title: General rules for predicting phase transitions in perovskites due to octahedral tilting.
abstract: Recent experiments on several oxide perovskites reveal that they undergo tilt phase transitions to higher-symmetry phases on increasing pressure and that dTc/dP<0, contrary to a general rule previously proposed for such zone-boundary transitions. We show that the negative slope of the phase boundary is a consequence of the octahedra in these perovskites being more compressible than the extra-framework cation sites. Conversely, when the octahedra are stiffer than the extra-framework cation sites, the phase transition temperatures increase with increasing pressure, dTc/dP>0.
authors.affiliation: Virginia Tech Crystallography Laboratory, Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24060, USA. rangel@vt.edu
authors.forename: R J
authors.initials: RJ
authors.lastname: Angel
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: N L
authors.initials: NL
authors.lastname: Ross