“…The samples in the form of pellets were irradiated at room temperature by Ar 8 þ ion beam at energy of 1.2 MeV for different ion fluences in the range 10 11 -10 15 ions/cm 2 , using Low energy ion beam facility (LEIBF) at the Inter-University Accelerator Center, New Delhi, India. The full details of this set up are given in the paper of Kumar et al [13][14][15]. The pellets were mounted on a ladder target in an air tight chamber; the irradiations were started after attaining vacuum at 1.1 Â 10 À 6 Torr.…”