We investigated figure of merit in La-doped SrTiO 3 prepared by Combustion Synthesis (CS) with post Spark Plasma Sintering (SPS), on which effect of sintering time was mainly examined. The samples of Sr 0.92 La 0.08 TiO 3, CSed from oxides, carbonate, metal and sodium perchlorate, was prepared by SPS at 1573 K for 1, 5, 15 and 30 min for measuring thermoelectric properties from RT to 1173K. In conclusion, only 5-min-sintered product recorded a maximum value of 0.37 in figure of merit at 1045 K.

Thermoelectric properties of La-doped SrTiO 3 were investigated in order to determine the optimum sintering temperature for its fabrication by using a combination of combustion synthesis and spark plasma sintering. Combustion-synthesized samples (Sr 1Àx La x TiO 3 , x ¼ 0:08) were subjected to spark plasma sintering at temperatures from 1513 to 1663 K. The average grain size of sintered Sr 0:92 La 0:08 TiO 3 enlarged as sintering temperature rose up. The maximum average grain size was 23.5 mm for a sintering temperature of 1663 K. The thermoelectric properties of sintered Sr 0:92 La 0:08 TiO 3 were measured from room temperature to 1073 K. The optimum sintering temperature in the experimental sintering temperature range was 1633 K. Among the samples, the Sr 0:92 La 0:08 TiO 3 sample sintered at 1633 K showed the maximum power factor of 1:51 Â 10 À3 Wm À1 K À1 at 375 K. Further, we investigated the effects of pressing direction during sintering on the thermoelectric properties of combustion-synthesized Sr 0:92 La 0:08 TiO 3 . The combustion-synthesized samples were sintered well along the pressing direction during sintering; therefore, the electric conductivity measured along the pressing direction during sintering was more than twice that measured along the direction perpendicular to the pressing direction during sintering. Thus, we concluded that pressing direction during sintering affected the electric property of Sr 0:92 La 0:08 TiO 3 .

Single thermite-type combustion synthesis (STCS) for synthesizing Heusler alloy Fe2VAl from Fe, V2O5, and Al powders for thermoelectric applications was proposed and investigated, in which the microstructure and the thermoelectric properties of the product were mainly examined. Macroscopically, STCS was successfully carried out to produce metallic product of Fe2VAl in lower part and alumina as slag in upper part. According to SEM observation and FE-EPMA-analyzed, elemental mapping images, the product contained dispersed inclusions of spherical Al2O3 with 0.4 mol% and angulated AlN with 1.0 mol%. In comparison to the reported data on Fe2VAl, the thermal conductivity at room temperature became about half. It could be because of increased phonon scattering due to dispersed AlN&Al2O3 and non-stoichiometry of the product; Fe2.06V1.01Al0.93. As a result, the maximum values for the product were 99.6 mu W m K-1 (2) in power factor and 2.19 x 10 (3) at 309 K in dimensionless figure of merit

This paper describes thermoelectric properties of La-doped SrTiO 3 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 (Sr 1Àx La x TiO 3 , x ¼ 0:08) were spark-plasma-sintered (SPSed) at temperatures from 1513 to 1663 K and the thermoelectric properties of sintered Sr 0:92 La 0:08 TiO 3 were measured from room temperature to 1073 K. 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 1603 K. However, when sintering temperature rose over 1603 K, 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 1573 K showed the maximum of the dimensionless figure of merit of 0.16 at 1005 K.

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