Electronic structure and thermoelectric properties of narrow-band-gap intermetallic compound Al2Fe3Si3
We investigated the electronic structure and thermoelectric properties of a ternary intermetallic compound Al2Fe3Si3 composed only of abundant elements. First-principles band structure calculations implied that the target compound Al2Fe3Si3 forms a narrow band gap of a few hundred meV near the Fermi level, indicating that both p- and n-type thermoelectric properties can be obtained by shifting the chemical potential. We present the thermoelectric properties of the narrow-band-gap intermetallic compound Al2Fe3Si3, which was synthesized by arc melting and spark plasma sintering. The conduction type could be controlled through changing the Al/Si ratio. The measured Seebeck coefficients were +55 and −90 μV K−1 for p- and n-type materials, respectively. The obtained power factor was 370–400 μW m−1 K−2 in a mid-temperature region for both p- and n-type materials. Because of the low crystal symmetry of Al2Fe3Si3, the phonon thermal conductivity at 300 K exhibited a relatively low value of 4.5–5.5 W m−1 K−1, despite being composed of relatively light elements. The estimated dimensionless figure of merit was found to be less than 0.04, which should be largely enhanced for practical applications.
KeywordsThermoelectric properties Narrow band gap Intermetallic compound Band structure calculation Common elements
This work is supported by KAKENHI Grant Nos. 26709051 and 17H03421 from the Japan Society for the Promotion of Science (JSPS) and “Materials Research by Information Integration” Initiative (MI2I) project of the Support Program for Starting Up Innovation Hub from Japan Science and Technology Agency (JST). One of the authors (Y.T.) acknowledges Prof. Dr. Kaoru Kimura in University of Tokyo, Japan, for kind support on synthesis and measurements.
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