New crystal data for the intermetallic sigma phase in the Mo-Ru-system are reported and the indexing of the pattern given in the Powder Diffraction File has been extended. The material is tetragonal, P42/mnm (No. 136) with a = 9.5652(4) Å; c = 4.9362(3) Å; Vol = 451.63(7) Å3, Dc = 10.79 Mg m−3 for the composition Mo.63Ru.37, and a = 9.5569(21) Å; c = 4.9418(20) Å; Vol = 451.35(38) Å3, Dc = 10.75 Mg m−3 for Mo.70Ru.30.

Powder data were obtained by the Guinier method and the indexing was corroborated by single crystal data. Transition to the superconducting state took place in the interval 6.8 K – 8.8 K.

In the Bragg-Brentano X-ray powder diffractometer geometry the Automatic Divergence Slit (ADS) provides a fixed area of illumination on a flat specimen. For this case, the “constant volume” diffraction, appropriate for a Constant Divergence Slit (CDS) diffractometer, is not applicable and intensities must be corrected by a sinθ factor before comparison to CDS data.

It is shown that for thin layers the diffraction pattern may be treated as a “constant volume” diffraction case when the ADS is used. Moreover, the derivation of the unit cell dimensions using a common least-square procedure can result in excellent lattice parameters without using internal standards, because the transparency aberrations are minimized.

ADS data were obtained for a variety of reference materials including several NBS SRM powders. It was found that thin samples made of powder mixed with vaseline gave “constant volume” diffraction, less angular aberration, and yet had line intensities only somewhat less than bulk samples.

Three main benefits arise using a combination of thin layers and ADS: (a) The amount of material needed for routine chracterization is small, (b) The relative experimental intensities are approximately the same as those obtained from bulk specimens using a CDS. (c) The measured (Bragg) scattering angles are more accurate compared with those measured from bulk specimens.

The ε-phase is hexagonal, space group P63/mmc. For the composition Pb7Bi3 the following data were determined, a = 3.5058(1) Å c = 5.7959(5) Å, Vol. = 61.687 Å3(5), Dc = 11.17 Mg m−3. Filings from single crystal material were used to obtain powder data by the Guinier method and the X-ray results were in accordance with single crystal neutron diffraction data. Transition to the superconducting state took place in the interval 8.3 K–8.55 K.

Based on high purity constituents ternary AlFeSi intermetallic phases were prepared and annealed at 600°C for a month with compositions close to that of αH-AlFeSi (Al8Fe2Si) phase (∼8 wt.% Si, ∼32 wt.% Fe). The powder diffraction patterns and the chemical compositions of the different αH-AlFeSi intermetallic compounds formed as major components in the samples were investigated by X-ray powder diffraction and electron microprobe analysis, respectively.

A complete powder diffraction pattern is presented for the αH-AlFeSi intermetallic phase with 8 wt.% silicon and 33.5 wt.% iron content formed almost congruently. The refined cell parameters are given as

a = 12.4056 (7) Å

c = 26.236 (2) Å

Comparing the observed intensities with intensities calculated from single crystal data, gave very good agreement.

The lattice parameters of αH-AlFeSi phases with different silicon content were refined by the least-squares method. A contraction of the unit cell caused by the increase of the silicon content in the phase can be observed. Relative changes of the cell dimensions for 1 wt. % increase in silicon are −0.06%, −0.09 % and −0.21 % for the parameters a and c and for the unit cell volume, V, respectively.

Using a standard laboratory X-ray powder diffractometer under very stable environmental conditions, it has been found that measurements of the positions and heights of sharp diffraction maxima can be made with a precision of order 2 × 10 −4° in 2θ and 0.1% in height (for ∼ 2 × 105 counts per point at the peak). Under normal conditions, however, displacements of order 0.02° in 2θ and 3% in height are observed. These shifts have been attributed to changes in the diffraction geometry, in particular the sourcedivergence slit configuration, brought about by changes in ambient temperature and by changes in the temperature of the liquid used to cool the X-ray tube.

Indexed powder diffraction data for Lu(OH)3 are reported. The compound is cubic, Im3(No. 204), with a = 8.2221(3)Å, V = 555.84Å3, Z = 8, Dm = 5.36(4)Mg m−3 (Dx = 5.40Mg m−3). The refined cell parameter was determined by employing a Siemens Debye-Scherrer camera (Cu radiation, Ni filter). The indexed data were evaluated according to the quantitative figures of merit FN and M20 (F29 = 20(0.028,51) and M20 = 43.5). A thermal gravimetric analysis is presented. The JCPD S Diffraction File No. for Lu(OH)3 is 38–1500.

Tabular untwinned crystals of colorless transparent armstrongite from the Strange Lake Alkalic Complex, on the Quebec – Labrador boundary, Canada are monoclinic, space group choices I2/m, I2, Im (diffraction aspect I*/*), with refined unit-cell parameters a = 13.599 (9), b = 14.114(9), c = 7.833 (4) Å, β = 103.41 (5)°, V = 1462.4 (±3.0) Å3. a:b:c = 0.9635:1:0.5550, Z = 4 and D(x) = 2.696 g/cm3. A fully indexed X-ray powder pattern is presented. Averaged electron-microprobe analyses suggest a theoretical formula of CaZrSi6O15 · 3 H2O. The Strange Lake armstrongite is biaxial negative, α = 1.567 (1), β = 1.576 (1), γ = 1.577 (1), 2V (meas.) = 39 (1)°, 2V (calc.) = 37°, Z∥b, X Λc = +4°, with no absorption and weak dispersion r < v.

The structure of a birefringent andradite–grossular sample was refined using single-crystal X-ray diffraction (SCD) and synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Electron-microprobe results indicate a homogeneous composition of {Ca2.88Mn2+ 0.06Mg0.04Fe2+ 0.03}Σ3[Fe3+ 1.29Al0.49Ti4+ 0.17Fe2+ 0.06] Σ2(Si2.89Al0.11) Σ3O12. The Rietveld refinement reduced χ 2 = 1.384 and overall R (F 2) = 0.0315. The HRPXRD data show that the sample contains three phases. For phase-1, the weight %, unit-cell parameter (Å), distances (Å), and site occupancy factor (sof) are 62.85(7)%, a = 12.000 06(2), average <Ca–O> = 2.4196, Fe–O = 1.9882(5), Si–O = 1.6542(6) Å, Ca(sof) = 0.970(2), Fe(sof) = 0.763(1), and Si(sof) = 0.954(2). The corresponding data for phase-2 are 19.14(9)%, a = 12.049 51(2), average <Ca–O> = 2.427, Fe–O = 1.999(1), Si–O = 1.665(1) Å, Ca(sof) = 0.928(4), Fe(sof) = 0.825(3), and Si(sof) = 0.964(4). The corresponding data for phase-3 are 18.01(9)%, a = 12.019 68(3), average <Ca–O> = 2.424, Fe–O = 1.992(2), Si–O = 1.658(2) Å, Ca(sof) = 0.896(5), Fe(sof) = 0.754(4), and Si(sof) = 0.936(5). The fine-scale coexistence of the three phases causes strain that arises from the unit-cell and bond distances differences, and gives rise to strain-induced birefringence. The results from the SCD are similar to the dominant phase-1 obtained by the HRPXRD, but the SCD misses the minor phases.

Two molybdates MIV (MoO4)2 (with MIV = Hf or Zr) were synthesized by solid state reaction between MIVO2 and MoO3. Zirconium molybdate undergoes a reversible phase transition at 952 K.

Hf(MoO4)2 and H.T. Zr(MoQ4)2, obtained as single crystals, are trigonal, space group with Z = 6; the cell dimensions are respectively a = 10.1005(3), c = 11.7230(5)Å; V = 1035.76(11)Å3; Dm(298 K) = 4.78(4), Dx = 4.792 Mg m−3 and a = 10.1409(3), c = 11.7097(5)Å; V = 1042.88(11)Å3; Dm (298 K) = 3.91(4), Dx = 3.926 Mg m−3.

L.T. Zr(MoO4)2, indexed by the Visser automatic indexing program (1969) was found to be monoclinic, possible space group P2, P21 or Pm with Z = 4; the cell dimensions are a = 9.7557(5), b = 7.9373(5), c = 7.4631(4)Å, β = 97.959°(5); V = 572.3(5)Å Dm(298 K) = 4.74(5), Dx = 4.770 Mg m−3. Powder diffraction data were obtained at 293 K on a counter diffractometer with Ni-filtered copper radiation ( = 1.5418 Å).