Synthesis and luminescence properties of Ho3+/Yb3+ co-doped bismuth tungstate nanopowder.

Ho 3+ /Yb 3+ co-doped Bi 2 WO 6 (Ho 3+ /Yb 3+ -Bi 2 WO 6 ) nanopowders were synthesized by a simple hydrothermal method. Crystal structure, morphology and chemical composition of the samples were characterized by XRD, SEM, TEM and EDS. The effects of some critical synthesis conditions on the upconversion luminescence properties were studied in detail. Under the excitation of 980 nm laser diode, Ho 3+ /Yb 3+ -Bi 2 WO 6 upconversion nanopowder with strongest luminescence intensity was obtained when the concentration of Ho 3+ and Yb 3+ were 1 mol%, 5.0 mol% respectively, and calcined at 600 °C. Moreover, excitation power studies showed that a two-photon process was involved in the upconversion emissions. The probable upconversion luminescence mechanism was discussed according to the energy transfer process. [ABSTRACT FROM AUTHOR]