Orange‐ and Violet‐Emitting Long‐Lasting Phosphors

Orange phosphorescence from Eu 3+ ‐activated CaO and SrO and violet phosphorescence from Pb 2+ ‐activated SrO were clearly observed after the materials had been excited with ultraviolet light. The orange phosphorescence resulted from 5 D 0 to 7 F 1 transitions of the Eu 3+ ions and the violet from 3 P 0 to 1 S 0 transitions of the Pb 2+ ions. The phosphorescence lasted >1 h. Trapped‐electron centers and hole centers introduced into the CaO and SrO hosts by the ultraviolet light appear to have been responsible for generating the long‐lasting phosphorescence.