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Effects of Substrates with Different Dielectric Parameters on Left-Handed Frequency of Left-Handed Materials 下载免费PDF全文
Wedge-shaped left-handed materials (LHMs) with split ring resonators and wires structures are fabricated by photolithography and lift-off techniques, and the variation of left-handed frequency induced by substrates with different dielectric parameters is investigated. The Snell refraction experiments of the LHM samples are carried out on an angular resoled microwave spectrometer, and the results indicate that the left-handed frequencies of the LHMs shifted downward from 10.57 GHz to 9.74 GHz when the dielectric parameters of the LHM substrates increase from 3.7 to 4.8. Moreover, the finite difference time domain method is used to simulate the microwave transmission properties of the left-handed materials with different substrates, and the experimental results are in agreement with the numerical simulation results. In addition, the reason for the shifting of the left-handed frequency of the LHMs is discussed theoretically. 相似文献
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Direct ZnO x-ray detectors with tunable sensitivity are realized by delicately controlling the oxygen flux during the sputtering deposition process. The photocurrents induced by x-rays from a 40 kV x-ray tube with a Cu anode increase apparently as the oxygen flux decreases, which is attributed to the introduction of V_o detects.By introducing V_o defects, the annihilation rate of the photo-generated electron-hole pairs will be greatly slowed down, leading to a remarkable photoconductive gain. This finding informs a novel way to design the x-ray detectors based on abundant oxide materials. 相似文献
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Silicon micropillar electrodes of lithiumion batteries used for characterizing electrolyte additives 下载免费PDF全文
Fangrong Hu 《中国物理 B》2021,30(6):68202-068202
The <100> crystal-oriented silicon micropillar array platforms were prepared by microfabrication processes for the purpose of electrolyte additive identification. The silicon micropillar array platform was used for the study of fluorinated vinyl carbonate (FEC), vinyl ethylene carbonate (VEC), ethylene sulfite (ES), and vinyl carbonate (VC) electrolyte additives in the LiPF6 dissolved in a mixture of ethylene carbonate and diethyl carbonate electrolyte system using charge/discharge cycles, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, and x-ray photoelectron spectroscopy. The results show that the silicon pillar morphology displays cross-shaped expansion after lithiation/delithiation, the inorganic lithium salt keeps the silicon pillar morphology intact, and the organic lithium salt content promotes a rougher silicon pillar surface. The presence of poly-(VC) components on the surface of FEC and VC electrodes allows the silicon pillar to accommodate greater volume expansion while remaining intact. This work provides a standard, fast, and effective test method for the performance analysis of electrolyte additives and provides guidance for the development of new electrolyte additives. 相似文献
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MoSe2的禁带宽度较窄(1.1–1.5 eV),且具有可调谐的激子光电效应,这样使其在光致发光、光电晶体管、太阳能电池和光学非线性等方面具有潜在的应用价值.然而,纯的MoSe2的光生电子空穴复合率较高,限制了其在某些光学领域中的应用.通过设计MoSe2的复合材料,可以降低材料的光生电子空穴复合率,从而扩展其应用领域.首先,通过热溶剂法合成CNT/MoSe2复合材料;然后,通过浇铸法将其分散在甲基丙烯酸甲酯(MMA)中制备成有机玻璃,其中MMA会聚合成聚甲基丙烯酸甲酯(PMMA),并利用改进的Z-扫描技术首次对CNT/MoSe2/PMMA有机玻璃的非线性吸收、非线性散射和光限幅特性进行了研究.研究表明,随着输入能量的变化,通过调节输入能量,CNT/MoSe2/PMMA有机玻璃表现出饱和吸收(SA)和从SA到反饱和吸收的转变.结合材料特性及应用条件要求,可以得到CNT/MoSe2/PMMA有机玻璃在光学设备,如光学限制器和锁模/调Q激光器等方向具有较好的应用前景. 相似文献
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