Structural, optical, and spectroscopic properties of Er3+-doped TeO2-ZnO-ZnF2 glass-ceramics

Abstract Transparent fluorotellurite glass-ceramics have been obtained by heat treatment of precursor Er-doped TeO 2 –ZnO–ZnF 2 glasses. ErF 3 nanocrystals nucleated in the glass-ceramics have a typical size of 45 ± 10 nm. Based on the Judd-Ofelt theory, the main radiative parameters for the 4 I 13/2  →  4 I 15/2 transition have been obtained. The split of the absorption and emission bands and the reduction of the Ω 2 parameter, as compared to the glass, confirm the presence of Er 3+ ions in a crystalline environment in glass-ceramic samples. The analysis of the 4 I 13/2 decays suggests that a fraction of Er 3+ ions remains in a glass environment while the rest forms nanocrystals. For the glass-ceramics, intense red and green upconversion emissions were observed with an enhancement of the 4 F 9/2  →  4 I 15/2 red one compared to the glass sample. The temporal evolution of the red emission together with the excitation upconversion spectra suggests that energy transfer processes are responsible for the enhancement of the red emission.