Long-Lasting Phosphorescence in BaSi[sub 2]O[sub 2]N[sub 2]:Eu[sup 2+] and Ba[sub 2]SiO[sub 4]:Eu[sup 2+] Phases for X-Ray and Cathode Ray Tubes

We report the long-lasting bluish-green phosphorescence for X-ray or cathode ray tubes in the phosphors with compositions of either or synthesized by a solid-state reaction. By tuning the content, the phosphorescence may originate from in (peaking at 490 nm), (505 nm), and (590 nm) phases. The strong phosphorescence of the phase in is attributed to N substitution for O to generate a shallow trap. In , however, N prefers reacting with to form , thereby exhibiting a strong phosphorescence of the phase but a weak phosphorescence of the phase.