangbing

2017-01-01

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li7La3Zr2O12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10−3 to 10−4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnet solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm2 for the surface-engineered garnet/Li. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries. PMID:28435874

Design and characterization of Yb and Nd doped transparent ceramics for high power laser applications: recent advancements

NASA Astrophysics Data System (ADS)

Lapucci, A.; Vannini, M.; Ciofini, M.; Pirri, A.; Nikl, M.; Li, J.; Esposito, L.; Biasini, V.; Hostasa, J.; Goto, T.; Boulon, G.; Maksimov, R.; Gizzi, L.; Labate, L.; Toci, G.

2017-01-01

We report a review on our recent developments in Yttebium and Neodymium doped laser ceramics, along two main research lines. The first is the design and development of Yb:YAG ceramics with non uniform doping distribution, for the management of thermo-mechanical stresses and for the mitigation of ASE: layered structures have been produced by solid state reactive sintering, using different forming processes (spray drying and cold press of the homogenized powders, tape cast of the slurry); samples have been characterized and compared to FEM analysis. The second is the investigation of Lutetium based ceramics (such as mixed garnets LuYAG and Lu2O3); this interest is mainly motivated by the favorable thermal properties of these hosts under high doping. We recently obtained for the first time high efficiency laser emission from Yb doped LuYAG ceramics. The investigation on sesquioxides has been focused on Nddoped Lu2O3 ceramics, fabricated with the Spark Plasma Sintering method (SPS). We recently achieved the first laser emission above 1 W from Nd doped Lu2O3 ceramics fabricated by SPS.

Gallium induces the production of virulence factors in Pseudomonas aeruginosa.

PubMed

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

2014-02-01

The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by competing with iron, we hypothesized that it ultimately will lead cells to an iron deficiency status. As iron deficiency promotes the expression of virulence factors in vitro and promotes the pathogenicity of P. aeruginosa in animal models, it is anticipated that treatment with gallium will also promote the production of virulence factors. To test this hypothesis, the reference strain PA14 and two clinical isolates from patients with cystic fibrosis were exposed to gallium, and their production of pyocyanin, rhamnolipids, elastase, alkaline protease, alginate, pyoverdine, and biofilm was determined. Gallium treatment induced the production of all the virulence factors tested in the three strains except for pyoverdine. In addition, as the Ga-induced virulence factors are quorum sensing controlled, co-administration of Ga and the quorum quencher brominated furanone C-30 was assayed, and it was found that C-30 alleviated growth inhibition from gallium. Hence, adding both C-30 and gallium may be more effective in the treatment of P. aeruginosa infections. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

A new statistical analysis of rare earth element diffusion data in garnet

NASA Astrophysics Data System (ADS)

Chu, X.; Ague, J. J.

2015-12-01

The incorporation of rare earth elements (REE) in garnet, Sm and Lu in particular, links garnet chemical zoning to absolute age determinations. The application of REE-based geochronology depends critically on the diffusion behaviors of the parent and daughter isotopes. Previous experimental studies on REE diffusion in garnet, however, exhibit significant discrepancies that impact interpretations of garnet Sm/Nd and Lu/Hf ages.We present a new statistical framework to analyze diffusion data for REE using an Arrhenius relationship that accounts for oxygen fugacity, cation radius and garnet unit-cell dimensions [1]. Our approach is based on Bayesian statistics and is implemented by the Markov chain Monte Carlo method. A similar approach has been recently applied to model diffusion of divalent cations in garnet [2]. The analysis incorporates recent data [3] in addition to the data compilation in ref. [1]. We also include the inter-run bias that helps reconcile the discrepancies among data sets. This additional term estimates the reproducibility and other experimental variabilities not explicitly incorporated in the Arrhenius relationship [2] (e.g., compositional dependence [3] and water content).The fitted Arrhenius relationships are consistent with the models in ref. [3], as well as refs. [1]&[4] at high temperatures. Down-temperature extrapolation leads to >0.5 order of magnitude faster diffusion coefficients than in refs. [1]&[4] at <750 °C. The predicted diffusion coefficients are significantly slower than ref. [5]. The fast diffusion [5] was supported by a field test of the Pikwitonei Granulite—the garnet Sm/Nd age postdates the metamorphic peak (750 °C) by ~30 Myr [6], suggesting considerable resetting of the Sm/Nd system during cooling. However, the Pikwitonei Granulite is a recently recognized UHT terrane with peak temperature exceeding 900 °C [7]. The revised closure temperature (~730 °C) is consistent with our new diffusion model.[1] Carlson (2012) Am

Control of Gallium Oxide Growth on Liquid Metal Eutectic Gallium/Indium Nanoparticles via Thiolation.

PubMed

Farrell, Zachary J; Tabor, Christopher

2018-01-09

Eutectic gallium-indium alloy (EGaIn, a room-temperature liquid metal) nanoparticles are of interest for their unique potential uses in self-healing and flexible electronic devices. One reason for their interest is due to a passivating oxide skin that develops spontaneously on exposure to ambient atmosphere which resists deformation and rupture of the resultant liquid particles. It is then of interest to develop methods for control of this oxide growth process. It is hypothesized here that functionalization of EGaIn nanoparticles with thiolated molecules could moderate oxide growth based on insights from the Cabrera-Mott oxidation model. To test this, the oxidation dynamics of several thiolated nanoparticle systems were tracked over time with X-ray photoelectron spectroscopy. These results demonstrate the ability to suppress gallium oxide growth by up to 30%. The oxide progressively matures over a 28 day period, terminating in different final thicknesses as a function of thiol selection. These results indicate not only that thiols moderate gallium oxide growth via competition with oxygen for surface sites but also that different thiols alter the thermodynamics of oxide growth through modification of the EGaIn work function.

Garnet cannibalism provides clues to extensive hydration of lower crustal fragments in a subduction channel (Sesia Zone, Northwestern Alps)

NASA Astrophysics Data System (ADS)

Giuntoli, Francesco; Lanari, Pierre; Engi, Martin

2015-04-01

The extent to which granulites are transformed to eclogites is thought to impose critical limits on the subduction of continental lower crust. Although it is seldom possible to document such densification processes in detail, the transformation is believed to depend on fluid access and deformation. Remarkably complex garnet porphyroblasts are widespread in eclogite facies micaschists in central parts of the Sesia Zone (Western Italian Alps). They occur in polydeformed samples in assemblages involving phengite+quartz+rutile ±paragonite, Na-amphibole, Na-pyroxene, chloritoid. Detailed study of textural and compositional types reveals a rich inventory of growth and partial resorption zones in garnet. These reflect several stages of the polycyclic metamorphic evolution. A most critical observation is that the relict garnet cores indicate growth at 900 °C and 0.9 GPa. This part of the Eclogitic Micaschist Complex thus derived from granulite facies metapelites of Permian age. These dry rocks must have been extensively hydrated during Cretaceous subduction, and garnet records the conditions of these processes. Garnet from micaschist containing rutile, epidote, paragonite and phengite were investigated in detail. Two types of garnet crystals are found in many thin sections: mm-size porphyroclasts and smaller atoll garnets, some 100 µm in diameter. X-ray maps of the porphyroclasts show complex zoning in garnet: a late Paleozoic HT-LP porphyroclastic core is overgrown by several layers of HP-LT Alpine garnet, these show evidence of growth at the expense of earlier garnet generations. Textures indicate 1-2 stages of resorption, with garnet cores that were fractured and then sealed by garnet veins, rimmed by multiple Alpine overgrowth rims with lobate edges. Garnet rim 1 forms peninsula and embayment structures at the expense of the core. Rim 2 surrounds rim 1, both internally and externally, and seems to have grown mainly at the expense of the core. Rim 3 grew mainly at

Gallium nitride photocathodes for imaging photon counters

NASA Astrophysics Data System (ADS)

Siegmund, Oswald H. W.; Hull, Jeffrey S.; Tremsin, Anton S.; McPhate, Jason B.; Dabiran, Amir M.

2010-07-01

Gallium nitride opaque and semitransparent photocathodes provide high ultraviolet quantum efficiencies from 100 nm to a long wavelength cutoff at ~380 nm. P (Mg) doped GaN photocathode layers ~100 nm thick with a barrier layer of AlN (22 nm) on sapphire substrates also have low out of band response, and are highly robust. Opaque GaN photocathodes are relatively easy to optimize, and consistently provide high quantum efficiency (70% at 120 nm) provided the surface cleaning and activation (Cs) processes are well established. We have used two dimensional photon counting imaging microchannel plate detectors, with an active area of 25 mm diameter, to investigate the imaging characteristics of semitransparent GaN photocathodes. These can be produced with high (20%) efficiency, but the thickness and conductivity of the GaN must be carefully optimized. High spatial resolution of ~50 μm with low intrinsic background (~7 events sec-1 cm-2) and good image uniformity have been achieved. Selectively patterned deposited GaN photocathodes have also been used to allow quick diagnostics of optimization parameters. GaN photocathodes of both types show great promise for future detector applications in ultraviolet Astrophysical instruments.

Characterization of Pb-Doped GaN Thin Films Grown by Thermionic Vacuum Arc

NASA Astrophysics Data System (ADS)

Özen, Soner; Pat, Suat; Korkmaz, Şadan

2018-03-01

Undoped and lead (Pb)-doped gallium nitride (GaN) thin films have been deposited by a thermionic vacuum arc (TVA) method. Glass and polyethylene terephthalate were selected as optically transparent substrates. The structural, optical, morphological, and electrical properties of the deposited thin films were investigated. These physical properties were interpreted by comparison with related analysis methods. The crystalline structure of the deposited GaN thin films was hexagonal wurtzite. The optical bandgap energy of the GaN and Pb-doped GaN thin films was found to be 3.45 eV and 3.47 eV, respectively. The surface properties of the deposited thin films were imaged using atomic force microscopy and field-emission scanning electron microscopy, revealing a nanostructured, homogeneous, and granular surface structure. These results confirm that the TVA method is an alternative layer deposition system for Pb-doped GaN thin films.

Holmium: yttrium aluminum garnet laser-assisted endoscopic sinus surgery: laboratory experience.

PubMed

Shapshay, S M; Rebeiz, E E; Bohigian, R K; Hybels, R L; Aretz, H T; Pankratov, M M

1991-02-01

Endoscopic sinus surgery has gained wide acceptance since its introduction into the United States. Complex sinus anatomy and troublesome bleeding have been associated with complications, which vary in severity from synechia to blindness and leakage of cerebrospinal fluid. Endoscopic sinus surgery using a holmium: yttrium aluminum garnet pulsed solid-state laser oscillating at 2.1 microns with fiberoptic delivery was performed in the laboratory, and the results were compared with those of conventional endoscopic sinus surgery. Three beagle dogs, six human cadaver heads, and one calf head were used in the in vivo and in vitro studies to evaluate the bone ablation, tissue coagulation, and hemostatic properties of the holmium: yttrium aluminum garnet laser. Modified endoscopic telescopes for sinus surgery, a newly developed handpiece for fiberoptic delivery, and other surgical instruments were used. The results indicate that the holmium: yttrium aluminum garnet laser and new delivery instrumentation provide good hemostasis and controlled soft-tissue ablation and bone removal. The access to all sinuses in the human cadaver model was very good. The canine in vivo study showed delayed but complete healing on the laser-treated side. Clinical evaluation of the holmium: yttrium aluminum garnet laser is warranted to increase the precision and safety of endoscopic sinus surgery.

Polarization-free integrated gallium-nitride photonics

PubMed Central

Bayram, C.; Liu, R.

2017-01-01

Gallium Nitride (GaN) materials are the backbone of emerging solid state lighting. To date, GaN research has been primarily focused on hexagonal phase devices due to the natural crystallization. This approach limits the output power and efficiency of LEDs, particularly in the green spectrum. However, GaN can also be engineered to be in cubic phase. Cubic GaN has a lower bandgap (~200 meV) than hexagonal GaN that enables green LEDs much easily. Besides, cubic GaN has more isotropic properties (smaller effective masses, higher carrier mobility, higher doping efficiency, and higher optical gain than hexagonal GaN), and cleavage planes. Due to phase instability, however, cubic phase materials and devices have remained mostly unexplored. Here we review a new method of cubic phase GaN generation: Hexagonal-to-cubic phase transition, based on novel nano-patterning. We report a new crystallographic modelling of this hexagonal-to-cubic phase transition and systematically study the effects of nano-patterning on the GaN phase transition via transmission electron microscopy and electron backscatter diffraction experiments. In summary, silicon-integrated cubic phase GaN light emitters offer a unique opportunity for exploration in next generation photonics. PMID:29307953

Gallium Electromagnetic (GEM) Thruster Performance Measurements

NASA Technical Reports Server (NTRS)

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

2009-01-01

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.

The success and complementarity of Sm-Nd and Lu-Hf garnet geochronology

NASA Astrophysics Data System (ADS)

Baxter, E. F.; Scherer, E. E.

2013-12-01

Garnet's potential as a direct chronometer of tectonometamorphic processes and conditions was first realized over 30 years ago. Since then, the Sm-Nd and Lu-Hf systems have emerged as the most effective, with both permitting age precision < ×1 Myr. Both have proven successful not merely in dating garnet growth itself, but rather in constraining the ages, durations, and rates of particular earth processes or conditions that can be directly linked to garnet growth via chemical, thermodynamic, or petrographic, means. Appreciating important differences between Sm-Nd and Lu-Hf in terms of contaminant phases, partitioning, daughter element diffusivity, and isotopic analysis makes these two systems powerfully complementary when used and interpreted in concert. Well established, robust analytical methods mitigate the effects of ubiquitous mineral inclusions (monazite is most significant for Sm-Nd; zircon is most significant for Lu-Hf), improving the precision and accuracy of garnet dates from both systems. Parent-daughter ratios tend to be higher for Lu-Hf leading to the potential for better age precision in general. The Lu-176 decay rate is faster than Sm-147, meaning that Lu-Hf provides better age precision potential for young (Cenozoic) samples. However, Sm-Nd provides better precision potential for older (Precambrian) samples primarily because of the higher precisions on the parent-daughter ratios (i.e., 147Sm/144Nd) that can be achieved by ID-TIMS analysis. For dating microsampled zones or growth rings in single garnet crystals, Sm-Nd has proven most successful owing to more uniform distribution of Sm, and established methods to measure <10 ng quantities of Nd at high precision via TIMS. However, new MC-ICP-MS sample introduction technologies are closing this gap for small samples. For analyses of bulk garnet that grew over a protracted interval, Lu-Hf dates are expected to be older than Sm-Nd dates owing to differences in Lu and Sm zonation (i.e. Lu tends to be

Bragg Reflector-Induced Increased Nonradiative Lifetime in Gallium Arsenide (GaAs)/Aluminum Gallium Arsenide (AlGaAs) Double Heterostructures

DTIC Science & Technology

2015-09-01

ARL-TR-7473 ● SEP 2015 US Army Research Laboratory Bragg Reflector-Induced Increased Nonradiative Lifetime in Gallium Arsenide...return it to the originator. ARL-TR-7473 ● SEP 2015 US Army Research Laboratory Bragg Reflector-Induced Increased Nonradiative ...3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Bragg Reflector-Induced Increased Nonradiative Lifetime in Gallium Arsenide (GaAs)/Aluminum

Melts of garnet lherzolite: experiments, models and comparison to melts of pyroxenite and carbonated lherzolite

USGS Publications Warehouse

Grove, Timothy L.; Holbig, Eva S.; Barr, Jay A.; Till, Christy B.; Krawczynski, Michael J.

2013-01-01

Phase equilibrium experiments on a compositionally modified olivine leucitite from the Tibetan plateau have been carried out from 2.2 to 2.8 GPa and 1,380–1,480 °C. The experiments-produced liquids multiply saturated with spinel and garnet lherzolite phase assemblages (olivine, orthopyroxene, clinopyroxene and spinel ± garnet) under nominally anhydrous conditions. These SiO2-undersaturated liquids and published experimental data are utilized to develop a predictive model for garnet lherzolite melting of compositionally variable mantle under anhydrous conditions over the pressure range of 1.9–6 GPa. The model estimates the major element compositions of garnet-saturated melts for a range of mantle lherzolite compositions and predicts the conditions of the spinel to garnet lherzolite phase transition for natural peridotite compositions at above-solidus temperatures and pressures. We compare our predicted garnet lherzolite melts to those of pyroxenite and carbonated lherzolite and develop criteria for distinguishing among melts of these different source types. We also use the model in conjunction with a published predictive model for plagioclase and spinel lherzolite to characterize the differences in major element composition for melts in the plagioclase, spinel and garnet facies and develop tests to distinguish between melts of these three lherzolite facies based on major elements. The model is applied to understand the source materials and conditions of melting for high-K lavas erupted in the Tibetan plateau, basanite–nephelinite lavas erupted early in the evolution of Kilauea volcano, Hawaii, as well as younger tholeiitic to alkali lavas from Kilauea.

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

NASA Technical Reports Server (NTRS)

Snyder, G. Jeffrey (Inventor); Patel, Jagdishbhai (Inventor); Fleurial, Jean-Pierre (Inventor)

2004-01-01

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 regenerated by the receiving of electrons from the anode enabling the generation of additional electrons from additional .alpha.-particle collisions.

Evidence for polymetamorphic garnet growth in the Çine (southern Menderes) Massif, Western Turkey

NASA Astrophysics Data System (ADS)

Baker, C. B.; Catlos, E. J.; Sorensen, S. S.; Çemen, I.; Hancer, M.

2008-07-01

Garnet-based thermobarometry is often used to develop models for the evolution of the Menderes Massif, a key Aegean metamorphic core complex. Here we present X-ray element maps and high-contrast backscattered electron (BSE) and cathodoluminescence (CL) images from a garnet-bearing rock from the Çine (southern Menderes) Massif. The images document a polymetamorphic history as plagioclase and garnet grains show distinct cores and rims. The sample contains matrix monazite in reaction with allanite. The garnet in the sample is likely not in equilibrium with its matrix minerals. This is evidenced by BSE images that document compositional variability in both core and rim zoning and tracks of bright streaks extending from rim to core. We propose that some garnet that is now present in the Menderes Massif formed due to collision during Cambro-Ordovician and may have recrystallized during subsequent collisional and extensional events. These processes led to non-equilibrium compositions and can result in spurious pressure-temperature (P-T) calculations. To establish the feasibility of the P-T estimates of rocks from the Çine Massif for input into tectonic models for the region, more than one sample from single outcrops should be analyzed. Rocks within the Çine Massif have been suggested to display inverted metamorphism, an increase in T towards structurally higher levels. Based on the garnet documented here, we propose that the inverted metamorphism may be a consequence of apparent P-T rather than a real phenomenon.

Anisotropy of the magnetic susceptibility of gallium

USGS Publications Warehouse

Pankey, T.

1960-01-01

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

Experimental investigation of low temperature garnet-melt partitioning in CMASH, with application to subduction zone processes.

NASA Astrophysics Data System (ADS)

Morizet, Y.; Blundy, J.; McDade, P.

2003-04-01

During subduction, the slab undergoes several processes such as dehydration and partial melting at pressures of 2-3 GPa and temperatures of 600-900^oC. Under these conditions, there is little or no distinction between melt and fluid phases (Bureau &Keppler, 1999, EPSL 165, 187-196). To investigate the behaviour of trace elements under these conditions we have carried out partitioning experiments in the system CMASH at 2.2 GPa, 700-920^oC. CMAS starting compositions were doped with trace elements, and loaded together with quartz and water into a Pt capsule, which was in turn contained within a Ni-lined Ti capsule. Run durations were 3-7 days. A run at 810^oC produced euhedral calcic garnet, zoisite, quartz, hydrous melt and tiny clinopyroxene interpreted as quench crystals. LA-ICPMS and SIMS were used to quantify trace element concentrations of the phases. Garnet-melt D's for the HREE decrease from ˜300 for Lu to less than 0.2 for La. DSc and D_V are less than 5, consistent with the large X-site dimension in the garnet. DLi DSr and DBa are considerably less than the adjacent REE. There is a very slight negative partitioning anomaly for Zr and Hf relative to Nd and Sm; DHf is slightly greater than DZr. D_U < DTh, due largely to the oxidizing conditions of the experiment (NNO). The most striking result is very high D's for Nb and Ta: 18±10 and 5.4±1.9 (LA-ICPMS), 25.8±11.9 and 6.6±1.3 (SIMS) for Nb and Ta respectively. These are considerably larger than any previously measured (at much higher temperatures). The observed partitioning behaviour is consistent with the large temperature dependence for DREE proposed by Van Westrenen et al. (2001, Contrib Min Pet, 142, 219-234), and an even larger temperature dependence for DNb and DTa. These preliminary results suggest that garnet (rather than rutile) may play the key role in controlling the Nb and Ta budget of arc magmas and the Nb/Ta ratio of residual eclogites. For example, modelling of eclogite melting, using a N

Gallium-containing phospho-silicate glasses: synthesis and in vitro bioactivity.

PubMed

Franchini, Mirco; Lusvardi, Gigliola; Malavasi, Gianluca; Menabue, Ledi

2012-08-01

A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO2·24.3Na2O·26.9CaO·2.6P2O5·xGa2O3 (x=1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga2O3 content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga(3+) concentration measured in solution is ~6 ppm determined for 3.5% Ga2O3 content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome. Copyright © 2012 Elsevier B.V. All rights reserved.

Optical and Electrical Characterization of Bulk Grown Indium-Gallium-Arsenide Alloys

DTIC Science & Technology

2010-03-01

OPTICAL AND ELECTRICAL CHARACTERIZATION OF BULK GROWN INDIUM- GALLIUM -ARSENIDE ALLOYS THESIS...Government. AFIT/GAP/ENP/10-M02 OPTICAL AND ELECTRICAL CHARACTERIZATION OF BULK GROWN INDIUM- GALLIUM -ARSENIDE ALLOYS THESIS Presented to...ELECTRICAL CHARACTERIZATION OF BULK GROWN INDIUM- GALLIUM -ARSENIDE ALLOYS Austin C Bergstrom, BS 2 nd Lieutenant, USAF

The compression mechanism of garnets based on in situ observations

NASA Astrophysics Data System (ADS)

Dymshits, Anna; Sharygin, Igor; Litasov, Konstantin; Shatskiy, Anton

2014-05-01

Previously it was showed that the bulk modulus of garnet is strongly affected by the bulk modulus of the dodecahedra, while compressibility of other individual polyhedra displays no correlation with the compressibility of the structure as a whole (Milman et al., 2001). If so, Na-majorite (Na-maj) would have the smallest bulk modulus of all silicate garnets, as a phase with a predicted dodecahedral bulk modulus of approximately 70 GPa (Hazen et al., 1994). In fact Na-maj has the largest bulk modulus among the silicate garnets. This behavior must reflect the all-mineral framework of Na-maj with very small cell volume and silicon in the octahedral position. Thus, we conclude that not only the dodecahedral sites, but also the behavior of the garnet framework and relative sizes of the 8- and 6-coordinated cations, control garnet compression. The octahedral site in Na-maj is quite small (1.79 Å) and contains only silicon in comparison to the pyrope (1.85 Å) or majorite (1.88 Å). The small and highly charged octahedra shares four edges with the dodecahedra and thus restrict the volume of the large and low charged dodecahedra. In spite Na-maj has a large average X-cation radius (RNa = 1.07 Å) its dodecahedral volume is relatively small (V = 21.23 and 21.26 Å3). Pacalo et al. (1992) suggested that XO8 polyhedra act as braces and controls the amount of rotation between tetrahedra and octahedra within the corner-linked chains. In case of pyrope XO8 cite is not filled up and polyhedra within the corner-linked chains can rotate freely to accommodate applied stress. In case of Na-maj the dodecahedral site is filled up and rotational freedom is minimized. The dodecahedral site in knorringite (Knr) contains cation with a small radius (Mg-O = 2.22 and 2.34 Å), so XO8 polyhedra is not filled up and can rotate freely to accommodate applied stress. In case of uvarovite not only octahedral but the dodecahedral site is also large (Ca-O = 2.35 and 2.51 Å), so the rotational

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

PubMed

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

2012-04-23

Hypersensitivity to pressure and temperature is observed in the near-infrared emission lines of the Nd(3+) ion in a Cr(3+),Nd(3+):Gd(3)Sc(2)Ga(3)O(12) crystal, associated to the R(1,2)((4)F(3/2))→Z(5)((4)I(9/2)) and R(1,2)((4)F(3/2))→Z(1)((4)I(9/2)) transitions. The former emissions show large linear pressure coefficients of -11.3 cm(-1)/GPa and -8.8 cm(-1)/GPa, while the latter show high thermal sensitivity in the low temperature range. Thus this garnet crystal can be considered a potential optical pressure and/or temperature sensor in high pressure and temperature experiments up to 12 GPa and below room temperature, used in diamond anvil cells and excited with different UV and visible commercial laser due to the multiple Cr(3+) and Nd(3+) absorption bands. © 2012 Optical Society of America

Analysis of garnets from the archaeological sites in Slovenia

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

Interface Engineering of Garnet Solid Electrolytes

NASA Astrophysics Data System (ADS)

Cheng, Lei

Solid lithium ion conductors represent a promising class of materials for next generation high energy density batteries, with the potential for enabling use of high capacity Li metal anodes and providing opportunities for novel lithium-free cathode materials. However, highly resistive interfaces stymie their practical use. This urgent scientific challenge requires mechanistic understanding of ion transport at interfaces, as well as development of novel processes to achieve low interfacial resistances. The goal of this PhD dissertation was to generate fundamental understandings of garnet-structured Al substituted Li7La3Zr2O 12 (LLZO) electrolyte surfaces and interfaces with lithium metal electrodes. Specifically in this research, the topmost surface microstructure, local chemical environment, and surface chemistry were carefully studied. The ceramic processing of garnet is discussed and ways to control the sintering behavior and microstructures were explored and successfully demonstrated. Factors contributing to high interfacial resistance were systematically studied. The source of the high interfacial impedance has been traced to the presence of Li2CO 3 on pellet surfaces resulting from air exposure after processing. In addition, it was discovered that surface grain boundaries are surprisingly fast ion transport pathways and surface microstructure is critically important to lithium ion transport at interfaces. Complex homo- and heterostructured LLZO solid electrolytes with controllable surface and bulk microstructures were successfully fabricated, which allowed the comparison and separation of the contribution from the surface and the bulk. Engineered pellet surfaces allowed us to achieve the lowest interfacial resistance ever reported for this composition, resulting in significantly improved cycling behavior. Lastly, it was found that LLZO surfaces can be effectively stabilized under air exposure conditions, preventing Li2CO3 formation and maintaining low

Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

PubMed

Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

2016-04-01

Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+.

Synthesis of complex oxides with garnet structure by spray drying of an aqueous salt solution

NASA Astrophysics Data System (ADS)

Makeenko, A. V.; Larionova, T. V.; Klimova-Korsmik, O. G.; Starykh, R. V.; Galkin, V. V.; Tolochko, O. V.

2017-04-01

The use of spray drying to obtain powders of complex oxides with a garnet structure has demonstrated. The processes occurring during heating of the synthesized oxide-salt product, leading to the formation of a material with a garnet structure, have been investigated using DTA, TGA, XPS, and XRD. It has been shown that a single-phase garnet structure of system (Y x Gd(3- x))3Al5O12 can be synthesized over the entire range of compositions.

Single-Crystal X-Ray Diffraction of Pyrope Garnet to 84 GPa

NASA Astrophysics Data System (ADS)

Finkelstein, G. J.; Dera, P. K.; Duffy, T. S.

2012-12-01

Garnets are characteristic minerals of many metamorphic and igneous rocks, and are also important upper-mantle constituents. Mg-rich (pyrope) garnets occur in both peridotite and eclogite compositions in the upper mantle. At high temperatures and pressures above 25 GPa, garnets transform to the perovskite structure. The post-garnet transition kinetics are sluggish, and in cold subducting slabs garnets could persist metastably at temperatures as high as 1700 K on geological timescales. These phases could add positive buoyancy to a subducting slab, inhibiting subduction. There has been minimal previous work on the 300 K compression behavior of aluminosilicate garnets at pressures higher than 10 GPa. In this work, we have collected single-crystal X-ray diffraction data on near end-member natural pyrope (Dora Maira pyrope) to 84 GPa. By extending the compression of pyrope to much higher pressures, we can better constrain the equation of state while also characterizing the structural response to such extreme pressures for the first time. Crystals were polished to ~5-10 μm in thickness, and loaded in a diamond anvil cell with gold foil and ruby balls as pressure calibrants. Helium was used as a pressure-transmitting medium. High-pressure single-crystal X-ray diffraction experiments were performed at the GSECARS 13-ID-D beamline of the Advanced Photon Source and the 12.2.2 beamline of the Advanced Light Source. Structure refinements were carried out successfully to the highest pressure using Shelx-97, extending the range over which the compression behavior of this material has been characterized by a factor of nearly three. Pyrope exhibits smooth compression behavior and no phase transitions over the investigated pressure range. A preliminary 3rd order Birch-Murnaghan equation of state was successfully fit to data up to 52 GPa. If the bulk modulus is fixed to 170 GPa, a value consistent with previous Brillouin and Ultrasonic studies, our data yields a pressure derivative

Angiotensin-I-converting enzyme and gallium scan in noninvasive evaluation of sarcoidosis

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

Nosal, A.; Schleissner, L.A.; Mishkin, F.S.

1979-03-01

Angiotensin-converting enzyme assays and gallium-scan results were obtained from 27 patients with biopsy-proven, clinically active sarcoidosis. Twenty-three of these patients had elevated converting enzyme levels, and 22 had positive gallium-scan results. Three of four patients with normal or borderline-elevated levels of angiotensin-converting enzyme also had positive gallium-scan results. Of 156 nonsarcoid patients (pulmonary and other diseases), 27 were found to have elevated serum converting enzyme levels, and 25 of these had negative gallium-scan results. These results indicate that the combination of an assay of angiotensin-converting enzyme and gallium scan increases diagnostic specificity from 83% to 99% without sacrificing sensitivity. Itmore » was concluded that the concurrent use of angiotensin-converting enzyme assay and gallium scan is of value in the diagnosis of sarcoidosis.« less

Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

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

Fu, Kun; Gong, Yunhui; Liu, Boyang

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li 7La 3Zr 2O 12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10 -3 to 10 -4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnetmore » solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm 2 for the surface-engineered garnet/Li. Li 7La 2.75Ca 0.25Zr 1.75Nb 0.25O 12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries.« less

Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

DOE PAGES

Fu, Kun; Gong, Yunhui; Liu, Boyang; ...

2017-04-07

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li 7La 3Zr 2O 12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10 -3 to 10 -4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnetmore » solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm 2 for the surface-engineered garnet/Li. Li 7La 2.75Ca 0.25Zr 1.75Nb 0.25O 12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries.« less

Preliminary Spectroscopic Measurements for a Gallium Electromagnetic (GEM) Thruster

NASA Technical Reports Server (NTRS)

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

2007-01-01

As a propellant option for electromagnetic thrusters, liquid ,gallium appears to have several advantages relative to other propellants. The merits of using gallium in an electromagnetic thruster (EMT) are discussed and estimates of discharge current levels and mass flow rates yielding efficient operation are given. The gallium atomic weight of 70 predicts high efficiency in the 1500-2000 s specific impulse range, making it ideal for higher-thrust, near-Earth missions. A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma and estimate electron temperature. The spectra show that neutral, singly, and doubly ionized gallium species are present in a 20 J, 1.8 kA (peak) are discharge. With graphite present on the insulator to facilitate breakdown, singly and doubly ionized carbon atoms are also present, and emission is observed from molecular carbon (CZ) radicals. A determination of the electron temperature was attempted using relative emission line data, and while the spatially and temporally averaged, spectra don't fit well to single temperatures, the data and presence of doubly ionized gallium are consistent with distributions in the 1-3 eV range.

Garnet clinopyroxenite layers from the mantle sequences of the Northern Apennine ophiolites (Italy): Evidence for recycling of crustal material

NASA Astrophysics Data System (ADS)

Montanini, A.; Tribuzio, R.; Thirlwall, M.

2012-10-01

This study aims to define the origin of garnet clinopyroxenite layers from the mantle sequences of the External Ligurian ophiolites. These mantle sequences retain a subcontinental origin and were exposed at a Jurassic ocean-continent transition. The garnet clinopyroxenites are mafic rocks with Mg# values of 66-71. Their chondrite-normalised REE patterns are characterised by severe LREE depletion (CeN/SmN=0.1-0.2) and nearly flat (Type-A pyroxenites) to moderately enriched HREE (Type-B pyroxenites). In addition, Type-A pyroxenites display a small positive Eu anomaly. The whole-rock REE variations are paralleled by the garnet REE compositions. We attribute the major and trace element characteristics of the garnet clinopyroxenites to recycling of gabbroic protoliths that underwent partial melting under eclogite facies conditions. The garnet clinopyroxenites may represent variably evolved garnet+clinopyroxene cumulates formed by eclogite-derived melts. In an alternative hypothesis, Type-A and -B pyroxenites are residual rocks after eclogite melting and cumulates derived from the eclogite melts, respectively. The high pressure fractionation event that gave rise to the garnet clinopyroxenites is considered of Triassic age on the basis of Sm-Nd and Lu-Hf isotope correlations. The Nd-Hf isotopic compositions of the garnet clinopyroxenites in the Triassic (ɛNd=+4.7 to +7.6, ɛHf=+4.4 to +12.8) lie below the mantle array, in agreement with recycled ancient MOR-type material. The oxygen isotopic composition of garnet and clinopyroxene from the garnet clinopyroxenites (δ18O=+4.9‰ to +5.2‰) may be reconciled with subduction-related recycling of the lowermost oceanic crust, or delamination and foundering of underplated gabbros from the continental lithosphere. The potential involvement of the garnet clinopyroxenites in the melting processes that gave rise to the MOR-type oceanic crust in the Jurassic would account for the moderate Nd isotope variability and the garnet

Influence of doping on thermal diffusivity of single crystals used in photonics: measurements based on thermal wave methods.

PubMed

Bodzenta, Jerzy; Kaźmierczak-Bałata, Anna; Wokulska, Krystyna B; Kucytowski, Jacek; Łukasiewicz, Tadeusz; Hofman, Władysław

2009-03-01

Three crystals used in solid-state lasers, namely, yttrium aluminum garnet (YAG), yttrium orthovanadate (YVO(4)), and gadolinium calcium oxoborate (GdCOB), were investigated to determine the influence of dopants on their thermal diffusivity. The thermal diffusivity was measured by thermal wave method with a signal detection based on mirage effect. The YAG crystals were doped with Yb or V, the YVO(4) with Nd or Ca and Tm, and the GdCOB crystals contained Nd or Yb. In all cases, the doping caused a decrease in thermal diffusivity. The analysis of complementary measurements of ultrasound velocity changes caused by dopants leads to the conclusion that impurities create phonon scattering centers. This additional scattering reduces the phonon mean free path and accordingly results in the decrease of the thermal diffusivity of the crystal. The influence of doping on lattice parameters was investigated, additionally.

A generalized garnet-forming reaction for metaigneous rocks in the Adirondacks

USGS Publications Warehouse

McLelland, J.M.; Whitney, P.R.

1980-01-01

A generalized reaction is presented to account for garnet formation in a variety of Adirondack metaigneous rocks. This reaction, which is the sum of five partial reactions written in aluminum-fixed frames of reference, is given by: 4(y+1+w)Anorthite+4 k(y+1+2 w)Olivine +4(1-k)(y+1+2 w)Fe-oxide+(8(y+1) -4 k(y+1+2 w))Orthopyroxene = 2(y+1)Garnet +2(y+1+2 w)Clinopyroxene+4 wSpinel where y is a function of plagioclase composition, k refers to the relative amounts of olivine and Fe-oxide participating in the reaction, and w is a measure of silicon mobility. When mass balanced for Mg and Fe, this reaction is found to be consistent with analyzed mineral compositions in a wide range of Adirondack metaigneous rocks. The reaction applies equally well whether the garnets were formed directly from the rectants given above or went through an intermadiate stage involving the formation of spinel, orthopyroxene, and clinopyroxene. The actual reactions which have produced garnet in both undersaturated and quartz-bearing rocks are special cases of the above general reaction. The most important special cases appear to be those in which the reactants include either olivine alone (k=1) or Fe-oxide alone (k=0). Silicon is relatively immobile (w =2) in olivine bearing, magnesium-rich rocks (k???1), and this correlates with the increased intensity in spinel clouding of plagioclase in these rocks. Silicon mobility apparently increases in the more iron-rich rocks, which also tend to contain clear or lightly clouded plagioclase. In all the rocks studied the most common composition of metamorphic plagioclase is close to An33 (i.e., y=1). Plagioclase of lower anorthite content may be too sodic to participate in garnet formation at the P-T conditions involved. ?? 1980 Springer-Verlag.

Magneto-Optical Experiments on Rare Earth Garnet Films.

ERIC Educational Resources Information Center

Tanner, B. K.

1980-01-01

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)

Strain-dependent evolution of garnets in a high pressure ductile shear zone using Synchroton x-ray microtomography

NASA Astrophysics Data System (ADS)

Macente, Alice; Fusseis, Florian; Menegon, Luca; John, Timm

2016-04-01

Synkinematic reaction microfabrics carry important information on the kinetics, timing and rheology of tectonometamorphic processes. Despite being routinely interpreted in metamorphic and structural studies, reaction and deformation microfabrics are usually described in two dimensions. We applied Synchrotron-based x-ray microtomography to document the evolution of a pristine olivine gabbro into a deformed omphacite-garnet eclogite in 3D. In the investigated samples, which cover a strain gradient into a shear zone from the Western Gneiss Region (Norway) previously described by John et al., (2009), we focused on the spatial transformation of garnet coronas into elongated clusters of garnets. Our microtomographic data allowed us to quantify changes to the garnet volume, their shapes and their spatial arrangement. We combined microtomographic observations with light microscope- and backscatter electron images as well as electron microprobe- (EMPA) and electron backscatter diffraction (EBSD) analyses to correlate mineral composition and orientation data with the x-ray absorption signal of the same mineral grains. This allowed us to extrapolate our interpretation of the metamorphic microfabric evolution to the third dimension, effectively yielding a 4-dimensional dataset. We found that: - The x-ray absorption contrast between individual mineral phases in our microtomographic data is sufficient to allow the same petrographic observations than in light- and electron microscopy, but extended to 3D. - Amongst the major constituents of the synkinematic reactions, garnet is the only phase that can be segmented confidently from the microtomographic data. - With increasing deformation, the garnet volume increases from about 9% to 25%. - Garnet coronas in the gabbros never completely encapsulate olivine grains. This may indicate that the reaction progressed preferentially in some directions, but also leaves pathways for element transport to and from the olivines that are

Recovery of Gallium from Secondary V-Recycling Slag by Alkali Fusion

NASA Astrophysics Data System (ADS)

Gao, Lei; Shi, Zhe; Zhang, Gui-fang

Secondary V-recycling slag, an industrial waste containing high gallium is being dumped continuously, which causes the loss of gallium. Thus, the alkali fusion process was employed to recover gallium from this slag. The effects factors on extraction of gallium such as roasting temperature, roasting time, alkali fusion agent concentration and CaO concentration were investigated in the paper. The experimental results indicated that excessive roasting temperature and roasting time is unfavorable to the recovery rate of gallium. The appropriate roasting temperature and duration are 1000°C and 2 hours, respectively; The appropriate proportioning of Na2CO3: NaOH is 2:1 when the concentration of alkali fusion agent weighs 0.4 times the mass of the slag; In order to remove SiO2 from the leaching liquor, CaO should be used as an additive in the roasting process. The appropriate concentration of CaO should weigh 0.2 times the mass of the slag. Employing these optimal alkali fusion conditions in the roasting process, gallium recovery is above 90%.

The influence of Mg doping on the formation of Ga vacancies and negative ions in GaN bulk crystals

NASA Astrophysics Data System (ADS)

Saarinen, K.; Nissilä, J.; Hautojärvi, P.; Likonen, J.; Suski, T.; Grzegory, I.; Lucznik, B.; Porowski, S.

1999-10-01

Gallium vacancies and negative ions are observed in GaN bulk crystals by applying positron lifetime spectroscopy. The concentration of Ga vacancies decreases with increasing Mg doping, as expected from the behavior of the VGa formation energy as a function of the Fermi level. The concentration of negative ions correlates with that of Mg impurities determined by secondary ion mass spectrometry. We thus attribute the negative ions to MgGa-. The negative charge of Mg suggests that Mg doping converts n-type GaN to semi-insulating mainly due to the electrical compensation of ON+ donors by MgGa- acceptors.

Crystallography, Spectroscopic Analysis, and Lasing Properties of Nd(3+) :Y3Sc2Al3O12

DTIC Science & Technology

1989-12-01

aluminum garnet (GSAG), are formed from more stable constitu- ent oxides than gallium-containing materials, 2. Experimental Results and such as gadolinium ...the which an assessment can be made regarding aluminum -based systems, such as YAG, YSAG, Nd:YSAG as a laser material. or gadolinium scandium...Structure oxidation state variation or oxygen vacancies, and this problem is greatly reduced in alumi- Yttrium scandium aluminum garnet be- nate systems

Coexisting calderite and spessartine garnets in eclogite-facies metacherts of the Western Alps

NASA Astrophysics Data System (ADS)

Cenki-Tok, B.; Chopin, C.

2006-09-01

The coexistence of a colourless and a yellow garnet was observed in eclogite-facies manganese concentrations of the Mesozoic ophiolitic Zermatt-Saas Unit, at the Praborna mine near Saint-Marcel, Val d’Aoste, Italy, and in the upper Maurienne Valley, France. They occur both in oxidised metachert with hematite and braunite (+ minor Mn-pyroxenoid and tirodite, rare tiragalloite; with ardennite or piemontite in distinct layers), and in more reduced, carbonate-rich boudins included in it. The co-occurrence takes a variety of textural aspects, from coexisting euhedral garnets (10-100 µm in size for the calderite to mm-size for spessartine) to sharp overgrowths of yellow calderitic garnet on colourless spessartine, to yellow cauliflower-like masses (a few hundreds of µm in size) overgrowing colourless spessartine and showing evidence of oscillatory zoning, resorption stages and resumed growth. Sector zoning and anisotropy are common, although not consistent features. Compositions can be expressed to 95% in the quadrilateral system (Ca, Mn2+)3 (Al, Fe3+)2 Si3O12, with less than 1.0 wt% MgO and 0.8 wt% TiO2 in colourless spessartine, and less than 0.2 wt% MgO and 1.6 wt% TiO2 in yellow garnet. Calcium partitions into the ferric garnet. Coexisting pairs define two compositional gaps, bounded by values of the Fe3+/(Al + Fe3+) ratio of 10 and 15% for the first one, of 40 and 65% for the other. The optically obvious discontinuity (colour change and Becke’s line) corresponds to the narrower gap, between colourless spessartine and yellow spessartine, whereas the broad compositional gap occurs within yellow garnet, between yellow spessartine and yellow calderite, and is only revealed by back-scattered electron images. Only the latter can be a candidate for a miscibility gap, if any.

Boron, bismuth co-doping of gallium arsenide and other compounds for photonic and heterojunction bipolar transistor devices

DOEpatents

Mascarenhas, Angelo

2015-07-07

Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is sued to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

Multielemental analyses of isomorphous Indian garnet gemstones by XRD and external pixe techniques.

PubMed

Venkateswarulu, P; Srinivasa Rao, K; Kasipathi, C; Ramakrishna, Y

2012-12-01

Garnet gemstones were collected from parts of Eastern Ghats geological formations of Andhra Pradesh, India and their gemological studies were carried out. Their study of chemistry is not possible as they represent mixtures of isomorphism nature, and none of the individual specimens indicate independent chemistry. Hence, non-destructive instrumental methodology of external PIXE technique was employed to understand their chemistry and identity. A 3 MeV proton beam was employed to excite the samples. In the present study geochemical characteristics of garnet gemstones were studied by proton induced X-ray emission. Almandine variety of garnet is found to be abundant in the present study by means of their chemical contents. The crystal structure and the lattice parameters were estimated using X-Ray Diffraction studies. The trace and minor elements are estimated using PIXE technique and major compositional elements are confirmed by XRD studies. The technique is found very useful in characterizing the garnet gemstones. The present work, thus establishes usefulness and versatility of the PIXE technique with external beam for research in Geo-scientific methodology. Copyright © 2012 Elsevier Ltd. All rights reserved.

Growth and luminescent properties of Yb:YAG and Ca co-doped Yb:YAG ultrafast scintillation crystals

NASA Astrophysics Data System (ADS)

Zhu, Maodong; Qi, Hongji; Pan, Mingyan; Hou, Qing; Jiang, Benxue; Jin, Yaxue; Han, Hetong; Song, Zhaohui; Zhang, Hui

2018-05-01

In this work, Yb-doped Y3Al5O12 [yttrium aluminum garnet (YAG)] crystals and Ca co-doped Yb:YAG crystals were grown by the Czochralski (CZ) method. The chemical formulas of the two crystals are (Yb0.1Y0.9)3Al5O12 and (Ca0.001Yb0.1Y0.899)3Al5O12, respectively. The structural, optical and luminescent properties of the Yb:YAG and Ca, Yb:YAG crystals were investigated by X-ray rocking curve, X-ray diffraction, Raman spectra, UV-Visble-NIR absorption spectra and X-ray fluorescence. X-ray fluorescence spectrum with two emission peaks at 330 nm and 490 nm were observed in the two kinds of crystals, which would increase slightly after the annealing. Comparing to the Yb:YAG crystal, Ca co-doped Yb:YAG crystal behaved the better luminescent intensity without changing the crystal structure and vibrational modes. This indicates that by doping Ca2+ in Yb:YAG crystal may be an appropriate way to enhance the luminescent property of the scintillation crystal.

Optical absorption and emission bands of Tm 3+ ions in calcium niobium gallium garnet crystal

NASA Astrophysics Data System (ADS)

Tsuboi, Taiju; Tanigawa, Masayuki; Shimamura, Kiyoshi

2000-12-01

Absorption spectra of Tm 3+ ions in Ca 3Nb 1.6875Ga 3.1875O 12 (CNGG) crystal have been investigated at various temperatures between 15 and 296 K. Luminescence spectra in a spectral region of 400-1750 nm are investigated under excitation into various excited states of Tm 3+ and the conduction band of CNGG at room temperature. The absorption and emission bands of Tm 3+ in CNGG are observed to be broader than those observed in other Tm 3+-doped crystals such as LiNbO 3. This is due to the disordered structure of CNGG. From the temperature dependence of absorption spectra, five Stark levels are derived for the 3H 6 ground state. The highest Stark level is found to be 351 cm -1 above the ground level. It is suggested that the low efficiency of the 2.02 μm lasing at room temperature is due to the narrow splitting of the Stark levels.

Gallium Oxide Nanostructures for High Temperature Sensors

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

Chintalapalle, Ramana V.

Gallium oxide (Ga 2O 3) thin films were produced by sputter deposition by varying the substrate temperature (T s) in a wide range (T s=25-800 °C). The structural characteristics and electronic properties of Ga 2O 3 films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga 2O 3 films. XRD and SEM analyses indicate that the Ga 2O 3 films grown at lower temperatures were amorphous while those grown at T s≥500more » oC were nanocrystalline. RBS measurements indicate the well-maintained stoichiometry of Ga 2O 3 films at T s=300-800 °C. The electronic structure determination indicated that the nanocrystalline Ga 2O 3films exhibit a band gap of ~5 eV. Tungsten (W) incorporated Ga 2O 3 films were produced by co-sputter deposition. W-concentration was varied by the applied sputtering-power. No secondary phase formation was observed in W-incorporated Ga 2O 3 films. W-induced effects were significant on the structure and electronic properties of Ga2O3 films. The band gap of Ga 2O 3 films without W-incorporation was ~5 eV. Oxygen sensor characteristics evaluated using optical and electrical methods indicate a faster response in W-doped Ga 2O 3 films compared to intrinsic Ga 2O 3 films. The results demonstrate the applicability of both intrinsic and W-doped Ga-oxide films for oxygen sensor application at temperatures ≥700 °C.« less

Gallium alloy films investigated for use as boundary lubricants

NASA Technical Reports Server (NTRS)

1966-01-01

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

Preservation of Partial Melt Textures in Inclusions in Garnet Megacrysts of Pelitic Paragneiss, UHP Terrane, North-East Greenland Eclogite Province

NASA Astrophysics Data System (ADS)

Lang, H. M.; Gilotti, J. A.

2005-12-01

Although paragneiss is not common in the North-East Greenland Eclogite Province (NEGEP), of the few paragneiss samples collected in the UHP zone, some contain inclusion-rich garnet megacrysts (to 2 cm) in an anatectic matrix. In the matrix, quartz ribbons are segregated from anatectic melt layers and lenses that contain plagioclase, antiperthitic alkali-feldspar, white mica, biotite, small garnets, rutile and minor kyanite. In addition to one-phase and two-phase inclusions of quartz, polycrystalline quartz (no definitive coesite-replacement textures), and phengitic white mica, the garnet megacrysts contain some relatively large polyphase inclusions with all or most of the following phases: kyanite, rutile, phengitic white mica, biotite, quartz, Na-rich plagioclase, K-feldspar and zircon. Textures in these complex, polyphase inclusions suggest that their constituent minerals crystallized from a melt. Crystals are randomly oriented with early crystallizing minerals (kyanite, rutile, micas) forming euhedral grains and later crystallizing minerals (quartz and feldspars) filling the interstitial spaces. The textures and mineral assemblages are consistent with dehydration melting of phengitic white mica + quartz (enclosed in garnet) during decompression of the rocks from UHP metamorphic conditions. Although anatectic minerals in the matrix may have experienced extensive retrograde re-equilibration subsequent to crystallizing from a melt, the minerals trapped in the crystallized melt inclusions in garnet are likely to preserve their original textures and compositions. Microtextures in the melt inclusions and surrounding garnet suggest that partial melting was accompanied by volume expansion and that some melt penetrated garnets. Some radial fractures extend from inclusion margins into surrounding garnet. Individual fractures may have formed by volume expansion on melting or expansion accompanying the coesite-quartz transformation. Small and large polycrystalline quartz

Precipitation of Oriented Rutile and Ilmenite Needles in Garnet, Northeastern Connecticut, USA: Evidence for Extreme Metamorphic Conditions?

NASA Astrophysics Data System (ADS)

Ague, J. J.; Eckert, J. O.

2011-12-01

We report the discovery of oriented needles of rutile and, less commonly, ilmenite in the cores of garnets from northeastern CT, USA. The rocks preserve granulite facies mineral assemblages, form part of the Merrimack Synclinorium, and underwent metamorphism and deformation during the Acadian orogeny. The needles appear identical to those reported from a number of extreme P-T environments worldwide, including UHP metamorphic rocks, high-P granulites, and garnet peridotites. The needles are predominantly oriented along <111> directions in garnet. The long axes of the rutile needles commonly do not go extinct parallel to the cross hairs under cross-polarized light (e.g., Griffin et al., 1971). This anomalous extinction indicates that the needles do not preserve a specific crystallographic relationship with their garnet hosts (e.g., Hwang et al., 2007). The needles range from a few hundred nm to a few um in diameter, and can be mm-scale in length. Micrometer-scale plates of rutile, srilankite and crichtonite have also been observed in some garnets together with the Fe-Ti oxide needles. Several origins for the needles have been proposed in the literature; we investigate the hypothesis that they precipitated in situ from originally Ti-rich garnet. Chemical profiles across garnets indicate that some retain Ti zoning, with elevated-Ti concentrations in the cores dropping to low values in the rims. For these zoned garnets, high-resolution, 2-D chemical mapping using the JEOL JXA-8530F field emission gun electron microprobe at Yale University reveals that the needles are surrounded by well-defined Ti-depletion halos. Chemical profiles also document strong depletions of Cr (which is present in both rutile and ilmenite) directly adjacent to needles. The observed Ti-depletions demonstrate that the needles precipitated from Ti-bearing garnet, probably during cooling and/or decompression associated with exhumation. The rutile precipitates must be largely incoherent with respect

Tunable Solid-State Quantum Memory Using Rare-Earth-Ion-Doped Crystal, Nd(3+):GaN

DTIC Science & Technology

2017-04-01

by plasma-assisted molecular beam epitaxy in a modular Gen II reactor using liquid gallium, solid Nd, and a nitrogen plasma. The photoluminescence (PL...provide a tunable memory. To vary the applied field, we designed and grew a series of Nd-doped GaN p-i-n structures, strain- balanced superlattice...27 Fig. 23 Electric field vs. GaN well/ AlxGa(1-x)N barrier thickness for strain- balanced superlattice (SBSL) structures with

Fractographic and three body abrasion behaviour of Al-Garnet-C hybrid chill cast composites

NASA Astrophysics Data System (ADS)

Bandekar, Nityanand; Prasad, M. G. Anantha

2017-08-01

Fractographic and tribological behaviour of hybrid composite of aluminum alloy LM13 matrix with garnet and carbon was investigated. Conventional stir casting technique was used to fabricate the composites with chill cast technique. Various chill materials like Copper, Steel, Iron and Silicon carbide were used to improve the directional solidification. The garnet being added ranges from 3 to 12 wt-% in steps of 3wt-% and constant 3wt-% of carbon. The experiment evaluates the mechanical, fractographic and three body abrasion behaviour of the hybrid composites for various parameters of load, garnet and chills. Microstructural characterization of the composite samples revealed a uniform distribution of reinforcements with minimum clustering. SEM was used for examine worn surfaces. The addition of garnet and carbon reinforcement decreases the wear rate of hybrid composites. Fracture behaviour showed the changes from ductile mode to brittle mode of failure. Further, directional chilling with copper chill improves the wear resistance of the composites.

In Situ Neutron Depth Profiling of Lithium Metal-Garnet Interfaces for Solid State Batteries.

PubMed

Wang, Chengwei; Gong, Yunhui; Dai, Jiaqi; Zhang, Lei; Xie, Hua; Pastel, Glenn; Liu, Boyang; Wachsman, Eric; Wang, Howard; Hu, Liangbing

2017-10-11

The garnet-based solid state electrolyte (SSE) is considered a promising candidate to realize all solid state lithium (Li) metal batteries. However, critical issues require additional investigation before practical applications become possible, among which high interfacial impedance and low interfacial stability remain the most challenging. In this work, neutron depth profiling (NDP), a nondestructive and uniquely Li-sensitive technique, has been used to reveal the interfacial behavior of garnet SSE in contact with metallic Li through in situ monitoring of Li plating-stripping processes. The NDP measurement demonstrates predictive capabilities for diagnosing short-circuits in solid state batteries. Two types of cells, symmetric Li/garnet/Li (LGL) cells and asymmetric Li/garnet/carbon-nanotubes (LGC), are fabricated to emulate the behavior of Li metal and Li-free Li metal anodes, respectively. The data imply the limitation of Li-free Li metal anode in forming reliable interfacial contacts, and strategies of excessive Li and better interfacial engineering need to be investigated.

On the nature and origin of garnet in highly-refractory Archean lithosphere: implications for continent stabilisation

NASA Astrophysics Data System (ADS)

Gibson, Sally

2014-05-01

The nature and timescales of garnet formation in the Earth's subcontinental lithospheric mantle (SCLM) are important to our understanding of how this rigid outer shell has evolved and stabilised since the Archean. Nevertheless, the widespread occurrence of pyrope garnet in the sub-cratonic mantle remains one of the 'holy grails' of mantle petrology. The paradox is that garnet often occurs in mantle lithologies (dunites and harzburgites) which represent residues of major melting events (up to 40 %) whereas experimental studies on fertile peridotite suggest this phase should be exhausted by <20 % melting. Furthermore, garnets commonly found in mantle peridotite suites have diverse compositions that are typically in equilibrium with high-pressure, small-fraction, mantle melts suggesting they formed as a result of enrichment of the lithospheric mantle following cratonisation. This refertilisation -- which typically involves addition of Fe, incompatible trace elements and volatiles -- affects the lower 30 km of the lithosphere and potentially leads to negative buoyancy and destabilisation. Pyrope garnets found in mantle xenoliths from the eastern margin of the Tanzanian Craton (Lashaine) have diverse compositions and provide major constraints on how the underlying deep (120 to 160 km) mantle stabilised and evolved during the last 3 billion years. The garnets display systematic trends from ultra-depleted to enriched compositions that have not been recognised in peridotite suites from elsewhere (Gibson et al., 2013). Certain harzburgite members of the xenolith suite contain the first reported occurrence of pyrope garnets with rare-earth element (REE) patterns similar to hypothetical garnets proposed by Stachel et al. (2004) to have formed in the Earth's SCLM during the Archean, prior to metasomatism. These rare ultra-depleted low-Cr garnets occur in low temperature (~1050 oC) xenoliths derived from depths of ~120 km and coexist in chemical and textural equilibrium with

Diffusion-controlled garnet growth in siliceous dolomites of the Adamello contact aureole, N-Italy

NASA Astrophysics Data System (ADS)

Muller, T.; Fiebich, E.; Foster, C. T.

2012-12-01

Texture forming processes are controlled by many factors, such as material transport through polycrystalline materials, surface kinetics, fluid flow, and many others. In metamorphic rocks, texture forming processes typically involve local reactions linked to net mass transfer which allows constraining the actual reaction path in more detail. In this study, we present geochemical data combined with textural modeling to constrain the conditions and reaction mechanism during contact metamorphic garnet growth in siliceous dolomites in the southern Adamello Massif, Italy. The metamorphic garnet porphyroblasts are poikiloblastic and idiomorphic in shape with a typical grain size ranging between 0.6-1 cm in diameter sitting in a matrix of calcite+diopside+anorthite+wollastonite. Inclusions in the grossular-rich garnets are almost uniquely diopside. On the hand specimen, garnets are surrounded by visible rims of about 0.6 mm indicating a diffusion-limited reaction mechanism to be responsible for the garnet formation. In the course of this study samples have been characterized by polarization microscopy, element x-ray maps using EMPA, cathodulominescence images and stable isotope analyses of carbon and oxygen of matrix carbonates. In addition, pseudosections have been calculated using the software package PerpleX (Connolly, 2005) based on the bulk chemistry of collected samples. Results indicate that the visible margin consists of a small rim (< 1 mm) purely consisting of recrystallized calcite adjacent to the garnet edge. The major part of the observed halo, however, is characterized by the absence of anorthite and wollastonite. The observed texture of garnet porphyroblasts growing and simultaneously forming an anorthite and wollastonite free margin can successfully be reproduced using the SEG program (Foster, 1993), which assumes diffusive mass transport. Therefore the model constrains the diffusive fluxes of Ca, Mg, Al and Si by mass balance and the local Gibbs

Microfluidic platforms for gallium-based liquid metal alloy

NASA Astrophysics Data System (ADS)

Kim, Daeyoung

As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non

Harmonic technology versus neodymium-doped yttrium aluminium garnet laser and electrocautery for lung metastasectomy: an experimental study.

PubMed

Fiorelli, Alfonso; Accardo, Marina; Carelli, Emanuele; Del Prete, Assunta; Messina, Gaetana; Reginelli, Alfonso; Berritto, Daniela; Papale, Ferdinando; Armenia, Emilia; Chiodini, Paolo; Grassi, Roberto; Santini, Mario

2016-07-01

We compared the efficacy of non-anatomical lung resections with that of three other techniques: monopolar electrocautery; neodymium-doped yttrium aluminium garnet laser and harmonic technology. We hypothesized that the thermal damage with harmonic technology could be reduced because of the lower temperatures generated by harmonic technology compared with that of other devices. Initial studies were performed in 13 isolated pig lungs for each group. A 1.5-cm capsule was inserted within the lung to mimic a tumour and a total of 25 non-anatomical resections were performed with each device. The damage of the resected lung surface and of the tumour border were evaluated according to the colour (ranging from 0-pink colour to 4-black colour), histological (ranging from Score 0-no changes to Score 3-presence of necrotic tissue) and radiological (ranging from Score 0-isointense T2 signal at magnetic resonance imaging to Score 3-hyperintense T2 signal) criteria. A total of seven non-anatomical resections with harmonic technology were also performed in two live pigs to assess if ex vivo results could be reproducible in live pigs with particular attention to haemostatic and air-tightness properties. In the ex vivo lung, there was a statistical significant difference between depth of thermal damage (P < 0.0001) in electrocautery (1.3 [1.2-1.4]), laser (0.9 [0.6-0.9]) and harmonic (0.4 [0.3-0.5]) groups. Electrocautery had a higher depth of thermal damage compared with that of the laser (P = 0.01) and harmonic groups (P = 0.0005). The harmonic group had a less depth of thermal damage than that of the laser group (P = 0.01). Also, histological damages of tumour borders (P < 0.001) and resected lung surface (P < 0.001), radiological damage of tumour borders (P < 0.001) and resected lung surface (P < 0.001) and colour changes (P < 0.001) were statistically different between three study groups. Resections of in vivo pig lungs showed no bleeding; 2 of 7 cases of low air leaks were

Novel solution-phase structures of gallium-containing pyrogallol[4]arene scaffolds**

PubMed Central

Kumari, Harshita; Kline, Steven R.; Wycoff, Wei G.; Paul, Rick L.; Mossine, Andrew V.; Deakyne, Carol A.; Atwood, Jerry L.

2012-01-01

The variations in architecture of gallium-seamed (PgC4Ga) and gallium-zinc-seamed (PgC4GaZn) C-butylpyrogallol[4]arene nanoassemblies in solution (SANS/NMR) versus the solid state (XRD) have been investigated. Rearrangement from the solid-state spheroidal to the solution-phase toroidal shape differentiates the gallium-containing pyrogallol[4]arene nanoassemblies from all other PgCnM nanocapsules studied thus far. Different structural arrangements of the metals and arenes of PgC4Ga versus PgC4GaZn have been deduced from the different toroidal dimensions, C–H proton environments and guest encapsulation of the two toroids. PGAA of mixed-metal hexamers reveals a decrease in gallium-to-metal ratio as the second metal varies from cobalt to zinc. Overall, the combined study demonstrates the versatility of gallium in directing the self-assembly of pyrogallol[4]arenes into novel nanoarchitectures. PMID:22511521

Window structure for passivating solar cells based on gallium arsenide

NASA Technical Reports Server (NTRS)

Barnett, Allen M. (Inventor)

1985-01-01

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.

Gallium Potentiates the Antibacterial Effect of Gentamicin against Francisella tularensis

PubMed Central

Lindgren, Helena

2015-01-01

The reasons why aminoglycosides are bactericidal have not been not fully elucidated, and evidence indicates that the cidal effects are at least partly dependent on iron. We demonstrate that availability of iron markedly affects the susceptibility of the facultative intracellular bacterium Francisella tularensis strain SCHU S4 to the aminoglycoside gentamicin. Specifically, the intracellular depots of iron were inversely correlated to gentamicin susceptibility, whereas the extracellular iron concentrations were directly correlated to the susceptibility. Further proof of the intimate link between iron availability and antibiotic susceptibility were the findings that a ΔfslA mutant, which is defective for siderophore-dependent uptake of ferric iron, showed enhanced gentamicin susceptibility and that a ΔfeoB mutant, which is defective for uptake of ferrous iron, displayed complete growth arrest in the presence of gentamicin. Based on the aforementioned findings, it was hypothesized that gallium could potentiate the effect of gentamicin, since gallium is sequestered by iron uptake systems. The ferrozine assay demonstrated that the presence of gallium inhibited >70% of the iron uptake. Addition of gentamicin and/or gallium to infected bone marrow-derived macrophages showed that both 100 μM gallium and 10 μg/ml of gentamicin inhibited intracellular growth of SCHU S4 and that the combined treatment acted synergistically. Moreover, treatment of F. tularensis-infected mice with gentamicin and gallium showed an additive effect. Collectively, the data demonstrate that SCHU S4 is dependent on iron to minimize the effects of gentamicin and that gallium, by inhibiting the iron uptake, potentiates the bactericidal effect of gentamicin in vitro and in vivo. PMID:26503658

Gallium Potentiates the Antibacterial Effect of Gentamicin against Francisella tularensis.

PubMed

Lindgren, Helena; Sjöstedt, Anders

2016-01-01

The reasons why aminoglycosides are bactericidal have not been not fully elucidated, and evidence indicates that the cidal effects are at least partly dependent on iron. We demonstrate that availability of iron markedly affects the susceptibility of the facultative intracellular bacterium Francisella tularensis strain SCHU S4 to the aminoglycoside gentamicin. Specifically, the intracellular depots of iron were inversely correlated to gentamicin susceptibility, whereas the extracellular iron concentrations were directly correlated to the susceptibility. Further proof of the intimate link between iron availability and antibiotic susceptibility were the findings that a ΔfslA mutant, which is defective for siderophore-dependent uptake of ferric iron, showed enhanced gentamicin susceptibility and that a ΔfeoB mutant, which is defective for uptake of ferrous iron, displayed complete growth arrest in the presence of gentamicin. Based on the aforementioned findings, it was hypothesized that gallium could potentiate the effect of gentamicin, since gallium is sequestered by iron uptake systems. The ferrozine assay demonstrated that the presence of gallium inhibited >70% of the iron uptake. Addition of gentamicin and/or gallium to infected bone marrow-derived macrophages showed that both 100 μM gallium and 10 μg/ml of gentamicin inhibited intracellular growth of SCHU S4 and that the combined treatment acted synergistically. Moreover, treatment of F. tularensis-infected mice with gentamicin and gallium showed an additive effect. Collectively, the data demonstrate that SCHU S4 is dependent on iron to minimize the effects of gentamicin and that gallium, by inhibiting the iron uptake, potentiates the bactericidal effect of gentamicin in vitro and in vivo. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The therapeutic potential of iron-targeting gallium compounds in human disease: From basic research to clinical application.

PubMed

Chitambar, Christopher R

2017-01-01

Gallium, group IIIa metal, shares certain chemical characteristics with iron which enable it to function as an iron mimetic that can disrupt iron-dependent tumor cell growth. Gallium may also display antimicrobial activity by disrupting iron homeostasis in certain bacteria and fungi. Gallium's action on iron homeostasis leads to inhibition of ribonucleotide reductase, mitochondrial function, and changes in proteins of iron transport and storage. In addition, gallium induces an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Early clinical trials evaluated the efficacy of the simple gallium salts, gallium nitrate and gallium chloride. However, newer gallium-ligands such as Tris(8-quinolinolato)gallium(III) (KP46) and gallium maltolate have been developed and are undergoing clinical evaluation. Additional gallium-ligands that demonstrate antitumor activity in preclinical studies have emerged. Their mechanisms of action and their spectrum of antitumor activity may extend beyond the earlier generations of gallium compounds and warrant further investigation. This review will focus on the evolution and potential of gallium-based therapeutics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Magnesium isotope fractionation in co-existing clino-pyroxene and garnet: implications for geothermometry and mantle source characterization

NASA Astrophysics Data System (ADS)

Chakrabarti, R.; Jacobsen, S. B.; Basu, A. R.

2011-12-01

It is now well established that the Mg isotopic composition of the bulk silicate Earth, as represented by olivines, peridotites and basalts is identical to bulk meteorites and the Moon. However, small differences have been documented between co-existing olivines and clino-pyroxenes in mantle xenoliths as well as co-existing hornblendes and biotites in granitoids; spinels show some of the heaviest δ26Mg (deviation of the 26Mg/24Mg ratio from the Dead Sea Metal standard). A recent study has documented a large Mg isotopic fractionation between co-existing omphacite and garnet (Δ26MgOMP-GT = δ26MgOMP - δ26MgGT ~1.14) from eclogites in the Dabie orogen of China. This large equilibrium Mg isotope fractionation is explained by the difference in coordination number of Mg in omphacite (six) and garnet (eight). We report stable Mg isotopic compositions of co-existing garnet and clino-pyroxenes from different mantle-derived rocks. Garnet-omphacite pairs analyzed are from an eclogite xenolith from the Roberts Victor kimberlite pipe, the ultra-high pressure Tso Morari eclogite from the Ladakh Himalayas and the Healdsburg eclogite from the Franciscan Subduction Complex, which have a wide range in estimated temperatures of equilibration. Although, the latter two eclogites were exhumed in orogenic belts, our selective picking of the mineral cores for analysis avoided retrograded compositions. We have also analyzed Cr-diopside and pyrope-rich garnet pairs from several southern African kimberlite pipes. These include granular garnet peridotite xenoliths (P = 30-40 kbar, T =950-10500C) as well as the deeper sheared xenoliths (P = 50-60 kbar, T = 13500C). Rapid quenching of the kimberlite-hosted xenoliths ensures minimal low temperature pervasive alteration of these samples. Also analyzed are samples from the Gore Mt. amphibolite and a wollastonite-diopside-garnet skarn from the Adirondacks with equilibration temperatures of 700-7260C. Minerals were separated by hand-picking under

Multiple scaling power in liquid gallium under pressure conditions

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

Li, Renfeng; Wang, Luhong; Li, Liangliang

Generally, a single scaling exponent, Df, can characterize the fractal structures of metallic glasses according to the scaling power law. However, when the scaling power law is applied to liquid gallium upon compression, the results show multiple scaling exponents and the values are beyond 3 within the first four coordination spheres in real space, indicating that the power law fails to describe the fractal feature in liquid gallium. The increase in the first coordination number with pressure leads to the fact that first coordination spheres at different pressures are not similar to each other in a geometrical sense. This multiplemore » scaling power behavior is confined within a correlation length of ξ ≈ 14–15 Å at applied pressure according to decay of G(r) in liquid gallium. Beyond this length the liquid gallium system could roughly be viewed as homogeneous, as indicated by the scaling exponent, Ds, which is close to 3 beyond the first four coordination spheres.« less

Gallium(iii) and iron(iii) complexes of quinolone antimicrobials.

PubMed

Mjos, Katja Dralle; Cawthray, Jacqueline F; Polishchuk, Elena; Abrams, Michael J; Orvig, Chris

2016-08-16

Iron is an essential nutrient for many microbes. According to the "Trojan Horse Hypothesis", biological systems have difficulties distinguishing between Fe(3+) and Ga(3+), which constitutes the antimicrobial efficacy of the gallium(iii) ion. Nine novel tris(quinolono)gallium(iii) complexes and their corresponding iron(iii) analogs have been synthesized and fully characterized. Quinolone antimicrobial agents from three drug generations were used in this study: ciprofloxacin, enoxacin, fleroxacin, levofloxacin, lomefloxacin, nalidixic acid, norfloxacin, oxolinic acid, and pipemidic acid. The antimicrobial efficacy of the tris(quinolono)gallium(iii) complexes was studied against E. faecalis and S. aureus (both Gram-positive), as well as E. coli, K. pneumonia, and P. aeruginosa (all Gram-negative) in direct comparison to the tris(quinolono)iron(iii) complexes and the corresponding free quinolone ligands at various concentrations. For the tris(quinolono)gallium(iii) complexes, no combinational antimicrobial effects between Ga(3+) and the quinolone antimicrobial agents were observed.

Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster

NASA Technical Reports Server (NTRS)

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

2007-01-01

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.

Non-LTE gallium abundance in HgMn stars

NASA Astrophysics Data System (ADS)

Zboril, M.; Berrington, K. A.

2001-07-01

We present, for the first time, the Non-LTE gallium equivalent widths for the most prominent gallium transitions as identified in real spectra and in (hot) mercury-manganese star. The common feature of the departure coefficients is to decrease near the stellar surface, the collision rates are dominant in many cases and the Non-LTE equivalent widths are generally smaller. In particular, the abundance difference as derived from UV and visual lines is reduced. The photoionization cross sections were computed by means of standard R-matrix formalism. The gallium cross-sections are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/373/987

Systematic Study of p-type Doping and Related Defects in III-Nitrides: Pathway toward a Nitride HBT

DTIC Science & Technology

2012-11-20

InGaN growth where an intermediate regime does not exist.40 Considering GaN molecular - beam epitaxy (MBE) growth phase diagrams such as those...1009 (2007). 44 S. D. Burnham, Improved Understanding and Control of Magnesium-Doped Gallium Nitride by Plasma Assisted Molecular Beam Epitaxy , in...reported using a modified form of molecular beam epitaxy (MBE) called Metal-Modulated Epitaxy (MME).11, 12 The details of this shuttered technique

Multistage metasomatism in lithospheric mantle beneath V. Grib pipe (Arkhangelsk diamondiferous province, Russia): evidence from REE patterns in garnet xenocrysts.

NASA Astrophysics Data System (ADS)

Shchukina, Elena; Alexei, Agashev; Nikolai, Pokhilenko

2015-04-01

150 garnet xenocrysts from V. Grib kimberlite pipe were analyzed for major and trace elements compositions. 70 % of garnet belong to lherzolite field; 14 % - megacrysts and pyroxenites; 11 % - eclogites; 4 % - harzburgite; 1 % (1- wehrlite defined by Sobolev (1973). Harzburgite garnets: sinusoidal REE patterns Smn/Ern > 5 (5.2 - 19.8). low Y (0.5 - 3.9 ppm), Zr (1.1 - 44.6 ppm), Ti (54 - 1322 ppm). Wehrlite garnetd: close to sinusoidal REE patterns, Smn/Ern - 1.8. Megacrysts and pyroxenites garnets: normal REE patterns Smn/Ern < 1 (0.2 - 0.6), high TiO2 (0.9 - 1.3 wt %). Lherzolite garnets 70 % show four groups of REE patterns similar to peridotite xenoliths (Shchukina et al., 2013, 2015). 1-st contains MREE at С1 level, Sm/Ern - 0.03, La/Ybn - 0.002. increasing La -Yb range, low Y, Zr, Ti indicating residual nature. 2-nd: MREE at 2 - 13 chondrite units, Smn/Ern (0.16 - 0.98), La/Ybn - 0.001 - 0.040 and flat pattern from MREE to HREE. 3-rd -MREE at 5 - 14 chondrite units, Sm/Ern > 1 (1.05 - 4.81) La/Ybn - 0.010-0.051 increasing an hump at MREE decreasing to HREE. 4-th: sinusoidal REE, Sm/Ern 4.2 - 27.2. and harzburgite Y, Zr, Ti . Average Cr2O3 content increases from 2-nd to the 3-rd group (3.3 to 5.7 wt%) and 4th (7.9 wt %). Average Y/Zr decreases from 2-nd (0.6) to 3rd (0.2) and 4th group (0.08). REE and Y, Zr, Ti indicate the metasomatic origin of garnets of 2, 3. 4 groups. Modeling of TREfor equilibrated melts and fractional crystallization 2nd group close to Turyino field basalts and 3-rd - to Izmozero field picrites of Arkhangelsk diamondiferous province (ADP). Basing on geochemical data of garnet xenocrysts and garnets and clinopyroxenes in peridotites (Shchukina et al., 2013, 2015) we suppose at least 3 stage of high-temperature metasomatic enrichment. 1st stage - is enrichment of residual garnets (found only in peridotite garnets) in LREE by the influence of carbonatite melt close to the Mela field carbonatites of ADP. REE patterns in clinopyroxenes from

Magnesium acceptor in gallium nitride. I. Photoluminescence from Mg-doped GaN

NASA Astrophysics Data System (ADS)

Reshchikov, M. A.; Ghimire, P.; Demchenko, D. O.

2018-05-01

Defect-related photoluminescence (PL) is analyzed in detail for n -type, p -type, and semi-insulating Mg-doped GaN grown by different techniques. The ultraviolet luminescence (UVL) band is the dominant PL band in conductive n -type and p -type GaN:Mg samples grown by hydride vapor phase epitaxy (HVPE) and molecular beam epitaxy. The UVL band in undoped and Mg-doped GaN samples is attributed to the shallow M gGa acceptor with the ionization energy of 223 meV. In semi-insulating GaN:Mg samples, very large shifts of the UVL band (up to 0.6 eV) are observed with variation of temperature or excitation intensity. The shifts are attributed to diagonal transitions, likely due to potential fluctuations or near-surface band bending. The blue luminescence (B LMg ) band is observed only in GaN:Mg samples grown by HVPE or metalorganic chemical vapor deposition when the concentration of Mg exceeds 1019c m-3 . The B LMg band is attributed to electron transitions from an unknown deep donor to the shallow M gGa acceptor. Basic properties of the observed PL are explained with a phenomenological model.

Gallium nitrate: effects on cartilage during limb regeneration in the axolotl, Ambystoma mexicanum.

PubMed

Tassava, Roy A; Mendenhall, Luciara; Apseloff, Glen; Gerber, Nicholas

2002-09-01

Gallium nitrate, a drug shown to have efficacy in Paget's disease of bone, hypercalcemia of malignancy, and a variety of experimental autoimmune diseases, also inhibits the growth of some types of cancer. We examined dose and timing of administration of gallium nitrate on limb regeneration in the Mexican axolotl, Ambystoma mexicanum. Administered by intraperitoneal injection, gallium nitrate inhibited limb regeneration in a dose-dependent manner. Gallium nitrate initially suppressed epithelial wound healing and subsequently distorted both anterior-posterior and proximo-distal chondrogenic patterns. Gallium nitrate given at three days after amputation severely inhibited regeneration at high doses (6.25 mg/axolotl) and altered the normal patterning of the regenerates at low doses (3.75 mg/axolotl). Administration of 6.25 mg of gallium nitrate at four or 14 days prior to amputation also inhibited regeneration. In amputated limbs of gallium-treated axolotls, the chondrocytes were lost from inside the radius/ulna. Limbs that regenerated after gallium treatment was terminated showed blastema formation preferentially over the ulna. New cartilage of the regenerate often attached to the sides of the existing radius/ulna proximally into the stump and less so to the distal cut ends. J. Exp. Zool. 293:384-394, 2002. Copyright 2002 Wiley-Liss, Inc.

High Performance, Low Temperature Solution-Processed Barium and Strontium Doped Oxide Thin Film Transistors.

PubMed

Banger, Kulbinder K; Peterson, Rebecca L; Mori, Kiyotaka; Yamashita, Yoshihisa; Leedham, Timothy; Sirringhaus, Henning

2014-01-28

Amorphous mixed metal oxides are emerging as high performance semiconductors for thin film transistor (TFT) applications, with indium gallium zinc oxide, InGaZnO (IGZO), being one of the most widely studied and best performing systems. Here, we investigate alkaline earth (barium or strontium) doped InBa(Sr)ZnO as alternative, semiconducting channel layers and compare their performance of the electrical stress stability with IGZO. In films fabricated by solution-processing from metal alkoxide precursors and annealed to 450 °C we achieve high field-effect electron mobility up to 26 cm 2 V -1 s -1 . We show that it is possible to solution-process these materials at low process temperature (225-200 °C yielding mobilities up to 4.4 cm 2 V -1 s -1 ) and demonstrate a facile "ink-on-demand" process for these materials which utilizes the alcoholysis reaction of alkyl metal precursors to negate the need for complex synthesis and purification protocols. Electrical bias stress measurements which can serve as a figure of merit for performance stability for a TFT device reveal Sr- and Ba-doped semiconductors to exhibit enhanced electrical stability and reduced threshold voltage shift compared to IGZO irrespective of the process temperature and preparation method. This enhancement in stability can be attributed to the higher Gibbs energy of oxidation of barium and strontium compared to gallium.

High Performance, Low Temperature Solution-Processed Barium and Strontium Doped Oxide Thin Film Transistors

PubMed Central

2013-01-01

Amorphous mixed metal oxides are emerging as high performance semiconductors for thin film transistor (TFT) applications, with indium gallium zinc oxide, InGaZnO (IGZO), being one of the most widely studied and best performing systems. Here, we investigate alkaline earth (barium or strontium) doped InBa(Sr)ZnO as alternative, semiconducting channel layers and compare their performance of the electrical stress stability with IGZO. In films fabricated by solution-processing from metal alkoxide precursors and annealed to 450 °C we achieve high field-effect electron mobility up to 26 cm2 V–1 s–1. We show that it is possible to solution-process these materials at low process temperature (225–200 °C yielding mobilities up to 4.4 cm2 V–1 s–1) and demonstrate a facile “ink-on-demand” process for these materials which utilizes the alcoholysis reaction of alkyl metal precursors to negate the need for complex synthesis and purification protocols. Electrical bias stress measurements which can serve as a figure of merit for performance stability for a TFT device reveal Sr- and Ba-doped semiconductors to exhibit enhanced electrical stability and reduced threshold voltage shift compared to IGZO irrespective of the process temperature and preparation method. This enhancement in stability can be attributed to the higher Gibbs energy of oxidation of barium and strontium compared to gallium. PMID:24511184

Origin of biotite-hornblende-garnet coronas between oxides and plagioclase in olivine metagabbros, Adirondack region, New York

USGS Publications Warehouse

Whitney, P.R.; McLelland, J.M.

1982-01-01

Complex multivariant reactions involving Fe-Ti oxide minerals, plagioclase and olivine have produced coronas of biotite, hornblende and garnet between ilmenite and plagioclase in Adirondack olivine metagabbros. Both the biotite (6-10% TiO2) and the hornblende (3-6% TiO2) are exceptionally Titanium-rich. The garnet is nearly identical in composition to the garnet in coronas around olivine in the same rocks. The coronas form in two stages: (a) Plagioclase+Fe-Ti Oxides+Olivine+water =Hornblende+Spinel+Orthopyroxene??Biotite +more-sodic Plagioclase (b) Hornblende+Orthopyroxene??Spinel+Plagioclase =Garnet+Clinopyroxene+more-sodic Plagioclase The Orthopyroxene and part of the clinopyroxene form adjacent to olivine. Both reactions are linked by exchange of Mg2+ and Fe2+ with the reactions forming pyroxene and garnet coronas around olivine in the same rocks. The reactions occur under granulite fades metamorphic conditions, either during isobaric cooling or with increasing pressure at high temperature. ?? 1983 Springer-Verlag.

The Inhibition of Escherichia coli Biofilm Formation by Gallium Nitrate-Modified Titanium.

PubMed

Zhu, Yuanyuan; Qiu, Yan; Chen, Ruiqi; Liao, Lianming

2015-08-01

Periprosthetic infections are notoriously difficult to treat due to biofilm formation. Previously, we reported that gallium-EDTA attached to PVC (polyvinyl chloride) surface could prevent bacterial colonization. Herein we examined the effect of this gallium-EDTA complex on Escherichia coli biofilm formation on titanium. It was clearly demonstrated that gallium nitrate significantly inhibited the growth and auto-aggregation of Escherichia coli. Furthermore, titanium with gallium-EDTA coating resisted bacterial colonization as indicated by crystal violet staining. When the chips were immersed in human serum and incubated at 37 °C, they demonstrated significant antimicrobial activity after more than 28 days of incubation. These findings indicate that gallium-EDTA coating of implants can result in a surface that can resist bacterial colonization. This technology holds great promise for the prevention and treatment of periprosthetic infections.

Wear performance of garnet aluminium composites at high contact pressure

NASA Astrophysics Data System (ADS)

Sharma, Anju; Arora, Rama; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

2016-05-01

To satisfy the needs of the engineering sector, researchers and material scientists in this area adopted the development of composites with tailor made properties to enhance efficiency and cost savings in the manufacturing sector. The technology of the mineral industry is shaping the supply and demand of minerals derived materials. The composites are best classified as high performance materials have high strength-to-weight ratios, and require controlled manufacturing environments for optimum performance. Natural mineral garnet was used as the reinforcement of composite because of satisfactory mechanical properties as well as an attractive ecological alternative to others ceramics. For this purpose, samples have been prepared with different sizesof the garnet reinforcement using the mechanical stirring method to achieve the homogeneously dispersed strengthening phase. A systematic study of the effect of high contact pressure on the sliding wear behaviour of garnet reinforced LM13 alloy composites is presented in this paper. The SEM analysis of the worn samples and debris reveals the clues about the wear mechanism. The drastic improvement in the wear resistance of the composites at high contact pressure shows the high potential of the material to be used in engineering applications.

Hot and solid gallium clusters: too small to melt.

PubMed

Breaux, Gary A; Benirschke, Robert C; Sugai, Toshiki; Kinnear, Brian S; Jarrold, Martin F

2003-11-21

A novel multicollision induced dissociation scheme is employed to determine the energy content for mass-selected gallium cluster ions as a function of their temperature. Measurements were performed for Ga(+)(n) (n=17 39, and 40) over a 90-720 K temperature range. For Ga+39 and Ga+40 a broad maximum in the heat capacity-a signature of a melting transition for a small cluster-occurs at around 550 K. Thus small gallium clusters melt at substantially above the 302.9 K melting point of bulk gallium, in conflict with expectations that they will remain liquid to below 150 K. No melting transition is observed for Ga+17.

Comparison of Micro-Leakage from Resin-Modified Glass Ionomer Restorations in Cavities Prepared by Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) Laser and Conventional Method in Primary Teeth

PubMed Central

Bahrololoomi, Zahra; Razavi, Forooghosadat; Soleymani, Ali Asghar

2014-01-01

Introduction: In recent years, significant developments have been taking place in caries removal and cavity preparation using laser in dentistry. As laser use is considered for cavity preparation, it is necessary to determine the quality of restoration margins. Glass ionomer cements have great applications for conservative restoration in the pediatric field. The purpose of this in vitro study was to compare resin-modified glass ionomer restorations micro-leakage in cavities prepared by Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) laser irradiation and conventional method in primary teeth. Methods: This was an in vitro experimental study. Forty primary canine teeth were divided into 2 groups: group 1 represented cavities prepared by the no. 008 diamond bur, group 2 represented cavities prepared by Er:YAG laser. After cavity preparation, samples were restored by resin-modified glass ionomer. The teeth were thermocycled for 700 cycles, placed in 2% methylene blue for 24h and sectioned in the buccolingual direction. The degree of dye penetration was scored by 3 examiners. Data was analyzed using Mann-Whitney Test. Results: There was no statistical difference in micro-leakage between the two modes of cavity preparation (P=0.862) Conclusion: Since preparing conservative cavities is very important in pediatric dentistry, it is possible to use Er:YAG laser because of its novel and portable technology. However, further investigations of other restorative materials and other laser powers are required. PMID:25653819

Formation of self-organized nanoporous anodic oxide from metallic gallium.

PubMed

Pandey, Bipin; Thapa, Prem S; Higgins, Daniel A; Ito, Takashi

2012-09-25

This paper reports the formation of self-organized nanoporous gallium oxide by anodization of solid gallium metal. Because of its low melting point (ca. 30 °C), metallic gallium can be shaped into flexible structures, permitting the fabrication of nanoporous anodic oxide monoliths within confined spaces like the inside of a microchannel. Here, solid gallium films prepared on planar substrates were employed to investigate the effects of anodization voltage (1, 5, 10, 15 V) and H(2)SO(4) concentration (1, 2, 4, 6 M) on anodic oxide morphology. Self-organized nanopores aligned perpendicular to the film surface were obtained upon anodization of gallium films in ice-cooled 4 and 6 M aqueous H(2)SO(4) at 10 and 15 V. Nanopore formation could be recognized by an increase in anodic current after a current decrease reflecting barrier oxide formation. The average pore diameter was in the range of 18-40 nm with a narrow diameter distribution (relative standard deviation ca. 10-20%), and was larger at lower H(2)SO(4) concentration and higher applied voltage. The maximum thickness of nanoporous anodic oxide was ca. 2 μm. In addition, anodic formation of self-organized nanopores was demonstrated for a solid gallium monolith incorporated at the end of a glass capillary. Nanoporous anodic oxide monoliths formed from a fusible metal will lead to future development of unique devices for chemical sensing and catalysis.

Defining conditions of garnet growth across the central and southern Menderes Massif, western Turkey

NASA Astrophysics Data System (ADS)

Etzel, T. M.; Catlos, E. J.; Kelly, E. D.; Cemen, I.; Ozerdem, C.; Atakturk, K. R.

2017-12-01

Here we apply thermodynamic modeling using Theriak-Domino to garnet-bearing rocks from the central and southern portions of the Menderes Massif to gain insight into the dynamics of western Turkey as the region experienced a transition from collisional to extensional tectonics. To this end, we report new pressure-temperature (P-T) paths from garnet-bearing rocks collected along the Alasehir detachment fault, a prominent exhumation structure in the central portion of the Menderes Massif in western Turkey, constituting the southern margin of the Alasehir Graben. These paths are compared to those from the Selimiye shear zone in the Southern (Cine) Massif. Two Alasehir garnets collected from the same outcrop record two P-T paths: 1) a prograde path beginning at 565oC and 6.4 kbar increasing to 592 oC and 7.5 kbar; and 2) near isobaric growth initiating at 531oC and 7.1 kbar and terminating at 571oC and 7.3 kbar. High-resolution P-T paths could not be modeled for the majority of Alasehir samples due to diffusional modification of garnet. However, conditions were estimated by garnet isopleth thermobarometry at the point of highest spessartine content for each crystal. Calculated P-T values for this subset of samples range between 566-651oC and 6.2-6.8 kbar. Despite this broad range, these P-T conditions are consistent with what is observed in the modeled paths. Th-Pb ages of matrix monazite range from 35.8±3.0 to 20.6±2.4 Ma, suggesting metamorphism in the central Menderes Massif occurred over a 15 m.y. period. Selimiye shear zone rocks show distinct N-shaped P-T paths, suggesting garnets in the central and southern portion of the Menderes Massif record distinctly different tectonic histories.

Realization of the Gallium Triple Point at NMIJ/AIST

NASA Astrophysics Data System (ADS)

Nakano, T.; Tamura, O.; Sakurai, H.

2008-02-01

The triple point of gallium has been realized by a calorimetric method using capsule-type standard platinum resistance thermometers (CSPRTs) and a small glass cell containing about 97 mmol (6.8 g) of gallium with a nominal purity of 99.99999%. The melting curve shows a very flat and relatively linear dependence on 1/ F in the region from 1/ F = 1 to 1/ F = 20 with a narrow width of the melting curve within 0.1 mK. Also, a large gallium triple-point cell was fabricated for the calibration of client-owned CSPRTs. The gallium triple-point cell consists of a PTFE crucible and a PTFE cap with a re-entrant well and a small vent. The PTFE cell contains 780 g of gallium from the same source as used for the small glass cell. The PTFE cell is completely covered by a stainless-steel jacket with a valve to enable evacuation of the cell. The melting curve of the large cell shows a flat plateau that remains within 0.03 mK over 10 days and that is reproducible within 0.05 mK over 8 months. The calibrated value of a CSPRT obtained using the large cell agrees with that obtained using the small glass cell within the uncertainties of the calibrations.