Abstract
The etched surfaces of (110), (111), and (100) planes of copper single crystal, which had been treated with aq. solution of ammonium persulfate, were observed with electron diffraction and electron microscope.
On (110) plane, it was observed that all of the etched faces were covered with {110} faces consisting of piles of thin rhombic crystals.
When crystal surface was parallel to (111) plane, it was observed that triangular (111) faces appeared on the top of triangular pyramid consisting of {110} faces.
However, {100} faces were not observed on etched surface of (100) plane.
