Fluorescent Properties of Alkaline Earth Aluminates of the Type MAl[sub 2]O[sub 4] Activated by Divalent Europium

The luminescent characteristics of alkaline earth aluminates activated by divalent europium have been investigated. Ultraviolet excitation of these compounds can occur through the host lattice and from the 4f 7 ground state to excited states of the 4f 7 and 4f 6 5d 1 electronic configurations of divalent europium. The emissions involve 4f‐5d transitions as evidenced by the broadness of the spectra, sensitivity to structure, and sensitivity to temperature. Evidence is also presented that the Eu 2+ occupies cationic‐lattice sites. The performance details of these phosphors in fluorescent lamps are described.