Color tunable upconversion luminescence from ex-situ sol-gel derived Titania-Silicate dense glass-ceramic co-doped with Pr-Yb ion pair

Praseodymium–Ytterbium (Pr3+-Yb3+) ion pair co-doped with Silica-Titania dense glass ceramic material was synthesized by novel ex-situ sol-gel method after annealing at ca. 900 °C and investigated for their morphological, structural and luminescence characteristics. Color-tunable upconversion luminescence (UCL) are observed from varying Yb3+ (X mol%; X = 0.0, 0.7, 1.5, 3.0) and fixed Pr3+ (0.7 mol%) ions co-doped ex-situ sol-gel silicate-titania (STPYX) dense glass-ceramic (DGC) materials under 980 nm laser diode pumping source due to the transfer of energy from the Yb3+→ Pr3+ ion. An original ultra-broadband UCL spectra is achieved from the STPYX-DGC materials for excitation photon of wavelength (λex = 980 nm) for varying Yb3+ ion concentration, where the optimized UCL has been observed for material with 1.5 mol% Yb3+ ion concentration. Further, two dimensional spatially resolved photoluminescence intensity distribution study has also been performed using 2D-PL confocal mapping throughout the STPY15-DGC material for a similar excitation source. The color tunability from white to red is evident from the CIE co-ordinate of corresponding UCL spectra of the as-synthesized materials at different activator (Yb3+) ion concentrations. An intense absorption spectrum with peaks assigned to both Pr3+ and Yb3+ ions is also observed for the STPY07-DGC material.