Influences of spark plasma sintering temperature on the microstructures and thermoelectric properties of (Sr sub(0.95)Gd sub(0.05))TiO sub(3) ceramics

• Published in: Chinese physics B 2015-06, Vol.24 (6), p.067202-1-067202-5
• Main Authors: Li, Liang-Liang, Qin, Xiao-Ying, Liu, Yong-Fei, Liu, Quan-Zhen
• Format: Article
• Language: English
• Subjects: Ceramics; Density; Figure of merit; Grain size; Sintering; Spark plasma sintering; Thermal conductivity; Thermoelectricity
• ISSN: 1674-1056; 1741-4199
• DOI: 10.1088/1674-1056/24/6/067202

(Sr sub(0.95)Gd sub(0.05))TiO sub(3) (SGTO) ceramics are successfully prepared via spark plasma sintering (SPS) respectively at 1548, 1648, and 1748 K by using submicron-sized SGTO powders synthesized from a sol-gel method. The densities, microstruc-tures, and thermoelectric properties of the SGTO ceramics are studied. Though the Seebeck coefficient shows no obvious difference in the case that SPS temperatures range from 1548 K to 1648 K, the electrical conductivity and the thermal conductivity increase remarkably due to the increase in grain size and density. The sample has a density higher than 98% theoretical density as the sintering temperature increases up to 1648 K and shows average grain sizes increasing from ~ 0.7 mu m to 7 mu m until 1748 K. As a result, the maximum of the dimensionless figure of merit of ~ 0.24 is achieved at ~ 1000 K for the samples sintered at 1648 K and 1748 K, which was ~ 71% larger than that (0.14 at ~ 1000 K) for the sample sintered at 1548 K due to the enhancement of the power factor.