| When achieving the white light emission using the near UV irradiation and RGB phosphors, the existed series red phosphors such as sulphide, tungstate and molybdate cannot completely satisfy the needs of practical applications due to the poor color rendering index and short lifespan of the light emitting device caused by the low efficiencies excited by near UV LED and the unstable matrix. In this paper, we get inspiration from the same actual working conditions of high pressure mercury lamp phosphors and near UV LED phosphors, series phosphors of Sc0.93-xLnxVO4:Eu3+0.07(Ln=Y, La, Gd, Lu), Sc0.73-xY0.2VO4:Eu3+0.07,Bi3+x and Sc0.73Y0.2(M,VO4): Eu3+0.07(M=BO33-, PO43-) were prepared to search novel red phosphors with high efficiencies and stable matrix to satisfy the urgent needs of white LED industry. The main work and results are as follows:(1) Sc VO4:Eu3+: The doping of Eu3+ does not change the body-centered tetragonal structure of Sc VO4 and show concentration quenching, the optimum Eu3+ doping concentration is 7mol%. The excitation spectrum of samples covers broad band of 200-400 nm, and there are strong broadband absorption peak locates at 331.8nm and weak excitation peak locates at 396.6nm. The main emission peak locates at 331.8nm, which show the bright red light, and color coordinates are located in the red region.(2) Sc0.93-xLnxVO4:Eu3+0.07(Ln=Y, La, Gd, Lu): The emission intensity of samples is increased and the cost is decreased by the doping of Ln3+, and the emission intensity of Sc0.93-xLnxVO4:Eu3+0.07 was higher than that of Sc0.93VO4:Eu3+0.07. The emission intensity of Sc0.93-xLnxVO4:Eu3+0.07(Ln=Y, La, Gd, Lu) reach the maximum, up to 156%, 120%, 120% and 133% when the doping concentration of Y3+, La3+ were 20mol% and Gd3+, Lu3+ were 5mol%. The samples simultaneously show high quantum efficiency and low thermal quenching. The Sc0.88Lu0.05VO4:Eu3+0.07 shows high quantum efficiency of 94% and 37% under 330 nm and 397 nm, respectively. The Sc0.93-xLnxVO4:Eu3+0.07(Ln=Y, La, Gd, Lu) phosphor show high thermal stability with the rise of temperature. When the temperature raises to 100℃, the emission intensity maintain 85% of that in the room temperature.(3) Sc0.73-xY0.2VO4:Eu3+0.07,Bi3+x: The sensitization effect of Bi3+ on Eu3+ was investigated based on Sc0.73Y0.2VO4:Eu3+0.07 phosphors. The results show the excitation spectrum of Sc0.73-xY0.2VO4:Eu3+0.07,Bi3+x emerged redshift and the excitation intensity increase first and then decrease within the near UV excitation(360-410nm). The emission spectrum appear relevant pattern that the relative fluorescence intensity reach the maximum when the doping concentration of Bi3+ is 1mol% excited at 397 nm and the emission intensity was 2 times higher relative to Sc0.73Y0.2VO4:Eu3+0.07 phosphor, the emission intensity of samples was 1.5 times higher relative to Sc0.73Y0.2VO4:Eu3+0.07 phosphor. The Sc0.72Y0.2VO4: Eu3+0.07,Bi3+0.01 phosphor show high internal quantum efficiency and thermal stability, the high internal quantum efficiency is up to 91% under 330 nm excitation; When the temperature raises to 100℃, the emission intensity maintain 88% of that in the room temperature.(4) Sc0.73Y0.2(M,VO4):Eu3+0.07(M=BO33-, PO43-): The Sc0.73Y0.2(M,VO4):Eu3+0.07(M=BO33-, PO43-) red phosphors were synthesized. The influence of BO33- and PO43- doping on crystal structure and fluorescence properties were investigated. The results show that the boron-doping strengthen the absorption of samples within near UV wavelength and maintain the body-centered tetragonal structure of(Sc,Y)VO4:Eu3+. When n(V/B)=9/1 and n(V/P)=8/2 under 365 nm excitation, the fluorescence intensity of samples reach the maximum,up to 155%、135% respectively relatively to Sc0.73Y0.2VO4:Eu3+0.07. The internal quantum efficiency of Sc0.73Y0.2(V0.9B0.1)O3.9:Eu3+0.07 and Sc0.73Y0.2(V0.8P0.2)O4:Eu3+0.07 are respectively up to 64% and 56% under 397 nm excitation, which show high internal quantum efficiency. Besides, the samples show high thermal stability, especially for Sc0.73Y0.2(V0.9B0.1)O3.9:Eu3+0.07 phosphor, the relative luminous intensity maintain 92% when the temperature is 200℃, which show good thermal stability. |
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