Preparation and optical properties of MgAl2O4-Ce:GdYAG composite ceramic phosphors for white LEDs

High-power light-emitting-diode (LED) lighting has attracted great attention in high-luminance applications. However, the color converters with high stability, high thermal conductivity and high efficiency are scarce. In this work, we developed promising MgAl2O4-Ce:GdYAG composite ceramic color converters in which a broadband yellow-emitting phosphor Ce:GdYAG is combined with a thermally stable spinel phase MgAl2O4. The microstructure, phase composition, photoluminescence and thermal stability were investigated in detail. After being packaged with blue LED, a high luminous efficacy value of 108.41m/W is achieved by the composite ceramic phosphor with the molar ratio (MgAl2O4 to Ce:GdYAG) of 1.0 and the thickness of 0.2 mm, as well as high CRI value of 70 and low CCT value of 4543. The light scattering nature of composite ceramic phosphors makes them an ideal and promising candidate for high-brightness white LEDs.