Fabrication and optical properties of NUV-emitting SiO2–SrB4O7:Eu2+ glass–ceramic thin films

SiO2–SrB4O7:Eu2+ glass–ceramic thin films were fabricated for possible application in near ultraviolet (NUV) emitting devices. Nano-sized SrB4O7:Eu2+ powders were prepared by a Pechini-type sol–gel method and a subsequent ball-milling treatment. The powders showed NUV emissions centered at 367 nm, upon irradiation with UV of shorter wavelengths, due to an allowed 4f65d1 → 4f7 electronic transition of Eu2+ ions. The glass–ceramic thin films were prepared by dip-coating of tetraethylorthosilicate (TEOS) solutions dispersed with the nano-sized SrB4O7:Eu2+ powders and a subsequent heat-treatment. It was found that the glass–ceramic thin films had relatively high thermal stability up to 800 °C in terms of the Eu2+ emissions. SiO2 layers surrounding SrB4O7:Eu2+ appeared to be effective for the surface passivation of the phosphor particles.