Properties of transparent Ce:YAG ceramic phosphors for white LED

Transparent Ce:YAG ceramic phosphors were synthesized from the oxide powder which was produced by co-preparation method of the hydroxides. The Ce:YAG ceramics had a broad emission band peaked at 530 nm due to the 5d -> 4f transition of Ce(3+). The transmittances of the samples obtained were 70-87% at 800 nm. The absorption coefficient and emission intensity of Ce(3+) were increased with increasing thickness. Under 465 nm LED excitation, the color coordinates of the Ce:YAG ceramics shifted from the blue region to yellow region with increasing sample thickness, passing nearby the theoretical white point in the chromaticity diagram. The highest value of luminous efficacy of the ceramic white LED was 73.5 lm/W. (C) 2010 Elsevier B.V. All rights reserved.