GB675122A - Improvements in or relating to fluorescent materials - Google Patents

Abstract

675,122. Luminescent materials. EKCOENSIGN ELECTRIC, Ltd., EVANS, J. N. I., and HEWSON, W. A. Dec. 29, 1950 [Dec. 30, 1949], No. 33295/49. Class 39 (i). In the preparation of fluorescent calcium halo-phosphate, the formation of hydroxyapatite is precluded by the selection of suitable ingredients and conditions. One method comprises heating together calcium pyrophosphate, manganese phosphate or carbonate, antimony oxide, calcium fluoride, calcium carbonate and ammonium chloride with or without aluminium oxide in proportions calculated to give a structure R 5 (PO 4 )X where R is calcium, partially substituted by a manganese and aluminium and X is fluorine and/or chlorine. The antimony oxide is linked in the crystal lattice. The inclusion of a small amount of manganese gives a blue fluorescence whereas 0.55 mols. of MnO to 3 mols. of P 2 O 5 gives a red fluorescence with less manganese; the fluorescent colour is a warm white. For 3 mols. of P 2 O 5 the corresponding quantities of other additions are Al 2 O 3 0.32 mols, Sb 2 O 3 0.13 mols., CaF 2 0.7 mols. and NH 4 Cl 0.5 mols. The materials are milled together before the addition of the ammonium chloride. An average particle size as high as 10 microns being instanced. Ammonium chloride is omitted if a green fluorescence is required. The material is suitable for coating the interior surfaces of lamps.