Bright yellow pigment and broadband NIR-I phosphor based on octahedral coordinated mix-valence Cr in Ca 2 LiScB 4 O 10

The novel yellow color compounds Ca 2 LiSc 1- x B 4 O 10 : x Cr with NIR emission were successfully synthesized by the solid state method. All samples are of pure phases through X-ray diffraction results. The oxidation state of Cr dopant in this borate is confirmed to be mix -valence ( +3 and + 6) using XPS analysis. Based on the analysis of Cr oxidation state and UV-Visible spectrum, the Cr-O charge transfer from Cr 6 + octahedral sites in the visible light range is the reason for the yellow color. Meanwhile, a near infrared (NIR) broadband emission at 800 nm with FWHM of 141 nm is from Cr 3 + in octahedron, which could be effectively excited by 495 and 630 nm. The yellow chromophore and NIR lumophore are successfully combined in Ca 2 LiScB 4 O 10 : Cr using economical raw materials through simple method, and may be applied in the field of yellow pigment and NIR phosphor.