The effect of additional doping with Nb, Al or Cu on ferromagnetism and conductivity in V-doped TiO 2 powders

Abstract

Rutile Ti 0.94V 0.06O 2 and Ti 0.93V 0.06M 0.01O 2 (M=Nb, Al, and Cu) polycrystalline powders are synthesized by the standard solid-state reaction method. The room-temperature saturation magnetization and resistivity of Ti 0.94V 0.06O 2 powders are 2.5×10 −3 emu/g (≈0.60×10 −3 μ B/V) and above 10 7 Ω cm, respectively. The ferromagnetism weakens remarkably, and the conductivity enhances after additional doping with Nb or Al in V-doped rutile TiO 2 powders. The room-temperature magnetization and resistivity of Ti 0.93V 0.06Cu 0.01O 2 powders are 2.1×10 −3 emu/g and 1.26×10 6 Ω cm, respectively. Based on analysis for chemical valence of dopants by the x-ray photoelectron spectroscopy spectra, and using the bound magnetic polaron model, the microscopic mechanisms of ferromagnetism in V-doped rutile TiO 2 powders with or without additional dopants are discussed in detail.