| Lead zirconate titanate | |
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Lead zirconate titanate |
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Other names
PZT |
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| Identifiers | |
| CAS number | 12626-81-2 |
| PubChem | 159452 |
| EC-number | 235-727-4 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | (Pb[ZrxTi1-x]O3 0≤x≤1) |
| Molar mass | 303.065 to 346.4222 g/mol |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Lead zirconate titanate (Pb[ZrxTi1-x]O3 0≤x≤1), also called PZT, is a ceramic perovskite material that shows a marked piezoelectric effect. PZT-based compounds are composed of the chemical elements lead and zirconium and the chemical compound titanate which are combined under extremely high temperatures. A filter is then used to remove the particulates. PZT-based compounds are used in the manufacturing of ultrasound transducers, in the manufacturing of ceramic capacitors, STM/AFM actuators (tubes), and the like. PZT was developed by Yutaka Takagi, Gen Shirane and Etsuro Sawaguchi, physicists at the Tokyo Institute of Technology, around 1952. PZT is a hazardous material, registered as CAS registry number 12626-81-2 , EC-No 235-727-4, and PubChem 159452
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Its properties make PZT-based compounds one of the most prominent and useful electroceramics. Being piezoelectric, it develops a voltage (or potential difference) across two of its faces when compressed (useful for sensor applications), or physically changes shape when an external electric field is applied (useful for actuator applications). The dielectric constant of PZT can range from 300 to 3850 depending upon orientation and doping.[1]
Being pyroelectric, this material develops a voltage difference across two of its faces when it experiences a temperature change. As a result, it can be used as a sensor for detecting heat.
It is also ferroelectric, which means it has a spontaneous electric polarization (electric dipole) which can be reversed in the presence of an electric field.
The material features an extremely large dielectric constant at the morphotropic phase boundary (MPB) near x = 0.52.[2]
PZT is used to make ultrasound transducers and other sensors and actuators, as well as high-value ceramic capacitors and FRAM chips. PZT is also used in the manufacture of ceramic resonators for reference timing in electronic circuitry. In 1975 Sandia National Laboratories was working on anti-flash goggles to protect aircrew from burns and blindness in case of a nuclear explosion. The PLZT lenses could turn opaque in less than 150 microseconds.
Commercially, it is usually not used in its pure form, rather it is doped with either acceptor dopants, which create oxygen (anion) vacancies, or donor dopants, which create metal (cation) vacancies and facilitate domain wall motion in the material. In general, acceptor doping creates hard PZT while donor doping creates soft PZT. Hard and soft PZT's generally differ in their piezoelectric constants. Piezoelectric constants are proportional to the polarization or to the electrical field generated per unit of mechanical stress, or alternatively is the mechanical strain produced by per unit of electric field applied. In general, 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 thereby lowering the losses in the material, but at the expense of a reduced piezoelectric constant.
One of the commonly studied chemical composition is PbZr0.52Ti0.48O3. The increased piezoelectric response and poling efficiency near to x = 0.52 is due to the increased number of allowable domain states at the MPB. At this boundary, the 6 possible domain states from the tetragonal phase <100> and the 8 possible domain states from the rhombohedral phase <111> are equally favorable energetically, thereby allowing a maximum 14 possible domain states.
Like structurally similar lead scandium tantalate and barium strontium titanate, PZT can be used for manufacture of uncooled staring array infrared imaging sensors for thermographic cameras. Both thin film (usually obtained by chemical vapor deposition) and bulk structures are used. The formula of the material used usually approaches Pb1.1(Zr0.3Ti0.7)O3 (called PZT 30/70). Its properties may be modified by doping it with lanthanum, resulting in lanthanum-doped lead zirconate titanate (PLZT, also called lead lanthanum zirconate titanate), with formula Pb0.83La0.17(Zr0.3Ti0.7)0.9575O3 (PLZT 17/30/70).[3]