Synthesis and luminescence of SiO2/Zn2SiO4 and SiO2/Zn2SiO4:Mn composite with sol-gel methods

The sol gel method is used for the preparation of undoped and manganese-doped Zn2SiO4 particles embedded in SiO2 host matrix with supercritical drying of ethyl alcohol in two steps. Zn2SiO4 and Zn2SiO4: Mn were prepared by simple solid-phase reaction in a natural atmosphere at 1200 °C after the incorporation of the nanoparticles of ZnO and ZnO: Mn, respectively, in the silica monolith. The photoluminescence (PL) measurements show a band centered at about 760 nm in the case of non-doped Zn2SiO4 which is attributed to energy transfer from Zn2SiO4 particles to NBOHs interface defects. In the case of Manganese doped Zn2SiO4, the PL reveals a band centered at about 525 nm attributed to Mn2+ in Zn2SiO4. Photoluminescence excitation (PLE) measurements show different origins of the emission. It was suggested that electronic transition 4T1(4G)→6A1(6S) associated with Mn2+ ions in willemite and the presence of Mn2+ in intensive crystal field were responsible for these luminescence band centered at 525 nm.