L.L. Liu
,
X.F. Bi
,
S.K. Gong
金属学报(英文版)
FeNi multilayer films were prepared by EB-PVD technique. A modified TG-DSCapparatus was used to measure their Curie temperatures, which were around 760°C,lower than that of pure Fe thin films. The easy magnetization axis was in-plane. Hightemperature annealing in vacuum decreased the coercivity sharply. The saturationmagnetization also changed with heat treatment. After annealing at the temperatureequal to the substrate temperature during deposition, the saturation magnetizationdecreased.
关键词:
multilayer film
,
null
,
null
,
null
,
null
刘金练
,
麦发任
,
吴显明
,
李雷勇
,
施雯
材料科学与工程学报
采用固相法合成LiMn2-xBixO4-yFy（x=0,0.03;y=0,0.05,0.1）,通过X-射线衍射、扫描电子显微镜、恒电流充放电及循环伏安等技术分析检测合成材料的结构、形貌及电化学性能。结果表明：合成的LiMn2-xBixO4-yFy均为尖晶石结构,无杂相,颗粒表面光滑,大小均匀。常温下以0.2C倍率循环30次,LiMn1.97Bi0.03O3.95F0.05容量保持率为90.88%,远高于未改性LiMn2O4的86.51%,常温及55℃下以1 C倍率循环100次,LiMn1.97Bi0.03O3.95F0.05容量保持率分别为91.81%和83.69%,高于未改性的78.65%和71.82%。Bi和F复合掺杂提高了材料的稳定性和循环性能,尤其是高温循环性能。
关键词:
锂离子电池
,
锰酸锂
,
掺杂
,
电化学性能
Superconductor Science & Technology
It is shown that the superconductivity in Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds can be modulated by internal (chemical) pressure. The internal pressure is induced by Gd substitution for Ce in CeFeAsO(0.84)F(0.16), which compresses the crystal lattice. The temperature dependences of resistivity and magnetization show that the superconducting-transition temperature T(c) is enhanced from 40 K for CeFeAsO(0.84)F(0.16) to 47.5 K for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16). The increase and subsequent decrease of Tc upon application of external pressure, as observed previously in LaFeAsO(0.89)F(0.11), is entirely confirmed by the modulation of Tc of the Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by internal pressure.
关键词:
layered quaternary compound;43 k;iron
Rui XIONG
材料科学技术（英文）
The electronic structure of the quasi-two-dimensional (2D) semiconducting molybdenum purple bronze Bi0.2MoO3 was presented by X-ray photoemission spectroscopy. The valence band of Bi0.2MoO3 is made up of Opπ non-bonding level, π and σ bonding bands. The peak at 1.5 eV and the shoulder at 0.5 eV in the forbidden band may be formed from the non-bonding dxy orbitals of some Mo atoms. The O1s core-level spectrum demonstrates the presence of two inequivalent bonds of oxygen ions in Bi0.2MoO3. Bi4f core-level spectrum shows two bonding characters of Bi atoms in bismuth molybdenum single crystal. Mo3d core-level spectrum confirms two kinds of valence states of Molybdenum (Mo+5 and Mo+6). Ar+ ion irradiation induces more significant distortion of MoO6 octahedra.
关键词:
Bi0.2MoO3 single crystal
,
null
,
null
Journal of Applied Physics
Structural parameters have a critical impact on superconductivity in iron-based oxypnictide superconductors. Structural evolution study was performed on Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by the analysis of the x-ray diffraction patterns with Rietveld refinement. Substitution of Gd for Ce generates internal pressure that compresses the crystal lattice. The contraction of the c axis is also indicated by the reduction of Ce/Gd-As and Ce/Gd-O/F distances, while there is a slight increase in the As-Fe-As block size, which is compensated by a large reduction in the Ce/Gd-O/F-Ce/Gd block with Gd substitution. The diagonal Fe-As-Fe angle for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16), with the highest T(c) among Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds, is 111.13 degrees. It is close to the ideal value of 109.47 degrees for the perfect FeAs tetrahedron, which is situated in the region of Fe-As-Fe bond angles where RFeAsO compounds tend to have the highest T(c). (C) 2011 American Institute of Physics. [doi:10.1063/1.3565408]
关键词:
layered quaternary compound;high-temperature superconductivity
张庆福
,
李臣
,
宋志国
,
李永进
,
邱建备
,
杨正文
无机材料学报
doi:10.15541/jim20160471
本工作研究了卤素离子含量对卤磷酸钙固溶体中Bi离子的价态和发光性能的影响.荧光分析表明,卤素磷酸钙中的Bi2+/Bi3+可以通过其F-/Cl-组分变化实现有效调控;当卤素离子全部为Cl-离子时,晶体中Bi2+全部消失.上述现象的主要原因在于,当卤素离子为F或者Cl时,晶体中与其邻近的Ca(2)位点可以被分裂为Ca(2)a或Ca(2)b两种不同的格位,而Ca(2)a位点则有利于实现Bi3+的自还原.上述研究结果可以为Bi离子在晶体中的价态调控提供指导.
关键词:
卤磷酸钙
,
Bi
,
发光性能
,
调控
Hongchao LIU
,
Changlin KUO (Shanghai Institute of Ceramics
,
Chinese Academy of Sciences
,
Shanghai 200050
,
China)
材料科学技术（英文）
In cooperation with figure-of-merits the Rietveld analysis can appraise both angular and intensity data of powder diffraction. In this work, X-ray diffraction pattern of Bi4(SiO4)3 was redetermined with intensity figure-of-merits, which qualify agreement between observed and calculated relative intensities. F30 is 158.90 (0.0059, 32), intensity figure of merit Rint is 8.7, I20(17), 8.0. The values of figure-of-merits show that the data of JCPDS cards are distorted. Both the experimental and calculated peak positions and heights are listed in detail.
关键词:
崔雅静
,
陈永亮
,
杨烨
,
王雅真
,
张勇
,
赵勇
低温物理学报
通过先制备一种纳米尺寸的GdF_3作为GdFeAsO_(1-x)F_x样品中F的反应原料,在相对较低的温度(1120℃)下成功制备出一系列GdFeAsO_(1-x)F_x(x=0,0.05,0.1,0.15,0.2,0.25)多晶样品.X射线衍射结果表明,超导样品属四方ZrCuSiAs-type结构,晶格参数随着掺F量的增加而减小.扫描电子显微镜测试结果表明,样品具有片层状晶体形貌特征.当掺F量x=0.1时,样品表现出超导电性,超导转变温度为22K,随着掺F量的增多,超导转变温度升高.和其他制备方法相比,这种制备方法更有利于F的掺入,而且可有效减少样品中杂质相的含量.
关键词:
铁基超导体
,
ZrCuSiAs结构
Acta Physica Sinica
In this work, La(0.1)Bi(0.9-x)Eu(x)FeO(3) compounds were prepared by solid-state reaction. The phase relation at room temperature was investigated by X-ray powder diffraction. A rhombohedral (R3c) phase exists for x <= 0.05; for 0.08 <= x <= 0.12 a pseudo-R3c phase is found; for x >= 0.15 it is an orthorhombic (Pbnm) phase, while the distortion of the Pbnm phase was observed for the composition range of 0.15 <= x <= 0.20. Magnetic measurements indicate that weak ferromagnetism exists in all the compounds, and for the compounds with x <= 0.20 the magnetic moment has the maximum value at x = 0.12. The composition dependence of dielectric constant was investigated at room temperature. The relationship between the structure and the physical properties was discussed.
关键词:
La(0.1)Bi(0.9-x)Eu(x)FeO(3);X-ray diffraction;magnetism;dielectric;constant;transition;ceramics;bifeo3
