Conservation of dielectric constant upon amorphization in perovskite oxides

TL;DR

This study shows that amorphous RAO₃ oxides maintain similar dielectric constants to their crystalline perovskite phases due to disorder-activated polar responses, despite reductions in ionic charges.

Contribution

It demonstrates that amorphization does not significantly alter the dielectric constant in RAO₃ oxides, revealing a new understanding of dielectric behavior in disordered materials.

Findings

Amorphous RAO₃ oxides have similar dielectric constants as their crystalline counterparts.

Disorder-activated polar modes compensate for reduced ionic charges.

Density-functional perturbation theory effectively models dielectric response in amorphous oxides.

Abstract

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 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.