Study On The Effect Of Doping Diverse Ion In Ca₃Co₄O₉ Thermoelectric Material

Thermoelectric material is wide regarded in the world by applicational foreground of refrigeration and generating electricity, if the material figure of merit can be more enhanced, its probility of entering wide practicability will come true. Samdwich and Co-based oxide thermoelectric material is turned into a thermoelectric material of wide applicational foreground and fetching attention, because of its some excellent speciality. The paper study more systemic the different preparation technics and doping element and their effect of the Ca₃Co₄O₉ material shaped, structure and thermoelectric performance. The study result indicate:The most excellent temperature of solid sintering technics is 900℃or so, the temperature can both ensure the decompose of the CaCO₃ and creating the new CaO and accelerate celerity synthesize and stabilization of the Ca₃Co₄O₉. The two sintering technics and CaF₂ doping can accelerate the form and perfection of the Ca₃Co₄O₉ mineral crystalloid. but their effect of thermoelectric performance is complex, especially the effect of the CaF₂ doping, comparing the blank sample, the Seebeck coefficient is not evidence changed. appropriate CaF₂ doping in determinate temperature range, its electricity performance can be enhanced, but the excessive Fion doping can be made the increase of the sample resistivity. CaF₂ doping can be made the increase of the thermal conductivity. That the CaF₂ doping makes the synthetical effect of the Ca₃Co₄O₉ thermoelectric performance is disadvantageous.At Sol- gel method, the microstructure change of the Ca₃Co₄O₉ is not obvious. Comparing the blank sample, for the K doping, the effect of the sample Seebeck coefficient is not evidence, but the effects of the sample resistivity and power factor are disadvantageous. For the Zn doping, comparing the blank sample, the Seebeck coefficient is enhanced, and the determinate doping can make the effect of the sample resistivity not too obvious, and the advantage function of the sample power factor can be made in determinate temperature range. About the compound of the K and Zn doping, comparing the blank sample, the Seebeck coefficient is enhanced, and the resistivity is increased before 400℃, but it is decreased after the temperature, and the power factor is enhanced after 500℃, it is illuminated that the appropriate compound doping can enhance the power factor of the sample in some temperature range.The result in this thesis shows Ca₃Co₄O₉ is a promising thermoelectric material. Once it has appropriate synthesis method and suitable dopants, the probability of thermoelectric properities improvements will exist.