SPS-sintered NaTaO3-Fe2O3 composite exhibits enhanced Seebeck coefficient and electric current

Abstract

NaTaO3 - 50 wt% Fe2O3 composite ceramics showed a large Seebeck voltage of -300 mV at a temperature gradient of 650 K yielding a constant Seebeck coefficient of more than -500 μV/K over a wide temperature range. We report for the first time that spark plasma sintering (SPS) at low temperature (870 K) could maintain the short-circuit current of -80 μA, which makes this thermoelectric material a possible candidate for high-temperature applications up to 1,623 K. The reason for the good performance is the interface between Fe2O3 and surrounding NaTaO3 perovskite. When SPS is used, constitutional vacancies disappeared and the electric conductivity increases remarkably yielding ZT of 0.016.