Tunable multicolor and bright white emission of one-dimensional NaLuF4:Yb~(3+),Ln~(3+) (Ln = Er, Tm, Ho, Er/Tm, Tm/Ho) microstructures

摘要

Well-defined one-dimensional NaLuF4:Yb~(3+),Er~(3+)/Tm~(3+)/Ho~(3+) microtubes and microrods were successfully prepared by a surfactant-free molten salt method for the first time. It is found that with the prolonged time, the phase of NaLuF4 transforms from cubic to hexagonal, while the morphology changes from nanoparticles to microtubes then to microrods. Moreover, upon 980 nm laser diode (LD) excitation, white up-conversion (UC) light was successfully achieved by properly tuning the sensitizer (Yb~(3+)) concentration in the host matrix. The relative emission intensities of different emission colors in Yb~(3+)/Er~(3+), Yb~(3+)/Tm~(3+), and Yb~(3+)/Ho~(3+) doped β-NaLuF4 can be precisely adjusted in a broad range by tuning the Yb~(3+) doping concentration. Consequently, effective UC emissions with multicolors and a strong white light can be realized in β-NaLuF4:Yb~(3+)/Er~(3+)/Tm~(3+), and β-NaLuF4:Yb~(3+)/Tm~(3+)/Ho~(3+) structures by the appropriate control of the emission intensity balance for the three blue, green, and red basic colors. UC mechanisms in the co-doping and tri-doping β-NaLuF4 samples were analyzed in detail based on the emission spectra and the plot of luminescence intensity to pump power. The as-obtained abundant luminescence colors in a much wide region contribute themselves great potential applications in various fields. Furthermore, the paper also provides an effective and facile approach to gain a desired color by manipulating the sensitizer concentration.