Specific heat of Ba x Sr 1—x TiO ₃ ferroelectric perovskites

The specific heat of an anharmonic BaxSr1—xTiO3 ferroelectric crystal is calculated in its paraelectric phase from the Silverman–Joseph Hamiltonian augmented with fourth order phonon coordinates using double time Green's functions. The soft mode contribution to specific heat is described by appropriate Einstein terms. The variation of specific heat with temperature and defect parameters is discussed. The effect of defects on specific heat can be observed in the presence of anharmonicity. Around the Curie temperature the Cochran soft mode is held to be responsible for the anomalous behaviour of specific heat.