NOVEL LONG DECAY PHOSPHORS

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PROBLEM TO BE SOLVED : To provide long decay phosphors and methods for producing them. SOLUTION : The phosphors comprise a matrix of the formula Sr4Al14O25 comprising europium as an activator and a further rare earth element as a co-activator, where the Al/Sr ratio in the starting materials is in the range from 3.1 to less than 3.5 and the Eu/Sr ratio is in the range from 0.0015 to 0.01. The methods for producing of the phosphors comprise the steps of milling the starting materials comprising a boron compound selected from boric acid, boron oxide and borate salts in an amount such that the B/Sr molar ratio is between 0.1 and 0.3, treating the milled composition with heat, grinding the block material which is obtained through the heat treatment, ball-milling the crushed material, sieving the material, and washing the material with an aqueous solution. SELECTED DRAWING : None COPYRIGHT : (C)2018, JPO&INPIT