Mn-Ce co-activated garnet crystals as bright scintillators for fast gamma and high-performance X-ray imaging

Abstract

Cerium-activated garnet-structured crystal Gd₃(Al,Ga)₅O₁₂:Ce (GAGG:Ce) is regarded as one of the most effective scintillators for high-resolution radiation detection due to its high light yield, excellent energy resolution, and exceptional radiation hardness. Nevertheless, the long radiative lifetime of Ce³⁺ and the slow component in scintillation decay time pose significant limitations on its further application. To overcome these problems, a novel strategy has been proposed to create a complementary de-excitation channel by introducing Mn²⁺ as a co-activator. This newly created channel facilitates the transfer of energy from Ce³⁺ to the acceptor during non-radiative processes, thereby enhancing the de-excitation efficiency of Ce³⁺. Notably, benefitting from the luminescence of dual luminescence centers along with the energy transfer between Ce³⁺ and Mn²⁺, the higher X-ray excited luminescence intensity (128 % enhancement compared to undoped crystals) and faster scintillation decay are simultaneously realized for the first time in GAGG:Ce crystals. The higher X-ray excited luminescence intensity results in an excellent spatial resolution of 30.0 lp mm⁻¹, which is significant for X-ray imaging applications. This enhancement greatly facilitates the commercialization of Ce-activated garnet-structured scintillators. The study highlights the potential of the cooperation of Mn²⁺ and Ce³⁺ in optimizing scintillation performances, thereby opening avenues for the development of ultrafast and efficient inorganic scintillators.