Chemical reaction at high temperature and high pressure III : reaction of silicon and phosphorus at high temperature and high pressure

Several kinds of new high pressure phases in the silicon-phosphorus system have been prepared by direct union of crystalline silicon and red phosphorus under the conditions of temperatures of 1100-1800℃ and pressures of 15-50kb. 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 pressures 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 have been investigated. Among the new high pressure phases, a cubic pyrite type silicon diphosphide SiP_2 with a lattice constant of 5, 682 A and a cubic sphalerite (zinc-blende) type silicon monophosphide SiP with a lattice constant of 5.241 A are included. SiP_2 is prepared at 1100-1500℃ under 20-40 kb. SiP may be formed through the following reaction only above about l700℃ under pressure of 40-50kb ; SiP_2→SiP+P. It is one of the characteristics of the silicon-phosphorus system that the reaction is influenced rather sensitively not only by temperature and pressure but also by the composition of reactants and the reaction time.