| Summary: | Lu<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce<sup>3+</sup> phosphor ceramics were fabricated by vacuum sintering. On this basis, a bi-layer composite phosphor was prepared by low-temperature sintering to cover the phosphor ceramics with a layer of SrAlSiN<sub>3</sub>:Eu<sup>2+</sup>-phosphor-in-glass (PiG). The optical, thermal, and colorimetric properties of LuAG:Ce<sup>3+</sup> phosphor ceramics, SrAlSiN<sub>3</sub>:Eu<sup>2+</sup> phosphors and SrAlSiN<sub>3</sub>:Eu<sup>2+</sup>-PiG were studied individually. Combining the bi-layer composite phosphors with the blue LED chip, it is found that the spectrum can be adjusted by varying the doping concentration of SrAlSiN<sub>3</sub>:Eu<sup>2+</sup>-PiG and the thickness of Lu<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce<sup>3+</sup> phosphor ceramics. The maximal color rendering index value of the white LED is 86, and the R9 is 61. Under the excitation of a laser diode, the maximum phosphor conversion efficacy of the bi-layer composite phosphors is 120 lm/W, the R<sub>a</sub> is 83, and the correlated color temperature is 4534 K. These results show that the bi-layer composite phosphor ceramic is a candidate material to achieve high color rendering index for high brightness lighting.
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