Clean Surface of Tungsten and Field-Evaporation Mechanism

Abstract

Temperature dependency of the surface phenomenon of tungsten and field-evaporation mechanism are investigated from the standpoint of surface energy and binding energy. The clean and atomically smooth surface is usually obtained by field-evaporation in field-ion microscope, which is different from that obtained by annealing without applied electric field. The annealing surface is approaching to the minimum state of chemical potential which is mainly controled by migration energy of surface atoms. The field-evaporation process at low-temperature is mainly influenced by polarization energy of atom under the influence of high electric field. The field-evaporation process at high-temperature is influenced by the activation energy for the surface self-migration of the surface atom on each crystal plane. The enhancement factors β1 and β2 of electric field applied on surface atoms are obtained by means of electrolytic trough and resistance network analogue computer. The step heights are calculated for various planes of B. C. C. metals, which are necessary to the calculation of local radii of curvature.