Rare metal improves performance of energy-harvesting piezoelectric crystals

April 19 (UPI) -- Researchers have discovered that the addition of a rare earth metal significantly improves the performance of piezoelectric crystals.

Piezoelectric crystals are used in sensors, including underwater sonars and medical ultrasound imaging devices. These technologies use perovskite oxide crystals, or PMN-PT crystals.

Scientists have also tried to use piezoelectric crystals, which convert mechanical oscillations into electricity, to power wearable electronics and other types of novel technologies.

An international team of scientists from Australia, China and the United States found a way to improve the performance of PMN-PT crystals. Scientists added samarium atoms during the crystal growth process -- one samarium atom per thousand atoms of the parent crystal -- and found the additive created more homogeneous piezoelectric properties inside the crystal, boosting the crystal's performance.

The piezoelectric coefficient, quantified in picocoulombs per Newton, describes the efficiency of a material's piezoelectric properties. More efficient piezoelectric crystals do more with less.

In lab tests, scientists confirmed that conventional PMN-PT crystals feature a piezoelectric coefficient between 1,200 and 2,500 pC/N. PMN-PT crystals enhanced with samarium produced 3,400 to 4,100 pC/N.

Scientists also noted that the addition of samarium granted the crystals more uniform, or homogeneous, physical properties.

"These crystals are ideal for a variety of sensing applications and could reduce cost by eliminating waste," researchers wrote in their study, published this week in the journal Science.