Nonmonotonic Composition Dependence of the Dielectric Response of Ba1-xCaxZrO3

摘要: We use first-principles density functional theory calculations to investigate the dielectric response of BaZrO 3 based perovskites. In this study we have substituted Ca for Ba over a range compositions understand what causes recently reported (Levin et al., J. Solid State Chem. 2003, 175, 170) nonmonotonic 1-x x ZrO (BCZ). show that in all studied there appear two new sets IR active phonon modes increase constant e. One set occurs below normal A-O modes, due "rolling cation" motion about its O 12 cage. The second between and B-O mode frequencies, caused by displacement along one Cartesian direction. As more is added BCZ, Ca-Ca interactions increase, leading displacements three directions, stronger Ca-O bonds increased Ο 6 tilts. Such structural deformations decrease These effects are responsible anomalous compositional dependence BCZ response.