Pre-crystallization heat treatment and infrared luminescence enhancement in Ni 2+ -doped transparent glass-ceramics

We report on design and fabrication of Ni 2+ -doped glass-ceramics from a low-alkali optical glass in Li 2 O-Na 2 O-Ga 2 O 3 -SiO 2 -GeO 2 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 Ni 2+ 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.