Activation by Anions in the Oxy-Acid Phosphors

Abstract

The luminescence of alkaline earth sulfates and silicates activated by anions, has been observed. The activating anions were , , , , , , , , , , , S2−, and . The products showed fluorescent emissions varying in color from blue to red and in visible intensity from very faint to strong. The samples showing the strongest emission are: and , both emitting in the blue. Evidence is presented to show that these phosphors are truly activated by the ion, and not simply dilute samples of the tungstates. It is proposed that activation by anions can be divided into two classes: intraionic, where the emission occurs within the impurity anion; and interionic, where more complex interactions occur. The latter class shows strong shifts in emission color as the host crystal is changed; the intraionic group, including tungstate and vanadate, generally show stronger emission than the others.