NOVEL LONG DECAY PHOSPHOR

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PROBLEM TO BE SOLVED : To provide long decay phosphors comprising rare earth-activated strontium aluminates, and methods for producing them.SOLUTION : Phosphors comprise a matrix of the formula, SrAlOcomprising europium as an activator and a further rare earth element as a co-activator. The molar ratio of Al/Sr in the starting materials is in the range of 3.1 to less than 3.5, and the ratio of Eu/Sr is in the range of 0.0015 to 0.01. A method for production of the phosphor comprises the steps of : milling the starting materials for synthesis of the phosphor, which includes a boron compound selected from boric acid, boric oxide or borates in an amount such that the B/Sr molar ratio is between 0.1 to 0.3; heat-treating the milled composition; grinding the block material obtained through the heat treatment; ball-milling the ground material; sieving the material; and washing the material with an aqueous solution.