Three systems such as CaS, BaS and ZnS are used as greund matarials and transition elements such as Bi, Cu, Ag and Ni are used as activators to prepare phosphorescent materials of strong after-grow intensity.
These three systems in which we have 31 kinds of different composition samples are heated at given temperatures in ihe electrical furnace and are cooled in the air in order to crystallize them.
In the case of BaS system, the mixture of CaO and purified S is better than the other kinds of calcium compound as the ground meterials to crystallize phosphors.
In BaS system, the mixture of BaCO_(3) and purified S, in ZnS system ZnS respectively is the most proper ground material to prepare such a strong after-grow intensifled phosphors.
In a given ranae, the higher in temperature and the longer time of heating, the better phosphors we pbtain. (Recived December 30, 1962)
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