共查询到20条相似文献,搜索用时 31 毫秒
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Nd(Fe1—xCox)10V2的Moessbauer谱 总被引:349,自引:0,他引:349
通过X射线衍射,磁测量和Noessbauer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。 相似文献
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R3(Fe,Mo)29(R=Sm,Y)化合物及其氮化物的磁性 总被引:2,自引:0,他引:2
潘洪革 《稀有金属材料与工程》1999,28(1):18-21
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。 相似文献
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在2:17型稀土-铁-碳化物中,用Ga替代Fe,可稳定稀土碳化物的晶体结构。本文讨论了Sm2Fe17-xGaxCy(2≤x≤6,0≤y≤3.0)化合物的形成。结果与磁性,给出了单胞体积V,室温饱和磁化强度σs居里温度Tc和室温各向异性场Ha与Ca和C含量的关系,发现在低Ga和高C样品中,居里温度一般大于620K,室温各向异性场高于120KOe,快淬方法获得在室温轿顽力大于13KOe。 相似文献
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采用提拉法生长出了掺钕钨酸铋钠(分子式Nd:NaBi(WO4)2,简称Nd:NBW)和掺钕钨酸钇钠(分子式Nd:NaY(WO4)2,简称Nd:NYW)晶体。通过TG-DTA分析得到Nd:NBW的熔点为936.2℃,Nd:NYW的熔点为1209.07℃。由吸收光谱可以看出,Nd:NBW在802nm有较强的吸收峰,Nd:NYW在804nm,752nm,586nm附近有较强、较宽的吸收峰,二者均适合于LD泵浦;并计算了晶体中Nd^+3+的吸收截面积。通过比较Nd:NBW和Nd:NYW的红外光谱和拉曼光谱结果,认为二者结构基本相同,为四方晶系、白钨矿结构、141/a空间群。 相似文献
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随着稀土含量的增加,快淬薄带矫顽力提高,剩磁降低,当稀土总量为10at%和快淬速度为12 m/s时,快淬薄带的矫顽力可达955 kA/m.当稀土总量为9.5at%时,快淬薄带晶化后的磁性能几乎不受快淬速度的影响.Dy替代部分Nd,提高了快淬薄带的非晶形成能力和热稳定性;经过晶化处理后,快淬薄带的矫顽力明显提高,剩磁略有下降,居里温度提高.Pr替代部分Nd,也提高了快淬薄带的非晶形成能力和热稳定性:经过晶化处理后,快淬薄带的剩磁和矫顽力都有所增加. 相似文献
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以四方晶系Nd2Fe14B相为基的永磁体具有极好的磁性性能,Nd2Fe14C的组织结构与Nd2FeB相同,其性能也接近,只是Nd2Fe14C的晶体各向异性磁场大于Nd2Fe14B。制取矫顽磁力(Hc)1.2T的Nd2Fe14C在1150K下要退火504h,Pr2Fe14C需要几个月退火和冷却。为了制取高性能的磁性材料并缩短制取周期,德国德累斯顿固体与材料研究院运用熔体离心铸造——短时间退火工艺生产了磁矫顽力高的Nd2Fe14C永磁材料和模压磁体,并研究了镝和硼添加剂对其相变和磁性性能的影响。用电弧熔炼法将纯度99.9%的各元素制得Nd14Fe77C8,Nd13Dy2FeC8、Nd13Dy2F… 相似文献
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R3(Fe,M)29化合物中的Fe—Fe及R—Fe之间的交换作用 总被引:1,自引:1,他引:0
根据R3(Fe,M)29(R=稀土,M=V、Ti、Mo)化合物的居里温度的实验值,使用平均场近似的方法计算R3(Fe,M)29化合物中的R-Fe,Fe-Fe之间的交换耦合参数JRFe和JFeFe。结果表明:对于R相同而M不同时,当M=V时JFeFe最大,而M=Mo时JFeFe最小;但是,当M=Ti时JRFe最大,当M=Mo时JRFe最小。 相似文献
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LIUHanqiang WANGBiao HANGuangbing GAORuwei 《稀有金属(英文版)》2005,24(2):200-204
The influence of solidification rate on the microstructure of (Nd,Dy)12.8(Fe,Co)80.7B6.5 cast strips was reported in this paper. The strips prepared at different wheel speeds were analyzed by X-ray diffraction (XRD). The microstructure of the strips was investigated by backscattered scanning microscope (BSM). The XRD results show that the strips are mainly composed of the main phase (Tx) existing apparent alignment along [00L]. The thickness of TI columnar grains is larger when the solidification rate is lower and the over-small isotropic microcystalline appear on the cooling surface of the strips when the solidification rate is too high. The adequate wheel speed for obtaining the optimum microstructure of the strips is about V = 2.0 m/s. The strip prepared at V = 2.0 m/s possesses suitable thickness and the highest alignment degree of T1 columnar grains, unifomly distributed Nd-rich phase, and no existence of α-Fe phase. This kind of cast strip is an ideal starting material for preparing sintered magnets with high magnetic properties. 相似文献
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INTRODUCTIONThehighCurietemperatureandlowesttempera turecoefficientoftheSm2 Co17permanentmagnetsmakethembeidealcandidatesforhight 相似文献
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用熔体快淬 晶化处理的方法制备了不同Dy含量的Nd8-xDyxFe83 5Co2 Nb1Ga1B4 5(x =0 ,0 2 ,0 5 ,0 8,1 0 )纳米复合材料 ,用差动 (扫描 )分析 (DSC)、X 射线衍射 (XRD)、透射电镜 (TEM )等研究了样品的晶化过程及微结构 ,用振动样品磁强计 (VSM)测量了磁性能。实验结果表明 :硬磁性相的晶化温度随Dy含量的增加逐渐升高 ,在最佳热处理条件下 ,矫顽力随Dy含量的增加首先有较大的提高 ,在Dy含量x >0 8以后增加较缓慢。剩磁随Dy含量的增加逐渐下降 ,在Dy含量x >0 8以后下降更加显著 ,磁能积在x =0 5~ 0 8附近出现峰值。剩磁和矫顽力与Dy含量的非线性关系是由于软、硬磁性晶粒之间交换耦合作用的强弱导致的。 相似文献
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Thin films of Nd^3+/V^5+-cosubstituted bismuth titanate, (Bi3.sNd0.5)( Ti2.96V0.04)O12 (BNTV), were fabricated on the Pt(111)/Ti/SiO2/Si(100) substrates by a chemical solution deposition technique and annealed at different temperatures of 650, 700, 750 and 800 ℃. The surface morphology and ferroelectric properties of the samples were studied in detail. The result shows that the film annealed at 800 ℃ indicates excellent ferroelectricity with a remanent polarization of 2Pr=40.9 i.tC/cm^2, a coercive field (Ec) of 114 kV/cm at an applied electrical field of 375 kV/cm. The substitution of Ti-site ion by V^5+ ions could improve the upper limit of the optimal annealing temperature by decreasing the space charge density in BNT thin film. Additionally, the mechanism concerning the dependence of ferroelectric properties of BNTV thin films on the annealing temperature was discussed. 相似文献
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LI Zuoan SONG Qinggong Department of Physical Chemistry University of Science Technology Beijing Beijing China College of Science Civil Aviation University of China Tianjin China 《稀有金属(英文版)》2004,23(2):161-164
Based on cluster variation method (CVM) and natural iteration method (NIM), order-disorde phase transition inthe intercalation compounds M_(1/2)TiS_2 is simulated by computer. The favorble conditions, under which 3a_0~(1/2)×a_0 super-structure is formed, are given, and the results are in good agreement with the experiments and theoretical calculations. Therelationship between critical temperature and M-ion-vacancy interaction parameter is linear. 相似文献