The combustion synthesis of the common ferroelectric material, BaTiO3, was developed using the stoichiometry: BaO2+0.2 Ti+0.8 TiO2→BaTiO3+0.3 O2. An adiabatic temperature, Tad, of the reaction was calculated from known thermodynamic data to be 1917 °C. Real time chemical changes in the formation of BaTiO3 during the reaction have been monitored using time-resolved X-ray diffraction with synchrotron radiation as the X-ray source. A time resolution of 250 ms was achieved. The combustion synthesis of BaTiO3 was followed by observing the intensities of reactant and product Bragg diffraction peaks in order to qualitatively identify the phases present. Because BaTiO3 forms initially as a cubic phase, X-ray diffraction of the product was monitored for a period of 20 min after the reaction to observe the phase transformation to the tetragonal form. This transformation is evident in these post-reaction scans as the cubic 110 and 220 peaks are split to the tetragonal 101/110 and 202/220 ones, respectively.

2,4-dichloro-5-nitrobenzoic acid (C7H3NO4Cl2) has been investigated by means of X-ray powder diffraction. The title compound is monoclinic with unit-cell parameters a=13.761 (2), b=8.435 (1), c=7.684 (1) Å, β=99.85 (1)°, V=878.5 (1) Å3, Z=4, Dx=1.772 g/cm3, space group P21/a (14).

Yttrium oxalate dihydrate, Y2(C2O4)3.2H2O, has been investigated by means of X-ray powder diffraction. Unit cell dimensions were determined by an indexing program based on the variation of parameters by successive dichotomies. The diffractometer data were collected with strictly monochromatic radiation. A monoclinic cell was found: a=9.3811(8)Å, b=11.6385(15)Å, c=5.9726(7)Å, β=96.079(8)°, which is characterized by the figures of merit M20=87 and F30=112 (0.0065,41). A preliminary analysis of the anisotropic line broadening has revealed some microstructural properties. It is shown that line broadening is mainly due to a micro-strain effect.

Powder X-ray diffraction data are reported for semimagnetic semiconductor Hg0.89Fe0.11S and Hg0.98Co0.02S crystals grown by the Bridgman method and for Hg0.80Mn0.20S crystal synthesized by a solid-state reaction method. The crystals have the sphalerite structure of metacinnabar (sphalerite-type high-temperature polymorph of HgS, space group F4¯3m). Phase analysis does not show any trace of other phases. The lattice parameters of the studied samples are a=5.803 20(5) Å, 5.8063(1) Å and 5.839 80(6) Å, respectively. The calculated density is reported.

A method of analysis for X-ray diffractometry is proposed for determining the number and the concentrations of phases in a series of samples of the same multiphase system. This method can be used when n samples containing N phases, where N<n, with different concentrations are given or prepared from a given sample.

The method of principal component analysis was applied to the determination of the number of individual phases in multiphase mixtures. A quantification method using the intensity ratio to an arbitrary chosen standard mixture, which is also one of the mixtures to be analyzed, is proposed.

In this study, we examined the validity of this method for X-ray diffractograms of two and three component systems. It is shown that the values determined by the present method are in good agreement with the prepared concentrations of the samples.

DISVAR93 is a collection of programs devised to process XRPD patterns with the aim of determining the parameters of systematic instrumentation and sample effects. These effects have an influence on data uncertainty and also accuracy of the adopted models describing diffraction phenomena. Such modeling is carried out through the mathematical X-ray powder-diffraction theory, while parameter optimization is achieved by using the additive property of X2 and constraining the models to converge simultaneously to the same minimum in a restrained Hilbert's space. The package has been designed to allow both user interaction as well as automatic linking of programs managed by one main menu and offer several options to satisfy individual user requirements.

An X-ray diffraction peak-broadening analysis of four oxides is described: La2CuO4 and La1.85M0.15CuO4 (M = Ca,Ba,Sr) high-Tc superconductors. The diffraction line profiles were fitted with a convolution of specimen and instrumental functions, and the specimen peakbroadening angular dependence was analyzed with the Warren-Averbach method. It was found that microstrains and incoherently diffracting domains are highly anisotropic. In the superconductors, stacking-fault probability increases with increasing Tc; microstrain decreases. In La2CuO4, different broadening of (h00) and (0k0) reflections is not caused by stacking faults; it might arise from lower crystallographic symmetry.

The two ternary phases W5As2.5P1.5 and Ni4Nb5P4 have been investigated by X-ray powder diffraction. Precise data for the two compounds were collected using CuKα1 radiation over the range 11°–140° 2θ. Unit cell refinements (space group I4/m) led to a=9.4729(3) Å, c=3.2414(2) Å (Dx=13.16 gcm−3) with M20=127, F30=91(0.0092,36) for W5As2.5P1.5 and a=9.9304(4) Å, c=3.5243(3) Å (Dx=7.87 gcm−3) with M20=179, F30=138(0.0068,32) for Ni4Nb5P4.

Structural and chemical changes in materials can be dynamically observed by using time resolved X-ray Powder Diffraction (XRPD) to collect patterns as these events happen. During calcination of amorphous zirconium hydroxide, Zr(OH)4, and its crystallisation to a metastable tetragonal form of zirconia, ZrO2, patterns have been collected at 10°C temperature intervals during a heating sequence to 500°C. These patterns show both the onset of ordering within the amorphous starting material and the progress of its conversion into crystalline zirconia. Events are recorded within the pattern in the form of peak growth and reduction in amorphous component of the pattern with increasing temperature.

The activity of the high Tc task group of the ICDD Ceramic Subcommittee is described. This activity includes the compilation of X-ray powder diffraction patterns of the high Tc superconductors and related phases identified from the International Centre for Diffraction Data/Powder Diffraction File (ICDD/PDF). The coverage of this ICDD/PDF Superconductor SubFile (SC) includes high Tc phases and their structurally related phases, products of elemental substitution in the high Tc phases, phases found in the phase diagrams containing the high Tc phases, as well as potential reaction products with commonly used sample containers, and potential conventional low-temperature (metallic and nonmetallic) superconductors.

Although there is mounting interest in the measurement of stresses in composite materials after fabrication and/or use, few measurements to date have not taken into account the three dimensional nature of the stress system in such materials. Most data give only the net stress, that is, the difference between principal stresses. A procedure for a more complete measurement (in a reasonable time) is developed here, including the separation of macrostresses and microstresses. If time does not permit a full investigation, measurements of the lattice parameters of the component phases provide a simple way to sample the hydrostatic component due to differential thermal contraction. The Barrett-Predecki method of adding filler is particularly promising for stress measurements in those composites whose component phases do not give appropriate diffraction peaks. This procedure could also be used for monitoring stresses during the useful life of such materials.