In this work, the influence of Al (0, 2, 4, and 6 wt.%) on the optical properties of ZnO has been briefly investigated and described. The undoped and doped samples were characterized using a UV-visible spectrophotometer and Photoluminescence (PL). The X-ray diffraction (XRD) data in our preceding study is also indexed, and materials are said to have a wurtzite-structured hexagonal phase and exhibit no impurity phases. The average crystallite sizes of the pure ZnO were found to increase, i.e., from 14.19 nm to 34.17 nm with an increase in temperature, and in the case of Al-doped ZnO, at a constant temperature, from 35.05 nm to 18.89 nm, respectively. The average crystallite size of AZO (Al-doped ZnO) decreases with increasing Al content. With the increasing temperature, increases in crystallinity and size of the pure ZnO have been observed. In the case of Al doping, with an increase in the concentration of doping the crystallite size is seen to be decreased, without any change in the temperature. Al doping improves the formation of the well-ordered crystalline structure of ZnO up to a certain limit of doping. The absorbance spectra were used to determine the optical band gap of the samples. The optical photoluminescence (PL) spectra of both ZnO and AZO nanopowder are obviously influenced by the increasing temperature and Al doping content, respectively. Different optical properties of ZnO and AZO were observed for different contents of Al in ZnO. The band gap of AZO nanopowder with different concentrations has been seen to be lower than that of undoped ZnO (3.10 eV), suggesting broad application potential. Also, the optical properties of ZnO were tailored by Al doping in the near visible region, suggesting various potential uses.

Zinc oxide and metal-doped oxides are multifunctional nanomaterials used in the Nano World due to their distinctive characteristics and unique physical and chemical properties such as extraordinary chemical stability, anti-corrosion, low electrons conductivity, a broad range of radiation absorption, high photo stability, and tremendous heat resistance. To synthesize zinc oxide and Al-doped ZnO nanostructures with the inexpensive sol-gel method is our research objective, further we aimed to analyse the characterization of undoped and Al-doped ZnO nanopowder. Al-doped zinc oxide with compositional formula AlxZn1-xO (x = 0, 2, 4, 6) was synthesized using Zinc acetate dihydrate (Zn (CH3COO)2. 2H2O) as a precursor, Sodium hydroxide (NaOH) and distilled water were used as a second-hand medium for the preparation of the solution. Ethanol (CH2COOH) served as a versatile intermediate and was used as a solvent. The X-ray diffraction peaks suggest a hexagonal wurtzite crystal structure which matches with the pattern of the standard hexagonal structure of ZnO and Al-doped zinc oxide in all samples. X-ray diffraction result exhibits good crystallinity. The scanning electron microscopy images confirm the clear formation of spherical ZnO nanopowder and the change of the morphology of the nanopowder with the incorporation of the aluminium. The scanning electron microscopy results are in adjacent settlement with that estimated by the DebyeSheerer formula created on the X-ray diffraction pattern. The usual crystallite size of Aldoped zinc oxide decreases by an increase in Al concentration with capping without varying the temperature. X-ray diffraction and scanning electron microscopy with energy dispersive x-ray analysis revealed that all samples crystallize in polycrystalline nature with wurtzite lattice. The result of energy dispersive x-ray analysis characterization shows that the ZnO nanopowders with no other main adulterated phase. Extant learning ventures this as a low-cost method for the synthesis of pure and capped Al-doped ZnO for industry scale applications.