Dielectric materials are electrical insulators that can be polarised by the application of an electric field. The dielectric properties of solids are generally shown in insulators. When the insulators are kept in a strong electric field then the electrons and the nucleus of the atoms of an insulator are pulled in the opposite directions to each other. This separation of electrons and nucleus in opposite directions results in the formation of dipoles in the atoms or molecules. These dipoles can arrange themselves in three ways:
- i) They may arrange themselves systematically so that they have a net dipole moment.
- ii) They can also arrange themselves in a way such that the net dipole moment becomes zero.
- iii) Sometimes there is no dipole in the crystal and only ions are present.
Some dielectric properties of solids are as follows:
- A) Piezoelectricity: Substances in which the dipole aligns itself in an ordered manner to produce a net dipole moment, exhibit piezoelectricity and are known as piezoelectric substances.
- B) Pyroelectricity: When some polar crystals are heated they produce a small electric potential. The electric potential thus produced is known as pyroelectricity. This phenomenon is termed as pyroelectric effect.
- c) Ferroelectricity: Some piezoelectric crystals have permanent dipoles and are called as ferroelectric crystals. Even in the absence of electric field,they retain the arrangement of dipoles. By applying an external electric field the direction of polarisation of dipoles in these kinds of crystals can be reversed. Ferroelectricity is analogous to ferromagnetism.
Example: Rochelle’s salt.
- D) Anti ferroelectricity: The effect under which the net dipole moment of a piezoelectric crystal is zero is referred to as anti-ferroelectricity.
This was a brief layout of the dielectric properties of solids. To know more about the properties of solids please download BYJU’S – the learning app.
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