Hydrothermal synthesis and properties of NiFe₂O₄@BaTiO₃composites with well-matched interface

Abstract

NiFe 2 O 4 @BaTiO 3 multiferroic composite particles were produced by a simple hydrothermal method in two steps: preparing NiFe 2 O 4 nanoparticles and then synthesizing core-shell nanocomposites. Multiferroic composite ceramics were sintered from these powders. X-ray diffraction, Raman scattering and energy dispersive x-ray analyses indicated that the core-shell composites with a NiFe 2 O 4 core and BaTiO 3 shell were formed in the hydrothermal environment. Different types of sharp interfaces were self-assembled owing to the minimization of direct elastic energy. The saturation magnetization of the composites linearly increased with the NiFe 2 O 4 content while the dielectric constant decreased. A dielectric peak appeared at around 460• C because of the oxygen vacancies in the BaTiO 3 ceramics. It resulted in an enhancement of magnetic permeability in the composites, indicating magnetoelectric coupling that was also observed by direct magnetoelectric measurements.

Magnetoelectric coupling on multiferroic cobalt ferrite–barium titanate ceramic composites with different connectivity schemes

“…Nano-composites, which exhibit multiferroic, as well as magnetoelectric properties, have been prepared by various methods including solid state reaction, sol-gel, and hydrothermal synthesis [4,5,6]. Barium titanate, BaTiO3, is often used as the ferroelectric constituent due to its excellent piezoelectric properties and lead free chemical composition.…”

Fabrication, structure and properties of BaTiO3–BaFe12O19 composites with core–shell heterostructure

“…Though there is no secondary phase beside BaTiO 3 and BaFe 12 O 19 shown in XRD pattern, it is just because of the concentration of the soft magnetic phase is too low. [14], resulting in a high coercivity of 0.96BaTiO 3 -0.04BaFe 12 O 19 core-shell nanoparticles. The exchange coupling effect increases with the continuous increase of BaFe 12 O 19 content, with which the rotation of the domains on one particle as the field is reversed induces domains in contiguous particles to rotate, and thereby the coercivity decreases [1].…”

“…Consequently, with the temperature increasing, a higher energy is provided to restore polarization. The higher the frequency, the higher the required temperature, and thus, the dielectric maximum shifts toward higher temperatures [14]. The inherently low electrical resistivity of BaFe 12 O 19 is detrimental to conventional polarization measurements of BaTiO 3 @BaFe 12 O 19 composites [8].…”

“…of large interfacial area for better phase connectivity [12], resulting in superior dielectric and magnetic properties. There are many examples of BaTiO 3 -based core-shell composites that provide optimal properties such as BaTiO 3 -Fe 2 O 3 [13] and BaTiO 3 -(Ni, Zn, Co)Fe 2 O 4 [14,12,2] core-shell composites. T.A.…”

Multiferroic Ni0.6Zn0.4Fe2O4-BaTiO3 nanostructures: Magnetoelectric coupling, dielectric, and fluorescence

“…3,11,13 The second process is hydrothermal, which is surfactant free, and the size and shape of nanostructure depends on the adjustment of pH value, hydrolysis time, and temperature. 7,16 In the present paper, we have prepared MF composite of Ni 0. 6 O 4 Ti), polyethylene glycol (PEG), and urea taken in desired stoichiometric ratios.…”