Thermoelectric performance of Dy/Y co-doped SrTiO3 ceramic composites with submicron A2Ti2O7 (A = Dy, Y) pyrochlore

Dy/Y co-doped SrTiO3 ceramic composites with submicron A(2)Ti(2)O(7) (A = Dy, Y) pyrochlore were in situ synthesized by a solid-state method. The microstructure of the A(2)Ti(2)O(7) phase and its relationship with the thermoelectric properties of Sr0.9-xDyxY0.1TiO3 ceramics are studied. As the Dy content increases, the secondary phase content increases and the grain size slightly decreases from 1.03 to 0.77 mu m; meanwhile, the grain size of the main phase also decreases. The highest power factor of 1034.5 mu WK-2 m(-1) at 569 K has been obtained for the x = 0.08 sample due to comparatively lower electrical resistivity. In addition, the introduction of Dy reduces the thermal conductivity dramatically by decreasing the grain size of the main phase, increasing the number of the second phase and enhancing the scattering of mass fluctuation. In the end, the zT> 0.20 is obtained within the range of size of 0.80-1.03 mu m and the mass fraction of 4.91%-13.50% for the second phase. The maximum zT value of 0.22 has been obtained for the x = 0.08 sample with the second phase size and the mass fraction of 0.88 mu m and 11.6%, respectively. Thus, heavy element doping and the second phase with the right grain size and proportion can result in high thermoelectric properties for SrTiO3 samples.

Automated summary

The microstructure and thermoelectric properties of Dy/Y co-doped SrTiO3 ceramic composites with submicron A(2)Ti(2)O(7) pyrochlore were studied. It was found that heavy element doping and the introduction of the right grain size and proportion of the second phase can lead to high thermoelectric properties in SrTiO3 samples. An optimized zT value of 0.22 was achieved for a sample with specific second phase size and mass fraction.