Synergetic optimization of charge transport and breakdown strength of epoxy nanocomposites: Realizing sandwich topological structure through constructing a SiC@SiO2/EP surface layer and m-BNNS/EP insert layer

Dielectric energy storage capacitors have advantages such as ultra-high power density, extremely fast charge and discharge speed, long service lifespan and are significant for pulsed power system, smart power grid, and power electronics. Polypropylene (PP) is one of the most widely used dielectric materials for dielectric energy storage capacitors. It is of interest to investigate how to improve its electrical breakdown strength by nanodoping and the influencing mechanism of nanodoping on the electrical breakdown properties of polymer nanocomposites. PP/Al2O3 nanocomposite dielectric materials with various weight fraction of nanoparticles are fabricated by melt-blending and hot-pressing methods. Thermally stimulated current, surface potential decay, and dc electrical breakdown experiments show that deep trap properties and associated molecular chain motion are changed by incorporating nanofillers into polymer matrix, resulting in the variations in conductivity and dc electrical breakdown field of nanocomposite dielectrics. Then, a charge transport and molecular displacement modulated electrical breakdown model is utilized to simulate the dc electrical breakdown behavior. It is found that isolated interfacial regions formed in nanocomposite dielectrics at relatively low loadings reduce the effective carrier mobility and strengthen the interaction between molecular chains, hindering the transport of charges and the displacement of molecular chains with occupied deep traps. Accordingly, the electrical breakdown strength is enhanced at relatively low loadings. Interfacial regions may overlap in nanocomposite dielectrics at relatively high loadings so that the effective carrier mobility decreases and the interaction between molecular chains may be weakened. Consequently, the molecular motion is accelerated by electric force, leading to the decrease in electrical breakdown strength. The experiments and simulations reveals that the influence of nanodoping on dc electrical breakdown properties may origin from the changes in the charge transport and molecular displacement characteristics caused by interfacial regions in nanocomposite dielectrics.

Download Full-text

Modulating topological structure of carbon nanotube/cyanate ester-boron nitride/cyanate ester multi-layered composites for enhancing dielectric properties, breakdown strength and energy density

Journal of Materials Science Materials in Electronics ◽

10.1007/s10854-019-01956-z ◽

2019 ◽

Vol 30 (17) ◽

pp. 15952-15963

Author(s):

Jing Yang ◽

Li Yuan ◽

Guozheng Liang ◽

Chunqing Lu ◽

Aijuan Gu

Keyword(s):

Carbon Nanotube ◽

Dielectric Properties ◽

Energy Density ◽

Boron Nitride ◽

Topological Structure ◽

Breakdown Strength ◽

Cyanate Ester ◽

Layered Composites

Download Full-text

TOPOLOGICAL EFFECTS OF CHARGE TRANSFER IN TELOMERE G-QUADRUPLEX: MECHANISM ON TELOMERASE ACTIVATION AND INHIBITION

International Journal of Modern Physics B ◽

10.1142/s021797921350001x ◽

2012 ◽

Vol 27 (04) ◽

pp. 1350001

Author(s):

XIN WANG ◽

SHI-DONG LIANG

Keyword(s):

Charge Transfer ◽

Charge Transport ◽

Topological Structure ◽

Function Method ◽

Energy Gap ◽

Fundamental Property ◽

Structure Transition ◽

Charge Current ◽

G Quadruplex ◽

Topological Effect

We explore the charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of the charge transport in TG4 DNA. The consecutive TG4 (CTG4) is semiconducting with 0.2 ~ 0.3 eV energy gap. Charges transfer favorably in the CTG4, but are trapped in the nonconsecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly ~ 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

Download Full-text

Numerical Simulation on Charge Transport and DC Breakdown in Polyethylene-Based Micro-h-BN/Nano-SiO2 with Filler Orientation Dependent Trap Energy

Energies ◽

10.3390/en14154645 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4645

Author(s):

Xuri Xu ◽

Yu Gao ◽

Jing Li ◽

Zheng Song ◽

Huicun Zhao ◽

...

Keyword(s):

Numerical Simulation ◽

Electric Field ◽

Charge Transport ◽

Breakdown Strength ◽

Hexagonal Boron Nitride ◽

Charge Trapping ◽

Sample Surface ◽

Normal Sample ◽

Normal Vector ◽

Inorganic Particles

In order to improve the thermal conductivity and the insulation properties of polyethylene (PE) used as cable insulation under DC stress, hexagonal boron nitride (h-BN) and inorganic particles have been considered as micro-filler and nano-filler, respectively. As a 2D material, the orientation of h-BN possibly affects the insulation properties of the polymer. It is important to understand the influence of the filler orientation on the insulation performance of the polymer. In this work, a numerical simulation has been performed to investigate the effect of orientation of micro-h-BN on charge transport and DC breakdown of PE-based micro/nano-composites and a comparison between the simulation result and previous literature data has been conducted. The h-BN was designated to be parallel, perpendicular to the normal sample surface vector (the direction of electric field in this work) or randomly distributed in the matrix, and the charge transport behavior and DC breakdown strength in the samples were discussed by using the bipolar charge transport (BCT) model. The results indicated that when the h-BN was perpendicular to the normal vector, the density of trapped charge was the largest and the DC breakdown strength was the highest among the three cases studied. It is suggested that the charge trapping/de-trapping processes and the electric field in the sample vary with the orientation of h-BN through tailoring the trap characteristics of the material.

Download Full-text

TUNNELING SPECTROSCOPY OF MANGANITES WITH NANOSCALE STRUCTURAL NON-UNIFORMITIES

Modern Physics Letters B ◽

10.1142/s0217984908017394 ◽

2008 ◽

Vol 22 (29) ◽

pp. 2811-2819 ◽

Cited By ~ 6

Author(s):

V. M. SVISTUNOV ◽

V. N. LEONOVA ◽

M. A. BELOGOLOVSKII ◽

Yu. V. MEDVEDEV ◽

Yu. F. REVENKO ◽

...

Keyword(s):

Experimental Data ◽

Surface Layer ◽

Charge Transport ◽

Electron Tunneling ◽

Differential Conductance ◽

Surface Layers ◽

Near Surface ◽

Inelastic Tunneling ◽

Metal Tip ◽

Native Surface

We report on our recent electron-tunneling studies of bulk manganite samples that provide important information about the structure of the near-surface layers of the material and the nature of the charge transport across them. It is shown that the even part of the differential conductance of contacts formed by a metallic injector with the surface of a manganite is a power function of the voltage bias. High voltages applied to the sample are found to locally modify the conductance of the degraded native surface layer. Experiments aimed to monitor the force applied to a metal tip pressed into the surface of a manganite prove the presence of sub-surface layers with properties significantly different from those near the surface. Experimental data are analyzed and interpreted within the Glazman–Matveev theory taking into account inelastic tunneling through two metallic "drops" inside the insulating barrier.

Download Full-text