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Structure determination at room temperature and phase transition studies above Tc in ABi(4)Ti(4)O(15) (A=Ba, Sr or Pb)

Nalini, G and Row, Guru TN (2002) Structure determination at room temperature and phase transition studies above Tc in ABi(4)Ti(4)O(15) (A=Ba, Sr or Pb). In: Bulletin of Materials Science, 25 (4). pp. 275-281.

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Abstract

The room temperature structure of three compounds belonging to the Aurivillius family (n = 4), ABi(4)Ti(4)O(15) (A = Ba, Sr or Pb) has been analysed. BaBi4Ti4O15 crystallizes in a tetragonal 14/mmm space group whereas SrBi4Ti4O15 and PbBi4Ti4O15 crystallize in the orthorhombic space group A2(1)am. The starting model for the Sr and Pb analogues was derived from ab initio methods and refined using the Rietveld method. The cations Ba and Sr are disordered over the Bi sites while the Pb cation is found exclusively in the [Bi2O2](2+) layers. The TiO6 octahedra are tilted with the Ti-O bonds forming zigzag chains along the c axis. The displacement of Bi atoms along the a axis might be responsible for ferroelectricity in these compounds. The high temperature X-ray data above T-c indicate no structural transition for A = Ba and Pb while A = Sr transforms to the tetragonal structure.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Indian Academy Sciences.
Keywords: ab initio structure;powder XRD;Rietveld refinement;Aurivillius phases
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 22 Sep 2004
Last Modified: 19 Sep 2010 04:16
URI: http://eprints.iisc.ernet.in/id/eprint/2003

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