Morphology of potassium chloride in aqueous and in formamide solution — An experimental and computational investigation

Abstract

The morphology of potassium chloride grown in pure water as well as in water–formamide solution was investigated. Surface morphology of the crystals was examined by using scanning electron microscopy. It has been observed that the potassium chloride crystals are largely grown with {100} face at different concentrations in pure water, which contradicts earlier reports. Experimental results show that the potassium chloride crystals grown in formamide are also cubic in nature. However, it has been found that the sodium chloride crystals are octahedrons under similar conditions. The difference in the morphological behavior of these two alkali halides with formamide was investigated with computational methods. The calculated results revealed that formamide is largely preferred to adsorb on the {111} surface of NaCl, which can lead to octahedrons. However, the energetics is not substantially different for the adsorption of additives to the important surfaces of potassium chloride and results in the formation of a competing stable {100} surface.