X-ray powder diffraction data and refined unit cell parameters for three compounds found during experimental determination of the BaO:Fe2O3:TiO2 phase diagram are reported here. All three phases crystallize in space group C2/m (No. 12). Ba2Fe2Ti4O13 (“2:1:4”) is isostructural with K2Ti6O13 and Ba2ZnTi5O13: a=15.1939(9), b=3.8912(3), c=9.1244(5) Å, β=98.456(5)°; Z=2, ρcalc=4.890 g/cc. Ba3Fe10TiO20 (“3:5:1”) is structurally analogous to its aluminum congener Ba3Al10TiO20: a=15.336(1), b=11.7986(9), c=5.1700(4) Å, β=91.220(6)° (I2/m setting); Z=2, ρcalc=4.750 g/cc. Ba4Fe2Ti10O27 (“4:1:10”) is also isostructural with its aluminum analog Ba4Al2Ti10O27: a=19.799(1), b=11.4324(6), c=9.8936(6) Å, β=109.146(4)° (C2/m); Z=4, ρcalc=4.934 g/cc. The 2:1:4 and 3:5:1 compounds adopt open-framework type structures while the 4:1:10 phase exhibits an eight-layer close-packed arrangement.

Described is an improved Gandolfi camera which overcomes the disadvantages of the adjustment procedure of the conventional instrument. The basic principle of the new construction is the introduction into a camera of a complete goniometer head as sample holder with two 45° rotation axes. Particular advantages of the modified Gandolfi camera are a simple and time saving centering technique as well as convenient combination possibilities of powder and single crystal investigations.

My students and I have developed a LOTUS 1-2-3 spreadsheet to aid in data reduction tasks associated with preparing powder diffraction data for publication in the Powder Diffraction File (PDF) (1987) and this journal. Portions of a sample spreadsheet and the formulae in each of the computational cells are given in the Table 1. The concept of this spreadsheet should apply to any of the available computer spreadsheet programs, although the specific codes for the mathematical functions may differ.

The user enters data only into columns C, D and F-H. All other entries will be calculated from the input data. Observed 2θ angles are entered into column D. The corresponding d-spacing is calculated in column A. The Miller indices of these peaks are entered into column C. Prior to use of the spreadsheet, the observed 2θ angles and hkl's had been used to refine unit cell parameters using the Appleman and Evans (1973) least squares unit cell parameter refinement computer program implemented for the IBM PC by Garvey (1986).

X-ray diffraction quantitative phase analysis is a technique widely used in materials science and engineering research. The method proposed by Zevin [L. S. Zevin, J. Appl. Cryst. 10, 147 (1977)] has proven very useful in practice because standards or pure crystalline phases are not needed, but, Zevin only described the case of n samples, each of which contain different concentrations of the same n phases. An extension of this method, in which the reference samples could contain less phases than the analyzed sample is proposed in this paper. The absence of phases in reference samples is not arbitrary but depends on certain conditions. The conditions required to solve the equations are discussed in detail using the concepts of the set theory, and the results of confirmation experiments agree well with the theory.

An organic nonlinear optical material, 3-methyl-4-methoxy-4′-nitrostilbene (C16H15NO3), has been characterized by X-ray powder diffraction. Experimental values of 2θ corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 77 observed reflections with 2θ up to 82° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The unit cell parameters least-squares refined from 30 non-overlapping peaks of the orthorhombic compound with a Aba2 space group are a=15.7882(3) Å, b=13.4892(4) Å, c=13.3940(2) Å, V=2852.5(4) Å3, Z=8, Dx=1.254 g/cm3. The powder diffraction results are in a agreement with those obtained from single-crystal structure data.

X-ray powder diffraction data for Ti2O2(C2O4)(OH)2·H2O were obtained. The crystal system was determined to be orthorhombic with space group C2221. The unit cell parameters were refined to a = 1.0503(2) nm, b = 1.5509(3) nm, and c = 0.9700(1) nm.

A computer program is presented that allows for the analysis of powder X-ray diffraction (XRD) patterns. Some peculiar features of the program are: the aptitude for dealing with diffractograms obtained from semicrystalline polymer samples and the ability to evaluate XRD patterns collected with CPS 120 detectors. The program is available as freeware via anonymous ftp at: ftp.cc.uniud.it under the directory/pulwin/.

A task group of the JCPDS—International Center for Diffraction Data (ICDD) was established with the charge of investigating the use of silver behenate, CH3(CH2)20COO·Ag, as a possible low-angle calibration standard for powder diffraction applications. Utilizing several data collection and analysis techniques, long-period spacing (d001) values with a range of 58.219–58.480 Å were obtained. Using the same collected data and one data analysis refinement calculation method resulted in dm values with a range of 58.303–58.425 Å. Data collected using a silicon internal standard and the same singular data analysis calculation method provided d001 values with a range of 58.363–58.381 Å.

A wide range of transition metal oxide solid solutions have been prepared and characterised using powder X-ray diffraction (MnxCo1−xFe2O4, FexCo1−xFe2O4, NixCo1−xFe2O4, FeFexCr2−xO4, MnFexCr2−xO4, MnxFe1−xCr2O4, MnxFe1−xFe2O4, NixFe1−xFe2O4). Calibration curves have been obtained relating oxide composition to unit cell parameter or d spacing. From these curves it is possible to identify the composition of oxides formed on steel surfaces in varied industrial environments. Even when poor diffraction patterns are obtained and little sample is available, an estimate of composition can be made.

The X-ray powder diffraction pattern of hydrated lithium monoborate LiB(OH)4, sometimes formulated LiBO2·2H2O, has been obtained. Refinements of indexed reflections yielded the following parameters: a = 9.1732(7)Å, b = 7.9622(6)Å, c = 8.5354(8)Å, space group Pbca, Z = 8, Dx = 1.827, Dm = 1.83 g/cm3. The Smith–Snyder figure-of-merit is F30 = 101(0.007,44).