Tunable color of Tb3+/Eu3+/Tm3+-coactivated K3La(PO4)2 via energy transfer: A single-phase white-emitting phosphor

A series of Tm3+, Tb3+, Eu3+ coped K3La(PO4)(2) phosphors was synthesized via solid-state reaction. The compounds were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectra as well as fluorescent decay curves. The energy transfers from Tb3+ to Eu3+ in the K3La(PO4)(2) host were investigated according to the Inokuti-Hirayama theoretical model which suggests they are of the resonant type via a dipole-dipole mechanism. By adjusting the doping concentrations of Tb3+, Tm3+ and Eu3+, a white emission can be reached in the K3La(PO4)(2) host. The energy transfer efficiency and the CIE coordinates of K3La(PO4)(2):RE3+ (RE = Tm, Tb, Eu) phosphors were calculated. In addition, the temperature-dependent emission showed good thermal stability of as-prepared phosphors. The obtained properties indicated that prepared compounds can be used as a single-component white emitting phosphor in WLEDs structures.