Nd(Fe_(1-x)Co_x)_(10)V_2的Mssbauer谱

通过X射线衍射、磁测量和M ssbauer谱等测试方法研究了Nd(Fe1-xCox) 10 V2 的结构和磁性。结果表明 :Nd(Fe1-xCox) 10 V2 (x =0 ,0 .0 5 ,0 .1,0 .15 ,0 .2 )化合物的晶体结构均为ThMn12 型结构 ;随着Co含量增大 ,晶格常数将单调减少 ,居里温度Tc 呈单调增大 ,饱和磁化强度Ms 逐渐增加。Co部分取代Nd(Fe1-xCox) 10 V2 中的Fe原子 ,将择优占据 8i铁晶位。     

Nd(Fe1-xCox)10V2的Mossbauer谱

通过X射线衍射、磁测量和Mossbauer谱等测试方法研究了Nd(Fe1-xCox)10V2的结构和磁性.结果表明:Nd(Fe1-xCox)10V2(x=0,0.05,0.1,0.15,0.2)化合物的晶体结构均为ThMn12型结构;随着Co含量增大,晶格常数将单调减少,居里温度Tc呈单调增大,饱和磁化强度Ms逐渐增加.Co部分取代Nd(Fe1-xCox)10V2中的Fe原子,将择优占据8i铁晶位.     

Si原子择优占位对R2Co17化合物中Co次晶格磁晶各向异性的影响

对R2Co17-xSix（R＝Ce,Gd和Y）化合物的X射线衍射和磁性测量研究结果表明,Si原子的加入使R2Co17化合物的室温磁晶各向异性由易面转变为易轴,各向异性常数随Si原子浓度的增加而出现极大值、重点讨论了Si原子在Co次晶格四个不同晶位择优占位与Co次晶格磁晶各向异性演化的关系,其中18h晶位对Co次晶格各向异性负贡献起重要作用     

IN SITU TEM OBSERVATION OF AMORPHOUS Nd_χFe_(1-χ) THIN FILMS AND THEIR CRYSTALLIZATION

用X射线衍射和透射电镜研究了用闪蒸法(Flash evaporation)在77K制备的Nd_xFe_(1-x)(X=0.06-0.90)非晶薄膜的室温稳定性及其晶化过程 当0.19相似文献   

金属间化物Nd(Fe_(1-x)Co_x)_(10)V_2的磁性能机制

通过X射线衍射.磁测量和M(?)ssbauer谱测定了Nd（Fe1-Cox）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原子的替代将导致化合物各个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.将择优占据8i铁晶位.取向样品NdFe10V2的热磁曲线和变温M(?)ssbauer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.     

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     

NdxFe1—x非晶膜及其晶化过程的TEM原位观察

用X射线衍射和透射电镜研究了用闪蒸法(Flash evaporation)在77K制备的Nd_xFe_(1-x)(X=0.06-0.90)非晶薄膜的室温稳定性及其晶化过程当0.19相似文献   

快淬Fe3B／Nd2Fe14B永磁材料晶化行为及磁性能的研究

利用熔体快淬和晶化处理的方法制备了快淬Fe3B／Nd2Fe14B永磁材料。采用XRD，DTA，VSM等方法对合金的晶化行为和磁性能进行研究。结果表明：对于Fe3B／Nd2Fe14B熔体快淬永磁粉末，升温速率对各相的析出和分解温度有一定的影响。完全过淬的Nd4.5Fe77B18.5和Nd4Fe77Cr0.5B18.5合金熔体快淬粉在进行973K，7min晶化处理过程中，首先形成Nd2Fe23B3相，然后Nd2Fe23B3相发生分解，其产物为Fe3B／Nd2Fe14B，此后再没有发生其它的相转变。当晶化温度大于953K，保温10min后，样品的剩磁、矫顽力和最大磁能积明显提高。微量元素Cr的添加对相转变温度有影响，同时可以细化晶粒，提高矫顽力，从而改善材料的永磁性能。     

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。     

Y2（Fe.095Al0.05）14B的中子衍射研究

用中子衍射对永磁合金Y_2(Fe_(0.95)Al_(005))_(14)B进行了测量。结果表明:其仍为Nd_2Fe_(14)B型四角结构,空间群为P42/mnm;Al进入晶体结构之中并择优占据4c及8j_2晶位。对Al的择优占位与磁性的关系进行了初步的讨论。     

STRUCTURAL REFINEMENT FOR Nd_2(Fe_(0.9)Si_(0.1))_(14) B FROM NEUTRON DIFFRACTION MEASUREMENT

Neutron diffraction measurements on Nd2(Fe0,Si0 ,)14B at room temperature and 77 K were performed. Data analysis using profile refinement was carried out. The results show that at room temperature Si atoms occupy preferentially 4c, 8j, and I6k2 sites, and the magnetic moments of bath Nd and Fe are parallel to C—axis. At 77 K, the site occupations remain unchanged as in room temperature, while the calculated Nd magnetic moment direction has an angular deviation of 37.8 ° from C—axis.     

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.     

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。     

Irradiation-induced amorphized state of rapidly quenched R 12Fe82B6 alloys (R = Nd, Er)

Rapidly quenched (RQ) alloys R ₁₂Fe₈₂B₆ (R = Nd, Er) have been prepared by melt spinning. Their magnetic properties, structure, and phase composition have been studied before and after fast-neutron irradiation to a fluence of 1.2 × 10²⁰ n/cm². Before irradiation, it is the Nd₂Fe₁₄B-type phase (space group P4₂/mnm) that is mainly present in the RQ alloys at 295 K. In the Nd₁₂Fe₈₂B₆ alloy, this phase has a ferro-magnetic structure with magnetic moments at the Nd and Fe atoms oriented parallel to the c axis; the Er₂Fe₁₄B phase found in the Er₁₂Fe₈₂B₆ alloy is characterized by a ferrimagnetic order of Er and Fe magnetic moments parallel to the basal plane. After irradiation, the crystalline state of both RQ alloys transforms into an amorphous state. The ferro- and ferrimagnetic orders are retained in them, but the Curie temperature of the alloys with Nd and Er decreases by 100 and 200 K, respectively. The spontaneous magnetization of the irradiated alloys at 5 K is approximately equal to their magnetization in the crystalline state, whereas their coercive force is lower than that for the alloys before irradiation by two orders of magnitude. The effects observed are explained by the dispersion of Fe-Fe exchange interactions resulting from the dispersion of interatomic spacings in the amorphous alloys.     

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.     

PHASE COMPONENT AND CURIE TEMPERATURE OF Nd_4(Fe_(1-x)Cr_x)_(77.5)B_(18.5)ALLOYS

1.IntroductionThenewhard-magneticNdFeBall0yswithlowNdc0ncentration(35at.%)havebeenobtainedbycrystallization0fam0rphous.ibbo.sI1-3].Theirmagneticpr0pertiesatr0omtemperatureareasfollows:coercivityHc=16O-24OkA/m,remanenceB,=1'2-1.25T,andmagneticenergy(BH).ax=64108kJ/m'.ThevaluesofB.and(BH).axaremuchhigherthanth0se0fthewidelyusedanis0tropic(Ba,Sr)Fe12Ol9ferritesandAlNiC0alloys.Inpreyi0uspapers['-'1,wehavereportedthestructuralandmagneticpr0perties.Recentlywestudiedtheinfluenceofthesubstit…     

Nd60Fe30M10（M=Al，Si，Ga）系非晶永磁的性能与组织结构

采用真空快淬设备以辊速5m／s、10m／s、15m／s、20m／s、30m／s制备了Nd60Fe30M10（M=Al,Si,Ga）系的“非晶带”,研究了制备速度对“非晶带”永磁性能和结构的影响。实验结果表明：Nd60Fe30Si10和Nd60Fe30Ga10同经典合金Nd40Fe30Al10一样,也显示出非晶永磁性能,并且比相同条件下制备的Nd60Fe30Al10“非晶带”的永磁性能更好;三种“非晶带”的矫顽力随辊速的降低而提高。对Nd60Fe30Al10“非晶带”的TEM分析表明,以30m／s辊速制备的“非晶带”,有2～5nm的析出物弥散分布在非晶基体上;而以5m／s辊速制备的“非晶带”,有10nm左右和150-200nm的析出物分布在非晶基体上。析出物的生成,促进了矫顽力的提高。     

磁一级相变La(Fe,Si)13基化合物的研究进展

对NaZn13型La(Fe,Si)13化合物在磁性、相变特性及磁熵变规律和制备方法等方面的研究进展进行总结和论述.低Si含量的La(Fe,Si)13化合物具有良好的软磁特性,表现出特殊的磁相变特征:在居里温度处的热诱导一级磁性转变和高于居里温度时的磁场诱导巡游电子变磁性转变,并伴随着巨大的磁熵变和磁致伸缩.随Si含量增高,化合物的这种特殊磁相变特征逐渐减弱,呈现二级相变特征.总结了元素替代和添加对La(Fe,Si)13化合物性能的影响,一定的合金化可以改变居里温度并保持巨大的磁熵变,这对于近室温磁致冷有着重要意义.快速凝固技术的应用解决了化合物合成困难的问题,降低了材料的制造成本,使得NaZn13型La(Fe,Si)13化合物成为最有应用前景的近室温磁致冷工质之一.本文还探讨了这种化合物用做磁致伸缩材料的可能性.