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What Is Dielectrics?

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  • Written By: Andrew Kirmayer
  • Edited By: Shereen Skola
  • Last Modified Date: 14 September 2014
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    Conjecture Corporation
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The field of dielectrics is a branch of physics that covers how insulating materials separate different electrical charges in a capacitor. A capacitor is a device with two metal plates of opposite charges, with a dielectric insulating material in between the keeps the charges separate. Properties that affect dielectrics can include thermal expansion, thermal conductivity, and specific heat. The strength of the interacting charges in a given material is defined by the dielectric constant. All materials, including air, water, glass, and different parts of the human body have a specific dielectric constant, and dielectrics have been used to develop superconductors, optical telecommunication systems, and microelectronic devices.

Non-metallic solids act as insulators because they don’t conduct charges well, so positive and negative charges remain on opposite sides. The plates in a capacitor can be spaced apart by very small margins, with a dielectric material in between, lowering the strength of an electric field and preventing a device from shorting out. Capacitance arises from a ratio between the charge and the voltage and is measured proportionally to the dielectric constant of the insulating material. If the charge and voltage are too high, the dielectric material fails, the charges can no longer be separated, and enough heat can build up to damage the capacitor and associated electronics.

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The science of dielectrics has been utilized for manufacturing circuit boards and the tiny components that mount to them. It is also possible to fabricate microscopic parts at high speeds using light sources such as visible light, ultraviolet light, and x-rays. Insulating films made of complex polymers also act as dielectrics for very small integrated circuits and their parts. Smaller circuit dimensions means currents are more likely to leak, and an increase in heat can significantly damage a circuit component that can barely be seen with the naked eye. Storage capacitors and nonvolatile memory use materials with a high dielectric constant to resist the effects of strong charges.

Anything from a piece of metal to air to human bone is dielectric and can store an electric charge. Scientists studying nanoscale materials are conscious of dielectrics to help understand how energy is stored in various nanocomposite materials. When manufacturing nanoscale structures, researchers can control how many air bubbles are inside to adjust the dielectric constant. The importance of fabricating materials without defects is addressed by using special microscopes that can measure dielectric properties of insulating materials. Microscopically thin dielectric materials are constantly being fabricated with properties that suit specific applications.

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