CaO:Bi phosphor powders were successfully synthesized by the sol–gel combustion method. Post heat treatment led to the enrichment of the Ca2+ site with multiple Bi centers. These centers were responsible for the change in the ultra-broadband cathodoluminescence (CL) emission as a function of different electron beam currents/beam voltages. The CaO phase formation and the presence of the enrichment of Bi was confirmed by using the X-ray diffraction and X-ray photoelectron spectroscopy techniques. The thermoluminescence afterglow spectra for the samples annealed at 800 °C and 1200 °C were strongly modified for the CaO and the presence of the multiple Bi centers. Of particular interest was that the ultra-broadband CL may have potential applications in inorganic single-emitting components that produce various colours under different beam currents/beam voltages or in a variety of optical devices if it can be better controlled.
