L'effet photodiélectrique obtenu avec Zns(Cu, Co) et Zns(Cu. Ni)

Abstract
In a previous extensive study, it was pointed out that the dispersion of the complex dielectric constant of excited phosphors powders could result from three processes : the first kind process due to the dispersion of crystal dielectric constant, the second and the third kind processes being two kinds of peculiar Maxwell-Wagner dispersions. The experiments described here are concerned with ZnS(Cu), ZnS(Cu, Ni), and ZnS(Cu, Co). At a given frequency, the measurements of the real and imaginary part of the complex dielectric constant of the powder, show a killing effect on the dielectric change, parallel to the quenching of phosphorescence. For an equal quantity of killer, the killing effect is much more important with Ni. Further experiments with ZnS(Cu, Co) show that the main phenomenon impelled by introduction of Co, is a decrease of the critical frequency in the first kind effect dispersion region, while the static dielectric constant related to this region is hardly disturbed. In terms of a theory published elsewhere [1], this implies an increase of the barrier height inside the two-well-traps concerned. On the other hand, photoconductivity is increased, so that the second kind effect dispersion region overlaps the first one.