Dual-mode blue emission, enhanced up-conversion luminescence and paramagnetic properties of ytterbium and thulium-doped Ba2GdF7 multifunctional nanophosphors.

A series of Ba 2 GdF 7 :Yb 3+ , Tm 3+ nanophosphors (NPs) with dual-mode (down-conversion (DC) and upconversion (UC)) luminescence were successfully prepared by hydrothermal method at 180 °C. The NPs have sphere-like morphology and cubic structure. Under the excitation of ultraviolet 355 nm and near-infrared 980 nm, Yb 3+ and Tm 3+ ions co-doped Ba 2 GdF 7 phosphors exhibit bright blue dual-mode emission. The mechanism of UC emissions was determined three-photon absorption. The energy transfer processes from Yb 3+ to Tm 3+ were discussed in detail. The up-conversion luminescence of Ba 2 GdF 7 :Yb 3+ /Tm 3+ nanophosphors were enhanced by introducing the sensitizer Yb 3+ ions and modifying the cetyltrimethylammonium bromide (CTAB) surfactant, respectively. Moreover, the as-prepared samples exhibit paramagnetic properties at room temperature. This type of multifunctional nanophosphors have promising applications in anti-counterfeiting, drug delivery, solid state lasers, biolabels, MRI, light emitting diodes (LEDs). [ABSTRACT FROM AUTHOR]