Effects of Ni concentration on structural, magnetic and optical properties of Ni-doped ZnO nanoparticles

摘要

Ni-doped zinc oxide (Zn_(1-x)Ni_xO, 0 ≤x ≤0.08) diluted magnetic semiconductors have been synthesized by the using a sol-gel method. Structural, magnetic and optical properties of the samples have been studied. The results of X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray absorption fine structure (XAFS) indicated that Ni ions were substitutionally incorporated into the crystal lattice of ZnO. With Ni concentration increasing up to 2 at.%, all diffraction peaks corresponded to wurtzite structure of ZnO, but for Zn_(0.97)Ni_(0.03)O, secondary phase of NiO emerged. Based on the results of X-ray photoelectron spectroscopy (XPS), Ni incorporated into the ZnO lattice as Ni~(2+). The produced samples showed good high-Tc (Curie temperature) ferromagnetism. The results of vibrating sample magnetometer (VSM) and photoluminescence (PL) showed that ferromagnetism (FM) of the Ni-doped ZnO nanoparticles originated from the presence of the O vacancy.