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Journal of Physical Studies 22(4), Article 4301 [5 pages] (2018)
DOI: https://doi.org/10.30970/jps.22.4301 LUMINESCENCE PECULIARITIES OF POLYSTYRENE COMPOSITE WITH EMBEDDED YVO4:Eu NANOPARTICLEST. Demkiv, O. Halyatkin, M. Chylii, T. Malyi, V. Vistovsky, L. Bulyk, L. Demkiv, A. Voloshinovskii
Ivan Franko National University of Lviv, |
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8nm and 16 nm YVO4:Eu nanoparticles have been synthesized by the low temperature chemical method and annealed at $T$ = 800$^\circ$C. The nanocomposite films based on scintillation polystyrene loaded with YVO$_4$:Eu (40 wt\%) nanoparticles have been obtained. The luminescence-kinetic characteristics of YVO$_4$:Eu nanoparticles and nanocomposites have been investigated. The luminescence of the polystyrene nanocomposite loaded with YVO$_4$:Eu (40 wt\%) nanoparticles reveals the bands characteristic of the luminescent impurities of p-Terpinil (370 nm), POPOP (420 nm) and of YVO$_4$:Eu nanoparticles ($^5$D$_0 \rightarrow$ $^7$F$_1$ band) at 590 nm, the band $^5$D$_0 \rightarrow$ $^7$F$_2$ at 617 nm, and the weaker $^5$D$_0 \rightarrow$ $^7$F$_3$ (590 nm) and $^5$D$_0 \rightarrow$ $^7$F$_4$ (700 nm) bands. The intensity of X-ray excited luminescence of the polystyrene composites loaded with YVO$_4$:Eu nanoparticles (40 wt\%) increases 3 times. The luminescence decay kinetic of the polystyrene composite in the case of X-ray excitation reproduces the decay kinetic curve of pure polystyrene scintillator with the time constant of $\sim$2.7 ns. The contribution of Eu$^{3+}$ luminescence to the scintillation pulse is insignificant due to the significant decrease of the luminescence intensity of Eu$^{3+}$ centers with decreasing nanoparticle sizes, and the decay time constant of Eu$^{3+}$ luminescence ($\tau=0.8$ ms) is significantly greater than the duration of the main scintillation pulse.
The increase in the detection efficiency of the ionizing radiation by the nanocomposite is caused by the increase in the absorption capacity. The increase in absorption is caused by the presence of heavy inorganic YVO$_4$:Eu nanoparticles compared to the polystyrene matrix without any nanoparticles and by the transfer of excitation energy from embedded nanoparticles to the polystyrene matrix due to the electron escape from YVO$_4$:Eu nanoparticles into the host matrix. The discrepancy between the calculated and observed efficiency detection for the nanocomposite is due to the aggregation of nanoparticles, which prevents the escape of electrons from nanoparticles into the polystyrene matrix.
PACS number(s): 32.50.+d, 78.67.Bf, 81.05.Qk