Electronic structure and ferroelectric behavior of lanthanum substituted bismuth titanate

R. MACHADO; STACHIOTTI, MARCELO

Iguazu Falls, Brasil

Congreso; 11 International Meeting on Ferroelectricity; 2005

Universidade Federla de Sao Carlos - Universidad Nacional de La Plata

The effect of substituting La for Bi atoms in Bi4Ti3O12 is investigated from first-principles calculations using the full-potential linearized augmented plane wave (LAPW) method. A comparative study of the electronic structure and lattice-dynamics properties of Bi4Ti3O12 and La2Bi2Ti3O12 shows the role of covalent bonding in the ferroelectric instabilities. The displacement patterns displayed by unstable zone-center phonon modes and a detailed analysis of the orbital contribution to the valence band illustrate the importance of Bi (La)-O interactions for the ferroelectric behavior of the doped material.