Electrical and thermal properties of Tb0.3Dy0.7Fe2-x

Samples of Tb0.3Dy0.7Fe2-x where x=0.05-0.10 (TERFENOL-D) were characterized for electrical resistivity and thermal diffusivity between room temperature and the Curie temperature, which for this composition is 360 degrees C. Additionally, the thermal diffusivity of one of the samples was measured to 1000 degrees C. Measurements were performed on two different orientations of standard, production-grade, grain-oriented TERFENOL-D produced by a Bridgman growth technique at ETREMA Products, Inc. The orientations were parallel and normal to the < 112 > crystallographic direction. The electrical resistivity and thermal diffusivity both exhibited isotropic behavior over the temperature range studied. The electrical resistivity of all samples increased monotonically from 0.06 m Omega-cm at room temperature to 0.14 m Omega cm at 360 degrees C, consistent with behavior expected for normal metals. The thermal conductivity was found to decrease with temperature from 135 mW/cm degrees C at room temperature to 122 mW/cm degrees C at 360 degrees C. The thermal diffusivity was found to exhibit a sharp cusp in the vicinity of the Curie temperature, T-C, increasing with temperature for T > T-C. Application of the Wiedemann-Franz law indicates that over 86% of the heat is carried by electrons. (C) 2000 American Institute of Physics. [S0021-8979(00)02602-5].