Synthesis And Photolunminescence Properties Of Phosphates Doped With Rare Earth Ions For White-light LED

The white light emitting diode（LED）has attracted increasing attention in recent years due to their excellent properties such as small bulk,low power consumption,high brightness,long operating time,environmental benefit and color diversity,which compared with traditional lighting.UV-LED has good advantages of color control and uniform,which compared with blue LED and trichromatic LED.The properties of luminescent materials play a major role in UV-LED,so it is important to find a suitable phosphor for UV-LED.Phosphate system has good absorption ability and high conversion efficiency.Based on those reason,the following tasks are finished in this paper.1.The phosphors LaPO₄:RE(RE=Eu³⁺,Tb³⁺)and BiPO₄:RE(RE=Dy³⁺,Tb³⁺)were synthesized by the hydrothermal method in this work and the optical properties of these materials were studied.The LaPO₄:Eu³⁺ was excited by near –ultraviolet of 394 nm,it is a red emitting phosphor.The LaPO₄:Tb³⁺ was excited by near –ultraviolet of 369 nm,it is a green emitting phosphor.The BiPO₄:Dy³⁺ was excited by near –ultraviolet of 350 nm,it is a white emitting phosphor.The BiPO₄:Tb³⁺ was excited by near –ultraviolet of 369 nm,it is a green emitting phosphor.2.The phosphors Na₃Y（PO₄）₂:RE(RE=Eu³⁺,Tb³⁺)were synthesized by hydrothermal method,and their morphological and spectral properties were studied.The particles show spindle-shaped and have uniform size.Na₃Y（PO₄）₂:Eu³⁺ is a red emitting phosphor and Na₃Y（PO₄）₂:Tb³⁺ is a green emitting phosphor.3.The Zn₃（PO₄）₂ and Zn_2.75（PO₄）₂:Tb_0.25³⁺ phosphors were synthesized by hydrothermal method.The optimum pH value has been found at the range of 3–9 for the preparation of Zn₃（PO₄）₂ and luminescent properties on which were studied subsequently.The morphologies of Zn₃（PO₄）₂ are relative with the pH value of the reaction predecessor.Zinc phosphate was synthesized at the pH value below 7.Mixtures of Zn₃（PO₄）₂ and NH₄ZnPO₄ appeared at the value of pH=7.Pure NH₄ZnPO₄ was prepared in the alkaline environment.Zn_2.75（PO₄）₂:Tb_0.25³⁺ is a green emitting phosphor.4.The phosphors of LiBaPO₄:Dy³⁺ were synthesized by the high temperature solid state method and the spectral properties and thermoluminescence properties of these phosphor was investigated.The results show that the material can be excited by 370⁴10 nm,and it is a white emitting phosphor.At the same time,it is a kind of good thermoluminescenc material.