Orientation of chemical etch pits on (100) and (111) surfaces of silver

Abstract

The orientation of etch pits chemically formed on (100) and (111) surfaces of silver has been studied. On (100) faces, the etch pits changed from square with edges parallel to 〈110〉 directions to circles and then to square with edges parallel to 〈100〉 directions as the ratio of NH 4OH to H 2O 2 etching solution was reduced. On (111) faces, the etch pits were triangular or hexagonal, and all had edges parallel to the 〈110〉 directions. When the ratio of NH 4OH to H 2O 2 is large, the etch pits were “negatively oriented” triangles. The reduction of the ratio resulted in formation of hexagonal etch pits, while a further reduction yielded “positively oriented” triangles.