Cu結晶の(111)面転位ピットの形態変化について

Abstract

Dislocation etch pits on the (111) surface of Cu crystals have been observed to study the effects of the composition, stirring rate and temperature of etchants and the small addition of Al in Cu. The etchants are Young’s solutions containing (NH4)2S2O8, NH4OH and NH4Br. The dislocation etch pit morphology strongly depends on the composition of the etchants. It is shown that the pit size varies with the concentration of the etchant and the pit shape varies with the ratio of each components in the etchant. At a ratio (NH4)2S2O8:NH4OH:NH4Br nearly equal to 1∼1.5:6:0.3, the triangular pyramid pits surrounded with 〈110〉 sides are produced, while, off this ratio, the etch pits tend to become more or less rounded. On the other hand, the stirring of the etchant increases the pit size remaining its shape unchanged. Such a tendency is also indicated with an increase of etchant temperature from 260 to 300 K, except a slight rounding of etch pit at 300 K. Moreover, with the addition of Al, the etch pits become small and rounded, though the straight-sided pits are revealed when etched with etchant containing high concentration of (NH4)2S2O8. Some discussions about the effects of the etching condition are given in connection with the kink nucleation and motion at the surface steps.