Luminescence and electron degradation properties of Bi doped CaO phosphor

Ca _1-x O:Bi _x=0.5% phosphor powder was successfully synthesized by the sol-gel combustion method. The structure, morphology and luminescent properties of the phosphor were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence and cathodoluminescence (CL) spectroscopy. The results showed that the Ca _1-x O:Bi _x=0.5% consisted of single face-centred cubic crystals and that the phosphor particles were uniformly distributed. When the phosphor was excited by a xenon lamp at 355 nm, or a 325 nm He-Cd laser, or electron beam, it emitted strongly in the blue near-UV range with a wavelength of 395 nm ( ³ P ₁ → ¹ S ₀ transition of Bi ³⁺ ). The CL intensity was monitored as a function of the accelerating voltage and also as a function of the beam current. The powder was also subjected to a prolonged electron beam irradiation to study the electron beam induced CL intensity degradation. X-ray photoelectron spectroscopy was used to analyze the Ca _1-x O:Bi _x=0.5% phosphor sample surface before and after degradation.