High thermal conductivity in Ga2TeO6 crystals: Synergistic effects of rigid polyhedral frameworks and stereochemically inert cations

Abstract

The investigation of thermal transport properties of materials has become increasingly important in technological applications, including thermal management and energy conversion. Recently, ultrahigh or low thermal conductivity has been reported in nitride, boride, and chalcogenide by different strategies. However, the strategy to design oxide crystals with unique thermal properties is also a challenge. In this work, a new ternary oxide crystal Ga₂TeO₆ is designed and expected to show high thermal conductivity due to its lone pairs-free octahedra connected along the c-axis by sharing edges. The thermal conductivities of Ga₂TeO₆ crystal are determined to be 19.2 and 23.9 W m⁻¹ K⁻¹ along the a- and c-axis directions at 323 K, respectively, which are significantly higher than those of most reported oxide crystals. First-principles calculations and crystal structure analyses reveal that the Ga₂TeO₆ crystal shows high sound velocity and weak lattice anharmonicity due to lone pairs-free octahedra and highly symmetric group arrangement. The results suggest that much attention must be paid to the polyhedron with lone pairs and its arrangement in materials design to balance the functions and thermal properties.