Effect of Annealing on Thermoelectric Properties of Bismuth Telluride Compounds

概要

論文の詳細を見る
The thermoelectric properties of the $p$-type (Bi0.25Sb0.75)2Te3 doped with 3 wt% excess Te and the $n$-type Bi2(Te0.94Se0.06)3 doped substantially with 0.07 wt% I and 0.02 wt% Te which were grown by the Bridgman method at a rate of 6 cm/h were measured before and after annealing, where the annealing was done in the temperature range from 473 up to 673 K for 1–10 h in vacuum and in a hydrogen stream. When annealing was done at 673 K for 2 h in vacuum, the power factor at 298 K for the $p$-type specimen increased by 35% from $4.25\times 10^{-3}$ to $5.72\times 10^{-3}$ W/mK2. In contrast, when annealing was done at 673 K for 5 h in a hydrogen stream, the power factor at 298 K for the $n$-type specimen increased by 24% from $4.82\times 10^{-3}$ to $5.99\times 10^{-3}$ K-1. The thermal conductivities $\kappa$ at 298 K for both annealed specimens then decreased by about 5%. As a result, the maximum thermoelectric figures of merit $Z$ at 298 K for the annealed $p$- and $n$-type specimens reached surprisingly large values of $4.16\times 10^{-3}$ K-1 and $3.99\times 10^{-3}$ K-1, respectively, with corresponding $ZT$ values of 1.26 and 1.19. The reason that the $Z$ values of bismuth telluride compounds were significantly enhanced by such an annealing is also discussed.
Publication Office, Japanese Journal of Applied Physics, Faculty of Science, University of Tokyoの論文
2003-02-15