High-pressure phase transitions of Mg2Ge and Mg2Sn: First-principles calculations

• Published in: Physica. B, Condensed matter Condensed matter, 2011-04, Vol.406 (9), p.1789-1794
• Main Authors: Yu, Fei, Sun, Jiu-Xun, Chen, Tai-Hong
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Density functional theory; Electron density of states and band structure of crystalline solids; Electron states; Exact sciences and technology; General theory; High pressure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Phase transition; Physics; Semiconductor compounds; Structure of solids and liquids; crystallography
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2011.02.029

Phase transitions of the anti-fluorite compounds Mg2Ge and Mg2Sn under high pressure were investigated using the first-principles plane-wave method within the pseudopotential and generalized gradient approximations. The calculated results show that Mg2Ge and Mg2Sn undergo two first-order phase transitions at high pressure and the sequence of the pressure-induced phase transitions is from the anti-fluorite to the anti-cotunnite, and then to the Ni2In-type structure. The high pressure behaviors of Mg2Ge and Mg2Sn are similar to Mg2Si and the isostructural alkali-metal oxide Li2O. Moreover, the electronic and optical properties of both the anti-fluorite and the high-pressure phases are presented.