New Strategy for Black Phosphorus Crystal Growth through Ternary Clathrate

We are reporting a new synthetic strategy to grow large-sized black phosphorus (Black-P) crystals through a ternary clathrate Sn 24 P 22– x I 8, under lower synthetic temperature and pressure. The Black-P crystals are found grown in situ at the site where the solid clathrate originally resides, which suggests chemical vapor mineralizer does not play a critical role for the Black-P formation. More detailed systematical studies have indicated the P vacancies in the framework of the ternary clathrate Sn 24 P 22– x I 8 are important for the subsequent Black-P from phosphorus vapors, and a likely vapor–solid–solid model is responsible for the Black-P crystal growth. The obtained room temperature mobility μ is ∼350 cm 2 /V·s from Hall measurements at mechanically cleaved flakes, where noticeable microcracks are visible. The obtained high mobility value further suggests the high quality of the Black-P crystals synthesized through this route.