Composition Influence on the Thermo-optical Properties and Luminescence Efficiency of Europium-Doped Calcium Aluminosilicate Glasses

Abstract

In this work, the influence of the composition on the thermal and thermo-optical properties and luminescence of europium-doped calcium aluminosilicate glasses is investigated. High purity reagents were used to prepare samples with nominal compositions: $2.5\hbox {Eu}_{2}\hbox {O}_{3},\,4.1\hbox {MgO},\,(7 + x)\hbox {SiO}_{2},\,(47.4 - x/2)\hbox {CaO},\,\hbox {and} (39 - x/2)\hbox {Al}_{2}\hbox {O}_{3},\,x = (0, 22, 27, 32, 37, 42,\,\hbox {and}\,47)\,(\hbox {in mass}\%)$. The ratio CaO/ Al$_{2}$O$_{3}$ was kept at 1.2. At room temperature, measurements of the specific heat, mass density, temperature coefficient of the optical path length, and refractive index were performed. Two-beam thermal lens spectroscopy in the mismatch mode was used to determine the absolute values of the thermal diffusivity at room temperature. Using the thermal lens signal, the rate of heat generated by the nonradiative process was estimated, which showed a large decrease with increasing silica content. The decrease of this parameter can be related to the increase of the luminescence efficiency, which agrees with the results of luminescence spectroscopy. These results suggest an increase in the luminescence efficiency of europium-doped calcium aluminosilicate glasses at increments of increasing silica content.