Enhanced thermoelectric performance of skutterudite Co1_yNiySn1.5Te1.5_x with switchable conduction behavior

A fine control of carriers in solids is the most essential thing while exploring any functionality. For a ternary skutterudite like CoSn1middot5Te1.5-x, which has been recently recognized as a potential material for thermoelectric conversion, the dominant carrier could be either electrons or holes via chemically tuning the quaternary Sn2Te2 rings in the structure. Both theoretical calculation and different spectroscopic probes, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were employed to unveil the conduction type switching details. On the other hand, a Ni-for-Co substitution was applied to enhance electronic transport, and thereby the thermoelectric power factor. Thanks to the substantial cut-off of lattice thermal conductivity by the characteristic Sn2Te2 rings in the skutterudite structure, ultimately a 70-fold increase in the dimensionless figure-of-merit (zT) is achieved at 723 K with the nominal composition Co0middot95Ni0middot05Sn1middot5Te1.5.

Automated summary

The researchers achieved control over the carrier type by manipulating the quaternary Sn2Te2 rings in the material's structure and enhancing electronic transport by substituting Ni for Co, thereby improving the thermoelectric power factor. This study demonstrates the potential of ternary skutterudite materials like CoSn1middot5Te1.5-x in thermoelectric conversion.