Swift heavy ion induced synthesis and enhanced photoluminescence of SrS:Ce nanoparticles

We report the swift heavy ion induced synthesis and enhanced photoluminescence of SrS:Ce nanoparticles in comparison to the coarser or virgin sample. The coarser samples of SrS:Ce were irradiated with 120 MeV Ni9+ ion beam for fluences in the range of 5 × 1011–5 × 1012 ions/cm2. The swift heavy ion (SHI) induced nanoparticle synthesis has been explained in the light of Coulomb Explosion Model. The X-ray diffraction and selected area electron diffraction confirms no change in rocksalt phase except the loss of crystallinity under the swift heavy ion irradiation. The transmission electron microscopy reveals the near spherical shape of SHI induced nanoparticles having a size of 15–20 nm for a fluence of 5 × 1012 ions/cm2. Reflection spectrum shows a blue shift in the band to band absorption for SHI induced nanoparticles, but the absorption around 427 nm, which may be attributed to the 5d–4f levels of Ce3+, does not show any shift in comparison to the coarser material. Interestingly, we found an increase in the photoluminescence intensity without any blue shift in the emission wavelength for SHI induced SrS:Ce nanoparticles which may be ascribed to stronger quantum confinement for small sized nanoparticles. The enhancement in PL and improved blue/green ratio for swift heavy ion induced nanoparticles may make it a better candidate for practical applications such as in optical devices.