Ruddlesd-Popper结构钛酸锶薄膜的横向热电效应及其与各向异性输运性质的关联研究

The researches about Transverse thermoelectric effect (TTE) always focus on the untraditional thermoelectric materials for a long time. What’s more, the sluggish development of theories and lacked improvement of performances have seriously restricted the development of related devices for potential applications. Based on the essential that TTE effect is an unconventional thermoelectric effect using the anisotropy of the Seebeck coefficient tensor, we proposed a new idea that a larger TTE effect will be obtained when the traditional thermoelectric materials with large Seebeck coefficient combined with anisotropic structures. In this research, the layered Srn+1(Ti1-xNbx)nO3n+1 epitaxial films with Ruddlesden-Popper deposited by PLD will be studied detailly. According to the anisotropic transport properties and TTE performances study through quantitative regulating the doping amount of Nb and structural anisotropy, the correlation between them will be built, and the quantitative relations between them will be clarified. Further more, the mechanism of TTE effect controlled by anisotropic transport properties will be revealed. This research is expected to be a theoretical derection for optimizing TTE performance and materials development.

横向热电效应（TTE）的研究基本围绕非传统热电材料展开，理论发展停滞不前，性能提高乏力，影响器件开发和应用。基于TTE效应是一种Seebeck系数张量元各向异性的特殊热电效应的本质，提出将传统热电材料与结构各向异性相结合可以获得较大TTE效应的新思路。本项目拟采用层状Ruddlesden–Popper结构的Srn+1(Ti1-xNbx)nO3n+1热电外延薄膜为研究对象,通过定量调节薄膜的Nb掺杂量和结构各向异性实现对各向异性输运性质和TTE效应的可控调节研究，建立掺杂量、结构各向异性、输运性质各向异性以及TTE性能之间的关联性，阐明它们之间的定量关系，揭示TTE性能受控调节机理，为TTE性能的优化改善和新材料的开发提供理论依据和新思路。

横向热电（TTE）电压效应在光、热探测器和能量转换器件方面有着广泛的应用前景。本项目针对目前横向热电电压效应很少涉及到传统热电材料以及很难在各向异性小的材料中产生等问题。以层状结构钛酸锶热电材料为研究对象，首先对层状钛酸锶块体材料的熔盐合成进行了研究，得到了制备纯相层状钛酸锶粉体的工艺及其生长机制，并以此粉体为原料，采用流延和热压工艺制备的具有多级声子散射中心的块体层状结构钛酸锶的热、电输运性质进行了系统的研究。在块体层状钛酸锶掺杂的研究基础之上，得到PLD薄膜生长的靶材，进而开展了PLD生长层状钛酸锶薄膜的研究，通过对制备的薄膜物相、微观结构、输运性质的表征分析，获得温度、氧压等薄膜沉积参数对其的影响规律以及层状结构钛酸锶薄膜的稳定台阶流外延生长机制。对系列层状结构钛酸锶薄膜TTE效应的测试，找出了不同外延取向角度、调制长度和调制周期等系列样品的TTE信号规律并建立了它们之间的定量关系，通过分析外延取向角度、调制长度和调制周期等参数对ΔS和非稳态热输运性质的影响规律，建立它们与TTE电压信号峰值和响应时间（包括上升沿时间和下降沿时间）之间的定量调节关系。通过信号拟合计算以及对薄膜的实际测试，证实了层状结构钛酸锶薄膜具有较大的各向异性Seebeck系数，这将为其它材料TTE效应的开发提供思路和依据。