Heteroepitaxial growth in aqueous solutions: Rubidium iodide on mica

We have performed a series of experiments in which the heteroepitaxial grow th of rubidium iodide on mica was carried out by precipitation from aqueous solution. The process was studied using time-lapse optical microscopy, ex situ atomic-force microscopy, and x-ray diffraction. We find that this is a n extremely robust epitaxial growth system, in that highly oriented islands are formed over a wide range of temperatures and evaporation rates. From t he x-ray measurements we find that die distribution of azimuthal island ori entations is in most cases less than 0.3 degrees wide, despite the fact tha t growth rates are generally well over 1 mu m/s. Using EX situ atomic-force microscopy, we show that during early stages of growth the external morpho logy of the epitaxial islands crosses over from a circular island shape to a triangular one, at an island size of approximately 1 mu m. Overall, the g rowth of salts on mica provides a rich environment in which to probe nuclea tion and growth phenomena as functions of temperature, evaporation rate, an d epitaxial misfit. [S0163-1829(98)02345-5].