Annealing temperature dependence of ferromagnetism in Co-doped TiO2 nanofibres

Co-doped TiO2 nanofibres with an average diameter of ∼70 nm were fabricated by electrospinning. The samples were annealed at different temperatures in air and SEM, XRD, VSM, PL were employed to characterize the samples. XRD measurements showed that the nanofibres present anatase and rutile phase at annealing temperature of 420 and 800 °C, respectively. It is found that the ferromagnetic moment of Co-doped TiO2 nanofibres decrease with increasing of annealing temperature. In addition, photoluminescence is different from that of pure TiO2 and the emission due to oxygen vacancies decrease with increasing of annealing temperature, indicating that oxygen vacancies may play an important role for ferromagnetism and F-center-mediated interaction between Co spins may be responsible for the creation of ferromagnetism in Co-doped TiO2 nanofibres.