Magnetic properties and XPS of Dy-Y and Dy-Nd alloys

The magnetic properties and X-ray photoelectron spectroscopy (XPS) spectra in the Dy100-xYx and Dy100-zNdz rare-earth alloys are studied.The magnetism measurements show that the dhcp crystal-field influence in the Dy-Nd alloys,which tends to destroy the orbital moment,does not vanish even though a field of 6T is applied.With increasing Y (or Nd) content the temperature region corresponding to helical phase becomes wider (or narrower).The XPS records suggest that the property of the valence fluctuation in neodymium tends to increase the Fermi wave vector kF of the Dy-Nd alloys.This testifies that the abrupt dropping of the Neel temperature,as Nd is introduced,is not only due to a dilution effect of Nd.The introduction of light rare earths into heavy ones is favorable for suppressing the helical phase in the alloys and overcoming the negative magnetocaloric effect.This result will play a guiding role in designing composite magnetic refrigeration working substances.     

RECo_5热膨胀反常研究

本文研究了RECo_5在居里温度附近热膨胀反常的特点。利用高温X射线衍射方法从室温到600℃测定了CeCo_5,Ce(Co_(0.6)Cu_(0.2))_5和Ce(Co_(0.9)Fe_(0.1))_5晶格常数α和c随温度的变化。在居里点附近,CeCo_5的晶格常数c随温度的变化存在明显的拐折,在磁有序区域内具有因瓦反常,而晶格常数α随温度基本保持连续线性的变化,没有反常效应.用Cu原子部分取代Co原子以后,Ce(Co_(0.3)Cu_(0.2))_5沿c轴的热膨胀反常显著减弱。利用中子衍射研究了RE(Co,Cu)_5结构的有序性,从中子衍射的谱线分析表明,在CaCu_5型结构的RE(Co,Cu)_5金属间化合物中,Cu原子优先占据2c位置,由此解释了RECo_5热膨胀反常的原因。     

廉价高性能稀土永磁材料

由美国Ovonic综合材料公司于今年宣布的一种新的水磁材料,其商业名称为Ni—Rem(这是从Hard Iron Rare Earth Magnet和High I otropy Remanence Enhanced Magnet缩写而成的),这种新的永磁材料的性能比目前大量生产的永磁性铁     

THERMAL EXPANSION ANOMALIES OF THE COMPOUNDS RECo_5

本文研究了RECo_5在居里温度附近热膨胀反常的特点。利用高温X射线衍射方法从室温到600℃测定了CeCo_5,Ce(Co_(0.6)Cu_(0.2))_5和Ce(Co_(0.9)Fe_(0.1))_5晶格常数α和c随温度的变化。在居里点附近,CeCo_5的晶格常数c随温度的变化存在明显的拐折,在磁有序区域内具有因瓦反常,而晶格常数α随温度基本保持连续线性的变化,没有反常效应.用Cu原子部分取代Co原子以后,Ce(Co_(0.3)Cu_(0.2))_5沿c轴的热膨胀反常显著减弱。利用中子衍射研究了RE(Co,Cu)_5结构的有序性,从中子衍射的谱线分析表明,在CaCu_5型结构的RE(Co,Cu)_5金属间化合物中,Cu原子优先占据2c位置,由此解释了RECo_5热膨胀反常的原因。     

A Study of the Magnetic Properties of Intermetallic Compound RFe_(12-x)M_x

The structure and intrinsic magnetic properties of RFeM(M=V or Ti),type 1:12,have been studied bymagnetic measurement and X-ray diffraction.They are body-centered tetragonal ThMn_(12)structure.Thechanges of crystal lattice constants coincide with that of their element radii.Curie temperature is decided mainlyby the exchange interactions of 3d-3d and 3d-4f atom pairs.The data obtained by mean-field approximationagree well with experimental values.The magnetic moment coupling in these compounds for LRE isferromagnetic,and for HRE is antiferromagnetic.At low temperature,anisotropy field is decided by REsublattice.In this paper,the influence of magnetic properties of cobalt and nickel replacing iron has also beenstudied.     

参加第四届希土永磁国际会议及在日本参观的概况

序言第四届希土永磁国际会议于1979年5月22日到24日在日本箱根举行。希土永磁会议是在1974年由希土永磁的权威、美国道顿(Dayton)大学教授K.Strnat创办的。以往的三届会议都是在美国召开的,本届会议是由日本未踏加工技术协会主办,日本金属学会,日本电气学会,日本应用物理学会,日本应用磁学学会协赞召开的。尽管会议的专     

Nd_2(Fe_(1-x)M_x)_(14)B(M=C,Si)合金的磁性

本文研究了Nd_2(Fe_(1-x)M_x)_(14)B的磁性。少量类金属原子C和Si取代部分Fe,能形成四方结构,且具有单轴各向异性。碳取代Fe,使化合物的Curie温度降低,低温下粘结体样品的内禀矫顽力减少;而Si对Fe的取代可使Curie温度升高,并在x=0.15附近达到极大值。含Si样品在0≤x≤0.10范围内,矫顽力显著增加,室温下从x=0的62.7kA/m增加到x=0.06的138.7 kA/m,并且在x=0.06附近,剩磁有一个极值,饱和磁化强度减少不多。