In that paper, they referred to findings by other researchers that an AC electric field can improve the piezoelectric response of the crystal by 20% to 40% compared with the crystal treated by a DC electric field. But the team discovered that inside the crystal during AC switching cycles, the domain sizes actually got bigger, not smaller as would be expected.
“We proposed a theoretical model of domain change under electric fields, we use computation to confirm it, and because of our simulation, we have shown that researchers in the future will have to look inside the crystal,” Chen said. “The previous researchers showed that higher piezoelectric response is due to smaller domains, but they only looked at the surface. We showed computationally that actually, the domains became bigger with higher piezoelectricity, and that was found by examining under the crystal’s surface.”
According to Wang, this new understanding of the relationship between ferroelectric crystal domain size and piezoelectricity can provide guidance to improve piezoelectric performance of materials.
“We hope that this study allows people to rethink the design principles for piezoelectric materials, perhaps creating better piezoelectric materials in ways that were not thought possible before,” Wang said. “This may enable better piezoelectrics made from lower-cost materials, or from materials that are more environmentally friendly.”
Along with Wang and Chen, the other author on the study was Fei Li, a previous postdoctoral researcher in materials science and engineering at Penn State and now a full professor at Xi’an Jiaotong University in China.
The National Science Foundation supported this research.