Crystal and X-ray powder diffraction data are presented for the title compound. The powder pattern was indexed and refined on a monoclinic cell with a=17.356(6) Å, b=3.528(1) Å, c=11.285(1) Å, β=94.23(2) Å. The cell volume and Dm=1.772 g/cm3 give Z=4. The space group could not be determined with certainty. The planes of the urate anions likely are stacked parallel or nearly parallel to (010).

The crystal structure of 1-amino-4-methoxycarbonyl-3-methyl-8-oxopyrazolo[1,5-a]pyrimidine monohydrate, C9H10N4O3·H2O, from the family of pyrazolo[1,5-a]pyrimidines which demonstrate an activity against the influenzavirus A and coxsackievirus B3, has been determined from laboratory (Guinier-Johannson photograph) powder diffraction data using a grid search procedure. Parameters of the monoclinic cell (P21/a, No. 14, Z=4) at 295 K are a=11.599(7) Å, b=11.550(7) Å, c=8.575(5) Å, β=110.76(4)°. Rietveld refinement (full-pattern-decomposition) gave χ2=4.8(4.5), Rp=0.048(0.043), Rwp=0.065(0.062). The observed microstrain-induced anisotropy of diffraction line broadening was approximated by a quartic form in h,k,l. The obtained results allowed to distinguish between several isomers which were indistinguishable by others methods.

Arsenic molybdate, As2MoO7, produced by phase transformation of As4Mo3O15, has been analyzed by X-ray powder diffraction. The powder diffraction data were collected with a focusing (Guinier-type) transmission diffractometer equipped with a primary-beam monochromator (Ge 111) for Cu Kα radiation and a scanning position-sensitive detection system. A monoclinic unit cell was determined using an indexing program and compared with calculated single crystal data.

A two-stage procedure is described for quantitative phase analysis of multicomponent mixtures. Profile analysis of the diffraction pattern of a mixture of phases is done in stage one to obtain integrated intensities with higher accuracy. In stage two a structural refinement is done which yields a scale factor. The weight of a phase in a mixture is proportional to its specific scale factor. The two-stage method was found to be effective for the quantitative phase analysis of a mixture of minerals which always contain structural defects. The procedure was tested first by using two artificial mixtures and then it was applied to natural kaolin. The results obtained were more accurate than some of the other methods used for quantitative analysis; moreover, it can also be used with mixtures containing amorphous or undetermined phases.

Although forensic science is regarded with a certain amount of fascination and admiration by the general public, to the practising forensic scientist it is often associated with painstaking and frustrating examinations.

This is particularly so in the most traditional area of forensic science, namely that of contact evidence where the identification and comparison of minute samples may provide an important clue for the investigator and assist in the conviction or exoneration of an accused person.

Contact evidence may include hairs and other fibres, paint samples, glass fragments, stains, soils and other deposits. Modern instrumentation such as infra-red spectrophotometry, gas chromatography, atomic absorption spectroscopy and energy dispersive X-ray analysis now allows a relatively simple identification of the composition of these materials. However, these techniques are not necessarily directed towards the absolute determination of structure of materials and this is particularly so in the case of crystalline materials of forensic interest such as soil, mortar, brick dust and paint fillers. Although the techniques previously mentioned provide the basis of an elemental analysis this may not be of much assistance in a forensic approach where chemical structure is the basis of a scentific comparison.

Three computer programs for Rietveld analysis DBWS-9411, HILL-93.06, and FULLPROF-3.1 have been tested and compared using data for two samples of different complexity, spinel, and anglesite. The investigation shows that results are “program dependent.” The obtained R indices for spinel are in the ranges 10.60%–13.26%(Rwp) and 3.15%–5.25%(RB). Similarly, the ranges for anglesite are 9.76%–14.06%(Rwp) and 2.15%–5.06%(RB). Some atom and displacement parameters are significantly different, too. In attempt to define the standard procedure for Rietveld analysis, three parameters, n, BKPOS, and RLIM were examined. It was found that the most appropriate values for them are: n=8–10, BKPOS=90°, and RLIM=40° 2θ. Using Fourier filtering for background modeling, significantly lower R indices were obtained in comparison to polynomial and interpolated background. At the same time the great numbers of atom and cell parameters agree within ±3σmax and e.s.d.'s were identical or lower than those achieved for polynomial and interpolated background. It was found that the function given by Bérar and Baldinozzi (1993) (J. Appl. Crystallogr. 26, 128–129) much better described asymmetric peak profiles at low 2θ angles. This function and Fourier filtering were implemented only in FULLPROF, which has more possibilities and some advantages over the other two programs. In addition, the peak shift parameters (sample displacement and transparency) were tested. It was shown that under present circumstances these parameters do not have much effect on atom parameters and R indices. However, differences in unit cell parameters were considerable greater, most probably because of the large correlation between zero-point, lattice, and peak shift parameters.

The crystal structures of BaR2ZnO5, where R=La, Nd, Dy, Ho, and Y, were studied by neutron diffraction, and that of the Er analog was investigated by synchrotron X-ray diffraction. Two structure types were confirmed for this series of compounds and agreed with those reported in literature. The compounds with a smaller size of R (R=Dy, Ho, Y, and Er) are isostructural to the orthorhombic “green phase (BaY2CuO5)” compounds. The cell parameters for compounds with the R=Er to Dy range from a=7.0472(1) Å to 7.0944(1) Å, b=12.3022(1) Å to 12.3885(2) Å, and c=5.6958(1) Å to 5.7314(1) Å, respectively. R is 7-fold coordinated inside a monocapped trigonal prism. These prisms share edges to form wavelike chains parallel to the long b-axis. The Ba atoms reside in 11-fold coordinated cages. The compounds which contain a larger size R (R=La and Nd) crystallize in the tetragonal I4/mcm space group, but are not isostructural to the “brown phases” BaR2CuO5. The lattice parameters for the La and Nd analogs are a=6.9118(1) Å, c=11.6002(2) Å for BaLa2ZnO5, and a=6.7608(1) Å and c=11.5442(2) Å for BaLa2ZnO5. The structure consists of ZnO4 tetrahedral groups (instead of planar CuO4 groups as found in the brown phase) with Ba ions inserted in between. The structure can be viewed as consisting of alternate layers of Zn-Ba-O and Nd-O extending infinitely in the xy plane and perpendicular to the z-axis.

Twenty seven new rare earth (Ln) compounds CuLn2 Ge2O8, CuLn2Ge4O12 and CuLn2Si4O12 have been synthesized. The powder diagrams were indexed and solid solutions of silicates and germanates were investigated. Structural variations with temperature, lanthanide contraction and Ge/Si substitution are described. Indications for second order phase transitions were found.

In the preparation of ceramic SrCe0.95Yb0.05O3−α great care was taken to obtain a homogeneous, carbonate free and dense material of exactly the given composition. The material is an important high-temperature protonic conductor (HTPC). X-ray powder diffraction data are reported. The cell parameters obtained are a=6.007(2) Å, b=12.296(3) Å, c=8.588(2) Å, cell volume 634.4(1) Å3, Z=8. The space group is most probably Pnma (62) and Dx=5.806(2) g/cm3. The bending strength of the sintered dense material is 175±6 MPa.

Two structurally related compounds, Tl3Li(MoO4)2 and Tl3Li(WO4)2, have been synthesized by solid state reaction. Space group (P63mc) and unit-cell parameters [a(Å)=6.00392(3); c(Å)=15.8203(1) and a(Å)=6.03484(3); c(Å)=15.81759(9), respectively, for Tl3Li(MoO4)2 and Tl3Li(WO4)2] were determined. Powder diffraction data for each phase are reported.

Characterization of some crystalline species present in atmospheric particulate matter can be investigated by an X-ray diffractometric technique. According to the analytical strategy, filtering media suitable for collecting airborne particles must be selected. In order to recognize the X-ray diffraction patterns and consequently the inherent analytical interference of filtering media, a systematic X-ray diffraction evaluation of several substrates was performed. Although artifact formation during ambient sampling can occur on quartz and glass fiber filters, these filters were also included in the diffractometric characterization. In this work, commercial filters were thermally treated and submitted to X-ray diffraction scanning. Results have shown pronounced variations in the diffractometric profiles of each thermally treated substrate. The selection criteria for choosing the filtering media was established by considering their chemical and physical properties and also the crystalline species to be collected on them.

New solid solution phases in the (Y,Ca)(Cr,Co)O3 system have been synthesized and characterized by powder X-ray diffraction. The selected compositions in this system were prepared by the modified Pechini method. Powder-diffraction patterns were prepared.

Precise X-ray powder diffraction data are given for two germanides, CoGe and Co5Ge7. The refined unit cell parameters for CoGe are a=11.630(1) Å, b=3.8014(3) Å, c=4.9347(3) Å and β=100.889(8)° (space group C2/m, Pearson symbol mC16) with volume of the unit cell 214.24(2) Å3; the figures of merit are M20=96, F30=77 (0.0085, 46). The refined unit cell parameters for Co5Ge7 are a=7.6262(4) Å and c=5.8017(5) Å (I4mm, tI24) with volume of the unit cell 337.42(3) Å3; the figures of merit are M20=204 and F22=130(0.0068, 25). The dependence on composition of the unit cell parameters of CoGe is discussed in terms of specific defect structures.