Structural and Photoluminescent Properties of Zn2SiO4:Mn2+ Nanoparticles Prepared by a Protected Annealing Process

This works presents a new method for the production of colloidal suspensions of Zn2SiO4:Mn (ZSM) luminescent nanoparticles. The process consists in achieving a high temperature solid state reaction among silica nanoparticles homogenously dispersed within a ZnO matrix in large excess. Highly crystalline, well dispersed nanoparticles are recovered as a colloidal suspension after dissolution of the ZnO matrix in slightly acidic water. Yellow emitting beta-Zn2SiO4:Mn or green emitting alpha- Zn2SiO4:Mn are obtained depending on the reaction temperature (either 800 or 900 degrees C) and the Mn content. Zn2-2xSiO4:Mn-x particles with x up to 3% can be obtained with a maximum relative emission efficiency of about 16% as compared to a bulk ZSM phosphor reference. The principle of this new synthetic route opens a new field of investigation for the production of colloidal dispersion of refractory compounds with a high crystallinity.