Chemical reaction at high temperature and high pressure IV : high pressure phases in the Ge-P system

Abstract

Several types of new high pressure phases is the germanium-phosphorus system have been prepared by direct union of germanium and red phosphorus at temperatures of 600～1500℃ and pressures of 10～50 kb. The high pressure equipments are the piston cylinder of Bridgman type and the compact cubic anvil. The main reaction process in this system under high pressure has been presumed by means of X-ray diffraction. The effects of temperature, pressure, reaction time and the composition of the reactants on the main reaction process are described in comparison with the silicon-phosphorus system under high pressure. Among the new high pressure phases a disordered sphalerite type GeP with a lattice constant of 5.581 Å and a sphalerite type GeP with a lattice constant of 5.463 Å are included. The sphalerite type GeP is the phase corresponding to the sphalerite type SiP and SnP obtained under high temperature and high pressure. The high pressure phase which corresponds completely to the pyrite type SiP_2 is not observed in the germanium-phosphorus system, but a similar cubic phase with a lattice constant of 5.619 Å, which may have a stoichiometric composition GeP_2, is confirmed. The phases is the germanium-phosphorus system are much more complicated than those in the silicon-phosphorus system under high pressure. It may be due to the higher metallic nature of germanium as compared with silicon.