In this study, the Mg1−xZnxFe2O4 nanoparticles (x=0–0.9) were prepared by sol-gel method. These ferrites exhibit an inverse spinel structure and the lattice parameter increases as the substitution of ...Zn2+ ions is increased. At lower Zn content (0.1≤x≤0.5), saturation magnetization (Ms) increases, while it decreases at higher Zn content (x≥6). The remnant magnetization (0.17–2.0emu/g) and coercive field (6.0–60Oe) indicate a ferrimagnetic behavior. The average core diameter of selected ferrites is around 15nm and the nanoparticles morphology is quasi spherical. The heating ability of some Mg0.9Zn0.1Fe2O4 and Mg0.7Zn0.3Fe2O4 aqueous suspensions indicates that the magnetic nanoparticles can increase the medium temperature up to 42°C in a time less than 10min
•Magnetic nanoparticles of Mg1−xZnxFe2O4 were synthesized by sol-gel method.•Nanoparticles showing a single spinel crystalline structure were obtained.•Aqueous suspensions of Mg0.7Zn0.3Fe2O4 and Mg0.9Zn0.1Fe2O4 show heating ability.
Amide-based discotic supramolecular organic materials are of interest for fundamental understanding of cooperative self-assembly and collective dipole switching mechanisms as well as for practically ...relevant ferroelectric and piezoelectric properties. Here, we show how replacing amides (dipole moment of ∼3.5 D) with thioamides (∼5.1 D) as dipolar moieties in the archetypal
C
3
-symmetric discotic molecule BTA leads to ferroelectric materials with a higher remnant polarization and lower coercive field. The thioamide-based materials also demonstrate a rare negative piezoelectricity and a previously predicted, yet never experimentally observed, polarization reversal
via
asymmetric intermediate states, that is, ferrielectric switching.
Ferro- and piezoelectric hysteresis curves of a thioamide-based supramolecular organic discotic show intuitively expected but rarely observed ferrielectric behavior.
We have studied the magnetic switching behavior of L10-ordered FePt films with varying thickness. It was found that coercivity is strongly dependent on the film thickness. The obvious variations of ...the coercivity in the thin films are confirmed by the measurements of structural and magnetic properties. With increasing thickness, the degree of L10 chemical ordering increased, while the magnetization reversal process transforms from a pinned two-steps magnetization reversal to a comparatively smooth domain wall motion behavior. Although considering anisotropy, exchange interaction and applied magnetic field, the switching behavior in films is quite complex, the main features of the magnetization reversal mechanism can be understood by performing detailed investigation on the effect of the deposition temperature and the angle of magnetic field.
•Series of FePt films with L10 phase have been prepared.•We focused on the magnetization reversal mechanism with varying thicknesses.•The angle-dependence of switching process is revealed in the FePt films.•Different switching mechanisms were found by increasing the film thickness.
A series of LaFe1−xTixO3 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) nanoparticles have been successfully synthesized by simple co-precipitation technique. The synthesized samples (calcined at 800° C/3hr) were ...characterised for structural, optical and magnetic properties. Structural phase formation of the crystal shows orthorhombic planes of these samples phases. The average crystallite size (Dc) is decreasing with a dopant and found to be varying between ∼ 9 and 25 nm. Tailored surface morphology was analyzed using scanning electron microscope (FESEM) and transmission electron microscopes (TEM) with selected area electron diffraction pattern (SAED) also confirms the evolution of orthorhombic phases. Diffuse reflectance spectra (DRS) are recorded to evaluate the variation of optical band gap (Eg) upon titanium doping into the LaFeO3 system. The obtained results attributed that Eg values are increasing with dopant altering between 2.05 and 2.61 eV. The metal oxide (M - O) stretching vibrations and few functional groups are detected from infrared spectra (IR). The weak ferromagnetic behaviour is observed from hysteresis loop behaviour. Additionally, the large hysteresis loop behaviour induces no saturation up to 15 kOe in nanoparticles coercivity (Hc) and anisotropy constants (K1) are eventually decreasing with ‘x’ values.
Display omitted
•Series of LaFe1−xTixO3 nanoparticles synthesized by simple method.•Samples assased by XRD, FESEM, TEM+SAED, DRS techniques.•Structural phase formation shows orthorhombic crystal planes.•Average crystallite size (Dc) ∼ 9–25 nm confirms the orthorhombic phases.•Optical energy-band shows increasing with dopant altering between 2.05 and 2.61 eV.
Display omitted
•The Fe3N nanoparticles were successfully synthesized by a simple urea route.•The prepared Fe3N 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-Fe3N nanoparticles/C composite materials have been synthesized by ethylenediamine nitrided urea complexing precursors. The prepared ε-Fe3N NPs have regular spherical shape and small particle size. And the prepared ε-Fe3N 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-Fe3N. We consider that the surface properties and particle size of the prepared materials will result in the changes in magnetic properties.
MnFe2O4 bulk sample was synthesized by conventional solid state reaction method, at 1350°C. Nanoparticles with mean size of 〈D〉TEM=10.4(±1.1)nm were prepared by thermal decomposition of metal ...nitrates, at 350°C. And a film sample was prepared by pulsed laser deposition of bulk ferrite on MgO(100) at substrate temperature of 600°C. Then a comparative study of the structural and magnetic properties of the samples has been carried out using different measurements. X-ray diffraction pattern of bulk and nanoparticles samples confirmed formation of spinel phase. The film sample showed an epitaxial growth on MgO in (400) direction. Saturation magnetization of nanoparticles at 300K, MS=33emu/g, was comparable with film sample, MS=38emu/g, both being ∼2.5 times smaller than that of bulk sample (MS=82emu/g). The results showed the importance of surface effects in the film sample and nanoparticles. The obtained zero coercivity of bulk sample at 300K and the low value of 8Oe at 5K is attributed to soft magnetic behavior of the MnFe2O4. On the other hand, nanoparticles showed superparamagnetic behavior at 300K; and blocked state with a large coercivity of 730Oe at 5K. The film sample showed non-zero corecivity at both 5 and 300K which reveals higher magnetic anisotropy of film compared to the bulk ferrite.
We discuss the mechanism of the coercivity enhancement by the grain boundary diffusion process (GBDP) using Dy vapor based on detailed microstructural characterizations. Scanning electron microscopy ...and electron probe microanalysis showed that a (Nd,Dy)2Fe14B shell formed in the outer region of Nd2Fe14B grains while its thickness decreased from the surface to the center of a cube-shaped sample. Atom probe tomography showed that the Dy content at grain boundaries (GBs) was close to that in the (Nd,Dy)2Fe14B shell. High-temperature annealing (at 900°C) of a GB diffusion processed magnet led to the disappearance of the GB layers, which resulted in a substantial reduction in coercivity. This suggests that both the (Nd,Dy)2Fe14B shell and the Nd-rich GB phase layer are required microstructural features for the coercivity enhancement by the GBDP.
A profoundly effective magnetically recoverable nano zinc ferrite nanocatalyst was fabricated by means of sol-gel auto ignition strategy. The synthesized nanocatalyst has been completely portrayed by ...standard techniques for structural, morphological, compositional, surface, magnetic, dielectric, optical and photoluminescence properties individually. The x-ray diffraction pattern affirmed the arrangement of cubic spinel structure with an average crystallite size of 21 nm. FE-SEM images uncovered the circular morphology with nanometric average grain measure (37 nm). The surface area, pore volume and pore radius was observed to be 39.812 m2 g−1, 3.41 cc g−1 and 1.34 nm individually from BET analysis. VSM investigation demonstrated the superparamgnetic nature of the prepared sample with moderate magnetization value and negligible coercivity. The optical band gap deduced from UV-vis spectra was observed to be 2.098 eV. Every one of these properties of zinc nanoferrite makes them brilliant contender for microwave radiation absorption. Further, a proficient and versatile microwave irradiated solvent free synthesis of chalcone derivatives has been developed using prepared zinc nanoferrite catalyst. The remarkable highlights of this new protocol are solvent free reaction, economical cheapness, eco-friendliness, high yields, reduced reaction times and easy recovery and reuse of zinc ferrite nanocatalyst.
The structural and magnetic properties of amorphous Fe87−yB13Cuy (y=0 to 1.5) annealed with a range of heating rates (α) up to 150K/s were investigated. The lowest coercivity (Hc) for Fe87B13 after ...crystallization shows a dramatic decrease from 174A/m to 6.7A/m when α is increased from 1.7K/s to 150K/s. The coercivity of Fe87−yB13Cuy annealed at 150K/s is reduced by Cu addition and Hc=3.0A/m is obtained at y=1.5. Nanostructures with a grain size of 15 to 20nm were evident in transmission electron micrographs from these rapidly annealed alloys.
Display omitted
PDF
