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.

Spin waves in micro-structured yttrium iron garnet nanometer-thick films

DOE PAGES

Jungfleisch, Matthias B.; Zhang, Wei; Jiang, Wanjun; ...

2015-03-24

Here, we investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of 40 nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spinwave amplitude of 10 μm was observed. This leads to an estimated Gilbert damping constant of α = (8.79 ± 0.73) x 10 $-$4, which is larger than damping values obtained through ferromagnetic resonance measurements in unstructured films. Furthermore, we compared the theoretically calculated spatial interference of waveguide modes to the spin-wave pattern observed experimentally by means of Brillouin light scattering spectroscopy.

High-frequency magnetodielectric response in yttrium iron garnet at room temperature

NASA Astrophysics Data System (ADS)

Zhu, Jie; Liu, Yuan; Jia, Longfei; Zhang, Baoshan; Yang, Yi; Tang, Dongming

2018-05-01

Magnetic and dielectric properties of Yttrium Iron Garnet are measured over a frequency ranging from 0.5 GHz to 10 GHz with a magnetic field applied parallel to the propagation direction of the microwave. At the same time, the magnetodielectric phenomena are detected quantitatively. The maximum amplitude of the magnetodielectric coefficient is acquired at the ferromagnetic resonance frequency, and the value is up to 1.2% with the magnetic field of 1500 Oe applied. The phenomena have been explained by the Faraday's electromagnetic induction of the precession of the magnetic moments in the electromagnetic field at the ferromagnetic resonance frequency.

Curie temperature, exchange integrals, and magneto-optical properties in off-stoichiometric bismuth iron garnet epitaxial films

NASA Astrophysics Data System (ADS)

Vertruyen, B.; Cloots, R.; Abell, J. S.; Jackson, T. J.; da Silva, R. C.; Popova, E.; Keller, N.

2008-09-01

We have studied the influence of the stoichiometry on the structural, magnetic, and magneto-optical properties of bismuth iron garnet (Bi3Fe5O12) thin films grown by pulsed laser deposition. Films with different stoichiometries have been obtained by varying the Bi/Fe ratio of the target and the oxygen pressure during deposition. Stoichiometry variations influence the Curie temperature TC by tuning the (Fe)-O-[Fe] geometry: TC increases when the lattice parameter decreases, contrary to what happens in the case of stoichiometric rare-earth iron garnets. The thermal variation of the magnetization, the Faraday rotation, and the Faraday ellipticity have been analyzed in the frame of the Néel two-sublattice magnetization model giving energies of -48K (4.1 meV), -29K (2.5 meV), and 84 K (7.3 meV) for the three magnetic exchange integrals jaa , jdd , and jad , respectively. Magneto-optical spectroscopy linked to compositional analysis by Rutherford backscattering spectroscopy shows that Bi and/or Fe deficiencies also affect the spectral variation (between 1.77 and 3.1 eV). Our results suggest that bismuth deficiency has an effect on the magneto-optical response of the tetrahedral Fe sublattice, whereas small iron deficiencies affect predominantly the magneto-optical response of the octahedral sublattice.

Neutron scattering study of yttrium iron garnet

NASA Astrophysics Data System (ADS)

Shamoto, Shin-ichi; Ito, Takashi U.; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato; Akatsu, Mitsuhiro; Kodama, Katsuaki; Nakao, Akiko; Moyoshi, Taketo; Munakata, Koji; Ohhara, Takashi; Nakamura, Mitsutaka; Ohira-Kawamura, Seiko; Nemoto, Yuichi; Shibata, Kaoru

2018-02-01

The nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y3Fe5O12 have been studied using neutron scattering. The refined nuclear structure is distorted to a trigonal space group of R 3 ¯ . The highest-energy dispersion extends up to 86 meV. The observed dispersions are reproduced by a simple model with three nearest-neighbor-exchange integrals between 16 a (octahedral) and 24 d (tetrahedral) sites, Ja a, Ja d, and Jd d, which are estimated to be 0.00 ±0.05 , -2.90 ±0.07 , and -0.35 ±0.08 meV, respectively. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of q -integrated dynamical spin susceptibility χ″(E ) exhibits a square-root energy dependence at low energies. The magnon density of state is estimated from χ″(E ) obtained on an absolute scale. The value is consistent with the single chirality mode for the magnon branch expected theoretically.

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

Finite temperature magnon spectra in yttrium iron garnet from a mean field approach in a tight-binding model

NASA Astrophysics Data System (ADS)

Shen, Ka

2018-04-01

We study magnon spectra at finite temperature in yttrium iron garnet using a tight-binding model with nearest-neighbor exchange interaction. The spin reduction due to thermal magnon excitation is taken into account via the mean field approximation to the local spin and is found to be different at two sets of iron atoms. The resulting temperature dependence of the spin wave gap shows good agreement with experiment. We find that only two magnon modes are relevant to the ferromagnetic resonance.

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

Revising the magnetic structure and dynamics of Yttrium Iron Garnet

NASA Astrophysics Data System (ADS)

Princep, Andrew; Boothroyd, Andrew; Ewings, Russell; Ward, Simon; Dubs, Carsten

Yttrium iron garnet (YIG) is the `miracle material' of microwave magnetics. Since its synthesis by Geller and Gilleo in 1957, it is widely acknowledged to have contributed more to the understanding of electronic spin-wave and magnon dynamics than any other substance. Its astonishingly narrow excitation linewidth allows magnon propagation to be observed over centimetre distances, making it both a superior model system for the experimental study of fundamental aspects of microwave magnetic dynamics and an ideal platform for the development of microwave magnetic technologies. Our experiments on a large, pristine single crystal at the ISIS facility using both diffraction and time-of-flight spectroscopy have provided new results on both the magnetic structure and the excitation spectrum, which revise nearly 60 years of scientific research and will be essential insights for the fledgling scientific field of Magnonics. EPSRC, UK.

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.

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).

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

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.

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} .

Phase Diagram for Magnon Condensate in Yttrium Iron Garnet Film

PubMed Central

Li, Fuxiang; Saslow, Wayne M.; Pokrovsky, Valery L.

2013-01-01

Recently, magnons, which are quasiparticles describing the collective motion of spins, were found to undergo Bose-Einstein condensation (BEC) at room temperature in films of Yttrium Iron Garnet (YIG). Unlike other quasiparticle BEC systems, this system has a spectrum with two degenerate minima, which makes it possible for the system to have two condensates in momentum space. Recent Brillouin Light Scattering studies for a microwave-pumped YIG film of thickness d = 5 μm and field H = 1 kOe find a low-contrast interference pattern at the characteristic wavevector Q of the magnon energy minimum. In this report, we show that this modulation pattern can be quantitatively explained as due to unequal but coherent Bose-Einstein condensation of magnons into the two energy minima. Our theory predicts a transition from a high-contrast symmetric state to a low-contrast non-symmetric state on varying the d and H, and a new type of collective oscillation. PMID:23455849

Magnetophotonic crystals based on yttrium-iron-garnet infiltrated opals: Magnetization-induced second-harmonic generation

NASA Astrophysics Data System (ADS)

Murzina, T. V.; Kim, E. M.; Kapra, R. V.; Moshnina, I. V.; Aktsipetrov, O. A.; Kurdyukov, D. A.; Kaplan, S. F.; Golubev, V. G.; Bader, M. A.; Marowsky, G.

2006-01-01

Three-dimensional magnetophotonic crystals (MPCs) based on artificial opals infiltrated by yttrium iron garnet (YIG) are fabricated and their structural, optical, and nonlinear optical properties are studied. The formation of the crystalline YIG inside the opal matrix is checked by x-ray analysis. Two templates are used for the infiltration by YIG: bare opals and those covered by a thin platinum film. Optical second-harmonic generation (SHG) technique is used to study the magnetization-induced nonlinear-optical properties of the composed MPCs. A high nonlinear magneto-optical Kerr effect in the SHG intensity is observed at the edge of the photonic band gap of the MPCs.

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.

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

Spin wave propagation in perpendicularly magnetized nm-thick yttrium iron garnet films

NASA Astrophysics Data System (ADS)

Chen, Jilei; Heimbach, Florian; Liu, Tao; Yu, Haiming; Liu, Chuanpu; Chang, Houchen; Stückler, Tobias; Hu, Junfeng; Zeng, Lang; Zhang, Youguang; Liao, Zhimin; Yu, Dapeng; Zhao, Weisheng; Wu, Mingzhong

2018-03-01

Magnonics offers a new way for information transport that uses spin waves (SWs) and is free of charge currents. Unlike Damon-Eshbach SWs, the magneto-static forward volume SWs offer the reciprocity configuration suitable for SW logic devices with low power consumption. Here, we study forward volume SW propagation in yttrium iron garnet (YIG) thin films with an ultra-low damping constant α = 8 ×10-5 . We design different integrated microwave antenna with different k-vector excitation distributions on YIG thin films. Using a vector network analyzer, we measured SW transmission with the films magnetized in perpendicular orientation. Based on the experimental results, we extract the group velocity as well as the dispersion relation of SWs and directly compare the power efficiency of SW propagation in YIG using coplanar waveguide and micro stripline for SW excitation and detection.

Flux-gate magnetic field sensor based on yttrium iron garnet films for magnetocardiography investigations

NASA Astrophysics Data System (ADS)

Vetoshko, P. M.; Gusev, N. A.; Chepurnova, D. A.; Samoilova, E. V.; Syvorotka, I. I.; Syvorotka, I. M.; Zvezdin, A. K.; Korotaeva, A. A.; Belotelov, V. I.

2016-08-01

A new type of f lux-gate vector magnetometer based on epitaxial yttrium iron garnet films has been developed and constructed for magnetocardiography (MCG) investigations. The magnetic field sensor can operate at room temperature and measure MCG signals at a distance of about 1 mm from the thoracic cage. The high sensitivity of the sensor, better than 100 fT/Hz1/2, is demonstrated by the results of MCG measurements on rats. The main MCG pattern details and R-peak on a level of 10 pT are observed without temporal averaging, which allows heart rate anomalies to be studied. The proposed magnetic sensors can be effectively used in MCG investigations.

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.

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.

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.

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.

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.

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

Radiotherapeutic bandage based on electrospun polyacrylonitrile containing holmium-166 iron garnet nanoparticles for the treatment of skin cancer.

PubMed

Munaweera, Imalka; Levesque-Bishop, Daniel; Shi, Yi; Di Pasqua, Anthony J; Balkus, Kenneth J

2014-12-24

Radiation therapy is used as a primary treatment for inoperable tumors and in patients that cannot or will not undergo surgery. Radioactive holmium-166 ((166)Ho) is a viable candidate for use against skin cancer. Nonradioactive holmium-165 ((165)Ho) iron garnet nanoparticles have been incorporated into a bandage, which, after neutron-activation to (166)Ho, can be applied to a tumor lesion. The (165)Ho iron garnet nanoparticles ((165)HoIG) were synthesized and introduced into polyacrylonitrile (PAN) polymer solutions. The polymer solutions were then electrospun to produce flexible nonwoven bandages, which are stable to neutron-activation. The fiber mats were characterized using scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and inductively coupled plasma mass spectrometry. The bandages are stable after neutron-activation at a thermal neutron-flux of approximately 3.5 × 10(12) neutrons/cm(2)·s for at least 4 h and 100 °C. Different amounts of radioactivity can be produced by changing the amount of the (165)HoIG nanoparticles inside the bandage and the duration of neutron-activation, which is important for different stages of skin cancer. Furthermore, the radioactive bandage can be easily manipulated to irradiate only the tumor site by cutting the bandage into specific shapes and sizes that cover the tumor prior to neutron-activation. Thus, exposure of healthy cells to high energy β-particles can be avoided. Moreover, there is no leakage of radioactive material after neutron activation, which is critical for safe handling by healthcare professionals treating skin cancer patients.

Negative permittivity and permeability spectra of Cu/yttrium iron garnet hybrid granular composite materials in the microwave frequency range

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

Tsutaoka, Takanori, E-mail: tsutaok@hiroshima-u.ac.jp; Fukuyama, Koki; Kinoshita, Hideaki

2013-12-23

The relative complex permittivity and permeability spectra of the coagulated copper and yttrium iron garnet (Cu/YIG) hybrid granular composite materials have been studied in the microwave range. The insulator to metal transition was observed at the percolation threshold of Cu particle content (φ{sub Cu} = 16.0 vol. %) in the electrical conductivity. In the percolation threshold, the low frequency plasmonic state caused by the metallic Cu particle networks was observed. The percolated Cu/YIG granular composites show simultaneous negative permittivity and permeability spectra under external magnetic fields.

Magnetic study of the low temperature anomalies in the magnetodielectric terbium iron garnet

NASA Astrophysics Data System (ADS)

Lahoubi, Mahieddine

2018-05-01

The anomalous magnetic properties at low temperatures of terbium iron garnet (TbIG) are analyzed and summarized using neutron powder diffraction (NPD) experiments together with high field magnetization, magnetostriction and specific heat measurements performed on single crystals. Reliable information at both microscopic and macroscopic levels is provided about the significant change of the double umbrella structure observed in the NPD results near 54 K. The positions of the observed maxima at 55-65 K in the paraprocess magnetic susceptibility along the three mean directions and paraprocess of the forced magnetostriction along the easy axis of magnetization 〈111〉 agree with the manifestations of the "low-temperature point" TB predicted by Belov at 58 K. However, the pronounced maximum at 57 K in the excess of specific heat in zero magnetic fields reveals that the Schottky effect causes anomaly at temperature close the TB point. The results are discussed and compared with previous magnetic, magneto-optical and magnetodielectric reports.

Nonlinear spin conductance of yttrium iron garnet thin films driven by large spin-orbit torque

NASA Astrophysics Data System (ADS)

Thiery, N.; Draveny, A.; Naletov, V. V.; Vila, L.; Attané, J. P.; Beigné, C.; de Loubens, G.; Viret, M.; Beaulieu, N.; Ben Youssef, J.; Demidov, V. E.; Demokritov, S. O.; Slavin, A. N.; Tiberkevich, V. S.; Anane, A.; Bortolotti, P.; Cros, V.; Klein, O.

2018-02-01

We report high power spin transfer studies in open magnetic geometries by measuring the spin conductance between two nearby Pt wires deposited on top of an epitaxial yttrium iron garnet thin film. Spin transport is provided by propagating spin waves that are generated and detected by direct and inverse spin Hall effects. We observe a crossover in spin conductance from a linear transport dominated by exchange magnons (low current regime) to a nonlinear transport dominated by magnetostatic magnons (high current regime). The latter are low-damping magnetic excitations, located near the spectral bottom of the magnon manifold, with a sensitivity to the applied magnetic field. This picture is supported by microfocus Brillouin light-scattering spectroscopy. Our findings could be used for the development of controllable spin conductors by variation of relatively weak magnetic fields.

Thermal Conductivity of a Nanoscale Yttrium Iron Garnet Thin-Film Prepared by the Sol-Gel Process

PubMed Central

2017-01-01

The thermal conductivity of a nanoscale yttrium iron garnet (Y3Fe5O12, YIG) thin-film prepared by a sol-gel method was evaluated using the ultrafast pump-probe technique in the present study. The thermoreflectance change on the surface of a 250 nm thick YIG film, induced by the irradiation of femtosecond laser pulses, was measured, and curve fitting of a numerical solution for the transient heat conduction equation to the experimental data was performed using the finite difference method in order to extract the thermal property. Results show that the film’s thermal conductivity is 22–83% higher than the properties of bulk YIG materials prepared by different fabrication techniques, reflecting the microstructural characteristics and quality of the film. PMID:28858249

Spin valve effect of the interfacial spin accumulation in yttrium iron garnet/platinum bilayers

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

Jin, Lichuan; Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716; Zhang, Dainan

2014-09-29

We report the spin valve effect in yttrium iron garnet/platinum (YIG/Pt) bilayers. The spin Hall effect (SHE) generates spin accumulation at the YIG/Pt interface and can be opened/closed by magnetization switching in the electrical insulator YIG. The interfacial spin accumulation was measured in both YIG/Pt and YIG/Cu/Pt structures using a planar Hall configuration. The spin valve effect remained, even after a 2 nm thick Cu layer was inserted between the YIG and Pt layers, which aimed to exclude the induced magnetization at the YIG/Pt interface. The transverse Hall voltage and switching field were dependent on the applied charge current density. Themore » origin of this behavior can be explained by the SHE induced torque exerted on the domain wall, caused by the transfer of the spin angular momentum from the spin-polarized current to the YIG magnetic moment.« less

Shock wave compression of iron-silicate garnet.

NASA Technical Reports Server (NTRS)

Graham, E. K.; Ahrens, T. J.

1973-01-01

Shock wave compression data to over 650 kb are presented for single-crystal almandine garnet. The data indicate the initiation of a phase transformation near 200 kb. Total transition to the high-pressure polymorph occurs at approximately 300 kb. The elastic properties of the high-pressure phase are calculated from the metastable Hugoniot data by using the linear shock velocity-particle velocity relationships. The overall results obtained strongly suggest that upper mantle minerals are likely to occur in the ilmenite structure over a substantial part of the lower mantle.

Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers

PubMed Central

Li, Junxue; Xu, Yadong; Aldosary, Mohammed; Tang, Chi; Lin, Zhisheng; Zhang, Shufeng; Lake, Roger; Shi, Jing

2016-01-01

Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin–orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon. The transmitted signal scales linearly with the driving current without a threshold and follows the power-law Tn with n ranging from 1.5 to 2.5. Our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics. PMID:26932316

Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers.

PubMed

Li, Junxue; Xu, Yadong; Aldosary, Mohammed; Tang, Chi; Lin, Zhisheng; Zhang, Shufeng; Lake, Roger; Shi, Jing

2016-03-02

Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin-orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon. The transmitted signal scales linearly with the driving current without a threshold and follows the power-law T(n) with n ranging from 1.5 to 2.5. Our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics.

Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers

DOE PAGES

Li, Junxue; Xu, Yadong; Aldosary, Mohammed; ...

2016-03-02

Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin–orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon.more » The transmitted signal scales linearly with the driving current without a threshold and follows the power-law T n with n ranging from 1.5 to 2.5. Lastly, our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics.« less

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.

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.

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.

Study of RE-garnets using BPW method

NASA Astrophysics Data System (ADS)

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

1995-02-01

The magnetic susceptibility of rare-earth (Y and Lu) iron garnets is studied using a modified Bethe-Peierls-Weiss (BPW) approximation. The modifications enable us to incorporate the three exchange parameters Jad, Jaa and Jdd necessary to describe the systems. We get excellent fits to the experimental susceptibilities from which we determined the J-values. These also give excellent agreement with the spin wave dispersion relation constant D.

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.

Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin–orbit torque

PubMed Central

Collet, M.; de Milly, X.; d'Allivy Kelly, O.; Naletov, V. V.; Bernard, R.; Bortolotti, P.; Ben Youssef, J.; Demidov, V. E.; Demokritov, S. O.; Prieto, J. L.; Muñoz, M.; Cros, V.; Anane, A.; de Loubens, G.; Klein, O.

2016-01-01

In recent years, spin–orbit effects have been widely used to produce and detect spin currents in spintronic devices. The peculiar symmetry of the spin Hall effect allows creation of a spin accumulation at the interface between a metal with strong spin–orbit interaction and a magnetic insulator, which can lead to a net pure spin current flowing from the metal into the insulator. This spin current applies a torque on the magnetization, which can eventually be driven into steady motion. Tailoring this experiment on extended films has proven to be elusive, probably due to mode competition. This requires the reduction of both the thickness and lateral size to reach full damping compensation. Here we show clear evidence of coherent spin–orbit torque-induced auto-oscillation in micron-sized yttrium iron garnet discs of thickness 20 nm. Our results emphasize the key role of quasi-degenerate spin-wave modes, which increase the threshold current. PMID:26815737

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

High-efficiency control of spin-wave propagation in ultra-thin yttrium iron garnet by the spin-orbit torque

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

Evelt, M.; Demidov, V. E., E-mail: demidov@uni-muenster.de; Bessonov, V.

2016-04-25

We study experimentally with submicrometer spatial resolution the propagation of spin waves in microscopic waveguides based on the nanometer-thick yttrium iron garnet and Pt layers. We demonstrate that by using the spin-orbit torque, the propagation length of the spin waves in such systems can be increased by nearly a factor of 10, which corresponds to the increase in the spin-wave intensity at the output of a 10 μm long transmission line by three orders of magnitude. We also show that, in the regime, where the magnetic damping is completely compensated by the spin-orbit torque, the spin-wave amplification is suppressed by themore » nonlinear scattering of the coherent spin waves from current-induced excitations.« less

Morphology and magnetic characterisation of aluminium substituted yttrium-iron garnet nanoparticles prepared using sol gel technique.

PubMed

Yahya, Noorhana; Al Habashi, Ramadan Masoud; Koziol, Krzysztof; Borkowski, Rafal Dunin; Akhtar, Majid Niaz; Kashif, Muhammad; Hashim, Mansor

2011-03-01

Aluminum substituted yttrium iron garnet nano particles with compositional variation of Y(3.0-x) A1(x)Fe5O12, where x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 were prepared using sol gel technique. The X-ray diffraction results showed that the best garnet phase appeared when the sintering temperature was 800 degrees C. Nano-crystalline particles with high purity and sizes ranging from 20 to 100 nm were obtained. It was found that the aluminum substitution had resulted in a sharp fall of the d-spacing when x = 2, which we speculated is due to the preference of the aluminum atoms to the smaller tetrahedron and octahedron sites instead of the much larger dodecahedron site. High resolution transmission electron microscope (HRTEM) and electron diffraction (ED) patterns showed single crystal nanoparticles were obtained from this method. The magnetic measurement gave moderate values of initial permeability; the highest value of 5.3 was shown by sample Y3Fe5O12 at more than 100 MHz which was attributed to the morphology of the microstructure which appeared to be homogeneous. This had resulted in an easy movement of domain walls. The substitution of aluminum for yttrium is speculated to cause a cubic to rhombodedral structural change and had weakened the super-exchange interactions thus a fall of real permeability was observed. This might have created a strain in the sub-lattices and had subsequently caused a shift of resonance frequencies to more than 1.8 GHz when x > 0.5.

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.

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

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.

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.

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.

Reflection and Transmission Coefficient of Yttrium Iron Garnet Filled Polyvinylidene Fluoride Composite Using Rectangular Waveguide at Microwave Frequencies

PubMed Central

Soleimani, Hassan; Abbas, Zulkifly; Yahya, Noorhana; Shameli, Kamyar; Soleimani, Hojjatollah; Shabanzadeh, Parvaneh

2012-01-01

The sol-gel method was carried out to synthesize nanosized Yttrium Iron Garnet (YIG). The nanomaterials with ferrite structure were heat-treated at different temperatures from 500 to 1000 °C. The phase identification, morphology and functional groups of the prepared samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The YIG ferrite nanopowder was composited with polyvinylidene fluoride (PVDF) by a solution casting method. The magnitudes of reflection and transmission coefficients of PVDF/YIG containing 6, 10 and 13% YIG, respectively, were measured using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in X-band frequencies. The results indicate that the presence of YIG in polymer composites causes an increase in reflection coefficient and decrease in transmission coefficient of the polymer. PMID:22942718

Effects of Iron and Aluminum on Phase Boundaries at 600-800 km Depths

NASA Astrophysics Data System (ADS)

Shim, Sang-Heon; Ye, Yu; Prakapenka, Vitali; Meng, Yue

2014-05-01

High-resolution seismic studies have reported complex discontinuity structures at 600-800 km depths. However, the origin of the structures have not been well understood. In order to understand compositional effects, we have measured the post-spinel, post-garnet, and post-ilmenite phase boundaries in MgO-Al2O3-SiO2 (iron free) and CaO-MgO-Al2O3-SiO2-FeO (iron bearing) systems with pyrolitic oxide ratios. In-situ X-ray diffraction measurements were performed at 20-30 GPa and 1500-2300 K in the laser-heated diamond-anvil cell at the GSECARS and HPCAT sectors of the Advanced Photon Source. We use the Pt and Au pressure scales for the iron-free and iron-bearing compositions, respectively. The Pt and Au scales were calibrated with respect to each other in separate experiments. In most experiments, Ar was cryogenically loaded in the sample chamber as a thermal insulation and pressure transmitting medium, except for a few experiments where a KCl medium was used. At temperatures above 1900 K, the post-garnet transition occurs at higher pressures than the post-spinel transition in both the iron-free and iron-bearing systems. At lower temperatures, while the post-ilmenite transition occurs at nearly same pressures as the post-spinel transition in the iron-bearing system, the post-ilmenite transition occurs at slightly higher pressure (1 GPa) than the post-spinel transitions in the iron-free system. In the iron-free system, akimotoite is stable to much higher temperature (2300 K) than previously thought. In the iron-bearing system, the stability of akimotoite is limited to 2050 K. Our data indicate that Al partitions more into akimotoite than garnet in the iron-free system, which is the opposite to what has been found in iron-bearing systems. The high Al content in akimotoite seems to be responsible for the high-temperature stability of akimotoite in the iron-free system. The Clapeyron slope of the post-garnet boundary is greater by a factor of 2.5 in the iron-bearing system

INTEGRATED AND FIBER OPTICS: Investigation of the refractive index profile of inhomogeneous iron garnet films containing bismuth

NASA Astrophysics Data System (ADS)

Arzamastseva, G. V.; Kravchenko, V. B.; Filimonova, L. M.

1989-02-01

The refractive index n of quasihomogeneous iron garnet films with the composition (YGdYb)3 - xBixFe5 - yAlyO12 increased considerably as a result of reduction in the growth temperature Tg. This was attributed mainly by an increase in x and a reduction in y. The dependences n(Tg) were used to select the conditions for growth of inhomogeneous (across the thickness) films and to predict the refractive index profile n(z), where z was measured from the free surface along the normal to the film. The spectra of optical modes were analyzed in the WKB approximation and this yielded the n(z) profiles for films with a refractive index n decreasing monotonically from the free surface and for films with the symmetric profile n(z) (buried waveguides). The n(z) profiles were compared with the distributions of the compensation temperature Tc(z), and of x(z) and y(z) across the thickness.

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.

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.

High-quality single-crystal thulium iron garnet films with perpendicular magnetic anisotropy by off-axis sputtering

NASA Astrophysics Data System (ADS)

Wu, C. N.; Tseng, C. C.; Lin, K. Y.; Cheng, C. K.; Yeh, S. L.; Fanchiang, Y. T.; Hong, M.; Kwo, J.

2018-05-01

High-quality single-crystal thulium iron garnet (TmIG) films of 10-30 nm thick were grown by off-axis sputtering at room temperature (RT) followed by post-annealing. X-ray photoelectron spectroscopy (XPS) was employed to determine the TmIG film composition to optimize the growth conditions, along with the aid of x-ray diffraction (XRD) structural analysis and atomic force microscope (AFM) for surface morphology. The optimized films exhibited perpendicular magnetic anisotropy (PMA) and the saturation magnetization at RT was ˜99 emu/cm3, close to the RT bulk value ˜110 emu/cm3 with a very low coercive field of ˜2.4 Oe. We extracted the H⊥ of 1734 Oe and the peak-to-peak linewidth ΔH of ferromagnetic resonance are only about 99 Oe, significantly lower than that of PLD grown TmIG film and bulk single crystals. The high-quality sputtered single-crystal TmIG films show great potential to be integrated with topological insulators or heavy metals with strong spin-orbit coupling for spintronic applications.

Stress induced modulation of magnetic domain diffraction of single crystalline yttrium iron garnet

NASA Astrophysics Data System (ADS)

Mito, Shinichiro; Yoshihara, Yuki; Takagi, Hiroyuki; Inoue, Mitsuteru

2018-05-01

Stress induced modulation of the diffraction angle and efficiency of the light reflected from a stripe-domain magnetic garnet was demonstrated. The spacing of the magnetic domain was changed using the inverse magnetostriction effect. The sample structure was a piezo actuator/Al reflection layer/magnetic garnet substrate. A diffraction angle between the 0th and 1st ordered light was changed from 9.12 deg. to 10.20 deg. This result indicates that the domain spacing was changed from 3.3 μm to 3.0 μm. The change of the diffraction angle was irreversible for the voltage. However, reversible, linear and continuous change of the diffraction efficiency was observed. These results could be applicable for a voltage-driven optical solid state light deflector with low power consumption and high switching speed.

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

Investigation of the unidirectional spin heat conveyer effect in a 200 nm thin Yttrium Iron Garnet film

NASA Astrophysics Data System (ADS)

Wid, Olga; Bauer, Jan; Müller, Alexander; Breitenstein, Otwin; Parkin, Stuart S. P.; Schmidt, Georg

2016-06-01

We have investigated the unidirectional spin wave heat conveyer effect in sub-micron thick yttrium iron garnet (YIG) films using lock-in thermography (LIT). Although the effect is small in thin layers this technique allows us to observe asymmetric heat transport by magnons which leads to asymmetric temperature profiles differing by several mK on both sides of the exciting antenna, respectively. Comparison of Damon-Eshbach and backward volume modes shows that the unidirectional heat flow is indeed due to non-reciprocal spin-waves. Because of the finite linewidth, small asymmetries can still be observed when only the uniform mode of ferromagnetic resonance is excited. The latter is of extreme importance for example when measuring the inverse spin-Hall effect because the temperature differences can result in thermovoltages at the contacts. Because of the non-reciprocity these thermovoltages reverse their sign with a reversal of the magnetic field which is typically deemed the signature of the inverse spin-Hall voltage.

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

Forward volume and surface magnetostatic modes in an yttrium iron garnet film for out-of-plane magnetic fields: Theory and experiment

NASA Astrophysics Data System (ADS)

Lim, Jinho; Bang, Wonbae; Trossman, Jonathan; Amanov, Dovran; Ketterson, John B.

2018-05-01

We present experimental and theoretical results on the propagation of magnetostatic spin waves in a film of yttrium iron garnet (YIG) for out-of-plane magnetic fields for which propagation in opposite directions is nonreciprocal in the presence of a metal layer. The plane studied is defined by the film normal n and n × k where k is the wave vector of the mode. Spin waves in this setting are classified as forward volume waves or surface waves and display non-reciprocity in the presence of an adjacent metal layer except for when H//n. The measurements are carried out in a transmission geometry, and a microwave mixer is used to measure the change of phase, and with it the evolution of wavevector, of the arriving spin wave with external magnetic field.

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

Structure-substitution limit correlation study on Cr{sup 3+} substituted polycrystalline yttrium iron garnet

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

Modi, K. B.; Saija, K. G.; Sharma, P. U.

2016-05-06

Polycrystalline samples of Cr{sup 3+} - substituted yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}) system with general chemical formula, Y{sub 3}Fe{sub 5-x}Cr{sub x}O{sub 12}, x = 0.0, 0.2, 0.4 and 0.6 were synthesized by double sintering ceramic technique and characterized by X-ray powder diffractometry. The Rietveld fitted X-ray diffraction patterns analysis revealed mono phase formation for x = 0.0 - 0.4 compositions while x = 0.6 composition possesses mixed phase character. The observed substitution limit has been discussed in the light of ionic size of substituent, electrostatic energy, electronic configuration and synthesis parameters. These observations strongly suggest that the electronicmore » configuration of Cr{sup 3+}, which is favorable to the formation of d2sp3 (octahedral) type bonds, must be important. In the case of Cr{sup 3+}, the substitution does not appear to proceed well for x much greater than 0.5, this limitation probably is a consequence of the strong preference of a smaller ion Cr{sup 3+}, for a larger octahedral site which quickly leads to a condition not comparable with the requirement of the structure. The distribution of cations, mean ionic radii and theoretical lattice constant values have been determined.« less

Yttrium Iron Garnet Thin Films with Very Low Damping Obtained by Recrystallization of Amorphous Material

PubMed Central

Hauser, Christoph; Richter, Tim; Homonnay, Nico; Eisenschmidt, Christian; Qaid, Mohammad; Deniz, Hakan; Hesse, Dietrich; Sawicki, Maciej; Ebbinghaus, Stefan G.; Schmidt, Georg

2016-01-01

We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG) by annealing in oxygen atmosphere. Our findings show that well below the melting temperature the material transforms into a fully epitaxial layer with exceptional quality, both structural and magnetic. In ferromagnetic resonance (FMR) ultra low damping and extremely narrow linewidth can be observed. For a 56 nm thick layer a damping constant of α = (6.15 ± 1.50) · 10−5 is found and the linewidth at 9.6 GHz is as small as 1.30 ± 0.05 Oe which are the lowest values for PLD grown thin films reported so far. Even for a 20 nm thick layer a damping constant of α = (7.35 ± 1.40) · 10−5 is found which is the lowest value for ultrathin films published so far. The FMR linewidth in this case is 3.49 ± 0.10 Oe at 9.6 GHz. Our results not only present a method of depositing thin film YIG of unprecedented quality but also open up new options for the fabrication of thin film complex oxides or even other crystalline materials. PMID:26860816

Observation of electromagnetically induced transparency and absorption in Yttrium Iron Garnet loaded split ring resonator

NASA Astrophysics Data System (ADS)

Tay, Z. J.; Soh, W. T.; Ong, C. K.

2018-04-01

In this paper, we propose a new method of controlling microwave transmission from Electromagnetically Induced Absorption (EIA) to Electromagnetically Induced Transparency (EIT). EIA describes the state where the system strongly absorbs microwaves, whereas EIT describes the state in which the system is transparent to microwaves. Control is achieved via coupling of the 3 GHz photon mode of a metamaterial Split Ring Resonator (SRR) to the spin wave magnon modes of a Yttrium Iron Garnet (YIG) bulk. The system is described by a 2-body interaction matrix with an additional fitting parameter τ which takes into account the fact that the microstrip feed line could excite the SRR as well as the YIG. The parameter τ reveals the effect of geometry and shielding on the coupling behaviour and gives rise to unique physics. In low τ (τ ⩽ 2) configurations, only EIT is reported. However, in high τ (τ ≈ 10) configurations, EIA is reported. Furthermore, we report that the system can be easily changed from a low τ to high τ configuration by shielding the SRR from the microstrip with a thin metal piece. Varying the τ parameter through shielding is thus proposed as a new method of controlling the microwave transmission at the coupling region.

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.

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.

Phase stable rare earth garnets

DOEpatents

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

2013-06-11

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

Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

NASA Astrophysics Data System (ADS)

Maendl, Stefan; Grundler, Dirk

2018-05-01

We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

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.

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.

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.

Spin Seebeck effect and ballistic transport of quasi-acoustic magnons in room-temperature yttrium iron garnet films

NASA Astrophysics Data System (ADS)

Noack, Timo B.; Musiienko-Shmarova, Halyna Yu; Langner, Thomas; Heussner, Frank; Lauer, Viktor; Heinz, Björn; Bozhko, Dmytro A.; Vasyuchka, Vitaliy I.; Pomyalov, Anna; L’vov, Victor S.; Hillebrands, Burkard; Serga, Alexander A.

2018-06-01

We studied the transient behavior of the spin current generated by the longitudinal spin Seebeck effect (LSSE) in a set of platinum-coated yttrium iron garnet (YIG) films of different thicknesses. The LSSE was induced by means of pulsed microwave heating of the Pt layer and the spin currents were measured electrically using the inverse spin Hall effect in the same layer. We demonstrate that the time evolution of the LSSE is determined by the evolution of the thermal gradient triggering the flux of thermal magnons in the vicinity of the YIG/Pt interface. These magnons move ballistically within the YIG film with a constant group velocity, while their number decays exponentially within an effective propagation length. The ballistic flight of the magnons with energies above 20 K is a result of their almost linear dispersion law, similar to that of acoustic phonons. By fitting the time-dependent LSSE signal for different film thicknesses varying by almost an order of magnitude, we found that the effective propagation length is practically independent of the YIG film thickness. We consider this fact as strong support of a ballistic transport scenario—the ballistic propagation of quasi-acoustic magnons in room temperature YIG.

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

Nonlocal magnon spin transport in yttrium iron garnet with tantalum and platinum spin injection/detection electrodes

NASA Astrophysics Data System (ADS)

Liu, J.; Cornelissen, L. J.; Shan, J.; van Wees, B. J.; Kuschel, T.

2018-06-01

We study the magnon spin transport in the magnetic insulator yttrium iron garnet (YIG) in a nonlocal experiment and compare the magnon spin excitation and detection for the heavy metal paramagnetic electrodes platinum (Pt|YIG|Pt) and tantalum (Ta|YIG|Ta). The electrical injection and detection processes rely on the (inverse) spin Hall effect in the heavy metals and the conversion between the electron spin and magnon spin at the heavy metal|YIG interface. Pt and Ta possess opposite signs of the spin Hall angle. Furthermore, their heterostructures with YIG have different interface properties, i.e. spin mixing conductances. By varying the distance between injector and detector, the magnon spin transport is studied. Using a circuit model based on the diffusion-relaxation transport theory, a similar magnon relaxation length of  ∼10 μm was extracted from both Pt and Ta devices. By changing the injector and detector material from Pt to Ta, the influence of interface properties on the magnon spin transport has been observed. For Ta devices on YIG the spin mixing conductance is reduced compared with Pt devices, which is quantitatively consistent when comparing the dependence of the nonlocal signal on the injector-detector distance with the prediction from the circuit model.

Sound velocities of skiagite-iron-majorite solid solution to 56 GPa probed by nuclear inelastic scattering

NASA Astrophysics Data System (ADS)

Vasiukov, D. M.; Ismailova, L.; Kupenko, I.; Cerantola, V.; Sinmyo, R.; Glazyrin, K.; McCammon, C.; Chumakov, A. I.; Dubrovinsky, L.; Dubrovinskaia, N.

2018-05-01

High-pressure experimental data on sound velocities of garnets are used for interpretation of seismological data related to the Earth's upper mantle and the mantle transition zone. We have carried out a Nuclear Inelastic Scattering study of iron-silicate garnet with skiagite (77 mol%)-iron-majorite composition in a diamond anvil cell up to 56 GPa at room temperature. The determined sound velocities are considerably lower than sound velocities of a number of silicate garnet end-members, such as grossular, pyrope, Mg-majorite, andradite, and almandine. The obtained sound velocities have the following pressure dependencies: V p [km/s] = 7.43(9) + 0.039(4) × P [GPa] and V s [km/s] = 3.56(12) + 0.012(6) × P [GPa]. We estimated sound velocities of pure skiagite and khoharite, and conclude that the presence of the iron-majorite component in skiagite strongly decreases V s . We analysed the influence of Fe3+ on sound velocities of garnet solid solution relevant to the mantle transition zone and consider that it may reduce sound velocities up to 1% relative to compositions with only Fe2+ in the cubic site.

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

Garnet pyroxenite from Nilgiri Block, southern India: Vestiges of a Neoarchean volcanic arc

NASA Astrophysics Data System (ADS)

Samuel, Vinod O.; Kwon, Sanghoon; Santosh, M.; Sajeev, K.

2018-06-01

Southern peninsular India preserves records of Late Neoarchean-Early Paleoproterozoic continental building and cratonization. A transect from the Paleoarchean Dharwar Craton to the Neoarchean arc magmatic complex in the Nilgiri Block across the intervening Moyar Suture Zone reveals an arc-accretionary complex composed of banded iron formation (BIF), amphibolite, metatuff, garnet-kyanite schist, metagabbro, pyroxenite and charnockite. Here we investigate the petrology, geochronology and petrogenesis of the pyroxenite and garnet-clinopyroxenite. The pyroxenite is mainly composed of orthopyroxene and clinopyroxene with local domains/pockets enriched in a clinopyroxene-garnet assemblage. Thermobarometric calculations and phase equilibria modeling suggest that the orthopyroxene- and clinopyroxene-rich domains formed at 900-1000 °C, 1-1.2 GPa whereas the garnet- and clinopyroxene-rich domains record higher pressure of about 1.8-2 GPa at similar temperature conditions (900-1000 °C). Zircon U-Pb SHRIMP dating show weighted mean 207Pb-206Pb age of 2532 ± 22 Ma, with metamorphic overgrowth at 2520 ± 27 Ma and 2478 ± 27 Ma. We propose a tectonic model involving decoupling and break-off of the oceanic plate along the southern flanks of the Dharwar Craton, which initiated oceanic plate subduction. Slab melting eventually built the Nilgiri volcanic arc on top of the over-riding plate along the flanks of the Dharwar Craton. Our study supports an active plate tectonic regime at the end of the Archean Era, aiding in the growth of paleo-continents and their assembly into stable cratons.

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.

Measurements of long-wavelength spin waves for the magnetic field in the Damon-Eshbach, backward-volume and forward-volume geometries of an yttrium iron garnet film

DOE PAGES

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; ...

2018-03-23

In this paper, we report systematic measurements of the dispersion of long wavelength spin waves for a wide range of wave vectors for the magnetic field along the three principal directions defining the forward volume, backward volume and Damon-Eshbach modes of a 9.72 μm thick film of an yttrium iron garnet obtained using lithographically patterned, multi-element, spatially resonant, antennas. Overall good agreement is found between the experimental data for the backward volume and Damon-Eshbach modes and the magnetostatic theory of Damon and Eshbach. Also, good agreement is found between the experimental data for the forward volume mode and the theorymore » of Damon and van de Vaart.« less

Measurements of long-wavelength spin waves for the magnetic field in the Damon-Eshbach, backward-volume and forward-volume geometries of an yttrium iron garnet film

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

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan

In this paper, we report systematic measurements of the dispersion of long wavelength spin waves for a wide range of wave vectors for the magnetic field along the three principal directions defining the forward volume, backward volume and Damon-Eshbach modes of a 9.72 μm thick film of an yttrium iron garnet obtained using lithographically patterned, multi-element, spatially resonant, antennas. Overall good agreement is found between the experimental data for the backward volume and Damon-Eshbach modes and the magnetostatic theory of Damon and Eshbach. Also, good agreement is found between the experimental data for the forward volume mode and the theorymore » of Damon and van de Vaart.« less

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

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

Experimental Constraints on the Partitioning and Valence of V and Cr in Garnet and Coexisting Glass

NASA Technical Reports Server (NTRS)

Righter, K.; Sutton, S.; Berthet, S.; Newville, M.

2008-01-01

A series of experiments with garnet and coexisting melt have been carried out across a range of oxygen fugacities (near hematite-magnetite (HM) to below the iron-wustite (IW) buffers) at 1.7 GPa to study the partitioning and valence of Cr and V in both phases. Experiments were carried out in a non end loaded piston cylinder apparatus, and the run products were analyzed with electron microprobe and xray absorption near edge structure (XANES) analysis at beamline 13-ID at the Advanced Photon Source of Argonne National Lab. The valence of vanadium and chromium were determined using the position and intensity of the Ka pre-edge peaks, calibrated on a series of Cr and Vbearing standard glasses. This technique has been applied to V and Cr in glasses and V in spinels previously, and in these isotropic phases there are no orientational effects on the XANES spectra (Righter et al., 2006, Amer. Mineral. 91, 1643-1656). We also now demonstrate this to be true for V and Cr in garnet. Also, previous work has shown that V has a higher valence in the glass (or melt) than in the coexisting spinel. This is also true for V in garnet-glass pairs in this study. Vanadium valence in garnets varies from 2.7 below the IW buffer to 3.7 near HM, and for coexisting glass it varies from 3.2 to 4.3. Vanadium valence measured in some natural garnets from mantle localities indicates V in the more reduced range at 2.5. Comparisons will be made between fO2 estimated from V valence and other methods for garnet-bearing mantle samples. In contrast, Cr valence measured in garnet and coexisting glass for all experimental and natural samples is 2.9- 3.0, suggesting that the valence of Cr does not vary within either phase across a large fO2 range. These results demonstrate that while V varies from 2+ to 3+ to 4+ in garnet-melt systems, Cr does not, and this will ultimately affect the partitioning behavior of these two elements in natural systems. Garnet/melt D(Cr) are between 12 and 17 across this range

Strong excitation of surface and bulk spin waves in yttrium iron garnet placed in a split ring resonator

NASA Astrophysics Data System (ADS)

Tay, Z. J.; Soh, W. T.; Ong, C. K.

2018-02-01

This paper presents an experimental study of the inverse spin Hall effect (ISHE) in a bilayer consisting of a yttrium iron garnet (YIG) and platinum (Pt) loaded on a metamaterial split ring resonator (SRR). The system is excited by a microstrip feed line which generates both surface and bulk spin waves in the YIG. The spin waves subsequently undergo spin pumping from the YIG film to an adjacent Pt layer, and is converted into a charge current via the ISHE. It is found that the presence of the SRR causes a significant enhancement of the mangetic field near the resonance frequency of the SRR, resulting in a significant increase in the ISHE signal. Furthermore, the type of spin wave generated in the system can be controlled by changing the external applied magnetic field angle (θH ). When the external applied magnetic field is near parallel to the microstrip line (θH = 0 ), magnetostatic surface spin waves are predominantly excited. On the other hand, when the external applied magnetic field is perpendicular to the microstrip line (θH = π/2 ), backward volume magnetostatic spin waves are predominantly excited. Hence, it can be seen that the SRR structure is a promising method of achieving spin-charge conversion, which has many advantages over a coaxial probe.

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.

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.

Coexisting cummingtonite and aluminous hornblende from garnet amphibolite, Boehls Butte area, Idaho, USA

USGS Publications Warehouse

Hietanen, A.

1973-01-01

Electron microprobe analyses of green hornblende and coexisting cummingtonite from garnet amphibolite show identical Fe/Mg ratios ( = 0.9). Cummingtonite is iron-magnesium silicate with very little calcium and aluminum and practically no alkalies. In contrast, the hornblende has 1.5 tetrahedral Al, 0.9 octahedral Al and a considerable amount of Ca and alkalies. Comparison with the hornblendes from the Sierra Nevada shows a higher relative amount of tschemakite molecule in the hornblendes from Idaho where pressures during the recrystallization were higher. ?? 1973.

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.

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.

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.

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.

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

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.

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

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

Electric field tuning of magnetism in heterostructure of yttrium iron garnet film/lead magnesium niobate-lead zirconate titanate ceramic

NASA Astrophysics Data System (ADS)

Lian, Jianyun; Ponchel, Freddy; Tiercelin, Nicolas; Chen, Ying; Rémiens, Denis; Lasri, Tuami; Wang, Genshui; Pernod, Philippe; Zhang, Wenbin; Dong, Xianlin

2018-04-01

In this paper, the converse magnetoelectric (CME) effect by electric field tuning of magnetization in an original heterostructure composed of a polycrystalline yttrium iron garnet (YIG) film and a lead magnesium niobate-lead zirconate titanate (PMN-PZT) ceramic is presented. The magnetic performances of the YIG films with different thicknesses under a DC electric field applied to the PMN-PZT ceramics and a bias magnetic field are investigated. All the magnetization-electric field curves are found to be in good agreement with the butterfly like strain curve of the PMN-PZT ceramic. Both the sharp deformation of about 2.5‰ of PMN-PZT and the easy magnetization switching of YIG are proposed to be the reasons for the strongest CME interaction in the composite at the small electric coercive field of PMN-PZT (4.1 kV/cm) and the small magnetic coercive field of YIG (20 Oe) where the magnetic susceptibility reaches its maximum value. A remarkable CME coefficient of 3.1 × 10-7 s/m is obtained in the system with a 600 nm-thick YIG film. This heterostructure combining multiferroics and partially magnetized ferrite concepts is able to operate under a small or even in the absence of an external bias magnetic field and is more compact and power efficient than the traditional magnetoelectric devices.

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.

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.

Native iron in the continental lower crust - Petrological and geophysical implications

NASA Technical Reports Server (NTRS)

Haggerty, S. E.; Toft, P. B.

1985-01-01

Lower crustal granulite xenoliths recovered from a kimberlite pipe in western Africa contain native iron (Fe) as a decomposition product of garnet and ilmenite. Magnetic measurements show that less than 0.1 percent (by volume) of iron metal is present. Data from geothermometry and oxygen geobarometry indicate that the oxide and metal phases equilibrated between iron-wuestite and magnetite-wuestite buffers, which may represent the oxidation state of the continental lower crust, and the depleted lithospheric upper mantle. Ferromagnetic native iron could be stable to a depth of about 95 kilometers and should be considered in the interpretation of long-wavelength static magnetic anomalies.

Native iron in the continental lower crust - Petrological and geophysical implications

NASA Astrophysics Data System (ADS)

Haggerty, S. E.; Toft, P. B.

1985-08-01

Lower crustal granulite xenoliths recovered from a kimberlite pipe in western Africa contain native iron (Fe) as a decomposition product of garnet and ilmenite. Magnetic measurements show that less than 0.1 percent (by volume) of iron metal is present. Data from geothermometry and oxygen geobarometry indicate that the oxide and metal phases equilibrated between iron-wuestite and magnetite-wuestite buffers, which may represent the oxidation state of the continental lower crust, and the depleted lithospheric upper mantle. Ferromagnetic native iron could be stable to a depth of about 95 kilometers and should be considered in the interpretation of long-wavelength static magnetic anomalies.

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.

Canted ferrimagnetism in Ca2+Sc3+ substituted yttrium-iron-garnet

NASA Astrophysics Data System (ADS)

Pardavi-Horváth, M.; Thavendrarajah, A.; Wigen, P. E.; DeGasperis, P.

1988-11-01

The temperature dependence of the magnetization of Y3-y-zCayLuzFe5-xScxO12 (0.6≤x≤1.2, 0≤y≤0.3, 0≤z≤0.9) epitaxial garnet films was measured from 4.2 K up to the Curie temperature. For x=0.7 and T≥50 K, 4πMs is enhanced by about 10% compared to the magnetization of Sc0.7 YIG. At T<50 K, a reduction of the magnetization, increasing with increasing substitution, was observed for all the measured samples. Agreement between the experimental results and molecular field models was obtained by taking into account the canting of the unsubstituted sublattice, the presence of charge compensating Fe4+ ions, a low-temperature ordering of Fe3+ ions with less than two magnetic nearest neighbors, and assuming a lattice parameter-dependent exchange interaction ratio with d(Jdd/Jad)/da =28 nm.-1 For x=1.2 and T<10 K the magnetization can be influenced by cooling through the Curie point in a magnetic field.

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

Gadolinium Scandium Gallium Garnet (GSGG) as a Solid-State Laser Host

DTIC Science & Technology

1987-07-01

o*SATI CODSi1.SBEC EM (otne nrvrs fnceayad dniy nb)k ubr ~~~~~~~~ Gadolinium Scandium Gallium Garnet (GSGG)asaSldtteLerHt 17. ABSTRACT 6.SUJCTTEM...certain other garnet materials for replacement. It also addresses the solid-state laser host material Gadolinium Scandium Gal- lium Garnet (GSGG) and its...by neodymium-doped yttrium aluminum garnet (Nd:YAG) or other mate- rials for most applications. In the years after the invention of the ruby laser, in

Ce3+-Doped garnet phosphors: composition modification, luminescence properties and applications.

PubMed

Xia, Zhiguo; Meijerink, Andries

2017-01-03

Garnets have the general formula of A 3 B 2 C 3 O 12 and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are closely related to the structure and composition. In particular, Ce 3+ -doped garnet phosphors have a long history and are widely applied, ranging from flying spot cameras, lasers and phosphors in fluorescent tubes to more recent applications in white light LEDs, as afterglow materials and scintillators for medical imaging. Garnet phosphors are unique in their tunability of the luminescence properties through variations in the {A}, [B] and (C) cation sublattice. The flexibility in phosphor composition and the tunable luminescence properties rely on design and synthesis strategies for new garnet compositions with tailor-made luminescence properties. It is the aim of this review to discuss the variation in luminescence properties of Ce 3+ -doped garnet materials in relation to the applications. This review will provide insight into the relation between crystal chemistry and luminescence for the important class of Ce 3+ -doped garnet phosphors. It will summarize previous research on the structural design and optical properties of garnet phosphors and also discuss future research opportunities in this field.

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.

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.

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

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

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

Charge-coupled Substituted Garnets (Y3-xCa0.5xM0.5x)Fe5O12 (M = Ce, Th): Structure and Stability as Crystalline Nuclear Waste Forms

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

Guo, Xiaofeng; Kukkadapu, Ravi K.; Lanzirotti, Anthony

2015-04-20

The garnet structure has been proposed as a potential crystalline nuclear waste form for accommodation of actinide elements, especially uranium (U). In this study, yttrium iron garnet (YIG) as a model garnet host was studied for the incorporation of U analogs, cerium (Ce), and thorium (Th), incorporated by a charge-coupled substitution with calci-um (Ca) for yttrium (Y) in YIG, namely 2Y3+ = Ca2+ + M4+, where M4+ = Ce4+ or Th4+. Single phase garnets Y3-xCa0.5xM0.5xFe5O12, synthesized by the citrate-nitrate combustion method, were obtained up to x = 0.7. Ce was confirmed to be tetravalent by X-ray absorption spectroscopy and X-raymore » photoelectron spectroscopy. X-ray diffraction and 57Fe-Mössbauer spectroscopy indicated that the samples are single phase, M4+ and Ca2+ cations are restricted to the c-site, the nature of M4+ has only a minor effect on the structure, and the local environments of both the tetrahedral and octahedral Fe3+ are systematically affected by the extent of substitution, especially on the tetrahedral sublattice. The charge coupled substitution has advantages in incorporating Ce/Th and in stabilizing the substituted phases, compared to a single substitution strategy. Enthalpies of formation of garnets were obtained by high temperature oxide melt solution calorimetry, and the enthalpies of substitution of Ce and Th were determined. The thermodynamic analysis demonstrates that the substituted garnets are entropically rather than energetically stabilized. This suggests that such garnets may form and persist in repositories at high temperature but might decompose near room temperature. These structural and thermodynamic findings shed light on possible incorporation of U in this garnet system.« less

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

Nanometer-Thick Yttrium Iron Garnet Film Development and Spintronics-Related Study

NASA Astrophysics Data System (ADS)

Chang, Houchen

In the last decade, there has been a considerable interest in using yttrium iron garnet (Y3Fe5O12, YIG) materials for magnetic insulator-based spintronics studies. This interest derives from the fact that YIG materials have very low intrinsic damping. The development of YIG-based spintronics demands YIG films that have a thickness in the nanometer (nm) range and at the same time exhibit low damping similar to single-crystal YIG bulk materials. This dissertation reports comprehensive experimental studies on nm-thick YIG films by magnetron sputtering techniques. Optimization of sputtering control parameters and post-deposition annealing processes are discussed in detail. The feasibility of low-damping YIG nm-thick film growth via sputtering is demonstrated. A 22.3-nm-thick YIG film, for example, shows a Gilbert damping constant of less than 1.0 x 10-4. The demonstration is of great technological significance because sputtering is a thin film growth technique most widely used in industry. The spin Seebeck effect (SSE) refers to the generation of spin voltage in a ferromagnet (FM) due to a temperature gradient. The spin voltage can produce a pure spin current into a normal metal (NM) that is in contact with the FM. Various theoretical models have been proposed to interpret the SSE, although a complete understanding of the effect has not been realized yet. In this dissertation the study of the role of damping on the SSE in YIG thin films is conducted for the first time. With the thin film development method mentioned in the last paragraph, a series of YIG thin films showing very similar structural and static magnetic properties but rather different Gilbert damping values were prepared. A Pt capping layer was grown on each YIG film to probe the strength of the SSE. The experimental data show that the YIG films with a smaller intrinsic Gilbert damping shows a stronger SSE. The majority of the previous studies on YIG spintronics utilized YIG films that were grown on single

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.

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

Charge-coupled substituted garnets (Y 3–x Ca 0.5x M 0.5x )Fe₅O₁₂ (M = Ce, Th): Structure and stability as crystalline nuclear waste forms

DOE PAGES

Guo, Xiaofeng; Kukkadapu, Ravi K.; Lanzirotti, Antonio; ...

2015-04-20

The garnet structure has been proposed as a potential crystalline nuclear waste form for accommodation of actinide elements, especially uranium (U). In this study, yttrium iron garnet (YIG) as a model garnet host was studied for the incorporation of U analogs, cerium (Ce) and thorium (Th), incorporated by a charge-coupled substitution with calcium (Ca) for yttrium (Y) in YIG, namely, 2Y³⁺ = Ca²⁺ + M⁴⁺, where M⁴⁺ = Ce⁴⁺ or Th⁴⁺. Single-phase garnets Y 3–xCa 0.5xM 0.5xFe₅O₁₂ (x = 0.1–0.7) were synthesized by the citrate–nitrate combustion method. Ce was confirmed to be tetravalent by X-ray absorption spectroscopy and X-ray photoelectronmore » spectroscopy. X-ray diffraction and ⁵⁷Fe–Mössbauer spectroscopy indicated that M⁴⁺ and Ca²⁺ cations are restricted to the c site, and the local environments of both the tetrahedral and the octahedral Fe³⁺ are systematically affected by the extent of substitution. The charge-coupled substitution has advantages in incorporating Ce/Th and in stabilizing the substituted phases compared to a single substitution strategy. Enthalpies of formation of garnets were obtained by high-temperature oxide melt solution calorimetry, and the enthalpies of substitution of Ce and Th were determined. The thermodynamic analysis demonstrates that the substituted garnets are entropically rather than energetically stabilized. This suggests that such garnets may form and persist in repositories at high temperature but might decompose near room temperature.« less

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.

Molecular field coefficients and cation distribution of substituted yttrium iron garnets

NASA Astrophysics Data System (ADS)

Röschmann, P.; Hansen, P.

1981-10-01

The saturation magnetization Ms(T) of Ga, Al, Sc, and CaVBi substituted Y3Fe5O12 (YIG) single crystals and of polycrystalline Ca/Ge and Ca/Ti substituted YIG has been investigated for 4.2 K ⩽T⩽TC. The samples were repeatedly annealed and quenched at different equilibrium temperatures 773 K⩽Te ⩽1523 K. The attained site exchange of Fe and the substituents between the a and d sites resulted in considerable changes of Ms(T). From a fit of the Néel molecular field theory to the Ms(T) data the dependence of the magnetic moments at T = 0 K and of the molecular field coefficients on the amount of nonmagnetic substitutions on the a and d sites were determined. It turned out that ion-specific sets of equations are required accounting for the ''particular ion effect'' of different cation species. The cation distributions inferred from the magnetic data have been analyzed along with a thermodynamic equilibrium model. The derived site stabilizing energies for the mixed Fe-Ga and Fe-Al garnets agree well with recently reported data. New results are presented for the site stabilizing energies in Ca/Ge:YIG and for the substituents Sc and Ti with octahedral site preference.

Spatial and size distributions of garnets grown in a pseudotachylyte generated during a lower crust earthquake

NASA Astrophysics Data System (ADS)

Clerc, Adriane; Renard, François; Austrheim, Håkon; Jamtveit, Bjørn

2018-05-01

In the Bergen Arc, western Norway, rocks exhumed from the lower crust record earthquakes that formed during the Caledonian collision. These earthquakes occurred at about 30-50 km depth under granulite or amphibolite facies metamorphic conditions. Coseismic frictional heating produced pseudotachylytes in this area. We describe pseudotachylytes using field data to infer earthquake magnitude (M ≥ 6.6), low dynamic friction during rupture propagation (μd < 0.1) and laboratory analyses to infer fast crystallization of microlites in the pseudotachylyte, within seconds of the earthquake arrest. High resolution 3D X-ray microtomography imaging reveals the microstructure of a pseudotachylyte sample, including numerous garnets and their corona of plagioclase that we infer have crystallized in the pseudotachylyte. These garnets 1) have dendritic shapes and are surrounded by plagioclase coronae almost fully depleted in iron, 2) have a log-normal volume distribution, 3) increase in volume with increasing distance away from the pseudotachylyte-host rock boundary, and 4) decrease in number with increasing distance away from the pseudotachylyte -host rock boundary. These characteristics indicate fast mineral growth, likely within seconds. We propose that these new quantitative criteria may assist in the unambiguous identification of pseudotachylytes in the field.

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.

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.

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

Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Pal, AnnaMarie T.; 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 presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

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.

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--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/).

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

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.

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

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.

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

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

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.

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

A Calorimetric Study of Almandine: Are the Thermodynamic Properties of the End-Member Aluminosilicate Garnets Finally Known Quantitatively?

NASA Astrophysics Data System (ADS)

Dachs, E.; Geiger, C. A.; Benisek, A.

2012-12-01

The aluminosilicate garnets (E3Al2Si3O12 with E = Fe2+, Mn2+, Ca, Mg) form an important rock-forming mineral group. Much study has been directed toward determining their thermodynamic properties. The iron end-member almandine (Fe3Al2Si3O12) is a key phase in many petrologic investigations. As part of an ongoing calorimetric and thermodynamic study of the aluminosilicate garnets, the heat capacity of three synthetic well-characterized polycrystalline almandine garnets and one natural almandine-rich single crystal was measured. The various garnets were characterized by optical microscopy, electron-microprobe analysis, X-ray powder diffraction and 57Fe Mössbauer spectroscopy. Heat capacity measurements were performed in the temperature range 3 to 300 K using relaxation calorimetry and between 282 and 764 K using DSC methods. From the former, So values between 336.7 ± 0.8 and 337.8 ± 0.8 J/molK are calculated for the different samples. The smaller value is considered the best So for end-member stoichiometric almandine, because it derives from the "best" Fe3+-free synthetic sample. The Cp behavior for almandine at T > 298 K is given by the polynomial (in J/molK): Cp = 649.06(±4) - 3837.57(±122)T-0.5 - 1.44682(±0.06)107T-2 + 1.94834(±0.09)109T-3, which is calculated using DSC data together with one published heat-content datum determined by transposed-drop calorimetry along with a new determination that gives H1181K - H302K = 415.0 ± 3.2 kJ/mole. Almandine shows a λ-type heat-capacity anomaly at low temperatures resulting from a paramagnetic-antiferromagnetic phase transition at about 9 K. The lattice heat capacity was calculated using the single-parameter phonon dispersion model of Komada and Westrum (1997), which allows the non-lattice heat capacity (Cex) behavior to be modelled. An analysis shows the presence of an electronic heat-capacity contribution (Cel - Schottky anomaly) around 17 K that is superimposed on a larger magnetic heat-capacity effect (Cmag

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

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.

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

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

Non-local detection of spin dynamics via spin rectification effect in yttrium iron garnet/SiO{sub 2}/NiFe trilayers near simultaneous ferromagnetic resonance

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

Soh, Wee Tee, E-mail: a0046479@u.nus.edu; Ong, C. K.; Peng, Bin

2015-08-15

The spin rectification effect (SRE), a phenomenon that generates dc voltages from ac microwave fields incident onto a conducting ferromagnet, has attracted widespread attention due to its high sensitivity to ferromagnetic resonance (FMR) as well as its relevance to spintronics. Here, we report the non-local detection of yttrium iron garnet (YIG) spin dynamics by measuring SRE voltages from an adjacent conducting NiFe layer up to 200 nm thick. In particular, we detect, within the NiFe layer, SRE voltages stemming from magnetostatic surface spin waves (MSSWs) of the adjacent bulk YIG which are excited by a shorted coaxial probe. These non-localmore » SRE voltages within the NiFe layer that originates from YIG MSSWs are present even in 200 nm-thick NiFe films with a 50 nm thick SiO{sub 2} spacer between NiFe and YIG, thus strongly ruling out the mechanism of spin-pumping induced inverse spin Hall effect in NiFe as the source of these voltages. This long-range influence of YIG dynamics is suggested to be mediated by dynamic fields generated from YIG spin precession near YIG/NiFe interface, which interacts with NiFe spins near the simultaneous resonance of both spins, to generate a non-local SRE voltage within the NiFe layer.« less

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.

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

NASA Astrophysics Data System (ADS)

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

2012-08-01

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

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.

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.

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

The switching of strong spin wave beams in patterned garnet films.

PubMed

Gieniusz, R; Gruszecki, P; Krawczyk, M; Guzowska, U; Stognij, A; Maziewski, A

2017-08-18

The application of spin waves in communication with information encoded in amplitude and phase could replace or enhance existing microelectronic and microwave devices with significantly decreased energy consumption. Spin waves (SW) are usually transported in a magnetic material shaped to act as a waveguide. However, the implementation of SW transport and switching in plane homogeneous magnetic films and running as a narrow beam with a small divergence angle still present a challenge. We propose a realization of a strong SW switchers based on a patterned yttrium iron garnet (YIG) film that could serve as a magnonic fundamental building block. Our concept relies on the creation of a narrow beam of relatively short-wavelength SW by effect of a total non-reflection, found to be tied to refraction on the decreasing internal magnetic field, near a line of antidots at YIG. Nonreciprocal SW excitation by a microstrip antenna is used for controlling the direction of the signal flow. We demonstrate unique features of the propagation of microwave-excited SW beams, provide insight into their physics and discuss their potential applications in high-frequency devices.

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

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

Combining Textural Techniques to Explore Effects of Diagenesis and Low-grade Metamorphism on Iron Mineralogy and Iron Speciation

NASA Astrophysics Data System (ADS)

Slotznick, S. P.; Webb, S.; Eiler, J. M.; Kirschvink, J. L.; Fischer, W. W.

2016-12-01

Iron chemistry and mineralogy in the sedimentary rocks provide a valuable tool for studying paleoenvironmental conditions due to the fact that iron atoms can take on either the +II or +III valence state under geological redox conditions. One method utilizing this redox chemistry is `iron speciation', a bulk chemical sequential extraction technique that maps proportions of iron species to redox conditions empirically calibrated from modern sediments. However, all Precambrian and many Phanerozoic rocks have experienced post-depositional processes; it is vital to explore their effects on iron mineralogy and speciation. We combined light and electron microscopy, magnetic microscopy, (synchrotron-based) microprobe x-ray spectroscopy, and rock magnetic measurements in order to deconvolve secondary overprints from primary phases and provide quantitative measurement of iron minerals. These techniques were applied to excellently-preserved shale and siltstone samples of the 1.4 Ga lower Belt Supergroup, Montana and Idaho, USA, spanning a metamorphic gradient from sub-biotite to garnet zone. Previously measured Silurian-Devonian shales, sandstones, and carbonates in Maine and Vermont, USA spanning from the chlorite to kyanite zone provided additional well-constrained, quantitative data for comparison and to extend our analysis. In all of the studied samples, pyrrhotite formation occurred at the sub-biotite or sub-chlorite zone. Pyrrhotite was interpreted to form from pyrite and/or other iron phases based on lithology; these reactions can affect the paleoredox proxy. Iron carbonates can also severely influence iron speciation results since they often form in anoxic pore fluids during diagenesis; textural analyses of the Belt Supergroup samples highlighted that iron-bearing carbonates were early diagenetic cements or later diagenetic overprints. The inclusion of iron from diagenetic minerals during iron speciation analyses will skew results by providing a view of pore

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.

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

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.

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.

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

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

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

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

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

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

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.

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.

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

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.

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) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

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

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

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

Magnetic Field Synthesis for Microwave Magnetics.

DTIC Science & Technology

1982-04-01

Uniform Fields Ferrimagnetic Films Yettrium Iron Garnet Magnetic Fields 2.ABSTRACT (Continue en reviresde It neceeectv .. d identify by block num~ber) he...Iron Garnet ," Proc. of IEEE, 64 794 (1976). 3. J. H. Collins and F. A. Pizzarello, "Propagating Magnetic Waves in Thick Films : A Complementary...E. Wigen, "Exchange-Dominated Surface Spin Waves in Thin Yttrium-Iron- Garnet Films ," Phys. Rev. B, 11 420 (1975). 36. C. Vittoria and J. H. Schelleng

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.

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.

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.

Kyanite-garnet gneisses of the Kåfjord Nappe - North Norwegian Caledonides: P-T conditions and monazite Th-U-Pb dating

NASA Astrophysics Data System (ADS)

Ziemniak, Grzegorz; Kośmińska, Karolina; Majka, Jarosław; Janák, Marian; Manecki, Maciej

2016-04-01

The Kåfjord Nappe is the part of the Skibotn Nappe Complex traditionally ascribed to the Upper Allochthon of the North Norwegian Caledonides. Pressure-temperature (P-T) conditions and metamorphic age of the Kåfjord Nappe are not well constrained, geochronological data are limited to a single Rb-Sr age of c. 440 Ma (Dangla et al. 1978). Metamorphic evolution of kyanite-garnet gneisses of the Kåfjord Nappe is presented here. The kyanite-garnet gneisses are associated with a few meters thick amphibolite lenses. The gneisses mainly consist of quartz, plagioclase, biotite, muscovite, garnet, kyanite, and rutile. Retrograde minerals are represented by sillimanite and chlorite. Garnet occurs as two textural types. Garnet-I forms euhedral porphyroblasts with multiple small inclusions. Profiles through garnet-I show chemical zonation in all components. The composition varies from Alm64-68Prp11-16Grs13-18Sps2-8 in the core to Alm68-70Prp17-18Grs10-13Sps1-3 in the rim. Garnet-II is subhedral to anhedral, its core is inclusion-rich, whereas rim contains only single inclusions. Chemical composition of garnet-II is similar to that of the garnet-I rim. P-T conditions have been estimated using the garnet-biotite-muscovite-plagioclase (GBPM) geothermobarometer (Holdaway, 2001; Wu, 2014). Calculated peak P-T metamorphic conditions are 610-625 °C and 7.6-8.2 kbar corresponding to the amphibolite facies conditions. Phase equilibrium modelling in the NCKFMMnASH system yields peak metamorphic conditions of c. 620 °C at 8 kbar. Growth conditions of garnet-I core modelled in the NCKFMMnASH system are c. 570 °C at 9.7 kbar. Chemical Th-U-total Pb monazite dating has been performed. Preliminary dating results from the kyanite-garnet gneiss of the Kåfjord Nappe yield an array of dates from 468 Ma to 404 Ma. There is a correlation between an increase of yttrium content and decrease of monazite single dates. Compositional maps confirm an increase of yttrium towards the rim of the

Origin of sapphirine- and garnet-bearing clinopyroxenite xenoliths entrained in the Jiande basalts, SE China

NASA Astrophysics Data System (ADS)

Xiao, Yan; Zhang, Hong-Fu; Liang, Zi; Su, Ben-Xun; Zhu, Bin; Sakyi, Patrick Asamoah

2018-04-01

We present petrological and geochemical data of sapphirine- and garnet-bearing clinopyroxenite xenoliths entrained in the Jiande Cenozoic basalts, SE China, to investigate their igneous and metamorphic history, and reconstruct of the thermal-tectonic evolution of the lithospheric mantle. These xenoliths have an unusual mineral association consisting of clinopyroxene + garnet/kelyphite + spinel (±sapphirine). Clinopyroxene has high Mg# (89-93) and displays convex-upward REE pattern. Garnet, partially to completely kelyphitized, is rich in pyrope end-member. It usually includes relics of spinel, suggesting that garnet was formed at the expense of spinel. The spinel has high MgO (20.8-22.9 wt%) and Al2O3 (64.8-67.9 wt%) contents. Sapphirine, forming a rim on spinel, has homogeneous SiO2 (14.5-14.9 wt%), Al2O3 (60.9-61.7 wt%) and MgO (19.7-20.1 wt%) contents, interpreted to be of metamorphic origin. The subsolidus reaction for the formation of sapphirine is as follows: spinel + garnet = sapphirine + clinopyroxene + orthopyroxene. Thus, the earliest mineral assemblage recorded in these xenoliths was spinel + clinopyroxene. The clinopyroxene in the Jiande clinopyroxenite xenoliths has Li abundances (1.04-1.63 ppm) similar to high-P mafic cumulate but much lower than those in crustal eclogite. In addition, the clinopyroxene and garnet do not show positive Eu anomalies. Therefore, the protolith of these three clinopyroxenite xenoliths was most likely a pyroxenite, originating as clinopyroxene + spinel cumulates from mafic melts percolating through the mantle. Many reaction textures such as formation of garnet and sapphirine were developed during decompression possibly coupled with cooling and melt percolation. During this process, the earlier composition of clinopyroxene and spinel also changed. The latest P-T conditions recorded in these xenoliths were at pressure of 8-10 kbar and temperatures of 1069-1094 °C. These observations imply that these rocks have been

U-Pb Geochronology of Grandite Skarn Garnet: Case Studies From Jurassic Skarns of California

NASA Astrophysics Data System (ADS)

Gevedon, M. L.; Seman, S.; Barnes, J.; Stockli, D. F.; Lackey, J. S.

2016-12-01

We present 3 case studies using a new method for U-Pb dating grossular-andradite (grandite) skarn garnet via LA-ICP-MS (Seman et al., in prep). Grandite is commonly rich in U, with high Fe3+ contents generally correlating with higher U concentrations. Micron-scale non-radiogenic Pb heterogeneities allow for regression of age data using Tera-Wasserberg concordia. Although others have dated accessory skarn minerals, garnet U-Pb ages are powerful because garnet grows early and is nearly ubiquitous in skarns, resists alteration, and provides a formation age independent of that of the causative pluton. The Darwin stock (Argus range, eastern CA) was likely a short-lived, single pulse of magmatism, genetically related to the Darwin skarn. A robust skarn garnet U-Pb age of 176.8 ± 1.3 Ma agrees well with the pluton U-Pb zircon age of 175 Ma (Chen and Moore, 1982). Furthermore, zircon separated from, and in textural equilibrium with, exoskarn garnetite yields a U-Pb age of 176.8 ± 1 Ma. Such agreement between plutonic and skarn zircon ages with a skarn garnet age in a geologically simple field area is the ideal scenario for establishing grandite U-Pb as a viable tool for directly dating skarns. The Black Rock skarn (BRS; eastern CA) is more complex: multiple plutons and ambiguous field relations complicate determination of a causative pluton. A skarn garnet U-Pb age of 172.0 ± 3 Ma confirms a middle Jurassic BRS formation age. Investigation of 4 local plutons yield zircon U-Pb ages of 222 ± 3 Ma, 213 ± 4 Ma, 207 ± 4 Ma and 176.2 ± 2 Ma. Comparison of the skarn garnet U-Pb and pluton ages suggest the BRS is genetically related to the youngest pluton, providing basis for further field and geochemical investigation. The Whitehorse skarn (WS; Mojave Desert, CA) lies in an important region for studying the changing tectono-magmatic regime of the Jurassic North American Cordillera; basin fill suggests a tectonically-controlled oscillating regional shoreline (Busby, 2012

Sm-Nd dating of multiple garnet growth events in an arc-continent collision zone, northwestern U.S. Cordillera

NASA Astrophysics Data System (ADS)

Getty, Stephen R.; Selverstone, Jane; Wernicke, Brian P.; Jacobsen, Stein B.; Aliberti, Elaine; Lux, Daniel R.

1993-03-01

Integrated petrologic and Sm-Nd isotopic studies in garnet amphibolites along the Salmon River suture zone, western Idaho, delineate two periods of amphibolite grade metamorphism separated by at least 16 million years. In one amphibolite, P-T studies indicate a single stage of metamorphism with final equilibration at ˜600°C and 8 9 kbar. The Sm-Nd isotopic compositions of plagioclase, apatite, hornblende, and garnet define a precise, 8-point isochron of 128±3 Ma (MSWD=1.2) interpreted as mineral growth at the metamorphic peak. A40Ar/39Ar age for this hornblende indicates cooling through ˜525°C at 119±2 Ma. In a nearby amphibolite, garnets with a two-stage growth history consist of inclusion-rich cores surrounded by discontinuous, inclusion-free overgrowths. Temporal constraints for core and overgrowth development were derived from Sm-Nd garnet — whole rock pairs in which the garnet fractions consist of varying proportions of inclusion-free to inclusion-bearing fragments. Three garnet fractions with apparent “ages” of 144, 141, and 136 Ma are thought to represent mixtures between late Jurassic (pre-144 Ma) inherited radiogenic components preserved within garnet cores and early Cretaceous (˜128 Ma) garnet overgrowths. These observations confirm the resilience of garnet to diffusive exchange of trace elements during polymetamorphism at amphibolite facies conditions. Our geochronologic results show that metamorphism of arc-derived rocks in western Idaho was episodic and significantly older than in arc rocks along the eastern margin of the Wrangellian Superterrane in British Columbia and Alaska. The pre-144 Ma event may be an expression of the late Jurassic amalgamation of marginal oceanic arc-related terranes (e.g., Olds Ferry, Baker, Wallowa) during the initial phases of their collision with North American rocks. Peak metamorphism at ˜128 Ma reflects tectonic burial along the leading edge of the Wallowa arc terrane during its final penetration and

Trace element zoning as a record of chemical disequilibrium during garnet growth

NASA Astrophysics Data System (ADS)

Chernoff, Carlotta B.; Carlson, William D.

1999-06-01

Trace element concentrations in pelitic garnets from the Picuris Range of New Mexico display precipitous changes coincident with abrupt variations in Ca concentration. These patterns probably arise from the transitory participation of different trace element enriched phases in the garnet forming reaction. Changes in the reactant and product assemblages occur at different times during the reaction history for crystals of different size, so they cannot be the result of any event affecting the entire rock, such as a change in pressure, temperature, or fluid composition. Instead, they reflect kinetic factors that cause Ca, Y, Yb, P, Ti, Sc, Zr, Hf, Sr, Na, and Li to fail to achieve chemical equilibrium during garnet growth. Caution is needed to avoid misinterpreting excursions in the concentration of these elements as event markers recording simultaneous rockwide changes in intensive parameters, when in fact they may record transient disequilibrium states that are local in scope, and not contemporaneous.

Compositional controls on spinel clouding and garnet formation in plagioclase of olivine metagabbros, Adirondack Mountains, New York

USGS Publications Warehouse

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

1980-01-01

Olivine metagabbros from the Adirondacks usually contain both clear and spinel-clouded plagioclase, as well as garnet. The latter occurs primarily as the outer rim of coronas surrounding olivine and pyroxene, and less commonly as lamellae or isolated grains within plagioclase. The formation of garnet and metamorphic spinel is dependent upon the anorthite content of the plagioclase. Plagioclase more sodic than An38??2 does not exhibit spinel clouding, and garnet rarely occurs in contact with plagioclase more albitic than An36??4. As a result of these compositional controls, the distribution of spinel and garnet mimics and visually enhances original igneous zoning in plagioclase. Most features of the arrangement of clear (unclouded) plagioclase, including the shells or moats of clear plagioclase which frequently occur inside the garnet rims of coronas, can be explained on the basis of igneous zoning. The form and distribution of the clear zones may also be affected by the metamorphic reactions which have produced the coronas, and by redistribution of plagioclase in response to local volume changes during metamorphism. ?? 1980 Springer-Verlag.

Garnet breakdown in some deep seated garnetiferous xenoliths from the central Sierra Nevada: Petrologic and tectonic implications

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Biswajit

1991-06-01

Garnets in garnetiferous xenoliths from Big Creek, Pick and Shovel and Chinese Peak volcanic pipes, occurring along the axial region of the Sierra Nevada batholith, have broken down to variable degrees to optically opaque and extremely fine-grained kelyphitic rims and seams. In some cases, only opaque pseudomorphs of garnet remain; in others, garnet occurs only as a tiny relict within an opaque mass; in still others, the kelyphite forms a rim and pervades the garnet grain in a complex reticulate fashion. Backscattered-electron imaging and electron microprobe analyses reveal that the unaltered portions of garnets exhibit negligible compositional variations. The unaltered portion is often surrounded by a resorbed rim whose composition is slightly different from that of the bulk garnet; however no systematic difference occurs between the compositions of resorbed rims and those of the unaltered garnets. Around the resorbed rim, lies a zone composed of symplectic intergrowths of aluminous spinel, aluminous orthopyroxene and calcic plagioclase (An 91). Compositions of the symplectite spinels and orthopyroxenes are different from the compositions of those occurring as major discrete phases in the rocks. The possibility that the kelyphites results from oxidation is ruled out. Two alternatives for the origin of these kelyphites seem viable. In the first, they are the result of isochemical decomposition of garnet due to transport by the host lavas from depth to the surface. In the second, they are produced by breakdown and retrogression of garnet due to tectonic transport of the precursor rocks from high P- T conditions to lower P- T conditions before their incorporation into the host volcanics. The second alternative is favored and is supported by the following arguments: (1) Decompression due to transport of the xenoliths by the volcanics should essentially take place along an adiabat and would most likely cause partial melting. No melt phase was found in the symplectites

Fluid-induced Crystallization of Majoritic Garnet During Deep Continental Subduction (Western Gneiss Region, Norway)

NASA Astrophysics Data System (ADS)

Scambelluri, M.; Pettke, T.; van Roermund, H. L.

2008-12-01

In ultrahigh pressure (UHP) rocks, garnet containing pyroxene exsolutions derives from breakdown of majorite crystallized at depths > 200 km. Presence of microdiamonds in some of these rocks [1], including those of the Western Gneiss Region (WGR) of Norway [2], may suggest a fluid-bearing environment for the genesis of majorite. The WGR UHP gneisses host garnet peridotite and websterite recording uplift from extraordinary depths prior to uptake in a subducting slab [2]. These ultramafic rocks (islands of Otrøy and Bardane) derive from depleted Archean transition-zone mantle (350 km depth) upwelled and accreted to a cratonic lithosphere (M2 stage). Evidence for this are decimetric garnets (grt) preserved in Otrøy, hosting up to 20 volume% orthopyroxene (opx) and clinopyroxene (cpx) exsolved from precursor majoritic garnet (M1 stage). The pyroxene lamellae (20-30 ¥ìm thick, hundreds of ¥ìm long) [3] were exsolved under high-T, as shown by the garnet/cpx REE distribution [4]. This Archean-mid Proterozoic record is overprinted by the 425- 390 Ma Scandian continental subduction (M3 stage), forming new grt + cpx + opx + phlogopite (phl) + spinel (sp) that contain diamond-bearing micro-inclusions witnessing deep COH subduction fluids [2]. Here we document formation of new majoritic garnet in the M3 assemblage and in veins at Bardane [5]. Textural characteristics, together with the LREE and LILE enrichments of the M3 minerals, indicate that the new majorite is linked to infiltration of subduction fluids during renewed burial towards sub-lithospheric depths. It represents the deepest occurrence of fluid-related microstructures in mantle rocks. The new majoritic garnet crystallized at grain boundaries and in micro-veins at 7 Gpa and 900-1000 °C. It hosts thin pyroxene needles (5 mm thick, 100 mm long) exsolved under comparatively low-T, as indicated by the garnet/cpx REE distribution. The trace element signature of the majorite-bearing subduction assemblage is LREE

Single and multiphase inclusions in metapelitic garnets of the Rhodope Metamorphic Province, NE Greece.

PubMed

Mposkos, Evripidis; Perraki, Maria; Palikari, Sarra

2009-08-01

Single and multiphase inclusions in garnet porphyroblasts from the diamond-bearing pelitic gneisses were studied by means of combined Raman Spectroscopy and Electron Scanning Microscopy (SEM/EDX). They are either randomly distributed or with preferred orientation within the garnet host and their dimensions vary from less than 5 up to 60 microm. In the single-phase inclusions quartz, rutile, kyanite and graphite dominate. Biotite, zircon, apatite, monazite and allanite are also common. Two types of multiphase inclusions were recognized, hydrous silicate (Type I) and silicate-carbonate (Type II) ones. The carbon-bearing multiphase inclusions predominantly consist of Mg-siderite+graphite+CO(2)+muscovite+quartz formed by a high density carboniferous fluid rich in Fe, Mg, Si and less Ca, Mn, Al and K trapped in the growing garnet in a prograde stage of metamorphism at high-pressure (HP) conditions. The carbon-free multiphase inclusions predominantly consist of biotite+quartz+rutile+/-kyanite+muscovite formed through decompression-dehydration/melting reactions of pre-existing phengite. Single and multiphase inclusions are characterized by polygonal to negative crystal shape formed by dissolution-reprecipitation mechanism between the garnet host and the inclusions during the long lasting cooling period (>100 Ma) of the Kimi Complex.

Present understanding of the stability of Li-stuffed garnets with moisture, carbon dioxide, and metallic lithium

NASA Astrophysics Data System (ADS)

Hofstetter, Kyle; Samson, Alfred Junio; Narayanan, Sumaletha; Thangadurai, Venkataraman

2018-06-01

Fast lithium-ion conducting garnet-type metal oxides are promising membranes for next-generation all-solid-state Li batteries and beyond Li-ion batteries, including Li-air and Li-S batteries, due to their high total Li-ion conductivity and excellent chemical stability against reaction with elemental Li. Several studies have been reported on structure-chemical composition-ionic conductivity property in Li-stuffed garnet-type metal oxides. Here, an overview of the chemical and electrochemical stability of lithium-based garnets against moisture/humidity, aqueous solutions, carbon dioxide, sulfur, and metallic lithium are analyzed. Moisture and aqueous stability studies focus on understanding the crystal structure stability, the proton exchange capacity as a function of Li content in Li-stuffed garnets, and how the protonated species affect the crystal structure and mass transport properties. H+/Li+ exchange was found to be in the range of 2-100%. Stability concerning Li-ion conductivity and morphology under carbon dioxide are discussed. Interfacial chemical stability with lithium metal characterized by electrochemical stability window, Li dendrite formation and area specific resistance (ASR) for the reaction Li ⇌ Li+ +e- are presented. Recent attempts to suppress dendrite formation and to reduce ASR via surface modification are also highlighted. Li and Li-stuffed garnet interface ASR values are shown to be as high as >2000 Ω cm2 and as low as 1 Ω cm2 at room temperature for surface modified Li-stuffed samples. Furthermore, recent studies on Li-S battery utilizing chemically stable Li - garnet electrolyte are also discussed.

H partitioning between NAMs in garnet-bearing peridotite at subsolidus conditions

NASA Astrophysics Data System (ADS)

Demouchy, S. A.; Shcheka, S.; Denis, C. M. M.; Thoraval, C.

2017-12-01

Hydrogen distribution between nominally anhydrous minerals (NAMs) of a garnet-lherzolite under subsolidus conditions has been investigated. Separated NAMs from a garnet-peridotite from Patagonia (Chile) are annealed together (olivine, orthopyroxene, clinopyroxene and garnet) using a piston-cylinder at 3 GPa and 1100 °C using talc-Pyrex cell assembly for 10, 25 and 100 hours. The talc-pyrex assembly provides enough hydrogen in the system to re-equilibrate the hydrogen concentrations at high pressure. The three co-existing nominally anhydrous minerals (NAMs, i.e., olivine, orthopyroxene and clinopyroxene) were successfully analyzed using FTIR. The resulting hydrogen concentrations exceed significantly the initial hydrogen concentration by a factor of 13 for olivine and a factor of 3 for both pyroxenes. Once mineral-specific infrared calibrations are applied, the average concentrations in NAMs are 115±12 ppm wt H2O for olivine, 635±75 ppm wt H2O for orthopyroxene and 1214±137 ppm wt H2O for clinopyroxene, garnet grains are dry. Since local equilibrium seems achieved over time (for 100 hours), the calculated concentration ratios are interpreted as mineral-to-mineral hydrogen partition coefficients (i.e., Nernst `s law) for a garnet-peridotite assemblage. It yields, based on mineral-specific infrared calibrations, Dopx/ol=5±1, Dcpx/ol= 10±2, and Dcpx/opx=1.9±0.4. While Dcpx/opx is in agreement (within error) with previous results from experimental studies and concentration ratios observed in mantle-derived peridotites, the Dpx/ol from this study are significantly lower than the values reported from mantle-derived xenoliths and also at odd with several previous experimental studies where melt and/or hydrous minerals co-exists with NAMs. The results confirm the sensitivity of hydrogen incorporation in olivine regarding the amount of water-derived species (H) in the system and/or the amount of water in the co-existing silicate melt. The results are in agreement with

Neoarchean metamorphism recorded in high-precision Sm-Nd isotope systematics of garnets from the Jack Hills (Western Australia)

NASA Astrophysics Data System (ADS)

Eccles, K. A.; Baxter, E. F.; Mojzsis, S. J.; Marschall, H.; Williams, M. L.; Jercinovic, M. J.

2013-12-01

Studies of metasedimentary rocks from the Jack Hills, which host Earth's oldest known detrital minerals, have focused on zircon and occasionally monazite or xenotime, but no attention has been directed toward one of the most common mineral markers of metamorphism: garnet. Garnet can provide a record of the post-depositional, prograde metamorphic history of Archean metasedimentary rocks. Additionally, the use of a newly developed detrital garnet dating technique [1,2] may reveal information about pre-depositional metamorphism that could address lingering questions about the nature and timing of Earth's earliest tectonometamorphic events. Here we investigate garnet from the Jack Hills metasedimentary rocks to test whether they record in situ metamorphism or are a detrital relict of even older metamorphic events. We identified garnet in two bulk quartz-pebble conglomerate samples collected from the 'discovery' outcrop at Eranondoo Hill in the Jack Hills of Western Australia. Electron microprobe analyses of polished grains and SEM measurements of unpolished grain surfaces are consistent, revealing garnet composition indicative of a single generation/population of predominantly almandine-spessartine solid solution (~10-35% mole fraction spessartine). Compositional maps of garnet grains reveal little zoning and no discontinuities, most consistent with a single growth event. Dating Jack Hills' garnet via the Sm-Nd system is possible due to continued development of small sample analysis techniques, including running NdO+ TIMS analyses with Ta2O5 activator [3] permitting <50 ppm 2 sigma analytical precision on a 400pg in-house standard and continued improvement in blanks (<15pg full procedural blanks). Additionally, employing a nondestructive chemical prescreening technique (tabletop SEM) allows for grouping of multiple grains based on chemical similarity. Final Nd loads in the 450-750pg range routinely yield dates with precisions <×10Ma for two point isochrons between

Garnet film rotator applied in polarizing microscope for domain image modulation (abstract)

NASA Astrophysics Data System (ADS)

Wakabayashi, K.; Numata, T.; Inokuchi, S.

1991-04-01

A garnet film polarization rotator placed before the analyzer in a polarizing microscope was investigated to obtain the difference image of a positive and a negative one of magnetic domain in real time along with an image processor. In the difference image, a nonmagnetic image can be reduced and hence the weak magnetic contrast enhanced. Theoretical calculation of S/N and contrast C of the domain image as a function of the rotation shows they take maxima at the rotation angle of 2.6° and 0.1°, respectively, with the extinction ratio of e=4×10-6 of a polarizing microscope. Thus, since the thickness of the garnet film required is 1 μm or so, the absorption by the garnet rotator does not bring a serious problem even in a visible region for the domain observation. The optimum rotation of the rotator for a high quality observation was obtained by a quantitative study of images obtained experimentally as well as by a visual evaluation. A magnetically unsaturated garnet film with perpendicular magnetization (i.e., multidomain) was employed as a rotator, in which the polarization rotation angle θm of the undeflected beam with respect to the light diffraction could be continuously varied by an applied magnetic field. The dependences of S/N and C on θm were measured, resulting in a well agreement between the measured and the calculated. The visually best image was obtained at θm=0.5° which made the product of S/N and C maximum. The domain image of the Kerr rotation angle of θk=0.22° was observed in S/N=47 dB and C=0.4 when Ar+ laser (λ=515 nm) of tenths of a watt was employed as a light source. Since the domain image with 47 dB S/N does not need an image summation for a noise reduction, a garnet film rotator makes it possible to invert the contrast of a domain image in a real time for an improved domain observation.

Rb-Sr ages from phengite inclusions in garnets from high pressure rocks of the Swiss Western Alps

NASA Astrophysics Data System (ADS)

de Meyer, Caroline M. C.; Baumgartner, Lukas P.; Beard, Brian L.; Johnson, Clark M.

2014-06-01

The Zermatt-Saas Fee Zone (ZSZ) was subducted to eclogite-facies conditions, reaching peak pressures and temperatures of 20-28 kbar and 500-630 °C. The rocks were partially overprinted under greenschist-facies conditions during exhumation. Previous Rb-Sr isochron ages obtained on matrix phengites in metasediments of the ZSZ have been interpreted to date early exhumation of the ZSZ. Here we present new Rb-Sr geochronology on phengite inclusions in garnets to date prograde growth of garnets. We show that garnet acted as a shield for the included phengites, limiting Rb and Sr isotope exchange with the bulk rock, upon complete enclosure of the mica, during garnet growth, even if peak metamorphism exceeded the Rb-Sr blocking temperature. Similarly, garnet isolated the micas from the matrix during subsequent recrystallization due to fluid infiltration or deformation during exhumation. Phengite inclusion ages for two metapelitic samples from the same locality (Triftji) are 44.86±0.49 Ma and 43.6±1.8 Ma, and are about 4 m.y. older than the corresponding matrix mica ages of 40.01±0.51 Ma and 39.5±1.1 Ma, respectively. The results confirm previous Sm-Nd and Lu-Hf geochronology on the ZSZ that indicated protracted garnet growth during prograde metamorphism, and confirm that at least parts of the ZSZ underwent peak metamorphic HP conditions less than 43 m.y. ago, followed by rapid exhumation to upper greenschist-facies conditions around 40 Ma ago.

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.

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

Yttrium geothermometry: an approach to determine the oldest garnet growth recrystallization conditions from micaschists (Yunquera Unit, Betic Cordilleras, southern Spain

NASA Astrophysics Data System (ADS)

Esteban, J. J.; Cuevas, J.; Tubía, J. M.; Gil Ibarguchi, J. I.

2012-04-01

The garnet-xenotime geothermometry is nowadays been using as a tool to identify low-grade relic garnets and even to calculate garnet growth temperatures in metapelites that have undergone a polymetamorphic evolution (Pyle and Spear, 2000; Borghi et al., 2006). A prograde metamorphic evolution, under continuously increasing temperature, can induce garnet and accompanying phase's composition homogenization by intra-crystalline diffusion, leading to flat zoning profiles. Consequently, the application of conventional geothermobarometers on those mineral assemblages does establish minimum P-T conditions. Therefore, the less susceptible elements to diffusion processes, like trace elements, should be taken into account in order to reconstruct their metamorphic evolution. We studied a polymetamorphic micaschist recovered from the Yunquera Unit, one of the tectonic slices of the Internal Zone of the Betic Cordilleras (southern Spain) (Dürr, 1963). The Yunquera unit evidences three stages of recrystallization at different P-T conditions. According to conventional geothermobarometry (Esteban et al., 2005) the metamorphic peak, M2, is estimated at 1200-1300 MPa and 560-695 °C and the decompression path, M3, at 600 MPa and 700 °C. The lack of mineral paragenesis in apparent chemical equilibrium during M1, does not allow determining accurately its recrystallization conditions. Xenotime, identified by scanning electron microprobe, appears as matrix mineral and therefore the entire garnets are assumed to be in chemical equilibrium with it. Yttrium profiles of two garnets show a mean bell-shape compositional variation that differs significatively from the discontinuous profiles shown by Ca, Mg and Fe. This difference accounts for different diffusion rates for those elements and agree with the original Y-zoning preservation. A third Y-profile shows an oscillatory compositional variation. The internal part of garnets, bounded by sharp inclusion trails, are characterized by sawed

Minor elements, HREE and d18O distribution in UHP garnets from the Dora-Maira massif (western Alps)

NASA Astrophysics Data System (ADS)

Brunet, F.; Chazot, G.; Vielzeuf, D.; Chopin, C.

2003-04-01

The spatial distribution of minor elements, HREE and δ18O in garnet can be used as a probe of the availability and mobility of those elements and isotopes at the time of crystal growth, provided that the initial record was not significantly modified by intracrystalline diffusion and that growth took place under nearly constant pressure and temperature conditions. Garnets from three different Dora-Maira rock-types have been studied, (1) nearly pure pyrope (GT1) from the magnesian coesite-bearing quartzites, (2) almandine/pyrope dominant garnets (GT2) from jadeite-quartzite veins which crosscut the Mg-quartzite body, (3) almandine/grossular dominant garnets (GT3) from the country-rock gneiss, sampled in the vicinity of the quartzites. In GT1, minor elements are mainly Fe, Na and P. Na and P are incorporated according to a Na^+ + P5+ = Me2+ + Si4+ substitution with P_2O_5 contents up to 2000 to 2500 ppm. HREE concentrations obtained by LA-ICP-MS, vary by 2 orders of magnitude from core to rim. The δ18O ratio (Cameca 1270, Nancy), around 5 ppm (SMOW), is constant within error throughout the analysed crystals. In GT2, the situation is different since HREE concentrations appear remarkably constant within a given crystal and from one crystal to the other. In contrast with GT1, Na in GT2 is partly charge-balanced by yttrium incorporation. The δ18O ratio in GT2 of around 7 ppm is close to that encountered in GT3 (gneiss) between 7 and 8 ppm. In GT3, phosphorus content is close to detection limit (P_2O_5 below 300 ppm). HREE concentrations are highly variable from one crystal to the other and unfortunately, the size of garnet crystals does not allow profiling. Although δ18O ratio in garnet is imposed by the bulk-rock isotopic composition, HREE distribution is dominated by element availability through the fluid composition and/or absence/presence of accessory phases. The decrease in HREE and P concentration from GT1 cores to rims suggest that these elements are

The Effect of fO2 on Partition Coefficients of U and Th between Garnet and Silicate Melt

NASA Astrophysics Data System (ADS)

Huang, F.; He, Z.; Schmidt, M. W.; Li, Q.

2014-12-01

Garnet is one of the most important minerals controlling partitioning of U and Th in the upper mantle. U is redox sensitive, while Th is tetra-valent at redox conditions of the silicate Earth. U-series disequilibria have provided a unique tool to constrain the time-scales and processes of magmatism at convergent margins. Variation of garnet/meltDU/Th with fO2 is critical to understand U-series disequilibria in arc lavas. However, there is still no systematic experimental study about the effect of fO2 on partitioning of U and Th between garnet and melt. Here we present experiments on partitioning of U, Th, Zr, Hf, Nb, Ta, and REE between garnet and silicate melts at various fO2. The starting material was hydrous haplo-basalt. The piston cylinder experiments were performed with Pt double capsules with C-CO, MnO-Mn3O4 (MM), and hematite-magnetite (HM) buffers at 3 GPa and 1185-1230 oC. The experiments produced garnets with diameters > 50μm and quenched melt. Major elements were measured by EMPA at ETH Zurich. Trace elements were determined using LA-ICP-MS at Northwestern University (Xi'an, China) and SIMS (Cameca1280 at the Institute of Geology and Geophysics, Beijing, China), producing consistent partition coefficient data for U and Th. With fO2 increasing from CCO to MM and HM, garnet/meltDU decreases from 0.041 to 0.005, while garnet/meltDTh ranges from 0.003 to 0.007 without correlation with fO2. Notably, garnet/meltDTh/U increases from 0.136 at CCO to 0.41 at HM. Our results indicate that U is still more compatible than Th in garnet even at the highest fO2 considered for the subarc mantle wedge (~NNO). Therefore, we predict that if garnet is the dominant phase controlling U-Th partitioning during melting of the mantle wedge, melts would still have 230Th excess over 238U. This explains why most young continental arc lavas have 230Th excess. If clinopyroxene is the dominant residual phase during mantle melting, U could be more incompatible than Th at high fO2

Punctuated HT/UHT metamorphism during prolonged Archean orogenesis in the Pikwitonei Granulite Domain revealed by garnet petrochronology

NASA Astrophysics Data System (ADS)

Dragovic, Besim; Guevara, Victor; Caddick, Mark; Couëslan, Chris; Baxter, Ethan

2017-04-01

Fundamental to every modern continent's early (Archean) history is the generation of high temperature conditions required to produce the dense, strong, relatively anhydrous rocks that comprise most of Earth's stable cratonic crust. While the thermal gradients supported in Archean terranes are better understood, the timescales over which these conditions occur are more enigmatic. Garnet petrochronology allows for the interrogation of a semi-continuous record of these tectonometamorphic conditions, by linking pressure-temperature-fluid conditions (using phase equilibria modeling, trace element thermometry, stable isotope geochemistry) to a precise chronologic/chronometric record (e.g. high-precision Sm-Nd geochronology, geospeedometry of major and trace element diffusion profiles). Here, we utilize techniques from this burgeoning field of study to elucidate the rates and conditions of high temperature/ultra-high temperature (HT/UHT) metamorphism in the 2.7 Ga Pikwitonei Granulite Domain (PGD). The PGD represents over 150,000 km2 of dominantly granulite-facies metamorphic rocks situated at the NW edge of the Superior Province. Peak temperatures in the region range from 760°C in the southernmost part of the PGD, to 900-960˚C in the central/western PGD ( 40-60 km apart). Previous studies have suggested that metamorphism was long-lived in the region, occurring over 100 Ma, from 2.71-2.60 Ga [1, 2, 3]. High-precision garnet geochronology on microsampled garnets provides a detailed growth history of several lithologies across the region. Where necessary, bulk garnet analysis (i.e. dating based upon multiple whole garnet crystals rather than portions thereof) was also performed. While cooling from HT/UHT will result in some degree of intra-mineral age resetting, a detailed isotopic study of a range of large garnet porphyroblasts from the PGD (those which would be variably reset depending on peak T, grain size, and initial cooling rate) can retain information about both

Raman spectroscopy of detrital garnet from the (U)HP terrane of eastern Papua New Guinea

NASA Astrophysics Data System (ADS)

Andò, Sergio; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Malusà, Marco G.; Aliatis, Irene; Vezzoli, Giovanni; Garzanti, Eduardo

2013-04-01

Garnet is one of the most widespread heavy minerals in sediments derived from orogenic systems. Its chemical composition varies systematically with temperature and pressure conditions, and thus provides information on the metamorphic evolution of source areas that is crucial in tectonic and geodynamic reconstructions. Garnet is easily identified in mineral grain mounts and is relatively stable during burial diagenesis. Raman spectroscopy allows rapid determination of garnet compositions in grain mounts or thin sections of sand and sandstone samples, and can be used to assess their density and chemical composition quite accurately ("MIRAGEM" method of Bersani et al., 2009; Andò et al., 2009). In the D'Entrecastreaux Islands of southeastern Papua New Guinea, the world's youngest (U)HP rocks are exposed. There, mafic rocks and their felsic host gneisses were metamorphosed under eclogite facies conditions from late Miocene to Pliocene, before being exhumed from depths of ~90 km (Baldwin et al., 2004, 2008). The eclogite preserves a peak assemblage of garnet, omphacite, rutile, phengite and Si02 (Hill and Baldwin, 1993). A coesite-eclogite has been found in one small island outcrop. In order to sample garnet populations representative of a larger geographical area, we sampled and studied a heavy-mineral-dominated placer sand (HMC 80) from a beach from SE Goodenough Island. Garnet grains in beach sand are associated with blue-green to subordinately green-brown amphibole and minor epidote, omphacitic clinopyroxene, titanite, apatite and rutile. The subordinate low-density fraction is feldspatho-quartzose with high-rank metamorphic rock fragments and biotite (Q62 F35 Lm2; MI 360). Detrital garnets are mostly classified as almandine with relatively high Mg and Ca and lacking Mn, typical of the eclogite facies (Win et al., 2007; type Ci garnets of Mange and Morton 2007; Andò et al., 2013). In well-described stratigraphic sequences within syn-and post-tectonic basins

Very high-pressure orogenic garnet peridotites

PubMed Central

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

2007-01-01

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

Longitudinal spin Seebeck effect in various garnet ferrites

NASA Astrophysics Data System (ADS)

Uchida, K.; Nonaka, T.; Kikkawa, T.; Kajiwara, Y.; Saitoh, E.

2013-03-01

The longitudinal spin Seebeck effect (LSSE) is investigated in various garnet ferrites Y3-xRxFe5-yMyO12 (R=Gd, Ca; M=Al, Mn, V, In, Zr) by means of the inverse spin Hall effect in Pt films. The magnitude of the LSSE voltage in the Pt/Y3-xRxFe5-yMyO12 samples is found to be enhanced with increasing concentration of Fe in the garnet ferrites, which can be explained by a change in the spin-mixing conductance at the Pt/Y3-xRxFe5-yMyO12 interfaces. We also investigate the dependence of the LSSE voltage on macroscopic magnetic parameters of Y3-xRxFe5-yMyO12. The experimental results show that the LSSE voltage in the Pt/Y3-xRxFe5-yMyO12 samples has a positive correlation with the Curie temperature and the saturation magnetization, but no clear correlation with the gyromagnetic ratio and the Gilbert damping constant of the samples.

Garnet peridotites from Williams kimberlites, north-central Montana, U.S.A

USGS Publications Warehouse

Hearn, B.C.; McGee, E.S.

1983-01-01

Two Williams kimberlites, 250x350m and 37x390m, in the eastern part of a swarm of 30 middle Eocene alnoitic diatremes in north-central Montana, USA, contain xenoliths of garnet-bearing lherzolites, harzburgites and dunites, in addition to spinel peridotites and upper and lower crustal amphibolites and granulites. Colluvial purple, red, and pink garnets are dominantly Mg- and Cr-rich, indicating their derivation From peridotites or megacrysts, and have CaO and Cr2O3 contents that fall in the lherzolite trend. Temperatures were calculated by the Lindsley-Dixon 20 kb method for lherzolites and by the O'Neill-Wood method for harzburgites and dunites, and pressures were calculated by the MacGregor method, or were assumed to be 50 kb for dunites. Most peridotites equilibrated at 1220-1350?C and 50-60 kb, well above a 44mW/m2 shield geotherm and on or at higher P than the graphite-diamond boundary. Four lherzolites are low T-P (830-990?C, 23-42 kb) and are close to the shield geotherm. All four low T-P lherzolites have coarse textures whereas the high T-P cluster has both coarse and porphyroclastic textures, indicating a range of conditions of deformation and recrystallization in a restricted high T-P range. The tiny size (0.01-0.2 mm) of granulated and euhedral olivines in several xenoliths shows that deformation was occurring just prior to incorporation in kimberlite and that ascent was rapid enough (40-70 km/hr) to retard Further coarsening of fine-grained olivine. For other high T-P peridotites, cessation of deformation and beginning of recrystallization before or during inclusion in kimberlite is suggested by larger (up to 3mm) euhedral olivines in a matrix of fine granulated olivine or by optical continuity of large and nearby small olivines. Two low T-P lherzolites contain distinctive, phlogopite-rimmed, 5-8mm clots of moderate-Cr garnet + Cr-spinel + Cr-diopside + enstatite that are inferred to have formed by reaction of an initial high-Cr garnet brought into the

Pressure-induced nano-crystallization of silicate garnets from glass

PubMed Central

Irifune, T.; Kawakami, K.; Arimoto, T.; Ohfuji, H.; Kunimoto, T.; Shinmei, T.

2016-01-01

Transparent ceramics are important for scientific and industrial applications because of the superior optical and mechanical properties. It has been suggested that optical transparency and mechanical strength are substantially enhanced if transparent ceramics with nano-crystals are available. However, synthesis of the highly transparent nano-crystalline ceramics has been difficult using conventional sintering techniques at relatively low pressures. Here we show direct conversion from bulk glass starting material in mutianvil high-pressure apparatus leads to pore-free nano-polycrystalline silicate garnet at pressures above ∼10 GPa in a limited temperature range around 1,400 °C. The synthesized nano-polycrystalline garnet is optically as transparent as the single crystal for almost the entire visible light range and harder than the single crystal by ∼30%. The ultrahigh-pressure conversion technique should provide novel functional ceramics having various crystal structures, including those of high-pressure phases, as well as ideal specimens for some mineral physics applications. PMID:27924866

Garnet-type solid-state fast Li ion conductors for Li batteries: critical review.

PubMed

Thangadurai, Venkataraman; Narayanan, Sumaletha; Pinzaru, Dana

2014-07-07

Batteries are electrochemical devices that store electrical energy in the form of chemical energy. Among known batteries, Li ion batteries (LiBs) provide the highest gravimetric and volumetric energy densities, making them ideal candidates for use in portable electronics and plug-in hybrid and electric vehicles. Conventional LiBs use an organic polymer electrolyte, which exhibits several safety issues including leakage, poor chemical stability and flammability. The use of a solid-state (ceramic) electrolyte to produce all-solid-state LiBs can overcome all of the above issues. Also, solid-state Li batteries can operate at high voltage, thus, producing high power density. Various types of solid Li-ion electrolytes have been reported; this review is focused on the most promising solid Li-ion electrolytes based on garnet-type metal oxides. The first studied Li-stuffed garnet-type compounds are Li5La3M2O12 (M = Nb, Ta), which show a Li-ion conductivity of ∼10(-6) at 25 °C. La and M sites can be substituted by various metal ions leading to Li-rich garnet-type electrolytes, such as Li6ALa2M2O12, (A = Mg, Ca, Sr, Ba, Sr0.5Ba0.5) and Li7La3C2O12 (C = Zr, Sn). Among the known Li-stuffed garnets, Li6.4La3Zr1.4Ta0.6O12 exhibits the highest bulk Li-ion conductivity of 10(-3) S cm(-1) at 25 °C with an activation energy of 0.35 eV, which is an order of magnitude lower than that of the currently used polymer, but is chemically stable at higher temperatures and voltages compared to polymer electrolytes. Here, we discuss the chemical composition-structure-ionic conductivity relationship of the Li-stuffed garnet-type oxides, as well as the Li ion conduction mechanism.

Major element and oxygen isotope geochemistry of vapour-phase garnet from the Topopah Spring Tuff at Yucca Mountain, Nevada, USA

USGS Publications Warehouse

Moscati, Richard J.; Johnson, Craig A.

2014-01-01

Twenty vapour-phase garnets were studied in two samples of the Topopah Spring Tuff of the Paintbrush Group from Yucca Mountain, in southern Nevada. The Miocene-age Topopah Spring Tuff is a 350 m thick, devitrified, moderately to densely welded ash-flow tuff that is zoned compositionally from high-silica rhyolite to latite. During cooling of the tuff, escaping vapour produced lithophysae (former gas cavities) lined with an assemblage of tridymite (commonly inverted to cristobalite or quartz), sanidine and locally, hematite and/or garnet. Vapour-phase topaz and economic deposits associated commonly with topaz-bearing rhyolites (characteristically enriched in F) were not found in the Topopah Spring Tuff at Yucca Mountain. Based on their occurrence only in lithophysae, the garnets are not primary igneous phenocrysts, but rather crystals that grew from a F-poor magma-derived vapour trapped during and after emplacement of the tuff. The garnets are euhedral, vitreous, reddish brown, trapezohedral, as large as 2 mm in diameter and fractured. The garnets also contain inclusions of tridymite. Electron microprobe analyses of the garnets reveal that they are almandine-spessartine (48.0 and 47.9 mol.%, respectively), have an average composition of (Fe1.46Mn1.45Mg0.03Ca0.10)(Al1.93Ti0.02)Si3.01O12 and are comparatively homogeneous in Fe and Mn concentrations from core to rim. Composited garnets from each sample site have δ18O values of 7.2 and 7.4‰. The associated quartz (after tridymite) has δ18O values of 17.4 and 17.6‰, values indicative of reaction with later, low-temperature water. Unaltered tridymite from higher in the stratigraphic section has a δ18O of 11.1‰ which, when coupled with the garnet δ18O values in a quartz-garnet fractionation equation, indicates isotopic equilibration (vapour-phase crystallization) at temperatures of ~600°C. This high-temperature mineralization, formed during cooling of the tuffs, is distinct from the later and commonly recognized

Cellular Precipitates Of Iron Oxide in Olivine in a Stratospheric Interplanetary Dust Particle

NASA Technical Reports Server (NTRS)

Rietmeijer, Frans J. M.

1996-01-01

The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at approx. 1100 C during atmospheric entry flash (5-15 s) heating.

Testing Mechanisms and Scales of Equilibrium Using Textural and Compositional Analysis of Porphyroblasts in Rocks with Heterogeneous Garnet Distributions

NASA Astrophysics Data System (ADS)

Ruthven, R. C.; Ketcham, R. A.; Kelly, E. D.

2015-12-01

Three-dimensional textural analysis of garnet porphyroblasts and electron microprobe analyses can, in concert, be used to pose novel tests that challenge and ultimately increase our understanding of metamorphic crystallization mechanisms. Statistical analysis of high-resolution X-ray computed tomography (CT) data of garnet porphyroblasts tells us the degree of ordering or randomness of garnets, which can be used to distinguish the rate-limiting factors behind their nucleation and growth. Electron microprobe data for cores, rims, and core-to-rim traverses are used as proxies to ascertain porphyroblast nucleation and growth rates, and the evolution of sample composition during crystallization. MnO concentrations in garnet cores serve as a proxy for the relative timing of nucleation, and rim concentrations test the hypothesis that MnO is in equilibrium sample-wide during the final stages of crystallization, and that concentrations have not been greatly altered by intracrystalline diffusion. Crystal size distributions combined with compositional data can be used to quantify the evolution of nucleation rates and sample composition during crystallization. This study focuses on quartzite schists from the Picuris Mountains with heterogeneous garnet distributions consisting of dense and sparse layers. 3D data shows that the sparse layers have smaller, less euhedral garnets, and petrographic observations show that sparse layers have more quartz and less mica than dense layers. Previous studies on rocks with homogeneously distributed garnet have shown that crystallization rates are diffusion-controlled, meaning that they are limited by diffusion of nutrients to growth and nucleation sites. This research extends this analysis to heterogeneous rocks to determine nucleation and growth rates, and test the assumption of rock-wide equilibrium for some major elements, among a set of compositionally distinct domains evolving in mm- to cm-scale proximity under identical P-T conditions.

Origins of subcalcic garnets and their relation to diamond forming fluids—Case studies from Ekati (NWT-Canada) and Murowa (Zimbabwe)

NASA Astrophysics Data System (ADS)

Klein-BenDavid, Ofra; Graham Pearson, D.

2009-02-01

Subcalcic, high-Cr (G10) garnets are found as inclusions within diamonds and in peridotitic xenoliths. The strong spatial associations between G10 garnets and diamond make them an important tool in the investigation of diamond genesis. We present an integrated study of the major and trace element composition and oxygen-Sr-Nd-Hf isotopic ratios of eight G10 garnets from the Ekati mine (NWT-Canada) and four from the Murowa mine (Zimbabwe) in an attempt to determine their petrogenetic evolution and to further examine a possible relationship between the metasomatic agents responsible for G10 garnet signatures and diamond forming fluids. All garnets display sinusoidal to mildly sinusoidal REE patterns and have negative Ti, Sr and positive U anomalies. They have variably radiogenic 87Sr/ 86Sr (0.703261-0.731191) and non-radiogenic ɛNd values (-8.1 to -27.1), except for one sample from Murowa that has a positive ɛNd of 2.5. One Ekati sample has an extremely low ɛHf value of -61.6. The Ekati garnets we have studied all appear to come from a single depth in the Slave lithospheric mantle. On the base of Cr-Ca relations they have crystallized at 4.9 GPa and display dunitic Ca intercept values. Their δ 18O values range between +5.23‰ and +5.42‰. The Ekati G10 garnets record a complex, multi-stage metasomatic history involving the interaction of several components during their genesis. One metasomatic agent was enriched in HFSE, LREE, Sr, and depleted in Nb. This agent had the least radiogenic Sr. Another metasomatic agent had highly radiogenic Sr, and was enriched in LREE, Sr, Nb, Th and U. The G10 garnets have very low ɛNd and ɛHf values combined with radiogenic Sr, thus, they require an early lithospheric mantle enrichment event at some stage during their genesis or during the evolution of any precursor material that they formed from. The only Hf isotope composition measurable from the Ekati suite is so unradiogenic ( ɛHf = -61) that it yields a Lu/Hf model age of

Partition coefficients for REE between garnets and liquids - Implications of non-Henry's Law behaviour for models of basalt origin and evolution

NASA Technical Reports Server (NTRS)

Harrison, W. J.

1981-01-01

An experimental investigation of Ce, Sm and Tm rare earth element (REE) partition coefficients between coexisting garnets (both natural and synthetic) and hydrous liquids shows that Henry's Law may not be obeyed over a range of REE concentrations of geological relevance. Systematic differences between the three REE and the two garnet compositions may be explained in terms of the differences between REE ionic radii and those of the dodecahedral site into which they substitute, substantiating the Harrison and Wood (1980) model of altervalent substitution. Model calculations demonstrate that significant variation can occur in the rare earth contents of melts produced from a garnet lherzolite, if Henry's Law partition coefficients do not apply for the garnet phase.

Chemical and oxygen isotope zonings in garnet from subducted continental crust record mineral replacement and metasomatism

NASA Astrophysics Data System (ADS)

Vho, Alice; Rubatto, Daniela; Regis, Daniele; Baumgartner, Lukas; Bouvier, Anne-Sophie

2017-04-01

Garnet is a key mineral in metamorphic petrology for constraining pressure, temperature and time paths. Garnet can preserve multiple growth stages due to its wide P-T stability field and the relatively slow diffusivity for major and trace elements at sub-solidus temperatures. Pressure-temperature-time-fluid paths of the host rock may be reconstructed by combining metamorphic petrology with microscale trace element and oxygen isotope measurements in garnet. Subduction zones represent relevant geological settings for geochemical investigation of element exchanges during aqueous fluid-rock interactions. The Sesia Zone consists of a complex continental sequence containing a variety of mono-metamorphic and poly-metamorphic lithologies such as metagranitoids, sediments and mafic boudins. The precursor Varisican-Permian amphibolite-facies basement (6-9 kbar 650-850°C; Lardeaux and Spalla, 1991; Robyr et al., 2013) experienced high pressure metamorphism (15-22 kbar 500-550°C; Regis, et al. 2014; Robyr et al., 2013) during Alpine subduction. In different lithologies of the Internal Complex (Eclogitic Micaschist Complex), including metabasites from the Ivozio Complex, Ti-rich metasediments from Val Malone and pre-Alpine Mn-quartzites associated to metagabbros from Cima Bonze, garnet is abundant and shows a variety of complex textures that cannot be reconciled with typical growth zoning, but indicate resorption and replacement processes and possible metasomatism. In-situ, microscale oxygen isotopes analysis of garnet zones was performed by ion microprobe with the SwissSIMS Cameca IMS 1280-HR at University of Lausanne and SHRIMP-SI at the Australian National University. Each sample has a distinct δ18O composition, and the δ18O values show different degrees of variation between domains. Homogeneously low values of < 5‰ are measured in the garnets from the Ivozio Complex metagabbro. Intragrain variations of up to 3.5‰ in the porphyroblasts from Val Malone metasediments

Metasomatic processes in the mantle beneath the Arkhangelsk province, Russia: evidence from garnet in mantle peridotite xenoliths, Grib pipe

NASA Astrophysics Data System (ADS)

Kargin, Alexei; Sazonova, Lyudmila; Nosova, Anna; Kovalchuk, Elena; Minevrina, Elena

2015-04-01

The Arkhangelsk province is located in the northern East European Craton and includes more than 80 bodies of kimberlite, alkaline picrite and other ultramafic and mafic rocks. They erupted through the Archean-Early Proterozoic basement into the Riphean-Paleozoic sedimentary cover. The Grib kimberlite pipe is located in the central part of the Arkhangelsk province in the Verkhotina (Chernoozerskoe) kimberlite field. The age of the Grib kimberlite is 376+-3 Ma (Rb-Sr by phlogopite). The Grib kimberlite pipe is the moderate-Ti kimberlites (TiO2 1-2 wt %) with strongly fractionated REE pattern , (La/Yb)n = 38-87. The Nd isotopic composition of the Grib pipe ranges epsilon Nd from -0.4 to + 1.0 and 87Sr/86Sr(t) from 0.7042 to 0.7069 (Kononova et al., 2006). Geochemical (Jeol JXA-8200 electron microprobe; SIMS; LA-ICP-MS) composition of clinopyroxene and garnet from mantle-derived xenoliths of the Grib kimberlite pipe was studied to provide new insights into metasomatic processes in the mantle beneath the Arkhangelsk province. Based on both major and trace element data, five geochemical groups of peridotitic garnet were distinguished. The partial melting of metasomatic peridotite with crystallization of a garnet-clinopyroxene association, and orthopyroxene assimilation by protokimberlitic melts was simulated and a model of garnet and clinopyroxene metasomatic origin was proposed. The model includes three stages: 1. Mantle peridotite was fertilized by subduction-derived sediment partial melts/fluids at the lithosphere-asthenosphere boundary to yield a CO2-bearing mantle peridotite (source I). 2. The partial melting of the carbonate-bearing mantle source 1 produced carbonatite-like melts (a degree of partial melting was 1,5 %), which could form the carbonatite-kimberlite rocks of the Mela River (Arkhangelsk province, 50 km North-West of Grib kimberlite) and also produce the metasomatic reworking of (carbonate-bearing) mantle peridotite (mantle source II) and form type-1

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.

A Study of Defect Behavior in Almandine Garnet

NASA Astrophysics Data System (ADS)

Geiger, C. A.; Brearley, A. J.; Dachs, E.; Tipplet, G.; Rossman, G. R.

2016-12-01

Transport and diffusion in crystals are controlled by defects. However, a good understanding of the defect types in many silicates, including garnet, is not at hand. We undertook a study on synthetic almandine, ideal end-member Fe3Al2Si3O12, to better understand its precise chemical and physical properties and defect behavior. Crystals were synthesized at high pressures and temperatures under different fO2 conditions using various starting materials with H2O and without. The almandine obtained came in polycrystalline and single-crystal form. The synthetic reaction products and crystals were carefully characterized using X-ray powder diffraction, electron microprobe and TEM analysis and with 57Fe Mössbauer, UV/VIS single-crystal absorption and IR single-crystal spectroscopy. Various possible intrinsic defects, such as the Frenkel, Schottky and site-disorder types, along with Fe3+, in both synthetic and natural almandine crystals, were analyzed based on model defects expressed in Kröger-Vink notation. Certain types of minor microscopic- to macroscopic-sized precipitation or exsolution phases, including some that are nanosized, that are observed in synthetic almandine (e.g., magnetite), as well as in more compositionally complex natural crystals (e.g., magnetite, rutile, ilmenite), may result from defect reactions. An explanation for their origin through minor amounts of defects in garnet has certain advantages over other models that have been put forth in the literature that assume strict garnet stoichiometry for their formation and/or open-system atomic transport over relatively long length scales. Physical properties, including magnetic, electrical conductivity and diffusion behavior, as well as the color, of almandine are also analyzed in terms of various possible model defects. It is difficult, if not impossible, to synthesize stoichiometric end-member almandine, Fe3Al2Si3O12, in the laboratory, as small amounts of extrinsic OH- and/or Fe3+ defects, for example

Metasomatic Control of Water in Garnet and Pyroxene from Kaapvaal Craton Mantle Xenoliths

NASA Technical Reports Server (NTRS)

Peslier, Anne H.; Woodland, Alan B.; Bell, David R.; Lazarov, Marina; Lapen, Thomas J.

2012-01-01

Fourier transform infrared spectrometry (FTIR) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) were used to determine water, rare earth (REE), lithophile (LILE), and high field strength (HFSE) element contents in garnet and pyroxene from mantle xenoliths, Kaapvaal craton, southern Africa. Water enters these nominally anhydrous minerals as protons bonded to structural oxygen in lattice defects. Pyroxene water contents (150-400 ppm in clinopyroxene; 40-250 ppm in orthopyroxene) correlate with their Al, Fe, Ca and Na and are homogeneous within a mineral grains and a xenolith. Garnets from Jagersfontein are chemically zoned for Cr, Ca, Ti and water contents. Garnets contain 0 to 20 ppm H2 Despite the fast diffusion rate of H in mantle m inerals, the observations above indicate that the water contents of mantle xenolith minerals were not disturbed during kimberlite entrainment and that the measured water data represent mantle values. Trace elements in all minerals show various degrees of light REE and LILE enrichments indicative of minimal to strong metasomatism. Water contents of peridotite minerals from the Kaapvaal lithosphere are not related to the degree of depletion of the peridotites. Instead, metasomatism exerts a clear control on the amount of water of mantle minerals. Xenoliths from each location record specific types of metasomatism with different outcomes for the water contents of mantle minerals. At pressures . 5.5 GPa, highly alkaline melts metasomatized Liqhobong and Kimberley peridotites, and increased the water contents of their olivine, pyroxenes and garnet. At higher pressures, the circulation of ultramafic melts reacting with peridotite resulted in co-variation of Ca, Ti and water at the edge of garnets at Jagersfontein, overall decreasing their water content, and lowered the water content of olivines at Finsch Mine. The calculated water content of these melts varies depending on whether the water content of the peridotite

Oxygen isotopes in garnet and accessory minerals to constrain fluids in subducted crust

NASA Astrophysics Data System (ADS)

Rubatto, Daniela; Gauthiez-Putallaz, Laure; Regis, Daniele; Rosa Scicchitano, Maria; Vho, Alice; Williams, Morgan

2017-04-01

Fluids are considered a fundamental agent for chemical exchanges between different rock types in the subduction system. Constraints on the sources and pathways of subduction fluids thus provide crucial information to reconstruct subduction processes. Garnet and U-Pb accessory minerals constitute some of the most robust and ubiquitous minerals in subducted crust and can preserve multiple growth zones that track the metamorphic evolution of the sample they are hosted in. Microbeam investigation of the chemical (major and trace elements) and isotopic composition (oxygen and U-Pb) of garnet and accessory minerals is used to track significant fluid-rock interaction at different stages of the subduction system. This approach requires consideration of the diffusivity of oxygen isotopes particularly in garnet, which has been investigated experimentally. The nature of the protolith and ocean floor alteration is preserved in relict accessory phases within eclogites that have been fully modified at HP conditions (e.g. Monviso and Dora Maira units in the Western Alps). Minerals in the lawsonite-blueschists of the Tavsanli zone in Turkey record pervasive fluid exchange between mafic and sedimentary blocks at the early stage of subduction. High pressure shear zones and lithological boundaries show evidence of intense fluid metasomatism at depth along discontinuities in Monviso and Corsica. In the UHP oceanic crust of the Zermatt-Saas Zone, garnet oxygen isotopes and tourmaline boron isotopes indicate multistage fluid infiltration during prograde metamorphism. Localized exchanges of aqueous fluids are also observed in the subducted continental crust of the Sesia-Lanzo Zone. In most cases analyses of distinct mineral zones enable identification of multiple pulses of fluids during the rock evolution.

Magnetostatic Waves-Based Integrated Optic Bragg Cell Modules With Applications To RF Signal Processing

DTIC Science & Technology

1992-06-30

18-722, 1985. (b)N. Koshizuka, K. Ando, and T. Okuda, "Growth-Induced Birefringence in LPE - grown Iron Garnet Films ," in Proc. Int. Sy ,p...J. Martin, R. Wolf, R. C. LeCraw, and S. L. Black,"Switching and modulation of light in magneto-optic waveguides of garnet films ," Appl. Phys. Lett...in an Yttrium Iron Garnet Film ," Soy. Tech. Phys. Lett., Vol..1, pp.386-387, 1985. (c) A. A. Solomko. Yu. A. Gaidai, A. V. Dovzhenko, M. V

The Role of Garnet Pyroxenite in High-Fe Mantle Melt Generation: High Pressure Melting Experiments

NASA Astrophysics Data System (ADS)

Tuff, J.; Takahashi, E.; Gibson, S.

2004-12-01

Evidence for the existence of heterogeneous or 'marble cake' convecting mantle1 is provided recently by rare, high MgO ( ˜ 15 wt.%) primitive magmas with anomalously high abundances of FeO* ( ˜ 13.5 to 16 wt. %2,3; where FeO* = total Fe as FeO). These high-Fe mantle melts show a limited occurrence in the initial stage of magmatism in large igneous provinces (e.g. Deccan, Ethiopia and Paraná-Etendeka) and some have incompatible trace-element and radiogenic-isotopic ratios (Sr, Nd and Pb) that resemble those of ocean-island basalts. This suggests that they are predominantly derived from the convecting mantle2. The ferropicrites are mildly- to sub-alkaline and have low contents of Al2O3 (< 10 wt.%) and heavy rare-earth elements (e.g. Lu < 0.18ppm) that are consistent with the increased stability of garnet, due to the high FeO* content in the ferropicrite mantle source. It has been proposed that the source of the high FeO* may be garnet-pyroxenite streaks derived from subducted mafic oceanic crust2. We have undertaken melting experiments between 1 atmosphere and 7 GPa in order to determine the anhydrous phase relations of an uncontaminated ferropicrite lava from the base of the Early-Cretaceous Paraná-Etendeka continental flood-basalt province. The sample has high contents of MgO ( ˜ 14.9 wt.%), FeO* (14.9 wt.%) and NiO (0.07 wt.%). Olivine phenocrysts have maximum Fo contents of 85 and are in equilibrium with the host rock, assuming a Kd of 0.32 and we believe that the sample is representative of a primary Fe-rich mantle plume derived melt. In total, 75 experimental runs were carried out. Melting phase relations as well as compositions and modal proportions of all coexisting phases were successfully determined in 60 run products. Phase relations indicate that the ferropicrite melt was generated either at ˜ 2.2 GPa from an olivine-pyroxene residue or ˜ 5 GPa from a garnet-pyroxene residue. A low bulk-rock Al2O3 content (9 wt.%) and high [Gd/Yb]n ratio (3.1) are

Investigating the origins of rhythmic major-element zoning in HP/LT garnets from worldwide subduction mélanges

NASA Astrophysics Data System (ADS)

Viete, D. R.; Hacker, B. R.; Seward, G.; Allen, M. B.

2016-12-01

Rhythmic major-element zoning has been documented in garnets from high pressure/low temperature (HP/LT) lenses within a number of worldwide subduction mélanges (e.g. California, Chinese Tianshan, Cuba, Greek Cyclades, Guatemala, Japan, Venezuela). The origin of these features has implications for the nature of subduction-zone processes. Conditions of rhythmic zoning acquirement in HP/LT garnets of California and Venezuela were investigated by use of Raman and FTIR microspectroscopy, and thermodynamic modelling of phase equilibria. Quartz-in-garnet Raman barometry reveals varying P—on the order of 100­-300 MPa, over radial distances of 10s of µm—in association with the high-Mn (and low-Mg) bands that define the fine-scale rhythmic zoning. Results from FTIR microspectroscopy demonstrate association between the high-Mn bands and locally depressed (structural) OH and elevated (molecular) H2O concentrations. The microspectroscopy results suggest changes in P and fluid activity attended development of the cryptic rhythmic zoning. Perple_X modelling of phase equilibria shows that, for specific rock chemistry and subduction P-T conditions, garnet modal abundance is extremely sensitive to changes in P (e.g. 10-20 vol.% growth/dissolution for ΔP = 200 MPa). Rhythmic major-element zoning may reflect P- and/or fluid-driven cycles of garnet stability-instability and/or varying reaction progress/kinetics during subduction. Steep compositional gradients that define the rhythmic major-element zoning limit time scales at subduction T, requiring that such individual stability-instability and/or accelerated reaction cycles were extremely brief. Seismic cycles or porosity waves represent ephemeral phenomena capable of accounting for development of rhythmic major-element zoning in HP/LT garnet, during subduction, as a result of fluctuations in both P and fluids. Metamorphic rocks may well carry detailed records of the catastrophism that punctuates longer-term tectonometamorphic

Cr-pyrope garnets in the lithospheric mantle 2. Compositional populations and their distribution in time and space

NASA Astrophysics Data System (ADS)

Griffin, W. L.; Fisher, N. I.; Friedman, J. H.; O'Reilly, Suzanne Y.; Ryan, C. G.

2002-12-01

Three novel statistical approaches (Cluster Analysis by Regressive Partitioning [CARP], Patient Rule Induction Method [PRIM], and ModeMap) have been used to define compositional populations within a large database (n > 13,000) of Cr-pyrope garnets from the subcontinental lithospheric mantle (SCLM). The variables used are the major oxides and proton-microprobe data for Zn, Ga, Sr, Y, and Zr. Because the rules defining these populations (classes) are expressed in simple compositional variables, they are easily applied to new samples and other databases. The classes defined by the three methods show strong similarities and correlations, suggesting that they are statistically meaningful. The geological significance of the classes has been tested by classifying garnets from 184 mantle-derived peridotite xenoliths and from a smaller database (n > 5400) of garnets analyzed for >20 trace elements by laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICPMS). The relative abundances of these classes in the lithospheric mantle vary widely across different tectonic settings, and some classes are absent or very rare in either Archean or Phanerozoic SCLM. Their distribution with depth also varies widely within individual lithospheric sections and between different sections of similar tectonothermal age. These garnet classes therefore are a useful tool for mapping the geology of the SCLM. Archean SCLM sections show high degrees of depletion and varying degrees of metasomatism, and they are commonly strongly layered. Several Proterozoic SCLM sections show a concentration of more depleted material near their base, grading upward into more fertile lherzolites. The distribution of garnet classes reflecting low-T phlogopite-related metasomatism and high-T melt-related metasomatism suggests that many of these Proterozoic SCLM sections consist of strongly metasomatized Archean SCLM. The garnet-facies SCLM beneath Phanerozoic terrains is only mildly depleted

The solubility and site preference of Fe3+ in Li7−3xFexLa3Zr2O12 garnets

PubMed Central

Rettenwander, D.; Geiger, C.A.; Tribus, M.; Tropper, P.; Wagner, R.; Tippelt, G.; Lottermoser, W.; Amthauer, G.

2015-01-01

A series of Fe3+-bearing Li7La3Zr2O12 (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe3+ pfu could be incorporated in Li7−3xFexLa3Zr2O12 garnet solid solutions. At Fe3+ concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe3+ contents lower than 0.52 Fe3+ pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a0, for all solid-solution garnets is similar with a value of a0≈12.98 Å regardless of the amount of Fe3+. 57Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO3 in syntheses with Fe3+ contents greater than 0.16 Fe3+ pfu. The composition of different phase pure Li7−3xFexLa3Zr2O12 garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li6.89Fe0.03La3.05Zr2.01O12, Li6.66Fe0.06La3.06Zr2.01O12, Li6.54Fe0.12La3.01Zr1.98O12, and Li6.19Fe0.19La3.02Zr2.04O12. The 57Fe Mössbauer spectrum of cubic Li6.54Fe0.12La3.01Zr1.98O12 garnet indicates that most Fe3+ occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe3+ in smaller amounts occurs at a general 96h site, which is only present for certain Li-oxide garnets, and in Li6.54Fe0.12La3.01Zr1.98O12 this Fe3+ has a distorted 4-fold coordination. PMID:26435549

Characterisation of a garnet population from the Sikkim Himalaya: implications for the mechanisms and rates of porphyroblast crystallisation

NASA Astrophysics Data System (ADS)

George, Freya; Gaidies, Fred

2016-04-01

Analysis of porphyroblast distribution in metamorphic rocks yields insight into the processes controlling metamorphic reaction rates. By coupling this textural record with microprobe analysis and phase-equilibria and diffusion modelling, a detailed view of the nucleation and growth history of metamorphic minerals can be obtained. In this study, we comprehensively characterise the 3D distribution and compositional variation of a garnet population in a garnet-grade pelitic schist of the Lesser Himalayan Sequence (Sikkim), in order to investigate both the rates and kinetic controls of porphyroblastic crystallisation. Quantification of the size, shape and spatial distribution of garnet using high-resolution μ-computed X-ray tomography and statistical analysis reveals a log-normal crystal size distribution, systematic variation of aspect ratio with crystal size, and a significantly clustered garnet texture in the study sample. The latter is indicative of interface-controlled nucleation and growth, with nucleation sites controlled principally by a heterogeneous precursor assemblage. At length-scales less than 0.7 mm, there is evidence for adjacent grains that are on average smaller than the mean size of the population; this minor ordering is attributed to secondary redistribution of porphyroblast centers and reduction of crystal sizes due to syn-kinematic growth and resorption, respectively. Geochemical traverses through centrally sectioned garnet crystals of variable size highlight several features: (1) core compositions of even the smallest crystals preserve primary prograde growth zonation, with little evidence for diffusional modification in any crystal size; (2) rim compositions are within error between grains, suggestive of sample-scale equilibration of the growth medium at the time of cessation of crystallisation; (3) different grains of equal radii display equivalent compositional zoning; and (4) gradients of compositional profiles display a steepening trend in

The formation and trace elements of garnet in the skarn zone from the Xinqiao Cu-S-Fe-Au deposit, Tongling ore district, Anhui Province, Eastern China

NASA Astrophysics Data System (ADS)

Xiao, Xin; Zhou, Tao-fa; White, Noel C.; Zhang, Le-jun; Fan, Yu; Wang, Fang-yue; Chen, Xue-feng

2018-03-01

Xinqiao is a large copper-gold deposit and consists of two major mineralization types: stratabound and skarn. The skarn occurs along the contact between a quartz diorite intrusion and Carboniferous-Triassic limestone. Xinqiao has a strongly developed skarn zone, including endoskarn and exoskarn; the exoskarn is divided into proximal and distal exoskarn. We present systematic major, trace and rare earth element (REE) concentrations for garnets from the skarn zone, discuss the factors controlling the incorporation of trace elements into the garnets, and constrain the formation and evolution of the garnet from skarn zone in Xinqiao deposit. Grossular (Adr20-44Grs56-80) mostly occurs in endoskarn and has typical HREE-enriched and LREE-depleted patterns, with small Eu anomalies and low ∑REE. Garnets from the exoskarn show complex textures and chemical compositions. The composition of garnets range from Al-rich andradite (Adr63-81Grs19-47) to andradite (Adr67-98Grs2-33). Garnet in endoskarn has typical HREE-enriched and LREE-depleted patterns. Al-rich andradite in proximal skarn has small Eu anomalies and moderate ∑REE. Andradite from distal exoskarn shows strong positive Eu anomalies and has variable ∑REE. The U, Y, Fe and Al relationship with ∑REE shows that two mechanisms controlled incorporation of REE into the garnets: crystal chemistry (substitution and interstitial solid solution) mainly controlled in the endoskarn garnet (grossular) and the proximal exoskarn (Al-rich andradite), and fluid and rock chemistry (surface adsorption and occlusion) controlled REEs in the distal exoskarn. Furthermore, Al has a negative relationship with ∑REE indicating that REE3+ did not follow a coupled, YAG-type substitution into the garnets. Variations in textures and trace and rare earth elements of garnets suggest that the garnets in the endoskarn formed by slow crystal growth at low W/R ratios and near-neutral pH in a closed system during periods of diffusive metasomatism

Multiferroic properties of the Y2BiFe5O12 garnet

NASA Astrophysics Data System (ADS)

Durán, A.; Ostos, C.; Arnache, O.; Siqueiros, J. M.; García-Guaderrama, M.

2017-10-01

Multiferroic properties are found in the Yttrium iron garnet (YIG) modified with Bi3+. The X-ray diffraction pattern shows that the Bi3+ ion is completely soluble up to one-third of the Y molar content forming the Y2BiFe5O12 compound as a single phase. Structural analysis did not show signals of other incipient non-centrosymmetric phases in the compound. However, the dielectric and polarization studies clearly exhibit a typical relaxor ferroelectric behavior at room temperature where the maxima of the broad permittivity peaks shift with frequency. The quadratic diffuseness coefficient obtained from the modified Curie-Weiss law suggests polar nanoregion switching in a broad temperature range. Using the Vogel-Fulcher relationship, the activation energy and freezing temperature were found to be 243.1 meV and 322.6 K, respectively. Here, the main contribution to relaxation comes from thermally activated reorientation of the dipole moments, as confirmed by the well-defined hysteresis loops in the P-E measurements. The dipole fluctuations arise from the compositional disorder induced by Bi3+ ions randomly distributed in the lattice, having thermally active polarization fluctuations above the freezing temperature, Tf. Furthermore, it is found that Bi3+ preserves the magnetization features of this compound. Thus, the Bi3+ modified YIG compound is found to be a multiferroic material at room temperature.

Origin of Ti-rich garnets in the groundmass of Wajrakarur field kimberlites, southern India: insights from EPMA and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Dongre, Ashish N.; Viljoen, K. S.; Rao, N. V. Chalapathi; Gucsik, A.

2016-04-01

Although Ti-rich garnets are commonly encountered in the groundmass of many alkaline igneous rocks, they are comparatively rare in kimberlites. Here we report on the occurrence of Ti-rich garnets in the groundmass of the P-15 and KL-3 kimberlites from the diamondiferous Wajrakarur field in the Eastern Dharwar craton of southern India. These garnets contain considerable Ti (11.7-23.9 wt.% TiO2), Ca (31.3-35.8 wt.% CaO), Fe (6.8-15.5 wt.% FeOT) and Cr (0.04-9.7 wt.% Cr2O3), but have low Al (0.2-5.7 wt.% Al2O3). In the case of the P-15 kimberlite they display a range in compositions from andradite to schorlomite, with a low proportion of grossular (andradite(17.7-49.9)schorlomite(34.6-49.5)-grossular(3.7-22.8)-pyrope(1.9-10.4)). A few grains also contain significant chromium and represent a solid solution between schorlomite and uvarovite. The Ti-rich garnets in the KL-3 kimberlite, in contrast, are mostly schorlomitic (54.9-90.9 mol %) in composition. The Ti-rich garnets in the groundmass of these two kimberlites are intimately associated with chromian spinels, perhaps suggesting that the garnet formed through the replacement of spinel. From the textural evidence, it appears unlikely that the garnets could have originated through secondary alteration, but rather seem to have formed through a process in which early magmatic spinels have reacted with late circulating, residual fluids in the final stages of crystallization of the kimberlite magma. Raman spectroscopy provides evidence for low crystallinity in the spinels which is likely to be a result of their partial transformation into andradite during their reaction with a late-stage magmatic (kimberlitic) fluid. The close chemical association of these Ti-rich garnets in TiO2-FeO-CaO space with those reported from ultramafic lamprophyres (UML) is also consistent with results predicted by experimental studies, and possibly implies a genetic link between kimberlite and UML magmas. The occurrence of Ti-rich garnets of

Tectonothermal evolution of a garnet-bearing quartzofeldspathic gneiss from the Moyar shear zone, south India and its bearing on the Neoarchean accretionary tectonics

NASA Astrophysics Data System (ADS)

Bhadra, Subhadip; Nasipuri, Pritam

2017-03-01

We present mesoscale structural development across the Nilgiri Block and the flanking Moyar and Bhavani shear zones in south India, and detailed mineral-chemical and geothermobarometric studies of a garnet-bearing quartzofeldspathic gneiss from the easternmost part of the Moyar shear zone. Barring a narrow (< 100 μm) rim domain, major element distribution within garnet porphyroblasts reveals complete chemical homogenization. The absence of growth zoning in garnet porphyroblasts may suggest a protracted post-garnet growth residence period of the rock at elevated temperatures. Chemical zoning near garnet rim reflects the signature of both retrograde net-transfer (ReNTR) and retrograde exchange (ReER) equilibria. The ReNTR-equilibrium is recognized by prominent Mn kick-up in garnet, whereas the ReER-equilibrium is identified by divergence of Fe and Mg between garnet and biotite. Diffusion modelling, though qualitative, of the observed chemical zoning in garnet suggests an initial phase of rapid ( 150 °C/Ma) cooling, which may have been achieved by tectonic-extrusion-induced exhumation. Pressure-temperature conditions for peak, ReNTR and ReER are constrained, respectively, at 900 °C; 9-11 kbar, 735 °C; 8 kbar and 685 °C; 7.8 kbar. Analyses of structural fabrics establish oppositely verging nature of the Moyar and Bhavani shear zone and may suggest a doubly vergent orogenic development, with the former as prowedge and the latter as retrowedge. The presence of the Nilgiri Block as a topographically elevated region between these oppositely dipping thrust faults indeed corroborates a doubly vergent orogenic setup. The tectonic scenario is comparable with a continent-continent collision type accretionary tectonics. Peak high-P granulite facies metamorphism and post-peak long residence period of the studied quartzofeldspathic gneiss at deep crustal level suitably fit into the Neoarchean crustal dynamics resulting in crustal thickening, in the order of 41 km, within the

Development of Novel Garnet-Type Solid Electrolytes for Potential Application in Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Narayanan, Sumaletha

The development of promising solid electrolytes having a garnet-like structure has been successfully achieved through solid state (ceramic) method. Various approaches to improve the Li ion conductivity were employed. The first approach involved creating oxide ion vacancies into the crystal structure of parent garnet-like oxide, Li5La3Nb2O 12 to create a novel family of compounds with nominal composition, Li 5La3Nb2-xYxO12-δ (0 ≤ x ≤ 1). The second approach was Li stuffing into the garnet-like oxides to develop a series of Li stuffed novel Li5+2xLa3Nb 2-xYxO12 (0.05 ≤ x ≤ 0.75) and Li6.5 La2.5Ba0.5ZrTaO12. Powder X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) coupled with a wavelength-dispersive spectrometer (WDS), 7Li nuclear magnetic resonance (Li-NMR), and AC impedance spectroscopy were employed to characterize the structure, morphology, elemental composition, Li ion sites, and Li ion conductivity. Studies have shown that Li5+2xLa 3Nb2-xYxO12 have turned out to be promising solid electrolytes with high Li ion conductivity (10-4 Scm -1 at ambient temperatures). In addition, all families of garnets are found to be chemically stable with Li cathode materials (Li2MMn 3O8, where M = Fe, Co) up to 400 °C in air. The developed electrolyte materials have the potential to be used in all-solid-state Li ion batteries.

First findings of monocrystalline aragonite inclusions in garnet from diamond-grade UHPM rocks (Kokchetav Massif, Northern Kazakhstan).

PubMed

Korsakov, Andrey V; Vandenabeele, Peter; Perraki, Maria; Moens, Luc

2011-10-01

The presence of aragonite inclusions in garnet from diamond-grade metamorphic rocks from the Kokchetav Massif, Northern Kazakhstan was identified for the first time by means of Raman analyses and mapping. Aragonite appears within the inclusions up to 50 μm in size as a single crystal. These inclusions have rounded shape. The grain boundary between the host-garnet is smooth. No cracks occur around the aragonite inclusions. No significant shift in the main aragonite Raman band was measured. These observations indicate that residual pressure within the inclusion is minor. These findings imply either non-UHPM origin of the host garnet or significant plastic deformation of host minerals during retrograde stage. These features should be taken into account for recovery peak metamorphic conditions and modeling of exhumation processes of UHPM complexes. Copyright © 2010 Elsevier B.V. All rights reserved.

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.

Comparative Studies on Al-Based Composite Powder Reinforced with Nano Garnet and Multi-wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Basariya, M. Raviathul; Srivastava, V. C.; Mukhopadhyay, N. K.

2015-11-01

Effect of mechanical alloying/milling on microstructural evolution and hardness variations of garnet and multi-walled carbon nanotubes (MWCNTs)-reinforced Al-Mg-Si alloy (EN AW6082) composites are investigated. Structural and morphological studies revealed that the composite powders prepared by milling display a more homogenous distribution of the reinforcing particles. Improved nanoindentation hardness viz., 4.24 and 5.90 GPa are achieved for EN AW6082/Garnet and EN AW6082/MWCNTs composites, respectively, and it is attributed to severe deformation of the aluminum alloy powders and embedding of the harder reinforcement particles uniformly into the aluminum alloy matrix. However, enhancement in case of MWCNTs-reinforced composite makes apparent the effect of its nanosized uniform dispersion in the matrix, thereby resisting the plastic deformation at lower stress and increased dislocation density evolved during high-energy ball milling. The results of the present study indicate that carbon nanotubes and garnet can be effectively used as reinforcements for Al-based composites.

Enrichment of trace elements in garnet amphibolites from a paleo-subduction zone: Catalina Schist, southern California

USGS Publications Warehouse

Sorensen, Sorena S.; Grossman, J.N.

1989-01-01

The abundance, P-T stability, solubility, and element-partitioning behavior of minerals such as rutile, garnet, sphene, apatite, zircon, zoisite, and allanite are critical variables in models for mass transfer from the slab to the mantle wedge in deep regions of subduction zones. The influence of these minerals on the composition of subduction-related magmas has been inferred (and disputed) from inverse modelling of the geochemistry of island-arc basalt, or by experiment. Although direct samples of the dehydration + partial-melting region of a mature subduction zone have not been reported from subduction complexes, garnet amphibolites from melanges of circumpacific and Caribbean blueschist terranes reflect high T (>600??C) conditions in shallower regions. Such rocks record geochemical processes that affected deep-seated, high-T portions of paleo-subduction zones. In the Catalina Schist, a subduction-zone metamorphic terrane of southern California, metasomatized and migmatitic garnet amphibolites occur as blocks in a matrix of meta-ultramafic rocks. This mafic and ultramafic complex may represent either slab-derived material accreted to the mantle wedge of a nascent subduction zone or a portion of a shear zone closely related to the slab-mantle wedge contact, or both. The trace-element geochemistry of the complex and the distribution of trace elements among the minerals of garnet amphibolites were studied by INAA, XRF, electron microprobe, and SEM. In order of increasing alteration from a probable metabasalt protolith, three common types of garnet amphibolite blocks in the Catalina Schist are: (1) non-migmatitic, clinopyroxene-bearing blocks, which are compositionally similar to MORB that has lost an albite component; (2) garnet-amphibolite blocks, which have rinds that reflect local interaction between metabasite, metaperidotite, and fluid; and (3) migmatites that are extremely enriched in Th, HFSE, LREE, and other trace elements. These trace-element enrichments

Solid state lasers based on chromium- and neodymium-activated scandium garnets operating in the Q-switched mode

NASA Astrophysics Data System (ADS)

Denisov, A. L.; Zharikov, E. V.; Zavartsev, Iu. D.; Zagumennyi, A. I.; Lutts, G. B.

1991-02-01

The development of passively Q-switched and self-Q-switched lasers based on chromium-containing scandium garnets with phototropic centers is reported. The lasers operate over a wide frequency repetition rate with a mean output up to 100 W. The characteristics of phototropic absorption in the 1-micron region are examined, and the possibility of lasing at the weak transition of the Nd(3+) ion in chromium-containing scandium garnets with phototropic centers is discussed.

Raman spectroscopic study of synthetic pyrope-grossular garnets: structural implications

NASA Astrophysics Data System (ADS)

Du, Wei; Han, Baofu; Clark, Simon Martin; Wang, Yichuan; Liu, Xi

2018-02-01

A study of the effect of substitution of Mg and Ca in garnet solid solution (Grtss) was carried out using Raman spectroscopy to probe changes to the crystal lattice. The garnet solid solutions with composition changing along pyrope (Py; Mg3Al2Si3O12) and grossular (Gr; Ca3Al2Si3O12) binary were synthesized from glass at 6 GPa and 1400 °C and a second series of Grtss with composition Py40Gr60 were synthesized at 6 GPa but different temperatures from 1000 to 1400 °C. Raman mode assignments were made based on a comparison with the two end members pyrope and grossular, which show consistent result with literature study on single crystals data. The correlation between the Raman mode frequencies and compositional changes along the pyrope-grossular binary suggests a two-mode behavior for Mg and Ca cations in the garnet structure. The full widths at half-maximum of selected Raman modes increase on moving away from the end members and are about double the end-member values in the mid-position, where the frequencies closely linearly change with composition. The frequencies of the translational modes of the SiO4 tetrahedron (T(SiO4)) show large deviations from linearity indicating a strong kinematic coupling with the translational modes of the Ca and Mg cations. The anomalies in T(SiO4) are linked to mixing unit cell volume, suggesting that the nonlinear mixing volume behavior along the pyrope-grossular binary is related to the resistance of the Si-O bond to expansion and compression, which is caused by substitution of Mg and Ca cations in the dodecahedral sites. Annealing temperature also shows effect on Raman mode frequencies, but the main factor controlling the changes in mode frequencies along pyrope-grossular binary is composition.

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.;

Investigations on the Crystal-Chemical Behavior of Transition-Metal-Bearing Aluminosilicate Garnet Solid Solutions Using 27Al and 29Si NMR Spectroscopy

NASA Astrophysics Data System (ADS)

Palke, A. C.; Geiger, C. A.; Stebbins, J. F.

2015-12-01

The petrological importance of silicate garnet is derived from the presence of three distinct cation sites of varying size and coordination number. This allows for a wide range of trace, minor, and major element substitutions. However, a full and precise crystal-chemical understanding of the nature of transition metals in garnet is not at hand. Possible mechanisms of various charge-balanced substitutions (e.g. octahedral Ti4+ or tetrahedral Al3+) and the structural state of solid solutions (i.e. short- to long-range ordering) need study. We report on ongoing efforts in these directions using 27Al and 29Si Magic-Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy. Early work on synthetic and natural Fe- and Mn-bearing pyrope- and grossular-rich garnets focused on the effect these paramagnetic transition metals have in measuring and interpreting NMR spectra. These results have been expanded with NMR measurements on synthetic pyrope-rich garnets containing other paramagnetic transition metals including Cr3+, V3+, Co2+, and Ni2+ as well as diamagnetic Ti4+. NMR peaks are severely broadened in the presence of even small concentrations of Cr3+, Mn2+, and Fe3+ leading to a loss of spectral resolution. On the other hand, the spectra of garnet containing V3+, Fe2+, Co2+, and Ni2+ have better resolution and show separate paramagnetically shifted NMR peaks. In some cases, crystal-chemical information can be obtained because of the large frequency separations between the NMR peaks that can be assigned to various local atomic configurations around Al and Si. Furthermore, the 27Al NMR spectrum of a synthetic pyrope garnet with about 2% diamagnetic Ti4+ on the octahedral site showed the absence of any tetrahedral Al3+, which rules out the substitution mechanism VITi + IVAl = VIAl + IVSi in the solid solution. Our NMR investigations on garnet are now being made at the exploratory level. We think that NMR spectra of diamagnetic garnet can provide information on a

Kinetic characteristics of the luminescence decay for industrial yttrium-gadolinium-aluminium garnet based phosphors

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Stepanov, S. A.; Valiev, D. T.; Vishnyakova, E. A.; Abdullin, H. A.; Marhabaeva, A. A.; Tulegenova, A. T.

2016-02-01

The spectral and decay kinetic characteristics of pulse cathodoluminescence and photoluminescence of phosphors based on yttrium-gadolinium-aluminum garnet were investigated using pulsed optical time resolved spectroscopy.

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.

Early Triassic change in the erosional level in the eastern part of the Bohemian Massif revealed by detrital garnet assemblages from the Buntsandstein siliciclastics of southern Poland

NASA Astrophysics Data System (ADS)

Kowal-Linka, Monika; Walczak, Klaudia

2017-04-01

Garnets, as constituents of various magmatic and metamorphic rocks, show different chemical compositions depending on the type of magma or primary rock, the temperature, and the pressure. This diversity of chemical compositions makes detrital garnets a very useful tool for provenance analysis and deciphering changes in erosional levels of source areas. Preliminary works reveal that the Lower and Middle Buntsandstein terrigenous and marine sandstones cropping out in southern Poland (50˚ 28'20"N, 18˚ 04'33"E and 50˚ 27'35"N, 18˚ 07'23"E) are characterized by very different heavy mineral assemblages (HMA) and types of detrital garnets. The aim of the research is to recognize the source areas and causes of these distinct variations using petrographic analysis, heavy mineral analysis, and electron probe microanalysis. During the Early Triassic, the area under study was located between two landmasses: the eastern margin of the Bohemian Massif (BM) to the west and Pre-Carpathian Land (PCL) to the east. Presently, the sampled area is situated ˜50 km from the NE margin of the BM, which consists of many garnet-bearing rocks and is a presumable source area for the examined grains. The PCL was hidden under the Carpathians during the Alpine orogeny and knowledge of its composition is very limited. Petrographic analysis shows that the older sandstones are red to rusty quartz arenites with a hematite-rich matrix and well-rounded grains (aeolian deposits). The younger sandstones are bicolored quartz wackes (dirty pink with grey patches) with a calcite matrix and angular to rounded grains (shallow marine deposits). The arenites contain zircon, tourmaline, and rutile grains accompanied by garnet, staurolite, apatite, and topaz. The opaque heavy minerals include ilmenite, ilmenite-rutile aggregates, magnetite and rarely chromian spinel. In contrast, the HMA from the wackes consist mostly of garnets, while the minerals listed above occur in subordinate amounts. The garnets from

Glass in garnet pyroxenite xenoliths from Kaula Island, Hawaii: Product of infiltration of host nephelinite

NASA Astrophysics Data System (ADS)

Garcia, Michael O.; Presti, A. A.

1987-10-01

Garnet-bearing, mantle-derived pyroxenites have been found at a new locality in Hawaii, Kaula Island. They occur as xenoliths in a nephelinite tuff. Some of the pyroxenites contain basaltic glasses, a common feature in mantle-derived xenoliths. Results of petrography, mineral chemistry, and least-squares mixing calculations show that the glasses are products of infiltration of the host nephelinite into the xenoliths and partial assimilation of garnet, spinel, and clinopyroxene. These results should encourage others to thoroughly test petrographically viable explanations for glasses in xenoliths before invoking absent phases or metasomatic fluids as explanations for the glasses. *Currently with Mobil Oil Company, Houston, Texas

The role of trace element partitioning between garnet, zircon and orthopyroxene on the interpretation of zircon U-Pb ages: an example from high-grade basement in Calabria (Southern Italy)

NASA Astrophysics Data System (ADS)

Fornelli, A.; Langone, A.; Micheletti, F.; Pascazio, A.; Piccarreta, G.

2014-03-01

The recognition of the coeval growth of zircon, orthopyroxene and garnet domains formed during the same metamorphic cycle has been attempted with detailed microanalyses coupled with textural analyses. A coronitic garnet-bearing granulite from the lower crust of Calabria has been considered. U-Pb zircon data and zircon, garnet and orthopyroxene chemistries, at different textural sites, on a thin section of the considered granulite have been used to test possible equilibrium and better constrain the geological significance of the U-Pb ages related to zircon separates from other rocks of the same structural level. The garnet is very rich in REE and is characterised by a decrease in HREE from core to outer core and an increase in the margin. Zircons show core-overgrowth structures showing different chemistries, likely reflecting episodic metamorphic new growth. Zircon grains in matrix, corona around garnet and within the inner rim of garnet, are decidedly poorer in HREE up to Ho than garnet interior. Orthopyroxene in matrix and corona is homogeneously poor in REE. Thus, the outer core of garnet and the analysed zircon grains grew or equilibrated in a REE depleted system due to the former growth of garnet core. Zircon ages ranging from 357 to 333 Ma have been determined in the matrix, whereas ages 327-320 Ma and around 300 Ma have been determined, respectively, on cores and overgrowths of zircons from matrix, corona and inner rim of garnet. The calculated DREEzrn/grt and DREEopx/grt are largely different from the equilibrium values of literature due to strong depletion up to Ho in zircon and orthopyroxene with respect to garnet. On the other hand, the literature data show large variability. In the case study, (1) the D zrn/grt values define positive and linear trends from Gd to Lu as many examples from literature do and the values from Er to Lu approach the experimental results at about 900 °C in the combination zircon dated from 339 to 305 Ma with garnet outer core

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.

Unraveling the polymetamorphic history of garnet-bearing metabasites: Insights from the North Motagua Mélange (Guatemala Suture Zone)

NASA Astrophysics Data System (ADS)

Bonnet, G.; Flores, K. E.; Martin, C.; Harlow, G. E.

2014-12-01

The Guatemala Suture Zone is the fault-bound region in central Guatemala that contains the present North American-Caribbean plate boundary. This major composite geotectonic unit contains a variety of ophiolites, serpentinite mélanges, and metavolcano-sedimentary sequences along with high-grade schists, gneisses, low-grade metasediments and metagranites thrusted north and south of the active Motagua fault system (MFS). The North Motagua Mélange (NMM) outcrops north of the MFS and testifies the emplacement of exhumed subduction assemblages along a collisional tectonic setting. The NMM is composed of a serpentinite-matrix mélange that contains blocks of metabasites (subgreenschist facies metabasalt, grt-blueschist, eclogite, grt-amphibolite), vein-related rocks (jadeitite, omphacitite, albitite, mica-rock), and metatrondhjemites. Our new detailed petrographic and thermobarometric study on the garnet-bearing metabasites reveals a complex polymetamorphic history with multiple tectonic events. Eclogites show a classical clockwise PT path composed of (a) prograde blueschist/eclogite facies within garnet cores, (b) eclogite facies metamorphic peak at ~1.7 GPa and 620°C, (c) post-peak blueschist facies, (d) amphibolite facies overprint, and (e) late stage greenschist facies. Two types of garnet amphibolite blocks can be found, the first consist of (a) a relict eclogite facies peak at ~1.3 GPa and 550°C only preserved within anhedral garnet cores, and (b) surrounded by a post-peak amphibolite facies. In contrast, the second type displays a prograde amphibolite facies at 0.6-1.1 GPa and 400-650°C. The eclogites metamorphic peak suggests formation in a normal subduction zone at ~60 km depth, a subsequent exhumation to the middle section of the subduction channel (~35 km), and a later metamorphic reworking at lower P and higher T before its final exhumation. The first type of garnet amphibolite shows a similar trajectory as the eclogites but at warmer conditions. In

Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

NASA Astrophysics Data System (ADS)

Narduzzi, F.; Farina, F.; Stevens, G.; Lana, C.; Nalini, H. A.

2017-06-01

Magmatic garnet, together with epidote, is a rare mineral association in cordilleran-I-type granitoids and of special petrogenetic significance. The metaluminous to slightly peraluminous (ASI = 0.97-1.07) Galiléia batholith (Brazil) is a large (ca. 30,000 km2), Neoproterozoic (ca. 632-570 Ma) weakly foliated calc-alkaline granitoid body, characterized by the widespread occurrence of garnet (grossular 25-43 mol%) and epidote (pistacite 9.3-22.7 mol%). Field, petrographic and mineral chemical evidence indicates that garnet, epidote, biotite as well as white mica crystals (low-Si phengite), are magmatic. There is no difference in bulk rock major and trace element composition between the Galiléia granitoids and other garnet-free cordilleran-type granitoids worldwide. This evidence strongly suggests that the origin of the uncommon garnet + epidote parageneses is related to the conditions of magma crystallization, such as pressure, temperature and water content. Comparison between the mineral assemblages and mineral compositions from this study and those recorded in crystallization experiments on metaluminous calc-alkaline magmas, as well as within garnet-bearing metaluminous volcanic rocks and granitoids, indicates that the supersolidus coexistence of grossular-rich garnet, epidote and white mica is consistent with magma crystallization at pressures greater than 0.8 GPa (above 25 km depth) and at temperatures below 700 °C, i.e. near the water saturated solidus. Furthermore, resorption textures around garnet (plagioclase ± quartz coronas) and epidote suggest that these minerals have been partially consumed prior to complete crystallization. These findings demonstrate that at 630 Ma the crust underneath the Araçuaí Orogen was already at least 25-30 km thick and relatively cool. However, this contrasts with the marked high heat flow registered from the neighbour Carlos Chagas Batholith located 50 km to the east. In fact such granitoids record granulite

MSW Variable Time-Delay Techniques.

DTIC Science & Technology

1982-07-01

21 I, 5. RITAXIAL GEOWTH O COG FILKS G0 film growth by lpe was Investigated as a possible nouagnetic, dielectric spacer sediun between two YG fls...using two yttrium iron garnet films sandwiching simple single finger transducers. Difficulties In exciting the symetric forward volume mode are explained...direction. Measurements of time delay versus frequency are presented for epitaxially grown Yttrium Iron Garnet (YIG) films . Finally, transducer coupling

Rapid Thermal Annealing of Cathode-Garnet Interface toward High-Temperature Solid State Batteries.

PubMed

Liu, Boyang; Fu, Kun; Gong, Yunhui; Yang, Chunpeng; Yao, Yonggang; Wang, Yanbin; Wang, Chengwei; Kuang, Yudi; Pastel, Glenn; Xie, Hua; Wachsman, Eric D; Hu, Liangbing

2017-08-09

High-temperature batteries require the battery components to be thermally stable and function properly at high temperatures. Conventional batteries have high-temperature safety issues such as thermal runaway, which are mainly attributed to the properties of liquid organic electrolytes such as low boiling points and high flammability. In this work, we demonstrate a truly all-solid-state high-temperature battery using a thermally stable garnet solid-state electrolyte, a lithium metal anode, and a V 2 O 5 cathode, which can operate well at 100 °C. To address the high interfacial resistance between the solid electrolyte and cathode, a rapid thermal annealing method was developed to melt the cathode and form a continuous contact. The resulting interfacial resistance of the solid electrolyte and V 2 O 5 cathode was significantly decreased from 2.5 × 10 4 to 71 Ω·cm 2 at room temperature and from 170 to 31 Ω·cm 2 at 100 °C. Additionally, the diffusion resistance in the V 2 O 5 cathode significantly decreased as well. The demonstrated high-temperature solid-state full cell has an interfacial resistance of 45 Ω·cm 2 and 97% Coulombic efficiency cycling at 100 °C. This work provides a strategy to develop high-temperature all-solid-state batteries using garnet solid electrolytes and successfully addresses the high contact resistance between the V 2 O 5 cathode and garnet solid electrolyte without compromising battery safety or performance.

Intercomparison of garnet barometers and implications for garnet mixing models

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

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

1985-01-01

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

The timing of high-temperature retrogression in the Reynolds Range, central Australia: constraints from garnet and epidote Pb-Pb dating

NASA Astrophysics Data System (ADS)

Buick, Ian S.; Frei, Robert; Cartwright, Ian

Lower Calcsilicate Unit metasediments and underlying migmatitic Napperby Gneiss metagranite at Conical Hill in the Reynolds Range, central Australia, underwent regional high-grade ( 680 to 720°C), low-pressure/high-temperature metamorphism at 1594+/- 6Ma. The Lower Calcsilicate Unit is extensively quartz veined and epidotised, and discordant grandite garnet+epidote quartz veins may be traced over tens of metres depth into pegmatites that pooled at the Lower Calcsilicate Unit-Napperby Gneiss contact. The quartz veins were probably precipitated by water-rich fluids that exsolved from partial melts derived from the Napperby Gneiss during cooling from the peak of regional metamorphism to the wet granite solidus. Pb stepwise leaching (PbSL) on garnet from three discordant quartz veins yielded comparable single mineral isochrons of 1566+/-32Ma, 1576+/-3Ma and 1577+/-5Ma, which are interpreted as the age of garnet growth in the veins. These dates are in good agreement with previous Sensitive High Resolution Ion Microprobe (SHRIMP) ages of zircon and monazite formed during high-temperature retrogression (1586+/-5 to 1568+/-4Ma) elsewhere in the Reynolds Range. The relatively small age difference between peak metamorphism and retrograde veining suggests that partial melting and melt crystallisation controlled fluid recycling in the high-grade rocks. However, PbSL experiments on epidote intergrown with, and partially replacing, garnet in two of the veins yielded isochrons of 1454+/-34 and 1469+/- 26Ma. The 100-120Ma age difference between intergrown garnet and late epidote from the same vein suggests that the vein systems may have experienced multiple episodes of fluid flow.

Petrology and fluid inclusions of garnet-clinopyroxene rocks from the Gondwana suture zone in southern India: Implications for prograde high-pressure metamorphism

NASA Astrophysics Data System (ADS)

Tsunogae, T.

2012-04-01

The Palghat-Cauvery Suture Zone (PCSZ) in the southern granulite terrane, India, which separates Pan-African granulite blocks (e.g., Madurai and Trivandrum Blocks) to the south and Archean terrane (e.g., Salem Block and Dharwar Craton) to the north is regarded as a major suture zone in the Gondwana collisional orogeny. It probably continues westwards to the Betsimisaraka suture in Madagascar, and eastwards into Sri Lanka and possibly into Antarctica. The available geochronological data including U-Pb zircon and EPMA monazite ages indicate that the rocks along the PCSZ underwent an episode of high-grade metamorphism at ca. 530 Ma that broadly coincides with the time of final assembly of the Gondwana supercontinent. Recent investigations on high-grade metamorphic rocks in this region have identified several new occurrences of garnet-clinopyroxene rocks and associated meta-gabbros from Perundurai, Paramati, Aniyapuram, Vadugappatti, and Mahadevi areas in Namakkal region within the central domain of the PCSZ. They occur as elongated boudins of 1 m to 1 km in length within hornblende-biotite orthogneiss. The garnet-clinopyroxene mafic granulites contain coarse-grained (up to several cm) garnet (Alm30-50 Pyr30-40 Grs10-20) and clinopyroxene (XMg = 0.70-0.85) with minor pargasite, plagioclase (An30-40), orthopyroxene (hypersthene), and rutile. Garnet and clinopyroxene are both subidioblastic and contain few inclusions of clinopyroxene (in garnet) and plagioclase. Orthopyroxene occur only as Opx + Pl symplectite between garnet and clinopyroxene in almost all the localities, suggesting the progress of decompressional reaction: Grt + Cpx + Qtz => Opx + Pl, which is a dominant texture in the PCSZ. The prograde mineral assemblage of the rocks is therefore inferred to be Grt + Cpx + Qtz, although quartz was probably totally consumed by the progress of the reaction. The metamorphic P-T calculations using Grt-Cpx-Pl-Qtz geothermobarometers yield T = 850-900°C and P >13 kbar

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

The mantle and crustal evolution of two garnet peridotite suites from the Western Gneiss Region, Norwegian Caledonides: An isotopic investigation

NASA Astrophysics Data System (ADS)

Brueckner, H. K.; Carswell, D. A.; Griffin, W. L.; Medaris, L. G., Jr.; Van Roermund, H. L. M.; Cuthbert, S. J.

2010-06-01

A compilation of published and unpublished geochronological and isotopic data from garnet-bearing orogenic peridotites in the HP/UHP Western Gneiss Region (WGR) of the Norwegian Caledonides indicate a common origin for all WGR peridotites, followed by different, though related, Proterozoic and Phanerozoic histories for those in the northwestern WGR (NW peridotites) compared to those in the central and western WGR (CW peridotites). All peridotites are refractory fragments of the subcontinental lithosphere generated by Archean melt extraction, which produced strongly depleted dunites and harzburgites with relict orthopyroxene and majoritic garnet megacrysts (M 1NW) within the NW peridotites. The Archean history is preserved by Re-Os sulfide and whole-rock ages from several WGR bodies and by Sm-Nd ages from the M 1NW megacrysts. Subsequently the CW peridotites were re-fertilized within the lithospheric mantle by mid-Proterozoic or older silicate melts that generated M 2CW garnet pyroxenites and adjacent garnet peridotites. Clinopyroxenes from these bodies show large variation in 143Nd/ 144Nd, but nearly constant 87Sr/ 86Sr, suggesting autometasomatism of depleted mantle by LREE-enriched, Rb-poor melts derived from equally depleted mantle. NW peridotites lack mid-Proterozoic garnet pyroxenite intrusions, but M 2NW garnet-rich assemblages that exsolved from relict M 1 megacrysts may have equilibrated at the same time as the M 2CW refertilization. Sm-Nd and Lu-Hf mineral apparent isochron ages from both suites range from 1.75 to ca. 0.87 Ga. The age spectrum suggests continuous diffusion among M 2 minerals that formed ≥ 1.75 Ga ago punctuated by partial re-equilibration during a 1.0 Ga thermal event. Much later the NW peridotites were transferred from the mantle wedge into the crust as the WGR was subducted into the mantle during the ca 400 Ma Scandian Orogeny. Further subduction heterogeneously metasomatized and recrystallized the NW peridotites to form M 3NW garnet

Microwave Magnetic Materials for Radar and Signal Processing Devices - Thin Film and Bulk Oxides and Metals

DTIC Science & Technology

2007-11-29

films, (3) low field effective linewidth in polycrystalline ferrites, (4) Fermi-Pasta-Ulam recurrence for spin wave solitons in yttrium iron garnet...Fermi- Pasta-Ulam recurrence for spin wave solitons in yttrium iron garnet (YIG) film strips in a feedback ring system, (5) the Hamiltonian...XRD data. point in field was so small that field modulation and lock -in The FMR field is taken at the peak loss point in the (b) detection methods

Iron isotopic systematics of pyroxenite xenoliths from North China Craton: implications for Melt-rock interaction in the sub-continental lithospheric mantle beneath eastern China

NASA Astrophysics Data System (ADS)

Zhao, X.; Cao, H.; Yu, H.; Huang, F.

2016-12-01

Iron isotope systems have become widely used tools in high temperature geochemistry and provide important constraints on mantle dynamics. Here, we report Fe isotopic data on a series of pyroxenite xenoliths from Hannuoba, North China Craton to further constrain the Fe isotopic composition of the mantle and investigate the behavior of Fe isotopes during mantle processes. These xenoliths range from Cr- pyroxenites, Al-pyroxenites to garnet pyroxenites, and are taken as physical evidence for different episodes of melt injection events. Our results show that both Cr- pyroxenites and Al-pyroxenites have a narrow range of Fe isotopes (δ57Fe=-0.01 to 0.09), similar to that reported typical mantle peridotites and they show equilibrium inter-mineral Fe isotope fractionation between coexisting mantle minerals. In contract, the garnet pyroxenites, which are products of reaction between a silicate melt and peridotite, exhibit larger Fe isotopic variations, with δ57Fe ranging from 0.08 to 0.30. The δ57Fe values of minerals in these garnet pyroxenites also vary widely from -0.25 to -0.03 in olivines, from -0.04 to 0.14 in orthopyroxenes, from -0.07 to 0.31 in clinopyroxenes, from 0.07 to 0.26 in spinels and from 0.30 to 0.39 in garnets. These observed data stand in marked contrast to the calculated equilibrium Fe isotope fractionation between coexisting mantle minerals at mantle temperature from theory, indicating disequilibrium isotope fractionation. The disequilibrium isotope fractionations between coexisting mantle minerals in garnet pyroxenites most likely reflect kinetic isotope fractionation during melt-peridotite interaction. In addition, the phlogopite clinopyroxenite with an apparent metasomatic overprint has the heaviest δ57Fe (as high as 1.00) but lightest δ26Mg (as low as -1.50) values of the investigated samples. Our study shows that mantle metasomatism plays an important role in producing Fe isotopic heterogeneity of the subcontinental mantle.

Properties of Ferrite Garnet (Bi, Lu, Y)3(Fe, Ga)5O12 Thin Film Materials Prepared by RF Magnetron Sputtering

PubMed Central

Nur-E-Alam, Mohammad; Belotelov, Vladimir; Alameh, Kamal

2018-01-01

This work is devoted to physical vapor deposition synthesis, and characterisation of bismuth and lutetium-substituted ferrite-garnet thin-film materials for magneto-optic (MO) applications. The properties of garnet thin films sputtered using a target of nominal composition type Bi0.9Lu1.85Y0.25Fe4.0Ga1O12 are studied. By measuring the optical transmission spectra at room temperature, the optical constants and the accurate film thicknesses can be evaluated using Swanepoel’s envelope method. The refractive index data are found to be matching very closely to these derived from Cauchy’s dispersion formula for the entire spectral range between 300 and 2500 nm. The optical absorption coefficient and the extinction coefficient data are studied for both the as-deposited and annealed garnet thin-film samples. A new approach is applied to accurately derive the optical constants data simultaneously with the physical layer thickness, using a combination approach employing custom-built spectrum-fitting software in conjunction with Swanepoel’s envelope method. MO properties, such as specific Faraday rotation, MO figure of merit and MO swing factor are also investigated for several annealed garnet-phase films. PMID:29789463

IBA investigations of loose garnets from Pietroasa, Apahida and Cluj-Someşeni treasures (5th century AD)

NASA Astrophysics Data System (ADS)

Bugoi, R.; Oanţă-Marghitu, R.; Calligaro, T.

2016-03-01

This paper reports the archaeometric investigations of 418 loose garnets from Pietroasa and Cluj-Someşeni treasures and Apahida II and III princely grave inventories (5th century AD). The chemical composition of the gems was determined by external beam micro-PIXE technique at the AGLAE accelerator of C2RMF, Paris, France. Complementary observations made by Optical Microscopy revealed details on the gemstones cutting and polishing and permitted to identify certain mineral inclusions. The compositional results evidenced several types of garnets from the pyralspite series, suggesting distinct provenances for these Early Medieval gems.

High-spin europium and gadolinium centers in yttrium-aluminum garnet

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Potapov, A. P.; Asatryan, G. R.; Uspenskaya, Yu. A.; Petrosyan, A. G.; Fokin, A. V.

2016-08-01

Electron-spin resonance spectra of Eu2+ and Gd3+ centers substituting Y3+ ions in single-crystal yttrium-aluminum garnet have been studied and the parameters of their rhombic spin Hamiltonian have been determined. The fine-structure parameters of the above ions have been calculated in the superposition model disregarding changes in the angular coordinates of the ligand environment of the impurity defect thus demonstrating the necessity of taking these changes into account.

Deeply subducted continental fragments - Part 1: Fracturing, dissolution-precipitation, and diffusion processes recorded by garnet textures of the central Sesia Zone (western Italian Alps)

NASA Astrophysics Data System (ADS)

Giuntoli, Francesco; Lanari, Pierre; Engi, Martin

2018-02-01

Contiguous continental high-pressure terranes in orogens offer insight into deep recycling and transformation processes that occur in subduction zones. These remain poorly understood, and currently debated ideas need testing. The approach we chose is to investigate, in detail, the record in suitable rock samples that preserve textures and robust mineral assemblages that withstood overprinting during exhumation. We document complex garnet zoning in eclogitic mica schists from the Sesia Zone (western Italian Alps). These retain evidence of two orogenic cycles and provide detailed insight into resorption, growth, and diffusion processes induced by fluid pulses in high-pressure conditions. We analysed local textures and garnet compositional patterns, which turned out remarkably complex. By combining these with thermodynamic modelling, we could unravel and quantify repeated fluid-rock interaction processes. Garnet shows low-Ca porphyroclastic cores that were stable under (Permian) granulite facies conditions. The series of rims that surround these cores provide insight into the subsequent evolution: the first garnet rim that surrounds the pre-Alpine granulite facies core in one sample indicates that pre-Alpine amphibolite facies metamorphism followed the granulite facies event. In all samples documented, cores show lobate edges and preserve inner fractures, which are sealed by high-Ca garnet that reflects high-pressure Alpine conditions. These observations suggest that during early stages of subduction, before hydration of the granulites, brittle failure of garnet occurred, indicating high strain rates that may be due to seismic failure. Several Alpine rims show conspicuous textures indicative of interaction with hydrous fluid: (a) resorption-dominated textures produced lobate edges, at the expense of the outer part of the granulite core; (b) peninsulas and atoll garnet are the result of replacement reactions; and (c) spatially limited resorption and enhanced transport

50 MeV, Li{sup 3+} - ion irradiation effect on magnetic ordering of Y{sup 3+} - substituted yttrium iron garnet

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

Sharma, P. U.; Zankat, K. B.; Dolia, S. N.

2016-05-06

This communication presents the effect of non-magnetic Y{sup 3+} ions substitution for magnetic Fe{sup 3+} ions and 50 MeV, Li{sup 3+} ion irradiation (fluence: 5 × 10{sup 13} ions/cm{sup 2}) on magnetic ordering and Neel temperature of Y{sub 3+x}Fe{sub 5-x}O{sub 12} (x = 0.0, 0.2, 0.4 and 0.6) garnet system, studied by means of X-ray powder diffractometry and thermal variation of low field (0.5 Oe) ac susceptibility measurements. The un-irradiated compositions exhibit normal ferrimagnetic behavior with decrease in transition temperature (T{sub N}) on increasing Y{sup 3+}-concentration (x). The irradiated counterparts are characterized by tailing effect indicative of non-uniform effect of irradiationmore » and lower value of T{sub N}. The results have been discussed based on the weakening of magnetic exchange interactions and cumulative effect of redistribution of cations and fractional creation of localized paramagnetic centers resulting from swift heavy ion irradiation. The Neel temperatures and exchange integrals have been calculated theoretically.« less

Majorite-Garnet Partitioning of the Highly Siderophile Elements: New Results and Application to Mars

NASA Technical Reports Server (NTRS)

Danielson, L. R.; Righter, K.; Waeselmann, N.; Humayun, M.

2015-01-01

HSE and Os isotopes are used to constrain processes such as accretion, mantle evolution, crustal recycling, and core-mantle mixing, and to constrain the timing and depth of differentiation of Mars. Although showed that the HSE contents of the martian mantle could have been established by metal-silicate equilibrium in early Mars, the role of a cooling magma ocean and associated crystallization in further fractionating the HSEs is unclear. Garnet is thought to have played an important role in controlling trace element concentrations in the martian mantle reservoirs. However, testing these models, including Os isotopes, has been hindered by a dearth of partitioning data for the HSE in deep mantle phases - majorite, wadsleyite, ringwoodite, akimotoite - that may be present in the martian mantle. We examine the partitioning behavior of HSEs between majorite garnet (gt), olivine (oliv), and silicate liquid (melt).

MgSiO3-FeSiO3-Al2O3 in the Earth's lower mantle: Perovskite and garnet at 1200 km depth

NASA Technical Reports Server (NTRS)

O'Neill, Bridget; Jeanloz, Raymond

1994-01-01

Natural pyroxene and garnet starting material are used to study the effects of joint Fe and Al substitution into MgSiO3 perovskite at approxmiately 50 GPa. Garnet is found to coexist with perovskite in samples containing both Fe and Al to pressures occurring deep into the lower mantel (approximately 1200 km depth). The volume of the perovskite unit cell is V(sub o(Angstrom(exp 3)) = 162.59 + 5.95x(sub FeSiO3) + 10.80x(sub Al2O3) with aluminum causing a significant increase in the distortion from the ideal cubic cell. On the basis of a proposed extension of the MgSiO3-Al2O3 high-pressure phase diagram toward FeSiO3, Fe is shown to partition preferentially into the garnet phase. The stability of garnet deep into the lower mantel may hinder the penetration of subducted slabs below the transition zone.

Garnet Ring Measurements for the Fermilab Booster 2nd Harmonic Cavity

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

Kuharik, J.; Dey, J.; Duel, K.

A perpendicularly biased tuneable 2nd harmonic cavity is being constructed for use in the Fermilab Booster. The cavity's tuner uses National Magnetics AL800 garnet as the tuning media. For quality control, the magnetic properties of the material and the uniformity of the properties within the tuner must be assessed. We describe two tests which are performed on the rings and on their corresponding witness samples.

Neodymium:yttrium-aluminum-garnet laser fusion of endarterectomy flaps.

PubMed

Humphrey, P W; Slocum, M M; Loy, T S; Silver, D

1995-07-01

This study evaluated the efficacy of neodymium:yttrium-aluminum-garnet laser welding of flaps in canine arteries and in securing the distal flap during human carotid endarterectomy. Endarterectomy flaps were created in both common carotid and both common femoral arteries in 12 dogs. The flaps were repaired with either the neodymium:yttrium-aluminum-garnet laser or with 6-0 polypropylene sutures. The arteries were removed after duplex scanning at either 7 or 28 days. Eighteen high carotid endarterectomy flaps in 16 patients have been subsequently secured with the laser welding technique. Laser repairs (125 +/- 19 joule) of the canine arteries were completed more quickly than suture repairs (mean 25 seconds vs 135 seconds, respectively; p < 0.04). Duplex ultrasonography revealed no discernable differences between the two groups of arteries. Arteries studied at 7 days revealed three microscopic flaps (two suture, one laser), more subintimal fibroblastic proliferation in suture than laser-repaired carotid arteries (3: 1, p = 0.0530), and similar amounts of inflammation in suture- and laser-repaired arteries. Arteries studied at 28 days revealed one microscopic intimal flap (suture-repaired); equal fibroblastic and inflammatory responses in suture- and laser-repaired vessels; and no evidence of laser thermal injury. Eighteen carotid endarterectomy flaps have been successfully fused with no immediate or long-term complications in 16 patients (follow-up of 0 to 24 months). Laser fusion appears to be a safe and effective method for securing distal carotid endarterectomy flaps.

Evaluation of stability region for scandium-containing rare-earth garnet single crystals and their congruent-melting compositions

NASA Astrophysics Data System (ADS)

Kaurova, I. A.; Domoroshchina, E. N.; Kuz'micheva, G. M.; Rybakov, V. B.

2017-06-01

Single crystals of scandium-containing rare-earth garnets in system R-Sc-C-O (R3+=Y, Gd; C3+=Al, Ga) have been grown by the Czochralski technique. X-ray diffraction analysis has been used to refine crystal compositions. The fundamental difference between the melt compositions and compositions of grown crystals has been found (except for compositions of congruent-melting compounds, CMC). The specific features of garnet solid solution formation have been established and the ternary diagrams with real or hypothetical phases have been built. The dinamics of coordination polyhedra changes with the formation of substitutional solid solutions have been proposed based on the mathematical modeling and experimental data. Possible existence of CMC with garnet structure in different systems as well as limit content of Sc ions in dodecahedral and octahedral sites prior to their partial substitution of ions, located in other sites, have been evaluated. It was established that the redistribution of cations over crystallographic sites (antistructural point defects) due to system self-organization to maintain its stability may be accompanied by cation ordering and the symmetry change of individual polyhedrons and/or the whole crystal.

Eclogitization on the way up: Lu-Hf garnet chronology of metasomatic ultrahigh-pressure rocks from the Western Gneiss Complex, Norway

NASA Astrophysics Data System (ADS)

Cutts, J.; Smit, M. A.; Vrijmoed, J. C.

2016-12-01

The Western Gneiss Complex (WGC) is a fragment of continental crust that was subjected to high- and ultrahigh pressure (HP; UHP) conditions as a result of Caledonian continental collision (420-400 Ma). Most eclogite lenses and related high-pressure rocks have yielded petrological and chronological results that are consistent with a generalized model of Caledonian continental subduction. A distinct suite of eclogitic rocks - metasomatized (`Caledonized') Fe-Ti meta-peridotites - indicate extreme pressure conditions that do not fit the regional field gradient. The timing of these excursions is critical to their interpretation; however, so far limited age constraints exist for these rocks. In this study, we subject one such rock - the Magerøy orthopyroxene eclogite on the island of Otrøy - to Lu-Hf garnet chronology; a method that provides precise and robust data for garnet even at extreme temperatures. Conventional barometry indicates equilibration of the main garnet-bearing assemblage at c. 4.3 GPa and garnet geochronology yielded a date of c. 390 Ma. This result overlaps with Sm-Nd garnet and U-Pb zircon ages from the nearby diamond-bearing Svartberget peridotite body and leucosomes in its host gneiss. However, the age is ≥ 10 Ma younger than age data for most other eclogite lenses in WGC and corresponds to a time when the terrane was already exhumed to 30-35 km depth. The discrepancy in P-T-t evolution between the bulk of the WGC, and the (ultra-) mafic rocks at Magerøy and Svartberget indicates that the latter rocks reflect localized fluid-induced re-equilibration at pressures higher than lithostatic. The new data provide new support for the occurrence of this phenomenon in subducted continental crust undergoing exhumation and partial melting.

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.

P-T Path and Nd-isotopes of Garnet Pyroxenite Xenoliths From Salt Lake Crater, Oahu

NASA Astrophysics Data System (ADS)

Ichitsubo, N.; Takahashi, E.; Clague, D. A.

2001-12-01

Abundant garnet pyroxenite and spinel lherzolite xenoliths are found in Salt Lake Crater (SLC) in Oahu, Hawaii [Jackson and Wright, 1970]. The SLC pyroxenite suite xenoliths (olivine-poor type) have complex exsolution textures that were probably formed during a slow cooling. In this study, we used digital image software to obtain modal data of exsolved phases in the host pyroxene using backscattered electron images (BEIs). The abundances of the exsolved phases were multiplied by the phase compositions determined by electron probe micro-analyzer (EPMA) to reconstruct pyroxene compositions prior to exsolution. In order to evaluate the error in this calculation, we recalculated the reconstructed pyroxene compositions using the different pyroxene pairs. Reconstructed clinopyroxenes in each sample have almost no variations (MgO, CaO +/-1wt %, FeO +/-0.5wt % and the other oxides ~+/-0.1wt %). Reconstructed orthopyroxenes are more variable in MgO, CaO (+/-2wt %) and FeO (+/-1wt %) than reconstructed clinopyroxenes, but the other oxides have only limited variations ( ~+/-0.5wt %). These compositions were used to calculate igneous stage (magmatic) P-T conditions based on the geothermometers and geobarometers of Wells [1977] and Brey and Kohler [1990] Following assumptions are made: (1) the reconstructed pyroxene compositions are the final record in the primary igneous stage, and (2) cores of the largest garnet grains in each sample record the primary igneous stage composition.. The recalculation using the different pairs of reconstructed pyroxenes show the uncertainty to be +/- 30° C and 0.1 GPa. These appear to be small compared to the large intrinsic errors of geothermometer and geobarometers (+/-20° -35° C and +/- 0.3-0.5 GPa). Estimated P-T conditions for garnet pyroxenites are 1.5-2.2 GPa, 1000° -1100° C in the final reequilibration stage and 2.2-2.6 GPa (at maximum), 1150° -1300° C (at minimum) in the igneous stage. The all samples show ca. 200° C cooling and

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

Pantzas, Konstantinos, E-mail: konstantinos.pantzas@lpn.cnrs.fr; Institut P', CNRS-Université de Poitiers - ENSMA - UPR 3346, SP2MI - Téléport 2 Bd Marie Pierre Curie, B.P. 30179, F-86962, Futuroscope Chasseneuil Cedex; Patriarche, Gilles

Direct bonding of yttrium iron garnet (YIG) on silicon without the use of an intermediate bonding layer is demonstrated and characterized using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy. During the bonding experiment, the garnet is reduced in the presence of oxide-free silicon. As a result, a 5 nm thick SiO{sub 2}/amorphous-YIG bilayer is formed and welds the garnet to silicon.

Timescales between mantle metasomatism and kimberlite ascent indicated by diffusion profiles in garnet crystals from peridotite xenoliths

NASA Astrophysics Data System (ADS)

Jollands, Michael C.; Hanger, Brendan J.; Yaxley, Gregory M.; Hermann, Jörg; Kilburn, Matthew R.

2018-01-01

Rare garnet crystals from a peridotite xenolith from the Wesselton kimberlite, South Africa, have distinct zones related to two separate episodes of mantle metasomatism. The garnet cores were firstly depleted through melt extraction, then equilibrated during metasomatism by a potentially diamond-forming carbonate-bearing or proto-kimberlitic fluid at 1100-1300 °C and 4.5-5.5 GPa. The garnet rim chemistry, in contrast, is consistent with later overgrowth in equilibrium with a kimberlite at around 1025 ± 25 °C and 4.2 ± 0.5 GPa. This suggests that the rock was physically moved upwards by up to tens of kilometres between the two metasomatic episodes. Preserved high Ca, Al and Cr contents in orthopyroxenes suggest this uplift was tectonic, rather than magmatic. Diffusion profiles were measured over the transitions between garnet cores and rims using electron microprobe (Mg, Ca, Fe for modelling, plus Cr, Mn, Ti, Na, Al) and nano Secondary Ion Mass Spectrometry (NanoSIMS; 89Y, along with 23Na, Ca, Cr, Fe, Mn and Ti) analyses. The short profile lengths (generally <10 μm) and low Y concentrations (0.2-60 ppm) make the NanoSIMS approach preferable. Diffusion profiles at the interface between the zones yield constraints on the timescale between the second metasomatic event and eruption of the kimberlite magma that brought the xenolith to the surface. The time taken to form the diffusion profiles is on the order of 25 days to 400 yr, primarily based on modelling of Y diffusion along with Ca, Fe and Mg (multicomponent diffusion) profiles. These timescales are too long to be produced by the interaction of the mantle xenolith with the host kimberlite magma during a single-stage ascent to the crust (hours to days). The samples offer a rare opportunity to study metasomatic processes associated with failed eruption attempts in the cratonic lithosphere.

Effect of recording condition on the diffraction efficiency of magnetic hologram with magnetic garnet films

NASA Astrophysics Data System (ADS)

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

2014-09-01

A holographic memory has been attracting attention as recording media with high recording density and high data transfer rate. We have studied the magnetic garnets as a rewritable and long life media for magnetic holography. However, since the signal intensity of reconstructed image was relatively low, the effects of recording conditions on the diffraction efficiency of magnetic hologram were investigated with experiments and the numerical simulation using COMSOL multi-physics. The diffraction efficiency tends to decrease as increasing the spatial frequency, and the use of short pulse laser with the pulse width of 50 ps was found to be effective to achieve high diffraction efficiency. This suggests that the formation of clear magnetic fringe similar to interference pattern can be obtained by the use of short pulse laser since undesirable heat diffusion during radiation does not occur. On the other hand, the diffraction efficiency increased as increasing the film thickness up to 3.1 μm but was saturated in the garnet film thicker than 3.1 μm in the case of spatial frequency of 1500 line pair/mm. The numerical simulation showed that the effective depth of magnetic fringe was limited about 1.8 μm irrespective of the garnet film thickness because the fringes were connected by thermal diffusion near the surface of the film, and the effective depth is limited due to this connection of the magnetic fringe. Avoiding this fringe connection, much higher diffraction efficiency will be achieved.

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

Application of domain structures elements of ferrite-garnet films for transport of magnetic microparticles

NASA Astrophysics Data System (ADS)

Gorobets, Yu. I.; Dzhezherya, Yu. I.; Melnichuk, I. A.; Cherepov, S. V.; Kuz', A. P.

2010-12-01

The physical background of the device for the transportation of magnetic microparticles which is using a domain structure of garnete-ferrite films with easy-plane anisotropy are developed and experimentally proved in the present paper. The proposed device can be used in microbiology, medicine, and genetic engineering.

Sulfides in the Garnet Pyroxenite xenoliths from Oahu, Hawaii

NASA Astrophysics Data System (ADS)

Sen, I. S.; Sen, G.; Bizimis, M.

2007-12-01

Oahu is known for its garnet bearing xenoliths that occur in the Honolulu Volcanics. Clinopyroxene is the dominant minerals of these rocks, and modes of other silicate minerals - orthopyroxene, olivine, garnet, amphibole, and phlogopite vary considerably. Ilmenite and Spinels of diverse variety also occur (Keshav et al. 2007, J. Petrol.). In this report we present new electron microprobe and LA-ICPMS data on the sulfides that are always present in these xenoliths although they make up only trace amounts. In terms of morphology and mode of occurrence the sulfides can be divided fundamentally into two types - Type I occurs as poikilitic inclusions in the silicate phases mostly in clinopyroxene and Type II occurs in the interstitial spaces between the silicates, along grain boundaries and along cracks within individual silicate grains. Sizes of both types vary considerably. Type I sulfides are generally globular and appear to have formed from immiscible sulfide melts that got enclosed by the silicate minerals that grew from the main body of silicate melt. Keshav et al. (2007) estimate the average solidus temperatures of garnet pyroxenites from Oahu to range from 1215 to 1600°C (average 1325°C) at 3-5 GPa. Therefore, the Type I sulfides are high temperature sulfides that formed above the silicate solidus. Type II sulfides take various forms - from vein-like to dendritic. Compositionally, both types include Ni rich pyrrhotites (Ni content varies from 3-5 wt%) and monosulfide solid solutions(MSS). The MSS are divided into Ni rich MSS containing as much as 20 wt% of Ni, the average is 15 wt% while the Ni poor MSS has 5-9 wt% of Ni in it. We have limited data on PGE so far but the Type II sulfides have a very low PGE content. Two recent papers have noted that Hawaiian plume-derived shield tholeiites are too rich in Ni for a given SiO2% to be produced by partial melting of a peridotite and called for an unusual Ni-rich pyroxenite source in which the large Ni content is

Y3Fe5O12 nanoparticulate garnet ferrites: Comprehensive study on the synthesis and characterization fabricated by various routes

NASA Astrophysics Data System (ADS)

Niaz Akhtar, Majid; Azhar Khan, Muhammad; Ahmad, Mukhtar; Murtaza, G.; Raza, Rizwan; Shaukat, S. F.; Asif, M. H.; Nasir, Nadeem; Abbas, Ghazanfar; Nazir, M. S.; Raza, M. R.

2014-11-01

The effects of synthesis methods such as sol-gel (SG), self combustion (SC) and modified conventional mixed oxide (MCMO) on the structure, morphology and magnetic properties of the (Y3Fe5O12) garnet ferrites have been studied in the present work. The samples of Y3Fe5O12 were sintered at 950 °C and 1150 °C (by SG and SC methods). For MCMO route the sintering was done at 1350 °C for 6 h. Synthesized samples prepared by various routes were investigated using X-ray diffraction (XRD) analysis, Field emission scanning electron microscopy (FESEM), Impedance network analyzer and transmission electron microscopy (TEM). The structural analysis reveals that the samples are of single phase structure and shows variations in the particle sizes and cells volumes, prepared by various routes. FESEM and TEM images depict that grain size increases with the increase of sintering temperature from 40 nm to 100 nm.Magnetic measurements reveal that garnet ferrite synthesized by sol gel method has high initial permeability (60.22) and low magnetic loss (0.0004) as compared to other garnet ferrite samples, which were synthesized by self combustion and MCMO methods. The M-H loops exhibit very low coercivity which enables the use of these materials in relays and switching devices fabrications. Thus, the garnet nanoferrites with low magnetic loss prepared by different methods may open new horizon for electronic industry for their use in high frequency applications.

Pan-African metamorphic evolution in the southern Yaounde Group (Oubanguide Complex, Cameroon) as revealed by EMP-monazite dating and thermobarometry of garnet metapelites

NASA Astrophysics Data System (ADS)

Owona, Sebastien; Schulz, Bernhard; Ratschbacher, Lothar; Mvondo Ondoa, Joseph; Ekodeck, Georges E.; Tchoua, Félix M.; Affaton, Pascal

2011-01-01

Garnet-bearing micaschists and paragneisses of the Yaounde Group in the Pan-African Central African Orogenic Belt in Cameroon underwent a polyphase structural evolution with the deformation stages D 1-D 2, D 3 and D 4. The garnet-bearing assemblages crystallized in course of the deformation stage D 1-D 2 which led to the formation of the regional main foliation S 2. In XCa- XMg coordinates one can distinguish several zonation trends in the garnet porphyroblasts. Zonation trends with increasing XMg and variably decreasing XCa signalize a garnet growth during prograde metamorphism. Intermineral microstructures provided criteria for local equilibria and a structurally controlled application of geothermobarometers based on cation exchange and net transfer reactions. The syndeformational P- T path sections calculated from cores and rims of garnets in individual samples partly overlap and align along clockwise P- T trends. The P- T evolution started at ˜450 °C/7 kbar, passed high-pressure conditions at 11-12 kbar at variable temperatures (600-700 °C) and involved a marked decompression toward 6-7 kbar at high temperatures (700-750 °C). Th-U-Pb dating of metamorphic monazite by electron microprobe (EMP-CHIME method) in eight samples revealed a single period of crystallization between 613 ± 33 Ma and 586 ± 15 Ma. The EMP-monazite age populations between 613 ± 33 Ma enclosed in garnet and 605 ± 12 Ma in the matrix apparently bracket the high temperature-intermediate pressure stage at the end of the prograde P- T path. The younger monazites crystallized still at amphibolite-facies conditions during subsequent retrogression. The Pan-African overall clockwise P- T evolution in the Yaounde Group with its syndeformational high pressure stages and marked pressure variations is typical of the parts of orogens which underwent contractional crustal thickening by stacking of nappe units during continental collision and/or during subduction-related accretionary processes.

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.

Garnet lherzolites from Louwrensia, Namibia: Bulk composition and P/T relations

USGS Publications Warehouse

Boyd, F.R.; Pearson, D.G.; Hoal, Karin O.; Hoal, B.G.; Nixon, P.H.; Kingston, M.J.; Mertzman, S.A.

2004-01-01

Bulk, mineral and trace element analyses of garnet lherzolite xenoliths from the Louwrensia kimberlite pipe, south-central Namibia, together with previously published Re-Os isotopic data [Chem. Geol. (2004)], form the most extensive set of chemical data for off-craton suites from southern Africa. The Louwrensia suite is similar to those from the Kaapvaal craton in that it includes both predominantly coarse-grained, equant-textured peridotites characterised by equilibration temperatures 1200 ??C. Redepletion ages range back to 2.1 Gy, concordant with the age of the crustal basement and about 1 Gy younger than the older peridotites of the adjacent Kaapvaal craton root. The coarse, low-temperature Louwrensia peridotites have an average Mg number for olivine of 91.6 in comparison to 92.6 for low-temperature peridotites from the craton. Orthopyroxene content averages 24 wt.% with a range of 11-40 wt.% for Louwrensia low-temperature peridotites, in comparison to a mean of 31.5 wt.% and a range of 11-44 wt.% for low-temperature peridotites from the Kaapvaal craton. Other major, minor and trace element concentrations in minerals forming Louwrensia lherzolites are more similar to values in corresponding Kaapvaal peridotite minerals than to those in lithospheric peridotites of Phanerozoic age as represented by off-craton basalt-hosted xenoliths and orogenic peridotites. Proportions of clinopyroxene and garnet in both the Louwrensia and Kaapvaal lherzolites overlap in the range up to 10 wt.% forming a trend extending towards pyrolite composition. Disequilibrium element partitioning between clinopyroxene and garnet for some incompatible trace elements is evidence that some of the trend is caused by enrichment following depletion. The disequilibrium is interpreted to have been caused by relatively recent growth of diopside, as previously suggested for cratonic peridotites. Attempts to constrain the depth of melting required to produce the Louwrensia peridotites suggests

Garnet peridotite xenoliths in a Montana, U.S.A., kimberlite

USGS Publications Warehouse

Carter, Hearn B.; Boyd, F.R.

1975-01-01

Within a swarm of late middle Eocene subsilicic-alkalic diatremes, one diatreme 270 by 370 m and an associated dike contain common xenoliths of granulite and rare xenoliths of spinel peridotite and garnet peridotite. Six garnet lherzolite xenoliths have been found and these show a range of textures. Four are granular, and two are intensely sheared. Phlogopite is absent from the intensely sheared xenoliths and is thought to be primary in part in the granular xenoliths. Estimated temperatures and depths of equilibration of xenolith pyroxenes range from 920??C, 106 km (32 kbar) to 1315??C, 148 km (47 kbar). The xenoliths show increasing amounts of deformation with greater inferred depths of origin. The temperature-depth points suggest a segment of an Eocene geotherm for Montana which is similar in slope to the steep portion of the pyroxene-determined Lesotho geotherm (Boyd and Nixon, this volume) and is considerably steeper than typical calculated shield and continental geotherms at present. The steep trend could be a result of plate-tectonic shearing and magma ascension within an Eocene low-velocity zone. Preservation of intensely sheared textures requires rapid transport of material from about 150 km depth during active deformation of relatively dry rock. The occurrence of monticellite peridotite in this kimberlite diatreme suggests that magmas which crystallized to monticellite peridotite at relatively shallow depth could be one of the primitive types of kimberlite magma. ?? 1975.

Pressures of skarn formation at Casting Copper NV, USA, based on Raman spectroscopy and elastic modeling of apatite inclusions in garnet

NASA Astrophysics Data System (ADS)

Steele-MacInnis, M.; Barkoff, D. W.; Ashley, K.

2017-12-01

Thermobarometry of metasomatic rocks is commonly challenging, owing to the high variance of hydrothermal mineral assemblages, thermodynamic disequilibrium and overprinting by subsequent hydrothermal episodes. Here, we estimate formation pressures of a Cu-Fe-sulfide-bearing andradite-diopside skarn deposit at Casting Copper (Yerington district, NV) using Raman spectroscopy and elastic modeling of apatite inclusions in garnet. Andradite garnet from the Casting Copper skarn contains inclusions of hydroxyl-fluorapatite, calcite, hematite, magnetite, and ilmenite. Raman spectroscopy reveals that the apatite inclusions are predominantly under tension of -23 to -123 MPa at ambient conditions. Elastic modeling of apatite-in-garnet suggest entrapment occurred at 10 to 115 MPa, assuming a trapping temperature of 400 °C, which is consistent with paleodepth estimates of 2-3 km. These results provide independent constraints on the conditions of hydrothermal skarn formation at Casting Copper, and suggest that this approach may be applied to other, less-constrained skarn systems.

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

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

High Density Ion Implanted Contiguous Disk Bubble Technology.

DTIC Science & Technology

1987-10-31

magnetic garnet films were grown by liquid phase epitaxy ( LPE ) from a Bi 20 3-PbO flux system. Films were grown with a 600C to 700C supercooling at...Matsutera, "Large Magnetic Anisotropy Change Induced By Hydrogen Ion Implantation In Europium Iron Garnet LPE Films ", J. of Magnetism and Magnetic...summarizes the design, development and growth of various bubble garnet films in our facility, to be used in the fabrication of high density bubble storage

An occurrence of metastable cristobalite in high-pressure garnet Granulite

USGS Publications Warehouse

Darling, R.S.; Chou, I.-Ming; Bodnar, R.J.

1997-01-01

High-pressure (0.8 gigapascals) granulite facies garnet from Gore Mountain, New York, hosts multiple solid inclusions containing the low- pressure silica polymorph cristobalite along with albite and minor ilmenite. Identification of cristobalite is based on Raman spectra, electron microprobe analysis, and microthermometric measurements on the ??/?? phase transformation. The cristobalite plus albite inclusions may have originated as small, trapped samples of hydrous sodium-aluminum-siliceous melt. Diffusive loss of water from these inclusions under isothermal, isochoric conditions may have resulted in a large enough internal pressure decrease to promote the metastable crystallization of cristobalite.

Bluish-White Luminescence in Rare-Earth-Free Vanadate Garnet Phosphors: Structural Characterization of LiCa3MV3O12 (M = Zn and Mg).

PubMed

Hasegawa, Takuya; Abe, Yusuke; Koizumi, Atsuya; Ueda, Tadaharu; Toda, Kenji; Sato, Mineo

2018-01-16

Extensive attention has been focused toward studies on inexpensive and rare-earth-free garnet-structure vanadate phosphors, which do not have a low optical absorption due to the luminescence color being easily controlled by its high composition flexibility. However, bluish emission phosphors with a high quantum efficiency have not been found until now. In this study, we successfully discovered bluish-white emitting, garnet structure-based LiCa 3 MV 3 O 12 (M = Zn and Mg) phosphors with a high quantum efficiency, and the detailed crystal structure was refined by the Rietveld analysis technique. These phosphors exhibit a broad-band emission spectra peak at 481 nm under near UV-light excitation at 341 nm, indicating no clear difference in the emission and excitation spectra. A very compact tetrahedral [VO 4 ] unit is observed in the LiCa 3 MV 3 O 12 (M = Zn and Mg) phosphors, which is not seen in other conventional garnet compounds, and generates a bluish-white emission. In addition, these phosphors exhibit high quantum efficiencies of 40.1% (M = Zn) and 44.0% (M = Mg), respectively. Therefore, these vanadate garnet phosphors can provide a new blue color source for LED devices.

Alternations in burial and exhumation along the Selimiye (Kayabükü) shear zone in the Menderes Massif from detailed garnet pressure-temperature paths

NASA Astrophysics Data System (ADS)

Kelly, E. D.; Atakturk, K. R.; Catlos, E. J.; Lizzadro-McPherson, D. J.; Cemen, I.; Lovera, O. M.

2015-12-01

Pressure-temperature (P-T) paths derived from garnet chemical zoning and supported by thermal modeling record alternating burial and exhumation during Main Menderes Metamorphism in western Turkey. We studied six rocks along the Selimiye (Kayabükü) shear zone, three from the footwall (Çine nappe) and three from the hanging wall (Selimiye nappe). The shear zone bounds the southern Menderes Massif metamorphic core complex and has been suggested to record compression followed by extension. The rocks are lower-amphibolite facies garnet-bearing metapelites with nearly identical mineral suites. Retrograde overprinting hinders classical thermobarometry; to overcome this, preserved chemical zoning in garnet combined with a G-minimization approach was used to construct detailed P-T paths (e.g., 50 points in some paths). During continuous temperature increase, the Çine nappe paths show increasing, decreasing, and then increasing pressure (an N-shaped path) ending at 7-8 kbar and ~565-590 °C. The Selimiye nappe paths show a single increase in P-T ending at ~7.3 kbar and ~580 °C. Similar bulk-rock compositions in all samples and the separation by the shear zone suggest that garnets grew during distinct events in each nappe. The timing of garnet growth, and thus the P-T paths, is currently undetermined, as monazite inclusions in garnet appear secondary and complicated by excess common Pb. The Çine nappe N-shaped path describes alternations in burial and exhumation, possibly due to thrust motion along the shear zone. To demonstrate the physical plausibility of the P-T paths, a 2-D finite difference solution to the diffusion-advection equation was applied. The results of the thermal modeling suggest that thrusting, denudation, and renewed thrusting would produce similar changes in P-T to the N-shaped path. Thus, the Çine nappe N-shaped P-T path appears to record a gap in thrust motion along the Selimiye (Kayabükü) shear zone prior to ultimate unroofing of the massif.

The solubility and site preference of Fe{sup 3+} in Li{sub 7−3x}Fe{sub x}La{sub 3}Zr{sub 2}O{sub 12} garnets

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

Rettenwander, D., E-mail: daniel.rettenwander@sbg.ac.at; Geiger, C.A.; Tribus, M.

2015-10-15

A series of Fe{sup 3+}-bearing Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and {sup 57}Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe{sup 3+} pfu could be incorporated in Li{sub 7−3x}Fe{sub x}La{sub 3}Zr{sub 2}O{sub 12} garnet solid solutions. At Fe{sup 3+} concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses withmore » starting materials having intended Fe{sup 3+} contents lower than 0.52 Fe{sup 3+} pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a{sub 0}, for all solid-solution garnets is similar with a value of a{sub 0}≈12.98 Å regardless of the amount of Fe{sup 3+}. {sup 57}Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO{sub 3} in syntheses with Fe{sup 3+} contents greater than 0.16 Fe{sup 3+} pfu. The composition of different phase pure Li{sub 7−3x}Fe{sub x}La{sub 3}Zr{sub 2}O{sub 12} garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li{sub 6.89}Fe{sub 0.03}La{sub 3.05}Zr{sub 2.01}O{sub 12}, Li{sub 6.66}Fe{sub 0.06}La{sub 3.06}Zr{sub 2.01}O{sub 12}, Li{sub 6.54}Fe{sub 0.12}La{sub 3.01}Zr{sub 1.98}O{sub 12}, and Li{sub 6.19}Fe{sub 0.19}La{sub 3.02}Zr{sub 2.04}O{sub 12}. The {sup 57}Fe Mössbauer spectrum of cubic Li{sub 6.54}Fe{sub 0.12}La{sub 3.01}Zr{sub 1.98}O{sub 12} garnet indicates that most Fe{sup 3+} occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe{sup 3+} in

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.

Lu/Hf dating of garnet constrains timing of metamorphism and deformation, Prince Rupert Area, British Columbia

NASA Astrophysics Data System (ADS)

Wolf, D. E.; Andronicos, C. L.; Vervoort, J. D.; Mansfield, M.

2008-12-01

We present new Lu-Hf garnet ages that constrain the timing of deformation and metamorphism in the Western Metamorphic Belt (WMB), near Prince Rupert, British Columbia. We examined four samples of grt- bearing schist collected within the aureole to the Ecstall Pluton in the WMB. Garnets were separated from these rocks and dated using the Lu-Hf method at Washington State University. We determined geologically meaningful ages from three of these samples. The tectonic history of the Prince Rupert area is marked by phases of transpressive deformation, which included the development of crustal scale strike-slip shear zones and thrust slices with inverted metamorphic gradients. The Grenville Channel shear zone (GCSZ) is a crustal-scale sinistral-slip shear zone over 300 km long that strikes NW with a steep dip and shallow lineation. The GCSZ cuts through the WMB, a ductile fold and thrust belt composed of gneiss and schist with an inverted metamorphic sequence. Index minerals range from: chl and chd-grade units at the bottom of the sequence, str-bearing rocks in the middle, and ky-grt schist and local migmatites at the top of the thrust stack. The WMB was deformed and intruded by the Ecstall Pluton after the inverted metamorphic sequence had formed. The Ecstall is an epi-bearing hbl-qtz diorite emplaced between 91 and 93.5±1 Ma (Butler et al., 2001). Sample G-16A from Kumeleon Inlet (W of the Ecstall pluton) is a schist containing grt+biot+musc+qtz+epi+amph+sil, with small (<1 mm) euhedral grt. Kinematic indicators, including grt porphyroclasts, indicate left-lateral, top to the south, strike-slip shear. This sample yields a Lu-Hf age of 102±3.6 Ma (2σ, MSWD=1.5) based on seven grt and three whole-rock fractions, and a P-T estimate of 5.5±1 kbar and 590°±50° C from garnet-biotite thermobarometry. Sample 98-114A from Ridley Island (NW of Ecstall pluton) is a schist containing musc+biot+qtz+grt+ky+plag+chl+ill and with syn-tectonic euhedral garnet (1 cm). Grt

Fabrication of Material and Devices for Very High Density Information Storage.

DTIC Science & Technology

1986-11-24

IKawanishi, "Miagnetic anid opticeal propert I e of Co. I It substituted garnet films p~rep~ared by the lPE niethod and its ipplication to hlermtmt"Ile( i...medium. Highly Bi-substituted garnet films on glass and G( substrates were successfully RF sputtered and characterized by the group of M. Goni.1 The filns...writing due to the temperature dependence of the coercive force 11. Preparation of bismuth iron garnet films by ion bean sputtering onto GGG

Eclogites and garnet clinopyroxenites in the Anrakhai complex, Central Asian Orogenic Belt, Southern Kazakhstan: P-T evolution, protoliths and some geodynamic implications

NASA Astrophysics Data System (ADS)

Pilitsyna, Anfisa V.; Tretyakov, Andrey A.; Degtyarev, Kirill E.; Cuthbert, Simon J.; Batanova, Valentina G.; Kovalchuk, Elena V.

2018-03-01

The Anrakhai Metamorphic Complex (AMC), located in the SE part of the Chu-Ili Mountains of Southern Kazakhstan in the western part of Central Asian Orogenic Belt, exhibits occurrences of HP metamorphic rocks in the form of eclogites and garnet clinopyroxenites with peak metamorphic conditions of 750-850° and 15-19 kbar estimated with both conventional geothermobarometric methods and phase diagram modeling. P-T estimates as well as intimate field relations evidently imply a common metamorphic history for eclogites and garnet clinopyroxenites of the AMC. These high-pressure, medium temperature eclogite facies P-T conditions are indicative of a collision or subduction tectonic setting. Major and trace element geochemistry suggests that they probably had a common magmatic origin as part of a suite of differentiated tholeiitic intrusions. Furthermore, distinctive mineral and chemical compositions of these eclogites and garnet clinopyroxenites correspond to the Fe-Ti type of ultramafic rocks suggesting that they may have been derivatives of intraplate tholeiitic melts, introduced into continental crust before HP metamorphism.

Honeycomb-alumina supported garnet membrane: Composite electrolyte with low resistance and high strength for lithium metal batteries

NASA Astrophysics Data System (ADS)

Liu, Kai; Wang, Chang-An

2015-05-01

Li-ion ceramic electrolyte material is considered the key for advanced lithium metal batteries, and garnet-type oxides are promising ceramic electrolyte materials. To disentangle the thinness-strength dilemma in garnet-type Li6.4La3Zr1.4Ta0.6O12 (LLZTO) electrolyte, we designed and successfully synthesized a ceramic-ceramic composite electrolyte, i.e. a honeycomb-Al2O3 pellet supported LLZTO membrane. The honeycomb-Al2O3 pellet acts as a supporter to the thin LLZTO membrane and makes the whole composite electrolyte strong enough, while the straight holes in the Al2O3 supporter can be filled with liquid electrolyte and acts as channels for Li+ transportation. Such a composite design eliminates the concern over the LLZTO membrane's fragility, and keeps its good electrical property.

Local stress distribution around garnet inclusions during hydration of granulite in the Bergen Arcs, Norway

NASA Astrophysics Data System (ADS)

Centrella, Stephen; Vrijmoed, Johannes C.; Putnis, Andrew; Austrheim, Håkon

2017-04-01

The importance of heterogeneous stress and pressure distribution within a rock has been established over the last decades (see review in Tajčmanová et al., 2015). During a hydration reaction, depending on whether the system is open to mass transfer, the volume changes of the reaction may be accommodated by removing material into the fluid phase that leaves the system (Centrella et al., 2015; Centrella et al., 2016). The magnitudes and the spatial distribution of stress and pressure that evolve during such processes is largely unknown. We present here a natural example where a granulite is hydrated at amphibolite facies conditions from the Bergen Arcs in Norway. Granulitic garnet is associated with kyanite and quartz on one side, and amphibole-biotite on the other side. The first couple replaces the plagioclase of the granulite matrix whereas the second replaces the garnet. We use electron probe microanalysis (EPMA) and X-ray mapping to investigate the spatial and possible temporal relationships between these two parageneses. Gresens' analysis has been used to determine the mass balance and the local volume changes associated with the two reactions. The reaction to kyanite+quartz induces a loss in volume compared to the original plagioclase whereas the second reaction amphibole+biotite gains volume compared to the original garnet. The specific mass evolution associated with both reactions suggests a local mass balance probably associated with a single hydration event. Using the methodology of Vrijmoed & Podladchikov (2015) we test whether the microstructure may be partly related to the local stress heterogeneity around the garnet inclusion. We evaluate the phase assemblage and distribution at chemical equilibrium under a given input pressure field that can be computed with the Thermolab software. By varying the input pressure field using the Finite Element Method and comparing the resulting equilibrium assemblage to the real data an estimate of the local stress

COMPARATIVE EVALUATION OF R3f GARNET BEAD FILTRATION AND MULTIMEDIA FILTRATION SYSTEMS; FINAL REPORT

EPA Science Inventory

This report summarizes the results of tests conducted to date at the EPA T&E Facility on the R3f filtration system utilizing fine beads (such as garnet beads or glass beads) and a conventional multimedia filtration system. Both systems have been designed and built by Enprotec, a...

Magneto-optic current sensor

DOEpatents

Lanagan, Michael T.; Valsko-Vlasov, Vitalii K.; Fisher, Brandon L.; Welp, Ulrich

2003-10-07

An optical current transducer configured to sense current in the conductor is disclosed. The optical current transducer includes a light source and a polarizer that generates linearly polarized light received from a the light source. The light is communicated to a magneto-optic garnet that includes, among other elements, bismuth, iron and oxygen and is coupled to the conductor. The magneto-optic garnet is configured to rotate the polarization of the linearly polarized light received from the polarizer. The optical current transducer also includes an analyzer in optical communication with the magneto-optic garnet. The analyzer detects the rotation of the linearly polarized light caused by the magneto-optic garnet.

In Situ Measurements of the Post-Spinel and Post-Garnet Phase Boundaries in Pyrolite at 17-32 GPa and 1500-2400 K

NASA Astrophysics Data System (ADS)

Ye, Y.; Gu, C.; Shim, S. H.; Prakapenka, V.; Meng, Y.

2014-12-01

Recent seismic studies have revealed complex structures near 660-km depth. In order to understand the effects of composition and temperature, we measured the depth and Clapeyron slope of the post-spinel and post-garnet boundaries at the pressure-temperature conditions of 600-700 km depths in pyrolitic compositions: (1) MgO-Al2O3-SiO2 (MAS) and (2) CaO-MgO-Al2O3-SiO2-FeO (CMASF). Glass starting materials were mixed with either gold or platinum powder (10 wt%) for laser coupling and internal pressure scale. Cold compressed foils of the mixtures were loaded in the diamond-anvil cell together with Ar or KCl for thermal insulation and pressure transmission. X-ray diffraction patterns were measured for the samples in the diamond-anvil cell at in situ high pressure and high temperature combined with double side laser heating at beamlines 13-IDD (GSECARS) and 16-IDB (HPCAT) in the Advanced Photon Source. Within 5 to 8 minutes of heating, stable crystalline phase assemblages were formed and persisted with further heating for 20 to 30 minutes. A total of 160 heating cycles were conducted at different pressures and temperatures, providing tight constrains on the phase boundaries. Our data show that the post-spinel transition occurs at 23.6-24.5 GPa and 1850 K with a Clapeyron slope of -2.5(4) MPa/K if the Pt pressure scales are used, consistent with the seismic observation of the 660 discontinuity. The post-garnet boundary occurs at 24.2-27.5 GPa and 1900 - 2450 K. We found that the Clapeyron slope of the post-garnet transition increases with Fe: from 2.4 MPa/K for MAS to 6.2 MPa/K for CMASF. Below 1900 K, garnet disappears near the post-spinel boundary within the resolution of our measurements. Our new data supports the notion that the 660 discontinuity is dominated by the post-spinel phase transition below 1900 K while dominated by the post-garnet phase transition above 1900 K. However, our data indicate much larger Clapeyron slope of the post-garnet transition, suggesting

Deformation behavior of migmatites: insights from microstructural analysis of a garnet-sillimanite-mullite-quartz-feldspar-bearing anatectic migmatite at Rampura-Agucha, Aravalli-Delhi Fold Belt, NW India

NASA Astrophysics Data System (ADS)

Prakash, Abhishek; Piazolo, Sandra; Saha, Lopamudra; Bhattacharya, Abhijit; Pal, Durgesh Kumar; Sarkar, Saheli

2018-03-01

In the present study we investigate the microstructural development in mullite, quartz and garnet in an anatectic migmatite hosted within a Grenvillian-age shear zone in the Aravalli-Delhi Fold Belt. The migmatite exhibits three main deformation structures and fabrics (S1, S2, S3). Elongated garnet porphyroblasts are aligned parallel to the metatexite S2 layers and contain crenulation hinges defined by biotite-sillimanite-mullite-quartz (with S1 axial planar foliation). Microstructural evidence and phase equilibrium relations establish the garnet as a peritectic phase of incongruent melting by breakdown of biotite, sillimanite ± mullite and quartz at peak P-T of 8 kbar, 730 °C along a tight-loop, clockwise P-T path. Monazite dating establishes that the partial melting occurred between 1000 and 870 Ma. The absence of subgrains and systematic crystal lattice distortions in these garnets despite their elongation suggests growth pseudomorphing pre-existing 3-D networks of S1 biotite aggregates rather than high-temperature crystal plastic deformation which is noted in the S1 quartz grains that exhibit strong crystallographic preferred orientation (CPO), undulatory extinction and subgrains. Mode-I fractures in these garnet porphyroblasts induced by high melt pressure during late stage of partial melt crystallization are filled by retrograde biotite-sillimanite. Weak CPO and non-systematic crystal lattice distortions in the coarse quartz grains within the S2 leucosome domains indicate these crystallized during melt solidification without later crystal plastic deformation overprint. In the later stages of deformation (D3), strain was mostly accommodated in the mullite-biotite-sillimanite-rich restite domains forming S3 which warps around garnet and leucosome domains; consequently, fine-grained S3 quartz does not exhibit strong CPOs.

P-T-t metamorphic evolution of highly deformed metapelites from the Pinkie unit of western Svalbard using quartz-in-garnet barometry, trace element thermometry, P-T-X-M diagrams and monazite in-situ dating

NASA Astrophysics Data System (ADS)

Kośmińska, Karolina; Spear, Frank; Majka, Jarosław

2017-04-01

We present the results of quartz-in-garnet (QuiG) Raman barometry coupled with P-T-X-M diagrams, trace element thermometry, and monazite dating from metapelites of the Pinkie unit on Prins Karls Forland, western Svalbard. This unconventional approach, which combines traditional and novel thermobarometry techniques as well as dating results, provides the opportunity to decipher the pressure-temperature-time (P-T-t) metamorphic evolution of these highly deformed rocks, for which the P-T conditions could not have been obtained using traditional techniques. The Pinkie unit is comprised of Barrovian-type zones expressed by the following three mineral assemblages: Grt+St+Ms+Bt+Pl+Q, Grt+St+Ky+Ms+Bt+Pl+Q and Grt+Ky+Ms+Bt+Pl+Q. The metamorphic assemblages have been strongly affected by pervasive mylonitization. Two generations of garnet are present. Early garnet-I forms large (up to 2 mm) anhedral and inclusion-rich porphyroblasts that are strongly deformed with resorbed rims. Its composition varies from Alm81Grs5Prp11Sps3 in the core to Alm84Grs4Prp10Sps2 in the rim for a St-bearing sample. St-Ky bearing metapelites contain garnet-I, which is characterized by Alm88Grs2Prp8Sps2 in the core and Alm89Grs2Prp8Sps1 in the rim. In the Ky-bearing sample garnet-I composition is varying from Alm77Grs4Prp11Sps8 in the core to Alm83Grs4Prp9Sps4 in the rim. Garnet-II is characterized by small (up to 0.5 mm) euhedral grains that locally overgrows garnet-I. It contains very scarce inclusions, mostly quartz. Grt-II composition is very similar in all Pinkie unit samples and is characterized by Alm80Grs11Prp8Sps1(0). The measured maximum shift of the 464 cm-1 Raman band for quartz in garnet-I is 1.05 cm-1 for St-bearing samples, 1.80 cm-1 for St-Ky bearing rocks, and 2.10 cm-1 for Ky-bearing samples, respectively. The highest shift obtained for inclusions in garnet-II is 2.7 cm-1. Monazite-in-garnet thermometry combined with the QuiG yielded P-T conditions of garnet-I nucleation as

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.

Development and Characterization of Novel Garnet and Gold Thin Films for Photonic and Plasmonic Applications

NASA Astrophysics Data System (ADS)

Dulal, Prabesh

The massive amount of data that we produce and share today is the result of advancements made in the semiconductor and magnetic recording industries. As the number of transistors per unit area in integrated circuits continues to rise, power dissipation is reaching alarming levels. Photonics, which essentially is a marriage of semiconductor with laser technology has shown great promise in tackling the issue of power dissipation. The first part of this work focuses on optical isolators, which are essential to halt back-reflections that interfere with the laser source of the photonic systems. Novel terbium iron garnet thin-film optical isolators have been developed on semiconductor platforms and their magneto-optical properties are explored. Modesolver and finite-difference simulations are done to assess their device-feasibility and efficiency. Subsequently, a new photonic device has been developed using current semiconductor microelectronic fabrication techniques. Advancement in magnetic recording is equally vital to keep up with the demand for more data at faster speeds as the current perpendicular recording technique is fast-approaching its areal density limitations. Heat assisted magnetic recording (HAMR) is the next step in the evolution of hard drives. HAMR involves heating of magnetic media using plasmonic near field transducers (NFTs), which must be able to withstand elevated temperatures for extended times. The second part of this work presents a statistical crystallographic study of thermally induced deformation of Au NFTs. Subsequently, the most thermally stable crystallographic orientation for Au NFT has been determined that could lead to significant improvements in HAMR drive reliability.

Caledonian evolution of the Moine Supergroup: Prograde garnet growth and context for quartz fabric-based deformation thermometry

NASA Astrophysics Data System (ADS)

Law, Richard; Ashley, Kyle; Thigpen, Ryan

2014-05-01

Despite the detailed Caledonian structural/tectonic framework developed for the Moine Supergroup of northern Scotland, debate continues over the tectonic processes that drove metamorphism. Rapid temporal evolution of the metamorphic sequence has led some geologists to suggest that crustal thickening alone cannot provide sufficient heat flow to reach the metamorphic grades observed. Rather, they postulate that large-scale contact metamorphism or initial heating in an extensional, back-arc setting is required. We present coupled petrographic analyses and forward phase stability modeling for quantifying prograde metamorphic evolution in pelite horizons dispersed across the Caledonian thrust sheets. Results suggest garnet growth was syn-kinematic during prograde decompression. Rutile and ilmenite inclusions in garnet cores and rims, respectively, support this claim, while chemical profiles and crystal morphology argue against a detrital origin for these garnet grains. The observed clockwise P-T path for these garnets is incompatible with extensional or contact metamorphic models (would require counter-clockwise paths). Rather, the P-T data suggests advection of isotherms during thrusting as the dominant mechanism for metamorphism (Thigpen et al., 2013). Recent studies in other orogens (e.g., Spear et al., 2012) suggest that heating over long time scales under mid-crustal conditions may not be needed to reach the metamorphic grades observed. Therefore the structurally higher, more hinterland Caledonian thrust sheets may have reached peak metamorphism in a much shorter time period than previously expected. The paucity of pelitic horizons across the foreland-positioned Moine thrust sheet has previously limited insight into the prograde evolution of these rocks. However, the dominance of quartz-rich units has allowed the thermal structure of the thrust sheet to be evaluated using quartz c-axis fabric opening angle-based deformation thermometry. Microstructures in the

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.

Genesis of Ultra-High Pressure Garnet Pyroxenite in Orogenic Peridotites and its bearing on the Isotopic Chemical Heterogeneity in the Mantle Source of Oceanic Basalts

NASA Astrophysics Data System (ADS)

Varas Reus, María Isabel; Garrido, Carlos J.; Marchesi, Claudio; Bosch, Delphine; Hidas, Károly

2017-04-01

The genesis of ultra-high pressure (UHP) garnet pyroxenites in orogenic peridotite massifs and its implications on the formation of chemical heterogeneities in the mantle and on basalt petrogenesis are still not fully understood. Some UHP (diamond-bearing) garnet pyroxenites have isotopic, and major and trace element compositions similar to the recycled oceanic crustal component observed in oceanic basalts [1-6]. These pyroxenites hence provide an exceptional opportunity to investigate in situ the nature and scale of the Earth's mantle chemical heterogeneities. Here, we present an integrated geochemical study of UHP garnet pyroxenites from the Ronda (Betic Belt, S. Spain) and Beni Bousera (Rif Belt, N. Morocco) peridotite massifs. This investigation encompasses, in the same sample, bulk rock major and trace elements, as well as Sr-Nd-Pb-Hf isotopic analyses. According to their Al2O3 content, we classify UHP garnet pyroxenites into three groups that have distinct trace elements and Sr-Nd-Pb-Hf isotopic signatures. Group A pyroxenites (Al2O3: 15 - 17.5 wt. %) are characterized by low initial 87Sr/86Sr, relatively high 143Nd/144Nd, 206Pb/204Pb and 176Hf/177Hf ratios, and highly variable 207Pb/204Pb and 208Pb/204Pb ratios. Group B pyroxenites (Al2O3 < 14 wt. %) have isotopic signatures characterized by relatively high initial 87Sr/86Sr and low 143Nd/144Nd, 206Pb/204Pb and 176Hf/177Hf ratios. Group C pyroxenites (Al2O3 ˜ 15 wt. %) display relatively low initial 87Sr/86Sr and 206Pb/204Pb ratios, high 143Nd/144Nd and 176Hf/177Hf ratios, and 207Pb/204Pb and 208Pb/204Pb ratios similar to Group B pyroxenites. The major and trace element, and isotopic compositions of the studied Ronda and Beni Bousera UHP garnet pyroxenites lend support to the "Marble Cake Mantle" model [7] for the genesis of these pyroxenites. This model envisions the mantle source of oceanic basalts as a mélange of subducted, ancient oceanic crust —-represented by garnet pyroxenites in orogenic

Absence of magnetic ordering and field-induced phase diagram in the gadolinium aluminum garnet

NASA Astrophysics Data System (ADS)

Florea, O.; Lhotel, E.; Jacobsen, H.; Knee, C. S.; Deen, P. P.

2017-12-01

The robustness of spin liquids with respect to small perturbations, and the way magnetic frustration can be lifted by slight changes in the balance between competing magnetic interactions, remains a rich and open issue. We address this question through the study of the gadolinium aluminum garnet Gd3Al5O12 , a related compound to the extensively studied Gd3Ga5O12 . We report on its magnetic properties at very low temperatures. We show that despite a freezing at about 300 mK, no magnetic transition is observed, suggesting the presence of a spin-liquid state down to the lowest temperatures, similarly to Gd3Ga5O12 , in spite of a larger ratio between exchange and dipolar interactions. Finally, the phase diagram as a function of field and temperature is strongly reminiscent of the one reported in Gd3Ga5O12 . This study reveals the robust nature of the spin-liquid phase for Gd ions on the garnet lattice, in stark contrast to Gd ions on the pyrochlore lattice for which a slight perturbation drives the compound into a range of magnetically ordered states.

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

First-principles density functional calculation of electrochemical stability of fast Li ion conducting garnet-type oxides.

PubMed

Nakayama, Masanobu; Kotobuki, Masashi; Munakata, Hirokazu; Nogami, Masayuki; Kanamura, Kiyoshi

2012-07-28

The research and development of rechargeable all-ceramic lithium batteries are vital to realize their considerable advantages over existing commercial lithium ion batteries in terms of size, energy density, and safety. A key part of such effort is the development of solid-state electrolyte materials with high Li(+) conductivity and good electrochemical stability; lithium-containing oxides with a garnet-type structure are known to satisfy the requirements to achieve both features. Using first-principles density functional theory (DFT), we investigated the electrochemical stability of garnet-type Li(x)La(3)M(2)O(12) (M = Ti, Zr, Nb, Ta, Sb, Bi; x = 5 or 7) materials against Li metal. We found that the electrochemical stability of such materials depends on their composition and structure. The electrochemical stability against Li metal was improved when a cation M was chosen with a low effective nuclear charge, that is, with a high screening constant for an unoccupied orbital. In fact, both our computational and experimental results show that Li(7)La(3)Zr(2)O(12) and Li(5)La(3)Ta(2)O(12) are inert to Li metal. In addition, the linkage of MO(6) octahedra in the crystal structure affects the electrochemical stability. For example, perovskite-type La(1/3)TaO(3) was found, both experimentally and computationally, to react with Li metal owing to the corner-sharing MO(6) octahedral network of La(1/3)TaO(3), even though it has the same constituent elements as garnet-type Li(5)La(3)Ta(2)O(12) (which is inert to Li metal and features isolated TaO(6) octahedra).

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

Effects of Gd/Lu ratio on the luminescence properties and garnet phase stability of Ce3+ activated GdxLu3-xAl5O12 single crystals

NASA Astrophysics Data System (ADS)

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

2018-06-01

The luminescence properties of Ce3+ activated (Gd,Lu)3Al5O12 single crystals are investigated as a function of the Gd/Lu ratio with the aim of an improved understanding of the luminescence quenching, energy transfer processes, and garnet phase stability. Upon heavy substitution of Lu with Gd, the target garnet phase becomes thermodynamically unstable and unwanted secondary phase inclusions arise. The secondary phase shows luminescence properties in the UV spectral range. The thermal quenching process of the 5d→4f emission of Ce3+ in the garnet phase is determined by the temperature dependence of the photoluminescence decay time and delayed radiative recombination decays. The results show that the onset of the thermal quenching is moved to lower temperatures with increasing the Gd3+ content. The main mechanism responsible for the luminescence quenching is due to the non-radiative relaxation from 5d1 excited state to 4f ground state of Ce3+. The energy transfer processes between Gd3+ and Ce3+ as well as between secondary and garnet phase are evidenced by the photoluminescence excitation and emission spectra as well as decay kinetic measurements.

Combined garnet and zircon geochronology of the ultra-high temperature metamorphism: Constraints on the rise of the Orlica-Śnieżnik Dome, NE Bohemian Massif, SW Poland

NASA Astrophysics Data System (ADS)

Walczak, Katarzyna; Anczkiewicz, Robert; Szczepański, Jacek; Rubatto, Daniela; Košler, Jan

2017-11-01

Garnet and zircon geochronology combined with trace element partitioning and petrological studies provide tight constraints on evolution of the UHT-(U)HP terrain of the Orlica-Śnieżnik Dome (OSD) in the NE Bohemian massif. Lu-Hf dating of peritectic garnet from two mesocratic granulites constrained the time of its initial growth at 346.9 ± 1.2 and 348.3 ± 2.0 Ma recording peak 2.5 GPa pressure and 950 °C temperature. In situ, U-Pb SHRIMP dating of zircon from the same granulite gave a younger age of 341.9 ± 3.4 Ma. Ti-in-zircon thermometry indicates crystallization at 810-860 °C pointing to zircon formation on the retrograde path. Lu partitioning between garnet rim and zircon suggest equilibrium growth and thus U-Pb zircon age constrain the terminal phase of garnet crystallization which lasted about 6 Ma. All Sm-Nd garnet ages obtained for mesocratic and mafic granulites are identical and consistently younger than the corresponding Lu-Hf dates. They are interpreted as reflecting cooling of granulites through the Sm-Nd closure temperature at about 337 Ma. The estimated PTt path documents the ca. 10 Ma evolution cycle of the OSD characterized by two distinct periods: (1) 347 - > 342 Ma period corresponds to nearly isothermal decompression resulting from crustal scale folding and vertical extrusion of granulites, and (2) at > 342-337 Ma which corresponds to a fast, nearly isobaric cooling.

P-T evolution of slivers of garnet-bearing micaschist in the sole of the Western Vardar Ophiolite Unit at Brezovica, Kosovo

NASA Astrophysics Data System (ADS)

Massonne, Hans-Joachim; Koller, Friedrich; Onuzi, Kujtim

2016-04-01

Rocks of the metamorphic sole of ophiolite complexes are regarded as an important factor to understand the process of obduction of former oceanic lithosphere on top of continental crust. The metamorphic evolution of these rocks can give, for instance, hints at the thickness of the obducted oceanic lithosphere. We have started to study the sole of the Western Vardar Ophiolitic Unit at the municipality of Bresovica, Kosovo. This unit is regarded as part of the former Vardar Ocean, a branch of the Neotethys, which was obducted onto the margin of the Adriatic microplate in Jurassic times. The sole in our study area, below strongly serpentinized ultramafic rocks, is characterized by a melange of various rock types, which are of medium metamorphic grade only in the vicinity of the ultramafic rocks. Our field work resulted in the recognition of several slivers of garnet-bearing micaschist among these medium-grade rocks which are dominated by amphibolite. In such a medium-grade rock from Bresovica the mineral assemblage talc + phengite was reported (Abraham and Schreyer, 1976, J. Petrol. 17, 421-439), which turned out by experiments in a piston-cylinder apparatus to be a high-pressure (HP: > 10 kbar) assemblage (Massonne and Schreyer, 1989, Eur. J. Mineral. 1, 391-410). We studied a garnet-bearing micaschist in detail. Elemental mapping and spot analyses of garnet obtained with an electron microprobe yielded core compositions of Alm0.695Gross(+Andr)0.11Pyr0.185Spes0.01. The composition of the garnet rim is Alm0.71Gross(+Andr)0.065Pyr0.21Spes0.015. On the basis of the bulk-rock composition of the micaschist, a P-T pseudosection was constructed with PERPLEX in the system K-Na-Ca-Mg-Mn-Fe-Al-Si-Ti-O-H. This pseudosection was contoured by isopleths for various parameters among them were the molar fractions of garnet components. According to such isopleths and the compositional variation of garnet, a more or less isobaric heating is likely. This heating to 650 °C has occurred

Genesis of ultra-high pressure garnet pyroxenites in orogenic peridotites and its bearing on the compositional heterogeneity of the Earth's mantle

NASA Astrophysics Data System (ADS)

Varas-Reus, María Isabel; Garrido, Carlos J.; Marchesi, Claudio; Bosch, Delphine; Hidas, Károly

2018-07-01

We present an integrated geochemical study of ultra-high pressure (UHP) garnet pyroxenites from the Ronda and Beni Bousera peridotite massifs (Betic-Rif Belt, westernmost Mediterranean). Based on their Sr-Nd-Pb-Hf isotopic systematics, we classify UHP garnet pyroxenites into three groups: Group A pyroxenites (Al2O3: 15-17.5 wt.%) have low initial 87Sr/86Sr, relatively high εNd, εHf and 206Pb/204Pb ratios, and variable 207Pb/204Pb and 208Pb/204Pb. Group B pyroxenites (Al2O3 < 14 wt.%) are characterized by high initial 87Sr/86Sr and relatively low εNd, εHf and 206Pb/204Pb ratios. Group C pyroxenites (Al2O3 ∼ 15 wt.%) have depleted radiogenic signatures with relatively low initial 87Sr/86Sr and 206Pb/204Pb, high εNd and εHf, and their 207Pb/204Pb and 208Pb/204Pb ratios are similar to those of Group B pyroxenites. The major and trace element and isotopic compositions of UHP garnet pyroxenites support their derivation from ancient (1.5-3.5 Ga) oceanic crust recycled into the mantle and intimately stirred with peridotites by convection. However, the genesis of these pyroxenites requires also the involvement of recycled continental lower crust with an isotopic composition akin to the lower crustal section of the lithosphere where these UHP garnet pyroxenites now reside in. These oceanic and continental crustal components were stirred in different proportions in the convective mantle, originating pyroxenites with a more marked geochemical imprint of either oceanic (Group A) or continental lower crust (Group B), or hybrid compositions (Group C). The pyroxenite protoliths likely underwent several melting events, one of them related to the formation of the subcontinental lithospheric mantle and continental crust, generating restitic UHP garnet pyroxenites now preserved in the Ronda and Beni Bousera orogenic peridotites. The extent of melting was mostly controlled by the bulk Mg-number (Mg#) of the pyroxenite protoliths, where protoliths with low Mg# experienced higher

Iron Homeostasis and Nutritional Iron Deficiency123

PubMed Central

Theil, Elizabeth C.

2011-01-01

Nonheme food ferritin (FTN) iron minerals, nonheme iron complexes, and heme iron contribute to the balance between food iron absorption and body iron homeostasis. Iron absorption depends on membrane transporter proteins DMT1, PCP/HCP1, ferroportin (FPN), TRF2, and matriptase 2. Mutations in DMT1 and matriptase-2 cause iron deficiency; mutations in FPN, HFE, and TRF2 cause iron excess. Intracellular iron homeostasis depends on coordinated regulation of iron trafficking and storage proteins encoded in iron responsive element (IRE)-mRNA. The noncoding IRE-mRNA structures bind protein repressors, IRP1 or 2, during iron deficiency. Integration of the IRE-RNA in translation regulators (near the cap) or turnover elements (after the coding region) increases iron uptake (DMT1/TRF1) or decreases iron storage/efflux (FTN/FPN) when IRP binds. An antioxidant response element in FTN DNA binds Bach1, a heme-sensitive transcription factor that coordinates expression among antioxidant response proteins like FTN, thioredoxin reductase, and quinone reductase. FTN, an antioxidant because Fe2+ and O2 (reactive oxygen species generators) are consumed to make iron mineral, is also a nutritional iron concentrate that is an efficiently absorbed, nonheme source of iron from whole legumes. FTN protein cages contain thousands of mineralized iron atoms and enter cells by receptor-mediated endocytosis, an absorption mechanism distinct from transport of nonheme iron salts (ferrous sulfate), iron chelators (ferric-EDTA), or heme. Recognition of 2 nutritional nonheme iron sources, small and large (FTN), will aid the solution of iron deficiency, a major public health problem, and the development of new policies on iron nutrition. PMID:21346101

The effect of bonding environment on iron isotope fractionation between minerals at high temperature

NASA Astrophysics Data System (ADS)

Sossi, Paolo A.; O'Neill, Hugh St. C.

2017-01-01

Central to understanding the processes that drive stable isotope fractionation in nature is their quantification under controlled experimental conditions. The polyvalent element iron, given its abundance in terrestrial rocks, exerts controls on the structural and chemical properties of minerals and melts. The iron isotope compositions of typical high temperature minerals are, however, poorly constrained and their dependence on intensive (e.g. fO2) and extensive (e.g. compositional) variables is unknown. In this work, experiments involving a reference phase, 2 M FeCl2·4H2O(l), together with an oxide mix corresponding to the bulk composition of the chosen mineral were performed in a piston cylinder in Ag capsules. The oxide mix crystallised in situ at 1073 K and 1 GPa, in equilibrium with the iron chloride, and was held for 72 h. In order to characterise the effect of co-ordination and oxidation state on the isotope composition independently, exclusively Fe2+ minerals were substituted in: VIII-fold almandine, VI-fold ilmenite, fayalite and IV-fold chromite and hercynite. Δ57FeMin-FeCl2 increases in the order VIII < VI < IV, consistent with a decrease in the mean Fe-O bond length. Magnetite, which has mixed VI- and IV-fold co-ordination, has the heaviest Δ57Fe by virtue of 2/3 of its iron being the smaller, ferric ion. The composition of the VIFe2+-bearing minerals is similar to that of the aqueous FeCl2 fluid. To the degree that this represents the speciation of iron in fluids exsolving from magmas, the fractionation between them should be small, unless the iron is hosted in magnetite. By contrast, predominantly Fe2+-bearing mantle garnets should preserve a much lighter δ57Fe than their lower pressure spinel counterparts, a signature that may be reflected in partial melts from these lithologies. As the Fe-O bond lengths in fayalite and ilmenite are comparable, their isotope compositions overlap, suggesting that high Ti mare basalts acquired their heavy isotopic

Combined garnet and zircon geochronology and trace elements studies - constraints of the UHP-(U)HT evolution of Orlica-Śnieżnik Dome (NE Bohemian Massif).

NASA Astrophysics Data System (ADS)

Walczak, Katarzyna; Anczkiewicz, Robert; Szczepański, Jacek; Rubatto, Daniela

2017-04-01

The Orlica-Śnieżnik Dome (OSD), located on the NE margin of the Bohemian Massif, is predominantly composed of amphibolite-facies orthogneiss that contain bodies of HP and UHP eclogites and granulites. Numerous geochronological studies have been undertaken to constrain the timing of the ultra-high grade metamorphic event. Despite this, the exact timing of UHP-(U)HT conditions remain dubious (e.g. Brueckner et al., 1991; Anczkiewicz et al., 2007; Bröcker et al., 2009 & 2010). We have utilized garnet and zircon geochronology to provide time constraints on the evolution of the UHT-(U)HP rocks of the OSD. We have combined the ages with trace element analyses in garnet and zircon to better understand the significance of the obtained ages in petrological context. Lu-Hf grt-wr dating of peritectic garnet from two felsic granulites constrained the time of its initial growth at 346.9 ± 1.2 and 348.3 ± 2.0 Ma, recording peak conditions of 2.7 GPa and 950°C (e.g. Ferrero et al., 2015). In situ U-Pb SHRIMP dating of zircon from the same granulite gave a younger age of 342.2 ± 3.4 Ma. HREE partitioning between garnet rim and metamorphic zircon indicate their growth in equilibrium, hence, the U-Pb zircon date constrains the terminal phase of garnet crystallization. Similar ages were obtained from two eclogite bodies from Międzygórze and Nowa Wieś localities; Lu-Hf (grt-cpx-wr) dating provided ages of 346.5 ± 2.4 and 348.1 ± 9.1 Ma for samples from Międzygórze and Nowa Wieś, respectively. The same age (within error) of 346.3 ± 5.2 Ma was reported by Bröcker et al. (2010) for zircon from the Międzygórze eclogite. Comparison of REE concentrations in garnet (this study) and in metamorphic zircon (reported in Bröcker et al., 2010) indicate that garnet and zircon crystallized in equilibrium. Furthermore, M-HREE patterns observed in both garnet and zircon strongly suggest their growth at eclogite facies conditions. Sm-Nd garnet ages obtained for both felsic and mafic

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.

Thorium-uranium fractionation by garnet - Evidence for a deep source and rapid rise of oceanic basalts

NASA Technical Reports Server (NTRS)

Latourrette, T. Z.; Kennedy, A. K.; Wasserburg, G. J.

1993-01-01

Mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) are derived by partial melting of the upper mantle and are marked by systematic excesses of thorium-230 activity relative to the activity of its parent, uranium-238. Experimental measurements of the distribution of thorium and uranium between the melt and solid residue show that, of the major phases in the upper mantle, only garnet will retain uranium over thorium. This sense of fractionation, which is opposite to that caused by clinopyroxene-melt partitioning, is consistent with the thorium-230 excesses observed in young oceanic basalts. Thus, both MORBs and OIBs must begin partial melting in the garnet stability field or below about 70 kilometers. A calculation shows that the thorium-230-uranium-238 disequilibrium in MORBs can be attributed to dynamic partial melting beginning at 80 kilometers with a melt porosity of 0.2 percent or more. This result requires that melting beneath ridges occurs in a wide region and that the magma rises to the surface at a velocity of at least 0.9 meter per year.

Yttrium aluminium garnet under pressure: Structural, elastic, and vibrational properties from ab initio studies

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

Monteseguro, V.; Rodríguez-Hernández, P.; Muñoz, A., E-mail: amunoz@ull.es

The structural, elastic, and vibrational properties of yttrium aluminum garnet Y{sub 3}Al{sub 5}O{sub 12} are studied under high pressure by ab initio calculations in the framework of the density functional theory. The calculated ground state properties are in good agreement with the available experimental data. Pressure dependences of bond length and bulk moduli of the constituent polyhedra are reported. The evolution of the elastic constants and the major elastic properties, Young and shear modulus, Poisson's ratios, and Zener anisotropy ratio, are described. The mechanical stability is analyzed, on the light of “Born generalized stability criteria,” showing that the garnet ismore » mechanically unstable above 116 GPa. Symmetries, frequencies, and pressure coefficients of the Raman-active modes are discussed on the basis of the calculated total and partial phonon density of states, which reflect the dynamical contribution of each atom. The relations between the phonon modes of Y{sub 3}Al{sub 5}O{sub 12} and the internal and external molecular modes of the different polyhedra are discussed. Infrared-active modes, as well as the silent modes, and their pressure dependence are also investigated. No dynamical instabilities were found below 116 GPa.« less

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

Phase transitions and Al partitioning in a pyrolitic MgO-Al2O3-SiO2 composition at 16-31 GPa and 1500-2300 K

NASA Astrophysics Data System (ADS)

Ye, Y.; Gu, C.; Shim, S.; Prakapenka, V.; MacDowell, A.

2013-12-01

In order to understand strong seismic heterogeneities found in the base of the mantle transition zone, it is important to explore the effects of temperature and composition on the phase boundaries in the region. We have determined the phase boundaries near the 660-km discontinuity in an iron-free pyrolitic MgO-Al2O3-SiO2 (MAS) composition by combining in-situ synchrotron X-ray diffraction and laser-heated diamond-anvil cell at 16-31 GPa and 1500-2300 K. The pyrolitic MAS composition glass starting materials were mixed with platinum (laser coupler and internal pressure scale) and loaded into the diamond-anvil cells together with argon (pressure transmitting medium and thermal insulator). The in-situ measurements were conducted at the GSECARS sector of Advanced Photon Source and beamline 12.2.2 of Advanced Light Source. We found that the post-spinel transition (ringwoodite to perovskite+periclase) occurs at the pressure and temperature conditions expected for the 660-km discontinuity at 1800 K if the shockwave platinum pressure scale by Holmes et al. (1989) is used. At temperatures above 1900 K, ringwoodite breaks down to garnet+periclase, instead of perovskite+periclase, followed by the post-garnet transition (garnet to perovskite) at the pressure-temperature conditions expected for warm heterogeneities at 650-680 km depths (23-24 GPa and 1900-2300 K). The Clapeyron slopes of the post-spinel and post-garnet boundaries are constrained to be -2.8×0.2 and +2.4×0.3 MPa/K, respectively, indicating similar magnitude of thermal effects (with opposite signs) on the topography of the 660-km discontinuity by these phase boundaries. The dominance of the post-garnet transition above normal mantle temperatures will facilitate material exchange across the 660 discontinuity in warm mantle heterogeneities due to its positive Clapeyron slope. In our pyrolitic MAS composition, akimotoite was observed up to 2000-2300 K between 20 and 22 GPa in both fresh sample heating and reversal

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

Thermal effects from modified endodontic laser tips used in the apical third of root canals with erbium-doped yttrium aluminium garnet and erbium, chromium-doped yttrium scandium gallium garnet lasers.

PubMed

George, Roy; Walsh, Laurence J

2010-04-01

To evaluate the temperature changes occurring on the apical third of root surfaces when erbium-doped yttrium aluminium garnet (Er:YAG) and erbium, chromium-doped yttrium scandium gallium garnet (Er,Cr:YSGG) laser energy was delivered with a tube etched, laterally emitting conical tip and a conventional bare design optical fiber tip. Thermal effects of root canal laser treatments on periodontal ligament cells and alveolar bone are of concern in terms of safety. A total of 64 single-rooted extracted teeth were prepared 1 mm short of the working length using rotary nickel-titanium Pro-Taper files to an apical size corresponding to a F5 Pro-Taper instrument. A thermocouple located 2 mm from the apex was used to record temperature changes arising from delivery of laser energy through laterally emitting conical tips or plain tips, using an Er:YAG or Er,Cr:YSGG laser. For the Er:YAG and Er,Cr:YSGG systems, conical fibers showed greater lateral emissions (452 + 69% and 443 + 64%) and corresponding lower forward emissions (48 + 5% and 49 + 5%) than conventional plain-fiber tips. All four combinations of laser system and fiber design elicited temperature increases less than 2.5 degrees C during lasing. The use of water irrigation attenuated completely the thermal effects of individual lasing cycles. Laterally emitting conical fiber tips can be used safely under defined conditions for intracanal irradiation without harmful thermal effects on the periodontal apparatus.

A Rechargeable Li-Air Fuel Cell Battery Based on Garnet Solid Electrolytes.

PubMed

Sun, Jiyang; Zhao, Ning; Li, Yiqiu; Guo, Xiangxin; Feng, Xuefei; Liu, Xiaosong; Liu, Zhi; Cui, Guanglei; Zheng, Hao; Gu, Lin; Li, Hong

2017-01-24

Non-aqueous Li-air batteries have been intensively studied in the past few years for their theoretically super-high energy density. However, they cannot operate properly in real air because they contain highly unstable and volatile electrolytes. Here, we report the fabrication of solid-state Li-air batteries using garnet (i.e., Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 , LLZTO) ceramic disks with high density and ionic conductivity as the electrolytes and composite cathodes consisting of garnet powder, Li salts (LiTFSI) and active carbon. These batteries run in real air based on the formation and decomposition at least partially of Li 2 CO 3 . Batteries with LiTFSI mixed with polyimide (PI:LiTFSI) as a binder show rechargeability at 200 °C with a specific capacity of 2184 mAh g -1 carbon at 20 μA cm -2 . Replacement of PI:LiTFSI with LiTFSI dissolved in polypropylene carbonate (PPC:LiTFSI) reduces interfacial resistance, and the resulting batteries show a greatly increased discharge capacity of approximately 20300 mAh g -1 carbon and cycle 50 times while maintaining a cutoff capacity of 1000 mAh g -1 carbon at 20 μA cm -2 and 80 °C. These results demonstrate that the use of LLZTO ceramic electrolytes enables operation of the Li-air battery in real air at medium temperatures, leading to a novel type of Li-air fuel cell battery for energy storage.

A Rechargeable Li-Air Fuel Cell Battery Based on Garnet Solid Electrolytes

PubMed Central

Sun, Jiyang; Zhao, Ning; Li, Yiqiu; Guo, Xiangxin; Feng, Xuefei; Liu, Xiaosong; Liu, Zhi; Cui, Guanglei; Zheng, Hao; Gu, Lin; Li, Hong

2017-01-01

Non-aqueous Li-air batteries have been intensively studied in the past few years for their theoretically super-high energy density. However, they cannot operate properly in real air because they contain highly unstable and volatile electrolytes. Here, we report the fabrication of solid-state Li-air batteries using garnet (i.e., Li6.4La3Zr1.4Ta0.6O12, LLZTO) ceramic disks with high density and ionic conductivity as the electrolytes and composite cathodes consisting of garnet powder, Li salts (LiTFSI) and active carbon. These batteries run in real air based on the formation and decomposition at least partially of Li2CO3. Batteries with LiTFSI mixed with polyimide (PI:LiTFSI) as a binder show rechargeability at 200 °C with a specific capacity of 2184 mAh g−1carbon at 20 μA cm−2. Replacement of PI:LiTFSI with LiTFSI dissolved in polypropylene carbonate (PPC:LiTFSI) reduces interfacial resistance, and the resulting batteries show a greatly increased discharge capacity of approximately 20300 mAh g−1carbon and cycle 50 times while maintaining a cutoff capacity of 1000 mAh g−1carbon at 20 μA cm−2 and 80 °C. These results demonstrate that the use of LLZTO ceramic electrolytes enables operation of the Li-air battery in real air at medium temperatures, leading to a novel type of Li-air fuel cell battery for energy storage. PMID:28117359

Composite Polymer-Garnet Solid State Electrolytes

NASA Astrophysics Data System (ADS)

Villa, Andres; Oduncu, Muhammed R.; Scofield, Gregory D.; Marinero, Ernesto E.; Forbey, Scott

Solid-state electrolytes provide a potential solution to the safety and reliability issues of Li-ion batteries. We have synthesized cubic-phase Li7-xLa3Zr2-xBixO12 compounds utilizing inexpensive, scalable Sol-gel synthesis and obtained ionic conductivities 1.2 x 10-4 S/cm at RT in not-fully densified pellets. In this work we report on the fabrication of composite polymer-garnet ceramic particle electrolytes to produce flexible membranes that can be integrated with standard battery electrodes without the need for a separator. As a first step we incorporated the ceramic particles into polyethylene oxide polymers (PEO) to form flexible membranes. Early results are encouraging yielding ionic conductivity values 1.0 x 10-5 S/cm at RT. To increment the conductivity in the membranes, we are optimizing amongst other: the ceramic particle size distribution and weight load, the polymer molecular weight and chemical composition and the solvated Li-salt composition and content. Unhindered ion transport across interfaces between the composites and the battery electrode materials is paramount for battery performance. To this end, we are investigating the effect of interface morphology, its atomic composition and exploring novel electrode structures that facilitate ionic transport.

A Brillouin Light Scattering Study of Magnetic Excitations.

DTIC Science & Technology

1986-01-30

collaborative project with CNR-Rome, with materials emphasis on substi- tuted LPE garnet thin films . "Localized Canting Models for Substituted Magnetic Oxides...thermal magnons in FeBO 3, exchange in substituted ferrites, parametric spin-waves in epitaxial yttrium iron garnet (YIG. films , surface magnon angle...and surface magnons in thin films . Central to the research was the develooment of a hiqh contrast, high resolu- tion multipassltandem Fabry; Perot

Low temperature Voigt effect in the terbium gallium garnet crystal.

PubMed

Akbar, Ali; Khalid, Muhammad Waleed; Anwar, Muhammad Sabieh

2017-11-27

Magnetic linear birefringence and dichroism are investigated for the paramagnetic terbium gallium garnet (TGG) single crystal in the temperature range 8-100 K. The reciprocal nature is confirmed for the linear birefringence. Furthermore a theoretical model is validated that describes the intermixing of linear and circular birefringence. The ellipticity and rotation of the polarization ellipse are investigated in the light of these measurements. These otherwise minuscule magnetically induced effects are amplified at cryogenic temperatures and are determined by a phase-sensitive technique based on the Fourier decomposition of detected signal intensities. The correspondent measurements also allow us to determine the Curie-Weiss constant corroborating the presence of a magnetically frustrated spin system. Additionally we show how the Voigt geometry enables determining the direction of a magnetic field.

Iron

MedlinePlus

... too little iron, you may develop iron deficiency anemia. Causes of low iron levels include blood loss, poor diet, or an inability to absorb enough iron from foods. People at higher risk of having too little iron are young children and women who are pregnant or have periods. ...

Iron and alloys of iron. [lunar resources

NASA Technical Reports Server (NTRS)

Sastri, Sankar

1992-01-01

All lunar soil contains iron in the metallic form, mostly as an iron-nickel alloy in concentrations of a few tenths of 1 percent. Some of this free iron can be easily separated by magnetic means. It is estimated that the magnetic separation of 100,000 tons of lunar soil would yield 150-200 tons of iron. Agglutinates contain metallic iron which could be extracted by melting and made into powder metallurgy products. The characteristics and potential uses of the pure-iron and iron-alloy lunar products are discussed. Processes for working iron that might be used in a nonterrestrial facility are also addressed.

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.

MANUFACTURING METHODS FOR PHASE SHIFTERS.

DTIC Science & Technology

MANUFACTURING), (*PHASE SHIFT CIRCUITS, FERRITES, GARNET , DIGITAL SYSTEMS, X BAND, C BAND, S BAND, RADAR EQUIPMENT, MAGNETIC MATERIALS, YTTRIUM COMPOUNDS, GADOLINIUM COMPOUNDS, ALUMINUM COMPOUNDS, IRON COMPOUNDS, OXIDES.

Iron excretion in iron dextran-overloaded mice

PubMed Central

Musumeci, Marco; Maccari, Sonia; Massimi, Alessia; Stati, Tonino; Sestili, Paola; Corritore, Elisa; Pastorelli, Augusto; Stacchini, Paolo; Marano, Giuseppe; Catalano, Liviana

2014-01-01

Background Iron homeostasis in humans is tightly regulated by mechanisms aimed to conserve iron for reutilisation, with a negligible role played by excretory mechanisms. In a previous study we found that mice have an astonishing ability to tolerate very high doses of parenterally administered iron dextran. Whether this ability is linked to the existence of an excretory pathway remains to be ascertained. Materials and methods Iron overload was generated by intraperitoneal injections of iron dextran (1 g/kg) administered once a week for 8 weeks in two different mouse strains (C57bl/6 and B6D2F1). Urinary and faecal iron excretion was assessed by inductively coupling plasma-mass spectrometry, whereas cardiac and liver architecture was evaluated by echocardiography and histological methods. For both strains, 24-hour faeces and urine samples were collected and iron concentration was determined on days 0, 1 and 2 after iron administration. Results In iron-overloaded C57bl/6 mice, the faecal iron concentration increased by 218% and 157% on days 1 and 2, respectively (p<0.01). The iron excreted represented a loss of 14% of total iron administered. Similar but smaller changes was also found in B6D2F1 mice. Conversely, we found no significant changes in the concentration of iron in the urine in either of the strains of mice. In both strains, histological examination showed accumulation of iron in the liver and heart which tended to decrease over time. Conclusions This study indicates that mice have a mechanism for removal of excess body iron and provides insights into the possible mechanisms of excretion. PMID:24960657

Non-transferrin bound iron: a key role in iron overload and iron toxicity.

PubMed

Brissot, Pierre; Ropert, Martine; Le Lan, Caroline; Loréal, Olivier

2012-03-01

Besides transferrin iron, which represents the normal form of circulating iron, non-transferrin bound iron (NTBI) has been identified in the plasma of patients with various pathological conditions in which transferrin saturation is significantly elevated. To show that: i) NTBI is present not only during chronic iron overload disorders (hemochromatosis, transfusional iron overload) but also in miscellaneous diseases which are not primarily iron overloaded conditions; ii) this iron species represents a potentially toxic iron form due to its high propensity to induce reactive oxygen species and is responsible for cellular damage not only at the plasma membrane level but also towards different intracellular organelles; iii) the NTBI concept may be expanded to include intracytosolic iron forms which are not linked to ferritin, the major storage protein which exerts, at the cellular level, the same type of protective effect towards the intracellular environment as transferrin in the plasma. Plasma NTBI and especially labile plasma iron determinations represent a new important biological tool since elimination of this toxic iron species is a major therapeutic goal. The NTBI approach represents an important mechanistic concept for explaining cellular iron excess and toxicity and provides new important biochemical diagnostic tools. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

Is There Segregation of Rare Earth Ions in Garnet Optical Ceramics?

NASA Astrophysics Data System (ADS)

Boulon, Georges; Epicier, T.; Zhao, W.; Guzik, M.; Pan, Y.; Jiang, B.

Research on advanced optical materials for a large variety of applications is always increasing. As an example, we can note high progress in solid-state laser sources like laser-diode (LD) - pumped solid-state lasers (DPSSL) including developments of new materials and high-power laser diode led to high-power and tuneable solid-state lasers. A wide variety of materials has been studied to develop more efficient and high power microchip lasers [1]. In end-pumping schemes, in particular, materials with a short absorption length for the LD pump beam are strongly anticipated for highly efficient operations because of the excellent match between the mode and pump beam profiles. High Nd3+ concentrations were so considered such as NdP5O14, LiNdP4O12 (LNP), and NdAl3(BO3)O4. However, crystal growths of these compositions are not so easy. Cubic crystals are much more researched. When looking at the literature for actual applications, we see immediately the importance of cubic garnet crystals for which dodecahedral (Y3+), octahedral (Al3+) and tetrahedral (Al3+) sites are considered as a reservoir for many activators like: Ce3+, Nd3+, Er3+, Tm3+, Ho3+, Yb3+ rare earth ions in dodecahedral symmetry sites and transition metal ions like Cr3+ in the octahedral symmetry sites or Cr4+ in the tetrahedral symmetry sites. Among garnet crystals, Y3Al5O12 (YAG) host is the most used, commercially produced by the Czochralski method. However, in the case of the most used Nd3+: YAG laser crystal, the Nd3+ concentration that affects the performance in laser applications, is strongly limited to 0.2-1.4 Nd3+ at. % as a result of the segregation distribution coefficient [1].

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

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

Ostafiychuk, B. K.; Yaremiy, I. P., E-mail: yaremiy@rambler.ru; Yaremiy, S. I.

2013-12-15

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

Sm-Nd Mineral Isochron Age Patterns from Garnet-bearing Peridotite of the Western Gneiss Region, Norwegian Caledonides: Discrete Mantle Events or Continuous Re- equilibration?

NASA Astrophysics Data System (ADS)

Brueckner, H. K.

2007-12-01

The garnet peridotites (and pyroxenites) of the UHP Western Gneiss Region of Norway give Sm-Nd garnet, clinopyroxene, whole rock, orthopyroxene, amphibole ages that range from ca. 1.7 Ga to 424 Ma. Most of these twenty seven ages are much older than the continent-continent collision that transferred these peridoitites from the mantle into the crust (i.e. the 400 Ma Scandian Orogeny) suggesting the garnet peridotites of the WGR are unique relative to those in other UHP terranes, which invariably give ages that overlap the time of UHP metamorphism of the enclosing country rocks. All but the youngest ages given by WGR peridotites reflect processes that occurred deep in the mantle beneath the Baltic Shield, but it is unclear if they date a series of discrete events related to the tectonic evolution of the Baltic Shield or if the ages reflect continuous, but variable, re-equilibration of the Sm-Nd system between phases during the residence of the peridotites in the mantle. Three ages overlap the 1.75 to 1.55 Ga Gothian Orogeny while twelve ages are within error of the 1.2 to 0.9 Ga Sveconorwegian Orogeny. The three youngest ages (438 to 424 Ma) are associated with a younger generation of garnets and may mark the beginning of eclogite-facies metamorphism of Baltica as it was subducted beneath Laurentia during the Scandian Orogeny. However, the remaining nine ages spread more or less continuously between these three major events. The overall pattern on a histogram is a range of ages with a pronounced peak at and near the Sveconorwegian Orogeny. The ages therefore appear to date continuous diffusion between minerals from garnet-bearing assemblages that formed originally during or, less likely, before the Gothian Orogeny interrupted by a pronounced thermal event during the Svconorwegian Orogeny and a recrystallization event during the early stages of the Scandian orogeny. The degree of re-equilibration was probably controlled by the ambient temperature of the peridotite

U-Pb SHRIMP geochronology of zircon in garnet peridotite from the Sulu UHP terrane, China: Implications for mantle metasomatism and subduction-zone UHP metamorphism

USGS Publications Warehouse

Zhang, R.Y.; Yang, J.S.; Wooden, J.L.; Liou, J.G.; Li, T.F.

2005-01-01

We studied the Zhimafang ultrahigh-pressure metamorphic (UHP) peridotite from pre-pilot drill hole PP-1 of Chinese Continental Scientific Drilling project in the Sulu UHP terrane, eastern China. The peridotite occurs as lens within quartofeldspathic gneiss, and has an assemblage of Ol + Opx + Cpx + Phl + Ti-clinohumite (Ti-Chu) + Grt (or chromite) ?? magnesite (Mgs). Zircons were separated from cores at depths of 152 m (C24, garnet lhezolite), 160 m (C27, strongly retrograded phlogopite-rich peridotite) and 225 m (C50, banded peridotite), and were dated by SHRIMP mass spectrometer. Isometric zircons without inherited cores contain inclusions of olivine (Fo91-92), enstatite (En91-92), Ti-clinohumite, diopside, phlogopite and apatite. The enstatite inclusions have low Al2O3 contents of only 0.04-0.13 wt.%, indicating a UHP metamorphic origin. The weighted mean 206Pb/238U zircon age for garnet lherzolite (C24) is 221 ?? 3 Ma, and a discordia lower intercept age for peridotite (C50) is 220 ?? 2 Ma. These ages are within error and represent the time of subduction-zone UHP metamorphism. A younger lower intercept age of 212 ?? 3 Ma for a foliated wehrlite (C27) was probably caused by Pb loss during retrograde metamorphism. The source of zirconium may be partially attributed to melt/fluid metasomatism within the mantle wedge. Geochronological and geochemical data confirm that the mantle-derived Zhimafang garnet peridotites (probably the most representative type of Sulu garnet peridotites) were tectonically inserted into a subducting crustal slab and subjected to in situ Triassic subduction-zone UHP metamorphism. ?? 2005 Elsevier B.V. All rights reserved.

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

Radiative Performance of Rare Earth Garnet Thin Film Selective Emitters

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

Garnet and clinopyroxene pseudomorphs: example of local mass balance in the Caledonides of western Norway.

NASA Astrophysics Data System (ADS)

Centrella, Stephen; Austrheim, Håkon; Putnis, Andrew

2015-04-01

The Precambrian granulite facies rocks of Lindås Nappe, Bergen Arcs, Caledonides of W.Norway are partially hydrated at amphibolites and eclogite facies conditions. The Lindås Nappe outcrop over an area of ca 1000 km2 where relict granulite facies lenses make up only ca 10%. At Hillandsvatnet, garnetite displays sharp hydration fronts across which the granulite facies assemblage composed of garnet (70%) and clinopyroxene (30%) is replaced by an amphibolite facies mineralogy defined by chlorite, epidote and amphibole. This setting allows us to assess the mechanism of fluid transport through an initially low permeability rock and how this induces changes of texture and element transport. The replacement of garnet and clinopyroxene is pseudomorphic so that the grain shapes of the garnet and clinopyroxene are preserved even if when they are completely replaced. This requires that the reactive fluids must pass through the solid crystal grains and this can be achieved by an interface coupled dissolution-precipitation mechanism. Porosity generation is a key feature of this mechanism (Putnis and Austrheim 2012). The porosity is not only a consequence of reduction in solid molar volume but depends on the relative solubilities of parent and product phases in the reactive fluid. Putnis et al. 2007 and Xia et al. 2009 have shown that even in pseudomorphic reactions where the molar volume increases, porosity may still be generated by the reaction. This is fundamental in understanding the element mobility and the mass transfer in a low permeability rock even more when the bulk rock composition of these two rocks stay unchanged; except a gain in water during amphibolitisation. The textural evolution during the replacement of garnet by pargasite, epidote and chlorite and pyroxene by hornblende and quartz in our rock sample conforms to that expected by a coupled dissolution-precipitation mechanism. SEM and Microprobe analysis coupled with the software XMapTools V 1.06.1 .(Lanari

Trans-Amazonian U-Th-Pb monazite ages and P-T-d exhumation paths of garnet-bearing leucogranite and migmatitic country rock of the southeastern Tandilia belt, Rio de la Plata craton in Argentina

NASA Astrophysics Data System (ADS)

Martínez, Juan Cruz; Massonne, Hans-Joachim; Frisicale, María Cristina; Dristas, Jorge A.

2017-03-01

A garnet-bearing leucogranite and two country rocks from the Transamazonian Tandilia belt of the Rio de la Plata craton were studied in detail. The leucogranite contains garnet with homogeneous composition of pyr6(gros + andr)2spes5alm87. In a garnet-biotite migmatite, the core and rim compositions of garnet are pyr1.7(gros + andr)5spes5.6alm87.7 and pyr1.2(gros + andr)5.5spes6.7alm86.6, respectively. These compositions in a sillimanite-garnet-muscovite migmatite are pyr4(gros + andr)2.7spes2.7alm90.6 and pyr2.7(gros + andr)4spes3.2alm90.1, respectively. We used this information to decipher the P-T evolution of the rocks applying P-T and T-H2O pseudosections with the PERPLE_X computer software package taking into consideration deformational microstructures. The leucogranite records an isothermal decompression from 5.3 to 3.8 kbar at 665 °C. The garnet-biotite migmatite was exhumed from 5.5 kbar at 630 °C to 4.3 kbar at 615 °C and the sillimanite-garnet-muscovite migmatite from supersolidus conditions of 670 °C and 3.6 kbar to 625 °C at 2.4 kbar. Late andalusite formed in this rock. Seventy four analyses of 28 monazite grains of the country rocks yielded three groups of U-Th-Pb ages which were related to a collisional event (I: ca. 2.13-2.14 Ga.), a postcollisional thermal overprint (II: ca. 2.01 Ga) and slow cooling of the orogen (III: 1.80-1.90 Ga). Inherited ages of 2.28 and 2.25 Ga could refer to an early accretionary stage of the orogen. An age of 2.41 Ga indicates the presence of recycled Siderian continental crust. Synkinematic crystallization of melts and the subsolidus development of an S2-foliation, demonstrated by deformational microstructures, occurred during the exhumation of the studied area from depths of 18 km to 8 km in the time interval 2.01-1.90 Ga.

Nanophase iron phosphate, iron arsenate, iron vanadate, and iron molybdate minerals synthesized within the protein cage of ferritin.

PubMed

Polanams, Jup; Ray, Alisha D; Watt, Richard K

2005-05-02

Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin.

Intravenous iron-dextran: studies on unsaturated iron-binding capacity

PubMed Central

Cox, J. S. G.; Moss, G. F.; Bremner, I.; Reason, Janet

1968-01-01

A method is described for measuring the plasma unsaturated iron-binding capacity in the presence of very high concentrations of iron as iron-dextran. The procedure utilizes 59Fe to label the apotransferrin with subsequent separation of ionic iron from transferrin-bound iron on an ion exchange or Sephadex G.25 column. The unsaturated iron-binding capacity has been measured in rabbits and dogs after intravenous injection of iron-dextran and in human subjects after total dose infusion of iron-dextran. No evidence of saturation of the unsaturated iron-binding capacity was found even when the plasma iron values were greater than 40,000 μg Fe/100 ml. PMID:5697365

Transparent ceramic garnet scintillator optimization via composition and co-doping for high-energy resolution gamma spectrometers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Beck, Patrick R.; Swanberg, Erik L.; Hunter, Steven L.

2016-09-01

Breakthrough energy resolution, R(662keV) <4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce), by optimizing fabrication conditions. Here we describe the dependence of scintillation light yield and energy resolution on several variables: (1) Stoichiometry, in particular Gd/Y and Ga/Al ratios which modify the bandgap energy, (2) Processing methods, including vacuum vs. oxygen sintering, and (3) Trace co-dopants that influence the formation of Ce4+ and modify the intra-bandgap trap distribution. To learn about how chemical composition influences the scintillation properties of transparent ceramic garnet scintillators, we have measured: scintillation decay component 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. Optimized GYGAG(Ce) provides R(662 keV) =3.0%, for 0.05 cm3 size ceramics with Silicon photodiode readout, and R(662 keV) =4.6%, at 2 in3 size with PMT readout.

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.

Direct 40Ar/39Ar age determination of fluid inclusions using in-vacuo¬ stepwise crushing - Example of garnet from the Cycladic Blueschist Unit on Syros

NASA Astrophysics Data System (ADS)

Uunk, Bertram; Postma, Onno; Wijbrans, Jan; Brouwer, Fraukje

2017-04-01

Metamorphic minerals and veins commonly trap attending hydrous fluids in fluid inclusions, which yield a wealth of information on the history of the hosting metamorphic system. When these fluids are sufficiently saline, the KCl in the inclusions can be used as a K/Ar geochronologic system, potentially dating inclusion incorporation. Whilst primary fluid inclusions (PFIs) can date fluid incorporation during mineral or vein growth, secondary fluid inclusion trails (SFIs) can provide age constraints on later fluid flow events. At VU Amsterdam, a new in-vacuo crushing apparatus has been designed to extract fluid inclusions from minerals for 40Ar/39Ar analysis. Separates are crushed inside a crusher tube connected to a purification line and a quadrupole mass spectrometer. In-vacuo crushing is achieved by lifting and dropping a steel pestle using an externally controlled magnetic field. As the gas can be analyzed between different crushing steps, the setup permits stepwise crushing experiments. Additionally, crushed powder can be heated by inserting the crusher tube in an externally controlled furnace. Dating by 40Ar/39Ar stepwise crushing has the added advantage that, during neutron irradiation to produce 39Ar from 39K, 38Ar and 37Ar are also produced from 38Cl and 40Ca, respectively. Simultaneous analysis of these argon isotopes permits constraining the chemistry of the argon source sampled during the experiment. This allows a distinction between different fluid or crystal lattice sources. Garnet from three samples of the HP metamorphic Cycladic Blueschist Unit on Syros, Greece was stepwise crushed to obtain fluid inclusion ages. Initial steps for all three experiments yield significant components of excess argon, which are interpreted to originate from grain boundary fluids and secondary fluid inclusions trails. During subsequent steps, age results stabilize to a plateau age. One garnet from North Syros yields an unusually old 80 Ma plateau age. However, isochrons

Ferritin accumulation under iron scarcity in Drosophila iron cells.

PubMed

Mehta, A; Deshpande, A; Bettedi, L; Missirlis, F

2009-10-01

Ferritins are highly stable, multi-subunit protein complexes with iron-binding capacities that reach 4500 iron atoms per ferritin molecule. The strict dependence of cellular physiology on an adequate supply of iron cofactors has likely been a key driving force in the evolution of ferritins as iron storage molecules. The insect intestine has long been known to contain cells that are responsive to dietary iron levels and a specialized group of "iron cells" that always accumulate iron-loaded ferritin, even when no supplementary iron is added to the diet. Here, we further characterize ferritin localization in Drosophila melanogaster larvae raised under iron-enriched and iron-depleted conditions. High dietary iron intake results in ferritin accumulation in the anterior midgut, but also in garland (wreath) cells and in pericardial cells, which together filter the circulating hemolymph. Ferritin is also abundant in the brain, where levels remain unaltered following dietary iron chelation, a treatment that depletes ferritin from the aforementioned tissues. We attribute the stability of ferritin levels in the brain to the function of the blood-brain barrier that may shield this organ from systemic iron fluctuations. Most intriguingly, our dietary manipulations demonstrably iron-depleted the iron cells without a concomitant reduction in their production of ferritin. Therefore, insect iron cells may constitute an exception from the evolutionary norm with respect to iron-dependent ferritin regulation. It will be of interest to decipher both the physiological purpose served and the mechanism employed to untie ferritin regulation from cellular iron levels in this cell type.

Crystal structure refinements of tetragonal (OH,F)-rich spessartine and henritermierite garnets

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

Antao, Sytle M.; Cruickshank, Laura A.

Cubic garnet (space group Ia\\overline 3 d) has the general formulaX 3Y 2Z 3O 12, whereX,YandZare cation sites. In the tetragonal garnet (space groupI4 1/acd), the corresponding cation sites areX1 andX2,Y, andZ1 andZ2. In both space groups only theYsite is the same. The crystal chemistry of a tetragonal (OH,F)-rich spessartine sample from Tongbei, near Yunxiao, Fujian Province, China, with composition X(Mn 2.82Fe^{2+}_{0.14}Ca 0.04) Σ3 Y{Al 1.95Fe^{3+}_{0.05}} Σ2 Z[(SiO 4) 2.61(O 4H 4) 0.28(F 4) 0.11] Σ3(Sps 94Alm 5Grs 1) was studied with single-crystal X-ray diffraction and space groupI4 1/acd. The deviation of the unit-cell parameters from cubic symmetry is smallmore » [a= 11.64463(1),c= 11.65481 (2) Å,c/a= 1.0009]. Point analyses and back-scattered electron images, obtained by electron-probe microanalysis, indicate a homogeneous composition. TheZ2 site is fully occupied, but theZ1 site contains vacancies. The occupiedZ1 andZ2 sites with Si atoms are surrounded by four O atoms, as in anhydrous cubic garnets. Pairs of split sites are O1 with F11 and O2 with O22. When theZ1 site is vacant, a larger [(O 2H 2)F 2] tetrahedron is formed by two OH and two F anions in the O22 and F11 sites, respectively. This [(O 2H 2)F 2] tetrahedron is similar to the O 4H 4tetrahedron in hydrogarnets. These results indicate ^{X}{{\\rm Mn}^ {2+}_{3}}\\,^{Y}{\\rm Al}_{2}^{Z}[({\\rm SiO}_{4})_{2}({\\rm O}_{2}{\\rm H}_{2})_{0.5}({\\rm F}_{2})_{0.5}]_{\\Sigma3} as a possible end member, which is yet unknown. The H atom that is bonded to the O22 site is not located because of the small number of OH groups. In contrast, tetragonal henritermierite, ideally ^{X}{\\rm Ca}_{3}\\,^{Y}{\\rm Mn}^{3+}_{2}\\,^{Z}[({\\rm SiO}_{4})_{2}({\\rm O}_{4}{\\rm H}_{4})_1]_{\\Sigma3}, has a vacantZ2 site that contains the O 4H 4tetrahedron. The H atom is bonded to an O3 atom [O3—H3 = 0.73 (2) Å]. Because of O2—Mn 3+—O2 Jahn–Teller elongation of the Mn 3+O 6octahedron, a weak hydrogen bond is

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.

Garnet Signatures in Geophysical and Geochemical Observations: Insights into the Thermo-Petrological Structure of Oceanic Upper Mantle

NASA Astrophysics Data System (ADS)

Grose, C. J.; Afonso, J. C.

2013-12-01

We have developed new physically comprehensive thermal plate models of the oceanic lithosphere which incorporate temperature- and pressure-dependent heat transport properties and thermal expansivity, melting beneath ridges, hydrothermal circulation near ridge axes, and insulating oceanic crust. These models provide good fits to global databases of seafloor topography and heat flow, and seismic evidence of thermal structure near ridge axes. We couple these thermal plate models with thermodynamic models to predict the petrology of oceanic lithosphere. Geoid height predictions from our models suggest that there is a strong anomaly in geoid slope (over age) above ~25 Ma lithosphere due to the topography of garnet-field mantle. A similar anomaly is also present in geoid data over fracture zones. In addition, we show that a new assessment of a large database of ocean island basalt Sm/Yb systematics indicates that there is an unmistakable step-like increase in Sm/Yb values around 15-20 Ma, indicating the presence of garnet. To explain this feature, we have attempted to couple our thermo-petrological models of oceanic upper mantle with an open system, non-modal, dynamic melting model with diffusion kinetics to investigate trace element partitioning in an ascending mantle column.

The first discovery of Hadean zircon in garnet granulites from the Sutam River (Aldan Shield)

NASA Astrophysics Data System (ADS)

Glukhovskii, M. Z.; Kuz'min, M. I.; Bayanova, T. B.; Lyalina, L. M.; Makrygina, V. A.; Shcherbakova, T. F.

2017-09-01

For the first time in Russia, a Hadean zircon grain with an age of 3.94 Ga (ID-TIMS) has been discovered in high-aluminous garnet granulites of the Aldan Shield among the U-Pb zircons with an age from 1.92 Ga. In this connection, the problems of its parental source, the petrogenesis of granulites that captured this zircon, and the mechanism of occurrence of these deep rocks in the upper horizons of the crust have been solved. The comparison of the geochemistry of garnet granulites and the middle crust has shown that the granulites are enriched in the entire range of rare-earth elements (except for the Eu minimum), as well as in Al2O3, U, and Th and are depleted in the most mobile elements (Na, Ca, Sr). In the upper part of the allitic weathering zone of the middle crust, which formed under conditions of arid climate, this zircon grain was originated from the weathered granites from the middle crust. In the latter case, they were empleced discretely in the upper granite-gneiss crust under high pressure conditions (the rutile age is 1.83-1.82 Ga). The zircon with an age of 3.94 Ga is comparable to the Hadean zircons from orthogneisses of the Acasta region (Canadian Shield, 4.03-3.94 Ga).

Theoretical and experimental studies of electronic, optical and luminescent properties for Tb-based garnet materials

NASA Astrophysics Data System (ADS)

Ding, Shoujun; Zhang, Haotian; Dou, Renqin; Liu, Wenpeng; Sun, Dunlu; Zhang, Qingli

2018-07-01

Terbium-aluminum (Tb3Al5O12: TAG) as well as Terbium-scandium-aluminum (Tb3Sc2Al3O12: TSAG) garnet materials have attracted tremendous attention around the world owing to their multifunctional applications. However, the electronic structure, optical and luminescent properties for TAG and TSAG are still requiring elucidation. To solve these intriguing problems, firstly, a systematic theoretical calculation based on the density functional theory methods were carried out on them and their electronic structure and optical properties were obtained. The calculated results indicating that both TAG and TSAG belongs to direct band gap materials category with band gap of 4.46 and 4.05 eV, respectively. Secondly, we compared the calculated results with the experimental results (including band gap, refractive index and reflectivity) and found that they were in good coincident. Lastly, we investigated the luminescence properties of TSAG and evaluated its probability for using as visible phosphor and laser matrix. In addition, a Judd-Ofelt theory calculation was performed on TSAG to reveal the radioactive transition of Tb-4f configuration and the three Judd-Ofelt intense parameters were obtained to be 4.47, 1.37 and 4.23 × 10-20 cm2, respectively. All of the obtained results can provide an essential understanding of TAG and TSAG garnet materials and also useful for the further exploration of them.

Syntheses, structure and magnetic properties of two vanadate garnets Ca{sub 5}M{sub 4}V{sub 6}O{sub 24} (M=Co, Ni)

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

Wang, Nannan; College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108; He, Zhangzhen, E-mail: hcz1988@hotmail.com

2015-08-15

Two vanadate compounds Ca{sub 5}M{sub 4}V{sub 6}O{sub 24} (M=Co, Ni) have been synthesized by a high-temperature solid-state reaction. The compounds are found to crystallize in the cubic system with a space group Ia-3d, which exhibit a typical garnet structural framework. Magnetic measurements show that Ca{sub 5}M{sub 4}V{sub 6}O{sub 24} (M=Co, Ni) exhibit similar magnetic behaviors, in which Ca{sub 5}Co{sub 4}V{sub 6}O{sub 24} possesses an antiferromagnetic ordering at T{sub N}=~6 K while Ca{sub 5}Ni{sub 4}V{sub 6}O{sub 24} shows an antiferromagnetic ordering at T{sub N}=~7 K. - Graphical abstract: Garnet vanadate compounds Ca{sub 5}M{sub 4}V{sub 6}O{sub 24} (M=Co, Ni) have been synthesizedmore » by a high-temperature solid-state reaction. Structural features and magnetic behaviors are also investigated. - Highlights: • New type of garnet vanadates Ca{sub 5}M{sub 4}V{sub 6}O{sub 24} (M=Co, Ni) are synthesized by a high-temperature solid-state reaction. • Structural features are confirmed by single crystal samples. • Magnetic behaviors are firstly investigated in the systems.« less

Iron deficiency and iron deficiency anaemia in women.

PubMed

Percy, Laura; Mansour, Diana; Fraser, Ian

2017-04-01

Iron deficiency (ID) is the most common micronutrient deficiency worldwide with >20% of women experiencing it during their reproductive lives. Hepcidin, a peptide hormone mostly produced by the liver, controls the absorption and regulation of iron. Understanding iron metabolism is pivotal in the successful management of ID and iron deficiency anaemia (IDA) using oral preparations, parenteral iron or blood transfusion. Oral preparations vary in their iron content and can result in gastrointestinal side effects. Parenteral iron is indicated when there are compliance/tolerance issues with oral iron, comorbidities which may affect absorption or ongoing iron losses that exceed absorptive capacity. It may also be the preferred option when rapid iron repletion is required to prevent physiological decompensation or given preoperatively for non-deferrable surgery. As gynaecologists, we focus on managing women's heavy menstrual bleeding (HMB) and assume that primary care clinicians are treating the associated ID/IDA. We now need to take the lead in diagnosing, managing and initiating treatment for ID/IDA and treating HMB simultaneously. This dual management will significantly improve their quality of life. In this chapter we will summarise the importance of iron in cellular functioning, describe how to diagnose ID/IDA and help clinicians choose between the available treatment options. Copyright © 2016. Published by Elsevier Ltd.

CLMSZ, Garnet Mountain area, southern California: A collisionally generated contractional shear zone

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

Bracchi, K.A.; Girty, G.H.; Girty, M.S.

1993-04-01

The Harper Creek gneiss (HCg) and Oriflamme Canyon unit (OCu) underlie the central portion of the Cuyamaca Laguna Mountains shear zone (CLMSZ) in and around Garnet Mountain, Peninsular Ranges, California, and may have been deformed during Cretaceous arc-continent collision. U-Pb zircon work and petrological and geochemical analyses suggest that in the Garnet Mountain area, the 140 Ma HCg is derived from granite and granodiorite, whereas the 122 [+-] 1 Ma OCu is a protomylonite derived from a granite. Both units appear to be per aluminous calc-alkaline magmatic arc granitoids. Mineral assemblages suggest uppermost greenschist to lower amphibolite grade conditions duringmore » deformation. In the HCg, S-1hc is a mylonitic gneissosity with a mean attitude of N11W, 60 NE. A mineral streaking lineation lies within the plane of S-1hc and has a mean attitude of 61[degree] N76E. In the OCu, S-1oc strikes about N13W and dips 52 NE and contains a mineral streaking lineation with an attitude of 49 N52E. Dextral and sinistral shear bands, S-2d and S-2s (looking NW), transect S-1hc and S-1oc. S-2d and S-2s strike subparallel to S-1. In the HCg S-2s is weakly developed and dips about 32 NE, whereas S-2d is more dominant and dips about 76 NE. On the OCu these relationships are reversed. S-2d does not cross cut S-2s: hence, the two sets of shear bands are interpreted to be conjugates reflecting NE-SW contraction and subvertical extension during collisional development of the CLMSZ.« less

46 CFR 56.60-10 - Cast iron and malleable iron.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Cast iron and malleable iron. 56.60-10 Section 56.60-10... APPURTENANCES Materials § 56.60-10 Cast iron and malleable iron. (a) The low ductility of cast iron and... avoided. Cast iron and malleable iron components shall not be used at temperatures above 450 °F. Cast iron...

Higher iron bioavailability of a human-like collagen iron complex.

PubMed

Zhu, Chenhui; Yang, Fan; Fan, Daidi; Wang, Ya; Yu, Yuanyuan

2017-07-01

Iron deficiency remains a public health problem around the world due to low iron intake and/or bioavailability. FeSO 4 , ferrous succinate, and ferrous glycinate chelate are rich in iron but have poor bioavailability. To solve the problem of iron deficiency, following previous research studies, a thiolated human-like collagen-ironcomplex supplement with a high iron content was prepared in an anaerobic workstation. In addition, cell viability tests were evaluated after conducting an MTT assay, and a quantitative analysis of the thiolated human-like collagen-iron digesta samples was performed using the SDS-PAGE method coupled with gel filtration chromatography. The iron bioavailability was assessed using Caco-2 cell monolayers and iron-deficiency anemia mice models. The results showed that (1) one mole of thiolated human-like collagen-iron possessed approximately 35.34 moles of iron; (2) thiolated human-like collagen-iron did not exhibit cytotoxity and (3) thiolated human-like collagen- iron digesta samples had higher bioavailability than other iron supplements, including FeSO 4 , ferrous succinate, ferrous glycine chelate and thiolated human-like collagen-Fe iron. Finally, the iron bioavailability was significantly enhanced by vitamin C. These results indicated that thiolated human-like collagen-iron is a promising iron supplement for use in the future.

Major and trace element modeling of mid-ocean ridge mantle melting from the garnet to the plagioclase stability fields: Generating local and global compositional variability

NASA Astrophysics Data System (ADS)

Brown, S. M.; Behn, M. D.; Grove, T. L.

2017-12-01

We present results of a combined petrologic - geochemical (major and trace element) - geodynamical forward model for mantle melting and subsequent melt modification. The model advances Behn & Grove (2015), and is calibrated using experimental petrology. Our model allows for melting in the plagioclase, spinel, and garnet fields with a flexible retained melt fraction (from pure batch to pure fractional), tracks residual mantle composition, and includes melting with water, variable melt productivity, and mantle mode calculations. This approach is valuable for understanding oceanic crustal accretion, which involves mantle melting and melt modification by migration and aggregation. These igneous processes result in mid-ocean ridge basalts that vary in composition at the local (segment) and global scale. The important variables are geophysical and geochemical and include mantle composition, potential temperature, mantle flow, and spreading rate. Accordingly, our model allows us to systematically quantify the importance of each of these external variables. In addition to discriminating melt generation effects, we are able to discriminate the effects of different melt modification processes (inefficient pooling, melt-rock reaction, and fractional crystallization) in generating both local, segment-scale and global-scale compositional variability. We quantify the influence of a specific igneous process on the generation of oceanic crust as a function of variations in the external variables. We also find that it is unlikely that garnet lherzolite melting produces a signature in either major or trace element compositions formed from aggregated melts, because when melting does occur in the garnet field at high mantle temperature, it contributes a relatively small, uniform fraction (< 10%) of the pooled melt compositions at all spreading rates. Additionally, while increasing water content and/or temperature promote garnet melting, they also increase melt extent, pushing the

Evidence that stainable bone marrow iron following parenteral iron therapy does not correlate with serum iron studies and may not represent readily available storage iron.

PubMed

Thomason, Ronald W; Almiski, Muhamad S

2009-04-01

We recently reported that parenteral iron therapy is associated with a characteristic pattern of iron staining on bone marrow aspirate smears. We now present clinical information from 6 patients who received parenteral iron and, at one or more points in follow-up, were found to have low or borderline low serum ferritin levels and/or serum iron levels, even though marrow aspirate smears revealed abundant stainable iron in the pattern characteristic of prior parenteral iron therapy. We conclude that stainable iron seen in this pattern does not correlate with serum iron studies and may not represent functionally available storage iron. This pattern of iron staining should not be used as evidence to withhold further iron therapy in patients who otherwise continue to have features of iron deficiency anemia.

Garnet Pyroxenites from Kaula, Hawaii: Implications for Plume-Lithosphere Interaction

NASA Astrophysics Data System (ADS)

Bizimis, M.; Garcia, M. O.; Norman, M. D.

2006-12-01

The presence of garnet pyroxenite xenoliths on Oahu and Kaula Islands, Hawaii, provides the rare opportunity to investigate the composition of the deeper oceanic mantle lithosphere and the nature of plume-lithosphere interaction in two dimensions, downstream from the center of the Hawaiian plume. Kaula (60 miles SW of Kauai) is on the same bathymetric shallow as Kauai and the Kaula-Niihau-Kauai islands form a cross-trend relationship to the Hawaiian Island ridge. Here, we present the first Sr-Nd isotope data on clinopyroxenes (cpx) from Kaula pyroxenites, and we compare them with the Salt Lake Crater (SLC) pyroxenites from Oahu. The Kaula cpx major element compositions overlap those of the (more variable) SLC pyroxenites (e.g. Mg# = 0.79-0.83), except for their higher Al2O3 contents (9% vs. 5-8%) than the SLC. The Kaula cpx are LREE enriched with elevated Dy/Yb ratios, similar to the SLC pyroxenites and characteristic of the presence of garnet that preferentially incorporates the HREE. In Sr-Nd isotope space, the Kaula pyroxenite compositions (87Sr/86Sr= 0.70312-0.70326, ɛNd= 7.2-8.6) overlap those of both the Oahu-Kauai post erosional lavas and the SLC pyroxenites, falling at the isotopically depleted end of the Hawaiian lava compositions. The depleted Sr-Nd isotope compositions of the Kaula pyroxenites suggest that they are not related to the isotopically enriched shield stage Hawaiian lavas, either as a source material (i.e. recycled eclogite) or as cumulates. Their elevated 87Sr/86Sr ratios relative to MORB also suggests that they are not likely MORB-related cumulates. The similarities between the Oahu and Kaula pyroxenites, some 200 km apart, suggest the widespread presence of pyroxenitic material in the deeper (>60km) Pacific lithosphere between Oahu and Kaula-Kauai, as high pressure cumulates from melts isotopically similar to the secondary Hawaiian volcanism. The presence of this material within the lower lithosphere is consistent with seismic observations

Dietary iron intake, iron status, and gestational diabetes.

PubMed

Zhang, Cuilin; Rawal, Shristi

2017-12-01

Pregnant women are particularly vulnerable to iron deficiency and related adverse pregnancy outcomes and, as such, are routinely recommended for iron supplementation. Emerging evidence from both animal and population-based studies, however, has raised potential concerns because significant associations have been observed between greater iron stores and disturbances in glucose metabolism, including increased risk of type 2 diabetes among nonpregnant individuals. Yet, the evidence is uncertain regarding the role of iron in the development of gestational diabetes mellitus (GDM), a common pregnancy complication which has short-term and long-term adverse health ramifications for both women and their children. In this review, we critically and systematically evaluate available data examining the risk of GDM associated with dietary iron, iron supplementation, and iron status as measured by blood concentrations of several indicators. We also discuss major methodologic concerns regarding the available epidemiologic studies on iron and GDM. © 2017 American Society for Nutrition.

The Irony of Iron – Biogenic Iron Oxides as an Iron Source to the Ocean

PubMed Central

Emerson, David

2016-01-01

Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB) that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity. PMID:26779157

Nonthermal ultrafast optical control of the magnetization in garnet films

NASA Astrophysics Data System (ADS)

Hansteen, Fredrik; Kimel, Alexey; Kirilyuk, Andrei; Rasing, Theo

2006-01-01

We demonstrate coherent optical control of the magnetization in ferrimagnetic garnet films on the femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses. Linearly polarized laser pulses are shown to create a long-lived modification of the magnetocrystalline anisotropy via optically induced electron transfer between nonequivalent ion sites while circularly polarized pulses additionally act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday effect. Due to the slow phonon-magnon interaction in these dielectrics, thermal effects of the laser excitation are clearly distinguished from the ultrafast nonthermal effects and can be seen only on the time scale of nanoseconds for sample temperatures near the Curie point. The reported effects open exciting possibilities for ultrafast manipulation of spins by light, and provide insight into the physics of magnetism on ultrafast time scales.

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.

Weathering of almandine garnet: influence of secondary minerals on the rate-determining step, and implications for regolith-scale Al mobilization

Treesearch

Jason R. Price; Debra S. Bryan-Ricketts; Diane Anderson; Michael A. Velbel

2013-01-01

Secondary surface layers form by replacement of almandine garnet during chemical weathering. This study tested the hypothesis that the kinetic role of almandine's weathering products, and the consequent relationships of primary-mineral surface texture and specific assemblages of secondary minerals, both vary with the solid-solution-controlled variations in Fe and...

Effects of calcium on hepatocyte iron uptake from transferrin, iron-pyrophosphate and iron-ascorbate.

PubMed

Nilsen, T

1991-10-16

Calcium stimulates hepatocyte iron uptake from transferrin, ferric-iron-pyrophosphate and ferrous-iron-ascorbate. Maximal stimulation of iron uptake is observed at 1-1.5 mM of extra-cellular calcium and the effect is reversible and immediate. Neither the receptor affinity for transferrin, nor the total amounts of transferrin associated with the cells or the rate of transferrin endocytosis are significantly affected by calcium. In the presence of calcium the rate of iron uptake of non-transferrin bound iron increases abruptly at approximate 17 degrees C and 27 degrees C and as assessed by Arrhenius plots, the activation energy is reduced in a calcium dependent manner at approx. 27 degrees C. At a similar temperature, i.e., between 25 degrees C and 28 degrees C, calcium increases the rates of cellular iron uptake from transferrin in a way that is not reflected in the rate of transferrin endocytosis. By the results of this study it is concluded that calcium increases iron transport across the plasma membrane by a mechanism dependent on membrane fluidity.

Response to parenteral iron therapy distinguish unexplained refractory iron deficiency anemia from iron-refractory iron deficiency anemia.

PubMed

Akin, M; Sarbay, H; Guler, S; Balci, Y I; Polat, A

2016-04-01

We evaluated that response to parenteral iron therapy could be helpful in distinguishing the types of iron deficiency anemia. This study analyzed responses to IV iron sucrose therapy of 15 children with unexplained refractory iron deficiency anemia (URIDA). We compared the results at diagnosis, 6 weeks and 6 months after the therapy. Results were compared with responses of 11 patients' results with iron-refractory iron deficiency anemia (IRIDA) from our previous study. Six weeks after the start of treatment, ferritin, MCV, MCH and Hb values were in normal range in 10 patients. The increase in Hb, MCH, MCV, and ferritin values ranged 2.6-3.5 g/dL, 1.7-4.2 pg, 2-9 fL, and 13-25 ng/mL, respectively. In five patients, Hb, MCH, and MCV mean (range) values [11.2 g/dL (11-12.2), 24.5 pg (24-25.6), and 67 fL (65-70)] were nearly normal but ferritin mean (range) values [9.8 ng/mL (8-11)] were below normal. Six weeks after the start of treatment, Hb, MCH, MCV and ferritin values of patients with IRIDA were increased. The increase in Hb, MCH, MCV, and ferritin values ranged 0.8-2.7 g/dL, 1.7-4.2 pg, 2-9 fL, and 13-25 ng/mL, respectively. IRIDA is only partially responsive to parenteral iron supplementation. In conclusion, this study demonstrated that the response to intravenous iron therapy for the URIDA cases improved blood parameters more effectively than hereditary IRIDA. Response to parenteral iron therapy would be helpful to distinguish unexplained refractory IDA from hereditary IRIDA for clinicians who do not have access to hepcidin or TMPRS6 mutation analysis. © 2016 John Wiley & Sons Ltd.

The Effect Of Local Coal And Smelting Sponge Iron On Iron Content Of Pig Iron

NASA Astrophysics Data System (ADS)

Oediyani, Soesaptri; Juwita Sari, Pramita; Hadi P, Djoko

2018-03-01

The new regulation on mineral resources was announced by Ministry of Energy and Mineral resources (ESDM) of Indonesia at 2014 which it called Permen ESDM No 1/2014. Therefore, this research was conducted to add the value of local iron ores by using smelting technology. The objective of the research is to produce pig iron that meet the requirement of the new regulation of mineral resources such as 90% Fe. First, iron ores and coal mixed together with lime as a flux, then smelted in a Electric Arc Furnace at 1800°C. The process variables are (1; 1.25; 1.5; 1.75; 2.0) and the composition of coal (0.8%, 1.6%, 3.0%). The type of coal that used in this research was bituminous coal from Kalimantan and also the iron ores from Kalimantan. The products of the smelting technology are Pig iron and slag. Both pig iron and slag then analyzed by SEM-EDS to measure the iron content. The result shows that the maximum iron content on pig iron is about 95.04% meanwhile the minimum iron content on slag is about 3.66%. This result achieved at 1.6% coal and 2.0.

Molecular control of vertebrate iron homeostasis by iron regulatory proteins

PubMed Central

Wallander, Michelle L.; Leibold, Elizabeth A.; Eisenstein, Richard S.

2008-01-01

Both deficiencies and excesses of iron represent major public health problems throughout the world. Understanding the cellular and organismal processes controlling iron homeostasis is critical for identifying iron-related diseases and in advancing the clinical treatments for such disorders of iron metabolism. Iron regulatory proteins (IRPs) 1 and 2 are key regulators of vertebrate iron metabolism. These RNA binding proteins post-transcriptionally control the stability or translation of mRNAs encoding proteins involved in iron homeostasis thereby controlling the uptake, utilization, storage or export of iron. Recent evidence provides insight into how IRPs selectively control the translation or stability of target mRNAs, how IRP RNA binding activity is controlled by iron-dependent and iron-independent effectors, and the pathological consequences of dysregulation of the IRP system. PMID:16872694

Iron regulatory proteins and their role in controlling iron metabolism.

PubMed

Kühn, Lukas C

2015-02-01

Cellular iron homeostasis is regulated by post-transcriptional feedback mechanisms, which control the expression of proteins involved in iron uptake, release and storage. Two cytoplasmic proteins with mRNA-binding properties, iron regulatory proteins 1 and 2 (IRP1 and IRP2) play a central role in this regulation. Foremost, IRPs regulate ferritin H and ferritin L translation and thus iron storage, as well as transferrin receptor 1 (TfR1) mRNA stability, thereby adjusting receptor expression and iron uptake via receptor-mediated endocytosis of iron-loaded transferrin. In addition splice variants of iron transporters for import and export at the plasma-membrane, divalent metal transporter 1 (DMT1) and ferroportin are regulated by IRPs. These mechanisms have probably evolved to maintain the cytoplasmic labile iron pool (LIP) at an appropriate level. In certain tissues, the regulation exerted by IRPs influences iron homeostasis and utilization of the entire organism. In intestine, the control of ferritin expression limits intestinal iron absorption and, thus, whole body iron levels. In bone marrow, erythroid heme biosynthesis is coordinated with iron availability through IRP-mediated translational control of erythroid 5-aminolevulinate synthase mRNA. Moreover, the translational control of HIF2α mRNA in kidney by IRP1 coordinates erythropoietin synthesis with iron and oxygen supply. Besides IRPs, body iron absorption is negatively regulated by hepcidin. This peptide hormone, synthesized and secreted by the liver in response to high serum iron, downregulates ferroportin at the protein level and thereby limits iron absorption from the diet. Hepcidin will not be discussed in further detail here.

DETERMINATION OF FERRITIN AND HEMOSIDERIN IRON IN PATIENTS WITH NORMAL IRON STORES AND IRON OVERLOAD BY SERUM FERRITIN KINETICS

PubMed Central

SAITO, HIROSHI; TOMITA, AKIHIRO; OHASHI, HARUHIKO; MAEDA, HIDEAKI; HAYASHI, HISAO; NAOE, TOMOKI

2012-01-01

ABSTRACT We attempted to clarify the storage iron metabolism from the change in the serum ferritin level. We assumed that the nonlinear decrease in serum ferritin was caused by serum ferritin increase in iron mobilization. Under this assumption, we determined both ferritin and hemosiderin iron levels by computer-assisted simulation of the row of decreasing assay-dots of serum ferritin in 11 patients with normal iron stores free of both iron deficiency and iron overload; chronic hepatitis C (CHC) and iron deficiency anemia after treatment, and 11 patients with iron overload; hereditary hemochromatosis (HH) and transfusion-dependent anemias (TD). We determined the iron removal rates of 20 and 17 mg/day by administering mean doses of deferasirox at 631 and 616 mg/day in 2 TD during the period of balance of iron addition and removal as indicated by the serum ferritin returned to the previous level. The ferritin-per-hemosiderin ratio was almost the same in both HH and CHC. This matched the localized hepatic hemosiderin deposition in CHC with normal iron stores. We detected the ferritin increased by utilizing the hemosiderin iron in iron removal and the ferritin reduced by transforming ferritin into hemosiderin in iron additions. The iron storing capacity of hemosiderin was limitless, while that of ferritin was suppressed when ferritin iron exceeded around 5 grams. We confirmed the pathway of iron from hemosiderin to ferritin in iron mobilization, and that from ferritin to hemosiderin in iron deposition. Thus, serum ferritin kinetics enabled us to be the first to clinically clarify storage iron metabolism. PMID:22515110

MR characterization of hepatic storage iron in transfusional iron overload.

PubMed

Tang, Haiying; Jensen, Jens H; Sammet, Christina L; Sheth, Sujit; Swaminathan, Srirama V; Hultman, Kristi; Kim, Daniel; Wu, Ed X; Brown, Truman R; Brittenham, Gary M

2014-02-01

To quantify the two principal forms of hepatic storage iron, diffuse, soluble iron (primarily ferritin), and aggregated, insoluble iron (primarily hemosiderin) using a new MRI method in patients with transfusional iron overload. Six healthy volunteers and 20 patients with transfusion-dependent thalassemia syndromes and iron overload were examined. Ferritin- and hemosiderin-like iron were determined based on the measurement of two distinct relaxation parameters: the "reduced" transverse relaxation rate, RR2 , and the "aggregation index," A, using three sets of Carr-Purcell-Meiboom-Gill (CPMG) datasets with different interecho spacings. Agarose phantoms, simulating the relaxation and susceptibility properties of tissue with different concentrations of dispersed (ferritin-like) and aggregated (hemosiderin-like) iron, were used for validation. Both phantom and in vivo human data confirmed that transverse relaxation components associated with the dispersed and aggregated iron could be separated using the two-parameter (RR2 , A) method. The MRI-determined total hepatic storage iron was highly correlated (r = 0.95) with measurements derived from biopsy or biosusceptometry. As total hepatic storage iron increased, the proportion stored as aggregated iron became greater. This method provides a new means for noninvasive MRI determination of the partition of hepatic storage iron between ferritin and hemosiderin in iron overload disorders. Copyright © 2013 Wiley Periodicals, Inc.

Quantification of body iron and iron absorption in the REDS-II Donor Iron Status Evaluation (RISE) study.

PubMed

Kiss, Joseph E; Birch, Rebecca J; Steele, Whitney R; Wright, David J; Cable, Ritchard G

2017-07-01

Repeated blood donation alters the iron balance of blood donors. We quantified these effects by analyzing changes in body iron as well as calculating iron absorbed per day for donors enrolled in a prospective study. For 1308 donors who completed a final study visit, we calculated total body iron at the enrollment and final visits and the change in total body iron over the course of the study. Taking into account iron lost from blood donations during the study and obligate losses, we also calculated the average amount of iron absorbed per day. First-time/reactivated donors at enrollment had iron stores comparable to previous general population estimates. Repeat donors had greater donation intensity and greater mean iron losses than first-time/reactivated donors, yet they had little change in total body iron over the study period, whereas first-time/reactivated donors had an average 35% drop. There was higher estimated iron absorption in the repeat donors (men: 4.49 mg/day [95% confidence interval [CI], 4.41-4.58 mg/day]; women: 3.75 mg/day [95% CI, 3.67-3.84 mg/day]) compared with estimated iron absorption in first-time/reactivated donors (men: 2.89 mg/day [95% CI, 2.75-3.04 mg/day]; women: 2.76 mg/day [95% CI, 2.64-2.87 mg/day]). The threshold for negative estimated iron stores (below "0" mg/kg stores) was correlated with the development of anemia at a plasma ferritin value of 10 ng/mL. These analyses provide quantitative data on changes in estimated total body iron for a broad spectrum of blood donors. In contrast to using ferritin alone, this model allows assessment of the iron content of red blood cells and the degree of both iron surplus and depletion over time. © 2017 AABB.

Optical investigation of domain resonances in magnetic garnet films

NASA Astrophysics Data System (ADS)

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

1996-08-01

Magnetic garnet films of composition (Y,Bi) 3(Fe,Al) 5O 12 are grown by liquid phase epitaxy on [111] oriented substrates of Gd 3Ga 5O 12. Lattices of parallel stripe domains are stabilized by a static induction applied in the film plane. The two branches DR ± of the domain resonance and the domain wall resonance DWR are excited by microwave magnetic fields in the frequency range up to 6 GHz. Light passing the stripe domain lattice parallel to the film normal is modulated at the excitation frequency. A modulation bandwidth of more than 2 GHz is observed. The resonances can be calculated with high accuracy by a hybridization model, if the quality factor Q of the film exceeds 0.5. For Q < 0.5 a simple approximation is used to describe the superposition of the DR + and DR - resonances. The superposition model predicts two stability states of the resonance DR + which are observed experimentally. From the optical measurements precession angles of the resonance DR - of nearly 6° and wall oscillation amplitudes up to 25 nm are derived.

[Iron concentration and acceptation of yoghurt prepared in casting iron pots (iron migration and acceptation of yogurt)].

PubMed

Quintaes, Késia Diego; Almeyda Haj-Isa, Niurka M; Morgano, Marcelo Antônio

2005-12-01

Food fortification is an interesting strategy to treat and prevent iron anemia. This study aims to quantify the iron in yoghurt, with gelatin and sugar and without, prepared in iron and glass containers. Sensorial test was use to evaluate the acceptance and preference of the both products. The yoghurt was prepared in containers of iron and glass with UHT milk, powder milk and natural industrialized yoghurt. After fermentation, half of the product received addition of sugar and strawberry flavor gelatin. The collected samples get the total iron quantified by ICP OES. Sensorial analysis involving 105 consumers was use to determine the acceptance and preference of the products. 0,018 and 0,882mg of iron per 100g added in the natural yoghurt prepared in the glass and in the iron pots, respectively. The yoghurt with gelatin presented 0,037 and 1,302mg of iron per 100g when prepared in the glass and in the iron pots, respectively. The preference was low for the yoghurt prepared in the iron pot (29,5%), but when added strawberry gelatin it was about 51,5%. The yoghurt prepared in iron pots, is easily home made and adds important amount of iron. Add gelatin and sugar can favored its consumption.

49 CFR 192.373 - Service lines: Cast iron and ductile iron.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the service...

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.

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

Iron state in iron nanoparticles with and without zirconium

NASA Astrophysics Data System (ADS)

Filippov, V. P.; Khasanov, A. M.; Lauer, Yu. A.

2017-11-01

Mössbauer and X-ray methods are used for investigations of structure, stability and characteristics of pure-iron grain and two iron-zirconium alloys such as Fe + 5 wt.% Zr and Fe + 10 wt.% Zr. The used powder was ground for 24 h in a SPEX Model 8000 mill shaker. Complex nanoparticles are found, which change their properties under milling. Mössbauer spectral parameters are obtained for investigated materials. Milling results in formation of nanosized particles with two states of iron atoms: one main part is pure α-Fe and another part of iron atoms displaced in grain boundaries or defective zones in which hyperfine magnetic splitting decrease to ˜ 30.0 T. In alloys with Zr three iron states are formed in each alloy, main part of iron is in the form of α-Fe and another two states depend on the concentration of Zr and represent iron in grain boundaries with Zr atoms in nearest neighbor. The changing of iron states is discussed.

Studying Irony Detection Beyond Ironic Criticism: Let's Include Ironic Praise

PubMed Central

Bruntsch, Richard; Ruch, Willibald

2017-01-01

Studies of irony detection have commonly used ironic criticisms (i.e., mock positive evaluation of negative circumstances) as stimulus materials. Another basic type of verbal irony, ironic praise (i.e., mock negative evaluation of positive circumstances) is largely absent from studies on individuals' aptitude to detect verbal irony. However, it can be argued that ironic praise needs to be considered in order to investigate the detection of irony in the variety of its facets. To explore whether the detection ironic praise has a benefit beyond ironic criticism, three studies were conducted. In Study 1, an instrument (Test of Verbal Irony Detection Aptitude; TOVIDA) was constructed and its factorial structure was tested using N = 311 subjects. The TOVIDA contains 26 scenario-based items and contains two scales for the detection of ironic criticism vs. ironic praise. To validate the measurement method, the two scales of the TOVIDA were experimentally evaluated with N = 154 subjects in Study 2. In Study 3, N = 183 subjects were tested to explore personality and ability correlates of the two TOVIDA scales. Results indicate that the co-variance between the ironic TOVIDA items was organized by two inter-correlated but distinct factors: one representing ironic praise detection aptitude and one representing ironic criticism detection aptitude. Experimental validation showed that the TOVIDA items truly contain irony and that item scores reflect irony detection. Trait bad mood and benevolent humor (as a facet of the sense of humor) were found as joint correlates for both ironic criticism and ironic praise detection scores. In contrast, intelligence, trait cheerfulness, and corrective humor were found as unique correlates of ironic praise detection scores, even when statistically controlling for the aptitude to detect ironic criticism. Our results indicate that the aptitude to detect ironic praise can be seen as distinct from the aptitude to detect ironic criticism. Generating

METABOLISM OF IRON STORES

PubMed Central

SAITO, HIROSHI

2014-01-01

ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since the pioneering research by Shoden in 1953. However, we recently developed a new method for determining ferritin iron and hemosiderin iron by computer-assisted serum ferritin kinetics. Serum ferritin increase or decrease curves were measured in patients with normal storage iron levels (chronic hepatitis C and iron deficiency anemia treated by intravenous iron injection), and iron overload (hereditary hemochromatosis and transfusion dependent anemia). We thereby confirmed the existence of two iron pathways where iron flows followed the numbered order (1) labile iron, (2) ferritin and (3) hemosiderin in iron deposition and mobilization among many previously proposed but mostly unproven routes. We also demonstrated the increasing and decreasing phases of ferritin iron and hemosiderin iron in iron deposition and mobilization. The author first demonstrated here the change in proportion between pre-existing ferritin iron and new ferritin iron synthesized by removing iron from hemosiderin in the course of iron removal. In addition, the author disclosed the cause of underestimation of storage iron turnover rate which had been reported by previous investigators in estimating storage iron turnover rate of normal subjects. PMID:25741033

Partitioning of Nd, Tb, Lu, and Hf Between Garnet and Ordinary Chondrite Melt at 5 to 9 GPa: Applications to Martian Differentiation

NASA Technical Reports Server (NTRS)

Draper, D. S.; Chabot, N. L.; Xirouchakis, D.; Wasserman, A. A.; Agee, C. B.

2001-01-01

One explanation for Al and REE depletions in SNC meteorites is early majorite fractionation in a deep martian magma ocean. We report initial results from an experimental investigation of partitioning between majoritic garnet and ordinary chondrite liquid. Additional information is contained in the original extended abstract.

New developments and controversies in iron metabolism and iron chelation therapy

PubMed Central

Kontoghiorghe, Christina N; Kontoghiorghes, George J

2016-01-01

Iron is essential for all organisms including microbial, cancer and human cells. More than a quarter of the human population is affected by abnormalities of iron metabolism, mainly from iron deficiency and iron overload. Iron also plays an important role in free radical pathology and oxidative damage which is observed in almost all major diseases, cancer and ageing. New developments include the complete treatment of iron overload and reduction of morbidity and mortality in thalassaemia using deferiprone and selected deferiprone/deferoxamine combinations and also the use of the maltol iron complex in the treatment of iron deficiency anaemia. There is also a prospect of using deferiprone as a universal antioxidant in non iron overloaded diseases such as neurodegenerative, cardiovascular, renal, infectious diseases and cancer. New regulatory molecules of iron metabolism such as endogenous and dietary chelating molecules, hepcidin, mitochondrial ferritin and their role in health and disease is under evaluation. Similarly, new mechanisms of iron deposition, removal, distribution and toxicity have been identified using new techniques such as magnetic resonance imaging increasing our understanding of iron metabolic processes and the targeted treatment of related diseases. The uniform distribution of iron in iron overload between organs and within each organ is no longer valid. Several other controversies such as the toxicity impact of non transferrin bound iron vs injected iron, the excess levels of iron in tissues causing toxicity and the role of chelation on iron absorption need further investigation. Commercial interests of pharmaceutical companies and connections to leading journals are playing a crucial role in shaping worldwide medical opinion on drug sales and use but also patients’ therapeutic outcome and safety. Major controversies include the selection criteria and risk/benefit assessment in the use of deferasirox in thalassaemia and more so in idiopathic

Flexible interfaces between Si anodes and composite electrolytes consisting of poly(propylene carbonates) and garnets for solid-state batteries

NASA Astrophysics Data System (ADS)

Huo, Hanyu; Sun, Jiyang; chen, Cheng; Meng, Xianglu; He, Minghui; Zhao, Ning; Guo, Xiangxin

2018-04-01

Flexible interfaces between Si anodes and composite electrolytes consisting of poly(propylene carbonates) (PPCs) and garnets have been fabricated. The solid polymer electrolytes (SPEs) of PPC/garnet/LiTFSI show the conductivity of 4.2 × 10-4 S cm-1 at room temperature. Their combination with the Si layer anodes allows great alleviation of internal stress resulting from the large volume variation during lithiation and delithiation process of Si anodes. As a result, the Si/SPE/Li cells exhibit 2520 mAh g-1, 2260 mAh g-1, 1902 mAh g-1, 1342 mAh g-1 at 0.1 C, 0.2 C, 0.5 C, and 1 C, respectively. Furthermore, with such compatible and stable interfaces of Si/SPE and the LiFePO4 cathodes in solid-state batteries, the specific capacity of 2296 mAh g-1 in terms of Si is obtained, which remains 82.6% after 100 cycles at room temperature and 0.1 C. The results here indicate that constructing of flexible interfaces between Si anodes and SPEs is a promising strategy to develop high performance solid-state batteries.

Age and composition of the UHP garnet peridotites in the Dabie orogenic belt (central China) record complex crust-mantle interaction in continental margin

NASA Astrophysics Data System (ADS)

Zhao, Y.; Zheng, J.; Wang, B.

2017-12-01

The Dabie-Sulu UHP belt was created by the collision between the North and South China cratons in Middle Triassic time (240-225 Ma). There are lots of garnet-bearing ultramafic body occurs as a lens in the belt. Age and composition of the Maowu garnet peridotites in the Dabie orogenic belt are reported. The garnet harzburgites are main moderately refractory (Mg#Ol=92) and minor fertile (Mg#Ol=88) with high Ni (2344-2603 ppm) and low Al2O3 (0.35-0.54 wt.%), CaO (0.76-2.19 wt.%) and TiO2 (˜0.01 wt.%). Zircons in the harzburgites mainly document metamorphism at 230 ± 2 Ma, 275 ± 5 Ma, 357 ± 4 Ma, and complex minor populations of ages including: 1.8 Ga, 1.3 Ga, and Neoproterozic-early Paleozoic ages (901-420 Ma). The early Meszosic and late Paleozoic zircons have similar trace-element patterns and ranges in ɛHf(t) (+0.6 to +3.4), Th/U ratio (0.2-0.7) and Hf depleted-mantle model ages (TDM ) mainly cluster in the interval 1.2-0.9 Ga. In contrast, the Paleo-Mesoproterozoic zircons have negative ɛHf(t) (-24.9 to -2.7) and oldest Hf TDM = 3.4Ga. Zircons of Neoproterozic-early Paleozoic have a wide range of Hf depleted-mantle model ages (2.4-0.7Ga) and ɛHf(t) (-15.3 to +9.5). Above of the all, we suggest that the Maowu garnet harzburgites are interpreted as a fragment of the metasomatized ancient lithospheric mantle beneath the southern margin of the North China Craton. They experienced the Proterozoic thermal event (1.9-1.8Ga), which is coeval with the assembly of the supercontinent Columbia. And then 1.3Ga mantle metasomatism with asthenospheric materials resulted in the final breakup of the Columbia supercontinent. Neoproterozic-early Paleozoic (901-420 Ma), deep parts of the south margin of the craton were metasomatized during the assembly and breakup of the Rodinia supercontinent. Then, the southern margin of the craton occurred oceanic crust subduction ( 357 Ma), subsequent continental deep subduction and final continent-continent collision in Triassic.

From crustal protoliths to mantle garnet pyroxenites: a highly siderophile elements and Os isotope perspective from the Ligurian mantle section (N. Apennine, Italy)

NASA Astrophysics Data System (ADS)

Montanini, A.; Luguet, A.; van Acken, D.; Tribuzio, R.

2017-12-01

Pyroxenites are a major form of mantle heterogeneity and may originate through migration of melts or recycling of mafic crustal lithologies. Here, we present HSE (Os, Ir, Pt, Pd, Re) and 187Os/188Os isotopic systematics of "aged" pyroxenites (Mg-rich, Al-poor garnet websterites and Al-rich garnet clinopyroxenites) enclosed in fertile mantle sequences of the Jurassic Alpine-Apennine ophiolites. The garnet clinopyroxenites have heterogeneous mafic crustal precursors that experienced a long-lived evolution of recycling into the mantle (1.5-1.0 Ga) as inferred from Lu-Hf isotope systematics. They originated as melt-dominated systems by crystallization of eclogite-derived melts. The websterites were interpreted as hybrid lithologies with a crustal geochemical fingerprint and a larger peridotite wall rock contribution. The host lherzolites show flat CI-chondrite-normalized HSE patterns. All the pyroxenites are variably depleted in Os and Ir and enriched in the incompatible HSE (Pt, Pd and Re) with respect to host peridotites and have flat to negatively sloping Pd-Re segments. Centimetre- to metre-scale 187Os isotopic heterogeneity is observed in the investigated mantle sequence. The initial 187Os/188Os ratios recalculated for the age of the Mesozoic partial melting event inferred from Nd-Hf isotope systematics are unradiogenic to slightly radiogenic in the peridotites (0.124-0.134) and vary from moderately to highly radiogenic in the pyroxenites (0.149-2.190). Bulk rock HSE compositions of the pyroxenites do not match gabbroic eclogites nor residua after eclogite partial melting, in agreement with lithophile element geochemistry. The HSE patterns of the garnet clinopyroxenites are related to sulphur saturation and sulfide crystallization from partial melts of gabbro-derived eclogites. Decoupling between Re/Os (TMa = 2.0-2.8 Ga) and Lu-Hf isotope systematics of the pyroxenites may be due to fractionation of Re/Os ratios with no Os isotopic homogenization of the sulfide

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.

SOFIA EXES Observations of Herschel’s Garnet Star and the two α Red Supergiants

NASA Astrophysics Data System (ADS)

Harper, Graham M.; DeWitt, Curtis N.; Richter, Matthew; Guinan, Edward F.; Montiel, Edward; Bennett, Philip D.; EXES Instrument Team

2018-06-01

We report EXES Cycle 4 and 5 observations of M supergiants, made at high spectral resolution (R > 50,000), and obtained from NASA-DLR SOFIA.Emission profiles from Herschel’s Garnet Star (μ Cephei: M2 Ia) show distinct structure and asymmetry in the [S I] 25.25 micron and [Fe II] 25.99 micron lines. These profiles are unlike the remarkably symmetric [Fe II] profile observed from Betelgeuse (α Orionis: M2 Iab) at R=65,000. These diagnostics both arise from upper energy levels with Eup ≈ 550 K and they probe the inner circumstellar envelope. The flux ratios of [S I]/[Fe II] are very different for μ Cep, α Ori, and Antares (α Scorpii: M1.5 Iab), suggesting that the intrinsic far ultraviolet photoionization field of μ Cep is weaker than that of α Ori, and that α Sco’s hot companion may contribute to ionizing neutral sulfur. We find that the mid-IR emission from μ Cep is centered close to the optical radial velocity of V(LSR)=33.0 km s-1 [V(Helio)=19.3 km s-1] reported in the General Catalogue of Stellar Radial Velocities (Wilson 1953), and which is substantially different to that inferred from low-J CO radio emission, i.e. V(LSR)=25 km s-1. It appears that Herschel's Garnet Star has undergone discrete events of asymmetric mass loss.Acknowledgements: This work has made extensive use of the SAO/NASA ADS and VizieR search tools, and the ASTRAL and SIMBAD databases. Financial support has been provided by NASA SOFIA Cycle 4 and 5 grants SOF 04-0136 and 05-0073 issued by USRA.

Iron deficiency and iron excess damage mitochondria and mitochondrial DNA in rats

PubMed Central

Walter, Patrick B.; Knutson, Mitchell D.; Paler-Martinez, Andres; Lee, Sonia; Xu, Yu; Viteri, Fernando E.; Ames, Bruce N.

2002-01-01

Approximately two billion people, mainly women and children, are iron deficient. Two studies examined the effects of iron deficiency and supplementation on rats. In study 1, mitochondrial functional parameters and mitochondrial DNA (mtDNA) damage were assayed in iron-deficient (≤5 μg/day) and iron-normal (800 μg/day) rats and in both groups after daily high-iron supplementation (8,000 μg/day) for 34 days. This dose is equivalent to the daily dose commonly given to iron-deficient humans. Iron-deficient rats had lower liver mitochondrial respiratory control ratios and increased levels of oxidants in polymorphonuclear-leukocytes, as assayed by dichlorofluorescein (P < 0.05). Rhodamine 123 fluorescence of polymorphonuclear-leukocytes also increased (P < 0.05). Lowered respiratory control ratios were found in daily high-iron-supplemented rats regardless of the previous iron status (P < 0.05). mtDNA damage was observed in both iron-deficient rats and rats receiving daily high-iron supplementation, compared with iron-normal rats (P < 0.05). Study 2 compared iron-deficient rats given high doses of iron (8,000 μg) either daily or every third day and found that rats given iron supplements every third day had less mtDNA damage on the second and third day after the last dose compared to daily high iron doses. Both inadequate and excessive iron (10 × nutritional need) cause significant mitochondrial malfunction. Although excess iron has been known to cause oxidative damage, the observation of oxidant-induced damage to mitochondria from iron deficiency has been unrecognized previously. Untreated iron deficiency, as well as excessive-iron supplementation, are deleterious and emphasize the importance of maintaining optimal iron intake. PMID:11854522

Zinc deficiency-induced iron accumulation, a consequence of alterations in iron regulatory protein-binding activity, iron transporters, and iron storage proteins.

PubMed

Niles, Brad J; Clegg, Michael S; Hanna, Lynn A; Chou, Susan S; Momma, Tony Y; Hong, Heeok; Keen, Carl L

2008-02-22

One consequence of zinc deficiency is an elevation in cell and tissue iron concentrations. To examine the mechanism(s) underlying this phenomenon, Swiss 3T3 cells were cultured in zinc-deficient (D, 0.5 microM zinc), zinc-supplemented (S, 50 microM zinc), or control (C, 4 microM zinc) media. After 24 h of culture, cells in the D group were characterized by a 50% decrease in intracellular zinc and a 35% increase in intracellular iron relative to cells in the S and C groups. The increase in cellular iron was associated with increased transferrin receptor 1 protein and mRNA levels and increased ferritin light chain expression. The divalent metal transporter 1(+)iron-responsive element isoform mRNA was decreased during zinc deficiency-induced iron accumulation. Examination of zinc-deficient cells revealed increased binding of iron regulatory protein 2 (IRP2) and decreased binding of IRP1 to a consensus iron-responsive element. The increased IRP2-binding activity in zinc-deficient cells coincided with an increased level of IRP2 protein. The accumulation of IRP2 protein was independent of zinc deficiency-induced intracellular nitric oxide production but was attenuated by the addition of the antioxidant N-acetylcysteine or ascorbate to the D medium. These data support the concept that zinc deficiency can result in alterations in iron transporter, storage, and regulatory proteins, which facilitate iron accumulation.

Out of Balance—Systemic Iron Homeostasis in Iron-Related Disorders

PubMed Central

Steinbicker, Andrea U.; Muckenthaler, Martina U.

2013-01-01

Iron is an essential element in our daily diet. Most iron is required for the de novo synthesis of red blood cells, where it plays a critical role in oxygen binding to hemoglobin. Thus, iron deficiency causes anemia, a major public health burden worldwide. On the other extreme, iron accumulation in critical organs such as liver, heart, and pancreas causes organ dysfunction due to the generation of oxidative stress. Therefore, systemic iron levels must be tightly balanced. Here we focus on the regulatory role of the hepcidin/ferroportin circuitry as the major regulator of systemic iron homeostasis. We discuss how regulatory cues (e.g., iron, inflammation, or hypoxia) affect the hepcidin response and how impairment of the hepcidin/ferroportin regulatory system causes disorders of iron metabolism. PMID:23917168

Mammalian iron metabolism and its control by iron regulatory proteins☆

PubMed Central

Anderson, Cole P.; Shen, Lacy; Eisenstein, Richard S.; Leibold, Elizabeth A.

2013-01-01

Cellular iron homeostasis is maintained by iron regulatory proteins 1 and 2 (IRP1 and IRP2). IRPs bind to iron-responsive elements (IREs) located in the untranslated regions of mRNAs encoding protein involved in iron uptake, storage, utilization and export. Over the past decade, significant progress has been made in understanding how IRPs are regulated by iron-dependent and iron-independent mechanisms and the pathological consequences of IRP2 deficiency in mice. The identification of novel IREs involved in diverse cellular pathways has revealed that the IRP–IRE network extends to processes other than iron homeostasis. A mechanistic understanding of IRP regulation will likely yield important insights into the basis of disorders of iron metabolism. This article is part of a Special Issue entitled: Cell Biology of Metals. PMID:22610083

Iron-binding haemerythrin RING ubiquitin ligases regulate plant iron responses and accumulation

PubMed Central

Kobayashi, Takanori; Nagasaka, Seiji; Senoura, Takeshi; Itai, Reiko Nakanishi; Nakanishi, Hiromi; Nishizawa, Naoko K.

2013-01-01

Iron is essential for most living organisms. Plants transcriptionally induce genes involved in iron acquisition under conditions of low iron availability, but the nature of the deficiency signal and its sensors are unknown. Here we report the identification of new iron regulators in rice, designated Oryza sativa Haemerythrin motif-containing Really Interesting New Gene (RING)- and Zinc-finger protein 1 (OsHRZ1) and OsHRZ2. OsHRZ1, OsHRZ2 and their Arabidopsis homologue BRUTUS bind iron and zinc, and possess ubiquitination activity. OsHRZ1 and OsHRZ2 are susceptible to degradation in roots irrespective of iron conditions. OsHRZ-knockdown plants exhibit substantial tolerance to iron deficiency, and accumulate more iron in their shoots and grains irrespective of soil iron conditions. The expression of iron deficiency-inducible genes involved in iron utilization is enhanced in OsHRZ-knockdown plants, mostly under iron-sufficient conditions. These results suggest that OsHRZ1 and OsHRZ2 are iron-binding sensors that negatively regulate iron acquisition under conditions of iron sufficiency. PMID:24253678

Ferritin iron minerals are chelator targets, antioxidants, and coated, dietary iron.

PubMed

Theil, Elizabeth C

2010-08-01

Cellular ferritin is central for iron balance during transfusions therapies; serum ferritin is a small fraction of body ferritin, albeit a convenient reporter. Iron overload induces extra ferritin protein synthesis but the protein is overfilled with the extra iron that damages ferritin, with conversion to toxic hemosiderin. Three new approaches that manipulate ferritin to address excess iron, hemosiderin, and associated oxidative damage in Cooley's Anemia and other iron overload conditions are faster removal of ferritin iron with chelators guided to ferritin gated pores by peptides; more ferritin protein synthesis using ferritin mRNA activators, by metal complexes that target mRNA 3D structures; and determining if endocytotic absorption of iron from legumes, which is mostly ferritin, is regulated during iron overload to prevent excess iron entry while providing protein. More of a focus on ferritin features, including protein cage structure, iron mineral, regulatable mRNA, and specific gut absorption properties, will achieve the three novel experimental goals for managing iron homeostasis with transfusion therapies.

Siderophore-mediated iron trafficking in humans is regulated by iron

PubMed Central

Liu, Zhuoming; Lanford, Robert; Mueller, Sebastian; Gerhard, Glenn S.; Luscieti, Sara; Sanchez, Mayka; Devireddy, L.

2013-01-01

Siderophores are best known as small iron binding molecules that facilitate microbial iron transport. In our previous study we identified a siderophore-like molecule in mammalian cells and found that its biogenesis is evolutionarily conserved. A member of the short chain dehydrogenase family of reductases, 3-OH butyrate dehydrogenase (BDH2) catalyzes a rate-limiting step in the biogenesis of the mammalian siderophore. We have shown that depletion of the mammalian siderophore by inhibiting expression of bdh2 results in abnormal accumulation of cellular iron and mitochondrial iron deficiency. These observations suggest that the mammalian siderophore is a critical regulator of cellular iron homeostasis and facilitates mitochondrial iron import. By utilizing bioinformatics, we identified an iron-responsive element (IRE; a stem-loop structure that regulates genes expression post-transcriptionally upon binding to iron regulatory proteins or IRPs) in the 3′-untranslated region (3′-UTR) of the human BDH2 (hBDH2) gene. In cultured cells as well as in patient samples we now demonstrate that the IRE confers iron-dependent regulation on hBDH2 and binds IRPs in RNA electrophoretic mobility shift assays. In addition, we show that the hBDH2 IRE associates with IRPs in cells and that abrogation of IRPs by RNAi eliminates the iron-dependent regulation of hBDH2 mRNA. The key physiologic implication is that iron-mediated post-transcriptional regulation of hBDH2 controls mitochondrial iron homeostasis in human cells. These observations provide a new and an unanticipated mechanism by which iron regulates its intracellular trafficking. PMID:22527885

Iron overdose

MedlinePlus

... 1222) from anywhere in the United States. Poisonous Ingredient Iron can be harmful in large amounts. Where Found Iron is an ingredient in many mineral and vitamin supplements. Iron supplements ...

Phase diagram and high degeneracy points for generic anisotropic exchange on the garnet lattice

NASA Astrophysics Data System (ADS)

Andreanov, Alexei; McClarty, Paul

Garnet magnets with chemical formula RE3Ga5O12 where RE is a rare earth ion have properties that are determined by a combination of geometrical frustration and strong spin-orbit coupling. The former arises from the RE structure which consists of two interpenetrating hyperkagome lattices while the latter leads, in general, to an anisotropy in the magnetic exchange. We systematically explore and describe the full phase diagram for the case of all nearest-neighbor interactions compatible with lattice symmetries and consider the role of fluctuations and further neighbor couplings around high degeneracy points in the phase diagram. AA was supported by Project Code(IBS-R024-D1).

Iron release from the Lucky Iron Fish®: safety considerations.

PubMed

Armstrong, Gavin R; Dewey, Cate E; Summerlee, Alastair Js

2017-01-01

The principal objective was to explore in greater detail safety issues with regard to the use of the Lucky Iron Fish® (fish) as a treatment for iron deficiency and iron deficiency anaemia in women in rural Cambodia. Experiments were done to determine: (1) purity of the iron in the fish by mass spectroscopy; (2) release of iron and contaminants released during boiling in water using inductive-ly-coupled plasma optical emission spectroscopy; (3) the impact of cooking time, acidity and number of fish in acidified water and two types of Khmer soups; and (4) drinkability of the water after boiling with different num-bers of fish. The fish is composed primarily of ferrous iron with less than 12% non-ferrous iron. Contaminants were either not detectable or levels were below the acceptable standards set by the World Health Organization. The length of time boiling the fish and the acidity of the water increased iron release but even with 5 fish boiled for 60 minutes, iron levels only approached levels where side effects are observed. Boiling one fish in water did not affect the perception of colour, smell or taste of the water but boiling in water with two or more fish resulted in the water being unpalatable which further limits the potential for iron toxicity from using the fish. The results suggest that the Lucky Iron Fish™ may be a safe treatment for iron deficiency.

New insights into iron deficiency and iron deficiency anemia.

PubMed

Camaschella, Clara

2017-07-01

Recent advances in iron metabolism have stimulated new interest in iron deficiency (ID) and its anemia (IDA), common conditions worldwide. Absolute ID/IDA, i.e. the decrease of total body iron, is easily diagnosed based on decreased levels of serum ferritin and transferrin saturation. Relative lack of iron in specific organs/tissues, and IDA in the context of inflammatory disorders, are diagnosed based on arbitrary cut offs of ferritin and transferrin saturation and/or marker combination (as the soluble transferrin receptor/ferritin index) in an appropriate clinical context. Most ID patients are candidate to traditional treatment with oral iron salts, while high hepcidin levels block their absorption in inflammatory disorders. New iron preparations and new treatment modalities are available: high-dose intravenous iron compounds are becoming popular and indications to their use are increasing, although long-term side effects remain to be evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reducing iron deficiency anemia in Bolivian school children: calcium and iron combined versus iron supplementation alone.

PubMed

Miranda, Melissa; Olivares, Manuel; Brito, Alex; Pizarro, Fernando

2014-01-01

The aim of this study was to determine the effect of combined calcium and iron versus single iron supplementation on iron status in Bolivian schoolchildren. Children ages 6 to 10 y old (N = 195), were randomly assigned to receive either 700 mg Ca (as calcium carbonate) plus 30 mg Fe (as ferrous sulfate) (Ca + Fe group) or 30 mg Fe (as ferrous sulfate) (Fe group). The doses were administered daily, from Monday to Friday, between meals at school over 3 mo. Iron status was assessed at baseline and after intervention. Additionally, overall nutritional status was assessed by anthropometry and an estimation of dietary intake. At baseline, the prevalence of anemia in the Ca + Fe group and the Fe group were 15% and 21.5%, respectively. After 3 mo follow-up, the prevalence of iron deficiency anemia dropped significantly (P < 0.001) to 3% in both groups (χ(2) = NS). Iron dietary intake was within recommended levels, but calcium intake only covered 39% of the Recommended Daily Intake. Combined calcium and iron supplementation is equally as effective as single iron supplementation in reducing the prevalence of iron deficiency anemia in Bolivian school children. Copyright © 2014 Elsevier Inc. All rights reserved.

Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism

PubMed Central

Horniblow, Richard D.; Dowle, Miriam; Iqbal, Tariq H.; Latunde-Dada, Gladys O.; Palmer, Richard E.

2015-01-01

Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease. PMID:26378798

[Old and new iron parameters in iron metabolism and diagnostics].

PubMed

Graf, Lukas; Herklotz, Roberto; Huber, Andreas R; Korte, Wolfgang

2008-09-01

Iron is an element which is essential to life but also potentially toxic. Therefore, clever mechanisms exist in the human body for uptake, transport and storage of iron. Hepcidin, which seems to be the master protein for regulation of intestinal iron absorption, is known for a short time. The expression of hepcidin is not only influenced by iron levels but also by mediators of inflammation and growth factors of erythropoiesis. Hence hepcidin plays also a crucial role in the development of anemia of chronic disease and iron overload due to ineffective erythropoiesis. Serum ferritin is a reliable parameter to estimate the storage iron. It is an acute phase protein which is elevated during infections and inflammations, though. In these situations, measurement of soluble transferrin receptors is a useful tool to differentiate between iron deficiency and anemia of chronic disease. Newer parameters as erythrocyte zink protoporphyrin or percentage of hypochromic erythrocytes (%HYPO) are suited to detect a functional iron deficiency. Early diagnosis of iron overload is essential to prevent organ damage. Serum ferritin and transferrin are useful parameters to screen for iron overload. If no clear reason for a secondary iron overload can be found, the search for a hereditary haemochromatosis is recommended. Most of these hereditary haemochromatoses are a result of mutations in the HFE gene (homozygous state for Cys282Tyr or compound heterozygosity for Cys282Tyr/ His63Asp) which can be detected by PCR technique. Liver biopsy is still the gold standard for quantification of storage iron. However, a method of increasing importance for quantification of iron overload is magnetic resonance imaging with new approaches as for example T2*.

Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

NASA Astrophysics Data System (ADS)

Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

2016-11-01

Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

Iron Chelation

MedlinePlus

... fortified cereals and eggs. What is Iron Chelation Therapy? Drugs called iron chelators remove extra iron from ... form that must be dissolved in juice or water and taken (by mouth) once a day. Most ...

Development of composite ceramic materials with improved thermal conductivity and plasticity based on garnet-type oxides

NASA Astrophysics Data System (ADS)

Golovkina, L. S.; Orlova, A. I.; Boldin, M. S.; Sakharov, N. V.; Chuvil'deev, V. N.; Nokhrin, A. V.; Konings, R.; Staicu, D.

2017-06-01

Powders based on the complex garnet-type oxide Y2.5Nd0.5Al5O12 - x wt. % Ni (x = 0, 10, 20) were prepared using wet chemistry methods. Ceramics based on these compounds were obtained by Spark Plasma Sintering (SPS) with a relative densities: 99%. 4% (TD = 4.77 g/cm3 (0%)), 97.6% (TD = 4.88 g/cm3 (10%)), 94.4% (TD = 5.06 g/cm3 (20%)). The influence of nickel concentration on the mechanical (fracture toughness, microhardness) and thermophysical (thermal conductivity) properties of the composites was studied.

Magnetic Resonance Characterization of Hepatic Storage Iron in Transfusional Iron Overload

PubMed Central

Tang, Haiying; Jensen, Jens H.; Sammet, Christina L.; Sheth, Sujit; Swaminathan, Srirama V.; Hultman, Kristi; Kim, Daniel; Wu, Ed X.; Brown, Truman R.; Brittenham, Gary M.

2013-01-01

Purpose To quantify the two principal forms of hepatic storage iron, diffuse, soluble iron (primarily ferritin), and aggregated, insoluble iron (primarily hemosiderin) using a new MRI method in patients with transfusional iron overload. Materials and Methods Six healthy volunteers and twenty patients with transfusion-dependent thalassemia syndromes and iron overload were examined. Ferritin- and hemosiderin-like iron were determined based on the measurement of two distinct relaxation parameters: the “reduced” transverse relaxation rate, RR2 and the “aggregation index,” A, using three sets of Carr-Purcell-Meiboom-Gill (CPMG) datasets with different interecho spacings. Agarose phantoms, simulating the relaxation and susceptibility properties of tissue with different concentrations of dispersed (ferritin-like) and aggregated (hemosiderin-like) iron, were employed for validation. Results Both phantom and in vivo human data confirmed that transverse relaxation components associated with the dispersed and aggregated iron could be separated using the two-parameter (RR2, A) method. The MRI-determined total hepatic storage iron was highly correlated (r = 0.95) with measurements derived from biopsy or biosusceptometry. As total hepatic storage iron increased, the proportion stored as aggregated iron became greater. Conclusion This method provides a new means for non-invasive MRI determination of the partition of hepatic storage iron between ferritin and hemosiderin in iron overload disorders. PMID:23720394

Efficacy of iron fortification compared to iron supplementation among Vietnamese schoolchildren

PubMed Central

Thi Le, Huong; Brouwer, Inge D; Burema, Jan; Nguyen, Khan Cong; Kok, Frans J

2006-01-01

The effect of iron fortification is generally assumed to be less than iron supplementation; however, the magnitude of difference in effects is not known. The present study aims to compare the efficacy of these two strategies on anaemia and iron status. After screening on low Hb, 425 anaemic children in six primary schools in Tam Nong district of Phu Tho province were included in a randomized, placebo-controlled trial comparing two groups receiving iron fortified instant noodles or iron supplementation for 6 months and a control group, with children in all groups having been dewormed. Blood samples were collected before and after intervention for haemoglobin, serum ferritin (SF), serum transferrin receptor (TfR), C-reactive protein (CRP), and haemoglobinopathies analysis. Regression analysis was used to assess the effect of iron fortification and iron supplementation on haemoglobin concentration, SF, TfR, body iron, and anaemic status as outcome variables. The improvement of haemoglobin, SF, and body iron level in the group receiving iron fortification was 42% (2.6 g/L versus 6.2 g/L), 20% (23.5 μg/L versus 117.3 μg/L), and 31.3% (1.4 mg/kg versus 4.4 mg/kg) of that in the iron supplementation group. The prevalence of anaemia dropped to 15.1% in the control group, with an additional reduction of anaemia of 8.5% in the iron supplementation group. The additional reduction due to iron fortification was 5.4%, which amounts to well over 50% of the impact of supplementation. In conclusion, the efficacy of iron fortification based on reduction of prevalence of anaemia, and on the change in haemoglobin level, is about half of the maximum impact of supplementation in case of optimal compliance. Thus, in a population of anaemic children with mild iron deficiency, iron fortification should be the preferred strategy to combat anaemia. PMID:17147795

Efficacy of iron fortification compared to iron supplementation among Vietnamese schoolchildren.

PubMed

Thi Le, Huong; Brouwer, Inge D; Burema, Jan; Nguyen, Khan Cong; Kok, Frans J

2006-12-05

The effect of iron fortification is generally assumed to be less than iron supplementation; however, the magnitude of difference in effects is not known. The present study aims to compare the efficacy of these two strategies on anaemia and iron status. After screening on low Hb, 425 anaemic children in six primary schools in Tam Nong district of Phu Tho province were included in a randomized, placebo-controlled trial comparing two groups receiving iron fortified instant noodles or iron supplementation for 6 months and a control group, with children in all groups having been dewormed. Blood samples were collected before and after intervention for haemoglobin, serum ferritin (SF), serum transferrin receptor (TfR), C-reactive protein (CRP), and haemoglobinopathies analysis. Regression analysis was used to assess the effect of iron fortification and iron supplementation on haemoglobin concentration, SF, TfR, body iron, and anaemic status as outcome variables. The improvement of haemoglobin, SF, and body iron level in the group receiving iron fortification was 42% (2.6 g/L versus 6.2 g/L), 20% (23.5 microg/L versus 117.3 microg/L), and 31.3% (1.4 mg/kg versus 4.4 mg/kg) of that in the iron supplementation group. The prevalence of anaemia dropped to 15.1% in the control group, with an additional reduction of anaemia of 8.5% in the iron supplementation group. The additional reduction due to iron fortification was 5.4%, which amounts to well over 50% of the impact of supplementation. In conclusion, the efficacy of iron fortification based on reduction of prevalence of anaemia, and on the change in haemoglobin level, is about half of the maximum impact of supplementation in case of optimal compliance. Thus, in a population of anaemic children with mild iron deficiency, iron fortification should be the preferred strategy to combat anaemia.

High efficiency iron electrode and additives for use in rechargeable iron-based batteries

DOEpatents

Narayan, Sri R.; Prakash, G. K. Surya; Aniszfeld, Robert; Manohar, Aswin; Malkhandi, Souradip; Yang, Bo

2017-02-21

An iron electrode and a method of manufacturing an iron electrode for use in an iron-based rechargeable battery are disclosed. In one embodiment, the iron electrode includes carbonyl iron powder and one of a metal sulfide additive or metal oxide additive selected from the group of metals consisting of bismuth, lead, mercury, indium, gallium, and tin for suppressing hydrogen evolution at the iron electrode during charging of the iron-based rechargeable battery. An iron-air rechargeable battery including an iron electrode comprising carbonyl iron is also disclosed, as is an iron-air battery wherein at least one of the iron electrode and the electrolyte includes an organosulfur additive.

Grain growth kinetics of ringwoodite and majorite garnet mixtures and implications for the rheology of the transition zone

NASA Astrophysics Data System (ADS)

Ezad, I.; Dobson, D. P.; Brodholt, J. P.; Thomson, A.; Hunt, S.

2017-12-01

The grain size of the transition zone is a poorly known but important geophysical parameter. Among others, the grain size may control the rheology, seismic attenuation and radiative thermal conductivity of the mantle. However, the grain size of the transition zone minerals ringwoodite (Mg,Fe)2SiO4 and majorite garnet MgSiO3 under appropriate zone conditions is currently unknown and there are very few experiments with which to constrain it. In order to determine the grain size of the transition zone, the grain growth kinetics must be determined for a range of mantle compositions. We have, therefore, experimentally determined the grain growth kinetics of the lowermost transition zone minerals through multi anvil experiments at University College London (UCL). This is achieved through a comprehensive set of time series experiments at pressures of 21 GPa and temperatures relevant to the transition zone. We have also determined the effect of varying water content, oxygen fugacity, iron content and aluminium content also discussed by Dobson and Mariani., (2014). Our initial grain growth experiments conducted at 1200°C and 1400°C at 18 GPa show extremely slow grain growth kinetics; time series experiments extended to 105.8 seconds are unable to produce grains larger than 100 nm. This suggests that fine-grained material at the base of the transition zone will persist on geological timescales. Such small grains size suggests that diffusion creep might be the dominant deformation mechanism in this region. Reference: Dobson, D.P., Mariani, E., 2014. The kinetics of the reaction of majorite plus ferropericlase to ringwoodite: Implications for mantle upwellings crossing the 660 km discontinuity. Earth Planet. Sci. Lett. 408, 110-118. doi:10.1016/j.epsl.2014.10.009

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.

Crystallographic Orientation Relationships (CORs) between rutile inclusions and garnet hosts: towards using COR frequencies as a petrogenetic indicator

NASA Astrophysics Data System (ADS)

Griffiths, Thomas; Habler, Gerlinde; Schantl, Philip; Abart, Rainer

2017-04-01

Crystallographic orientation relationships (CORs) between crystalline inclusions and their hosts are commonly used to support particular inclusion origins, but often interpretations are based on a small fraction of all inclusions in a system. The electron backscatter diffraction (EBSD) method allows collection of large COR datasets more quickly than other methods while maintaining high spatial resolution. Large datasets allow analysis of the relative frequencies of different CORs, and identification of 'statistical CORs', where certain limited degrees of freedom exist in the orientation relationship between two neighbour crystals (Griffiths et al. 2016). Statistical CORs exist in addition to completely fixed 'specific' CORs (previously the only type of COR considered). We present a comparison of three EBSD single point datasets (all N > 200 inclusions) of rutile inclusions in garnet hosts, covering three rock systems, each with a different geological history: 1) magmatic garnet in pegmatite from the Koralpe complex, Eastern Alps, formed at temperatures > 600°C and low pressures; 2) granulite facies garnet rims on ultra-high-pressure garnets from the Kimi complex, Rhodope Massif; and 3) a Moldanubian granulite from the southeastern Bohemian Massif, equilibrated at peak conditions of 1050°C and 1.6 GPa. The present study is unique because all datasets have been analysed using the same catalogue of potential CORs, therefore relative frequencies and other COR properties can be meaningfully compared. In every dataset > 94% of the inclusions analysed exhibit one of the CORs tested for. Certain CORs are consistently among the most common in all datasets. However, the relative abundances of these common CORs show large variations between datasets (varying from 8 to 42 % relative abundance in one case). Other CORs are consistently uncommon but nonetheless present in every dataset. Lastly, there are some CORs that are common in one of the datasets and rare in the remainder

International Arctic Research Programs

DTIC Science & Technology

1989-07-01

beryllium graphite - (moonstone) cerium marble garnet chrniun ol ivine gronlandite copper phosphorus jasper gold soapstone kornerupine iron sulphur...Green- from the magnetic pole to the auroral zone. landic sea under marginal conditions where Besides these groundbased activities, mea- surements of

49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

Code of Federal Regulations, 2011 CFR

2011-10-01

... for Corrosion Control § 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to a... 49 Transportation 3 2011-10-01 2011-10-01 false Remedial measures: Cast iron and ductile iron...

49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

Code of Federal Regulations, 2010 CFR

2010-10-01

... for Corrosion Control § 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to a... 49 Transportation 3 2010-10-01 2010-10-01 false Remedial measures: Cast iron and ductile iron...

Sensitivity of magnetic properties to chemical pressure in lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li

NASA Astrophysics Data System (ADS)

Mukherjee, P.; Sackville Hamilton, A. C.; Glass, H. F. J.; Dutton, S. E.

2017-10-01

A systematic study of the structural and magnetic properties of three-dimensionally frustrated lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li is presented. Garnets with Ln  =  Gd show magnetic behaviour consistent with isotropic Gd3+ spins; no magnetic ordering is observed for T  ⩾  0.4 K. Magnetic ordering features are seen for garnets with Ln  =  Tb, Dy, Ho in the temperature range 0.4  <  T  <  2.5 K, however the nature of the magnetic ordering varies for the different Ln as well as for different combinations of A and X. The magnetic behaviour can be explained by tuning of the magnetic interactions and changes in the single-ion anisotropy. The change in magnetic entropy is evaluated from isothermal magnetisation measurements to characterise the magnetocaloric effect in these materials. Among the Gd garnets, the maximum change in magnetic entropy per mole (15.45 J K-1 molGd-1 ) is observed for Gd3Sc2Ga3O12 at 2 K, in a field of 9 T. The performance of Dy3Ga5O12 as a magnetocaloric material surpasses the other garnets with Ln  =  Tb, Dy, Ho.

Results of the First American Prospective Study of Intravenous Iron in Oral Iron-Intolerant Iron-Deficient Gravidas.