Dielectric and Piezoelectric Properties of BiFeO 3 from Atomistic Simulations

GRAF, MÓNICA ELISABET; SEPLIARSKY, MARCELO CLAUDIO; MACHADO, RODRIGO; STACHIOTTI, MARCELO GABRIEL

Porto

Encuentro; 13th European Meeting on Ferroelectricity; 2015

Recently we have investigated the structural and polar properties of BiFeO3 at finite temperature using an atomistic model fitted to first-principles calculations [1]. Molecular dynamics simulations showed a direct transition from the low-temperature R3c ferroelectric phase to the Pbnm orthorhombic phase without evidence of any intermediate bridging phase between them. The Pbnm high-temperature phase was characterized as antiferroelectric by the presence of two sublattices with opposite polarizations, and the characteristic double-hysteresis loop under the action of an external electric field [1]. One advantage of our theoretical approach is the possibility to calculate single crystal properties, which are important to determine the anisotropy of material properties. In this work we use the developed model to investigate dielectric and piezoelectric properties of BiFeO3 as function of the temperature and strain. To this purpose,we calculate for each phase the coefficients along the corresponding crystallographic directions.[1] Phase transitions and antiferroelectrcity in BiFeO 3 from atomic-level simulations, Graf M, Tinte S, Sepliarsky M, and Stachiotti MG, Physical Review B, 90, 184108 (2014).