Preparation of Transparent Ce³⁺:GdYAG Ceramics Phosphors for White LED

Transparent Ce:GdYAG ceramics were synthesized in the composition of (Gd Y_0.999-Ce_0.001)₃Al₅O₁₂ using a co-preparation method of the hydroxides. The maximum value of parallel light transmittance of the sample was 80 % at 800 nm. The samples showed a broad emission band due to the 5d→4f transition of Ce³⁺. The emission peak wavelength red-shifted from 530 nm to 560 nm with increasing Gd content. The maximum QY values of the samples with different Gd concentration were 85 ∼ 95 %. The color coordinates of the Ce:GdYAG ceramics based white LED located near the theoretical white point by optimizing the thickness. The Ra value improved from 65 to 81 with increasing Gd content.