Investigation on the structural and magnetic properties of Co+ implanted rutile TiO2

Crystalline Co nanoparticles in rutile TiO2 were synthesized by 180 keV Co+ ion implantation at 623 K with the fluence of Φ = 4 × 1016 cm−2. The structural and magnetic properties of samples after thermal annealing at different temperatures were characterized by synchrotron radiation X-ray diffraction (SR-XRD), Rutherford backscattering/channeling (RBS/C) and superconducting quantum interference device (SQUID) magnetometer. The SR-XRD results reveal the formation of hcp Co nanoparticles in the as-implanted samples. With increasing annealing temperature, the transition of Co nanoparticles from hcp to fcc is observed. After annealing at 1073 K, the lattice damage is significantly repaired compared with the as-implanted one. The Co nanoparticles forming inside TiO2 are the major contribution of the measured ferromagnetism.