Theoretical study on martensitic-type transformation of rutile, columbite, and baddeleyite phase of TiO₂

¹ Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University Xi'an 710069, China
² Stanford Research Computing Center, Stanford University - Stanford, CA 94305, USA

^(a) jiangzy@nwu.edu.cn (corresponding author)
^(b) zyzhang@stanford.edu

Received: 11 October 2020
Accepted: 12 February 2021

Abstract

The martensitic-type phase transition pathways between any two among rutile, columbite-type, and baddeleyite-type phase of TiO₂ are studied with linear interpolation and G-SSNEB methods within first-principles calculations. Our theoretical simulations reveal that the reverse transition from the rutile to the columbite-type phase should be realized easily at above 550 °C because its theoretical potential barrier of phase transition is basically the same as the average kinetic energy of molecule unit at 550 °C. The phase transitions of columbite-type to baddeleyite-type and rutile to baddeleyite-type are two-step transitions in which the crystal volume should be compressed to a certain extent at first, and then the atoms of alternative (200) and (002) crystal plane begin to shuffle, at the same time the crystal cell begins to shear. Their phase transition resistance originates from the crystal shear rather than atomic shuffles of alternative (200) and (002) crystal plane. Our theoretical calculations give the reason why the baddeleyite-type crystal phase cannot return to rutile phase but to columbite-type phase after depressurization.