Order-disorder, local structure and precursor effects in BaTiO 3

TINTE, S.; STACHIOTTI, M. G.; SEPLIARSKY, M.; MIGONI, R. L.; RODRIGUEZ, C. O.

FERROELECTRICS

TAYLOR & FRANCIS LTD

Año: 2000 vol. 237 p. 41 - 48

0015-0193

Interatomic potentials are determined in the framework of the nonlinear oxygen polarizabilitymodel to describe the structural behavior of BaTi03. To this purpose, the adiabatic potentialis evaluated for different ferroelectric distortions and the model potential parameters areobtained by comparing with LAPW total energy calculations. The phase diagram as a func-tion of temperature is obtained through constant pressure molecular dynamics simulations,and the non-trivial phase sequence is correctly reproduced. Calculations of the pair distribu-tion function indicate that order-disorder is the dominant dynamics at all transitions. Precur-sor clusters with local polarizations correlated along Ti-0 chains are determined to persistseveral hundreds of degrees above the para-ferroelectric transition.