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 4f7 ground state to excited states of the 4f7 and 4f65d1 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 Eu2+ occupies cationic‐lattice sites. The performance details of these phosphors in fluorescent lamps are described.

No abstract

The adoption of YVO4:normalEu as a new red ‐emitting primary in color television has stimulated investigation of a new class of phosphors obtained by appropriate substitutions in YVO4:normalEu . Substitution of Y3+ by Gd3+ and Lu3+ provides equally efficient hosts for Eu3 + with no significant spectral differences. Substitution of Y3+ by La3+ leads to a less efficient host with important differences in the emission characteristics of Eu3+. Use of rare earth activators ether than Eu3+ provides a series of phosphors which emit over most of the visible range. Spectral data and preferred concentration ranges are presented as well as the effect of temperature on the fluorescent emission intensities.

VOLUME 2 8, NO. 4, APRIL 1956 459 acteristio lines to be counted, and absorption effects in three regions to consider. The three counts should, however, contain enough information in many cases to permit the drawing of valid conclusions.

2, jV. Y.The peroxy complexes of group IV, V, VI, and VII transition elements, formed in concentrated sulfuric acid media, were investigated for application to the analysis of niobia and tantala mixtures.(A number of correlations were made of the spectra of the peroxy complexes with their positions in the periodic table .) One result of this study was the discovery of a peroxy-tantalate whose absorption spectrum had its peak at 285 mg.