MAGNETIC PROPERTIES OF R 3(Fe, Mo) 29 N x (R=Sm OR Y) INTERSTITIAL NITRIDES

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＲ３（Ｆｅ,Ｍ）２９（Ｒ＝ｒａｒｅｅａｒｔｈ;Ｍ＝Ｔｉ,Ｖ,Ｍｎ,Ｍｏ,ｅｔｃ）ｃｏｍｐｏｕｎｄｓａｒｅｎｅｗｌｙｄｉｓｃｏｖｅｒｅｄｒａｒｅｅａｒｔｈｉｒｏｎｉｎｔｅｒｍｅｔａｌｉｃｓ．Ｔｈｅｙａｌｍｏｓｔｅｘｉｓｔ...     

STRUCTURAL AND MAGNETIC PROPERTIES OF Ho_2AlFe_(16x) Mn_xCOMPOUNDS

Ｉｎｐｒｅｖｉｏｕｓｗｏｒｋ〔１〕,ｗｅｒｅｐｏｒｔｅｄｔｈａｔｔｈｅｒｈｏｍｂｏｈｅｄｒａｌｏｒｈｅｘａｇｏｎａｌ２：１７ｐｈａｓｅｓｔｒｕｃｔｕｒｅｃａｎｂｅｓｔａｂｉｌｉｚｅｄｂｙｒｅｐｌａｃｉｎｇＦｅｗｉｔｈＡｌ．ＴｈｅｓｉｎｇｌｅｐｈａｓｅｃｏｍｐｏｕｎｄｓｏｆＲ２ＡｌＦｅ１６ｘＭｎｘ（Ｒ＝ｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔ）ｆｒｏｍｗｉｔｈＭｎｃｏｎｃｅｎｔｒａｔｉｏｎｕｐｔｏｘ＝８ｆｏｒＴｈ２Ｎｉ１７ｐｈａｓｅａｎｄｘ＝１６ｆｏｒＴｈ２Ｚｎ１７ｐｈａｓｅ．Ｉｎｔｈｉｓｗｏｒ…     

钇对超微晶软磁合金结构和磁性能的影响

本文研究了添加少量稀土元素Ｙ对超微晶软磁合金磁性能的影响，利用Ｘ射线衍射和Ｍｏｓｓｂａｕｅｒ谱分析了合金的相结构和各相中Ｆｅ原子的局域环境。结果表明，０．５％的Ｙ对合金的软磁性能有很大的改善，少量的Ｙ可固溶于α－Ｆｅ中，随Ｙ和添加量的增加，Ｙ可能析出，并对晶化有强烈的抑制作用。     

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     

纳米稀土金属Gd的磁性及分形特征

采用惰性气体保护蒸发凝聚技术制备出粒径为４～１５ｎｍ的稀土金属Ｇｄ微粉（ｎｍＧｄ）。经振动样品磁强计测试，表明ｎｍＧｄ微粉在某一特征粒径ｄｃ时磁化率χ取得最小值。利用小角Ｘ射线散射方法分析了ｎｍＧｄ微粉的三维生长分形特征，表明ｎｍＧｄ微粒聚集体系呈质量分形，制备气压越小则分维系数Ｄｆ越小。微粒生长模型是扩散限制聚集（ＤＬＡ）与扩散限制团聚聚集（ＤＬＣＡ）模型共存，相应这两个模型阶段的分维系数Ｄｆ存在一特征粒径ｄｆ。根据纳米微粒理论对ｎｍＧｄ微粉体系的量子尺寸效应的特征尺寸ｄｑ进行了估算，并就三种特征粒径ｄｃ、ｄｆ和ｄｑ进行了分析和比较     

MAGNETIC PROPERTIES AND COLOSSAL MAGNETO RESISTANCE OF La 1-x Sr x Mn 0.88 Fe 0.12 O 3

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＡＢＯ３ｏｘｉｄｅｓｗｉｔｈｐｅｒｏｖｓｋｉｔｅｂａｓｅｄｓｔｒｕｃｔｕｒｅｏｆＭｎｓｅｒｉｅｓｗｈｉｃｈｈａｖｅＣＭＲｅｆｅｃｔｓｈａｖｅｂｅｎｔｈｅｓｕｂｊｅｃｔｓｏｆｉｎｔｅｎｓｉｖｅｒｅｓｅａｒｃｈｅｆｆｏｒ...     

PREPARATION OF NANOCOMPOSITE BINARY GADOLINIUM ALLOYS AND THEIR ENHANCED MAGNETIC ENTROPY CHANGE

ＰＲＥＰＡＲＡＴＩＯＮＯＦＮＡＮＯＣＯＭＰＯＳＩＴＥＢＩＮＡＲＹＧＡＤＯＬＩＮＩＵＭＡＬＬＯＹＳＡＮＤＴＨＥＩＲＥＮＨＡＮＣＥＤＭＡＧＮＥＴＩＣＥＮＴＲＯＰＹＣＨＡＮＧＥ￥ＺｈａｎｇＪｉｅｌｉ；ＳｈａｏＹｕａｎｚｈｉ（Ｄｅｐａｒｔｍｅｎｔｏｆｐｈｙｓ...     

稀土元素对NiAl/CrMo(Hf)共晶合金氧化性能影响

研究了稀土元素Ce、Nd对NiAl-28Cr-5．5Mo—0．5Hf合金高温氧化性能的影响。并通过扫描电镜和能谱分析研究了氧化产物的微观组织与成分．结果表明：稀土的加入改变了表层氧化膜中各氧化物的含量。适量稀土元素的加入可消除内氧化和减小氧化增重．     

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。     

Influence of Sn substitution for Co in RCo2 （R = Gd, Tb, Dy） alloys on the structure and magnetocaloric effect

The phases and the magnetocaloric effect in the alloys R(Co1-xSnx)2 with x=0, 0.025, 0.050, 0.075, and 0.100 were investigated by X-ray diffraction analysis and magnetization measurement. The substitution of Sn in RCo2 is limited. The cubic MgCu2-type structure for the alloys of RCo2 was confirmed by X-ray powder diffraction and the remaining alloys mainly consisted of the RCo2 phase, along with some RCo3 and R5Sn3 impurity phases. The impurity phases increase with the increase of Sn content. The Tc of the alloys is not very sensitive to the Sn substitution for Dy(Co1-xSnx)2 and Tb(Co1-xSnx)2, whereas in Gd(Co1-xSnx)2, the Curie temperatures significantly increase. The maximum magnetic entropy changes in the alloys Dy(Co1-xSnx)2 (x=0,0.025, 0.050, 0.075) are 5.78, 5.43, 3.88, and 2.98 J·kg-1·K-1, respectively, and those in the Tb(Co1-xSnx)2 (x =0,0.025) are 3.44, and 2.29 J·kg-1·K-1 respectively in the applied field change of 0-2.0 T.     

MAGNETIC PROPERTIES OF Nd_2(Fe_(1-x)M_x)_(14)B(M=C,Si)ALLOYS

The magnetic properties of Nd_2(Fe_(1-x)M_x)_(14)B(M=C and Si) compounds have been investi-gated.Substituting Fe by small amount of metalloid C and Si atoms,the compounds are intetragonal structure and have uniaxial anisotropy.The substitution of C for part of Fe de-creases the Curie temperature of the compounds and the intrinsic coercivity of bond samples atlow temperature.The replacement of Fe by Si makes the Curie temperature increase with amaximum at the vicinity of x=0.15.When the range of the content of Si is 0≤x≤0.10,thecoercivity distinctly increases at room temperature.from 62.7 kA/m at x=0 to138.7kA/m at x=0.06,where the residual magnetization has a maximum:in the mean timethe saturation magnetization decreases only by a small amount.     

THE SYNTHESIS AND MAGNETOSTRICTION OF P rx Ce 1 x Fe 2 COMPOUNDS

１．ＩｎｔｒｏｄｕｃｔｉｏｎＡｌａｒｇｅｍａｇｎｅｔｏｓｔｒｉｃｔｉｏｎｍｉｇｈｔｂｅｅｘｐｅｃｔｅｄｉｎＰｒＦｅ２ｂａｓｅｄｏｎｓｉｎｇｌｅｉｏｎｍｏｄｅｌｐｒｅｄｉｃｔｉｏｎ〔１〕ａｎｄｉｔｉｓａｐｏｔｅｎｔｉａｌｃａｎｄｉｄａｔｅｆｏｒｇｉａｎｔｍａｇｎｅｔｏｓｔｒｉｃｔｉｖｅｍａｔｅｒｉａｌｓ．Ｈｏｗｅｖｅｒ,ｔｈｅｐｒｅｖｉｏｕｓｒｅｓｅａｒｃｈｅｓｉｎｄｉｃａｔｅｄｔｈａｔｓｏｍｅｒａｒｅｅａｒｔｈｉｒｏｎＬａｖｅｓｐｈａｓｅｃｏｍｐｏｕｎｄｓＲＦｅ２（Ｒ＝Ｌａ,Ｐｒ,Ｎｄ,Ｅ…     

EFFECT OF CHROMIUM SUBSTITUTION ON STRUCTURAL AND MAGNETIC PROPERTIES OF R_2Fe_(17) COMPOUND

ＴｗｏｄｒａｗｂａｃｋｓｒｅｓｔｒｉｃｔｔｈｅａｐｐｌｉｃａｔｉｏｎｏｆｔｈｅＲ２Ｆｅ１７ｃｏｍｐｏｕｎｄｓａｓｐｅｒｍａｎｅｎｔｍａｇｎｅｔ：ｎｏｎｅｏｆｔｈｅｍｅｘｈｉｂｉｔｓａｎｅａｓｙｃａｘｉｓｍａｇｎｅｔｏｃｒｙｓｔａｌｌｉｎｅａｎｉｓｏｔｒｏｐｙａｔｒｏｏｍｔｅｍｐｅｒａｔｕｒｅａｎｄＣｕｒｉｅｔｅｍｐｅｒａｔｕｒｅＴｃｏｆｔｈｅｍｉｓｒｅｌａｔｉｖｅｌｙｌｏｗ．Ｉｎｒｅｃｅｎｔｙｅａｒｓ,ｖａｒｉｏｕｓｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓｂａｓｅｄｏｎＲ２Ｆｅ１７ｈａｖｅｂｅｅ…     

亚稳态化合物Ce_2Fe_(23)B_3的结构与磁性

研究了非晶态Ce_2Fe_(23)B_3合金的晶化以及亚稳态化合物Ce_2Fe_(23)B_3的结构与磁性XRD分析证实,Ce_2Fe_(23)B_3为bcc结构,晶格常数α=1.417nm由Ce_2Fe_(23)B_3的室温Mossbauer谱,确定不同Fe位Fe原子磁矩的大小依次为:μFe(48e_1)>μFe(48e_2)>μFe(48e_3)>μFe(16c)>μFe(24d),平均每个Fe原子和Ce原子的磁矩分别为1.94和0.85μB     

Sm(Co_(bal)Fe_xCu_(0.088)Zr_(0.025))_(7.5)(x=0-0.30)烧结永磁体的磁性及其高温特性

用粉末冶金工艺制备了Sm（CobalFexCu0.88Zr0.025）7.5（x=0-0.30）烧结磁体,对Fe含量x对磁体的磁性及其高温特性的影响进行了系统研究.随Fe含量的增加,最大磁能积（BH）max和剩磁Br逐渐增加,分别在x为0.21和0.27时达到了最大值205kJ/m3和1.055T,然后迅速下降.当x≥0.24时,磁体中开始有FeCo软磁性相析出,破坏了磁体的永磁特性.Fe含量对磁体高温稳定性有巨大的影响,在Fe含量x=0.21时,磁体内禀矫顽力温度系数β为-0.23％/K;当x=0.07时,β降至-0.14％/K（293-723K）.制备出有很好的高温稳定性的永磁材料Sm（CobalFe0.07Cu0.088Zr0.025)7.5,在723K时其磁性能为:Br=0.725T,bHc=517kA/m,iHc=764kA/m,（BH）max=95 kJ/m3,B-H退磁曲线保持为直线.     

微晶(nm)级Fe-Cu-Mo-Si-B合金软磁材料及其结构SCIEI

本文研究了nm级微晶软磁材料Fe-Cu-Mo-Si-B合金系在不同磁退火方式以及不同热处理温度下磁性能的变化。结果表明,最佳热处理为510℃,保温1h;以缓慢冷却性能最好,并利用透射电镜,X射线衍射及热磁曲线对最佳热处理状态下的样品进行了组织观察和结构确定。该材料由两相组成:一相是a-FeSi固溶体,尺寸在10—20nm之间;另一相为非晶态。     

Al70—xCu8Fe10Cr12Cex准晶合金的凝固形貌及组织

研究了Ｃｅ对ＡｌＣｕＦｅＣｒ准晶合金凝固特性的影响。结果表明加入Ｃｅ能提高ＡｌＣｕＦｅＣｒ合金的硬度，加入适量的Ｃｅ可细化晶粒；而且固液界面的生长方式随着Ｃｅ含量的增加而明显改变，使合金凝固形貌表现出由胞状晶向胞状枝晶再向树枝晶转变的规律     

Fe73.5Cu1.0Mo3.0Si13.5B9.0纳米软磁合金的结构与磁性

用X射线衍射及滋测量等方法研究了不同退火温度下Fe73.5Cu1.0Mo3.0Si13.5B9.0纳米软磁合金的结构与磁性,发现合金的显微组织结构与退火温度有关，退火温度为500-520℃时，合金具有最佳软磁性能，合金中如出现Fe-B化合物，软磁性能恶化.     

Fe_（73．5）Cu_（1．0）Mo_（3．0）Si_（13．5）B_（9．0

用Ｘ射线衍射及磁测量等方法研究了不同退火温度下Ｆｅ_（７３．５）Ｃｕ_（１．０）Ｍｏ_（３．０）Ｓｉ_（１３．５）Ｂ_（９．０）纳米软磁合金的结构与磁性．发现合金的显微组织结构与退火温度有关，退火温度为５００─５２０℃时，合金具有最佳软磁性能，合金中如出现Ｆｅ－Ｂ化合物，软磁性能恶化．     

Peculiarities of the R3(Fe,Si)29 phase formation in the Sm---Fe---Si system

The phase content of the Sm(Fe_1−xSi_x)_y alloys (0.05≤x≤0.15; 8.5≤y≤12) has been studied by X-ray diffraction using micromonocrystals. The compounds Sm₂(Fe,Si)₁₇, Sm(Fe,Si)₁₂ and a novel Sm₃(Fe,Si)₂₉ compound with a monoclinic unit cell are found. The lattice parameters of Sm₃(Fe,Si)₂₉ are: a=1.056 nm, b=0.850 nm, c=0.966 nm, β=96.8°. This compound forms as a result of a solid state transformation from the high-temperature Sm₂(Fe,Si)₁₇ phase. Diffuse effects observed in rocking photographs suggest transition structures arising from this transformation. The Curie temperatures of Sm₃(Fe,Si)₂₉ vary in the interval 496–521 K.