Physical Review B
In a recent publication [S. Dong et al., Phys. Rev. Lett. 103, 127201 (2009)], two (related) mechanisms were proposed to understand the intrinsic exchange bias present in oxides heterostructures involving G-type antiferromagnetic perovskites. The first mechanism is driven by the Dzyaloshinskii-Moriya interaction, which is a spin-orbit coupling effect. The second is induced by the ferroelectric polarization, and it is only active in heterostructures involving multiferroics. Using the SrRuO(3)/SrMnO(3) superlattice as a model system, density-functional calculations are here performed to verify the two proposals. This proof-of-principle calculation provides convincing evidence that qualitatively supports both proposals.
关键词:
thin-films;weak ferromagnetism;superlattices;anisotropy;bifeo3;srruo3;model
Ximiao PAN
,
Zhanpeng JIN
材料科学技术（英文）
The phase equilibrium relations of the ternary Ni-Cr-Zr system at 900°C have been investigated by means of diffusion triple and electron probe microanalysis (EMPA) techniques. A series of tie lines and triangles have been determined, and the corresponding tentative isothermal section is presented based on the current information.
关键词:
Nickel
,
null
,
null
,
null
Journal of Alloys and Compounds
The subsolidus phase relations in the ZnO-MoO3-B2O3, ZnO-MoO3-WO3 and ZnO-WO3-B2O3 ternary systems have been investigated by the means of X-ray powder diffraction (XRD). There is no ternary compound in all the systems. There are five binary compounds and five tie lines in the ZnO-MoO3-B2O3 system. This system can be divided into six 3-phase regions. There are three binary compounds and three tie lines in the ZnO-MoO3-WO3 system. This system can be divided into four 3-phase regions. There are four binary compounds and four tie lines in the ZnO-WO3-B2O3 system. This system can be divided into five 3-phase regions. The possible component regions for ZnO single crystal flux growth were discussed. The phase diagram of Zn3B2O6-ZnWO4 pseudo-binary system has been constructed, and the result reveals this system is eutectic system. The eutectic temperature is 1007 degrees C and eutectic point component is 70 mol% Zn3B2O6. (c) 2007 Elsevier B.V. All rights reserved.
关键词:
ZnO-MoO3-B2O3;ZnO-MoO3-WO3;ZnO-WO3-B2O3;Zn3B2O6-ZnWO4;phase relation;zno single-crystals;zinc oxide;growth;moo3-wo3
Surface & Coatings Technology
In order to reduce the high brittleness of laser clad Fe-B coatings, the composite Fe-Ti-B coating was developed by laser cladding with a powder mixture of B4C and Fe-Ti alloy. The microstructure, hardness and cracking resistance of these coatings were investigated in this paper. The experimental work enables the following findings to be reached: (i) the needle-like TIE, whiskers could be synthesized in situ using the laser cladding method in the composite Fe-Ti-B coating. (ii) The size, shape and volume fractions of TiB2 whiskers in the composite coating are greatly dependent upon powder compositions (contents of B, Ti elements and the ratio of B/Ti elements) and the laser energy density used. The average ratio of width/length for the synthesized TiB2 whiskers increases with increasing laser energy density and ratio of B/Ti elements in this coating. (iii) Both the hardness and cracking resistance of the Fe-B laser clad coating could be improved by the formation of TIE, whiskers. (C) 2001 Elsevier Science B.V. All rights reserved.
关键词:
TiB2;laser cladding;coating;steel;microstructure;powders
Haihua LIU
金属学报(英文版)
doi:10.1016/S1006-7191(08)60120-9
A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-tie wall in Permalloy is used to measure the remnant magnetic field by tilting the specimen and adjusting the objective lens current. The remnant magnetic field is estimated to be about 17 Oe, in a direction opposite to that of the objective lens magnetic field. The remnant magnetic field can be compensated by adjusting the value of the objective lens current.
关键词:
Lorentz electron microscopy
,
Lorentz lens
,
remnant magnetic field
,
Permalloy
,
cross-tie walls
汤清虎
,
赵培真
,
张庆红
,
王野
催化学报
分别采用模板剂离子交换法(TIE法)、水热合成法(DHT法)及浸渍法合成了Co-MCM-41,此催化剂能够在无共还原剂存在条件下催化以氧气为氧化剂的烯烃环氧化反应. 另外考察了催化剂的结构特别是钴的存在状态与催化性能之间的关系,以期能够弄清催化环氧化反应中催化剂活性位的本质. X射线衍射及N2吸附-脱附等结果证实,当导入分子筛中的钴的量在2.2%以下时,所有的Co-MCM-41均具有规整排列的六方孔道结构. 漫反射光谱和H2程序升温还原等结果表明,通过TIE法合成的样品中钴主要以孤立态钴离子(single-site Co(Ⅱ))形式存在,而以DHT法合成的样品中钴主要以微晶态Co2SiO4形式存在,浸渍法合成的样品中则存在大量颗粒状氧化钴. 催化反应结果表明,当钴含量均接近1.0%时,采用 TIE法合成的样品的苯乙烯转化率为45%,而用DHT法和浸渍法合成的样品的苯乙烯转化率均低于30%. 考虑到氧化钴和Co2SiO4的低活性以及DHT法和浸渍法合成样品中可能存在一小部分孤立态钴离子,我们推测MCM-41中的孤立态钴离子是催化活化分子氧发生环氧化反应的高效活性位.
关键词:
钴
,
MCM-41分子筛
,
孤立态钴
,
硅酸钴离子
,
氧化钴
,
苯乙烯
,
氧气
,
环氧化
Journal of Alloys and Compounds
The subsolidus phase relations of the ternary system ZnO-V(2)O(5)-WO(3) was investigated by means of Xray diffraction (XRD) analysis. The phase relations had been constructed. Five binary compounds, five tie lines and six three-phase regions were determined in this system. The possible component regions for ZnO single crystal flux growth were discussed. The phase diagram of Zn(4)V(2)O(9)-ZnWO(4) pseudo-binary system from 740 degrees C to 1300 degrees C was also determined through XRD and differential thermal analysis (DTA) methods. DTA results indicated this system was a eutectic system, and the eutectic temperature was 880 degrees C and eutectic point component was 78 mol% Zn(4)V(2)O(9) and 22 mol% ZnWO(4). The compounds composed of 78 mol% Zn(4)V(2)O(9) and 22 mol% ZnWO(4) might be suitable flux for ZnO crystal growth. (C) 2008 Elsevier B.V. All rights reserved.
关键词:
ZnO-V(2)O(5)-WO(3) system;Zn(4)V(2)O(9)-ZnWO(4) pseudo-binary system;Crystal growth;ZnO semiconductor;Phase relation;single-crystals;v2o5-zno system;diagram;znv2o6
QIN Guiying YU Xuejie JIN Heng WANG Jingcheng Shanghai Iron and Steel Research Institute
,
Shanghai
,
China
金属学报(英文版)
The relationship between structure and hysteresis of phase transformation temperature in NiTi shape memory alloy has been investigated by means of TEM observation,positron an- nihilation and electrical resistivity measurement.The sequence of hysteresis for the alloy aged under different regimes was found to be:plate martensite>R-phase>tie-like martensite. The reversible displaeement of phase boundaries of these transformations is blocked by the co- herent stress field around Ti_(11)Ni_(14)phase particles.A linear relationship between S paramet- er of positron annihilation and maximum values of temperature hysteresis showed that the mismatch dislocation and elastic stress field established by Ti_(11)Ni_(14)phase precipitation are the main factor to determine the temperature hysteresis of phase transformation in NiTi shape memory alloy.
关键词:
shape memory alloy
,
null
,
null
,
null
SHAO Zhongbao
,
LIU Kuiren
,
MENG Bo
,
LI Ying
,
YANG Yuqing(Department of Chemistry
,
Northeastern University
,
Shenyang 110006
,
China) LIU Huakun
,
DOU Shixue(University of New South Wales
,
Kensington
,
Australia)
金属学报(英文版)
Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ternary CuO-PbO-Ag system,there is a eutectic reaction CuO+PbO+Ag=L at 750℃ and a composition of 12.04 mol.% Ag,16.35 mol.% CuO and 71.61 mol.% PbO.Two miscibility gaps near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in the ternary system.SEM and energy dispersive spectroscopy(EDS) confirm the presence of two liquid phases and the eutectic point.
关键词:
:phase equilibrium
,
null
,
null
,
null
,
null
