Field dependent dielectric behaviour of BaxSr1-xTiO3 perovskites

Using the method of double time thermal Green's function and Kubo formalism, a general expression has been derived for the electric field dependence of the complex dielectric constant of BaxSr1-xTiO3 ferroelectric crystal in the paraelectric phase from the Silverman-Joseph Hamiltonian augmented with fourth order phonon co-ordinates. The change of mass as well as harmonic force constant between impurity atom and host lattice atoms are taken into account. The frequency, temperature and electric field dependent dielectric constant of BaxSr1-xTiO3 crystal has been discussed. Dielectric constant increases with increase of applied field. The results are compared with previous experimental and theoretical results. (author)