Structural, optical and room temperature magnetic properties of sol–gel synthesized (Co, Fe) co-doped SnO2 nanoparticles

Abstract

Co-Fe co-doped SnO2 nanocrystals with different dopant concentrations (Co = 15 wt% and Fe = 1, 3, 5 wt%) were synthesized by sol–gel technique. XRD spectra revealed the formation of pure SnO2 phase, indicating that the synthesis was effective in diluting the Co and Fe ions into the SnO2 lattice. The structures of the samples were confirmed to be tetragonal, and reductions in lattice parameters confirmed the incorporation of dopant ions in SnO2 lattice. The diffuse reflectance spectroscopy data revealed an increase in the range of absorption and a decrease in energy band gap with an increase in Fe concentration. TEM/SAED confirmed the nanoparticle size and crystalline nature of the samples. The room temperature ferromagnetism was noticed for all the samples, where the magnetization increased with an increase in Fe concentration, whereas the coercivity was more for the sample with less iron concentration. It has been concluded that the ferromagnetic properties depend not only on the distribution of defects but also on the surface diffusion of the dopant ions and nanometric size of the materials.