The thermophysical characteristics of the surfaces of crystalline bodies

Up to now, with very few exceptions, no distinction has been made in the scientific literature on the physics of interphase phenomena between the notions on surface energy and surface tension. For the liquid state, this is unimportant; however, for the solid crystalline state, the situation changes significantly. As follows from the results of calculations in [1–3], the ratio of the surface tension to the surface energy, for example, for alkali halide crystals at absolute zero temperature, varies from five to ten. It is very difficult to experimentally check these results because of lack of reliable methods for measuring these quantities in the solid state; furthermore, it is impossible to ascertain which method should be applied to measure one or another quantity. The main force characteristic of the surface of crystalline bodies, namely, the tensor of surface tension, is determined. The most general relationship between the components of the surface tension tensor and the surface energy is derived for a multicomponent solid, from which, with quite definite (but not always trivial) assumptions, the relation between them (known in the literature) is obtained. A mechanism is suggested to explain the considerable difference between the numerical values of the surface energy and the surface tension in the solid state.