玻璃态窄带隙碲基热电材料的制备与性能研究

The preparation of nanoscaled thermoelectric materials has showed a remarkable enhancement of thermoelectric properties by effectively suppressing the thermal conductivity. This implies that amorphous states with structural disordering would provide an alternative strategy for the development of novel thermoelectric materials with remarkable properties. This proposal will focus on the experimental studies the glass transition behaviors and the thermoelectric properties of narrow-band-gap Te-based alloys in order to exploit new routes in preparing glassy Te-based thermoelectric materials. Studies will start with component selection of alloys where the entropies of fusion of Te-based compounds and eutectic systems are emphasized to explore the glass transition. Glass transition thermodynamic and kinetic parameters are characterized to interpret the glass transition features and the glass forming ability of Te-based alloys. The kinetics involved in structural relaxation and crystallization of the glassy alloys is studied to clarify the thermal stability in terms of the phase transition routes. The dependence of the thermal conductivity on the relaxation and crystallization will be intensively investigated. The electrical conductivity will be modified by tailoring the concentration of components as well as the doping of other atoms. The studies will provide experimental and theoretical references for the understanding of the glass transition of narrow-band-gap Te-based alloys together with the exploitation of new glassy thermoelectrical materials.

研究表明材料的纳米化能够有效地降低热电材料的热导率进而提高其热电性能。这预示着具有无序结构特征的非晶态有可能为制备新型高性能的热电材料提供新的思路。本项目针对窄带隙碲基合金提出开展玻璃转变与玻璃态热电性能的实验研究，探索制备高性能玻璃态碲基热电材料的新途径。研究思路是：基于材料的熔化熵从合金的组分选择入手、通过构建碲化物共晶体系实现窄带隙碲基合金的玻璃化转变；并通过对电导率的调控来提高热电性能。为此，将从组成、热力学与动力学等方面分析窄带隙碲基合金的玻璃形成能力，建立玻璃形成基本规律；实验标定玻璃化转变与玻璃态的结构弛豫和晶化动力学特征，阐明相变路径并解释其热稳定性；探讨热导率随玻璃态弛豫与晶化的变化规律；从合金自身组分的调控与外来原子掺杂两个方面入手改善碲基合金的电导率。项目的开展将为理解窄带隙碲基合金的玻璃化转变、开发具有高热电性能与高热稳定性的玻璃态热电材料提供实验与理论依据。

本项目根据申请书中的研究规划对玻璃态窄带隙碲基热电材料的制备与性能开展了的系统研究。围绕窄带隙碲基半导体材料的非晶化，我们提出综合考虑热力学与动力学共同作用这一思路，成功设计了新型Ga2Te3-SnTe碲基非晶体系，并确定了其玻璃形成区间，分析了其玻璃转变特征。利用晶化动力学方程对其晶化机制、热稳定性及析出相进行了分析研究。对块体(Ga2Te3)34(SnTe)66玻璃的烧结工艺及其热电性能进行了进一步的优化改良，获得了具有极低热导率和较高Seebeck系数的潜在应用价值的高性能玻璃态热电材料。拓宽了碲基非晶半导体的研究范围，为热电材料的发展提供了更多的选择。相关结果发表SCI收录论文23篇，其中包含J. Applied. Phys.、J. Non-Cryst. Solids、J. Chem. Phys.等期刊。国内外学术会议邀请报告12次。2013和2015年作为中方组织者与意大利比萨大学联合举办学术研讨会2次。