Chemical reaction at high temperature and high pressure V : kinetics of solid state reaction of zinc with phosphorus to form Zn3P2 under high pressure

Abstract

The rate of reaction between solid powders of zinc and phosphorus to form Zn_3P_2 has been studied at temperatures of 50～300℃ under pressures of 5～40kb. The rate was followed by measuring the amount of Zn_3P_2 by X-ray diffraction and found to fit the formula 1-x=6/πn^2Σ^^∞__n=1 1/n^2exp (-n^2kt) which is based on the diffusion of the components into spherical particles. The kinetic data are explained on the hypothesis that the rate of reaction is determined by the diffusion of zinc followed by a slower diffusion of phosphorus. The apparent activation energy E and the apparent activation volume ΔV≠ for the diffusion process were estimated to be 14～18kcal/mole and 3.3～4.1cm^3/mole for the temperature range 150～200℃ respectively. These values are in agreement with the activation enthalpy and the activation volume of the self-diffusion of zinc given by Liu and Drickamer under high pressure.