| Microporous materials with regular microporous structures have been widely usedin many industrial processes such as catalysis, adsorption and separation, as well as innew applications of photoluminescence, electronics, magnetism, sensors, medicine,and etc. The lanthanide containing miroporous frameworks with novel structures andexcellent properties which have potential applications as catalysts, optic devices andfast-ion conductors have been attracted a considerable attention in the recent decades.In this thesis, the study of the mild hydrothermal synthesis, structuralcharacterizations and interesting properties of a series of lanthanide silicates,gemanates and phosphites will be present.The main results in this thesis are summarized as follows:1. A family of microporous lanthanide silicates, K8Ln3Si12O32NO3·H2O (denotedLnSiO-CJ3, Ln=Eu, Tb, Gd, Sm), were successfully synthesized under mildhydrothermal conditions at230oC. The X-ray powder diffraction patterns of thesecompounds show that they are isostructural. The structure of EuSiO-CJ3wasdetermined by single-crystal X-ray diffraction analysis. The structure is based on[Si3O8]n4n-layers with6-,8-,12-rings that are connected by EuO6octahedra to form a3-D framework with8-ring channels along the [001] direction. Charge neutrality isachieved by the K+and NO3-ions located in the channels. It is a kind of KNO3salt-inclusion compound, which is rarely existed in lanthanide silicate. The frameworkof EuSiO-CJ3shows high thermal stability, which can be stable up to800oC. Thepeaks in the emission spectra of LnSiO-CJ3(Ln=Eu, Tb) belong to the characteristictransitions of Ln3+(Ln=Eu, Tb) respectively. The lifetime measurements ofLnSiO-CJ3(Ln=Eu, Tb) suggest the presence of three Ln3+(Ln=Eu, Tb)environments, which are consistent with the crystallographic results. Ion-exchangecapacity of EuSiO-CJ3was investigated by the exchange of NO3-ions with halideions (F-, Cl-, Br-). The ion-exchanged EuSiO-CJ3samples also show excellentphotoluminescent properties. 2. Na8CeSi6O18and Na8Ce0.73Ti0.27Si6O18(denoted CeSiO-CJ11A andCeTiSiO-CJ11B, respectively) were the first successful examples of Ce4+andCe4+/Ti4+mixed cyclosilicates synthesized under mild hydrothermal conditions at230oC. Their isostructure is confirmed by the X-ray powder diffraction analysis. Thesingle-crystal X-ray diffraction analysis of CeSiO-CJ11A reveals that its structure iscomprised of [Si6O18]n12n-cyclosilicate anions that are linked via CeO6octahedra,giving rise to a3D framework which contains6-ring channels delimited by the SiO4tetrahedra and CeO6octahedra along the [101] direction. Charge neutrality is achievedby Na+ions located in the channels. Interestingly, the surface photovoltage (SPV) andtransient photovoltage (TPV) studies of CeSiTiO-CJ11B show that it exhibits thecharacter like n-type semiconductor and a slow recombination process.3. A family of novel2D layered lanthanide germanates K3[TbxEu1-xGe3O8(OH)2](x=1,0.88,0.67,0; denoted TbGeO-JU-87, Tb0.88Eu0.12GeO-JU-87,Tb0.67Eu0.33GeO-JU-87, and EuGeO-JU-87) were synthesized under mildhydrothermal conditions in a concentrated gel system. They are isostructuralconfirmed by the powder X-ray diffraction analysis. The single-crystal X-raydiffraction analysis of EuGeO-JU-87reveals that it is a2D layered[EuGe3O8(OH)2]n3n-anionic framework, which is built up from GeO4H/GeO4tetrahedra and EuO6octahedra by sharing vertex O atoms. Charge neutrality isachieved by K+ions located in the free void space. Interestingly, photoluminescencestudies show that Tb0.88Eu0.12GeO-JU-87and Tb0.67Eu0.33GeO-JU-87exhibit a highTb3+to Eu3+energy transfer efficiency and TbxEu1-xGeO-JU-87system displaystunable photoluminescent properties according to the calculation of the CIE colourdiagram.4. A family of lanthanide phosphites GdxTb2-x(HPO3)3(H2O)2(0≤x≤2) weresynthesized by using the microwave irradiation synthesis method. They areisostructural confirmed by the powder X-ray diffraction analysis. The single-crystalX-ray diffraction analysis of Gd2(HPO3)3(H2O)2reveals that it is a3-D framework,which is built up from GdO7/GdO8polyhedra and HPO3pseudo tetrahedra by sharingvertex O atoms. The photoluminescent study of Gd2(HPO3)3(H2O)2and Tb2(HPO3)3(H2O)2shows the typical Gd3+and Tb3+photoluminescence, respectively. Thephotoluminescence study of Gd/Tb mixed samples indicates the occurence ofGd3+-Tb3+energy transfer. The Tb3+doped gadolinium phosphites display the5D4→7F3-6transitions assigned to Tb3+, which could be used as green color phosphors.The magnetic measurement of Gd2(HPO3)3(H2O)2reveals that it exhibits very weak antiferromagnetic behavior and its experimental reciprocal susceptibility can be fittedby Curie–Weiss law at4～300K.
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