X-ray powder diffraction data for In3.85Zr2.80Sn0.35O12

X-ray powder diffraction data for In3.85Zr2.80Sn0.35O12 are reported. The powders were prepared using a wet-chemical precipitation method. The XRD data could be fitted with a rhombohedral unit cell in space group R3 (No. 148). The Rietveld refined unit cell parameters are a=0.951 49(2) nm and c=0.889 51(2)nm in a hexagonal setting with Z=3 and Dx=6.69(1)g/cm3.

Studies on Crystal Structure and Magnetic Scaling Behavior of Perovskite-Like (La1−xPbx)MnO3 System with x = 0 - 0.5

ABSTRACTThe magnetic critical behaviors in the perovskite-like (La1−xPbx)MnO3 series with x = 0.0 ∼ 0.5 are studied by means of dc magnetic measurements. All the samples crystallize in the rhombohedral unit cell with a C R 3 space group (a 0.54 nm and c 1.33 nm). The detailed crystallographic parameters of all the samples are obtained by the refinements of the powder x-ray diffraction data using the Rietveld method. The substitution effect of Pb2+ ions on La3+ sites induces a mixed-valence state of Mn3+/Mn4+ and enhances magnetic transition temperature in the (La1−xPbx)MnO3 system. The transition temperature TC increases with the Pb content from 225 K as x = 0 to 355 K as x = 0.5. The canonical spin-glass behaviors in low fields and the scaling behaviors of magnetic physical quantities are clearly observed in all our samples. The values of the related critical exponents and the scaling functions of magnetic data are close to those of the conventional spin glass systems.

Oxygen Ion Conductivities of Rhombohedral Phases in the Ba-Sr-Bi Oxide System

ABSTRACTThe rhombohedral phase of the Ba-Bi-O system is known to be a good oxygen ion conductor. Previous studies on conductivity of that system have shown that there is a sudden increase in conductivity at the β2-β1 polymorphic transition. Therefore, the high temperature β2 phase is a very good anionic conductor with values up to 10−1-100 S/cm. In the Ba-Sr-Bi-O system, the rhombohedral phase that contains Ba and Sr coexists with BaBiO3. Several specimens of the rhombohedral phase with different [Ba]-[Sr] ratios were synthesized. Electron microprobe analysis was used to determine the chemical composition of each specimen and to ensure that it consisted of a monophasic assemblage. Results of X-ray powder diffraction experiments confirmed that each sample has a rhombohedral unit cell. Oxygen ion conductivities of these materials were measured using the 2-probe AC Impedance technique over the 320-730°C temperature range. In each case, a sudden increase in conductivity indicates temperature range of the polymorphic transition. Exchange of the smaller cation Sr for Ba makes the transition temperature increase almost in a linear manner. Conductivities of all β2 polymorphs at a given temperature are very similar to conductivities of Ba-Bi-O and Sr-Bi-O β2 polymorphs. Conductivities of all β1 polymorphs are also similar. Apparently, the nature of the alkaline earth present has only slight influence on conductivities of these phases.

Ternäre Chalkogenide M3M2′X2 mit Shandit-Struktur / Ternary Chalcogenides M3M2′X2 with Shandite-Type Structure

Metal-rich ternary chalcogenides M3M2′X2 (M = Ni, Co, Pd, Rh; M′ = In, Tl, Pb, Sn; X = S, Se) with Shandite-type structure were synthesized from mixtures of the elements and/or binary components. A single-crystal investigation on Co3ln2S2 verifies the rhombohedral unit cell of Shandite-type compounds, originally postulated by Peacock and McAndrew (Crystal data for Co3ln2S2: Rhombohedral, space group R3̄m; a = 549,31 (6) pm, a = 57.89°, Z= 1; 3 Co in 3d, 1 In(l) in 1 a, 1 In(2) in 1 b, 2 S in 2c with x = 0.2790).

X-Ray Determination of the Structure of Ice IV

Ice IV, a wholly metastable ice phase, has a structure based on a framework of tetrahedrally hydrogen-bonded water molecules in a rhombohedral unit cell. The structure involves two non-equivalent types of water molecules and four non-equivalent types of hydrogen bonds. A novel structural feature is a hydrogen bond that passes through the center of a 6-ring of water molecules and links non-adjacent structural layers. The bond network is proton-disordered, even after quenching.

X-Ray Determination of the Structure of Ice IV

Ice IV, a wholly metastable ice phase, has a structure based on a framework of tetrahedrally hydrogen-bonded water molecules in a rhombohedral unit cell. The structure involves two non-equivalent types of water molecules and four non-equivalent types of hydrogen bonds. A novel structural feature is a hydrogen bond that passes through the center of a 6-ring of water molecules and links non-adjacent structural layers. The bond network is proton-disordered, even after quenching.

Goyazite and florencite from two African carbonatites

SummaryFlorencite with ω 1·653, εd 1·661, G 3·457, a 6·971 ± 0·004 Å, c 16·42±0·13 Å, and rhombohedral unit-cell contents Sr0·42Ce0·52Ca0·14Al2·83(PO4)1·77(SO4)0·10 F0·41(OH)5·24(H2O)0·85 occurs in the Kangankunde carbonatite in Nyasaland, and goyazite with G 3·386, a 6·982±0·001 Å, c 16·54±0·02 Å, and rhombohedral unit-cell contents Ba0·05Sr0·50Ce0·41Ca0·08A2·78(PO4)1·62(SO4)0·19F0·30(OH)5·30(H2O)1·18 on the Wigu carbonatite in Tanganyika. Hydrothermal decomposition experiments in the Wigu material indicate stability below 535 ± 10 °C at pH2O 200 bars and 565 ± 10°C at pH2O 2500 bars ; both minerals exhibit endothermic peaks at 630°C in differential thermal analyses. The crystal chemistry of the goyazite series is discussed in the light of the two new analyses and of newly determined unit-cell dimensions for four other members of the goyazite series. Goyazite, florencite, and gorceixite appear to have crystallized during late-stage replacement processes or under supergene conditions in carbonatites.

Connellite, buttgenbachite, and tallingite

There are many basic copper chlorides and sulphates which occur as minerals but have received little recent crystallographic study. Yet copper is a widely distributed element and many of these minerals are the products of corrosion and weathering of bopper and copper ores.In 1948 we were able to confirm the earlier goniometric work of G. F. Herbert Smith (1906) that paratacamite and atacamite are not identical species (Max H. Hey, 1950) and showed that the two minerals give different X-ray powder patterns. This result was further extended by Clifford Frondel (1950) to a single 'crystal and thermal study of paratacamite, in the course of which he measured the rhombohedral unit-cell dimensions and showed that this mineral can be artificially produced by various methods as well as by the action of salt-water on copper.