夹层对MxIn4Se3-δ化合物热电性能的影响与机理研究

项目名称： 夹层对MxIn4Se3-δ化合物热电性能的影响与机理研究

项目编号： No.51202005

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 无机非金属材料学科

项目作者： 李海金

作者单位： 安徽工业大学

项目金额： 25万元

中文摘要： In4Se3-δ具有内禀准二维结构，室温下热电势S较高(～-500μVK-1)，热导率κ较低(～1Wm-1K-1), 700K时ZT值约为1，具有广阔的应用前景。但其载流子浓度n较低(～1017cm-3)，电阻率ρ较大(～10-3Ωcm)，使得功率因子PF较低。如何有效降低ρ并维持较大S成为提高ZT值的关键。对此问题，我们将Bi、Pb、Gd、Nd等元素引入范德瓦尔斯层，形成夹层化合物MxIn4Se3-δ，M的电荷转移可增加n，降低ρ，提高PF；而M的"晃动"可增强声子散射使κ减小，从而提高ZT值。此外，利用夹层与δ的调节组合来提高ZT值。本课题采用球磨结合热压技术制备MxIn4Se3-δ多晶材料。通过调节M、x、δ，研究其对MxIn4Se3-δ热电性能的影响规律和机理，探讨其对In4Se3-δ的电荷密度波和派尔斯畸变的影响规律及机制，为提高In4Se3-δ的热电性能奠定可靠的实验基础。

中文关键词： 热电性能；电阻率；热电势；热导率；

英文摘要： The In4Se3 semiconductor crystal forms a layered structure of (In3)5+ clusters covalently bonded to Se ions in the b-c planes held together by van der waals interactions along the a axis. The In4Se3 compounds show high negative thermopower (Seebeck coefficient, S) (～-500μVK-1) and very low thermal conductivity (κ) (～1Wm-1K-1) at room-temperature owing to the inherent quasi-two-dimensional structure and lattice distortion (charge density wave and Peierls distortion). The thermoelectric properties of polycrystalline In4Se3 samples have been investigated by several groups and reported to have a maximum ZT (=σS2/κ) about 1 at about 700K. It is significantly that In4Se3 compounds are promising applications in "environmentally friendly" power generation. However, the electrical resistivities (ρ) of In4Se3 are too high (～10-3Ωcm) for the materials to be good thermoelectric materials with very high ZT due to the low carrier concentration (～1017cm-3), resulting in the low power factor (PF). So there is much room for improvement in ZT for In4Se3 if a key strategy could be found to significantly reduce the electrical resistivity without too much affecting the thermopower. According to the phonon-glass and electron-crystal (PGEC) concept and the experimental results of the thermoelectric properties for intercalation compoun

英文关键词： thermoelectric properties；electrical resistivity；thermopower；thermal conductivity；