X-ray powder diffraction patterns of orthorhombic- and rhombohedral-distorted perovskite PrNiO3 obtained at room temperature, 200°, 400°, 500°, and 600°C were analyzed and evaluated. An examination of the diffraction profiles shows essentially no line broadening indicating that the PrNiO3 powders synthesized by solid state reaction are well-crystallized and probably strain-free. The reliability and accuracy of the patterns were evaluated, and the figures-of-merit were in triple digits for the 500° and 600°C patterns of the rhombohedral phase and double digits for the more complex orthorhombic diffraction patterns recorded at room-temperature, 200°, and 400°C. Values of lattice parameters refined from the observed diffraction peak positions agree with those obtained from the Rietveld whole-pattern fitting analysis to within 1–2 × 10−4.

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.

X-ray diffraction experiments performed on the compounds FeIINbIVF6 and CoIINbIVF6 have shown that they crystallize in the rhombohedral system, space group R3¯ with a cationic ordering. Unit cell parameters were determined: a=5.4201(8) Å, c=14.072(2) Å, V=357.8(1) Å, Z=3 for FeNbF6, and a=5.351(2) Å, c=13.960(6) Å, V=346.2(2) Å, Z=3 for CoNbF6. Synthesis and powder diffraction data are reported.

Each of the RIR based methods for carrying out quantitative X-ray powder diffraction analysis are described and a consistent set of notation is developed. The so called “standardless” analysis procedures are shown to be a special case of the internal-standard method of analysis where the normalizing assumption is used. All analytical methods, other than the Rietveld whole pattern matching procedure, require the use of explicitly measured standards, typically in the form of RIR values. However, if only semi-quantitative results can be tolerated, the standards may be obtained by using published RIR and relative intensity values. The exciting new techniques of whole pattern fitting and Rietveld constrained quantitative analysis are also described in RIR notation and shown also to be forms of the internal-standard method with the normalization assumption. The quantitative results obtained from Rietveld quantitative analysis are derived from computed standards in the form of computed, normalized, RIRN values. The normalization assumption in Rietveld analysis allows the exclusive use of computed standards and comes as close to a “standardless” analysis as one can achieve: relying on the absence of amorphous material and on the validity of the structural models. Relationships are given for obtaining quantitative analysis from these RIRN values obtainable from the least-squares scale factors.

A nonlinear optical material 3-nitro–4-hydroxy–4′-bromobenzophenone has been characterized by x-ray powder diffraction. Experimental values of 2θ, corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 109 observed reflection with 2θ up to 90° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The unit cell parameters least-squares refined from 34 nonoverlapping peaks of the orthorhombic compound with a P212121 space group are a = 7.619(7) Å, b = 27.651(5) Å, c = 5.650(7) Å, V = 1190.5(9) Å3, Z = 4, and Dx = 1.389 g/cm3.

Room temperature crystalline structures of La2-xSrxCuO4 samples with uncommonly high hole concentrations (p) up to p=0.4, annealed under 1 and 100 bars of oxygen pressure have been analyzed by X-ray diffraction. Results show that the x=0 sample with p=0.09 and superconducting below 20K is orthorhombic at room temperature. The orthorhombic distortion at 300K decreases with increasing x and becomes tetragonal when x reaches 0.08. This orthorhombic-to-tetragonal phase transformation is consistent with previous work. Samples with x≥0.28 and p≥0.31 remain tetragonal but are nonsuperconducting down to 5K. Lattice dimension anomalies have also been observed and are correlated with the sudden appearance of oxygen vacancies, as seen by the hole concentration measurements. Initially, the value of the lattice dimension a decreases and c increases monotonically with increasing x. A sudden increase in a and decrease in c begins when x reaches 0.28 for samples prepared under 1 bar of oxygen indicating a sudden loss of oxygen from the structure. This sudden reversal in lattice dimensions a and c is not present in samples annealed under 100 bars of oxygen pressure suggesting essentially no oxygen vacancies. The increase in c with x of the La2-xSrxCuO4 samples with no oxygen vacancies can be attributed mainly to the result of substituting smaller La+3 ions by larger Sr+2 ions. A study of the variation of c with the hole concentration reveals that the c lattice dimension drops sharply with no change in the hole concentration when oxygen is continuously removed from the lattice caused by an increase of the Sr content in La2-xSrxCuO4.

A new method for the quantification of montmorillonite by full-profile Rietveld analysis of the XRD profile is presented. A measured standard XRD pattern of Algerian bentonite was used to construct a universally applicable montmorillonite (hkl) file for use with a P.C. based Rietveld XRD quantitative analysis system, SIROQUANT. “Universal” means that the standard file can be used for montmorillonites from other localities. The validity of the montmorillonite standard profile was tested with weighed mixtures of quartz and different standard montmorillonites. The results show the montmorillonite observed (hkl) file is generally applicable (i.e., universal), and can be used to quantify montmorillonite in any mineral without modification or chemical treatment of the sample. Two halfwidth functions were used for the montmorillonite, corresponding to the sharp (hk0) and broad (hkl) classes of reflections. A March preferred orientation parameter for montmorillonite was also refined.

A new quantitative X-ray powder diffraction (QXRPD) method has been developed to analyze polyphase crystalline mixtures. The unique approach employed in this method is the utilization of the full diffraction pattern of a mixture and its reconstruction as a weighted sum of diffraction patterns of the component phases. To facilitate the use of the new method, menu-driven interactive computer programs with graphics have been developed for the VAX series of computers. The analyst builds a reference database of component diffraction patterns, corrects the patterns for background effects, and determines the appropriate reference intensity ratios. This database is used to calculate the weight fraction of each phase in a mixture by fitting its diffraction pattern with a least-squares best-fit weighted sum of selected database reference patterns.

The new QXRPD method was evaluated using oxides found in ceramics, corrosion products, and other materials encountered in the laboratory. Experimental procedures have been developed for sample preparation and data collection for reference samples and unknowns. Prepared mixtures have been used to demonstrate the very good results that can be obtained with this method.

A comparison of X-ray powder diffraction and electron probe microanalyses on samples of Na- and K-doped Bi4V2O11 (BIMEVOX) solid electrolytes indicates some of the problems associated with using XRD to assess phase purity, especially in materials of variable composition such as BIMEVOXes. In this study both the Na- and K-doped materials appeared phase pure by XRD. EPMA indicated the Na-doped materials to be single phase with their expected compositions while the K-containing materials were not phase pure with very little K present in the main BIMEVOX phase.

An environmentally controlled sample stage for Scintag's six-position XRD sample changer is described. Unlike the commercial environmental stages for Scintag XRD units which require removal of the sample changer, and installation and alignment of the sample stage, the stage described herein is designed to fit directly on the sample changer with no realignment. Such a stage provides for more convenient operation for an X-ray diffractometer with multiple users in both routine (ambient environment) and nonroutine (nonambient temperatures up to 250 °C and varying relative humidities) modes. In addition, the new stage uses a window made of a material that is safer to machine compared to beryllium (which is toxic).

Synthesis and unit cell parameter refinement of 25 ferroelectric compounds with the tungsten bronze structure are reported. A general chemical formula for these compounds is (A1, A2, C) B10 O30, where specifically A1 and A2 = K, Na, Ba, Sr, Pb, La, Eu, Sm, Y, Bi; C = Li; and B = Nb, Ta, Ti, W. All compounds were prepared by solid state sintering at temperatures ranging from 1100°C to 1380°C. Refined cell parameters (tetragonal with space group P4bm[100]), I/Icor values, calculated densities and Z values are included for the 25 compounds.