Electroluminescent phosphors, electroluminescent panels and lamps made with such phosphors, and a process and apparatus for treating phosphors are disclosed in which the phosphor particles are coated with a very thin coating of SiO.sub.2, to protect the phosphor particles from aging due to moisture intrusion....http://www.google.es/patents/US4961956?utm_source=gb-gplus-sharePatente US4961956 - Electroluminescent lamps and phosphors
