Efficient green upconversion emission in transparent Teo2-Geo2 glass-ceramic obtained by billet extrusion

Abstract

Transparent Yb3+/Er3+glass-ceramic was successfully obtained by the extrusion method. The extrusion of oxyfluoride tellurite-germanate glass co-doped with Yb3+and Er3+ions at 520°C resulted in the formation of Ba0:75Er0:25F2:25 nanocrystals, leading to an increase in the upconversion (UC) emission intensity of 35 times in glass-ceramic with respect to the glass. The glass to glass-ceramic transition was confirmed by X-ray diffraction (XRD) and Transmission electron microscope (TEM). Also, the structural changes that occurred during crystallization were assessed using Fourier-transform infrared (FTIR) spectroscopy. Furthermore, the pump power and temperature UC emission dependence of glass and glass-ceramic under 976 nm laser excitation were investigated in detail. The assessments showed that i) two-phonons are involved in the UC process and ii) the temperature has a significant influence over it. The Yb3+/Er3+ codoped glass-ceramic shows relatively high Sa and Sr values in a wide temperature range from 300 to 573 K, presenting the maximal Savalue of 3:50 x 10–3 at 573 K and the maximal Sr value of 6:30 x 10–3at 364 K. These results suggest that the glass-ceramic is a good candidate for optical applications such as luminescent thermometry.