Effect of 500 keV Ar 2+ ion irradiation on structural and magnetic properties of TiO 2 thin films annealed at 900 °C

Abstract

Present study investigates the structural and magnetic properties of TiO 2 thin films prepared by electron beam evaporation technique, annealed at 900 °C and irradiated with 500 keV Ar 2+ ions. The films before irradiation exhibit anatase phase. Irradiation leads to diffused XRD peaks indicating amorphisation of the anatase phase at the fluence of 1 × 10 14 ions/cm 2 . Increasing the fluence to 5 × 10 16 ions/cm 2 leads to evolution of brookite phase out of the amorphous TiO 2 . In addition, an impurity phase, Ti 4 O 7 is observed in pristine as well as in irradiated films, which show radiation resistant behavior to 500 keV Ar 2+ ion irradiation upto the highest fluence 5 × 10 16 ions/cm 2 . Anatase to brookite phase transformation followed by an intermediate amorphous phase occurs without showing either grain growth or change in film thickness as evidenced from Atomic Force Microscopy (AFM) and Rutherford's Back Scattering (RBS) measurements, respectively. Further, both pristine and irradiated films exhibit ferromagnetic behavior at room temperature (RT) irrespective of their phase and crystallinity. The difference in magnetization observed in pristine and film irradiated at ion fluence 5 × 10 16 ions/cm 2 is ascribed to the difference in oxygen vacancies. © 2018 Elsevier B.V.