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聚苯胺光学吸收及应用 被引量:11
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作者 金绪刚 黄承亚 龚克成 《半导体光电》 EI CAS CSCD 北大核心 1997年第3期203-207,共5页
从结构和性能的角度对聚苯胺不同形态因电子或极子跃迁引起的在可见近红外区的吸收特性进行了总结。重点讨论了本征态盐的分子链构像结构对光学吸收的影响。
关键词 有机聚合物 聚苯胺 光学吸收 半导体材料
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光电系统的匹配设计 被引量:9
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作者 达争尚 陈良益 《光子学报》 EI CAS CSCD 北大核心 2003年第6期669-671,共3页
通过对光电系统中探测器对图像采样的分析 ,由瑞利判别给出了光学系统 探测器匹配的原则 :即瑞利斑的直径等于探测器像元中心距的大小 ,并分析了系统的MTF ;通过分析系统的信息传递关系 。
关键词 光电系统 匹配设计 光电成像系统 探测器 信息传递 系统带宽 电子图像重建系统
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Bezier曲面片的光滑拼接 被引量:5
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作者 王继贵 王仁宏 《辽宁师范大学学报(自然科学版)》 CAS 北大核心 2005年第1期16-18,共3页
在研究两曲面片间几何连续条件基础上,给出了运用构造过渡曲面片来光滑地连接两相邻曲面片的一种方法,所得结果是对刘鼎元,胡康生等研究成果的改进,并给出了本算法的试验结果.
关键词 光滑拼接 BEZIER曲面 过渡曲面 几何连续 两相 算法 连接 构造 条件 研究成果
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Q波段微带到带状线垂直过渡结构
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作者 邹辉耀 孙树风 张晓阳 《太赫兹科学与电子信息学报》 2024年第7期748-751,共4页
层间垂直过渡结构通常被用来实现组件结构的小型化和高密度设计,在毫米波电路布线中起着不可或缺的作用。本文设计了一种可用于Q波段的微带线到带状线的垂直过渡结构,在微带线的末端采用“水滴”匹配结构,以金属通孔连接传输线的形式进... 层间垂直过渡结构通常被用来实现组件结构的小型化和高密度设计,在毫米波电路布线中起着不可或缺的作用。本文设计了一种可用于Q波段的微带线到带状线的垂直过渡结构,在微带线的末端采用“水滴”匹配结构,以金属通孔连接传输线的形式进行射频信号的垂直传输。运用三维高频电磁仿真软件(HFSS)建立该结构,并与其他类似结构进行性能仿真比对。优化结果表明,这种结构在42~47 GHz频带范围内,反射系数小于-20 dB,带内插入损耗优于0.3 dB,可以满足工程应用的要求。相比同类型的其他垂直过渡结构,本文结构在减小占用面积的同时保持了良好的传输性能。 展开更多
关键词 垂直过渡 Q波段 “水滴”匹配 带状线 微带线
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Doping-induced metal–N active sites and bandgap engineering in graphitic carbon nitride for enhancing photocatalytic H_(2 )evolution performance 被引量:5
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作者 Xiaohui Yu Haiwei Su +3 位作者 Jianping Zou Qinqin Liu Lele Wang Hua Tang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第2期421-432,共12页
Durable and inexpensive graphitic carbon nitride(g-C_(3)N_(4))demonstrates great potential for achieving efficient photocatalytic hydrogen evolution reduction(HER).To further improve its activity,g-C_(3)N_(4)was subje... Durable and inexpensive graphitic carbon nitride(g-C_(3)N_(4))demonstrates great potential for achieving efficient photocatalytic hydrogen evolution reduction(HER).To further improve its activity,g-C_(3)N_(4)was subjected to atomic-level structural engineering by doping with transition metals(M=Fe,Co,or Ni),which simultaneously induced the formation of metal-N active sites in the g-C_(3)N_(4)framework and modulated the bandgap of g-C_(3)N_(4).Experiments and density functional theory calculations further verified that the as-formed metal-N bonds in M-doped g-C_(3)N_(4)acted as an"electron transfer bridge",where the migration of photo-generated electrons along the bridge enhanced the efficiency of separation of the photogenerated charges,and the optimized bandgap of g-C_(3)N_(4)afforded stronger reduction ability and wider light absorption.As a result,doping with either Fe,Co,or Ni had a positive effect on the HER activity,where Co-doped g-C_(3)N_(4)exhibited the highest performance.The findings illustrate that this atomic-level structural engineering could efficiently improve the HER activity and inspire the design of powerful photocatalysts. 展开更多
关键词 g-C_(3)N_(4) Photocatalytic H_(2)generation Metal-N active sites transition metal doping band gap engineering
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轨道电路多音调频信号的数字解调方法 被引量:2
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作者 祝林啸 吴嗣亮 《中国铁道科学》 EI CAS CSCD 北大核心 2005年第5期91-95,共5页
针对新型数字编码轨道电路传输的窄带多音调频信号,提出利用FIR高通数字滤波器进行多音调频信号数字解调的方法。FIR高通滤波器幅频响应曲线中过渡带局部具有近似线性的特点。对采样率为10 kHz,过渡带为800 Hz至3 800 Hz的10阶FIR高通... 针对新型数字编码轨道电路传输的窄带多音调频信号,提出利用FIR高通数字滤波器进行多音调频信号数字解调的方法。FIR高通滤波器幅频响应曲线中过渡带局部具有近似线性的特点。对采样率为10 kHz,过渡带为800 Hz至3 800 Hz的10阶FIR高通滤波器幅频响应曲线过渡带局部进行线性拟合。利用其中具有高度线性特性的部分对轨道电路窄带多音调频信号进行幅频变换,从变换结果的幅度包络中得到调制信号信息。对调制信号进行频谱分析,得到原始的列车控制编码信号。仿真结果表明,高通FIR数字滤波器鉴频特性线性度高,所需FIR滤波器阶数少,实现方法简单,在0 dB信噪比、14 dB信干比环境下能够很好地恢复原始调制信号。 展开更多
关键词 轨道电路 调频信号 过渡带 鉴频
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First-principles study of structural and electronic properties of multiferroic oxide Mn_(3)TeO_(6) under high pressure
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作者 潘小龙 王豪 +2 位作者 柳雷 陈向荣 耿华运 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期448-454,共7页
Mn_(3)TeO_(6)(MTO) has been experimentally found to adopt a P2_(1)/In structure under high pressure,which exhibits a significantly smaller band gap compared to the atmospheric R3 phase.In this study,we systematically ... Mn_(3)TeO_(6)(MTO) has been experimentally found to adopt a P2_(1)/In structure under high pressure,which exhibits a significantly smaller band gap compared to the atmospheric R3 phase.In this study,we systematically investigate the magnetism,structural phase transition,and electronic properties of MTO under high pressure through first-principles calculations.Both R3 and P2_(1)/n phases of MTO are antiferromagnetic at zero temperature.The R3 phase transforms to the P2_(1)/n phase at 7.5 8 GPa,accompanied by a considerable volume collapse of about 6.47%.Employing the accurate method that combines DFT+U/and GW,the calculated band gap of R3 phase at zero pressure is very close to the experimental values,while that of the P2_(1)/n phase is significantly overestimated.The main reason for this difference is that the experimental study incorrectly used the Kubelka-Munk plot for the indirect band gap to obtain the band gap of the P2_(1)/n phase instead of the Kubelka-Munk plot for the direct band gap.Furthermore,our study reveals that the transition from the R3 phase to the P2_(1)/n phase is accompanied by a slight reduction in the band gap. 展开更多
关键词 MAGNETISM phase transition band gap high pressure
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波导与微带线和共面线的过渡问题 被引量:2
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作者 龚克 王激 《微波学报》 CSCD 北大核心 1994年第2期12-16,共5页
MIMIC的应用必然涉及到不同传输线之间的过渡问题,本文介绍了两种新型的波导——微带和波导——共面波导过渡器.通过实验,分析了过渡器的特性,并给出了Ka波段内的优化数据.
关键词 波导 微波线 共面线
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Strain engineering in single-,bi-and tri-layer MoS_(2),MoSe_(2),WS_(2)and WSe_(2) 被引量:5
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作者 Felix Carrascoso Hao Li +1 位作者 Riccardo Frisenda Andres Castellanos-Gomez 《Nano Research》 SCIE EI CAS CSCD 2021年第6期1698-1703,共6页
Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS_(2),MoSe_(2),WS_(2) and WSe_(2).In this work we provide a thorough description of the technical de... Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS_(2),MoSe_(2),WS_(2) and WSe_(2).In this work we provide a thorough description of the technical details to perform uniaxial strain measurements on these two-dimensional semiconductors and we provide a straightforward calibration method to determine the amount of applied strain with high accuracy.We then employ reflectance spectroscopy to analyze the strain tunability of the electronic properties of single-,bi-and tri-layer MoS_(2),MoSe_(2),WS_(2) and WSe_(2).Finally,we quantify the flake-to-flake variability by analyzing 15 different single-layer MoS_(2) flakes. 展开更多
关键词 two-dimensional(2D)materials transition metal dichalcogenides strain engineering band gap differential reflectance
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Revisit of the band gaps of rutile SnO2 and TiO2: a first-principles study 被引量:2
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作者 Xuefen Cai Peng Zhang Su-Huai Wei 《Journal of Semiconductors》 EI CAS CSCD 2019年第9期55-60,共6页
From the recent experimentally observed conduction band offset and previously reported band gaps,one may deduce that the valence band offset between rutile SnO2 and TiO2 is around 1 eV,with TiO2 having a higher valenc... From the recent experimentally observed conduction band offset and previously reported band gaps,one may deduce that the valence band offset between rutile SnO2 and TiO2 is around 1 eV,with TiO2 having a higher valence band maximum.This implication sharply contradicts the fact that the two compounds have the same rutile structure and the Γ3^+ VBM state is mostly an oxygen p state with a small amount of cation d character,thus one would expect that SnO2 and TiO2 should have small valence band offset.If the valence band offset between SnO2 and TiO2 is indeed small,one may question the correctness of the previously reported band gaps of SnO2 and TiO2.In this paper,using first-principles calculations with different levels of computational methods and functionals within the density functional theory,we reinvestigate the long-standing band gap problem for SnO2.Our analysis suggests that the fundamental band gap of SnO2 should be similar to that of TiO2,i.e.,around 3.0 eV.This value is significantly smaller than the previously reported value of about 3.6 eV,which can be attributed as the optical band gap of this material.Similar to what has been found in In2O3,the discrepancy between the fundamental and optical gaps of SnO2 can be ascribed to the inversion symmetry of its crystal structure and the resultant dipole-forbidden transitions between its band edges.Our results are consistent with most of the optical and electrical measurements of the band gaps and band offset between SnO2 and TiO2,thus provide new understanding of the band structure and optical properties of SnO2.Experimental tests of our predictions are called for. 展开更多
关键词 SNO2 TiO2 band gap band OFFSET dipole-forbidden transition
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Pressure manipulation of ultrafast carrier dynamics in monolayer WS_(2)
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作者 Yao Li Haiou Zhu Zongpeng Song 《Journal of Semiconductors》 EI CAS CSCD 2023年第8期35-40,共6页
Two-dimensional transition metal dichalcogenides(TMDs)have intriguing physic properties and offer an exciting platform to explore many features that are important for future devices.In this work,we synthesized monolay... Two-dimensional transition metal dichalcogenides(TMDs)have intriguing physic properties and offer an exciting platform to explore many features that are important for future devices.In this work,we synthesized monolayer WS_(2)as an example to study the optical response with hydrostatic pressure.The Raman results show a continuous tuning of the lattice vibrations that is induced by hydrostatic pressure.We further demonstrate an efficient pressure-induced change of the band structure and carrier dynamics via transient absorption measurements.We found that two time constants can be attributed to the capture process of two kinds of defect states,with the pressure increasing from 0.55 GPa to 2.91 GPa,both of capture processes were accelerated,and there is an inflection point within the pressure range of 1.56 GPa to 1.89 GPa.Our findings provide valuable information for the design of future optoelectronic devices. 展开更多
关键词 two-dimensional transition metal dichalcogenides hydrostatic pressure carrier dynamics band structure ultrafast spectroscopy
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External-to-internal synergistic strategy to enable multi-scale stabilization of LiCoO_(2)at high-voltage
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作者 Shuaipeng Hao Yunjiao Li +5 位作者 Jiachao Yang Shan Wang Zhouliang Tan Xiaoming Xi Zhenjiang He Panpan Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第1期516-527,I0013,共13页
High-voltage LiCoO_(2)(LCO)offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries,however,LiCoO_(2)is subject to serious structural and interfacial degradation above voltages>4.5... High-voltage LiCoO_(2)(LCO)offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries,however,LiCoO_(2)is subject to serious structural and interfacial degradation above voltages>4.55 V(vs.Li/Li^(+)).Herein,an in-situ Li_(6.25)La_(3)Zr_(2)A_(l0.25)O_(12)(LLZAO)layer is constructed on the LCO surface to achieve operating voltage at 4.6 V.The detailed characterizations(ex-situ XRD,ex-situ Raman,DFT,etc.)reveal that the LLZAO layer greatly enhances Li+conductivity attributed to the ionconducting layer on the surface/interface,and closely combines with LiCoO_(2)particle to ensure stable cathode/electrolyte interface,thus suppressing the highly reactive Co^(4+)and O^(-)triggered surface side reactions at high-voltage.Moreover,the introduction of La^(3+)/Zr^(4+)/Al^(3+)with a larger ionic radius(La^(3+)/Zr^(4+)are larger than Co^(3+))and weaker electronegativity(La/Zr/Al are weaker than Co)into Co^(3+)sites readjusts the electron cloud density between Co–O–Li,which reinforces the Co–O bond and widens the band-center gap of Co 3d and O 2p,thus restraining the detrimental phase transition(from H3 to H1-3 phase)and the formation of Co_(3)O_(4)spinel phase(attributed to lattice oxygen release),subsequently alleviating the particle cracking and structural collapse during repeated Li^(+)de/intercalation.Therefore,after 100 cycles at 3.0–4.6 V,LCO@1.0LLZAO exhibits a superior discharge capacity of 188.5 m A h g^(-1),with a capacity retention of 85.1%.The above research has brought about meaningful guidance for the evolution of cathode materials with high voltage. 展开更多
关键词 LLZAO layer High-voltage LiCoO_(2) Irreversible phase transition band-center gap Lattice oxygen release
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Calculation of Electronic Structure of Anatase TiO_2 Doped with Transition Metal V,Cr,Fe and Cu Atoms by the Linearized Augmented Plane Wave Method 被引量:2
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作者 廖斌 覃礼钊 +3 位作者 吴先映 侯兴刚 程肯 刘安东 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第7期869-873,共5页
The electronic density of states and band structures of doped and un-doped anatase TiO2 were studied by the Linearized Augmented Plane Wave method based on the density functional theory. The calculation shows that the... The electronic density of states and band structures of doped and un-doped anatase TiO2 were studied by the Linearized Augmented Plane Wave method based on the density functional theory. The calculation shows that the band structures of TiO2 crystals doped with transition metal atoms become narrower. Interesting, an excursion towards high energy level with increasing atomic number in the same element period could be observed after doping with transition metal atoms. 展开更多
关键词 linearized augmented plane wave DOPED anatase Ti02 transition metal energy band
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Chebyshev滤波器设计的优化 被引量:3
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作者 萧强 《华北电力大学学报(自然科学版)》 CAS 北大核心 2003年第3期77-83,共7页
提出了更便于使用的设计通带等纹波Chebyshev滤波器的解析公式。分析了阻带等纹波Chebyshev滤波器,推导了它的实用设计公式,并推出了保证通带和阻带指标前提下获得过渡带尽可能窄的优化形式。通过设计举例,比较了3种类型滤波器的性能,... 提出了更便于使用的设计通带等纹波Chebyshev滤波器的解析公式。分析了阻带等纹波Chebyshev滤波器,推导了它的实用设计公式,并推出了保证通带和阻带指标前提下获得过渡带尽可能窄的优化形式。通过设计举例,比较了3种类型滤波器的性能,指出阻带等纹波Chebyshev滤波器的优化设计与常用的通带等纹波Chebyshev滤波器设计有大致相同的实现成本和性能,又具备某些特殊优点,是值得广泛选用的设计。 展开更多
关键词 Chebyshev滤波器 设计 优化 数字信号处理 相频特性 幅频特性
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基于LGA工艺的D波段微带线-波导过渡结构 被引量:3
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作者 陈柏燊 唐杨 +3 位作者 岳海昆 朱华兵 闻彰 邓贤进 《太赫兹科学与电子信息学报》 北大核心 2019年第5期735-738,共4页
设计了一个工作于D波段的微带转波导结构。过渡结构由2部分组成,分别为微带-带状线过渡结构和带状线-波导过渡结构。相比传统的微带至波导结构,该结构无需额外的金属波导短路结构,减少了加工流程,直接和标准波导相连即可。仿真结果表明,... 设计了一个工作于D波段的微带转波导结构。过渡结构由2部分组成,分别为微带-带状线过渡结构和带状线-波导过渡结构。相比传统的微带至波导结构,该结构无需额外的金属波导短路结构,减少了加工流程,直接和标准波导相连即可。仿真结果表明,在122~140 GHz范围内,反射系数小于-10 dB,最小插入损耗为1.85 dB。该过渡结构基于栅格阵列(LGA)封装工艺,能够直接与其他的芯片和无源器件进行集成和封装,对射频微系统的集成具有重要意义。 展开更多
关键词 过渡结构 微带线 带状线 波导 D波段 系统集成
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Direct Observation of NN Pairs Transfer in GaP1-xNx (x=0.12%) 被引量:1
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作者 吕毅军 高玉琳 +4 位作者 郑健生 张勇 MASCARENHAS A. 辛火平 杜武青 《Chinese Physics Letters》 SCIE CAS CSCD 2005年第11期2957-2959,共3页
Time-resolved photoluminescence (TRPL) was applied to investigate the transient process in GaP1-xNx (x = 0.12%) alloy. The filling, transferring and decay processes among nitrogen pairs are directly observed. The ... Time-resolved photoluminescence (TRPL) was applied to investigate the transient process in GaP1-xNx (x = 0.12%) alloy. The filling, transferring and decay processes among nitrogen pairs are directly observed. The NN4 pair, either not present or only a small obscure peak under a proper excitation condition in the steady-state photoluminescence spectrum, is well resolved by TRPL. 展开更多
关键词 NITROGEN-BOUND EXCITONS band-GAP ALLOYS PHOTOLUMINESCENCE DEPENDENCE transition EVOLUTION GAASN DECAY TIME
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Threshold and decay properties of transient isolated turbulent band in plane Couette flow 被引量:1
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作者 Jianzhou LU Jianjun TAO +1 位作者 Weitao ZHOU Xiangming XIONG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第10期1449-1456,共8页
By direct numerical simulations of the plane Couette flow (PCF) in a large computational domain, it is shown that an isolated turbulent band decays monotonically at low Reynolds numbers but experiences transient growt... By direct numerical simulations of the plane Couette flow (PCF) in a large computational domain, it is shown that an isolated turbulent band decays monotonically at low Reynolds numbers but experiences transient growth before the eventual relaminarization at moderate Reynolds numbers. The lower bound Reynolds number of the transient-growth regime is determined as 286. The width, length, and tilt angle of the iso- lated band structure are defined based on the disturbance kinetic energy in the mid-plane, and the geometric characteristics of the band can be described with a tilted rectangle. It is illustrated that before its eventual fragmentation, the isolated turbulent band decays in a style of longitudinal contraction, where the center, width, and tilt angle of the band keep almost constant but the band length contracts with a statistically constant velocity. 展开更多
关键词 plane COUETTE flow (PCF) SUBCRITICAL transition TURBULENT band
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Band Structures and Two-photon Absorption of ZnGeP_2 and AgGaS_2 Crystals 被引量:1
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作者 程文旦 谢知 +3 位作者 吴东升 黄淑萍 王金云 张浩 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2010年第6期950-956,共7页
Band structure and bonding properties have been investigated in terms of periodic density functional theory(DFT) method,and two-photon absorption(TPA) spectra have been simulated by two-band model for ZnGeP2 and A... Band structure and bonding properties have been investigated in terms of periodic density functional theory(DFT) method,and two-photon absorption(TPA) spectra have been simulated by two-band model for ZnGeP2 and AgGaS2 crystals.It has been predicted that the AgGaS2 crystal has a wider window of nonlinear transmission,and the laser pumping energy larger than 1.02 and 1.35 eV will lead to deleterious TPA of higher nonlinear effect for ZnGeP2 and AgGaS2 crystals,respectively.Electron origin of TPA for them is also discussed. 展开更多
关键词 DFT band structure TPA electron transition
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Precision mapping the topological bands of 2D spin-orbit coupling with microwave spin-injection spectroscopy 被引量:1
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作者 Xiao-Tian Xu Chang-Rui Yi +5 位作者 Bao-Zong Wang Wei Sun Youjin Deng Xiong-Jun Liu Shuai Chen Jian-Wei Pan 《Science Bulletin》 SCIE EI CAS CSCD 2018年第22期1464-1469,共6页
To investigate the band structure is one of the key approaches to study the fundamental properties of a novel material.We report here the precision band mapping of a 2-dimensional(2D) spin-orbit(SO) coupling in an opt... To investigate the band structure is one of the key approaches to study the fundamental properties of a novel material.We report here the precision band mapping of a 2-dimensional(2D) spin-orbit(SO) coupling in an optical lattice.By applying the microwave spin-injection spectroscopy, the band structure and spin-polarization distribution are achieved simultaneously.The band topology is also addressed with observing the band gap close and re-open at the Dirac points.Furthermore, the lattice depth and the Raman coupling strength are precisely calibrated with relative errors in the order of 10^(-3).Our approach could also be applied for exploring the exotic topological phases with even higher dimensional system. 展开更多
关键词 2D SPIN-ORBIT coupling MICROWAVE SPIN-INJECTION SPECTROSCOPY Spin polarization TOPOLOGICAL band TOPOLOGICAL phase transition
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Strain effect on the orientation-dependent harmonic spectrum of monolayer aluminum nitride 被引量:1
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作者 ZiWen Wang ShiCheng Jiang +7 位作者 GuangLu Yuan Tong Wu Cheng Li Chen Qian Cheng Jin Chao Yu WeiJie Hua RuiFeng Lu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2020年第5期98-104,共7页
In this study, we theoretically investigate the strain effect on the orientation-dependent high-order harmonic generation(HHG) of monolayer aluminum nitride(Al N) by solving the multiband semiconductor Bloch equations... In this study, we theoretically investigate the strain effect on the orientation-dependent high-order harmonic generation(HHG) of monolayer aluminum nitride(Al N) by solving the multiband semiconductor Bloch equations in strong laser fields. Our simulations denote that the efficiency of the orientation-dependent HHG is considerably enhanced when a 15% biaxial tensile strain is applied to Al N, which is attributed to the downshifting energy level of the conduction band. Furthermore, the odd-even feature in the orientation-dependent high harmonic spectra owing to the strain is considerably different when compared with that in the case without strain. The enhanced quantum interference between different energy bands in strained Al N around the Γ-M direction is responsible for the observed odd-even distributions of the orientation-dependent HHG. This study helps to better understand the HHG in solids by tuning their electronic structures. 展开更多
关键词 ULTRAFAST strong laser field HIGH-ORDER HARMONIC generation MONOLAYER material strain modulation band structure transition DIPOLE MOMENT
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