Unstability and phase transition splitting in perovskites at non-ferroelectric structural phase transitions

This report considers the critical behaviour of perovskites near non-ferroelectric phase transition taking into account the elastic degrees of freedom. It is unambigously shown that only the first-order transitions may occur in this type of crystal. This paper points out that splitting of continuous phase transition into two first order transitions with non-Landau intermediate phase may take place. Estimations given in the work allowing to look for materials in which such splitting is possible purposefully.