Ce: YAG- Al 2 O 3 composite ceramics are regarded as highly promising materials for laser illumination application due to their high luminous efficacy and thermal stability. Nevertheless, the Ce: YAG 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) 3 Al 5 O 12 –Al 2 O 3 composite ceramic phosphors via a vacuum solid-state sintering method. It was observed that the introduction of Mn 2+ ions created a second luminescence center with an emission peak centered at 580 nm. As the Mn 2+ 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 Tb 3+ and Mn 2+ , Ce 3+ 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 Ce 3+ concentration of 3 at% and a Mn 2+ 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.
Qingle Pang,Wenlei Liu,Jianxing Shen,Tailin Wang,Chuanbing Cheng,Yuanhui Liu,Xiujun Han
Yttrium aluminum garnet (YAG) phosphor transparent ceramics prepared via vacuum hot pressing (HP) suffer from carbon contamination owing to the graphite mould used in the HP system. The conventional method was to dope LiF as a decarburizing agent, but carbon contamination cannot be effectively prevented when preparing Ce:YAG ceramics via a solid-phase reaction combined with HP sintering. In this study, we report the fabrication of highly transparent Ce:YAG ceramics via HP sintering with a flexible hexagonal boron nitride (BN-h) wrapping, which prevents carbon contamination of the samples caused by the graphite mould used in the process. High-transmittance Ce:YAG ceramics were prepared at a medium temperature of 1600 °C and a low vacuum pressure of 10 −1 Pa.
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