Conductivity and Dielectric Properties of Nearly Monodisperse NiFe2O4 Nanoparticles

Oleylamine (OAm) functionalized NiFe2O4 nanoparticles were synthesized by reflux method. Oleylamine as a multufunctional ligand provides the essential basic condition for the formation of NiFe2O4 nanoparticles, and it has also surfactant and reducing agent roles. The product was characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry, and thermal gravimetric analyzer (TG). The detailed electrical conductivity and dielectric property of measurements have been performed by dielectric impedance analyzer. The conductivity results show that ac conductivity (σac) is temperature dependent particularly at low frequencies whereas dc conductivity (σdc) exhibits only temperature dependency. The highest dc conductivity is 4.37 × 10 −12 S.cm −1 at 120 ∘C. The dielectric constant (ε′), dielectric loss (ε″), and dielectric loss tangent (tan δ) show different behaviors with frequency and temperature. The variation of dielectric properties with temperature is mainly due to temperature-assisted electron exchange between Ni 2+ and Fe 3+ ions.