Characterization of CdO nanoparticles prepared by co-precipitation method under different pH and calcination temperatures

Pure CdO nanoparticles were prepared by co-precipitation method at different calcination temperatures (550, 600, 650, and 700 °C) and different pH (10, 11, 12, and 13). This investigation is intended to study the effect of the different preparation conditions on the physical properties of the obtained CdO nanoparticles. The crystal structure, morphology, elemental content, and functional groups of the CdO nanoparticles were investigated using X-ray powder diffraction (XRD), Transmission electron microscopy (TEM,) Energy-dispersive X-ray (EDX), and Fourier transform Infrared (FTIR), respectively. The crystallinity and the particle size of CdO nanoparticles were both enhanced with the increase in temperature. As for pH variation, the samples prepared at pH = 10 and 11 have shown a multiphase XRD spectrum, attributed to the incomplete reduction in CdO. The EDX and FTIR results confirmed the stoichiometry of the samples and the existence of Cd–O vibrational bonds. The optical properties were studied using room temperature UV–Vis and PL spectroscopies. The energy bandgap showed a decrease with temperature and was found particle size-dependent. The PL emission spectra showed deep level violet and blue emissions with maximum intensities at pH = 12 and T = 650 °C. The magnetic properties were examined using M-H measurements. The curves showed a combination of diamagnetic and ferromagnetic contributions for all samples. The Differentiation-Deconvolution-Selective Integration (DDSI) method was utilized to isolate the ferromagnetic contribution and determine the magnetic parameters. The broad particle size distribution of the prepared nanoparticles is considered to be the key factor in understanding the magnetic behavior of the samples. Accordingly, this work reveals that the structural, optical, and magnetic properties of CdO nanoparticles can be tuned by applying different preparation conditions allowing for numerous applications.