| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 101 === Due to the limited resources exhaust gradually, development of new energy source、energy saving and carbon reduction, including fuel cell、reproductive alcohol、solar material, has become an important trend to our life. Thermoelectric materials is an expect way about the energy conversion. Thermoelectric materials and devices have widely used in the fields of energy conversion, sensors, and thermoelectric cooling. The ceramic thermoelectric materials are also well-known for no toxin and no pollution, is a highly anticipated material. SrTiO3 is a functional material it have lots of advantage for example : high dielectric constant、low dielectric loss and stable at high temperature, so it has widely used in electronic、mechanical、ceramic industry and photo catalytic fields. Recently it has been applied in the thermoelectric application, but difficult to sinter into dense bulk is a problem.
In this study, sintering behavior of La-doped SrTiO3 powders in reduction atmosphere (Ar-5%H2) and thermoelectric properties of dense bulk were investigated. Result shows that La-doped SrTiO3 powders were obtained from precursor by PC method and calcined at 600℃/9 h. The particle size of La-doped SrTiO3 is 10-30 nm . After CIP-ing, the powders were sintered at 1400℃/4h in Ar-5%H2 atmosphere. The bulks with relative density are higher than 92%, especially the Sr0.96La0.04TiO3 bulk with relative density of 99.2% were obtained. Second phase were found for the samples doping amounts of La larger than 8 mol%. The grain sizes of La-doped SrTiO3 bulks are 1 ~ 4 μm.
In terms of thermoelectric properties, the highest electrical conductivity of 63.58 S/cm at 303K was obtained in Sr0.96La0.04TiO3 sample. The specimen of SrTiO3 showed the best Seebeck coefficient of 380.37μV/K at 473K. And the maximum power factor of 502.43 μW/mK2 at 473K was obtained from the Sr0.96La0.04TiO3 sample.
Keywords: Thermoelectric materials, SrTiO3, PC method, High density bulks.
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