Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Abstract

Nanocrystalline Cd substituted ZnO nanoparticles with common formula Zn (1-x) CdxO (x = 0%, 3%, 6%, and 10%) were fabricated by a co-precipitation technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to investigate the microstructures and morphology of synthesized nanoparticles at room temperature. The outcome of the x-ray diffraction (XRD) study supports the existence of wurtzite crystal structure for ZnO, and Cd substituted ZnO samples conformed that substituted Cd ions are catching up Zn site. The morphological assessments of the fabricated nanoparticles indicated that the nature of the nanoparticles is a slightly hexagonal and mostly spherical shape with size ranges 46-55 nm. The electric impedance of the samples was measured in a wide range of frequency 100Hz–2MHz at different temperatures (140 K-260 K) using an LCR meter. It was observed that the dielectric constants (ἐ), (ε´´), loss tangent (tanδ), and ac conductivity of pure and Cd substituted ZnO nanoparticles depended on frequency. The calculations of dielectric measurement showed that the parameters (ἐ), (ε´´), loss tangent (tanδ) decreased with the increase in frequency. But the ac conductivity enhanced with the frequency, whereas the values of the above parameters increased with the temperature rise. The dielectric parameters are also found to improve with the increase in Cd concentrations. The correlated barrier-hopping (CHB) model dominated in ac conductivity. The reduction in the bandgap was also observed with Cd concentration.