Intrinsically Low Thermal Conductivity in a Novel Cu‐S Modified ZrS₂ Compound with Asymmetric Bonding

Abstract

Materials with low thermal conductivity have received significant attention across various research fields, including thermal insulation materials, thermal barrier coatings, and thermoelectric materials. Exploring novel materials with intrinsically low thermal conductivity and investigating their phonon transport properties, chemical bonding, and atomic coordination are crucial. In this study, a novel ternary sulfide is successfully discovered, Cu2ZrS3, which is achieved by introducing copper ions into both the interlayer and intralayer of ZrS2. The resulting structure encompasses various coordination forms within each layer, such as [CuS4], [ZrS6], and [CuS3], leading to pronounced phonon anharmonicity induced by the asymmetric bonding of tri‐coordinated Cu atoms within the [ZrS6] layer. As a result, Cu2ZrS3 exhibits intrinsically low lattice thermal conductivity (κL) of about 0.83 W m−1 K−1 at 300 K and 0.35 W m−1 K−1 at 683 K, which are in the exceptionally low level among sulfides. In comparison to the conventional approach of inserting guests between layers, the substitution of atoms within layers provides a novel and effective strategy for designing low κL materials in transition metal dichalcogenides (TMDCs).

Three-Fold Coordination of Copper in Sulfides: A Blockade for Hole Carrier Delocalization but a Driving Force for Ultralow Thermal Conductivity

“…In conclusion, the realization of mixed frameworks involving the coexistence of two different types of polyhedra for copper (3-fold and tetrahedra) within the same matrix is a very attractive line of research to pursue for the discovery of efficient thermoelectric copper-based chalcogenides. This specific feature, described in high ZT tetrahedrite Cu 12 Sb 4 S 13 , has been recently reported in Cu 2 ZrS 3 , a 2D structure without a LP cation and exhibiting extremely low lattice thermal conductivity . Considering that copper-rich sulfides are also widely investigated for various applications and that thermal, electrical, but also mechanical and ionic properties of solids are closely related to atomic displacements and/or carrier concentration, we expect our findings to have wide materials-development implications.…”

“…This specific feature, described in high ZT tetrahedrite Cu 12 Sb 4 S 13 , has been recently reported in Cu 2 ZrS 3 , a 2D structure without a LP cation and exhibiting extremely low lattice thermal conductivity. 97 Considering that copper-rich sulfides are also widely investigated for various applications and that thermal, electrical, but also mechanical and ionic properties of solids are closely related to atomic displacements and/or carrier concentration, we expect our findings to have wide materialsdevelopment implications.…”