Ce/Mn/Cr: Y₃Al₅O₁₂ phosphor ceramics for white LED and LD lighting with a high color rendering index

Ce/Mn/Cr: Y₃Al₅O₁₂ transparent ceramics with a pure garnet structure and a high color rendering index were prepared by a solid-state reaction method. Mn²⁺ and Cr³⁺ enhance the emission between 500 and 700 nm and expand the conventional Ce: YAG phosphors spectrum. The Ce³⁺ can work both, as activators and sensitizers, and the intense energy transfer from Ce³⁺ to Mn²⁺/Cr³⁺ is realized through the non-radiative and radiative processes. In the sample with the optimized doping concentration the high color rendering index (CRI) value of 75.3 can be achieved under a 450 nm laser diode excitation. The chromaticity coordinates can be tuned from (0.3125, 0.3232) to (0.2917,0.2851) by varying the doping concentration. With the increasing Mn²⁺/Cr³⁺ doping concentration, the lifetime of Ce³⁺, quantum efficiency and luminous efficiency are all gradually decreased. This work effectively offers a scheme for realizing the high color rendering performance of phosphor-converted transparent ceramics in white LEDs/LDs.