| Abstrakt: |
Secondary nuclei of potash alum crystals may easily be produced by gentle crystal contact. In this investigation, crystal faces of the {100}, {110} and {111} families were identified in a parent crystal, and gentle contact between these and a solid surface in a slightly supersaturated solution of potash alum produced many secondary nuclei of the same orientation. Breeding of the large number of particles produced by contact between a parent crystal and a glass surface under supersaturated aqueous solution was directly observed by optical microscopy with an in situ, thermostatted cell. A strong correlation was found between the symmetry of the nuclei produced and that of the parent crystal face. Ex situ scanning (SEM) and transmission electron microscopic (TEM) measurements were also carried out to study this type of secondary nuclei, produced from a known surface geometry. In these cases, many small nuclei in the size range of 50 nm to 1 μm were produced and studied. The larger crystals displayed morphologies commensurate with that of the parent face; the very small nuclei, whilst frequently showing very poorly ordered boundaries, nonetheless were highly ordered internally, as shown by electron diffraction, the symmetry observed reflecting that of the parent face. |
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