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Chapter V Dielectric Study of ……
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this type of dielectric measurement techniques. When the nominally electric
insulating material is placed in a varying electrostatic field, the heating effect
of a material due to its own electric (dielectric) losses is known as dielectric
heating. The material to be heated is placed between two metallic electrodes
and high frequency signals of 2 to 90 MHz are applied by high frequency
oscillator. The resultant heat is generated within the material and in the
homogeneous materials it is through out uniform.
Solid dielectrics are employed for the vast majority of commercial
applications. Important solid dielectrics include many ceramics and glasses;
plastics and rubber; minerals such as quartz, mica, magnesia, and asbestos;
and paper and fibrous products. The mechanical and thermal properties as
well as the electrical response are important in the choice of dielectric for a
particular product. For high mechanical strength and temperature resistance,
ceramic and mineral insulators are preferred, while plastic and rubber are
employed where flexibility is desired. Low-loss non-polar dielectrics, such as
polyethylene or polystyrene, are necessary for many ultra high frequency
applications.
The material requirements for dielectric devices are usually
determined by the specific electrical characteristics desired for the operating
frequencies selected. Semiconductors, such as silicon and germanium, and
piezo-electric or ferroelectric ceramics, including heavy metal titanates,
zirconates, and niobates, have found considerable application. Many authors
have discussed various dielectric properties, dielectric applications and
dielectric theories in details [6-11]. Classical theory of dielectric constant was
also been given by Kachhava and Saxena [12].
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