【作者】 彭卿；

【导师】 李亚栋；

【作者基本信息】 清华大学 ， 无机化学， 2003， 博士

【摘要】 硒碲化合物半导体纳米材料因其优异的光、电、磁性能，具有广阔的应用前景。如何在合成过程中实现对它们的晶体结构、维度、形貌、表面结构和能带结构的调控，将为实现材料性能的人工剪裁，深入系统研究材料结构与性能的关系具有重要的意义。本论文在硒碲化合物半导体纳米材料的化学合成新途径及其调控合成方法等方面做了很多有益的探索性研究。在合成新途径的探索方面，从发现了水热元素直接反应法，发展到亚硒酸盐水热还原法，提出了化学调控合成的新概念，为液相中金属硒碲化合物的合成提供了可能的动力学调控手段和方法。在实验上，选用络合剂络合金属离子，通过筛选合适的络合剂、调节反应温度、反应物比例等条件，成功地实现了对CdSe晶体结构、维度、尺寸和形貌等的选择性调控合成，并详细讨论了调控机制，为半导体纳米材料的调控合成开辟了新的途径。在化学调控合成思想的指导下，运用已取得的调控合成的成功经验，利用MnSeO3沉淀缓释放出Mn2+源和硒源，在调节反应温度的基础上，于同一反应体系成功地合成了MnSe2和MnSe的立方体和球形微米晶，实现了产物组成和维度的调控，并对它们的磁行为进行了研究。用亚碲酸盐代替亚硒酸盐，上述方法被成功应用到金属碲化物的动力学调控合成中，通过共还原反应机理，利用新生的元素Co、Ni与活性碲，于水溶液中合成了CoTe和NiTe的一维纳米线。亚硒（碲）酸盐还原水热法为金属硒碲化合物的调控合成提供了一个强有力的手段，进一步发展和完善了化学调控合成的方法，丰富了调控合成思想。以ZnO22-阴离子提供锌源，利用它在强碱性溶液中缓慢释放出Zn2+，并与Se2-之间的电荷排斥作用，成功地调节了反应动力学，获得了尺寸和分散性都非常均匀的微米级ZnSe空心球，并实现了空心球内部粒子尺寸的调控，提出了新颖的气液界面团聚机理。进行了ZnSe微球自组装的尝试，并初步获得了微球排列紧密的二维ZnSe片和三维紧密堆积结构，展现了很好的自组装前景。最后通过置换反应法对ZnSe微球的表面进行了修饰，成功制备了多种核壳结构，为材料性能的“剪裁”打下了良好的基础。更多还原

【Abstract】 Nanoscale semiconductor metal selenides and tellurides have attracted substantial research interests during the past years. It has been demonstrated that the optical, electrical and magnetic properties of them could be tailored in a controllable way by altering their structure, morphology, dimension, or composition. In this dissertation, valuable researches have been carried out to the exploration of new synthetic methods in solution phase, and controlled syntheses of metal selenides and tellurides. The main point can be summarized as follows:A low-temperature elemental-direct-reaction route to nanocrystalline CdSe and ZnSe, and further more, by using the newly produced Se with high reactivity as reactant, a controllable synthetic route named "selenite reduction hydrothermal method" have been developed. Various chemical strategies have been introduced to the system to affect the dynamics of reaction, and thus, to adjust the nucleation and growth process. By using appropriate complexing agents as controlling reagents and adjusting the reaction temperature, both morphologies (nanorods and fractals) and structural phases (zinc blende or wurtzite structures) of CdSe nanocrystals can be easily controlled.A precipitate slow-release controlled method was designed in the synthesis of manganese selenides. High quality cube-like MnSe2 and sphere-like (-MnSe micro-crystals have been obtained in aqueous solution at low temperatures (100(C~180(C). By using tellurite as reactant, uniform CoTe and NiTe nanocluster wires were successfully synthesized through a co-reduction process. Through the competition of ionization equilibrium of ZnO22- and precipitation reaction, the nucleation and growth process of ZnSe have been adjusted, and monodispersed ZnSe semiconductor hollow microspheres are obtained. These microspheres were found to form through aggregation of small ZnSe nanocrystals sizes of which could be finely tuned by temperature control. A novel gas-liquid interface aggregation mechanism was proposed and this idea might be generalized in other systems. Optical characterization showed interesting photonic properties and attempts to assemble them into 2D and 3D arrays were carried out. The core/shell structures of ZnSe/MSe (M=Ag, Cu, Pb, Cd) microspheres were also synthesized by a simple substitution reaction.更多还原