【作者】 刘威；

【导师】 刘晓旸； 赵旭东；

【作者基本信息】 吉林大学 ， 无机化学， 2015， 博士

【摘要】 稀土因其优良的光学、电学、磁学等物理性质，已被广泛的应用于生活中的各个方面。作为一种传统材料，硅酸盐的合成和应用研究一直是科研工作者研究的热点。而作为硅酸盐材料的新秀，具有规则孔道结构的硅酸盐化合物在近几十年的研究中也表现出许多优异的性质，并在催化、吸附等方面表现出巨大的应用潜力。将稀土元素独特的发光性质与微孔硅酸盐均一的孔道性质有机的结合在一起，一直是人们感兴趣并不断探索的研究课题。微孔稀土硅酸盐的合成大多都是采用中温水热法在200°C以下的温度条件下合成的，反应容器为不锈钢反应釜。本论文通过Quickpress3.0活塞-圆筒式高压反应装置和HR-1B-2型LECO高温高压水热反应装置，尝试在更高的压力和温度条件下，对具有新颖结构的微孔稀土硅酸盐/锗酸盐化合物的合成进行研究。在0.5~1GPa压力范围，300~700°C温度范围内成功合成出了一系列结构新颖的稀土硅酸盐及锗酸盐化合物，并对它们的晶体结构和荧光性质进行了研究。（1）采用高温高压合成方法，成功合成出了一个新的Na15Eu3Si12O36单晶。通过单晶X射线衍射分析对其晶体结构进行了解析，并且用粉末X射线衍射和X射线能谱分析对单晶解析的结果进行了验证。单晶结构解析的结果表明，该晶体是由[Si6O12]n12n-环硅酸盐阴离子和EuO6八面体通过共用顶端O原子而相互连接所构筑成的三维开放骨架结构。该结构含有由EuO6八面体和SiO4四面体共同限定组成的沿[010]方向的6元环孔道结构。同时，单晶解析的结果表明，在其结构中Na(2)+和Na(3)+离子的位置分别被Eu(2)和Eu(3)部分占据，这种按统计无序的Eu/Na占有率无序对Na15Eu3Si12O36的荧光性质有着重要的影响，而这一结果在对其荧光性质测试中被验证。（2）在高温高压条件下，成功合成出了具有新结构的铕硅酸盐，其化学构成为Na3EuSi6O15·1.47H2O。单晶X射线衍射晶体结构解析的结果表明，该晶体是由波浪形SiO4四面体单层之间通过EuO7多面体相互连接起来而形成的三维开放骨架结构。SiO4四面体所形成的单层沿[010]轴方向具有4，5，6，8元环孔道结构。Na3EuSi6O15·1.47H2O的三维骨架结构中存在着由EuO7多面体和SiO4四面体限定形成的沿[100]方向的4，8元环孔道结构，以及沿[001]方向的5，6元环孔道结构。对其热稳定性和荧光性质的研究表明，它的结构在800°C依然可以稳定存在，并且表现出红光发射。这些结果证明Na3EuSi6O15·1.47H2O是一种具有良好热稳定性的荧光材料。（3）采用高温高压熔盐法，以KF·2H2O和KOH作为助熔剂，成功合成出了一个具有新结构的含氟微孔铕硅酸盐，其化学构成为K2EuSi4O10F。通过单晶X射线衍射、粉末X射线衍射分析确定了其晶体结构。K2EuSi4O10F的结构是由SiO4四面体所构成的沿b轴方向的管状链，以及沿b轴方向排列的EuO4F2八面体无限链之间通过共用顶端的氧原子而相互连接形成的沿b轴方向具有6，8元环孔道结构的三维开放骨架结构。对其荧光性质的研究表明，K2EuSi4O10F晶体具有强烈的红光发射，是一种具有潜在应用价值的红光荧光材料。（4）采用HR-1B-2型LECO高温高压水热反应装置，成功合成出了一系列具有2D层状结构的稀土锗酸盐：K3[LnGe3O8(OH)2]。通过单晶X射线衍射、粉末X射线衍射、EDS、红外光谱对其结构进行了研究。单晶结构分析表明K3[LnGe3O8(OH)2]是由[GdGe3O8(OH)2]n3n阴离子骨架所构成的二维层状结构，其基本结构由GeO4/GeO4H四面体和GdO6八面体通过桥氧相互连接而形成的平行于（010）晶面方向的GdGe3O8(OH)2单层，而单层之间则由O H···O键相互连接形成沿b轴方向按[ABAB…]顺序排列。对共掺杂样品K3[Gd1-xTbxGe3O8(OH)2]（x=0.1，0.3）荧光性质的研究表明，在其荧光光谱中存在着Gd3+和Tb3+的能量传递过程，荧光发射光谱表现出Tb3+离子的特征发射，是一种潜在的绿色荧光材料更多还原

【Abstract】 Lanthanide-containing compounds have been extensively studied because they mayserve as optical, electronic, and magnetic materials. As a traditional material, mostsilicates have high thermal and hydrothermal stabilities. Many studies have focusedon the synthesis of microporous silicates of transition metals, main group elements,lanthanides, and uranium because of their versatile structural chemistry as well asinteresting physical and chemical properties. Among them, lanthanide silicates, whichcontain stoichiometric amounts of framework Ln3+ions, have high thermal stabilityand tunable optical properties, making them potential candidates as fast ionconductors and optical materials. Most of these compounds were synthesized undermild hydrothermal conditions in Teflon-lined stainless steel autoclaves in thetemperature range of100~240°C. Herein, we mainly focus on the preparation andcharacteristics of the lanthanide silicates/germanates with photoluminescenceproperties and novel structures under high-temperature and high-pressure conditions.The experiments were carried out at the range from0.5to5GPa and300to700°C inthe Quickpress3.0piston-cylinder and LECO Tem-Pres high pressure hightemperature instrument. The structures and photoluminescence properties of theseas-prepared compounds were also investigated.(1) A new europium silicates, Na15Eu3Si12O36was successfully synthesized under high temperature and high pressure conditions, and structurally characterizedby single-crystal and powder X-ray diffraction (XRD). The single-crystal XRDanalysis of Na15Eu3Si12O36reveals that its structure is based on [Si6O18]n12n cyclosilicate anions that are built from six SiO4tetrahedra sharing two of their four Ocorners with each other. Such [Si6O18]n12n cyclosilicate anions are linked via EuO6octahedra to form a three-dimensional (3D) framework containing6-membered ringchannels delimited by the SiO4tetrahedra and EuO6octahedra along the [010]direction. The Na+ions are located in the free void space to achieve the chargebalance.Single crystal X-ray analysis also reveals that the crystallographic positionsof Na(2) and Na(3) are shared with partially occupied Eu(2) and Eu(3) centers,respectively. This statistical disorder of Eu and Na centers have an importantinfluence on the photoluminescence properties of Na15Eu3Si12O36.(2) A new europium silicates, K2EuSi4O10F was successfully synthesized from aKF·2H2O–KOH flux under high temperature and high pressure conditions, andstructurally characterized by single-crystal and powder X-ray diffraction (XRD). Thesingle-crystal XRD analysis reveals that the structure of K2EuSi4O10F consists ofinfinite tubular chains of corner-sharing SiO4tetrahedra, which are further linkedtogether via corner sharing O atoms by infinite chains of EuO4F2octahedra forming a3-D framework that contains8-ring and6-ring channels along the [010] direction.Every EuO4F2octahedron has four equatorial O atoms that are shared by threeneighboring tubular silicate chains and two axial F atoms. These axial F atoms act ascommon vertices to other octahedra forming a one-dimensional chain of EuO4F2octahedra along the [010] direction. The photoluminescence study is consistent withthe crystallography result and show that K2EuSi4O10F exhibit strong red emission.(3) A new europium silicate, Na3EuSi6O15·1.47H2O, has been synthesized usinga high temperature and high pressure synthetic method. The structure ofNa3EuSi6O15·1.47H2O is based on corrugated silicate single layers with thecomposition [Si2O5] in the ab plane containing4,5,6, and8rings, which are linkedvia EuO7polyhedra to form a three-dimensional (3D) framework of Na3EuSi6O15·1.47H2O. It contains4,8-ring channels along the [100] direction and5,6ring along the [001] direction. The Na+ions are located in the free void space tobalance the charge. The photoluminescence studies are consistent with thecrystallographic results and show that Na3EuSi6O15·1.47H2O is a potential redphosphor.(4) A family of2D-layered lanthanide germanates K3[Gd1-xTbxGe3O8(OH)2](x=0,0.3,0.1, and1), have been synthesized by a high temperature, high pressurehydrothermal method and characterized by single-crystal X-ray diffraction,photoluminescence, IR spectra, and Energy-dispersive spectroscopy (EDS). TheX-ray powder diffraction patterns of these compounds reveal that they areisostructural. The single-crystal X-ray diffraction analysis of K3[GdGe3O8(OH)2]reveals that it is2D-layered [LnGe3O8(OH)2]n3n anionic framework which is built upfrom GeO4H/GeO4tetrahedra and GdO6octahedra by sharing vertex O atoms. K+ionslocate in the free void space to achieve the charge balance of the framework. Samplecontaining only Tb3+emit mainly from one transition,5D4→7F5(552nm). Mixedlanthanide samples, K3[Gd1-xTbxGe3O8(OH)2](x=0.3, and0.1), have also beenprepared and efficient Gd→Tb energy transfer has been observed.更多还原