Doped ions (Co2+, Fe3+) tuning morphologies and magnetic properties of indium oxide nanoparticles

Transition-metal ion-doped indium oxide was potentially used in spintronic devices. In this article, 10 at.% Co²⁺- and Fe³⁺-doped indium oxide nanocrystals were, respectively, prepared by direct solvothermal method. The influences of doped ions on their morphologies and magnetic properties of indium oxide nanocrystals were investigated. It was found that the doped ions could tune the microscopic morphologies and crystalline structures of indium oxide nanoparticles. Co²⁺-doped samples were polycrystalline nanoflowers aggregated by about 5 nm nanocrystals while Fe³⁺-doped specimens were single-crystalline nanocubes with crystalline sizes of about 16 nm. Meanwhile, the magnetic transition from diamagnetism to paramagnetism was also realized by doping Co²⁺ or Fe³⁺ ions into the indium oxide host matrices. In addition, their magnetic properties were further demonstrated to be intrinsic and not caused by impurities.