A dielectric material is a type of electrical insulator that can be polarized when an electric field is applied. These dielectric properties are typically exhibited by solid insulators. When these insulators are placed in a strong electric field, the electrons and the atomic nucleus are drawn in opposite directions. This results in the creation of dipoles within the atoms or molecules. These dipoles can align themselves in three distinct ways:
- i) They might systematically organize themselves to achieve a net dipole moment.
- ii) They can also position themselves so that the total dipole moment equals zero.
- iii) In some instances, there may be no dipole in the crystal, only ions.
Here are some key dielectric properties of solids:
- A) Piezoelectricity: Materials in which the dipole aligns itself systematically to generate a net dipole moment , exhibit a property known as piezoelectricity. These are referred to as piezoelectric materials.
- B) Pyroelectricity: Certain polar crystals, when heated, generate a small electric potential. This electric potential is referred to as pyroelectricity, and the phenomenon is known as the pyroelectric effect.
- C) Ferroelectricity: Some piezoelectric crystals possess permanent dipoles and are known as ferroelectric crystals. These crystals maintain their dipole arrangement even without an electric field. An external electric field can reverse the polarization direction of the dipoles in these crystals. Ferroelectricity is somewhat similar to ferromagnetism.
Example: Barium Titanate.
- D) Anti ferroelectricity: When the net dipole moment of a piezoelectric crystal is zero, the effect is called anti-ferroelectricity.
This is a concise overview of the dielectric properties of solids. To delve deeper into solid properties, consider exploring more educational resources.