Structure, dielectric and optical properties of Nd³⁺-doped LiTaO₃ transparent ferroelectric glass-ceramic nanocomposites

Abstract

Here, we present the structural, dielectric and optical properties of neodymium ion (Nd³⁺) doped novel transparent glass-ceramics containing LiTaO3 nanocrystals in the Li₂O-Ta₂O₅-SiO₂-Al₂O₃ (LTSA) glass system prepared by the melt-quenching technique. The precursor glasses were isothermally crystallized at 680 °C for 3-100 h, following the differential thermal analysis (DTA) data, to obtain nanostructured glass-ceramics. They were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Fourier transform infrared reflection spectra (FTIRRS), optical absorption and luminescence spectroscopy along with dielectric constant measurements. XRD, FESEM, TEM and FTIRRS confirm the nanocrystallization of LiTaO₃ (14-36 nm) in the LTSA glass matrix. A steep increase in dielectric constant (ε _r) of glass-ceramics with heat-treatment time is observed due to high dielectric constant ferroelectric LiTaO₃ formation. The measured NIR photoluminescence spectra have exhibited emission transitions of ⁴F_3/2 → ⁴I_J (J = 9/2, 11/2 and 13/2) from Nd³⁺ ions upon excitation at 809 nm. It is observed that the photoluminescent intensity and excited state (⁴F_3/2) lifetime of Nd³⁺ ions decrease with increase in heat-treatment time due to concentration quenching effect. The absorption spectra and fluorescence measurements reveal that the incorporation of Nd³⁺ ions in the LiTaO₃ crystal lattice in the oxide glassy matrix is important for obtaining desirable fluorescence performance of the material.