Carbon doping of Ti0.91Co0.03La0.06O2 nanoparticles for enhancing room-temperature ferromagnetism using carboxymethyl cellulose as carbon source

Abstract

The enhanced room temperature ferromagnetism (RTFM) as well as its mechanism in the C-doped Ti0.91Co0.03La0.06O2 nanoparticles using carboxymethyl cellulose (CMC) as the C source are reported. The samples were synthesized by a two-step sol-gel route and characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, and magnetic measurement techniques, respectively. The results support the uniform incorporation of C atoms into the anatase Ti0.91Co0.03La0.06O2 lattice and the associated remarkable RTFM as a result of C doping. Both interstitial C (Ci) and the substitutional C for Ti sites (CTi) in the C-doped samples were identified based on the XPS results. The variation tendency of saturation magnetization (Ms) is in accordance with that of the concentration of CTi i.e. the C˭O units content in the Ti0.91Co0.03La0.06O2 lattice. Furthermore, the RTFM is enhanced by the superposition effect of the ferromagnetic exchange coupling between Co2+ ions in the host and the ferromagnetic p-p coupling interactions between C 2p and O 2p states of the C˭O units in the C-doped Ti0.91Co0.03La0.06O2 nanoparticles.