MXenes are a family of two-dimensional nanomaterials. Titanium carbide MXene (Tisub.3Csub.2Tsub.x-MXene), reported in 2011, is the first inorganic compound reported among the MXene family. In the ...present work, we report on the study of the composition and various physical properties of Tisub.3Csub.2Tsub.x-MXene nanomaterial, as well as their temperature evolution, to consider MXenes for space applications. X-ray diffraction, thermal analysis and mass spectroscopy measurements confirmed the structure and terminating groups of the MXene surface, revealing a predominant single OH layer character. The temperature dependence of the specific heat shows a Debye-like character in the measured range of 2 K–300 K with a linear part below 10 K, characteristic of conduction electrons of metallic materials. The electron density of states (DOS) calculations for Tisub.3Csub.2OH-MXene reveal a significant DOS value at the Fermi level, with a large slope, confirming its metallic character, which is consistent with the experimental findings. The temperature dependence of electrical resistivity of the MXene samples was tested for a wide temperature range (3 K–350 K) and shows a decrease on lowering temperature with an upturn at low temperatures, where negative magnetoresistance is observed. The magnetoresistance versus field is approximately linear and increases its magnitude with decreasing temperature. The magnetization curves are straight lines with temperature-independent positive slopes, indicating Pauli paramagnetism due to conduction electrons.
There is an increasing understanding of the mechanisms underlying the development of magnetoelectric coupling and multiferroic order in both single-phase and composite materials. The investigations ...underlying this advance include a range of studies on thin films, which are expected to play an important role in the development of novel magnetoelectric devices. The properties of both single-phase and composite systems are widely studied. While single-phase materials can exhibit rich spin-charge coupling physics, the magnetizations, polarizations, and transition temperatures are often too small to be innately useful for device design. Conversely, a number of ferromagnetic–piezoelectric composites can show strong magnetoelectric coupling at ambient temperatures, which develops as a product-property mediated by elastic deformation, making these systems more directly amenable to fabricating devices. In this review, we provide a short overview of the mechanisms for magnetoelectric coupling in multiferroics, together with a discussion of how this magnetoelectric coupling is relevant for designing new multiferroic devices, including magnetic field sensors, dual electric and magnetic field tunable microwave and millimetre wave devices and miniature antennas. We present a brief summary of some of the significant results in studies on thin-film multiferroics, with an emphasis on single-phase materials, and covering systems where the magnetic and ferroelectric transitions fall at the same temperature as well as systems where they fall at different temperatures.
Owing to their reduced dimensions, the magnetic properties of ultrathin magnetic films and multilayers, e.g. magnetic anisotropies and exchange coupling, often depend strongly on the surface and ...interface structure. In addition, chemical composition, crystallinity, grain sizes and their distribution govern the magnetic behaviour. All these structural properties can be modified by light-ion irradiation in an energy range of 5-150 keV due to the energy loss of the ions in the solid along their trajectory. Consequently the magnetic properties can be tailored by ion irradiation. Similar effects can also be observed using Ga+ ion irradiation, which is the common ion source in focused ion beam lithography.
Exfoliated magadiite nanosheets embedded with Fe.sub.3O.sub.4 were constructed. Advantage was taken of the strong coordination between the silanol groups in magadiite nanosheets and the Gd.sup.3+ ion ...to prepare the final adsorbent, Gd.sup.3+-immobilized magnetic magadiite nanosheets. The adsorbent with two-dimensional (2D) morphology offered high surface area and abundant Gd.sup.3+ contents for phosphopeptides enrichment, on which Fe.sub.3O.sub.4 with positive electricity incorporated the magnetic properties. Combining with matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI TOF-MS), the method showed low detection limit (0.05 fmol). The feasibility of using the 2D nanocomposite for phosphopeptides enrichment was demonstrated using mixtures of beta-casein and bovine serum albumin (1:5000). The standard deviation of captured phosphopeptides in three repeated experiments were in the range 0.15-0.42 (< 0.5% RSD). Further evaluation revealed that the nanocomposite was capable of enriching phosphopeptides from non-fat milk, human saliva, and serum. Graphical abstract
In this study, composite particles of rGO/CoFesub.2Osub.4 were synthesized using a solvothermal method to fabricate a low-density magnetorheological (MR) material with enhanced sedimentation ...stability. The morphology and crystallographic features of rGO/CoFesub.2Osub.4 were characterized via SEM, TEM, and XRD, and its magnetic properties were tested using VSM. The MR fluid was formulated by blending rGO/CoFesub.2Osub.4 particles into silicone oil. Under different magnet strengths (H), a rotational rheometer was used to test its MR properties. Typical MR properties were observed, including shear stress, viscosity, storage/loss modulus, and dynamic yield stress (τsub.dy) following the Herschel–Bulkley model reaching 200 Pa when H is 342 kA/m. Furthermore, the yield stress of the MR fluid follows a power law relation as H increases and the index changes from 2.0 (in the low H region) to 1.5 (in the high H region). Finally, its MR efficiency was calculated to be about 10sup.4% at H of 342 kA/m.
A high perovskite activity is sought for use in magnetic applications. In this paper, we present the simple synthesis of (2.5% and 5%) Tellurium-impregnated-LaCoOsub.3 (Te-LCO), Te and LaCoOsub.3 ...(LCO) by using a ball mill, chemical reduction, and hydrothermal synthesis, respectively. We also explored the structure stability along with the magnetic properties of Te-LCO. Te has a rhombohedral crystal structure, whereas Te-LCO has a hexagonal crystal system. The reconstructed Te was imbued with LCO that was produced by hydrothermal synthesis; as the concentration of the imbuing agent grew, the material became magnetically preferred. According to the X-ray photoelectron spectra, the oxidation state of the cobaltite is one that is magnetically advantageous. As a result of the fact that the creation of oxygen-deficient perovskites has been shown to influence the mixed (Tesup.4+/2−) valence state of the incorporated samples, it is abundantly obvious that this process is of utmost significance. The TEM image confirms the inclusion of Te in LCO. The samples start out in a paramagnetic state (LCO), but when Te is added to the mixture, the magnetic state shifts to a weak ferromagnetic one. It is at this point that hysteresis occurs due to the presence of Te. Despite being doped with Mn in our prior study, rhombohedral LCO retains its paramagnetic characteristic at room temperature (RT). As a result, the purpose of this study was to determine the impacts of RT field dependency of magnetization (M-H) for Te-impregnated LCO in order to improve the magnetic properties of RT because it is a low-cost material for advanced multi-functional and energy applications.
We focused on obtaining MFe2O4 nanoparticles using ricin oil solution as surfactant and on their structural characterization and magnetic properties. The annealed samples at 500°C in air for 6h were ...analyzed for the crystal phase identification by powder X-ray diffraction using CuKα radiation. The particle size, the chemical composition and the morphology of the calcinated powders were characterized by scanning electron microscopy. All sintered samples contain only one phase, which has a cubic structure with crystallite sizes of 12–21nm. From the infrared spectra of all samples were observed two strong bands around 600 and 400cm−1, which correspond to the intrinsic lattice vibrations of octahedral and tetrahedral sites of the spinel structure, respectively, and characteristic vibration for capping agent. The magnetic properties of fine powders were investigated at room temperature by using a vibrating sample magnetometer. The room temperature M–H hysteresis loops show ferromagnetic behavior of the calcined samples, with specific saturation magnetization (Ms) values ranging between 11 and 53emu/g.
► MFe2O4 nanoparticles obtained using ricin oil as surfactant. ► The structures were confirmed by SEM micrographs, FTIR spectra and XRD spectroscopy. ► The samples contain only one phase with crystallite sizes of 12–21nm.
Metal–organic framework (MOF) is highly desirable as a functional material owing to its low density, tunable pore size, and diversity of coordination formation, but limited by the poor dielectric ...properties. Herein, by controlling the solvent and mole ratio of cobalt/linker, multidimension‐controllable MOF‐derived nitrogen‐doped carbon materials exhibit tunable morphology from sheet‐, flower‐, cube‐, dodecahedron‐ to octahedron‐like. Tunable electromagnetic parameters of Co@N‐doped carbon composites (Co@NC) can be obtained and the initial MOF precursor determines the distribution of carbon framework and magnetic cobalt nanoparticles. Carbonized Co@NC composites possess the following advantages: i) controllable dimension and morphology to balance the electromagnetic properties with evenly charged density distribution; ii) magnetic‐carbon composites offer plenty of interfacial polarization and strong magnetic coupling network; iii) a MOF‐derived dielectric carbon skeleton provides electronic transportation paths and enhances conductive dissipation. Surface‐mediated magnetic coupling reflects the stray magnetic flux field, which is corroborated by the off‐axis electron holography and micro‐magnetic simulation. Optimized octadecahedral Co@NC sample exhibits the best microwave absorption (MA) of −53.0 dB at the thickness of 1.8 mm and broad effective frequency from 11.4 to 17.6 GHz (Ku‐band). These results pave the way to fabricate high‐performance MA materials with balanced electromagnetic distribution and controlled morphology.
A series of magnetic‐dielectric composites with homogeneous Co NPs embedded into the metal–organic framework‐derived carbon framework are fabricated by a self‐template and confined conversion strategy. Benefiting from the precise dimension regulation and perfect magnetic‐electric balance, the multi‐morphology Co@NC absorbers endow the composite with optimal and efficient microwave absorption performance.
A series of homoleptic (Tb(III)(Pc)(2) ) and heteroleptic (Tb(III)(Pc)(Pc')) Tb(III) bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert-butyl or ...tert-butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron-donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N-Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand-field effect. In particular, heteroleptic Tb(III) (Pc)(Pc') complex 4, which contains one octa(tert-butylphenoxy)-substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single-molecule magnet reported to date.
The discovery of magnetism by the ancient Greeks was enabled by the natural occurrence of lodestone - a magnetized version of the mineral magnetite. Nowadays, natural minerals continue to inspire the ...search for novel magnetic materials with quantum-critical behaviour or exotic ground states such as spin liquids. The recent surge of interest in magnetic frustration and quantum magnetism was largely encouraged by crystalline structures of natural minerals realizing pyrochlore, kagome, or triangular arrangements of magnetic ions. As a result, names like azurite, jarosite, volborthite, and others, which were barely known beyond the mineralogical community a few decades ago, found their way into cutting-edge research in solid-state physics. In some cases, the structures of natural minerals are too complex to be synthesized artificially in a chemistry lab, especially in single-crystalline form, and there is a growing number of examples demonstrating the potential of natural specimens for experimental investigations in the field of quantum magnetism. On many other occasions, minerals may guide chemists in the synthesis of novel compounds with unusual magnetic properties. The present review attempts to embrace this quickly emerging interdisciplinary field that bridges mineralogy with low-temperature condensed-matter physics and quantum chemistry.
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