Energy transfer and luminescent properties of a green-to-red color tunable Tb3+, Eu3+ co-doped K2Y(WO4)(PO4) phosphor

A color-tunable Tb3+, Eu3+ co-doped K2Y(WO4)(PO4) phosphor was prepared by solid-state method. The excitation peak wavelength of the resulting phosphor was 377 nm and the emission peak wavelengths were at 545 nm, attributed to the 5D4 → 7F5 transition of Tb3+, and at 613 mm, attributed to the 5D0 → 7F2 transition of Eu3+. Both cross relaxation and exchange interaction are responsible for the Tb3+ → Eu3+ energy transfer in K2Y(WO4)(PO4): Tb3+, Eu3+ system. The intensity ratio of the two peaks could be freely controlled by varying the Eu/Tb ratio, allowing color to be tuned over a wide range from green to red.