Zinc diphosphide (ZnP<sub>2</sub>) is an inorganic chemical compound. It is a red semiconductor solid with a band gap of 2.1 eV. It is one of the two compounds in the zinc-phosphorus system, the other being zinc phosphide (Zn<sub>3</sub>P<sub>2</sub>).
Zinc diphosphide can be prepared by the reaction of zinc with phosphorus.
ZnP<sub>2</sub> has a room-temperature tetragonal form that converts to a monoclinic form at around 990 ðC. In both of these forms, there are chains of P atoms, helical in the tetragonal, semi-spiral in the monoclinic.
This compound is part of the Zn-Cd-P-As quaternary system and exhibit partial solid-solution with other binary compounds of the system.
ZnP<sub>2</sub>, like Zn<sub>3</sub>P<sub>2</sub>, is highly toxic due to the release of phosphine gas when the material reacts with gastric acid.