Thermoelectric Properties of $\beta$-Fe1-xCoxSi2 Semiconductors

概要

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The thermoelectric properties of Co-substituted $\beta$-FeSi2 (Fe1-xCoxSi2, $0.00\leqq x\leqq 0.10$) have been characterized by Hall effect measurements at 300 K and by measurements of electrical resistivity ($\rho$), Seebeck coefficient ($S$), and thermal conductivity ($\kappa$) between 300 and 1150 K@. Fe1-xCoxSi2 samples are $n$-type in the measured temperature range. The electrical resistivity, Seebeck coefficient, and thermal conductivity are strongly affected by the Co substituting concentration ($x$). For the composition $0.00\leqq x\leqq 0.05$, $\kappa$ decreases with increasing temperature, reaches a minimum, and increases. At $x=0.10$, the $\kappa$ increases monotonically with increasing temperature. From the composition and temperature dependences of $\kappa$, it was found that the thermal conductivity of the lattice component $\kappa_{\text{ph}}$ is dominant in Fe1-xCoxSi2 semiconductors. At low temperatures, $\kappa_{\text{ph}}$ can be explained by the presence of small polarons. At $x=0.05$, the power factor ($P=S^{2}/\rho$) as well as the dimensionless figure of merit ($\mathit{ZT}$) shows a maximum value of $1.1\times 10^{-5}$ W/cm K2 and 0.25 at 940 K.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2001-05-15