Electric field dependent microwave losses in Ba x Sr 1-x TiO 3 perovskites

Ashish Kukreti, Ashok Kumar, U Naithani
2008 Indian Journal of Pure & Applied Physics   unpublished
The electric field dependent microwave loss of anharmonic Ba x Sr 1-x TiO 3 perovskites has been calculated in its para electric phase from the Silverman Joseph Hamiltonoian augumented with fourth order phonon coordinates using double time Greens functions. The results are used to obtain an expression for the frequency and temperature dependence of dielectric loss at microwave frequencies due to impurity and anharmonic scattering. The loss tangent consists of a contribution which is quadratic
more » ... hich is quadratic in applied biasing and field independent. The variation of tanδ with applied field is noticeable in the vicinity of Curie temperature. In the higher temperature region, the electric field effect ceases and the increase in loss arises mainly due to higher order anharmonic terms.