Pre-crystallization heat treatment and infrared luminescence enhancement in Ni2+-doped transparent glass-ceramics

We report on design and fabrication of Ni2+-doped glass-ceramics from a low-alkali optical glass in Li2O-Na2O-Ga2O3-SiO2-GeO2 system by melting technique and subsequent thermally controlled nano-crystallization. The analysis of differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, absorption and fluorescence spectroscopy reveals, for the first time, the real possibility of optimizing the integrated intensity of Ni2+ near-infrared emission through controlled pre-treatments at temperatures of nanophase nucleation, with the enhancement up to a factor of four with respect to gallium germanosilicate glass-ceramics obtained without pre-treatments. Importantly, the effects on the light emission are shown to be related to the influence of pre-treatment on size and size distribution of the gallium oxide nanocrystals which result from subsequent crystallization at higher temperature.