  Undoped and Mn doped ZnO samples with different percentage of Mn content (1
mol%, 2 mol% and 3mol%) were synthesized by a simple solvo-thermal method. We
have studied the structural, chemical and optical properties of the samples by
using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy
dispersive x-ray (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy
and UV-VIS spectroscopy. The XRD spectra show that all the samples are
hexagonal wurtzite structures. The lattice parameters calculated for the Mn
doped ZnO from the XRD pattern were found to be slightly larger than those of
the undoped ZnO, which indicates substitution of Mn in ZnO lattice. SEM
photograph shows the grain size of undoped ZnO is bigger than the Mn doped ZnO
indicating hindrance of grain growth upon Mn doping. As the Mn doping increases
the optical band gap decreases for the range of Mn doping reported here.
