Synthesis And Thermoelectric Performance Of The VA-VIA Nano-thermoelectric Materials

Thermoelectric material, is a kind of novel functional material. It converts directly heatenergy to electricity or reversely, and attracts much attention for its applications inthermoelectric power generation and cooling. In this dissertation，we developed an effectiveand precisely controlled synthesis of the thermoelectric materials with desired sizes andmorphologies, produced by simple and low-energy-consuming hydrothermal/solvothermalmethods. The as-prepared samples exhibited excellent thermoelectric performance. In thispaper, we study the syntheses, structures and morphologies of three kinds of thermoelectricmaterials in the V-VIA group. The thermoelectric properties have also been studied.Antimony telluride (Sb2Te3) hexagonal nanosheets have been prepared via a facilesolvothermal method without any templates. The Sb2Te3nanopowders were hot pressingsintered (HPS) to a nanostructured bulk material, and the thermoelectric properties weremeasured. Relatively high electrical conductivity, high Seebeck coefficient and low thermalconductivity have been achieved in the Sb2Te3nanosheet sintered bulk sample. Consequently,the maximum in ZT of0.57is achieved.Hierarchical nanostructured Sb2Te3has been synthesized through a simple greenhydrothermal method with EDTA as complexing agent and alginic acid as the reducing agent.Some factors influencing the compositions and morphologies of Sb2Te3nanocrystalsincluding the amount of alginic acid and solvents were also systematically investigated. Themaximum ZT of the Sb2Te3powder bulk sample sintered by hot pressing is0.21.Bismuth telluride (Bi2Te3) nanoflowers have been successfully synthesized via asolvothermal process, employing ethanolamine as solvent, Bi(NO3)3·5H2O and Na2TeO3asprecursors, ascorbic acid as reducing agent. A room temperature electrical conductivity of10.4×104-1m-1and a Seebeck coefficient of32μV K-1were obtained for the SPSsintered bulk sample.A facile solvothermal approach has been developed for the fabrication of antimonyselenide (Sb2Se3) nanowires. The optical property was also studied. The experimental resultsshow that the material may have great potential applications in optical, electrical andthermoelectric fields.