【作者】 张爱玉；

【导师】 吕孟凯；

【作者基本信息】 山东大学 ， 材料学， 2009， 博士

【摘要】 金属硫族化合物是一类重要的功能材料,在光学、电子学及光电领域都有着重要的应用。金属硫族化合物纳米材料更是现代材料学研究的热点。纳米材料的性质取决于其制备过程及组成基元的尺寸、形貌、分布等特点,因而对纳米材料的制备方法和形貌控制的研究是纳米材料研究的重点。本论文的第二、三章,我们选取一种三元硫化物和多种二元硒/硫/碲化物为研究对象,开发出几种简便、环保的制备方法;对产物的相和形貌的形成及控制进行了研究。另外,硫族化合物中的复合金属氧化物是稀土离子掺杂荧光粉最常用的基质材料,对基质材料的选择和改性是获得更强更好发光材料的重要手段。在第四章我们就选取性能稳定的金属锆酸盐作为对象,对其进行了制备、稀土离子掺杂及发光性质的研究。在第一章中,对纳米材料、纳米材料的制备、发光理论与发光材料进行了阐述,并对金属硫族化合物纳米材料制备的一些研究现状进行了简要的介绍。在第二章中,使用表面活性剂辅助的乙二醇回流法制备了CuInS₂纳米空心球。空心球的平均尺寸在80-100nm,球壁由10nm左右的CuInS₂纳米颗粒组成。提出一个囊胞模板的机制来解释空心球的形成。表面活性剂十六烷基三甲基溴化胺（CTAB）在空心球结构的形成过程中起到重要作用,一定浓度的CTAB在乙二醇溶液中形成均匀的球形囊泡,产物以CTAB囊泡为模板析出,并进一步结晶化形成CuInS₂纳米空心球。另外,在CuInS₂的形成过程中,乙二醇不仅是很好的溶剂而且是将Cu²⁺还原为Cu⁺的还原剂;原料中微量水的存在对CuInS₂的形成也是必要的。针对目前金属硒化物纳米材料的制备存在像原料有毒、反应条件苛刻等一些问题。在第三章中,我们介绍了两种合成金属硒（硫/碲）化物纳米结构的方法。这两种方法均有操作简单、毒性小、成本低、可控性好等特点。利用这两种方法进行了不同相和形貌的可控合成研究;对产物进行了结构和形貌表征,并提出了各种不同的相和形貌的形成机理。第一种方法是乙酸盐.石蜡法,用这种方法合成了一系列的硒/硫/碲化物,产物表现出多种形貌。讨论了产物的相和形貌的形成机制。石蜡代替有毒的TOP溶解硒（硫/碲）粉形成均一的溶液。油酸可以与各种金属乙酸盐形成可溶性的油酸盐前驱体,保证了金属离子与Se（S/Te）的石蜡溶液的充分反应,并使该方法适用于多种金属的硫族化物的合成。形貌的形成主要受两个因素影响,产物自身的晶体结构和油酸对晶面的作用。对于乙酸盐-石蜡法中产物相和形貌的控制,选取了具有多个相的硒化铜作为对象,研究了反应条件对其相和形貌的影响。通过调节反应参数可以控制合成的硒化铜为CuSe或者Cu_2-δSe;不同硒化铜相的形成主要受两个因素——氧化还原性和稳定性控制。另外通过控制油酸的量可以调节Cu_2-δSe的组分δ值。所得产物存在两种不同的形貌,纳米片和纳米片与纳米线的混合。提出了一个浓度控制的生长机制来解释不同形貌的生成。使用表面活性剂十二烷基苯磺酸钠（SDBS）修饰可以获得在水溶液中分散性很好的CuSe纳米片。第二种方法为乙二醇法,采用这一方法我们在同一体系中可以选择合成PbSe纳米晶或者Se微/纳米棒;这是一个动力学竞争的过程,控制较高的反应温度有利于PbSe纳米晶的形成,低温有利于Se微/纳米棒的生成。离子性表面活性剂的使用更有利于获得形貌规则的产物;阳离子表面活性剂的使用更有利于PbSe相的生成。该反应还可在多个不同金属阳离子/表面活性剂的体系中进行,形成Se微/纳米棒和其他一些硒化物纳米晶。第四章以发光性质研究为主,采用溶胶-凝胶-燃烧法制备了纯相和稀土离子掺杂的金属锆酸盐——钙钛矿结构的SrZrO₃和烧绿石结构的RE₂Zr₂O₇的纳米晶粉末。对其进行了结构和发光性质表征,发现了一些新的发光性质以及发光性质与结构特点的联系。首先在300℃的低温下引发燃烧反应制备出片状结构的SrZrO₃纳米晶粉末。700℃的二次烧结可以去除残留的有机物,并提高产物结晶性。首次在未掺杂的SrZrO₃中检测到了荧光发射,位于400nm左右的缺陷中心发光。二次烧结可大幅度提高该发光强度。采用700℃下的直接燃烧法还制备出了多孔形貌的SrZrO₃纳米晶粉末以及Eu³⁺掺杂的SrZrO₃纳米晶粉末。Eu³⁺掺杂的SrZrO₃在紫外光的激发下表现出很强的红光发射。用不同波长的光激发样品可以获得纳米晶内部的结构信息。该荧光粉具有较高的稳定性。第二部分,通过600℃下引发的燃烧反应制备了一系列的RE₂Zr₂O₇（RE=La、Nd、Eu、Y）粉末,产物结构为烧绿石或者缺陷萤石,形貌为团聚的纳米晶粒。除Eu₂Zr₂O₇表现出Eu³⁺的特征发光外,所有样品的发光都来源于其自身的氧弗兰克尔缺陷。对RE₂Zr₂O₇进行Pb²⁺掺杂可以增强该发光的强度,但对不同的RE₂Zr₂O₇增强幅度相差很大。结构与发光性质分析发现,RE₂Zr₂O₇的缺陷发光强度取决于晶体结构的有序性。我们提出一个通过缺陷荧光强度来判断RE₂Zr₂O₇晶体从烧绿石结构到缺陷萤石结构有序性变化的方法。考虑到发光强度的相对性,可以通过比较二价金属离子掺杂对RE₂Zr₂O₇发光强度的增强幅度来判断RE₂Zr₂O₇晶体结构的有序性程度:增幅大则有序程度高,增幅小则有序程度低。我们还对La₂Zr₂O₇和Y₂Zr₂O₇进行了稀土激活离子的掺杂。Eu³⁺掺杂的La₂Zr₂O₇、Y₂Zr₂O₇纳米晶粉末均表现出Eu³⁺特征的橙红光发射,发光强度随掺杂浓度的增加而增强。Dy³⁺掺杂的La₂Zr₂O₇分别在575nm、480nm两处有黄、蓝光发射,由于存在荧光浓度猝灭,发光强度随掺杂浓度的增加先增强后减弱,2.0mol%为Dy³⁺的最佳掺杂浓度。Eu³⁺、Dy³⁺共掺的La₂Zr₂O₇样品表现为Eu³⁺的发光。由于存在Dy³⁺到Eu³⁺的能量传递,Eu³⁺、Dy³⁺共掺的样品发光强度明显高于单掺Eu³⁺的样品。对Eu³⁺、Dy³⁺离子掺杂的La₂Zr₂O₇、Y₂Zr₂O₇纳米晶粉末进行不同波长光激发以及不同浓度掺杂时,发射光谱的细节变化揭示了晶体结构的特点。在第五章中,我们对本论文的内容进行了总结。更多还原

【Abstract】 Metal chalcogenides are important functional materials with wide applications in the optical,electronic and optoelectronic field.The nanomaterials of metal chalcogenides are even the hot subject of the material researches.The properties of the nanomaterials depend on their process history,size,morphology and distribution.Thus the preparation method and the morphology controlling become the key parts of the nanomaterial researches.In Chapter 2 and 3 of this thesis,we took one ternary sulfide and a series of binary selenide/sulfides/tellurides as the objects of study,developed several handy and environment-friendly methods to synthesize these chalcogenides,and investigated the formation process and the control of the products and their morphology.The polyoxides, as one kind of the chalcogenides,are the most useful luminescence host materials,and phosphors with better luminescent property can be developed by choosing and modifying the host materials.In Chapter 4,we chose the stable zirconates as the object, and carried out a research on the preparation,rare earth ions-doping and luminescence property of them.In Chapter 1,we introduced the conception,preparation method of nanomaterials,the theory of luminescence and the luminescent materials,and presented the current research status of the metal chalcogenide nanomaterials preparation.In Chapter 2,CuInS₂ hollow nanospheres were prepared through a surfactantassisted glycol-reflux method.The hollow spheres have an average diameter of 80-100 nm,and the shells of the hollow spheres are composed of CuInS₂ nanoparticles of about 10 nm in size.A vesicle-template mechanism was proposed to explain the formation process of the hollow structure,during which amorphous hollow structures are first formed on the surfactant template and then crystallize in the refluxing process. Furthermore,in the reaction,glycol acted not only as a good solvent but also as a reducer reducing Cu²⁺ to Cu⁺.The trace water in the raw materials was also required for the formation of CuInS₂. Considering the problems existing in the present synthesis methods of selenide nanomaterials,such as the toxic reagents and rigorous reaction condition,we introduced in Chapter 3 two methods to prepare nanoscaled metal slenides（sulfides or tellurides）. Both of the methods are featured with easy operation,low toxicity,low cost and high controlling.Phase-and morphology-controllable synthesis of the various chalcogenide materials were researched through the two methods,the structure and morphology of the products were characterized,and several mechanisms were proposed to explain the formation of the different phase and morphology.Firstly,it is the Acetate-Paraffin method,by which we synthesized a series of selenides/sulfides/tellurides.The products showed various morphologies.Mechanisms were proposed to explain the formation of the different chalcogenides and their nanostructures.Paraffin liquid instead of TOP was used to dissolve Se（S/Te） powder.Oleic acid can react with each metal acetate to form the soluble M-OA complex,promising the thorough reaction between metal cations and Se（S/Te）/paraffin solution,and thus this method is suitable for the preparation of many metal chalcogenides.The morphologies of the chalcogenides are mainly affected by two factors,the crystal structure and the action of oleic acid on the crystal faces.To examine the phase and morphology control of the products from the Acetae-Paraffin method,we carried out an in-depth study on copper selenide,which show complexity of composition and structure.CuSe or Cu_2-δSe was selectively synthesized by adjusting the reaction parameters.The formation of the different phases of copper selenide is determined by two elements—the redox and stability.Theδvalue of Cu_2-δSe can also be adjusted by changing the oleic acid amount.The products showed two morphologies, nanoflakes,or the mixture of nanoflakes and nanowires.A concentration-limited growth mechanism was proposed to explain the various morphologies of Cu_2-δSe and CuSe forming at the different condition.The SDBS-modified CuSe nanoflakes exhibited good dispersivity in water.The other method is based on ethylene glycol.PbSe nanoparticles and Se micro/nanorods can be selectively synthesized in the same reaction system by this glycol method.It is a kinetic competition process.PbSe nanocrystals would form when the reaction temperature was controlled at a high level,while the low temperature favored the formation of Se rods.The products showed more regular morphology when ionic surfactants was used.The PbSe phase was easier to form when the surfactant was cationic.This method can be used in the other metal cation/surfactant system,resulting in Se micro/nanorods and other selenide nanocrystals.The research emphasis in Chapter 4 switched to the luminescence property.Pure and doped metal zirconates—perovskite-structured SrZrO₃ and pyrochlore-structured RE₂Zr₂O₇ nanocrystals were prepared through a facile sol-gel-combustion method.The products were characterized by the crystal structure and luminescence property,and some new luminescence properties and relationship between structure and luminescence were discovered.Firstly,SrZrO₃ nanocrystalline flakes were prepared through a combustion reaction ignited at a temperature as low as 300℃.The further calcination at 700℃removed the organic residues and improved the crystallinity of the products.For the first time,we detected a luminescence at 400nm,which might originate from the defect centers in the nanocrystals.The intensity of this luminescence was dramatically enhanced after the further calcination,due to the removal of organic residues which has a deleterious effect on the luminescence.Porous and Eu³⁺-doped SrZrO₃ nanopowders were prepared by combustion at 700℃.Eu³⁺-doped SrZrO₃ emitted strong red light under UV excitation.The structure details of the nanocrystals can be revealed by exciting the products with light of different wavelength.The Eu³⁺-doped SrZrO₃ phosphor showed a high stability of luminescence.Secondly,a series of RE₂Zr₂O₇ （RE=La,Nd,Eu,Y） powders were prepared through the combustion reaction ignited at 600℃.The products showed crystal structure of pyrochlore or defected fluorite,and morphology of aggregated nanocrystals.Except the characteristic luminescence emission of Eu³⁺ for Eu₂Zr₂O₇,all the samples showed luminescence originating from the intrinsic oxygen Frenkel defect of the crystals.The intensity of this emission can be increased by the doping of Pb²⁺.The amplitude of the increase varies widely for different RE₂Zr₂O₇.Analyzing the crystal structure and luminescence property of RE₂Zr₂O₇,we found that the luminescence intensity of RE₂Zr₂O₇ is intimately related to the ordering degree of their crystal structure.So we proposed a method to judge the disordering degree of RE₂Zr₂O₇（from pyrochlore structure to defected fuorite structure） according to the luminescence intensity of them.Considering the luminescence intensity is relative,the disordering degree can be estimated by the increase amplitude of the luminescence after the doping of Pb²⁺.The increase amplitude is larger,the ordering degree is higher,and the increase amplitude is smaller,the ordering degree is lower. La₂Zr₂O₇ and Y₂Zr₂O₇ nanocrystals were doped with rare earth ions.Eu³⁺-doped La₂Zr₂O₇ and Y₂Zr₂O₇ nanocrystals showed orange-red emission from the characteristic transition of Eu³⁺.The luminescence intensity increased with the Eu³⁺ concentration. Dy³⁺-doped La₂Zr₂O₇ nanocrystals emited yellow and blue light at 575nm and 480nm respectively.The luminescence intensity first increased and then decreased with the Dy³⁺ concentration because of the luminescence concentration quenching,and 2.0mol% is the best doping concentration of Dy³⁺.Eu³⁺,Dy³⁺-codoped La₂Zr₂O₇ nanocrystals only showed the characteristic luminescence of Eu³⁺.The luminescence intensity of Eu³⁺,Dy³⁺-codoped La₂Zr₂O₇ nanocrystals is much higher than that of the samples only doped with Eu³⁺,due to the energy transfer from Dy³⁺ to Eu³⁺ in the codoped sample. There was a change in the fine structure of the emission spectra when the excitation wavelength or Eu³⁺ concentration was altered,which can disclose the structure feature of La₂Zr₂O₇ and Y₂Zr₂O₇ nanocrystals.In Chapter 5,a concise summary of the contents was given.更多还原