Crystal surface morphology developed during the sublimation of oriented zinc single crystals

The surface structure of zinc single crystals subjected to a sublimation treatment has been studied by the techniques of optical metallography, optical goniometry and by Laue X-ray diffraction. Right cylinders with a <001> axis were enclosed, with titanium getter material, in Vycor tubes evacuated to 10^-5 mm Hg and heated to temperatures in the vicinity of 370°C for periods of 100 to 200 hr. A thermal gradient existed in the evacuated chamber such that zinc was transported from one end of the tube to the other end. The sublimation process exposed macroscopically visible crystallographic planes in local regions of the crystals. The three-dimensional structure of the facet morphology has been determined. The exposed planes are of the type {100}, {401}, {301}, {302}, {101}, {405}, {203} and {10 10}. The {0001} surfaces were relatively unaffected by the sublimation process. The facet structures appear to be related to some extent to the dislocation substructure and also to the Gibbs-Wulff surface energy construction for zinc.