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Landau Theory Applied to Transitions in BaCeO 3 and PrAlO 3
Author(s) -
Darlington C. N. W.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199709)203:1<73::aid-pssb73>3.0.co;2-9
Subject(s) - octahedron , landau theory , condensed matter physics , order (exchange) , phase transition , tilt (camera) , series (stratigraphy) , materials science , physics , statistical physics , crystallography , chemistry , mathematics , crystal structure , geology , geometry , finance , economics , paleontology
The perovskites BaCeO 3 and PrAlO 3 undergo a series of phase transitions in which the oxygen octahedra become tilted about 〈100〉 pseudocubic directions. The sequences are unusual in that the number of pseudocubic components of octahedral tilt increase as temperature is raised. Landau theory is applied to both systems. In order to reproduce the sequences, a temperature dependence is given to one of the fourth‐order coefficients in the expansion. The potentials used reproduce the transition temperatures and the order of the transitions.