Journal of Electronic Materials

, Volume 40, Issue 5, pp 662–669

Effects of Ir Substitution and Processing Conditions on Thermoelectric Performance of p-Type Zr0.5Hf0.5Co1−xIrxSb0.99Sn0.01 Half-Heusler Alloys

  • Nathan J. Takas
  • Pranati Sahoo
  • Dinesh Misra
  • Hongfang Zhao
  • Nathaniel L. Henderson
  • Kevin Stokes
  • Pierre F.P. Poudeu
Article

DOI: 10.1007/s11664-010-1501-0

Cite this article as:
Takas, N.J., Sahoo, P., Misra, D. et al. Journal of Elec Materi (2011) 40: 662. doi:10.1007/s11664-010-1501-0

A series of samples with the composition Zr0.5Hf0.5Co1−xIrxSb0.99Sn0.01 (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−xIrxSb0.99Sn0.01 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 com- position Zr0.5Hf0.5Co0.5Ir0.5Sb0.99Sn0.01. The thermal conductivity of Zr0.5Hf0.5- Co1−xIrxSb0.99Sn0.01 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 

Copyright information

© TMS 2011

Authors and Affiliations

  • Nathan J. Takas
    • 1
  • Pranati Sahoo
    • 1
    • 2
  • Dinesh Misra
    • 1
  • Hongfang Zhao
    • 1
    • 2
  • Nathaniel L. Henderson
    • 1
  • Kevin Stokes
    • 1
    • 3
  • Pierre F.P. Poudeu
    • 1
    • 2
  1. 1.The Advanced Materials Research InstituteUniversity of New OrleansNew OrleansUSA
  2. 2.Department of ChemistryUniversity of New OrleansNew OrleansUSA
  3. 3.Department of PhysicsUniversity of New OrleansNew OrleansUSA

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