Alkali earth aluminate-silicate photoluminescent materials activated by rare earth elements

摘要

Alkali earth aluminate-silicate photoluminescent materials activated by rare earth elements having the composition MO.aAlSB2/SBOSB3/SBbSiOSB2/SBcL:fX in which MO is at least one alkali earth metal oxide selected from strontium oxide, calcium oxide, magnesium oxide and barium oxide, L is a mineraliser and X is a rare earth element activator. Ranges are given for factors a, b, c and f which express the molar amounts of each component relative to one mole of MO. The rare earth element activator may be europium oxide and at least one other rare earth metal oxide. Preferably the activator is a combination of europium oxide and dysprosium oxide. The mineraliser may be an alkali halide, an ammonium halide salt or an ammonium phosphate, particularly ammonium chloride, ammonium bromide or ammonium biphosphate. The materials may be prepared by sintering a mixture of an alkali earth metal carbonate or oxide, aluminium oxide or aluminium hydrate and silica powder, the mineraliser and the activator at 1200 to 1450 {C under a reducing atmosphere to produce a sinter which is then crushed, washed and dried. The photoluminescent materials may be used in the manufacture of luminescent plastics, rubbers, coatings and ceramic glazes.