Synthesis and optical properties of a lithium niobiosilicate glass doped with europium

The sol-gel method was used to prepare a lithium niobiosilicate glass doped with europium ions, 91SiO2-4Li2O-4Nb2O5-1Eu2O3 (% mole). The dried gel was heat-treated between 500 °C and 750 °C and glass ceramics were obtained. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman studies show that crystallization starts at temperatures above 600 °C. The LiNbO3 and EuNbO4 nanocrystals were found in the heat-treated samples as corroborated by the structural, morphological and optical properties. Room temperature photoluminescence (PL) studies allow us the identification of multiple Eu-related optical centres and the strongest red 5D0 → 7F2 intraionic transitions occur in the samples heat-treated at 600 °C where the LiNbO3 crystal phase was detected.