| Sung-Yoon Kim, Go-Eun Lee, and Il-Ho Kim* |
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| Charge Transport and Thermoelectric Properties of Mn-Doped
Tetrahedrites Cu12-xMnxSb4S13 |
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Received: 18 February 2021; Accepted: 2 March 2021. Published online: 6 April 2021. |
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| ABSTRACT |
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Mn-doped tetrahedrites Cu12-xMnxSb4S13 (0.1 ≤ x ≤ 0.4) were synthesized by mechanical alloying (MA) and
sintered by hot pressing (HP). A single tetrahedrite phase was synthesized by MA without post-annealing, and it was stable
without any phase changes after HP. The hot-pressed specimens had a relative density higher than 98.6%. The lattice constant
of the Mn-doped samples increased compared to that of undoped Cu12Sb4S13, but no significant change in the lattice constant
was observed with a change in Mn content. All Mn-doped tetrahedrites acted as p-type semiconductors, as confirmed from
positive Hall and Seebeck coefficient values. The Seebeck coefficient increased with increasing temperature but decreased with
increasing Mn content; maximum Seebeck coefficient values of 200−219 μVK-1 were obtained at 323−723 K for x = 0.1.
Electrical conductivity increased with increasing temperature and Mn content; the highest electrical conductivity values of
(1.76−2.45) × 104 Sm-1 were obtained at 323−723 K for x = 0.4. As a result, Cu11.6Mn0.4Sb4S13 exhibited a maximum power
factor of 0.80 mWm-1K-2 at 723 K. As the Mn content increased, both the electronic and lattice thermal conductivities increased,
and thus, the total thermal conductivity was the lowest at 0.48–0.63Wm-1K-1 at 323–723 K for x = 0.1. A maximum
dimensionless figure of merit of 0.75 was obtained at 723 K for Cu11.7Mn0.3Sb4S13. The MA-HP process is suitable for preparing
doped tetrahedrites exhibiting excellent thermoelectric performance. |
| Keywords:
thermoelectric, tetrahedrite, charge transport, mechanical alloying, hot pressing |
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