Preparation And Thermoeletric Properties Of Modified Titanium Oxide Ceramics

TiO₂is a kind of widely used inorganic oxide materials. It is normally an insulator.However, it can be an n-type semiconductor after being sintered at high temperature inreducing atmosphere. In this paper, TiO₂-xceramics are fabricated by the normalpressure sintering and microwave sintering respectively, and then heat-treated in N2-H2mixed atmosphere to obtain semiconducting behavior. Effects of graphene oxide,CuO-V₂O₅sintering additive, Ta₂O₅and sintering methods on the microstructure,sintering behavior and thermoelectric properties of TiO₂-xceramics are investigated.Addition of graphene oxide can enhance the electrical conductivity and lower thethermal conductivity of titanium dioxide. When the testing temperature is300℃, the ZTvalue of TiO₂-xceramics with0.2mass%graphene oxide can reach0.065, which is18%higher than that of the compared sample.CuO-V₂O₅sintering aid reduces the sintering temperature of TiO₂-xceramics from1350℃to1200℃. It also inhibits the growth of grain, which is helpful to lower thethermal conductivity of TiO₂-xceramics, and then improve their thermoelectricproperties. At500℃, the electrical conductivity of TiO₂-xceramics with1mass%CuO-V₂O₅is13S·cm^-1, which is about1.8times of the compared sample.The addition of Ta₂O₅can further enhance the electrical conductivity of thetitanium oxide, and then improve its thermoelectric properties. By adding5mass%Ta₂O₅, the electrical conductivity of the titanium oxide ceramics achieves maximum of53S·cm^-1at500℃, which is about4times that of the compared samples. Moreover, thepower factor can reach2.6×10^-4W·m^-1·K^-2at500℃, which is2.9times larger than thatof the compared samples.