PMT-PT Crystals

PMN-PT (lead magnesium niobate-lead titanate) and PIN-PMN-PT (lead indium niobate-lead magnesium niobate-lead titanate)

The PMN-PT (lead magnesium niobate-lead titanate) crystal family is known for its extremely high electromechanical coupling coefficient, high piezoelectric coefficient, high strain and low dielectric loss. As a result, ultrasonic probes and sensors of ferroelectric applications made from PMN-PT crystals are more sensitive and have broader bandwidth, and micro-actuators gain more strain.

PMN-PT crystal products are available in different shapes (plates, rings, wedges or boules), which can be provided as-sliced, as tested or electroded.

The second generation of this crystal family is PIN-PMN-PT (lead indium niobate-lead magnesium niobate-lead titanate). Such crystals are particularly attractive to applications where higher ambient temperature and higher power are required. Doped with indium (In) and sometimes with traces of manganese (Mn), PIN-PMN-PT has a higher transition temperature and higher coercive field (Ec) than PMN-PT, which makes it an ideal candidate for SONAR, infrared and pyroelectric applications.

Two typical applications of PMN-PT crystals are medical ultrasound, non-destructive testing (NDT) and energy harvesting. The superior coupling coefficient and electro-mechanical properties give PMN-PT crystal several advantages:
1) Very high sensitivity
2) Very broad bandwidth
These advantages translate into high imaging quality and high efficiency.

When high d33 and high k33 are desired, the crystal boules grown along [001] are used. The (001) plates are cut out of the boule and poled along [001], so the product performance is maximized and in-plate property variation is minimized. Below is a set of recommended domain engineering factors for each applications.

 

The following table shows the typical values of the main properties of PMN.PT, with two different percentages of PT content (lower: about 28%,  higher: about 32%) in comparison with PIN-PMN-PT