CHEMICAL REACTION AT HIGH TEMPERATURE AND HIGH PRESSURE VI Polymorphic Transition in ZnP, at High Temperature and High Pressure

:1 new pressure-induced modification of zincdiphosphide, ZnP2, has been prepared by the di reel union o(zinc with phosphorus and also through the polymorphic transitions of both monoclinic and tetragonal ZnP2. The application of pressures above 20 kb combined with temperatures above 150'C is required for [be synthesis. The new modification of ZnP2 has a pseuda•cuhic cps[al symmetry with a lattice constant a=5.322r~ and has a measured density 3.55 g/cma. It is found to be a semiconducting phase with an energy gap ER=0.44eV at 15 kb in [he temperature range from 20' to I50'C. The effects of temperature and pressure nn the polymorphic transition of monoclinic and tetragonal ZnP2 have been investigated and the stability region for the high pressure madiGcation determined by quenching method. The synthesis of a diamond-like farm of ZnP2, which is one of II-VZry•pe compounds. suggests [he possibility of synthesizing other unsymmetrical group 1V analogs which x'as predicted by Hall and Compton earlier.