Synthesis, Characterization, and Ultralow Thermal Conductivity of a Lattice-Mismatched SnSe₂(MoSe₂)_1.32 Heterostructure

A significant experimental challenge in testing proposed relationships between structure and properties is the synthesis of targeted structures with atomistic control over both the structure and the composition. SnSe₂(MoSe₂)_1.32 was synthesized to test the hypothesis that the low-temperature synthesis of two interleaved structures would result in complete turbostratic disorder and that the disorder would result in ultralow thermal conductivity. SnSe₂(MoSe₂)_1.32 was prepared by depositing elements to form a precursor containing Sn|Se and Mo|Se bilayers, each containing the number of atoms required to form single dichalcogenide planes. The nanoarchitecture of alternating Sn and Mo layers is preserved as the dichalcogenide planes self-assemble at low temperatures. The resulting compound contains well-formed dichalcogenide planes that closely resemble that found in the binary compounds and extensive turbostratic disorder. As expected from proposed structure-property relationships, the thermal conductivity of SnSe₂(MoSe₂)_1.32 is ultralow, ∼0.05 W m^-1 K^-1.