不同晶体结构Gd2(MoO4)3:Eu3+荧光粉的合成及其发光性能研究

采用溶胶凝胶-燃烧法,柠檬酸为络合剂合成出系列Gd₂(MoO₄)₃:Eu³⁺荧光粉.利用X射线衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱对样品的结构、形貌和发光性能进行了研究.XRD分析表明:稀土离子与柠檬酸为1:0.5时,800℃热处理获得单斜结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉.单斜结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉到正交结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉的转换可以通过改变稀土离子与柠檬酸摩尔比和热处理温度等合成条件实现.Gd₂(MoO₄)₃:Eu³⁺荧光粉的形貌受合成条件的影响.荧光光谱研究表明:Gd₂(MoO₄)₃:Eu³⁺荧光粉的主发射峰位于616 nm处来自于Eu³⁺的⁵D₀→⁷F₂电偶极跃迁.正交结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉发射强度明显高于单斜结构的荧光粉.计算⁵D₀→⁷F₂与⁵D₀→⁷F₁跃迁发射的相对强度比值表明:正交结构的Gd₂(MoO₄)₃:Eu³⁺中Eu³⁺局域环境的对称性较高。

Synthesis and Luminescence Properties of Gd2(MoO4)3:Eu^3+ Phosphors with the Different Crystalline Structures

A series of Gd2(MoO4)3:Eu^3+phosphors were prepared by a sol-gel combustion method with citric acid as complexing agent.The structure,morphology and luminescence properties of Gd2(MoO4)3:Eu^3+phosphors were characterized by XRD,SEM and fluorescence spectrum.The results of XRD indicate that Gd2(MoO4)3:Eu^3+ phosphors with monoclinic system could be obtained by annealing precursor of molar ratio of rare earth ions to citric acid being 1:0.5 at 800℃.The phase transformation from Gd2(MoO4)3:Eu^3+ phosphors with monoclinic to orthogonal structure could be achieved by changing annealing temperature and the molar ratio of rare earth ions to citric acid.The morphology of Gd2(MoO4)3:Eu^3+ phosphors are affected by synthesis conditions.The results of fluorescence spectra show that a main emission peak of Gd 2(MoO 4)3:Eu^3+ phosphors is at 616 nm due to the 5D0→7F2 electric dipole transition of Eu^3+.The emission intensity of Gd2(MoO4)3:Eu^3+ phosphors with orthogonal crystal system was significantly stronger than that of monoclinic system.The 5D0→7F2/5D0→7F1 relative emission intensity ratios calculated show the local symmetry environment around Eu^3+ increases in Gd2(MoO4)3:Eu^3+ phosphors with orthogonal structure compared with that of monoclinic structure.