Influence of Co co-doping on structural, optical and magnetic properties of SnO2:Cr nanoparticles

• We are the first to report on Cr and Co co-doped SnO2 DMS nanoparticles.
• Structural, bandgap and magnetic studies were carried out.
• Tunable bandgap with Co co-doping concentration was noticed.
• Effect of Co co-doping concentration on magnetic properties of SnO2:Cr was studied.
• SnO2:(Cr, Co) nanoparticles may find applications in spintronic devices.

We are the first to report a systematic study on the structural, optical and magnetic properties of chromium and cobalt co-doped SnO2 nanoparticles synthesized by the simple co-precipitation method using polyethylene glycol (PEG) as capping agent. EDAX spectra confirmed the presence of Sn, O, Cr and Co elements in the samples with near stoichiometry. X-ray diffraction studies revealed that all the samples were in single phase rutile type tetragonal crystalline structure. Peak broadening analysis was used to evaluate the average crystallite size and lattice strain using Scherer’s equation and Williamson–Hall (W–H) method. From TEM images particle size was found be around 9–12 nm. Redshift of absorption edge and related bandgap narrowing was observed from the optical absorption spectra. FTIR studies indicated that PEG simply co-exists on the surface of the nanoparticles and acts as the capping agent preventing agglomeration of the nanoparticles. Discrepancy in saturation of magnetization with inclusion of Co content in host matrix can be attributed to antiferromagnetic interactions as anticipated by the BMP model.