We report calculations indicating that amorphous RAO3 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 non-polar 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.
@article{arxiv.0803.0478,
title = {Conservation of dielectric constant upon amorphization in perovskite oxides},
author = {Pietro Delugas and Vincenzo Fiorentini and Alessio Filippetti and Geoffrey Pourtois},
journal= {arXiv preprint arXiv:0803.0478},
year = {2009}
}