Enhanced anti-stocks luminescence in LaNbO4:Ln3+ (Ln3+ = Yb3+, Er3+/Ho3+/Tm3+) with abundant color

Lanthanide ion doped up-conversion luminescent (UCL) materials, which have the ability to convert nearinfrared longer wavelength excitation light into shorter wavelength visible light, have recently drawn much attention. Now, a series of Ln(3+) (Yb3+, Er3+/Ho3+/Tm3+) ions doped LaNbO4 (LNO) materials were prepared through a two-step route, including a facile sol-gel process and subsequent combustion. In our work, thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), up-conversion luminescence (UCL), energy level diagram, luminescent lifetimes and corresponding CIE were utilized to characterize the properties. A 980 nm laser was employed to excite Yb3+ ions to achieve the F-2(7/2) -> F-2(5/2) transition, and the LNO: Yb3+, Er3+/Ho3+/Tm3+ samples exhibited intense green, yellowish-green and blue emission, respectively. Luminescent spectra at different powers demonstrated the two-photon absorption process; meanwhile, the corresponding energy transfer mechanisms from Yb3+ to Ln(3+) and the emissions of Ln(3+) under 980 nm laser excitation were described via an energy level diagram. Moreover, multicolor UCL emissions, the optimal intensities and corresponding mechanism were systematically explored via a suite of concentration spectra of different Ln(3+) ions. At last, the decay lifetimes based on the concentration variation of Yb3+ ion demonstrated that the lifetimes are heavily influenced by Yb3+ ion.