Sol–gel syntheses, luminescence, and energy transfer properties of α-GdB5O9:Ce3+/Tb3+ phosphors

Abstract

Sol–gel method was applied to prepare homogenous and highly crystalline phosphors with the formulas α-GdB₅O₉:xTb³⁺ (0 ≤ x ≤ 1), α-Gd_1−xCe_xB₅O₉ (0 ≤ x ≤ 0.40), α-GdB₅O₉:xCe³⁺, 0.30Tb³⁺ (0 ≤ x ≤ 0.15) and α-GdB₅O₉:0.20Ce³⁺, xTb³⁺ (0 ≤ x ≤ 0.10). The success of the syntheses was proved by the linear shrinkage or expansion of the cell volumes against the substitution contents. In α-GdB₅O₉:xTb³⁺, an efficient energy transfer from Gd³⁺ to Tb³⁺ was observed and there was no luminescence quenching. The exceptionally high efficiency of the f–f excitations of Tb³⁺ implies that these phosphors may be good green-emitting UV-LED phosphors. For α-Gd_1−xCe_xB₅O₉, Ce³⁺ absorbs the majority of the energy and transfers it to Gd³⁺. Therefore, the co-doping of Ce³⁺ and Tb³⁺ leads to a significant enhancement in the green emission of Tb³⁺. Our current results together with the study on α-GdB₅O₉:xEu³⁺ in the literature indicate that α-GdB₅O₉ is a good phosphor host with advantages including controllable preparation, diverse cationic doping, the absence of concentration quenching, and effective energy transfer.