Elsevier, Materials Science and Engineering: B, (197), p. 75-81
DOI: 10.1016/j.mseb.2015.03.011
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Ball milling (BM) combined with spark plasma sintering (SPS) is increasingly used for fabricating high-performance thermoelectric materials. This work was conducted to clarify the effects of BM and SPS on the electrical transport and thermoelectric properties of both p- and n-type Bi2Te3 based materials using commercially available p-type (Bi,Sb)2Te3 and n-type Bi2(Se,Te)3 ingots. Interestingly, it is found that BM and SPS differently affected the electrical properties of p- and n-type Bi2Te3-based thermoelectric materials; the dimensionless thermoelectric figure of merit (ZT) increases in p-type Bi0.5Sb1.5Te3 but decreases somewhat in n-type Bi2Te2.7Se0.3 after BM and SPS. Hall experiments reveal the reason for this difference. Both p-type and n-type sintered materials show 2–3 times higher mechanical strength than the ingots because of microstructure refinement effect, which has been measured by using a small-sized biaxial bending test. The improved mechanical properties are in favor for device fabrication.