Temperature dependence of the dislocation line charge in sodium chloride single crystals

The dislocation line charge has been shown to change sign twice between room temperature and 800°C, in accordance with the theory of ESHEL8Y et al. From the fact that at room temperature the specimens are in the so-called pseudo-intrinsic region and from the room temperature value of the line charge, derived from an earlier described model, the free energy of formation of cation vacancies is found to be 0.93 eV, in good agreement with the value determined by DAVIDGE.