Chelation-controlled compound transition of luminescent fluoride crystals

It is interesting that the natural phenomenon of chelator citrate stabilizing nanocrystals in bone could be learned and utilized in manipulating man-made nano-materials. During the synthesis of upconversion luminescent fluorides, it appeared that, the more citrate participated, the more difficult the resultant material transformed from cubic phase KY3F10 nanocrystals, through hexagonal KYF4, to orthorhombic YF3 crystals or mesocrystals, which clearly indicates the critical role of citrate in stabilizing KY3F10 nanocrystals. Particles with different size, morphology, composition, and phase were controlled through the only variation of citric acid content. Meanwhile, the self-assembled mesocrystals showed emergent luminescent property with 63 times higher intensity, compared with the nanocrystals. The same sized YF3 single crystals and YF3 mesocrystals also exhibited dramatic difference in luminescent intensity.