Manganese Activated Calcium Silicate Phosphors

Abstract

Single activated CaSiO3·normalMn 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 normalMnO . Complete solid solution of larger amounts of normalMnO is made possible by firing the phosphors in atmospheres of steam and of hydrogen. Single activated CaSiO3·normalPb phosphors produce blue or ultraviolet fluorescence, depending upon the conditions of preparation.Double activated CaSiO3·normalPb·normalMn 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.

A new precipitation based method for preparation of metasilicate phosphors

“…3, curve b). These results are in excellent agreement with those reported by Frolich [30]. CaSiO 3 :Pb and related phosphors have been studied quite early.…”

“…CaSiO 3 activated with Pb and Mn is one of the earliest known, red emitting phosphor [30]. More recent works report luminescence of doubly activated (Eu,Bi) CaSiO 3 [31] and SrSiO 3 [32].…”

The Calcium Silicate Mn + Pb Phosphor Phase Relationships and Preparation

“…In this way, metastable liquids are avoided in the system CaSiO~-MnSiO~-PbSiO~. However, the quaternary solid solution is unstable due to the volatility of lead so that the reaction: fi(Ca,Mn)SiO~ss -F Pb ~ § fl(Ca,Mn,Pb)SiO~ss [1] cannot be expected to be very successful. The alternative reaction: a(Ca,Pb)SiO~ss -F Mn ~*-~ fl(Ca,Mn,Pb)SiO~ss [2] should be more successful due to the greater stability of lead in a(Ca,Pb)SiO.ss than in fi(Ca,Mn,Pb) SiO,ss.…”

“…Attempts to prepare fi(Ca,Mn,Pb)SiO,ss by reaction [1] did not yield high brightness phosphors since it is not possible to incorporate enough Pb in the phosphor to give sufficiently high absorption for 2537A.…”

Developments in Luminescence and Display Materials Over the Last 100 Years as Reflected in Electrochemical Society Publications

“…In 1948, Froelich 11 had reported on a new calcium silicate phosphor, which was later used in many color corrected fluorescence lamps. Smith 12 showed the importance of the atmosphere of firing of ZnS phosphors.…”