A phosphor comprises, in atomic percentages, 90% to 100% of a mixed metal oxide MxTyOz, wherein M is a metal selected from Zn, Sn, In, Cu, and combinations thereof, T is a refractory metal selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and combinations thereof, and O is Oxygen, x, y, and z being chosen such that z is at most stoichiometric for MxTyOz; and 0% to 10% of a dopant comprising a substance selected from a rare earth element of the lanthanide series, Mn, Cr, and combinations thereof, or stoichiometrically excess zinc, copper, tin, or indium. Cathodoluminescent phosphor compositions stimulable by electrons of very low energy are prepared from metal oxides treated with refractory metals in various processes disclosed. Metal oxides or mixed-metal oxides of zinc, copper, tin, or indium are heated in the presence of a refractory metal such as titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, or combinations or alloys thereof to make phosphors of various chromaticities. In a simple embodiment, a quantity of Ta.sub.2 O.sub.5 is added to a quantity of ZnO and heated at an effective temperature and time to form Ta.sub.2 Zn.sub.3 O.sub.8, which is useful in various forms as a blue-light-emitting phosphor. In preferred embodiments, the phosphors are prepared in situ in an electrically-conductive thin-film or surface-layer form during fabrication of displays.