金属间化合物Ho_2Co_(17-x)Si_x的各向异性机制研究

研究了非磁性原子 Si替代 Co对 Ho2 Co1 7金属间化合物结构和磁性的影响。 X射线衍射分析表明 ,所有 Ho2 Co1 7- x Six(x=0 .5 ,1.0 ,1.5 ,2 .0 ,2 .5 ,3.0 )化合物都为 Th2 Ni1 7型六角结构 ;化合物的晶格常数和单胞体积都随 Si含量的增加而呈线性下降。磁性测量表明 ,Ho2 Co1 7- x Six 化合物的饱和磁化强度随 Si含量的增加而呈线性下降。从热磁曲线测量观察到 ,Ho2 Co1 7- x Six 化合物在 x=0 .5时呈面各向异性 ,当 1.0≤ x≤ 3.0时出现由易面到易轴的自旋重取向 ,自旋重取向温度 Tsr随 Si原子含量的增加先下降 ,而后又上升 ,在 x=2 .5处出现最低点。     

金属间化合物Nd(Fe1-xCox)10V2的结构和磁性研究

通过 X射线衍射和磁测量等手段对金属间化合物 Nd(Fe1 - x Cox) 1 0 V2 的结构和磁性进行了研究。结果表明 ,金属间化合物 Nd(Fe1 - x Cox) 1 0 V2 (x=0 ,0 .0 5 ,0 .1,0 .15 ,0 .2 )的晶体结构均为 Th Mn1 2 型结构 ;随着 Co含量 x的增大 ,晶格常数 a、c和晶胞体积 V将单调减小 ,居里温度 Tc呈单调增大 ,饱和磁化强度 Ms逐渐增加。取向样品Nd Fe1 0 V2 的 X射线衍射和变温穆斯堡尔谱研究结果表明该化合物在 T=12 0 K条件下存在自旋重取向现象。     

金属间化合物Ho2Co17-xSix的各向异性机制研究

研究了非磁性原子Si替代Co对Ho2Co17金属间化合物结构和磁性的影响.X射线衍射分析表明,所有Ho2Co17-xSix(x=0.5,1.0,1.5,2.0,2.5,3.0)化合物都为Th2Ni17型六角结构;化合物的晶格常数和单胞体积都随Si含量的增加而呈线性下降.磁性测量表明,Ho2Co17-xSix化合物的饱和磁化强度随Si含量的增加而呈线性下降.从热磁曲线测量观察到,Ho2Co17-xSix化合物在x=0.5时呈面各向异性,当1.0≤x≤3.0时出现由易面到易轴的自旋重取向,自旋重取向温度Tsr随Si原子含量的增加先下降,而后又上升,在x=2.5处出现最低点.     

Nd2Co17-xTix的结构和磁特性

用电子探针(EPMA)和20T强脉冲磁场测试仪分析和测试了Nd2Co17-xTix的结构和磁特性。结果表明,在x=1时,经过1050℃×15h均匀化处理,Nd2Co17型化合物变成Nd(CoTi)12和Nd2(CoTi)7型化合物,而呈现出单轴各向异性。此时合金的饱和磁极化强度为0.7T,各向异性场为2281.3kA/m。     

Y2(Co,Si)17化合物的结构与磁晶各向异性

采用真空电弧熔炼法制备了 Y2 Co17- x Six化合物。用 X-射线衍射和磁性测量方法 ,研究了化合物的晶体结构和内禀磁性。实验结果表明 ,随 Si原子浓度增加 ,Y2 Co17- x Six化合物的居里温度和饱和磁化强度急剧下降。本文重点讨论了 Si原子在 Co次晶格的四个不同晶位择优占位与 Co次晶格磁晶各向异性从易面转变为易轴的演化关系 ,其中 1 8h晶位对 Co次晶格各向异性负贡献起重要作用。     

RE2(CoFe)17-xTix型合金的结构和磁性(RE=Nd,La)

用电子探针(EPMA)、 X射线衍射仪和20 T脉冲强磁场测试仪研究了RE2(CoFe)17-xTix(RE=Nd, La)的结构与磁性. 结果表明, Nd2Co17-xTix 经过1050 ℃×15 h均匀化处理, 在x=1时, Nd2Co17型化合物变成Nd(CoTi)12和Nd2(CoTi)7型化合物, 而呈现出单轴各向异性. 此时合金的饱和磁化强度为0.7 T, 各向异性场为2250.3 kA*m-1. 对La-Co-Fe-Ti 2∶17型合金的磁特性进行了研究. 随着铁含量的增加, 合金的饱和磁化强度明显增加, 但也明显地降低了各向异性场.     

氢对金属玻璃Fe39Ni39Si8B12Mn2磁性的影响

使用大角转动张力磁化法研究了金属玻璃Fe39Ni39Si8B12Mn2渗氢后时效过程中磁化曲线和饱和磁致伸缩系数的变化。结果表明:含氢的Fe39Ni39Si8B12Mn2金属玻璃饱和磁化强度下降,而各向异性常数增加,相应饱和磁伸系数λ_s减小。     

磁控溅射Co1-x-Ptx薄膜晶体的结构与磁性能

通过磁控溅射制备了一系列不同成分的Co-Pt二元合金薄膜,并利用振动样品磁强计(VSM)和X-射线衍射技术(XRD)研究了Pt含量对薄膜磁性能和晶体结构的影响.结果表明:Pt的摩尔分数在0~28.5%范围内,薄膜均为密排六方结构(HCP);Co-Pt薄膜的晶格常数(c,a)随Pt含量的增加呈线性增大趋势,但其c/a的值却先减小后增大;矫顽力则先增大后减小,在Pt的摩尔分数为20%时达到最大值(156.89 kA/m);饱和磁化强度随Pt含量的增加而单调减小.     

稀土-铁-碳化合物磁性的理论分析

利用两个次晶格的分子场理论分析了稀土-铁-碳化合物的磁性,计算了分子场系数nFF,nRF,nRR以及自旋交换系数AFF,ARF,ARR,并对所得结果进行了讨论。     

Anisotropy of rare-earth magnets

Rare-earth intermetallics such as Nd₂Fe₁₄B and Sm-Co are widely used as high-performance permanent magnets, because they combine high magnetocrystalline anisotropy with reasonable magnetization and Curie temperature. The anisotropy is a combined effect of spin-orbit coupling and electrostatic crystal-field interactions. The main contribution comes from the rare-earth 4f electrons, which are well-screened from the crystalline environment but exhibit a strong spin-orbit coupling. In this limit, the magnetocrystalline anisotropy has a very transparent physical interpretation, the anisotropy energy essentially being equal to the energy of Hund's-rules 4f ion in the crystal field. The corresponding expression for the lowest-order uniaxial anisotropy constant K₁ is used to discuss rare-earth substitutions, which have recently attracted renewed interest due to shifts in the rare-earth production and demand. Specific phenomena reviewed in this article are the enhancement of the anisotropy of Sm₂Fe₁₇ due to interstitial nitrogen, the use of Sm-Co magnets for high-temperature applications, and the comparison of rare-earth single-ion anisotropy with other single-ion and two-ion mechanisms.     

Magnetic Properties of NdMn_(6-x) Co_x Sn_6 Compounds

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Influence of Non—Magnetic Substitutional Atoms on Spontaneous Moment and Curie Temperature of Ce2Co17Compounds

The structure and magnetic properties of Ce2Co17-xMx(M=Ga,Al and Si)compounds for Mcomcentrations up to x=5 were studied by means of X-ray diffraction and magnetic measurements,The experimental results show that the Curie temperatures and Co spontaneous magnetization decrease significantly with increasing the addition of non-magnetic substitutional atoms,and that Si which has a minimum solid solubility ic Ce2Co17causes a largest reduction of Curie temperature,spontaneous magnetization and moment perCo atom compared with Ga and Al.     

Structure and Magnetic Properties of Y(Fe_(1-x) Co_x)_ (11.3) Nb_(0.7)

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Structural and Magnetic Properties of the New Type of Rare Earth-Iron-Nitrogen Intermetallic Compounds

We succeed in inserting a number of nitrogen atoms into the R_2Fe_(17)and RTiFe_(11)intermetalliccompounds.The nitrides retain original Th_2Zn_(17)(or Th_2Ni_(17_)and ThMn_(12)structures,but with an increase inthe unit cell volume.The interstitial nitrogen atoms are found to have an effect of increasing the Curie tempera-ture and saturation magnetization.Moreover,a distinct effect on the magnetocrystalline anisotropy is also ob-served in these nitride compounds.Especially,NdTiFe_(11)N_(0.5)and SmTiFe_(11)N_2 have excellent intrinsic magneticproperties favourable for permanent magnet applications.     

金属间化物（Sm_（1－x）Dy_x）_2Fe_（17）N_y中的各向异性机制探讨

本文主要通过变温穆斯堡尔谱等手段研究金属间化物（Ｓｍ（１－ｘ）Ｄｙｘ）２Ｆｅ（１７）Ｎｙ（ｘ＝０．４；２＜ｙ＜３）的自旋重取向现象，进而对其中的各向异性产生机制进行分析。由实验结果得出Ｄｙ次格子的单轴各向异性较强，导致在１５０Ｋ～１００Ｋ较低温度下出现自旋重取向现象。     

Magnetic Properties of the Nitrides of R_2Fe_(17)CN_x

The carbon and nitrogen atoms can be introduced into the R_2Fe_(17) structure by a proper heat treatment.The crystallographic and intrinsic magnetic properties of a series of R_2Fe_(17)CN_x,where R=Y,Sm,Gd,Tb,Dy,Er have been investigated by using X-ray diffraction technique and magnetic measurements.The interstitial car-bon and nitrogen atoms are found to have an effect of dilating unit cell volume,raising Curie temperature andsaturation magnetization,as well as enhancing uniaxial magnetocrystalline anisotropy.