Bi2Te3 based bulks with high figure of merit obtained from cut waste fragments of cooling crystal rods

Abstract

Bi2Te3 based cutting waste fragments were recycled by vacuum metallurgical technology to prepare p-type Bi2Te3 based thermoelectric materials. Through washing, vacuum metallurgical, component adjustment, second smelting and resistance pressing sintering (RPS) process, Bi0.4Sb1.6Te3 bulks were successfully obtained. All evidences confirmed that most of impurities from line cutting process such as Sb2O3 could be removed by washing, vacuum metallurgical process used in this work, and the recycling yield is up to 98%. The carrier content and corresponding thermoelectric properties could be adjusted effectively by appropriate component adjustment treatment. At lastly, a Bi0.4Sb1.6Te3 bulk was obtained and its' dimensionless figure of merit (ZT) could reach 1.07 at 379 K and the average ZT value was over 1.0 from 299 K to 419 K. Compared with the traditional process of recycling the single elemental Bi, Sb, Te by wet chemical metallurgical method, the vacuum metallurgical recycling technology introduced here is accordance with the principles of 3-R (reduce, reuse and recycle), and characterized by low cost, low degree of difficulty, low emission, high environmental protection and high efficiency, and the purified ingots can be directly used as raw material for the production of high-performance thermoelectric materials.