Connection of activation volume and activation enthalpy with the bulk properties in olivine, LiBr and CsCl

The activation volume V^act has been measured for olivine, LiBr and CsCl. It is shown that the quantity V^act/H^act, where H^act denotes the activation enthalpy, is governed by the elastic properties of the bulk material in accordance to a model suggested by Varotsos and Alexopoulos. An explanation of the latter model for the migration process is attempted by means of the ballistic model independently suggested by Van Vechten.