J.P. Xie
,
H.L. Yuan
,
A.Q. Wang
,
W.Y. Wang
,
Y.R. Zhao
金属学报(英文版)
The mathematic calculation on two-body wear of austenitic manganese steel has been
performed by means of the elastic contact theory, stress interferometer and SEM.
Stress distribution in contacted area was calculated and the mechanism on two-body
wear has been investigated through numerical quadrature. Results show that two-body
wear is mainly plowing wear, the cracks of abrasive dust originates from the region
between 0.2® and 0.5® (® is radius of contacted round). Driving force to make crack
extension along y axis is ¿yzmax and extension direction is 45± with horizon. Driving
forces to make crack extension along x axis is alternative ¾x and ¿yzmax, the direction
of crack extension is 37。 with horizon.
关键词:
mathematic calculation
,
null
YANG Jilian ZHANC Baisheng DINC Yongfan China Institute of Atomic Engergy
,
Beijing
,
ChinaYANG Yingchang ZHANG Xiaodong Peking University
,
Beijing
,
ChinaPAN Shuming General Research Institute for Non-Ferrous Metals
,
Beijing
,
China associate professor
,
P.O.Box 275
,
Branch No.30
,
Beijing 102413
,
China
金属学报(英文版)
The N occupying sites and magnetic structures in R_2Fe_(17)N_x(R=Y,Dy,Nd)are de- termined by neutron diffraction.The effects of the site occupation of N on magnetic properties are discussed primarily.
关键词:
neutron diffraction
,
null
,
null
,
null
,
null
,
null
杨继廉
,
张百生
,
丁永凡
,
杨应昌
,
张晓东
,
潘树明
金属学报
用中子衍射法测定了R_2Fe_(17)N_x(R=Y,Dy,Nd)中N的占位及磁结构,初步讨论了N的占位对磁性能的影响
关键词:
中子衍射
,
Curie temperature
,
permanent magnet
Journal of Applied Physics
Samples of R2Fe17C(y)N(x) (R = Y, Sm, Er, Tm) were prepared by arc melting appropriate amount of R, Fe, and C, vacuum annealing at 1373 K and finally annealing at 740 K in nitrogen for 10 h. The magnetic properties of these compounds were investigated by means of ac initial susceptibility, magnetization measurements, and x-ray diffraction. The thermal stability of the nitride phase was studied by differential scanning calorimetry. It was found that, when heated above 600 K, R2Fe17C(y)N(x) irreversibly decomposes N which is irrespective of the carbon concentration and rare-earth element. The Curie temperatures of R2Fe17C(y)N(x) are independent of the carbon concentration and are approximately 400 K higher than those of the corresponding pure R2Fe17 compounds. However, the Curie temperatures cannot be correlated to the composition x of the initial R2Fe17C(y)N(x) compounds at room temperature because some N was lost during the heating to T(c). In the Er and Tm compounds spin reorientation transitions were found, marking the change of the easy magnetization direction from the c axis to the basal plane with increasing temperature. The Tm compounds show an additional magnetic transition at low temperatures (below 40 K). A coexistence of the hexagonal and the rhombohedral structural modifications was found in Er2Fe17C(y)N(x) when y < 1.5, characterized by two different spin reorientation temperatures. The anisotropy fields of Sm2Fe17C(y)N(x) are higher than that of Sm2Fe17N(x). Indications of a magnetic phase transition were found also in Sm2Fe17C0.7N(x) and Sm2Fe17C0.9N(x).
关键词:
magnetocrystalline anisotropy;carbides;alloys
Journal of Applied Physics
The magnetic properties of R2Co14B1-xCx (x=0, 0.5 and R=Y, Sm) compounds have been studied by measuring the temperature dependence of the easy- and hard-magnetization curves on magnetically aligned samples between 1.5 and 300 K for Y2Co14(B,C) and at 4.2 K for Sm2Co14(B,C). The magnetic anisotropy of Y2Co14B increases due to the substitution of C for B, whereas the saturation magnetization decreases. Between 1.5 and 300 K, the anisotropy field of Y2Co14B0.5C0.5 increases about 2 T and the Co moment decreases about 0.05mu(B). The anisotropy field Of Sm2Co14B also increases upon C substitution and the saturation magnetization decreases slightly. The ac susceptibilities of both SM2Co14B and Sm2Co14B0.5C0.5 exhibit anomalies that may arise from a spin reorientation within the basal plane.
关键词:
nd2fe14b;exchange;nd2co14b;r2fe14b;field
Journal of Physics-Condensed Matter
In this study, the transport and magnetic properties of electron-doped perovskites R(x)Ca(1-x)MnO(3) (R = La, Y and Ce) were investigated. As the R ion content increases, the crystal structure, resistivity, magnetoresistance, magnetization and related characteristic temperature of these systems all vary systematically. The data show that the variations in the electrical transport properties are mainly dependent on carrier concentration, whereas the magnetic properties of these systems are also dependent on crystal structure. When the carrier concentration exceeds a certain level, charge ordering occurs, leading to the localized electronic state and peaks in the magnetization curves. The magnetic transition temperature T(N) can be well described by crystal structural parameters, suggesting that crystal structure and magnetic properties are strongly coupled to each other.
关键词:
rare-earth manganates;phase-separation;colossal magnetoresistance;manganites;oxides;bandwidth;physics;camno3;ln
郝延明
,
刘倩
,
周严
,
付维贵
,
赵淼
功能材料
根据德拜理论和格律乃森关系导出的R2Fe17(R=Y,Tm)化合物在顺磁态的晶胞参数(a,c,v)及由负膨胀测定法得到的R2Fe17(R=Y,Tm)化合物的晶胞参数的差别,计算了R2Fe17(R=Y,Tm)化合物的本征体磁致伸缩随温度的变化关系.计算结果表明R2Fe17(R=Y,Tm)化合物的本征磁致伸缩随着温度的增加而急剧减小.分析表明这种现象与磁化强度和交换耦合作用随温度的下降有关.本文还研究了重稀土原子磁性对R2Fe17化合物的本征磁致伸缩的影响,结果表明重稀土原子磁矩及R-T交换耦合作用使R2Fe17化合物的本征磁致伸缩增强,但增强的幅度比3d次晶格引起的本征磁致伸缩小一个数量级,亦即R2Fe17化合物的本征磁致伸缩主要来源于3d次晶格中的Fe-Fe交换作用.
关键词:
R2Fe17(R=Y
,
Tm)化合物
,
本征磁致伸缩
,
交换耦合作用
Solid State Communications
Samples with composition R2Fe14M3 (M = Ga and Si; R = Y, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm) have been prepared by are-melting. Crystal-structure studies have shown that the prepared samples are single phase with the rhombohedral Th2Zn17 and/or the hexagonal Th2Ni17 structure. Substitution of Ga for Fe in R2Fe17 leads to an increase of the unit-cell volume, whereas Si substitution reduces the unit-cell volume. The Curie temperatures of the R2Fe14Ga3 and R2Fe14Si3 compounds are much larger than those of the corresponding R2Fe17 compounds. The Fe moment decreases upon Ga or Si substitution. The compounds R2Fe14Ga3 and R2Fe14Si3 With R = Er and Tm exhibit a spin-reorientation transition at low temperature. (C) 1997 Elsevier Science Ltd.
关键词:
neutron-diffraction;solid-solutions;substitution;anisotropy;nd2fe17
肖瑗
,
王哲飞
,
龚志杰
,
王丽熙
,
张其土
功能材料
采用固相合成法制备了(Y0.99R0.01)2 Ti2O7(R=Pr、Tb、Ho、Er、Tm、Yb、Lu)陶瓷,研究了Pr、Tb、Ho、Er、Tm、Yb及Lu掺杂对Y2Ti2O7陶瓷物相组成、烧结性能和微波介电性能的影响.结果表明A位取代能改进其微波介电性能.烧结样品为单相的烧绿石结构,主晶相为Y2Ti2O7.当R=Er,1450℃烧结4h时,(Y0.99Er0.01)2Ti2O7陶瓷的微波介电性能最佳:εr=44.3,Q×f=12021GHz(5.371GHz),τf=+44×10-6/℃,优于Y2Ti2O7陶瓷的介电性能(εr=54,Q×f=6565 GHz,τf=-31×10-6/℃).
关键词:
无机非金属材料
,
微波介质陶瓷
,
Y2Ti2O7
,
烧绿石结构
,
掺杂
