Effect of Co doping on the structural and optical properties of ZnO nanospindles synthesized by co-precipitation method

Abstract

Co doped ZnO nanospindles with general compositional formula Zn1−xCoxO (0 ≤ x ≤ 0.1) are prepared by wet chemical co precipitation method. The samples are characterized for its structural, morphological, compositional and optical properties by X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive analysis of X-rays (EDAX), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy. XRD patterns confirm wurtzite structure with no secondary phases for pure and Co doped ZnO samples. The crystallite size of the samples calculated from the XRD patterns are found to be in the range of 22–31 nm. SEM images show that the particles are spindle shape with an average length and diameter 660 and 295 nm respectively. The average particle size as calculated from TEM image are found to be in the range of 28–40 nm. EDAX spectra confirms the presence of Co in the samples with expected stoichiometry. FTIR results give information about the nature of chemical bonding and incorporation of the dopants into the ZnO lattice. UV–Visible spectra show well excitonic absorption peaks and the band gap energies are estimated to values between 3.15–3.54 eV. The variation of band gap energy is discussed.