Morphology/phase controllable synthesis of monodisperse ScVO4 microcrystals and tunable multicolor luminescence properties in Sc(La)VO4(PO4):Bi3+,Ln3+ phosphors†
Abstract
A facile one-pot hydrothermal approach was employed to prepare novel chocolate-like ScVO4 microcrystals using polyethylene glycol as an additive. XRD, SEM, and PL were used to characterize the structures, morphologies and luminescence properties of samples, respectively. Four different types of ScVO4 microcrystals including regular dodecahedral, truncated octahedral, chocolate-like and compressed chocolate-like structures could be obtained by varying the amount of polyethylene glycol. The possible formation mechanism of the chocolate-like ScVO4 microcrystals could be attributed to the nucleation–dissolution–recrystallization process on the basis of a series of time-dependent control experiments. As good matrix materials, the tunable multicolor luminescence of ScVO4:Ln3+ (Ln = Sm, Eu, Dy, Ho, Er, Tm, Yb/Er, Yb/Ho, Yb/Tm) was achieved. Most importantly, doping La3+ or PO43− into the ScVO4 host can form mixed crystals and increasing the La3+ or PO43− concentration will induce the phase transition from tetragonal to monoclinic lattices. We further found that the luminous intensity of phosphors with a tetragonal structure was higher than that of phosphors with a monoclinic structure in LaxSc1−xVO4:0.1%Eu3+ and Sc(VO4)1−x(PO4)x:0.1%Eu3+, respectively. In addition, the modulation of the electronic band gap through doping Bi3+ ions into the host lattice would result in a blue-shift of the photoluminescence spectrum for the Sc(VO4)1−x(PO4)x:1%Bi3+ phosphor, which provides a new path toward tunable phosphors.