Ground state and properties of ferroelectric superlattices based on crystals of the perovskite family

• Published in: Physics of the solid state Vol. 52; no. 7; pp. 1448 - 1462
• Main Author: Lebedev, A. I.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.07.2010; Springer
• Subjects: Crystals; Dielectrics; Magnetism and Ferroelectricity; Perovskite; Physics; Physics and Astronomy; Solid State Physics; Structure; Brillouin Zone; Paraelectric Phase; Polarization Vector; Phonon Spectrum; Structural Distortion
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783410070218

The crystal structure of the ground state of ten free-standing ferroelectric superlattices based on crystals with the perovskite structure (BaTiO 3 /SrTiO 3 , PbTiO 3 /SrTiO 3 , PbTiO 3 /PbZrO 3 , SrZrO 3 /SrTiO 3 , PbZrO 3 /BaZrO 3 , BaTiO 3 /BaZrO 3 , PbTiO 3 /BaTiO 3 , BaTiO 3 /CaTiO 3 , KNbO 3 /KTaO 3 , and KNbO 3 /NaNbO 3 ) was calculated from first principles within the density functional theory taking into account criteria for stability of the structures with respect to acoustic and optical distortions. It was shown that the ground state in all the considered superlattices corresponds to the ferroelectric phase. It was found that the polarization vector has a tendency toward a tilt to the plane of the superlattice layers, which makes it possible to decrease the electrostatic and elastic energy in the superlattices consisting of materials with different ferroelectric properties. The importance of the inclusion of structural distortions due to unstable phonons at the Brillouin zone boundary, which, in a number of cases, lead to significant changes in ferroelectric and dielectric properties of the superlattices, was demonstrated.