Structural, optical and thermal properties of Na2MgSnS4

Abstract

Thermal properties are inherent in all crystalline materials, and an understanding of thermal properties is integral to any application of interest. Furthermore, low thermal conductivity, κ, materials continue to be of great importance from both a fundamental scientific viewpoint as well as for technologically significant applications. Herein we report on the structural and thermal properties, as well as the optical properties, of the relatively unexplored quaternary chalcogenide Na₂MgSnS₄. The crystal structure, which can be thought of as being derived from cation substitution from the ternary chalcogenide NaCrS₂, was investigated via Rietveld refinement, and Raman spectroscopy revealed the Raman-active modes for this quaternary chalcogenide. Analyses and modelling of the temperature-dependent thermal properties revealed relatively large lattice anharmonicity and low average speed of sound resulting in intrinsically low κ. In light of the current interest in layered multinary chalcogenides, our results can be employed in the development of this and similar layered quaternary chalcogenides for applications of interest.