Effect of Mn doping on the structural and optical properties of SnO2 nanoparticles

Mn doped SnO2 nanoparticles were synthesized by sol–gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), UV-Visible absorption spectroscopy, photoluminescence (PL), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy measurements. XRD analysis revealed the formation of single phase rutile type tetragonal structure of all samples which was further supported by Raman studies and FTIR measurements. Crystallite size was observed to vary from 16.2 nm to 7.1 nm as the Mn content increased from 0% to 15%, suggesting the prevention of crystal growth with Mn doping. It was evident from the absorption spectra that the absorbance tends to increase with the increase in dopant concentration. Optical band gap was calculated using Tauc relation and found to increase with the increase in Mn content confirming the size reduction as a result of Mn doping. Raman spectroscopy measurement depicted the broadening of most intense Raman peak observed at 630 cm−1 with Mn doping, indicating that the Mn ions are substituted at the Sn sites in SnO2 matrix. Room temperature PL spectra revealed that the intensity of luminescent emission tends to increase with the increase in Mn concentration.

► A significant decrease in particle size has been observed with the increase in manganese concentration, without affecting the rutile structure of SnO2.
► Reduction in particle size is confirmed by both XRD and TEM.
► Photoluminescence spectra show that luminescence increases with the increase in manganese concentration.