The magnetic properties and magnetocaloric effects (MCE) of HoNiGa compound are investigated systematically. The HoNiGa exhibits a weak antiferromagnetic (AFM) ground state below the Neel temperature TN of 10 K, a...The magnetic properties and magnetocaloric effects (MCE) of HoNiGa compound are investigated systematically. The HoNiGa exhibits a weak antiferromagnetic (AFM) ground state below the Neel temperature TN of 10 K, and the AFM ordering could be converted into ferromagnetic (FM) ordering by external magnetic field. Moreover, the fie/d-induced FM phase exhibits a high saturation magnetic moment and a large change of magnetization around the transition temperature, which then result in a large MCE. A large -△SM of 22.0 J/kg K and a high RC value of 279 J/kg without magnetic hysteresis are obtained for a magnetic field change of 5 T, which are comparable to or even larger than those of some other magnetic refrigerant materials in the same temperature range. Besides, the μ0H2/3 dependence of |△SPKM| well follows the linear fitting according to the mean-field approximation, suggesting the nature of second-order FM-PM magnetic transition under high magnetic fields. The large reversible MCE induced by metamagnetic transition suggests that HoNiGa compound could be a promising material for magnetic refrigeration in low temperature range.展开更多
A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_...A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.展开更多
HoBi single crystal and polycrystalline compounds with Na Cl-type structure are successfully obtained,and their magnetic and magnetocaloric properties are studied in detail.With temperature increasing,Ho Bi compound u...HoBi single crystal and polycrystalline compounds with Na Cl-type structure are successfully obtained,and their magnetic and magnetocaloric properties are studied in detail.With temperature increasing,Ho Bi compound undergoes two magnetic transitions at 3.7 K and 6 K,respectively.The transition temperature at 6 K is recognized as an antiferromagneticto-paramagnetic(AFM–PM)transition,which belongs to the first-order magnetic phase transition(FOMT).It is interesting that the Ho Bi compound with FOMT exhibits good thermal and magnetic reversibility.Furthermore,a large inverse and normal magnetocaloric effect(MCE)is found in Ho Bi single crystal in the H||[100]direction,and the positive?SMpeak reaches 13.1 J/kg·K under a low field change of 2 T and the negative?S_(M)peak arrives at-18 J/kg·K under a field change of5 T.These excellent properties are expected to be applied to some magnetic refrigerators with special designs and functions.展开更多
The magnetocaloric effect(MCE) in EuCu1.75P2 compound is studied by the magnetization and heat capacity measurements.Magnetization and modified Arrott plots indicate that the compound undergoes a second-order phase ...The magnetocaloric effect(MCE) in EuCu1.75P2 compound is studied by the magnetization and heat capacity measurements.Magnetization and modified Arrott plots indicate that the compound undergoes a second-order phase transition at TC ~ 51 K.A large reversible MCE is observed around TC.The values of maximum magnetic entropy change(-△SxMma) reach 5.6 J·kg^-1·K-1 and 13.3 J·kg^-1·K-1 for the field change of 2 T and 7 T,respectively,with no obvious hysteresis loss in the vicinity of Curie temperature.The corresponding maximum adiabatic temperature changes(△Tadmax) are evaluated to be 2.1 K and 5.0 K.The magnetic transition and the origin of large MCE in EuCu1.75P2 are also discussed.展开更多
The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably, resulting in the magnetost...The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably, resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil_χFexGe alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe, metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil-xFezGe alloys at temperature below the structural transition temperature.展开更多
We have studied the magnetic and magnetocaloric properties of the Er3Co compound, which undergoes ferromagnetic ordering below the Curie temperature Tc = 13 K. It is found by fitting the isothermal magnetization curve...We have studied the magnetic and magnetocaloric properties of the Er3Co compound, which undergoes ferromagnetic ordering below the Curie temperature Tc = 13 K. It is found by fitting the isothermal magnetization curves that the Landau model is appropriate to describe the Er3Co compound. The giant magnetocaloric effect (MCE) without hysteresis loss around Tc is found to result from the second-order ferromagnetic-to-paramagnetic transition. The max- imal value of magnetic entropy change is 24.5 J/kg.K with a refrigerant capacity (RC) value of 476 J/kg for a field change of 0-5 T. Large reversible MEC and RC indicate the potentiality of Er3Co as a candidate magnetic refrigerant at low temperatures.展开更多
The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively in- vestigated during the last two decades, not only due to their potential applications for magnetic refr...The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively in- vestigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s) (Zn, Mg, and Cd). Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi2B2C superconductors is also presented.展开更多
In this article, our recent progress concerning the effects of atomic substitution, magnetic field, and temperature on the magnetic and magnetocaloric properties of the LaFe13-xAlx compounds are reviewed. With an incr...In this article, our recent progress concerning the effects of atomic substitution, magnetic field, and temperature on the magnetic and magnetocaloric properties of the LaFe13-xAlx compounds are reviewed. With an increase of the aluminum content, the compounds exhibit successively an antiferromagnetic (AFM) state, a ferromagnetic (FM) state, and a mictomagnetic state. Furthermore, the AFM coupling of LaFe13 -xAlx can be converted to an FM one by substituting Si for A1, Co for Fe, and magnetic rare-earth R for La, or introducing interstitial C or H atoms. However, low doping levels lead to FM clusters embedded in an AFM matrix, and the resultant compounds can undergo, under appropriate applied fields, first an AFM-FM and then an FM-AFM phase transition while heated, with significant magnetic relaxation in the vicinity of the transition temperature. The Curie temperature of LaFe13-xAlx can be shifted to room temperature by choosing appropriate contents of Co, C, or H, and a strong magnetocaloric effect can be obtained around the transition temperature. For example, for the LaFel 1.5All.5Co.2Hl.o compound, the maximal entropy change reaches 13.8 J.kg-1.K-1 for a field change of 0-5 T, occurring around room temperature. It is 42% higher than that of Gd, and therefore, this compound is a promising room-temperature magnetic refrigerant.展开更多
The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and un...The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and undergo a second order transition from spin glass(SG) state to paramagnetic(PM) state. The spin glass transition temperatures T_g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures(θp) for Ho_5 Pd_2,(Ho_(0.75) Y_(0.25)_5 Pd_2, and(Ho_(0.5) Y_(0.5))_5 Pd_2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments(μeff) are10.8 μB/Ho, 10.3 μB/RE, and 7.5 μB/RE, respectively. Magnetocaloric effect(MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change-?SMof the(Ho_(1-x)Y_x)_5 Pd_2(x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J·kg^(-1)·K^(-1), 11.1 J·kg^(-1)·K^(-1), and 8.9 K J·kg^(-1)·K^(-1), with corresponding refrigerant capacity values of 382.3 J·kg^(-1), 336.2 J·kg^(-1), and 242.5 J·kg^(-1), respectively.展开更多
Magnetic properties and magnetocaloric effect in TbCo2-xFex compounds are studied by DC magnetic measurement. With increasing content of Fe, the entropy changes decrease slightly, though the Curie temperature is tuned...Magnetic properties and magnetocaloric effect in TbCo2-xFex compounds are studied by DC magnetic measurement. With increasing content of Fe, the entropy changes decrease slightly, though the Curie temperature is tuned from 231 K (x = 0) to 303 K (x = 0.1). Magnetic entropies of TbCo2 compound are calculated by using mean field approximation (MFA). Results estimated by using Maxwell relation are consistent with that of MFA calculation. It is shown that the entropy changes are mainly derived from the magnetic entropy changes. The lattice has almost no contribution to the entropy change in the vicinity of phase transition.展开更多
The crystal structure, itinerant-electron metamagnetic transition (IEMT) and magnetocaloric effect (MCE) in the iron-based rare-earth intermetallic compound La0.8Ce0.2Fe11.4Si1.6 have been investi- gated. The powder X...The crystal structure, itinerant-electron metamagnetic transition (IEMT) and magnetocaloric effect (MCE) in the iron-based rare-earth intermetallic compound La0.8Ce0.2Fe11.4Si1.6 have been investi- gated. The powder X-ray diffraction revealed that the ingot of La0.8Ce0.2Fe11.4Si1.6 annealed at 1373 K in vacuum for only 5 days could be crystallized in the cubic NaZn13-type structure. The La0.8Ce0.2Fe11.4Si1.6 compound exhibited giant values of the isothermal entropy change ?SM around the Curie temperature TC (about 186 K). And the maximum value ΔS M max is about 78.29 J/(kg·K) under a field change of 0—3 T, which can be calculated by the magnetization iso- therms around TC. Such a large MCE is attributed to the sharp change of magnetization and susceptibility around TC and the first-order magnetic transition of field-induced IEMT above TC.展开更多
Magnetic properties and magnetocaloric effects(MCEs) of the HoPdAl compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated.Both the compounds are found to be antiferromagn...Magnetic properties and magnetocaloric effects(MCEs) of the HoPdAl compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated.Both the compounds are found to be antiferromagnet with the Néel temperature TN=12 and 10 K,respectively.A field-induced metamagnetic transition from antiferromagnetic(AFM) state to ferromagnetic(FM) state is observed below TN.For the hexagonal HoPdAl,a small magnetic field can induce an FM-like state due to a weak AFM coupling,which leads to a high saturation magnetization and gives rise to a large MCE around TN.The maximal value of magnetic entropy change(?SM) is-20.6 J/kg K with a refrigerant capacity(RC) value of 386 J/kg for a field change of 0-5 T.For the orthorhombic HoPdAl,the critical field required for metamagnetic transition is estimated to be about 1.5 T,showing a strong AFM coupling.However,the maximal SM value is still-13.7 J/kg K around TN for a field change of 0-5 T.The large reversible SM and considerable RC suggest that HoPdAl may be an appropriate candidate for magnetic refrigerant in a low temperature range.展开更多
The magnetocaloric effect(MCE) of RT Si and RT Al systems with R = Gd–Tm, T = Fe–Cu and Pd, which have been widely investigated in recent years, is reviewed. It is found that these RT X compounds exhibit various c...The magnetocaloric effect(MCE) of RT Si and RT Al systems with R = Gd–Tm, T = Fe–Cu and Pd, which have been widely investigated in recent years, is reviewed. It is found that these RT X compounds exhibit various crystal structures and magnetic properties, which then result in different MCE. Large MCE has been observed not only in the typical ferromagnetic materials but also in the antiferromagnetic materials. The magnetic properties have been studied in detail to discuss the physical mechanism of large MCE in RT X compounds. Particularly, some RT X compounds such as Er Fe Si,Ho Cu Si, Ho Cu Al exhibit large reversible MCE under low magnetic field change, which suggests that these compounds could be promising materials for magnetic refrigeration in a low temperature range.展开更多
At cryogenic temperatures,the investigations of magnetic phase transition and magnetocaloric effect in RE_(2)FeC_(4)(RE=Ho,Er,and Tm) compounds were performed.Ho_(2)FeC_(4)and Er_(2)FeC_(4)compounds undergo two magnet...At cryogenic temperatures,the investigations of magnetic phase transition and magnetocaloric effect in RE_(2)FeC_(4)(RE=Ho,Er,and Tm) compounds were performed.Ho_(2)FeC_(4)and Er_(2)FeC_(4)compounds undergo two magnetic phase transitions with the temperature decreasing:from paramagnetic(PM) to ferromagnetic(FM) transition at their respective Curie temperature(Tc) and from FM to antiferromagnetic(AFM) or ferrimagnetic(FIM) transition below 2 K.Tm_(2)FeC_(4)compound exhibits only a second-order PM to FM phase transition at TC=K.Large reversible MCE without hysteresis loss is observed in RE_(2)FeC_(4)(RE=Ho,Er,and Tm) compounds.Particularly,the maximum value of magnetic entropy change(-ASM)is 21.62 J/(kg K) under the magnetic field change(Δ_(μ0)H) of 0-5 T for Er_(2)FeC_(4).The Er_(2)FeC_(4)compound presenting excellent magnetocaloric performance makes it a competitive cryogenic magnetic refrigeration material.展开更多
The table-like magnetocaloric effect is significant for the magnetic refrigeration applications above 20 K based on the Ericsson cycle.Herein,we prepared a series of Nd_(6)Fe_(13)Pd_(1-x)Cu_(x)(x=0.05,0.1,0.15)compoun...The table-like magnetocaloric effect is significant for the magnetic refrigeration applications above 20 K based on the Ericsson cycle.Herein,we prepared a series of Nd_(6)Fe_(13)Pd_(1-x)Cu_(x)(x=0.05,0.1,0.15)compounds by the arc-melting method.These compounds show the single crystalline phase in the tetragonal Nd_(6)Fe_(13)Si-type structure with the space group I4/mcm.A magnetic phase transition from ferromagnetism to antiferromagnetism and a metamagnetic transition from the antiferromagnetic state to the ferromagnetic state are observed in each of the compounds.The compounds exhibit table-like magnetocaloric effects with large refrigerant capacities.A constantΔSM in a temperature span of 40 K in the Nd_(6)Fe_(13)Pd_(0.85)Cu_(0.15) compound are observed.For a field change of 0–5 T,the peak values of–ΔS_(M) for the Nd_(6)Fe_(13)Pd_(0.95)Cu_(0.05),Nd_(6)Fe_(13)Pd_(0.90)Cu_(0.10),and Nd_(6)Fe_(13)Pd_(0.85)Cu_(0.15) compounds are estimated to be 4.8,4.6 and 4.4 J/(kg·K)with corresponding refrigerant capacity values of 323,331 and 316 J/kg,respectively.The obtained table-like magnetocaloric effects with large refrigerant capacities as well as fairly small thermal and magnetic hysteresis deem these series of compounds good candidates for single-phase magnetic refrigeration based on the Ericsson cycle.展开更多
The ErCo2 compound is prepared by arc-melting and its entropy changes are calculated using Maxwell relation. Its entropy change reaches 38 J/(kg·K) and its refrigerant capacity achieves 291 J/kg at 0-5 T. The m...The ErCo2 compound is prepared by arc-melting and its entropy changes are calculated using Maxwell relation. Its entropy change reaches 38 J/(kg·K) and its refrigerant capacity achieves 291 J/kg at 0-5 T. The mean field approximation is used to calculate the magnetic entropy of ErCo2 compound. Results estimated by using the Maxwell relation deviate from mean field approximation calculations in ferrimagnetic state; however, the data obtained by the two ways are consistent in the vicinity of phase transition or at higher temperatures. This indicates that entropy changes are mainly derived from magnetic degree of freedom, and the lattice has almost no contribution to the entropy change in the vicinity of phase transition but its influence is obvious in the ferrimagnetic state below TC.展开更多
The structure and magnetic properties of MnCoSil_xPx (x = 0.054).50) are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the s...The structure and magnetic properties of MnCoSil_xPx (x = 0.054).50) are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the same time, the temperature of metamagnetic transition from a low-temperature non-collinear ferromagnetic state to a high-temperature ferromagnetic state decreases and a new magnetic transition from a higher-magnetization ferromagnetic state to a lower- magnetization ferromagnetic state is observed in each of these compounds for the first time. This is explained by the changes of crystal structure and distance between Mn and Si atoms with the increase of temperature according to the high- temperature XRD result. The metamagnetic transition is found to be a second-order magnetic transition accompanied by a low inversed magnetocaloric effect (1.0 J·kg-1 ·K- 1 at 5 T) with a large temperature span (190 K at 5 T) compared with the scenario of MnCoSi. The changes in the order of metamagnetic transition and structure make P-doped MoCoSi compounds good candidates for the study of magnetoelastic coupling and the modulation of magnetic phase transition.展开更多
Rare-earth orthoferrite REFeO_(3)(where RE is a rare-earth ion)is gaining interest.We created a high-entropy orthoferrite(Tm_(0.2)Nd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))FeO_(3)(HEOR)by doping five RE ions in equimolar ratios...Rare-earth orthoferrite REFeO_(3)(where RE is a rare-earth ion)is gaining interest.We created a high-entropy orthoferrite(Tm_(0.2)Nd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))FeO_(3)(HEOR)by doping five RE ions in equimolar ratios and grew the single crystal by optical floating zone method.It strongly tends to form a single-phase structure stabilized by high configurational entropy.In the low-temperature region(11.6‒14.4 K),the spin reorientation transition(SRT)ofΓ_(2)(F_(x),C_(y),G_(z))‒Γ_(24)‒Γ_(4)(G_(x),A_(y),F_(z))occurs.The weak ferromagnetic(FM)moment,which comes from the Fe sublattices distortion,rotates from the a-to c-axis.The two-step dynamic processes(Γ_(2)‒Γ_(24)‒Γ_(4))are identified by AC susceptibility measurements.SRT in HEOR can be tuned in the range of 50‒60000 Oe,which is an order of magnitude larger than that of orthoferrites in the peer system,making it a candidate for high-field spin sensing.Typical spin-switching(SSW)and continuous spin-switching(CSSW)effects occur under low magnetic fields due to the strong interactions between RE‒Fe sublattices.The CSSW effect is tunable between 20‒50 Oe,and hence,HEOR potentially can be applied to spin modulation devices.Furthermore,because of the strong anisotropy of magnetic entropy change()and refrigeration capacity(RC)based on its high configurational entropy,HEOR is expected to provide a novel approach for refrigeration by altering the orientations of the crystallographic axes(anisotropic configurational entropy).展开更多
In this study,the thermal expansion of Hf_(1-x)Ta_(x)Fe_(2)(x=0.10,0.13,0.15)compounds by adjusting the Ta concentration was successfully regulated.The magnetocaloric properties,hydrostatic pressure affecting the anti...In this study,the thermal expansion of Hf_(1-x)Ta_(x)Fe_(2)(x=0.10,0.13,0.15)compounds by adjusting the Ta concentration was successfully regulated.The magnetocaloric properties,hydrostatic pressure affecting the antiferromagnetic-ferromagnetic transition,and magnetostriction in the low magnetic field were studied.TheΔS_(M)values of 3.3 J·(kg-K)^(-1)and 3.6 J·(kg·K)^(-1)were obtained under magnetic fields of 10 kOe and 15 kOe in the Hf_(0.85)Ta_(0.15)Fe_(2),respectively.In the antiferromagnetic-ferromagnetic state transformation process under hydrostatic pressure up to 0.8 GPa,the state temperature does not decrease in a strictly linear manner.Outstanding magnetostrictive properties of 0.12%were obtained at a magnetic field of 10 kOe.This kind of alloy is supposed to be controlled under hydrostatic pressure to obtain good magnetic refrigeration performance and magnetostrictive properties.展开更多
A series of CeMn2(Si1-xGex)2(x = 0.2, 0.4, 0.6, 0.8) compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-fie...A series of CeMn2(Si1-xGex)2(x = 0.2, 0.4, 0.6, 0.8) compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-field-cooled(ZFC) and FC magnetization measurements show a transition from antiferromagnetic(AFM) state to ferromagnetic(FM) state at room temperature with the increase of the Ge concentration. For x = 0.4, the sample exhibits two kinds of phase transitions with increasing temperature: from AFM to FM and from FM to paramagnetic(PM) at around TN-197 K and T C-300 K,respectively. The corresponding Arrott curves indicate that the AFM–FM transition is of first-order character and the FM–PM transition is of second-order character. Meanwhile, the coexistence of positive and negative magnetic entropy changes can be observed, which are corresponding to the AFM–FM and FM–PM transitions, respectively.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51671022 and 51427806)the Beijing Natural Science Foundation,China(Grant No.2162022)the Fundamental Research Funds for the Central Universities,China(Grant No.FRF-TP-15-002A3)
文摘The magnetic properties and magnetocaloric effects (MCE) of HoNiGa compound are investigated systematically. The HoNiGa exhibits a weak antiferromagnetic (AFM) ground state below the Neel temperature TN of 10 K, and the AFM ordering could be converted into ferromagnetic (FM) ordering by external magnetic field. Moreover, the fie/d-induced FM phase exhibits a high saturation magnetic moment and a large change of magnetization around the transition temperature, which then result in a large MCE. A large -△SM of 22.0 J/kg K and a high RC value of 279 J/kg without magnetic hysteresis are obtained for a magnetic field change of 5 T, which are comparable to or even larger than those of some other magnetic refrigerant materials in the same temperature range. Besides, the μ0H2/3 dependence of |△SPKM| well follows the linear fitting according to the mean-field approximation, suggesting the nature of second-order FM-PM magnetic transition under high magnetic fields. The large reversible MCE induced by metamagnetic transition suggests that HoNiGa compound could be a promising material for magnetic refrigeration in low temperature range.
基金Japanese Ministry of Education, Science, Sports and Culture!Grantin-Aid for Scientific Research (B)(2) 08455287
文摘A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.
基金the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province,China(Grant No.2021L304)the Taiyuan University of Science and Technology Scientific Research Initial Funding,China(Grant Nos.20202022 and 20222002)+2 种基金the Funding for Outstanding Doctoral Research in Jin,China(Grant No.20212002)the Fund from the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,China(Grant No.2022-KF-32)the National Natural Science Foundation of China(Grant No.51901150)。
文摘HoBi single crystal and polycrystalline compounds with Na Cl-type structure are successfully obtained,and their magnetic and magnetocaloric properties are studied in detail.With temperature increasing,Ho Bi compound undergoes two magnetic transitions at 3.7 K and 6 K,respectively.The transition temperature at 6 K is recognized as an antiferromagneticto-paramagnetic(AFM–PM)transition,which belongs to the first-order magnetic phase transition(FOMT).It is interesting that the Ho Bi compound with FOMT exhibits good thermal and magnetic reversibility.Furthermore,a large inverse and normal magnetocaloric effect(MCE)is found in Ho Bi single crystal in the H||[100]direction,and the positive?SMpeak reaches 13.1 J/kg·K under a low field change of 2 T and the negative?S_(M)peak arrives at-18 J/kg·K under a field change of5 T.These excellent properties are expected to be applied to some magnetic refrigerators with special designs and functions.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11004044)the Natural Science Foundation of Zhejiang Province,China(Grant No. Y4110581)
文摘The magnetocaloric effect(MCE) in EuCu1.75P2 compound is studied by the magnetization and heat capacity measurements.Magnetization and modified Arrott plots indicate that the compound undergoes a second-order phase transition at TC ~ 51 K.A large reversible MCE is observed around TC.The values of maximum magnetic entropy change(-△SxMma) reach 5.6 J·kg^-1·K-1 and 13.3 J·kg^-1·K-1 for the field change of 2 T and 7 T,respectively,with no obvious hysteresis loss in the vicinity of Curie temperature.The corresponding maximum adiabatic temperature changes(△Tadmax) are evaluated to be 2.1 K and 5.0 K.The magnetic transition and the origin of large MCE in EuCu1.75P2 are also discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.50701022 and 50831006)
文摘The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably, resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil_χFexGe alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe, metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil-xFezGe alloys at temperature below the structural transition temperature.
基金Project supported by the National Basic Research Program of China (Grant No. 2006CB601101)the National Natural Science Foundation of China (Grant No. 50731007)the Knowledge Innovation Project of the Chinese Academy of Sciences
文摘We have studied the magnetic and magnetocaloric properties of the Er3Co compound, which undergoes ferromagnetic ordering below the Curie temperature Tc = 13 K. It is found by fitting the isothermal magnetization curves that the Landau model is appropriate to describe the Er3Co compound. The giant magnetocaloric effect (MCE) without hysteresis loss around Tc is found to result from the second-order ferromagnetic-to-paramagnetic transition. The max- imal value of magnetic entropy change is 24.5 J/kg.K with a refrigerant capacity (RC) value of 476 J/kg for a field change of 0-5 T. Large reversible MEC and RC indicate the potentiality of Er3Co as a candidate magnetic refrigerant at low temperatures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374081 and 11004044)the Fundamental Research Funds for the Central Universities+4 种基金China(Grant Nos.N150905001L1509006and N140901001)the Japan Society for the Promotion of Science Postdoctoral Fellowships for Foreign Researchers(Grant No.P10060)the Alexander von Humboldt(Av H)Foundation(Research stipend to L.Li)
文摘The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively in- vestigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s) (Zn, Mg, and Cd). Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi2B2C superconductors is also presented.
基金Project supported by the National Natural Science Foundation of Chinathe Key Research Program of the Chinese Academy of Sciences+1 种基金the National Basic Research Program of Chinathe National High Technology Research and Development Program of China
文摘In this article, our recent progress concerning the effects of atomic substitution, magnetic field, and temperature on the magnetic and magnetocaloric properties of the LaFe13-xAlx compounds are reviewed. With an increase of the aluminum content, the compounds exhibit successively an antiferromagnetic (AFM) state, a ferromagnetic (FM) state, and a mictomagnetic state. Furthermore, the AFM coupling of LaFe13 -xAlx can be converted to an FM one by substituting Si for A1, Co for Fe, and magnetic rare-earth R for La, or introducing interstitial C or H atoms. However, low doping levels lead to FM clusters embedded in an AFM matrix, and the resultant compounds can undergo, under appropriate applied fields, first an AFM-FM and then an FM-AFM phase transition while heated, with significant magnetic relaxation in the vicinity of the transition temperature. The Curie temperature of LaFe13-xAlx can be shifted to room temperature by choosing appropriate contents of Co, C, or H, and a strong magnetocaloric effect can be obtained around the transition temperature. For example, for the LaFel 1.5All.5Co.2Hl.o compound, the maximal entropy change reaches 13.8 J.kg-1.K-1 for a field change of 0-5 T, occurring around room temperature. It is 42% higher than that of Gd, and therefore, this compound is a promising room-temperature magnetic refrigerant.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB643703)the National Key Research and Development Program of China(Grant No.2016YFB0700901)+1 种基金the National Natural Science Foundation of China(Grant Nos.51261004 and 51761007)Guangxi Natural Science Foundation,China(Grant No.2018GXNSFAA294051)
文摘The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and undergo a second order transition from spin glass(SG) state to paramagnetic(PM) state. The spin glass transition temperatures T_g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures(θp) for Ho_5 Pd_2,(Ho_(0.75) Y_(0.25)_5 Pd_2, and(Ho_(0.5) Y_(0.5))_5 Pd_2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments(μeff) are10.8 μB/Ho, 10.3 μB/RE, and 7.5 μB/RE, respectively. Magnetocaloric effect(MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change-?SMof the(Ho_(1-x)Y_x)_5 Pd_2(x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J·kg^(-1)·K^(-1), 11.1 J·kg^(-1)·K^(-1), and 8.9 K J·kg^(-1)·K^(-1), with corresponding refrigerant capacity values of 382.3 J·kg^(-1), 336.2 J·kg^(-1), and 242.5 J·kg^(-1), respectively.
基金Project supported by the National Natural Science Foundation of China (Grant No 50571112) and the National Basic Research Program of China (Grant No 2006CB601101).
文摘Magnetic properties and magnetocaloric effect in TbCo2-xFex compounds are studied by DC magnetic measurement. With increasing content of Fe, the entropy changes decrease slightly, though the Curie temperature is tuned from 231 K (x = 0) to 303 K (x = 0.1). Magnetic entropies of TbCo2 compound are calculated by using mean field approximation (MFA). Results estimated by using Maxwell relation are consistent with that of MFA calculation. It is shown that the entropy changes are mainly derived from the magnetic entropy changes. The lattice has almost no contribution to the entropy change in the vicinity of phase transition.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 50164003).
文摘The crystal structure, itinerant-electron metamagnetic transition (IEMT) and magnetocaloric effect (MCE) in the iron-based rare-earth intermetallic compound La0.8Ce0.2Fe11.4Si1.6 have been investi- gated. The powder X-ray diffraction revealed that the ingot of La0.8Ce0.2Fe11.4Si1.6 annealed at 1373 K in vacuum for only 5 days could be crystallized in the cubic NaZn13-type structure. The La0.8Ce0.2Fe11.4Si1.6 compound exhibited giant values of the isothermal entropy change ?SM around the Curie temperature TC (about 186 K). And the maximum value ΔS M max is about 78.29 J/(kg·K) under a field change of 0—3 T, which can be calculated by the magnetization iso- therms around TC. Such a large MCE is attributed to the sharp change of magnetization and susceptibility around TC and the first-order magnetic transition of field-induced IEMT above TC.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50731007 and 51021061)the Knowledge Innovation Project of the Chinese Academy of Sciencesthe High-Technology Research and Development Program of China
文摘Magnetic properties and magnetocaloric effects(MCEs) of the HoPdAl compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated.Both the compounds are found to be antiferromagnet with the Néel temperature TN=12 and 10 K,respectively.A field-induced metamagnetic transition from antiferromagnetic(AFM) state to ferromagnetic(FM) state is observed below TN.For the hexagonal HoPdAl,a small magnetic field can induce an FM-like state due to a weak AFM coupling,which leads to a high saturation magnetization and gives rise to a large MCE around TN.The maximal value of magnetic entropy change(?SM) is-20.6 J/kg K with a refrigerant capacity(RC) value of 386 J/kg for a field change of 0-5 T.For the orthorhombic HoPdAl,the critical field required for metamagnetic transition is estimated to be about 1.5 T,showing a strong AFM coupling.However,the maximal SM value is still-13.7 J/kg K around TN for a field change of 0-5 T.The large reversible SM and considerable RC suggest that HoPdAl may be an appropriate candidate for magnetic refrigerant in a low temperature range.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.5137102611274357+1 种基金and 51327806)the Fundamental Research Funds for the Central Universities(Grant Nos.FRF-TP-14-011A2 and FRF-TP-15-002A3)
文摘The magnetocaloric effect(MCE) of RT Si and RT Al systems with R = Gd–Tm, T = Fe–Cu and Pd, which have been widely investigated in recent years, is reviewed. It is found that these RT X compounds exhibit various crystal structures and magnetic properties, which then result in different MCE. Large MCE has been observed not only in the typical ferromagnetic materials but also in the antiferromagnetic materials. The magnetic properties have been studied in detail to discuss the physical mechanism of large MCE in RT X compounds. Particularly, some RT X compounds such as Er Fe Si,Ho Cu Si, Ho Cu Al exhibit large reversible MCE under low magnetic field change, which suggests that these compounds could be promising materials for magnetic refrigeration in a low temperature range.
基金Project supported by the National Natural Science Foundation of China (52171195,52171054)the National Science Foundation for Distinguished Young Scholars (51925605)the Scientific Instrument Developing Project of Chinese Academy of Sciences (YJKYYQ20200075)。
文摘At cryogenic temperatures,the investigations of magnetic phase transition and magnetocaloric effect in RE_(2)FeC_(4)(RE=Ho,Er,and Tm) compounds were performed.Ho_(2)FeC_(4)and Er_(2)FeC_(4)compounds undergo two magnetic phase transitions with the temperature decreasing:from paramagnetic(PM) to ferromagnetic(FM) transition at their respective Curie temperature(Tc) and from FM to antiferromagnetic(AFM) or ferrimagnetic(FIM) transition below 2 K.Tm_(2)FeC_(4)compound exhibits only a second-order PM to FM phase transition at TC=K.Large reversible MCE without hysteresis loss is observed in RE_(2)FeC_(4)(RE=Ho,Er,and Tm) compounds.Particularly,the maximum value of magnetic entropy change(-ASM)is 21.62 J/(kg K) under the magnetic field change(Δ_(μ0)H) of 0-5 T for Er_(2)FeC_(4).The Er_(2)FeC_(4)compound presenting excellent magnetocaloric performance makes it a competitive cryogenic magnetic refrigeration material.
基金Project supported by the National Natural Science Foundation of China(21805196)Guangxi Natural Science Foundation(2018GXNSFAA294051)the Guangxi Science and Technology Project(AD19110065)。
文摘The table-like magnetocaloric effect is significant for the magnetic refrigeration applications above 20 K based on the Ericsson cycle.Herein,we prepared a series of Nd_(6)Fe_(13)Pd_(1-x)Cu_(x)(x=0.05,0.1,0.15)compounds by the arc-melting method.These compounds show the single crystalline phase in the tetragonal Nd_(6)Fe_(13)Si-type structure with the space group I4/mcm.A magnetic phase transition from ferromagnetism to antiferromagnetism and a metamagnetic transition from the antiferromagnetic state to the ferromagnetic state are observed in each of the compounds.The compounds exhibit table-like magnetocaloric effects with large refrigerant capacities.A constantΔSM in a temperature span of 40 K in the Nd_(6)Fe_(13)Pd_(0.85)Cu_(0.15) compound are observed.For a field change of 0–5 T,the peak values of–ΔS_(M) for the Nd_(6)Fe_(13)Pd_(0.95)Cu_(0.05),Nd_(6)Fe_(13)Pd_(0.90)Cu_(0.10),and Nd_(6)Fe_(13)Pd_(0.85)Cu_(0.15) compounds are estimated to be 4.8,4.6 and 4.4 J/(kg·K)with corresponding refrigerant capacity values of 323,331 and 316 J/kg,respectively.The obtained table-like magnetocaloric effects with large refrigerant capacities as well as fairly small thermal and magnetic hysteresis deem these series of compounds good candidates for single-phase magnetic refrigeration based on the Ericsson cycle.
基金Project supported by the National Natural Science Foundation of China (Grant No 50571112) and the National Basic Research Program of China (Grant No 2006CB601101).
文摘The ErCo2 compound is prepared by arc-melting and its entropy changes are calculated using Maxwell relation. Its entropy change reaches 38 J/(kg·K) and its refrigerant capacity achieves 291 J/kg at 0-5 T. The mean field approximation is used to calculate the magnetic entropy of ErCo2 compound. Results estimated by using the Maxwell relation deviate from mean field approximation calculations in ferrimagnetic state; however, the data obtained by the two ways are consistent in the vicinity of phase transition or at higher temperatures. This indicates that entropy changes are mainly derived from magnetic degree of freedom, and the lattice has almost no contribution to the entropy change in the vicinity of phase transition but its influence is obvious in the ferrimagnetic state below TC.
基金Project supported by the National Natural Science Foundation of China(Grant No.11275013)the Fund from the National Physics Laboratory,China Academy of Engineering Physics(Grant No.2013DB01)the National Key Basic Research Program of China(Grant No.2010CB833104)
文摘The structure and magnetic properties of MnCoSil_xPx (x = 0.054).50) are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the same time, the temperature of metamagnetic transition from a low-temperature non-collinear ferromagnetic state to a high-temperature ferromagnetic state decreases and a new magnetic transition from a higher-magnetization ferromagnetic state to a lower- magnetization ferromagnetic state is observed in each of these compounds for the first time. This is explained by the changes of crystal structure and distance between Mn and Si atoms with the increase of temperature according to the high- temperature XRD result. The metamagnetic transition is found to be a second-order magnetic transition accompanied by a low inversed magnetocaloric effect (1.0 J·kg-1 ·K- 1 at 5 T) with a large temperature span (190 K at 5 T) compared with the scenario of MnCoSi. The changes in the order of metamagnetic transition and structure make P-doped MoCoSi compounds good candidates for the study of magnetoelastic coupling and the modulation of magnetic phase transition.
基金supported by the research grant from the National Natural Science Foundation of China(NSFC)(Nos.12074242 and 12204298)the Science and Technology Commission of Shanghai Municipality(No.21JC1402600).
文摘Rare-earth orthoferrite REFeO_(3)(where RE is a rare-earth ion)is gaining interest.We created a high-entropy orthoferrite(Tm_(0.2)Nd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))FeO_(3)(HEOR)by doping five RE ions in equimolar ratios and grew the single crystal by optical floating zone method.It strongly tends to form a single-phase structure stabilized by high configurational entropy.In the low-temperature region(11.6‒14.4 K),the spin reorientation transition(SRT)ofΓ_(2)(F_(x),C_(y),G_(z))‒Γ_(24)‒Γ_(4)(G_(x),A_(y),F_(z))occurs.The weak ferromagnetic(FM)moment,which comes from the Fe sublattices distortion,rotates from the a-to c-axis.The two-step dynamic processes(Γ_(2)‒Γ_(24)‒Γ_(4))are identified by AC susceptibility measurements.SRT in HEOR can be tuned in the range of 50‒60000 Oe,which is an order of magnitude larger than that of orthoferrites in the peer system,making it a candidate for high-field spin sensing.Typical spin-switching(SSW)and continuous spin-switching(CSSW)effects occur under low magnetic fields due to the strong interactions between RE‒Fe sublattices.The CSSW effect is tunable between 20‒50 Oe,and hence,HEOR potentially can be applied to spin modulation devices.Furthermore,because of the strong anisotropy of magnetic entropy change()and refrigeration capacity(RC)based on its high configurational entropy,HEOR is expected to provide a novel approach for refrigeration by altering the orientations of the crystallographic axes(anisotropic configurational entropy).
基金financially by the School of Mechanical,Materials,Mechatronic and Biomedical Engineering,University of Wollongong,AustraliaThe China Scholarship Council(No.201808140031)+1 种基金The Emerging Industry Leadership Talent Program of Shanxi Province(No.2019042)Scientific and Technological Innovation Projects for Excellent Researchers of Shanxi Province(No.201805D211042)。
文摘In this study,the thermal expansion of Hf_(1-x)Ta_(x)Fe_(2)(x=0.10,0.13,0.15)compounds by adjusting the Ta concentration was successfully regulated.The magnetocaloric properties,hydrostatic pressure affecting the antiferromagnetic-ferromagnetic transition,and magnetostriction in the low magnetic field were studied.TheΔS_(M)values of 3.3 J·(kg-K)^(-1)and 3.6 J·(kg·K)^(-1)were obtained under magnetic fields of 10 kOe and 15 kOe in the Hf_(0.85)Ta_(0.15)Fe_(2),respectively.In the antiferromagnetic-ferromagnetic state transformation process under hydrostatic pressure up to 0.8 GPa,the state temperature does not decrease in a strictly linear manner.Outstanding magnetostrictive properties of 0.12%were obtained at a magnetic field of 10 kOe.This kind of alloy is supposed to be controlled under hydrostatic pressure to obtain good magnetic refrigeration performance and magnetostrictive properties.
基金Project supported by the Beijing Natural Science Foundation,China(Grant No.2152034)the National Natural Science Foundation of China(Grant Nos.11274357 and 51271196)
文摘A series of CeMn2(Si1-xGex)2(x = 0.2, 0.4, 0.6, 0.8) compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-field-cooled(ZFC) and FC magnetization measurements show a transition from antiferromagnetic(AFM) state to ferromagnetic(FM) state at room temperature with the increase of the Ge concentration. For x = 0.4, the sample exhibits two kinds of phase transitions with increasing temperature: from AFM to FM and from FM to paramagnetic(PM) at around TN-197 K and T C-300 K,respectively. The corresponding Arrott curves indicate that the AFM–FM transition is of first-order character and the FM–PM transition is of second-order character. Meanwhile, the coexistence of positive and negative magnetic entropy changes can be observed, which are corresponding to the AFM–FM and FM–PM transitions, respectively.