Photo- and mechano-luminescence characteristics and the mechanism analysis of green nanophosphors: BaReAl3O7:Tb3+ (Re = La, Y)

Abstract

Two bifunctional nanophosphors of BaLaAl₃O₇:xTb³⁺ (BLAO:Tb) and BaYAl₃O₇: yTb³⁺ (BYAO:Tb) have been designed and prepared by the high-temperature solid state reaction method. The green photoluminescence (PL) of the BYAO:Tb sample is significantly stronger than that of the BLAO:Tb sample. The optimal Tb³⁺ doping concentrations of two systems are 4 and 5 mol%, respectively. In addition, the BLAO:Tb and BYAO:Tb powders exhibit different lifetimes, i.e., single and double exponential decay processes in turn. Furthermore, the green mechanoluminescence (ML) phenomena of two kinds of nanophosphors are also observed when they are scratched with a pen. The ML intensity of the BYAO:4 Tb sample is weaker than that of the BLAO:5 Tb sample under almost the same external force, but the former becomes more intense as the scratching force increases. The PL/ML mechanism is analyzed based on the measurements of thermoluminescence (TL) spectra, and it is found that the initial total concentration of the trapped carriers in the BYAO:4 Tb samples is n₀ = 2.959 × 10⁴ cm⁻³, which is lower than that of the BLAO:5Tb³⁺ sample (3.301 × 10⁴ cm⁻³). However, the activation energies of the former are generally smaller than those of the latter. In conclusion, the new PL/ML bifunctional material has a better application potential because the novel aluminate ABAl₃O₇ structure is best suited for doping trivalent terbium ions.