A Comparative Study of Zinc Oxide Nano Particles Synthesized by Hydrothermal, Sol-gel and Thermal Decomposition

In the proposed work, Zinc oxide nano particles (ZnO NP's) are synthesized using three different methods: Hydrothermal, Sol-gel and Thermal decomposition. The samples are characterized using Xray diffraction (XRD), UV visible spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FT-IR) and scanning electron microscopy (SEM). The XRD pattern exhibit single-phase polycrystalline nature of all the samples exhibiting the most intense peak at (101). The diffraction peaks are located at 31.80, 34.46, 36.28, 47.60, 56.62, 62.98, 68.04, 69.16 and 77.00 and have been keenly indexed as hexagonal wurtzite phase of ZnO. The FT-IR Spectra of ZnO NP's is recorded in the wave number range from 400 to 4000 cm(-1). In UV visible Spectra of ZnO absorption edge for solgel is around 345 nm, 360 nm for hydrothermal and shifted to 376 nm for thermal decomposition, which shows the increase in crystalline size. The energy band gap of materials is calculated using a well-known Tauc's plot from which the values Eg for all the three samples are for sol-gel E-g = 2.78 eV, thermal decomposition E-g = 2.90 eV and hydrothermal E-g = 3.20 eV. SEM images exhibit the formation of large spherical Nano particles for sol-gel method, Wurtzite structure for thermal decomposition and Nano rods in hydrothermally synthesized ZnO sample.