scholarly journals Thickness-Dependent DC Electrical Breakdown of Polyimide Modulated by Charge Transport and Molecular Displacement

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1012 ◽  
Author(s):  
Daomin Min ◽  
Yuwei Li ◽  
Chenyu Yan ◽  
Dongri Xie ◽  
Shengtao Li ◽  
...  
Keyword(s):  
Charge Transport ◽  
Carrier Mobility ◽  
Dielectric Material ◽  
Electrical Breakdown ◽  
Electrical Equipment ◽  
Sample Thickness ◽  
Inverse Power ◽  
Breakdown Field ◽  
Influencing Mechanism ◽  
Main Factor

Polyimide has excellent electrical, thermal, and mechanical properties and is widely used as a dielectric material in electrical equipment and electronic devices. However, the influencing mechanism of sample thickness on electrical breakdown of polyimide has not been very clear until now. The direct current (DC) electrical breakdown properties of polyimide as a function of thickness were investigated by experiments and simulations of space charge modulated electrical breakdown (SCEB) model and charge transport and molecular displacement modulated (CTMD) model. The experimental results show that the electrical breakdown field decreases with an increase in the sample thickness in the form of an inverse power function, and the inverse power index is 0.324. Trap properties and carrier mobility were also measured for the simulations. Both the simulation results obtained by the SCEB model and the CTMD model have the inverse power forms of breakdown field as a function of thickness with the power indexes of 0.030 and 0.339. The outputs of the CTMD model were closer to the experiments. This indicates that the displacement of a molecular chain with occupied deep traps enlarging the free volume might be a main factor causing the DC electrical breakdown field of polyimide varying with sample thickness.

scholarly journals Carrier Transport and Molecular Displacement Modulated dc Electrical Breakdown of Polypropylene Nanocomposites

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1207 ◽  
Author(s):  
Daomin Min ◽  
Chenyu Yan ◽  
Rui Mi ◽  
Chao Ma ◽  
Yin Huang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Charge Transport ◽  
Carrier Mobility ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Dielectric Materials ◽  
Breakdown Field ◽  
Smart Power ◽  
Electrical Breakdown Strength ◽  
Effective Carrier

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.

scholarly journals GaN-Based PCSS with High Breakdown Fields

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1600
Author(s):  
Matthew Gaddy ◽  
Vladimir Kuryatkov ◽  
Nicholas Wilson ◽  
Andreas Neuber ◽  
Richard Ness ◽  
...  
Keyword(s):  
Active Region ◽  
High Voltage ◽  
Electrical Breakdown ◽  
Base Material ◽  
Hydride Vapor Phase Epitaxy ◽  
Switching Behavior ◽  
Breakdown Field ◽  
Organic Chemical ◽  
Mesa Structure ◽  
Gap Spacing

The suitability of GaN PCSSs (photoconductive semiconductor switches) as high voltage switches (>50 kV) was studied using a variety of commercially available semi-insulating GaN wafers as the base material. Analysis revealed that the wafers’ physical properties were noticeably diverse, mainly depending on the producer. High Voltage PCSSs were fabricated in both vertical and lateral geometry with various contacts, ohmic (Ti/Al/Ni/Au or Ni/Au), with and without a conductive n-GaN or p-type layer grown by metal-organic chemical vapor deposition. Inductively coupled plasma (ICP) reactive ion etching (RIE) was used to form a mesa structure to reduce field enhancements allowing for a higher field to be applied before electrical breakdown. The length of the active region was also varied from a 3 mm gap spacing to a 600 µm gap spacing. The shorter gap spacing supports higher electric fields since the number of macro defects within the device’s active region is reduced. Such defects are common in hydride vapor phase epitaxy grown samples and are likely one of the chief causes for electrical breakdown at field levels below the bulk breakdown field of GaN. Finally, the switching behavior of PCSS devices was tested using a pulsed, high voltage testbed and triggered by an Nd:YAG laser. The best GaN PCSS fabricated using a 600 µm gap spacing, and a mesa structure demonstrated a breakdown field strength as high as ~260 kV/cm.

Role of Ti and Y in the nucleation of the primary α-Al of Al7075–Ti–Y natural composites and influence of ultrasonic vibration

2021 ◽  
Vol 112 (8) ◽  
pp. 652-664
Author(s):  
Xiao-Hui Chen ◽  
Lei Liu ◽  
Jinbo Li ◽  
Fayun Zhang
Keyword(s):  
Reaction Kinetics ◽  
Grain Refinement ◽  
Ultrasonic Vibration ◽  
Nano Particles ◽  
Influencing Mechanism ◽  
Ultrasonic Time ◽  
Natural Composites ◽  
Corrosion Pits ◽  
Main Factor

Abstract Al7075–Ti–Y natural composites were prepared by using a combination of ultrasonic vibration and casting. The effects of titanium (Ti) and yttrium (Y) on the nucleation of primary α-Al were studied and the influencing mechanism of Y on the TiAl3 formation was analysed. Furthermore, a reaction kinetics model of TiAl3 under ultrasonic vibration was established. The results showed that the uniformly distributed TiAl3 and Al3Y nano-particles resulted in grain refinement. Y changed the morphology of TiAl3 and the appearance of corrosion pits was related to the fact that Y was dissolved within the TiAl3 structure to form Ti(Al,Y)3. The established model revealed that ultrasonic vibration significantly promoted the formation of TiAl3, and that ultrasonic time was the main factor affecting its growth.

scholarly journals Effects of Solvent Vapor Annealing on Morphology and Charge Transport of Poly(3-hexylthiophene) (P3HT) Films Incorporated with Preformed P3HT Nanowires

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1188
Author(s):  
Mingu Jang ◽  
Yang-Il Huh ◽  
Mincheol Chang
Keyword(s):  
Thin Films ◽  
Charge Transport ◽  
Carrier Mobility ◽  
Morphological Changes ◽  
Charge Carrier Mobility ◽  
Solvent Vapor ◽  
Molecular Ordering ◽  
Vapor Annealing ◽  
Solvent Vapor Annealing ◽  
Influence Of Solvent

We systematically studied the influence of solvent vapor annealing on the molecular ordering, morphologies, and charge transport properties of poly(3-hexylthiophene) (P3HT) thin films embedded with preformed crystalline P3HT nanowires (NWs). Solvent vapor annealing (SVA) with chloroform (CF) was found to profoundly impact on the structural and morphological changes, and thus on the charge transport characteristics, of the P3HT-NW-embedded P3HT films. With increased annealing time, the density of crystalline P3HT NWs was increased within the resultant films, and also intra- and intermolecular interactions of the corresponding films were significantly improved. As a result, the P3HT-NW-embedded P3HT films annealed with CF vapor for 20 min resulted in a maximized charge carrier mobility of ~0.102 cm2 V−1 s−1, which is higher than that of pristine P3HT films by 4.4-fold (μ = ~0.023 cm2 V−1 s−1).

scholarly journals The Influence of Morphology on the Charge Transport in Two-Phase Disordered Organic Systems

2015 ◽  
Vol 1737 ◽  
Author(s):  
Cristiano F. Woellner ◽  
Leonardo D. Machado ◽  
Pedro A. S. Autreto ◽  
José A. Freire ◽  
Douglas S. Galvão
Keyword(s):  
Charge Transport ◽  
Master Equation ◽  
Carrier Mobility ◽  
Three Dimensional ◽  
Domain Size ◽  
Threshold Field ◽  
Phase System ◽  
Two Phase ◽  
Donor Acceptor ◽  
Pauli Master Equation

ABSTRACTIn this work we use a three-dimensional Pauli master equation to investigate the charge carrier mobility of a two-phase system, which can mimic donor-acceptor and amorphous-crystalline bulk heterojunctions. Our approach can be separated into two parts: the morphology generation and the charge transport modeling in the generated blend. The morphology part is based on a Monte Carlo simulation of binary mixtures (donor/acceptor). The second part is carried out by numerically solving the steady-state Pauli master equation. By taking the energetic disorder of each phase, their energy offset and domain morphology into consideration, we show that the carrier mobility can have a significant different behavior when compared to a one-phase system. When the energy offset is non-zero, we show that the mobility electric field dependence switches from negative to positive at a threshold field proportional to the energy offset. Additionally, the influence of morphology, through the domain size and the interfacial roughness parameters, on the transport was also investigated.

Research on Influencing Mechanism of Industrial Carbon Emissions in Hebei Province

2012 ◽  
Vol 260-261 ◽  
pp. 1052-1056
Author(s):  
Wei Yang Yu ◽  
Hui Ning Zhao
Keyword(s):  
Energy Consumption ◽  
Carbon Emissions ◽  
Value Added ◽  
Hebei Province ◽  
Added Value ◽  
Industrial Carbon ◽  
Decomposition Model ◽  
Influencing Mechanism ◽  
Index Decomposition ◽  
Main Factor

This paper calculates carbon emissions in Hebei Province based on energy consumption and carbon coefficients and adopts the index decomposition model to analyze the influence of value-added industries and carbon emissions per unit added value on carbon emissions.The results indicate that the increase of value-added industries in Hebei Province is the main factor affecting the growth of carbon emissions, but the decrease of carbon emissions per unit added value induces carbon emissions to a lesser reducing. The conclusions can offer the decision basis for reducing carbon emissions.

scholarly journals Justification of the active method of protecting the insulation of submersible electric motors

2019 ◽  
Vol 124 ◽  
pp. 02003
Author(s):  
V. A. Trushkin ◽  
O. N. Churlyaeva ◽  
R. V. Kozichev
Keyword(s):  
Physical Properties ◽  
Electrical Breakdown ◽  
Electrical Equipment ◽  
Working Environment ◽  
Operating Parameters ◽  
Insulation Resistance ◽  
Electric Motors ◽  
Electrically Conductive ◽  
Active Method ◽  
Conductive Properties

The article provides an analysis of the properties of the working environment of submersible electrical equipment. The influence of the operating parameters of electrical equipment on the physical properties of the fluid (its electrically conductive properties) is considered. Mathematical confirmation of the implementation of electroosmosis in the capillaries of the insulation of submersible electric motors is given. The rationale for the active method of protecting submersible electrical equipment from reducing insulation resistance and preventing electrical breakdown is given.

HOPPING CONDUCTION IN POLYMERS

1994 ◽  
Vol 08 (07) ◽  
pp. 847-854 ◽  
Author(s):  
Heinz Bässler
Keyword(s):  
Charge Transport ◽  
Carrier Mobility ◽  
Localized States ◽  
Time Dependent ◽  
Hopping Conduction ◽  
Moderate Degree ◽  
Density Of Localized States ◽  
Temporal Features ◽  
Gaussian Density ◽  
Energetic Disorder

The concept of hopping within a Gaussian density of localized states introduced earlier to rationalize charge transport in random organic photoconductors is developed further to account for temporal features of time of flight (TOF) signals. At moderate degree of energetic disorder (σ/kT~3.5…4.5) there is a transport regime intermediate between dispersive and quasi-Gaussian type whose signatures are (i) universal TOF signals that can appear weakly dispersive despite yielding a well defined carrier mobility and (ii) an asymmetric propagator of the carrier packet yielding a time dependent diffusivity.

scholarly journals Graphene induced electrical percolation enables more efficient charge transport at a hybrid organic semiconductor/graphene interface

2018 ◽  
Vol 20 (6) ◽  
pp. 4422-4428 ◽  
Author(s):  
Nicolas Boulanger ◽  
Victor Yu ◽  
Michael Hilke ◽  
Michael F. Toney ◽  
David R. Barbero
Keyword(s):  
Charge Transport ◽  
Organic Semiconductor ◽  
Self Assembly ◽  
Carrier Mobility ◽  
Polymer Chains ◽  
Semiconducting Polymer ◽  
Electrical Percolation ◽  
Graphene Interface ◽  
Efficient Charge

Self-assembly of semiconducting polymer chains during crystallization reveals a percolation induced mechanism of charge transport on graphene, which enhances current and carrier mobility.

scholarly journals Fabrication of Fe3O4@SiO2 Nanofluids with High Breakdown Voltage and Low Dielectric Loss

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 716
Author(s):  
Bin Du ◽  
Yu Shi ◽  
Qian Liu
Keyword(s):  
Dielectric Loss ◽  
Breakdown Voltage ◽  
Shell Thickness ◽  
Electrical Breakdown ◽  
Sio2 Nanoparticles ◽  
Electrical Equipment ◽  
Insulating Oil ◽  
Low Dielectric ◽  
Sio2 Shell ◽  
High Dielectric

Insulating oil modified by nanoparticle (often called nanofluids) has recently drawn considerable attention, especially concerning the improvement of electrical breakdown and thermal conductivity of the nanofluids. However, traditional insulating nanofluid often tends to high dielectric loss, which accelerates the ageing of nanofluids and limits its application in electrical equipment. In this paper, three core-shell Fe3O4@SiO2 nanoparticles with different SiO2 shell thickness were prepared and subsequently dispersed into insulating oil to achieve nanofluids. The dispersion stability, breakdown voltages and dielectric properties of these nanofluids were comparatively investigated. Experimental results show the alternating current (AC) and positive lightning breakdown voltage of nanofluids increased by 30.5% and 61%, respectively. Moreover, the SiO2 shell thickness of Fe3O4@SiO2 nanoparticle had significant effects on the dielectric loss of nanofluids.

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