Studies on ac response of zinc oxide pellets

摘要: The ac responses of the ZnO pellets have been studied by measurements (impedance, capacitance and phase angle) over temperature range 300–435 K. conductivity is observed to be proportional ωs, where ω angular frequency exponent s a temperature- frequency-dependent parameter. Based on existing theories conduction, it has concluded that for low region (20 Hz–2 kHz), dominant conduction mechanism in multihopping at all temperatures, whereas high (500 kHz–2 MHz), small polaron tunneling model pellets. Activation energies processes are estimated 0.028–0.277 eV which found vary with signal. These results consistent hopping model. dielectric loss tangent dependent both temperature. Such dependences explained taking into account equivalent circuit comprising frequency-independent capacitive element parallel temperature-dependent resistive element, series value resistance. Impedance spectroscopy studies show single semicircular arcs complex impedance spectra temperatures K, their centres lying below real axis particular angle depression indicating multirelaxation behaviour