Post-Cotunnite phase of TeO2

TL;DR

This study uses first-principles calculations to identify a new high-pressure phase of TeO2, revealing phase transitions and re-entrance at extreme pressures, aligning well with experimental data.

Contribution

The paper predicts the structure of the post-cotunnite phase of TeO2 and details its phase transition pressures using density-functional theory and structure searching techniques.

Findings

Transition from cotunnite to post-cotunnite at 130 GPa

Post-cotunnite structure has P2_1/m symmetry

Re-entrance of cotunnite phase at 260 GPa

Abstract

We have used first-principles density-functional-theory methods with a random-structure-searching technique to determine the structure of the previously unidentified post-cotunnite phase of TeO2. Our calculations indicate a transition from the cotunnite to post-cotunnite phase at 130 GPa. The predicted post-cotunnite structure has P2_1/m space group symmetry and its calculated x-ray diffraction pattern is in good agreement with the available experimental data. We find that the cotunnite phase re-enters at about 260 GPa.