2 research outputs found
Comprehensive Solid-State Characterization of Rare Earth Fluoride Nanoparticles
The combination of multinuclear solid-state
NMR spectroscopy and
powder X-ray diffraction has been applied to characterize the octahedron-shaped
crystalline nanoparticle products resulting from an inverse micelle
synthesis. Rietveld refinements of the powder X-ray diffraction data
from the nanoparticles revealed their general formula to be (H<sub>3</sub>O)ĀY<sub>3</sub>F<sub>10</sub>Ā·<i>x</i>H<sub>2</sub>O. <sup>1</sup>H magic-angle spinning (MAS) NMR experiments
provided information on sample purity and served as an excellent probe
of the zeolithic incorporation of atmospheric water. <sup>19</sup>F MAS NMR experiments on a series of monodisperse nanoparticle samples
of various sizes yielded spectra featuring three unique <sup>19</sup>F resonances arising from three different fluorine sites within the
(H<sub>3</sub>O)ĀY<sub>3</sub>F<sub>10</sub>Ā·<i>x</i>H<sub>2</sub>O crystal structure. Partial removal of zeolithic water
from the internal cavities and tunnels of the nanoparticles led to
changes in the integrated peak intensities in the <sup>19</sup>F MAS
NMR spectra; the origin of this behavior is discussed in terms of <sup>19</sup>F longitudinal relaxation. <sup>19</sup>Fā<sup>89</sup>Y variable-amplitude cross-polarization (VACP) NMR experiments on
both stationary samples and samples under MAS conditions indicated
that two distinct yttrium environments are present, and on the basis
of the relative peak intensities, the population of one of the two
sites is closely linked to the nanoparticle size. Both <sup>19</sup>F MAS and <sup>19</sup>Fā<sup>89</sup>Y VACP/MAS experiments
indicated small amounts of an impurity present in certain nanoparticles;
these are postulated to be spherical amorphous YF<sub>3</sub> nanoparticles.
We discuss the importance of probing molecular-level structure in
addition to microscopic structure and how the combination of these
characterization methods is crucial for understanding nanoparticle
design, synthesis, and application