CREATION OF F CENTERS IN LITHIUM FLUORIDE BETWEEN 77 DEGREES K AND 600 DEGREES K AND THEIR INTERPRETATION BY A RECOMBINATION MODEL OF INTERSTITIAL-VACANCIES

In pure LiF crystals, the number of F centers generated by X-ray irradiation between 200° and 600°K is proportional to the square root of the irradiation time. At room temperature, for the same irradiation time, the number of F centers increases proportionately to the square root of the radiation intensity. At irradiation temperatures higher than 400°K a fraction of F centers clusters to form large agglomerates observable by small angle X-ray scattering. One assumes that the radiation creates KI Frenkel pairs per unit time (I being the radiation intensity) and that interstitials thus created diffuse towards F centers or towards traps which are assumed to be agglomerates of interstitials: the calculation leads to a generation law of F centers proportional to (It) 1 2 in good agreement with experimental results. One thus verifies this model by studying the disappearance of M centers by X-ray irradiation below 250°K: such a bleaching occurs through trapping of free interstitials by these centers. © 1969.