Pentastrontium bromidephosphate, Sr5(PO4)3Br, was prepared by solid state reaction. The crystal structure of polycrystalline Sr5(PO4)3Br was refined from X-ray powder diffraction data by the Rietveld method using the structure model of Sr5(PO4)3Cl single crystals. Sr5(PO4)3Br is isostructural with Sr5(PO4)3Cl. The space group is P63/m. The cell parameters are a0=9.9641(1) Å, c0=7.2070(1) Å, α=β=90°, γ=120°, Z=2, d(calc)=4.27 g/cm3, and d(expt)=4.10 g/cm3. Atomic parameters are given. Final values are Rp=10.9%, Rwp=14.3%, and S=1.28. The figure of merit is F30=58 (0.013, 39).

The main difficulty in the quantitative mineral analysis of rocks is connected with the variable nature of the mineral species. In the present paper a combined method (and a corresponding computer program) is proposed, which practically overcomes this difficulty. This method is based on linear equations, which are a combination of the chemical mass-balance equations with those of the quantitative X-ray diffractometry, and can perform (completely or partly) both the quantification and the chemical characterization of the minerals on several rock samples simultaneously, demanding only easily accessible initial information, such as: (i) major element (oxide) compositions for the samples; (ii) qualitative mineral composition of the samples; (iii) X-ray intensities for one or few nonoverlapped reflections of the crystalline minerals (not necessarily of all): (iv) some characteristic data for the phases (i.e., chemical composition data), if these are accurately known. Where it is possible the minerals may be expressed via end members. The samples may contain amorphous phases and/or phases without X-ray data. From the general case some very simple partial cases are derived, demanding less initial information. This method has the following advantages over the previous ones of similar philosophy: (i) drastic reduction of the number of required samples; (ii) sufficiency of equations for any analytical problem; (iii) possibility of performing partial analysis when a complete one is impossible; (iv) possibility of using the same end member in more than one solid solution. Analysis examples are given.

The powder diffraction data for 1-aminoanthraquinone at 295 K (P1¯, No. 2, Z=1) are given. The cell parameters found are a=8.205(1), b=8.396(1), c=3.7882(3) Å, α=93.46(1), β=92.57(1), γ=105.13(1)°. The crystal packing model is proposed giving Rb=0.095. The disordered molecule of 1-aminoanthraquinone occupies a special position on the inversion center.

Taking advantage of the feasibility to obtain well-prepared surfaces, an extensive work has been done in studying X-ray diffraction line broadening effects from flat polycrystalline samples of uranium and uranium alloys. The broadening analysis has been used as a semiquantitative method for measuring inhomogeneity of alloying, hardness, and residual thermal stresses. Good correlation between the microstrain and the hardness was found after heat treatments and cold work. A comparable correlation was found between the microstrain in the supersaturated α-uranium phase quenched from the γ region, and the concentration of the alloying elements. The measured microstrain in the supersaturated α-uranium phase was used as a quantitative value for determination of the solubility limit of Ta and W in γ-uranium. As a result of this study it was found that the limit of solubility is approximately 2.6 and 2.0 at. % for Ta and W, respectively.

As part of a study by high-resolution X-ray diffraction of chrome ores from the Great Dyke, Zimbabwe, powder data are reported for a well-crystallized ferroan magnesiochromite spinel, in which some Cr had been replaced by Al. Data were obtained by using CuKα1 radiation, with an incident beam focusing monochromator to eliminate the Kα2 component. The cell parameter is a0=8.3123(2) Å, the figures of merit are M17=383 and F17=182 (0.0055, 17) and the calculated density is 4.50(5) Mgm−3. A small amount of sample broadening was observed and this was attributed to a mean crystallite size of 259(1) nm. © 1997 International Center for Diffraction Data.

An experimental investigation has been carried out to determine the extent to which axial divergence in a conventional powder diffractometer influences the measurement of peak profile parameters. A Siemens D5000 θ–2θ diffractometer was used for this study along with the LaB6 line profile standard SRM 660. Eight unique levels of axial divergence were investigated either by removing one or more of the Soller slits, or by introducing different combinations of Soller slits in the incident and diffracted beams. The measure of axial divergence used throughout is based on the maximum axial divergences of the incident and diffracted beams, Ψi and Ψd. Axial divergence produces a small and almost constant shift δ2θp in the peak angle which in a typical diffractometer would amount to a zero offset 2θ≈0.005°. The integrated intensity of a profile increases almost linearly with the product Ψi*Ψd. The increase in breadth in profiles in the angular region 2θ<120° arises mainly from the change in asymmetry DH=Hlo−Hhi in which one side of the profile broadens (i.e., either the high angle or low angle side) without any significant broadening of the other side. Moreover, the asymmetry DH is linearly dependent on 2θ for a fixed level of axial divergence, and linearly dependent on the total axial divergence Ψi+Ψd at fixed 2θ.

Cu2Th4(MoO4)9 is cubic: a=14.4856(1) Å, space group I4¯3d, Z=4. Its crystal structure was recently determined using a single crystal. The results of chemical study allow one to reject the existence of Li4Th7(MO4)16 and La(MO4)(ReO4) compounds with M=Mo, W, reported as isostructural with Cu2Th4(MoO4)9. Precise X-ray powder patterns are established for Cu2Th4(MoO4)9 and isotypic compounds Li2Th4(MoO4)9, Li2Th4(WO4)9, and La4(MoO4)3(ReO4)6.

Sm2Bi2Ti3O12 was synthesized by solid state reaction from Sm2O3, Bi2O3, and TiO2 in molar relation 1:1:3. Title compound is isostructural with Bi4Ti3O12. Products of the reaction were analyzed by X-ray diffraction methods. The crystal structure was refinement by the Rietveld Method. Cell parameters are: a=5.368(2), b=5.369(2), and c=32.71(2) Å, space group Fmmm. The final R value was 9.96% (Rw=13.43%).© 1998 International Center for Diffraction Data.