PHOTOLUMINESCENCE AND THERMALLY STIMULATED LUMINESCENCE IN KMGF3-EU2+ CRYSTALS

Rare earth impurities constitute an important group of activators for ionic crystals, and originate phosphors which exhibit, in general, interesting features of luminescence yield and efficiency. Because of possible technological application, insulating crystals doped with rare earth ions have attracted attention in the past few years. In search of new luminescent materials for radiation dosimetry, Eu-doped crystals of KMgF3 (a compound which belongs to the perovskite group) were recently investigated. They showed intense thermoluminescence signals and quite encouraging dosimetric properties. Hence the importance of the investigation on the nature of the point defects contained in the phosphor and the dependence of their luminescence on the sample quality and history. Optical absorption and emission measurements clearly show that, despite doping of the material with Eu3+ ions, only Eu2+ ions are incorporated in the crystalline samples. Systematic thermoluminescence experiments indicate that the intensity of the glow peak of the impurity is linearly dependent on the dopant concentration and on the radiation dose.