Gang JI
,
Shishen YAN
,
Yanxue CHEN
,
Qiang CAO
,
Wei XIA
,
Yihua LIU
,
Liangmo MEI
,
Ze ZHANG
,
null
材料科学技术（英文）
2×(FeNi/CoZnO)/ZnO/(CoZnO/Co) ×2 spin-injection devices were prepared by sputtering and photo-lithography. In the devices, two composite magnetic layers 2×(FeNi/CoZnO) and (CoZnO/Co) ×2 with different coercivities were used to fabricate the ZnO-based semiconductor spin valve. Since the CoZnO ferromagnetic semiconductor layers touched the ZnO space layer directly, the significant spin injection from CoZnO into ZnO was observed by measuring the magnetoresistance of the spin-injection devices. The magnetoresistance reduced linearly with increasing temperature, from 1.12% at 90 K to 0.35% at room temperature.
关键词:
Spin injection
,
磁电阻
,
铁磁性半导体
Baoxin HUANG
,
Yihua LIU
,
Ruzhen ZHANG
,
Chengjian WANG
,
Gang JI
,
Liangmo MEI
材料科学技术（英文）
The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied. With increasing the substituting amount of Gd, the phase transition temperature of metal-isolator for the samples decreases, the corresponding peak resistivity increases,the Curie temperature decreases monotonically. The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude. The effects of substituting Gd can be explained in terms of the lattice effects. An irreversible MR behaviour was observed in Gd-substituting compounds. This effect became marked when the substituting amount of Gd was greater than 7%. A maximum irreversible increment of MR ratio as large as 91% was obtained when Gd substituting amount was 11%.
关键词:
Manganese perovskites
,
null
,
null
,
null
Ruwei GAO
,
Yihua LIU
,
Shishen YAN Deheng ZHANG and Lin ZHANG(Dept. of Physics
,
Shandong University
,
Jinan 250100
,
China)
材料科学技术（英文）
Magnetism and its dependence on annealing temperature for r.f. sputtered Co/Cu multilayers have been investigated. It was found that the easy magnetization axes of the films are paralIel to the substrate and the magnetic properties of both as-sputtered and annealed multilayers are isotropic in the film plane. The coercive field Hc is 4.8 kA/m and the ratio of remanence-tosaturation magnetization Mi/M is about 0.73 for as-sputtered samples. Both Hc and Mr/Ms increase with increasing annealing temperatures, especially when annealing temperatures are higher than 400℃. These experimental results can be interpreted using the ferromagnetic exchange coupling and the pinning theory of the coercivity
关键词:
徐卫兵
,
戈明亮
,
何平笙
应用化学
doi:10.3969/j.issn.1000-0518.2001.09.011
用熔融插层法制备聚甲醛/蒙脱土纳米复合材料,用X射线衍射研究聚甲醛及复合材料的微观结构,表明复合材料是纳米复合材料.用DSC法研究其非等温结晶行为,对所得数据分别用Jeziorny法、Ozawa法和Liu法进行处理.结果表明,Jeziorny法和Liu法处理非等温结晶过程比较理想.聚甲醛及聚甲醛/有机蒙脱土纳米复合材料的结晶活化能分别为334.6和196.9 kJ/mol,说明有机蒙脱土的加入,降低了聚甲醛的结晶活化能,且t1/z缩短,起到了异相成核的作用.
关键词:
聚甲醛
,
蒙脱土
,
纳米复合材料
,
非等温结晶动力学
王平华
,
徐国永
应用化学
doi:10.3969/j.issn.1000-0518.2004.08.007
用熔融复合法制备聚丙烯/凹凸棒土纳米复合材料,用DSC法研究其非等温结晶行为,对所得的数据分别用Jeziorny法、Ozawa法和Liu法进行处理.结果表明,Jeziorny法和Liu法处理非等温结晶过程比较理想.聚丙烯及聚丙烯/凹凸棒土纳米复合材料的结晶活化能分别为194.1和162.8 kJ/mol,表明凹凸棒土的加入,降低了聚丙烯的结晶活化能,且t1/2缩短,起到了异相成核作用.
关键词:
聚丙烯
,
凹凸棒土
,
纳米复合材料
,
非等温结晶动力学
Scripta Materialia
A recent comment on a previously published paper addressed the invalid explanation of the off diagonal interdiflusion coefficients of the beta-Ni(Al,Cr) phase in the Ni-Cr-Al system according to the symmetric property of the thermodynamic matrix. In this paper, the experimental data presented by Hou et al. was reanalyzed and the interdiffusion coefficient matrix was estimated again. The results of the analysis have been discussed in terms of a brief reply to the comments of Liu and Liang. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
Diffusion;Intermetallic compound;Ni-Cr-Al
邓超
,
邵玮
,
李春忠
高分子材料科学与工程
采用元机纳米锑掺杂二氧化锡(ATO)和有机聚醚酯(PEE)协同提高聚时苯二甲酸乙二酯(PET)的抗静电性能,合成了聚对苯二甲酸乙二酯-聚醚酯/锑掺杂二氧化锡纳米复合材料(PET-PEE/ATO).使用Czawa方程和Liu-Mo方程研究了PET-PEE/ATO纳米复合材料的非等温结晶过程.Ozawa方程研究发现,在非等温结晶过程中,PET、PET-PEE、PET/ATO、PET-PEE/ATO的成核性能依次提高.Liu-Mo方程发现,ATO和PEE的加入分别促进了异相成核作用和加快了结晶生长,PET-PEE/ATO结晶成核性能最好,结晶速率最快.
关键词:
聚对苯二甲酸乙二酯
,
有机聚醚酯
,
无机纳米锑掺杂二氧化锡
,
纳米复合材料
,
非等温结晶动力学
王浩
,
刘国权
金属学报
doi:10.3321/j.issn:0412-1961.2008.07.001
以MacPherson-Srolovitz提出的三维个体晶粒长大拓扑依赖速率方程以及三维晶粒组织的晶粒尺寸-晶粒面数间的抛物线型统计关系为基础,导出了相应的描述三维准稳态晶粒尺寸分布的函数族.采用纯Fe实验数据以及顶点法、基元演化法.相场模型和Monte Carlo法进行了验证,结果表明,函数族中峰值左偏的函数适合三维准稳态晶粒尺寸分布的定量表述.将该函数与Liu等提出的2种三维准稳态晶粒尺寸分布函数进行的对比表明:此3种函数的解析表达形式有所不同,但其曲线图在一定条件下相互吻合.此外,MacPherson-Srolovitz三维拓扑依赖速率方程、Hillert三维速率方程及Yu-Liu三维速率方程尽管表达形式不同均能较好地反映三维正常晶粒长大的动力学规律.
关键词:
三维晶粒长大
,
准稳态晶粒尺寸分布
,
长大速率方程
,
计算机仿真
王浩
,
刘国权
,
秦湘阁
金属学报
采用Potts模型Monte Carlo方法对3种现存的三维个体晶粒长大速率拓扑依赖性
方程进行了仿真验证. 结果表明, Rivier速率方程认为晶粒
体积变化率dVf/dt与晶粒面数f成线性关系, 与仿真
结果明显不符, 不适用于描述三维晶粒长大过程的动力
学. 当晶粒面数f≥8时, Yu-Liu速率方程和
MacPherson-Srolovitz速率方程均与仿真结果很好吻合,
表明这两者均可以用来定量描述三维晶粒长大过程的动力学；当
f＜8时, 这两个方程均与仿真结果有显著差异.
关键词:
三维晶粒长大
,
topology-dependent grain growth rate equation
