微波合成对SrAl_2O_4:Eu^(2+),Dy^(3+)晶相和铕的价态的影响

Influence of Microwave on Phase Structures of SrAl_2O_4:Eu^(2+),Dy^(3+) and on Valence of Europium

为了在较低温度下合成性能优良的SrAl2O4∶Eu2+,Dy3+(SAO-ED)发光材料,采用溶胶-凝胶-微波法在900℃烧结30 min合成SAO-ED发光材料。产品的发光性能优于传统高温固相法1400℃烧结3 h制备的产品。根据Henderson和Taylor提出的公式对SrAl2O4的XRD数据进行了量化,计算出单斜晶系(M)和六方晶系的比例;结果表明,溶胶-凝胶-微波法制备的产品中只有单斜晶系存在,而高温固相法制备的产品中有六方晶系存在,六方晶系不发光。另外,产品采用XANES表征了Eu离子存在的价态,发现溶胶-凝胶微波法制备的产品中残留的Eu3+的比例远低于传统高温固相法制备的产品。以上两种原因导致了产品的发光性能优于高温固相法制备的产品。

In order to prepare luminescent materials with good properties at low temperature, SrAl2O4：Eu^2＋,Dy^3＋（SAO-ED） was synthesized by sol-gel-microwave method at 900 ℃ for 30 min. The luminescent properties of the product were higher than that of samples prepares by solid-state method at 1400℃ for 3 h. The proportion of monoclinic and hexagonal phases in SAO-ED was calculated using the parameter R proposed by Henderson and Taylor. The results showed that only the monoclinic polymorph was present in the samples prepared by sol-gel-microwavemethod, but monoclinic and hexagonal phases were both present in the samples prepares by solid-state method and hexagonal phase had no luminescence property. The valence of Eu in SAO-ED were characterized by XANES, the results showed that the amount of residue Eu^3 ＋ in samples prepared by sol-gel-microwave method was far lower than that in samples prepared by solidstate method. All these reasons explained why the luminescent properties of the product were higher than that of samples prepares by solidstate method.