Cleavage Surface Energy of {100} Magnesium Oxide

Abstract

The modification of the Gilman cleavage technique described recently by Westwood and Hitch has been used to determine the surface energy γ0 of {100} MgO at 298°K. The value 1150±80 ergs/cm2 is in good agreement with previous experimental estimates of γ0, but somewhat lower than theoretical estimates. Metallographic studies were made of the plastic relaxation that occurs in the vicinity of the crack tip when cleavage cracks are repropagated, and a correlation between the extent of plastic relaxation, crack length, and the measured cleavage surface energy was observed.