Annealing or direct synthesis of uniform inorganic nanoparticles using salt powder as separation medium

Uniform nanoparticles have shown to hold great potential in many different fields. As a result, many resources have been devoted to the search for a general synthesis of uniform nanoparticles, which has led to the proliferation of solution-based methods. However, some of these techniques are inherently difficult to scale up and are unable to meet future industry needs. Additionally, since the synthesis temperature of these methods can only go as high as the evaporation point of the solvent, they are not compatible with the high temperatures required to obtain certain desired properties such as high crystallinity. Recently, solventless methods have gained considerable attention since they are relatively fast and require no expensive or toxic solvents. Inorganic salt powder can be used as separation medium to prevent aggregation and sintering by keeping the as-prepared nanoparticles or precursor materials physically separated. This review surveys the use of inorganic salts in solventless techniques for the annealing or direct synthesis of uniform nanoparticles.