Mechanical stability of TiO<sub>2</sub> polymorphs under pressure: ab initio calculations
Koči, L; Kim, D Y; de Almeida, J S; Mattesini, M; Isaev, E; Ahuja, R; Koči, L; Condensed Matter Theory Group, Physics Department, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden; Kim, D Y; Condensed Matter Theory Group, Physics Department, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden; de Almeida, J S; Condensed Matter Theory Group, Physics Department, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden; Mattesini, M; Departamento de Física de la Tierra, Astronomía y Astrofísica I, Universidad Complutense de Madrid, E-28040 Madrid, Spain; Isaev, E; Condensed Matter Theory Group, Physics Department, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden ; Theoretical Physics Department, Moscow State Institute of Steel and Alloys, 4 Leninskii prospect, Moscow 119049, Russia; Ahuja, R; Condensed Matter Theory Group, Physics Department, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden ; Applied Materials Physics, Department of Materials Science and Engineering, The Royal Institute of Technology, SE-100 44 Stockholm, Sweden
Журнал:
Journal of Physics: Condensed Matter
Дата:
2008-08-27
Аннотация:
First-principles calculations using plane-wave basis sets and ultrasoft pseudopotentials have been performed to study the mechanical stabilities of the rutile, pyrite, fluorite and cotunnite phases of titanium dioxide (TiO<sub>2</sub>). For these polymorphs, we have calculated the equilibrium volumes, equations of state, bulk moduli and selected elastic constants. Compared to the three phases rutile, pyrite and fluorite, the recently discovered cotunnite phase shows the highest c<sub>44</sub> for all pressures considered. Cotunnite also shows the highest bulk modulus amongst the four studied phases at an ambient pressure of B<sub>0</sub> = 272 GPa.
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