Structural, optical and dielectric properties of Al/Mn doped ZnO nanoparticles, a comparative study

Pure, and doped with Al/Mn, ZnO nanoparticles were produced by the chemical co-precipitation method. X-ray diffraction analysis confirmed the hexagonal crystalline with wurtzite structure of pure and doped samples. Williamson-Hall (W-H) analysis was used to determine the crystallite size and micro-strains. The change in the bond length and lattice parameters of the doped ZnO confirms the incorporation of Al3+ ions to interstitial sites and Mn2+ ions to substitutional sites of ZnO lattice. UV-Visible spectroscopy has been used to study the change in the absorption edge after doping. Dielectric and conducting properties have been investigated and compared. Dielectric properties of doped samples have indicated the hopping mechanism liable for the change. Dielectric loss (tan delta) shows the opposite direction with frequency due to dielectric dispersion. The ac conductivity also indicated their variation after doping and is associated with an increase in the charge carrier and defects, which ultimately decides the overall change.