Virginia TechAngel, Ross J.Zhao, J.Ross, Nancy L.2013-12-102013-12-102005-07-08Angel, RJ ; Zhao, J ; Ross, NL, Jul 8, 2005. “General rules for predicting phase transitions in perovskites due to octahedral tilting,” PHYSICAL REVIEW LETTERS 95(2): 025503. DOI: 10.1103/PhysRevLett.95.0255030031-9007http://hdl.handle.net/10919/24483Recent experiments on several oxide perovskites reveal that they undergo tilt phase transitions to higher-symmetry phases on increasing pressure and that dT(c)/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, dT(c)/dP > 0.en-USIn Copyrightx-ray-diffractioncrystal-chemistrygdfeo3-type perovskitespowderdiffractionpressuredistortionlaalo3mgsio3gpabehaviorPhysicsArticle - Refereedhttp://link.aps.org/doi/10.1103/PhysRevLett.95.025503https://doi.org/10.1103/PhysRevLett.95.025503