DEPENDENCE OF UV STABILITY OF ALUMINATE PHOSPHORS ON ACTIVATOR CONCENTRATION

Investigations of the changes of luminescent optical properties of Ba1-xEu(x)MgAl10O17 and Ce1-y Tb(y)MgAl11O19 under the influence of ultra-violet radiation (U.V.) in vacuum have shown that the stability of phosphors increases considerably if the concentration of activator ions x, y grows. The results obtained show that there are two causes for the aging process: First, the competitive absorption of exciting radiation by defects and U.V. produced colour centres; and second, the direct interaction of activator ions and colour centres. The influence exercised by both processes is reduced if the concentration x, y increases.