Synthesis and photoluminescence properties of the novel Eu3+-activated CaNa(PO3)3 phosphors

Abstract

In this paper, Eu3+-doped CaNa(PO3)3 phosphors were successfully synthesized by the conventional solid-state method. Their phase purities and microstructure as well as luminescence properties were systematically investigated by X-ray diffraction, scanning electron microscope, and photoluminescence spectrum. The most intense excitation band centered at 394 nm suggested the sample showed a high absorption to n-ultraviolet light. Exposed to n-ultraviolet light, the orange-red luminescence could be observed, which was ascribed to the dominated 5D0 → 7F2 transition. Concentration quenching occurred as the Eu3+ doping concentration exceeded the optimal value (x = 0.3). According to our calculations of critical distance Rc (3.92 A) and θ (= 2.85), it is believed that exchange interaction is responsible for the energy transfer mechanism in CaNa(PO3)3. The concentration dependence of decay lifetime was analyzed in detail, and it revealed the existence of self-quenching and self-trapping effect in the process of concentration quenching. The Judd–Ofelt (J–O) theory was used to analyze the symmetry of the surrounding environment of Eu3+. The quantum efficiency of CaNa(PO3)3:0.3Eu3+ was measured to be 27.54%. Besides, the CIE chromaticity coordinates and color purity of CaNa(PO3)3:0.05Eu3+ were calculated to be about (0.651, 0.348) and 95%, respectively. These findings indicate that the orange-red phosphor CaNa(PO3)3:Eu3+ has great promise in n-UV-pumped w-LEDs.