Hydrothermal synthesis of ScVO4:Ln3+ (Ln = Eu, Dy, Eu/Dy) microcrystals with controllable morphology, energy transfer and multicolor luminescence

ScVO4:Ln3+ (Ln = Eu, Dy, Eu/Dy) were prepared by hydrothermal method without employing any organic additives. X-ray diffraction (XRD), scanning electron microscopy (SEM) and down-conversion (DC) spectra were used to characterize the phase, morphology and luminescence of the obtained samples, respectively. The effect of pH value and reaction time on the morphologies (including dodecahedrons, olive tetrahedrons, rectangular blocks and micrometer rods) and sizes of ScVO4 were studied in detail. Additionally, the possible formation mechanism of ScVO4 dodecahedral was considered as a dissolution recrystallization process. Under UV excitation, the red emission of ScVO4: Eu3+ at 622 nm from the 5D0-7F2 transition and the blue and yellow emissions of ScVO4:Dy3+ microcrystals at 484/579 nm assigned to the 4F9/2 - 6H15/2 and 4F9/2 - 6H13/2 transitions were observed. Multicolor emissions (blue → yellow → white → orange → red) of ScVO4: Eu3+/Dy3+ phosphors can be flexibly adjusted through controlling the ratio of Dy3+ to Eu3+ concentration under optimal excitation of 282 nm. And multicolor luminescence can also be obtained via adjusting the excitation wavelength at a constant doping concentration. The as-synthesized phosphors might be potentially applied in display devices, decorative lights and illuminations.