Solid-state reaction route to synthesis of ordered mesoporous β-Zn2SiO4:Mn-SiO2 composites with ultraviolet and yellow emission

Ordered mesoporous Mn-doped β-Zn2SiO4-SiO2 composites are synthesized by solid state reaction at 800 °C using mesoporous silica as assisted template and silicon source. The formation temperature of β-Zn2SiO4 doped with Mn2+ is much lower than that of conventional solid state reaction, which is ascribed to the high reactivity of mesoporous silica with large surface area and porous structure. Mn-doped β-Zn2SiO4 crystals disperse in the mesoporous silica frameworks which play roles in supporting the mesoporous structure and restraining the phase transformation from β- to α-Zn2SiO4, contributing to enhancing the stability of composites. Excitation spectra of the composites show the zinc silicate absorption around 210 nm and the charge transfer band around 245 nm. Mn-doped β-Zn2SiO4-SiO2 composites exhibit an ultraviolet emission at 390 nm attributed to silica and a strong yellow emission around 575 nm driven by 4T1 to 6A1 radiative transition of Mn2+. No obvious concentration quenching is observed at high doping level of 0.08, proving the homogeneous doping of Mn2+ in the composites. This route exhibits a significant advantage of lowering the reaction temperature, facilitating easy doping and preventing concentration quenching.