Method for the preparation of a phosphor by firing a mixture of the raw materials of the phosphor, wherein prior to firing said mixture the following steps are carried out :
(I) mixing the raw materials of the phosphor in an aqueous medium in finely divided state while at least one of said materials is present as a sol, (II) transforming the sol into a gel while it is intimately mixed with the other finely divided raw materials, and (III) drying the gel to form a xerogel.