Tb3+-doped Sr-3(PO4)(2) phosphor was prepared by a sol-gel combustion method. A trigonal structure having Sr and O atoms occupying two different lattice sites were obtained. Scanning Auger nanoprobe was used to analyze the morphology of the particles. Photoluminescence (PL) and cathodoluminescence (CL) properties of Sr-3(PO4)(2):Tb powder phosphors were evaluated and compared. In addition, the CL intensity degradation of Sr-3(PO4)(2):Tb was evaluated when the powders were irradiated with a beam of electrons in a vacuum chamber maintained at an O-2 pressure of 1 x 10(-6) Torr or a background pressure of 1 x 10(-8) Torr O-2. The surface chemical composition of the degraded powders, analyzed by X-ray photoelectron spectroscopy (XPS), suggests that new compounds (metal oxides) of strontium and phosphorous were formed on the surface. It is most likely that these compounds contributed to the CL intensity degradation of the Sr-3(PO4)(2): Tb phosphors. The CL properties and possible mechanism by which the new metal oxides were formed on the surface due to a prolonged electron beam irradiation are discussed. (C) 2011 Elsevier B.V. All rights reserved.