Powder diffraction data

ICDD, International Centre for Diffraction Data, Powder Diffraction File—2 Sets 1-47, Card 18-117 (1997a). 

International Center for Diffraction Data, Powder Diffraction File database, that the analyzed sample is composed of almost 100% BaCe0, 95 Yb0 05O3-5 perovskite. 

International Centre for Diffraction Data, Powder Diffraction File 33-1354. 

International Center for Diffraction Data Powder Diffraction File, ASTM, Swarthmore, PA... 

Peterson, V. K., A. S. Ray and B. A. Hunter (2006). A Comparative Study of Rietveld Phase Analysis of Cement Clinker Using Neutron, Laboratory X-Ray, and Synchrotron Data . Powder Diffraction 21 12-18. 

Powder diffraction studies with neutrons are perfonned both at nuclear reactors and at spallation sources. In both cases a cylindrical sample is observed by multiple detectors or, in some cases, by a curved, position-sensitive detector. In a powder diffractometer at a reactor, collimators and detectors at many different 20 angles are scaimed over small angular ranges to fill in the pattern. At a spallation source, pulses of neutrons of different wavelengdis strike the sample at different times and detectors at different angles see the entire powder pattern, also at different times. These slightly displaced patterns are then time focused , either by electronic hardware or by software in the subsequent data analysis. 

Powder diffraction patterns have three main features that can be measured t5 -spacings, peak intensities, and peak shapes. Because these patterns ate a characteristic fingerprint for each crystalline phase, a computer can quickly compare the measured pattern with a standard pattern from its database and recommend the best match. Whereas the measurement of t5 -spacings is quite straightforward, the determination of peak intensities can be influenced by sample preparation. Any preferred orientation, or presence of several larger crystals in the sample, makes the interpretation of the intensity data difficult. 

J. D. H. Doimay and H. M. Ondik, Crystal Data Determinative Tables, 3rd ed, U.S. Department of Commerce, National Bureau of Standards Joiut Committee on Powder Diffraction Standards, Washiagton, D.C., 1972, pp. 0-23, 0-73, 0-97, 0-106. 

Sea.rch-Ma.tch. The computer identifies which crystalline phases (components) match the unknown pattern by using a file of known powder patterns maintained by the International Center for Diffraction Data (ICDD). The Powder Diffraction File contains interplanar t5 -spacings d = A/(2sin0)] and intensities of the diffraction maxima for each crystalline powder pattern submitted to the ICDD. Currendy there are about 65,000 patterns in the file. Current search—match programs can successfully identify up to seven components in an unknown pattern. A typical diffraction pattern of an unknown sample and the components identified by the computer search-match program is shown in Figure 15. 

According to X-ray powder diffraction data, compounds RF NbOFs, Cs2NbOF5 [174] and Cs2TaOF5 [176] have similar type structure and are similar to K2GeF6, whereas (NFL,)2NbOF5 crystal structure is similar with Rb2Mo02F4 [184]. The above-mentioned compounds contain isolated NbOF52" complex ions [185]. 

X - Ray powder diffraction data of some important tantalum and niobium fluoride compounds (CuKa radiation)... 

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