Structural, optical and magnetic properties of Cr doped SnO2 nanoparticles stabilized with polyethylene glycol

Pure and Cr (1, 3, 5 and 7 at%) doped SnO₂ nanoparticles were synthesized in aqueous solution by a simple chemical co-precipitation method using polyethylene glycol (PEG) as a stabilizing agent. The effect of Cr doping on the structural, optical and magnetic properties of SnO₂ nanoparticles was investigated. EDAX spectra confirmed the presence of Sn, O and Cr in near stoichiometry. XRD patterns revealed that particles of all samples were crystallized in single phase rutile type tetragonal crystal structure (P4₂/mnm) of SnO₂. The peak positions with Cr concentration shifted to higher 2θ values. Lattice parameters were also decreased with increasing Cr concentration. TEM studies indicated that the particle size is in the range of 8-10 nm. The optical absorption studies indicated that the absorption edge shifted towards lower wavelengths with inclusion of Cr content. FTIR spectrum displays various bands that are due to fundamental overtones of PEG and O-Sn-O entities. Further it revealed that the undoped and as well as Cr doped SnO₂ nanoparticles were capped by PEG. Magnetization measurements at room temperature revealed that all the doped samples were ferromagnetic in nature. Well defined strong room temperature ferromagnetic hysteresis loop was observed for 1% Cr doped SnO₂ nanoparticles.