We present an overview of the factors as well as post processing tools allowing optimization of magnetic softness and GMI effect of rapidly quenched materials: microwires and ribbons. Generally, low ...coercivity and high GMI effect have been observed in as-prepared Co-rich compositions. Annealing at adequate conditions can be very effective for manipulation of the magnetic properties and GMI effect of amorphous and nanocrystalline rapidly quenched materials. After annealing of Co-rich compositions, we can observe transformation of inclined hysteresis loops to rectangular. However, at certain annealing conditions GMI effect can be improved. Using stress-annealing, GMI effect of both Fe-rich and Co-rich microwires as well as of amorphous ribbons can be improved. On the other hand, in Fe-rich FeCuNbSiB microwires after appropriate annealing we observed considerable magnetic softening and GMI effect enhancement. The other promising post-processing allowing GMI effect optimization is Joule heating.
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•Trends in optimization of GMI effect in amorphous and nanocrystalline materials.•Magnetic softening of Fe-rich microwires after stress-annealing or nanocrystallization.•Improvement of GMI effect after Joule heating of Co-rich microwires.•Optimization of GMI effect after post-processing of Co-rich amorphous ribbons.•Improvement of GMI effect after annealing and stress-annealing of Co-rich microwires.
Abstract
Plastic degradation by biological systems with re-utilization of the by-products could be a future solution to the global threat of plastic waste accumulation. Here, we report that the ...saliva of
Galleria mellonella
larvae (wax worms) is capable of oxidizing and depolymerizing polyethylene (PE), one of the most produced and sturdy polyolefin-derived plastics. This effect is achieved after a few hours’ exposure at room temperature under physiological conditions (neutral pH). The wax worm saliva can overcome the bottleneck step in PE biodegradation, namely the initial oxidation step. Within the saliva, we identify two enzymes, belonging to the phenol oxidase family, that can reproduce the same effect. To the best of our knowledge, these enzymes are the first animal enzymes with this capability, opening the way to potential solutions for plastic waste management through bio-recycling/up-cycling.
•Improvement of GMI effect of Fe-rich microwires by stress-annealing.•Improvement of magnetic softness of Fe-rich microwires by stress-annealing.•Dependence of transverse magnetic anisotropy on ...stress, time and temperature of stress-annealing.•An increase in the outer domain sheath volume with transverse magnetic anisotropy upon stress-annealing.
Stress-annealing allows considerably modify magnetic properties of Fe-rich glass-coated microwires. Varying the stress-annealing conditions (temperature, time and stress applied during the annealing) we can observe either remarkable improvement of magnetic softness and giant magnetoimpedance (GMI) effect. Observed changes have been attributed to the transverse magnetic anisotropy. An improvement of the circumferential permeability in the surface layer of metallic nucleus is evidenced from observed magnetic softening and remarkable GMI effect rising. We assumed that stress-annealing leads to an increase in the outer domain sheath with transverse magnetic anisotropy rise in expense of inner axially magnetized core typically existing in as-prepared Fe-rich microwires. Consequently, stress annealing enabled us to design the magnetic anisotropy distribution beneficial for optimization of the GMI effect and magnetic softness of Fe-rich magnetic microwires.
We studied influence of post-processing (annealing and stress-annealing) on domain wall dynamics in Fe-, Ni- and Co-based magnetic microwires with spontaneous and induced magnetic bistability. ...As-prepared Co-based microwires with low and negative magnetostriction present linear hysteresis loops. Magnetic bistability in Co-based microwires has been induced by annealing. Minimizing magnetoelastic anisotropy either by adjusting the chemical composition with a low magnetostriction coefficient or by heat treatment is an appropriate route for the domain wall dynamics optimization in magnetic microwires. Stress-annealing allows further improvement of domain wall velocity and hence is a promising method allowing optimization of the DW dynamics in magnetic microwires. The beneficial influence of stress-annealing on the DW dynamics is explained considering an increase in the volume of outer domain shell with transverse magnetization orientation in expense of decrease in the radius of the inner axially magnetized core. Such transverse magnetic anisotropy can affect the DW dynamics in similar way as the applied transverse magnetic field and hence is beneficial for the DW dynamics optimization. Thus, stress-annealing allows designing the magnetic anisotropy distribution more favorable for the DW dynamics improvement. Co-rich microwires with magnetic bistability induced by annealing present a considerable enhancement in the DW velocity upon applied tensile stress: exactly the opposite to the case of magnetic microwires with spontaneous magnetic bistability. Observed dependence has been explained considering decrease in the magnetostriction coefficient under effect of the applied stress.
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•Rectangular hysteresis loops of annealed Co-rich microwires.•Tuning of hysteresis loops varying stress-annealing conditions.•Enhancement of domain wall velocity after annealing and stress-annealing.•Enhancement of domain wall velocity by applied stress in Co-rich microwires.•Modification of the magnetic anisotropy distribution by stress-annealing.
We report features of microstructure, martensitic transformation, magnetic properties and magnetocaloric effect in three off-stoichiometric Ni45Mn44In11, Ni47Mn41In12and Ni48Mn39In13 ...(nominal-compositions) alloys ribbons. They were selected in the 7.8<e/a<8.0 range, being e/a the valence electron concentration per atom, one of the parameters that determines functional properties displayed by these alloys near room-temperature. Although the real composition is shifted from nominal one in each sample, its influence on all here studied properties at the temperature range of 50–400K is analyzed. Especially, the role played by Ni content in the decrease of magnetization observed in two alloys with respect to the third one with the lowest e/a. Ni content effect on the antiferromagnetic interaction present in the martensitic phase of the alloys ribbons is also evidenced.
•Three off-stoiquiometric Ni–Mn–In Heusler alloys ribbons with low In content were prepared by melt spinning.•A drastic decrease in magnetization for the two alloys with e/a=7.9 and 8.0 in comparison with the alloy showing e/a=7.8 with less Ni content.•High spin freezing temperature around 300K for the two alloys with e/a=7.9 and 8.0.•Exchange bias field at 5K about 1.3kOe and 1.8kOe for alloys with a high at% of Ni, but 0.012kOe for the ribbon with less Ni content.•Magnetocaloric effect enhanced for the alloy with less Ni content.
—We showed that stress-annealing performed under proper conditions can improve magnetic softness, domain wall (DW) velocity and giant magneto-impedance (GMI) effect of Fe-based microwires. One order ...of magnitude improvement of GMI ratio and more than 100% increase of DW velocity have been achieved by stress-annealing. Observed dependencies have been related to the domain structure modification evidenced from the evolution of the hysteresis loops upon stress-annealing. We discussed observed results considering that the outer domain shell with transverse magnetic anisotropy affects the travelling DW in a similar way as the application of transverse bias magnetic field. GMI ratio improvement is attributed to beneficial magnetic anisotropy distribution achieved by stress-annealing.
•Metastability and field-induced arrested state.•Giant negative magnetoresistance.•Large inverse magnetocaloric effect.•Large exchange bias despite extremely small coercive field.•Incipient ...antiferromagnetism.
The transport and magnetic properties of ferromagnetic shape memory alloy of nominal composition Ni46Mn41In13 are reported. The alloy undergoes martensitic phase transition (MPT) around 240K. The region around this structural transition is found to be highly metastable and susceptible to the applied magnetic field. Giant negative magnetoresistance (∼−64% at 70kOe) is observed in the vicinity of the thermally driven MPT. The existence of large inverse magnetocaloric effect around the MPT is also confirmed by the direct measurement using modulated ac field technique. The sample shows large exchange bias at low temperature. The role of Mn–Mn intersite antiferromagnetic correlation is discussed for the above magneto-functional behaviors.
The magnetoimpedance (MI) response in field-annealed soft magnetic Fe73.5Cu1Nb3Si13.5B9 nanocrystalline ribbons has been studied for samples with single-layer and bilayer geometry. We have found that ...bilayer ribbons reveal higher magnetoimpedance values at low frequencies (typically between 2 and 5 MHz), while single-layer ribbons exhibit more pronounced MI effect at intermediate frequencies (above 10 MHz). The correlations between the MI effect and ribbon thickness are discussed in terms of skin effect. The highest sensitivity (η) 65%/Oe was achieved for the samples annealed in magnetic field applied transverse to the ribbon length. The observed findings are of practical importance to develop high-sensitivity magnetic sensors.
•GMI effect is investigated in nanocrystalline Fe73.5Cu1Nb3Si13.5B9 single- and bilayer ribbons.•Bilayers are more appropriate for usage at lower frequencies as compared to single-layers.•Maximum GMI ratios of 177% and sensitivities of 65%/Oe were achieved after TF annealing.•The observed findings are of practical importance for low/intermediate-frequency GMI sensors.
We studied the correlation of magnetic properties, structure, and giant magnetoimpedance (GMI) effect in Finemet-type FeCuNbSiB microwires. We observed that the GMI effect and magnetic softness of ...glass-coated microwires produced by the Taylor–Ulitovsky technique can be tailored by heat treatment. We observed a considerable magnetic softening of studied microwires after annealing. This magnetic softening correlates with the devitrification of amorphous samples. Amorphous Fe-rich microwires exhibited a low GMI effect (GMI ratio below 1%). Considerable enhancement of the GMI effect (GMI ratio up to 125%) has been observed in heat-treated microwires with a nanocrystalline structure.
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