X-ray powder diffraction patterns for 18 phases of 14 well-known explosives have been developed in our laboratory. Experimental patterns were obtained with an automated diffractometer for those phases for which samples were available. For phases with known crystal structures, patterns were calculated from the lattice and atomic positional parameters for comparison with the experimental patterns. Eleven of the experimental patterns have been included in Powder Diffraction File (PDF) Sets 40 and 42; four have been accepted but not yet issued. A final experimental pattern shall be submitted this year. In two other instances, since samples of sufficient quantity and/or quality were not available, calculated patterns alone are considered here. A review of the development of the crystallographic knowledge of these substances is given here together with a critique of the patterns and other known patterns of these phases.

A set of nine transition metal oxophosphorous compounds, consisting of four hypophosphites and five phosphites has been synthesized and studied using X-ray powder diffraction techniques. The compounds are α-Mn(H2PO2)2·H2O, Co(H2PO2)2 ·0.53H2O, MCl(H2PO2)2·H2O (M = Co2+, Ni2+), M2(HPO3)2·2H2O (M = Co2+, Ni2+), and M11 (HPO3)8(OH)6 (M = Zn2+, Co2+, Ni2+). Unit cells and X-ray powder patterns are reported.

Bragg–Brentano X-ray powder diffractometry data and refined unit cell parameters are reported for a synthetic sample of dolerophanite, copper (II) oxysulphate [Cu2O(SO4)], prepared by heating AR copper (II) sulphate anhydrate in a muffle furnace at 725 °C. The data are compared with (i) two Debye–Scherrer patterns published by Mrose [Am. Mineral. 6, 146–153 (1961)]—for a synthetic sample and for a natural dolerophanite, the latter being pattern 13–189 in the ICDD Powder Diffraction File and (ii) a Debye–Scherrer pattern for a synthetic dolerophanite described by Borchardt and Daniels [J. Phys. Chem. 61, 917–921 (1957)]. A calculated pattern is also presented for the crystal structure of dolerophanite described by Effenberger [Monatschefte fur Chemie. 116, 927–931 (1985)]. The measured and calculated patterns reported here show reasonable internal consistency for both line positions and intensity data. While the agreement between these results and the data sets of Mrose is sound in terms of line positions, there is substantial disagreement overall between the intensity values given by the authors and those of Mrose. There is closer agreement between the intensities from the current study and those of Borchardt and Daniels.

X-ray powder diffraction is a convenient tool for monitoring changes in structural parameters due to modifications in sample composition and processing conditions. Due to the complexity of incommensurate modulated structures powder diffraction techniques have not been commonly applied. Programs ALSQ and QRIET have been produced to perform lattice parameter and structure refinements on incommensurate modulated materials with a displacive modulation model. In applying these programs to the Bi2Sr2CaCu2O8 superconductor which has this type of structure, it is shown that a decrease in the lattice parameters and an increase in the modulation vector occurs as the Ca content of the Bi-2212 phase, controlled by the use of the glass ceramic process, increases.

The utility of ultra-high-temperature (2100 °C) X-ray powder diffraction technique for investigating the high-temperature phase relationships of two pseudobinary mixtures, Al2O3/Y2O3 and AlN/SiO2, is described. The in situ analysis to 1600 °C was carried out using a platinum holder and a Pt/Rh thermocouple; whereas analysis beyond 1600 °C was performed with a tungsten holder, extremely pure, oxygen-free inert gas environment, and an opticalpyrometer to monitor temperatures up to 2100 °C. The solid-state interaction between Al2O3 and Y2O3 commenced with the formation of Al2Y4O9 (YAM), a yttria rich compound, at 1300 °C followed by AlYO3 (YAP) and Al5Y3O12 (YAG) at 1400 °C. Further heating to 1500 °C and above resulted in the increased concentration of YAG at the expense of the other two phases, followed by melting of the entire sample at 2050 °C. The only phase formed during cooling (from the molten state) was YAG. AlN and SiO2 did not react with each other, in an inert atmosphere, and they remained as separate, discrete phases even at 1600 °C. In the presence of oxygen, they reacted to form mullite and cristobalite, or SIALON depending on the partial pressure of oxygen.

Numerous spurious X-ray peaks were encountered during grazing incidence angle diffractometer scans of ceramic and polymeric thin films on crystalline and amorphous substrate materials. At least three possible sources of spurious peaks are identified. (1) At (2θ) values greater than ∼ 10°, Laue reflections from characteristic and Bremsstrahlung continuum radiation produce spurious peaks with a (2θ) dependence on X-ray incident angle and sample orientation. At (2θ) values less than 10°, (2) specular X-ray reflection from a boundary between two media of different indices of refraction and (3) diffuse surface scattering produces spurious peaks with a dependence on X-ray incident angle and sample surface topography. From an understanding of the spurious peaks, improved experimental techniques may be developed. Because these peaks can interfere significantly with grazing incidence diffractometer scans, it is particularly important to those making studies of thin films by this asymmetric diffraction geometry to be aware of the existence and origins of these spurious peaks.

Residual strains and microstresses are evaluated for both phase of a hot-pressed, fine-grained α-alumina reinforced with 25 wt% (29 vol%) single-crystal silicon carbide whiskers at temperatures from 25 to 1000 °C. The sample was maintained in a nonoxidizing environment while measurements of the interplaner spacing of alumina (146) and SiC (511 + 333) were made using X-ray diffraction methods. The residual strains were profiled at temperature increments of 250 °C from which the corresponding microstresses were calculated. Linear extrapolation of the SiC ε33 profile indicates that the strains are completely relaxed at a temperature of approximately 1470 °C. These residual stress relaxation results suggest that elevated temperature toughness and fracture strength of this composite may result from cooperative mechanisms.

The X-ray powder diffraction pattern of hydrated lithium monoborate LiB(OH)4, sometimes formulated LiBO2·2H2O, has been obtained. Refinements of indexed reflections yielded the following parameters: a = 9.1732(7)Å, b = 7.9622(6)Å, c = 8.5354(8)Å, space group Pbca, Z = 8, Dx = 1.827, Dm = 1.83 g/cm3. The Smith–Snyder figure-of-merit is F30 = 101(0.007,44).

Single crystals and powder samples of Ba4ZnTi11O27 and Ba2ZnTi5O13 have been synthesized and studied using single-crystal X-ray precession photographs and X-ray powder diffraction. Unit cell dimensions were calculated from a least-squares refinement with a final maximum Δ2θ of 0.05°. Both phases were found to have monoclinic cells, space group C2/m. The refined lattice parameters for the Ba4ZnTi11O27 compound are a= 19.8687(8) Å, b=11.4674(5) Å, c=9.9184(4) Å, β= 109.223(4)°, and Z=4. The refined lattice parameters for the Ba2ZnTi5O13 compound are a= 15.2822(7) Å, b=3.8977(1) Å, c=9.1398(3) Å, β=98.769(4)°, and Z=2.

A natural olivine sample from a mantle peridotite xenolith has been studied by in situ high-temperature powder diffraction. The structure has been successfully refined from powder data at three temperatures (25, 600, and 800 °C) using the Rietveld method. The study shows that the full-profile technique is well suited for the structure analysis of high-temperature powder diffraction data. The results indicate that, in this temperature range, there is no significant ordering of the Fe,Mg cations in the two crystallographically independent octahedral sites. This has implications for the thermodynamic modeling of olivine at upper mantle conditions. The present experiments allowed measurement of the lattice thermal expansion of olivine in the temperature range 25–800 °C, and assessment of the temperature dependence of the isotropic atomic displacement parameters.

Afghanite is a feldspathoid of the cancrinite-group: It is hexagonal, space group P63mc. The afghanite sample was found in the M. Somma-Vesuvio volcanic complex (Italy) and was previously described as davyne: Calculated cell parameters are a = 12.7997(4) Å, c = 21.4062(11) Å; the volume is 3037.2(2) Å3. The strongest lines are: 3.694(100), 3.647(56), 4.826(30), 2.678(25), 2.134(18), 3.999(12), 2.750(12), and 2.771(10). The new data provide quantitative measurement of intensities, an increased number of indexed peaks, and a different empirical formula with respect to the PDF 20-1086.