Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Patent
1994-09-14
1995-12-05
Bonner, C. Melissa
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
423331, C09K 1159
Patent
active
054726360
ABSTRACT:
A process for producing a manganese and lead activated calcium metasilicate phosphor having the nominal formula CaSiO.sub.3 :MN:Pb. The process involves preparing a uniform aqueous dispersion of fumed silica having an ultrafine average particle size of less than 50 nm, a calcium precursor, a manganese precursor, and a lead precursor. Preferably, the calcium, manganese, and lead precursors are added as powders to an aqueous dispersion of said ultrafine fumed silica. The ultrafine fumed silica aqueous dispersion is heated to a temperature of about 50.degree.-90.degree. C. and the powders are mechanically dispersed in the fumed silica aqueous dispersion to form the uniform aqueous dispersion. The molar ratio of calcium:silicon in the mixture is approximately stoichiometric to 1.3:1; and the molar ratios of manganese and lead in the dispersion are sufficient to activate the phosphor. The precipitate from the dispersion is calcined at a temperature of about 1050.degree.-1135.degree. C. for a time sufficient to form a manganese and lead activated calcium silicate phosphor having a peak emission in the red region of the visible spectrum when stimulated by external radiation at approximately 254 nm. The phosphor product has an average primary particle size of less than 5 .mu.m and a brightness at least equivalent to that of commercially available manganese and lead activated calcium silicate phosphors.
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Forster Cheryl M.
Kasenga Anthony F.
Bonner C. Melissa
Clark Robert F.
Osram Sylvania Inc.
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