Synthesis And Thermoelectric Properties Of Ag Doped Ca₂Co₂O₅

Abstract:People pay much attention to Ca2Co2O5based thermoelectric oxides due to their anti-oxidation thermal stability However,thermoelectric ZT of this kind of materials are still very low and limit its practical application which urges people to find new ways to improve the properties of the materials. In this dissertation, doped Ag was used to enhance the thermoelectric properties of Ca2Co2O5.Therefore,in this paper, Sol-gel method was applied to prepared Ca2Co2O5powders using Clacim Nitrate,Cobalt Nitrate and Citrateas raw materials. Initial pH, heating time, calcination temperature, lemon with metal ratio, calcining time to prepared phase Ca2Co2O5powder were studied, the most good preparation was determined Ca2-xAgxCo2O5(x=0,0.1,0.2,0.3) doped Ag was prepared under optimum preparation conditions and test their phase and morphology; Ca2Co2O5ceramics were fabricate by cold pressure and sintering process.the impacts of compressive strength on synthesizing Ca2Co2O5ceramics of adhesives, molding pressure, holding pressure time were investigated and the ceramic fracture surface thermoelectric properties of Ca2-xAgxCo2O5(x=0,0.1,0.2,0.3) were tested and analysed.Uniform plate-like Ca2Co2O5powder with particle diameter size of1μm, a thickness of about0.1μm can be successfully synthesized by Sol-gel method; the compression strength of Ca2Co2O5ceramic was about90MPa; Ca can be partially replaced by Ag and Ca2-xAgxCo2O5ceramic was P-type semiconductor preferential growth of the ceramic grains; doped samples of P-type semiconductor, Seebeck coefficient was positively correlated with temperature, while the electrical resistivity and thermal conductivity were negatively correlated with temperature; Ag doping could improves the carrier concentration and resistivity decreases; ZT value along with the increase of doped, the maximum ZT value reached0.221; Ag doped thermoelectric properties of Ca2Co2O5doped Ag was significantly improved. Totally,there are29pieces of figures,6sheets of tables and104pieces of references.