This study presents an experimental investigation of the coupled caloric effect driven by dual-fields in metamagnetic alloy ErCo_(2) with strong magneto-structural coupling.Magnetic measurements were conducted under d...This study presents an experimental investigation of the coupled caloric effect driven by dual-fields in metamagnetic alloy ErCo_(2) with strong magneto-structural coupling.Magnetic measurements were conducted under different pressures,revealing that the application of hydrostatic pressure stabilizes a small volume of paramagnetism(PM) phase,resulting in a shift of the phase transition temperature towards the low-temperature region.This shift is opposite to the temperature associated with the magnetic field-driven phase transition.As pressure increases,the metamagnetic transition in ErCo_(2) is suppressed,and the hysteresis disappears.However,the produced cross-coupling caloric effect compensates the decrease in entropy change caused by the disappearance of the metamagnetic transition.As a result,a reversible giant magnetocaloric effect of 46.2 J/(kg·K) without hysteresis is achieved at a pressure of 0.910 GPa.Moreover,we propose that the temperature span of ErCo_(2) can be significantly widened by optimizing the thermodynamic pathway of the magnetic and pressure fields,overcoming the defect of a narrow temperature range.展开更多
By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to cla...By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.展开更多
CaBaCo_(4)O_(7)has been widely studied because of its distinctive structure and magnetic properties.This study examined the influence of different cooling atmospheres on the structure,magnetic properties,and dielectri...CaBaCo_(4)O_(7)has been widely studied because of its distinctive structure and magnetic properties.This study examined the influence of different cooling atmospheres on the structure,magnetic properties,and dielectric behavior of CaBaCo_(4)O_(7).Samples were cooled under different atmospheric conditions to assess these influences.Our findings indicate that reduced oxygen content leads to increased lattice distortion.Since oxygen atoms play a crucial role in mediating magnetic exchange,oxygen deficiency disrupts long-range magnetic order and promotes short-range antiferromagnetic interactions.Additionally,the cooling atmosphere significantly impacts grain size,thereby affecting the dielectric constant and dielectric loss.In the argon-cooled CaBaCo_(4)O_(7)(Ar)sample,oxygen deficiency reduced dielectric permittivity and increased dielectric loss.展开更多
The melt-spinning technique offers an opportunity for tailoring magnetic properties by controlling the structures and microstructures in both single-phase and composite magnets.This review first broadly discusses the ...The melt-spinning technique offers an opportunity for tailoring magnetic properties by controlling the structures and microstructures in both single-phase and composite magnets.This review first broadly discusses the principle of cooling control,amorphization,crystallization,annealing,and consolidation of the melt-spun ribbons.The phase,microstructure,and magnetic properties of popular single-phase nanocrystalline magnets are reviewed,followed by the nanocomposite magnets consisting of magnetically hard and soft phases.The precipitation-hardened magnetic materials prepared by melt spinning are also discussed.Finally,the role of intergrain exchange coupling,thermal fluctuation,and reversible/irreversible magnetization processes are discussed and correlated to the magnetic phenomena in both single-phase and nanocomposite magnets.展开更多
Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applicati...Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applications at low temperatures.Here,a giant low-field magnetocaloric effect in ferromagnetically ordered Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds was reported,and the magnetic structure was characterized based on low-temperature neutron powder diffraction.With increasing Tm content from 0 to 1,the Curie temperature of Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds decreases from 16.0 K to 3.6 K.For Er_(0.7)Tm_(0.3)Al_(2) compound,it showed the largest low-field magnetic entropy change(–SM)with the peak value of 17.2 and 25.7 J/(kg K)for 0–1 T and 0–2 T,respectively.The(–SM)max up to 17.2 J/(kg K)of Er0.7Tm0.3Al2 compound for 0–1 T is the largest among the intermetallic magnetocaloric materials ever reported at temperatures below 20 K.The peak value of adiabatic temperature change(Tad)max was determined as 4.13 K and 6.87 K for 0–1 T and 0–2 T,respectively.The characteristic of second-order magnetic transitions was confirmed on basis of Arrott plots,the quantitative criterion of exponent n,rescaled universal curves,and the mean-field theory criterion.The outstanding low-field MCE performance with low working temperatures indicates that Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds are promising candidates for magnetic cooling materials at liquid hydrogen and liquid helium temperatures.展开更多
Structural properties of the organic-inorganic hybrid(C_(2)H_(5)NH_(3))_(2)CuCl_(4) have been investigated by means of x-ray powder diffraction and Rietveld analysis. A structural phase transition from Pbca to Aba2 oc...Structural properties of the organic-inorganic hybrid(C_(2)H_(5)NH_(3))_(2)CuCl_(4) have been investigated by means of x-ray powder diffraction and Rietveld analysis. A structural phase transition from Pbca to Aba2 occurs at T_(4)= 240 K, which results in a paraelectric–ferroelectric phase transition. The release of the Jahn–Teller distortion with increasing temperature toward T_(4) is revealed by the structural analysis.展开更多
Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability,and also results in unu...Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability,and also results in unusual phenomena in terms of alloying effects.In the present work,we systematically studied the influence rules of early transition elements on the rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content and explored the related mechanisms.In terms of rapid solidified structure,the additions of early transition elements always inhibit the for-mation of pre-existingα-Fe crystals even eliminate them,and the additions that could produce larger atomic mismatch parameter(δ)and negative mixing enthalpy(△H_(mix))show stronger effects.In terms of nanocrystallization behaviors,the increases inδand negative△H_(mix) weaken the competitive growth between the pre-existing nanocrystals during annealing and then coarsen the nanostructure of the an-nealed alloys and deteriorate their magnetic softness,while the excessive increases inδand negativeHmix could significantly suppress the growth ofα-Fe crystals by diffusion inhibition during annealing and thus remarkable refine the nanostructure of the annealed alloys and improve their magnetic softness.展开更多
Bulk anisotropic Sm_(2)Co_(7) nanocrystalline magnets were successfully prepared by hot deformation process using spark plasma sintering technology.The coercivity of the isotropic Sm_(2)Co_(7) nanocrystalline magnet i...Bulk anisotropic Sm_(2)Co_(7) nanocrystalline magnets were successfully prepared by hot deformation process using spark plasma sintering technology.The coercivity of the isotropic Sm_(2)Co_(7) nanocrystalline magnet is 34.76 kOe,further,the ultra-high coercivity of 50.68 kOe is obtained in the anisotropic hot deformed Sm_(2)Co_(7) magnet when the height reduction is70%,which is much higher than those of the ordinarily produced hot deformed Sm_(2)Co_(7) magnet.X-ray diffraction(XRD)analysis shows that all the samples are Sm_(2)Co_(7) single phase.The investigation by electron backscatter diffraction indicates that increasing the amount of deformation is beneficial to the improvement of the(001) texture of Sm_(2)Co_(7) magnets.The Sm_(2)Co_(7) nanocrystalline magnet generates a strong c-axis crystallographic texture during large deformation process.展开更多
The crystallization behavior and mechanism of CaO–Al2O3–MgO–SiO2(CAMS)-based diopside glass ceramics with nano-ZrO2 nucleators and CeO2 agents have been investigated.The use of nanoscale ZrO2 as nucleators is favor...The crystallization behavior and mechanism of CaO–Al2O3–MgO–SiO2(CAMS)-based diopside glass ceramics with nano-ZrO2 nucleators and CeO2 agents have been investigated.The use of nanoscale ZrO2 as nucleators is favorable to the crystallization of glass ceramic at a relatively lower temperature due to the reduction of the activation energy, while the activation energy is increased after adding the CeO2 agent.The microstructure and orientation have been analyzed by scanning electron microscopy and electron backscatter diffraction.Two discernible layers are observed, featured in glass and crystalline phases, respectively.Remarkably textured polycrystalline diopsides are verified for the samples(A and B)free of CeO2 agents, with c-axes perpendicular to the interface of the two layers.Comparatively, the c-axes of diopside grains of the sample(C) with CeO2 agents are proved to be parallel to the interface.Nanocrystals are detected in the vicinity of the interface for sample C.展开更多
Amorphous Sm-Co films with uniaxial in-plane anisotropy have great potential for application in information-storage media and spintronic materials.The most effective method to produce uniaxial inplane anisotropy is to...Amorphous Sm-Co films with uniaxial in-plane anisotropy have great potential for application in information-storage media and spintronic materials.The most effective method to produce uniaxial inplane anisotropy is to apply an in-plane magnetic field during deposition.However,this method inevitably requires more complex equipment.Here,we report a new way to produce uniaxial in-plane anisotropy by growing amorphous Sm-Co films onto(011)-cut single-crystal substrates in the absence of an external magnetic field.The tunable anisotropy constant,kA,is demonstrated with variation in the lattice parameter of the substrates.A kA value as high as about 3.3×10^4J·m^-3 was obtained in the amorphous Sm-Co film grown on a LaAlO3(011)substrate.Detailed analysis indicated that the preferential seeding and growth of ferromagnetic(FM)domains caused by the anisotropic strain of the substrates,along with the formed Sm-Co,Co-Co directional pair ordering,exert a substantial effect.This work provides a new way to obtain in-plane anisotropy in amorphous Sm-Co films.展开更多
Overcoming the trade-offbetween saturation magnetic induction(B_(s))and coercivity(H_(c))of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-anderror method...Overcoming the trade-offbetween saturation magnetic induction(B_(s))and coercivity(H_(c))of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-anderror methods,which are time-consuming and inefficient.Herein,we present an interpretable machine learning(ML)algorithm for the effective design of advanced FNAs with improved B_(s)and low H_(c).Firstly,the FNAs datasets were established,consisting of 20 features including chemical composition,process parameters,and theoretically calculated parameters.Subsequently,a three-step feature selection was used to screen the key features that affect the B_(s)and H_(c)of FNAs.Among six different ML algorithms,extreme gradient boosting(XGBoost)performed the best in predicting B_(s)and H_(c).We further revealed the association of key features with B_(s)and H_(c)through linear regression and SHAP analysis.The valence electron concentration without Fe,Ni,and Co elements(VEC1)and valence electron concentration(VEC)ranked as the most important features for predicting B_(s)and H_(c),respectively.VEC1 had a positive impact on B_(s)when VEC1<0.78,while VEC had a negative effect on H_(c)when VEC<7.12.Optimized designed FNAs were successfully prepared,and the prediction errors for B_(s)and H_(c)are lower than 2.3%and 18%,respectively,when comparing the predicted and experimental results.These results demonstrate that this ML approach is interpretable and feasible for the design of advanced FNAs with high B_(s)and low H_(c).展开更多
The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental analysis.Based on the first principl...The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental analysis.Based on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was investigated.The experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 K.The magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and discussed.The values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,respectively.As a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.展开更多
Topologically protected magnetic skyrmions are expected to be used in the next-generation spintronic devices.Realizing their nucleation and manipulation at room temperature is fundamental for future practical applicat...Topologically protected magnetic skyrmions are expected to be used in the next-generation spintronic devices.Realizing their nucleation and manipulation at room temperature is fundamental for future practical applications.Here,using in situ Lorentz transmission electron microscopy and micromagnetic simulation,we demonstrate that magnetic biskyrmions can spontaneously exist at room temperature in Nd_(1-x) Tb_(x)Co_(5)(x=0.3,0.5)alloys.The spontaneous biskyrmions are controllably obtained over a wide temperature range across room temperature by switching atomic chemical environment.Furthermore,the density of biskyrmions can be tuned by a small magnetic field.High-density biskyrmions are stimulated to form in the thinner region at room temperature by introducing an in-plane magnetic field component.These results provide valuable insights into the manipulation of topological states,which is of great significance to their practical applications.展开更多
Ion substitution has significantly improved the performance of ferrite magnets,and cobalt remains a key area of research.Studies on the mechanism of Co^(2+)in strontium ferrite,especially SrFe_(2n-x)Co_(x)O_(19-d)(n=6...Ion substitution has significantly improved the performance of ferrite magnets,and cobalt remains a key area of research.Studies on the mechanism of Co^(2+)in strontium ferrite,especially SrFe_(2n-x)Co_(x)O_(19-d)(n=6.1-5.4;x=0.05-0.20)synthesized using the ceramic method,showed that Co^(2+)preferentially enters the lattice as the Fe/Sr ratio decreases.This results in a decrease in the lattice constants a and c due to oxygen vacancies and iron ion deficiency.The impact of Co substitution on morphology is minor compared to the effect of the Fe/Sr ratio.As the Fe/Sr ratio decreases and the Co content increases,the saturation magnetization decreases.The magnetic anisotropy field exhibits a nonlinear change,generally increasing with higher Fe/Sr ratios and Co content.These changes in the performance of permanent magnets are attributed to the absence of Fe^(3+)ions at the 12k+2a and 2b sites and the substitution of Co^(2+)at the 2b site.This suggests that by adjusting the Fe/Sr ratio and appropriate Co substitution,the magnetic anisotropy field of M-type strontium ferrite can be effectively optimized.展开更多
The magnetic and magnetocaloric effects(MCE)of the amorphous RE_(55)Co_(30)Al_(10)Si_(5)(RE=Er and Tm)ribbons were systematically investigated in this paper.Compounds with R=Er and Tm undergo a second-order magnetic p...The magnetic and magnetocaloric effects(MCE)of the amorphous RE_(55)Co_(30)Al_(10)Si_(5)(RE=Er and Tm)ribbons were systematically investigated in this paper.Compounds with R=Er and Tm undergo a second-order magnetic phase transition from ferromagnetic(FM)to paramagnetic(PM)around Curie temperature T_(C)~9.3 K and 3 K,respectively.For Er_(55)Co_(30)Al_(10)Si_(5) compound,an obvious magnetic hysteresis and thermal hysteresis were observed at low field below 6 K,possibly due to spin-glass behavior.Under the field change of 0 T–5 T,the maximum values of magnetic entropy change(-△S_(M)^(max))reach as high as 15.6 J/kg·K and 15.7 J/kg·K for Er_(55)Co_(30)Al_(10)Si_(5) and Tm_(55)Co_(30)Al_(10)Si_(5) compounds,corresponding refrigerant capacity(RC)values are estimated as 303 J/kg and 189 J/kg,respectively.The large MCE makes amorphous RE_(55)Co_(30)Al_(10)Si_(5)(RE=Er and Tm)alloys become very attractive magnetic refrigeration materials in the low-temperature region.展开更多
We investigate the structural,magnetic,and magnetocaloric effects(MCE)of Tm_(1-x)Er_(x)CuAl(x=0.25,0.5,and 0.75)compounds.The compounds undergo a second-order phase transition originating from the ferromagnetic to par...We investigate the structural,magnetic,and magnetocaloric effects(MCE)of Tm_(1-x)Er_(x)CuAl(x=0.25,0.5,and 0.75)compounds.The compounds undergo a second-order phase transition originating from the ferromagnetic to paramagnetic transition around 3.2 K,5 K,and 6 K,respectively.The maximum magnetic entropy changes(-△S_(M)^(max))of Tm_(1-x)Er_(x)CuAl(x=0.25,0.5,and 0.75)are 17.1 J·kg^(-1)·K^(-1),18.1 J·kg^(-1)·K^(-1),and 17.5 J·kg^(-1)·K^(-1)under the magnetic field in the range of 0-2 T,with the corresponding refrigerant capacity(RC)values of 131 J·kg^(-1),136 J·kg^(-1),and 126 J·kg^(-1),respectively.The increase of-△S_(M)^(max)for Tm0.5Er0.5CuAl may be relevant to the change of magnetic moment distribution of Er and stress coming from element substitution.This work provides several compounds that can enrich the family of giant MCE materials in the cryogenic region.展开更多
The magnetization process and corresponding magnetization curve are usually used to analyze the coercivity mechanism of NdFe-B based sintered magnet.However,different demagnetization histories will seriously influence...The magnetization process and corresponding magnetization curve are usually used to analyze the coercivity mechanism of NdFe-B based sintered magnet.However,different demagnetization histories will seriously influence the magnetization curve,leading to an inaccurate understanding and analysis of magnetization process.In this work,we investigated the magnetization behavior of multi-main phase(MMP)magnets with thermal demagnetized and alternating current demagnetized states.Recoil curves of initial magnetization process and demagnetization process of thermal demagnetized magnets reflect the movement of domain walls inside the grains and the magnetization interaction between the grains,respectively.It is noted that the former process cannot represent the magnetization reversal of the entire magnet,which is not appropriate to analyze coercivity mechanism alone.While the recoil curves of both two processes of AC demagnetized magnets can illustrate the magnetization reversal of the entire grains and the interaction between grains.Magneto-optical Kerr microscope shows that the grains of thermal demagnetized magnets are in multi-domain states,and the grains of AC demagnetized magnets are almost in singledomain states.Domain walls of thermal demagnetized magnets move easily within the grains,which is more conducive to magnetization saturation in industrial production.In addition,the minorloops of thermal demagnetized magnets can independently represent the transition of grains from multi-domain to single-domain and the demagnetization of single-domain grains,which is equivalent to characterizing the internal interactions by recoil curves.The investigation of magnetization characteristics of MMP sintered magnets starting from different demagnetized states is helpful to further understand the internal interaction and magnetic hardening mechanism.展开更多
The environmental friendliness and high efficiency of magnetocaloric refrigeration make it a promising substitute for vapor compression refrigeration.However,the common use of heat transfer fluid in conventional passi...The environmental friendliness and high efficiency of magnetocaloric refrigeration make it a promising substitute for vapor compression refrigeration.However,the common use of heat transfer fluid in conventional passive magnetic regenerators(PMRs)and active magnetic regenerators(AMRs)makes only partial materials contribute to the regeneration process,which produces large regeneration loss and greatly limits the regeneration effi-ciency and refrigeration performance at high frequency.Herein,we propose a new conceptual hybrid magnetic regenerator(HMR)composed of multiple solid-state high thermal conductivity materials(HTCMs)and magnetocaloric materials(MCMs),in which both HTCM and MCM elements participate in the regeneration process.This novel working mode could greatly reduce regeneration losses caused by dead volume,pressure losses,and temperature nonuniformity in heat transfer substances to markedly improve regeneration efficiency at high working frequencies.Using the experimentally obtained adiabatic temperature change and magnetic work and with the help of finite element simulation,a maximum temperature of 26 K,a dramatically large cooling power of 8.3 kW/kg,and a maximum ideal exergy efficiency of 54.2%are achieved at the working frequency of 10 Hz for an ideal prototype device of a rotary HMR magnetocaloric refrigerator,which shows potential for achieving an integrative,advanced performance against current AMR/PMR systems.展开更多
The 2:14:1-type rare-earth(RE)-Fe-B permanent magnets prepared by the dual alloy method have been found to possess much superior magnetic properties to those prepared by the single alloy method,providing an appealing ...The 2:14:1-type rare-earth(RE)-Fe-B permanent magnets prepared by the dual alloy method have been found to possess much superior magnetic properties to those prepared by the single alloy method,providing an appealing route to promote the utilization of high-abundance RE elements Ce and La and balance the use of the RE source.However,the relationship between magnetic interactions among different 2:14:1 main phases and superior magnetic properties is still unclear.In this study,we investigated the magnetic interactions and reversal field distribution in these magnets using first-order reversal curve(FORC)images.The FORC images showed that(Nd,Pr)27.8(La,Ce)2.7FebalM1.4B1.0(S-9)and(Nd,Pr)19.5(La,Ce)11.0FebalM1.4B1.0(S-36)have the characteristics of multiple main phases.The reverse magnetic fields corresponding to the soft and hard main phases,as well as the associated exchange coupling,were highly dependent on the La Ce content.The higher the La Ce content,the weaker the exchange coupling and the more asynchronous the demagnetization process.In addition,the FORC images indicated that the magnetization reversal process also varies with La Ce content,where the nucleation and propagation of reversed domains dominant in the S-9 magnet,while the domain propagation in the S-36 magnet is considerably suppressed.Additional micromagnetic simulations also revealed that the coercivity and exchange coupling of multi-main-phase magnets decrease with increasing La Ce content,correlating well with the experimental results.These findings may not only contribute to a better understanding of the complex magnetic interactions between the soft and hard phases and how they affect macroscopic magnetic properties but also help in improving the magnetic performance of the RE-Fe-B magnets with high La Ce content.展开更多
基金supported by the National Key R&D Program of China (2021YFB3501202,2021YFB3501204,2019YFA0704900,2020YFA0711500,2023YFA1406003,2022YFB3505201)the National Natural Science Foundation of China (52088101,U23A20550,92263202,22361132534)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB33030200)。
文摘This study presents an experimental investigation of the coupled caloric effect driven by dual-fields in metamagnetic alloy ErCo_(2) with strong magneto-structural coupling.Magnetic measurements were conducted under different pressures,revealing that the application of hydrostatic pressure stabilizes a small volume of paramagnetism(PM) phase,resulting in a shift of the phase transition temperature towards the low-temperature region.This shift is opposite to the temperature associated with the magnetic field-driven phase transition.As pressure increases,the metamagnetic transition in ErCo_(2) is suppressed,and the hysteresis disappears.However,the produced cross-coupling caloric effect compensates the decrease in entropy change caused by the disappearance of the metamagnetic transition.As a result,a reversible giant magnetocaloric effect of 46.2 J/(kg·K) without hysteresis is achieved at a pressure of 0.910 GPa.Moreover,we propose that the temperature span of ErCo_(2) can be significantly widened by optimizing the thermodynamic pathway of the magnetic and pressure fields,overcoming the defect of a narrow temperature range.
基金supported by the National Natural Science Foun-dation of China(No.52401222)Zhejiang Provincial Natural Sci-ence Foundation(LQN25E010011)+2 种基金Ningbo Natural Science Founda-tion(2024J073)Ningbo Major Special Projects of the Plan“Science and Technology Innovation 2025"(No.2022Z107)Ningbo Key Research and Development Program(No.2023Z097).
文摘By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.
基金Project supported by the Key Research Project of Colleges and Universities of Henan Province(Grant No.23A140017)the Research Project of Department of Science and Technology of Henan Province(Grant No.242102231072)+1 种基金the National Natural Sciences Foundation of China(Grant No.52402336)the special fund of the Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences“New magnetic materials and structural devices for 5G communication”(Grant No.E41602QB01).
文摘CaBaCo_(4)O_(7)has been widely studied because of its distinctive structure and magnetic properties.This study examined the influence of different cooling atmospheres on the structure,magnetic properties,and dielectric behavior of CaBaCo_(4)O_(7).Samples were cooled under different atmospheric conditions to assess these influences.Our findings indicate that reduced oxygen content leads to increased lattice distortion.Since oxygen atoms play a crucial role in mediating magnetic exchange,oxygen deficiency disrupts long-range magnetic order and promotes short-range antiferromagnetic interactions.Additionally,the cooling atmosphere significantly impacts grain size,thereby affecting the dielectric constant and dielectric loss.In the argon-cooled CaBaCo_(4)O_(7)(Ar)sample,oxygen deficiency reduced dielectric permittivity and increased dielectric loss.
基金Project supported by the National Natural Science Foundation of China(Grant No.51590880)National Key Research and Development Program of China(Grant Nos.2014CB643700 and 2016YFB070090)
文摘The melt-spinning technique offers an opportunity for tailoring magnetic properties by controlling the structures and microstructures in both single-phase and composite magnets.This review first broadly discusses the principle of cooling control,amorphization,crystallization,annealing,and consolidation of the melt-spun ribbons.The phase,microstructure,and magnetic properties of popular single-phase nanocrystalline magnets are reviewed,followed by the nanocomposite magnets consisting of magnetically hard and soft phases.The precipitation-hardened magnetic materials prepared by melt spinning are also discussed.Finally,the role of intergrain exchange coupling,thermal fluctuation,and reversible/irreversible magnetization processes are discussed and correlated to the magnetic phenomena in both single-phase and nanocomposite magnets.
基金supported by the National Key Research and Development Program of China(Nos.2021YFB3501202 and 2019YFB2005800)the Science Center of the National Science Foundation of China(No.52088101)+1 种基金the National Natural Science Foundation of China(Nos.51871019,52171170,52130103,51961145305,51971026,and 52171169)the Beijing Natural Science Foundation Key Program(Grant Nos.Z190007 and Z200007),and“111 Project”(No.B170003).
文摘Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applications at low temperatures.Here,a giant low-field magnetocaloric effect in ferromagnetically ordered Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds was reported,and the magnetic structure was characterized based on low-temperature neutron powder diffraction.With increasing Tm content from 0 to 1,the Curie temperature of Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds decreases from 16.0 K to 3.6 K.For Er_(0.7)Tm_(0.3)Al_(2) compound,it showed the largest low-field magnetic entropy change(–SM)with the peak value of 17.2 and 25.7 J/(kg K)for 0–1 T and 0–2 T,respectively.The(–SM)max up to 17.2 J/(kg K)of Er0.7Tm0.3Al2 compound for 0–1 T is the largest among the intermetallic magnetocaloric materials ever reported at temperatures below 20 K.The peak value of adiabatic temperature change(Tad)max was determined as 4.13 K and 6.87 K for 0–1 T and 0–2 T,respectively.The characteristic of second-order magnetic transitions was confirmed on basis of Arrott plots,the quantitative criterion of exponent n,rescaled universal curves,and the mean-field theory criterion.The outstanding low-field MCE performance with low working temperatures indicates that Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds are promising candidates for magnetic cooling materials at liquid hydrogen and liquid helium temperatures.
基金supported by the National Natural Science Foundation of China (Grant No. 51925605)Fujian Institute of Innovation,Chinese Academy of Sciences(Grant No. FJCXY18040303)the Youth Innovation Promotion of the Chinese Academy of Sciences (Grant No. 2013004)。
文摘Structural properties of the organic-inorganic hybrid(C_(2)H_(5)NH_(3))_(2)CuCl_(4) have been investigated by means of x-ray powder diffraction and Rietveld analysis. A structural phase transition from Pbca to Aba2 occurs at T_(4)= 240 K, which results in a paraelectric–ferroelectric phase transition. The release of the Jahn–Teller distortion with increasing temperature toward T_(4) is revealed by the structural analysis.
基金supported by the National Key R&D Program of China(No.2021YFB3803004)the National Natural Science Foundation of China(Nos.52101239 and 52171153)+4 种基金Ningbo Natural Science Foundation(No.2021J222)the“Pioneer”R&D Program of Zhejiang Province(No.2023C01075)Youth Innovation Promotion Association CAS(No.2021294)Zhejiang Provincial Key Research and Development Projects(No.2021C01033)CITIC Group Major Science and Technology Innovation Project(HT-FZB-2022190).
文摘Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability,and also results in unusual phenomena in terms of alloying effects.In the present work,we systematically studied the influence rules of early transition elements on the rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content and explored the related mechanisms.In terms of rapid solidified structure,the additions of early transition elements always inhibit the for-mation of pre-existingα-Fe crystals even eliminate them,and the additions that could produce larger atomic mismatch parameter(δ)and negative mixing enthalpy(△H_(mix))show stronger effects.In terms of nanocrystallization behaviors,the increases inδand negative△H_(mix) weaken the competitive growth between the pre-existing nanocrystals during annealing and then coarsen the nanostructure of the an-nealed alloys and deteriorate their magnetic softness,while the excessive increases inδand negativeHmix could significantly suppress the growth ofα-Fe crystals by diffusion inhibition during annealing and thus remarkable refine the nanostructure of the annealed alloys and improve their magnetic softness.
基金Project supports by the Science Center of the National Natural Science Foundation of China(Grant No.52088101)the National Natural Foundation of China(Grant No.51590880)+2 种基金the Fujian Institute of Innovation,Chinese Academy of Sciences(Grant No.FJCXY18040302)the Key Program of the Chinese Academy of Sciences(Grant No.KJZD-EW-M05-1)the Natural Science Foundation of Inner Mongolia,China(Grant Nos.2018LH05006 and2018LH05011)。
文摘Bulk anisotropic Sm_(2)Co_(7) nanocrystalline magnets were successfully prepared by hot deformation process using spark plasma sintering technology.The coercivity of the isotropic Sm_(2)Co_(7) nanocrystalline magnet is 34.76 kOe,further,the ultra-high coercivity of 50.68 kOe is obtained in the anisotropic hot deformed Sm_(2)Co_(7) magnet when the height reduction is70%,which is much higher than those of the ordinarily produced hot deformed Sm_(2)Co_(7) magnet.X-ray diffraction(XRD)analysis shows that all the samples are Sm_(2)Co_(7) single phase.The investigation by electron backscatter diffraction indicates that increasing the amount of deformation is beneficial to the improvement of the(001) texture of Sm_(2)Co_(7) magnets.The Sm_(2)Co_(7) nanocrystalline magnet generates a strong c-axis crystallographic texture during large deformation process.
基金Project supported by the National Natural Sciences Foundation of China(Grant No.51590881)the National Key Research Program of China(Grant No.2016YFB0700903)+1 种基金the Inner Mongolia Science and Technology Major Project of China 2016the Fujian Institute of Innovation,Chinese Academy of Sciences(Grant No.FJCXY18040302)
文摘The crystallization behavior and mechanism of CaO–Al2O3–MgO–SiO2(CAMS)-based diopside glass ceramics with nano-ZrO2 nucleators and CeO2 agents have been investigated.The use of nanoscale ZrO2 as nucleators is favorable to the crystallization of glass ceramic at a relatively lower temperature due to the reduction of the activation energy, while the activation energy is increased after adding the CeO2 agent.The microstructure and orientation have been analyzed by scanning electron microscopy and electron backscatter diffraction.Two discernible layers are observed, featured in glass and crystalline phases, respectively.Remarkably textured polycrystalline diopsides are verified for the samples(A and B)free of CeO2 agents, with c-axes perpendicular to the interface of the two layers.Comparatively, the c-axes of diopside grains of the sample(C) with CeO2 agents are proved to be parallel to the interface.Nanocrystals are detected in the vicinity of the interface for sample C.
基金supported by the National Key Research and Development Program of China(2017YFB0702702,2018YFA0305704,2016YFB700903,2017YFA0303601,and 2017YFA0206300)the National Natural Sciences Foundation of China(51531008,51771223,51590880,11674378,51971240,U1832219,and 11934016)+2 种基金the Inner Mongolia Science and Technology Major Project of China 2016the Strategic Priority Research Program(B)Key Programof the Chinese Academy of Sciences(CAS).
文摘Amorphous Sm-Co films with uniaxial in-plane anisotropy have great potential for application in information-storage media and spintronic materials.The most effective method to produce uniaxial inplane anisotropy is to apply an in-plane magnetic field during deposition.However,this method inevitably requires more complex equipment.Here,we report a new way to produce uniaxial in-plane anisotropy by growing amorphous Sm-Co films onto(011)-cut single-crystal substrates in the absence of an external magnetic field.The tunable anisotropy constant,kA,is demonstrated with variation in the lattice parameter of the substrates.A kA value as high as about 3.3×10^4J·m^-3 was obtained in the amorphous Sm-Co film grown on a LaAlO3(011)substrate.Detailed analysis indicated that the preferential seeding and growth of ferromagnetic(FM)domains caused by the anisotropic strain of the substrates,along with the formed Sm-Co,Co-Co directional pair ordering,exert a substantial effect.This work provides a new way to obtain in-plane anisotropy in amorphous Sm-Co films.
基金supported by the National Key R&D Program of China(Grant No.2022YFB2404101)the“Pioneer”R&D Programof Zhejiang Province(No.2023C01075)+1 种基金the Youth Innovation Promotion Association CAS(Grant No.2021294)the Ningbo Natural Science Foundation(No.2021J197).
文摘Overcoming the trade-offbetween saturation magnetic induction(B_(s))and coercivity(H_(c))of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-anderror methods,which are time-consuming and inefficient.Herein,we present an interpretable machine learning(ML)algorithm for the effective design of advanced FNAs with improved B_(s)and low H_(c).Firstly,the FNAs datasets were established,consisting of 20 features including chemical composition,process parameters,and theoretically calculated parameters.Subsequently,a three-step feature selection was used to screen the key features that affect the B_(s)and H_(c)of FNAs.Among six different ML algorithms,extreme gradient boosting(XGBoost)performed the best in predicting B_(s)and H_(c).We further revealed the association of key features with B_(s)and H_(c)through linear regression and SHAP analysis.The valence electron concentration without Fe,Ni,and Co elements(VEC1)and valence electron concentration(VEC)ranked as the most important features for predicting B_(s)and H_(c),respectively.VEC1 had a positive impact on B_(s)when VEC1<0.78,while VEC had a negative effect on H_(c)when VEC<7.12.Optimized designed FNAs were successfully prepared,and the prediction errors for B_(s)and H_(c)are lower than 2.3%and 18%,respectively,when comparing the predicted and experimental results.These results demonstrate that this ML approach is interpretable and feasible for the design of advanced FNAs with high B_(s)and low H_(c).
基金supported by the National Key Research and Development Program of China (2021YFB3501204)the National Science Foundation for Excellent Young Scholars (52222107)+2 种基金the National Science Foundation for Distinguished Young Scholars (51925605)the National Natural Science Foundation of China (52171195)Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences (E055B002)。
文摘The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental analysis.Based on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was investigated.The experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 K.The magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and discussed.The values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,respectively.As a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.
基金supported by the Science Center of the Na-tional Science Foundation of China(Grant No.52088101)the Na-tional Natural Science Foundation of China(Grant Nos.52121001,52001019,52271195,52101210,and 52130103)+2 种基金the National Key and Development Program of China(Grant Nos.2021YFB3501600,2022YFB3505302)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant Nos.XDB33030100,XDB33030200)Youth Innovation Promotion Association(No.CAS Y201903).
文摘Topologically protected magnetic skyrmions are expected to be used in the next-generation spintronic devices.Realizing their nucleation and manipulation at room temperature is fundamental for future practical applications.Here,using in situ Lorentz transmission electron microscopy and micromagnetic simulation,we demonstrate that magnetic biskyrmions can spontaneously exist at room temperature in Nd_(1-x) Tb_(x)Co_(5)(x=0.3,0.5)alloys.The spontaneous biskyrmions are controllably obtained over a wide temperature range across room temperature by switching atomic chemical environment.Furthermore,the density of biskyrmions can be tuned by a small magnetic field.High-density biskyrmions are stimulated to form in the thinner region at room temperature by introducing an in-plane magnetic field component.These results provide valuable insights into the manipulation of topological states,which is of great significance to their practical applications.
基金support from the Research Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(Grant No.E355B001)Key Research Program of the Chinese Academy of Sciences(Grant No.ZDRW-CN-2021-3)Science Center of the National Natural Science Foundation of China(Grant No.52088101).
文摘Ion substitution has significantly improved the performance of ferrite magnets,and cobalt remains a key area of research.Studies on the mechanism of Co^(2+)in strontium ferrite,especially SrFe_(2n-x)Co_(x)O_(19-d)(n=6.1-5.4;x=0.05-0.20)synthesized using the ceramic method,showed that Co^(2+)preferentially enters the lattice as the Fe/Sr ratio decreases.This results in a decrease in the lattice constants a and c due to oxygen vacancies and iron ion deficiency.The impact of Co substitution on morphology is minor compared to the effect of the Fe/Sr ratio.As the Fe/Sr ratio decreases and the Co content increases,the saturation magnetization decreases.The magnetic anisotropy field exhibits a nonlinear change,generally increasing with higher Fe/Sr ratios and Co content.These changes in the performance of permanent magnets are attributed to the absence of Fe^(3+)ions at the 12k+2a and 2b sites and the substitution of Co^(2+)at the 2b site.This suggests that by adjusting the Fe/Sr ratio and appropriate Co substitution,the magnetic anisotropy field of M-type strontium ferrite can be effectively optimized.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52171195 and 52171054)the National Natural Science Foundation for Distinguished Young Scholars(Grant No.51925605)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.YJKYYQ20200042)。
文摘The magnetic and magnetocaloric effects(MCE)of the amorphous RE_(55)Co_(30)Al_(10)Si_(5)(RE=Er and Tm)ribbons were systematically investigated in this paper.Compounds with R=Er and Tm undergo a second-order magnetic phase transition from ferromagnetic(FM)to paramagnetic(PM)around Curie temperature T_(C)~9.3 K and 3 K,respectively.For Er_(55)Co_(30)Al_(10)Si_(5) compound,an obvious magnetic hysteresis and thermal hysteresis were observed at low field below 6 K,possibly due to spin-glass behavior.Under the field change of 0 T–5 T,the maximum values of magnetic entropy change(-△S_(M)^(max))reach as high as 15.6 J/kg·K and 15.7 J/kg·K for Er_(55)Co_(30)Al_(10)Si_(5) and Tm_(55)Co_(30)Al_(10)Si_(5) compounds,corresponding refrigerant capacity(RC)values are estimated as 303 J/kg and 189 J/kg,respectively.The large MCE makes amorphous RE_(55)Co_(30)Al_(10)Si_(5)(RE=Er and Tm)alloys become very attractive magnetic refrigeration materials in the low-temperature region.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52171195,and 52171054)the National Science Foundation for Distinguished Young Scholars(Grant No.51925605)the Scientific Instrument Developing Project of Chinese Academy of Sciences(Grant No.YJKYYQ20200042)
文摘We investigate the structural,magnetic,and magnetocaloric effects(MCE)of Tm_(1-x)Er_(x)CuAl(x=0.25,0.5,and 0.75)compounds.The compounds undergo a second-order phase transition originating from the ferromagnetic to paramagnetic transition around 3.2 K,5 K,and 6 K,respectively.The maximum magnetic entropy changes(-△S_(M)^(max))of Tm_(1-x)Er_(x)CuAl(x=0.25,0.5,and 0.75)are 17.1 J·kg^(-1)·K^(-1),18.1 J·kg^(-1)·K^(-1),and 17.5 J·kg^(-1)·K^(-1)under the magnetic field in the range of 0-2 T,with the corresponding refrigerant capacity(RC)values of 131 J·kg^(-1),136 J·kg^(-1),and 126 J·kg^(-1),respectively.The increase of-△S_(M)^(max)for Tm0.5Er0.5CuAl may be relevant to the change of magnetic moment distribution of Er and stress coming from element substitution.This work provides several compounds that can enrich the family of giant MCE materials in the cryogenic region.
基金supported by the National Natural Science Foundation of China(Grant No.52371169)the National Natural Science Foundation of China(Grant Nos.52088101,52001012,12204268,and 92263202)+6 种基金the National Key R&D Program of China(Grant No.2023YFA1610400)the“Leading Goose”R&D Program of Zhejiang Province(Grant No.2022C01110)the Challenge-led projects of China Rare Earth Group(Grant No.ZXKCJBGS-202405-06)the Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20230329)the Young Elite Scientists Sponsorship Program by BAST(Grant No.BYESS2023302)the National Key R&D Program of China(Grant Nos.2021YFB3501202,2022YFB3505201,and 2019YFA0704900)the Strategic Priority Research Program B of Chinese Academy of Sciences(Grant No.XDB33030200)。
文摘The magnetization process and corresponding magnetization curve are usually used to analyze the coercivity mechanism of NdFe-B based sintered magnet.However,different demagnetization histories will seriously influence the magnetization curve,leading to an inaccurate understanding and analysis of magnetization process.In this work,we investigated the magnetization behavior of multi-main phase(MMP)magnets with thermal demagnetized and alternating current demagnetized states.Recoil curves of initial magnetization process and demagnetization process of thermal demagnetized magnets reflect the movement of domain walls inside the grains and the magnetization interaction between the grains,respectively.It is noted that the former process cannot represent the magnetization reversal of the entire magnet,which is not appropriate to analyze coercivity mechanism alone.While the recoil curves of both two processes of AC demagnetized magnets can illustrate the magnetization reversal of the entire grains and the interaction between grains.Magneto-optical Kerr microscope shows that the grains of thermal demagnetized magnets are in multi-domain states,and the grains of AC demagnetized magnets are almost in singledomain states.Domain walls of thermal demagnetized magnets move easily within the grains,which is more conducive to magnetization saturation in industrial production.In addition,the minorloops of thermal demagnetized magnets can independently represent the transition of grains from multi-domain to single-domain and the demagnetization of single-domain grains,which is equivalent to characterizing the internal interactions by recoil curves.The investigation of magnetization characteristics of MMP sintered magnets starting from different demagnetized states is helpful to further understand the internal interaction and magnetic hardening mechanism.
基金supported by the National Key Research and Development Program of China(grant nos.2021YFB3501202,2020YFA0711500,2019YFA0704900,and 2023YFA1406003)the National Natural Science Foundation of China(grant nos.52088101,92263202,U23A20550,and 22361132534)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB33030200)The authors are highly grateful to Prof.Bing Li of IMR CAS for providing the thermal conductivity materials of ALCs.A portion of this work was carried out at the Synergetic Extreme Condition User Facility(SECUF)。
文摘The environmental friendliness and high efficiency of magnetocaloric refrigeration make it a promising substitute for vapor compression refrigeration.However,the common use of heat transfer fluid in conventional passive magnetic regenerators(PMRs)and active magnetic regenerators(AMRs)makes only partial materials contribute to the regeneration process,which produces large regeneration loss and greatly limits the regeneration effi-ciency and refrigeration performance at high frequency.Herein,we propose a new conceptual hybrid magnetic regenerator(HMR)composed of multiple solid-state high thermal conductivity materials(HTCMs)and magnetocaloric materials(MCMs),in which both HTCM and MCM elements participate in the regeneration process.This novel working mode could greatly reduce regeneration losses caused by dead volume,pressure losses,and temperature nonuniformity in heat transfer substances to markedly improve regeneration efficiency at high working frequencies.Using the experimentally obtained adiabatic temperature change and magnetic work and with the help of finite element simulation,a maximum temperature of 26 K,a dramatically large cooling power of 8.3 kW/kg,and a maximum ideal exergy efficiency of 54.2%are achieved at the working frequency of 10 Hz for an ideal prototype device of a rotary HMR magnetocaloric refrigerator,which shows potential for achieving an integrative,advanced performance against current AMR/PMR systems.
基金supported by the Beijing Natural Science Foundation(Grant No.2214070)Science Center of the National Science Foundation of China(Grant No.52088101)+6 种基金National Natural Science Foundation of China(Grant Nos.52001012,51901057,U1832219,51771223,and 51971240)Heye Chongming Project(Grant No.HYCMP-2021001)National Key Research and Development Program of China(Grant Nos.2021YFB3501202,2021YFB35015043,2020YFA0711502,2019YFA0704900,2018YFA0305704,and 2017YFA0303601)Key Projects of Capacity Construction of Science and Technology Innovation Service(Grant No.19002020124)Beijing Talent Training Quality Construction Project(Grant No.19008021064)Strategic Priority Research Program B(Grant No.XDB33030200)Key Program of the Chinese Academy of Sciences(CAS)。
文摘The 2:14:1-type rare-earth(RE)-Fe-B permanent magnets prepared by the dual alloy method have been found to possess much superior magnetic properties to those prepared by the single alloy method,providing an appealing route to promote the utilization of high-abundance RE elements Ce and La and balance the use of the RE source.However,the relationship between magnetic interactions among different 2:14:1 main phases and superior magnetic properties is still unclear.In this study,we investigated the magnetic interactions and reversal field distribution in these magnets using first-order reversal curve(FORC)images.The FORC images showed that(Nd,Pr)27.8(La,Ce)2.7FebalM1.4B1.0(S-9)and(Nd,Pr)19.5(La,Ce)11.0FebalM1.4B1.0(S-36)have the characteristics of multiple main phases.The reverse magnetic fields corresponding to the soft and hard main phases,as well as the associated exchange coupling,were highly dependent on the La Ce content.The higher the La Ce content,the weaker the exchange coupling and the more asynchronous the demagnetization process.In addition,the FORC images indicated that the magnetization reversal process also varies with La Ce content,where the nucleation and propagation of reversed domains dominant in the S-9 magnet,while the domain propagation in the S-36 magnet is considerably suppressed.Additional micromagnetic simulations also revealed that the coercivity and exchange coupling of multi-main-phase magnets decrease with increasing La Ce content,correlating well with the experimental results.These findings may not only contribute to a better understanding of the complex magnetic interactions between the soft and hard phases and how they affect macroscopic magnetic properties but also help in improving the magnetic performance of the RE-Fe-B magnets with high La Ce content.
