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Article
Effects of Ir Substitution and Processing Conditions on Thermoelectric Performance of p-Type Zr0.5Hf0.5Co1−xIrxSb0.99Sn0.01 Half-Heusler Alloys
Journal of Electronic Materials (2011)
  • Nathan J. Takas, Georgia Southern University
  • Pranati Sahoo
  • Dinesh Misra, University of New Orleans
  • Hongfang Zhao
  • Nathaniel L. Henderson
  • Kevin L. Stokes, University of New Orleans
  • Pierre F.P. Poudeu, University of New Orleans
Abstract
A series of samples with the composition Zr0.5Hf0.5Co1−x Ir x Sb0.99Sn0.01 (x = 0.0 to 0.7) were synthesized by high-temperature solid-state reaction at 1173 K. High-density pellets of the powders were obtained using hot press (HP) and spark plasma sintering (SPS) techniques. The thermoelectric properties of the pellets were measured from 300 K to 750 K. Independently of the pressing conditions, all Ir-containing samples (x > 0) showed p-type semiconducting behavior. At 300 K, the electrical conductivity and thermopower of Zr0.5Hf0.5Co1−x Ir x Sb0.99Sn0.01 materials surprisingly increased with increasing Ir concentration. The largest electrical conductivity and thermopower values of 150 S/cm and 140 μV/K, respectively, were observed at 300 K for x = 0.7. The thermal conductivity of the synthesized materials decreased with increasing Ir content, went through a minimum value (x = 0.3), and increased thereafter with further addition of Ir. Pellets fabricated by SPS showed smaller thermal conductivity than pellets of the same composition obtained from uniaxial hot pressing. A thermal conductivity value of ∼2.0 W/m K was observed at 300 K for an SPS pellet with the composition Zr0.5Hf0.5Co1−x Ir x Sb0.99Sn0.01. The thermal conductivity of Zr0.5Hf0.5-Co1−x Ir xSb0.99Sn0.01 decreased with rising temperature, and the smallest value of ∼1.5 W/m K was observed at 750 K for the SPS specimen with x = 0.5.
Keywords
  • Thermoelectric materials,
  • Phonon scattering,
  • Iridium,
  • Half-Heusler compounds,
  • Thermal conductivity
Disciplines
Publication Date
2011
Citation Information
Nathan J. Takas, Pranati Sahoo, Dinesh Misra, Hongfang Zhao, et al.. "Effects of Ir Substitution and Processing Conditions on Thermoelectric Performance of p-Type Zr0.5Hf0.5Co1−xIrxSb0.99Sn0.01 Half-Heusler Alloys" Journal of Electronic Materials Vol. 40 Iss. 5 (2011)
Available at: http://works.bepress.com/nathan_takas/4/