• Mori, Takao
• Bourgès, Cédric
• Tsujii, Naohito
• Bauer, Ernst
• Gao, Weihong

Abstract

<jats:title>Abstract</jats:title><jats:p>We investigated the effects on thermoelectric properties of Cu doping in Fe<jats:sub>2‐<jats:italic>x</jats:italic></jats:sub>Cu<jats:sub><jats:italic>x</jats:italic></jats:sub>VAl at Fe site of full‐Heusler type compound. It is found that the Cu doping for Fe sites causes a significant increase in the absolute value of Seebeck coefficient |<jats:italic>S|</jats:italic> and a decrease in thermal conductivity. The Seebeck coefficient (<jats:italic>S</jats:italic>)=‐148μV/K and the Power factor (<jats:italic>PF</jats:italic>)=4.0 mWK<jats:sup>−2</jats:sup>m<jats:sup>−1</jats:sup> have been observed for Fe<jats:sub>1.9</jats:sub>Cu<jats:sub>0.1</jats:sub>VAl (<jats:italic>x</jats:italic>=0.1) at 300 K. To further improve it, we fixed the Cu doping level at x=0.1 in Fe<jats:sub>2‐<jats:italic>x</jats:italic></jats:sub>Cu<jats:sub><jats:italic>x</jats:italic></jats:sub>VAl and co‐doped the material with Si at Al site, namely, Fe<jats:sub>1.9</jats:sub>Cu<jats:sub>0.1</jats:sub>VAl<jats:sub>1‐<jats:italic>y</jats:italic></jats:sub>Si<jats:sub><jats:italic>y</jats:italic>.</jats:sub> The thermoelectric properties have been improved by Si doping to a certain limit. We observed a decrease in electrical resistivity and lattice thermal conductivity by Si doping for Al. The maximum power factor of 4.5 mWK<jats:sup>−2</jats:sup>m<jats:sup>−1</jats:sup> has been achieved for Fe<jats:sub>1.9</jats:sub>Cu<jats:sub>0.1</jats:sub>Al<jats:sub>0.9</jats:sub>Si<jats:sub>0.1</jats:sub> at 350 K. More precisely, the thermoelectric performance has been improved with co‐doping of Cu for Fe sites and Si for Al sites. The largest <jats:italic>ZT</jats:italic> value is 0.13 for Fe<jats:sub>1.9</jats:sub>Cu<jats:sub>0.1</jats:sub>VAl<jats:sub>1‐<jats:italic>y</jats:italic></jats:sub>Si<jats:sub><jats:italic>y</jats:italic></jats:sub> (<jats:italic>y</jats:italic>=0.15). Magnetic susceptibility suggests that all the measured compounds are showing paramagnetic behavior. The magnetic character is the most pronounced in Fe<jats:sub>1.9</jats:sub>Cu<jats:sub>0.1</jats:sub>VAl among the materials investigated, pointing to a possible correlation between the magnetic character due to electronic correlation and the larger Seebeck coefficient in this sample.</jats:p>

Topics

• impedance spectroscopy
• compound
• resistivity
• susceptibility
• thermal conductivity