An analysis of the microstructure of nanocrystalline yttrium oxide produced by thermal decomposition of a double oxalate yttrium and ammonium, at temperatures in the range 600 °C to 900 °C, is described. The study is based on line broadening analysis carried out with the (Voigt/Langford) integral breadth and Fourier methods combined with the pattern decomposition technique. Due to the line overlap arising from the density of diffraction lines, the whole pattern refinement method (pattern matching and Rietveld approaches) is also applied. No marked line broadening anisotropy is observed in the patterns. It is shown that for the two samples prepared at the highest temperatures the results are similar whatever the method used and the material can be considered as strain free. For the two lowest temperatures only the whole pattern refinement method is applied. The results suggest that a small amount of lattice microdistortion is present in these two last samples. It is shown that the crystallite growth varies exponentially with temperature. The results obtained from line broadening analysis are compared to those observed with scanning electron microscopy, from which a good accordance is noted between the two techniques.

X-ray powder diffractograms from fcc crystals containing high concentration (more than 1%) of planar defects [deformation stacking faults (SF), double deformation SF, twin boundaries (TB)] have been simulated by Monte Carlo method in kinematic approach. It was shown that the characteristics of powder diffraction peak profiles (except peaks with indexes H00) dependent nonmonotonically on PD concentration, during which peak maximums stay in Bragg positions. An addition point to emphasize is that an appearance of TB only in the crystal not affects on position of all peaks. Several types of PD to be occurred simultaneously in the crystal influence on powder diffractograms additively. Peculiarities of the powder diffraction pattern inherent in different types of PD have been revealed to permit predominant PD type to be found with a high degree of accuracy based on experimental data.

It was seen during the phase relation studies on the CeO2–YO1.5 system that the ceria is able to accommodate a large anion deficiency caused by aliovalent substitution. A neutron powder diffraction study has been carried out at room temperature for the titled solid solution, Ce1−xYxO2−x/2 with x=0.32, which is an anion-deficient variant of the ideal fluorite structure. The structure has been found to be face centered cubic. No superlattice reflections have been observed indicating that the vacancies occupy the random positions in this highly defective solid solution. The bond distances and angles are also being reported.

Fluorellestadite, Ca10(SiO4)3(SO4)3F2, has been synthesized as single phase. This compound crystallizes in the apatite type structure, s.g. P63/m, with parameters a=9.4417(1) Å, c=6.9396(1) Å and V=535.76(1) Å3. The refinement of its crystal structure converged to RWP=12.33% and RF=4.58%. The atomic parameters have been used to analyze the phase content of mineralized white Portland clinkers. These clinkers contain Ca3SiO5, Ca2SiO4, Ca12Al14O32F2 and Ca10(SiO4)3(SO4)3F2. The agreement between the elemental composition inferred from the Rietveld phase analysis and that measured by XRF is noteworthy. This comparison does not take into account the presence of amorphous phases and unmodeled elemental substitutions in crystalline phases. Similar Rietveld studies on commercial white Portland clinkers are also shown to be feasible.

The Rietveld method can be combined with the addition method to determine the absolute quantities of the phases treated by Rietveld refinement plus the quantity of phase(s) not treated by it (amorphous or unobserved). If q is the added proportion of a defined phase already present in the sample, and a1 and a2 its relative proportions as determined by Rietveld refinement prior and after the addition, the proportion of the amorphous (untreated) phase(s) in the original sample is calculated as xo=[a2−(1−q)a1−q]/(1−q)(a2−a1). The absolute quantities of the phases treated by Rietveld refinement are then determined by a correction for the content of the amorphous phase(s), or they can be calculated directly from specific equations. The advantage of the method is that no new variables are introduced in the refinement when the added standard already is a part of the original mixture.

The structure of the oxyphosphate Li0.50Ni0.25TiO(PO4) has been determined from conventional X-ray and neutron powder diffraction data. The parameters of the monoclinic cell (space group P21/c, Z=4), obtained from X-ray results, are: a=6.3954(6) Å, b=7.2599(6) Å, c=7.3700(5) Å, and β=90.266(6)°; those resulting from neutron study are: a=6.3906(7) Å, b=7.2568(7) Å, c=7.3673(9) Å, and β=90.234(7)°. Refinement by the Rietveld method using whole profile, leads to satisfactory reliability factors: cRwp=0.128, cRp=0.100, and RB=0.038 for X-ray and cRwp=0.110, cRp=0.120, and RB=0.060 for neutrons. The structure of Li0.50Ni0.25TiO(PO4) can be described as a TiOPO4 framework constituted by chains of tilted corner-sharing TiO6 octahedra running parallel to the c axis and cross linked by phosphate tetrahedra. In this framework, there are octahedral cavities occupied by Li and Ni atoms: Li occupies the totality of the 2a sites and Ni occupies statistically half of the 2b sites. Ti atoms are displaced from the center of octahedra units in alternating long (2.242 Å) and short (1.711 Å) Ti–O bonds along chains.

The change in the orthorhombic structure of PbZrO3 was studied as a function of the La substitution for Pb and Ti substitution for Zr. Two types of changes can occur: (1) a change in the atom coordinates toward the positions for a perfect cubic perovskite lattice; and (2) a change of orthorhombic unit cell parameters so that ao, bo, and co exactly fit with the cubic cell parameter ac. Therefore, ao=ac√2, bo=ac.2√2, and co=ac.2, where ao, bo, and co are the orthorhombic cell parameters, and ac is the cubic cell parameter. Substitution of Pb by La in the orthorhombic PLZT leads to both a change in atom coordinates and a change in unit cell parameters toward the perfect cubic structure, especially for La≥4. Substitution of Zr by Ti in the orthorhombic PLZT leads to similar atom coordinate changes, but the unit cell parameters do not change. The composition 0/92.5/7.5 contains a major tetragonal phase and a minor orthorhombic phase. There are only small differences in the orthorhombic structure between the A and the B composition of PLZT. The A composition has a structure closer to the cubic structure than the B composition.

Rietveld neutron powder profile analysis of the (Na1−xKx)0.5Bi0.5TiO3 (NKBT) series (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) is reported over the temperature range 293–993 K. A detailed characterization of the structures and phase transitions occurring across this series as a function of temperature has been made. Room-temperature refinements have revealed a rhombohedral phase, space group R3c for x=0, 0.2, and 0.4, which exhibits an antiphase, a−a−a− oxygen tilt system with parallel cation displacements along [111]p. An intermediate zero-tilt rhombohedral phase, space group R3m possessing cation displacements along [111]p, has been established for x=0.5 and 0.6. At the potassium-rich end of the series at x=0.8 and 1.0, a tetragonal phase, space group P4mm is observed possessing cation displacements along [001]. At the sodium-rich end of the series for x=0.2, the unusual tetragonal structure with space group P4bm is seen for Na0.5Bi0.5TiO3 which possesses a combination of in-phase a0a0c+ tilts and antiparallel cation displacements along the polar axis. Temperature-induced phase transitions are reported and structural modifications are discussed.

A novel porous material of composition Zn3(VO4)2⋅3H2O was prepared hydrothermally. The solid crystallizes in the hexagonal space group P6, with a=6.078 77(8), c=7.1827(2) Å, and V=229.857 Å3.

All known occurrences of nickelphosphide (Ni,Fe)3P—a mineral encountered mainly in meteoritic irons—represent relatively small grains, which prevents acquiring powder data of a reasonable quality. Synthetic analogues of this mineral, corresponding chemically to that found in the meteorite Vicenice, have been synthesized. Powder data collected using a standard laboratory diffractometer in the Bragg–Brentano geometry are presented. The space group of nickelphosphide is identical to that of schreibersite (Fe,Ni,Co)3P and synthetic Ni3P—I4. The unit-cell dimensions refined from the powder data are a=9.0168(1) Å, c=4.4501(1) Å, and V=361.80(1) Å3, with Z=8.

The compound Ba4Nd3F17 was prepared by heating predried BaF2 and EuF3 (4:3) at 900 °C for 8 h in static vacuum. The polycrystalline sample obtained was characterized by Rietveld refinement of the observed powder diffraction data with the starting model of Ba4Y3F17. This compound crystallizes in a rhombohedral lattice with unit-cell parameters, a=11.2818(3) and c=20.7788(11) Å, Z=6, (Space group R 3, No. 148). The Rp, Rwp and Rexp factors were 9.5%, 12.9% and 10.9%, respectively.

The two mixed halides of barium, barium chloroiodide and barium bromoiodide, were synthesized via a solid-state reaction route. In this article, their powder XRD data are reported. A careful analysis of the X-ray data shows that both BaClI and BaBrI crystallize in the orthorhombic structure. The lattice parameters obtained are a=17.841±0.003 Å, b=8.441±0.001 Å and c=5.642±0.001 Å for BaClI (SG. Pbam, No. 55) and a=13.667±0.002 Å, b=12.012±0.001 Å and c=10.871±0.002 Å for BaBrI (SG. P2221 No. 17).