The main characteristics of a new method of texture analysis are presented as well aa a comparative study of the results obtained with three different methods.

X-ray powder diffraction data of BaFCl are reported for 2θ from 5° to 150° at 25 °C. Strain-free and dendrite-free single crystals of BaFCl, grown by flux method with KCl as flux, were powdered for recording this data. BaFCl is tetragonal, space group P4/nmm, with a=4.3964(1) Å and c=7.2315(3) Å.

A new mixed lead thorium phosphate, Pb0.5Th2(PO4)3, has been isolated in the system PbO–ThO2–P2O5. Its crystal structure (monoclinic symmetry, a=17.459(1) Å, b=6.8451(4) Å, c=8.1438(5) Å, β=101.247(5)°, space group C2/c) has been determined from conventional monochromatic X-ray powder diffraction data. The structure is related to the MITh2(PO4)3 structure type. Lead atoms are located in the channels parallel to the c axis, out of the twofold axis for 0.97 Å, and are statistically distributed on a quarter of crystallographic positions. The thermal stability of this material is greater than that of the monazite-type compound PbTh(PO4)2.

Crystal structures of types II and III chlorothalonil, 2,4,5,6-tetrachloro-1,3-dicyanobenzene, (C8Cl4N2) were solved by applying Monte Carlo simulated annealing techniques to X-ray powder diffraction data and refined using the Rietveld method. Both types of chlorothalonil crystallize in monoclinic symmetry (space group P21 and two molecules per unit cell). Lattice parameters are: a=8.1615(18) Å, b=9.4191(19) Å, c=6.4728(14) Å, β=93.7307(64)° and V=497.8 Å3 for type II, and a=8.6003(10) Å, b=9.2382(11) Å, c=6.3024(7) Å, β=96.2152(60)° and V=498.5 Å3 for type III. The structures of both types of chlorothalonil are stacked by two coplanar molecular sheets paralleled to the b-axis. The adjacent two paralleled molecules in type II are on the same plane, while those in type III are on two different parallel planes.

An Sb3Nb3O13 [Sb(III)2Sb(v)Nb(v)3O13] phase having a defect pyrochlore structure has been prepared by heating a sol–gel derived powder in oxygen. X-ray powder diffraction results indicate that Sb3Nb3O13 has a face-centered cubic structure, S.G. Fd3m(227), with a refined unit cell parameter a =10.4965(1) Å, calculated density Dx=4.893, four molecules per unit cell (Z), and a calculated figure of merit SS/FOM F30=92.4(0.009,38).

We report on the use of a microcalorimeter X-ray detector with a transition edge sensor in an electron probe to perform quantitative analysis. We analyzed two bulk samples of multielement glasses that have been previously characterized by chemical methods for use as standard reference materials. The spectra were analyzed against standards using three different correction schemes. In one of the standards, the reference line was easily resolved despite its proximity within 45 eV of another line. With the exception of direct measurements of oxygen (a particularly challenging element), the results are in agreement with the certified characterization to better than 1% absolute or 8% relative. This demonstrates the potential of microcalorimeter detectors as replacements for conventional energy dispersive detectors in applications requiring high energy resolution.

Considering the thermal expansion of silicon at ambient conditions, the lattice parameter will change 0.00032 Å for a 10 °C range. This range is measurable with modern diffraction instrumentation illustrating the importance of knowing the accurate lattice parameter, the temperature of measurement, and the thermal expansion coefficient. The best value for the expansion coefficient is 2.45×10−6/°C.

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.

X-ray powder diffraction is a convenient tool for monitoring changes in structural parameters due to modifications in sample composition and processing conditions. Due to the complexity of incommensurate modulated structures powder diffraction techniques have not been commonly applied. Programs ALSQ and QRIET have been produced to perform lattice parameter and structure refinements on incommensurate modulated materials with a displacive modulation model. In applying these programs to the Bi2Sr2CaCu2O8 superconductor which has this type of structure, it is shown that a decrease in the lattice parameters and an increase in the modulation vector occurs as the Ca content of the Bi-2212 phase, controlled by the use of the glass ceramic process, increases.

Observed powder diffraction data for two tetracyclines were interpreted with the aid of calculated patterns based upon the crystal structures determined from a single crystal of the same batch for each compound. The results consist of high quality standard powder patterns with the usual supporting data.

Fourteen reference patterns of oxide ceramics are reported. Included in the fourteen reference patterns are data for nine high critical temperature super-conducting oxide related phases: (BaCuEr2O5, Ba2Cu3EuO7, BaCuGd2O5, Ba2Cu3GdO7, Ba2.4Cu5La4O13, Ba1.9cu3La1.1O7, Ba2Cu3SmO7 and (Ba0.4Sr0.6)2Cu3 YO7). 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)). The symbols used in this article are defined in the PDF cards.

The crystal structure of titanium-tin tellurium oxide Sn0.59Ti0.41Te3O8 has been determined using X-ray powder diffraction techniques. At room temperature, the title compound crystallizes in cubic space group Ia-3, with lattice parameter a=11.05515(6) Å. Rietveld refinement of the structure led to final confidence factors Rp=0.0395 and Rwp=0.0577. The structure of Sn0.59Ti0.41Te3O8 consists of isolated Ti/SnO6-octahedra slightly deformed in the a direction. The TeO4E [E=lone pair of Te(IV) atoms] groups are located between the octahedra ensuring the stability of the structure by Ti/Sn-O-Te bonding contacts. Only one peak in thermal behavior was detected for this compound at 488 K by differential scanning calorimetry experiment. An IR spectroscopic study is employed as a means to obtain preliminary structural information and shows the presence of the Ti/SnO6 and TeO4E groups. This result is later confirmed by X-ray diffraction studies.

The intensity diffracted by a low-mass sample with negligible absorption may be expressed as It = I∞ (B/2μ*)/G, where I∞ = intensity diffracted by a bulk sample, B = cross section of the primary beam, μ* = mass absorption coefficient, and G = mass of the sample. Measurable intensity may be obtained from samples with less than 1 μg mass. In order to improve the limit of detection, the primary beam should be collimated so as to irradiate the sample and only a minimum volume of the sample support. The optimum spreading area of a low-mass sample is S sinθ≅10μ*. Comminution of low-mass samples to 1 — 2μm particles is adequate for reasonable intensity measurements.

Tacrine hydrochloride monohydrate, velnacrine maleate and suronacrine maleate have been investigated by means of X-ray powder diffraction. The unit cell dimensions, determined by single-crystal diffraction data, agree well with those of powder diffraction analysis, which is characterized by good figures of merit for the three drugs. Present work assures that single-crystals are good representatives of the commercial powdered samples, since experimental and simulated (from structure determination) powder patterns are practically identical.

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 powder diffraction data for 1-aminoanthraquinone at 295 K (P1¯, No. 2, Z=1) are given. The cell parameters found are a=8.205(1), b=8.396(1), c=3.7882(3) Å, α=93.46(1), β=92.57(1), γ=105.13(1)°. The crystal packing model is proposed giving Rb=0.095. The disordered molecule of 1-aminoanthraquinone occupies a special position on the inversion center.

Powder X-ray diffraction data of melatonin C13H16N2O2 were collected on a conventional X-ray powder diffractometer: the monoclinic cell parameter are a=7.7416(8) Å, b=9.2897(9) Å, c=17.1444(16) Å, β=96.756(9)°, volume 1224.4(3) Å3 (space group P21/c). The strongest lines are (d (Å), I/I0) 8.161 (100), 5.411 Å (46), 3.412 Å (34), 4.668 Å (33), 4.645 Å (25), 3.554 Å (22), 3.668 Å (16), and 4.483 Å (14). Reported intensities are validated by Rietveld analysis. The data consist of measured positions and intensities and cover an angular range up to 60° 2θ: experimental, calculated, and difference patterns are also reported.

Characterization of some crystalline species present in atmospheric particulate matter can be investigated by an X-ray diffractometric technique. According to the analytical strategy, filtering media suitable for collecting airborne particles must be selected. In order to recognize the X-ray diffraction patterns and consequently the inherent analytical interference of filtering media, a systematic X-ray diffraction evaluation of several substrates was performed. Although artifact formation during ambient sampling can occur on quartz and glass fiber filters, these filters were also included in the diffractometric characterization. In this work, commercial filters were thermally treated and submitted to X-ray diffraction scanning. Results have shown pronounced variations in the diffractometric profiles of each thermally treated substrate. The selection criteria for choosing the filtering media was established by considering their chemical and physical properties and also the crystalline species to be collected on them.

Na4CrNi(PO4)3 orthophosphate powder was prepared from acid solutions of NiO, Na2CO3 and aqueous solutions of Cr(NO3)3.9H2O, and (NH4)2HPO4 at a final temperature of 750 °C. The hexagonal unit cell parameters were determined to be ah≈8.789 Å and ch≈21.481 Å in space group R3¯c. These parameters were compared to those of Na4AA′(PO4)3 (AA′=CrMg, CrCo, TiNa, ZrNa). The linear variations of these parameters versus the mean A cation radius (rAA′) are consistent with the atomic distribution found for the structure of Na4NiCr(PO4)3. The ah and ch parameters are functions of the An+ ion size.

Evidence is provided that the tridymite component observed in the X-ray diffraction patterns of some sewage sludge ashes (SSAs) should not be interpreted as the tridymite modification of SiO2 but as the tridymite form of AlPO4. This proof is based on a combined X-ray Powder Diffraction (XRD), X-ray fluorescence (XRF) and Mossbauer spectroscopy investigation of two SSAs produced at two fluidized bed incineration facilities, located in different municipalities and operated differently. The structural and chemical characterization was carried out on the ‘as received’ SSA samples as well as on the residues of these two SSAs pretreated by leaching in citric acid. In addition, direct proof is presented that the tridymite form of AlPO4 does crystallize from X-ray amorphous precursors under conditions that mimic the huge heating rate and short retention time (just seconds at T ≈ 850 °C) typical for fluidized bed incinerators.