Powder Metallurgic Synthesis of Mid-temperature Lead-free AgSn$lt;inf$gt;18$lt;/inf$gt;SbTe$lt;inf$gt;20$lt;/inf$gt; Thermoelectric Materials and Processing Influence on Thermoelectric Performance

Lead-free thermoelectric materials gain increasing attention for environmentally friendly powergeneration applications derived from waste-heat sources. In this work, mid-temperature lead-free p-type AgSn 18 SbTe 20 thermoelectric materials were fabricated by a process combining mechanical alloying (MA) and spark plasma sintering (SPS). Electrical conductivity, Seeback coefficient, power factor and thermal conductivity of the sintered samples were measured in the temperature range from 300 K to 723 K, and the thermoelectric figure of merit, ZT, values were calculated. The phase structures and morphologies of the samples were observed. The effects of milling time and sintering temperatures on thermoelectric properties were investigated. And the results show that properly prolonging milling time and decreasing sintering temperature can enhance thermoelectric performance of the materials. The ZT value can be enhanced by 59% through optimizing the processing parameters, resulting in a relatively high ZT up to 0.62 at 723 K when the materials are milled for 12 h and sintered at 743 K.