Papers by Keyword: Rietveld Refinement

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Authors: Alexander M. Korsunsky, Karen E. Wells, Brian A. Shaw
504
Authors: Frida Ulfah Ermawati, Suasmoro Suasmoro, Suminar Pratapa
Abstract: A study of liquid mixing route to synthesize high purity Mg0.8Zn0.2TiO3 nanopowder, a candidate dielectric ceramics, has been successfully performed. Formation of the phases on the dried powder was studied using TG/DTA, XRD and FT-IR data. Rietveld analysis on the collected XRD patterns confirmed the formation of solid solution in the system. Such solid solution can be obtained from the powder calcined at 500 °C, but calcination at 550 °C gave rise to the most optimum molar purity up to 98.5% without intermediate phases. The role of Zn ions on the formation of solid solution was also discussed. Homogeneity of particle size distribution and nano-crystallinity of the system was verified from the particle size analyzer data, TEM image and the Rietveld analysis output.
47
Authors: Y. Kabalov, E. Sokolova, V. Gorbatova, J. Schneider, A. Konev
994
Authors: John S.O. Evans
Abstract: Topas is a powerful and flexible software suite for the analysis of powder diffraction (and other) data. In this paper we describe methods to interact with the software in efficient and customisable ways. We also provide brief details of a wiki site for sharing ideas and methods for this software (topas.dur.ac.uk). Finally we give an overview of the potential advantages of parametric refinement methods within Topas and exemplify them with a quantitative analysis study of the phase transitions in WO3.
1
Authors: Fu Zeng Ren, Ren Long Xin, Xiang Ge, Yang Leng
Abstract: Nanocrystalline Zn-substituted calcium hydroxyapatite (HA) powder was synthesized by wet chemical method. Detailed characterization was carried out with both experimental techniques and numerical simulation method. X-ray diffraction (XRD) patterns show the calcium phosphate maintains as the apatite phase when the atomic ratio of Zn/(Zn+Ca) is less than 17% Zn in aqueous solutions. The calcium phosphate crystallinility decreases with the Zn concentration increase. The morphological changes with Zn substitution in HA were investigated by TEM. Lattice parameters of the apatitic samples were determined by XRD Rietveld refinement method. A computational study using ab initio generalized gradient approximation density functional theory was performed on Zn-substituted HA. Comparison of the experimental and computer simulation results provides our insights of Zn substitution in apatite structure.
1379
Authors: J. Lorimier, Frédéric Bernard, Olivier Isnard, J.C. Niepce, J.F. Bérar
594
Authors: Frédéric Bernard, J. Lorimier, V. Nivoix, N. Millot, P. Perriat, J.C. Niepce, B. Gillot, M. Ferlet, Jean François Berar
594
Authors: H. Sitepu, J.P. Wright, T. Hansen, Daniel Chateigner, Heinz Günter Brokmeier, Clemens Ritter, Takaomi Ohba
Abstract: The crystal structure of R-phase in Ti50.75.Ni47.75.Fe1.50 shape memory alloy (SMA) has been studied at a temperature of (290 ± 7) K on cooling by combined synchrotron and neutron powder diffraction using Rietveld refinement with generalized spherical harmonic (GSH) description for preferred orientation (PO). The results showed that (i) no significant improvement in the crystallographic RWP-factor was found when the inversion center was removed from the 3 P model, suggesting that the space group was indeed 3 P and not lower symmetry 3 P neither m P31 and (ii) the refined atomic parameters were converging only when the 3 P space group was used in the refinement.
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