Editing Ceramic (section)

====Ferroelectricity and supersets====
[[Piezoelectricity]], a link between electrical and mechanical response, is exhibited by a large number of ceramic materials, including the quartz used to [[crystal oscillator|measure time]] in watches and other electronics. Such devices use both properties of piezoelectrics, using electricity to produce a mechanical motion (powering the device) and then using this mechanical motion to produce electricity (generating a signal). The unit of time measured is the natural interval required for electricity to be converted into mechanical energy and back again.

The piezoelectric effect is generally stronger in materials that also exhibit [[pyroelectricity]], and all pyroelectric materials are also piezoelectric. These materials can be used to inter-convert between thermal, mechanical, or electrical energy; for instance, after synthesis in a furnace, a pyroelectric crystal allowed to cool under no applied stress generally builds up a static charge of thousands of volts. Such materials are used in [[motion sensor]]s, where the tiny rise in temperature from a warm body entering the room is enough to produce a measurable voltage in the crystal.

In turn, pyroelectricity is seen most strongly in materials that also display the [[ferroelectric effect]], in which a stable electric dipole can be oriented or reversed by applying an electrostatic field. Pyroelectricity is also a necessary consequence of ferroelectricity. This can be used to store information in [[ferroelectric capacitor]]s, elements of [[ferroelectric RAM]].

The most common such materials are [[lead zirconate titanate]] and [[barium titanate]]. Aside from the uses mentioned above, their strong piezoelectric response is exploited in the design of high-frequency [[loudspeaker]]s, transducers for [[sonar]], and actuators for [[atomic force microscope|atomic force]] and [[scanning tunneling microscope]]s.