A deformed aluminum-copper alloy was studied by X-ray diffraction. The 111 diffraction profile was found to consist of a main peak and a subpeak. They were separated by a numerical differential method combined with a non-linear least square profile fitting procedure. The subpeak could not be ascribed to the θ phase in the alloy since the intensity ratio of the subpeak to main peak is 20-30 times more than the volume ratio of the θ phase to die matrix. On the other hand, the Transmission Electron Microscope (TEM) micrographs showed clearly that there is a highly inhomogeneous dislocation distribution just like the cell structure in pure aluminum. The main X-ray peak was thus assumed to be due to diffraction from the cell interior while the subpeak is determined by the cell wall. After applying a series of standard data processing procedures based on Wilkens' theory and the Pearson VII-Voigt function, the dislocation densities in both the cell interior and wall were evaluated.

The X-Ray Powder Data File (XRPDF) enables one to identify the compounds in a sample. More often than not, however, a semi-quantitative analysis is wanted. Visual inspection of the pattern may give a vague impression of the composition, but the errors of such a result are usually not within reasonable limits. Clearly a less subjective and more accurate method is wanted. If the necessary data are printed on the cards, such a method will greatly enlarge the usefulness of the File.

Results are given of an assessment of a Rietveld-type X-ray powder diffraction pattern fitting structure refinement technique for assaying powdered mixtures as an alternative to conventional discrete peak empirical methods of the type described by Klug and Alexander (1974) and Chung (1974). The values obtained for a mixture of corundum and α-quartz, following calibration of the instrument with a profile of the former, indicate that this technique has excellent potential as an analytical tool.

The Reference Intensity Ratio (RIR) is a general, instrument-independent constant for use in quantitative phase analysis by the X-ray powder diffraction internal standard method. When the reference standard is corundum, RIR is known as I/Ic; These constants are collected in the Powder Diffraction File (1987), can be calculated, and can be measured. Recommended methods for accurate measurement of RIR constants are presented, and methods of using these constants for quantitative analysis are discussed. The numerous, complex constants in Copeland and Bragg's method introduced to account for superimposed lines can be simply expressed in terms of RIR constants and relative intensities. This formalism also permits introduction of constraints and supplemental equations based on elemental analysis.

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.

A computer program for analysing two-component interstratified structures by two different Fourier transform methods is described. The first method consists of the calculation of the X-ray diffraction intensity function, and in the second one (direct method) the distribution function of interlayer distances is calculated. The programs have been written in compiled GWBASIC for an Olivetti M-24 microcomputer (MS-DOS operating system), and they may also be run on any IBM compatible personal computer. As an example, this program is applied for the analysis of a chlorite-smectite interstratified mineral.

This paper presents the first Table of RIR values for quantitative analysis as a model for regular updates which will appear in future issues. Diffractionists interested in the reference intensity method of quantitative analysis are urged to read the criteria for preparing data to continue this Table and then to submit new data.

A nonlinear optical material 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, (CH3)2NC6H3NO2NHCOCH3, has been characterized by X-ray powder diffractometer method. The experimental 2θ values corrected for systematic errors, the relative intensities, values of dexp and the Miller indices of the 46 peaks observed in the 5° to 51° 2θ range are reported. The powder diffraction data have been evaluated, and the figure of merit is F30 = 36.6 (0.016, 51). The unit cell parameter least-squares refined from 38 non-overlapping peaks of the monoclinic compound with a P21 space group are: a = 4.792(1)Å, b = 13.055(2)Å, c = 8.735(1)Å, β = 94.43(2)°, V = 544.8(1)Å3, Z = 2, and Dx = 1.36 gm/cm3. The powder diffraction results are in a good agreement with those obtained from single-crystal structure data.

The method described in this paper is a strict protocol for X-ray diffraction (XRD) analysis of mineral phases found in soils. Its application is not restricted to soils and is an attempt to standardize XRD sample preparation and analysis. The protocol requires the particle size of the < 2 mm - 0.002 mm fraction be reduced to 0.002 mm before analysis. In die qualitative section, the clay fraction ( < 0.002 mm particle size) is prepared as oriented slides. The suspended clay fraction is saturated with ethylene glycol, K +, and Mg+2; pipeted; air-dried; heat-treated at 110°C, 350°C, and 550°C; and X-rayed at each step in order to properly identify the clay minerals. In the quantitative section, the method employs a matrix-flushing agent, corundum (Al2O3). The corundum acts also as an internal standard, a calibration standard, and a reference standard. The suspended clay fraction is freeze-dried and corundum is added to each sample. Randomly oriented powder mounts are prepared from the < 2 mm - 0.002 mm fraction, and the < 0.002 mm fraction, and X-rayed. A series of reference standards are prepared based on the existing mineralogy, corundum is added, and each mixture is X-rayed. The software integrates the area under specific peaks (chosen for intensity and no overlap) in each sample, calculates the reference intensity ratios (RIRs) and calculates the percentage of each mineral based on the equation of Chung (1974). The attention to detail allows documentation and verification of the results yielding data of known quality.

The Powder Diffraction File of crystallographic data has been converted from printed data cards to a computer database. Extensive testing, review, and editing of the database were completed, the history and first stages of which are presented. Computer programs used to create and analyze the database are described.

An ordered oxygen-deficient tetragonal perovskite compound La1.67Sr0.33Cu205 has been synthesized by solid state reaction. X-ray powder diffraction was used to characterize the material. Unit cell parameters least-squares refined from non-overlapping diffraction peaks are a = 10.8696(9)Å, c = 3.8612(6)Å and V = 456.2(1)Å3. X-ray powder data have been obtained for the experimentally observed peak positions corrected for systematic errors, the relative intensities, values of dexp and the Miller indices of both resolved and overlapping reflections. The experimental diffraction pattern was compared to computer simulated patterns calculated from the neutron crystal structure parameters and the non-oxygen-deficient LaCuO3 compound. The figure of merit is F30 = 33.8 (0.018, 48).

With the explosive growth in the number of highly automated powder diffraction systems, many types of analyses which were previously considered a specialty analysis are now performed on a routine basis. Algorithms have been developed for measuring peak profiles from which crystallite sizes, residual microstrain, and X-ray crystal structure (Rietveld techniques for example) can be determined. However, these techniques require an instrumental peak profile calibration standard to correct the experimental data for instrumental broadening due to the system optics.

Significant problems are encountered when laboratories try to cross-correlate or reproduce published data due to the lack of a common reference material for instrumental calibration. This is particularly distressing in microstrain and crystallite size calculations which can be dramatically affected by a poor choice of standard materials. Microstrain and crystallite size measurement are becoming increasingly important for the characterization of advanced materials and catalysts.

Trigonal CdSb2O6, prepared as a very crystalline powder by solid state reaction of CdO and Sb2O3, is isostructural with PbSb2O6 Space Group (S.G.) P31m (162), with a = 5.2399(2), c = 4.8045(4) Å, Z = 1 and Dc = 6.57 Mg.m−3. For the refinement of structural parameters from X-ray powder diffraction data two different methods have been employed and compared, both leading to very similar results. The refinements converged to RI = 0.025 using 35 intensities in the incremental optimization technique and to RF = 0.038, RW = 0.033 from 161 reflections in the least-squares refinement.

X-ray diffraction and neutron spectra present a peak assembly whose maxima are centered at angles corresponding to Bragg's law.

Analysis of diffracted intensity profiles in each peak can be used to estimate such morphologic characteristics of the samples as preferred orientation (Brindley and Kurtosy, 1961; Martin, 1966); crystallite sizes (Scherrer, 1919; Warren and Averbach, 1950; Wilson, 1962; and Guérin et al., 1986); and crystal shapes (Wilson, 1949). Such analysis can also be used to estimate the determination of residual stress and lattice defects (Warren and Averbach, 1950; Wilson, 1963). In such studies, a detailed analysis of the diffraction distribution is required and consequently adjustment of intensity values must be carried out, as they are affected by systematic errors in the measuring apparatus (for detailed description, see Klug and Alexander, 1974 and Wilson 1967).

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.

The effect of solid emulsifiers, added at the level of 10%, on the lattice parameters of tristearin and trilaurin, has been studied by powder X-ray diffraction method. The presence of sorbitan monostearate and glycerol-l-stearate affects slightly the lattice constant a in tristearin; on the other hand, although sorbitan monostearate causes an increase in a of trilaurin, glycerol-l-stearate does not. The presence of sorbitan monolaurate and glycerol-l-laurate affect a of trilaurin similarly to the long chain emulsifiers.

A correlation between the effect on a and the increase in melting point has been found.

The presence of the emulsifier does not alter drastically the lattice dimensions of the fat. The slight dissimilarity in crystal structure between tristearin and trilaurin is confirmed by the diverse effects of the emulsifiers on the internal structure of the fat.

The fly ash Standard Reference Materials (SRMs) issued by the U.S. National Bureau of Standards have been studied by X-ray powder diffraction (XRD). Based on observations of large diffuse scattering maxima in their X-ray diffractograms, it was evident that all of the ashes had a high glass content. SRM 1633a and 2689, derived from the combustion of bituminous coal, contained different amounts of quartz, mullite, hematite and ferrite spinel (magnetite). SRM 2891, derived from subbituminous coal had quite a different chemical composition and a more complex crystalline phase assemblage, that included these four phases plus anhydrite, tricalcium aluminate, lime, periclase and minor phases. SRM 2690, also derived from subbituminous coal, had only quartz, mullite and ferrite spinel as detectable phases in its diffractogram. Analytical CaO is an important factor in determining the phase assemblage; SRM 2691 had 25.8 wt%, SRM-2690 had 8.0%, and the ash derived from bituminous coals had only 1.6-3.0%. The changing composition of the glass phases in the SRMs is detected in a shift in the position and shape of the diffuse scattering maximum in the diffractograms. Use of an internal intensity standard permitted quantitative comparisons of the relative amounts of crystalline phases among the four fly ash SRMs.

Synthesis and unit cell parameter refinement of 25 ferroelectric compounds with the tungsten bronze structure are reported. A general chemical formula for these compounds is (A1, A2, C) B10 O30, where specifically A1 and A2 = K, Na, Ba, Sr, Pb, La, Eu, Sm, Y, Bi; C = Li; and B = Nb, Ta, Ti, W. All compounds were prepared by solid state sintering at temperatures ranging from 1100°C to 1380°C. Refined cell parameters (tetragonal with space group P4bm[100]), I/Icor values, calculated densities and Z values are included for the 25 compounds.

A quantitative simultaneous determination method by X-ray powder diffractometry is described for calcium sulfate and calcium carbonate in airborne dusts. In order to eliminate the mutual interference among diffraction peaks, and to avoid the presence of the hydration isomers of calcium sulfate, dust samples were heated at 350°C for 2 h. To reduce the errors due to the difference-in crystallinity between the standard materials and the samples, the synthesized calcium sulfate anhydrate (anhydrite) was heated to such an extent that the half-width of the 002,020 peak was identical with that of the anhydrite in pretreated dust samples. Standard calcium carbonate (calcite) was ground until the half-width and the orientation index of the 104 peak of calcite was identical with that of the calcite in dust samples. Linear calibration curves were obtained throughout the range of 0 ∼ 30 wt% for anhydrite and the range of 0 ∼ 10 wt% for calcite, respectively. The determination limits were 0.2 wt% for anhydrite and 0.3 wt% for calcite. Relative standard deviations were 3.4 % for 8.0 wt% of anhydrite and 1.8% for 5.4 wt% of calcite. The present method is applicable to determination of calcium sulfate and calcium carbonate in actual dust samples.

Lattice thermal expansion of a number of compositions in the tetragonal (P4mm) single cell region of the lead zirconate titanate Pb(ZrxTi1−x)O3 system have been measured by high temperature X-ray diffraction. Polynomial coefficients which describe the temperature dependence of the lattice constants of each composition below and above the ferroelectric-paraelectric transition temperature are given.