Structural and chemical changes in materials can be dynamically observed by using time resolved X-ray Powder Diffraction (XRPD) to collect patterns as these events happen. During calcination of amorphous zirconium hydroxide, Zr(OH)4, and its crystallisation to a metastable tetragonal form of zirconia, ZrO2, patterns have been collected at 10°C temperature intervals during a heating sequence to 500°C. These patterns show both the onset of ordering within the amorphous starting material and the progress of its conversion into crystalline zirconia. Events are recorded within the pattern in the form of peak growth and reduction in amorphous component of the pattern with increasing temperature.

A conventional Bragg-Brentano type diffractometer was equipped with a stepping motor, a timer, and a scaler, and an MC68000 Motorola microprocessor which controls the diffractometer functions. The microprocessor was programmed to operate the diffractometer in a step-scanning mode, to check a datum and to communicate with a process control computer, e.g. a PDP 11/44 or a Micro VaxII computer.

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 performances of Seeman-Bohlin (S-B) and Bragg-Brentano (B-B) diffractometers with flat thin film samples were compared on the basis of equal instrumental aberrations. It was found that the S-B arrangement has only a marginal advantage as regards diffracted intensity, and that both types of diffractometer may be successfully employed for characterization of thin films. Diffraction data obtained with very thin metallic films (down to 30 Å) are included for illustration. In order to eliminate reflections from the singlecrystal substrate in the B-B diffractometer, sample tilting was employed. Provided the tilting angle remains within 0.5°, sample tilting causes only moderate additional broadening of the thin film peaks.

The usefulness of complementing the results of X-ray diffraction (XRD) with an independent technique such as Raman spectroscopy (RS) was demonstrated by the successful identification of the products (TiN and Na-titanates) from the reaction of TiO2 with NaCN. The study of other reactions of NaCN with several Ti-compounds to produce TiN powder led to the development of new syntheses reactions for known [TiP2O7, NaTi2(PO4)3 and NaxTiO2] and for new [(TiO)2P2O7, Na(TiO)PO4 and Na4(TiO)(PO4)2] compounds. The reaction of NaxTiO2 with NaCN produced TiN in the form of whiskers.

Bright apple green millimeter-sized crystals of tavorite from the Tip Top pegmatite, near Custer, South Dakota are triclinic, space group , with refined unit-cell parameters a = 5.340(2), b = 7.283(2), c = 5.110(2)Å, α = 109.29(2)°, β = 97.86(3)°, γ = 106.32(3)°, V = 174.1(3)Å3, a:b:c = 0.7332:1:0.7016, Z = 2, D(m) (suspension in methylene iodide) = 3.32(1) and D(x) = 3.33 g/cm3 (for the theoretical formula). A fully indexed X-ray powder pattern is presented. Semiquantitative electron microprobe and secondary ion mass spectroscopic analyses indicate a formula near end-member LiFe + 3(PO4)(OH). The Tip Top tavorite is biaxial positive, α = 1.795(5), β = 1.81(1), γ = 1.86(1), 2V(meas.) = 50(2)°, 2V(calc.) = 59°, XΛa ≃ 15°, YΛb ≃ 0°, and ZΛc ≃ 38°. There is no evidence for optical absorption, pleochroism or dispersion.

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.

The construction and use of a captive inert atmosphere cell for the preservation of atmospherically sensitive samples during X-ray diffraction is described.

The diffraction patterns of coarse grained materials are compared to specimens with crystallite sizes of less than 1 µm characterized by diffraction spots. Based on an analysis of spot intensities it is shown that for: (a) an at-random distribution of crystallite orientations and (b) under the assumption of specific crystallite shapes it becomes possible to evaluate the distribution N(l) of linear crystallite dimensions (0.1 µm < l < 20 µm) from measured spot intensity distributions z(i).

The trihydrated ammonium trioxalato-ferrate (III) (NH4)3(Fe(C2O4)3)·3H2O cristallizes in the monoclinic system with:

The space group is P21/c[14].

Fourier transform methods of smoothing and interpolation are applied to X-ray diffraction data. It is shown that, frequently, too small a step size is used. Major gains are to be expected by selection of the optimum step size and use of these methods.

A comparison of Fourier transforms of diffractograms of quartz measured between 67 and 69° 2θ, collected at varying step intervals (0.1 to 0.01° 2θ) was used to illustrate these applications. By examining the Fourier transform of the diffractogram and noting where it decays to die baseline, a reasonable estimate of the optimal step interval can be obtained. In addition, Fourier interpolation can be used to enhance the appearance of the diffractogram, approximating a continuous plot.

Crystal data for four p-dibromobenzene/p-chloroiodobenzene mixed crystals, (pDBB)x(pCIB)1-x, with x = 0.1, 0.4, 0.7, 0.9, synthesized by the fusion-quenching method, and a typical powder diffraction pattern are reported. The unit cell is monoclinic with S.G. = P21/a and Z = 2. Cell parameters of solid solution members varied almost linearly between the end member values.

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.

X-ray powder data and crystal data for the ortho (2 –), meta (3 – ) and para (4 – ) isomers of nitroaniline, NO2C6H4NH2, are reported. The results are compared to existing PDF patterns.

Indexed X-ray diffraction powder data for three homologous amphiphiles, sodium octyl sulfate (SOS), CH3[CH2]7 OSO3Na, sodium decyl sulfate, CH3[CH2]9OSO3Na (SDS), and sodium dodecyl sulfate CH3[CH2]11OSO3Na (SLS), are reported. Probable space groups for the three compounds are monoclinic P2[3], Pm[6], or P2/m[10]. Refined cell parameters were determined from powder data obtained with a Guinier Camera. Powder data are compared to existing patterns, PDF 4-10 (SOS) and 4-6 (SLS).

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).

Fourteen reference patterns of oxide ceramics are reported. Included in the fourteen reference patterns are data for two high critical temperature superconducting oxide related phases (BaCuHo2O5 and Ba2YCu3O6.56). The general methods of producing these X-ray powder diffraction reference patterns were described previously in this journal (Vol. 1, No. 1, pg. 40 (1986)).

X-ray powder data and crystal data for acetaminophen, C8H9NO2, are reported and results are compared to existing PDF patterns.

The structure of TeO3, first published by Dumora and Hagenmuller (1968), was redetermined from new X-ray data collected with a powder diffractometer using space group R3̄c with a = 4.901(2), c = 13.030(4) Å, V = 271.05(8) Å3 and Z = 6. Intensity data were obtained with CuKα, radiation (λ = 1.540598 Å). Structure refinement was performed with 49 reflections and led to R = 0.058. The material is isostructural with FeF3. Powder data are given.

The trihydrated rubidium trioxalato-chromate(III), Rb3(Cr(C2O4)3)·3H2O cristallizes in the monoclinic system with:

The space group is P21/c. CuKα wavelength 1.541778.