Effect of Ni toward the optical and transport properties of the spinel solid solution NixCu1−xFe2O4 nanoparticles

Abstract

The solid solution NixCu1−xFe2O4 (x = 0, x = 0. 2,….x = 1) crystallizing in the spinel structure were prepared by the Sol-Gel method at 800 °C. The novelty of the work is also devoted to the synthesis of the spinel ferrites NixCu1−xFe2O4 (0 < x < 1) using the sol gel technique and the measurement of their structural and magnetic properties by X-ray diffraction and magnetic measurements. The structural, magnetic, optical and electrical properties were investigated. The formation of the tetragonal phase with a good crystallization and stoichiometric contents were confirmed by X-ray diffraction (x = 0 and 0.2) while a transition to cubic symmetry is observed for the other compositions. NixCu1−xFe2O4 exhibits n-type conduction with an increased band gap (Eg) as Ni is introduced in the crystal lattice while it decreases with augmenting the Ni-content in the cubic phase. The transport properties are characteristic of n-type behavior where the electrical conductivity decreases up to x = 0.4. Then, it increases and the conduction is mainly governed by the thermal emission over the inter-crystallites. An average hole mobility of ∼ 10−5 cm2 V−1 s−1 was determined for both symmetries. Magnetic measurements revealed that the saturation magnetization (Ms) increases with the Ni-content whereas the coercivity decreases. NiFe2O4 has the largest saturation magnetization (38.16 emu/g). The optical properties namely the energy gap (Eg), reflection index (n), extinction coefficient (k), dielectric complex (ɛ), optical conductivity (σopt), dissipation factor (tan δ) and relaxation time (τ) were determined.