Microstructure and thermoelectric properties of Bi0.5Na0.02Sb1.48-xInxTe3 alloys fabricated by vacuum melting and hot pressing

The BiNaSbInTealloys(x =0.02-0.20) were synthesized by vacuum melting and hot pressing methods at 753 K,60 MPa for 30 min.Effects of Na and In dual partial substitutions for Sb on the thermoelectric properties were investigated from 300 to 500 K.Substituting Sb with Na and In can enhance the Seebeck coefficient effectively near room temperature.The electrical resistivity of the Na and In dual-doping samples is higher within the whole test temperature range.The BiNaSbInTesamples(x = 0.02,0.06) play a great role in optimizing the thermal conductivity.As for the BiNaSbInTealloy,the minimum value of thermal conductivity reaches 0.53 W·m·Kat 320 K.The thermoelectric performance of the Na and In dualdoped samples is greatly improved,and a figure of merit ZT of 1.26 is achieved at 300 K for the BiNaSbInTe,representing 26%enhancement with respect to ZT = 1.0 of the undoped sample.