Lone-Pair-Like Interaction and Bonding Inhomogeneity Induce Ultralow Lattice Thermal Conductivity in Filled β-Manganese-Type Phases

Oleksandr Cherniushok; Raul Cardoso-Gil; Taras Parashchuk; Rafal Knura; Yuri Grin; Krzysztof T Wojciechowski

doi:10.1021/acs.chemmater.2c00915

Lone-Pair-Like Interaction and Bonding Inhomogeneity Induce Ultralow Lattice Thermal Conductivity in Filled β-Manganese-Type Phases

Chem Mater. 2022 Jul 26;34(14):6389-6401. doi: 10.1021/acs.chemmater.2c00915. Epub 2022 May 27.

Authors

Oleksandr Cherniushok¹, Raul Cardoso-Gil², Taras Parashchuk¹, Rafal Knura^{1

3}, Yuri Grin², Krzysztof T Wojciechowski¹

Affiliations

¹ Thermoelectric Research Laboratory, Department of Inorganic Chemistry, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Mickiewicza Ave. 30, 30-059 Krakow, Poland.
² Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany.
³ Department of Science, Graduate School of Science and Technology, Kumamoto University, 2 Chome-39-1 Kurokami, Chuo Ward, 860-8555 Kumamoto, Japan.

Abstract

Finding a way to interlink heat transport with the crystal structure and order/disorder phenomena is crucial for designing materials with ultralow lattice thermal conductivity. Here, we revisit the crystal structure and explore the thermoelectric properties of several compounds from the family of the filled β-Mn-type phases M _2/n ⁿ⁺Ga₆Te₁₀ (M = Pb, Sn, Ca, Na, Na + Ag). The strongly disturbed thermal transport observed in the investigated materials originates from a three-dimensional Te-Ga network with lone-pair-like interactions, which results in large variations of the Ga-Te and M-Te interatomic distances and substantial anharmonic effects. In the particular case of NaAgGa₆Te₁₀, the additional presence of different cations leads to bonding inhomogeneity and strong structural disorder, resulting in a dramatically low lattice thermal conductivity (∼0.25 Wm^-1 K^-1 at 298 K), being the lowest among the reported β-Mn-type phases. This study offers a way to develop materials with ultralow lattice thermal conductivity by considering bonding inhomogeneity and lone-pair-like interactions.