Dielectric relaxation studies of nanocrystalline CuAlO₂ using modulus formalism

Abstract

Transparent semiconductor CuAlO₂ in nanodimension was prepared by mechanical alloying of Cu₂O and α-Al₂O₃ powders in toluene medium. The formation of single phase CuAlO₂ with an average crystallite size of 45 nm was confirmed by x-ray diffraction analysis. The nanocrystalline nature of CuAlO₂ was confirmed by atomic force microscopy. Frequency-dependent dielectric property measurements and the relaxation behavior were studied using impedance spectroscopy. Dielectric relaxation time estimated from the modulus curves was found to be decreasing with increase in temperature. The existence of stretched exponent parameter β <1 in the present nanocrystalline CuAlO₂ implies non-Debye type relaxation behavior in this material.