Abstract
The synthesis and characterization of multicolor light-emitting nanomaterials based on rare earths (RE3+) are of great importance due to their possible use in optoelectronic devices, such as LEDs or displays. In the present work, oxyfluoride glass-ceramics containing BaF2 nanocrystals co-doped with Tb3+, Eu3+ ions were fabricated from amorphous xerogels at 350 °C. The analysis of the thermal behavior of fabricated xerogels was performed using TG/DSC measurements (thermogravimetry (TG), differential scanning calorimetry (DSC)). The crystallization of BaF2 phase at the nanoscale was confirmed by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM), and the changes in silicate sol–gel host were determined by attenuated total reflectance infrared (ATR-IR) spectroscopy. The luminescent characterization of prepared sol–gel materials was carried out by excitation and emission spectra along with decay analysis from the 5D4 level of Tb3+. As a result, the visible light according to the electronic transitions of Tb3+ (5D4 → 7FJ (J = 6–3)) and Eu3+ (5D0 → 7FJ (J = 0–4)) was recorded. It was also observed that co-doping with Eu3+ caused the shortening in decay times of the 5D4 state from 1.11 ms to 0.88 ms (for xerogels) and from 6.56 ms to 4.06 ms (for glass-ceramics). Thus, based on lifetime values, the Tb3+/Eu3+ energy transfer (ET) efficiencies were estimated to be almost 21% for xerogels and 38% for nano-glass-ceramics. Therefore, such materials could be successfully predisposed for laser technologies, spectral converters, and three-dimensional displays.
Highlights
Barium fluoride, BaF2, belongs to the group of attractive nanoparticles, produced using different preparation methods and applied in numerous multifunctional applications
This effect was confirmed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) used for self-assembled monodisperse BaF2 nanocrystals accomplished by the liquid–solid-solution (LSS) approach [2]
Recorded exothermic differential scanning calorimetry (DSC) peaks are clearly correlated with thermal decomposition of Ba(TFA)2 and crystallization of BaF2, which could be given by the chemical reaction: Nanomaterials 2022, 12, x FOR PEER REVIEW
Summary
BaF2 , belongs to the group of attractive nanoparticles, produced using different preparation methods and applied in numerous multifunctional applications. The quenching of fluorescence intensity (λem = 1052 nm) in nanosized Nd3+ :BaF2 domains was not observed even under very high dopant levels (~45 mol.% of Nd3+ ). Further experiments revealed the crystallization of cubic and orthorhombic BaF2 nanoparticles, and it was proven that such fluoride crystals could be quite transformed from the orthorhombic phase to the more thermodynamically stable cubic phase under certain preparation conditions. This effect was confirmed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) used for self-assembled monodisperse BaF2 nanocrystals accomplished by the liquid–solid-solution (LSS) approach [2]. BaF2 nanocrystals were fabricated from precursor Na2 O-K2 O-BaF2 -Al2 O3 -SiO2 glasses via their controlled heat treatment
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