A number of recent researches have been concerned with magnesium germanate phosphors. An improved such phosphor is reported here having over twice the brightness of the previous compositions as prepared in this laboratory, and which shows peak luminescence efficiency at temperatures near 350°C. Temperature dependence of luminescence studies on the improved composition and the others showed little difference between them in this respect though the data are in striking contrast with those reported by others. A partial explanation of the pronounced temperature effect (for temperatures <350°C) is presented and is based upon the broadening of the excitation spectrum at elevated temperatures in such a way as to increase absorption of the exciting radiation (3650A). Data are presented showing differences in the temperature dependence relation effected by wave-length of excitation and method of measurement; in addition, curves are included showing the variation of phosphorescence (t=1/120 sec.) with temperature as well as curves showing excitation and emission characteristics of the phosphor. Finally a practical application of this high temperature luminescence is demonstrated in the color corrected high pressure mercury lamps the emission characteristics of which are briefly discussed.
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