Increase of the blue upconversion emission in Tm3+/Yb3+ co-doped titanate glass–ceramics

Tm3+/Yb3+ co-doped La2O3–TiO2–ZrO2 glass–ceramics with intense blue emission have been fabricated by containerless processing in an aerodynamic levitation furnace, following by heat treatment at different temperatures in the air. The intensity of blue upconversion luminescence increases two times compared with the precursor glass after a heat treatment process at 890°C. Blue and red emissions centered at 476nm and 650nm owing to the Tm3+ transitions 1G4→3H6 and 1G4→3F4 are achieved under the excitation of 980nm at room temperature. The upconversion luminescence is based on a two-photon process by the cooperative sensitization which transfers energy from Yb3+ to Tm3+. Furthermore, Tm3+ and Yb3+ ions are enriched in nanoparticles which disperse in glass matrixes. Dense lattice fields and strong partitions of nanocrystals reduce energy losses caused by mutual interactions among rare earth ions to obtain strong upconversion luminescence. The presented intense blue emission of Tm3+/Yb3+ co-doped La2O3–TiO2–ZrO2 glass–ceramics shows potential promising perspective in the optical materials. •Tm3+/Yb3+ doped titanate glass–ceramics are prepared by containerless processing.•The blue emission increases two times by heating the precursor glass at 890°C.•The upconversion is based on a two-photon process by cooperative sensitization.•Tm3+ and Yb3+ are enriched in dense nanocrystals with strong partitions in matrixes.•Energy losses of rare earth ions are reduced for intense emission by nanocrystals.