Enhancing and Quenching of Intrinsic Luminescence and Characteristic Features of Calcium Tungstate Phosphorescence in the Presence of Lanthanides

It is found that doping of CaWO4 by impurities of the lanthanide series (their concentration in the charge 10−6 to 10−5 g-atom/mol) causes the increase of CaWO4 intrinsic luminescence up to 40 to 50% with ultraviolet excitation. Further increase of the lanthanide concentration results in quenching of the luminescence. Both effects approach the maxima in the region of the deepest depression in the excitation spectrum of CaWO4 at 12 eV. Lanthanides lead to the increase of CaWO4 phosphorescence. Mechanisms of the phenomena mentioned are discussed.