Wide-Temperature-Range Near-Zero Thermal Expansion via Stuffing-Controlled Dynamics in Diamond-Like Materials.

Near-zero thermal expansion (NZTE) materials are essential for emerging precision technologies, such as optical instruments and aerospace components. However, existing materials with robust performance over a broad temperature range are limited, especially if functional properties in addition to NZTE are sought. We report a data-driven materials design investigation and find that the zinc-blende structure is an excellent platform for obtaining NZTE and elucidating underlying crystal-chemical principles. Based on these, we introduced vacancy engineering and stuffed-atom incorporation, yielding a series of cubic quaternary chalcogenides AM3M'X4, where linkage ion vibrations are systematically modulated. We found that NaAg3TiS4, NaAg3TiSe4, and RbAg3TiSe4 are promising NZTE candidates with coefficients of thermal expansion below 2 × 10-6 K-1 over extended temperature windows (300-600 K). These are semiconducting materials distinct from low-thermal-expansion oxides. We explain the NZTE via the synergistic contributions of lattice softening, rigid-unit tilting, and linkage-ion transverse vibrations to the negative Grüneisen parameters. The stuffing of the zinc blende-based lattice provides a chemical way of tuning the linkage-ion transverse modes, thus controlling the thermal expansion in order to obtain NZTE.