Upconversion luminescence of Yb3+/Tb3+/Er3+-doped fluorosilicate glass ceramics containing SrF2 nanocrystals

Yb3+/Tb3+/Er3+-doped transparent alkaline earth fluorosilicate glass ceramics containing SrF2 nanocrystals were prepared and their microstructures and spectroscopic properties were investigated. The formation of SrF2 nanocrystals enriched with Yb3+/Tb3+/Er3+ in the glass ceramics was confirmed by XRD, HRTEM and SAED. The glass ceramics exhibited intense upconversion luminescence behaviors, owing to efficient energy transfers from Yb3+ to Er3+ and Tb3+ and low phonon assistant non-radiative transition probabilities of excited Er3+ and Tb3+. The upconversion could be enhanced significantly by increasing the annealing temperature and the luminescence color could be adjusted by varying the Yb3+/Tb3+/Er3+ ratio. Upconversion of Er3+ could be described as sequential energy transfer from single Yb3+ to single Er3+, while upconversion of Tb3+ described as cooperative energy transfer from double Yb3+ to single Tb3+.

Research highlights
► We prepared Yb3+/Tb3+/Er3+-doped glass ceramics containing SrF2 nanocrystals.
► Adjusting the doping ratio will induce multicolor upconversion luminescence of the glass ceramics.
► Increasing the annealing temperature will enhance the upconversion intensity.
► The upconversion mechanisms are described as cooperative energy transfers from Yb3+ to Tb3+/Er3+.
► So the glass ceramics have potential application in the color display and white light emitting devices.