Optimization Of Thermoelectric And Mechanical Properties Of Doped Skutterudites

Since the third industrial revolution, the usage of energy becomes widespread inmany fields. At the same time, due to the exploitation of fossil fuels, it produces largequantities of polluted gases, such as carbon monoxide, carbon dioxide and sulfurdioxide, and causes many serious environmental problems. Therefore, the researchersbegin to pay much attention to how to obtain a new type of clean, renewable energyand energy conversion technology. As a kind of materials with environmentalfriendliness, thermoelectric materials have great potential applications in the fields ofwaste heat power recycling and thermoelectric refrigeration.In this paper, optimization of thermoelectric properties of Ni-Te-Se codopedsubstituted skutterudites is the focus of the research. Ni-Te-Se codoped skutteruditecompounds are prepared by solid-state reaction and SPS technology, and theinfluences of codoping on microstructure and thermoelectric properties areinvestigated, which aims to improve the merit of ZT. In addition, the nano materials ofTe-Se codoped skutterudites with nano-TiN dispersed in are prepared and theinfluences of nano-particles on mechanical properties are investigated. The maincontents and results are listed as follows:The microstructure and thermoelectric properties of Ni-Te-Se codopedskutterudites are studied. The results show that the sizes of all sample grains arewithin the range of1-10μm. The grain sizes have no obvious changes with theincrease of the content of Ni. The suitable amount of Ni dopant not only resulted in animprovement of the electrical conductivity but also a drop of the lattice thermalconductivity. The highest ZT is greater than1.1at high temperature.The mechanical properties of composites Co4Sb11.5Te0.58Se0.12+x vol%TiN(x=0.0,0.5,1.0) after SPS are studied. It is found that the TiN particles dispersedalmost evenly, and part of the nano-TiN polymerizes in the form of aggregation. Theflexure strength are improved by the volume of addition. Compared with the TiN-freesamples, flexural strength of the composites are improved by15%. the fatigueproperty of the nanocomposite thermoelectric materials is increased significantly. Thefatigue fracture surface was basically characterized by intergranular fracture, whichsuggests brittle characteristics of the materials.