To study the behavior of divacancy and impurity, the diffusion process of I
nCl3 doped on the surface of a A-CI single crystal was measured by the inte
rnal friction and dielectric loss. All of the In3+ ions move to the disloca
tion core with a rate proportional to t(1/6) and the migration energy is 0.
060 eV. The concentration in the dipole of In3+ ion and cation vacancy rapi
dly becomes zero at the critical temperature 566 K. Reorientation of the di
pole and ionic conductivity gives an identical migration energy of 0.33 eV.
The binding energy between the vacancy and the trivalent impurity E-b is 0
.10 eV.