The intensity of the dielectric absorption in alkali halides containing divalent cations

The intensity of the dielectric absorption arising from the rotation of divalent ion-vacancy pairs in alkali crystals has been measured over a range of concentrations in the crystals NaCl:Ca 2+ , NaCl:Mn 2+ , KCl:Sr 2+ and LiF:Mg 2+ and found to agree with the value calculated from simple theory. In NaCl:Mn 2+ (and in some other systems) the absorption is slightly broader than a Debye curve. This is discussed in terms of the relative occupancy by vacancies of nearest neighbour and next nearest neighbour sites to the impurity ions.