British Library Electronic Table of Contents (United Kingdom)

Platinum Group Element (PGE) concentrations in garnet pyroxenite xenoliths from Oahu, Hawaii, are significantly lower than those in mantle peridotites and show fractionated patterns (e.g. PdN/OsN=2-10, PdN/IrN=4-24; N=chondrite normalized) and very high ReN/OsN ratios (9-248). Mass balance calculations show that the bulk rock pyroxenite PGE inventory is controlled by the presence of sulfide phases. The 187Os/188Os ratios of these pyroxenites vary from subchondritic to suprachondritic (0.123-0.164); and the 187Os/188Os ratios show good correlations with bulk rock and clinopyroxene major and trace element compositions, and bulk rock PGE and sulfur abundances. These observations suggest that the Os isotope compositions in these pyroxenites largely reflect primary processes in the oceanic mant...

Energy Technology Data Exchange (ETDEWEB)

Geological, geophysical, and engineering-geological research conducted at the 'Yeniseisky' site obtained data on climatic, geomorphologic, geological conditions, structure and properties of composing rock, and conditions of underground water recharge and discharge. These results provide sufficient information to make an estimate of the suitability of locating a radioactive waste (R W) underground isolation facility at the Nizhnekansky granitoid massif

International Nuclear Information System (INIS)

Magnetic materials such as yttrium iron garnet (YIG) are of great importance for its magneto-optic properties and for their potential applications in the domain of optical telecommunications. The deposition of thin films of YIG, on quartz or GGG (gadolinium gallium garnet) substrate, was performed using radio frequency non reactive magnetron sputtering, followed by high temperature annealing which is needed to enhance the crystallinity of the layers. Rutherford backscattering spectrometry RBS was used to determine the thickness and stoichiometry of the performed layers in order to investigate correlations between growth conditions and the quality of the final material. RBS measurements showed the influence of the deposition time and the temperature substrate on the film growth and its stoichiometry. (author)

Energy Technology Data Exchange (ETDEWEB)

The paleogeography postulated from the distribution of Permian and Triassic sedimentary rocks in the Middle East is shown and related to the paleostructure of the region. The Middle East region as defined here includes the Arabian Peninsula, Iran, Iraq, SE Turkey, Syria, Lebanon, Jordan, West Jordan, and the Sinai Peninsula. Within the limits of the area included in this study, a relatively stable pre-Late Triassic tectonic regime can be recognized and distinguished from a succession of diastrophic events of the Late Triassic epoch, which caused marked changes in the types and distribution of facies. Excluding NE Iran, the Middle East was stable from Late Cambrian to Middle Triassic times, as it formed a part of the Arabian Massif and much of the Middle East Platform, which is a broad shelf bordering the positive Afro-Arabian Massif to the NE and east. The sediments of this platform have undergone no strong deformation and have been subjected ...

International Nuclear Information System (INIS)

The umbrella magnetic structure of the terbium iron garnet (TbIG) has been studied using neutron diffraction experiments peformed in the 4.2 to 650 K temperature range which covers both the Neel temperature (Tsub(N) = 550 +- 10 K) and the compensation temperature (Tsub(comp) = 244 +- 2 K). When T > Tsub(N), the observed peak intensities originate from nuclear contribution only. When Tsub(comp) < T < Tsub(N), the results have been interpreted in the Neel theory of ferrimagnetism. Below Tsub(comp), three salient features have been observed: there appears superstructure lines forbiden by the cubic space group Ia3d, whereas the other superstructure peaks are found absent contrary to other heavy rare earth garnets; the strongest reflexion (110) vanishes near Tsub(comp). The magnetic modes associated to the rhombohedral symmetry space group R(-3)c have been calculated; the two inequivalent magnetic sites C_1 and C'_1 of the Tb"3"+ ion have ...

Energy Technology Data Exchange (ETDEWEB)

Thermophotovoltaic (TPV) converters were developed and tested at the heat source operating temperature of 1,700 K. Rare-earth-doped yttrium aluminum garnet (YAG) and lutetium yttrium aluminum garnet (Lu, YAG) selective emitters, as well as a blackbody emitter, were coupled to InGaAs/InP photovoltaic (PV) cells and bandpass/infrared (IR) reflector filters. YAG-based selective emitters were adopted with Ho, Tm, and Er. PV cells had bandgaps of 0.51, 0.57, and 0.69 eV. Converter energy conversion efficiencies approaching 30%, as well as electrical output power densities near 2 W/cm{sup 2} were demonstrated. The overall performance of the filtered blackbody-based converter was found to be superior to the selective emitter YAG-based converters. The details of the measurements performed on the above converters and their individual components are presented.

Energy Technology Data Exchange (ETDEWEB)

In this paper the authors 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.

International Nuclear Information System (INIS)

A sample of garnet-biotite plagiogneiss, GBPg-1 is currently being developed as a certified reference material at the Vinogradov Institute of Geochemistry. It was used as the sample that was distributed round 7 of International Proficiency Testing Program (GeoPT7) and was analyzed by 76 geoanalytical laboratories around the world. Twenty Russian laboratories involved in the interlaboratory experiment also analyzed GBPg-1. The resultant analytical data obtained from these two experiments has allowed GBPg-1 to be certified as a state standard sample for 50 elements. It also enabled a comparison of the quality of data developed by the Russian and international geoanalytical laboratories, to optimize the outcome of this interlaboratory experiment.

Energy Technology Data Exchange (ETDEWEB)

X-ray magnetic circular dichroism (XMCD) was used to probe the existence of induced magnetic moments in yttrium iron garnet (YIG) films in which yttrium is partly substituted with lanthanum, lutetium or bismuth. Spin polarization of the 4d states of yttrium and of the 5d states of lanthanum or lutetium was clearly demonstrated. Angular momentum resolved d-DOS of yttrium and lanthanun was shown to be split by the crystal field, the two resolved substructures having opposite magnetic polarization. The existence of a weak orbital moment involving the 6p states of bismuth was definitely established with the detection of a small XMCD signal at the Bi M{sub 1}-edge. Difference spectra also enhanced the visibility of subtle changes in the Fe K-edge XMCD spectra of YIG and {l_brace}Y, Bi{r_brace}IG films. Weak natural X-ray linear dichroism signatures were systematically observed with all iron garnet films and with a bulk YIG single crystal cut ...

British Library Electronic Table of Contents (United Kingdom)

Abstract: We have performed petrographic and spectroscopic studies of brown diamonds from an eclogite xenolith from the Udachnaya pipe (Yakutia, Russia). Brown diamonds are randomly intermixed with colorless ones in the rock and often located at the grain boundaries of clinopyroxene and garnet. Brown diamonds can be characterized by a set of defects (H4, N2D and a line at 490.7nm) which are absent in colorless diamonds. This set of defects is typical for plastically deformed diamonds and indicates that diamonds were likely annealed for a relatively short period after deformation had occurred. Excitation of brown colored zones with a 632.8nm He-Ne laser produced the typical diamond band plus two additional bands at 1730cm^-^1 and 3350cm^-^1. These spectral features are not genuine Raman ban...

CERN Document Server

We point out that electromagnetic one-way edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D gyroelectric photonic crystals possessing Dirac point-derived bandgaps, can appear in more general settings. In particular, we show that the TM modes in a gyromagnetic photonic crystal can be formally mapped to electronic wavefunctions in a periodic electromagnetic field, so that the only requirement for the existence of one-way edge modes is that the Chern number for all bands below a gap is non-zero. In a square-lattice gyromagnetic Yttrium-Iron-Garnet photonic crystal operating at microwave frequencies, which lacks Dirac points, time-reversal breaking is strong enough that the effect should be easily observable. For realistic material parameters, the edge modes occupy a 10% band gap. Numerical simulations of a one-way waveguide incorporating this crystal show 100% transmission across strong defects, such as perfect ...

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows: Stable aqueous sulfur species are mainly sulfide (H{sub 2}S) and sulfate (SO{sub 4}{sup 2-}) ions. However, several sulfoxy-anions may be detected as metastable anions in natural environment, as typically thiosulfate (S{sub 2}O{sub 3}{sup 2-}) and sulfite (SO{sub 3}{sup 2-}) ions [1]. In natural systems, uranium speciation and migration are mainly governed by carbonate complexes in non reducing conditions. Whereas sulfate is already known as a complexing agent of actinides, data relating to U-SO{sub 3}{sup 2-} and U-S{sub 2}O{sub 3}{sup 2-} complexes have only been proposed for U(VI) [2], but are usually not included in thermodynamic databases [3]. Therefore, it appears to be relevant to determine complexation constants of actinides with sulfur ligands, for RN migration studies, concerning nuclear waste disposal as well as migration behaviour in the geosphere. In the present study, values have been estimated for the first complexing constants of U{sup ...

International Nuclear Information System (INIS)

Different SiAlON composites based on #alpha#'-SiAlON are investigated, with respect to the phase relationships, densification behavior, and mechanical properties. The compositions are located on a phase-diagram line parallel to the Si_3N_4-Y_2O_3#centre dot#9AlN compound in the Si_3N_4-SiO_2-AlN-Al_2O_3-Y_2O_3-YN system. Analysis of the reaction sequences shows that the formation of the composites is associated with the transient appearance of Y_4Al_2O_9 (YAM), yttrium-aluminum-garnet (YAG), melilite, and a nitrogen-rich liquid phase. The small shift of compositions on the Si_3N_4-Y_2O_3#centre dot#9AlN compound phase-diagram line toward the Al_2O_3-rich side offers the advantage of a higher sinterability and the removal of the melilite phase from a wide range of compositions containing #alpha#'-SiAlON and polytypes. The #alpha#'/#beta#'-SiAlON composites show better mechanical properties in comparison to pure #alpha#'-SiAlON and composites of #alpha#'-SiAlON and ...