X-ray powder diffraction data, unit cell parameters and chemical data published previously for kutnohorite, the manganese-rich double carbonate mineral, are critically evaluated and compared with new measurements on a specimen from Chvaletice, Czechoslovakia with a composition Ca (Mn0.64Mg0.23Fe0.13)(CO3)2. Data were collected with a computer controlled diffractometer and analysed with profile analysis techniques. The new powder diffraction data set yields much better data and unit cell parameters than the earlier ones given for kutnohorite on PDF 11-345 (Powder Diffraction File, 1987). A least-squares evaluation resulted in ao = 4.8518(3)Å and co = 16.217(2)Å.

The following fourteen reference patterns of boride, telluride, and oxide ceramics are reported. Included in the fourteen reference patterns are data for six high Tc superconducting oxide and related phases (Ba2CaCu2TI2O8, BaCuEu2O5, BaCuTm2O5, BaCuDy2O5, Ba3.2Cu1.7Y0.8O6.1·xCO2, Sr2Bi2O5). The general methods of producing these X-ray powder diffraction reference patterns are described in this journal, Vol. 1, No. 1, pg. 40 (1986).

Samples were mixed with one or two internal standards: silicon (SRM640a), silver, tungsten, or fluorophlogopite (SRM675). Expected 2θ values for these internal standards are specified in the methods described (ibid.). Data were measured with a computer controlled step-scanning diffractometer. The POWDER-PATTERN system of computer programs was used to locate peak positions, to calibrate the patterns, and to perform variable indexing and least-squares cell refinement. A check on the overall internal consistency of the data was also provided by a computer method.

Intensities were measured as peak heights above background and were read manually from strip charts. To minimize preferred orientation effects, the powders were passed through a 400 mesh sieve and were mixed with an amorphous diluent, silica gel. Sample mounts were prepared by side-drifting and/or by dusting a thin layer of sample on a glass slide coated with a thin smear of silicone grease.

A discrepancy was discovered between an experimental X-ray diffraction pattern of sodium acetate trihydrate collected with the Gandolfi camera and a calculated pattern based on a single crystal study of the same compound. The experimental d spacings matched those of the calculated pattern with the exception of the strongest reflection d = 3.002 Å (h k l = 40 − 2) which was missing in the experimental pattern. Another experimental Gandolfi pattern obtained from a powdered sample of sodium acetate trihydrate gave excellent agreement with the calculated d spacings and intensities.

The results of our investigation into this discrepancy show that the angle θ, crystal alignment, camera diameter, and the crystal system can affect diffraction in the Gandolfi camera. It is shown that all reciprocal lattice points with θ angles less then 10.08° would diffract in the film plane of the 114.6 mm Gandolfi camera and points with θ angles less then 20.49° would diffract in the film plane for the 57.3 mm camera regardless of the crystal system or alignment. However, reciprocal lattice points aligned along the spindle axis of the 114.6 mm Gandolfi camera having reciprocal lattice points with Z ≥ 0.35 reciprocal lattice units (r.l.u.) and X and Y ≤ Z-0.35 r.l.u. will not diffract into the recording plane of the Gandolfi camera. The reciprocal lattice points aligned along the spindle axis of the 57.3 mm Gandolfi camera with Z ≥ 0.70 r.l.u. and X and Y ≤ Z-0.70 r.l.u. will not diffract into the recording plane of the camera.

The X-ray powder pattern of a partially combusted coal product has been separated into its diffraction component (caused by die crystalline minerals present in the sample) and its amorphous scattering component which is due to the fixed carbon retained in the sample. Analysis of the atompair intensity of the amorphous scattering component indicates that the molecular scatterer(s) in the fixed carbon fraction are similar, at least in short range structural details, to those in an amorphous carbon black sample which was prepared by high temperature combustion of polynuclear aromatic materials.

An expanded X-ray quantitative phase analysis method is presented. It is an extension of the method without standards. In order to get the method applied more extensively, there is a discussion at the end of this paper of the suitability of samples.

X-ray powder diffraction data show that the highest temperature solid phase of C4F8 has an orientationally disordered body-centered cubic structure, a = 7.06(3)Å, with two molecules per cell.