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MAGNETIC PROPERTIES OF NEW SERIES R-Mo-Fe NITRIDES WITH THE ThMn12-TYPE STRUCTURE AT A LOWER Mo CONTENT 下载免费PDF全文
A systematic study has been made on formation condition, crystallographic structure and magnetic properties of RMo1.5Fe10.5Nx, where R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er. The interstitial nitrogen atom effects on Curie temperature, saturation magnetization and magneto-crystalline anisotropy have been investigated. Two important preliminary results have been obtained. (1) A single phase crystallized in the ThMn12-type structure was stabilized with a smaller content of molybdenum, thus, the compounds possess a higher Curie temperature and a larger spontaneous magnetization. (2) A complete system of compounds with 1:12 type structure containing the light rare earth cerium and praseodymium was synthesized, which will be favorable for developing new rare earth hard magnetic materials. 相似文献
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A systematic investigation of nitrides R3Fe29-xCrxN4(R=Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. The nitrogen concentration in the nitride R3Fe29-xCrxNy was determined to be y=4. Nitrogenation leads to a relative volume expansion of about 5.3%. The lattice constants and unit cell volume decrease with in creasing rare earth atomic number from Nd to Dy, reflecting the lanthanide contraction. In average, the increase of Curie temperature upon nitrogenation is about 200 K, compared with its parent compound. The nitrogenation also results in a remarkable improvement in the saturation magnetization and anisotropy fields for R3Fe29-xCrxN4 at 4.2 K and room temperature, comp ared with their parent compounds. A spin reorientation of Nd3Fe24.5 Cr4.5N4 occurs at around 368 K, which is 138 K higher than that of Nd3Fe24.5Cr4.5.Magnetohistory effects of R3Fe29-xCrxN4(R=Nd and Sm) are observed in a low field of 0.04 T. First order magneti zation process occurs in Sm3Fe24.0Cr5.0N4 in magnetic fields of around 3.0 T at 4.2 K. After nitrogenation the easy magnetization direction of Sm3Fe24.0Cr5.0 is changed from the easy cone structure to the uniaxial. The excellent intrinsic magnetic properties of Sm3Fe24.0Cr5.0N4 make this compound a hopeful candidate for new high performance permanent magnets. 相似文献
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对多晶Y3Fe3Fe5-xMnxO12(x=0.05和0.09),得到300K下的中子衍射曲线。发现当x=0.05时,Mn3+离子占据16a和24d位置的几率分别为0.72和0.28;当x=0.09时,Mn3+离子全部占据16a位置;还得到两种组分16a和24d位置各自的磁矩值。在外磁场(800—10KOe)下测量Y3Fe5-xMnxO12(x=0—0.11)的磁化曲线,温度范围是1.5—300K。得到饱和磁矩值;并利用趋近饱和定律确定1.5K下的磁晶各向异性常数k1值,发现|k1|值随含锰量增加而减小。
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The structure and magnetic properties of two series of LaCois-based alloys, LaCo13-xFex(0≤x≤6) and La1-xRx(Co, Fe)13 (x=0.1,0.2; R=Y, Ge, Pr, Nd Sm, Gd, Tb, Dy, Ho, Er, and Yb), are studied by X-ray diffraction and magnetic mea- surements. In the above-mentioned composotions, all the samples display a structure of NaZn13 type (space group: Fm3c). In LaCo13-xFex system, as the iron content increases, its Curie temperature decreases, while thc magnetic moment per 3d atom increases. This may be explained by a rigid band model. In the other alloy system, the Curie temperature goes through a maxium at R=Gd, and this reflects the influ- ence of R - T interaction. It is also observed that saturation magnetization varies with R and gets lower when R is a heavy rare earth element. The contribution of R is close to that of a free-ion moment. La0.9Pr0.1Co9Fe4 has the largest value 29μB/f.u. 相似文献
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The crystal and magnetic structures of Nd2Fe14Si3 at room temperature were refined by Rietveld analysis of neutron-powder-diffraction data. It was found that silicon atoms occupy preferentially both 18h and 18f of Th2Zn17-type structure with occupancies 0.36 and 0.14, respectively, The Fe-Fe bond-lengths computed with the refined crystallographic parameters have optimum values, as compared with those of Nd2Fe17 compounds, which can explain well why the Curie temperature rises strongly when the unit cell volume reduces with the substitution of silicon for iron in Nd2Fe17. 相似文献
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EFFECT OF THE SUBSTITUTION OF Ga ON THE STRUCTURE AND MAGNETIC PROPERTIES OF Dy2Fe17 COMPOUND 下载免费PDF全文
Dy2Fe17-xGax (x = 0,1,2,3,4, 5 and 6) compounds were prepared by arc melting. These compounds are of single phase, having a hexagonal Th2Ni17-type structure fox x=0 and rhombohedral Th2Zn17-type structure for x≥1. The substitution of Ga for Fe in the Dy2Fe17 leads to a linear increase of unit-cell volumes. The saturation magnetization Ms at 1.5K is found to decrease linearly with increasing Ga concentration, from 65emu/g for x= 0 to 5emu/g for x = 6; and the Fe magnetic moment μFe is almost independent of Ga concentration. The Curie temperature TC is found first to increase with increasing Ga content x, and goes through a maximum value of 559 K at about x = 3, then decreases. The sharp increase of TC at lower Ga content may result from the increase of unit cell volumes. Dy2Fe17-xGax compounds with x≤5 exhibit easy plane anisotropy at room temperature, and those with x = 6 possess easy-axis. 相似文献
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本文讨论了Ландау二级相变理论中的稳定性条件,阐明了Лифшиц提出的对称改变限制条件是不必要的,从而可以讨论过去认为无法讨论的镧系金属镝(Dy)等在Neél点的二级相变,解释了镧系金属镝等在Neél点以下螺旋磁结构的螺距与温度成线性关系。同时,利用空间羣表示论和热力势极小条件,建立了一个讨论磁结构的新方法,用这方法分析了镧系金属的磁结构,所得的结果与中子衍射实验相符合。 相似文献
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用熔融法合成了单相填充式skutterudite化合物CeyFexCo4 -xSb12 (x =0— 3 0 ,y =0— 0 74) .对Ce的填充范围 ,置换Fe原子对化合物的结构及热电传输特性的影响进行了研究 ,Ce的填充分数随Fe含量的增加而线性增加 ,当Fe含量大约为 3时 ,Ce的填充分数达到 0 74.晶格常量a随Fe含量的增加而增加 ,Ce的填充使晶格常量进一步增加 .当Ce填充分数达到饱和状态时 ,CeyFexCo4 -xSb12 化合物表现为 p型传导 ,霍尔系数RH 随Fe含量的增加而降低 ,空穴浓度 p和电导率σ随Fe含量的增加而增加 ,泽贝克系数α随Fe含量的增加而降低 .当Fe/Co比大约为 1 5 / 2 5时 ,CeyFexCo4 -xSb12 的晶格热导率 (κl)达到最小值 . 相似文献
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系统研究了在外加诱导磁场下制备的Bi-Mn 6%合金的结构和低温磁特性.结果表明,在外加诱导磁场下制备的Bi-Mn 6%合金呈现典型的双相结构和各向异性特征,MnBi相c轴沿外加诱导磁场方向定向排列.发现MnBi相的矫顽力随温度的升高而增大,而饱和磁化强度则随温度的升高而减小.MnBi相的自旋重定向温度TSR随测量磁场的增大逐渐向低温区移动,在高的外加测量磁场下这种自旋重定向特征消失,发现了TSR随外加诱导制备磁场的增大而逐渐向高温区移动.对磁场诱导制备织构化MnBi相和该类材料磁各向异性能的物理机制进行了分析和讨论. 相似文献
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用中子衍射方法研究了室温下KLiSO4的晶体结构,进一步确定了Li原子的位置,所得到的结果与近年采用X射线分析的结果在z/c上的差异小于1%。
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