Dielectric Anomalies in Zinc Sulfide and Cadmium Sulfide Excited by Light

概要

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Experimental data were obtained on the dielectric relaxation of Debye type in ZnS phosphor and Anti-Debye type in CdS phosphor when they were excited by light. Anti-Debye type dispersion was observed when the dielectric properties were measured as a function of temperature. It was different from ordinary Debye type : the maximum of ε" shifted to lower temperature with increasing frequency, and ε' decreased at the dispersion as temperature rose. The activation energies for the dielectric relaxation were calculated, they were : 0.33 eV for ZnS : Cu, 0.28 eV for ZnS : Ag, 0.89 eV for CdS (1100℃, 40 hrs. in Ar) and 0.37 eV for CdS (650℃, 30 min.). Some of these values were compared with those obtained by other authors. Anomalous behaviors were observed on the rise and decay curves of ε" in CdS phosphor when excited by light and when the excitation was removed at constant temperature. In some cases ε" under illumination became smaller than the dark value. A tentative interpretation for the Anti-Debye dispersion was given on the assumption of simple two-layer model.
東北大学の論文