Optimization of Sintering Temperature for Maximizing Dimensionless Figure of Merit of La-Doped Strontium Titanate Thermoelectric Material in the Combination of Combustion Synthesis with Post Spark Plasma Sintering
نویسندگان
چکیده
This paper describes thermoelectric properties of La-doped SrTiO3 prepared by using a combination of combustion synthesis (CS) with post spark plasma sintering (SPS), on which effects of sintering temperature were mainly examined. In experimental, combustion-synthesized (CSed) samples (Sr1 xLaxTiO3, x 1⁄4 0:08) were spark-plasma-sintered (SPSed) at temperatures from 1513 to 1663K and the thermoelectric properties of sintered Sr0:92La0:08TiO3 were measured from room temperature to 1073K. In experimental sintering temperature range, sintering temperature didn’t heavily affect the average grain size of sintered SLTO in the case that sintering temperature ranges from 1543 to 1603K. However, when sintering temperature rose over 1603K, the average grain size of sintered SLTO was dramatically affected and it increased with sintering temperature. With increasing sintering temperature, the effects of phonon scattering at grain boundaries decreased therefore, thermal conductivity of all sintered samples increased with sintering temperature. With increasing sintering temperature, electric conductivity of sintered SLTO increased and absolute value of Seebeck coefficient of sintered SLTO decreased because sintering at higher temperature caused the more oxygen defects which generate the larger carrier density. In conclusion, the product sintered at 1573K showed the maximum of the dimensionless figure of merit of 0.16 at 1005K. [doi:10.2320/matertrans.M2010102]
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