Synthesis And Properties Of Sr₃Al₂O₆:Eu²⁺ Florescence Material

Eu²⁺ is one of the most convenient exciting ion in aluminates luminescent materials, but the stable europium ion in the world is Eu³⁺, so it is necessary to reduce Eu³⁺ into Eu²⁺. The reducing potentiality of Eu³⁺ depends on the matrix materials which Eu³⁺ is welled in, in some matrix, such as CaS,CaF₂,SrAl₂O₄,Sr₂MgSi₂O₇ et al, it is easy to reduce Eu³⁺, but it is very difficult in Sr₃Al₂O₆. In this paper, the reducing method of Eu³⁺ in Sr₃Al₂O₆,the effect of synthesis technique parameter on the reducing of Eu³⁺ has been investigated, the changeable fluorescent phenomenon of Sr₃Al₂O₆:Eu²⁺ has also been observed.In the process of synthesis Sr₃Al₂O₆ by means of solid state reaction method, with the help of (NH₄)₃PO₄·3H₂O, Eu³⁺ can be reduced effectively into Eu²⁺ in thermo-carbon reducing atmosphere. When mol ratio Sr/Al=1.2-1.5mol, Eu/Sr=0.02, P/Al=0.1-0.15, synthesizing temperature at 1220±20℃, sintering time 4h, the sample synthesized has changeable fluorescence phenomenon, that is, it emits 520nm yellow green light only when excited by 364nm violet light, emits 520nm yellow green fluorescence of Eu²⁺ and red fluorescence of Eu³⁺ when excited by violet light 254nm. From the fluorescence spectrum and EPR results show that Eu²⁺ in Sr₃Al₂O₆:Eu²⁺ is ionized when excited by high energy violet light 520nm, that is Eu²⁺→Eu³⁺+e, and then induces the changeable fluorescence phenomenon.Further tests show, by adding Ba²⁺ et al to change the parameter of matrix, by energy transferring with the help of Ce³⁺, Gd³⁺ et al, the spectrum of Sr₃Al₂O₆:Eu²⁺ can be adjusted, so there is the possibility to synthesize the white light fluorescence with high brightness.