Transport properties of unfilled Co1-x-yNixFeySb3 skutterudites synthesized via a rapid hydrothermal procedure: Analysis of the lattice thermal conductivity
Ahmad Gharleghi1*, Chia-Jyi Liu1
1Department of Physics, National Changhua University of Education, Changhua, Taiwan
* presenting author:AHMAD GHARLEGHI,
A series of co-doped Co1-x-yNixFeySb3 were fabricated using a rapid hydrothermal method at 170°C for a duration of 12 h, followed by evacuated-and-encapsulated heating at 580°C for a short period of 5 h. The resulting samples are characterized using powder x-ray diffraction, density, electronic and thermal transport measurements. The power factor of Co1-x-yNixFeySb3 is significantly enhanced in the high temperature region due to significant enhancement of the electrical conductivity and absolute value of thermopower. The latter arises from the onset of bipolar effects on thermopower being shifted to higher temperatures as compared with the nondoped CoSb3. The thermal conductivity of Co0.76Ni0.14Fe0.10Sb3 decreases with temperature down to 1.02 Wm-1K-1 at 600 K. As a result, the largest zT of 0.68 is attained for Co0.76Ni0.14Fe0.10Sb3 at 600 K. Furthermore, the lattice thermal conductivity is analyzed to gain insight into the contribution of various scattering processes that suppress the heat transfer through the phonons in Co1-x-yNixFeySb3.

Keywords: Thermoelectrics, Cobalt Skutterudites, Hydrothermal Synthesis, Bipolar Effects, Low Thermal Conductivity