Thermoelectric properties of hot-pressed Al- and Co-doped iron disilicide materials

In the present work, Al- and Co-doped beta-FeSi2 were fabricated by hot pressing technology at different pressures and a subsequent annealing process. For the prepared compacts, the phase, the microstructure, and the temperature dependent thermoelectric properties were characterized. The correlation of the materials factors: density, grain size, doping element, with the thermoelectric variables: Seebeck coefficient, electrical conductivity, thermal conductivity, ratio of electrical conductivity to thermal conductivity, and dimensionless figure of merit (ZT), is presented. The results show how the performance of thermoelectric FeSi2 could be affected by controlling materials compositions and processing conditions. At the measuring temperature of 923 K, a maximal ZT of 0.182 is achieved for Fe(0.9)5Co(0.05)Si(2), which was sintered at 1223 K and 50 MPa for 30 min under vacuum. The achieved ZT is believed to be comparatively large for thermoelectric beta-FeSi2. (C) 2006 Elsevier B.V. All rights reserved.