Ti掺杂Te置换型CoSb_3的高压合成及电热输运性能研究

Co Sb3基方钴矿化合物具有优良的电输运性能,是一种极具潜力的新型中温热电材料,但其相对较高的热导率限制了它在热电方面的应用和发展。针对方钴矿化合物特殊的笼状晶体结构,本文采用高温高压合成方法制备了具有Skutterudite结构的Ti掺杂Te置换型方钴矿热电材料,利用X射线衍射以及扫描电镜对该类样品的晶体结构和断面微观形貌进行了分析。分析结果表明高温高压合成方法可以快速的制备出单相Skutterudite结构、晶界明显且晶粒较小(1~3μm)的方钴矿热电材料。研究了室温情况下合成压力与Ti原子的掺杂浓度对所得样品热学与电学输运性能的影响规律。所得结果表明:通过高压快速制得的Ti掺杂Te置换型样品呈n型传导,与预期相同,Ti掺杂Te置换型Co Sb3样品的Seebeck系数随合成压力的升高而升高;不同掺杂浓度的样品获得最大功率因子(~10μWcm-1K-2)的合成压力均在1.5GPa左右;样品的热导率和晶格热导率整体上随着合成压力升高而降低。

Study on Electrical Transport Properties of TixCoSb11.5Te0.5 Prepared by HPHT

CoSb3-based skutterudites possess excellent electrical transport properties, which are desirable for potential mid-temperature thermoelectric materials. However, the large thermal conductivity of unfilled CoSb3-based skutterudites restricts their application and development. Therefore,based on the special cubic structure of CoSb3 compound,Skutter-udite compounds TixCoSb11.5Te0.5 have been prepared by high pressure and high temperature (HPHT) method. Seebeck coefficients measurements indicated that TixCoSb11.5Te0.5 were n-type semiconductor. The crystal structure and microstruc-ture have been analysed by X-ray diffraction and scanning electron microscopy (SEM). X-ray diffraction and SEM showed that single-phase CoSb3 with fine grain size (1~3μm) and abundant grain boundaries could be synthesized un-der high pressure. The Seebeck coefficients and the electrical resistivity of TixCoSb11.5Te0.5 all increased with increasing pressure at room temperature, and the power factor of the sample synthesized at 1.5GPa has a maximum value (10μWcm-1K2).