Mn2+-Si4+ co-doped Al2O3- Ce: (Y, Tb) AG composite ceramic phosphors for high color rendering white LED/LD illumination: an investigation on the luminescence properties and energy transfer mechanism

Ce: YAG- Al2O3 composite ceramics are regarded as highly promising materials for laser illumination application due to their high luminous efficacy and thermal stability. Nevertheless, pure YAG-based ceramics exhibit limited color rendering index (CRI) for indoor lighting due to their low red emission component. In this study, we synthesized high-performance Ce, Mn-doped (Y, Tb)3Al5O12-Al2O3 composite ceramic phosphors via a solid-state reaction method. It was observed that the introduction of Mn2+ ions created a secondary luminescence center with an emission peak centered at 580 nm. As the Mn2+ concentration increased, the emission peak redshifted from 580 nm to 591 nm, leading to a significant enhancement in the color rendering index of the ceramics. The cross-energy transfer between Tb3+ and Mn2+, Ce3+ ions augmented the absorption and conversion of blue light by the ceramics, thereby reducing the correlated color temperature greatly. Based on these findings, ceramics with a Ce3+ concentration of 3 at% and a Mn2+ concentration of 4 at% exhibited the highest CRI values (81.3 and 75.6) under both laser excitation and LED excitation, establishing them as strong candidates for achieving high color rendering in white LED/LD illumination applications.