TbMn6—xCoxSn6赝三元化合物的结构和磁性

本文研究了ＴｂＭｎ６－ｘＣｏｘＳｎ和赝三元化合物的结构和磁性，结果表明：用Ｃｏ部分取代ＴｂＭｎ６Ｓｎ６中的Ｍｎ不改变其晶体结构，但随Ｃｏ含量的增加晶格常数和单胞体积单调减小；居里温度随Ｃｏ含昨增大而降低；自旋重取向温度也随Ｃｏ含量增大而降低，但Ｃｏ含≥０．６时自旋重取向消失；     

金属间化物Nd(Fe1-xCox)10V2的磁性能机制

通过X射线衍射，磁测量和Moessbauer谱测定了Nd(Fe1-xCox)10V2的结构和磁性。结果表明：Nd(Fe1-xCox)10V2(x=0,0.05,0.10,0.15,0.20)化合物的晶体结构均为ThMn12型结构；随着Co含量x的增大，晶格常数将单调减少。Co原子的将导致化合物各个Fe晶位上的磁超精细场值Bhf逐渐增加。Co部分取代Nd(Fe1-xCox)10V2中的Fe原子时，将择优占扰8i铁晶位。取向样品NdFe10V2的热磁曲线和变温Moessbauer谱研究结果表明，该化合物在T＝120K条件下存在自旋重取向现象。     

化合物Gd1-xLaxMn2Ge2(x=0.06, 0.07)中场诱导的反铁磁→铁磁一级磁相变

在脉冲强磁场中测量了Gd1-xLaxMn2 Ge2 (x =0 .0 6 ,0 .0 7)化合物在不同温度下的磁化曲线。结果表明 ,当这些化合物处于反铁磁状态的温度范围内时 ,Mn次晶格中发生了场诱导的从反铁磁状态到铁磁状态的一级磁相变。随着温度的降低 ,相变临界磁场逐渐增大 ,达到最大值后 ,随着温度的进一步降低 ,临界磁场很快减小 ;随La含量的增加 ,相变临界磁场也很快减小。在交换相互作用的分子场模型基础上 ,考虑层面间Mn Mn交换作用随晶格常数a以及温度的变化 ,从理论上计算了这种场诱导的反铁磁→铁磁一级磁相变所对应的临界磁场 ,理论计算结果较好地描述了临界磁场随温度的变化规律。理论模型也较好地解释了在这些化合物中发生的从亚铁磁结构到反铁磁结构再到铁磁结构的一级自发磁相变     

Sm2Co17—xTix化合物的结构和磁性

利用X射线衍射和磁性测量研究了Sm2Co17-xTix化合物的结构和磁性，实验表明这些化合物都具有Th2Zn17型结构，Ti替代Co不改变化合物的晶体结构，但引起晶格膨胀，所有化合物在Curie温度以下都表现为单轴磁晶各向异性，随着Ti含量的增加，化合物的Curie温度和饱和磁化强度都单调降低，而磁晶各向异性场在Ti含量为1.0时出现一极大值。     

Sm_2Co_(17-x)Ti_x化合物的结构和磁性

利用 Ｘ射线衍射和磁性测量研究了 Ｓｍ２Ｃｏ１７－ｘＴｉｘ化合物的结构和磁性实验表明这些化合物都具有 Ｔｈ２Ｚｎ１７型 结构, Ｔｉ替代 Ｃｏ不改变化合物的晶体结构,但引起晶格膨胀所有化合物在 Ｃｕｒｉｅ温度以下都表现为单轴磁晶各向异性随 着 Ｔｉ含量的增加,化合物的 Ｃｕｒｉｅ温度和饱和磁化强度都单调降低,而磁晶各向异性场在 Ｔｉ含量为 １．０时出现一极大值     

R3（Fe,Mo）29（R=Sm,Y）化合物及其氮化物的磁性

合成了Ｒ３（Ｆｅ,Ｍｏ）２９（Ｒ＝Ｓｍ,Ｙ）化合物并在０．１ＭＰａ氮气条件下通过气相氮化法制备出其氮化物。Ｒ３（Ｆｅ,Ｍｏ）２９金属间化合物氮化后仍保持母相结构,但是晶胞体积发生膨胀,氮化处理同时导致化合物居里温度Ｔｃ和饱和磁化强度σｓ升高同时Ｓｍ３（Ｆｅ,Ｍｏ）２９化合物由平面各向异性变为单轴各向异性,但Ｙ３（Ｆｅ,Ｍｏ）２９Ｎｘ化合物的各向异性仍与母相相同,为面各向异性。     

Tb0.3Dy0.7(Fe1-xAlx)1.95合金的结构、磁致伸缩性能和自旋重取向研究

本文系统研究了室温下Tb0.3Dy0.7(Fe1-xAlx)1.95(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.35)合金中金属Al替代Fe对晶体结构、磁致伸缩、内禀磁致伸缩、各向异性和自旋重取向的影响.结果发现,x＜0.4时,Tb0.3Dy0.7(Fe1-xAlx)1.95完全保持MgCl2立方Laves相结构,晶格常数a随Al含量x的增加而增大.磁致伸缩测量发现,随着替代量x的增多磁致伸缩减小,x＞0.15时超磁致伸缩效应消失;x＜0.15时磁致伸缩在低场下(H≤40kA/m)有小幅增加,高场下迅速减小,而且易趋于饱和,说明添加少量Al有助于减小磁晶各向异性.内禀磁致伸缩λ111随[111]替代量x的增加大幅度降低.穆斯堡尔效应表明,Tb0.3Dy0.7(Fe1-xAlx)1.95合金的易磁化方向随成份和温度在{110}面逐渐偏离了立方晶体的主对称轴,即自旋重取向.室温下,当x=0.15时,Tb0.3Dy0.7(Fe1-xAlx)1.95合金中出现了少量非磁性相;x＞0.15时,合金完全呈顺磁性.     

相变扩散连接界面生成金属间化合物的数值模拟

在异种材料扩散连接的接头中,当界面上有脆性的金属间化合物产生时,接头往往表现出较差的力学性能。因此,从扩散连接的生产应用及扩散连接的理论研究出发,研究扩散连接接头的界面金属间化合物的生成规律,进而对其控制,是有着非常重要的现实意义的。扩散连接界面上金属间化合物的生成及成长机制是受扩散控制的反应扩散机制,而相变扩散连接中往往还伴随着相变,因此相变扩散连接的界面反应机制更为复杂。本文根据相变扩散连接的     

Mn2-xFexP0.51Si0.49化合物的比热容与相变

用差示扫描量热(DSC)法测定过渡金属化合物Mn2-xFexP0.51Si0.49(x=0.8,0.85,0.9,0.95,1.0)的比热容。结果表明,随着Fe含量的增加相变温度TC﹑相变热滞ΔThys增加。x=0.8,0.85,0.9,0.95,1.0对应的相变温度分别为280.1,311.2,316.5,323.6,347.0K,相变热滞分别为27.8,32.5,37.2,34,46.6K。由比热容确定了该系列化合物在相变点附近的最大熵变,其值分别为13.3,13.9,15.3,13.1,15.6J·(mol·K)-1。     

稀土—铁大磁致伸缩材料

由于稀土—铁大磁致伸缩材料具有室温下大磁致应变，优良低场磁性能及较大的机电耦合系数，因而越来越受到人们的重视，并应用到许多高科技领域。本文通过对稀土—铁大磁致伸缩材料的回顾，及其室温下大磁致应变的产生机制的分析，具体讨论了该材料的制备工艺及其材料性能改善途径，并概述了稀土—铁大磁致伸缩材料的生产状况和应用。     

Magnetocrystalline anisotropy and spin reorientation transition of DyMn6Sn6 compound

The spin-reorientation transition of intermetallic compound DyMn6Sn6 was investigated by applying the molecular field theory. The temperature dependence of easy magnetization direction of compound and the magnetic moment directions of Dy and Mn ions were theoretically calculated and they have good agreement with the experimental data. In the framework of single ion model, the temperature dependence of magnetocrystalline anisotropic constants K1R and K2R of Dy ion were also calculated. The results show that the fourth-order crystal field parameter, B 40, and the corresponding second-order magnetocrystalline anisotropic constant, K2R, of Dy ion must be taken into account in order to explain the spin-reorientation transition satisfactorily. The competition between K2R and K1R plays a key role in the spin-reorientation transition of DyMn6Sn6.     

Exchange interactions and magnetic properties of intermetallic compounds

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｉｎｔｅｒｍｅｔａｌｌｉｃｃｏｍｐｏｕｎｄｓＲＭｎ2 Ｇｅ2 ｃｒｙｓｔａｌｌｉｚｅｉｎｔｈｅｂｏｄｙ ｃｅｎｔｅｒｅｄ ｔｅｔｒａｇｏｎａｌＴｈＣｒ2 Ｓｉ2 ｔｙｐｅｓｔｒｕｃｔｕｒｅ(ｓｐａｃｅｇｒｏｕｐｉｓＩ4 /ｍｍｍ) ,ｗｈｉｃｈｉｓｃｏｎｓｉｓｔｅｄｏｆＲ ,ＧｅａｎｄＭｎｌａｙｅｒｓ ,ｓｔａｃｋｅｄｉｎｔｈｅｓｅｑｕｅｎｃｅＲ Ｇｅ Ｍｎ Ｇｅ Ｒ ａｌｏｎｇｔｈｅｃ ａｘｉｓ[1] .Ｆｒｏｍｔｈｅｍａｇｎｅｔｉｃｐｏｉｎｔｏｆｖｉｅｗ ,ＲＭｎ2 Ｇｅ2 ｃｏｍｐｏｕｎｄｓｈ…     

Structural and magnetic properties of (Sm_0.5Nd_0.5)_2(Fe_(1-x)Co_x)_(17)compounds

The structure, magnetization, and magnetocrystalline anisotropy were investigated using X-ray diffraction, vibrating sample magnetometer, and AC susceptibility-meter. It is found that the microstructure of (Sm0.5Nd0.5)2(Fe1-xCox)17 alloys is an (Sm,Nd)2(Fe,Co)17 phase with the rhombohedral Th2Zn17-type structure. The Curie temperature Tc increases with the Co concentration increasing, and the magnetization first increases as the Co content increases in (Sm0.5Nd0.5)2(Fe1-xCox)17 alloys and then decreases slowly. The easy magnetization direction (EMD) of (Sm0.5Nd0.5)2(Fe0.25Co0.75)17 is along the c-axis and a strong enhancement of the crystalline anisotropy energy constant K is produced by the addition of some Co atoms. The anisotropy energy constant reaches the maximum when x = 0.75 and then decreases slowly with the Co content further increasing. The (Sm0.5Nd0.5)2(Fe0.25Co0.75)17compound is an optical candidate for the new permanent magnet, which possesses a high magnetization, a high Curie temperature,     

2002∽2003年金属磁性功能材料新进展

本综述论文开始写于1995年，其后每年撰写。本年的介绍内容包含：(1)磁形状记忆智能材料；(2)高性能的Nd-Fe-B永磁材料；(3)Si钢片磁性的改进；(4)稀土过渡金属化合物的特殊磁性；(5)铁磁半导体的磁性。     

Electrical and magnetic properties of NdCuPb compound

Electrical and magnetic properties of NdCuPb compound were investigated by means of electrical resistivity, magnetization measurements in the temperature range 1.5–100 K. Low-field dc susceptibility goes through a maximum at T_N=13.2  K, indicating a paramagnetic to an antiferromagnetic transition and then follows a sharp peak at T=5.9  K. The susceptibility data exhibits a Curie–Weiss like behavior in the paramagnetic regime and the effective moment per neodium atom is found to be 3.62μ_B from the data at temperatures above 42 K. This value is exactly equal to that for Nd³⁺, while at lower temperatures, the data yields a little bit less than its free ion value. The ratio M/H versus temperature T curves for different values of the magnetic field split into multiple branches at about T=42  K due to crystalline field effects.In addition, electrical resistivity in a magnetic field up to 120 kOe was also measured in the same temperature range. The resistivity gives non-metallic behavior. The antiferromagnetic transition is clearly discern by a “Cr-like” anomaly at about 13 K, followed by a sharp increase in the resistivity (like a jump) at T=5.9  K where the susceptibility gives similar effect. On other hand, the magnetic contribution to the resistivity begins to decrease at T=42  K at which M/H curves merges. All these behavior may be attributed to crystal-field-splitting of neodium atoms’levels.     

均恒磁场对Cu与液态SnZn合金间化合物层结晶行为的影响(英文)

以Cu和SnZn合金的金属间化合物界面结晶为对象,研究均恒强磁场对界面化合物界面行为的影响,并通过扫描电镜、X射线衍射及电子探针分析磁场对界面金属间化合物组织、相结构及成分的影响规律。结果表明:与无磁场下的界面金属间化合物相比,0.1T磁感应强度降低了化合物层的生长,继续增加磁感应强度使得化合物层的生长加快。磁场改变了化合物层的晶体取向,但是对化合物的成分没有明显影响。这是因为磁场下热电磁对流和洛伦兹力对Cu溶解及液固界面前沿Cu溶质有富集的作用。     

High-temperature phase transition and magnetic property of LaFe11.6Si1.4 compound

The LaFe_11.6Si_1.4 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K(5 h) to 1623 K(2 h). The powder X-ray diffraction and metallographic microscopy show that 1423 K and 1523 K are two curial temperatures, at which large amount of 1:13 phase begins to form and the most amount of 1:13 phase is obtained, respectively. With annealing temperature increasing to 1573 K and 1623 K, a new phase of La₅Si₃ is detected in LaFe_11.6Si_1.4 compound. According to the DSC curve of as-cast LaFe_11.6Si_1.4 compound and the X-ray patterns of annealed LaFe_11.6Si_1.4 compounds, the high-temperature phase transition process is analyzed. For studying the influence of different high-temperature and short-time annealing on the Curie temperature, thermal and magnetic hysteresis, magnetocaloric effect of LaFe_11.6Si_1.4 compound annealed at different temperatures are also investigated.     

熔体快淬LaFe11．5Si1．5的巨大磁熵变

采用熔体快淬法制备了LaFe11．5Si1．5化合物。利用X射线衍射和能谱分析测定了熔体快淬带的相组成和元素分布：利用磁性能测试结果计算了磁熵变。结果表明：熔体快淬可以得到元素分布均匀的LaFe11．5Si1．5薄带，其相组成为NaZn13型LaFe11．5Si1．5化合物和大量α-Fe。退火后，快淬带中的α-Fe含量大大降低，得到了近似单相的LaFe11．5Si1．5化合物。由磁性能测试并经计算发现，快淬带经1000℃，6h时效后具有巨大的磁熵变。由此可见，熔体快淬可成为一种制备更廉价的高性能磁致制冷材料的新方法。     

Comparison of magnetic and transport properties of Gd6YPd3 and Gd7Pd3 single crystals

Electronic structure, transport and magnetic properties of the Gd₆YPd₃ single crystal have been measured. This compound crystallizes in the hexagonal Th₇Fe₃ type of structure with the ratio c/a = 0.63 similar to that obtained for Gd₇Pd₃. Gd₆YPd₃ orders ferromagnetically at 299 K while Gd₇Pd₃ displays also ferromagnetic transition but at about 334 K. All measured physical properties show a strong anisotropy. The thermal dependence of the electrical resistivity shows an anomalous character having a strong negative curvature and quadratic temperature dependences at low temperatures. The saturation magnetic moment per Gd ion is enhanced in relation to the theoretical value. Spin fluctuations taking place on the palladium atoms may be responsible for the magnetic properties of ternary compound.