High dielectric-energy storage and ferromagnetic-superparamagnetic properties: tetra-doping CuO nanocompositions

Abstract

AbstractTetra-doping by (Mn, Fe, Co, Ni) ions strongly boosted the room temperature dielectric constant and the ferromagnetic-superparamagnetic characteristics of monoclinic CuO structure. In this study, undoped CuO, Cu0.98Mn0.005Fe0.005Co0.005Ni0.005O, Cu0.96Mn0.01Fe0.01Co0.01Ni0.01O and Cu0.94Mn0.015Fe0.015Co0.015Ni0.015O nanocompositions were synthesized through coprecipitation technique. The crystal structure analysis verified that all samples have a pure single phase, corresponding to monoclinic CuO structure. The substitution of Cu2+-sites into CuO lattice by Mn2+, Fe2+/3+, Co2+ and Ni2+ ions has been deduced from the expansions of lattice constant, shifts of XRD diffraction peaks and band gap energy alteration. The additions of (Mn, Fe, Co, Ni) ions lead to the formation of homogenous distributed very fine spherical nanoparticles, especially at large concentrations of dopants (Cu0.94Mn0.015Fe0.015Co0.015Ni0.015O sample). The tetra-doping by (Mn, Fe, Co, Ni) ions reduced the intensity of the diffuse reflectance alongside red shifted the absorption edge and the band gap energy of monoclinic CuO structure. Cu0.98Mn0.005Fe0.005Co0.005Ni0.005O exhibits a high relative permittivity value of 6096 at low frequency of 42 Hz with small dielectric loss tangent (tan δ) compared to pure one. The tetra-doping by (Mn, Fe, Co, Ni) dopants induced excellent intrinsic ferromagnetic and superparamagnetic hysteresis loops into monoclinic CuO structure with full saturation loops shape and variable coercivity values.