| abstract |
An alkali earth aluminate-silicate photoluminescent pigment which is actvated by rare-earth elements according to the invention has excellent luminescent properties such as high initial intensity and long afterglow time. The pigment may readily be used in the manufacture of luminescent plastics, rubbers, coatings and ceramic glazes because it appears neutral in aqueous medium and the sinters are easily crushed into powder. The pigment has the composition formula of MO.aA12O3bSiO2cL: fX, in which MO is represented by at least one oxide selected from alkali earth metals such as SrO, CaO and MgO; L is a mineraliser selected from minerals, X is an activator selected from rare-earth elements; and a, b, c and f are variable factors having values in mole. The pigment is produced by firing selected ingredient materials in a controlled environment of a reduced atmosphere, filled with selected gases or elements, at a temperature of 1200 - 1450° C for 2-4 hours to produce a sinter; and the sinter is finally produced into photoluminescent pigments. |