Magnetic properties of soft magnetic composites prepared by gas-atomized glassy powders from a new Fe-based alloy with high glass-forming ability

With a pressing need for high efficiency, low power consumption, and miniaturization of electronics, soft magnetic composites(SMCs) show great potential, especially for applications in key electronic component. However, core loss is still the focused issue for SMCs that hinders their sustainable development and widespread applications. In the present study, high-performance SMCs were fabricated by novel Fe_(74)B_(7)C_(7)P_(7)Si_(3)Mo_(1)Cr_(1) powders with spherical shape and a fully glassy structure, which were successfully prepared by a gas atomization method. The microstructure and high-frequency magnetic properties of these SMCs were studied in detail. To enhance the soft ferromagnetism, the effects of annealing temperature(T_a) and powder size on their performance were clarified. Increasing T_a up to 703 K not only helps to effectively release internal stress in the powders, but also improves the integrity of the insulation layer structure, which is conducive to decreasing the core loss. In addition, reducing the powder size contributes to the overall performance enhancement. Prepared from the powders with the smallest mean particle size and annealed at 703 K, the SMC exhibits optimum property combination of a stable effective permeability of 26.2 up to 1 MHz, a total core loss of 883 kW m^(–3)(100 kHz, 100 mT), and a DC-Bias performance of 79.3% under 100 Oe field, which is even comparable to those of the most prominent SMCs reported so far. These results are meaningful for potentially stimulating the development and application of new low-loss SMCs.

Extremely efficient terahertz second-harmonic generation from organic crystals

Achieving efficient and intense second-harmonic generation(SHG)in the terahertz(THz)spectrum holds great potential for a wide range of technical applications,including THz nonlinear functional devices,wireless communications,and data processing and storage.However,the current research on THz harmonic emission primarily focuses on inorganic materials,which often offers challenges in achieving both efficient and broadband SHG.Herein,the remarkable efficiency of organic materials in producing THz harmonics is studied and demonstrated,thereby opening up a new avenue for searching candidates for frequency-doubling devices in the THz band.By utilizing DAST,DSTMS,and OH1 crystals,we showcase their superior frequency conversion capabilities when pumped by the narrowband THz pulses centered at 2.4,1.6,and 0.8 THz.The SHG spans a high-frequency THz domain of 4.8 THz,achieving an unprecedented conversion efficiency of∼1.21%while maintaining a perturbative nonlinear response.The highly efficient SHG of these materials is theoretically analyzed by considering the combined effects of dispersion,phonon absorption,polarization,and the nonlinear susceptibility of organic crystals.This work presents a promising platform for efficient THz frequency conversion and generation across a wide range of frequencies,offering new opportunities for novel nonlinear THz applications in next-generation electronics and optics.

Enhanced energy density in polyetherimide nanocomposite film at high temperature induced by electrospun BaZrTiO_(3) nanofibers

Polymer dielectrics which possess excellent dielectric properties such as high breakdown strength,flexibility,and facile processability are considered as promising materials for advanced electrostatic capacitors.However,most dielectric polymers have unsatisfactory energy storage performances at high-temperature environments.Here,polyetherimide(PEI) nanocomposite films contained with electrospun Ba(Zr_(0.79)Ti_(0.21))O_(3) nanofibers(BZTNFs) are fabricated by common solution casting method.The dielectric properties,especially the breakdown strength of the BZTNFs/PEI nanocomposites,are characterized,yet improvement is only in the small loading ones.The energy storage performance of the 0.5 vol% and1.0 vol% BZTNFs content nanocomposite is further investigated from 25 to 150℃.With the introduction of small loading BZTNFs,the dielectric permittivity and electric displacement of the nanocomposite are improved at all evaluated temperatures.The 1.0 vol% BZTNFs/PEI possesses a maximal discharged energy density of6.05 J·cm^(-3) with high efficiency of 94.9% at 25℃,then falls to 3.34 J·cm^(-3) with efficiency of 54.6% at 150℃ for the larger remnant displacement.Apparently,the relaxation ferroelectric nanofller of BZTNFs is much effective in increasing the dielectric permittivity of nanocomposite,but its capacity to restrict the migration of the charge carriers at high temperatures is weaker than that of the nanofillers with wider bandgap.The complementation of both kinds of the nanofillers probably provides an approach to available high-temperature dielectric films.

Remarkable plasticity and softness of polymorphic InSe van der Waals crystals

Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is unclear,and the understanding of detailed plastic deformation mechanisms is inadequate.Here three prototypes of InSe are predicted to be plastically deformable by calculation,and the plasticity of polymorphic crystals is verified by experiment.Moreover,distinct nanoindentation behaviors are seen on the cleavage and cross-section surfaces.The modulus and hardness of InSe are the lowest ones among a large variety of materials.The plastic deformation is further perceived from chemical interactions during the slip process.Particularly for the cross-layer slip,the initial In-Se bonds break while new In-In and Se-Se bonds are newly formed,maintaining a decent interaction strength.The remarkable plasticity and softness alongside the novel physical properties,endow InSe great promise for application in deformable and flexible electronics.

Recent progress in high-entropy metallic glasses

High-entropy metallic glass(HEMG)is a new type of metallic material with high-entropy alloy-like com-position and amorphous structure,which render HEMGs unusual glass formation behaviors and unique properties.In recent years,fast research progress has been witnessed on the HEMGs,and thus a sys-tematic review is required.In this review,we first introduce the concept of the HEMGs and summarize the developed HEMGs.Then,the glass-forming ability of the HEMGs is discussed,and the general rules are proposed.Focusing on the thermal stability of HEMGs,the effect of entropy on the energy states of HEMGs and the crystallization behavior of HEMGs are discussed.Finally,the mechanical,magnetic,cat-alytic and other properties of HEMGs are presented,and the advantages and disadvantages of HEMGs are shown.This review can function as a quick guideline for overviewing the HEMG field.

Effects of Mn-doping on the structure and electrical properties of Sm-PMN-PT piezoceramics

MnO_(2)-modified Pb_(0.9625)Sm_(0.025)(Mg_(1/3)Nb_(2/3))_(0.71)Ti_(0.2)9O_(3) ceramics were prepared via a solid-state reaction approach.Results of detailed characterizations revealed that the addition of MnO_(2) has influence on the grain size,and all samples exhibit a pure perovskite structure.As the content of manganese increases,the volume of tetragonal phase increases.The ceramics with 1.5 mol.%MnO_(2) show a high electro-strain of 0.151%at 2 kV/mm.Therefore,this study provides a new insight into the role of MnO_(2) addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping.