Synthesis,structural, optical and magnetic properties of Cu-doped ZnO nanorods prepared by a simple direct thermal decomposition route

Cu-doped ZnO nanorods (i.e. Cu = 1.75, 3.55, 5.17 and 6.39 at.%) have been successfully synthesized by simple, direct, thermal decomposition of zinc and copper acetates in air at 300 °C for 6 h. The prepared samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy. The XRD results indicate that the 1.75 at.% Cu-doped ZnO sample has a pure phase with the ZnO wurtzite structure, while the impurity phases are detected with increasing Cu concentrations. It was found that the doping of Cu results in a reduction of the preparation temperature. The optical properties of the samples were also investigated by UV–visible spectroscopy and photoluminescence measurements. The results show that the Cu doping causes the change in energy-band structures and effectively adjusts the intensity of the luminescence properties of ZnO nanorods. X-ray photoelectron spectroscopy analysis implies that there are some oxygen vacancies in the samples and also indicates that all the doped samples are associated with the mixture of Cu ion states (Cu²⁺ and Cu¹⁺/Cu⁰). Magnetic measurements by vibrating sample magnetometry indicate that undoped ZnO is diamagnetic, whereas all of the Cu-doped ZnO samples exhibit room temperature ferromagnetic behavior. We suggest that Cu substitution and density of oxygen vacancies (V _o) may play a major role in the room temperature magnetism of the Cu-doped ZnO samples.