High Performance BiSbTe Alloy for Superior Thermoelectric Cooling

At present, the weak thermoelectric and mechanical performance of zone-melting bismuth telluride alloys cannot support the further improvement of cooling and processing performance of semiconductor refrigeration devices. Here, MnO₂ is added into high-strength Bi_0.4Sb_1.6Te₃ prepared by ball milling method to optimize its thermoelectric transport properties. Via in situ reaction, Sb₂O₃ nano-precipitates are formed in the matrix, which also leads to the surplus of Te element. As results, the donor-like effect is suppressed, thereby increasing carrier concentration and power factor. Besides, volatilization of Te-rich phases during sintering leaves plentiful nanopores, which together with Sb₂O₃ nano-precipitates significantly decrease the lattice thermal conductivity. Eventually, the maximum ZT reaches 1.43 at 75 °C for the Bi_0.4Sb_1.6Te₃+0.01MnO₂ sample. On this basis, a 31-pairs module made of the material and commercial n-type BiTeSe produces large temperature differences (ΔT) of 70.1, 80.8, and 89.4 K at the hot-side temperature (T_h) of 300, 325, and 350 K respectively, which are highly competitive. The maximum coefficient of performance of 8.6 and cooling capacity of 7 W are achieved when T_h is set as 325 K. This excellent progress will promote the further development of bismuth telluride refrigeration modules.