Theoretical investigation, of Cochran’s mode frequency, and electrical permittivity of KH2AsO4 (KDA) crystal by using Zuberav’s statistical Green function technique

Abstract

Potassium dihydrogen arsenate KH2AsO4 crystal is investigated theoretically. It is an order disorder type of ferroelectrics. Another type is displacive like SrTiO3, LiNbO3, etc. The earlier model Hamiltonian (PLCM) is modified by adding some extra terms into it. Applying two time thermal dependent statistical Green function technique employing modified model, formulae for, Cochran’s mode frequency, electrical permittivity, Curie temperature, tangent delta, shift and width, are derived for the potassium dihydrogen arsenate crystal. Model values are fitted for KH2AsO4 crystal to obtain variation with temperature. Results are compared with experimental variations shown by Kaminow et al. [4] for the alkali phosphate potassium dihydrogen arsenate KH2AsO4 crystal.