Structural, optical, and magnetic properties of Co-doped SnO2 powders synthesized by the coprecipitation technique

We have used the coprecipitation technique to synthesize polycrystalline Co-doped SnO2 diluted magnetic semiconductors with Co concentrations of 0, 0.5, and 2.0%. X-ray diffraction patterns showed for all samples the expected SnO2 tetragonal structure with no additional peaks corresponding to parasitic phases. Transmission electron microscopy (TEM) did not indicate the presence of magnetic parasitic phases and confirmed that Co ions are uniformly distributed inside the samples. Optical absorption measurements showed an energy band gap which decreases when increasing the Co concentration. Raman spectroscopy shows an intensity loss of classical cassiterite SnO2 vibration lines, which is an indication of significant structural modifications and disorder of the SnO2 lattice. Magnetization measurements revealed a mixture of paramagnetic and antiferromagnetic behavior for Co-doped SnO2 with no sign of ferromagnetism.