The diffusion of calcium in magnesium oxide

The diffusion of Ca2+ at tracer concentrations in 99·99% pure single crystal MgO has been measured over the temperature range 900°c to 1700°c. It was found that the diffusion coefficient, D, could be expressed in the form: The observed activation energy can be correlated with the corresponding data for other divalent ions diffusing in MgO through the equation: where k is Boltzmann's constant in ev/k and T is the absolute temperature. where r is the ionic radius in centimetres; α is the ionic electronic polarizability in cubic centimetres and k 1 and k 2 are equal to 0·37 × 10−16 ev cm2 and 1·20 ev respectively.