A new anomalous relaxation function and electrical properties of disordered materials

A new anomalous relaxation function phi *(t) = exp [ - t/tau*] is obtained, where tau* = tau(g)/i((1-g)), i = root-1. The exponent g is the phase or loss factor, related to the impedance loss through the tan(delta(p)) at the impedance loss peak frequency omega(p) = 1/tau(g). Origin of the g(delta(p)) is attributed to the free energy barrier variations because of the non-periodic potential and many-body interactions of the mobile charges in disordered material medium. The phi*(t) has the stretched exponential behavior and the phase factor g(delta(p)) is responsible for the stretching of relaxation time. Many experimentally known features of the real part, sigma'(omega), of the complex conductivity sigma*(omega) and the imaginary part, epsilon "(omega), of the complex permittivity epsilon*(omega) are explained satisfactorily. The experimental data of doped crystalline and glassy materials are analysed and results show excellent agreement. (C) 2000 Elsevier Science S.A. All rights reserved.