A new and improved sample holder for use with powder X-ray diffractometry has been developed. This holder is made from a semiconductor grade silicon single crystal cut perpendicular to the [911] axis, i.e., Si (911). This crystal meets most of the basic requirements of an ideal zero background plate, with practically no interference lines. The pattern obtained, by using this crystal as background plate, is very clean, and even very low-intensity Bragg reflections of samples can be detected easily.

X-ray powder diffraction data are reported for the [(NH4)3Al1−xFex/2Crx/2(C2O4)3]·3H2O solid solution. The crystal system is triclinic with space group P1. Refined unit-cell parameters are given for the compositions x=0.10, 0.50 and 0.80.

Lobenzarit acid, C14H10ClNO4, and lobenzarit disodium (CCA), C14H8ClNNa2O4, have been investigated by means of X-ray powder diffraction. The unit cell dimensions were determined from diffractometer methods, using strictly monochromatized CuKα1 radiation, and evaluated by indexing programs. The triclinic cell found for lobenzarit acid was a=16.580(1) Å, b=16.389(1) Å, c=4.9023(3) Å, α=71.674(6)°, β=92.609(6)°, γ=97.127(6)°, Z=4, Dx=1.544 Mg/m3. The triclinic cell found for CCA was a=18.041(5) Å, b=11.461(4) Å, c=5.936(2) Å, α=66.80(3)°, β=103.61(3)°, γ=113.13(3)°, Z=4, Dx=2.159 Mg/m3.

Powder X-ray diffraction was used to investigate the solid solution range of the Bi14SrxCa12−xO33 series in the Bi–Sr–Ca–O system. Solid solution forms over the range 1≤x≤7 in Bi14SrxCa12−xO33. Experimental X-ray reference patterns of selected members with x=1, 3, 5, and 7 have been prepared for the powder diffraction file (PDF). These phases are monoclinic, C2/m, with cell parameter a ranging from 21.473(4) to 21.868(4) Å, b from 4.3564(9) to 4.3898(9) Å, c from 12.753(2) to 12.962(2) Å, β from 102.91(2)° to 102.79(1)°, and V from 1162.9(3) to 1213.5(3) Å3, respectively. These parameters increase monotonically as Ca is continuously replaced by the larger Sr.

Precision X-ray powder-diffraction data of pure solid C70 is reported. C70 prepared by slow evaporation of C70-in-toluene solution adopts an hcp structure (space group P63/mmc) with lattice parameters a=10.5934(10)Å and c=17.262(2)Å.

Thulium (Tm) doped barium yttrium ytterbium fluoride (BaYYbF8:Tm) thin films have been deposited on (100) silicon (Si) or (100) and (111) gallium arsenide (GaAs) substrates. When deposited on (100) Si, with an intermediate amorphous silicon dioxide (SiO2) layer, the BaYYbF8:Tm film was found to be polycrystalline, crystallizing in a previously unobserved cubic phase with a lattice constant a = 11.4208 (9) Å . Films deposited on GaAs, with an intermediate calcium fluoride (CaF2) layer, showed a high degree of planar orientation. Pole figure analysis revealed that the BaYYbF8:Tm films deposited on CaF2/GaAs are in-plane aligned dependent upon the substrate orientation.

Plane analytical geometry has been used to derive formulas of peak shifts due to specimen geometry and beam divergence of X-ray diffractometers in a Seemann–Bohlin configuration. When the attenuated diffraction below the specimen surface is not considered, peak shifts depend on Bragg angle (θ), incident beam divergence (2α), curvature radius of the specimen surface (r), and the tilt angle of the specimen (ψ). Numerical results show that at any fixed Bragg angle value, the peak shift increases with 2α whatever the combination of r and ψ values are. Moreover, at any fixed value of both Bragg angle and beam divergence, the peak shift depends directly on |ψ| and inversely on |r|. Shifts of peaks have been compared on both goniometer circle (Δ2θS) and focusing circle (Δ2θP). The results show that when ψ>0, then (Δ2θS) is less than (Δ2θP). On the contrary, when ψ<0, then (Δ2θS) is greater than (Δ2θP). Both (Δ2θS) and (Δ2θP) increase when the Bragg angle is decreased under the same fixed set of ψ, 2α, and r values. These peak shifts are so high that lattice strains may be masked at either high values of |ψ| and 2α, or small |r| values.

Rietveld analysis has been successfully used to characterize plasma-sprayed PSZ coatings in a study of the structural stability of 8 wt. % Y2O3–ZrO2 powders and 23 wt. % CeO2/3 wt. % Y2O3–ZrO2, sprayed onto steel substrates. The ceramics were examined in powder form prior to spraying, as-sprayed and after a series of high-temperature soaks at temperatures relevant to those found in heat engines. The study showed that the Y2O3–ZrO2 powders consist of mixtures of the cubic (as the minor phase) and tetragonal (major phase) zirconia and the cubic zirconia polymorph, whereas the as-sprayed materials contain only the tetragonal (major phase) and monoclinic polymorphs indicating that the cubic phase has been lost by transformation. The CeO2–ZrO2 powders consist of a mixture of cubic, tetragonal (major), and monoclinic polymorphs of which the monoclinic phase disappears after plasma spraying. After extended thermal cycling, the Y2O3–ZrO2 coatings did not alter in phase composition whereas the CeO2–ZrO2 coatings became entirely tetragonal.

X-ray powder-diffraction data for Pb2(C2O4)(NO3)2·2H2O were obtained. The crystal system was determined to be monoclinic. The unit-cell parameters were refined to a=10.613(2) Å, b=7.947(2) Å, c=6.189(1) Å, and β=104.48(2)°.

Error quantities, defined earlier to estimate the accuracy of texture measurement, are used to define a probability criterion for correct indexing of powder diffraction diagrams. The criterion is based on the compatibility of pole density distribution functions of different (hkl) depending on the directions {θ,γ}(hkl) of the reciprocal lattice vectors r*(hkl). The criterion was applied to permutation of the indices and variation of the angles {θ,γ}(hkl) in the vicinity of the correct values. In fortunate case, these angles can be determined within a few degrees by minimizing the error quantities. The method works very well with strong textures but it is still applicable if only weak textures can be achieved. The method was tested with different crystal symmetries including cubic, hexagonal, orthorhombic, and monoclinic. It is concluded that the criterion can be successfully applied to all crystal symmetries. If a measuring technique based on a position sensitive detector is used, even multifold peak superpositions in tilted sample orientations can be resolved. The method can also be applied if some (hkl) cannot be separated experimentally.

The ternary phase diagram of the system Bi2O3-CdO-GeO2 was investigated in several isothermal sections using predominantly X-ray powder diffraction. The following phases are described with respect to their crystal chemistry, phase relations and powder patterns: Bi2−2xCd2x(O3−x⍽9+x) (solid solution with anti-α-AgI structure), CdGeO3 (complicated polymorphism), Bi12GeO20 (stoichiometric sillenite), Cd-sillenite (solid solution), Bi1.8Cd0.2GeO4.9 (metastable, new phase, new structure type with GeO5 polyhedra), Bi2CdGeO6 (new ternary oxide, new structure type).

Two compounds of the elpasolite family (A2BLnX6), Cs2KTbCl6 and Cs2KEuCl6, were obtained {by evaporating to dryness a hot aqueous HCl solution of the appropriate chlorides [Morss etal., Inorg. Chem. 9, 1771 (1970)]} and characterized by powder X-ray diffraction. Title compounds are isostructural with cubic Rb2NaTmCl6 and correspond to the perovskite related structure with space group Fm3m, cell parameters 11.1294(6) and 11.1618(4) Å, V=1378.5(2), and V=1390.5(1) Å3, respectively.

The powder diffraction pattern of the new lead-based relaxor material Pb0.95Mg0.26Nb0.60Zr0.03O2.78 is described. The compound has a unit cell of a=4.0508(1) Å. The space group of the material is most probably Pm3m, with Z=1 and Dx=7.657 g/cm3.

Particle statistics in quantitative X-ray diffractometry relates to the number of particles (crystallites) contributing to the diffracted intensity for a given line. Variations in line intensity between replicate preparations of the same sample arise from statistical variations in the number of diffracting particles. The uncertainty in line intensity, and hence in quantitative estimates of analyte concentration, is termed the particle statistics error. A theoretical estimate of the error for stationary samples qives σPS=ξ[μ*〈v〉/c]1/2, where μ* is the mass absorption coefficient of the mixture, and 〈v〉 and c are the mean particle volume and mass concentration respectively of the analyte. The factor ξ is a function mainly of diffractometer geometry, but also contains contributions from rocking angle and reflection multiplicity. For measurements of the (112) quartz line with a Philips PW1050 vertical goniometer with 2o divergence slit and 0.3 mm receiving slit, ξ was calculated to be 116 g1/2 cm−5/2 for stationary samples. Three close-cut size fractions of quartz were prepared at various concentrations in a calcium carbonate matrix. Replicate preparations were measured and the standard deviation obtained as a function of particle volume and concentration. After correction for other contributing errors, including counting statistics and thermal fluctuations, the experimental value ξ=122±10 g1/2 cm−5/2 was obtained. The effect of sample spinning is considered briefly and predicted to reduce σPS by a factor of about 5. Experimentally, a reduction in σPS of about this order is observed, but the effect is rather variable.

A new phase in the system BaO–MnO–SiO2 obtained by a pyrosynthetic method has been inves- tigated using electron microprobe analysis (EPMA), X-ray powder diffraction (PDA), and trans- mission electron diffraction. The lattice parameters and possible space group of the phase with a general composition BaMnSi2O6 were determined as follows: a=13.896, b=12.261, c=10.781 Å, β=103.47°, space group P21/m, Z=12.

Calculated patterns for the BaR2PdO5 series, in which X is Pd and R=Nd, Sm, Eu, or Gd, have been prepared for materials characterization until experimental patterns can be determined. These compounds are isostructural to the superconductor related “brown phases” BaLa2CuO5 and BaNd2CuO5, which are tetragonal with space group P4/mbm, Z=4. The cell parameters of the Eu and Gd compounds were derived from the La and Nd analogs. The calculated patterns of these four compounds compared well to an experimental pattern of BaNd2CuO5.