The crystal structure of perovskite based Ba(Ce0.8Zr0.2)O-3 has been determ
ined by X-ray and neutron powder diffractions. The space group has been est
ablished by Rietveld refinement. Our final analysis indicates that the spac
e group of Ba(Ce0.8Zr0.2)O-3 is Imma with an anti-phase oxygen octahedral t
ilting along the two crystallographic axes. At a temperature above the tran
sition, 1273 K, the high temperature prototype phase is found to be cubic P
m (3) over barm. (C) 2001 Elsevier Science Ltd.