蒼鉛単結晶の蝕体現象と溶解速度の異方性について

Abstract

Phenomenon of solution bodies has been investigated with bismuth single crystals of circular rod and sphere forms etched with various reagents and some information as to the anisotropy of solution rate have been obtained. By etching with 31.6 percent nitric acid, a circular-rod crystal of which the rod axis is nearly parallel to the [111] direction converted into a hexagonal prism and crystals of which the rod axes are nearly parallel to the [\bar101] or [\bar211] directions transformed into elliptical rods. Also, a spherical crystal converted into a rugby ball-like shape of which the long axis coincided with the [111] direction and the surface was surrounded with six curved faces. From the relation of the forms and dimensions of the solution body produced with crystal orientations, it has been found that the relative rates of solution in 31.6 percent nitric acid along various crystal directions are in a ratio V〈111〉:V〈011〉:V〈001〉:V〈111〉:V〈\bar111〉:V〈\bar101〉=1.00:1.07:1.14:1.19:1.20:1.40. Reagents other than 31.6 percent nitric acid did not produce any clear-cut solution body. It was found, however, that the series of rates of solution in 50 percent aqueous solution of 1:2 mixture of hydrochloric acid and nitric acid (61.7%) was V〈111〉<V〈\bar211〉\doteqdotV〈\bar201〉.