Lobenzarit acid, C14H10ClNO4, and lobenzarit disodium (CCA), C14H8ClNNa2O4, have been investigated by means of X-ray powder diffraction. The unit cell dimensions were determined from diffractometer methods, using strictly monochromatized CuKα1 radiation, and evaluated by indexing programs. The triclinic cell found for lobenzarit acid was a=16.580(1) Å, b=16.389(1) Å, c=4.9023(3) Å, α=71.674(6)°, β=92.609(6)°, γ=97.127(6)°, Z=4, Dx=1.544 Mg/m3. The triclinic cell found for CCA was a=18.041(5) Å, b=11.461(4) Å, c=5.936(2) Å, α=66.80(3)°, β=103.61(3)°, γ=113.13(3)°, Z=4, Dx=2.159 Mg/m3.

Rietveld analysis has been successfully used to characterize plasma-sprayed PSZ coatings in a study of the structural stability of 8 wt. % Y2O3–ZrO2 powders and 23 wt. % CeO2/3 wt. % Y2O3–ZrO2, sprayed onto steel substrates. The ceramics were examined in powder form prior to spraying, as-sprayed and after a series of high-temperature soaks at temperatures relevant to those found in heat engines. The study showed that the Y2O3–ZrO2 powders consist of mixtures of the cubic (as the minor phase) and tetragonal (major phase) zirconia and the cubic zirconia polymorph, whereas the as-sprayed materials contain only the tetragonal (major phase) and monoclinic polymorphs indicating that the cubic phase has been lost by transformation. The CeO2–ZrO2 powders consist of a mixture of cubic, tetragonal (major), and monoclinic polymorphs of which the monoclinic phase disappears after plasma spraying. After extended thermal cycling, the Y2O3–ZrO2 coatings did not alter in phase composition whereas the CeO2–ZrO2 coatings became entirely tetragonal.

The ternary phase diagram of the system Bi2O3-CdO-GeO2 was investigated in several isothermal sections using predominantly X-ray powder diffraction. The following phases are described with respect to their crystal chemistry, phase relations and powder patterns: Bi2−2xCd2x(O3−x⍽9+x) (solid solution with anti-α-AgI structure), CdGeO3 (complicated polymorphism), Bi12GeO20 (stoichiometric sillenite), Cd-sillenite (solid solution), Bi1.8Cd0.2GeO4.9 (metastable, new phase, new structure type with GeO5 polyhedra), Bi2CdGeO6 (new ternary oxide, new structure type).

The powder diffraction pattern of the new lead-based relaxor material Pb0.95Mg0.26Nb0.60Zr0.03O2.78 is described. The compound has a unit cell of a=4.0508(1) Å. The space group of the material is most probably Pm3m, with Z=1 and Dx=7.657 g/cm3.

Reference X-ray diffraction patterns for the quarternary intermetallic superconductor phases of compositions LuNi2B2C and YNi2B2C are reported. Both materials were synthesized by the arc-melting technique. The patterns of these metallic phases exhibit preferred orientation in an ordinarily pressed sample, which was minimized through special specimen preparation. The observed intensities and the calculated values for both phases agree reasonably well with each other. Both compounds were refined in the space group I4/mmm, with a=3.4647(1) Å and c=10.6330(4) Å for LuNi2B2C and a=3.5271(1) Å, c=10.5361(7) Å for YNi2B2C.

Single crystals of rhombohedral bismuth tri-iodide grown by physical vapor transport are possible candidates for room-temperature detectors. Previously reported, low angle reflections in X-ray diffraction patterns of various BiI3 starting powders are attributed to the BiI3 structure from Rietveld analysis. Accordingly, the lattice parameters of stoichiometric BiI3 are determined as a0=7.5192±0.0003 Å and c0=20.721±0.004 Å at room temperature. It also appears that lattice parameter determination using Rietveld refinement can lead to significant errors if experimental aberrations are present and their nature and magnitude are unknown. A modified internal standard technique is applied to the data set prior to Rietveld refinement for more reliable lattice parameter determination.

The modal analysis of samples belonging to the zeolite-rich pyroclastic formation named “Neapolitan yellow tuff” (Central and Southern Italy) has been determined by full-profile refinement of X-ray powder diffraction (XRPD) data using a combined Rietveld–RIR method. The quantitative analysis and especially the zeolite content is a profitable source for geo-petrographic and genetic considerations and as well an essential source to assess the physical and chemical properties of the bulk material for a feasible use in industrial applications. Albeit a wealth of methods are used for the quantitative determination of zeolite content in pyroclastites they all fail for lack of accuracy as far as concerns the absolute standard deviation of the quantitative data. The outstanding outcomes achievable by using the Rietveld method make it as the most promising technique to fulfill this lack. The glass content in each sample is calculated by a combined Rietveld–RIR method in which a known amount of an internal standard is added to the mixture to rescale the Rietveld refined weight fractions into absolute values. Then, it is reasonable to designate this method as an external method according to the definition given by Hill and Howard (1987). Its counterpart is the internal method developed by Riello etal. (1995a,b). Other techniques such as the addition method and the background scattering volume calculation are developed to accomplish a further determination of the glass content. The results are compared to the values obtained from the Rietveld–RIR analysis. These experimental methods yield an over-estimation of the amorphous phase because the incoherent scattering contribution (air, absorption, sample holder, Compton scattering) is accounted for as the amorphous fraction itself. The glass content of each sample acquired from the Rietveld–RIR refinement on the “raw data” is compared to that accomplished from the refinement of incoherent scattering subtracted data. In addition, some largely used XRPD quantitative techniques such as the external standard and RIR (reference intensity ratio) and the influence of the sample loading method are accounted for in an internally consistent comparison among different procedures of analysis.

The effects of sample transparency in a powder diffraction experiment are discussed, and formulas including effects from horizontal divergence are derived. It is shown that the classical formula by Alexander [L. E. Alexander J. Appl. Phys. 21, 126 (1950)] is only a limiting case for zero horizontal divergence. It is also shown that in some cases extinction effects can play a role. The impact of these effects on both the line profile as well as the integrated intensity and experiments illustrating these phenomena, are discussed.

The determination of thin film thickness by four X-ray reflectivity methods (namely, the peak separation, the Fourier transform, the modified Bragg equation, and the curve-fitting methods) has been studied. An analysis of SrS and BaF2 thin films showed thickness values determined by the methods agreed to within 4%. The curve-fitting method had the highest accuracy but was time-consuming. The peak separation, the Fourier transform, and the modified Bragg equation methods are considerably faster and, on average, gave 2.8%, 0.9%, and 0.2% larger thicknesses than those of the curve-fitting method.

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.

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.

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.

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.