Everything about Lead Zirconate Titanate totally explained
Lead zirconate titanate (
[] 0<
x<1) is a
ceramic perovskite material that shows a marked
piezoelectric effect. It is also known as
lead zirconium titanate or
PZT, an abbreviation of the chemical formula.
Being piezoelectric, it develops a
voltage 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 actuators and the like).
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. These properties make PZT-based compounds one of the most prominent and useful
electroceramics. Commercially, it's usually not used in its pure form, rather it's
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. 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.
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.
One of the commonly studied chemical composition is
. 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 Pb
1.1(Zr
0.3Ti
0.7)O
3 (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 Pb
0.83La
0.17(Zr
0.3Ti
0.7)
0.9575O
3 (PLZT 17/30/70).
Further Information
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