Crystal chemistry, X-ray diffraction reference patterns, and bandgap studies for (Ba x Sr1-x)2CoWO6 (x = 0.1, 0.2, 0.3, 0.5, 0.7, and 0.9) - CORRIGENDUM

AbstractOlivine basalts from southern Egypt were studied by 57Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe2+), and a weak ferric (Fe3+) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe3+/ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.

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Crystal chemistry of lamprophyllite-group minerals from the Murun alkaline complex (Russia) and pegmatites of Rocky Boy and Gordon Butte (USA): single crystal X-ray diffraction and Raman spectroscopy study

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520621000354 ◽

2021 ◽

Vol 77 (2) ◽

Author(s):

Sergey M. Aksenov ◽

Anastasia D. Ryanskaya ◽

Yuliya V. Shchapova ◽

Nikita V. Chukanov ◽

Nikolay V. Vladykin ◽

...

Keyword(s):

Solid Solution ◽

Single Crystal ◽

Raman Spectra ◽

Crystal Chemistry ◽

Solid Solution Series ◽

X Ray Diffraction ◽

Alkaline Complex ◽

Oh Groups ◽

X Ray ◽

Solution Series

Specific features of the crystal chemistry of lamprophyllite-group minerals (LGMs) are discussed using the available literature data and the results of the single-crystal X-ray diffraction and a Raman spectroscopic studies of several samples taken from the Murun alkaline complex (Russia), and Rocky Boy and Gordon Butte pegmatites (USA) presented here. The studied samples are unique in their chemical features and the distribution of cations over structural sites. In particular, the sample from the Gordon Butte pegmatite is a member of the barytolamprophyllite–emmerichite solid solution series, whereas the samples from the Murun alkaline complex and from the Rocky Boy pegmatite are intermediate members of the solid solution series formed by lamprophyllite and a hypothetical Sr analogue of emmerichite. The predominance of O2− over OH− and F− at the X site is a specific feature of sample Cha-192 from the Murun alkaline complex. New data on the Raman spectra of LGMs obtained in this work show that the wavenumbers of the O—H stretching vibrations depend on the occupancies of the M2 and M3 sites coordinating with (OH)− groups. Cations other than Na+ and Ti4+ (mainly, Mg and Fe3+) can play a significant role in the coordination of the X site occupied by (OH)−. Data on polarized Raman spectra of an oriented sample indicate that the OH groups having different local coordinations have similar orientations with respect to the crystal. The calculated measures of similarity (Δ) for lamprophyllite and ericssonite are identical (0.157 and 0.077 for the 2M- and 2O-polytypes, respectively), which indicates that these minerals are crystal-chemically isotypic and probably should be considered within the same mineral group by analogy to the other mineralogical groups which combine isotypic minerals.

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Transition Metal-Gallium Ordering In HfCoGa2 And HfNiGa2

Zeitschrift für Naturforschung B ◽

10.1515/znb-2003-0103 ◽

2003 ◽

Vol 58 (1) ◽

pp. 16-21 ◽

Cited By ~ 5

Author(s):

Martin Schlüter ◽

Birgit Heying ◽

Rainer Pöttgen

Keyword(s):

Transition Metal ◽

Single Crystals ◽

Crystal Chemistry ◽

Glassy Carbon ◽

Previous Investigation ◽

Subsequent Annealing ◽

X Ray Diffraction ◽

X Ray ◽

Arc Melting

Abstract The gallides HfCoGa2 and HfNiGa2 were synthesized by arc-melting of the elements and subsequent annealing in glassy carbon crucibles. Their structures have been reinvestigated by X-ray diffraction on powders and single crystals: I4mm, a = 1222.4(1), c = 812.0(1) pm, wR2 = 0.0766, 1464 F2 values, 64 variables, BASF = 0.41(2) for HfCoGa2 and a = 1224.0(2), c = 809.3(2) pm, wR2 = 0.0609, 1499 F2 values, 63 variables for HfNiGa2. In contrast to a previous investigation (Dopov. Akad. Nauk Ukr. RSR, Ser. A, 51 (1988)) we observe a fully ordered arrangement of the transition metal and gallium atoms. The crystal chemistry of these gallides is briefly discussed.

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Crystal Chemistry and Microstructures of Uranyl Phosphates

MRS Proceedings ◽

10.1557/proc-506-839 ◽

1997 ◽

Vol 506 ◽

Cited By ~ 4

Author(s):

Y. Suzuki ◽

T. Murakami ◽

T. Kogure ◽

H. Isobe ◽

T. Sato

Keyword(s):

Electron Microscopy ◽

Crystal Chemistry ◽

Analytical Electron Microscopy ◽

Water Molecules ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Uranyl Phosphate ◽

Uranyl Phosphates ◽

Form Solid Solution

ABSTRACTThe crystal chemistry and microstructures of saleeite (Mg(UO2PO4)2•10H2O) and metatorbernite (Cu(UO2PO4)2•8H2O), from Koongarra, Australia and Shinkolobwe, Congo, were examined by X-ray diffraction analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis, transmission electron microscopy (TEM) and analytical electron microscopy. The uranyl phosphates consist of uranyl phosphate layers with cations and waters in the interlayers. The IR spectra of saleeite and metatorbernite show the presence of hydroxyls in the interlayers in addition to water molecules. The d002 spacings of the hydrated phases of saleeite and metatorbernite up to 300°C reveal that the uranyl phosphate layers themselves are quite stable in the temperature range although the interlayer water molecules are lost easily. The presence of a mixed phase of saleeite and metatorbernite is confirmed in the micrometer and nanometer scales. However, SEM and TEM examination suggest saleeite and metatorbemite generally grow separately, and rarely form solid solution or interstratification. The results imply that U is retained in uranyl phosphate minerals even when the temperature at around repositories increases, and that saleeite and metatorbernite precipitate independently from solution according to their solubilities even when Mg2+ and Cu2+ coexist in solution.

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Crystal chemistry of the compound Sr2Bi2CuO6

Journal of Materials Research ◽

10.1557/jmr.1990.0046 ◽

1990 ◽

Vol 5 (1) ◽

pp. 46-52 ◽

Cited By ~ 81

Author(s):

R. S. Roth ◽

C. J. Rawn ◽

L. A. Bendersky

Keyword(s):

Electron Diffraction ◽

Single Crystal ◽

Diffraction Pattern ◽

Crystal Chemistry ◽

Superconducting Phase ◽

X Ray Diffraction ◽

Monoclinic Symmetry ◽

X Ray ◽

Symmetry Space ◽

Symmetry Space Group

The compound Sr2Bi2CuO6 should nominally be the phase with n = 1 of the high Tc superconducting series Sr2Bi2CanO4+2n. However, the superconducting phase with n = 1 (with no CaO) occurs only with a gross deficiency in SrO content. Instead, at the composition Sr2Bi2CuO6, a different phase is formed with an x-ray diffraction pattern considerably different from that expected for the n −1 member of the series. This phase has been found, by a combination of electron diffraction and single crystal and powder x-ray diffraction, to have a commensurate lattice with monoclinic symmetry, space group C2/m or Cm, a = 24.473 (2), b = 5.4223 (5), c = 21.959 (2)A, and β = 105.40 (1)°. The actual composition of this phase may be deficient in CuO by as much as 1.0 mole %.

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The Stannides EuPdSn and EuPtSn

Zeitschrift für Naturforschung B ◽

10.1515/znb-1996-0608 ◽

1996 ◽

Vol 51 (6) ◽

pp. 806-810 ◽

Cited By ~ 15

Author(s):

Rainer Pöttgen

Keyword(s):

Single Crystal ◽

Single Crystals ◽

Crystal Chemistry ◽

Three Dimensional ◽

Type Structure ◽

X Ray Diffraction ◽

Space Group ◽

X Ray

Abstract EuPdSn and EuPtSn were prepared from the elements in tantalum tubes at 1070 K and investigated by X-ray diffraction on both powder as well as single crystals. They crystallize with the TiNiSi type structure of space group Pnma and with Z = 4 formula units per cell. Both structures were refined from single-crystal diffractometer data: a = 751.24(9), b = 469.15(6), c = 804.31(9) pm, V = 0.2835(1) nm3 for EuPdSn, and a = 753.38(7), b = 467.72(4), c = 793.08(7) pm, V = 0.2795(1) nnr for EuPtSn. The structures consist of three-dimensional [PdSn] and [PtSn] polyanionic networks in which the europium atoms are embedded. The crystal chemistry of these stannides is briefly discussed

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Therman Expansion and Crystal Chemistry of (Sr1−x , K2x )Zr4(PO4)6 Ceramic

Journal of Applied Crystallography ◽

10.1107/s0021889894013968 ◽

1995 ◽

Vol 28 (5) ◽

pp. 508-512 ◽

Cited By ~ 3

Author(s):

D.-M. Liu ◽

L.-J. Lin ◽

C.-J. Chen

Keyword(s):

Crystal Structure ◽

Grain Size ◽

Thermal Expansion ◽

High Temperature ◽

Crystal Chemistry ◽

X Ray Diffraction ◽

Lattice Thermal Expansion ◽

X Ray ◽

Thermal Expansion Anisotropy ◽

Sufficient Degree

Thermal expansion of (Sr1−x , K2x )Zr4(PO4)6 (SrKZP) (with x = 0–1) ceramic was investigated using both a dilatometer and a high-temperature X-ray diffractometer. The coefficients of thermal expansion (CTEs) of the SrKZP ceramic measured by the dilatometer demonstrate a similar trend as those from high-temperature X-ray diffraction. Both measurements show an ultra-low CTE at x = 0.5; nevertheless, this composition shows significant lattice thermal-expansion anisotropy (TEA), while the minimum TEA appears with composition x = 0.2. Although it possessed a sufficient degree of TEA, the x = 0.5 composition showed no visible microcracks or negligible microcracks over a grain size as large as 15 μm. A transition of space group from R{\bar 3} to R{\bar 3}c with composition between x = 0.3 and x = 0.5 has been observed. The crystal structure of the SrKZP ceramic with possible occupations of strontium and/or potassium within the lattice in relation to their influence on the CTEs is proposed.

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Crystal Chemistry of Carnotite in Abandoned Mine Wastes

Minerals ◽

10.3390/min10100883 ◽

2020 ◽

Vol 10 (10) ◽

pp. 883 ◽

Cited By ~ 1

Author(s):

Sumant Avasarala ◽

Adrian J. Brearley ◽

Michael Spilde ◽

Eric Peterson ◽

Ying-Bing Jiang ◽

...

Keyword(s):

Electron Microscopy ◽

Crystal Chemistry ◽

Mine Waste ◽

Atomic Ratio ◽

Synthetic Analog ◽

Mine Wastes ◽

X Ray Diffraction ◽

X Ray ◽

Degree Of Hydration ◽

Diffraction Patterns

The crystal chemistry of carnotite (prototype formula: K2(UO2)2(VO4)2·3H2O) occurring in mine wastes collected from Northeastern Arizona was investigated by integrating spectroscopy, electron microscopy, and x-ray diffraction analyses. Raman spectroscopy confirms that the uranyl vanadate phase present in the mine waste is carnotite, rather than the rarer polymorph vandermeerscheite. X-ray diffraction patterns of the carnotite occurring in these mine wastes are in agreement with those reported in the literature for a synthetic analog. Carbon detected in this carnotite was identified as organic carbon inclusions using transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) analyses. After excluding C and correcting for K-drift from the electron microprobe analyses, the composition of the carnotite was determined as 8.64% K2O, 0.26% CaO, 61.43% UO3, 20.26% V2O5, 0.38% Fe2O3, and 8.23% H2O. The empirical formula, (K1.66Ca0.043Al(OH)2+0.145 Fe(OH)2+0.044)((U0.97)O2)2((V1.005)O4)2·4H2O of the studied carnotite, with an atomic ratio 1.9:2:2 for K:U:V, is similar to the that of carnotite (K2(UO2)2(VO4)2·3H2O) reported in the literature. Lattice spacing data determined using selected area electron diffraction (SAED)-TEM suggests: (1) complete amorphization of the carnotite within 120 s of exposure to the electron beam and (2) good agreement of the measured d-spacings for carnotite in the literature. Small differences between the measured and literature d-spacing values are likely due to the varying degree of hydration between natural and synthetic materials. Such information about the crystal chemistry of carnotite in mine wastes is important for an improved understanding of the occurrence and reactivity of U, V, and other elements in the environment.

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Crystal Chemistry and Thermal Behavior of Fe-Carpholite from the Pollino Massif, Southern Italy

American Mineralogist ◽

10.2138/am-2020-7385 ◽

2021 ◽

Vol 106 (1) ◽

pp. 123-134

Author(s):

Ernesto Mesto ◽

Salvatore Laurita ◽

Maria Lacalamita ◽

Rosa Sinisi ◽

Giovanna Rizzo ◽

...

Keyword(s):

High Temperature ◽

Thermal Behavior ◽

Single Crystal ◽

Crystal Chemistry ◽

Powder Diffraction ◽

Molar Fraction ◽

X Ray Diffraction ◽

Simultaneous Formation ◽

X Ray ◽

Temperature Range

Abstract The crystal chemistry and thermal behavior of Fe-carpholite from the Pollino Massif have been investigated by a multi-method approach. A combination of optical microscopy, scanning electron microscopy, mRaman spectroscopy, thermal analysis, room-temperature single-crystal X-ray diffraction, and high-temperature X-ray powder diffraction was employed. Field and micromorphological observations showed that the studied carpholite occurs in veins embedded in fine-grained matapelites and coexist with quartz, calcite, chlorite, and phengite. In particular, the tiny carpholite crystals are closely associated with quartz, suggesting simultaneous formation. Structure refinements from single-crystal X-ray diffraction confirm that carpholite crystallizes in the Ccce space group. Anisotropic refinements converged at 2.3 ≤ R (%) ≤ 2.6 and yielded unit-cell parameters a ~13.77 Å, b ~20.16 Å, c ~5.11 Å, and V ~1419 Å3. An XFe [i.e., the molar fraction Fe2+/(Mg+Fe2++Mn)] of ~0.6 was derived from the refined occupancy at the M1 site and is correlated to structural expansion mainly along the b and a axes and to geometrical distortions of the M1, M2, and M3 octahedra. mRaman spectrum of unoriented Fe-carpholite crystals exhibits several bands in the 200–1200 cm–1 region, a strong peak at 3630 cm–1 and a weak peak at 3593 cm–1, the latter two of which account for the presence of two independent OH groups, as also revealed by the X-ray structure refinement. The TG curve indicates a total mass loss of 15.6% in the temperature range 30–1000 °C, and the DTA curve shows a broad endothermic band at ~400 °C, extending up to ~650 °C, and weak exothermic peaks at ~700 and 750 °C. The latter may be ascribed to the breakdown of the Fe-carpholite structure and crystallization of new phases. The in situ high-temperature X-ray powder diffraction from 30 to 1105 °C revealed no significant changes in XRD patterns from 30 to 355 °C but reflection splittings from 380 °C due to a Fe-oxidation/deprotonation process. The carpholite and deprotonated carpholite phases coexist in the temperature range 380–580 °C, whereas only the deprotonated phase is observed up to 630 °C. Above this temperature, the carpholite structure collapses and the characteristic peaks of spinel and quartz phases are observed. At 1105 °C, spinel, mullite, garnet, cristobalite, and tridymite can be clearly identified. Our results provide insight into the thermal stability of Fe-carpholites and may help understand the thermal evolution of HP/LT metasediments.

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