Ca3Lu(GaO)3(BO3)4:Eu3+: A novel high-brightness and thermal-stable red-emitting phosphor for white LEDs

Novel red-emitting Ca3Lu1-x(GaO)(3)(BO3)(4):xEu(3+) (CL(1-x)GB:xEu(3+); x=0.1-1.0) phosphors were synthesized for the first time via a high-temperature solid-state reaction. XRD, excitation and emission spectra, decay lifetimes, internal quantum efficiency, and thermal stability were studied. The results showed that under 397 nm UV light excitation, CL(1-x)GB:xEu(3+) phosphors exhibited bright red emissions peaking at 597 nm, 621 nm, 649 nm, and 693 nm, due to the D-5(0)-> F-7(J) (J = 1, 2, 3, 4) transitions. The optimal concentration of Eu3+ ions was 70 mol%. The Commission International de I'Eclairage (CIE) chromaticity coordinates, internal quantum efficiency, and color purity of the CL(0.3)GB:0.7Eu(3+) sample were determined to be (0.659, 0.339), 84%, and 91.1%, respectively. The temperature-dependent emission spectra of the CL(0.3)GB:0.7Eu(3+) phosphors revealed that emission intensity of all the characteristic peaks of Eu3+ at 423 K still remained about 83.6% in comparison with that at 303 K. Finally, under the current of 120 mA, bright white light with CIE chromaticity coordinates of (0.3804, 0.3804) and high color rending index of 88.2 was obtained by the fabricated prototype white light-emitting diode (WLED) device. The characteristics of the Eu3+-activated Ca3Lu(GaO)(3)(BO3)(4) (CLGB) red-emitting phosphors confirmed that CL(1-x)GB:xEu(3+) phosphors have excellent properties for the practical application in the WLEDs.