共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
A crystal and magnetic structure of manganites Pr0.7Ca0.3Mn1?y Fe y O3 (y = 0, 0.1) has been studied by means of powder neutron diffraction at pressures up to 4 GPa in the temperature range 15-300 K. Under high pressure, an appearance of A-type antiferromagnetic state in both systems was observed. Both compounds exhibit anisotropic compression of the lattice which leads to the apical compression of MnO6 octahedra along the crystallographic b-axis. The calculated from obtained structural data pressure dependence of the charge-carrier bandwidth is in a qualitative agreement with observed pressure behavior of insulator-metal transition temperature within the framework of the double-exchange model. 相似文献
3.
4.
Hong-Shuo Li J. M. Cadogan Jian-Min Xu S. X. Dou H. K. Liu 《Hyperfine Interactions》1994,94(1):1929-1935
A study of the Nd-Fe-Ti phases at the Fe-rich end of the phase diagram has been carried out using57Fe Mössbauer spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). In particular,57Fe Mössbauer spectroscopy has been used to characterize the phases present in these samples. In addition to the two well-known 217 and 112 phases, twonovel phases have been identified, with compositions denoted by3–29 and9–94, which are closely linked to the orthorhombic ScFe6Ga6-type and the hexagonal TbCu7-type structures, respectively. The possible crystal structures of these new phases will be discussed in terms of the dumbbell substitution sequence in the CaCu5 structure. 相似文献
5.
测定了不同材龄的LaNi4 .9Al0 .1氘化与去氘化动力学参数 ,评价了氚老化对LaNi4 .9Al0 .1动力学性能的影响。研究结果表明 ,氚老化不改变合金的氘化与去氘化的反应级数 ;反应速率随老化时间的增加而降低 ;活化能随老化时间的增加而增加 相似文献
6.
7.
《中国物理 B》2015,(5)
Ag-doped manganite powder samples, La0.7Sr0.1AgxMnO3-δ(x = 0.00, 0.025, 0.05, 0.075, and 0.10) were synthesized using the sol–gel method. X-ray diffraction patterns indicated that the samples had two phases with the R3c perovskite being the dominant phase and Mn3O4 being the second phase. X-ray energy dispersive spectra indicated that the ratio of Ag to La was very close to that of the nominal composition in the samples. The specific saturation magnetizations at 300 K increased from 32.0 A·m2/kg when x = 0.00 to 46.8 A·m2/kg when x = 0.10. The Curie temperature, T C, of the samples increased from 310 K when x = 0.00 to 328 K when x = 0.10. Because the atomic concentration ratios of La, Sr, and Mn in the five samples were all the same and only the Ag concentration changed, the variations of the specific saturation magnetizations at 300 K and the Curie temperatures suggested that the Ag cations have been doped into the A sites of the perovskite phase in the samples. 相似文献
8.
本文首次研究了Tm(0.1)Yb(10.9)氟氧化物玻璃在966nm半导体激光激发下的直接上转换敏化发光现象。测量发现存在很强的^1G4→^3H6的474nm三光子和较弱的^1D2→^3H6的362nm,^1D2→^3F4的452nm,^1G4→^3F4的650nm三光子以及^3F3→^3H6的681nm二光子上转换发光。并对他们的上转换机理做了简要的讨论分析。 相似文献
9.
10.
11.
The results of magnetic measurements and ferromagnetic resonance studies performed on U(Fe
x
Al1–x
)2 and U(Fe
y
Ni1–y
)2 compounds over a large temperature range are reported. The saturation magnetization decreases nearly linearly when substituting Fe by Al or Ni. In the composition range x<0.84 and y<0.81, the compounds are Pauli paramagnets, except in the region with y0.10. For UNi2 two types of magnetic behaviours are shown. This compound can be both a ferromagnet withT
c
=23.5 K and a Pauli paramagnet, depending on the crystal structure. Above the Curie temperatures, the reciprocal susceptibility for the compounds with x>0.84 and y>0.81 obeys a temperature dependence of the formX=X
o+C(T-)
–1. The effective iron moments decrease when substituting iron by nickel or aluminium. The ferromagnetic resonance measurements show that theg values are not composition-dependent. A linear variation of the mean iron magnetization with the exchange field is observed. Finally, the magnetic behaviour of iron in these compounds is analysed. 相似文献
12.
E. De Grave C. Dauwe A. Govaert J. De Sitter 《Applied Physics A: Materials Science & Processing》1977,12(2):131-136
Static magnetization measurements on the ferrimagnetic spinels Fe2(1?y)Mg1+y Ti y O4 withy=0.3, 0.4, 0.5, and 0.6 show that these compounds have no well-defined orderdisorder transition temperature and that their ferrimagnetism may not be described in terms of the Néel theory. From the Mössbauer spectra we conclude that a temperature dependent number of the ferric ions does not participate in the ferrimagnetism of those compounds with compositiony≧0.4. The explanation of the observed magnetic and Mössbauer properties is based on the assumption that each ferric ion must have at least two magnetic linkages of the type Fe A 3+ ?O2??Fe B 3+ in order to couple its magnetic moment to the neighbouring ones over the entire temperature interval between 0 K and the respective Néel temperature. 相似文献
13.
14.
《低温物理学报》2016,(2)
我们用光学浮区法生长了稀土正铁氧体Dy_(0.9)Sm_(0.1)FeO_3(DSFO)单晶,并通过劳厄衍射法确定了单晶样品的方向.对DSFO单晶的磁性研究表明:在DyFeO_3中掺杂10%的Sm后,体系的自旋重取向转变温度从51 K(DyFeO_3)降低到9 K,而且相变过程变成了由Γ_4到Γ_(42)再到Γ_1.在12—300 K区间DSFO处于Γ_4组态,沿c方向Fe离子磁晶格有一个净的磁矩和一个由它诱导的稀土离子的净磁矩.稀土磁矩和Fe磁矩之间本征地反平行耦合,但一个较小的磁场可以改变反平行耦合到平行耦合.在场冷降温模式下的磁化-温度曲线测试中,我们发现在不同的磁场下磁化曲线会在不同的位置发生跳变;这一现象由稀土磁矩和Fe磁矩之间的平行反平行转变导致,有望作为特定条件下的自旋开关而应用于自旋电子学器件中. 相似文献
15.
测量了 2H Nb0 .9Ta0 .1 Se2 单晶样品在不同电流下电压随磁场变化的曲线V(H) ,并从V(H)曲线得到V(I)数据 .使用标度关系V =α(I-Ic)β进行了拟合 ,得到了临界电流随磁场Ic(H)和微分电阻随磁场Rd 的变化关系 .在微分电阻随磁场变化的曲线中 ,电流较大时 ,靠近上临界磁场Hc2 附近出现一个强峰 ,而在低电流下 ,该峰消失 .同时在临界电流峰效应区的起始处出现一小峰 .实验结果表明掺Ta后 ,涡旋体系的动力学特性发生了显著的变化 . 相似文献
16.
Tm(0.1)Yb(10.9)氟氧化物玻璃陶瓷的直接上转换敏化发光 总被引:1,自引:0,他引:1
本文首次研究了掺杂Tm(0.1)Yb(10.9)氟氧化物玻璃陶次居966nm半导体激光激发下的直接上转换敏化发光现象。测量艰现存在很强的^1G4→^3H6的477nm的三光子和^3F4→^3H6的799.5nm双光子上转换荧光以及较弱的^1D2→^3H6的361nm,^1D2→^3H4的449.5nm,^1G4→^3F4的647.0nm和^3F3→^3H6的多个上转换发光。 相似文献
17.
Rostyslav M. Bilanych Ruslan M. Yevych Anton A. Kohutych Sergij I. Perechinskii Ivan M. Stoika Yulian M. Vysochanskii 《Central European Journal of Physics》2014,12(9):611-614
Elastic properties of (Pb y Sn1?y )2P2S6 solid solutions were studied using Brillouin scattering technique. Different scattering geometries were used for sound velocities determination that make it possible to find all components of the stiffness tensor. The concentration dependencies of volume compressibility, the Grüneisen parameter and Debye temperature were investigated. The results obtained were used to analyze chemical bonding with substitution of tin by lead at room temperature in the crystals under consideration. 相似文献
18.
19.
文中报道了 Bi_(1.9)Sb_(0.1)Sr_2Ca_2Cu_(2+x)O_y,系列的交流磁化率测量及 X 射线衍射结果,发现超导转变温度对于 Cu 的组份非常敏感,当 x=0.4时,样品在136.5K 出现抗磁性,其 X 射线衍射图中新相衍射峰较85K 超导相的峰更强,因此 Cu 的价态和配位数在形成高和 T_c 超导相中起着至关重要的作用. 相似文献
20.
基于伊辛模型的单自旋反转蒙特卡洛算法,考虑了粒子间的最近邻以及次近邻相互作用,研究了无序Fe0.5Mn0.1Al0.4合金的磁化强度和磁熵变.首先,强调了粒子间的次近邻相关作用对体系的磁性和热力学性质的影响,明确了次近邻相互作用系数,证实了低温合金阻挫的存在;其次,研究了在相变温度处(不同磁场下)磁化强度随外加磁场(温度)的变化情况以及磁性粒子对磁化强度的贡献,发现反铁磁性粒子Mn在低温区对Fe0.5Mn0.1Al0.4合金的相变起了主要作用,而高温区体系的相变是由铁磁性粒子Fe贡献的;最后,分析了体系在相变温度处磁熵变数值随外加磁场的变化情况以及磁熵变在不同的外磁场下随温度的变化情况,当外加磁场H=0.14(a.u.)时,Mn粒子在冻结温度处的平均磁化强度为零,体系处于最无序的状态,对应的磁熵变ΔS(0.1,0.14)达到了正向最大值,极值的位置对应于体系的相变温度. 相似文献