Structural and Optical Studies of ZnO Nanostructures Synthesized by Rapid Microwave Assisted Hydrothermal and Solvothermal Methods

We report the structural and optical studies of various morphologies of ZnO nanostructured (nanoparticles and nanorods) samples synthesized at low temperatures using novel microwave assisted hydrothermal and solvothermal methods within a short time without any post heat treatment. The structural and optical studies were carried out on as-synthesized ZnO samples using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), UV-visible spectroscopy and surface area analyzer techniques. Powder XRD results confirmed the formation of phase pure hexagonal crystal structured ZnO samples (S1, S2 and S3). Structural co-ordination of ZnO samples (S1, S2 and S3) was confirmed from the FTIR results. SEM images showed the formation of uniformly distributed ZnO nanoparticles (average particle size ∼90 nm) and nanorods (average diameter ∼100 nm, average length 0.3-1 μm) synthesized using facile microwave assisted hydrothermal and solvothermal methods. UV-visible spectral results showed that ZnO nanorods exhibited higher optical band gap than that of ZnO nanoparticles, which may be due to the one dimensional morphology of ZnO nanorods. Surface area analysis of the samples revealed that the small size crystallites exhibited high specific surface area.