Thermoelectric properties of heavy rare earth filled skutterudites Dy<inf>y</inf>Fe<inf>x</inf>Co<inf>4-x</inf>Sb<inf>12</inf>

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Journal Article
Journal of Electronic Materials, 2012, 41 (12), pp. 3402 - 3410
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Heavy rare earth element Dy-filled skutterudites (DyyFexCo4-xSb12) have been synthesized by a melting-quenching-annealing method and sintered by the spark plasma sintering technique. Our results suggest that single-phased DyyFexCo4-xSb12compounds could be obtained when the Fe content is less than 1.5. The maximum filling fraction of Dy in skutterudites increases with increasing Fe content. We also found significant lattice expansion induced by Fe substitution at Co sites and Dy filling in the voids. The electrical conductivity, Seebeck coefficient, and thermal conductivity have been measured in the temperature range from 300 K to 800 K. The low-temperature Hall coefficient and carrier mobility are reported in the temperature range from 2.5 K to 300 K. The power factor for DyyFexCo4-xSb12increases with increasing Fe content. A significant reduction in lattice thermal conductivity is observed in heavy rare earth element Dy-filled skutterudites due to the low localized vibrational frequency of Dy that effectively scatters low-frequency lattice phonons. The sample with composition Dy0.41Fe1.45Co2.55Sb12.28has lattice thermal conductivity as low as 1.05 W m-1K-1at room temperature. The thermoelectric figure of merit (ZT) reaches a maximum value of 0.67 at 750 K.© 2012 TMS.
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