Sn-assisted solid state crystallization of red phosphorus to black phosphorus

Low-cost red phosphorus (RP) can be completely transformed into black phosphorus (BP) in a solid-state through a ball milling process and a sintering process. With the addition of 1.5 wt.% Sn, RP was fully crystallized into Sn-doped BP and the electrical conductivity was also enhanced to 1625 S m−1 at 300 K, 16 times higher than the 100 S m−1 of pure BP. This study reveals the mechanisms of the complete phase transformation from amorphous RP to crystalline BP with the help of Sn, and electrical enhancement, due to the role of Sn as a p-type dopant.