Electrical Properties Of CoSb₃-based Thermoelectric Materials By Hpht

Thermoelectric material is a sort of functional material that can be directly converted between thermal energy and electrical energy. The thermoelectric devices that are made of it will have a bright future in power generation and cooling under the condition of temperature difference. However, the thermoelectric material at present has a low conversion efficiency, which confines it greatly from being used extensively in the national economy in turn. Therefore, in order to utilize the thermoelectric material on a large scale, it is key to improve its conversion efficiency. At the same time, the conversion efficiency of thermoelectric material depends on the material's thermoelectric property, the better the property is, the higher the conversion efficiency is.The property of thermoelectric material can be measured by the dimensionless figure of merit-ZT: (?)In the formula, S is the Seebeck factor,σis the electrical conductivity,ρis the electrical resistivity, andκis the thermal conductivity. S2σor called power factor which is decisive to the electrical quality of the material. The ZT values of the thermoelectric material being studied are all fewer than 2, which cannot satisfy the need of practical application. Therefore, boosting the material's dimensionless figure of merit is key to improve its conversion efficiency.Because the thermoelectric material like Skutterudites have great carriers mobility, big Seebeck factor and high conductivity, so has gained great attention of relevant studiers. By means of filling and doping, we could boost the power factor and reduce the thermal conductance of this kind of material. By introducing the synthesis techniques under high temperature and pressure, filling and replacing the factors of CoSb3 cardinal compound, this paper will study the effect of complex pressure and the impure quantity of external atom on the electrical transportation performance of the thermoelectric material like Skutterudites.Firstly, the author will make an experiment by taking of BaN6 as the adulteration matter. Through analyzing XRD, we see that complex sample has a unidirectional CoSb3 structure, as well as a dimensional group Im3, it means that we could composite the thermoelectric material like Skutterudite under high temperature and pressure. Then the author will have a study on pressure's effect on Seebeck factor and electrical resistivity of compound Ba0.32Co4Sb12, and Through analyzing the power factor of compound Ba0.32Co4Sb12, we reach a conclusion that: solid phase reaction under high pressure could synthetic polycrystal and unidirectional compound CoSb3 of N type rapidly; we mix alkaline-earth metal Ba in the cavity of compound CoSb3 successfully; complex pressure has a great effect on the electrical quality of our experimental sample, as the value data of power factor of compound Ba0.32Co4Sb12 synthesised under 2GPa come up to its maximum is 15.46μWcm-1K-2. On the base of filling Ba into compound CoSb3, we have a research on the solid solution Te of Sb bits under high temperature and pressure.By testing the electrical characteristics of synthetical sample, we know that: by taking of Te as the adulteration matter and through metathesising Sb partly under high temperature and pressure, we could improve the electrical quality of synthesized sample greatly, and the electrical resistivity of impure sample is less than the pure one completely; the modulus of some sample's Seebeck factor gets a boost; the power factor of the material increases, when 710K is 24μWcm-1K-2, it increases nearly one point five times compared with the thermoelectric material of pure Te.The above research indicates that, by filling and replacing the thermoelectric material like Skutterudites in the use of the method under high temperature and pressure, we could improve its electrical nature effectively, restraining the thermal conductance from increasing and ameliorating the electrical characteristics of the material as well.