GB930818A - Improvements in or relating to luminescent materials and radiation sources comprising the same - Google Patents

Abstract

930,818. Luminescent materials. PHILIPS ELECTRICAL INDUSTRIES Ltd. Sept. 19, 1961 [Sept. 22, 1960], No. 33499/61. Class 39 (1). A luminescent substance which is activated with monovalent copper with or without also bivalent manganese is represented by the formula: where A represents at least one of the alkaline earth metals calcium, strontium and barium and B represents at least one of the alkali metals lithium, sodium and potassium, which substance satisfies the following conditions: In a specific example, 46.9 gms. of SrHPO 4 , 11.62 gms. of Li 2 CO 3 , 0.36 gm. of CuSO 4 .5H 2 O, 0.55 gm. of MnNH 4 PO 4 , 0.58 gm. of Al 2 O 3 , and 4.14 gms. of (NH 4 ) 2 HPO 4 were mixed and heated in a furnace to a temperature of 1000‹ C. in air for 1 hour. The resulting product was pulverized and heated again to 750‹ C. in a stream of nitrogen and hydrogen for 1.5 hours, the resulting product satisfying the conditions a=3.05, b=1.64, c=0.005, d=0.02, e=0.04. In some other examples, only one heating step is used, viz. heating at a temperature of 1100‹ C. in a stream of nitrogen and hydrogen for 1 hour. The emission curves from 10 specific examples of the luminescent substance are shown with excitation by radiation of 253.7 mÁ wavelength, for example from a lowpressure mercury vapour discharge lamp. If copper is the sole activator a peak between 350-520 mÁ is obtained, with manganese present a second peak is obtained between 600-700 mÁ, and the addition of aluminium is stated to increase the light output.