The reduction in cathodoluminescent (CL) degradation of ZnS:Ag phosphor particles coated with aluminum doped zinc oxide (ZAO) films has been investigated. The films were deposited under various oxygen pressures using the atomic flux coating process. The characteristics of the coated phosphor particles with respect to as-received ones were investigated by x-ray photoelectron spectroscopy, CL degradation and scanning electron microscopy. All coated phosphor particles exhibited less CL degradation than the uncoated particles. The coatings deposited under 1.6×10-4 Torr of oxygen, a pressure much lower than the optimum one required to obtain highly transparent and conductive ZnO:Al films, provided the longest brightness lifetime. This increased phosphors lifetime was attributed to the high reactivity of the oxygen deficient ZAO coatings which acted as a sacrificial layer and trapped reactive species before they can reach the phosphor particles and alter their chemical composition.