We present ab initio density-functional and self-interaction-corrected calculations on the structure, electronic properties, k=0 vibrational modes, and static dielectric properties of the crystalline high-kappa distorted-perovskite oxide DyScO3. We find a gap of 6.1 eV (close to 5.7-5.9 eV experimentally) and a participation of both Sc and Dy in the mixed ionic-covalent bonding to O by means of which they both contribute to realizing the orthorhombic rotationally distorted equilibrium structure. In accordance with their role in the electronic structure, both Sc and Dy share essentially the same effective charge anomaly, at variance with other perovskites where anomalous effective charges are exclusive of either cation (e.g., La in LaAlO3 and Ti in BaTiO3). The orientationally averaged dielectric constant kappa similar or equal to 21-24 is in good agreement with experiment. The dielectric response is dominated by the vibrational ionic component, with a dominant mode featuring Sc-O units vibrating against the Dy sublattice. We provide details about the full (IR, Raman, and silent) vibrational spectrum.
|Titolo:||Cation charge anomalies and high-kappa dielectric behavior in DyScO3: Ab initio density-functional and self-interaction-corrected calculations|
|Autori:||Delugas P; Fiorentini V; Filippetti A; Pourtois G|
|Data di pubblicazione:||2007|
|Digital Object Identifier (DOI):||10.1103/PhysRevB.75.115126|
|Appare nelle tipologie:||1.1 Journal article|