Negative photoplastic effect due to the relaxed excited state of the F-center in alkali halides

Abstract

To make clear the mechanism of the photoplastic effect (PPE) in alkali halides containing F-centers, on the basis of the photochemical reaction of the F-center, temperature dependence of the PPE in KC1, and KBr and NaCl was studied from 95 K up to RT. The characteristic critical points θ _ts in colored KC1 and KBr were determined to be 110 and 190 K, respectively. Below θ _t the sign of the PPE in both crystals was negative, i.e., decrement of the flow stress during light illumination was observed. Moreover, the θ _ts were in good agreement with the temperature where the photoconductivities show remarkable increase in the course of the measurements. The negative PPE is explained in terms of the rotation of the principal strain axis of the relaxed state of the F-center having ?100? tetragonarity as to relax the stress around the edge dislocation coming closely.     

Erratum notice

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Transmission electron microscopy, physics of image formation and microanalysis, by Ludwig Reimer (Berlin: Springer-Verlag); pp. 521; price, $A50.25.

Charged beam interaction with solids, by Yoshi-Hiko Ohtsuki (London: Taylor and Francis Ltd.); pp. 248; price, £22.50.

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Nuclear data for science and technology, Proceedings of the International Conference, September 6-10, 1982, Antwerp, Belgium. K. H. Böckhoff (Editor). D. Reidal Publishing Company. Price U.S.$120.00.     

The role of mosaic block structure on onset of deformation and fatigue of bulk crystallized polyethylene

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Optical and selected thermal properties of samarium-doped fluorochlorozirconate (FCZ) glass-ceramics: Formation and growth of BaCl2 nanocrystals in FCZ glass-ceramics

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