Swift heavy ion-induced effects in Ce-doped nickel ferrite nanoparticles

Swift heavy ions of various energies are being used for material modifications. The induced modifications depend on the kind of defects produced during interaction of ions with the target material. In the present work, irradiation of 200 MeV Ag beam-induced effects in NiFe2O4 and NiCe0.04Fe1.96O4 nanoparticles are studied at two different fluences, 2 x 10(12) and 1 x 10(13) ions/cm(2). Nanoparticles of nickel ferrite and Ce-doped nickel ferrite were prepared by chemical route. X-ray diffraction pattern shows peaks corresponding to pure spinel structure in both the systems, NiFe2O4 and NiCe0.04Fe1.96O4. The pristine as well as irradiated nanoparticles were characterized by high-resolution transmission electron microscopy ( HRTEM), Raman spectroscopy, electron paramagnetic resonance spectroscopy ( EPR) and vibrating sample magnetometer ( VSM). Raman spectra show bands corresponding to spinel structure. After irradiation, the position of the bands does not change significantly for both samples. The widths corresponding to the same band in both the systems show opposite trend with fluence. VSM results show that after irradiation, the magnetization decreases from 40 to 32 A m(2)/kg for NiFe2O4 and from 39 to 31 A m(2)/kg for NiCe0.04Fe1.96O4. EPR results show that after doping with Ce as well as irradiation, the EPR line width is reduced, making samples important for applications.