用Ga取代部分Fe对R3（Fe,Mo）29结构及磁性的影响

详细研究了Ｇａ取代Ｒ３（Ｆｅ,Ｍｏ）２９（Ｒ＝Ｓｍ,Ｙ）（Ｇａ＜０．１５）中的部分Ｆｅ对其结构和内禀磁性的影响,包括不同的Ｇａ取代对Ｒ３（Ｆｅ,Ｍｏ）２９化合物的晶胞常数、居里温度、饱和磁化强度、磁晶各向异性的影响。结果表明：在Ｒ３（Ｆｅ,Ｍｏ,Ｇａ）２９化合物中,随着Ｇａ含量的增加,晶胞体积膨胀,居里温度升高,饱和磁化强度下降,Ｆｅ原子的平均磁矩降低,Ｓｍ３（Ｆｅ０．９６６－ｘＭｏ０．０３４Ｇａｘ）２９化合物的各向异性由平面向锥面结构转变,继续增加Ｇａ含量,有可能出现单轴各向异性。     

PREPARATION OF A SINGLE PHASE R 3(Fe, Mo) 29 (R=Ce, Nd, Sm, Gd, Tb, Dy AND Y)

１ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｒｅｃｅｎｔｙｅａｒｓ,ｒｅｓｅａｒｃｈｅｒｓｉｎｔｈｅｆｉｅｌｄｏｆｐｅｒｍａｎｅｎｔｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓｈａｖｅｐａｉｄｍｏｒｅａｔｔｅｎｔｉｏｎｔｏｔｈｅｎｅｗｔｙｐｅｏｆｒａｒｅｅａｒｔｈｉｒｏｎ...     

STRUCTURAL AND MAGNETIC PROPERTIES OF ( PrxSm1 - x ) Mn2Si2

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｅｒｎａｒｙｌａｙｅｒｅｄｉｎｔｅｒｍｅｔａｌｉｃｃｏｍｐｏｕｎｄｓＲＭｎ２Ｘ２（Ｒ＝ｒａｒｅｅａｒｔｈａｎｄＸ＝Ｓｉ,Ｇｅ）ｈａｖｅｂｅｃｏｍｅｏｆｒｅｎｅｗｅｄｉｎｔｅｒｅｓｔｒｅｃｅｎｔｌｙｂｅｃａｕｓｅｏｆｔｈｅｌ...     

Magnetocrystalline anisotropy and exchange interactions in the novel R3(Fe, V)29 compounds (R = Y, Nd, Sm)

A type of magnetocrystalline anisotropy and exchange interactions of the novel ternary R₃(Fe, V)₂₉ compounds (R = Y, Nd, Sm) have been investigated. The compounds are uniaxial ferromagnets with easy magnetization direction along the [ 0 1] axis of the monoclinic lattice at room temperature. The temperature variations of the magnetic moment and the first anisotropy constant for Y₃(Fe, V)₂₉ are presented. The first order magnetization process along the hard magnetization direction takes place for Sm₃(Fe, V)₂₉ at T < 120 K. A magnetic anomaly is detected in the temperature dependence of the a.c. susceptibility for Nd₃(Fe, V)₂₉ which can be related to a spin reorientation.     

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。     

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。     

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.     

EFFECTS OF Al CONTENT ON STRUCTURAL STABILITY AND MAGNETIC PROPERTIES OF Sm2 (Fe, Al) 17 COMPOUNDS

ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｗｅｌｋｎｏｗｎｔｈａｔＳｍ２Ｆｅ１７Ｎｙｃｏｍｐｏｕｎｄｓｈａｖｅｇｏｏｄｉｎｔｒｉｎｓｉｃｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓ［１］．ＢｅｃａｕｓｅｏｆｔｈｅｐｏｏｒｓｔａｂｉｌｉｔｙｏｆＳｍ２Ｆｅ１７Ｎｙａｔ...     

Magnetic anisotropy and magnetic properties of RTSi (R=Gd, Y; T=Mn, Fe) compounds

Magnetic properties of Gd_xY_1−xMnSi and GdMn_xFe_1−xSi compounds with CeFeSi-type structure have been studied by magnetization measurements in the temperature range 77–600 K in static magnetic fields up to 12 kOe. The measurements for some compounds have been carried out on single crystal samples. The easy magnetization direction of all single crystal samples was found to be the c axis. The value of the anisotropy constant K₁ for GdMnSi was estimated to be 2.0·10⁶ erg cm⁻³ at 77 K. The substitution in both rare earth and 3d sublattices leads to a sharp increase in magnetic anisotropy of these compounds. The concentration dependencies of magnetic ordering temperatures, effective magnetic moments and paramagnetic Curie temperatures have been determined. The obtained results can be explained by the modification of the band structure due to the change of interatomic distances and the filling of 3d band.     

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.     

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     

MAGNETIC PHASE TRANSITIONS AND MAGNETIC PROPERTIES OF Nd_3(Fe,Mo)_(29) COMPOUND AND ITS NITRIDE

ＭＡＧＮＥＴＩＣＰＨＡＳＥＴＲＡＮＳＩＴＩＯＮＳＡＮＤＭＡＧＮＥＴＩＣＰＲＯＰＥＲＴＩＥＳＯＦＮｄ３（Ｆｅ,Ｍｏ）２９ＣＯＭＰＯＵＮＤＡＮＤＩＴＳＮＩＴＲＩＤＥ①ＰａｎＨｏｎｇｇｅ,ＷａｎｇＸｉｎｈｕａ,ＣｈｅｎＹｕｎａｎｄＣｈｅｎＣｈａｎｇｐｉｎＤ...     

Phase diagram of R-Fe-Co pseudoternary system with R≤33.3%(mole fraction,R=Sm0.5Dy0.5)

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｗｏｓｕｃｃｅｓｓｆｕｌｆａｍｉｌｉｅｓｏｆｒａｒｅ ｅａｒｔｈｃｏｂａｌｔｐｅｒｍａｎｅｎｔｍａｇｎｅｔｓｐｒｏｄｕｃｅｄｃｏｍｍｅｒｃｉａｌｌｙａｒｅＳｍＣｏ5ａｎｄＳｍ2 Ｃｏ17.ＴｈｅＳｍＣｏ5ｍａｇｎｅｔｓｈａｖｅｂ     

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.     

Magnetic properties of novel compounds R3(Fe,Cr)29Xy (R=Nd, Sm and X=N, C)

The novel ternary rare-earth iron-rich interstitial compounds R₃(Fe,Cr)₂₉X_y (R=Nd, Sm and X=N, C) with the monoclinic Nd₃(Fe,Ti)₂₉ structure have been successfully synthesized. Introduction of the interstitial nitrogen and carbon atoms led to a relative volume expansion ΔV/V of about 6% and an enhancement of Curie temperatures T_c about 268 K for the nitride and about 139 K for the carbide, respectively. The Nd₃Fe_24.5Cr_4.5X_y compounds have a planar anisotropy at room temperature. A first-order magnetization process (FOMP) with critical field B_cr=4.4 T and 3.1 T at room temperature were observed for the Nd-nitride and carbide compounds, respectively. The Sm₃Fe₂₄Cr₅X_y compounds were found to have a large uniaxial anisotropy of about 18 T at 4.2 K and about 11 T at 293 K. A FOMP with B_cr=2.3 T was also observed in the Sm-nitride compounds at 4.2 K. Magnets with coercivity of μ_OjH_c0.8 T at 293 K has been successfully developed from the Sm₃Fe₂₄Cr₅X_y (X---N and C) phases.     

Nd3（Fe,Mo）29化合物及其氮化物的磁结构和内禀磁性

制备了具有Nd3（Fe,Ti）29型单斜结构的单相铁基金属间化合物Nd3（Fe,Mo）29及其氮化物,详细研究了：其在4．2K～300K之间的磁结构;磁晶各向异性;居里温度Tc,饱和磁化强度σs等内禀磁性。研究结果表明：Nd3（Fe,Mo）29金属间化合物氮化后仍保持母相结构,氮化后的晶胞体积,居里温度Tc和饱和磁化强度σs分别比氮化前提高了5．9％,70．9％,6．6％;N3d（Fe,Mo）29金属间化合物在230K左右存在自族重取向,温度低于230K时,其磁晶各向异性为锥面,温度高于230K时,其磁晶各向异性为易面;氮化后自族重取向消失。     

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.     

Mutual separation characteristics for binary oxides Y2O3-Ln2O3 （Ln= Sc, La, Nd, Sm） using stepwise selective chlorination-chemical vapor transport reaction mediated by vapor complexes KLnCl4

Mutual separation characteristics for binary oxide mixtures Y2 O3-Sc2 O3, Y2 O3-La2 O3, Y2 O3-Nd2 O3and Y2 O3-Sm2 O3 using a stepwise selective chlorination-chemical vapor transport(SC-CVT) reaction mediated by vapor complexes KLnCl4 were investigated. The total transported yields of the chlorides produced from the oxide mixtures are in the order of NdCl3 ＞SmCl3 ＞LaCl3 ＞YCl3 ＞ScCl3 , the main deposition temperature of the chlorides is in the order of ScCl3 ＜YCl3 ＜SmCl3 ＜NdCl3 ＜LaCl3, and the largest separation factor values are 1 100 for Y . Sc,14.88 for Y : La, 9.86 for Y . Nd and 16.45 for Y . Sm in the temperature range from 1 000 K to 1 120 K, while 157.7 for La : Y, 51.6 for Nd : Y and 12.4 for Sm : Y in the temperature range from 1 200 K to 1 300 K, respectively. The results were discussed on the difference of KScCl4, KYCl4 and KLnCl4 and the selective chlorination of binary oxides at 800 K. Furthermore, the separation characteristics of vapor rare earth complex KLnCl4 were studied compared with those of LnAlnCl3n 3.     

一维NiFe1.98RE0.02O4(RE=Pr, Nd, Sm)纳米丝的结构和磁性能

采用溶胶-凝胶法、静电纺丝技术和热处理技术相结合制备了一维NiFe_(1.98)RE_(0.02)O_4 (RE=Pr,Nd,Sm)纳米丝。利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和振动样品磁强计(VSM)对NiFe_(1.98)RE_(0.02)O_4 (RE=Pr,Nd,Sm)纳米丝的结构、形貌和磁性能进行表征。结果表明,NiFe_(1.98)RE_(0.02)O_4(RE=Pr,Nd,Sm)纳米丝表面光滑、直径均匀、连续,直径约60nm。掺杂Pr~(3+),Nd~(3+),Sm~(3+)均没有改变NiFe204的尖晶石结构,掺杂均降低了NiFe_2O_4的结晶度,晶粒尺寸D从44.8nm减小到33.8nm。NiFe_(1.98)RE~(0.02)O_4 (RE=Pr,Nd,Sm)纳米丝都表现出软磁特性。NiFe_(1.98)RE_(0.02)O_4 (RE=Pr,Nd,Sm)纳米丝的饱和磁化强度(Ms)分别为39.58,41.10,34.23 A·m~2/kg;矫顽力(H_c)分别为14119.2, 13678.4,15937.6 A/m;其中NiFe_(1.98)Nd_(0.02)O_4纳米丝的M_s (41.10 A·m~2/kg)最大,矫顽力H_c(13678.4A/m)最小,软磁性能最好。     

Magnetic structures of R2RhSi3 (R=Ho, Er) compounds

Powder X-ray and neutron diffraction and magnetic measurements have been performed on R₂RhSi₃ (R=Ho and Er) compounds at low temperatures. The compounds crystallize in a derivative of the hexagonal AlB₂-type structure. The crystal structure parameters have been refined on the basis of the X-ray and neutron diffraction patterns collected in the paramagnetic region. These compounds are antiferromagnets with Néel temperatures of 5.2 K for Ho₂RhSi₃ and 5 K for Er₂RhSi₃. Both compounds exhibit collinear magnetic structures, described by the propagation vector k=(1/2,0,0) for Ho₂RhSi₃ and k=(0,0,0) for Er₂RhSi₃. This magnetic order is stable in the temperature range between 1.5 K and the Néel temperature.