Nanophosphor LaF3:Ce has been synthesized and incorporated into a matrix to form a nanocomposite
scintillator suitable for application to γ-ray detection. Owing to the small nanocrystallite size (sub-10 nm),
optical emission from the γ / nanophosphor interaction is only weakly Rayleigh scattered (optical attenuation
length exceeds 1 cm for 5-nm crystallites), thus yielding a transparent scintillator. The measured energy
resolution is ca. 16% for 137Cs γ rays, which may be improved by utilizing brighter nanophosphors. Synthesis of
the nanophosphor is achieved via a solution-precipitation method that is inexpensive, amenable to routine
processing, and readily scalable to large volumes. These results demonstrate nanocomposite scintillator proof-of-
principle and provide a framework for further research in this nascent field of scintillator research.
Nanophosphors correspond to nanostructured, inorganic, insulating solid materials that emit light under particle or
electromagnetic excitation. Although extensive investigation of the optical properties of nanostructured semiconductors
is underway, nanophosphors remain largely unexplored. Nanophosphor Tb-doped Y2O3 was obtained by the solution
combustion technique with Tb concentrations up to 5 at.%. Structural characterization, assessed by transmission electron
microscopy and x-ray diffraction, show the existence of nanoparticles with a cubic crystallographic structure and sizes in
the 30 to 70 nm range. As a result of the combustion process, the nanoparticles agglomerate into large micron-sized
entities. Photoluminescence emission and excitation spectra obtained at room temperature show distinct differences in
the optical behavior of the bulk and nanomaterial. Specifically, the excitation spectra of the nanophosphors are
systematically blue-shifted relative to bulk spectra. The photoluminescence emission spectra, which originates from
5D4→7FJ transitions comprising several sharp lines in the visible spectrum, also exhibit contrasting behavior upon Tb
incorporation; the 5D4→7F5,6 intensity ratio decreases with increasing Tb content in the bulk but is constant in the
nanophosphor. Finally, the maximum in the quenching curve of the nanostructured material occurs at 1.5 at %, which is
three times higher than for the bulk material.
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