Doping Modification Of Microwave Assisted Oxide Thermoelectric Materials

Thermoelectric materials are semiconducting functional materials, which can be used to achieve a direct interconversion between thermal energy and electric energy by the movements carriers. Thermoelectricity generation and cooling will be extensive applied in future. As environmental pollution and energy shortage problems gradually intensifying, thermoelectric materials and devices research has attracted inciusive attention, for example, oxide thermoelectric materials, because it is cheap and can be used in an oxidizing atmosphere, it has good development prospects. In this paper, microwave solid-phase sintering and conventional high-temperature solid-phase sintering method were used for preparing thermoelectric materials. Using X-ray diffraction (XRD), scanning electron microscopy(SEM) techniques to research structural characterization of materials and using the Linseis Seebeck Machine to test the seebeck, electric conducticity and power factor of the materials, and we studied the effects of different element kinds and doping sum on thermoelectric properties when the A, B sites were substituted.The Ca3Co4O9 materials were synthesized by using solid-state reaction method. The effects of doping on thermoelectric properties of Ca3Co4O9 thermoelectric oxide materials have been studied by A, B sites substituting with Na-In, La-In and Sr-In, respectively. The results showed that the doped material remained laminated structure, doping did not change its crystalline structure except the size. After doping, the Seebeck, electric conducticity and power factor of the materials apparently increased compared with the undoped materials. According to the series of co-doped components, the materials might have the best thermoelectric properties when x=y= 0.02, at the test temperature of 965 K, the the power factor could reach 250.0 μW·(mK2)-1 for Na-In co-doped materials, the power factor could reach 239.8 μW·(mK2)-1 for La-In co-doped materials, the seebeck could reach 203.0 μV/K for Sr-In co-doped materials.The CaMnO3 materials were synthesized by using solid-state reaction method. The effects of doping on thermoelectric properties of CaMnO3 thermoelectric oxide materials have been studied by A site substituting with Y, and A, B sites substituting with Y-Nb, respectively. The results showed that the doped material remained single-phase structure, doping did not change its crystalline structure except the size.After doping, the Seebeck, electric conducticity and power factor of the materials apparently increased compared with the undoped materials. According to the series of Y doped components, the materials might have the best thermoelectric properties when x=0.07, the power factor could reach 126.3 μW·(mK2)-1 at the test temperature of 965 K; according to the series of co-doped components, the materials might have the best thermoelectric properties when x=y=0.06, at the test temperature of 965 K, the power factor could reach 154.0μW·(mK2)-1 for Y-Nb co-doped materials.