FLAT AREAS ON UNTOUCHED METAL CRYSTALS AND ANISOTROPY OF THEIR SURFACE ENERGY

Spherical crystals of copper and other fcc metals are grown by solidification of a drop of melt in vacuum. Flat areas on their (111)- and (001)-poles allow to calculate relative surface energies. For copper this energy is smaller on (001) than on (111), contrary to the other fcc metals and to former ideas, but consistent with calculations of Nicholas. Facetting was observed on copper after an anneal at 5×10-6 Torr but not at 5× 10-9 Torr. Near the melting point Cu, Ag, and Au crystals show an inhomogeneous emission of light: the (111)- and (001)-poles appear darker than their surroundings. Probably this indicates surface melting of high indexed planes. © 1969.