Enhanced thermoelectric performance of tin oxide through antimony doping and introducing pore structures

Antimony-doped tin oxide nanopowders were synthesized by the hydrothermal method. Porous antimony-doped tin oxide ceramics with variant porosity were obtained by controlling the spark plasma sintering temperatures. It was found that antimony doping can effectively improve the electric conductivity of SnO $$_2$$ , while the nanosized pores sufficiently reduce the thermal conductivity. An extremely low thermal conductivity of 0.79 W m $$^-1$$ K $$^-1$$ is obtained at room temperature in the sample sintered at 500 $$^\circ $$ C with porosity of 32.2%. However, the porous sample exhibits poor electrical conductivity. With increasing sintering temperature, the porosity of ceramic samples decreases gradually. Consequently, the lattice thermal conductivity increases monotonically. Meanwhile, both electrical conductivity and Seebeck coefficient show improvement with increasing sintering temperature. After sintering at 1000 $$^\circ $$ C, Sn $$_0.99$$ Sb $$_0.01$$ O $$_2$$ sample still owns a porosity of 7.2% and the lattice thermal conductivity is still as low as 4.2 W m $$^-1$$ K $$^-1$$ . As a result, a maximum ZT of $$\sim$$ 0.05 is achieved at 500 $$^\circ $$ C for Sn $$_0.99$$ Sb $$_0.01$$ O $$_2$$ sintered at 1000 $$^\circ $$ C, which is higher than the ZT value ever reported for SnO $$_2$$ .