Complex impedance, dielectric constant, electric modulus, and conductivity analysis of Cd doped ZnO nanostructures at high temperatures

Abstract

Cd-doped zinc oxide (ZnO) nanostructures with a standard formulation Z n ( 1 − x ) C d x O (x = 0%, 3%, 6%, and 10%) were fabricated by a co-precipitation technique. The structural and morphological analyses were studied using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The Study of x-ray diffraction investigation indorses the existence of a wurtzite structure with a P 6 3 mc space group in all the samples. Impedance spectroscopy, dielectric measurements, and electrical conductivity at different temperatures of 300–460 K with a frequency range from 20 Hz to 2 MHz were performed using an impedance LCR meter. The complex impedance spectrum ( Z ´ ´ v s Z ´ ) for all samples were fitted with a parallel bulk resistance ( R b ) and capacitance ( C b ) combination circuit. The results of the dielectric measurements indicate that the parameters ε ´ , ε ´ ´ , and tanδ are reduced with the increasing frequency and increase with temperature. The complex electric modulus plots ( M ´ , M ´ ´ ) with frequency have explained the non-Debye type of relaxations mechanism due to interfacial and depolarization. The variation of ac ( σ a c ) conductivity with Cd concentration indicates a gradual increase because the impedance values with Cd-doped decrease. It is confirmed that the activation energies decrease with the doping of Cd concentration. Moreover, ac conductivity was then investigated by Jonscher's power law. Finally, the temperature-dependent exponent s fitted well with the correlated barrier hopping (CHB) conduction. • Cd-doped ZnO nanoparticles with different concentrations were fabricated by the co-precipitation method. • XRD studies revealed the incorporation of Cd into ZnO lattice. • Nyquist plots suggested the negative temperature coefficient of resistance behaviour. • The influence of Cd-doping on the electrical behaviour of ZnO was reported.