Thermally driven structural phase transformation and dislocation density of CdS nanoparticles precipitated without surfactant in KOH alkaline medium

The present research demonstrates a detailed discussion of the effect of annealing temperature on the structural transformation and surface morphology of the CdS nanoparticles synthesized using the precipitation method without surfactant in KOH alkaline medium. The annealing temperature used was in the range of 160 - 480 degrees C. The sample's structural, functional group, and morphological properties were investigated using XRD, FTIR, and SEM techniques. XRD analysis reveals that the CdS has gradually been transformed from the pure cubic to hexagonal polycrystalline structure and improved crystallinity upon increasing the temperature. Besides, the estimated crystallite size and dislocation density parameters were calculated using the established Debye-Scherrer equation. The average crystallite size was in nano-dimension and increased gradually with temperature. The FTIR spectra indicate that the characteristic vibration band of CdS emerged in the lower wavenumber region of 650 and 500 cm(-1), and the band becomes stronger as the temperature rises. Also, the SEM images demonstrate that the CdS exhibits uniform spherical morphology, and the particle size grows more significant at elevated temperatures. The improved crystallinity and structural properties tuning ability against temperature allow beneficial optical applications as solar cells, photocatalysts, nonlinear optics, light-emitting diodes, and optoelectronic devices.