Zirconates are compounds which contain zirconium oxyanions. They are most commonly used in the production of advanced ceramic materials. These materials frequently exhibit dielectric and ferroelectric properties that make them useful in electronics applications, and additionally can be used as components of high-temperature solid electrolytes in fuel cells.
One of the most common and useful zirconate ceramics is lead zirconate titanate (PZT). It is a ceramic perovskite material similar to barium strontium titanate (BST) and shows a marked piezoelectric effect—it produces an electrical charge when mechanically compressed, a phenomenon exploited in the production of sophisticated electronic sensors. The piezoelectric effect also works in the opposite direction—PZT can be induced to physically change shape when an external electric field is applied, making it very valuable in actuator applications.
PZT is also pyroelectric, meaning that it develops a voltage difference across two of its faces when it experiences a temperature change, making it useful as a heat detecting sensor. It is also ferroelectric, which means it exhibits a spontaneous electric polarization which can be reversed in the presence of an electric field. These properties make PZT-based compounds one of the most prominent and useful electroceramics.
Commercially, PZT is rarely used in its pure form; rather, it is typically doped with either acceptor dopants or donor dopants. In general, acceptor doping creates hard PZT while donor doping creates soft PZT, which generally differ in their piezoelectric constants. Soft PZT has a higher piezoelectric constant, but larger losses in the material due to internal friction. In hard PZT, domain wall motion is pinned by the impurities, decreasing losses in the material but at the expense of a reduced piezoelectric constant.
PZT-based compounds are used in the manufacture of items such as ultrasound transducers, STM/AFM actuators, high-value ceramic capacitors, FRAM chips, uncooled staring array infrared imaging sensors for thermographic cameras, and other types of sensors. PZT is also used in the manufacture of ceramic resonators for reference timing in electronic circuitry.