Kaleidoscopic Incommensurate Structures of Aluminum-Substituted Rhenium Silicides

Al substitution leads
to kaleidoscopic vacancy-bearing crystal
structures in the rhenium silicides, ReAlxSi1.75–0.75x□0.25–0.25x (□ indicates Si/Al vacancies), including
two incommensurate structures newly found and successfully solved
with (3 + 1)-dimensional superspace groups in this work. The similarity
and difference among these structures, especially the subtle difference
in the ordered distribution of vacancies, are compared and discussed
in detail. With synthetic, crystallographic, and computational investigations,
we gained a comprehensive understanding of the composition–structure
relationship in these compounds, especially the ordered distribution
of Si/Al vacancies.