Enhancing the color of inorganic yellow pigments using yellow fluorescent materials: The case of BiVO4, PbCrO4/(Y,Gd)AG:Ce3+, Sr2SiO4:Eu2+

This paper presents a novel approach to enhancing the color of inorganic yellow pigments using yellow fluorescent materials. The results demonstrate that the inclusion of phosphor leads to a significant improvement in various color attributes. Specifically, the addition of 15 %–20 % phosphor of YAG:Ce3+, (Sr,Ba)2SiO4:Eu2+ or YAG:Ce3+,Gd3+ in BiVO4 or PbCrO4 increases the brightness value (L*) by 5.0 %–8.7 %, the yellowness value (b*) by 4.2 %–9.2 %, and the color saturation value (C*) by 4.1 %–8.7 %. Furthermore, the reflections in the yellow region show a notable increase of 13.7 %–22.1 %, while remaining relatively low in the blue region (the complementary color of yellow), at approximately 10 %. This phenomenon can be attributed to the strong yellow emission performance of phosphor and the interesting synergistic effect between phosphor and pigment. The strong blue absorption of conventional pigment powder compensates for the inherent lack of blue absorption in phosphor alone, thereby maintaining a low reflectivity for the complementary color (blue) of yellow. Moreover, the fluorescence lifetime of yellow substantially increases with the addition of phosphor in the mixed material. This observation aligns with the quantitative relationship between reabsorption and fluorescence lifetime, suggesting widespread reabsorption of yellow emission. This finding supports our hypothesis that positive synergies occur within the mixed layer. In summary, incorporating a small amount of phosphor into conventional pigments effectively enhances the coloring effect of the pigments.