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MM: Fachverband Metall- und Materialphysik

MM 62: Microstructure and Phase Transformations - nucleation kinetics and pressure effects

MM 62.5: Vortrag

Donnerstag, 23. März 2017, 12:45–13:00, IFW B

Pressure-induced ferroelastic phase transition in SnO₂ from density functional theory — •Lei Yang, Weiliu Fan, Yanlu Li, Lei Wei, and Xian Zhao — Shandong University

We studied the high-pressure ferroelastic transition of rutile- to CaCl₂-type SnO₂ within density functional theory and Landau free energy theory. Softening mechanism of B_1g mode (order parameter Q) and the coupling mechanism between the soft B_1g mode and the soft transverse acoustic (TA) mode (strain ε) are clarified by calculating Landau energy map around the ground state. It is found that the Sn-O-Sn bending induced soft B_1g mode effectively reduces the excess energy increase caused by bond stretching, which however always leads to SnO₆ octahedral distortion. The octahedral distortion is subsequently minimized by lattice distortion strain ε, which interacts with the soft B_1g mode to further increase the stability of system.