Al–Mg co-doping effect on optical and magnetic properties of ZnO nanopowders

• An obvious peak shift toward the small angles occurred with Mg doping.
• In the UV range, the absorption decreased with the increase of Mg.
• All the samples showed the room temperature ferromagnetism due to defect.
• Mg doping weakened the magnetic property of the nanoparticles at room temperature.

Zn0.97 − xMgxAl0.03O (x=0,0.01,0.03 and 0.05x=0,0.01,0.03 and 0.05) nanoparticles were prepared by hydrothermal growth, and their optical and magnetic properties were systematically studied by the X-ray diffraction (XRD), the UV-visible spectrophotometer, the infrared spectrometer and the physical properties measurement system (PPMS). These results showed that all the nanopowders had hexagonal wurtzite structures. With increasing the content of Mg, the strength of the (110) intensity peak increased. When Mg atoms were not incorporated into the Zn0.97Al0.03O lattice, the infrared light transmittance was higher than that of other groups of samples. In the UV range, the absorption decreased with the increase of the concentration of Mg. Mg doping weakened the magnetic property of the nanoparticles at room temperature. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves were separated with the decrease of temperature due to the pinning effect between the ferromagnetic domain and antiferromagnetic domain.