High-pressure synthesis at the origin of new developments in silicon clathrate physical chemistry

Since their discovery in 1965, various compositions of clathrate phases of silicon have been investigated and have revealed a direct correlation between the doping element and their properties. The recent development of a new synthesis technique using high-pressure and high-temperature (HPHT) conditions allows the synthesis of peculiar clathrate compositions which can show fascinating properties, such as Ba8Si46 which is a sp(3) silicon-based structure with superconducting characteristics. This work reports the synthesis of the first binary silicon clathrate doped with an electronegative element and prepared using HPHT: I8Si46-xIx. Some chemical and structural results are also presented.