Lattice Thermal Properties of Disordered Alloys: A Theoretical Approach

Abstract

The theoretical study of lattice thermal properties for disordered system is always a difficult task due to presence of disordered off-diagonal terms in the dynamical matrices. The presence of off-diagonal disorder in force constants cannot be dealt within a single site mean field approximation. Very few detailed firstprinciples study has been done for phonons in disordered systems. We shall present a theoretical formulation to lattice thermal properties of a configurational averaged disordered alloy. We have introduced a Kubo-Greenwood type formula which relates the thermal conductivity to (heat) current-current correlation function. Augmented space formalism introduced by one of us [2], takes into account configuration fluctuation over a large local environment. Detailed theoretical framework for the calculation of configuration-averaged lattice thermal conductivity was developed by two of us in previous communication [1]. In the present paper we have extended the methodology for body-centered cubic disordered alloys and applied it to study the frequency, temperature and concentration dependence thermal conductivity of 1 x x Fe Cr − .