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Multiferroic composite ceramics xNi0.15Cu0.25Zn0.6Fe2O4-(1-x) Ba0.85Ca0.15Zr0.1Ti0.9O3 (x = 0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.9 and 1) were prepared by combining chemical co-precipitation method with sol–gel method; the microstructure, dielectric, ferroelectric, magnetic and multiferroic properties were comparatively investigated. XRD results show that all the specimens have obvious bi-phases structure. The grains with larger size are magnetic phase Ni0.15Cu0.25Zn0.6Fe2O4(NCZF), while that of smaller size can be attributed to ferroelectric phase Ba0.85Ca0.15Zr0.1Ti0.9O3(BCZT). The dielectric constant of the sample with x = 0.6 is the largest at low frequency but the specimen x = 0.2 has the highest value of dielectric constant in high-frequency region. When x = 0.9, the ceramic has the largest loss, while it presents the lowest loss value when x = 0.3. The height of the peak decreases with increase in the frequency, and the position of the peak moves to higher temperature range with the decrease in x. The dielectric loss increases sharply with temperature, especially when x = 0.9, when the temperature is higher than 300 °C, the dielectric loss reaches hundreds of times under low frequency. Al samples present apparent ferroelectric hysteresis loops, but further characterization shows that the hysteresis may be attributed to leakage current. The remnant polarization(Pr) and coercive field(Ec) do not monotonically change with x, Pr is 0.1576 μC/cm2 at 2 kHz when x = 0.6. The magnetization monotonically changes with the x, indicating that there is a strong interfacial interaction between the two phases. Under the action of an external magnetic field of 1 mT, the magnetoelectric (ME) coupling is the strongest (relative polarization change 37%) when x = 0.2. [ABSTRACT FROM AUTHOR]

Magnetoelectric composites have attracted much attention due to their strong magnetoelectric coupling effect. In this paper, PbTiO3-NiFe2O4 (PTO/NFO) composite ceramics were prepared by sol-gel method. Effect of sintering temperatures on the structure, dielectric properties and multiferroic properties were studied. XRD results show that PTO/NFO ceramics have been successfully prepared. When the sintering temperature is 1050 °C, the secondary phase PbO2 exists in the ceramics. SEM results show that there were two kinds of grains with different sizes. EDS analysis suggested that the large particles are NFO and the small particles are PTO. The sintering temperature has a great influence on the dielectric and ferroelectric properties of the prepared ceramics. When the sintering temperature is 950 °C, the ceramics show the maximum dielectric constant at low frequency. When the sintering temperature is 1150 °C, the maximum residual polarization is 1.236 μC/cm2. The conductive mechanism of ceramics is dominated by Space Charge – Limited Conduction. The remanent magnetization and coercive field decrease with increasing the sintering temperature. The magnetoelectric coupling coefficient shows that ceramics have strong magnetoelectric coupling performance (5.7 V/cm·Oe). [ABSTRACT FROM AUTHOR]

Three different transition metal elements doped Fe3N were prepared by a simple path. Their structure, morphology, and magnetic properties were carefully investigated by X‐ray diffraction, transmission electron microscopy as well as vibrating sample magnetometer. Moreover, we detailedly compared and analyzed the impact of different transition metal elements on the properties of Fe3N. Combining with the results of analysis and comparison, it indicates that this simple method can be used to explore the impact on the transition metal nitride incorporated with different transition metal elements in the carbon‐rich system. [ABSTRACT FROM AUTHOR]

The (Fe 1- x Dy x ) 3 C@C composites were produced by a simple sol-gel route. The structure, composition, morphology and magnetism of the composites are studied by many characterization methods, for example, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM, TEM) as well as vibrating sample magnetometer (VSM). Analysis of the above results indicates that the (Fe 1- x Dy x ) 3 C is embedded in carbon nanotubes and carbon matrix and displays ferromagnetic properties. Moreover, this indicates that saturation magnetization ( M S ) values of the composites tend to increase with the increase in Dy doping. More importantly, we investigates the electrochemical hydrogen production capacity of the (Fe 1- x Dy x ) 3 C@C composites. [ABSTRACT FROM AUTHOR]

(Fe1−xNdx)3N was successfully prepared by a simple complex method. The as-synthetized (Fe1−xNdx)3N exhibits regular rod-like morphology and excellent magnetic properties. X-ray diffraction, scanning electron microscopy with Energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, as well as vibrating sample magnetometer are employed to analyze the structure, morphology and magnetic properties of the samples. What’s more, when the Nd doping concentration is 3%, the coercivity reaches a higher value of 664.61 Oe. It is much higher than the coercivity of 408.84 Oe for the pure Fe3N. The material shows a trend of transition to hard magnet. It opens the way for other soft magnet translating into hard magnet by doping rare earth ions. [ABSTRACT FROM AUTHOR]

Abstract: Iron carbides and nitrides have aroused great interest in researchers, due to their excellent magnetic properties, good machinability and the particular catalytic activity. Based on these advantages, iron carbides and nitrides can be applied in various areas such as magnetic materials, biomedical, photo‐ and electrocatalysis. In contrast to their simple elemental composition, the synthesis of iron carbides and nitrides still has great challenges, particularly at the nanoscale, but it is usually beneficial to improve performance in corresponding applications. In this review, we introduce the investigations about iron carbides and nitrides, concerning their structure, synthesis strategy and various applications from magnetism to the catalysis. Furthermore, the future prospects are also discussed briefly. [ABSTRACT FROM AUTHOR]

A new and simple method to fabricate magnetic Fe4N/Fe3C samples is reported. Meanwhile, pure phase iron carbides (θ-Fe3C and χ-Fe5C2) were obtained by controlling experimental conditions. The structures, magnetic properties, and morphology of the samples were investigated according to the generalized analysis of X-ray diffraction, X-ray photoelectron spectroscopy, as well as transmission electron microscopy and vibrating sample magnetometry. The magnetic properties measurement revealed the remarkable magnetic properties of the samples at 2 and 300 K. The application of the prepared samples as catalysts for oxygen evolution reaction was also investigated in alkaline solution. This simple and convenient route provides a new path to fabricate other metal nitrides and carbides. [ABSTRACT FROM AUTHOR]

Iron nitride (FeN) is a promising material with excellent magnetic properties, but the synthetic methods are difficult to operate in previous literatures. Here, we report a facile synthetic method using ferrous chloride tetrahydrate and ethanediamine as iron and nitrogen sources, followed by calcined at 540 °C for 1 h. The iron nitride with tunable morphology was obtained by changing the experimental conditions. More importantly, the magnetic performances have greatly been improved because of the tunable morphology. The coercivity can reach 408.84 Oe under the optimal conditions with superior retentivity and squareness, showing good ferromagnetic behaviors. This finding broadens our vision to realize the importance of morphology control and paves the way for other transition metal nitrides in obtaining tunable performances by controlling their morphologies. [ABSTRACT FROM AUTHOR]

A series of Fe3C/C-N x nanoparticles (NPs) with different nitrogen content are prepared by a simple one-pot route. In the synthetic procedure, aniline and acetonitrile are simultaneously used as the carbon and nitrogen source. The effect of calcination temperature on the structural and functional properties of the materials is investigated. Magnetic measurement shows that the sample prepared at 800 °C (Fe3C/C-N800 NPs) possesses the highest Ms value of 77.2 emu g−1. On testing as oxygen reduction reaction (ORR) catalysts, the sample prepared at 750 °C (Fe3C/C-N750 NPs) shows the best ORR performance among the series, with a more positive onset potential (+0.99 V vs. RHE), higher selectivity (number of electron transfer n≈3.93), longer durability, and stronger tolerance against methanol crossover than commercial Pt/C catalysts in a 0.1 m KOH solution. Moreover, in acidic solution, the excellent ORR activity and stability are also exhibited. [ABSTRACT FROM AUTHOR]

Fe3N submicrorods with desirable magnetic properties were prepared from a designed metal–organic framework precursor via a modified ethanediamine nitridation route. Magnetic resonance imaging using the Fe3N submicrorods was investigated carefully, confirming the Fe3N submicrorod could be acceptable as a significant contrast agent for its outstanding concentration dependent signal and high r2 relaxivity. Besides, the excellent saturation magnetization and homogeneous dispersity also developed the Fe3N application range. [ABSTRACT FROM AUTHOR]

• The Fe 3 N nanoparticles were successfully synthesized by a simple urea route. • The prepared Fe 3 N nanoparticles have regular spherical shape and uniform particle size. • Research on magnetic properties points out that the prepared nanoparticles possess relatively highe coercivity (604.4 Oe). • Through the study on surface properties of prepared materials, we analyzed the reasons for the change of coercivity. The ε-Fe 3 N nanoparticles/C composite materials have been synthesized by ethylenediamine nitrided urea complexing precursors. The prepared ε-Fe 3 N NPs have regular spherical shape and small particle size. And the prepared ε-Fe 3 N NPs/C magnetic materials have significantly higher coercivity (604.4 Oe) and relatively lower saturation magnetization (21.1 emu/g) compared with the reported experimental and theoretical studies of ε-Fe 3 N. We consider that the surface properties and particle size of the prepared materials will result in the changes in magnetic properties. [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]

Ca 3 (Ti 1- x Co x) 2 O 7 ceramics were prepared by a tartaric acid sol-gel method and sintered in an oxygen atmosphere. The introduction of Co2+/Co3+ as acceptor dopants leads to the formation of more oxygen vacancies and defect dipoles in Ca 3 (Ti 1- x Co x) 2 O 7 ceramics. Oxygen vacancy and defect dipoles lead to the transition of dielectric, leakage, and ferroelectric behaviors of Ca 3 (Ti 1- x Co x) 2 O 7 ceramics. The coexistence of hybrid improper ferroelectricity and ferromagnetism at room temperature in Ca 3 (Ti 1- x Co x) 2 O 7 ceramics has been successfully realized through the superexchange interaction of Co–O–Co. Ca 3 (Ti 1- x Co x) 2 O 7 ceramics exhibit superior ferroelectricity (the remnant polarization is 3.29 μC/cm2) and enhanced ferromagnetism (the remnant magnetization reaches 6.4×10−3 emu/g). This strategy based on the introduction of transition metal ions with unfilled 3d shells at B sites is an important approach to realize novel room-temperature single-phase multiferroic materials for Ca 3 Ti 2 O 7 -based materials. [ABSTRACT FROM AUTHOR]

With the development of electronic information technology, the miniaturization of lightweight devices and their integration have increased the requirements for materials, and two-dimensional composite multiferroic materials have become a major research hotspot in recent years. However, it is difficult for traditional solid multiferroic material to directly switch the magnetic/polarization direction under the action of an applied electric/magnetic field, limiting the improvement of the magnetoelectric coupling coefficient. In this study, a series of BiFeO 3 (BFO)/CoFe 2 O 4 (CFO) composite film multiferroic materials were prepared by changing the annealing routes and annealing atmosphere, the microstructure, ferroelectric properties, dielectric properties, photovoltaic properties, magnetic properties, and magnetoelectric coupling properties of composite films were routeatically studied. The results showed that under the slow annealing route, the composite film has obvious ellipsoidal grains with distinct grain boundaries and better crystallinity. Moreover, the performance of the film after annealing in different atmospheres of the slow annealing route was improved compared with that of the rapid annealing route after annealing in different atmospheres. Simultaneously, by changing the annealing atmosphere of the composite film, the film exhibited better magnetic optical properties and coupling properties after annealing in oxygen. In addition, this study showed that the dielectric constant and residual polarization value of the film increase under the action of magnetic field and illumination, and the maximum photomagnetic dielectric response (3.19%) and photomagnetic response (1.58%) are observed in the annealed film under the oxygen atmosphere of the slow annealing regime, indicating that the magnetoelectric coupling effect of the film is improved under the action of applied light. • Under the slow annealing system, the composite films have grain boundaries and better crystallinity. • The properties of the films annealed under the slow annealing regime are good under different atmospheres. • Films show better magnetic, optical and coupling properties after annealing in oxygen. • The dielectric constant and residual polarization of the film increase under the action of magnetic field and illumination. • Large photomagneto-dielectric responses (3.19%) and photomagneto-electric responses (1.58%) were observed. [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]

Black polycrystalline ε-Fe3N is precipitated from an anhydrous solution of FeCl3 in acetone to which different amounts of en are added as the nitrogen source prior to a calcination under N2 (560 °C, 30 min). [ABSTRACT FROM AUTHOR]