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
Drug hypersensitivity reactions(DHRs),which produce symptoms from skin rash to anaphylaxis,are immune-mediated adverse reactions caused by drug formulations.The diagnosis of DHRs is challenging due to the lack of stan...Drug hypersensitivity reactions(DHRs),which produce symptoms from skin rash to anaphylaxis,are immune-mediated adverse reactions caused by drug formulations.The diagnosis of DHRs is challenging due to the lack of standardization for many drugs,and both underdiagnosis and overdiagnosis hamper the follow-up treatment of patients.Therefore,improved methods for diagnosing patients with suspected DHRs are needed.In this review,we analyzed traditional methods used to diagnose DHRs as well as new diagnostic advances made during the last 2 years.None of the diagnostic methods is perfect,as each exhibits varying sensitivities to different types of DHRs.Overall,our analysis indicates that the accuracy of DHR diagnosis can be improved by obtaining a detailed clinical history,physical examination,in vivo and in vitro testing.展开更多
Allergic dermatological diseases represent a common group of conditions with multifactorial etiologies.Nutrition plays a significant role in the occurrence and prevention of allergy by influencing the inflammatory res...Allergic dermatological diseases represent a common group of conditions with multifactorial etiologies.Nutrition plays a significant role in the occurrence and prevention of allergy by influencing the inflammatory response,gut microbiota,and the barrier function of skin mucosa.The relationship between nutrition(high-fat diet,high-sugar diet,high-salt diet and high-protein diet included)and allergic dermatological diseases is discussed in this article.Also,the potential roles of some nutrients(such as vitamins,minerals and dietary fibers)that have anti-allergic effects in allergic dermatological disease are discussed.Finally,an outlook on the application of nutrition in the treatment of allergic dermatological disease is provided.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
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
Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous...Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.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
Searching for novel ferromagnetic oxides with high Curie temperature(TC)has been one of the main goals for oxide spintronics.The well-known perovskite cobaltate LaCoO_(3) is a classical ferromagnet in its thin-film fo...Searching for novel ferromagnetic oxides with high Curie temperature(TC)has been one of the main goals for oxide spintronics.The well-known perovskite cobaltate LaCoO_(3) is a classical ferromagnet in its thin-film form;however,it suffers from a low TC(~85 K).Here we report a new type of ferromagnetic La-Co-O films with an ultrahigh TC of~820 K.They are fabricated by pulsed laser deposition from a LaCoO_(3) target at low oxygen partial pressures.Detailed structural analysis indicates that they crystallize in terms of the Ruddlesden–Popper phase of La_(2)CoO_(4±x).In sharp contrast to the antiferromagnetism of bulk La_(2)CoO_(4),the strong ferromagnetism in the La_(2)CoO_(4±x) thin films is firmly demonstrated by magnetometry measurements,X-ray magnetic circular dichroism characterization,and magnetotransport experiments.More importantly,density functional theory calculations indicate that the nonstoichiometric oxygen induces an antiferromagnetic-to-ferromagnetic phase transition,accompanied by the orbital reconstruction of Co 3d electrons.Thus,our study provides an attractive strategy for designing or synthesizing exotic magnetic oxides with high ordering temperatures.展开更多
Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a uni...Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a unipolar electric field,the nonvolatile change in magnetization was nearly doubled compared with that obtained utilizing a conventional bipolar bias.Four stable nonvolatile magnetic states were obtained over a broad temperature span,from 320 to 390K,by adjusting the amplitude of the unipolar electric pulses,demonstrating the possibility of realizing a multistate nonvolatile magnetic memory in the FeRh/PMN-PT heterostructures.This work provides a new strategy for enhancing the magnetic response by utilizing unipolar electric fields and promotes the utilization of AFM-FM phase transition materials in multifunctional information storage and novel spintronic devices.展开更多
The discovery and study of skyrmion materials play an important role in basic frontier physics research and future information technology.The database of 196 materials,including 64 skyrmions,was established and predic...The discovery and study of skyrmion materials play an important role in basic frontier physics research and future information technology.The database of 196 materials,including 64 skyrmions,was established and predicted based on machine learning.A variety of intrinsic features are classified to optimize the model,and more than a dozen methods had been used to estimate the existence of skyrmion in magnetic materials,such as support vector machines,k-nearest neighbor,and ensembles of trees.It is found that magnetic materials can be more accurately divided into skyrmion and non-skyrmion classes by using the classification of electronic layer.Note that the rare earths are the key elements affecting the production of skyrmion.The accuracy and reliability of random undersampling bagged trees were 87.5%and 0.89,respectively,which have the potential to build a reliable machine learning model from small data.The existence of skyrmions in LaBaMnO is predicted by the trained model and verified by micromagnetic theory and experiments.展开更多
Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration.Numerous methods have been proposed to optimize the refrigeration properties of calo...Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration.Numerous methods have been proposed to optimize the refrigeration properties of caloric materials,of which single field tuning as a relatively simple way has been systemically studied.However,single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects,like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis.Because of the shortcomings of the caloric effect driven by a single field,multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view.This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials,consisting of enlarging caloric effects,reducing hysteresis losses,adjusting transition temperatures,and widening transition temperature spans,which indicate that further progress can be made in the application of this method.Furthermore,research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms,calling for more attention on multicaloric effects.Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief.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 in part by grants from the Tianshan Innovation Team Fund Project of Xinjiang Uygur Autonomous Region(2023D14005)the General Project of the Natural Science Foundation of the Xinjiang Uygur Autonomous Region(2022D01A109).
文摘Drug hypersensitivity reactions(DHRs),which produce symptoms from skin rash to anaphylaxis,are immune-mediated adverse reactions caused by drug formulations.The diagnosis of DHRs is challenging due to the lack of standardization for many drugs,and both underdiagnosis and overdiagnosis hamper the follow-up treatment of patients.Therefore,improved methods for diagnosing patients with suspected DHRs are needed.In this review,we analyzed traditional methods used to diagnose DHRs as well as new diagnostic advances made during the last 2 years.None of the diagnostic methods is perfect,as each exhibits varying sensitivities to different types of DHRs.Overall,our analysis indicates that the accuracy of DHR diagnosis can be improved by obtaining a detailed clinical history,physical examination,in vivo and in vitro testing.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region Distinguished Young Scholars[2022D01E81]Tianshan Innovation Team Fund Project of Xinjiang Uygur Autonomous Region[2023D14005]Tianshan Talent Fund Project of Xinjiang Uygur Autonomous Region-Youth Science and Technology Talents[2022TSYCCX0109].
文摘Allergic dermatological diseases represent a common group of conditions with multifactorial etiologies.Nutrition plays a significant role in the occurrence and prevention of allergy by influencing the inflammatory response,gut microbiota,and the barrier function of skin mucosa.The relationship between nutrition(high-fat diet,high-sugar diet,high-salt diet and high-protein diet included)and allergic dermatological diseases is discussed in this article.Also,the potential roles of some nutrients(such as vitamins,minerals and dietary fibers)that have anti-allergic effects in allergic dermatological disease are discussed.Finally,an outlook on the application of nutrition in the treatment of allergic dermatological disease is provided.
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 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This work was supported by National Natural Science Foundation of China(Nos.11834012,51620105014,91963207,91963122,51902237)National Key R&D Program of China(No.2018YFB0703603,2019YFA0704900,SQ2018YFE010905)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT 2020e004).EPMA experiments were performed at the Center for Materials Research and Testing of Wuhan University of Technology.The S/TEM work was performed at the Nanostructure Research Center(NRC),which is supported by the Fundamental Research Funds for the Central Universities(WUT:2019III012GX).
文摘Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.
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.
基金Z.Q.L.acknowledges the financial support of the National Key Research and Development Program of China(Nos.2022YFB3506000 and 2022YFA1602701)the National Natural Science Foundation of China(Nos.52271235 and 52121001)Beijing Natural Science Foundation(No.JQ23005).P.X.Q.acknowledges the financial support of the China National Postdoctoral Program for Innovative Talents(No.BX20230451).
文摘Searching for novel ferromagnetic oxides with high Curie temperature(TC)has been one of the main goals for oxide spintronics.The well-known perovskite cobaltate LaCoO_(3) is a classical ferromagnet in its thin-film form;however,it suffers from a low TC(~85 K).Here we report a new type of ferromagnetic La-Co-O films with an ultrahigh TC of~820 K.They are fabricated by pulsed laser deposition from a LaCoO_(3) target at low oxygen partial pressures.Detailed structural analysis indicates that they crystallize in terms of the Ruddlesden–Popper phase of La_(2)CoO_(4±x).In sharp contrast to the antiferromagnetism of bulk La_(2)CoO_(4),the strong ferromagnetism in the La_(2)CoO_(4±x) thin films is firmly demonstrated by magnetometry measurements,X-ray magnetic circular dichroism characterization,and magnetotransport experiments.More importantly,density functional theory calculations indicate that the nonstoichiometric oxygen induces an antiferromagnetic-to-ferromagnetic phase transition,accompanied by the orbital reconstruction of Co 3d electrons.Thus,our study provides an attractive strategy for designing or synthesizing exotic magnetic oxides with high ordering temperatures.
基金supported by the National Key Research and Development Program of China(Grant Nos.2020YFA0711502,2019YFA0704900,2018YFA0305704,and 2017YFB0702704)National Natural Science Foundation of China(Grant Nos.52088101,U1832219,51771223,51971240,and 51671022)+3 种基金China Postdoctoral Science Foundation(Grant No.2021M690346)Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange&Growth Program(Grant Nos.FRF-GF-20-08B,and QNXM20210014)State Key Lab of Advanced Metals and Materials(Grant No.2019-Z11)Key Program and Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB33030200)。
文摘Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a unipolar electric field,the nonvolatile change in magnetization was nearly doubled compared with that obtained utilizing a conventional bipolar bias.Four stable nonvolatile magnetic states were obtained over a broad temperature span,from 320 to 390K,by adjusting the amplitude of the unipolar electric pulses,demonstrating the possibility of realizing a multistate nonvolatile magnetic memory in the FeRh/PMN-PT heterostructures.This work provides a new strategy for enhancing the magnetic response by utilizing unipolar electric fields and promotes the utilization of AFM-FM phase transition materials in multifunctional information storage and novel spintronic devices.
基金This work was supported by the National Natural Science Foundation of China(grant nos.52001012,52088101,and 51925605)the National Key Research and Development Program of China(2021YFB3501202)+6 种基金the Beijing Natural Science Foundation(grant no.2214070)the National Key Research and Development Program of China(2021YFB3501504,2022YFB3505201,2020YFA0711502,and 2019YFA0704900)the National Natural Science Foundation of China(grant nos.92263202 and 51971240)the Heye Health Technology Chong Ming Project(HYCMP-2022002 and HYCMP-2022003)the Natural Science Foundation of Inner Mongolia Autonomous Region(2019MS05040)the Strategic Priority Research Program B(XDB33030200)the Key Program of the Chinese Academy of Sciences(CAS)。
文摘The discovery and study of skyrmion materials play an important role in basic frontier physics research and future information technology.The database of 196 materials,including 64 skyrmions,was established and predicted based on machine learning.A variety of intrinsic features are classified to optimize the model,and more than a dozen methods had been used to estimate the existence of skyrmion in magnetic materials,such as support vector machines,k-nearest neighbor,and ensembles of trees.It is found that magnetic materials can be more accurately divided into skyrmion and non-skyrmion classes by using the classification of electronic layer.Note that the rare earths are the key elements affecting the production of skyrmion.The accuracy and reliability of random undersampling bagged trees were 87.5%and 0.89,respectively,which have the potential to build a reliable machine learning model from small data.The existence of skyrmions in LaBaMnO is predicted by the trained model and verified by micromagnetic theory and experiments.
基金supported by the National Key R&D Program of China(Grant Nos.2020YFA0711502,2021YFB3501202,2019YFA0704900,2018YFA0305704,and 2022YFB3505201)the National Natural Sciences Foundation of China(Grant Nos.52088101,U1832219,51971240,and 52101228)+1 种基金the Strategic Priority Research Program B(Grant No.XDB33030200)the Key Research Program(Grant Nos.ZDRW-CN-2021-3,112111KYSB20180013)of the Chinese Academy of Sciences(CAS).
文摘Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration.Numerous methods have been proposed to optimize the refrigeration properties of caloric materials,of which single field tuning as a relatively simple way has been systemically studied.However,single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects,like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis.Because of the shortcomings of the caloric effect driven by a single field,multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view.This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials,consisting of enlarging caloric effects,reducing hysteresis losses,adjusting transition temperatures,and widening transition temperature spans,which indicate that further progress can be made in the application of this method.Furthermore,research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms,calling for more attention on multicaloric effects.Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief.
