Cd-doped ZnO nanoparticles synthesized by co-precipitation: insights into structural, optical, and dielectric performance

Abstract

This study describes the preparation of ZnO nanoparticles doped with 5 mol% Cd using a chemical co-precipitation technique, followed by evaluation of their structural, morphological, optical, and dielectric characteristics. XRD analysis confirmed the hexagonal wurtzite ZnO structure with no detectable impurity phases. The average crystallite size decreased from 42.94 nm for pure ZnO to 30.91 nm for Cd-doped ZnO. FTIR spectra revealed characteristic Zn–O vibrations and Cd-induced modifications of the ZnO lattice. EDX analysis confirmed the presence of Zn, O, and Cd in the doped sample, with compositions of 52.70 at.% Zn, 45.70 at.% O, and 1.60 at % Cd, verifying successful Cd incorporation into the ZnO matrix. Nearly spherical and uniformly distributed nanoparticles with an average grain size of around 46 nm were visible in SEM images. Optical characterization showed that the band gap energy decreased from 3.35 eV in pure ZnO to 3.26 eV in Cd-doped ZnO upon Cd inclusion, while also increasing the photoluminescence intensity and producing a strong near-band-edge emission. Dielectric measurements exhibited typical dielectric dispersion behaviour, with Cd-doped ZnO displaying an enhanced dielectric constant and higher AC conductivity compared with pure ZnO. These results confirm that Cd doping significantly modifies and improves the functional properties of ZnO nanoparticles, demonstrating their possible application in dielectric devices, energy-storage systems, and nanoelectronic applications.