The height of total entropy(S)for a magnetic refrigerant material is essentially concerned with the magnetic and structural transitions.However,the participation of such transitions in layered materials is not well un...The height of total entropy(S)for a magnetic refrigerant material is essentially concerned with the magnetic and structural transitions.However,the participation of such transitions in layered materials is not well understood.Therefore,the purpose of this work is to investigate the interplay between double layer lattice with their single perovskite counterpart,to achieve optimal magnetocaloric performance.A series of self-doped Pr_(1.4+x)Sr_(1.6-x)Mn_(2)O_(7)(0.0≤x≤0.5)Ruddlesden-Popper(R-P)perovskite have been prepared through the solid-state sintering method.With increasing the Pr-stoichiometry,the lattice faults have increased and the double layer lattice dramatically disintegrates into single perovskite structure.Due to the reduction of bilayer R-P phase into single perovskite the spin crossover occurs from weak bilayer(T=304 K)interactions towards the strong three-dimensional(T=308 K)interactions respectively.This series consistently develops thermomagnetic irreversibility in zero-field cooled(ZFC)-field cooled(FC)magnetization,which is indicative of a spin-glass state.The glassy nature has been ascribed collectively to the lattice strain produced because of dislocations and to an antiferromagnetic phase segregated at the surface.The maximum value of temperature average entropy change(TEC)and adiabatic temperature(ΔT)has enhanced nearly by 4 folds from 0.53 J kg^(-1)K^(-1),0.59 K(for x=0.0)up to 1.85 J kg^(-1)K^(-1),10 K(for x=0.5)at 2.5 T,respectively.Additionally,the room temperature relative cooling power has improved from 26.94 J/kg up to 77.84 J/kg with an applied field of 2.5 T.Our findings in this work suggest that the controlled reduction of double layer lattice into single perovskite and/or existence of both phases simultaneously in bilayer R-P manganites may be very effective in obtaining the desirable characteristics of magnetocaloric effects.展开更多
We present a simple hot press-based method for processing La(Fe,Si)13-based compounds consisting of La–Fe–Co–Si–C particles and phenolic resin. The magnetic entropy change △S per unit mass for the La Fe_(10.87)Co...We present a simple hot press-based method for processing La(Fe,Si)13-based compounds consisting of La–Fe–Co–Si–C particles and phenolic resin. The magnetic entropy change △S per unit mass for the La Fe_(10.87)Co_(0.63)Si_(1.5)C_(0.2)/phenolic resin compounds have nearly the same magnitude with the base materials. With the content of phenolic resin of 5.0 wt%, the compound conductivity is 3.13 W·m^(-1)·K^(-1). In order to measure the cooling performance of La(Fe,Si)13-based compounds,the La(Fe_(11.6-x)Co_(x))Si_(1.4)C_(0.15)(x =0.60, 0.65, 0.75, 0.80, 0.85)/phenolic resin compounds were pressed into thin plates and tested in a hybrid refrigerator that combines the active magnetic refrigeration effect with the Stirling cycle refrigeration effect. The test results showed that a maximum cooling power of 41 W was achieved over a temperature span of 30 K.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
We investigate the structure, magnetic properties, magnetic phase transitions and magnetocaloric effects(MCEs) of Er5Si3Bx(x=0.3,0.6) compounds. The Er5Si3Bx(x = 0.3, 0.6) compounds crystalize in a Mn5Si3type hexagona...We investigate the structure, magnetic properties, magnetic phase transitions and magnetocaloric effects(MCEs) of Er5Si3Bx(x=0.3,0.6) compounds. The Er5Si3Bx(x = 0.3, 0.6) compounds crystalize in a Mn5Si3type hexagonal structure(space group: P63/cm) and exhibit a successive complicated magnetic phase transition. The extensive magnetic phase transitions contribute to the broad temperature range of MCEs exhibiting in Er_(5)Si_(3)B_(x)(x=0.3,0.6) compounds, with maximum magnetic entropy change(-ΔSM_(max)) and refrigeration capacity of 10.2 J·kg^(-1)·K^(-1), 356.3 J/kg and 11.5 J·kg^(-1)·K^(-1),393.3 J/kg under varying magnetic fields 0–5 T, respectively. Remarkably, the δTFWHMvalues(the temperature range corresponding to 1/2×|-ΔSM_(max)|) of Er5Si3Bx(x=0.3,0.6) compounds were up to 41.8 K and 39.6 K, respectively. Thus, the present work provides a potential magnetic refrigeration material with a broad temperature range MCEs for applications in cryogenic magnetic refrigerators.展开更多
Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity(RC)was reported.Er_(20)Ho_(20)Dy_(20)Cu_...Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity(RC)was reported.Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass was observed with typical spin glass behavior around 15.5 K.In addition,we find that the magnetic entropy change(-△S_(M))originates from the sample undergoing a ferromagnetic(FM)to paramagnetic(PM)transition around 20 K.Under a field change from 0 T to 7 T,the value of maximum magnetic entropy change(-△S_(M)^(max))reaches 12.5 J/kg·K,and the corresponding value of RC reaches 487.7 J/kg in the temperature range from 6 K to 60 K.The large RC and wide temperature range make the Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass be a promising material for application in magnetic refrigerators.展开更多
Data-mining techniques using machine learning are powerful and efficient for materials design, possessing great potential for discovering new materials with good characteristics. Here, this technique has been used on ...Data-mining techniques using machine learning are powerful and efficient for materials design, possessing great potential for discovering new materials with good characteristics. Here, this technique has been used on composition design for La(Fe,Si/Al)_(13)-based materials, which are regarded as one of the most promising magnetic refrigerants in practice. Three prediction models are built by using a machine learning algorithm called gradient boosting regression tree(GBRT) to essentially find the correlation between the Curie temperature(T_C), maximum value of magnetic entropy change((?S_M)_(max)),and chemical composition, all of which yield high accuracy in the prediction of T_C and(?SM)_(max). The performance metric coefficient scores of determination(R^2) for the three models are 0.96, 0.87, and 0.91. These results suggest that all of the models are well-developed predictive models on the challenging issue of generalization ability for untrained data, which can not only provide us with suggestions for real experiments but also help us gain physical insights to find proper composition for further magnetic refrigeration applications.展开更多
Nowadays,magnetic cooling(MC) technology by using the magnetocaloric effect(MCE) has attracted extensive research interest for its promising practical applications.A constant large/giant MCE covers wide refrigeration ...Nowadays,magnetic cooling(MC) technology by using the magnetocaloric effect(MCE) has attracted extensive research interest for its promising practical applications.A constant large/giant MCE covers wide refrigeration temperatures(denote as table-like shape) is beneficial for obtaining high efficiency performance for MC.In this paper,the HoNi/HoNi2 composite was successfully synthesized by arc-melting method and proved to be composed of HoNi and HoNi2 crystalline phases with weight ratios of 52.4 wt.% and 47.6 wt.%,respectively.The maximum magnetic entropy change(-ΔSMmax)is 18.23 J/(kg·K),and the refrigerant capacity values RC1,RC2,and RC3 are 867.9 J/kg,676.4 J/kg,and 467.8 J/kg with ΔH=0-70 kOe,respectively.The table-like shape MCE and large refrigerant capacity values make the composite attractive for cryogenic MC using the Ericsson cycle.展开更多
In this paper, we study the effects of Pr substitution on the hydrogenating process and magnetocaloric properties of La_(1-x)Pr_xFe_(11.4)Si_(1.6)H_y hydrides. The powder x-ray diffraction patterns of the La_(1-x)Pr_x...In this paper, we study the effects of Pr substitution on the hydrogenating process and magnetocaloric properties of La_(1-x)Pr_xFe_(11.4)Si_(1.6)H_y hydrides. The powder x-ray diffraction patterns of the La_(1-x)Pr_xFe_(11.4)Si_(1.6) and its hydrides show that each of the alloys is crystallized into the single phase of cubic Na Zn_(13)-type structure. There are hydrogen-absorbing plateaus under 0.4938 MPa and 0.4882 MPa in the absorbing curves for the La_(0.8)Pr_(0.2)Fe_(11.4)Si_(1.6) and La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6) compounds. The releasing processes lag behind the absorbing process, which is obviously different from the coincidence between absorbing and releasing curves of the La Fe_(11.4)Si_(1.6) compound. The remnant hydrogen content for La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6) is significantly more than that for La_(0.8)Pr_(0.2)Fe_(11.4)Si_(1.6) after hydrogen desorption, indicating that more substitutions of Pr for La are beneficial to retaining more hydrogen atoms in the alloys. The values of maximum magnetic entropy change are 14.91 J/kg·K and 17.995 J/kg·K for La_(0.8)Pr_(0.2)Fe_(11.4)Si_(1.6)H_(0.13) and La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6)H_(0.87),respectively.展开更多
Due to the hydrogen embrittlement effect,La(Fe,Si)_(13)-based hydrides can only exist in powder form,which limits their practical application.In this work,ductile and thermally conductive Al metal was homogeneously mi...Due to the hydrogen embrittlement effect,La(Fe,Si)_(13)-based hydrides can only exist in powder form,which limits their practical application.In this work,ductile and thermally conductive Al metal was homogeneously mixed with La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)using the ball milling method.Then hydrogenation and compactness shaping of the magnetocaloric composites were performed in one step via a sintering process under high hydrogen pressure.As the Al content reached 9 wt.%,the La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)H_(y)/Al composite showed the mechanical behavior of a ductile material with a yield strength of~44 MPa and an ultimate strength of 269 MPa accompanied by a pronounced improvement in thermal conductivity.Due to the ease of formation of Fe-Al-Si phases and the several micron and submicron sizes of the composite particles caused by ball milling process,the magnetic entropy change of the composites was substantially reduced to~1.2 J/kg·K-1.5 J/kg·K at 0 T-1.5 T.展开更多
The magnetic functional materials play a particularly important role in our modern society and daily life.The magnetocaloric effect(MCE)is at the basis of a solid state magnetic refrigeration(MR)technology which may e...The magnetic functional materials play a particularly important role in our modern society and daily life.The magnetocaloric effect(MCE)is at the basis of a solid state magnetic refrigeration(MR)technology which may enhance the efficiency of cooling systems,both for room temperature and cryogenic appli-cations.Despite numerous experimental and theoretical MCE studies,commercial MR systems are still at developing stage.Designing magnetic solids with outstanding magnetocaloric performances remains therefore a most urgent task.Herein,recent progresses on characterizing the crystal structure,magnetic properties and cryogenic MCE of rare earths(RE)-based RE_(2)TMTM’O_(6)double perovskite(DP)oxides,where TM and TM’are different 3d transition metals,are summarized.Some Gd-based DP oxides are found to exhibit promising cryogenic magnetocaloric performances which make them attractive for active MR ap-plications.展开更多
The microstructure, magnetic entropy changes, hysteresis and magnetic properties of La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.5–x)Si_x(x=0.4, 0.5, 0.6, 0.7) compounds were studied by X-ray diffraction(XRD) and a superconducting...The microstructure, magnetic entropy changes, hysteresis and magnetic properties of La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.5–x)Si_x(x=0.4, 0.5, 0.6, 0.7) compounds were studied by X-ray diffraction(XRD) and a superconducting quantum interference device magnetometer(SQUID). The results showed that all the compounds presented cubic Na Zn13-type structure. Their Curie temperatures changed complicatedly with decreasing Al content due to changes of antiferromagnetic and ferromagnetic interaction. Under a field change from 0 to 2 T, the maximum magnetic entropy change for La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.1)Si_(0.4), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.0)Si_(0.5), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.9)Si_(0.6) and La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.8)Si_(0.7) were found to be –9.6, –4.8, –5.8 and –11.7 J/(kg·K), respectively. Moreover, their hysteresis losses were 1.13 J/(kg·K) or less. The large magnetic entropy changed and small hysteresis losses made them potential candidates for practical magnetic refrigeration application.展开更多
Tb1-xTmxFeO3(x = 0.00,0.15,0.25) polycrystalline series were synthesized using a solid-state reaction.Our results show that all three prepared samples are in a distorted orthogonal structure and their space group is p...Tb1-xTmxFeO3(x = 0.00,0.15,0.25) polycrystalline series were synthesized using a solid-state reaction.Our results show that all three prepared samples are in a distorted orthogonal structure and their space group is pbnm.When the Tm3+doping amount increases,the characteristics of the spin-flip of the sample decreases following an initial increase at the beginning;the antiferromagnetic property almost reaches zero;the magnetization decreases at the beginning but increases later on.The maximum magnetic entropy change and magnetic refrigeration effect RCP are reduced at varying degrees.Under a 7 T magnetic field,the maximum magnetic entropy change,△Smax,for the three samples of Tb1-xTmxFeO3 with x=0.00,0.15,0.25 is 13.78,-9.28,and 10.69 J/(K·kg),respectively;the magnetic refrigeration capacity(RCP) is 316.85,175.2,and 297.60 J/kg,respectively.In summary,doping with the element Tm reduces △Smax and RCP of the sample.Since the maximum magnetic entropy change and the cooling capacity for the three samples are relatively large,they can be used as an alternative for magnetic refrigerants.展开更多
This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorpho...This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorphous structure,and the temperature interval of the undercooled liquid AT was 45 K.The microwires underwent a second-order magnetic transition from a ferromagnetic to a paramagnetic state near the Curie temperature(T_(C)=52 K),The maximum magnetic entropy change(-ΔS_M^(max)),the relative cooling power and the refrigeration capacity reached 6.34 J·kg^(-1)·K^(-1).422.09 J·kg^(-1)and 332.94 J·kg^(-1),respectively,under a magnetic field change of 5 T.In addition,the temperature-averaged entropy changes with two temperature lifts(3 and 10 K)were 6.32 and 6.27 J·kg^(-1)·K^(-1),respectively.The good magnetocalorie performance highlights the significant potential for the Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)microwires to be used as magnetic refrigerant materials in low-temperature region applications.This work will serve as a valuable reference for future investigations on low-temperature high-entropy magnetocaloric materials.展开更多
A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;...A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;Gd,5),was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid,2-hydroxypyridine,Cu(CH_(3)COO)_(2)·H_(2)O,and Ln(ClO_(4))_(3)·6 H_(2)O.Notably,the [Cu_(6)Ln_(5)] clusters with high molecular symmetry of D_(3h) are rare examples of2-aminoisobutyric acid-based 3 d-4 f clusters.The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K,whereas the Gd-Cu exchange is an order of magnitude larger.Magnetization data collected for comp lex 5 yield a magnetic entropy change(-ΔSm) of 19.6 J kg^(-1) K^(-1)<1 at 3 K and 7 T,which may be attributed to the weak magnetic interactions between the component metal ions.展开更多
It is a meaningful and challenging work for structural and synthetic chemists to isolate nano-sized high-nuclearity cluster-molecules.In this work,two largest hetero-metallic nano-clusters Gd_(158)Co_(38) were obtaine...It is a meaningful and challenging work for structural and synthetic chemists to isolate nano-sized high-nuclearity cluster-molecules.In this work,two largest hetero-metallic nano-clusters Gd_(158)Co_(38) were obtained via the“multi-anions-template”method.Different from the reported giant hollow-nano-clusters,the Ln_(158) core in Gd_(158)Co_(38)(the protein-sized nano-clusters,ca.4.3 nm×3.6 nm×3.5 nm)has the highest Ln nuclear number,which is integrated by twelve halide ions(with the form of icosahedron)as key templates,while Co ions(as 3d metals)are located in its periphery.This emergence indicates a novel structure form of non-open Ln-containing high-nuclearity clusters,and affords a consummate pattern to analyse and assemble the complex cluster-molecules.In addition,Gd_(158)Co_(38)@Cl_(12)breaks the record magnetic entropy change of 3d-4f clusters with−∆S_(m)^(max)=46.95 J kg^(−1)K^(−1)at 7.0 T,2.0 K.展开更多
Borates have attained increasing attention attributed to their excellent thermal stability,distinctive thermodynamic property,and high mechanical strength in recent years.A series of polycrystalline Dydoped GdBO_(3) c...Borates have attained increasing attention attributed to their excellent thermal stability,distinctive thermodynamic property,and high mechanical strength in recent years.A series of polycrystalline Dydoped GdBO_(3) compounds was prepared,their crystal structures,magnetic properties,and cryogenic magnetocaloric effects were comprehensively investigated.The compounds crystallize in hexagonal structure(space group P6_(3)/mmc),the lattice constant decreases with the increase of Dy content.Dydoping in GdBO_(3) significantly reduces critical magnetic field and enhances low-field magnetocaloric effect.The maximum magnetic entropy changes for the Gd_(1-x)Dy_(x)BO_(3)(x=0.6,0.8,and 1)compounds in a field change of 2 T surpass 17.3 J/(kg·K)at 2.5 K,enhanced by nearly 120%compared to GdBO_(3)(8.0 J/(kg·K)).Besides,the corresponding refrigeration capacity increases from 33.9 to 62.2,57.2,and 72.5 J/kg,respectively,with an enhancement of 70%-110%.The considerable maximum magnetic entropy change,refrigerating capacity,and temperature averaged entropy change make them competitive candidates for cryogenic magnetic refrigeration.展开更多
Magnetic refrigeration based on the magnetocaloric effect(MCE)of magnetic solids has been considered as an emerging technology for hydrogen liquefaction.However,the lack of high-performance materials has slowed the de...Magnetic refrigeration based on the magnetocaloric effect(MCE)of magnetic solids has been considered as an emerging technology for hydrogen liquefaction.However,the lack of high-performance materials has slowed the development of any practical applications.Here,we present a family of rare-earth cobalt nickel-based magnetocaloric materials,namely Dy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds,and system-atically investigated their structural and magnetic properties as well as the MCE and magnetocaloric per-formance.All of these compounds crystallize in the C15-type Laves-phase structure and undergo typi-cal second-order magnetic phase transition(MPT).The change in magnetism and the MPT temperature for the Dy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds originate from the exchange interactions between nearest-neighbor RE 3+ion pairs.No hysteresis magnetocaloric effect was achieved,and the MPT tem-perature of these compounds could be tuned from the liquefaction temperature of nitrogen(∼77 K)to hydrogen(∼20 K)by adjusting the ratio of rare-earth elements.This study’s findings indicate that theDy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds are of potential for practical magnetic refrigeration applica-tions in the field of hydrogen liquefaction.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
基金the National Research Foundation of Korea grant the Korean government(No.2018R1D1A1B07046937)。
文摘The height of total entropy(S)for a magnetic refrigerant material is essentially concerned with the magnetic and structural transitions.However,the participation of such transitions in layered materials is not well understood.Therefore,the purpose of this work is to investigate the interplay between double layer lattice with their single perovskite counterpart,to achieve optimal magnetocaloric performance.A series of self-doped Pr_(1.4+x)Sr_(1.6-x)Mn_(2)O_(7)(0.0≤x≤0.5)Ruddlesden-Popper(R-P)perovskite have been prepared through the solid-state sintering method.With increasing the Pr-stoichiometry,the lattice faults have increased and the double layer lattice dramatically disintegrates into single perovskite structure.Due to the reduction of bilayer R-P phase into single perovskite the spin crossover occurs from weak bilayer(T=304 K)interactions towards the strong three-dimensional(T=308 K)interactions respectively.This series consistently develops thermomagnetic irreversibility in zero-field cooled(ZFC)-field cooled(FC)magnetization,which is indicative of a spin-glass state.The glassy nature has been ascribed collectively to the lattice strain produced because of dislocations and to an antiferromagnetic phase segregated at the surface.The maximum value of temperature average entropy change(TEC)and adiabatic temperature(ΔT)has enhanced nearly by 4 folds from 0.53 J kg^(-1)K^(-1),0.59 K(for x=0.0)up to 1.85 J kg^(-1)K^(-1),10 K(for x=0.5)at 2.5 T,respectively.Additionally,the room temperature relative cooling power has improved from 26.94 J/kg up to 77.84 J/kg with an applied field of 2.5 T.Our findings in this work suggest that the controlled reduction of double layer lattice into single perovskite and/or existence of both phases simultaneously in bilayer R-P manganites may be very effective in obtaining the desirable characteristics of magnetocaloric effects.
基金supported by the National Natural Science Foundation of China (Grant Nos. 52171054 and 52171195)the National Natural Science Foundation for Distinguished Young Scholars (Grant No. 51925605)。
文摘We present a simple hot press-based method for processing La(Fe,Si)13-based compounds consisting of La–Fe–Co–Si–C particles and phenolic resin. The magnetic entropy change △S per unit mass for the La Fe_(10.87)Co_(0.63)Si_(1.5)C_(0.2)/phenolic resin compounds have nearly the same magnitude with the base materials. With the content of phenolic resin of 5.0 wt%, the compound conductivity is 3.13 W·m^(-1)·K^(-1). In order to measure the cooling performance of La(Fe,Si)13-based compounds,the La(Fe_(11.6-x)Co_(x))Si_(1.4)C_(0.15)(x =0.60, 0.65, 0.75, 0.80, 0.85)/phenolic resin compounds were pressed into thin plates and tested in a hybrid refrigerator that combines the active magnetic refrigeration effect with the Stirling cycle refrigeration effect. The test results showed that a maximum cooling power of 41 W was achieved over a temperature span of 30 K.
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 Science and Technology Research Project for Education Department of Jiangxi Province, China (Grant No. GJJ218509)。
文摘We investigate the structure, magnetic properties, magnetic phase transitions and magnetocaloric effects(MCEs) of Er5Si3Bx(x=0.3,0.6) compounds. The Er5Si3Bx(x = 0.3, 0.6) compounds crystalize in a Mn5Si3type hexagonal structure(space group: P63/cm) and exhibit a successive complicated magnetic phase transition. The extensive magnetic phase transitions contribute to the broad temperature range of MCEs exhibiting in Er_(5)Si_(3)B_(x)(x=0.3,0.6) compounds, with maximum magnetic entropy change(-ΔSM_(max)) and refrigeration capacity of 10.2 J·kg^(-1)·K^(-1), 356.3 J/kg and 11.5 J·kg^(-1)·K^(-1),393.3 J/kg under varying magnetic fields 0–5 T, respectively. Remarkably, the δTFWHMvalues(the temperature range corresponding to 1/2×|-ΔSM_(max)|) of Er5Si3Bx(x=0.3,0.6) compounds were up to 41.8 K and 39.6 K, respectively. Thus, the present work provides a potential magnetic refrigeration material with a broad temperature range MCEs for applications in cryogenic magnetic refrigerators.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52371203 and 52271192)the Ministry of Science and Technology of China(Grant No.2021YFB3501201)。
文摘Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity(RC)was reported.Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass was observed with typical spin glass behavior around 15.5 K.In addition,we find that the magnetic entropy change(-△S_(M))originates from the sample undergoing a ferromagnetic(FM)to paramagnetic(PM)transition around 20 K.Under a field change from 0 T to 7 T,the value of maximum magnetic entropy change(-△S_(M)^(max))reaches 12.5 J/kg·K,and the corresponding value of RC reaches 487.7 J/kg in the temperature range from 6 K to 60 K.The large RC and wide temperature range make the Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass be a promising material for application in magnetic refrigerators.
基金supported by the National Basic Research Program of China(Grant No.2014CB643702)the National Natural Science Foundation of China(Grant No.51590880)+1 种基金the Knowledge Innovation Project of the Chinese Academy of Sciences(Grant No.KJZD-EW-M05)the National Key Research and Development Program of China(Grant No.2016YFB0700903)
文摘Data-mining techniques using machine learning are powerful and efficient for materials design, possessing great potential for discovering new materials with good characteristics. Here, this technique has been used on composition design for La(Fe,Si/Al)_(13)-based materials, which are regarded as one of the most promising magnetic refrigerants in practice. Three prediction models are built by using a machine learning algorithm called gradient boosting regression tree(GBRT) to essentially find the correlation between the Curie temperature(T_C), maximum value of magnetic entropy change((?S_M)_(max)),and chemical composition, all of which yield high accuracy in the prediction of T_C and(?SM)_(max). The performance metric coefficient scores of determination(R^2) for the three models are 0.96, 0.87, and 0.91. These results suggest that all of the models are well-developed predictive models on the challenging issue of generalization ability for untrained data, which can not only provide us with suggestions for real experiments but also help us gain physical insights to find proper composition for further magnetic refrigeration applications.
基金Project supported by the National Natural Science Foundation of China(Grant No.51690162)Science and Technology Committee of Shanghai,China(Grant No.19ZR1418300)+1 种基金Independent Research and Development Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(Grant No.SKLASS 2019-Z003)the Science and Technology Commission of Shanghai Municipality,China(Grant No.19DZ2270200).
文摘Nowadays,magnetic cooling(MC) technology by using the magnetocaloric effect(MCE) has attracted extensive research interest for its promising practical applications.A constant large/giant MCE covers wide refrigeration temperatures(denote as table-like shape) is beneficial for obtaining high efficiency performance for MC.In this paper,the HoNi/HoNi2 composite was successfully synthesized by arc-melting method and proved to be composed of HoNi and HoNi2 crystalline phases with weight ratios of 52.4 wt.% and 47.6 wt.%,respectively.The maximum magnetic entropy change(-ΔSMmax)is 18.23 J/(kg·K),and the refrigerant capacity values RC1,RC2,and RC3 are 867.9 J/kg,676.4 J/kg,and 467.8 J/kg with ΔH=0-70 kOe,respectively.The table-like shape MCE and large refrigerant capacity values make the composite attractive for cryogenic MC using the Ericsson cycle.
基金supported by the National Natural Science Foundation of China(Grant Nos.51301008 and 51171003)the Beijing Natural Science Foundation,China(Grant No.1112005)
文摘In this paper, we study the effects of Pr substitution on the hydrogenating process and magnetocaloric properties of La_(1-x)Pr_xFe_(11.4)Si_(1.6)H_y hydrides. The powder x-ray diffraction patterns of the La_(1-x)Pr_xFe_(11.4)Si_(1.6) and its hydrides show that each of the alloys is crystallized into the single phase of cubic Na Zn_(13)-type structure. There are hydrogen-absorbing plateaus under 0.4938 MPa and 0.4882 MPa in the absorbing curves for the La_(0.8)Pr_(0.2)Fe_(11.4)Si_(1.6) and La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6) compounds. The releasing processes lag behind the absorbing process, which is obviously different from the coincidence between absorbing and releasing curves of the La Fe_(11.4)Si_(1.6) compound. The remnant hydrogen content for La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6) is significantly more than that for La_(0.8)Pr_(0.2)Fe_(11.4)Si_(1.6) after hydrogen desorption, indicating that more substitutions of Pr for La are beneficial to retaining more hydrogen atoms in the alloys. The values of maximum magnetic entropy change are 14.91 J/kg·K and 17.995 J/kg·K for La_(0.8)Pr_(0.2)Fe_(11.4)Si_(1.6)H_(0.13) and La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6)H_(0.87),respectively.
基金Project supported by the Open Research Project of State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilizationthe National Natural Science Foundation of China(Grant Nos.51771197 and 52171187)。
文摘Due to the hydrogen embrittlement effect,La(Fe,Si)_(13)-based hydrides can only exist in powder form,which limits their practical application.In this work,ductile and thermally conductive Al metal was homogeneously mixed with La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)using the ball milling method.Then hydrogenation and compactness shaping of the magnetocaloric composites were performed in one step via a sintering process under high hydrogen pressure.As the Al content reached 9 wt.%,the La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)H_(y)/Al composite showed the mechanical behavior of a ductile material with a yield strength of~44 MPa and an ultimate strength of 269 MPa accompanied by a pronounced improvement in thermal conductivity.Due to the ease of formation of Fe-Al-Si phases and the several micron and submicron sizes of the composite particles caused by ball milling process,the magnetic entropy change of the composites was substantially reduced to~1.2 J/kg·K-1.5 J/kg·K at 0 T-1.5 T.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52171174 and 91963123)the Ten Thousand Talents Plan of Zhejiang Province(No.2018R52003)the Fundamental Research Funds for the Provincial University of Zhejiang(No.GK199900299012-022).
文摘The magnetic functional materials play a particularly important role in our modern society and daily life.The magnetocaloric effect(MCE)is at the basis of a solid state magnetic refrigeration(MR)technology which may enhance the efficiency of cooling systems,both for room temperature and cryogenic appli-cations.Despite numerous experimental and theoretical MCE studies,commercial MR systems are still at developing stage.Designing magnetic solids with outstanding magnetocaloric performances remains therefore a most urgent task.Herein,recent progresses on characterizing the crystal structure,magnetic properties and cryogenic MCE of rare earths(RE)-based RE_(2)TMTM’O_(6)double perovskite(DP)oxides,where TM and TM’are different 3d transition metals,are summarized.Some Gd-based DP oxides are found to exhibit promising cryogenic magnetocaloric performances which make them attractive for active MR ap-plications.
基金Project supported by the Science and Technology Development Fund of Higher Education of Tianjin,China(20130301)the Tianjin Research Program of Application Foundation and Advanced Technology,China(14JCQNJC4000)the National Natural Science Foundation of China(11604242)
文摘The microstructure, magnetic entropy changes, hysteresis and magnetic properties of La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.5–x)Si_x(x=0.4, 0.5, 0.6, 0.7) compounds were studied by X-ray diffraction(XRD) and a superconducting quantum interference device magnetometer(SQUID). The results showed that all the compounds presented cubic Na Zn13-type structure. Their Curie temperatures changed complicatedly with decreasing Al content due to changes of antiferromagnetic and ferromagnetic interaction. Under a field change from 0 to 2 T, the maximum magnetic entropy change for La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.1)Si_(0.4), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.0)Si_(0.5), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.9)Si_(0.6) and La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.8)Si_(0.7) were found to be –9.6, –4.8, –5.8 and –11.7 J/(kg·K), respectively. Moreover, their hysteresis losses were 1.13 J/(kg·K) or less. The large magnetic entropy changed and small hysteresis losses made them potential candidates for practical magnetic refrigeration application.
基金the National Natural Science Foundation of China(11164019,51562032,61565013)Inner Mongolia Natural Science Foundation of China(2015MS0101,2015MS0109)+2 种基金Inner Mongolia Institute of Science and Technology Key Project Fund(NJZZ11166,NJZY16237,NJZY12202)Board Project(201522011)Natural Science Foundation of Henan Province(182300410248)。
文摘Tb1-xTmxFeO3(x = 0.00,0.15,0.25) polycrystalline series were synthesized using a solid-state reaction.Our results show that all three prepared samples are in a distorted orthogonal structure and their space group is pbnm.When the Tm3+doping amount increases,the characteristics of the spin-flip of the sample decreases following an initial increase at the beginning;the antiferromagnetic property almost reaches zero;the magnetization decreases at the beginning but increases later on.The maximum magnetic entropy change and magnetic refrigeration effect RCP are reduced at varying degrees.Under a 7 T magnetic field,the maximum magnetic entropy change,△Smax,for the three samples of Tb1-xTmxFeO3 with x=0.00,0.15,0.25 is 13.78,-9.28,and 10.69 J/(K·kg),respectively;the magnetic refrigeration capacity(RCP) is 316.85,175.2,and 297.60 J/kg,respectively.In summary,doping with the element Tm reduces △Smax and RCP of the sample.Since the maximum magnetic entropy change and the cooling capacity for the three samples are relatively large,they can be used as an alternative for magnetic refrigerants.
基金financially supported by the National Natural Science Foundation of China(No.51827801)the support by the Overseas Visiting Study Program of Harbin Institute of Technology。
文摘This paper presents a systematic investigation of the microstructure and magnetocaloric properties of melt-extracted Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)high-entropy microwires.The fabricated wires exhibited an amorphous structure,and the temperature interval of the undercooled liquid AT was 45 K.The microwires underwent a second-order magnetic transition from a ferromagnetic to a paramagnetic state near the Curie temperature(T_(C)=52 K),The maximum magnetic entropy change(-ΔS_M^(max)),the relative cooling power and the refrigeration capacity reached 6.34 J·kg^(-1)·K^(-1).422.09 J·kg^(-1)and 332.94 J·kg^(-1),respectively,under a magnetic field change of 5 T.In addition,the temperature-averaged entropy changes with two temperature lifts(3 and 10 K)were 6.32 and 6.27 J·kg^(-1)·K^(-1),respectively.The good magnetocalorie performance highlights the significant potential for the Sm_(20)Gd_(20)Dy_(20)Co_(20)Al_(20)microwires to be used as magnetic refrigerant materials in low-temperature region applications.This work will serve as a valuable reference for future investigations on low-temperature high-entropy magnetocaloric materials.
基金supported by Shenzhen Science and Technology Program (No.JCYJ20180306170859634)National Natural Science Foundation of China (Nos.21773130,21801202,21871219, 21971203 and 21620102002)+4 种基金Shaanxi National Science Foundation (No.2019JQ-016)China Postdoctoral Science Foundation (Nos. 2019T120891 and 2018M643615)Key Laboratory Construction Program of Xi’an Municipal Bureau of Science and Technology (No. 201805056ZD7CG40)Cyrus Chung Ying Tang Foundation and Fundamental Research Funds for Central Universitiessupported by the Deutsche Forschungsgemeinschaft DFG (Nos.314331397,SCHN 615/23-1)。
文摘A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;Gd,5),was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid,2-hydroxypyridine,Cu(CH_(3)COO)_(2)·H_(2)O,and Ln(ClO_(4))_(3)·6 H_(2)O.Notably,the [Cu_(6)Ln_(5)] clusters with high molecular symmetry of D_(3h) are rare examples of2-aminoisobutyric acid-based 3 d-4 f clusters.The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K,whereas the Gd-Cu exchange is an order of magnitude larger.Magnetization data collected for comp lex 5 yield a magnetic entropy change(-ΔSm) of 19.6 J kg^(-1) K^(-1)<1 at 3 K and 7 T,which may be attributed to the weak magnetic interactions between the component metal ions.
基金supported by the National Key R&D Program of China(2018YFA0306004)the National Natural Science Foundation of China(21571103,21973038)+1 种基金Jiangsu Province(BK20191359)the Joint Fund for Regional Innovation and Development(U20A2073)。
文摘It is a meaningful and challenging work for structural and synthetic chemists to isolate nano-sized high-nuclearity cluster-molecules.In this work,two largest hetero-metallic nano-clusters Gd_(158)Co_(38) were obtained via the“multi-anions-template”method.Different from the reported giant hollow-nano-clusters,the Ln_(158) core in Gd_(158)Co_(38)(the protein-sized nano-clusters,ca.4.3 nm×3.6 nm×3.5 nm)has the highest Ln nuclear number,which is integrated by twelve halide ions(with the form of icosahedron)as key templates,while Co ions(as 3d metals)are located in its periphery.This emergence indicates a novel structure form of non-open Ln-containing high-nuclearity clusters,and affords a consummate pattern to analyse and assemble the complex cluster-molecules.In addition,Gd_(158)Co_(38)@Cl_(12)breaks the record magnetic entropy change of 3d-4f clusters with−∆S_(m)^(max)=46.95 J kg^(−1)K^(−1)at 7.0 T,2.0 K.
基金Project supported by the National Science Fund for Distinguished Young Scholars (51925605)the National Key R&D Program of China (2019YFA0704904)+1 种基金the National Natural Science Foundation of China (52171195)the Basic Frontier Scientific Research Program of Chinese Academy of Sciences From 0 to 1 Original Innovation Project (ZDBS-LY-JSC017)。
文摘Borates have attained increasing attention attributed to their excellent thermal stability,distinctive thermodynamic property,and high mechanical strength in recent years.A series of polycrystalline Dydoped GdBO_(3) compounds was prepared,their crystal structures,magnetic properties,and cryogenic magnetocaloric effects were comprehensively investigated.The compounds crystallize in hexagonal structure(space group P6_(3)/mmc),the lattice constant decreases with the increase of Dy content.Dydoping in GdBO_(3) significantly reduces critical magnetic field and enhances low-field magnetocaloric effect.The maximum magnetic entropy changes for the Gd_(1-x)Dy_(x)BO_(3)(x=0.6,0.8,and 1)compounds in a field change of 2 T surpass 17.3 J/(kg·K)at 2.5 K,enhanced by nearly 120%compared to GdBO_(3)(8.0 J/(kg·K)).Besides,the corresponding refrigeration capacity increases from 33.9 to 62.2,57.2,and 72.5 J/kg,respectively,with an enhancement of 70%-110%.The considerable maximum magnetic entropy change,refrigerating capacity,and temperature averaged entropy change make them competitive candidates for cryogenic magnetic refrigeration.
基金the National Natural Sci-ence Foundation of China(Grant No.52071197)the National Science Foundation for Distinguished Young Scholars(Grant No.51925605)the National Science Foundation for Excellent Young Scholars(Grant No.52222107).
文摘Magnetic refrigeration based on the magnetocaloric effect(MCE)of magnetic solids has been considered as an emerging technology for hydrogen liquefaction.However,the lack of high-performance materials has slowed the development of any practical applications.Here,we present a family of rare-earth cobalt nickel-based magnetocaloric materials,namely Dy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds,and system-atically investigated their structural and magnetic properties as well as the MCE and magnetocaloric per-formance.All of these compounds crystallize in the C15-type Laves-phase structure and undergo typi-cal second-order magnetic phase transition(MPT).The change in magnetism and the MPT temperature for the Dy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds originate from the exchange interactions between nearest-neighbor RE 3+ion pairs.No hysteresis magnetocaloric effect was achieved,and the MPT tem-perature of these compounds could be tuned from the liquefaction temperature of nitrogen(∼77 K)to hydrogen(∼20 K)by adjusting the ratio of rare-earth elements.This study’s findings indicate that theDy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds are of potential for practical magnetic refrigeration applica-tions in the field of hydrogen liquefaction.
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supported by the National Key Research and Development Program of China(2022YFB3505101)the National Science Foundation for Excellent Young Scholars(52222107)+2 种基金the National Science Foundation for Distinguished Young Scholars(51925605)the Research Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(E055B002)the Doctoral Postgraduate Innovation Funding project of Hebei Province(CXZZBS2023032)。