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arXiv · 2506.04936

Pressure-Induced Decomposition of beta-SnWO4

Sergio Ferrari·Daniel Diaz-Anichtchenko·Pablo Botella·Jordi Ibáñez·Robert Oliva·Alexei Kuzmin·Alfonso Muñoz·Frederico Alabarse·Daniel Errandonea
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Abstract

This study reports the decomposition of beta-SnWO4 into Sn, SnO2, and WO3 induced by static compression. We performed high-pressure synchrotron powder angle-dispersive X-ray diffraction measurements and found that decomposition occurs at a pressure of 13.97(5) GPa and is irreversible. This result contradicts a previous study that, based on density-functional theory calculations and crystal-chemistry arguments, predicted a pressure-driven transition from beta-SnWO4 to alpha-SnWO4. Our analysis indicates that the observed decomposition is unrelated to mechanical or dynamic instabilities. Instead, it likely stems from frustration of the beta-alpha transition, as this transformation requires a change in Sn coordination from octahedral to tetrahedral. The assessment of how pressure influences the volume of the unit cell provided an accurate determination of the room-temperature pressure-volume equation of state for beta-SnWO4. Furthermore, the elastic constants and moduli, as well as the pressure dependence of Raman and infrared modes of beta-SnWO4, were derived from density-functional theory calculations. Several phonon modes exhibited softening, and three cases of phonon anti-crossing were observed.

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Sergio Ferrari, Daniel Diaz-Anichtchenko, Pablo Botella, Jordi Ibáñez, Robert Oliva, Alexei Kuzmin, Alfonso Muñoz, Frederico Alabarse, Daniel Errandonea. 2025-06-05. Pressure-Induced Decomposition of beta-SnWO4. https://doi.org/10.1016/j.rinp.2025.108304

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