Processing and properties of Eu³⁺: LiTaO₃ transparent glass-ceramic nanocomposites

Abstract

We report here the processing and properties of transparent glass and glass-ceramic nanocomposites in the Li₂O-Ta₂O₅-SiO₂-Al₂O₃ system in the presence of Eu₂O₃ as luminescent probe. The formation of the LiTaO₃ crystal phase, the crystallite size, and the morphology with the progression of heat treatment have been examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transformed infrared reflectance spectroscopy measurements. The crystallite sizes obtained from XRD and TEM are found to increase with heat-treatment time and vary in the range of 2-20 nm. The measured photoluminescence spectra exhibit emission transitions of ⁵D_0,1→⁷F_j (j=0, 1, 2, 3, and 4) of Eu³⁺ ions. From the nature of the emission transitions, the site symmetry in the vicinity of Eu3+ ions has been found to be near C3v in the glass-ceramic nanocomposites. An inverse correlation has been observed between the asymmetric ratio (I_ED/I_MD) of Eu³⁺ ions and the dielectric constant (ε_r), with an increase in the heat-treatment time of glass, which is caused by the dipole-dipole interaction.