Insulator (electricity)

About: Insulator (electricity) is a research topic. Over the lifetime, 15941 publications have been published within this topic receiving 108950 citations. The topic is also known as: electrical insulator.

Anti-icing performance of RTV coatings on porcelain insulators by controlling the leakage current

Abstract: Considerable work has been done on preventing ice formation on insulators and the modification of the surface characteristics by increasing the contact angle and decreasing the adherent force have been tried with some degree of success. Heating by electric current has however proved to be an effective and practical method for de-icing transmission lines, but difficult to apply to insulators. A room temperature vulcanized (RTV) silicone rubber coating containing sufficient carbon black to render it partially conducting but not enough carbon to lose its surface hydrophobicity, has been investigated to determine if the heat generated would suffice to inhibit ice growth on the insulators. The heat exchange progress was analyzed and the leakage current through it to prevent ice forming was estimated and coatings developed accordingly. The anti-icing performances of these RTV silicone rubber coatings with different leakage current magnitudes were compared in a climate chamber. The results showed that the surface heating effect, together with the hydrophobicity, could significantly reduce the formation of ice on insulators.

Design Principles for Efficient and Stable Water Splitting Photoelectrocatalysts.

Abstract: ConspectusPhotoelectrochemical water splitting is a promising avenue for sustainable production of hydrogen used in the chemical industry and hydrogen fuel cells. The basic components of most photoelectrochemical water splitting systems are semiconductor light absorbers coupled to electrocatalysts, which perform the desired chemical reactions. A critical challenge for the design of these systems is the lack of stability for the majority of desired semiconductors under operating water splitting conditions. One strategy to address this issue is to protect the semiconductor by covering it with a stabilizing insulator layer, creating a metal-insulator-semiconductor (MIS) architecture, which has demonstrated improved stability. In addition to enhanced stability, the insulator layer may significantly affect the electron and hole transfer, which governs the recombination rates. Furthermore, the insertion of an insulator layer leads to the introduction of additional insulator/electrocatalyst and insulator/semiconductor interfaces. These interfaces can impact the system's performance significantly, and they need to be carefully engineered to optimize the efficiencies of MIS systems. In this Account, we describe our recent progress in shedding light on the critical role of the insulator and the interfaces on the performance of MIS systems. We discuss our findings by focusing on the concrete example of planar n-type Si protected by a HfO2 insulator layer and coupled to a Ni or Ir electrocatalyst that performs the oxygen evolution reaction, one of the water splitting half-reactions. To improve our fundamental understanding of the insulator layer, we precisely control the HfO2 insulator thickness using atomic layer deposition (ALD), and we perform a series of rigorous electrochemical experiments coupled with theory and modeling. We demonstrate that by tuning the insulator thickness, we can control the flux and recombination of photogenerated electrons and holes to optimize the generated photovoltage. Despite optimizing the thickness, we find that the maximum generated photovoltage in MIS systems is often significantly lower than the upper performance limit, i.e., there are additional losses in the system that could not be addressed by optimizing the insulator thickness. We identify the sources of these losses and describe strategies to minimize them by a combination of improving the semiconductor light absorption, removing nonidealities associated with interfacial defects, and finding alternative insulators with improved charge carrier selectivity. Finally, we quantify the improvements that can be obtained by implementing these specific strategies. Our collective work outlines strategies to analyze MIS systems, identify the sources of efficiency losses, and optimize the design to approach the fundamental performance limits. These general approaches are broadly applicable to photoelectrochemical materials that utilize sunlight to produce value-added chemicals.

Current-voltage characteristics, dielectric breakdown and potential distribution measurements in Au-SiOx-Au thin film diodes and triodes

Abstract: Vacuum-evaporated Au-SiOx-Au thin film cathodes with insulator thicknesses ranging up to approximately 6000 A have been tested at direct voltages up to 60 V. In addition to exhibiting negative resistivity and single-hole dielectric breakdowns which have previously been observed at voltages leas than 20 V, these samples also showed a destructive breakdown mechanism at a voltage (V β) normally between 20 V and 30 V, which was independent of the insulator thickness. Increased device temperatures and wrinkling of the counter electrode indicated thermal processes at the voltage V β. These results may be explained in terms of a high field region within the insulating layer, where dielectric breakdown is initiated. The existance of such a region has previously been reported, and was confirmed in the present work.

Electrical Conduction in Insulator Particle—Solid‐State Ionic and Conducting Particle‐Insulator Matrix Composites A Unified Theory

Abstract: A unified model is introduced for the first time for electrical conduction in both the insulator particle‐solid‐state ionic and conducting particle‐insulator matrix composites. In the model, the basic formulation of effective medium approximation is reconsidered by replacing the site conductivities with the contact conductivities as well as the probability of site occupation with the probability of contact development. The model predictions are in agreement with the available experimental data. © 2000 The Electrochemical Society. All rights reserved.