A Raman spectroscopic study of the phase transition of BaZr(PO{sub 4}){sub 2}: Evidence for a trigonal structure of the high-temperature polymorph
- Institut fuer Mineralogie, Westfaelische Wilhelms-Universitaet, Corrensstr. 24, 48149 Muenster (Germany)
- European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany)
- Faculte des Sciences-Universite de Nantes, Institut des Materiaux Jean Rouxel-Laboratoire de Chimie des Solides 2, rue de la Houssiniere, B.P. 32229, 44322 Nantes Cedex 3 (France)
We have studied the structural evolution of monoclinic BaZr(PO{sub 4}){sub 2} during heating up to 835K by Raman spectroscopy. In agreement with previous studies we found a first-order phase transition at about 730K during heating while upon cooling the reverse transition occurs at 705K. However, some disagreement about the crystal structure of the high-temperature polymorph occurs in the literature. While the space group has not yet been determined, the X-ray diffraction pattern of the high-temperature phase has been indexed on either an orthorhombic or a hexagonal unit cell. We found that the number of Raman active internal PO{sub 4} vibrational modes decrease from nine to six during the transition. A group theoretical survey through all orthorhombic, trigonal, and hexagonal factor groups revealed that the observed number of vibrations would only be consistent with the Ba and Zr atoms located at a D{sub 3d}(3-bar m) site, the P and two O atoms at a C{sub 3v}(3m), and six O atoms at a C{sub s}(m) site in the D{sub 3d} factor group. Based on our Raman data, the space group of the high-temperature polymorph is thus either D{sub 3d}{sup 1}(P3-bar 1m), D{sub 3d}{sup 3}(P3-bar m1), or D{sub 3d}{sup 5}(R3-bar m)
- OSTI ID:
- 20785014
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 5; Other Information: DOI: 10.1016/j.jssc.2006.01.065; PII: S0022-4596(06)00082-X; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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