Sol-gel synthesis of Eu3+/Bi3+ ions co-doped BaLa2WO7 phosphors for red-LEDs under NUV excitation and FEDs applications

Abstract

Eu3+ ions single-doped and Eu3+/Bi3+ ions co-doped BaLa2WO7 (BLWO) phosphors were synthesized by a citrate sol-gel method. The X-ray diffraction patterns confirmed their monoclinic phase with a space group P21/b after annealing at 1350°C. The morphological properties of the prepared BLWO: 0.09mol Eu3+ (i.e., BLWO:0.09Eu3+) and BLWO:0.09Eu3+/0.01Bi3+ phosphors were observed by field-emission scanning electron microscope and transmission electron microscope images. Under near-ultraviolet (NUV) excitations, the photoluminescence (PL) properties were investigated for the BLWO:Eu3+ and BLWO:Eu3+/Bi3+ phosphors. The PL results suggest that the both phosphors showed an intense characteristic red emission at 616nm due to the 5D0 → 7F2 electronic transition. The existence of energy transfer mechanism in between Bi3+ and Eu3+ ions was explained by their decay curves. Additionally, temperature-dependent PL emission spectra and quantum yield were studied for the optimized phosphor. By combing a 399nm NUV chip with the BLWO:0.09Eu3+/0.01Bi3+ phosphor, a red light-emitting diode was implemented. Furthermore, the cathodoluminescence (CL) properties were analyzed for the BLWO:0.09Eu3+ and BLWO:0.09Eu3+/0.01Bi3+ phosphors as a function of accelerating voltage and filament current. To estimate the CL potentiality, the BLWO:0.09Eu3+/0.01Bi3+ phosphor was compared with a commercial Y2O3:Eu3+ red phosphor. The Commission International de I-Eclairage chromaticity coordinates were calculated for the optimized phosphor samples.