Preparation and upconversion luminescence of Er3+/Yb3+ codoped Y2Ti2O7 nanocrystals

Abstract: Er3+/Yb3+ codoped pyrochlore-type (Y0.99-xEr0.01Ybx)2Ti2O7 (x=0, 2.5, 5.0, 7.5, 10.0 and 12.5mol%) nanocrystals have been successfully prepared by the sol–gel process with citric acid as chelator. The samples annealed at 800°C for 1h exhibit good crystallinity and narrow size distribution with average size of 20–30nm. Upon 980nm excitation at room temperature, green (at~525 and 545nm) and red (at~660nm) upconversion emissions were observed, which are ascribed to the (2H11/2, 4S3/2)→ 4I15/2 and 4 F9/2 → 4I15/2 transitions, respectively. And also, it has been found that the annealing temperatures and the Yb3+ ion doping concentrations have greatly influenced on the upconversion luminescence intensity. The results show that Y2Ti2O7 is an excellent host material for efficient upconversion nanophosphors. [Copyright &y& Elsevier]