![]() The thermal conductivity is calculated as a product of the thermal diffusivity, specific heat, and mass density that are measured by laser flash (LFA457 Netzsch), a differential scanning calorimeter (DSC 404 C Netzsch), and an Archimedes’ kit, respectively. Thus, by using a higher HP temperature of 1,373 K and changing the Ti concentration, we have achieved higher power factor and ZT than the previously reported results for the same compositions ( 24). We also observe that the lattice thermal conductivity hardly changes within the range of grain sizes studied in this work. Furthermore, a record output power density of ∼22 W⋅cm −2 with a leg length ∼2 mm is experimentally obtained with T C = 293 K and T H = 868 K. Such an unusually high power factor has previously been observed only in metallic systems such as YbAl 3 and constantan ( 26, 27). We find that higher HP temperature enhances the carrier mobility, leading to a high power factor of ∼106 μW⋅cm −1⋅K −2 at 300 K in Nb 0.95Ti 0.05FeSb. ![]() Here we report the thermoelectric properties of the Nb 1-xTi xFeSb system with Ti substitution up to x = 0.3 prepared by using arc melting, ball milling, and hot pressing (HP) at 1,123 K, 1,173 K, 1,273 K, and 1,373 K. ![]() Because high-temperature heat treatment for TE materials can be beneficial to TE performance ( 25), further optimization may be achieved in the NbFeSb system. However, they studied only one sintering temperature at 1,123 K ( 12, 24). ( 24) reported a higher power factor of ∼62 μW⋅cm −1⋅K −2 at 400 K in Nb 0.92Ti 0.08FeSb that was attributed to less electron scattering. However, the composition with 40% Ti substitution strongly scatters the electrons as well. ( 23), a high power factor of ∼38 μW⋅cm −1⋅K −2 was realized in the p-type half-Heusler Nb 0.6Ti 0.4FeSb 0.95Sn 0.05 at 973 K. ![]()
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