A study on structural and optical properties of Mn- and Co-doped SnO2 nanocrystallites

Pure and transition metal ion (Mn and Co)-doped SnO2 nanoparticles were synthesized using a simple chemical precipitation method. Transition metal ions (Mn and Co) of 1, 3 and 5 mol% were doped in order to study the influence of structural and optical properties. The structural, chemical and optical properties of the samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and UV-vis spectroscopy techniques. The SnO2 crystallites were found to exhibit tetragonal rutile structure with lattice parameters, revealing that the metal ions get substituted in the SnO2 lattice. It is observed that the peak position (1 1 0) get shifted to lower angles by increasing the dopant concentration. Hence the lattice parameters (a and c) and the cell volume get decreased. The SEM photograph shows that the grain size of pure SnO2 is larger than that of the metal-doped SnO2 indicating grain growth upon doping. TEM photograph revels that by increasing the content of metal ions, average grain size decreased. A significant red shift in the UV absorbing band edge was observed with the increase in the amount of the Mn and Co contents.