The characteristics of low-temperature-synthesized ZnS and ZnO nanoparticles

An easy and economic method is proposed to synthesize zinc sulfide (ZnS) nanocrystals. Zinc sulfide nanoparticles with different particle sizes were prepared by solid-state reaction of zinc acetate and thioacetamide at low temperature. After annealina at 600degreesC in air, zinc oxide (ZnO) nanoparticles were obtained. The ZnS and ZnO nanoparticles were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, differential thermal analysis and high-resolution analytical electron microscopy. The smallest crystallite size of ZnS nanoparticles obtained was 3.6 nm in diameter and the temperature for synthesizing was 100degreesC. The room temperature PL spectrum of ZnS sample deconvoluted by using a Lorentzian fit showed four peaks and the mechanism of emission was explained. A 26-fold increase in photoluminescence intensity has been observed in comparison with conventionally made ZnS particles. The particle size of ZnO samples calculated from XRD consistent with the TEM image was 37 nm and showed hexagonal structure. In the PL spectrum of ZnO nanoparticles, an emission peak at 501 nm was observed which was assumed to be due to the energy level of oxygen vacancies in ZnO energy band gap. By means of this method, it is easy to prepare ZnS and ZnO nanocrystals without wasting much time. (C) 2004 Elsevier B.V. All rights reserved.