Upconversion in Nd–Tm–Yb triply doped oxyfluoride glass–ceramics containing CaF2 nanocrystals

Abstract

Upconversion and energy transfer processes in Nd3+–Tm3+–Yb3+ triply doped oxyfluoride glass–ceramics containing CaF2 nanocrystals have been studied. Under 792nm excitation, we investigated the strong blue emission from Tm3+ ions in Tm3+–Yb3+, Tm3+–Nd3+, and Nd3+–Tm3+–Yb3+ doped glass–ceramics. The Nd3+–Tm3+–Yb3+ doped glass–ceramics has shown the strongest blue emission via a multiple-step energy transfer processes following the ground state absorption of Tm3+ and Nd3+ ions. In the Nd3+–Yb3+ doped glass–ceramic, much enhanced visible emission was observed due to the back transfer from Yb3+ ions. However, under 980nm excitation of Yb3+ ions, the triply doped glass–ceramics showed slightly weaker visible upconversion emission than the Tm3+–Yb3+ and Nd3+–Yb3+ co-doped glass–ceramics. Detailed upconversion mechanisms for observed emissions were suggested.