| 摘要 |
701,754. Luminescent materials. PATENTTREUHAND-GES. FUR ELEKTRISCHE GLUHLAMPEN. June 7, 1951 [June 21, 1950], No. 13562/51. Drawings to Specification. Class 39(1) A luminescent material, to be excited alone or mixed with other luminescent materials by ultraviolet rays, X-rays or cathode rays, particularly for electric discharge lamps, e.g. low-pressure mercury fluorescent tubes having the luminescent material associated with their inner walls, consists solely of calcium-strontium-silicate activated with lead and manganese. The material is prepared by mixing calcium carbonate, strontium carbonate and silica in mol ratios of 0.99-0.85: 0.01-0.15: 0.75-1.25, adding 1-3 per cent by weight of lead and of manganese e.g. in the form of lead oxide and manganese carbonate and heating the mixture several times at 1100-1300‹C in water vapour at a partial pressure of some 100 mm. The material is milled and sifted between the several heat treatments and may finally have a grain distribution having a maximum of 4Á, with 58 per cent of the grains having a size smaller than. 4Á and no grain being greater than 10Á. The halogenides or nitrates of calcium and strontium may be used. The emission maximum of the silicate may be shifted towards the long ultra-red wavelengths in the region of 650 mÁ, where Á=6080Š, by increasing the percentage of strontium. |
