Dielectric relaxation in Ge1−xSe2Pbx (x=0, 0.2 and 0.6) nano-crystalline system

Measurements of the ac conductivity and the dielectric loss of Pb modified Ge1−xSe2Pbx disordered system (x=0, 0.2 and 0.6) have been carried out in the frequency range 100 Hz–20 kHz and at temperature from 303 to 433 K. The virgin and the x=0.2 samples data shows a normal behavior according to the relation σac(ω)=AωS. However, the x=0.6 sample behaves differently. The exponent(s) measured for the two modified samples shows sub-linear relation depending on the temperature of measurements. The experimental results of the highly modified sample are interpreted in terms of the coexistence of two parallel conduction mechanisms; the predominance of each depends on both temperature and frequency.