GB645335A - Improvements in fluorescent lamps - Google Patents

Abstract

645,335. Luminescent glass. SYLVANIA ELECTRIC PRODUCTS, Inc. Sept. 16, 1946, No. 27744. Convention date, Jan. 11, 1944. Drawings to Specification. [Class 56] [Also in Group XL(a)] A cerium activated phosphate glass .for use in a fluorescent discharge lamp is formed according to one method from a raw batch comprising P 2 O 5 , compounds in the form of salts of elements of the first, second, and third groups of the periodic system, which transform into the metal oxides during melting of the raw batch, up to 10 per cent, preferably 2 per cent to 4 per cent, of a cerium salt, e.g. Ce 2 O 3 , CeO 2 , Ce(NO 3 ) 4 , Ce(NO 3 ) 3 , and a reducing agent, such as As 2 O 3 , red phosphorus, aluminium powder or cream of tartar. According to another method the raw batch consists of one or a mixture of several metaphosphates of the metals of the second and third groups of the periodic system, e.g. Zn(PO 3 ) 2 , Ba(PO 3 ) 2 , and Al(PO 3 ) 3 , and cerium salts and reducing agents as in the first method. Preferred mixing proportions of the three metaphosphates are given and vary from 0 per cent to 50 per cent for Zn(PO 3 ) 2 , from 0 per cent to 50 per cent for Ba(PO 3 ) 2 and from 40 per cent to 50 per cent for AL(PO 3 ) 3 . Cerium activated phosphate glasses can be formed having similar proportions of metaphosphates but made from the raw materials according to the first-mentioned method, e.g. starting from P 2 O 5 and either ZnO. BaO, Al 2 O 3 , 2 ZnCO 3 , 3 Zn(OH) 2 or BaCO 3 .