Effect of Mn Doping on Structural and Optical Properties of SnO2 Nanoparticles Prepared by Mechanochemical Processing

SnO2 is an n-type semiconductor with rutile crystalline structure and display many interesting optical properties. However, there are limited reports on effect of Mn doped SnO2 on optical properties, prepared by mechanochemical processing. This paper reports the effect of Mn doping on structural and optical properties of SnO2 nanoparticles (Sn1-xMnxO2, x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) prepared by mechanochemical processing in a high energy ball mill and heat-treated at 600 °C. Phase analysis of the dried powders was carried out from the data obtained by X-ray Diffraction (XRD) of the samples. The peak shifting in XRD patterns indicate that Mn ions were successfully doped into the SnO2 crystal lattice with successive increase in dopant levels. Average crystallite size, was calculated based on Scherrer's equation, and was found to vary from 24 to 35 nm. Blue shift in Eg at x>0.02 may be affected by decrease in crystallite size. Red shift in Eg with increasing Mn concentration (x ≤ 0.02) could be attributed to either sp-d exchange interaction and to the increasing crystallite size of the SnO2 nanoparticles. The quantum confinement effect was suggested to be the dominant reason for the changes in Eg. The reduction in emission intensity could be due to non-radiative recombination processes promoted by Mn ions with increasing Mn content.