발간논문

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Vol.36, No.8, 1318 ~ 1324, 1998
Title
The effect of extrusion ratio on microstructure and thermoelectric properties of p type Bi0.5Sb1.5Te3 materials
서준호 , 주민철 , 이지환 Jun Ho Seo , Min Chul Ju , Chi Hwan Lee
Abstract
The p-type 4wt% Te-doped Bi_(0.5)Sb_(1.5)Te₃ compounds were extruded under ratio of 10:1, 20:1 and 30:1 at 420℃. The effect of extrusion ratio on the microstructure and thermoelectric properties has been studied. With increasing the extrusion ratio, grains are slightly refined due to the dynamic recrystallization and also slightly oriented along the extrusion direction. The Seebeck coefficient α and electrical resistivity ρ increased with increasing extrusion ratio, which might be due to the decrease of the carrier concentration. The thermal conductivity k is gradually decreased with increasing the extrusion ratio due to the grain refinement. The compounds hot extruded under ratio of 20:1 show the highest value of figure of merit Z (2.75×10^(-3)/K). The Seebeck coefficient α and electrical resistivity ρ increased after heat treatment at 400℃ for 3 hour. This indicates that Te vacancy formed by extrusion promote second phase Te atom to diffuse into matrix.
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