Structural, magnetic, and optical properties of zinc- and copper- substituted nickel ferrite nanocrystals

Ferrite nanocrystals are interesting material due to their rich physical properties. Here we add nonmagnetic dopants Zn and Cu to nickel ferrite nanocrystals, Ni1-xMxFe2O4 (0<=x<=1, M{\in}{Cu, Zn}), and characterize how relevant properties of the samples are modified accordingly. Basically, these dopings cause a rearrangement of Fe+3 ions into the two preexisting octahedral and tetrahedral sites. In fact, this, we show, induces pertinent magnetic properties of the doped samples. In the case of the Cu-doping, the Jahn-Teller effect also emerges, which we identify through the FTIR Spectroscopy of the samples. Moreover, we show an increase in the lattice parameters of the doped samples, as well a superparamagnetic behavior for the doped samples is shown, while the Jahn-Teller effect precludes a similar behavior in the CuFe2O4 nanocrystals. The influences of Zn and Cu substitutions are investigated on the optical properties of nickel ferrite nanocrystals by photoluminescence measurement at room temperature.