分别采用不同的熔炼、退火工艺,结合放电等离子烧结方法制备了块状多晶 In4Se3热电材料。研究了熔炼时间和退火时间对材料物相、成分、显微结构及热电性能的影响。熔炼后铸锭中存在In及InSe杂相, Se缺失量随熔炼时间的延长而增加,使得样品载流子浓度增大,电导率有所提高,熔炼48 h样品ZT值相对较高。在确定熔炼工艺的基础上,进行不同时间的退火处理后, InSe相消失,显微结构中分布有较大尺寸的台阶状结构,这种台阶状结构有利于降低热导率,而对电导率无明显影响。实验结果表明：一定程度延长熔炼时间、退火时间对提高样品的热电性能有积极作用,其中熔炼48 h再退火96 h后的样品ZT值最高,在702 K达到0.83,比文献值提高约32%。
Polycrystalline In4Se3 thermoelectric materials were synthesized in the processing sequence of vacuum melting, annealing and spark plasma sintering. The effect(s) of melting and annealing duration periods on the phase, composition, microstructure, and thermoelectric properties of polycrystalline In4Se3 were investigated. After the melting process, both In and InSe phase were detected in the ingots. With increasing melting duration time, an in-crease in Se deficiency was observed, leading to an increase of carrier concentration, which contributed to the ob-served improvement of electrical conductivity. The specimen melted for 48 h showed relatively higher ZT. Thus on the basis of 48 h melting process, the ingots were then annealed for different periods of time, which eliminated the presence of InSe phase. After annealing, scattered large step-like structures were observed in the matrix, which fa-vored the reduction of thermal conductivity but had no significant influence on the electrical conductivity. TheZT was significantly enhanced to 0.83 at 702 K by extending melting and annealing duration time to 48 h and 96 h, re-spectively, which is 32% higher than that reported in literature. It was concluded that both the extension of melting and annealing duration periods could improve the thermoelectric performance of polycrystalline In4Se3.
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