Low thermal expansion for self-compounded Fe1-xCoxS over a wide temperature range

Abstract

Zero thermal expansion (ZTE) materials have great application prospects benefited by the inhibition of thermal shock and dimensional mismatch. Herein, a novel self-compounded Fe1-xCoxS composite was obtained by a simple low-temperature annealing method. The second non-stoichiometric phase with a few cation vacancies from the thermal annealing is key to optimizing the thermal expansion behavior. The negative thermal expansion (NTE) region of one phase overlaps the positive thermal expansion (PTE) region of another phase to achieve low expansion in the wide temperature zone. As a result, the obtained Fe0.94Co0.06S sample displays near ZTE covering a wide temperature range (αL = 1.9 ppm/K, ΔT = 176 K) by annealing. Furthermore, the synergistic effect from the self-compounded composite can effectively avoid thermal mismatch compared to the traditional composites with matrix and filler. This study provides a new strategy for regulating the thermal expansion of transition metal chalcogenide materials.