论文总字数：20492字

摘 要

TiS₂是一种环境友好型中低温热电材料的候选体系。但过高的晶格热导率限制了TiS₂基材料的热电优值ZT。TiS₂层状结构具有显著的各向异性，相比于c方向，a-b方向具有极高电导率而热导率相差不大，意味着提高晶粒在多晶体中的取向程度将大大提高a-b面统计取向方向上的热电性能。前期研究表明，液相辅助剪切粉碎法处理TiS₂粉体，可在保证结晶度同时有效减小颗粒尺寸、提高烧结体的织构度，产生有利于提高热电性能的协同作用：(1)有效提高a-b面内方向载流子迁移率，(2)通过增强晶界声子散射降低晶格热导率。这说明，通过该粉体预处理工艺，可在合理低载流子浓度条件下维持高电导率，因此可有效提升塞贝克系数，获得功率因子和热电优值的提升。

本实验预测了液相剪切剥离对Ti_{1 x}S₂热电性能的影响，同时结合他人对Ti_{1 x}S₂的研究，估算了最佳x值与载流子浓度

关键词：热电材料 TiS₂ 液相剥离 ZT值 织构

Effect of Liquid-Assisted Shear Pulverization on the Microstructure and Thermoelectric Properties of Titanium Sulfide Ceramics with Different Stoichiometry

ABSTRACT

TiS₂ is a candidate system of environmentally friendly medium and low temperature thermoelectric materials. However, the high lattice thermal conductivity limits the thermoelectric value ZT of TiS₂ based materials. The layered structure of TiS₂ has significant anisotropy. Compared with the c direction, the a-b direction has very high conductivity and the thermal conductivity is not much different, which means that improving the orientation degree of grains in polycrystalline bulks will greatly improve the thermal and electrical properties in the statistical orientation direction of a-b plane. The previous research shows that the Liquid phase exfoliation can effectively reduce the particle size and improve the texture of the sintering body while ensuring the crystallinity, resulting in the synergistic effect of improving the thermoelectric properties: (1) effectively improving the carrier mobility in the a-b direction, (2) reducing the lattice thermal conductivity by enhancing the phonon scattering at the grain boundary. At the same time, it shows that the high conductivity can be maintained under the condition of reasonable low carrier concentration through the powder pretreatment process, which can effectively improve the Seebeck coefficient, then obtain the enhancement of power factor and thermoelectric optimal value.

In this experiment, the influence of liquid shear stripping on the thermoelectric properties of Ti_{1 x}S₂ was predicted. The best x value and carrier concentration were estimated based on the study of Ti_{1 x}S₂ by others.

Key words: thermoelectricmaterial;TiS₂;Liquid phase exfoliation;ZT value;texture

目录

摘 要 II

ABSTRACT II

第1章 绪论 2

1.1课题研究背景 2

1.2热电材料概述 2

1.2.1塞贝克效应 2

1.2.2珀尔帖效应 2

1.2.3汤姆孙效应 2

1.2.4热电性能评估参数 2

1.3 TiS₂基热电材料的特点与研究进展 2

1.3.1近化学计量比TiS₂ 2

1.3.2化学计量Ti_{1 x}S₂ 2

1.3.3TiS₂基热电材料的研究进展 2

1.4提高TiS₂热电性能的方法 2

1.4.1高结晶度 2

1.4.2纳米化 2

1.4.3织构度 2

第2章 实验 2

2.1实验原料 2

2.2实验步骤 2

2.3实验流程图 2

2.4实验设备 2

第3章 液相辅助剪切对显微结构与性能的影响 2

3.1非定量化学计量TiS₂结论分析 2

3.1.1XRD分析 2

3.1.2粒度分析与形貌分析 2

3.1.3电导率 2

3.1.4热导率 2

3.1.5塞贝克系数 2

3.1.6功率因子 2

3.1.7ZT值 2

3.2非化学计量比TiS₂的热电性能 2

3.2.1电导率σ 2

3.2.2塞贝克系数S 2

3.2.3功率因数PF 2

第4章 预测结论与展望 2

参考文献 2

致谢 2

第1章 绪论

1.1课题研究背景

材料、信息、能源是新世纪人类发展的三大支柱，从改革发展以来传统能源已然不能满足人类社会高速发展的需求。同时，传统能源（煤、石油、天然气等）在自身消耗的同时不仅会产生大量温室气体，同时热利用率也不高，大量热量白白散失，如果将这部分热量用于发电，将极大缓解能源紧张的局面。这种情况下，对于节约能源而开发的新型材料有助于缓解人类社会对能源需求。

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