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arXiv · 2507.14514

Possible Orthorhombic Phase of Ta$_2$O$_5$ under High Pressures

Yan Gong·HuiMin Tang·Yong Yang·Yoshiyuki Kawazoe
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Abstract

A potential orthorhombic phase of Ta$_2$O$_5$, designated as Y-Ta$_2$O$_5$, is predicted under high-pressure conditions through density functional theory (DFT) calculations combined with structural search algorithms. This phase, consisting of four formula units per unit cell ($Z = 4$), exhibits the highest known Ta-O coordination numbers. Y-Ta$_2$O$_5$ is found to be the most energetically favorable form of Ta$_2$O$_5$ in the pressure range of approximately 70 GPa to at least 200 GPa. Both standard DFT-GGA and higher-accuracy GW calculations reveal that Y-Ta$_2$O$_5$ is a wide bandgap semiconductor with a direct bandgap. Additionally, nuclear quantum effects (NQEs) introduce nontrivial corrections to external pressure at fixed volumes, underscoring their significance in high-pressure phase stability analyses.

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Yan Gong, HuiMin Tang, Yong Yang, Yoshiyuki Kawazoe. 2025-07-19. Possible Orthorhombic Phase of Ta$_2$O$_5$ under High Pressures. https://arxiv.org/abs/2507.14514

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