Results and conclusions of the internet based ``Search/match round robin 2002''

Powder Diffraction 01/2003; 18:106-113. DOI: 10.1154/1.1557031
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    ABSTRACT: The fuzzy frontiers between structure determination by powder diffractometry and crystal structure prediction are discussed. The application of a search-match program combined with a database of more than 60 000 predicted powder diffraction patterns is demonstrated. Immediate structure solution (before indexing) is shown to be possible by this method if the discrepancies between the predicted crystal structure cell parameters and the actual ones are < 1 %. Incomplete chemistry of the hypothetical models (missing interstitial cations, water molecules, etc.) is not necessarily a barrier to a successful identification (in spite of inducing large intensity errors), provided the search-match is made with chemical restrictions on the elements present in both the virtual and experimental compounds. (C) 2008 International Centre for Diffraction Data.
    Powder Diffraction 06/2008; 23(2):S5-S12. DOI:10.1154/1.2903488 · 0.59 Impact Factor
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    ABSTRACT: The Tikhonov regularization of the reference intensity ratio (RIR) method integrated within the information retrieval system of X-ray phase analysis together with the method of cluster phase identification is reported. The possibilities of the methods are discussed by the example of the X-ray phase analysis of test mixtures from Round Robin on QPA held by the International Union of Crystallography Commission for Powder Diffraction (CPD).
    Journal of Structural Chemistry 04/2011; 52(2):319-325. DOI:10.1134/S0022476611020119 · 0.50 Impact Factor
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    ABSTRACT: Complete nominal solid solutions La0.67Ba0.33-xNaxMnO3 (0 ≤ x ≤ 0.33) have been elaborated by ceramic route at 1200°C. ICPAES chemical analysis and XRD Rietveld structure refinement revealed that the nominal Na content is not achieved by our ceramic method. The chemical formula should be rather written as LaαBaβNaλMnO3-δ with a significantly lower Na content (λ), than the nominal one (x), and with a slight deficit (δ) in oxygen content, leading to the appearance of two minor secondary phases identified as Mn3O4 and Na0.55Mn2O4·1.5H2O. Magnetization and electrical resistance vs. temperature show paramagnetic/semiconductor - ferromagnetic/metallic transitions with only a slight decrease in magnetic and electrical transition temperatures when Na content increases. Such amount of this decrease is not expected according to the nominal Na content giving a significant difference between nominal and experimental Mn4+/Mn3+ ratios.
    The European Physical Journal Conferences 06/2012; 29:00022-. DOI:10.1051/epjconf/20122900022