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Chapter V Dielectric Study of ……
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the latter dissipates a certain quantity of electrical energy that transforms into
heat energy. This phenomenon is commonly known as "the expense" or "loss
of power”, meaning an average electric power dissipated in material during a
certain interval of time. As a rule the loss of power in a specimen of material,
all other conditions being equal, is directly proportional to the square of the
voltage applied to the specimen (P = V 2 /R). The amount of power loss in a
dielectric under the action of the voltage applied to it is commonly known as
"dielectric loss". This is general term determining the loss of power in an
electrical insulation both at a direct and an alternating voltage.
The process can be represented by simple position of in phase and out
of phase components of dielectric constant. For alternating voltage the
permittivity can therefore be written by equation (5.18) as,
"
'
= tan δ = dielectric loss (5.20)
In practice, ’ is independent of the frequency of applied field but ” is
associated with power absorption. For static fields ” = 0.
5.7 Dielectric Study of Different Materials
Dielectric study has been carried out on different materials by various
workers. In this brief survey an overview is given on dielectric study carried
out on different materials, however, a focus is made on the NLO type KDP
and ADP crystals and their different doped systems. Dielectric studies on
single crystalline materials [13], ceramics [14-15], glasses [16-18], acrylic acid
doped ethyl cellulose films [19], poly (N- Methyl Pyrrole) thin films [20], copper
ferrite- barium titanate composites [21] and Zn- substituted cobalt
ferialuminates [22] have been reported.
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