MAX phases Hf2(SexS1_ x)C (x=0-1) and their thermal expansion behaviors

Herein, a series of chalcogen-containing MAX phases, Hf2(SexS1_x)C, were successfully synthesized, whose lattice parameter change follows the Vegard's law. The average coefficient of thermal expansion (CTE) can be continuously tuned from 7.59 mu K_ 1 to 9.93 mu K_ 1 when the occupancy rate x of Se changes from 0 to 1. The substitution of Se for S effectively soften the crystal structures that is reflected by long average M-A bond in Sealloying Hf2(SexS1_x)C. However, the CTEs along a and c axes in all Hf2(SexS1_ x)C MAX phases are almost same which may be find application in thermal barrier coating (TBC) that isotropic volume change is highly demanding.

Automated summary

A series of chalcogen-containing MAX phases, Hf2(SexS1_x)C, were successfully synthesized, and their lattice parameter change followed Vegard's law. The average coefficient of thermal expansion (CTE) could be continuously tuned by substituting Se for S, with Hf2(SexS1_x)C MAX phases having tunable CTE values ranging from 7.59 mu K_1 to 9.93 mu K_1. The substitution of Se effectively softened the crystal structures, as reflected by the longer average M-A bond in Sealloying Hf2(SexS1_x)C. Additionally, the CTEs along the a and c axes in all Hf2(SexS1_ x)C MAX phases were almost the same, indicating their potential application in thermal barrier coatings (TBC) that require isotropic volume change.