COATED PHOSPHORS

摘要

A process for preparing phosphor particles of a doped host oxide is described which comprises: preparing an aqueous solution of oxides of the host ion and of the dopant ion with sufficient strong acid to provide a pH less than 0.5, increasing the pH of the solution by the addition of a base comprising a Group 1A metal while maintaining the oxides in solution, adding a water soluble compound which decomposes under the reaction conditions to convert the material into hydroxy carbonate, heating the solution so as to cause said compound to decompose, recovering the resulting precipitate and calcining it at a temperature which is at least 500 DEG C.