Influence of Reaction Temperature on Crystal Structure and Band Gap of ZnO Nanoparticles

Zinc oxide nanoparticles have been synthesized at room temperature and at 50 degrees C via precipitation method for the present study. The effect of synthesis temperature on the crystalline size, microstructure, optical properties, and energy gap of the synthesized zinc oxide nanoparticles has been investigated. The particle size was found to reduce from 26 nm to 17 nm when the reaction temperature was increased from room temperature to 50 degrees C. Energy gap of the prepared samples has been theoretically determined using effective mass model equation and compared with the experimental value. It depicts that the energy gap of the smaller nanoparticles is higher than the bigger one. The recorded blue shift confirmed the quantum confinement effect. Compositional quality and functional group of the zinc oxide nanoparticles have been studied, and the frequency of zinc oxide nanoparticles has been observed at two different regions, 566 cm(-1) and 432 cm(-1). The recorded ultraviolet-visible spectrum shows absorption peaks at 361 nm and 328 nm, which are less than the absorption peak of bulk zinc oxide (388 nm). Peak absorption wavelength measurement shows the average size of the prepared zinc oxide nanoparticles is as small as 1.55 nm.