Morphology and growth mechanism of vapor grown Cd crystals as affected by Bi impurity

The effects of Bi impurity on the morphology and growth mechanism of (physical) vapor-deposited Cd crystals were investigated. Scanning electron microscopic observation revealed, for the first time, hexagonal prismatic Cd crystals which were grown on the Bi contaminated pyrex glass tube wall. This kind of morphology does not appear in the case of pure Cd without the impurity Bi. The top of the hexagonal prismatic crystal was usually rounded hemispherically. X-ray microprobe investigations showed that the tip of the crystals contained about 57 wt% Bi. It was concluded that the Cd hexagonal prismatic crystals grow by the mechanism of vapor-liquid-solid with the impurity Bi.