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991.
This paper reports the static and hyper-frequency magnetic properties, as well as their relationship with microstructure, of the ferromagnetic-ferroelectric co-fired composite ceramic, (1−x)Ba2Zn1.2Cu0.8Fe12O22-xPb(Ni1/3Nb2/3)0.8Ti0.2O3. The X-ray diffraction results did not detect any other phase in the co-fired ceramics, but found a crystal structural distortion of ferrite phase. Scanning electron microscopy photos showed that two phases’ grains matched well and stacked compactly and the hexagonal ferrite changed its grain morphology. The saturation magnetization increased with the reduction of magnetic phase in the range of 0<x<0.65 because of the stress-induced structural distortion. The permeability decreases monotonically with the reduction of magnetic phase in the whole composition range. 相似文献
992.
993.
多孔硅拉曼光谱随激发功率变化的研究 总被引:2,自引:0,他引:2
用阳极氧化法新制备了多孔硅样品,以457.5nm固体激光器为激发光源,在不同激发功率下,获得了拉曼谱图和一些谱峰参量随激光功率的变化关系。解释了520cm^-1和300cm^-1附近拉曼峰随功率变化的一系列可逆的实验现象:随激光功率升高出现的红移和非对称性展宽,主要是由于样品局域平均粒径变小而受量子限域效应的影响导致的;样品局域平均粒径在表面上的二维减小与随激光功率升高而导致的局域温升并不违背基本的热力学定律;高功率时520cm^-1附近双峰的出现是由于多孔硅样品局域平均粒径达到一定阈值而导致的纵模和横模双声子模的分裂。 相似文献
994.
探针尖带金属微粒的光子扫描隧道显微镜成像数值模拟 总被引:4,自引:1,他引:3
引入了色散介质的时域有限差分法散射场方程,并针对光子扫描隧道显微镜的带金属尖光纤扫描成像问题进行三维的数值模拟。在考虑了光纤和样品相互作用的情况下,采用等效入射波法设置入射波,探针扫描模式为等高扫描模式,从成像分辨力和灵敏度的角度,比较了不同入射角、不同的光纤一样品间距,不同金属类型,及不同金属尖大小的成像情况。数值模拟结果显示,带金属颗粒光纤探针尖的光子扫描隧道显微镜在成像分辨力和灵敏度上有显著的改进,而带不同类型金属颗粒情况下对分辨力影响不大,灵敏度是银最好。 相似文献
995.
996.
阐述了三螺旋DNA的发展和最新动态,并从3个方面展开评述:(1)三螺旋DNA稳定性的研究。三螺旋DNA的稳定性不仅取决于寡聚核苷酸的内在结构,还受外界环境如溶液的pH值、阳离子的种类和价态、DNA分子嵌入试剂和共聚物等的影响;(2)三螺旋DNA的应用。三螺旋DNA的形成为基因操纵和基因疗法提供了新方法,它在抑制DNA转录、复制、基因定点诱变、定点切割和诱导基因重组等方面有重要的应用前景;(3)三螺旋DNA的检测方法,包括紫外-可见吸收光谱法、荧光分析法、原子力显微术和顺磁共振谱等。 相似文献
997.
998.
A new type of SiO_2-MgO-CaO (SMC) whisker was used to modify high density polyethylene (HDPE).The melting behavior and crystallinity were investigated by differential scanning calorimetry (DSC).The dispersion of whiskers and interfacial adhesion in the prepared HDPE/SMC whisker composites were investigated by scanning electron microscopy (SEM).The mechanical properties were evaluated by mechanical tests and dynamic mechanical analysis (DMA).DSC data indicated that the melting temperature and the crystall... 相似文献
999.
Chengbin Jing Haiyang Shan Chuanjian Zhang Xiaodan Zang Wei Bai Junhao Chu 《Journal of Sol-Gel Science and Technology》2009,51(2):139-145
The solids content and gelation time of aqueous germanate solution were examined in this work. Samples of 5, 10 and 20 mol%
Mn doped Ge were prepared by using the aqueous germanate solution as a liquid Ge precursor. No second phase such as Mn5Ge3 was detected in the 5 and 10 mol% Mn doped samples, implying that Mn ions were uniformly diluted into the Ge host matrix.
The 5 and 10 mol% Mn-doped Ge samples exhibit room-temperature ferromagnetic behaviors that are likely originated from the
RKKY (Ruderman–Kittel–Kasuya–Yosida)-like interaction between the localized Mn ions in the Ge matrix. Therefore, the aqueous
germanate solution can be an alternative sol–gel precursor for preparation of the Mn
x
Ge1−x
diluted magnetic semiconductors (DMSs). 相似文献
1000.
Lingyun Chen Hang Xing Junfeng Bai Guoqing Jiang 《Journal of solid state chemistry》2009,182(6):1387-314
Novel MnO nano- and microparticles including spherical nanoparticles and various micropolyhedra of pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral particles, were controllably synthesized via solid-state thermolysis of inorganic core containing molecular clusters [Mn12O12(O2CR)16(H2O)4] (R=C6H5, CH3, and C6H5OCH2) in a conventional horizontal tube furnace. Among them, pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral MnO submicroscale particles were reported for the first time. The products were characterized by XRD, XPS, Raman spectrum, SEM, EDX, TEM and HRTEM. During the reaction process, thermolysis temperature, reaction time, and different molecular clusters {Mn12} precursors with different organic ligands as well play important roles in determining the sizes and shapes of the final products. The formed MnO nanospheres from [Mn12O12(O2CC6H5)16(H2O)4] at 400 °C for 10 h exhibited weak ferromagnetic behavior at low temperature which may be due to the size-effect of nanomaterials. Furthermore, the possible formation mechanism was also discussed. 相似文献