To probe the magnetic properties of Sn0.99Ni0.01O2 Sn0.98Ni0.02O2 nanoparticles, room temperature magnetization is performed on the samples and is shown in Figure 6. It shows no hysteresis loops and the magnetization curve exhibits zero remanence and coercivity (the coercive field is the applied magnetic field that needs to be applied in the direction opposite the initial magnetic field, to bring the magnetization back to zero), which proves that nanoparticles have superparamagnetic properties and they are single-domain nanoparticles [11, 12].
The superparamagnetism enables the nanoparticles to respond to an applied magnetic field without any permanent magnetization and redisperse rapidly when the magnetic field is removed. In the Figure 6, it can be also observed that magnetization of samples increases with increasing doping quantities of Ni.