Characterization of the incorporated SiO₂ co-doped with Sr²⁺ and Tb³⁺ phosphors into PLA polymer matrix

SiO₂: 0.4% Sr²⁺, x% Tb³⁺ (0 ≤ x ≤ 0.5) nanophosphor powders were prepared by sol-gel method. The powder samples were dispersed into the PLA polymer matrix through melt mixing method and compression molding to prepare the nanophosphor polymer composite. X-ray diffraction (XRD) patterns showed broad peaks with the position of the peaks shifting and more separating with an increase in Tb³⁺ concentration. The transmission electron microscope (TEM) images showed darker patches with the introduction of the nanophosphor, which indicates the incorporation of phosphor particles into PLA polymer. Differential scanning calorimeter (DSC) results revealed that the composites show an increase in the cold crystallization temperature (T_cc) and slight decrease in the glass transition temperature (T_g) as compared to the PLA. Thermogravimetric analysis (TGA) results showed that the thermal stability of the composites show an initial decrease with the incorporation of the fillers, but they become more thermally stable with higher Tb concentration in the fillers. Ultraviolet visible spectroscopy (UV–vis) results showed the decrease in transmittance for the composite compared to the PLA polymer. The photoluminescence (PL) results showed that the incorporation of the Sr²⁺doped SiO₂ only affected the luminescence intensity, while co-doping with the incorporation of the Sr²⁺ and Tb³⁺ ions induced the emissions peaks at 487, 543, 582 and 621 nm, which could be attributed to the ⁵D₄ → ^7F₃, ^7F₄, ^7F₅, and ^7F₆ transitions of Tb³⁺, respectively. The main aim of this study was to fabricate the light emitting polymer-based material.