Effect of partial crystallization on the thermal, optical, structural and Er3+ luminescence properties of silicate glasses
Résumé
The effect of partial substitution of CeO2, La2O3, SrO and CaO for B2O3 and Na2O on the crystallization, structural and optical properties of a borosilicate glass with the molar composition 50SiO2 26.9B2O3 -1.5Al2O3-0.5P2O5-20.94Na2O-0.12 Er2O3 was studied. The composition of the glass was modified in order to increase the glass tendency to crystallize as no strong evidence of the crystallization was observed in the Er3+ doped glasses prepared without nucleation agent. By controlling carefully the thermal treatment parameters, transparent glass-ceramics can be obtained. When heat treated at (Tg + 20 °C) for 17 h followed by a heat treatment at (Tp) for 24 h, sharp peaks were observed in the XRD pattern of the SrO, CaO, CeO2 and La2O3-containing glasses. These peaks were related to the formation of crystals with different compositions depending on the glass composition. From the spectroscopic properties of the glasses, the Er3+ ions are not suspected to be incorporated in the crystals except in the Ce-doped glass, for which we suspect the CePO4 crystals to contain Er3+ ions due to a strong modification of the Er3+ emission band at 1530 nm after heat treatment