X-ray powder diffraction data for [Ni(i-prxa)2(bpy)] (1), [Ni(i-prxa)2(phen)] (2), and [Ni(i-prxa)2(tmen)] (3), where i-pr=i-C3H7, xa=S2CO−, bpy=2,2′-bipyridine, phen=1,10-phenanthroline and tmen=N, N, N′, N′-tetramethylethylenediamine, are reported. For (1): Monoclinic, P21/n, a=10.8255(1) Å, b=12.7423(1) Å, c=15.9796(1) Å, β=92.037(3)°, V=2202.9(1) Å3, Z=4, Mr=485.3, T=296 K, DX=1.463 g/cm3, Dexp=1.47 g/cm3, CuKα1=1.540 51 Å, 63 lines. For (2): Monoclinic, P21/n, a=10.7591(1) Å, b=12.8115(2) Å, c=16.1162(3) Å, β=92.39(1)°, V=2219.5(2) Å3, Z=4, Mr=509.4, T=296 K, DX=1.525 g/cm3, Dexp=1.51 g/cm3, CuKα1=1.540 51 Å, 72 lines. For (3): Orthorhombic, P212121, a=9.341(4) Å, b=15.093(8) Å, c=15.990(7) Å, V=2254(2) Å3, Z=4, Mr=445.35, T=296 K, DX=1.312 g/cm3, Dexp=1.32 g/cm3, CuKα1=1.540 51 Å, 49 lines.

X-ray powder-diffraction data were collected for a new iron phosphate, Fe(PO4)·0.5H2O, obtained by reducing FePO4 with oxalic acid at 220 °C in the presence of water vapor and oxygen. The crystal system was determined to be orthorhombic with unit-cell parameters a=15.991(6) Å, b=20.156(7) Å, and c=7.223(2) Å.

The results of computer simulations of the absorption of diffracted X-rays in single-phase powders measured at cylindrical (or Debye–Scherrer capillary) geometry taking into consideration the size of the powder particles are presented. The samples are simulated by random dense packings of equal spheres. The calculations are carried out for different values of the ratio, Da, of particle size to cylinder diameter, the product, κ, of linear absorption coefficient and cylinder radius and the scattering angle 2θ. Strong deviations of the absorption factor from the values for the ideal case of very fine particles are found in the region 0≤2θ≤30°, and for medium and high values of κ,(κ≥5) and Da (Da≥0.002). The consequences for the experiment are discussed.

Two derivatives of 4-chloro-2,2′-iminodibenzoic acid: diethyl 4-chloro-2,2′-iminodibenzoate, C18H18ClNO4, and dimethyl 4-chloro-2,2′-iminodibenzoate C16H14ClNO4, have been investigated by means of X-ray powder diffraction. The unit cell dimensions were determined from diffractometer methods, using monochromatic CuKα1 radiation, and evaluated by indexing programs. The monoclinic cell found for diethyl 4-chloro-2,2′-iminodibenzoate was a=21.332(3) Å, b=7.889(2) Å, c=10.156(2) Å, β=91.43(1)°, Z=4, space group P2 (No. 3), Pm (No. 6), or P2/m (No. 10), Dx=1.351 mg/m3. The cell found for this compound is in good agreement with the one obtained from single crystal X-ray diffractometry. The monoclinic cell found for dimethyl 4-chloro-2,2′-iminodibenzoate has the dimensions a=15.962(2) Å, b=5.151(2) Å, c=12.590(2) Å, β=98.35(1)°. Z=4, space group P2 (No. 3), Pm (No. 6), or P2/m (No. 10), Dx=2.073 mg/m3.

The crystal structure of Ba4Ti10Al2O27 has been refined in a joint Rietveld refinement using neutron and X-ray powder data. The compound crystallizes in the monoclinic space group C2/m, with a=19.7057(3), b=11.3575(2), c=9.8318(2) Å, β=109.218(1)°, and V=2077.81(5) Å3. It is isostructural to Ba4Ti10Fe2O27 and Ba4Ti11ZnO27, and consists of a complex network of corner- and edge-sharing Ti/Al octahedra. The structure can best be described based on close-packed O/Ba-O layers in an 8-layer (8L) chhcchhc sequence. Out of a total of ten Ti/Al sites, Al was found to substitute for Ti mainly in four sites, and the remaining six sites were predominantly occupied by Ti. The unit cell contents derived from the refined site occupancies are Ba16Ti40.48Al7.52O108, essentially identical to the expected Ba16Ti40Al8O108. A reference diffraction pattern of this phase is also reported.

Estimation of reference intensity ratios (ki or RIR) can be made on the basis of an atomic scattering function. Tests of regression equations for 50 compounds that predict an approximate reference intensity ratio from the easily computed scattering function have shown usefulness in multicomponent semiquantitative X-ray diffraction analysis. The method is best applied whenever only one or two minor components of a multicomponent sample have no readily measurable or calculable ki values and must be estimated. Where the difference between observed and predicted constants is large, these tests show that the ratios of true- to test-weight fractions are proportional to the corresponding ki ratios. The largest absolute errors occur whenever the ki must be predicted for components with medium weight fraction values. Estimation of ki for components of less than 10 weight percent results in only small errors in both predicted component and the other components of the sample. Where more than two components require predicted ki in a given sample, unacceptable errors for all components may result.