EXPERIMENTAL STUDY ON THE ELECTRIC FIELD OF DISLOCATIONS IN COLOURED ALKALI HALIDE CRYSTALS

Rksumk.- Nous avons anterieurernent rnesure le ( ( spectre de photoconductivite de dislo-cation)) dans la bande F dans des cristaux de KC1 colores aux rayons X. Le spectre est interpret6 en supposant que le champ electrique interne des dislocations en mouvement perturbe les centres F, y produisant un effet Stark quadratique. En coniparant nos resultats a ceux de Chiarotti, Grassano et a/., nous avons estinle le champ interne dans notre cristal. Ce travail a egalenlent ete effectuk dans plusieurs autres halogenures alcalins. Abstract.- Previously the ( ( dislocation photoconduction spectrum)) in the F band was mea-sured by us in X-ray coloured KC1 crystals. The spectrum was interpreted by assuming that the internal electric field of moving dislocations perturbed the F-centres producing a quadratic Stark-effect in them. Comparing our results with Chiarotti, Grassano et a/. we estimated the internal field in our crystal. This work was carried out on several other alkali halides as well. In ionic crystals edge dislocations have an excess electric charge which is neutralized by tlie field of ions surrounding tlie dislocation. If these crystals are deformed in a suitable way an electric signa