Abstract
The Pnma-Imma-I4/mcm phase transitions of SrZrO3 have been successfully observed by measuring the variation of energies of phonon modes as a function of temperature. The squares of phonon mode frequencies, ω02, exhibit a linear relation with temperature, T, on both sides of the phase transitions. An unusual value of -7 of the ratio of ∂(ω02)/∂T below and above the phase transition temperature between Pnma and Imma, was observed compared to the value of -2 expected from the mean field theory. The result can be accounted for in terms of coupling between an optical mode and strain.
