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

Abstract

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.

Enhancement of thermoelectric properties of La-doped SrTiO 3 bulk by introducing nanoscale porosity

“…For comparison, previously reported results [25,26,33,34] are shown in figure 3, as well. The undoped SrTiO 3 is found to be an insulator; however, its electrical conductivity has been improved with 20 at% La doping in each sample and this result is comparable with the previously reported results [23,24,26,35]. The electrical conductivity, σ of all the samples increases initially with temperature up to 647 K (figure 3 a ), and then it starts to decrease with temperature afterward.…”

Thermoelectric properties of A-site deficient La-doped SrTiO3 at 100–900 °C under reducing conditions

“…Undoped STO shows poor to moderate thermoelectric performance even in reducing atmosphere [16][17][18][19][20][21] and donor doping on the A-and B-site is a common approach to enhance the TE-properties. The variation in zT for La-doped STO has been reported in [22][23][24] showing zT values between 0. In the present investigation we take advantage of the encouraging results related to A-site deficient, donor doped STO [29,33].…”