Microwave-Induced Self-Activated Emission in Spinel Gallate ZnGa₂O₄ for Dual-Channel Trapping and Detrapping

Self-activated luminescent materials have attracted increasing attention due to their broad applicability across diverse technological fields. However, a comprehensive understanding of the generation, regulation, and coexistence of self-activated luminescent centers with dopant-related emission centers remains limited. Herein, a defect-related self-activated blue-emitting center (with peak position located in the 450-500 nm range) is induced within the conventional spinel gallate phosphor system via a microwave-assisted preparation process. Notably, the self-activated emission universally coexists with the characteristic transitions of different dopant ions (Eu³⁺/Mn²⁺/Cr³⁺), indicating excellent compatibility between self-activated luminescent centers and multiple dopant-related emission centers. Taking ZnGa₂O₄:Cr³⁺ as an example, the self-activated luminescence shows pronounced dependence on both irradiation time and temperature. Further investigations elucidate that the electron trapping and detrapping pathways are associated with the coexisting self-activated and dopant-related luminescent centers, highlighting the distinct electron dynamics arising from their coexistence. Moreover, benefiting from the different temperature responses, a dual-emission ratiometric thermometry platform with a wide operating temperature range from 143 to 573 K is constructed. This work emphasizes the unique electron dynamics of self-activated luminescent centers and demonstrates their broad compatibility with diverse dopant systems, providing insights into the design of multifunctional luminescent materials based on intrinsic defect states.