The volume compression of BaNd2CuO5 (brown phase) and BaLu2CuO5 (green phase) have been measured to 8.67 and 9.23 GPa, respectively, utilizing a diamond anvil high-pressure cell and energy dispersive X-ray powder diffraction. The pressure dependence of the volume of the orthorhombic BaLu2CuO5 and tetragonal BaNd2CuO5 unit cell, as determined by a least-squares fit of the data, are both linear and follow the equations of V=−1.615P+260.62 Å3, and V=−1.9001P+476.92 Å3, respectively. While linear compressions of the unit cell parameters of BaNd2CuO5 exhibit isotropic compressive behavior within our experimental error, BaLu2CuO5 shows somewhat anisotropic compressibility behavior. From the observed data, the bulk modulus of BaNd2CuO5 is determined to be 161±8 GPa and the Young's modulus is estimated to be 193 ±9 GPa. For BaLu2CuO5, the corresponding bulk modulus and the Young's modulus are estimated to be 251±13 GPa and 301±16 GPa, which are significantly greater than those of the brown phase and the high-Tc superconductor Ba2YCu3O6+x. No evidence of a pressure-induced phase transformation was found in either compound in the pressure range studied.

A method for quantitative characterization of a phase's depth distribution is discussed in detail. Both model-independent and model-dependent nonlinear least squares technique methods were developed; in addition, an inverse Laplace transformation method is presented to solve the problem directly in mathematics. The methods can also be used for samples with preferred orientation. Furthermore, the technique is expanded to the technique of computed depth profiling of XRD patterns; then the depth profiles of other structural information that is based on the peak intensity, peak position, and line profile can be determined. A feasibility test was also performed.

Powder X-ray diffraction data are reported for La1−xSrxCo0.8Fe0.2O3 (x=0.2, 0.4) and La0.8Ba0.2Co0.8Fe0.2O3. The powders were prepared by thermal decomposition of metal-containing complex solutions. All compositions have rhombohedral unit cells. In hexagonal setting, the cell parameters are a=5.4451(2) Å, c=13.2553(2) Å for La0.6Sr0.4Co0.8Fe0.2O3; a=5.4556(3) Å, c=13.1999(2) Å for La0.8Sr0.2Co0.8Fe0.2O3 and a=5.4795(1) Å, c=13.2983(5) Å for La0.8Ba0.2Co0.8Fe0.2O3. The space group is probably R3c (167) for all three compositions.

A well-crystallized sample of powdered KCl has been distributed among several laboratories in order to test the reproducibility of the lattice parameter measurement on different X-ray powder diffraction instruments. The precision of the determined unit-cell dimension is in the 10−5 Å range, while the discrepancies among the results from different laboratories using the same numerical analysis are at least one order of magnitude higher. It is shown that if different numerical analyses, including full pattern refinement, are used, values differing in the third decimal digit are obtained for the same data set.

The crystal structure of La1−xSrxCoO3−δ (0≤x≤0.6) has been studied, using powder X-Ray diffraction. The crystal structure shows a transition from rhombohedral distorted perovskite for LaCoO3−δ into cubic perovskite for La0.4Sr0.6CoO3−δ. The cubic unit cell parameter is ac=3.8342(1) Å for La0.4Sr0.6CoO3−δ, the space group probably being Pm3m. Using a hexagonal setting, the cell parameters for La0.5Sr0.5CoO3−δ, are a=5.4300(3) Å, c=13.2516(10) Å; a=5.4375(1) Å, c=13.2313(4) Å for La0.6Sr0.4CoO3−δ; a=5.4437(1) Å, c=13.2085(5) Å for La0.7Sr0.3CoO3−δ; a=5.4497(2) Å, c=13.1781(6) Å for La0.8Sr0.2CoO3−δ and a=5.4445(2) Å, c=13.0936(6) Å for LaCoO3−δ with the space group probably being R3c.

Potassium hydrogen fluoride KHF2 is tetragonal at room temperature: a=5.667(1) Å, c=6.795(1) Å, d=2.38, Z=4, space group I4/mcm (No. 140). It gives a polymorphic transition at 196 °C to a cubic form: a=6.435(1) Å, Z=4, space group Fm3m, melts at 239 °C, and then dissociates into gaseous HF and solid KF.

Gamma-phase lithium aluminate (LiAlO2) is a ceramic powder used in molten carbonate fuel cells (MCFCs) and in other nuclear and ceramic applications. Upon exposure to water vapor and carbon dioxide at 25 °C, we have observed that gamma-LiAlO2 converts to lithium aluminum carbonate hydroxide hydrate, Li2Al4(CO3)(OH)12·3H2O(LACHH) and Li2CO3. The conversion was observed by X-ray diffraction (XRD) and carbonate analysis. An equation for the conversion is given, and the morphology is determined by scanning electron microscopy. A high-temperature XRD study and thermogravimetric/differential thermal analysis (TGA/DTA) showed that LACHH decomposes at 250 °C. The decomposition products of LACHH and Li2CO3 react to form first alpha-LiAlO2 and then gamma-LiAlO2 at temperatures of 650 and 1000 °C, respectively.

The crystal structure of Cr2[Ni(CN)4]3·10H2O has been determined on X-ray diffraction powder data by means of the Rietveld method. The starting model was based on the isomorphic, disordered structure of Mn3[Co(CN)6]2·12H2O. At room temperature the crystal is cubic, F4¯3m, a=10.097(6) Å, V=1029.4(5) Å3. The structure is disordered and contains 1.33 formula weights per unit cell. The Ni and Cr ions are coordinated by N and C atoms, respectively, forming octahedra linked by CN groups. The water molecules replace partly the chromium, carbon, and nitrogen positions in the crystal. The final R values are: Rwp=0.032 (Rexp=0.023), RB=0.088, and DW-Stat.=1.31 (DWexp=1.8).

A significant feature for the atomic structure of the intermetallic compounds Co2Al5 (hP28), monoclinic m-Co4Al13(mC(102-7.2) [notation according to Parthé etal. (1993)] and orthorhombic o-Co4Al13 (oP102) is the occurring of the filled pentagonal channels. Least-square refined lattice parameters as well as powder diffraction data are reported for these homeotypic phases.

A rapid whole-pattern profile-matching procedure for the quantitative assessment of multiphase powder diffraction patterns is described. Using a position-sensitive detector, with fixed beam-sample-detector geometry, we report on the efficacy and speed of this method in the quantitative assessment of four different multiphase samples.

The formation of the solid solutions in the (La1−xGdx)OCl series was studied by X-ray powder diffraction (XPD) at room temperature in the 2θ region between 6.5 and 120°. The Rietveld profile refinement analyses of the XPD patterns were carried out with the background, unit cell, atomic position, isotropic temperature, and Gaussian profile form parameters refined freely. All (La1−xGdx)OCl samples possessed the tetragonal PbFCl-type structure with P4/nmm as the space group (Z=2). The unit cell parameters a and c evolve smoothly through the series and no clustering of the Gd3+ ions was observed according to Vegard's law. The solid solubility exists throughout the whole series. The valence bond model was used to estimate the relative stabilities of the different (La1−xGdx)OCl solid solutions. The global instability index (GII) which equals to the deviation between the formal valence and the sum of the calculated valence bonds of each atom in the asymmetric unit was used as a tool in the assessment. In the (La1−xGdx)OCl series, GII increases both from the end and the beginning of the series toward the middle indicating diminishing stability. No breakdown of the La–Gd solid solution could be verified experimentally although the GII value for the (La0.4Gd0.6)OCl composition exceeds the limit of 0.2 which should mean the collapse of the structure. However, the diffraction reflections were found somewhat broader in the middle of the series indicating possible local distortion or disorder.

Indexed powder diffraction patterns and related crystallographic data are reported for ErNiSb, which is not represented in the X-ray Powder Diffraction File. The compound ErNiSb is cubic [space group F43m, Z=4, a=6.2693(1) Å]. The R=0.067 indicates that experimental intensities agree well with the calculated patterns.

A model for the crystalline structure of Ba2YCu0.25W0.75O6 solid solution is given. The model proposed a perovskite ordered structure, with a cubic unit cell made from eight perovskite-like units and having a symmetry described by the space group Fm3m. The crystalline structure was refined by the Rietveld technique, giving RF=0.048 for 82 reflections. The solid solution was characterized by the following parameters: Z=4, Mr=613.2, a=8.43630(8) Å, V=600.42(1) Å3, Dx=6.78 g cm−3, μ=209.04 mm−1, and F(000)=1047. The model assumed that copper and tungsten atoms, which were ordered with Y atoms, had the same local environment. Therefore, it was only a first approximation to the crystalline structure.