Environment-Dependent Eu 2+ -Activated Ba 3 CaK(PO 4 ) 3 toward White-Light Emission by Chemical Cosubstitution of the (BO 3 ) 3- Anion Group.

Investigating the phosphors doped with single activators in a single component to realize white-light emission is urgently desired for phosphor-converted white-light-emitting diodes. In this work, on the basis of the chemical unit cosubstitution strategy, the new borophosphate phosphors Ba 3 CaK(PO 4 ) 3- x (BO 3 ) x :0.02Eu 2+ with a mixed anion group were prepared. Coupling structure refinement and photoluminescence analyses, Ba 3 CaK(PO 4 ) 3- x (BO 3 ) x consists of five different cationic sites with different coordination environments, with Eu 2+ occupying the three sites for Ba 2+ . In the process of partial substituting (BO 3 ) 3- for (PO 4 ) 3- , because of the greatly distorted coordination field generated from the difference in the geometric configurations between the two anion groups, a red shift and broadening of the emission bands occurs, resulting in a color-adjustable emission from blue to white. A phosphor-converted light-emitting diode has been successfully fabricated with the incorporation of an as-prepared Ba 3 CaK(PO 4 ) 2.6 (BO 3 ) 0.4 :0.02Eu 2+ phosphor and a 405 nm near-ultraviolet chip, which exhibits Commission International de I'Eclairage chromaticity coordinates of (0.31, 0.37) and a correlated color temperature of 6295 K. As demonstrated in the present work, an approach adopted from phosphate to borophosphate is conducted to develop high-quality phosphors.