Ferroelectric materials are materials that possess a natural charge polarization that can be reversed by an external electric field, known as the process of switching. The property of ferroelectricity has been known since 1921 and, as of 2011, over 250 compounds have been shown to display such characteristics. Research has focused on lead titanate, PbTiO3, and related compounds. Of the ferroelectric materials studied as of 2011, all have been shown to be piezoelectric materials. This means that if mechanical pressure or other forms of energetic stress from audio or light energy are applied to such compounds, they will generate electricity.
The applications of ferroelectricity span a wide spectrum of electronics devices, from circuit components like capacitors and thermistors to devices with electro-optics or ultrasound capabilities. One of the most actively researched arenas for ferroelectric materials is that of computer memory. Engineering the materials at a nanometer scale produces what is known as vortex nanodomains that don't require an electric field to switch polarization. Several state university systems in the United States working together through 2011 with the Lawrence Berkeley National Laboratory are perfecting the material, that would require much less electrical power than traditional magnetic computer drives do. It would also be a solid state form of data memory that functions much faster and with greater storage capacity than the flash memory currently on the market, with the potential to one day store entire operating systems and software, making computer start up and processing speeds much greater.
The ferroelectric effect draws its name from ferromagnetism, which describes permanent magnetic materials based on iron that are found in nature. This is a bit of a misnomer, however, as most ferroelectric materials are not based upon the element iron. Salts of titanic acid which are derived from titanium dioxide make up many of the chief ferroelectric materials under research. These include barium titanate, BaTiO3, lead zirconate titanate, PZT, or related compounds like sodium nitrate, NaNO2.
PZT is the most widely used ferroelectric material in industry as of 2011. It is a hybrid material between ferroelectric lead titanate and anti-ferroelectric lead zirconate, which allows formulas for the material to be engineered closer to one or the other ends of the ferroelectric or anti-ferroelectric spectrum. Since PZT can be tuned for its sensitivity to mechanical, audio, or electric fields, and, since it is a ceramic material easily shaped, molded, and cut, it is often used for passive sensors and transmitters in highly specific frequencies.