排序方式: 共有44条查询结果,搜索用时 10 毫秒
21.
采用Frens法制备金纳米粒子溶胶,通过界面自组装技术在掺磷的非晶碳衬底表面构筑三维的金/氧化石墨烯/金复合结构.以罗丹明B为探针分子,考察金/氧化石墨烯/金复合材料的表面增强拉曼散射活性.结果表明,由于氧化石墨烯的化学增强和金纳米粒子的电磁场增强的协同作用,在该三维复合材料上获得了很强的罗丹明B拉曼信号.所设计的三维金/氧化石墨烯/金复合材料在生物分析、环境监测、疾病防控、食品安全等领域具有潜在的应用价值. 相似文献
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Dramatic reduction in dark current of β-Ga2O3 ultraviolet photodectors via β-(Al0.25Ga0.75)2O3 surface passivation 下载免费PDF全文
Jian-Ying Yue 《中国物理 B》2023,32(1):16701-016701
Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based on β -(Al0.25Ga0.75)2O3/β -Ga2O3 film grown by metal-organic chemical vapor deposition. It was known that various surface states increase dark current and a large number of defects can hinder the transport of carriers, resulting in low switching ratio and low responsivity of the device. In this work, β -(Al0.25Ga0.75)2O3 films are used as surface passivation materials. Owning to its wide band gap, we obtain excellent light transmission and high lattice matching with β -Ga2O3. We explore the change and mechanism of the detection performance of the β -Ga2O3 detector after β -(Al0.25Ga0.75)2O3 surface passivation. It is found that under the illumination with 254 nm light at bias 5 V, the β -(Al0.25Ga0.75)2O3/β -Ga2O3 photodetectors show dark current of just 18 pA and high current on/off ratio of 2.16×105. The dark current is sharply reduced about 50 times after passivation of the β -Ga2O3 surface, and current on/off ratio increases by approximately 2 times. It is obvious that β -Ga2O3 detectors with β -(Al0.25Ga0.75)2O3 surface passivation can offer superior detector performance. 相似文献
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于考虑了Ce-4f电子之间强关联作用PBE+U方案,采用第一性原理计算方法系统研究了掺杂Mn,Pr,Sn,Zr,Se和Te等对CeO2原子结构、电子结构和还原性能影响.针对形氧空位后掺杂离子对体系中电子转移影响,提出了两种不同制:对于Zr,Se和Te等掺杂CeO2,氧空位形能的降低主要是受到氧空位形后结构扭曲影响;而对于Mn,Pr和Sn等掺杂体系,氧空位形能受到结构扭曲和电子转移双重影响,因此,氧空位形后电子首先转移到掺杂离子上而不是通常的Ce4+上.研究发现,当四价掺杂离子到电子后最外层电子全满或半满结构时,氧空位形时所产生的电子会优先转移到掺杂离子上. 相似文献
24.
Coupling interaction between a single emitter and the propagating surface plasmon polaritons in a graphene microribbon waveguide 下载免费PDF全文
The coupling interaction between an individual optical emitter and the propagating surface plasmon polaritons in a graphene microribbon (GMR) waveguide is investigated by numerical calculations, where the emitter is situated above the GMR or in the same plane of the GMR, The results reveal a multimode coupling mechanism for the strong interaction between the emitter and the propagating plasmonic waves in graphene. When the emitter is situated in the same plane of the GMR, the decay rate from the emitter to the surface plasmon polaritons increases more than 10 times compared with that in the case with the emitter above the GMR. 相似文献
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采用固相反应法制备了Tb0.8Eu0.2MnO3多晶材料.对样品的X射线衍射(XRD)分析表明Eu3+固溶于TbMnO3中.测量了样品在低温(100 K ≤T≤ 300 K)和低频下(200 Hz≤f≤100 kHz)的复介电性质.在此温度区间内发现了两个介电弛豫峰.经分析认为低温峰(T≈170 K)起源于局域载流子漂移引起的偶极子极化效应,而高温峰(T≈290 K)则是由离子电导产生的边界和界面层的电容效应引起的.电阻率的测量显示在低温下(T≈230 K)存在明显的导电机制转变.
关键词:
多铁性材料
掺杂
介电性质 相似文献
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Ordered YBa2Cu3Oy nanowires have been fabricated by filling YBa2Cu3Oy melting liquid into the pores of the anodized alumina templates. X-ray powder diffraction proves that YBa2Cu3Oy nanowires crystallized in the Y-123 structure. The temperature dependence of ac susceptibility indicates a superconducting transition at 91 K for the YBa2Cu3Oy nanowire array. 相似文献
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采用基于密度泛函理论的第一性原理计算,系统地研究了BiFeO3的7种不同空间群(R3c,R3m,P4mm,Cm,Pm3m,R3m和R3c)结构及其转变关系.结果表明,铁电相R3c结构是基态,不同结构之间也存在着一定的转变关系,其变化主要包括两种形式,在[111]方向上Bi3+相对FeO6八面体存在一定的位移和FeO6八面体绕[111]极化轴的反铁扭曲旋转.此外,还得出BiFeO3的薄膜结构受到衬底结构的作用会导致其从三方相(R3c)向四方相(P4mm)转变. 相似文献
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研究了La(2-x)Bix/3Ca1/3MnO3体系的电阻行为和磁性转变,当x=0.0,0.2时,样品表现为铁磁转变,居里温度Tc分别为265K和245K,铁磁转变伴随着半导体-金属转变,对应于磁电阻效应的极大值;当x=0.4时,样品表现为复杂的磁性转变,样品的电阻率为半导体特性,对应的磁性转变没有半导体,金属转变发生,在x=0.4和0.6两个样品中,1T外场下85K时获得大于86%的巨磁电阻效应 相似文献