Structural and photoluminescent properties of Zn₂SiO ₄: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 β-Zn₂SiO₄:Mn or green emitting α- Zn₂SiO₄:Mn are obtained depending on the reaction temperature (either 800 or 900 °C) and the Mn content. Zn _2-2xSiO₄: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.