The powder diffraction pattern for p-Iodotoluene C7H7I at 293 K (P212121, No. 19, Z = 4) is given. The cell parameters found are a = 16.484(2) Å, b = 7.444(2) Å, c = 6.108(l) Å.

The crystal structure of a new compound Li2Mg2(WO4)3 has been determined by means of X-ray powder diffraction. Li2Mg2(WO4)3 belongs to the orthorhombic system, with space group Pnma and the lattice parameters are: a = 5.1129 Å, b = 10.462 A, and c = 17.612 Å at room.temperature. Its measured density is Dm = 5.48 g/cm3, and each unit cell contains four formula weights.

Three new compounds of generalised formula [Cu(LIII)XY]·nH2O [LIII=pymep, terpy; X=I, N3; Y=I, NO3, PF6; n=0,1], pymep (C14H15N3)=N-(6methyl–2-pyridyl–methylene) -2-(2-pyridyl)-ethylamine and terpy (C15H11N3)=2,2′;6′,2″-terpyridine have been prepared by reaction in solution. Crystal data were determined by single-crystal methods. Powder diffraction data and densities determined by a flotation method are also presented.

A Rietveld refinement of powder X-ray diffraction data of BiSbO4 is reported. The refined lattice parameters are a =5.4690(2), b =4.8847(3), c = 11.8252(6) Å, and β = 101.131(3)°. The powder data are compared with the PDF patterns designated BiSbO4 (30-177) and SbBiO4 (7-191).

An X-ray detector chain consisting of a Xe-filled proportional detector followed by a pulse height analyzer tuned to 8.1 keV may register energies between 5 and 45 keV, although with a low efficiency at the edges. For diffraction experiments on single-crystalline substrates, these diffracted intensities can be significant. In the high-energy range, regions of even higher intensity are found due to the so-called escape process. In the diffraction angle scan of an (001) oriented Si single-crystal measured with a low (fixed) incidence angle, we have identified 21 peaks, originating from three different diffraction processes: diffraction from white radiation, diffraction observed via an escape process, and crystal truncation rod scattering. These peaks interfere with diffraction studies if such a single crystal is used as a substrate for polycrystalline samples. A great reduction in the substrate background and removal of most of the substrate diffraction peaks is achieved with a graphite monochromator or with a graphite monochromator together with a β-filter.

An increasingly frequent used sample holder, the zero-background holder (ZBH), is evaluated for use in external standard calibration of powder patterns. The effectiveness of the ZBH calibration method is determined by comparison to the conventional internal- and external-standard calibration techniques. The three calibration methods are compared using the results of lattice parameter refinements of test powders, using Si as the standard. Several test materials were used in the evaluation which cover a wide range of absorption coefficients so sample transparency effects can be distinguished from sample displacement effects. Results of the calibrations clearly indicate that the ZBH method gives precision and accuracy comparable to the internal-standard method, and significantly better than the external-standard technique. In addition, the ZBH method yields substantially better results than the internal-standard method for materials with low absorption coefficients. Low-angle calibrations are also made on a ZBH using a proposed standard, silver behenate, which has peaks from 1.5° to 20° 2θ. These calibrations have shown that if care is not taken to establish a monolayer of powder on the ZBH crystal, significant errors in refined lattice parameters will result.

A simple procedure was devised for the preparation of a standard KCl powder to be used for the experimental determination of the instrumental profile in the Bragg–Brentano geometry. The standard was tested on several diffractometers, and narrow Bragg reflections in the range 28°–132° were recorded adopting various experimental conditions. Profiles were modeled with analytical functions, to describe the trend of width and shape of the instrumental profile as a function of the diffraction angle. Some indications were given to perform reliable profile fitting and line broadening analysis; a high resolution setup, obtained by employing narrow slits, large goniometer radius, and a monochromator in the diffracted beam, gives narrow reflections, even though the intensity of the diffracted beam is considerably reduced. The choice of these experimental conditions, which can be achieved using the majority of the commercial instruments, leads to symmetrical profiles, even at relatively low angle (2Θ=28°), which are highly recommended for reliable profile fitting and line broadening analysis.

X-ray powder diffraction data for Ti2O2(C2O4)(OH)2·H2O were obtained. The crystal system was determined to be orthorhombic with space group C2221. The unit cell parameters were refined to a = 1.0503(2) nm, b = 1.5509(3) nm, and c = 0.9700(1) nm.

The crystal structure data have been determined by X-ray diffraction for three rare earth magnetic materials, Nd2Co14B, Pr2Co14B, and Pr2Fe14B. The data were evaluated with several computer programs desingned for that purpose. The crystal structure for Nd2Co14B and Pr2Fe14D determined by X-ray diffraction agree with those obtained earlier by neutron diffraction.

The crystalline structure of new TlSr2PrCu207−x was obtained at room temperature (300 K) and low temperature (100 K) from X-ray powder diffraction with CuKα radiation using Rietveld analysis. TlSr2PrCu207−x has an isotypical structure with TlBa2CaCu207 (1212). At 300 K, crystal data: Tl0.864Sr2PrCu2O6.75, Mr=727.811, the tetragonal system, P4/mmm, a =3.85404(5) Å, c = 12.1046(2) Å, V=179.80 Å3, Z=1, Dx =6.7218 g cm−3, μ =1143.922 cm−1 (λ = 1.54051 Å), F(000)=317.0, the structure was refined with 28 parameters to Rwp=5.29%, Rp = 3.65% for 3551 step intensities and Rb=7.40%, Rf=639% for 155 peaks, “goodness of fit” 5=3.05. At 100 K, crystal data: Tl0.858Sr2PrCu2O6.61, Mr=724.345, the tetragonal system, P4/mmm, a =3.84872(6) Å, c = 12.0771(3) Å, V=178.89 Å3, Z=1, Dx=6.7235 g cm−3, μ=1146.939 cm−1 (λ= 1.54051 Å), F(000) = 315.4, the structure was refined with 26 parameters to Rwp=6.70%, Rp=5.11% for 2926 step intensities and Rb=7.83%, Rf=6.70% for 131 peaks, “goodness of fit” S = 1.75.

Accurate powder diffraction data for the superconducting phase TlBa2Ca2Cu3O9−δ have been obtained. This phase crystallizes in a tetragonal unit cell, with space group P4/mmm. Cell refinement of our material resulted in a tetragonal unit cell with a=3.8453(8)Å and c = 15.909(4)Å. These diffraction data improve on data currently present in the powder diffraction file. Our experimental data also agree with calculated diffraction patterns obtained from published atom positions.

Titanium oxycarbonitride was observed to form during the carbothermic reduction of TiO2 in the presence of nitrogen. A powder diffraction pattern for this phase which is isomorphous with TiC, TIN, and TiO is presented. The crystal structure is further discussed in terms of the observed composition and lattice defects.

Crystal structure analyses by the Rietveld method have shown that the framework structures of zeolites ZSM-5 and ZSM-8 are essentially identical. Therefore, it is difficult to distinguish the two phases especially when the template-free H forms are studied. In addition, some inconsistencies in publications on the two zeolites aggravate the correct interpretation of the powder diagrams. A powder pattern published for ZSM-8 which indicates significant differences between the lattice constants of ZSM-8 and ZSM-5 is shown to be incorrectly indexed. Correct reindexing gives lattice constants for ZSM-8 matching average ZSM-5 values. Peak splitting of a ZSM-8 reflection at 2θ≈23° (CuKα) has been used frequently to distinguish ZSM-8 from ZSM-5. However, it is also a common feature of ZSM-5 diagrams when the difference between a and b lattice constants is big enough to separate hkl and khl reflections within the instrumental resolution. Our data on two ZSM-8 samples indicate that cell dimensions of ZSM-8 do not deviate from average ZSM-5 values. It is suspected that effects in the decomposition of crystals upon calcination, and/or morphology and shape of twin individuals, and/or stacking faults account for different sorption properties of the two zeolites rather than differences in their average crystal structures.

Diffraction patterns were recorded, and unit cell dimensions refined by the least-squares method, for lactitol and lactitol monohydrate. Refined unit cell parameters for lactitol are: a =7.622(1) Å, b = 10.764(2) Å, c = 9.375(1) Å, β= 108.25(1)° in space group P21, and those for lactitol monohydrate a =7.844(1) Å, b = 12.673(2) Å, c = 15.942(2) Å in space group P212121.

Wide angle X-ray powder diffraction data from unoriented and uniaxially oriented films of high-density polyethylene were analyzed by the Rietveld whole pattern profile fitting technique. A Voigt function was used to model the profile and extract crystallographic information such as the unit cell dimensions, crystallite size and strain, and degree of orientation. The analysis revealed that the technique was efficient in providing not only accurate unit cell dimensions without an internal standard, but also crystallite size and strain information. The oriented films were also successfully modeled with this technique.