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Fe-Co-Ni合金纳米线有序阵列的模板合成与磁性 总被引:10,自引:0,他引:10
以二次阳极氧化的氧化铝膜为模板,用电化学沉积的方法成功地合成了Fe-Co-Ni三组份有序纳米线阵列.扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察表明纳米线表面光滑、有序、高长径比;磁性测量表明,其矫顽力较同组份的膜材料有较大的提高.将样品在惰性气体氛围中不同温度下退火,随着退火温度增加,其纵向矫顽力有一个极值,而对应的横向矫顽力没有类似的变化,关于这一现象的机理,本文进行了初步的讨论. 图5参15 相似文献
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利用热蒸发法在N型硅片表面成功制备出大面积SiO2纳米线和SiO2纳米棒结构.采用X射线粉末衍射(XRD),扫描电子显微镜(SEM),X射线能量色散谱(EDX),拉曼光谱(RS)和光致发光(PL)对合成的产物进行了表征.结果表明,用此方法生长的SiO2纳米材料,其结构和形貌与生长参数关系密切,随着沉积温度降低纳米线长度变短,最后呈现出棒状结构.此外,还研究了SiO2纳米结构独特的光学性质.该研究对改善光电子半导体器件的性能应用具有重要意义. 相似文献
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以取代靛红,(E)-硝基异噁唑芳烯烃和苯基甘氨酸为原料,乙腈为溶剂,经1,3-偶极子3+2环加成反应合成了8个新型的异噁唑拼接吡咯螺环氧化吲哚化合物(3a~3h),产率41%~62%,d/r值为2∶1~10∶1,其结构经~1H NMR,~(13)C NMR和HR-ESI-MS表征。采用MTT法研究了3a~3h对人肺癌细胞(A549),人前列腺(PC-3)和人白血病细胞(K562)的体外抗肿瘤活性。结果表明:3a,3b和3c分别对K562,PC-3和A549具有较好的抑制活性,其对应的IC50为16.0μmol·L~(-1),21.2μmol·L~(-1)和24.4μmol·L~(-1),优于顺铂(26.1μmol·L~(-1),27.2μmol·L~(-1)和25.6μmol·L~(-1))。 相似文献
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Structural Evolution of D5h(1)-C90 under High Pressure:A Mediate Allotrope of Nanocarbon from Zero-Dimensional Fullerene to One-Dimensional Nanotube 下载免费PDF全文
The hybridization of fullerene and nanotube structures in newly isolated C90 with the D5 h symmetric group(D5 h(1)-C90) provides an ideal model as a mediating allotrope of nanocarbon from zero-dimensional(OD) fullerene to one-dimensional nanotube.Raman and infrared spectroscopy combined with classical molecular dynamics simulation were used to investigate the structural evolution of D5 h(1)-C90 at ambient and high pressure up to35... 相似文献
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与超声塑料焊接相比,超声金属焊接负载重且变化剧烈,容易导致换能器出现无阻性点状态或者频率误跟踪。现有的频率跟踪方法往往只能在换能器有阻性点的状态下正常工作,在出现误跟踪时也无法自动复位。针对上述问题,本文基于梅森等效电路,推导出一种能够同时适配于谐振频率与反谐振频率,能够自行判断是否误跟踪频率跟踪算法。当换能器处于无阻性点状态时,算法将自动把跟踪目标变为相位差最小点,实现全状态频率跟踪。算法利用三个不同频率及其发波时换能器的电压电流相位进行计算,以此算出理想的频率跟踪步长和方向。最后通过MATLAB对算法进行仿真,验证算法在目标频率发生非线性变化时频率跟踪的效果。结果表明,新算法能够实现误跟踪的自复位和全状态频率跟踪,同时能在启动后10ms以内完成频率跟踪,跟踪精度达0.1hz。 相似文献
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采用高温熔融淬火法成功的合成了Tm~(3+)/Yb~(3+)共掺杂的含有不同浓度Tm~(3+)的氟氧化物碲酸盐玻璃.测量了样品的吸收光谱,结果表明Yb~(3+)和Tm~(3+)成功掺入到玻璃基质中.在980nm激发下,样品在801nm(3H4→3H6)发射最强,在476nm(1G4→3H6)和651nm(1G4→3F4)发射较弱;分析了上转换发光强度与Tm~(3+)浓度依赖关系,确定了上转换发光的最佳掺杂浓度为0.1%Tm2O3;探讨Tm~(3+)的上转换发光机理和Tm~(3+)的浓度猝灭机理,结果表明在980nm激发下Tm~(3+)获得的能量主要来自于Yb~(3+)→Tm~(3+)的量传递,Tm~(3+)的浓度猝灭机理为Tm~(3+)-Tm~(3+)之间的交叉弛豫导致的无辐射能量传递,根据能量匹配的原则,给出可能的交叉弛豫通道.此外,在980nm激发以3F2,3和3H4作为热耦合能级研究分析了Tm~(3+)在氟氧化物碲酸盐玻璃中的温度传感性能,结果表明灵敏度随温度的升高而升高,说明Tm~(3+)掺杂的氟氧化物碲酸盐玻璃可以作为光纤传感材料,且在高温灵敏度更佳. 相似文献
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通过在氮中引入杂质离子,利用高压手段获得具有新奇结构的多氮化合物是目前被广泛应用的研究方法.钙氮材料在催化、光电方面有着广泛的应用.具有较低电离能的钙(Ca)元素很容易和氮原子形成离子键钙氮化物.高压为寻找新型钙氮化合物提供了全新的技术途径.因此,利用高压方法,通过改变配比的方式,寻找具有新奇特性的钙氮高压结构,是一项非常有意义的工作.本文利用基于密度泛函理论的结构搜索方法,在100 GPa条件下,通过预测得到了一个稳定的Ca5N4相.该结构内部氮原子之间以N-N共价单键键合,氮原子和钙原子之间是离子键相互作用,且钙氮之间的电荷转移量为1.26 e/N atom.能带结构计算表明P 21/c-Ca5N4是一个直接带隙为1.447 eV的半导体结构.最后,系统地给出了该结构的拉曼振动光谱,并指认了拉曼振动模式,为实验合成该结构提供了理论指导. 相似文献
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In this article, the influence of La substitution for Sr on structure and physi-cal properties of the 2201 phase is studied. First, the crystal microstructure of the Bi2.1Sr1.9-xLaxCuOy (0≤x≤1.0) is characterized by means of X-ray diffraction and electron diffraction analyses, it is discovered that in the La-doped 2201 system with increasing La content the 2201 phase undergoes tetragnoal-orthorhombic-monoclinic structural transition. With this phase transition, the modulation vector of the 2201 phase transforms from incommensurate to commensurate, and the period of the mod- ulation wave decreases. Secondly, the superconductivity of this system is analyzed systematically. The results of the resistivity measurement show that the appropriate amount of La doping can raise the superconducting transition temperature (Tc) of the 2201 phase, with x=0.2, Tc reaches as high as 25K. However the excessive doping of La (x≥0.3) leads the 2201 phase to transit from metal to insulator and the su-perconductivity disappears. The measurement of thermoelectric power (TEP) of this system shows that with increasing La content the TEP value also increases gradu-ally. But the interesting point is that the transition from positive to negative in TEP occurs for x=0.2 sample. In addition, the electronic structure and oxygen content of this system are also studied. Based on these, we analyze the relation between the microstructure, electronic structure of the La-doped 2201 phase and its superconduc-tivity, indicating that the type of element substitution with higher valence, together with the microstructural distortion induced by the substitution affects the electronic states of Cu 3d seriously, that is, changes the degree of coulomb correlation of Cu 3d electrons, thus resulting in the transition of the type of carrier of this system and the decrease of hole carrier concentration, as well as the corresponding variation of the superconductivity of La-doped 2201 phase. 相似文献