Magnetoelectric and magnetodielectric coupling in partially Ni-doped CoFe2O4 and 0.15(Ba0.7Ca0.3TiO3)-0.85(BaZr0.2Ti0.8O3) composites prepared via clean microwave sintering

Multiferroic composites with high magnetoelectric coupling at room temperature are considered as the most significant materials due to their potential application in many electronic devices. Furthermore, ultrafast, eco-friendly energy-efficient innovative techniques to develop multifunctional materials have attracted abundant importance. In this study, we report on ferrite–ferroelectric particulate composites prepared via clean, eco-friendly, ultrafast, hybrid-microwave sintering. Partially Ni-doped CoFe2O4 was selected as a magnetostrictive phase due to its considerable value of the magnetostriction coefficient, λ11 ≈ −118 ppm, saturation magnetization Ms ≈ 80 emu/gm, and μB ≈ 3.37 and mixed with a 0.15(Ba0·7Ca0·3TiO3)–0.85(BaZr0·2Ti0·8O3) ferroelectric phase in different content ratios of 10%, 20%, 30%, and 40%. The multiferroic properties of the sintered composite samples were investigated considering magnetoelectric and magnetodielectric couplings. The highest value of the magnetoelectric coupling coefficient, αME = 22..09 mV/Oe·cm was observed for the composite with 40% ferrite content, while similar composite exhibits the higher value of the magnetodielectric coupling coefficient which is 3.52% at 1 kHz (frequency) and 1 T (magnetic field). X-ray diffraction and Raman spectroscopy confirmed the phases of the ferrite and ferroelectric constituents without revealing any additional phases. The impedance and AC conductivity of the multiferroic compositions were analyzed under various temperatures and by applying a magnetic field at room temperature. The temperature-dependent dielectric nature confirms that the addition of Ni-doped CoFe2O4 into a ferroelectric constituent substantially influences the dielectric constant in the paraelectric region. These results may offer an alternative technique for the preparation of multiferroic composites with improved coupling properties. © 2020 Elsevier B.V.1

Correlative structural refinement-magnetic tunability, and enhanced magnetostriction in low-temperature, microwave-annealed, Ni-substituted CoFe2O4 nanoparticles

The preparation of nanomaterials by conventional methods involves multiple steps that are time-and energy-consuming; hence, it must be replaced by clean, environment-friendly processes. Nanostructured mixed spinel ferrites have wide applicability given their electrical, magnetic, and magnetostrictive properties. Herein, we present an ultrafast, eco-friendly, and thermally efficient microwave (MW)-heating technique to replace the conventional strategies for the preparation of Ni-doped CoFe2O4 ferrite nano particles. Mixed spinel ferrite nanoparticles are obtained through an MW technique carried out for 20 min at 600 degrees C. The cubic nature of the MW-processed, Ni-substituted CoFe2O4 spinel ferrite is demonstrated by Rietveld refinement. Composition-dependent tunable magnetic properties associated with cation distribution and average crystallite size variation are realized by the substitution of Ni2+ at Co2+ in the CoFe2O4 lattice. The highest values of saturation magnetization and coercivity are noted for the Co0.9Ni0.1Fe2O4 ferrite at 5 K and the average crystallite size is similar to 20 nm; the octa to tetra transition of Co2+ is observed owing to substitution by Ni2+ ions. The highest values of magnetostrictive coefficient and strain sensitivity are detected for CoFe2O4; the Ni2+-substituted Co0.9Ni0.1Fe2O4 also exhibits nearly identical behavior. Thus, Ni2+-substituted CoFe2O4 is a remarkable magnetostrictive material suitable for developing magnetoelectric composites and magneto-mechanical sensor applications. Moreover, it is observed that efficient, fast, and eco-friendly microwave processing can be adopted as an alternative approach for low-temperature processing such kinds of nanostructured materials for future electromagnetic device applications. (C) 2021 Elsevier B.V. All rights reserved