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1.
We investigate the influence of Sb-doping on the martensitic transformation and magnetocaloric effect in Mn_(50)Ni_(40)Sn_(10-x)Sb_x(x = 1, 2, 3, and 4) alloys. All the prepared samples exhibit a B2-type structure with the space group F m3 m at room temperature. The substitution of Sb increases the valence electron concentration and decreases the unit cell volume. As a result, the magnetostructural transformation shifts rapidly towards higher temperatures as x increases.The changes in magnetic entropy under different magnetic field variations are explored around this transformation. The isothermal magnetization curves exhibit typical metamagnetic behavior, indicating that the magnetostructural transformation can be induced by a magnetic field. The tunable martensitic transformation and magnetic entropy changes suggest that Mn_(50)Ni_(40)Sn_(10-x)Sb_x alloys are attractive candidates for applications in solid-state refrigeration.  相似文献   

2.
The magnetic phase transition and magnetocaloric effect are studied in a series of Mn1-xZnxCoGe(x = 0.01, 0.02,0.04, and 0.08) alloys. By introducing a small quantity of Zn element, the structural transformation temperature of the MnCoGe alloy is greatly reduced and a first-order magnetostructural transition is observed. Further increasing the Zn concentration results in a second-order ferromagnetic transition. Large room-temperature magnetocaloric effects with small magnetic hysteresis are obtained in alloys with x = 0.01 and 0.02, which suggests their potential application in magnetic refrigeration.  相似文献   

3.
The magnetic properties and magnetocaloric effect(MCE)of EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds are investigated.Owing to electronic doping,parts of Ti ions are replaced by Nb ions,the lattice constant increases and a small number of Ti4+(3d^0)ions change into Ti3+(3d^1).It is the ferromagnetism state that is dominant in the derivative balance.The values of the maximum magnetic entropy change(-?SMmax)are 10.3 J/kg·K,9.6 J/kg·K,13.1 J/kg·K,and 11.9 J/kg·K for EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds and the values of refrigeration capacity are 36,33,86,and 80 J/kg as magnetic field changes in a range of 0 T–1 T.The EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds with giant reversible MCE are considered as a good candidate for magnetic refrigerant working at lowtemperature and low-field.  相似文献   

4.
In this work, we tuned the magnetostructural transformation and the coupled magnetocaloric properties of Mn_(48-x)V_xNi_(42)Sn_(10)(x = 0, 1, 2, and 3) ferromagnetic shape memory alloys prepared by means of partial replacement of Mn by V. It is observed that the martensitic transformation temperatures decrease with the increase of V content. The shift of the transition temperatures to lower temperatures driven by the applied field, the metamagnetic behavior, and the thermal hysteresis indicates the first-order nature for the magnetostructural transformation. The entropy changes with a magnetic field variation of 0–5 T are 15.2, 18.8, and 24.3 J·kg~(-1)·K~(-1) for the x = 0, 1, and 2 samples, respectively. The tunable martensitic transformation temperature, enhanced field driving capacity, and large entropy change suggest that Mn_(48-x)V_xNi_(42)Sn_(10) alloys have a potential for applications in magnetic cooling refrigeration.  相似文献   

5.
张虎  邢成芬  龙克文  肖亚宁  陶坤  王利晨  龙毅 《物理学报》2018,67(20):207501-207501
磁熵变(△SM)与磁场(μ0H)的相关性已在很多二级相变材料中被研究并报道,但一级相变材料的磁热效应与磁场相关性还少有报道.本文在具有一级磁结构相变的Mn0.6Fe0.4NiSi0.5Ge0.5材料中研究发现△SM与μ0H存在线性相关性,并通过麦克斯韦关系式的数值分析详细讨论了这一线性相关性的来源.同时,进一步发现在低磁场时,△SM近似正比于μ0H的平方.该线性相关性同样在一级磁结构相变Ni50Mn34Co2Sn14材料中得到了印证.但由于一级磁弹相变LaFe11.7Si1.3材料相变温度具有更强的磁场依赖性,不具有△SM的线性相关性,因此,本研究表明,当磁结构相变材料的相变温度具有弱磁场依赖性时,△SM与μ0H具有线性相关性.进而,在磁场未达到相变饱和磁场以下,利用△SM与μ0H的线性相关性可以有效推测更高磁场下的△SM.  相似文献   

6.
The magnetic properties and magnetocaloric effect(MCE) in EuTi_(1-x)Co_xO_3(x = 0, 0.025, 0.05, 0.075, 0.1) compounds have been investigated. When the Ti~(4+) ions were substituted by Co2+ions, the delicate balance was changed between antiferromagnetic(AFM) and ferromagnetic(FM) phases in the EuTiO_3 compound. In EuTi_(1-x)Co_xO_3 system, a giant reversible MCE and large refrigerant capacity(RC) were observed without hysteresis. The values of -?S_M~(max) were evaluated to be around 10 J·kg~(-1)·K~(-1) for EuTi_(0.95)Co_(0.05)O_3 under a magnetic field change of 10 kOe. The giant reversible MCE and large RC suggests that EuTi_(1-x)Co_xO_3 series could be considered as good candidate materials for low-temperature and low-field magnetic refrigerant.  相似文献   

7.
The crystal structure, phase transition, and magnetocaloric effect in Ni42.8Mn40.3Co5.7Sn11.2 alloy are investigated by structure analysis and magnetic measurements. A large magnetic entropy change of 45.6 J/kg.K is obtained at 215 K under a magnetic field of 30 kOe (1 Oe = 79.5775 A.m-1). The effective refrigerant capacity of Ni42.8Mn40.3Co5.7Sn11.2 alloy reaches 72.1 J/kg under an applied field changing from 0 to 30 kOe. The external magnetic field shifts the martensitic transition temperature about 3-4 K/10 kOe towards low temperature, indicating that magnetic field can retard the phase transition to a certain extent. The origin of large magnetic entropy change is discussed in the paper.  相似文献   

8.
Ersin Civan  Kagan Sarlar 《哲学杂志》2013,93(18):1464-1478
Abstract

The impacts of adding Cr on the Curie temperature (TC), glass-forming ability (GFA), and magnetocaloric effect were studied in Fe68?xCrxTb5B23Nb4 (x = 0, 2, 4, 6 and 8) metallic glasses prepared by suction casting. GFA depends on Cr content in the composition. For Fe68?xCrxTb5B23Nb4 bulk metallic glasses (BMGs), with critical diameters up to ~3 mm can be produced by suction casting and maximum value of GFA was found for x = 6. By exchanging Cr with Fe partially, TC could effectively be adjusted in a quite broad temperature interval from 487 K for x = 0 to 267 K for x = 8, whereas maximum magnetic entropy change decreased from 1.16 to 0.53 Jkg?1 K?1 and refrigeration capacity (RC) changed from 116 to 45.05 J/kg under a low field change of 2 T. Though TC is shifted to room temperature, maximum magnetic entropy change and RC decreased almost half of the base alloy. To enhance these properties (Fe0.62Cr0.06Tb0.05B0.23Nb0.04)100?yCuy (y = 0.75, 1), metallic glasses are prepared. By the help of small addition of Cu, magnetocaloric properties can be effectively increased without changing the TC. These findings show that the successful synthesis of the Fe-based Fe62Cr6Tb5B23Nb4 and (Fe0.62Cr0.06Tb0.05B0.23Nb0.04)100?yCuy (y = 0.75, 1) BMGs near room temperature, could be considered as promising candidates as magnetic refrigerant materials.  相似文献   

9.
10.
郝志红  王海英  张荃  莫兆军 《物理学报》2018,67(24):247502-247502
EuTi0_3是直接带隙半导体材料,在液氦温度附近呈现反铁磁性,且具有较大的磁熵变,但是当其转变为铁磁性时,可以有效提高低磁场下的磁熵变.本文通过元素替代,研究晶格常数的变化和电子掺杂对磁性和磁热效应的影响.实验采用溶胶凝胶法制备EuTiO_3和Eu_(0.9)M_(0.1)TiO_3 (M=Ca, Sr, Ba, La, Ce, Sm)系列样品.结果表明:大离子半径的碱土金属离子替代提高了铁磁性耦合,有利于提高低磁场下的磁热效应.电子掺杂可以抑制其反铁磁性耦合从而使其表现为铁磁性.当大离子半径的稀土La和Ce离子替代Eu离子时,既增大了晶格常数也实现了电子掺杂,表现出较强的铁磁性.在1 T的磁场变化下,Eu_(0.9)La_(0.1)TiO_3和Eu_(0.9)Ce_(0.1)TiO_3的最大磁熵变分别为10.8和11 J/(kg·K),均大于EuTi0_3的9.8 J/(kg·K);制冷能力分别为39.3和51.8 J/kg,相对于EuTi0_3也有所提高.  相似文献   

11.
郑新奇  沈保根 《中国物理 B》2017,26(2):27501-027501
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.  相似文献   

12.
Hydrogenation, crystal structure and magnetic properties of La(Fe0.91Si0.09)13H(D)y have been studied by pressure-composition isotherms (PCI), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and magnetization measurements. The maximum absorption capacity is found to be 1.9 H(D) atoms per formula unit as a solid solution. All hydrides and deuterides crystallize in the NaZn13-type cubic structure with the lattice parameter increasing linearly with H(D) concentration. The H(D) absorption enhances the Curie temperature significantly. The magnetic entropy change of the highly H-absorbed compound La(Fe0.91Si0.09)13H1.81 reaches ~26 J/kg·K under a magnetic field change of 5 T near the Curie temperature TC = 350 K. No observable isotope effect seems to imply that only the magnetovolume effect is responsible for the strong interplay between magnetism and lattice.  相似文献   

13.
沈保根  胡凤霞  董巧燕  孙继荣 《中国物理 B》2013,22(1):17502-017502
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 LaFe 13-xAlx can be converted to an FM one by substituting Si for Al,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 LaFe 11.5Al1.5C0.2H1.0 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.  相似文献   

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