| Abstract
| - β-NaYF4 microcrystals with a variety of morphologies, such as microrod, hexagonal microprism, andoctadecahedron, have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanningelectron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electronmicroscopy (HRTEM), and photoluminescence (PL) spectra were used to characterize the samples. Theintrinsic structural feature of β-NaYF4 seeds and two important external factors, namely, the pH valuesin the initial reaction solution and fluoride sources, are responsible for shape determination of β-NaYF4microcrystals. It is found that the organic additive trisodium citrate (Cit3-) as a shape modifier has thedynamic effect by adjusting the growth rate of different facets under different experimental conditions,resulting in the formation of the anisotropic geometries of various β-NaYF4 microcrystals. The possibleformation mechanisms for products with various architectures have been presented. A systematic studyon the photoluminescence of Tb3+-doped β-NaYF4 samples with rod, prism, and octadecahedral shapeshas shown that the optical properties of these phosphors are strongly dependent on their morphologiesand sizes. This synthetic methodology appears to be general and promises to provide a gateway intoother rare earth fluoride compounds.
- β-NaYF4 micorcystals with a variety of morphologies, such as microrod, hexagonal microprism, and octadecahedron, have been synthesized via a hydrothermal route. The intrinsic structural feature of β-NaYF4 seeds and two important external factors, namely, the pH values in the initial reaction solution and fluoride sources, are responsible for shape determination of β-NaYF4 microparticles. The possible formation mechanisms for products with various architectures have been presented. A systematic study on the photoluminescence of Tb3+-doped β-NaYF4 samples with rod, prism, and octadecahedral shapes has shown that the optical properties of these phosphors are strongly dependent on their morphologies and sizes.
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