Figures of Merit of Low-Cost CuAl_0.9Fe_0.1O₂ Thermoelectric Material Prepared at Different Solid State Reaction Sintering Temperatures

Abstract:

In this study, we investigated a CuAl_0.9Fe_0.1O₂ compound prepared at two different sintering temperatures in order to find out the effect of sintering temperature on the compound's figure of merit of thermoelectric properties. The thermoelectric CuAl_0.9Fe_0.1O₂ compound was prepared from high purity grade Cu₂O, Al₂O₃ and Fe₂O₃ powders. The mixture of these powders were ground and then pressed with uniaxial pressure into pellets. The pellets obtained were sintered in the air at 1423 K and 1473 K. X-ray diffraction (XRD) patterns showed a single phase of CuAl_0.9Fe_0.1O₂ with rhombohedral structure, , along with a trace of CuO second phase. Moreover, the XRD peaks of the sample sintered at 1423 K indicated that more Fe³⁺ atoms replaced Al³⁺ atoms in this sample than they did in the sample sintered at 1473 K. The average grain size of the CuAl_0.9Fe_0.1O₂ compound prepared increased with increasing sintering temperature, whereas its mean pore size and porosity decreased with increasing sintering temperature. The dispersed small pores markedly decreased the thermal conductivity of the compound, while the Fe³⁺ substitution of Al³⁺ increased its electrical conductivity. The highest figure of merit (ZT) found was 0.021 at 973 K in the CuAl_0.9Fe_0.1O₂ sample sintered at 1423 K. Our findings show that this low-cost material with a reasonable figure of merit is a good candidate for thermoelectric applications at high-temperature.

• Periodical: Key Engineering Materials (Volume 659)
• Pages: 185-189
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.659.185
• Online since: August 2015
• Authors: Aparporn Sakulkalavek*, Rungnapa Thonglamul, Rachsak Sakdanuphab
• Keywords: CuAlO₂, Delafossite, Thermoelectric Material, ZT

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