Sonochemical and microwave synthesis and characterization of ZnO nanoparticles

Zinc oxide nanoparticles were synthesized using sonochemical and microwave techniques. The nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and ultraviolet photoluminescence (PL). The SEM micrographs indicated that the particles were spherical in shape with a diameter of ∼160 nm. However, the TEM micrographs revealed the presence of nanoplatelets and rods with a particle-size of ∼2 nm x∼80 nm. The observed X-ray diffraction pattern was identical to the standard diffraction pattern of ZnO. Ultraviolet photoluminescence (PL) studies of the samples showed a strong PL intensity and a significant blue shift relative to the PL of the bulk. Shifts up to 70 meV were observed and attributed to a quantum confinement effect. Electrical measurements indicated a highly resistive nature of the nanoparticulate material.