CdS nanoparticles mechanochemically synthesized in a high-energy mill

This paper describes the structural and surface properties of cadmium sulphide nanoparticles synthesized in a planetary mill. CdS nanoparticles were prepared by the mechanochemical route from cadmium acetate and sodium sulphide precursors. The structure of the as-prepared products was characterized by X-ray powder diffraction which reveals the crystalline nature of CdS nanoparticles. Cubic beta-CdS (hawleyite) is the only product of mechanochemical synthesis. SEM, TEM and low temperature nitrogen sorption were used to analyze the particle size and morphology as well as surface composition. The SEM measurements show the aggregates of small nanocrystals in which particle sizes approximately of 2 nm were calculated by application of Williamson-Hall as well as Warren-Averbach method. The TEM confirms the aggregate formation of CdS nanoparticles due to the extremely small particle size and tendency to lower high surface energy. The optical properties of CdS nanoparticles were studied by UV-VIS spectroscopy. UV-VIS spectrum shows an obvious blue shift, which is the result of the quantum size effect. The main advantages of mechanochemical synthesis in the production of CdS nanoparticles is in the formation of uniform crystallites and particles with large surface area in comparison with CdS prepared by chemical route. The cadmium sulphide nanoparticles are obtained in the simple step, making the process attractive for industrial applications.