Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separ...Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separability of iron-based carriers require further enhancement.This study investigates the effect of the concentration of Mn doping on reactivity,elastic properties and magnetic properties based on density functional theory(DFT)calculations.Theoretical results demonstrate that Mn doping effectively enhances reactivity by reducing the oxygen vacancy formation energy(E_(vac))from 2.33 to 0.87 eV.However,Mn doping introduces HV/EV Ms lattice distortions that deteriorate elastic properties,thereby reducing wear resistance,as evidenced by a 54.54%decrease in the hardness-to-Young's modulus ratio(H_(v)/E_(v))forα-Fe_(2)O_(3)and an 83.33%reduction for Fe_(3)O_(4).Furthermore,Mn doping also modifies magnetic properties.The maximum of saturation magnetization(M_(s))of Fe_(3)O_(4)reaches 121.02 emu/g at 33.33%Mn doping concentration.Finally,systematic evaluation identifies 33.33%as the optimal Mn doping concentration,achieving a balance in enhanced reactivity,superior magnetic performance,and retained elastic stability.展开更多
The magnetic properties and Kondo effect in Ce3TiBi5 with a quasi-one-dimensional structure were investigated using in situ high-pressure resistivity measurements up to 48 GPa.At ambient pressure,Ce_(3)TiBi_(5) underg...The magnetic properties and Kondo effect in Ce3TiBi5 with a quasi-one-dimensional structure were investigated using in situ high-pressure resistivity measurements up to 48 GPa.At ambient pressure,Ce_(3)TiBi_(5) undergoes an antiferromagnetic(AFM)transition at T_(N)∼5 K.Under high pressures within 8.9 GPa,we find that Kondo scattering contributes differently to the high-temperature resistance,R(T),depending on the applied current direction,demonstrating a significantly anisotropic Kondo effect.The complete P–T phase diagram has been constructed,in which the pressure dependence of T_(N) exhibits a dome-like shape.The AFM order remains robust under pressure,even when the coherence temperature T^(*) far exceeds 300 K.We attribute the observed anisotropic Kondo effect and the robust AFM to the underlying anisotropy in electronic hybridization under high pressure.展开更多
The nanocrystalline magnets with nominal compositions of Sml_xLuxCo6.8Zr0.2 （x-=0, 0.2, 0.4, 0.6） were prepared directly by the intensive milling. The effects of Lu content on the phase structure, the magnetic prope...The nanocrystalline magnets with nominal compositions of Sml_xLuxCo6.8Zr0.2 （x-=0, 0.2, 0.4, 0.6） were prepared directly by the intensive milling. The effects of Lu content on the phase structure, the magnetic properties, and magnetization behaviors were also investigated. The XRD patterns of the as-milled samples showed a single SmCo7 phase with TbCu7 structure. Lu addition was proved to result in relevant improvements in the microstructure and magnetic properties, especially in the maximum energy product （BH）max. It was shown that a higher maximum energy product and coercivity of about 17.47 kJ/m3 and 473.45 kA/m were obtained in the sample with x=0.2. From the analysis of the magnetization reversal behavior, it was found that a stronger intergrain exchange coupling interaction was observed in the samples with Lu-doping. From the studies of the coercivity mechanism, it was shown that nucleation model was the dominant magnetization reversal process at the elevated temperature.展开更多
In general,the rapid growth of α-Fe clusters is a challenge in high Fe-content Fe-based amorphous alloys,negatively affecting their physical properties.Herein,we introduce an efficient and rapid post-treatment techni...In general,the rapid growth of α-Fe clusters is a challenge in high Fe-content Fe-based amorphous alloys,negatively affecting their physical properties.Herein,we introduce an efficient and rapid post-treatment technique known as ultrasonic vibration rapid processing(UVRP),which enables the formation of high-density strong magnetic α-Fe clusters,thereby enhancing the soft magnetic properties of Fe_(78)Si(13)B_(9) amorphous alloy ribbon.展开更多
The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized...The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure.The particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 nm.The selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline nature.The samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic behavior.The Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)interaction.The doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical transition.The divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from water.The removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),respectively.The Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.展开更多
Interlayer antiferromagnetic coupling,small magnetic anisotropy,and low air stability of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)have been critical bottlenecks to the future application of the quant...Interlayer antiferromagnetic coupling,small magnetic anisotropy,and low air stability of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)have been critical bottlenecks to the future application of the quantum anomalous Hall efect(QAHE)at zero magnetic feld.In this study,we propose a scheme to utilize capped sliding van der Waals materials to efectively modulate the magnetic and topological properties of MnBi_(2)Te_(4).Our results demonstrate that the h-BN/MnBi_(2)Te_(4)/h-BN heterostructure,constructed by sliding ferroelectric h-BN bilayer and MnBi_(2)Te_(4),not only realizes a transition from interlayer antiferromagnetic to ferromagnetic coupling but also signifcantly enhances the out-of-plane magnetism and air stability of MnBi_(2)Te_(4).Moreover,the above magnetic properties can be further improved by tuning the interlayer distance between h-BN and MnBi_(2)Te_(4).Additionally,the obtained band structures and topological properties clearly support that the h-BN/MnBi_(2)Te_(4)/hBN heterostructure can harbor the QAHE with a Chern number of C=1.This work provides a new and nonvolatile modulation approach to achieve high-temperature and high-precision QAHE at zero magnetic feld.展开更多
The effect of Ti addition on microstructures and magnetic properties of B-lean(Pr,Nd)_(31.1)Fe_(67.1-x)(CoCuGa)_(1.4)Ti_(x)B_(0.9)(wt%,x=0.0,0.1,0.2,0.3,0.4)sintered magnets were investigated.The remanence Bris slight...The effect of Ti addition on microstructures and magnetic properties of B-lean(Pr,Nd)_(31.1)Fe_(67.1-x)(CoCuGa)_(1.4)Ti_(x)B_(0.9)(wt%,x=0.0,0.1,0.2,0.3,0.4)sintered magnets were investigated.The remanence Bris slightly reduced due to the deteriorated orientation degree and the diminished volume fraction of main phase caused by the existence of rod-shaped Ti-B-rich phase.However,the HcJobviously increases from1145 kA/m for x=0.0 sample to 1515 kA/m for x=0.2 sample.The results demonstrate that the increments of coercivity for x=0.2 and x=0.0 samples after post-sinter annealing(PSA)are 62.9%and 20.6%,respectively.Rod-shaped Ti-B-rich phase forms after Ti doping,which leads to the existence of6:13:1 type RE-Fe-(Cu,Ga)phase with high Fe content at triple junctions.This is beneficial to the formation of continuous thin grain boundaries with low Fe content,which can weaken the exchange coupling interaction between adjacent grains,leading to the improved coercivity.展开更多
In this work,the properties and microstructure of sintered Nd-Pr-Fe-Co-Zr-Ga-Cu-B magnet prepared by the single-step annealing,double-step annealing,and triple-step annealing processes were studied.The triple-step ann...In this work,the properties and microstructure of sintered Nd-Pr-Fe-Co-Zr-Ga-Cu-B magnet prepared by the single-step annealing,double-step annealing,and triple-step annealing processes were studied.The triple-step annealed magnet exhibits the highest intrinsic coercivity of 19.72 kOe,which is a 58.5%enhancement relative to the as-sintered magnet,and has the best temperature stability of coercivity.The best continuity of grain boundary(GB)phase and the highest content of RE6Fe13Ga phase can be observed in the triple-step annealed magnet,along with relatively small grain size.After triple-step annealing process,the phase separation occurs at the triple-junction(TJ)region of the magnet,which is the Fe-rich phase identified as RE6Fe13Ga and the Fe-poor phase identified as Ia-RE_(2)O_(3).The Ia-RE_(2)O_(3)phase located at the corner of the TJ region can extend between the grains of(Nd,Pr)_(2)Fe_(14)B main phase to form the GB phase with a Fe content of less than 15 at%,thereby enhancing the magnetic isolation effect.The lattice misfit between the Ia-RE_(2)O_(3)phase and the adjacent main phase is less than 5%,which is helpful to reduce defects at the edges of the main phase grains,thus reducing the nucleation of reverse domains.展开更多
In this research work,sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles(SrFe_(2)O_(4))with different ratios of terbium(Tb).Different characterization techniques were used to in...In this research work,sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles(SrFe_(2)O_(4))with different ratios of terbium(Tb).Different characterization techniques were used to investigate the structural,morphological,dielectric and magnetic properties of the prepared samples.X-ray diffraction(XRD)result suggests that face-centered cube spinel nanocrystalline structure is formed.Crystallite size of the SrFe_(2)O_(4)decreases with rising of Tb ratio.The morphology,shape and size of the SrFe_(2)O_(4)were examined by scanning electron microscopy(SEM)analysis and results reveal inhomogeneous distributions of the nanostructures with high agglomeration.The electrical resistivity of the SrFe_(2)O_(4)increases with rising of Tb ratio,which is confirmed from the cyclic voltammetry.It is observed that dielectric constant of all the samples decreases with the increasing frequency range.It is determined that the dielectric constants of the spinel ferrites are frequency dependent and decrease with increasing the frequency of applied electric field.The magnetic behavior of SrFe_(2)O_(4)with different ratios of Tb was studied and it is found that the saturation magnetization values of samples decrease with increase in the substitution of Tb^(3+)at octahedral sites for Fe^(3+).This decrease in the values of M_(s) is also attributed to spin at surface of nanoparticles.展开更多
Structural fine-tuning is of significant importance to enhance the magnetic anisotropy and elucidate the magneto-structural relationship for single molecule magnets(SMMs).For this purpose,two mononuclear Dy^(3+) SMMs:...Structural fine-tuning is of significant importance to enhance the magnetic anisotropy and elucidate the magneto-structural relationship for single molecule magnets(SMMs).For this purpose,two mononuclear Dy^(3+) SMMs:[Dy{HB(pz)3}2(Sal)](1) and [Dy{HB(pz)_(3)}_(2)(MeO-Sal)](2),where HB(pz)_(3)^(-)represents hydro tris(pyrazolyl)borate,Sal denotes salicyiaidehyde and MeO-Sal stands for 5-methoxysalicylaldehyde,were designed and synthesized.Single crystal X-ray diffraction tests show that the two SMMs have very similar eight-coordinated molecule structures,although the introducing of-MeO substituent on salicyiaidehyde ligand induces the changes on the molecule packing mode and the space group.Both the two SMMs have a Dy-O_(aryloxidebond) that is significantly shorter than other Dy-O/N bonds,which defines the orientation of main anisotropy axis of the ground Kramers doublets and engenders the slow relaxation of the magnetization behavior,as evidenced by the magnetic susceptibility and the ab initio calculation.Though with an electron-donating substituent on the axial Sal ligand in 2,the collective magnetic anisotropy is not enhanced and the corresponding magneto-structural relationship is discussed based on the experimental and theoretical calculation results.In addition,as neutral molecules,1 and 2 are soluble in several common organic solvents,like CH_(2)Cl_(2),CHCl_(3),THF and so on.展开更多
Sm–Co-based films play an irreplaceable role in special applications due to their high curie temperature and magnetocrystalline anisotropic energy,especially in heat-assisted magnetic recording(HAMR),but the complex ...Sm–Co-based films play an irreplaceable role in special applications due to their high curie temperature and magnetocrystalline anisotropic energy,especially in heat-assisted magnetic recording(HAMR),but the complex composition of Sm–Co phase and unclear synergistic coupling mechanisms of multi-elemental doping become the challenges to enhance the properties.In this work,a novel strategy combining magnetron sputtering and a high-throughput experiment method is applied to solve the above-mentioned problems.Fe/Cu co-doping highly increases the remanence while maintaining a coercivity larger than 26 kOe,leading to an enhancement of the magnetic energy product to 18.1 MGOe.X-ray diffraction(XRD)and high-resolution transmission electron microscope(HRTEM)reveals that SmCo_(5) phase occupies the major fraction,with Co atoms partially substituted by Fe and Cu atoms.In situ Lorentz transmission electron microscopy(LTEM)observations show that the Sm(Co,Cu)5 phase effectively prohibits domain wall motions,leading to an increase of coercivity(H_(c)).Fe doping increases the low saturation magnetization(M_(s))and low remanence(Mr)due to the Fe atom having a higher saturation magnetic moment.The magnetization reversal behaviors are further verified by micromagnetic simulations.Our results suggest that Sm–Co-based films prepared via Fe/Cu co-doping could be a promising candidate for high-performed HAMR in the future.展开更多
The<001>orientation of the Goss texture aligned with the rolling direction is the most easily magnetized direction,effectively enhancing the magnetic properties of non-oriented silicon steel.In the present study...The<001>orientation of the Goss texture aligned with the rolling direction is the most easily magnetized direction,effectively enhancing the magnetic properties of non-oriented silicon steel.In the present study,an ultra-thin high-silicon sheet of 0.2 mm with a strong Goss texture was successfully fabricated using a two-stage rolling method,achieving superior magnetic properties.The combination of suitable primary rolling reduction and intermediate annealing proved beneficial in promoting the formation of Goss texture.Electron back scatter diffraction(EBSD)was used to characterize micro-shear bands within deformed grains of secondary rolled sheets.Observations revealed that the recrystallized Goss nucleus originated from the Goss substructure of shear bands within deformed{111}<112>grains during the initial stages of recrystallization.The influence of stored energy and grain size on texture evolution was thoroughly investigated using quasi-in situ EBSD during recrystallization.In the initial stages,large deformed{111}<112>and near{111}<112>grains with high stored energy facilitated nucleation and growth of Goss and near-Goss grains within shear bands and reduced grain boundary nucleation.In the later stages,large deformed grains with low stored energy underwent a strain-induced grain boundary migration mechanism to nucleate.During the recrystallization,many recrystallized Goss and near-Goss grains clustered together,with Goss grains rotating towards near-Goss orientation.The resulting annealed ultra-thin 0.2 mm sheet with a pronounced Goss texture exhibited superior magnetic properties.展开更多
A series of single-phase high-entropy perovskite ceramics(HEPCs)(La_(0.25)Nd_(0.25)Sm_(0.25)Gd_(0.25))_(1-x)Yb_(x)MnO_(3)(x=0.25,0.3,0.35 and 0.4)was synthesized using solid-state reactions.The effect of Yb on the str...A series of single-phase high-entropy perovskite ceramics(HEPCs)(La_(0.25)Nd_(0.25)Sm_(0.25)Gd_(0.25))_(1-x)Yb_(x)MnO_(3)(x=0.25,0.3,0.35 and 0.4)was synthesized using solid-state reactions.The effect of Yb on the structure and magnetic properties was systematically investigated.The results show that all samples are in orthorhombic perovskite structures with a space group of Pbnm and exhibit a strong crystallization trend sintered at 1300℃for 16 h.All HEPCs have a smooth surface morphology with distinct grain boundaries and exhibit significant hysteresis effects at T=5 K.With the increase of Yb,high lattice distortion and weak double exchange lead to the decrease of T_(C).The presence of Jahn-Teller(JT)distortion and the enhancement of MnO_(6)octahedral distortion result in different magnetic interactions.Moreover,the sample has the best magnetic properties at x=0.35 among the four HEPCs,which is attributed to the large content of Mn^(3+),remnant ratio(Mr/Ms)and lattice distortion(σ^(2)).This work provides a valuable reference for regulating the magnetism of high-entropy ceramics based on rare-earth perovskite manganese oxides.展开更多
Four types of resins,P1–P4,are used as binders for FeSiBC amorphous powder,which are then press-molded and heat-treated to fabricate magnetic powder cores(MPCs).By testing the permeability,loss,density,and radial cru...Four types of resins,P1–P4,are used as binders for FeSiBC amorphous powder,which are then press-molded and heat-treated to fabricate magnetic powder cores(MPCs).By testing the permeability,loss,density,and radial crush strength of MPCs,the effect of the binder on the magnetic properties of the cores is investigated and the best resin is found.The results show that the silicone resin P3 exhibits the best thermal stability,retaining 82.1%of its mass after heat treatment at 430°C.This contributes to improving the insulation of MPCs and reducing the eddy current loss,which is 46.06 mW cm^(−3)(150 kHz,20 mT)with the mechanical strength of 11.13 MPa.The bonding of epoxy resin P4 is superior to that of other resins,which significantly improves the powder compactness and makes MPCs density reach 5.67 g cm^(−3),and its permeability is as high as 28.7.The two types of resins have different advantages,and both lead to MPCs with excellent properties.展开更多
The impact of rare-earth yttrium and cold-rolling reduction rate on the texture evolution and magnetic properties of non-oriented electrical steel is investigated.The experimental results clearly demonstrate that the ...The impact of rare-earth yttrium and cold-rolling reduction rate on the texture evolution and magnetic properties of non-oriented electrical steel is investigated.The experimental results clearly demonstrate that the influencing mechanism of rare-earth yttrium on texture evolution varies at different stages.During the stage of normalization and annealing,the second-phase particles with yttrium precipitate at the grain boundaries of brass-oriented grains,pinning the grain boundaries and inhibiting the development of brass components.During the cold rolling stage,the purification of rare earth yttrium significantly reduces the shear band density of cold-rolled steel.Consequently,the experimental steel with yttrium exhibits larger and more uniform grain size after recrystallization annealing.During the recrystallization stage,the nucleation energy of experimental steel with yttrium is reduced,which facilitates the nucleation of low-energy{100}and{110}grains,and greatly limits the growth of γ-recrystallized grains,forming strong cube and Goss textures after recrystallization annealing.The combination of these effects contributes to the superior magnetic properties of the non-oriented electrical steel with yttrium.The influence of cold rolling reduction rate on the magnetic properties of non-oriented silicon steel needs to be comprehensively considered in terms of the recrystallized grain size,texture,and sample thickness.The samples with higher cold-rolling reduction rate have better magnetic properties due to the reduction in eddy current losses caused by thickness reduction,which offsets the adverse effects of smaller grain size and more γ texture components on magnetic properties.展开更多
Elemental modulation and heat treatment optimization have emerged as pivotal strategies for enhancing the soft magnetic properties of alloys.We thoroughly examine the impact of microalloyed Co on the amorphous formati...Elemental modulation and heat treatment optimization have emerged as pivotal strategies for enhancing the soft magnetic properties of alloys.We thoroughly examine the impact of microalloyed Co on the amorphous formation ability,thermal stability,and soft magnetic properties of Fe_(80)Co_(x)Si_(7-x)B_(8)P_(4)Cu1(x=0,0.5,1,1.5,2)alloys.The influence of different annealing processes on these properties is analyzed through detailed insights into the evolution of nanocrystalline microstructure and magnetic domain behavior.Our findings indicate that Co addition facilitates the nucleation and growth of the a-Fe(Si,Co)phase while broadening the thermal processing window,thereby significantly improving the alloy’s soft magnetic properties.Notably,the alloy with x=1 undergoes a pre-annealing and reheating process to yield a finer,denser,and more uniform nanocrystalline structure(average grain size D=20.29 nm,grain density Nd=1.5×10^(23)m^(-3)).This refinement enables the formation of broad magnetic domains characterized by 180°domain walls,culminating in exceptional soft magnetic properties,including a high magnetic flux density(B_(s)=1.81 T),high effective permeability(μ_(e)=18,014),and low coercivity(H_(c)=5.57 A m^(-1)).Further,the pinning fields(Hp)for the x=1 alloy are notably low,ranging from15 to 20 A m^(-1),while the maximum effective permeability reaches 69,300.These exceptional properties are directly linked to the alloy’s minimized total free energy(E)and its highly homogeneous microstructure,which collectively suppress magnetic pinning effects.Such characteristics position the x=1 alloy as an exceptional candidate for high-sensitivity applications,particularly in sensor device systems functioning under mild magnetic fields and necessitating swift reaction.展开更多
Owing to the presence of large residual internal stress during cold compaction,it is difficult to optimize the multiple high-frequency magnetic properties of amorphous soft magnetic composites(ASMCs)simultaneously.Her...Owing to the presence of large residual internal stress during cold compaction,it is difficult to optimize the multiple high-frequency magnetic properties of amorphous soft magnetic composites(ASMCs)simultaneously.Here,a surface nanoengineering strategy was proposed to address the above dilemma by constructing a stress buffer layer composed of amorphous nano-particles,between amorphous powder and insulation coating.The amorphous FeSiBCCr@x wt.%FeB(x=0.5,1,3)composite powders with coreshell structures were successfully prepared via an in-situ chemical reduction method.Especially,when the composite ratio of nano-particles is 1 wt.%,the comprehensive properties of the ASMC reach the best balance.Compared with the FeSiBCCr ASMC,the saturation magnetization of the modified ASMC enhances from 153 to 171 emu/g.Meanwhile,the core loss decreases by 28.25%,while the effective permeability increases by 25% and can stabilize to∼20 MHz.Therefore,our work provides a strategy for achieving superior comprehensive soft magnetic properties of ASMCs via surface nanoengineering,which presents enormous application potential in high-frequency electric devices.展开更多
This work investigated the microstructure,magnetic properties,and crystallization kinetics of the as-spun and annealed alloy ribbons of(Fe_(40-x)Co_xNi_(40)Si_(6.33)B_(12.66)Cu_1)_(0.97)Nb_(0.03),where x=0,6,7,8,9,pre...This work investigated the microstructure,magnetic properties,and crystallization kinetics of the as-spun and annealed alloy ribbons of(Fe_(40-x)Co_xNi_(40)Si_(6.33)B_(12.66)Cu_1)_(0.97)Nb_(0.03),where x=0,6,7,8,9,prepared using the meltspinning method.The results show that adding a moderate amount of Co can improve the glass forming ability(GFA),the first peak crystallization temperature,and thermal stability of the as-spun alloy ribbons.With x=7,the two-stage crystallization temperature interval△Tx=90 exhibits optimal thermal stability,and the alloy annealed at 673 K for 10 minutes shows the favorable combined magnetic properties,with H_(c)=0.12 A/m,M_(s)=88.7 A·m^(2)/kg,andμ_(e)=13800.The magnetic domain results show that annealing removes numerous pinning points in the magnetic domains of the alloy ribbons,making the domain walls smoother and effectively reducing the pinning effect.展开更多
Previous studies have demonstrated that increasing Fe doping content can enhance the saturation magnetization and maximum energy product of 2:17-type Sm-Co rare-earth permanent magnets.Howeve r,syste matic theo retica...Previous studies have demonstrated that increasing Fe doping content can enhance the saturation magnetization and maximum energy product of 2:17-type Sm-Co rare-earth permanent magnets.Howeve r,syste matic theo retical calculations and the effects of other transition metal dopants have yet to be explored.This study employed first-principles computational methods to investigate the effects of doping with 3d and Zr transition metal elements on the structural stability,magnetic properties,and electronic structure of Sm_(2)Co_(17)permanent magnets.The results indicate that Sc and Zr tend to occupy the Sm-6c site,while Ni,Cu and Zn preferentially occupy the 18h site,and Ti,V,Cr,Mn and Fe primarily occupy the Co-6c site.Except for V and Cu,all other elements effectively improve the structural stability of the doped systems.Additionally,Mn and Fe doping can significantly enhance the total magnetic moment and magnetocrystalline anisotropy energies of the Sm_(2)Co_(17)system,while Cr only increases the total magnetic moment.More importantly,doping with Cr,Mn and Fe within the doping co ntent range of9.8 at%<x<35.29 at% can simultaneously improve the structural stability,total magnetic moment and magnetocrystalline anisotropy energy of the Sm_(2)Co_(17) system.Our study provides valuable theoretical guidance for experimental exploration and is expected to promote the development and application of novel rare-earth permanent magnetic materials.展开更多
The Fe_(1−x)Ni_(x)VO_(4)(x=0,0.05,0.10,and 0.20)nanoparticles in this work were successfully synthesized via a co-precipitation method.The structural,magnetic and electrochemical properties of the prepared Fe_(1−x)Ni_...The Fe_(1−x)Ni_(x)VO_(4)(x=0,0.05,0.10,and 0.20)nanoparticles in this work were successfully synthesized via a co-precipitation method.The structural,magnetic and electrochemical properties of the prepared Fe_(1−x)Ni_(x)VO_(4) nanoparticles were studied as a function of Ni content.The experimental results show that the prepared Ni-doped FeVO_(4) samples have a triclinic structure.Scanning electron microscopy(SEM)images reveal a decrease in average nanoparticle size with increasing Ni content,leading to an enhancement in both specific surface area and magnetization values.X-ray absorption near edge structure(XANES)analysis confirms the substitution of Ni^(2+)ions into Fe^(3+)sites.The magnetic investigation reveals that Ni-doped FeVO_(4) exhibits weak ferromagnetic behavior at room temperature,in contrast to the antiferromagnetic behavior observed in the undoped FeVO_(4).Electrochemical studies demonstrate that the Fe_(0.95)Ni_(0.05)VO_(4) electrode achieves the highest specific capacitance of 334.05 F·g^(−1) at a current density of 1 A·g^(−1),which is attributed to its smallest average pore diameter.In addition,the enhanced specific surface of the Fe_(0.8)Ni_(0.2)VO_(4) electrode is responsible for its outstanding cyclic stability.Overall,our results suggest that the magnetic and electrochemical properties of FeVO_(4) nanoparticles could be effectively tuned by varying Ni doping contents.展开更多
基金Supported by National Natural Science Foundation of China(50976032,51776070)。
文摘Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separability of iron-based carriers require further enhancement.This study investigates the effect of the concentration of Mn doping on reactivity,elastic properties and magnetic properties based on density functional theory(DFT)calculations.Theoretical results demonstrate that Mn doping effectively enhances reactivity by reducing the oxygen vacancy formation energy(E_(vac))from 2.33 to 0.87 eV.However,Mn doping introduces HV/EV Ms lattice distortions that deteriorate elastic properties,thereby reducing wear resistance,as evidenced by a 54.54%decrease in the hardness-to-Young's modulus ratio(H_(v)/E_(v))forα-Fe_(2)O_(3)and an 83.33%reduction for Fe_(3)O_(4).Furthermore,Mn doping also modifies magnetic properties.The maximum of saturation magnetization(M_(s))of Fe_(3)O_(4)reaches 121.02 emu/g at 33.33%Mn doping concentration.Finally,systematic evaluation identifies 33.33%as the optimal Mn doping concentration,achieving a balance in enhanced reactivity,superior magnetic performance,and retained elastic stability.
基金supported by the National Key Research and Development Program of Chinathe National Natural Science Foundation of China (Grant Nos.2024YFA1408000,12474097,and2023YFA1406001)+2 种基金the Guangdong Provincial Quantum Science Strategic Initiative (Grant No.GDZX2201001)the Center for Computational Science and Engineering at Southern University of Science and Technology,the Major Science and Technology Infrastructure Project of Material Genome Big-science Facilities Platform supported by Municipal Development and Reform Commission of Shenzhen(for J.L.Z.and Y.L.)the Chinese funding sources applied via HPSTAR。
文摘The magnetic properties and Kondo effect in Ce3TiBi5 with a quasi-one-dimensional structure were investigated using in situ high-pressure resistivity measurements up to 48 GPa.At ambient pressure,Ce_(3)TiBi_(5) undergoes an antiferromagnetic(AFM)transition at T_(N)∼5 K.Under high pressures within 8.9 GPa,we find that Kondo scattering contributes differently to the high-temperature resistance,R(T),depending on the applied current direction,demonstrating a significantly anisotropic Kondo effect.The complete P–T phase diagram has been constructed,in which the pressure dependence of T_(N) exhibits a dome-like shape.The AFM order remains robust under pressure,even when the coherence temperature T^(*) far exceeds 300 K.We attribute the observed anisotropic Kondo effect and the robust AFM to the underlying anisotropy in electronic hybridization under high pressure.
基金Project supported by Zhejiang Province Innovative Research Team (2010R50016)Provincial Major Science and Technology Project of Zhejiang (2009C21010)+2 种基金the Provincial Natural Science Foundation of Zhejiang (Z4090462,Y6100640)National Natural Science Foundation of China (51001092)National Public Research Project Special for Quality Testing (201210107)
文摘The nanocrystalline magnets with nominal compositions of Sml_xLuxCo6.8Zr0.2 （x-=0, 0.2, 0.4, 0.6） were prepared directly by the intensive milling. The effects of Lu content on the phase structure, the magnetic properties, and magnetization behaviors were also investigated. The XRD patterns of the as-milled samples showed a single SmCo7 phase with TbCu7 structure. Lu addition was proved to result in relevant improvements in the microstructure and magnetic properties, especially in the maximum energy product （BH）max. It was shown that a higher maximum energy product and coercivity of about 17.47 kJ/m3 and 473.45 kA/m were obtained in the sample with x=0.2. From the analysis of the magnetization reversal behavior, it was found that a stronger intergrain exchange coupling interaction was observed in the samples with Lu-doping. From the studies of the coercivity mechanism, it was shown that nucleation model was the dominant magnetization reversal process at the elevated temperature.
基金supported by the Major Science and Technology Project of Zhongshan City(No.2022AJ004)the Key Basic and Applied Research Program of Guangdong Province(Nos.2019B030302010 and 2022B1515120082)Guangdong Science and Technology Innovation Project(No.2021TX06C111).
文摘In general,the rapid growth of α-Fe clusters is a challenge in high Fe-content Fe-based amorphous alloys,negatively affecting their physical properties.Herein,we introduce an efficient and rapid post-treatment technique known as ultrasonic vibration rapid processing(UVRP),which enables the formation of high-density strong magnetic α-Fe clusters,thereby enhancing the soft magnetic properties of Fe_(78)Si(13)B_(9) amorphous alloy ribbon.
文摘The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure.The particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 nm.The selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline nature.The samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic behavior.The Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)interaction.The doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical transition.The divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from water.The removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),respectively.The Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.
基金supported by the National Key R&D Program of China(Grant No.2024YFA1408103)National Natural Science Foundation of China(Grants No.11974098,12474158,12234017 and 12488101)+3 种基金Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302800)Natural Science Foundation of Hebei Province(Grant No.A202305017)Anhui Initiative in Quantum Information Technologies(Grant No.AHY170000)Fundamental Research Funds for the Central Universities(Grant No.WK2340000082)。
文摘Interlayer antiferromagnetic coupling,small magnetic anisotropy,and low air stability of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)have been critical bottlenecks to the future application of the quantum anomalous Hall efect(QAHE)at zero magnetic feld.In this study,we propose a scheme to utilize capped sliding van der Waals materials to efectively modulate the magnetic and topological properties of MnBi_(2)Te_(4).Our results demonstrate that the h-BN/MnBi_(2)Te_(4)/h-BN heterostructure,constructed by sliding ferroelectric h-BN bilayer and MnBi_(2)Te_(4),not only realizes a transition from interlayer antiferromagnetic to ferromagnetic coupling but also signifcantly enhances the out-of-plane magnetism and air stability of MnBi_(2)Te_(4).Moreover,the above magnetic properties can be further improved by tuning the interlayer distance between h-BN and MnBi_(2)Te_(4).Additionally,the obtained band structures and topological properties clearly support that the h-BN/MnBi_(2)Te_(4)/hBN heterostructure can harbor the QAHE with a Chern number of C=1.This work provides a new and nonvolatile modulation approach to achieve high-temperature and high-precision QAHE at zero magnetic feld.
基金supported by the National Natural Science Foundation of China(52061015,52371188)Young Talents Program of Jiangxi Provincial Major Discipline Academic and Technical Leaders Training Program(20212BCJ23008)+2 种基金Jiangxi Provincial Natural Science Foundation(20212BAB214018)Technology Program of Fujian Province(2021T3063)Jiangxi Province Key Laboratory of Magnetic Metallic Materials and Devices(2024SSY05061)。
文摘The effect of Ti addition on microstructures and magnetic properties of B-lean(Pr,Nd)_(31.1)Fe_(67.1-x)(CoCuGa)_(1.4)Ti_(x)B_(0.9)(wt%,x=0.0,0.1,0.2,0.3,0.4)sintered magnets were investigated.The remanence Bris slightly reduced due to the deteriorated orientation degree and the diminished volume fraction of main phase caused by the existence of rod-shaped Ti-B-rich phase.However,the HcJobviously increases from1145 kA/m for x=0.0 sample to 1515 kA/m for x=0.2 sample.The results demonstrate that the increments of coercivity for x=0.2 and x=0.0 samples after post-sinter annealing(PSA)are 62.9%and 20.6%,respectively.Rod-shaped Ti-B-rich phase forms after Ti doping,which leads to the existence of6:13:1 type RE-Fe-(Cu,Ga)phase with high Fe content at triple junctions.This is beneficial to the formation of continuous thin grain boundaries with low Fe content,which can weaken the exchange coupling interaction between adjacent grains,leading to the improved coercivity.
基金Project supported by the Major Special Project of Fujian Province(2023HZ021005)the Guiding Project of Fujian Province(2023H0006)+2 种基金the Major Project of Science and Technology of Fuzhou(2022-ZD-010)the Young and Middle-aged Teachers Education Scientific Research Project of Fujian Province(JAT200594,JAT231008)the Natural Science Foundation of Fujian Province(2022J011151)。
文摘In this work,the properties and microstructure of sintered Nd-Pr-Fe-Co-Zr-Ga-Cu-B magnet prepared by the single-step annealing,double-step annealing,and triple-step annealing processes were studied.The triple-step annealed magnet exhibits the highest intrinsic coercivity of 19.72 kOe,which is a 58.5%enhancement relative to the as-sintered magnet,and has the best temperature stability of coercivity.The best continuity of grain boundary(GB)phase and the highest content of RE6Fe13Ga phase can be observed in the triple-step annealed magnet,along with relatively small grain size.After triple-step annealing process,the phase separation occurs at the triple-junction(TJ)region of the magnet,which is the Fe-rich phase identified as RE6Fe13Ga and the Fe-poor phase identified as Ia-RE_(2)O_(3).The Ia-RE_(2)O_(3)phase located at the corner of the TJ region can extend between the grains of(Nd,Pr)_(2)Fe_(14)B main phase to form the GB phase with a Fe content of less than 15 at%,thereby enhancing the magnetic isolation effect.The lattice misfit between the Ia-RE_(2)O_(3)phase and the adjacent main phase is less than 5%,which is helpful to reduce defects at the edges of the main phase grains,thus reducing the nucleation of reverse domains.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Large Groups Project under(RGP.2/111/44)。
文摘In this research work,sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles(SrFe_(2)O_(4))with different ratios of terbium(Tb).Different characterization techniques were used to investigate the structural,morphological,dielectric and magnetic properties of the prepared samples.X-ray diffraction(XRD)result suggests that face-centered cube spinel nanocrystalline structure is formed.Crystallite size of the SrFe_(2)O_(4)decreases with rising of Tb ratio.The morphology,shape and size of the SrFe_(2)O_(4)were examined by scanning electron microscopy(SEM)analysis and results reveal inhomogeneous distributions of the nanostructures with high agglomeration.The electrical resistivity of the SrFe_(2)O_(4)increases with rising of Tb ratio,which is confirmed from the cyclic voltammetry.It is observed that dielectric constant of all the samples decreases with the increasing frequency range.It is determined that the dielectric constants of the spinel ferrites are frequency dependent and decrease with increasing the frequency of applied electric field.The magnetic behavior of SrFe_(2)O_(4)with different ratios of Tb was studied and it is found that the saturation magnetization values of samples decrease with increase in the substitution of Tb^(3+)at octahedral sites for Fe^(3+).This decrease in the values of M_(s) is also attributed to spin at surface of nanoparticles.
基金Project supported by the Nature Science Foundation of Shaanxi Province (2023-JC-YB-137)National Natural Science Foundation of China (21901200)。
文摘Structural fine-tuning is of significant importance to enhance the magnetic anisotropy and elucidate the magneto-structural relationship for single molecule magnets(SMMs).For this purpose,two mononuclear Dy^(3+) SMMs:[Dy{HB(pz)3}2(Sal)](1) and [Dy{HB(pz)_(3)}_(2)(MeO-Sal)](2),where HB(pz)_(3)^(-)represents hydro tris(pyrazolyl)borate,Sal denotes salicyiaidehyde and MeO-Sal stands for 5-methoxysalicylaldehyde,were designed and synthesized.Single crystal X-ray diffraction tests show that the two SMMs have very similar eight-coordinated molecule structures,although the introducing of-MeO substituent on salicyiaidehyde ligand induces the changes on the molecule packing mode and the space group.Both the two SMMs have a Dy-O_(aryloxidebond) that is significantly shorter than other Dy-O/N bonds,which defines the orientation of main anisotropy axis of the ground Kramers doublets and engenders the slow relaxation of the magnetization behavior,as evidenced by the magnetic susceptibility and the ab initio calculation.Though with an electron-donating substituent on the axial Sal ligand in 2,the collective magnetic anisotropy is not enhanced and the corresponding magneto-structural relationship is discussed based on the experimental and theoretical calculation results.In addition,as neutral molecules,1 and 2 are soluble in several common organic solvents,like CH_(2)Cl_(2),CHCl_(3),THF and so on.
基金supported by the National Key R&D Program of China(No.2022YFB3505700)the National Natural Science Foundation of China(No.51901079)+4 种基金Guangdong Science and Technology Program(No.2023A0505050145)the Natural Science Foundation of Guangdong Province(Nos.2024A1515030178,2020A1515010736 and 2021A1515010451)Guangzhou Municipal Science and Technology Program(No.202007020008)the Fundamental Research Funds for the Central Universities,the Opening Project of National Engineering Research Center for Powder Metallurgy of Titanium&Rare Metals,the Fundamental Research Funds for the Central Universities and Zhongshan Municipal Science and Technology Program(No.191007102629094)Zhongshan Collaborative Innovation Fund(No.2018C1001).
文摘Sm–Co-based films play an irreplaceable role in special applications due to their high curie temperature and magnetocrystalline anisotropic energy,especially in heat-assisted magnetic recording(HAMR),but the complex composition of Sm–Co phase and unclear synergistic coupling mechanisms of multi-elemental doping become the challenges to enhance the properties.In this work,a novel strategy combining magnetron sputtering and a high-throughput experiment method is applied to solve the above-mentioned problems.Fe/Cu co-doping highly increases the remanence while maintaining a coercivity larger than 26 kOe,leading to an enhancement of the magnetic energy product to 18.1 MGOe.X-ray diffraction(XRD)and high-resolution transmission electron microscope(HRTEM)reveals that SmCo_(5) phase occupies the major fraction,with Co atoms partially substituted by Fe and Cu atoms.In situ Lorentz transmission electron microscopy(LTEM)observations show that the Sm(Co,Cu)5 phase effectively prohibits domain wall motions,leading to an increase of coercivity(H_(c)).Fe doping increases the low saturation magnetization(M_(s))and low remanence(Mr)due to the Fe atom having a higher saturation magnetic moment.The magnetization reversal behaviors are further verified by micromagnetic simulations.Our results suggest that Sm–Co-based films prepared via Fe/Cu co-doping could be a promising candidate for high-performed HAMR in the future.
基金financially supported by the project for the full-time introduction of national high-level innovative technological talents in Hebei province(No.2024HBQZY CXY039)the Funds for Creative Research Groups of China(No.51921001)the Key R&D Program of Jiangxi Province of China(No.20212BBE51019)。
文摘The<001>orientation of the Goss texture aligned with the rolling direction is the most easily magnetized direction,effectively enhancing the magnetic properties of non-oriented silicon steel.In the present study,an ultra-thin high-silicon sheet of 0.2 mm with a strong Goss texture was successfully fabricated using a two-stage rolling method,achieving superior magnetic properties.The combination of suitable primary rolling reduction and intermediate annealing proved beneficial in promoting the formation of Goss texture.Electron back scatter diffraction(EBSD)was used to characterize micro-shear bands within deformed grains of secondary rolled sheets.Observations revealed that the recrystallized Goss nucleus originated from the Goss substructure of shear bands within deformed{111}<112>grains during the initial stages of recrystallization.The influence of stored energy and grain size on texture evolution was thoroughly investigated using quasi-in situ EBSD during recrystallization.In the initial stages,large deformed{111}<112>and near{111}<112>grains with high stored energy facilitated nucleation and growth of Goss and near-Goss grains within shear bands and reduced grain boundary nucleation.In the later stages,large deformed grains with low stored energy underwent a strain-induced grain boundary migration mechanism to nucleate.During the recrystallization,many recrystallized Goss and near-Goss grains clustered together,with Goss grains rotating towards near-Goss orientation.The resulting annealed ultra-thin 0.2 mm sheet with a pronounced Goss texture exhibited superior magnetic properties.
基金Project supported by the Guangxi Natural Science Foundation,China(2024GXNSFAA010415)the Opening Fund of the Key Laboratory of New Processing Technology for Nonferrous Metals&Materials of the Ministry of Education(22AA-9)。
文摘A series of single-phase high-entropy perovskite ceramics(HEPCs)(La_(0.25)Nd_(0.25)Sm_(0.25)Gd_(0.25))_(1-x)Yb_(x)MnO_(3)(x=0.25,0.3,0.35 and 0.4)was synthesized using solid-state reactions.The effect of Yb on the structure and magnetic properties was systematically investigated.The results show that all samples are in orthorhombic perovskite structures with a space group of Pbnm and exhibit a strong crystallization trend sintered at 1300℃for 16 h.All HEPCs have a smooth surface morphology with distinct grain boundaries and exhibit significant hysteresis effects at T=5 K.With the increase of Yb,high lattice distortion and weak double exchange lead to the decrease of T_(C).The presence of Jahn-Teller(JT)distortion and the enhancement of MnO_(6)octahedral distortion result in different magnetic interactions.Moreover,the sample has the best magnetic properties at x=0.35 among the four HEPCs,which is attributed to the large content of Mn^(3+),remnant ratio(Mr/Ms)and lattice distortion(σ^(2)).This work provides a valuable reference for regulating the magnetism of high-entropy ceramics based on rare-earth perovskite manganese oxides.
基金financially supported by the Key research and development project of Shandong province in China(Grant No.2022CXGC020308).
文摘Four types of resins,P1–P4,are used as binders for FeSiBC amorphous powder,which are then press-molded and heat-treated to fabricate magnetic powder cores(MPCs).By testing the permeability,loss,density,and radial crush strength of MPCs,the effect of the binder on the magnetic properties of the cores is investigated and the best resin is found.The results show that the silicone resin P3 exhibits the best thermal stability,retaining 82.1%of its mass after heat treatment at 430°C.This contributes to improving the insulation of MPCs and reducing the eddy current loss,which is 46.06 mW cm^(−3)(150 kHz,20 mT)with the mechanical strength of 11.13 MPa.The bonding of epoxy resin P4 is superior to that of other resins,which significantly improves the powder compactness and makes MPCs density reach 5.67 g cm^(−3),and its permeability is as high as 28.7.The two types of resins have different advantages,and both lead to MPCs with excellent properties.
基金supported by the 2024 Fundamental Research Project(No.LJ212410154007)of the Educational Department of Liaoning Province.
文摘The impact of rare-earth yttrium and cold-rolling reduction rate on the texture evolution and magnetic properties of non-oriented electrical steel is investigated.The experimental results clearly demonstrate that the influencing mechanism of rare-earth yttrium on texture evolution varies at different stages.During the stage of normalization and annealing,the second-phase particles with yttrium precipitate at the grain boundaries of brass-oriented grains,pinning the grain boundaries and inhibiting the development of brass components.During the cold rolling stage,the purification of rare earth yttrium significantly reduces the shear band density of cold-rolled steel.Consequently,the experimental steel with yttrium exhibits larger and more uniform grain size after recrystallization annealing.During the recrystallization stage,the nucleation energy of experimental steel with yttrium is reduced,which facilitates the nucleation of low-energy{100}and{110}grains,and greatly limits the growth of γ-recrystallized grains,forming strong cube and Goss textures after recrystallization annealing.The combination of these effects contributes to the superior magnetic properties of the non-oriented electrical steel with yttrium.The influence of cold rolling reduction rate on the magnetic properties of non-oriented silicon steel needs to be comprehensively considered in terms of the recrystallized grain size,texture,and sample thickness.The samples with higher cold-rolling reduction rate have better magnetic properties due to the reduction in eddy current losses caused by thickness reduction,which offsets the adverse effects of smaller grain size and more γ texture components on magnetic properties.
基金financially supported by the National Natural Science Foundation of China(Nos.52275567 and 52401242)Shanxi province key research and development program(No.202102050201006)+3 种基金the Funds for Local Scientific and Technological Development guided by the Central Government(No.YDZJSX2022A054)the Special Fund for Science and Technology Innovation Teams of Shanxi Province(No.202304051001036)Shanxi Province Basic Research Project(No.202403021221147)the Graduate Education Innovation Program Project of Taiyuan University of Science and Technology(No.BY2023001)
文摘Elemental modulation and heat treatment optimization have emerged as pivotal strategies for enhancing the soft magnetic properties of alloys.We thoroughly examine the impact of microalloyed Co on the amorphous formation ability,thermal stability,and soft magnetic properties of Fe_(80)Co_(x)Si_(7-x)B_(8)P_(4)Cu1(x=0,0.5,1,1.5,2)alloys.The influence of different annealing processes on these properties is analyzed through detailed insights into the evolution of nanocrystalline microstructure and magnetic domain behavior.Our findings indicate that Co addition facilitates the nucleation and growth of the a-Fe(Si,Co)phase while broadening the thermal processing window,thereby significantly improving the alloy’s soft magnetic properties.Notably,the alloy with x=1 undergoes a pre-annealing and reheating process to yield a finer,denser,and more uniform nanocrystalline structure(average grain size D=20.29 nm,grain density Nd=1.5×10^(23)m^(-3)).This refinement enables the formation of broad magnetic domains characterized by 180°domain walls,culminating in exceptional soft magnetic properties,including a high magnetic flux density(B_(s)=1.81 T),high effective permeability(μ_(e)=18,014),and low coercivity(H_(c)=5.57 A m^(-1)).Further,the pinning fields(Hp)for the x=1 alloy are notably low,ranging from15 to 20 A m^(-1),while the maximum effective permeability reaches 69,300.These exceptional properties are directly linked to the alloy’s minimized total free energy(E)and its highly homogeneous microstructure,which collectively suppress magnetic pinning effects.Such characteristics position the x=1 alloy as an exceptional candidate for high-sensitivity applications,particularly in sensor device systems functioning under mild magnetic fields and necessitating swift reaction.
基金financially supported by Guangdong Major Project of Basic and Applied Basic Research,China(No.2019B030302010)the National Natural Science Foundation of China(Nos.52071222,52301212,52101191,52192601,52192602,52192603)+1 种基金the National Key Research and Development Program of China(No.2021YFA0716302)Dongguan Key Research and Development Projects(No.20221200300062).
文摘Owing to the presence of large residual internal stress during cold compaction,it is difficult to optimize the multiple high-frequency magnetic properties of amorphous soft magnetic composites(ASMCs)simultaneously.Here,a surface nanoengineering strategy was proposed to address the above dilemma by constructing a stress buffer layer composed of amorphous nano-particles,between amorphous powder and insulation coating.The amorphous FeSiBCCr@x wt.%FeB(x=0.5,1,3)composite powders with coreshell structures were successfully prepared via an in-situ chemical reduction method.Especially,when the composite ratio of nano-particles is 1 wt.%,the comprehensive properties of the ASMC reach the best balance.Compared with the FeSiBCCr ASMC,the saturation magnetization of the modified ASMC enhances from 153 to 171 emu/g.Meanwhile,the core loss decreases by 28.25%,while the effective permeability increases by 25% and can stabilize to∼20 MHz.Therefore,our work provides a strategy for achieving superior comprehensive soft magnetic properties of ASMCs via surface nanoengineering,which presents enormous application potential in high-frequency electric devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.52275567)the Key Research and Development Program of Shanxi Province,China(Grant No.202202050201020)+3 种基金the Doctoral Starting-up Foundation of Taiyuan University of Science and Technology(Grant No.20192016)the Research Project Supported by Shanxi Scholarship Council(Grant No.2017-085)the Graduate Education and Teaching Reform Project of Shanxi Province,China(Grant No.2023JG136)the Special Fund for Science and Technology Innovation Teams of Shanxi Province,China(Grant No.202304051001036)。
文摘This work investigated the microstructure,magnetic properties,and crystallization kinetics of the as-spun and annealed alloy ribbons of(Fe_(40-x)Co_xNi_(40)Si_(6.33)B_(12.66)Cu_1)_(0.97)Nb_(0.03),where x=0,6,7,8,9,prepared using the meltspinning method.The results show that adding a moderate amount of Co can improve the glass forming ability(GFA),the first peak crystallization temperature,and thermal stability of the as-spun alloy ribbons.With x=7,the two-stage crystallization temperature interval△Tx=90 exhibits optimal thermal stability,and the alloy annealed at 673 K for 10 minutes shows the favorable combined magnetic properties,with H_(c)=0.12 A/m,M_(s)=88.7 A·m^(2)/kg,andμ_(e)=13800.The magnetic domain results show that annealing removes numerous pinning points in the magnetic domains of the alloy ribbons,making the domain walls smoother and effectively reducing the pinning effect.
基金Project supported by the National Key R&D Program of China(2022YFB3505301)the National Key R&D Program of Shanxi Province(202302050201014)+2 种基金the National Natural Science Foundation of China(12304148)the Natural Science Basic Research Program of Shanxi Province(202203021222219)the China Postdoctoral Science Foundation(2023M731452)。
文摘Previous studies have demonstrated that increasing Fe doping content can enhance the saturation magnetization and maximum energy product of 2:17-type Sm-Co rare-earth permanent magnets.Howeve r,syste matic theo retical calculations and the effects of other transition metal dopants have yet to be explored.This study employed first-principles computational methods to investigate the effects of doping with 3d and Zr transition metal elements on the structural stability,magnetic properties,and electronic structure of Sm_(2)Co_(17)permanent magnets.The results indicate that Sc and Zr tend to occupy the Sm-6c site,while Ni,Cu and Zn preferentially occupy the 18h site,and Ti,V,Cr,Mn and Fe primarily occupy the Co-6c site.Except for V and Cu,all other elements effectively improve the structural stability of the doped systems.Additionally,Mn and Fe doping can significantly enhance the total magnetic moment and magnetocrystalline anisotropy energies of the Sm_(2)Co_(17)system,while Cr only increases the total magnetic moment.More importantly,doping with Cr,Mn and Fe within the doping co ntent range of9.8 at%<x<35.29 at% can simultaneously improve the structural stability,total magnetic moment and magnetocrystalline anisotropy energy of the Sm_(2)Co_(17) system.Our study provides valuable theoretical guidance for experimental exploration and is expected to promote the development and application of novel rare-earth permanent magnetic materials.
文摘The Fe_(1−x)Ni_(x)VO_(4)(x=0,0.05,0.10,and 0.20)nanoparticles in this work were successfully synthesized via a co-precipitation method.The structural,magnetic and electrochemical properties of the prepared Fe_(1−x)Ni_(x)VO_(4) nanoparticles were studied as a function of Ni content.The experimental results show that the prepared Ni-doped FeVO_(4) samples have a triclinic structure.Scanning electron microscopy(SEM)images reveal a decrease in average nanoparticle size with increasing Ni content,leading to an enhancement in both specific surface area and magnetization values.X-ray absorption near edge structure(XANES)analysis confirms the substitution of Ni^(2+)ions into Fe^(3+)sites.The magnetic investigation reveals that Ni-doped FeVO_(4) exhibits weak ferromagnetic behavior at room temperature,in contrast to the antiferromagnetic behavior observed in the undoped FeVO_(4).Electrochemical studies demonstrate that the Fe_(0.95)Ni_(0.05)VO_(4) electrode achieves the highest specific capacitance of 334.05 F·g^(−1) at a current density of 1 A·g^(−1),which is attributed to its smallest average pore diameter.In addition,the enhanced specific surface of the Fe_(0.8)Ni_(0.2)VO_(4) electrode is responsible for its outstanding cyclic stability.Overall,our results suggest that the magnetic and electrochemical properties of FeVO_(4) nanoparticles could be effectively tuned by varying Ni doping contents.
