Ferromagnetic mechanism for Zn0.98Ni0.02O nanoparticles

Zn0.98Ni0.02O nanoparticles have been synthesized successfully by the sol–gel method. Effects of thermal annealing temperature (400, 500 and 600 °C) and atmosphere (argon and air) on the structural, magnetic and optical properties of the samples were investigated. Results indicated that Ni ions were successfully incorporated into the ZnO matrix and replaced Zn ions. By varying temperature and atmosphere of the thermal annealing treatment, we found that Zn0.98Ni0.02O nanoparticles exhibited ferromagnetism at room temperature and this behavior was believed to be from oxygen vacancies.