【作者】 肖秀珍；

【导师】 闫冰；

【作者基本信息】 同济大学 ， 无机化学， 2008， 博士

【摘要】 稀土离子具有丰富的4f能级,成为高新技术所要求具备优异性能的重要元素。稀土铌酸盐、钽酸盐和磷酸盐微纳米发光材料呈现出安全、无污染、持续发光、颗粒细小、色彩多样等许多优良特性。本文采用两种方法合成稀土铌酸盐、钽酸盐和磷酸盐微纳米发光材料。一种方法是通过选取具有链状结构的稀土芳香羧酸配合物作为稀土反应源,再复合有机聚合物（如PEG）作为分散介质,结合其他功能组分,原位构筑具有网状结构的杂化前驱体,以其为前驱体通过热处理合成了一系列具有规则形貌的稀土铌酸盐和钽酸盐纳米材料,研究它们的发光性质,如:RENbO₄:RE³⁺（RE=Eu,Tb,Dy,Er,Sm）;（Y,Gd）NbO₄:Eu³⁺/Tb³⁺;LnNbO₄:Bi⁽3+0;LnNbO₄:xBi³⁺,Dy³⁺;GdTaO₄:Ln³⁺(Ln=Eu³⁺,Tb³⁺,Dy³⁺,Er³⁺,Sm³⁺,Pr³⁺);（Y,Gd）TaO₄:Eu³⁺;Zn₃Nb₂O₈:Er³⁺,Eu³⁺,Dy³⁺;LnVTa₂O₉:5 mol%Eu³⁺/Dy³⁺;YNb_xV_1-xO₄:Eu³⁺,Dy³⁺,Er³⁺,Sm³⁺;RE（Nb,V）O₄:x mol%Dy³⁺;RE（Nb,V）O₄:5 mol%Dy³⁺,xBi³⁺;RE（Nb,P）O₄:RE³⁺（RE=Eu,Tb,Dy,Er,Sm）;YNb_xTa_1-xO₄:Eu³⁺,Dy³⁺。另外,通过原位湿化学法构筑杂化前驱体合成蓝色发光体铈酸锶和铈酸锶掺三价铕离子、镝离子发光体。另外一种方法是利用水热法,通过调节水热温度和反应溶剂合成稀土磷酸盐纳米发光材料。首先,改变温度,以YPO₄,LaPO₄和GdPO₄为基质,研究在这种条件下,其形貌、结构和发光性质的变化。结论是,与在pH值为3—4和温度为160℃得到的产物比较,温度的改变使得颗粒尺寸和结构发生了变化。颗粒尺寸都增大,尤其是YPO₄和GdPO₄,都呈现微米棒形貌。其次,通过改变溶剂合成稀土磷酸盐发光体。研究溶剂的改变与稀土磷酸盐发光体形貌、结构和发光的关系。在相同pH和温度下,分别用水和无水乙醇作为溶剂,得到的稀土磷酸的形貌和结构相似,YPO₄是四方相结构和纳米颗粒的形貌;LaPO₄和GdPO₄属于六方相结构,分别呈现纳米线和纳米棒的形貌。然而,以DMF（N,N-二甲基甲酰铵）为溶剂,引起了产物的形貌和结构的改变。以LaPO₄为基质,通过调节DMF和蒸馏水的比例,来研究LaPO₄的形貌和结构的改变。发现:随着DMF体积的增加,LaPO₄的结构由六方相变为单斜晶系,而形貌由纳米线变为纳米颗粒。另外,以DMF为溶剂,研究DMF对反应产物的影响。对于轻稀土离子如La³⁺,Pr³⁺和Nd³⁺而言,得到的产物是白色粉末,与DMF的体积无关。而对于中间稀土离子,如从Sm³⁺到Dy³⁺,产物的形貌与DMF的体积有很大的关系。当体积较低的时候,易形成白色粉末;而当体积较高的时候,得到的是与反应釜形状相似的柱状凝胶。对于重稀土离子如Ho³⁺,Lu³⁺,Y³⁺,无论DMF体积是多少,最终产物都是有机-无机凝胶。同时,还用部分VO₄^3-取代了PO₄^3-,水热法合成了GdP_xV_1-xO₄:Eu³⁺发光体系,并研究了VO₄^3-含量与产物结构、发光性质的关系。最后,利用水热法合成了Zn₃（PO₄）₂:Eu³⁺纳米发光材料并研究了其发光性质。橙光发射⁵D₀→⁷F₁发光强度是最强的。同时,通过调节温度和pO值,得到了Zn₃（PO₄）₂:Eu³⁺纳米棒以及纳米颗粒红色发光材料。在温度为160℃下,当pH在3—8之间,能够生成正交晶系的含结晶水的磷酸锌掺Eu³⁺。另外,随着温度的升高,形貌和结构变化不大。更多还原

【Abstract】 Orthoniobates,orthotantalates and orthophosphates have been shown to be the hosts for rare earth ions to emit different luminescence due to their safety and stable properties.In this paper,using rare earth complexes aromatic carboxylic acid（ortho hydroxylbenzoic acid）as the rare earth species and composing with organic polymers Polyethylene（PEG）as dispersing medium template and urea as a fuel,the hybrid precursor have been formed by in-situ co-precipitation method.Then after the calcination of the hybrid precursors,several series of rare earth niobates and tantalates phosphors have been synthesized,which present regulation morphologies just like cobblestone,grain and column,such as RENbO₄:RE³⁺（RE=Eu,Tb,Dy,Er,Sm）, （Y,Gd）NbO₄:Eu³⁺/Tb³⁺,LnNbO₄:Bi³⁺,LnNbO₄:x mol%Bi³⁺,5 mol%Dy³⁺,GdTaO₄: Ln³⁺(Ln=Eu³⁺,Tb³⁺,Dy³⁺,Er³⁺,Sm³⁺,Pr³⁺),（Y,Gd）TaO₄:Eu³⁺,Zn₃Nb₂O₈:Er³⁺, Eu³⁺,Dy³⁺,LnVTa₂O₉:5 mol%Eu³⁺/Dy³⁺,YNb_xV_1-xO₄:Eu³⁺,Dy³⁺,Er³⁺,Sm³⁺, RE（Nb,V）O₄:x mol%Dy³⁺,RE（Nb,V）O₄:5 mol%Dy³⁺,x mol%Bi³⁺;RE（Nb,P）O₄: RE³⁺（Re=Eu,Tb,Dy,Er,Sin）:YNb_xTa_1-xO₄:Eu³⁺,Dy³⁺.Under UV excitation,they emit different luminescence.At the same time,blue Sr₂CeO₄ and Eu³⁺/Dy³⁺-doped Sr₂CeO₄ phosphors have been fabricated from the hybrid precursors and their luminescence properties have been investigated.Furthermore,LaPO₄:Eu³⁺/Tb³⁺nanowires,nanorods and nanoparticles have been synthesized by adjusting the hydrothermal solvent.Using anhydrous Ethanol as solvent, the as-formed LaPO₄ powders show pure hexagonal phase and nanowires-like morphology,just like the product prepared using distilled water as solvent.However, with the presence of DMF,the morphology and structure of LaPO₄ have been changed. With the volume ratio of DMF to distilled water increase,the structure has been changed from hexagonal phase to monoclinic phase and the morphology from nanowires to nanoparticles.Obviously without any template or the higher temperature or alkaline conditions,the control on the morphology and structure of LaPO₄:Eu³⁺/ Tb³⁺is possible through adjusting the volume ratio of DMF to distilled water. Additionally,using DMF（N,N-dimethylformamide）as solvents,the final product show different results,which depend on the nature of lanthanide ion.As for the light lanthanide ions from La³⁺to Nd³⁺,the white powders of lanthanide ions coprecipitated with PO₄^3-have been obtained.While for the medium lanthanide ions from Eu³⁺to Dy³⁺,the final products depend on the volume of the DMF solvents.When volume of DMF is large,the final products show white powders and while volume of DMF is small,the inorganic-organic gels have been formed.However,for heavy lanthanide ions,the inorganic-organic gels always have been obtained in spite of the volume of DMF.In all the emission spectra of Eu³⁺- doped rare earth orthophosphates phosphors, ⁵D₀-⁷F₁ orange emission line are predominant,indicating that more Eu³⁺ion occupies a site with an inversion center.Besides this,through altering the hydrothermal temperature,Eu³⁺-doped YPO₄,LaPO₄ and GdPO₄ phosphors have been obtained, which present different morphologies and structures by comparing to the product under identical temperature.Especially,tetrahedral phase YPO₄:Eu³⁺exhibits interesting column-like morphology.Finally,Zn₃（PO₄）₂:Eu³⁺nano-sized phosphors have been prepared by the hydrothermal and the emission lines of Eu³⁺have been examined,among which,the intensity of ⁵D₀-⁷F₁ orange emission is the strongest.By changing the hydrothermal temperature and pH Value,the morphology and structure of the final products have been investigated.As a result,when the pH Value is from 4 to 8,the orthorhombic phase of hydrated Zn₃（PO₄）₂:Eu³⁺have been obtained,which show nanorods and nanoparticles,respectively.However,the morphology and structure of hydrated Zn₃（PO₄）₂:Eu³⁺show little difference with the increasing of the hydrothermal temperature.更多还原