Figure: Phase-field-simulated polar nanostructures for a [100]-poled piezoelectric single crystal of complex perovskite structure at 100 K (arrows represent the vectors of dipoles on nanometer scale; horizontal and left-side vertical scales are in nm; right-side colour scale is in degrees).

SFU at the forefront of solid state functional materials science

The motivationPiezoelectric materials generate electricity when squeezed or stretched and change their shape when electrified. They are used in electromechanical transducers that can ‘sense’ environmental forces (vibrations, sound waves, etc.) by giving out electric signals and mechanical responses (shape change, movements, displacements, etc., i.e. ‘actuate’) in response to a controlling electric drive. Thanks to these unique properties, piezoelectrics are used in medical ultrasonic devices for imaging, diagnosis and therapy, in machine tool controllers, in 3D printer heads and in energy harvesters. Other uses include precision positioning and underwater detection and navigation (sonar). There is an increasing demand for more responsive piezoelectric materials for applications in cutting-edge technologies.

The discovery – SFU researchers have contributed significantly to the recent development of high-performance piezoelectric materials of complex oxide perovskite solid solutions in the form of single crystals. These materials exhibit piezoelectric performance superior to the benchmark materials based on polycrystalline lead zirconate-tinanate (PZT), making them the piezoelectric material of choice for a wide range of technological applications. Yet, from a microscopic point of view, the underlying mechanisms and structures that make these single crystal piezoelectric materials so excellent have remained a puzzle. In this work, by means of experimental studies and theoretical modeling and through collaboration, an international team of scientists from Australia, Canada, China and U.S. has revealed the origin of high piezoelectricity in these novel piezoelectric single crystals in terms of atomic arrangements and dipole structure on the nanoscale.  

Its significance – Understanding the role of electrically charged nanoscopic regions (so-called polar nanoregions or domains, 5–10 nm in size with net local dipoles; see figure) in the appearance of high piezoelectricity not only provides a better understanding of the correlation between the arrangements of atoms and ions (nanostructure) and piezoelectric prowess, but it also bolsters future efforts to custom-design more effective piezoelectric materials. Based on these findings, researchers will be able to design and custom-make new and better piezoelectric materials for applications in advanced technologies and the next generation of electromechanical transducers and other functional devices, contributing to developments in the sectors of Energy, Environment, Health, Information Technology and Defence/Security, and improving our standard of living.

Read the paper“The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals” by Fei Li, Shujun Zhang, Tiannan Yang, Zhuo Xu, Nan Zhang, Gang Liu, Jianjun Wang, Jianli Wang, Zhenxiang Cheng, Zuo-Guang Ye, Jun Luo, Thomas R. Shrout & Long-Qing Chen. Nature Communications 7:13807 (2016).  doi:10.1038/ncomms13807

Website article compiled by Jacqueline Watson with Theresa Kitos