Influence of Al nitrate and Al chloride doping sources on structural and optical properties of sol-gel derived Al:ZnO nanoparticles

Al-doped ZnO nanoparticles have been synthesised via sol-gel method. Aluminum nitrate and aluminum chloride, as two widespread doping sources, have been compared in various Al/Zn molar ratios of 0.1, 0.5, 1, 2 and 5. After sol preparation, all samples with different Al content have been aged and then dried at 120 degrees C. The resultant grinned powders calcined at different temperatures of 400, 500, and 600 degrees C. X-ray diffraction (XRD) method has been used to investigate crystallisation behaviour and structural properties of samples. Less crystallinity in chloride source samples is detected compared to the nitrate source; however, identical distortion of hexagonal wurtzite unit cell in both sources was evident in XRD results. Field emission scanning electron microscopy demonstrates semisphere morphology of ZnO nanoparticles with particle size less than 60 nm. Fourier transform infrared spectroscopy was conducted to find possible chemical reactions and complexes during the sol-gel process in different Al source samples. UV-vis spectroscopy was carried out to find optical properties of the Al:ZnO samples. The results represent different optical properties in Al chloride and Al nitrate sources.