Fabrication, dielectric, and thermoelectric properties of textured SrTiO3 ceramics prepared by RTGG method

Abstract

Textured SrTiO3 ceramics with extensive [100] orientation were fabricated with the reactive templated grain growth (RTGG) method, using tabular Sr3Ti2O7 (abbreviated as S3T) particles as the templates. The microstructure and texture development of the samples sintered in different atmospheres were investigated along with their electrical properties. The X-ray diffraction (XRD) pattern suggested that the ceramics were all single phase and had a relatively high Lotgering factor (f=0.9). Electron back-scatter diffraction (EBSD) results showed that the textured ceramics exhibited {100} preferred orientation. The samples sintered in air exhibited anisotropic dielectric properties. The green body was sintered in nitrogen and then annealed in a reducing atmosphere (nitrogen and graphite) to test its thermoelectric properties. The minimum thermal conductivity was 2.1Wm−1K−1 at 1073K, which is lower than that of non-textured SrTiO3-based thermoelectric materials that have been reported. The Seebeck coefficients were negative, and the value increased as the temperature and texture fraction increased. The Seebeck coefficients were much higher than those of non-textured SrTiO3-based materials. The maximum value was −328μV/K at 1073K, which amounts to ~76% of the value for a SrTiO3 single crystal.