Swift heavy ion irradiation induced modification in structural, optical and luminescence properties of Y2O3:Tb3+ nanophosphor

This paper reports on a comparative study on the structural, optical and luminescence properties of Y2O3:Tb3+ nano-phosphor after 150 MeV Ni7+ and 120 MeV Ag9+ ion beam irradiation at various fluences ranging from 1×1011 to 1×1013 ions/cm2. The modifications in the structural, optical and luminescence properties of the nano-phosphor were studied before and after irradiation by using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis diffuse reflectance (DR) spectroscopy and photoluminescence spectroscopy (PL). The TEM results show the reduction of the particle size from 75 nm to 51 and 18 nm after ion irradiation with the Ni7+ and Ag9+ ions, respectively. The calculations from XRD data suggest that the particles consisted out of smaller crystallites of 64, 43 and 10 nm for the virgin, Ni7+ and Ag9+ irradiated samples, respectively. DR spectra show a blue shift in the absorption band, resulting in an increase in the band gap after ion irradiation. An increase in the intensity of the PL peaks without any shift in the peak positions was observed with the increase in the ion fluence. The relative intensity ratios of the different emissions at 485, 545, 585 and 625 nm due to the characteristic transitions for Tb3+ (5D4→7F6, to 5D4→7F5 5D4→7F4 and 5D4→7F3), however, changed with the ion fluence. The color coordinates of the Y2O3:Tb3+ therefore changed to the deep green light region with the increase in the ion fluence. The magnitude of the effect of the irradiation is greater in the case of the Ag9+ ions than the Ni7+ ions due to the high electronic energy loss of the Ag9+ ions in the nano-phosphors. The results can be correlated on the basis of linear energy transfer of the irradiated ions.