Temperature Dependence of Permittivity and Dissipation Factor of Potassium Dihydrogen Arsenate Crystal using Green Function Formalism

Abstract

Potassium Dihydrogen Arsenate(KDA)crystal is a ferroelectric crystal[1]. Earlier model Hamiltonian is modified with addition of phonon anharmonic, extra spin-lattice, four spin coupling and external electric field terms. Employing Zubarev's Green function formalism[2] formulae for ferroelectric mode frequency, permittivity and dissipation factor are derived. Model values for KDA crystal are fitted and thermal variations of ferroelectric mode frequency, dielectric constant and loss tangent are obtained. Theoretical variations are compared with experimental results for KDA crystal reported by others.