Influence of pH on the Morphology of KBr Solution Growth

The morphodrom of KBr crystal, growing in aqueous solution, has been obtained as a function of pH and supersaturation, by means of in situ observation with an optical microscope. The habit of the crystal changed from cubic to octahedral with increasing pH and supersaturation. The growth rate along [100] increased with increasing pH, while that along [111] decreased. The preferential adsorption of hydronium ions on the {100} face and OH- ions on the {111} face, resulting in the restriction of the growth rates was proposed for the interpretation of the influence of pH on the change of crystal habit. In situ observation of the macroscopic growth step patterns on the {100} face supported this presumption for the influence of pH on its growth.