检索结果-南通市图书馆

Enhanced thermoelectric and mechanical properties of Bi0.5Sb1.5te3 alloy with dispersed yttrium oxide ceramic nanoparticles

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第4期43卷 1758-1768页

作者： Cun-Cheng Li Ming-Wei Zhang ji-Wu Xin Lei Wei Wen-Yu Zhao School of Materials Science and Engineering Shandong University of Technology School of Electrical and Electronic Engineering Nanyang Technological University State Key Laboratory of Advanced technology for Materials Synthesis and Processing Wuhan University of Technology

Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi2te3-based composites.Inert ceramic nanoparticles are good candidates for achieving this goal.In this study,we designed and prepared a series of p-type Bi0.5Sb1.5te3nanocomposites decorated with Y2O3ceramic nanoparticles via ball-milling dispersion and spark-plasma sintering.Owing to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were observed.Transport measurements revealed that the Y2O3nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical conductivity.Moreover,the incorporated Y2O3nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal conductivity.Consequently,a peak figure of merit（ZT） of 1.23 at 313 K was achieved for 0.4%Y2O3/Bi0.5Sb1.5te3,which is 13% higher than that of the matrix.In addition,the Vickers hardness of the composite material was 35% higher than that of the matrix.This study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.

关键词： Bi 0.5 Sb 1.5 te 3 alloy Y 2 O 3 ceramic nanoparticles Microstructures Thermoelectric performance Mechanical properties

Chalcogen-dependent catalytic properties of RuX2 (X = S/Se/te) nanoparticles decorated carbon nanofibers for hydrogen evolution in acidic and alkaline media

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第4期17卷 2528-2537页

作者： Chengkai He Yue Wei jia Xu Yujie Wei Tao Wang Rongfei Liu Lvlv ji Zhun Liu Sheng Wang School of Materials Science and Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Physics Shaoxing UniversityShaoxing 312000China Zhejiang Kangjiesi New Material technology Co. LTDZhuji 311800China

Transition metal dichalcogenides(TMDs),with the general formula MX_(2)(M=Mo/W/Fe/Co/Ni,etc.;X=S/Se/te),have attracted extensive research interests for hydrogen evolution reaction(HER).Compared with numerous studies on noble-metal-free TMDs,the chalcogen-dependent HER catalytic properties of noble-metal-based TMDs are lack of sufficient research attention.Herein,a facile electrospinning-assisted synthetic strategy is proposed to synthesize ruthenium dichalcogenides(RuX_(2),X=S/Se/te)nanoparticles decorated carbon nanofibers(CNFs).Benefiting from the identical nanofibrous morphology and exposed crystal planes of RuX_(2)(111),the catalytic activities of RuX_(2)@CNFs samples were investigated and compared in a fair and direct manner.Detailed electrochemical measurements coupled with density functional theory calculations were carried out to probe their intrinsic HER catalytic activities,resulting in the catalytic activity order of RuS_(2)@CNFs>RuSe_(2)@CNFs>Rute_(2)@CNFs in acidic media and that of RuS_(2)@CNFs>Rute_(2)@CNFs>RuSe_(2)@CNFs in alkaline media.The superior catalytic performance of RuS_(2)@CNFs mainly stems from the relative lower HER energy barriers and thereby the higher intrinsic catalytic activity of RuS_(2)(111),leading to ultralow overpotentials of 44 and 9 mV at 10 mA·cm^(-2) in acidic and alkaline media,respectively.RuSe_(2)(111)is endowed with the more optimized Gibbs free energy of hydrogen adsorption(ΔGH*)than Rute_(2)(111),but Rute_(2)(111)shows enhanced catalytic property for H_(2)O dissociation and OH-desorption than RuSe_(2)(111),therefore,resulting in the altered catalytic activity sequences for RuSe_(2) and Rute_(2) in acidic and alkaline media.

关键词： hydrogen evolution reaction transition metal dichalcogenides carbon nanofibers electrocatalysis catalytic activity

Symmetry transformation of nonlinear optical current of tilted Weyl nodes and application to ferromagnetic MnBi_(2)te_(4)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第4期33卷 160-171页

作者：卢倬成冯济 International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China

A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.

关键词： nonlinear optical response topological Weyl semimetals chiral anomaly

terahertz identification and quantification of penicillamine enantiomers

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and techniques 2013年第1期24卷 12-16页

作者： ji te ZHAO Hongwei HAN Pengyu CHEN Min XIAO Tiqiao Shanghai Institute of Applied Physics Chinese Academy of Sciences Center for terahertz Research Rensselaer Polytechnic Institute

Identification and characterization of L-, D- and DL- penicillamine were demonstrated by terahertz time-domain spectroscopy (THz-TDS). To understand the physical origins of the low frequency resonant modes, the density functional theory (DFT) was adopted for theoretical calculation. It was found that the collective THz frequency motions were decided by the intramolecular and intermolecular hydrogen bond interactions. Moreover, the quantification of penicillamine enantiomers mixture was demonstrated by a THz spectra fitting method with a relative error of less than 3.5%. This technique can be a valuable tool for the discrimination and quantification of chiral drugs in pharmaceutical industry.

关键词：太赫兹时域光谱技术青霉胺量化对映体 THz-TDS 识别密度泛函理论氢键相互作用

Enhancing thermoelectric performance in P-type Mg_(3)Sb_(2)-based Zintls through optimization of band gap structure and nanostructuring

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & technology 2024年第3期170卷 25-32页

作者： Yi-bo Zhang ji-Sheng Liang Chengyan Liu Qi Zhou Zhe Xu Hong-bo Chen Fu-cong Li Ying Peng Lei Miao Guangxi Key Laboratory of Information Material Engineering Research Center of Electronic Information Materials and DevicesMinistry of EducationSchool of Material Science and EngineeringGuilin University of Electronic TechnologyGuilin 541004China Guangxi Key Laboratory for Relativity Astrophysics Center on Nanoenergy ResearchGuangxi Key Laboratory of Processing for Nonferrous Metal and Featured MaterialsSchool of Physical Science&TechnologyGuangxi UniversityNanning 530004China Guangxi Key Laboratory of Precision Navigation technology and Application Guilin University of Electronic TechnologySchool of Information and CommunicationGuilin 541004China

P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(te)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low te performance,limiting their application in te devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the te performance of Zintl phase materials or even others.

关键词： Thermoelectric materials Band engineering Nanostructuring P-type Mg_(3)Sb_(2) Ag and Bi Co-doping

Optical properties of carbon materials filled HDPE composites in THz region

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and techniques 2009年第5期20卷 265-270页

作者： CHEN Xiliang MA Mingwang YANG Xiaomin YANG Kang LIU Dan ji te WU Shengwei ZHU Zhiyong Shanghai Institute of Applied Physics Chinese Academy of Science Shanghai 201800 China Graduate School of Chinese Academy of Science Beijing 100049 China

The optical and electrical properties of several composites, formed by filling the high density polyethylene (HDPE) with similar amount of carbon black (CB), multi-walled carbon nanotubes (MWNT) and fullerene (C60), respectively, were characterized using a THz-TDS setup. It was found that the optical parameters and the details of their variation with frequency differ significantly for different kinds of carbon materials. The results are analyzed by using Cole-Cole formula of dipole relaxation under the assumption that carbon particles dispersed in the matrix behave like dipoles and contribute mainly to the dielectric loss in the THz frequency range. Fitting results indicate that MWNT and CB filled composites have a broader distribution of the relaxation time compared with C60 which possesses a nearly single relaxation time. Compared with CB and C60, MWNT filled composite possesses the larger relaxation strength due to its higher electron density and larger conductive clusters. The real part of conductivity for three kinds of composites all follows power law behavior with respect to frequency but the exponents are quite different. These phenomena may be related to the special properties of the fillers as well as their particulate structures, such as aspect ratio, particle size, and aggregate structure, etc.

关键词： HDPE MWNT 碳元素核技术

Dual-Mode Resonant Sectorial Monopole Antenna with Stable Backfire Gain

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年

作者： Feiyan ji Heng ZHANG Xiuqiong XING Wenjun LU Lei ZHU jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Key Laboratory of Wireless Sensor Network & Communication Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences Department of Electrical and Computer Engineering Faculty of Science and Technology University of Macau

A novel design approach to wideband, dual-mode resonant monopole antenna with stable, enhanced backfire gain is advanced. The sectorial monopole evolves from a linear, 0.75-wavelength electric prototype monopole under wideband dual-mode resonant operation. As theoretically predicted by the two resonant modes te9/5,1and experimentally validated at 2.4-GHz band, the designed antenna exhibits a wide impedance bandwidth over 90.1%(i.e., 2.06-5.44 GHz), in which the stable gain bandwidth in the backfire,-x-direction(θ = 90°, φ = 180°) with peak value of 3.2 dBi and fluctuation less than 3 dB is up to 45.3%(i.e., 3.74-5.44 GHz). It is concluded that the stable wideband backfire gain frequency response should be owing to the high-order resonant mode in the unique sectorial monopole antennas.

关键词：

考虑电力间接碳排放不确定性的电-冷-热综合能源系统两阶段鲁棒优化方法

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

电网技术 2024年第1期48卷 50-60页

作者：周特薛云飞季节韩杨包维瀚李付强杜尔顺张宁清华四川能源互联网研究院四川省成都市610299 电子科技大学机械与电气工程学院四川省成都市621000 国家电网有限公司华北分部北京市西城区100052

在“双碳”政策外力驱动下,传统电力系统的低碳化转型至关重要。该文重点研究碳-源-荷多重不确定因素对综合能源系统低碳经济运行的影响,提出综合能源系统两阶段鲁棒优化运行方法。首先,分析综合能源系统并网点的电力间接碳排放强度的... 详细信息

在“双碳”政策外力驱动下,传统电力系统的低碳化转型至关重要。该文重点研究碳-源-荷多重不确定因素对综合能源系统低碳经济运行的影响,提出综合能源系统两阶段鲁棒优化运行方法。首先,分析综合能源系统并网点的电力间接碳排放强度的不确定性,并使用多面体不确定集对其进行建模;其次,对综合能源系统所聚合的设备建立数学模型,并引入碳排放交易机制,分析设备运行成本与碳排放成本;然后,采用列和约束生成(column-and-constraint generation,C&CG)算法将两阶段鲁棒优化模型分解为主问题与子问题循环求解,利用Karush-Kuhn-Tucker(KKT)条件与big-M法对子问题中存在的双层结构与非线性项进行化简与线性化处理;最后,通过算例分析验证所建模型和求解算法的有效性,并剖析所提综合能源系统鲁棒优化方法的低碳经济性与抵御不确定因素波动的能力。

关键词：电力间接碳排放综合能源系统两阶段鲁棒优化列和约束生成算法 KKT条件

Enhanced thermoelectric performance enabled by compositing ZrO_(2)in n-type SiGe alloy with low thermal conductivity

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第3期43卷 1167-1176页

作者： Meng-Fei Wang Hua-Jun Lai ji-Sheng Liang Jun-Liang Chen Wang-Yang Ding Qi Zhou Ying Peng Cheng-Yan Liu Lei Miao Guangxi Key Laboratory for Relativity Astrophysics State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite StructuresSchool of Physical Science and TechnologyGuangxi UniversityNanning530004China Guangxi Academy of Sciences Nanning530007China Key Laboratory of Information Material Engineering Research Center of Electronic Information Materials and DevicesGuilin University of Electronic TechnologyMinistry of EducationGuilin541004China Guangxi Key Laboratory of Precision Navigation technology and Application School of Information and CommunicationGuilin University of Electronic TechnologyGuilin541004China

SiGe-based thermoelectric(te)materials have gained increasing interests due to their low maintenance costs,environmental friendliness and long lifespan.However,the intrinsically high thermal conductivity of Si-based materials also results in poor te properties.In this investigation,a zirconia(ZrO_(2))composite strategy was applied to an n-type SiGe alloy,tremendously elevating its te performance.After mechanical alloying and spark plasma sintering(SPS)processes,the ZrO_(2)induced the formation of nanopores in the SiGe matrix via phosphorus adsorption.Moreover,such increase in porosity enhanced the phonon scattering and dramatically suppressed lattice thermal conductivity,from 2.83 to 1.59 W·m^(-1)·K^(-1)at 873 K.Additionally,reduced phosphorus doping led to an increase in Seebeck coefficients and a relatively minor decrease in electrical conductivity,The power factor didn't deteriorate significantly,either,as its maximum of~3.43 mW·m^(-1-)K^(-2)was achieved at 873 K with(Si_(0.8)Ge_(0.2))_(0.097)P_(0.03)(ZrO_(2))_(0.003).In short,a peak figure of merit(ZT)of~1.27 at 873 K and an average ZT~0.7 from 323 to 873 K were obtained.This study demonstrates that the electrical and thermal transportation of SiGe material can be synergistically tuned by compositing ZrO_(2),illustrating a novel strategy to optimize the te properties of bulk materials.

关键词： Thermoelectric SiGe alloy ZrO2 composting P element adsorption nanopores