Photoluminescence and thermal stability of Tb3+-doped Gd2O3 nanoparticles embedded in SiO2 host matrix

Highlights: • The work reports the grown of Tb³⁺-doped Gd₂O₃ nanoparticles into SiO₂ via sol-gel. • The effects of Tb³⁺ concentration in the photoluminescence are discussed. • Thermal parameters reveal good stability, assigned to encapsulating by SiO₂. • Material shows good thermal response, applicable in thermometric devices. Terbium doped SiO₂-Gd₂O₃ materials were obtained by a sol-gel process and heat-treated at 1000 °C. The effect of Tb³⁺concentration on structural, optical and photoluminescent properties of materials are reported here. FT-IR indicated the presence of Gd₂O₃ and SiO₂ in the composition of materials. XRD showed the formation of the Gd₂O₃ cubic phase without the presence of phase impurities, and lattice parameter calculations indicated the effective inclusion of Tb³⁺ in Gd₂O₃ crystalline structure. SEM analysis revealed spherical particles of Gd₂O₃ and TEM confirmed that these particles are included in the amorphous SiO₂. Excitation spectra show bands in the UV-region at characteristic wavelengths of the Gd₂O₃ host absorption. Emission spectra were collected by changing the excitation, and the intensity shows dependence on the UV photon energy. Tb³⁺-doped Gd₂O₃ grown into SiO₂ showed higher Tb³⁺ lifetimes which are ideal for photonic applications. The temperature significantly influenced the luminescence of the materials, with chromaticity changing from green to blue region. The activation energy for thermal quenching (E_a) was determined by an Arrhenius methodology and the material shows a high thermal stability (E_a for thermal quenching = 0.378 eV).