What is a ferroelectric material?

• A tour of some examples of ferroelectric materials An overview • Non-conducting materials may have a net electrostatic polarisation induced by an external electric field. • Where the affects upon observable properties such as elastic, optical and thermal behaviour is large, these materials are termed ferroelectrics.

What is a ferrielectric material?

• If a material exhibits ferroelectric effects in one polar direction, and antiferroelectric effects perpendicular, it may be termed ferrielectric. Perovskites • Perovskite is a naturally occurring mineral with chemical formula CaTiO3. • This is a prototype for many ABO3 materials which are very important in ferroelectrics.

Which crystal class does not support ferroelectricity?

The crystal classification of a material has immediate implications for ferroelectric effects There are 32 crystal classes 11 of them have a centre of symmetry (centrosymmetric) and cannot support ferroelectricity Of the remaining 21, the O-point group (432) also excludes ferroelectricity.

What is the temperature dependence of a ferroelectric?

Other temperature effects • In some ferroelectrics, the temperature dependence of can be reasonably accurately represented by the Curie-Weiss law: • = 0+C/ (T-T0) • C is the Curie constant • T0 is the Curie-Weiss temperature, which in general differs from the Curie temperature (Tc) • Close to T0 becomes very large.

Are hydrogen fuel cells a good alternative to electrochemical storage?

Unlike electrochemical storage technology, the fuel and oxidant are externally supplied and need to be refilled for recycling in a fuel cell. However, the high cost and low efficiency place critical limitations for the broad applications of hydrogen fuel cells.

How does a superconducting magnetic energy storage system work?

Superconducting magnetic energy storage systems(SMESS) store electricity in the magnetic field through a large current circulating in a superconducting coil. Current studies focus on reducing the cost of coils and temperature control system.