Influence of Temperature on AC Conductivity of Nanocrystalline CuAlO2

Nanocrystalline CuAlO2 was synthesized by mechanical alloying of Cu2O and α-Al2O3 powders in the molar ratio of 1:1 for 20 h in toluene medium with tungsten carbide balls and vials using planetary ball mill. The ball milling was carried out at 300 rpm with a ball to powder weight ratio of 10:1 and then annealed at 1373 K in a platinum crucible for 20 h to get CuAlO2 phase with average crystallite size 45 nm. Complex impedance spectroscopic measurement in the frequency region 1 Hz to 10 MHz between the temperatures 333 to 474 K was carried out for nanocrystalline CuAlO2 sample. The obtained complex impedance data was analyzed for that of AC conductivities, correlations between DC and AC conductivities and crossover frequencies (fco) for all the measured temperatures. Barton, Nakajima and Namikawa (BNN) relation was applied to understand the correlation between DC and AC conductivities. The observed experimental results were discussed in the paper.