The boron and iron for aluminum substitution in the Rb-leucite structure (RbAlSi2O6, ICDD card 38-201) has been examined by sol-gel preparation of different samples along the three compositional joins Rb(X,Y)Si2O6, where X and Y are any two of the elements Al, Fe, B. The compound RbBSi2O6 (a0=12.831 Å) is here described and characterized by X-ray powder diffraction for the first time, while the compound RbFeSi2O6 is reexamined with a more precise determination of lattice parameters and diffraction intensities with respect to ICDD card 31-1189. The lattice parameters and the space groups of different selected terms of the three solid solutions are reported.

Indexed X-ray diffraction data are reported for 1-adamantanol. The data were indexed on a tetragonal unit cell with a=15.869 Å and c=6.879 Å, P44/nZ=8.

Methods for precise control of the cutting angles of quartz by x-ray measurements are described. The quartz must first be oriented by some other method (usually optically) before the x-ray method can be applied. The sense of direction of the cut is indicated by an arrow drawn on the outer surface of the test cut at the saw and this direction is preserved in making the x-ray measurement. The x-ray technique is an adaptation of the Bragg ionization chamber method and involves measuring the angle between the surface of the test cut or blank and an atomic reference plane parallel (or nearly parallel) to the surface. All measurements are direct, and require no computation. A Gieger-Muller tube operated in the proportional counter region is employed. Accuracy of the method is approximately ±1.5′, the measurement requires about 10-15 seconds, and is used by unskilled help. The procedures for calibrating the x-ray goniometer and measuring various types of cuts are described in detail. Methods involving precise angular adjustments of sections approximately oriented by other methods and the use of reflection intensity differences of certain planes on either side of the optic axis for detecting usable portion of electrical twins and negative and positive directions from Z are described. The methods are applicable to other fields.

The compounds, BaR2Ti3O10: R = La, Pr, Nd and Sm; BaR2Ti4O12: R = La, Pr, Sm, Gd, Eu have been prepared by solid state reaction and characterized by X-ray powder diffraction. Unit cell data are summarised; lattice parameters and unit cell volumes increase approximately linearly with lanthanide ion size.

Samples of the mineral ferroan clinozoisite from three localities of Greece (Paranesti-Drama, Xanthi, and Petritsi-Serres), with chemical formula Ca2Al3−xFexSi3O13H (x=0.55, 0.58, and 0.46, respectively), were measured by X-ray powder diffraction, using CoKa radiation. The PDF and bibliographic information were used in order to identify additional phases in the samples. Refinement combined with PDF resulted in the following: ferroan clinozoisite (100%) for the first sample, ferroan clinozoisite (97%) and malladrite (3%) for the second one, and ferroan clinozoisite (75%), clinopyroxene (20%), and malladrite (5%) for the third one. The crystal structure refinement was performed by the “Powder profile analysis (Rietveld)”. P21/m space group was chosen for the ferroan clinozoisite phases, with unit cell constants a=8.8919(5) Å, b=5.6260(3) Å, c=10.1570(6) Å, β=115.418(3)° (Paranesti), a=8.8944(7) Å, b=5.6394(4) Å, c=10.1626(8) Å, β=115.400(5)° (Xanthi) a=8.8965(8) Å, b=5.6372(4) Å, c=10.1595(9) Å, β=115.411(6)° (Petritsi) almost similar for the three samples, while the final R-p factors were 0.069, 0.064, and 0.063, respectively.

A powder diffraction method was applied to the quantitative analysis of amorphous silica in several quartz powders. Two calibration methods, i.e., direct analysis and the standard addition method were examined. Calibration mixtures were made by mixing a standard silica gel powder ground to under 5 μm particle size with a matrix quartz powder which was ground to 10 to 40 μm particle size and treated with NaOH solution to remove the amorphous phase caused by grinding. Intensity of the amorphous halo was measured at 23.0° 2θ, and the background intensity at 53.0° 2θ was subtracted. Linear calibration curves were obtained over the ranges of 0 to 50 wt% by direct analysis and 0 to 20 wt% by standard addition methods, respectively. The analytical results obtained by the two calibration methods were in good agreement with each other. The relative standard deviations for 4.3 wt% of amorphous silica were 4.6% by the direct analysis and 5.4% by the standard addition method. These methods were successfully applied to a correction of reference intensity ratios (RIR) for several quartz powders containing amorphous silica. After the correction for amorphous content, the relative standard deviations of the RIR values for quartz powders became smaller.

An X-ray powder diffraction analysis has been performed on several samples from the naturally occuring patina of the Statue of Liberty. This work, which was conducted as a service to the National Park Service as part of the restoration activities for the Statue, was performed to assess the impact of acid deposition on the phase composition of the patina. Samples of the patina that were obtained from various locations on the copper skin of the Statue were found to consist primarily of the basic copper sulfate known as brochantite or CuSO4·3Cu(OH)2. Another less stable form of basic copper sulfate CuSO4·2Cu(OH)2 known as antlerite was also observed in samples taken from areas that are more exposed to the incoming weather in New York harbor. The presence of antlerite supports the contention that acid deposition is promoting undesirable changes in the phase composition of the patina. Analyses were also performed on patina samples that were taken from pieces of the Statue's copper skin that had been removed in the years 1905 and 1980. X-ray powder diffraction of the corrosion product on the 1905 sample showed that it consisted primarily of the stable brochantite phase, while the 1980 sample displayed both copper chlorides as well as the less stable antlerite. Both samples also contained cuprite (Cu2O) which appears to have formed prior to either of the sulfates.

The structure of K3H(SO4)2 is found to be monoclinic with space group C2/c based on analogy of the powder X-ray diffraction pattern with that of the Rb3H(SO4)2. The lattice parameters are a=14.6984(7), b=5.6840(2), c=9.7834(5) Å, and β=103.004(5)°, Vol=796.39(5); Dx=2.589 gcm−3, Z=4, and I/Icor=1.30.

Since the discovery of the superconductivity in Ba2YCu3 O7-x, the system Ba-Y-Cu-O has generated vast interest. The presence and the properties of the intermediate phases were examined, and the existence of the BaY2O4 phase was confirmed.

We have determined the crystal structure of this material from powder data; it is orthorhombic, Pnma (no 62) with a = 10.394(3) Å, b = 3.450(1) Å, c = 12.113(4) Å, isotypic with SrY2O4 (CaFe2O4-type). The observed and calculated intensity values are reported together with the powder diffraction data, obtained both by Guinier and diffractometer methods.

A conventional vertical powder diffractometer has been adapted to allow the collection of high-resolution, single-wavelength diffraction data using Co, Cu or Mo radiation. The major modifications are (i) incorporation of an incident beam focusing monochromator attached to the tube shield, (ii) a variable tilt angle of the tube shield to provide a horizontal beam path through the diffractometer (for ease of alignment), (iii) mounting of the entire diffractometer on a single, very stable base-plate, with micrometer-controlled adjustment of the orientation, (iv) inclusion of a knife-edge, micrometer-controlled focusing slit, and (v) use of a range of Soller slits with acceptance angles down to 1.5° 2φ. The performance of the instrument compares favourably with conventional non-monochromated diffractometer data collected from SRM660 LaB6 and monoclinic ZrO2. In particular, the peaks are more symmetric and have narrower widths, and the peak-to-background ratio is much higher, leading to much superior resolution and profile shapes for structure solution and Rietveld refinement.