An effective nanostructured green phosphor Zn$_2$SiO$_4$:Mn$^{2+}$ prepared by sol-gel method

A nanostructured willemite doped with manganese (Zn$_2$SiO$_4$:Mn$^{2+}$) was synthesized by sol-gel method followed by high-temperature annealing. Prepared Zn$_2$SiO$_4$:Mn$^{2+}$ is characterized by average particle size of 100 nm, narrow particle size distribution, and high crystallinity. Under UV-excitation nanostructured willemite shows an intensive photoluminescence at 520 nm corresponded to activator Mn$^{2+}$ emission. It was found that the emission decay curves of willemite becomes non-exponential with increasing of manganese content. Zn$_2$SiO$_4$:Mn$^{2+}$ reveals long-lasting phosphorescence up to 45 ms. Absolute quantum yield of Zn$_2$SiO$_4$:Mn$^{2+}$ reaches 47 % at 0.1 at. % ofMn$^{2+}$. The luminescence concentration quenching effect at Mn$^{2+}$ concentration higher than 1 at % is observed.