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Tailoring charge affinity,dielectric property,and band gap of bacterial cellulose paper by multifunctional Ti_(2)NbO_(7)nanosheets for improving triboelectric nanogenerator performance

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Nano Research 2023年第2期16卷 3168-3179页

作者： Saichon Sriphan Utchawadee Pharino Thitirat Charoonsuk Phieraya Pulphol Phakkhananan Pakawanit Orawan Khamman Wanwilai Vittayakorn Naratip Vittayakorn Tosapol Maluangnont Faculty of Science Energy and EnvironmentKing Mongkut’s University of Technology North BangkokBangkok 10800Thailand Advanced Material Research Unit School of ScienceKing Mongkut’s Institute of Technology LadkrabangBangkok 10520Thailand Department of Materials Science Faculty of ScienceSrinakharinwirot UniversityBangkok 10110Thailand Synchrotron Light Research Institute(Public Organization) 111 University AvenueMuang DistrictNakhon Ratchasima 30000Thailand Department of Physics and Materials Science Faculty of ScienceChiang Mai UniversityChiang Mai 50200Thailand Department of Chemistry School of ScienceKing Mongkut’s Institute of Technology LadkrabangBangkok 10520Thailand Electroceramics Research Laboratory College of Materials Innovation and TechnologyKing Mongkut’s Institute of Technology LadkrabangBangkok 10520Thailand

Transparent,flexible,and high-performance triboelectric nanogenerator(TENG)from nature-derived materials are required for sustainable society development.However,low triboelectricity from natural material is generally observed.Tunable electronic band diagram(EBD)through facile manipulation is one of the efficient methods to promote the TENG output,requiring fundamental,in depth understanding.Herein,we employed the high quality,single crystal-like Ti_(2)NbO_(7)nanosheets(NSs)with dual dielectric and semiconducting properties as filler for bacterial cellulose(BC)-based TENG.Several techniques including X-ray diffraction(XRD),scanning electron microscopy(SEM),atomic force microscopy(AFM),ultraviolet–visible(UV–vis)absorption,energy dispersive X-ray spectroscopy(EDS),and synchrotron radiation X-ray tomographic microscopy(SRXTM)were applied to characterize the long-range structure,microstructure,optical properties,elemental composition,and three-dimensional(3D)distribution of components in the composites.The semi-transparent and flexible 5 vol.%Ti_(2)NbO_(7)NSs/BC preserved the integrity of cellulose,contained well-dispersed nanosheets,reduced optical band gap(4.20 vs.5.75 eV for BC),and increased surface roughness.The dielectric permittivity and conductivity increased with nanosheets content.Adding negatively-charged Ti_(2)NbO_(7)NSs could regulate the charge affinity of BC composite via shifting of Fermi energy over that of Al.It is found that adding 5 vol.%NSs into the BC film improved electrical outputs(~36 V and~8.8μA),which are 2–4 times higher than that of pure BC,even when paired with Al which lies adjacent in triboelectric series.Our work demonstrated the method to enhance BC-based TENG performance through EBD regulation using multifunctional Ti_(2)NbO_(7)NSs.

关键词： bacterial cellulose Ti_(2)NbO_(7)nanosheets synchrotron radiation X-ray tomographic microscopy dielectric property electronic band diagram triboelectric nanogenerators

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Investigation on dependence of BiFeO_3 dielectric property on oxygen content

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Chinese Physics B 2010年第7期19卷 555-558页

作者：娄艳辉宋桂林常方高王照奎 Department of Physics Henan Normal University

The influence of oxygen content on the dielectric property of BiFeO3 ceramics is studied by experiment and firstprinciples calculation. The experimental result demonstrates that the dielectric constant of BiFeO3 is strongly dependent on introduced oxygen and oxygen vacancies. By comparison with BiFeO3, the introduced oxygen and oxygen vacancies can lead to a reduction in dielectric constant of BiFeO5 at a lower frequency. The first-principles calculation also shows a similar result when photon energy is in a range of 2.0-4.1 eV. A likely explanation is that this oxygen content dependence may be ascribed to the distortion of Fe-O octahedron structure due to oxygen vacancies or excess oxygen ions in the crystal structure of BiFeO3.

关键词： BiFeO3 dielectric property oxygen content

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A Method to Adjust dielectric property of SiC Powder in the GHz Range

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Journal of Materials Science & Technology 2011年第5期27卷 421-425页

作者： Xiaolei Su Jie Xu Zhimin Li Junbo Wang Xinhai He Chong Fu WanchengZhou College of Mechanical & Electronic Engineering Xi'an Polytechnic University Xi~an 710048 China School of Technical Physics Xidian University Xi'an 710071 China State Key Laboratory of Solidification Processing Northwestern Polyteehnical University Xi'an 710072 China

The SiC powders by AI or N doping have been synthesized by combustion synthesis, using AI powder and NH4Cl powder as the dopants and polytetrafluoroethylene as the chemical activator. Characterization by X-ray diffraction, Raman spectrometer, scanning electron microscopy and energy dispersive spectrometer demonstrates the formation of Al doped SiC, N doped SiC and the AI and N co-doped SiC solid solution powders, respectively. The electric permittivities of prepared powders have been determined in the frequency range of 8.2-12.4 GHz. It indicates that the electric permittivities of the prepared SiC powders have been improved by the pure AI or N doping and decrease by the AI and N co-doping. The paper presents a method to adjust dielectric property of SiC powders in the GHz range.

关键词： Silicon carbide Combustion synthesis dielectric property

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Synthesis, Structure and dielectric property of Ba_(1- x)Sr_xZr_yTi_(1- y)O_3

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Chemical Research in Chinese Universities 1999年第3期15卷 267-270页

作者： DING Shi-wen ZHAI Yong-qing ZHANG Xue-jian WANG Hong-ge LIU Hai-yan Department of Chemistry Hebei UniversityBaoding 071002P.R.China

A sieres of Ba 1- x Sr x Zr y Ti 1- y O 3(0≤ x ≤0.4, 0< y <0.3) solid solutions was synthesized by soft chemical method below 100 ℃. The XRD and cell parameters component figures of the series of the solid solution... 详细信息

A sieres of Ba 1- x Sr x Zr y Ti 1- y O 3(0≤ x ≤0.4, 0dielectric constant was increased eight times at room temperature, while the dielectric loss was decreased three times.

关键词： BaTiO 3 solid solution Chemical adulteraion dielectric property

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Effects of HfO_2 buffer layers on the dielectric property and leakage current of Ba_(0.6)Sr_(0.4)TiO_3 thin films by pulsed laser deposition

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Journal of Shanghai University(English Edition) 2010年第6期14卷 456-459页

作者：耿彦程晋荣俞圣雯吴文彪 School of Materials Science and Engineering Shanghai University

Ba0.6Sr0.4TiO3 （BST） thin films with and without HfO 2 buffer layer were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. Dependences of HfO 2 thickness on the dielectric property and leakage current of BST thin films were focused. The dielectric constant of BST thin films increased and then decreased with the increase of HfO 2 thickness, while the dielectric relaxation was gradually improved. The loss tangent and leakage current under positive bias decreased with the HfO 2 thickness increasing. The leakage current analysis based on the Schottky emission indicated an improvement of the BST/Pt interface with HfO 2 buffer layer. The loss tangent, tunability and figure of merit of optimized HfO 2 buffered BST thin film achieved 0.009 8, 21.91% （E max = 200 kV/cm）, 22.40 at 10 6 Hz, respectively.

关键词： Ba0.6Sr0.4TiO3 （BST） thin film HfO 2 buffer layer dielectric property leakage current Schottky emission

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A Bilayer High-Temperature dielectric Film with Superior Breakdown Strength and Energy Storage Density

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Nano-Micro Letters 2023年第9期15卷 479-491页

作者： Jiang-Bo Ping Qi-Kun Feng Yong-Xin Zhang Xin-Jie Wang Lei Huang Shao-Long Zhong Zhi-Min Dang State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijing 100084People’s Republic of China

The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material.However,it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously.Considering that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)films.By revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from electrodes.Worthy to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin layer.In addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.

关键词： Film capacitor dielectric property Boron nitride nanosheets Surface coating Energy storage characteristics

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Construction of all-organic low dielectric polyimide hybrids via synergistic effect between covalent organic framework and cross-linking structure

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Nano Materials Science 2023年第4期5卷 429-438页

作者： Wanjing Zhao Zhaoyang Wei Chonghao Lu Yizhang Tong Jingshu Huang Xianwu Cao Dean Shi Robert KYLi Wei Wu Key Laboratory of Polymer Processing Engineering of Ministry of Education Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced ManufacturingSchool of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou510640China Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials Ministry of Education Key Laboratory for the Green Preparation and Application of Functional MaterialsHubei Key Laboratory of Polymer MaterialsFaculty of Materials Science and EngineeringHubei UniversityWuhan430062China Department of Materials Science and Engineering City University of Hong KongTat Chee AvenueKowloonHong Kong Special Administrative Region of China Jihua Laboratory Foshan528200China

Polyimide(PI)is a promising electronic packaging material,but it remains challenging to obtain an all-organic PI hybrid film with decreased dielectric constant and loss without modifying the monomer.Herein,a series of allorganic PI hybrid films were successfully prepared by introducing the covalent organic framework(COF),which could induce the formation of the cross-linking structure in the PI matrix.Due to the synergistic effects of the COF fillers and the cross-linking structure,the PI/COF hybrid film containing 2 wt%COF exhibited the lowest dielectric constant of 2.72 and the lowest dielectric loss(tanδ)of 0.0077 at 1 MHz.It is attributed to the intrinsic low dielectric constant of COF and a large number of mesopores within the PI.Besides,the cross-linking network of PI prevents the molecular chains from stacking and improves the fraction of free volume(FFV).The molecular dynamics simulation results are well consistent with the dielectric properties data.Furthermore,the PI/COF hybrid film with 5 wt%COF showed a significant enhancement in breakdown strength,which increased to 412.8 kV/mm as compared with pure PI.In addition,the PI/COF hybrid film achieve to reduce the dielectric constant and thermal expansion coefficient(CTE).It also exhibited excellent thermal,hydrophobicity,and mechanical performance.The all-organic PI/COF hybrid films have great commercial potential as next-generation electronic packaging materials.

关键词： Polyimide Covalent organic framework All-organic Cross-linking structure dielectric property Hybrid film

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Microstructural evolution and electromagnetic wave absorbing performance of single-source-precursor-synthesized SiCuCN-based ceramic nanocomposites

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Journal of Advanced Ceramics 2023年第7期12卷 1299-1316页

作者： Jincan Yang Qingbo Wen Bo Feng Yalei Wang Xiang Xiong State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Fundamentals Department Air Force Engineering UniversityXi'an 710051China

Copper(Cu)-containing single-source precursors(SSPs)for the preparation of SiCuCN-based ceramic nanocomposites were successfully synthesized for the first time using polysilazane(PSZ),copper(II)acetate monohydrate(CuAc),and 2-aminoethanol via nucleophilic substitution reactions at silicon(Si)centers of PSZ.The synthesis process,polymer-to-ceramic transformation,and high-temperature microstructural evolution of the prepared ceramics were characterized.dielectric properties and electromagnetic wave(EMW)absorbing performance of the ceramics were investigated as well.The results show that the polymer-to-ceramic transformation finishes at ca.900 ℃,and Cu nanoparticles are homogeneously distributed in a SiCN matrix,forming a SiCN/Cu nanocomposite.After annealing at 1200 ℃,the Cu nanoparticles completely transform into copper silicide(CusSi).Interestingly,the thermal stability of the Cu nanoparticles can be strongly improved by increasing the free carbon content,so that a part of metallic Cu nanoparticles can be detected in the ceramics annealed even at 1300 ℃,forming a SiCN/Cu/Cu_(3)Si/C nanocomposite.Compared with SiCN,the SiCuCN-based nanocomposites exhibit strongly enhanced dielectric properties,which results in outstanding EMW absorbing performance.The minimum reflection coefficient(RC_(min))of the SiCN/Cu/Cu_(3)Si/C nanocomposites annealed at 1300 ℃ achieves-59.85 dB with a sample thickness of 1.55 mm,and the effective absorption bandwidth(EAB)broadens to 5.55 GHz at 1.45 mm.The enhanced EMW absorbing performance can be attributed to an in situ formed unique network,which was constructed with Cu and Cu_(3)Si nanoparticles connected by ring-like carbon ribbons within the SiCN matrix.

关键词： polymer-derived ceramics(PDCs) dielectric property electromagnetic wave(EMW)absorbing copper(Cu) microstructure

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Feasibility of measuring moisture content of green sand by a low frequency multiprobe detector based on dielectric characteristics

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China Foundry 2023年第3期20卷 197-206页

作者： De-quan Shi Gui-li Gao Ming Sun Ya-xin Huang School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China School of Mechanical and Energy Engineering Shanghai Technical Institute of Electronics and InformationShanghai 201411China School of Materials Science&Chemical Engineering Harbin University of Science and TechnologyHarbin 150040China

Green sand is a mixture of silica sand,bentonite,water and coal powder,and other additives.Moisture content is an important index to characterize the properties of green sand.Based on the dielectric characteristics of green sand and transmission line theory,a method for rapidly measuring the moisture content of green sand by means of a low frequency multiprobe detector was proposed.A system was constructed,where six detectors with different arrangements and probes were designed.The experimental results showed that the voltage difference of transmission line increases with the increasing frequency before 29 MHz while decreases after 35 MHz.A voltage difference platform occurs in the range of 29-35 MHz,which is suitable for measuring the moisture content due to its insensitivity to frequency.The electric field intensity gradually decreases with the increase of the probe depth,and the intensity of central probe is always greater than that of the edge probe.When the distance of the probe away from the sand sample surface is 80 mm,the electric field intensity of the edge probe is found to be very weak.The optimal excitation frequency for measuring the moisture content of green sand is 29-33 MHz.The optimal detector is the one with one center probe and three edge probes,and their lengths are 80 mm and 60 mm,respectively.The distance between the center and edge probes is 25 mm,and the diameter of probes is 5 mm.Taking the voltage difference of transmission line,bentonite content,coal powder content and compactability as parameters of the input layer,and the moisture content as a parameter of the output layer,a three-layer BP artificial neural network model for predicting the moisture content of green sand was constructed according to the experimental results at 33 MHz.The prediction error of the model is not higher than 3.3% when the moisture content of green sand is within the range of 3wt.%-7wt.%.

关键词： green sand dielectric property moisture content multiprobe detector BP artificial neural network model

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Carrier Dynamics and Surface Reaction Boosted by Polymer-based Single-atom Photocatalysts

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Chemical Research in Chinese Universities 2022年第5期38卷 1207-1218页

作者： TENG Zhenyuan YANG Hongbin ZHANG Qitao OHNO Teruhisa Department of Applied Chemistry Faculty of EngineeringKyushu Institute of TechnologyKitakyushu 804-8550Japan School of Materials Science and Engineering Suzhou University of Science and TechnologySuzhou 215009P.R.China International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060P.R.China

Carrier dynamics and surface reaction are two critical processes for determining the performance of photocatalytic reaction.Highly designable polymer-based photocatalysts have shown promising protectives in energetic and environmental applications.In this prospective,we first distinguished the differences of physiochemical properties between polymer-based semiconductors and traditional inorganic semiconductors.Then,the effects of single-atom sites on the charge dynamics and reaction kinetics of polymer-based photocatalysts are further elaborated.Time(excitation)-space(wavefunction)population analysis,which can provide relevant information to clarify the structure-excitation relationships after introducing the single atom sites was also reviewed.In the future,with the further development of artificial intelligence,the establishment of an energy function with a regression accuracy close to or reaching the level of density functional theory is highly desired to infer the energetic diagram of the photocatalytic systems at the excited states.Furthermore,coordination structures,interaction with inorganic semiconductors,photocatalytic stability and solvent effects should also be carefully considered in the future studies of polymer-based photocatalyst.

关键词： Carrier dynamics Surface reaction Polymer Single-atom catalyst dielectric property

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