Abstract
Thermal formation and destruction of M centers in fictitious KCl crystals have been studied and compared with the experimental results in real crystals. In fictitious crystals an idealized F-center distribution is introduced. Half of F centers are distributed uniformly and their positions are fixed and the other half are distributed to make pairs with each F center distributed uniformly. Such pairs with various inter F-center distances are handled as H2 molecules in a dielectric medium and their concentrations are computed statistically. By moving F centers belonging to the latter half under an attractive force, the variation of the concentration of F-center pairs sitting at the nearest negative ion sites (M centers) are computed statistically and compared with the experimental results in real crystals. It is shown that the variations computed in fictitious crystals explain nicely the variation of M-center concentration in real crystals. It is also shown that a potential in short range is effective enough for the thermal M-center formation.
