Color Center Formation in Sodium Chloride

Abstract

identical with those used to measure the relative changes in the Seebeck coefficient (AQ)/Q 0 . A chopper technique was used to eliminate the effect of the temperature gradient on the resistivity measurements. The relation between (AQ)/Q 0 and (Ap)/p 0 gives directly a simple function of the parameters K and JL. A second relation involving K, Q||, and Q ± is obtained from the zero-strain value of the Seebeck coefficient.We have used the K values given by Goldberg 2 to calculate (?.. and Q ± . Subtracting the electronic part of these as estimated from low-field Hall data, we have found the ratio of the components of the phonon-drag Seebeck tensor for a single Recent experimental work in this laboratory on the F-center production in synthetic sodium chloride at room temperature by ionizing radiation has revealed growth curves for synthetic crystals which differ from those obtained for halite. From Fig. 1 it can be seen that the nat-IOXI0 17 ENERGY ABSORBED (ev/cm 3 )

New oxygen centres in KCl single crystals

“…The presence of the O(1) centre leads to a marked increase in the growth rate of F centres during the first stage of colouration. Similar increases have been observed for KC1 crystals doped with OH- [16] and H- [17] and also for divalent-cation-doped crystals [17 to 191. When an X-irradiated O(1)-doped crystal is exposed to light in the F band region, the decay of the F band is accompanied by the simultaneous decay and growth of several absorption bands in the uv region in a complex pattern.…”

Ionic crystals

“…At room temperature the data indicate that the rate of formation of the F band is strongly dependent upon the presence of impurities (34). In Figure 12 one sees that the initial rate of coloration is influenced by the presence of hydroxyl ions; however, for very high doses of radiation, there is an indication that the energy absorbed per F center formed is about the same regardless of the impurity concentration.…”

On the Kinetics of the X‐Ray Irradiation‐Caused Degradation of Photoluminescence of Some Phosphors

“…In general, the physical processes which result in the growth of absorption were found to be rather complicated. However, in several cases, good agreement between theory and experiments (6,7) was reported. Such detailed studies, although they might provide a better understanding of the degradation process, were not conducted for irradiated phosphors.…”