Long afterglow from multi dopant transparent and opaque glass ceramic phosphor for white, red, yellow, and blue emissions: Zn2SiO4:Eu3+, Dy3+, Mn2+

In this paper, preparation of long afterglow phosphor with different emission colors in the system Zn2SiO4:Eu3+, Dy3+, Mn2+ was done via melt-quenching technique. The effect of adding mono-di- and tri-dopant on the phosphorescence properties was studied. Also, the effect of applying different heat treatment programs on the appearance of glass-ceramic (GC) to get transparent or opaque materials were optimized. DTA, XRD, SEM, UV–visible - NIR, and fluorescence spectrophotometer were used to characterize the obtained materials. The results revealed crystallization of willemite and zinc borate; both Mn and Dy addition enhanced the degree of crystallization while Eu depressed it. Heat treatment at 650 °C/5 h revealed transparent glass-ceramic (TGC), above this temperature opaque glass-ceramic was appeared. Calculation of optical band gap (Eopt), Urbagh energy (∆E) and refractive index were located in the range: 2.1–2.8 eV, 0.53–0.79 eV and 2.45–2.64 respectively. Lifetime decay was increased by increasing heat treatment temperature; it reaches ~2 h after irradiation at 260 nm for 30 min giving green emission at 558 nm. Visual appearance for the emitting light varies from white, red, yellow to blue color.