β-NaYF 4 and β-NaYF 4 :Eu 3+ Microstructures: Morphology Control and Tunable Luminescence Properties (original) (raw)

2009, The Journal of Physical Chemistry C

NaYF 4 hexagonal microprisms and microrods with different aspect ratios have been prepared via a simple hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. The influences of reaction temperature and the molar ratio of NaF to Y 3+ on the crystal phases and shapes of final products have been studied in detail. The aspect ratios of products increase gradually with the increase of reaction temperature and NaF/Y 3+ molar ratio. The growth mechanisms of crystals prepared under the different conditions are presented systematically. More importantly, the systematical investigation on the luminescence properties of -NaYF 4 :xEu 3+ (x ) 0.5, 1, 2, 3, 5, and 10 mol %) with hexagonally microprismatic morphology shows the characteristic emissions of Eu 3+ ( 5 D J -7 F J′ , J, J′ ) 0, 1, 2, 3). Under the excitation of single wavelength light of 397 nm, the luminescence colors of the corresponding products can be tuned feasibly from bluish white to yellow to red by changing the doping concentration of Eu 3+ . This merit of multicolor emissions in the visible region endows this kind of materials with potential application in the field of light display systems, lasers, and optoelectronic devices.