Cu2-xS和Cu2-xSe类液态材料的可控制备与热电性能研究进展  

Progress in Controllable Preparation and Thermoelectric Properties of Cu2-xS and Cu2-xSe Liquid-like Materials

作　　者：林锦豪 谢华清[1] 吴子华[1] 李奕怀[1] 王元元[1] LIN Jinhao;XIE Huaqing;WU Zihua;LI Yihuai;WANG Yuanyuan(School of Environmental and Materials Engineering,Shanghai Polytechnic University,Shanghai 201209,China)

机构地区：[1]上海第二工业大学环境与材料工程学院,上海201209

出　　处：《材料导报》2020年第7期71-81,共11页Materials Reports

基　　金：国家自然科学基金(51590902,51676117);上海第二工业大学研究生项目基金(EGD18YJ0027)。

摘　　要：在高速发展的21世纪,随着化石能源的日渐枯竭,人们开始把目光投放到新能源的开发。其中,热电技术的研究和发展受到广泛关注。基于热电材料的热电发电技术能够将热能直接转换为电能,相关器件和系统具有体积小、质量轻、坚固、无传动部件、无噪声运行、安全可靠、易于控制等优点。热电优值(ZT)是评价热电性能的参数,ZT=S 2σT/κ,其中S是泽贝克系数,σ是电导率,T是绝对温度,κ是热导率。当ZT值达到1以上时,说明热电材料达到商业应用的基本要求。近年来,多类性能出色的热电材料被发现并得到深入研究。“声子液体-电子晶体”(PLEC)类材料概念被提出后,就凭借其超低热导率特征而受到了广泛关注。作为典型的PLEC类材料,Cu-S系材料备受关注并得到较为深入的研究,其中以Cu2S和Cu2Se为主,它们都是本征p型半导体材料,具有低的热导率。在结构上,两种半导体随着温度的升高,都会发生结构相变,其中,723 K的α-Cu2S和400 K的β-Cu2Se为立方相,具有很低的热导率。在α-Cu2S中,Cu离子在S原子组成的刚性亚点阵中具有类液体的迁移行为,成为液态亚点阵。液态亚点阵对格波声子的横向传输具有很强的扰动,减少了热传导的横模数目,导致定容比热、声子平均速率和声子平均自由程的减小,使Cu 2S具有很低的热导率。在制备方法上,Cu2-xS和Cu2-xSe均可采用纳米材料常见的合成方法——水热法和前驱体法,这两种合成方法均具有操作简单、成本低、粒径小和可灵活调控的优点。掺杂、复合是改善Cu2-xS和Cu2-xSe性能的常见手段,通过这两种方法改善其电导率或者改变其结构能够得到更低的热导率,从而获得更好的热电性能。如通过在S位上掺杂Te形成Cu 2S 0.52 Te 0.48,此化合物为纳米级马赛克结构,在1000 K时,其ZT值达到2.1。在Se位上掺杂S形成Cu 2Se 0.8 S 0.2,不仅能降低声子的散射速度In the 21 st century of rapid development of science,with the gradual depletion of fossil energy,discovery and application of new energy resources have been attracting lots of attention.Thermoelectric technology has become a promising choice.Thermoelectric conversion techno-logy based on thermoelectric materials can convert thermal energy into electrical energy directly.The related devices and systems have the advantages of small size,light weight,strong,non-transmission components,noise-free operation,safety,reliability and easy to control.Thermoelectric dimensionless figure of merit ZT is a parameter to evaluate the thermoelectric performance.ZT=S 2σT/κ,where S is the Seebeck coefficient,σis the electrical conductivity,T is the absolute temperature,andκis the thermal conductivity.It would have remarkable thermoelectric properties and can be considered for commercial applications if the ZT value is above 1.In recent years,various excellent thermoelectrical materials have been developed and applied.Since the concept of“Phonon liquid electron crystals(PLEC)”was brought up,more and more studies have been devoted to this novel kind of materials due to their feature of super-low thermal conductivity.Cu-S like materials(Cu2S and Cu2Se),as typical PLEC materials which are intrinsic p type semiconductors with very low thermal conductivity,have been taken more researches.As to their structures,both of them can undergo phase transition with increasing temperature.For instance,Cu 2S would change toα-Cu2S in 723 K and Cu2Se would becomeβ-Cu 2Se in 400 K,both of which are cubic phase with lo-wer thermal conductivity.Especially,in the structure ofα-Cu2S,a“liquid sub-lattice”is that S atoms form a rigid sublattice where Cu ions possess liquid-like migration behavior.Liquid sub-lattice disturbs the transverse propagation of lattice phonons strongly,such behavior reduces the number of transverse modes of heat conduction,leads to the decrease of specific heat at constant volume,average phonon velocity and average f

关 键 词：热电材料 PLEC类材料 Cu2-xS Cu2-xSe 

分 类 号：TB34[一般工业技术—材料科学与工程]