Role of CeO₂ and calcination temperature on the structural and optical properties of (ZnO) ₁-x/ (CeO₂)ₓ nanocomposites in the UV–visible region

Abstract

This study explores the optical properties of (ZnO)1-x/(CeO2)x nanocomposites within the UV–visible range (250–1000 nm). Two sets of samples were synthesized using a gelatin-based sol-gel method. The first set comprises (ZnO)1-x/(CeO2)x, where x values are 0.0 (pure ZnO), 0.03 (ZCe3), 0.05 (ZCe5), and 0.01 (ZCe10) that calcined at 600 °C for 2 h. The second set consists of (ZnO)0·97/(CeO2)0.03 samples, which were obtained at varying temperatures denoted as ZCe3-700, ZCe3-800, ZCe3-900, and ZCe3-1000 °C. X-ray diffraction (XRD) analysis was employed to investigate the structure of the prepared nanocomposites under different conditions. The XRD patterns revealed a hexagonal lattice structure for ZnO and a cubic lattice structure for CeO₂, confirming that ZnO and CeO₂ nanocrystals grew independently. The crystalline size of the samples was determined using the Size Strain Plot (SSP) method. Reflectance data acquired through UV–visible spectroscopy were utilized to calculate the band-gap value, which was subsequently analyzed using the Kramer-Kronig method. The results indicate that, although there is negligible variation in the band gap values among samples prepared with different combinations and temperatures, these parameters influence n(ω) and k(ω). These findings suggest that ZnO/CeO₂ nanocomposites hold promise for optoelectronic applications, and the optical properties can be fine-tuned by controlling the aspect ratio of ZnO and CeO₂.