Hydrothermal synthesis of iron pyrite (FeS22) crystalpowder and the rmal-kinetic study on crystal growth
水热法合成FeS2粉晶及其生长热动力学的研究

Single-phase iron pyrite (FeS 2 ) crystalpowder was prepared by sol-gel hydrothermal method, which was characterized via x-ray diffraction, Fourier transform infrared and scanning electron microscope. A simplified mathematic model was established to analyze the crystal growth process. Results indicate that phase transformation and diffusion mechanism control the process, which fits the second-order kinetic equation with an exponent 3.215 for time t. This is a decelerated process that can be divided into three steps: during the first period, marcasite and pyrite phases are produced, and then with inducting of sulfur into the reaction, the process is dominated by the merging of marcasite into pyrite. Ultimately, with the fuse of small grains and the growing of larger ones, single-phase iron pyrite crystals grow up through diffusion mechanism.