We report calculations indicating that amorphous RAO(3) oxides, with R and A trivalent cations, have approximately the same static dielectric constant as their perovskite crystal phase. The effect is due to the disorder-activated polar response of nonpolar crystal modes at low frequency, which compensates a moderate but appreciable reduction of the ionic dynamical charges. The dielectric response was studied via density-functional perturbation theory. Amorphous samples were generated by molecular dynamics melt-and-quench simulations.
|Titolo:||Conservation of dielectric constant upon amorphization in perovskite oxides|
|Autori:||Delugas P; Fiorentini V; Filippetti A; Pourtois G|
|Rivista:||PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS|
|Data di pubblicazione:||2007|
|Digital Object Identifier (DOI):||10.1103/PhysRevB.76.104112|
|Appare nelle tipologie:||1.1 Journal article|