High thermally stable Tm3+-doped alkali borosilicate glass: structure, Judd-Ofelt calculations, and near-pure blue light emission

Abstract

SiO₂-B₂O₃-Na₂O-NaF-WO₃-La₂O₃ glasses doped with Tm₂O₃ were prepared using the melt-quenching method. The Tm³⁺-doped glasses were studied through XRD, DSC, FTIR, absorption spectroscopy, Judd-Ofelt (J-O) theory, and photoluminescence spectroscopy. According to the J-O theory, a high Ω₂ value predicts a higher covalency between the Tm³⁺ and O^2- ions. Under 359 nm excitation, all the glasses exhibit blue emission with a color purity above 99.26%. The emission intensity of the glass doped with 0.4 mol% Tm2O3 reaches the highest and then decreases due to the concentration quenching. It is connected with the energy transfer between the Tm³⁺-Tm³⁺ ions, which is predominantly governed by dipole-dipole interactions according to the Inokuti-Hirayama (I-H) model. On this basis, the Yokota-Tanimoto model confirmed that, in addition to donor-acceptor interactions, donor-donor interactions become increasingly significant as the doping concentration increases, emerging as a crucial factor in concentration quenching. At 423 K, the intensity of the glass retains 71% of its initial value, with a color shift ranging from 0.0002 to 0.0158, demonstrating its excellent luminescent thermal stability. In summary, the obtained glasses are candidate materials for LED fields, especially suitable for blue and white light display devices.