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Multiferroic materials have attracted much attention because of their magnetoelectric coupling effect. In this paper, MnFe2O4 (MFO) magnetic particles and PbZr0.52Ti0.48O3 (PZT) ferroelectric particles were prepared by hydrothermal method and sol–gel method, respectively. PZT particles with different sizes were produced by tuning the sintering temperature, and on this basis, MFO-PZT multiferroic liquid was prepared by using monoamino ethoxy-coupling agent as the surfactants and dimethyl silicone oil as the carrier liquid. The effect of PZT particle size on magnetoelectric properties was studied. XRD and SEM show that the PZT particle and the MFO particle have no secondary phase, the size of MFO particle is 52 nm, and the PZT particle sizes are 0.38 μm, 1.07 μm, 1.68 μm, and 1.79 μm, respectively. When the particle size of PZT is 0.38 μm, a large dielectric constant of 8.39 of the multiferroic liquid was observed at low frequency (250 Hz). When the size of PZT is 1.79 μm, the liquid has the maximum saturation polarization intensity Ps ~ 0.0191 μC/cm2 and the maximum residual polarization intensity Pr ~ 0.0063 μC/cm2 was obtained. When a magnetic field is applied, the value of both Pr and Ps increases. When the size of PZT is 1.07 μm, the maximum magnetoelectric coupling coefficient of the liquid is 54.82 V/(cm·Oe). Compared with the same series of magnetoelectric materials, the magnetoelectric composite multiferroic liquid has a potential application prospect. [ABSTRACT FROM AUTHOR]

The Ca3Ti2O7 materials exhibit hybrid improper ferroelectricity due to the rotation and tilt coupling of TiO6 octahedron. However, the lower remnant polarization of Ca3Ti2O7 ceramics obtained by conventional solid-state method limits its practical application. Herein, the single-phase Ca3Ti2O7 ceramics with enhanced ferroelectricity were synthesized using an acetic acid sol–gel method and two-stage sintering. The sintering process does not significantly change the distortion amplitude of TiO6 octahedron in Ca3Ti2O7 ceramics but has a greater impact on the grain size and the concentration of oxygen vacancy. The synergistic effects of grain size and oxygen vacancy have been achieved in the Ca3Ti2O7 ceramics prepared by the optimal sintering process (1400 °C/12 h − 1550 °C/18 h), which leads to its enhanced hybrid ferroelectricity (Pr = 1.34 μC/cm2 and EC = 120 kV/cm). These findings demonstrate that the sol–gel method is an effective approach to obtain the Ca3Ti2O7 materials with enhanced hybrid improper ferroelectricity. [ABSTRACT FROM AUTHOR]

Low remnant polarization and high coercive field are the main factors limiting the practical application of Ca 3 Ti 2 O 7 -based hybrid improper ferroelectric ceramics. Based on sol-gel method and soft doping effect, (Ca 1- x Nd x) 3 Ti 2 O 7 (x= 0.003) ceramics with higher remnant polarization of ∼3.53 μC/cm2 and lower coercive field of ∼91 kV/cm were obtained. More interestingly, thanks to the large distortion amplitude of TiO 6 octahedron and effective suppression of defects such as oxygen vacancies caused by Nd3+ as a donor dopant, the remnant polarization of (Ca 1- x Nd x) 3 Ti 2 O 7 (x = 0.003 and 0.006) ceramics measured at 10 Hz using the DHM mode were as high as 7.33 μC/cm2 and 5.85 μC/cm2. These findings prove that the soft doping at A sites of Ca 3 Ti 2 O 7 material is a simple and effective strategy to enhance its hybrid improper ferroelectricity. [ABSTRACT FROM AUTHOR]

The (Fe 1- x Nd x ) 3 C nanoparticles (NPs) were prepared by a sol-gel method. The structure, morphology and magnetic properties were investigated by X-ray diffraction, Raman spectra, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Analysis results show that the (Fe 1- x Nd x ) 3 C NPs were embedded in multi-walled carbon nanotubes and displayed ferromagnetic properties. And it is indicated that their saturation magnetization (M s ) values tend to decrease with increasing the Nd doping concentration. More importantly, we propose a possible mechanism to explain the formation process of the (Fe 1- x Nd x ) 3 C NPs. [ABSTRACT FROM AUTHOR]

ε-Fe 3 N can be flexibly synthesized via a sol-gel route by using ethylenediamine as the nitrogen source, and the role of ethylenediamine can be demonstrated by adjusting the molar ratio of ethanediamine to acetone. Excellent magnetic properties (72.35 emu/g) and coercivity are obtained at the optimized condition, showing the potential applications in magnetic material field. In addition, the probable formation mechanism of iron nitride is investigated in this article, supported by XRD patterns and etc, which has important effect on the further research of the iron nitride via a sol-gel route. [ABSTRACT FROM AUTHOR]

Ni doped Fe 3 C ((Fe 1−x Ni x ) 3 C) Nanoparticles (NPs) were prepared via a sol-gel method. The structure, morphology and magnetic properties of the materials are researched. Analysis results show that the crystallite size and magnetic parameters of the materials are affected by the Ni-dopant. Furthermore, it is also well investigated of the water purification for the mesoporosity, magnetic, high specific surface area and facile magnetic separation of the materials. The current synthetic approach is versatile and simple, and thus shows great promise for the large scale synthesis of Fe 3 C based NPs that are useful for water treatment such as the removal of organic molecules. [ABSTRACT FROM AUTHOR]

• The effect of pH value of precursor solution on the microstructure and magnetoelectric properties of BaFe 12 O 19 nanoparticles and ceramics were studied. • The change of pH value of precursor solution causes large distortion of hexagonal flake grains of ceramics, which reflects the deformation of hexagonal cells in BaFe 12 O 19 crystal and leads to the asymmetry of local lattice. • The ferroelectric hysteresis loop and hysteresis loop indicate the multiferroic properties of the prepared ceramics at room temperature. The effect of ceramics leakage current on ferroelectric property were further studied. In this paper, BaFe 12 O 19 (BaM) ceramics at different pH values were prepared by sol–gel method. Effects of pH value on the microstructure, electrical as well as magnetic properties were systematically studied. XRD indicate that the ceramics were mainly BaM. However, with the pH value increasing further, the BaFe 2 O 4 impurity phase appears gradually in both powders and ceramics due to the degree of complexation between citric acid and metal cations and other reasons. SEM results show that the grain size of ceramics decreases from 2.28 μm to 1.35 μm with the pH value increase from 4 to 8. It is found that room temperature dielectric constant, residual polarization, and saturation magnetization of the ceramics is the largest when the pH value of the solution is 4, which are 0.108 μC/cm2 and 32.829 emu/g, respectively. The dielectric constant and residual polarization of ceramics decrease with the increase of pH value. The ferroelectric and magnetic hysteresis loops have confirmed room-temperature multiferroic properties of the prepared ceramics. It laid the foundation for the further development of new room temperature single-phase multi-iron materials. [ABSTRACT FROM AUTHOR]

Fe 3 C has been successfully prepared though a sol–gel process, performing good magnetic properties, whose saturated magnetization can be adjusted by the heating temperature. The introduction of hexamethylenetetramine (HMTA) improves the interference from Fe and ferrite, realizing a flexible and high-efficient route to iron carbide by tertiary amine. We believe the carbon-capsulated Fe 3 C will be a potential candidate in magnetic materials. [ABSTRACT FROM AUTHOR]

• The PLZT@SiO 2 composite ceramic was prepared by the Stöber method, which increased the density of the ceramic, and greatly improved the energy storage density. • SEM results indicate that SiO2 weakens the crystallinity of the ceramics and restricts the grain growth of all the specimens. • Compared with the single-phase PLZT ceramics, although the electric breakdown field strength of the core-shell structure sample has not improved much, its energy storage density has increased significantly. Pb 0.925 La 0.05 Zr 0.95 Ti 0.05 @ x wt%SiO 2 (PLZT@ x wt%SiO 2 , x = 0, 1, 2, 3 and 4, marked as S0, S1, S2, S3, S4 respectively) ceramics were prepared by combining conventional sol-gel method with Stöber method, the microstructure, electrical properties and energy storage characteristics were comparatively investigated. TEM analysis prove that samples S1, S2 and S3 present core-shell structures. SEM results indicate that SiO 2 weakens the crystallinity of the ceramics and restricts the grain growth of all the specimens. When the concentration of SiO 2 is 3 wt%, the sample shows better energy storage characteristics, the value of W re of this sample can reach 2.29 J/cm3; In addition, temperature (T) will induce a phase change in the sample. When T < 50 ℃, sample S3 is ferroelectric phase, when T is in the range of 50–130 ℃, sample S3 is coexistence of anti-ferroelectric and ferroelectric phase, showing double electric hysteresis loops. In this temperature range, the temperature stability of sample S3 is the poorest, and the increases in W re density and η are 317.39 % and 25.04%, respectively. The core-shell structure samples prepared by the Stöber method can increase the energy storage density by reducing the turnover electric field. The energy storage density has increased from 0.3 J/cm3 to 2.29 J/cm3. [ABSTRACT FROM AUTHOR]