Experimental and Theoretical Studies on α‑In2Se3 at High Pressure

• Published in: Inorganic chemistry Vol. 57; no. 14; pp. 8241 - 8252
• Main Authors: Vilaplana, Rosario, Parra, Samuel Gallego, Jorge-Montero, Alejandro, Rodríguez-Hernández, Plácida, Munoz, Alfonso, Errandonea, Daniel, Segura, Alfredo, Manjón, Francisco Javier
• Format: Journal Article
• Language: English
• Published: American Chemical Society 16-07-2018
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.8b00778

α­(R)-In2Se3 has been experimentally and theoretically studied under compression at room temperature by means of X-ray diffraction and Raman scattering measurements as well as by ab initio total-energy and lattice-dynamics calculations. Our study has confirmed the α (R3m) → β′ (C2/m) → β (R3̅m) sequence of pressure-induced phase transitions and has allowed us to understand the mechanism of the monoclinic C2/m to rhombohedral R3̅m phase transition. The monoclinic C2/m phase enhances its symmetry gradually until a complete transformation to the rhombohedral R3̅m structure is attained above 10–12 GPa. The second-order character of this transition is the reason for the discordance in previous measurements. The comparison of Raman measurements and lattice-dynamics calculations has allowed us to tentatively assign most of the Raman-active modes of the three phases. The comparison of experimental results and simulations has helped to distinguish between the different phases of In2Se3 and resolve current controversies.