Effect of 120 MeV Ag9+ ion beam irradiation on the structure and photoluminescence of SrS:Ce nanostructures

The effect of 120 MeV Ag9+ ions irradiation on the structure and photoluminescence of SrS:Ce nanostructures for the ion fluences 5×1011, 5×1012 and 1×1013 ions/cm2 has been investigated. X-ray diffraction confirms no change in cubic phase of swift heavy ion (SHI) irradiated samples. The crystallinity improves initially with the ion irradiation; however it deteriorates for the fluence 1×1013 ions/cm2. This may be attributed to the grain growth for initial fluences and then grain fragmentation for the highest fluence as confirmed by using the Debye Scherer’s relation. Transmission electron microscopy (TEM) confirms the change in whisker morphology of pristine sample to the non-uniform sized agglomerated particles. We observed an increase in PL intensity with the increase of ion fluence up to 5×1012 ions/cm2, however, further increase of ion fluence decreases the PL intensity, which may be attributed to the decrease in the crystallinity as confirmed by XRD. No shift in PL emission wavelength has been noticed for swift heavy ion (SHI) irradiated samples. The optimised concentration of Ce in SrS for maximum PL has been found to be 0.5 mol%. The results of excitation spectroscopy were also found to be consistent with the PL emission spectroscopy.