Thermal properties and upconversion luminescence of Er3+/Yb3+ co-doped La2O3–TiO2–WO3 glasses prepared by containerless processing

Abstract

Er3+/Yb3+ co-doped La2O3–TiO2–WO3 (LTW) glass spheres with different WO3 concentrations were prepared by aerodynamic levitation method. The effects of WO3 concentration on thermal properties, Raman spectra, upconversion luminescence spectra and fluorescence lifetime were studied. Er3+/Yb3+ co-doped LTW glasses have high thermal stability. With WO3 concentration increasing, the thermal stability decreases, and the glass forming ability increases and then decreases. The glasses perform low phonon energy with the maximum phonon energy of 737 cm−1. WO3 show little effect on the phonon energy of the glasses. Green and red upconversion luminescence centered at 554 nm and 673 nm were obtained under 980 nm excitation. As WO3 concentration increases, the intensity of upconversion luminescence first increases and then decreases. The introduction of WO3 can reduce the red/green ratio sharply. Compared to green upconversion luminescence, WO3 plays a role in constraining the red emission. The measurements of fluorescence lifetime confirm the intensity change for green and red emissions. The fluorescence lifetimes at 673 nm are longer than those at 554 nm, leading to stronger red upconversion luminescence. Novel Er3+/Yb3+ co-doped LTW bulk glasses obtained by containerless processing exhibit promising application prospect in small optics devices.