Origin of octahedral tilting in orthorhombic perovskites

• The adopted crystal structure of the ABO(3) perovskites is determined by the balance between the interaction of the semicore states of the A and B atoms and oxygen ions. Topological considerations show that the structural setup always stabilizes the cubic phase at large pressures, while small or negative pressures favor nonvanishing octahedral tiltings. As an example, we show that the structural distortion in CaSiO3 perovskite is slightly depressed with hydrostatic pressure, but it increases significantly with increasing volume.

Nyckelord

earths lower mantle

casio3 perovskite

thermal-expansion

ab-initio

stability

prediction

pressure

equation

srzro3

mgsio3

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