Effect of swift heavy ion irradiation on structural, optical and luminescence properties of SrAl₂O₄: Eu²⁺, Dy³⁺ nanophosphor

The effect of energy deposition by swift heavy ion (SHI) irradiation on the structural, optical and luminescence properties of the SrAl₂O₄:Eu²⁺, Dy³⁺ nanophosphor synthesized by a combustion method has been presented. The samples were irradiated with 120MeV Ag⁹⁺ SHIs at fluences in the range of 1×10¹²ionscm^-2 to 1×10¹³ionscm^-2. The X-ray diffraction results revealed that the obtained powder corresponds to the monoclinic-phase with space group P2₁ and the results also indicate that the SHI irradiation did not cause any change in the crystal structure of the phosphor. However, a decrease in the crystallinity was observed. Under 330nm excitation, the PL emission spectra show a broad band centered at 516nm which corresponds to the 4f⁶5d→4f⁷(⁸S_7/2) transition of the Eu²⁺ ion. The PL intensity of the phosphors was found to decrease with an increase in the ion fluences, which may be due to the enhancement in the non-radiative recombination via additional deep level traps introduced by the SHI irradiation. SHI irradiation enhanced the phosphorescence life time of the phosphors. After SHI irradiation, a blue shift in the diffuse reflectance spectra was observed. The thermoluminescent (TL) glow curve of the SHI irradiated phosphors showed a broadband with a shift in the peak position from 375K to 391K with an increase in the ion fluence. Also, the TL intensity has increased with an increase in the ion fluences.