Transition to n-type Thermoelectric Conduction in Ni-doped FeSe 2 Alloys

• Published in: 대한금속재료학회지 Vol. 60; no. 12; pp. 926 - 932
• Main Authors: 안영빈, Young Bin An, 박상정, Sang Jeong Park, 박옥민, Okmin Park, 김상일, Sang-il Kim
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.12.2022
• Subjects: FeSe 2</ sub>; thermoelectric transport
• ISSN: 1738-8228

We investigated the effect of Ni doping on the electrical, thermal, and thermoelectric transport properties of FeSe 2 polycrystalline alloys. FeSe 2 alloys exhibit both n-type and p-type conduction at different temperatures and thus their practicality as a thermoelectric material is somewhat limited. In this study, Fe 1-x NixSe 2 polycrystalline samples with x = 0, 0.01, 0.05, 0.075, 0.1, and 0.125 were synthesized, and it was shown that Ni doping in FeSe 2 alloys induces n-type conduction in the entire temperature range. The electrical conductivity is gradually increased with an increase in carrier concentration as Ni doping increases, from 8.52 (x = 0) to 329 S/cm (x = 0.125) at 300 K. The maximum power factor of 0.61 mW/mK 2 was observed in the Fe 1-x NixSe 2 sample at x = 0.01 at 600 K. Other Ni-doped samples exhibited power factors between 0.31 and 0.34 mW/mK 2 at 600 K. The thermal conductivity gradually decreased from 6.9 (x = 0) to 4.2 W/mK (x = 0.125) with Ni doping because of the additional point-defect phonon scattering of the Ni substitutes. As a result, a zT of 0.11 was observed in x = 0.01 at 600 K, while the zT of the other Ni-doped samples exhibited 0.056- 0.069 at 600 K. (Received 8 August, 2022; Accepted 7 September, 2022)