共查询到18条相似文献,搜索用时 187 毫秒
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研究了应用于锂二次电池正极的新型高能量密度存贮材料Li(AlxCo1-x)O2 (x=01—05)的磁性.发现Al3+的掺杂可导致Co3+中d电子自旋态发生变化,即有部分d电子进入高自旋态.伴随Co3+中电子状态的改变,材料结构演化也发生了相应变化,表现为c/a比增大明显减缓,较好地解释了材料结构对Vegard定律的正偏离.这对材料的微观结构与性能设计具有重要意义.
关键词:
锂电池材料
Li(AlxCo1-x)O2
磁性
自旋态
结构演化 相似文献
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在壳模型下探讨了6—11Li核的某些异常性质,特别是滴线核11Li奇异性质可能的微观起因.发现6Li核基态的电四极矩敏感地依赖于相互作用力中的张量力分量,6—8Li核第一激发态电四极约化跃迁几率增大,呈现集体性,可能是由集团结构所致,对3≤Z≤5和N≈8附近核,存在可能的跨壳激发或壳隙消失现象. 相似文献
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采用超声化学沉积法制备了ZnS:Mn2+/聚苯乙烯核壳结构和ZnS:Mn2+空心球.产物分别用透射电镜、X射线衍射仪和光致发光谱进行了表征.透射电镜结果表明,在聚苯乙烯胶体微球表面覆盖了平均尺寸为9nm的ZnS:Mn2+纳米颗粒,X射线衍射结果进一步验证了这个结论.将核壳粒子在500℃灼烧除去PS核后,可以得到空心的ZnS:Mn2+微球,Mn2+的发射谱的峰位在540nm,与体相材料相比,蓝移了45nm,这可能是由于壳层结构引起Mn-O八面体畸变,进而导致能带结构变化引起的. 相似文献
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用固相反应法和脉冲激光沉积 (PLD)制备了CaCu3Ti4O1 2 块材和薄膜 ,获得了相对介电常数ε′( 1kHz ,3 0 0K)高于140 0 0的介电特性 ,是目前该体系最好的结果 .报道了 ( 0 0l)取向高质量CaCu3Ti4O1 2 外延薄膜及其介电性质 .CaCu3Ti4O1 2 相对介电常数ε′在 10 0— 3 0 0K温度范围内基本保持恒定 ,稳定性好 .基于跳跃电导模型 ,对CaCu3Ti4O1 2薄膜介电电导的频率依赖关系作了合理解释 相似文献
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理论计算表明,介质包覆导体颗粒用作电流变液的分散相,可以获得高剪切应力的电流变液.采用溶胶-凝胶技术在尺度为5—10μm的石墨颗粒表面成功地包覆了TiO2,获得了金红石相TiO2包覆石墨的复合颗粒.配制成复合颗粒/硅油电流变液,其剪切应力与纯TiO2/硅油电流变液相比,可提高一个数量级.当电场强度为1.7kV/mm时,复合颗粒/硅油电流变液的剪切应力可达1.25kPa,电流密度小于10μA/cm2.
关键词:
电流变液
包覆
2')" href="#">TiO2
石墨 相似文献
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极性分子型电流变液是一种新型的电流变材料.其介电颗粒上吸附极性分子,极性分子在颗粒间强局域电场作用下发生取向是产生巨电流变效应的关键.通过对Ca—Ti—O(CTO)体系极性分子型电流变液电流密度的测量发现,其导电行为遵从Poole-Frenkel效应的规律,这是极性分子型电流变液的重要特征之一.而500 ℃处理过的CTO粉体不含极性分子,所配制的电流变液无巨电流变效应,其电流密度随外电场强度近似地呈线性关系,显示出传统电流变液特性. 相似文献
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《Current Applied Physics》2009,9(4):755-759
In order to reduce the density mismatch between TiO2 and the low dielectric medium and improve the dispersion stability of the electrophoretic particles in the low dielectric medium for electrophoretic display application, polystyrene/titanium dioxide (PS/TiO2) core–shell particles were prepared via in-situ sol–gel method by depositing TiO2 on the PS particle which was positively charged with 2-(methacryloyloxy)ehyl trimethylammonium chloride (DMC). The morphology and average particle size of PS/TiO2 core–shell particles were observed by transmission electron microscopy (TEM), scanning electron microscope (SEM) and particle size analyzer. It was found that density of PS/TiO2 core–shell particles were reduced obviously and the particles can suspend in the low dielectric medium of low density. The PS/TiO2 core–shell particles can endure ultrasonic treatment because of the interaction between TiO2 and PS. Zeta potential and electrophoretic mobility of the fabricated core–shell particles in a low dielectric medium with charge control agent was measured to be −44.3 mV and −6.07 × 10−6 cm2/Vs, respectively, which presents potential in electronic paper application. 相似文献
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Jin-Wook Shin Kyung Yoon Chung Ji Heon Ryu In-Wook Park Dang-Hyok Yoon 《Applied Physics A: Materials Science & Processing》2012,107(4):769-775
Li4Ti5O12 for anodic active material of lithium ion batteries is synthesized using different Li/Ti ratios of 3.5/5.0, 4.0/5.0 and 4.5/5.0 by a solid-state reaction between Li2CO3 and anatase TiO2 at 850?°C. All samples contain a small amount of transformed rutile TiO2 in the final Li4Ti5O12, where the amount of rutile TiO2 decreases with the increase in Li/Ti ratio. A stoichiometric Li4Ti5O12 with Li/Ti = 4.0/5.0 shows a slightly larger particle size and higher charge capacity than those of Li-deficient and Li-excessive particles, while the discharging rate capability is shown to mainly depend on particle size regardless of Li/Ti ratio. According to the time-resolved X-ray diffraction patterns using a synchrotron source, however, no significant difference is found in spite of the difference in Li/Ti ratio, indicating the structural stability of Li4Ti5O12 during the Li insertion and extraction process. 相似文献
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通过掺杂稀土元素,使TiO2电流变液的屈服强度提高到近5kPa(3kV/mm)。用DSC-TG、IR和XRD等手段对材料的Sol-gel制备过程和产物的晶体结构进行了分析。结果表明纯TiO2和掺杂稀土TiO2凝胶的分解分三阶段完成,并形成锐钛矿结构。掺杂浓度小于一定值时,稀土离子以置换Ti位固溶于TiO2晶格中并引起晶格膨胀。认为适当掺杂所导致的晶格常数变化改善了材料的介电性能,从而使TiO2的电流变性能优化。 相似文献
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将平均晶粒尺寸为4.6 nm的金粒子通过静电作用粘附于聚苯乙烯(PS)微球表面用于化学镀,化学镀金后PS表面的金沉积层几乎达到完全包覆,厚度70~90 nm;在Au/PS表面进行化学镀银,沉积的银颗粒堆积紧密,颗粒大小较先前沉积的金颗粒大,镀覆层厚度增厚至200~400 nm;模板去除后,获得了完全自支撑的Au40Ag60空心微球结构的圆柱状泡沫材料。制备的金银合金泡沫由直径约10 m的空心球壳组成,圆柱体直径约5 mm,密度约1.2 g/cm3。 相似文献
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N. Manikanthababu N. Arun M. Dhanunjaya V. Saikiran S.V.S. Nageswara Rao 《辐射效应与固体损伤》2015,170(3):207-217
The current trend in miniaturization of metal oxide semiconductor devices needs high-k dielectric materials as gate dielectrics. Among all the high-k dielectric materials, HfO2 enticed the most attention, and it has already been introduced as a new gate dielectric by the semiconductor industry. High dielectric constant (HfO2) films (10?nm) were deposited on Si substrates using the e-beam evaporation technique. These samples were characterized by various structural and electrical characterization techniques. Rutherford backscattering spectrometry, X-ray reflectivity, and energy-dispersive X-ray analysis measurements were performed to determine the thickness and stoichiometry of these films. The results obtained from various measurements are found to be consistent with each other. These samples were further characterized by I–V (leakage current) and C–V measurements after depositing suitable metal contacts. A significant decrease in the leakage current and the corresponding increase in device capacitance are observed when these samples were annealed in oxygen atmosphere. Furthermore, we have studied the influence of gamma irradiation on the electrical properties of these films as a function of the irradiation dose. The observed increase in the leakage current accompanied by changes in various other parameters, such as accumulation capacitance, inversion capacitance, flat band voltage, mid-gap voltage, etc., indicates the presence of various types of defects in irradiated samples. 相似文献
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Lei Zhang Haibo Wang Zefang Zhang Fei Qin Weili Liu Zhitang Song 《Applied Surface Science》2011,258(3):1217-1224
Monodisperse silica-coated polystyrene (PS) nano-composite abrasives with controllable size were prepared via a two-step process. Monodisperse positively charged PS colloids were synthesized via polymerization of styrene by using a cationic initiator. In the subsequent coating process, silica formed shell on the surfaces of core PS particles via the ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane. Neither centrifugation/water wash/redispersion cycle process nor surface modification or addition surfactant was needed in the whole process. The morphology of the abrasives was characterized by scanning electron microscope. Transmission electron microscope and energy dispersive X-ray analysis results indicated that silica layer was successfully coated onto the surfaces of PS particles. Composite abrasive has a core-shell structure and smooth surface. The chemical mechanical polishing performances of the composite abrasive and conventional colloidal silica abrasive on blanket copper wafers were investigated. The root mean square roughness decreases from 4.27 nm to 0.56 nm using composite abrasive. The PS/SiO2 core-shell composite abrasives exhibited little higher material removal rate than silica abrasives. 相似文献