Field dependent dielectric behaviour of Ba₁_-xCa_xTiO₃ferroelectric perovskites

Abstract

The electric field dependence of complex dielectric constant of Ba₁_-xCa_xTiO₃ferroelectric crystal in paraelectric phase has been studied by using the method of double times thermal Green’s function and Kubo formalism. A general expression is derived from the Silverman-Joseph Hamiltonian by taking into account the change of mass as well as harmonic force constant between impurity atom and host lattice atoms with fourth order phonon coordinates. The frequency, temperature and electric field dependent dielectric constant of Ba₁_-xCa_xTiO₃ crystal has been investigated. The dielectric constant increases with increase in temperature as well as with the applied electric field. The results are compared with the previous experimental and theoretical results.