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SPS-Sintered NaTaO3-Fe2O3 Composite exhibits Large Seebeck Coefficient and Electric Current

NaTaO3-50wt% 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 microV/K over a wide temperature range. We report for the first time that SPS sintering at low temperature 870K could maintain the short-circuit current of -80 microA, which makes this thermoelectric material a possible candidate for high-temperature applications up to 1623 K. The reason for the good performance is the interface between Fe2O3 and surrounding NaTaO3 perovskite. When spark-plasma sintering (SPS) is used, constitutional vacancies disappeared and the electric conductivity increases remarkably yielding ZT of 0.016.