Table of Contents
Physics Research International
Volume 2016 (2016), Article ID 9475740, 10 pages
http://dx.doi.org/10.1155/2016/9475740
Research Article

Study of Dielectric Properties and Ultrasonic Attenuation in KDP-Type Ferroelectrics

USIC, HNB Garhwal University, Srinagar, Garhwal, Uttrakhand 24 6174, India

Received 12 October 2015; Accepted 19 January 2016

Academic Editor: Sergey B. Mirov

Copyright © 2016 Vijay Singh Bist and Narayan Singh Panwar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The soft mode dynamical model has been used to study dielectric properties and ultrasonic attenuation in KDP-type ferroelectric crystals. The model Hamiltonian proposed by Blinc and Zeks has been modified by considering lattice anharmonicity up to fourth-order. The correlations appearing in the dynamical equation have been evaluated using double-time thermal retarded Green’s functions method and Dyson’s equation. Without any decoupling, the higher order correlations, appearing in the dynamical equation, have been evaluated using the renormalized Hamiltonian. The expressions for collective frequencies, width, dielectric constant, ultrasonic attenuation, and tangent loss have been calculated. The dielectric properties and ultrasonic attenuation strongly depend on the relaxational mode behavior of stochastic motion of H2PO4 group in KDP-type ferroelectrics. By fitting model values of physical quantities, the temperature dependence of and for different value of four-body coupling coefficient and dielectric constant and loss tangent has been calculated. The calculated and observed results have been found in good agreement.