Eur. Phys. J. AP 9, 1-9 (2000)
https://doi.org/10.1051/epjap:2000192

A neutron diffraction study of BaCe_xZr_1−xO₃

¹ Laboratoire d'Electrochimie et de Physicochimie des Matériaux et Interfaces (UMR INPG-CNRS), ENSEEG B.P. 75, 38402 Saint Martin d'Hères, France
² Institut Laue Langevin, Chemin des Martyrs, 38000 Grenoble, France

Corresponding author: Thierry.Pagnier@lepmi.inpg.fr

Received: 6 May 1999
Revised: 17 September 1999
Accepted: 20 October 1999
Published online: 15 January 2000

Abstract

High resolution neutron diffraction patterns of BaCe_xZr_1−xO₃ (x = 0, 0.1, 0.4, 0.8) were obtained at various temperatures. The phase diagram that was deduced from Raman measurements has been confirmed. Structural transitions occur in a fixed order Pnma-Imma- Rc-Pm3m as a function of temperature or composition. For BaCeO₃, the large volume change that has been previously claimed at the Imma-Rc transition has been revisited and found inconsistent. For a given composition, the cell volume increases when temperature increases, but the MO₆ (M=Ce-Zr) octahedron volume decreases. It is shown that the ratio of the cell volume to the octahedron volume is a good indicator of the phase transitions. Transitions occur at fixed values (5.77, 5.80 and 6 for the Pnma-Imma, Imma-Rc and Rc-Pm3m transitions respectively) independently of composition.