Synthesis And Luminescence Properties Study Of Strontium Sodium Vanadate Doped With Rare Earth Dysprosium Ions

White LED has become the fourth generation green light source because of its advantages of low energy consumption,long lifetime,fast response and small size.At present,there are mainly two ways of white light LED:one is the combination of blue light chip and YAG:Ce³⁺yellow phosphor.However,the lack of red component leads to the high color temperature and low color developing index of white light LED.The other is the combination of near-ultraviolet chip and blue,green and red trichromatic phosphor powder.But the mutual reabsorption of trichromatic phosphor powder,the matching problem of each phosphor powder and ultraviolet LED chip and the complex process limit its widespread use.The development of a new type of adjustable cold and warm white phosphors which can be excited by near-ultraviolet LED chip can overcome such problems well.NaSrVO₄ has strong stability of crystal structure,and it's raw materials are cheap and easily available.The rare earth Dy³⁺can emit white light under the excitation of ultraviolet and near ultraviolet light.NaSrVO₄:Dy³⁺is a potential new type of white light emitting phosphor which is expected to be used as ultraviolet and near-ultraviolet LEDs.In this paper,the process parameters and luminescence characteristics of synthesis of NaSrVO₄:Dy³⁺by citric acid sol combustion were studied,and the possibility of its application in white LED was discussed.The NaSrVO₄:Dy³⁺powder material with high purity and white light under the excitation of near ultraviolet light at 347 nm was synthesized under optimized process conditions of 900?combustion reaction temperature and 1 holding time.Its emission spectrum is characterized by a blue emission peak at 484 nm(corresponding to⁴F_9/2?⁶H_15/2 transition of Dy³⁺ion)and a yellow light emission peak at 580 nm(⁴F_9/2?⁶H_13/2 transition of Dy³⁺ion),which are combined into white light.The doping concentration of Dy³⁺is 5 mol%,and the white light emission intensity of NaSrVO₄:Dy³⁺phosphor is the strongest.When the doping concentration of Dy³⁺increases to 6 mol%,the luminous intensity decreases and the concentration quenching effect occurs.Dy³⁺entering the NaSrVO₄matrix lattice to replace part of Sr²⁺leads to charge imbalance,which will produce vacancy V_Sr"and affect the luminous intensity of phosphors.The luminescence effect can be effectively improved by adding Li⁺to charge compensation agent.The experimental results show that when the content of Li⁺is 1 mol%,the luminescence intensity of the synthesized samples is enhanced most obviouslyThe alkaline earth metal ions Mg²⁺,Ca²⁺,and Ba²⁺partially replace Sr²⁺,respectively,can enhance the luminous intensity of NaSrVO₄:Dy³⁺samples.When their doping amounts are 0.03 mol,0.04 mol,and 0.04 mol respectively,high-purity NaSrVO₄:Dy³⁺phosphors without other impurities are still obtained,and the luminous intensity enhancement effect is most significant.Compared with NaSrVO₄:0.05Dy³⁺and NaSrVO₄:0.05Dy³⁺,0.0075 Dy³⁺,the combined phosphors of La³⁺and Dy³⁺have higher luminous intensity and quantum efficiency.This indicates that the addition of rare earth La³⁺can play an energy transfer role,transferring the absorbed energy to the luminescent center Dy³⁺ion,and improving the luminescence intensityThe results show that NaSrVO₄:Dy³⁺is a kind of white fluorescent material with potential application value in white LED.