Kinetics of Vaporization of Potassium Chloride Containing Calcium Impurity

The vaporization rates of the (100) face of single crystals of KCl have been measured in the temperature range 430–550°C for crystals containing from less than 2–700‐ppm calcium impurity. The vaporization rates of all Ca²⁺‐doped crystals were higher than the rate of the ``pure'' crystal at all temperatures in the range studied. The activation energy for vaporization of ``pure'' crystals taken from the slope of the log rate vs. T⁻¹ curves is $\text{48 ± 2}\mathrm{kcal}/\mathrm{mole}$ solid. The behavior of these samples with respect to divalent ion doping is opposite to that observed in Ca²⁺‐doped NaCl.