Manganese Activated Calcium Silicate Phosphors

Single activated CaSiO 3 · Mn phosphors absorb very little Λ 2537 radiation and, consequently, do not fluoresce appreciably when so excited. Under cathode ray excitation the emission is strong and is made up of two bands, one peaking at 5600 Å, the other at 6200 Å, the longer of the two becoming more prominent at higher concentrations of MnO . Complete solid solution of larger amounts of MnO is made possible by firing the phosphors in atmospheres of steam and of hydrogen. Single activated CaSiO 3 · Pb phosphors produce blue or ultraviolet fluorescence, depending upon the conditions of preparation. Double activated CaSiO 3 · Pb · Mn phosphors, preferably prepared by steam firing, provide acceptable substitutes for ZnBeSilicate phosphors. They emit both visible light and useful ultraviolet when excited by X 2537. Their sensitivity, efficiency, and color make them useful for application in fluorescent lamps. They show exceptionally bright second stage phosphorescence, and remarkable temperature stability. In order to explain the mechanism of light production in double activated phosphors, internal optical excitation and paired Pb‐Mn centers are ruled out, and a mechanism first proposed by Rothschild is tentatively accepted.