Structure and luminescence properties of Eu3+-activated GaGd2SbO7 for light-emitting diodes.

Abstract

Eu³⁺-activated GaGd₂SbO₇ phosphors were synthesized via the solid-state reaction method. XRD confirmed the formation of a single-phase cubic pyrochlore structure, with Eu³⁺ occupying high-symmetry Gd³⁺ sites. Under 266 nm excitation, both host-related broadband emission and sharp Eu³⁺4f-4f transitions were observed. Increasing Eu³⁺ concentration enhanced energy transfer efficiency with optimal luminescence at 30 mol% Eu³⁺. Under 394/466 nm excitation, comparable intensities of the ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transitions confirm centrosymmetric site occupancy. The phosphors demonstrated an internal quantum efficiency of 88.19%, high color purity (>88%), strong thermal stability (71.6% intensity retention at 450 K), and a relatively high activation energy of 0.27 eV. Compared with previously reported Eu³⁺-based red phosphors, the Eu³⁺-activated GaGd₂SbO₇ phosphors provide efficient excitation under both near-UV and blue light, highlighting their promise as a competitive candidate for high-power warm-white LEDs and other solid-state lighting applications.