Calcium Halophosphate Phosphors

Abstract

Calcium halophosphates were prepared by firing together calcium chloride and calcium fluoride in various ratios with calcium phosphate containing antimony and manganese as activators, in an electric furnace at 1060°C. for 1 hour. The x‐ray diffraction studies gave patterns very similar to the mineral apatite. Spectral energy distribution measurements indicated that as the chlorine was replaced by equal mole fractions of fluorine, the peak of emission shifted from 5800 Å for all chlorine to 5550 Å when only fluorine was used. Calcium halophosphate activated with antimony alone has a peak of fluorescence at about 4800 Å. As the per centage of manganese is increased up to five per cent, the blue emission is entirely suppressed and a broad peak is obtained at about 5800 Å. The amount of antimony in the phosphor does not appreciably affect the fluorescent color. Excitation measurements of various calcium halophosphates reveal that there are two distinct peaks. A major one is located near 2500 Å and a minor one at 2200 Å. Replacing the chlorine by fluorine tends to shift the major peak toward the longer wavelengths. The effect of manganese seemed to be to enhance the minor excitation peak at 2200 Å. Fluorescent lamps made from this phosphor have been obtained that have outputs and color temperatures comparable to lamps made with zinc beryllium silicate and magnesium tungstate.