| 초록 |
The effect of in-plane epitaxial strain on the dielectric permittivity and polarization of four perovskite oxides (ABO3): BaTiO3 (BTO), CaTiO3 (CTO), PbTiO3 (PTO), SrTiO3 (STO) is investigated by Density-Functional Theory (DFT) based on pseudopotentials and a plane-wave basis. The behaviors of these materials with epitaxial strain were explained by A-site effect which has two-folded nature - electronic and volume effects. We found that the difference in phase diagrams with misfit strain of the materials has its origin in the different degrees of hybridization between A-site-p and O-2s orbitals. The volume effect, which is caused by the various A-atom effective radii, leads to the difference in the phase transition mechanisms of these perovskite oxides. The phase transition mechanism, either purely displacive in CTO and STO or mixed with order-disorder in BTO and PTO, determines the dielectric behavior of the strained perovskites near the phase transition. |
