SiGe-SrTiO3复合材料的制备及其热电机理研究

Thermoelectric material, as a functional material that can directly convert heat and electrical energy reversely, has a wide range of applications in the field of power generation, refrigeration and sensing, etc.. Although SiGe alloys have long been applied to the spacecraft's generators because they have high chemical, mechanical stability and high thermoelectric performance at high temperatures, its large-scale application is limited by the high price of Ge. At present, few researches on the alloys and oxides thermoelectric composites have been reported. Therefore, this project, by placement of cheap and environmental friendly SrTiO3 in SiGe base material to explore a new type of SiGe-SrTiO3 thermoelectric bulk composite. By precisely controlling of the microstructure and electronic structure of SiGe and SrTiO3 ceramic to unleash the interface effect of them, and then allow the electrical and thermal transport properties of the two materials play the greatest role mutually, finally obtain high-performance thermoelectric bulk composite. This study will be an important theoretical and practical significance for the research and application of alloy and oxide thermoelectric composite materials.

热电材料是能够将热能和电能直接相互转换的功能材料，在发电、制冷和传感等领域具有广泛的应用前景。SiGe合金具有很高的化学、机械稳定性能和在高温时表现出较高的热电性能，很早就被应用于宇宙飞船的发电机上。然而，由于Ge的价格昂贵而使其大规模的应用受到阻碍。目前合金和氧化物的复合热电材料的报道较少，因此本课题选择廉价和环境友好的SrTiO3与SiGe基体复合，探索一种新型的SiGe-SrTiO3复合热电块材。拟通过微观结构和电子结构的调控，发挥两种材料的界面效应，使两种材料复合后的热电输运性质扬长避短，得到高性能的复合热电块材。该研究对合金和氧化物复合热电材料的研究和应用具有重要的理论和实际指导意义。

热电材料是能够将热能和电能直接相互转换的功能材料，在发电、制冷和传感等领域具有广泛的应用前景。SiGe合金具有很高的化学、机械稳定性能和优异的高温热电性能，很早就被应用于宇宙飞船的发电机上。然而，由于Ge的价格昂贵而使其大规模的应用受到阻碍。目前合金和氧化物的复合热电材料的报道较少，因此本课题选择廉价和环境友好的SrTiO3与SiGe，探索了一种新型的SiGe-SrTiO3复合热电块材。首先，研究了SrTiO3的掺杂元素、微观结构和热-电输运性能之间的关联关系，确定了掺杂比例与浓度对电子结构、价态、第二相、孔隙率和热电输运性质的影响规律，从而优化工艺参数-微观结构-性能参数，进而使SrTiO3在1000K的ZT值提高至0.4以上，并揭示了其热电机理；其次，通过SiGe和SrTiO3的比例和微观结构调控，发挥两种材料的界面效应，使两种材料复合后的热电输运性能扬长避短，得到高性能SiGe-SrTiO3复合热电块材，其中SiGe为基体的复合材料在1000K时ZT为0.91，SrTiO3为基体的复合材料为0.42。该研究对合金和氧化物复合热电材料的研究和应用具有重要的理论和实际指导意义。