摘 要

随着世界对能源的需求日益攀升，不可再生的化石能源日益枯竭，社会与政治动荡由此急剧升级。同时，由于化石燃料的燃烧导致的全球气候变化对环境的影响也越来越令人担忧。热电材料是一种能实现热能和电能直接相互转换的功能材料。具有类金刚石结构的新型热电材料CuInTe₂化合物由于具有较高的赛贝克系数，相对较低的热导率，是一种很有发展前途的中温热电材料。

本论文以CuInTe₂基化合物为研究对象，采用传统熔融退火法结合等离子活化烧结技术（PAS）制备样品，探索了烧结温度对材料热电性能的影响，研究了SnTe、GeTe第二相复合对材料的微结构、相组成和电热输运性能的影响规律。研究结果表明：

采用传统熔融退火结合等离子活化烧结的方法可成功制备单相的CuInTe₂化合物。其最佳烧结温度为773 K。所得CuInTe₂化合物为p型热电材料，其最大zT值在825 K可达0.79。

引入SnTe第二相进行复合，在增加材料空穴浓度的同时，第二相界面的引入降低了材料的载流子迁移率。虽然低温时材料的电导率得到了一定提高，热导率也随SnTe含量增加而减小。但本征激发后，由于载流子迁移率的降低，材料的电导率低于本征CuInTe₂化合物，且相界面对高频声子散射作用有限，其热导率无明显降低，最终在825 K，SnTe复合x=0.01的样品zT值为0.77。

引入GeTe第二相进行复合，结果与SnTe相类似。随着GeTe含量的增加，低温时材料的电导率随之先升高后降低，其Seebeck系数先降低后升高，功率因子先升高后降低。热导率也随之有明显降低；但高温时材料的电导率比本征CuInTe₂低，Seebeck系数略有降低，功率因子随GeTe含量的增加而降低，热导率无明显的降低。最终导致高温下材料的zT值随GeTe含量增加而降低。在825 K，GeTe复合x=0.01的样品zT值为0.80。

关键词：CuInTe₂化合物；SnTe复合；GeTe复合；热电性能

Abstract

As the world's demand for energy continues to rise, non-renewable fossil fuels are increasingly depleted and social and political unrest is dramatically escalating. At the same time, the environmental impact of global climate change due to the burning of fossil fuels has become more and more worrying. Thermoelectric material is a kind of functional material which can realize the direct conversion of heat energy and electric energy. The new thermoelectric material CuInTe₂ with diamond-like structure is a promising medium-temperature thermoelectric material because of its high Seebeck coefficient and relatively low thermal conductivity.

In this paper, CuInTe₂-based compounds were prepared by conventional melting-annealing method combined with plasma activated sintering (PAS). The effects of sintering temperature on the thermoelectric properties were investigated. And we studied the influence of the second phase of SnTe,GeTe on its phase composition, microstructure, electrical transmission and thermal transfer performance. The results indicated:

Single phase CuInTe₂ compounds can be successfully prepared by conventional melting- annealing combined with plasma activated sintering. The optimum sintering temperature was 773 K. The resulting CuInTe₂ compound was a p-type thermoelectric material. The maximum zT value in the 825 K was 0.79.

The introduction of SnTe for recombination increased the vacancy concentration of the material, but the introduction of the second phase interfaces reduced the carriers mobility. At low temperature, the electrical conductivity of the material was improved, and the thermal conductivity decreased with the increase of SnTe content. However, after the intrinsic excitation, the conductivity of the material was lower than that of the intrinsic CuInTe₂ compound due to the decrease of carrier mobility. And the effect of phase interfaces on the high frequency phonon scattering was limited, so the thermal conductivity did not decrease obviously. At 825 K, The zT value of the SnTe composite (x = 0.01) was 0.77.

The results of the introduction of GeTe for recombination were similar to that of SnTe. With the increase of GeTe content, both of the conductivity and the power factor of the material first increased and then decreased, and the Seebeck coefficient first decreased and then increased. At high temperature, the conductivity of the material was lower than that of the intrinsic CuInTe₂, and the Seebeck coefficient was slightly lower.The power factor decreased with the increase of GeTe content, and the thermal conductivity had no obvious decrease, which lead to the decrease of zT value with the increase of GeTe content at high temperature. At 825 K, the zT value of the GeTe composite (x = 0.01) was 0.80.

Key Words：CuInTe₂ compound; SnTe; GeTe; thermoelectric performance

目 录

第1章 绪论 1

1.1 热电效应的基本原理 1

1.1.1 Seebeck效应 1

1.1.2 Peltier效应 2

1.1.3 Thomson效应 3

1.2 影响材料热电性能的物理参数 4

1.2.1 Seebeck系数 4

1.2.2 电导率 5

1.2.3 热导率 5

1.3 热电材料的研究进展 6

1.3.1 方钴矿（Skutterudite）化合物 6

1.3.2 Half-Heusler化合物 7

1.3.3 Clathrate化合物 8

1.4 CuInTe₂基热电材料的研究进展 9

1.4.1 CuInTe₂材料的基本性质 9

1.4.2 CuInTe₂材料的研究进展 11

1.5 本论文选题目的和主要研究内容 12

第2章 研究方法与实验设备 14

2.1 材料制备设备 14

2.1.1 熔融退火法及其设备 14

2.1.2 等离子活化烧结及其设备 15

2.1.3 切割设备 15

2.2 材料结构表征设备 16

2.2.1 X射线衍射分析 16

2.2.2 材料的微观形貌表征 16

2.3 材料热电性能测试设备 16

2.3.1 Seebeck系数及电导率测试 16

2.3.2 Hall系数测试 17

2.3.3 材料的密度测量 18

2.3.4 热导率测试 18

第3章 烧结温度对材料热电性能的影响规律 20

3.1 引言 20

3.2 实验 20

3.3 实验结果及讨论 20

3.3.1 CuInTe₂的物相分析 20

3.3.2 CuInTe₂的基本物理参数 21

3.3.3 CuInTe₂的电输运性能 21

3.3.4 CuInTe₂的热输运性能 22

3.3.5 CuInTe₂的热电优值 25

3.4 本章小结 25

第4章 SnTe第二相复合对材料热电性能的影响 26

4.1 引言 26

4.2 实验 26

4.3 实验结果及分析 26

4.3.1 (CuInTe₂)_1-x(SnTe)_x化合物的相组成与微结构 26

4.3.2 (CuInTe₂)_1-x(SnTe)_x化合物的电输运性能 29

4.3.3 (CuInTe₂)_1-x(SnTe)_x化合物的热输运性能 30

4.3.4 (CuInTe₂)_1-x(SnTe)_x化合物的热电优值 32

4.4 本章小结 32

第5章 GeTe第二相复合对材料热电性能的影响 34

5.1 引言 34