DIFFUSIONAL EVOLUTION OF DISPERSE CRYSTAL LINE PARTICLES DURING THE SINTERING ON THE SURFACE OF CRYSTAL

Diffusional evolution of fine crystalline particles LiF during the sin tering on vicinal surfaces of the same monocrystal in the temperature range 600-780-degrees-C has been studied by electron microscopy. The s intering of particles begins after the formation of epitaxial orientat ion with regard to the substrate and realises itself by layers as a re sult of adsorbed molecules redistribution among steps of particles wit h different curvature. Process of evaporation competes with the proces s of surface diffusion as a result of the opposite directions of step motion. The speed of steps and kinetic laws of spreading during the si ntering for different limiting conditions were found. In the case R mu ch greater than lambda (R - particle radius, lambda - effective surfac e diffusion length) predominate evaporation, solid spreading is possib le by surface diffusion only at R much less than lambda. New mechanism of spreading by diffusional coalescence of steps at R much greater th an lambda was experimentally observed and theoretically described.