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1.
We report on the magnetic properties and magnetocaloric effects of Mn5Ge3-xGax compounds with x=0.1,0.2,0.3,0.4,0.6 and 0.9. All samples crystallize in the hexagonal Mn5Si3-type structure with space group P63/mcm and order ferromagnetically.The Curie temperature of these compounds decreases with increasing x, from 306K (x=0.1) to 274K (x=0.9).The average Mn magnetic moments increases with increasing Ga content,reaching a maximum value at x=0.6.The magnetic entropy changes in these compounds are determined from the temperature and field dependence of the magnetization using the thermodynamic Maxwell relation.The Ga substitution has two kinds of influence on the magnetocaloric effect (MCE) of Mn5Ge3.One is that the magnitude of the magnetic entropy change decreases,the other is that the MCE peak becomes broadened. 相似文献
2.
Atomistic simulation of site preference, Curie temperature, and lattice vibration of Nd2Co7 - xFex 下载免费PDF全文
The effects of Fe substitution for Co on the structural stability and the site preference of intermetallics Nd 2 Co 7-x Fe x with a hexagonal Ce 2 Ni 7-type structure are studied by using a series of interatomic pair potentials.In Nd 2 Co 7-x Fe x,Fe atoms are substituted for Co atoms with a strong preference for the 6h sites and the order of site preference is 6h,4e,4f,2a,and 12k.Calculated lattice parameters are found to be consistent with the reported results in the literature.The variation behaviour of the Curie temperature of Nd 2 Co 7-x Fe x is explained qualitatively by the exchange interaction model.The properties related to lattice vibration,such as phonon density of states and Debye temperature,are first evaluated for the Nd 2 Co 7-x Fe x compounds. 相似文献
3.
《中国物理 B》2015,(4)
Mn substitution compounds YCo1-xMnx O3(0 ≤ x ≤ 0.2) are synthesized by using the sol–gel process. Electrical transport properties of YCo1-xMnx O3 are investigated in the temperature range from 200 K to 780 K. The experimental results show that after Mn substitution the electrical resistivity of YCo1-xMnx O3 first increases, then decreases, which is due to the electrons introduced by Mn doping. The sign of Seebeck coefficient for YCo1-xMnx O3(x = 0) is positive or negative, which is also proved by the Hall coefficient measurement. Moreover, at about room temperature, the Seebeck coefficient of YCo1-xMnx O3 with 1% doping Mn content becomes a negative value, whose absolute value is maximum;furthermore, the absolute value gradually decreases with increasing the Mn substitution content, which can be explained by the double carrier model. 相似文献
4.
Substituting AI for Fe in Pr(AlxFe1-x)1.9 alloys: Effects on magnetic and magnetostrictive properties 下载免费PDF全文
The magnetostrictive effects of substituting A1 for Fe in Pr(AlxFe1-x)1.9 (x = 0.0, 0.02, 0.05, 0.10) alloys between 5 K and 300 K were investigated. The substitution decreases the Curie temperature and the value of λ111. Fortunately, the substitution slightly increases the magnetostriction in a low magnetic field, which imbues these materials with potential advantages for applications. Rotation of the easy magnetization direction (EMD) from [ 111 ] to [ 100] in the Pr(A10.02Fe0.98)1.9 alloy as temperature decreases was detected by step scanned XRD reflections. 相似文献
5.
The influence of Ga or Si substitution for Co on the structural and magnetic properties of Pr2Co17 compounds is investigated. All samples studied here are single phase and have the rhombohedral Th2Zn17-type structure. The unit-cell volume is found to increase linearly by the substitution of Ga for Co,but reduce by the substitution of Si for Co in Pr2Co17 compounds. In Pr2Co17-x Mx, the Curie temperature decreases monoto nically with increasing at an approximate rate of 153K per Ga atom and 175K per Si atom. The saturation magnetic moment of Pr2Co17-x Mx ( M=Ga,Si) decreases with increasing x. The rates of the decrease are larger than that expected as a simple dilution. For Pr2Co17-xSix ,the spin reorientation transition is observed above room temperature. The spin-reorientation temperature Tsrfirst decreases with increasing Si content and then increases at higher x values (x>2). The spin reorientat ion behavior is interpreted by the competition between the Pr and Co sublattice anisotropies. The easy magnetization direction in Pr2Co17-xGax compounds is perpendicular to the c-axis, and no spin reorientation transition is observed. 相似文献
6.
The structural and magnetocaloric properties of Mn1.35Fe0.65P1-xSix compounds are investigated.The Sisubstituted compounds,Mn1.35Fe0.65P1-xSix with x = 0.52,0.54,0.55,0.56,and 0.57,are prepared by high-energy ball milling and the solid-state reaction.The X-ray diffraction shows that the compounds crystallize into the Fe 2 P-type hexagonal structure with space group P■2m.The magnetic measurements show that the Curie temperature of the compound increases from 253 K for x = 0.52 to 296 K for x = 0.56.The isothermal magnetic-entropy change of the Mn1.35Fe0.65P1-xSix compound decreases with the Si content increasing.The maximal value of the magnetic-entropy change is about 7.0 J/kg·K in the Mn1.35Fe0.65P0.48Si0.52 compound with a field change of 1.5 T.The compound quenched in water possesses a larger magnetic entropy change and a smaller thermal hysteresis than the non-quenched samples.The thermal hysteresis of the compound is less than 3.5 K.The maximum adiabatic temperature change is about 1.4 K in the Mn1.35Fe0.65P0.45Si0.55 compound with a field change of 1.48 T. 相似文献
7.
EFFECT OF MANGANESE SUBSTITUTION IN R2AlFe16-x Mnx(R=Y,Ho,Nd AND Pr)COMPOUNDS ON STRUCTURAL AND MAGNETIC PROPERTIES 下载免费PDF全文
The structural and magnetic properties of R2AlFe16-xMnx(0≤x≤8 for Y,Ho,0≤x≤10 for Pr, 0≤x≤16 for Nd)compounds have been investigated by means of X-ray diffraction and magnetization measurements.The R2AlFe16-xMnx compounds have a hexagonal Th2Ni17-type structure for R=Y and Ho, and a rhombohedral Th2Zn17-type structure for Nd and Pr.With increasing x,the unit-cell volumes have a small increase initially,followed by a greater linear increase.The Curie temperature and the saturation magnetizati on of these compounds show marvelous drop with increasing x.Compensation point was observed in the temperature dependence of the magnetization for Ho2AlFe12Mn4 compound. 相似文献
8.
Substituting Al for Fe in Pr(Al_xFe_(1-x))_(1.9) alloys:Effects on magnetic and magnetostrictive properties 下载免费PDF全文
The magnetostrictive effects of substituting Al for Fe in Pr(AlxFe1-x)1.9(x = 0.0, 0.02, 0.05, 0.10) alloys between5 K and 300 K were investigated. The substitution decreases the Curie temperature and the value of λ111. Fortunately, the substitution slightly increases the magnetostriction in a low magnetic field, which imbues these materials with potential advantages for applications. Rotation of the easy magnetization direction(EMD) from [111] to [100] in the Pr(Al0.02Fe0.98)1.9alloy as temperature decreases was detected by step scanned XRD reflections. 相似文献
9.
The resistivity and magnetization for the CuIr2(S1-xTex)4 (0≤x≤ 0.10) system are investigated. Compared with the Se doping, the substitution of Te for S leads to stronger suppression on the metal-insulator transition. Vacancies and imperfections in the sample lattice are found to modify the magnetization, which can be qualitatively understood to consist of the Pauli paramagnetism, Landau diamagnetism, Larmor diamagnetism and Curie magnetism contributions. 相似文献
10.
Effects of Cu on the martensitic transformation and magnetic properties of Mn_(50)Ni_(40)In_(10) alloy 下载免费PDF全文
The structures, the martensitic transformations, and the magnetic properties are studied systematically in Mn50Ni40-xCuxIn10, Mn50-xCuxNi40In10, and Mn50Ni40In10-xCux alloys. The partial substitution of Ni by Cu reduces the martensitic transformation temperature, but has little influence on the Curie temperature of austenite. Comparatively, the martensitic transformation temperature increases and the Curie temperature of austenite decreases with the partial replacement of Mn or In by Cu. The magnetization difference between the austenite phase and the martensite phase reaches 70 emu/g in Mn50Ni39Cu1In10; a field-induced martensite-to-austenite transition is observed in this alloy. 相似文献
11.
通过x射线衍射及磁测量手段研究了Y2(Fe1-y-x,Coy,C rx)17化合物的结 构及居里温度.研究结果表明Y2(Fe1-y-x,Coy,Crx)17化合物具有六 角相的Th2Ni17型结构.随着x的增加,Y2(Fe
关键词:
2(Fe1-y-x')" href="#">Y2(Fe1-y-x
y')" href="#">Coy
x)1 7化合物')" href="#">Crx)1 7化合物
x射线衍射
居里温度 相似文献
12.
The magnetic and dielectric properties of polycrystalline Cd1 - xFexCr2S4 (0 ≤ x ≤ 0.9) are investigated. Upon substitution of Cd by Fe, the Curie temperature (TC) is increased while the saturation magnetization is decreased. A low doping level of Fe increases the permittivity, while a high doping level decreases the permittivity, which is explained by the internal barrier layer capacitor model. Kinks are observed in the temperature-dependent permittivity and loss tangent near TC for the samples with x= 0.5, 0.7, 0.9, implying the existence of the magnetodielectric effect. Furthermore, with the increase of Fe content, a decrease of anomaly deviation rate induced by internal molecular field is revealed in the permittivity, while an increase is observed for the loss tangent. 相似文献
13.
采用基于第一性原理的密度泛函理论全势线性缀加平面波法,使用广义梯度近似处理交换相关势能,首先计算了β-FeSi2的电子结构及其各元素各亚层电子的能态密度,β-FeSi2的电子能态密度主要由Fe的d层电子和Si的p层电子的能态密度确定;其次通过计算不同掺杂系统的总能量确定了掺杂原子在β-FeSi2中的置换位置,在β-FeSi2中,Co置换FeⅡ位置的Fe原子,Al置换SiⅠ位置的Si原子,这种择位置换与现有的计算结果完全一致;最后计算了Fe1-xCoxSi2和Fe(Si1-xAlx)2的电子结构,对它们的电子结构特征进行了分析,并探讨了电子结构对其热电性能(塞贝克系数、电传输及热传输性能)的影响.
关键词:
第一性原理
电子结构
热电性能
2')" href="#">FeSi2 相似文献
14.
利用x射线衍射和磁测量研究了不同稳定元素Co以及Ti,V和Cr替代对Nd3Fe29-x-yCoxMy(M=Ti,V,Cr)化合物结构和磁性的影响.研究发现:每一个稳定元素都有一替代量极限,在此极限以内所有化合物均为Nd3(Fe,Ti)29型结构,A2/m空间群.不同稳定元素的溶解极限不同.Co的替代量与稳定元素有关,当以Cr作为稳定元素时,Cr的替代量随着Co含量的提高而提高
关键词:
3(Fe')" href="#">Nd3(Fe
Co
29')" href="#">M)29
结构
磁性 相似文献
15.
16.
通过X射线衍射及磁测量手段研究了Er2AlFe16-xMnx(x=1,2,3,4,6,8)化合物的结构和磁性. 研究结果表明Er2AlFe16-xMnx化合物具有六角相的Th2Ni17型结构. 采用X射线热膨胀测定法在103—654K的温度范围内测量了Er2AlFe16-xMnx(x=1,2,3,4)化合物的热膨胀性质,发现这些化合物在低温下存在热膨胀反常现象,在居里点附近具有负膨胀性质. 对自发磁致伸缩的研究结果表明Er2AlFe16-xMnx化合物中存在着较强的各向异性的自发磁致伸缩,低温下自旋重取向的出现使得化合物的自发体磁致伸缩有所增强. 磁测量结果表明Mn的替代导致Er2AlFe16-xMnx化合物的居里温度及自发磁化强度急剧下降,并且使得化合物的磁晶各向异性发生显著改变.
关键词:
2AlFe16-xMnx化合物')" href="#">Er2AlFe16-xMnx化合物
反常热膨胀
自发磁致伸缩 相似文献
17.
18.
19.
T.J.A. Popma A.M. van Diepen P.F. Bongers 《Journal of Physics and Chemistry of Solids》1974,35(2):201-205
The behaviour of the magnetization, Curie temperature, Mössbauer spectra, and lattice parameter is studied in the garnet series Bi0·8Ca2.χT2·2-2.χFe5-χVχ]O12. The shape of magnetization vs temperature curves shows only a minor dependence on x. The hyperfine field at the octahedral 57Fe nuclei at 5°K decreases linearly with x (12·5kOe per substituted V neighbour), while that at the tetrahedral 57Fe nuclei is not affected. The dependence of the Curie temperatures and hyperfine fields on x is discussed in relation to the Fe-O-V-O-Fe exchange. The influence of Bi substitution is consistent with the idea of a geometric effect. 相似文献