Correlation Between Saturation Magnetization, Bandgap and Lattice Volume of Transition Metal (M = Cr, Mn, Fe, Co or Ni) Doped Zn1-xMxO Nanoparticles
Dr. Alex Punnoose
This work reports on transition metal doped ZnO nanoparticles and compares the effects doping with different transition metal ions has on the structural, optical, and magnetic properties. Zn1-xMxO (M = Cr, Mn, Fe, Co or Ni) nanoparticles were prepared by a chemical process for x = 0.02 and 0.05 in powder form. The powders where characterized by x-ray diffraction, spectrophotometry and magnetometry. The Zn1-xMxO samples showed a strong correlation between changes in the lattice parameters, bandgap energy, and the ferromagnetic saturation magnetization. Unit cell volume and bandgap, determined from x-ray diffraction and spectrophotometry respectively, were maximized with Fe doping and decreased as the atomic number of the dopant moved away from Fe. Bandgap was generally lower at x = 0.05 than x = 0.02 for all dopants. Weak ferromagnetism was found for all transition metals, with the highest magnetization observed for 5% Fe, giving a similar trend corresponding to the unit cell volume and bandgap. The saturation magnetization reached a maximum of 6.38 memu/g for Zn0.95Fe0.05O. This correlation shows that the transition metal dopant type plays a crucial role in the structural, optical, and magnetic properties of ZnO.