Crystallographic structure, magnetic properties, and magnetic entropy change of the Cr-based spinel sulfides Co1-xCuxCr2S4 （x =0-0.8） have been investigated. All these compounds crystallize into the cubic spinel str...Crystallographic structure, magnetic properties, and magnetic entropy change of the Cr-based spinel sulfides Co1-xCuxCr2S4 （x =0-0.8） have been investigated. All these compounds crystallize into the cubic spinel structure, the Cu substitution shrinks linearly the lattice constant at a ratio of 0.0223 A per Cu atom in the unit cell, and enhances linearly the Curie temperature and the spontaneous magnetization at the rates of 18 K and 0.33 μB/f.u, per Cu atom in the unit cell, respectively. All these compounds show a typical behavior of second order magnetic transition, and a room temperature magnetic entropy change of 2.57 J/kg.K is achieved for Co0.4Cu0.6Cr2S4.展开更多
In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12...In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12）Co_7 series, R_3 Co series and RCu_2series）, which have been investigated in detail in the past several years. The R–T compounds are studied by means of magnetic measurements, heat capacity measurements, magnetoresistance measurements and neutron powder diffraction measurements. The R–T compounds show complex magnetic transitions and interesting magnetic properties.The types of magnetic transitions are investigated and confirmed in detail by multiple approaches. Especially, most of the R–T compounds undergo more than one magnetic transition, which has significant impact on the magnetocaloric effect of R–T compounds. The MCE of R–T compounds are calculated by different ways and the special shapes of MCE peaks for different compounds are investigated and discussed in detail. To improve the MCE performance of R–T compounds,atoms with large spin（S） and atoms with large total angular momentum（J） are introduced to substitute the related rare earth atoms. With the atom substitution, the maximum of magnetic entropy change（？SM）, refrigerant temperature width（Twidth）or refrigerant capacity（RC） is enlarged for some R–T compounds. In the low temperature range, binary R–T（R = Pr, Gd,Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series,R_（12）Co_7 series, R_3 Co series and RCu_2series） show excellent performance of MCE, indicating the potential application for gas liquefaction in the future.展开更多
2-(2,3-Dihydroxpropyliminomethyl)6-methoxyphenol(H3L), trimethylacetic acid(Hpiv), Gd(NO3)3·6 H2O and Co(NO3)2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2(L)2(μ3-OH)2...2-(2,3-Dihydroxpropyliminomethyl)6-methoxyphenol(H3L), trimethylacetic acid(Hpiv), Gd(NO3)3·6 H2O and Co(NO3)2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2(L)2(μ3-OH)2(piv)6]·2 Hpiv·2 CH3OH(1). X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798(6), b = 12.0877(5), c = 15.0367(7) A, α = 67.320(4)°, β = 81.583(4)°, γ = 75.201(4)°, V =1939.62(18) A3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ(I). In magnetization study, heterometallic 1 exhibits magnetocaloric effect(MCE) of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.展开更多
Phase transition process and magnetic entropy change -Delta S of Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys were studied. Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys still underwent simultaneous structural an...Phase transition process and magnetic entropy change -Delta S of Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys were studied. Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys still underwent simultaneous structural and magnetic transitions and transform from ferro-magnetic martensitic phase to paramagnetic austenitic phase during heating. Under a field of 2 T, the maximum magnetic entropy change -Delta S-M of Ni55.2Mn18.6Ga26.15Gd0.05 alloy was 7.7 J/kg.K at 317 K during heating and 8.6 J/kg.K at 314 K during cooling while it was 11.8 J/kg.K at 317 K in Ni55.2Mn18.6Ga26.05Gd0.15 alloy during heating.展开更多
Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applicati...Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applications at low temperatures.Here,a giant low-field magnetocaloric effect in ferromagnetically ordered Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds was reported,and the magnetic structure was characterized based on low-temperature neutron powder diffraction.With increasing Tm content from 0 to 1,the Curie temperature of Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds decreases from 16.0 K to 3.6 K.For Er_(0.7)Tm_(0.3)Al_(2) compound,it showed the largest low-field magnetic entropy change(–SM)with the peak value of 17.2 and 25.7 J/(kg K)for 0–1 T and 0–2 T,respectively.The(–SM)max up to 17.2 J/(kg K)of Er0.7Tm0.3Al2 compound for 0–1 T is the largest among the intermetallic magnetocaloric materials ever reported at temperatures below 20 K.The peak value of adiabatic temperature change(Tad)max was determined as 4.13 K and 6.87 K for 0–1 T and 0–2 T,respectively.The characteristic of second-order magnetic transitions was confirmed on basis of Arrott plots,the quantitative criterion of exponent n,rescaled universal curves,and the mean-field theory criterion.The outstanding low-field MCE performance with low working temperatures indicates that Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds are promising candidates for magnetic cooling materials at liquid hydrogen and liquid helium temperatures.展开更多
Magnetic refrigeration based on the magnetocaloric effect(MCE)is a novel refrigeration technology that will replace traditional vapor-compression refrigeration in the future.Improvement in the performance of MCE mater...Magnetic refrigeration based on the magnetocaloric effect(MCE)is a novel refrigeration technology that will replace traditional vapor-compression refrigeration in the future.Improvement in the performance of MCE materials is crucial for the development of magnetic refrigeration technology.This study presents a new method that enhances the MCE performance of(Sc,Ti)Fe_(2) via magnetic phase separation.The maximum magnetic entropy change induced by the coexistence of an in-plane ferromagnetic phase(FMab)and a canting antiferromagnetic phase(CAFM)in Sc_(0.3)Ti_(0.7)Fe_(2) is twice that found in other(Sc,Ti)Fe_(2 )compounds.Variable-temperature neutron diffraction experiments directly reveal that the large magnetic entropy change in Sc_(0.3)Ti_(0.7)Fe_(2) is dominated by the transformation from a highly ordered FMab state to a CAFM state with a lower magnetic order.The magnetic phase separation is a direct transition from a higher-ordered state with a larger lattice to a lower-ordered state with a smaller lattice that induces a large magnetic order change and lattice contraction.The combination of the metamagnetic transition and negative thermal expansion leads to enhanced MCE.This study suggests the possibility that magnetic phase separation can be an effective approach to achieving and controlling a large MCE in magnetic materials.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 phases in alloys(Tb1–xCex)Co2 with x=0,0.1,0.2,0.3,0.4 and 0.5 were investigated by X-ray diffraction analysis,and the magnetocaloric effect for x=0–0.4 was studied by magnetization measurement.The samples were ...The phases in alloys(Tb1–xCex)Co2 with x=0,0.1,0.2,0.3,0.4 and 0.5 were investigated by X-ray diffraction analysis,and the magnetocaloric effect for x=0–0.4 was studied by magnetization measurement.The samples were almost single phase with MgCu2-type cubic structure.The magnetization decreased with the increase of Ce.The Curie temperatures(Tc) of Tb1–xCexCo2 alloys with x from 0.1 to 0.4 were 180,165,160 and 152 K,respectively.For x=0.5 in the range from 100 K to 230 K,the point of magnetic transition was n...展开更多
Two metal (Ⅱ) complexes based on 1,3,5-triazine-2,4,6-triyltrithio-tri-acetate exhibit similar (6,3)-connected 2D layer with kgd topology. Negative and positive magnetic field effects (MFEs) on the fluorescence prope...Two metal (Ⅱ) complexes based on 1,3,5-triazine-2,4,6-triyltrithio-tri-acetate exhibit similar (6,3)-connected 2D layer with kgd topology. Negative and positive magnetic field effects (MFEs) on the fluorescence properties of the Mn(Ⅱ) and Zn(Ⅱ) complexes are observed, respectively.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274369,51472210,and 11675255)
文摘Crystallographic structure, magnetic properties, and magnetic entropy change of the Cr-based spinel sulfides Co1-xCuxCr2S4 （x =0-0.8） have been investigated. All these compounds crystallize into the cubic spinel structure, the Cu substitution shrinks linearly the lattice constant at a ratio of 0.0223 A per Cu atom in the unit cell, and enhances linearly the Curie temperature and the spontaneous magnetization at the rates of 18 K and 0.33 μB/f.u, per Cu atom in the unit cell, respectively. All these compounds show a typical behavior of second order magnetic transition, and a room temperature magnetic entropy change of 2.57 J/kg.K is achieved for Co0.4Cu0.6Cr2S4.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274357,51501005,51590880,and 11674008)the Fundamental Research Funds for the Central Universities,China(Grant No.FRF-TP-15-010A1)+1 种基金the China Postdoctoral Science Foundation(Grant No.2016M591071)the Key Research Program of the Chinese Academy of Sciences(Grant No.KJZD-EW-M05)
文摘In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12）Co_7 series, R_3 Co series and RCu_2series）, which have been investigated in detail in the past several years. The R–T compounds are studied by means of magnetic measurements, heat capacity measurements, magnetoresistance measurements and neutron powder diffraction measurements. The R–T compounds show complex magnetic transitions and interesting magnetic properties.The types of magnetic transitions are investigated and confirmed in detail by multiple approaches. Especially, most of the R–T compounds undergo more than one magnetic transition, which has significant impact on the magnetocaloric effect of R–T compounds. The MCE of R–T compounds are calculated by different ways and the special shapes of MCE peaks for different compounds are investigated and discussed in detail. To improve the MCE performance of R–T compounds,atoms with large spin（S） and atoms with large total angular momentum（J） are introduced to substitute the related rare earth atoms. With the atom substitution, the maximum of magnetic entropy change（？SM）, refrigerant temperature width（Twidth）or refrigerant capacity（RC） is enlarged for some R–T compounds. In the low temperature range, binary R–T（R = Pr, Gd,Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series,R_（12）Co_7 series, R_3 Co series and RCu_2series） show excellent performance of MCE, indicating the potential application for gas liquefaction in the future.
基金supported by the National Natural Science Foundation of China(No.21771043,51572050 and 21601038)Guangxi Natural Science Foundation(No.2015GXNSFDA139007 and 2016GXNSFAA380085)Guangxi Key Laboratory of Electrochemical and Magnetochemical Functional Materials(EMFM20162107)
文摘2-(2,3-Dihydroxpropyliminomethyl)6-methoxyphenol(H3L), trimethylacetic acid(Hpiv), Gd(NO3)3·6 H2O and Co(NO3)2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2(L)2(μ3-OH)2(piv)6]·2 Hpiv·2 CH3OH(1). X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798(6), b = 12.0877(5), c = 15.0367(7) A, α = 67.320(4)°, β = 81.583(4)°, γ = 75.201(4)°, V =1939.62(18) A3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ(I). In magnetization study, heterometallic 1 exhibits magnetocaloric effect(MCE) of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.
基金Project supported by the National Science Foundation of Chinathe National Basic Research Program of China and Institute of Physics,Chinese Academy of Sciences
文摘Phase transition process and magnetic entropy change -Delta S of Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys were studied. Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys still underwent simultaneous structural and magnetic transitions and transform from ferro-magnetic martensitic phase to paramagnetic austenitic phase during heating. Under a field of 2 T, the maximum magnetic entropy change -Delta S-M of Ni55.2Mn18.6Ga26.15Gd0.05 alloy was 7.7 J/kg.K at 317 K during heating and 8.6 J/kg.K at 314 K during cooling while it was 11.8 J/kg.K at 317 K in Ni55.2Mn18.6Ga26.05Gd0.15 alloy during heating.
基金supported by the National Key Research and Development Program of China(Nos.2021YFB3501202 and 2019YFB2005800)the Science Center of the National Science Foundation of China(No.52088101)+1 种基金the National Natural Science Foundation of China(Nos.51871019,52171170,52130103,51961145305,51971026,and 52171169)the Beijing Natural Science Foundation Key Program(Grant Nos.Z190007 and Z200007),and“111 Project”(No.B170003).
文摘Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applications at low temperatures.Here,a giant low-field magnetocaloric effect in ferromagnetically ordered Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds was reported,and the magnetic structure was characterized based on low-temperature neutron powder diffraction.With increasing Tm content from 0 to 1,the Curie temperature of Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds decreases from 16.0 K to 3.6 K.For Er_(0.7)Tm_(0.3)Al_(2) compound,it showed the largest low-field magnetic entropy change(–SM)with the peak value of 17.2 and 25.7 J/(kg K)for 0–1 T and 0–2 T,respectively.The(–SM)max up to 17.2 J/(kg K)of Er0.7Tm0.3Al2 compound for 0–1 T is the largest among the intermetallic magnetocaloric materials ever reported at temperatures below 20 K.The peak value of adiabatic temperature change(Tad)max was determined as 4.13 K and 6.87 K for 0–1 T and 0–2 T,respectively.The characteristic of second-order magnetic transitions was confirmed on basis of Arrott plots,the quantitative criterion of exponent n,rescaled universal curves,and the mean-field theory criterion.The outstanding low-field MCE performance with low working temperatures indicates that Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds are promising candidates for magnetic cooling materials at liquid hydrogen and liquid helium temperatures.
基金supported by the National Key Research and Development Program of China(No.2022YFE0109100)the National Natural Science Foundation of China(21825102,22275014,and 12104038)the Youth Talent Promotion Project from China Association for Science and Technology,and the Fundamental Research Funds for the Central Universities,China(06500201).
文摘Magnetic refrigeration based on the magnetocaloric effect(MCE)is a novel refrigeration technology that will replace traditional vapor-compression refrigeration in the future.Improvement in the performance of MCE materials is crucial for the development of magnetic refrigeration technology.This study presents a new method that enhances the MCE performance of(Sc,Ti)Fe_(2) via magnetic phase separation.The maximum magnetic entropy change induced by the coexistence of an in-plane ferromagnetic phase(FMab)and a canting antiferromagnetic phase(CAFM)in Sc_(0.3)Ti_(0.7)Fe_(2) is twice that found in other(Sc,Ti)Fe_(2 )compounds.Variable-temperature neutron diffraction experiments directly reveal that the large magnetic entropy change in Sc_(0.3)Ti_(0.7)Fe_(2) is dominated by the transformation from a highly ordered FMab state to a CAFM state with a lower magnetic order.The magnetic phase separation is a direct transition from a higher-ordered state with a larger lattice to a lower-ordered state with a smaller lattice that induces a large magnetic order change and lattice contraction.The combination of the metamagnetic transition and negative thermal expansion leads to enhanced MCE.This study suggests the possibility that magnetic phase separation can be an effective approach to achieving and controlling a large MCE in magnetic materials.
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.
文摘The phases in alloys(Tb1–xCex)Co2 with x=0,0.1,0.2,0.3,0.4 and 0.5 were investigated by X-ray diffraction analysis,and the magnetocaloric effect for x=0–0.4 was studied by magnetization measurement.The samples were almost single phase with MgCu2-type cubic structure.The magnetization decreased with the increase of Ce.The Curie temperatures(Tc) of Tb1–xCexCo2 alloys with x from 0.1 to 0.4 were 180,165,160 and 152 K,respectively.For x=0.5 in the range from 100 K to 230 K,the point of magnetic transition was n...
基金Funded by the Fundamental Research Funds for the Central Universities ( NO. CQDXWL-2012-024)
文摘Two metal (Ⅱ) complexes based on 1,3,5-triazine-2,4,6-triyltrithio-tri-acetate exhibit similar (6,3)-connected 2D layer with kgd topology. Negative and positive magnetic field effects (MFEs) on the fluorescence properties of the Mn(Ⅱ) and Zn(Ⅱ) complexes are observed, respectively.
