Mechanochemical synthesis of nanocrystalline materials in an industrial mill

Nanosized materials are polycrystalline materials, whose crystal size is a few (typically 1-100) nanometers in at least one dimension. It has been proposed that as particles become smaller in size they may take on different chemical and physical properties. One of the most intriguing observations was that nanocrystals prepared by the altered “nano“ approach exhibited a higher surface chemical reactivity than more conventionally prepared samples. Nanocrystalline materials have many potential applications in the area of advanced materials. Their strongly size-dependent optical properties render them attractive candidates as tunable light absorbers and emitters in optoelectronic devices such as light-emitting diodes and quantum-dot lasers. These materials can be synthesized via solid state reactions where the efficiency of synthesis can be strongly enhanced by an intervention of high-energy milling (mechanochemical synthesis). The mechanochemical synthesis can effectively control and regulate the course of solid state reactions. Nanocrystalline materials MeS (Me=Pb, Zn, Cd, Cu) were successfully synthesized by the mechanochemical route from the corresponding metal acetates and natrium sulphide in an industrial mill. Structure properties of the as-prepared products were characterized by the X-ray powder diffraction, revealing the crystalline nature of the MeS nanoparticles. The methods of TEM, particle size analysis and the low temperature nitrogen sorption were used to analyze the particle morphology and the surface composition. The average sizes of MeS particles of 4-18 nm were estimated by Scherrer´s formula. The nanocrystalline materials are obtained in the simple step, making the process attractive for industrial applications. The main advantage of the application of the industrial mill is that it is a “quantity” process, permitting kilograms of material to be produced at an ambient temperature in a very short processing time. Moreover, the milling method is inexpensive, ecollogically clean, since it does not require large volumes of solution and produces particles.