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.
Nanocrystalline p-type semiconductor copper aluminum oxide (CuAlO2) has been synthesized by mechanical alloying using freshly prepared Cu2O and alpha-AlO2O3 nanocrystals in toluene medium. A study on structural property performed with different alloying and post annealing durations, by X-ray diffraction (XRD) reveals the formation of single phase with average crystallite size approximately 45 nm. Optical absorbance onset at 364.5 nm confirms its wide band gap nature (E(g) = 3.4 eV) and the fluorescence emission behaviour (390 nm) confirms its direct band type transition. The activation energy for electrical conduction has been calculated by Arrhenius plots using impedance measurement. Both grain and grain boundary conductivity takes place with almost equal activation energies of approximately 0.45 eV. The paper discusses synthesis, structural, optical and electrical properties of delafossite CuAlO2 in detail.
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