Scientists discover the key to piezoelectric excellence in the newer materials read more at here www.spinonews.com/index.php/item/885-scientists-discover-the-key-to-piezoelectric-excellence-in-the-newer-materials

Scientists at the Department of Energy's Oak Ridge National Laboratory and their team have used neutron scattering to discover the key to piezoelectric excellence in the newer materials, which are called Relaxor-based ferroelectrics.

Relaxor-based oxide ferroelectrics have revolutionized piezoelectric devices. Compared with the performance of traditional materials, the strong response of Relaxor-based ferroelectrics yields a more detailed electrical signal that produces better images.

Michael Manley of ORNL said, we figured out at an atomic level why certain materials are so great at mechanically responding to an electric field by changing shape or size.

The finding provides a basis for high-performance actuators and sensors. Compared to traditional polycrystalline materials, the newer piezoelectric crystals generate a greater mechanical force in response to an applied electric field.

The ORNL-led team was surprised that the key to the impressive performance of Relaxor-based ferroelectrics is the vibrations of tiny volumes of the material, called polar Nano regions.

The mechanical response of Relaxor-based ferroelectric crystals is based on rotations of larger electrically aligned domains, about 20 microns in size. Polar Nano regions as narrow as 2 nanometers are responsible for the enhanced electromechanical coupling that enables the dramatic improvements in piezoelectric applications by lowering the resistance to this shearing in the crystal.

The new study used neutron scattering measurements of lattice dynamics and local structure to reveal the basis of the giant electromechanical coupling.

Traditional ferroelectric materials are stiff; it is difficult for their large domains to rotate. But in ultra-responsive, modern Relaxor-based ferroelectrics, the vibrations of the polar Nano regions mix with the vibrations of the surrounding lattice to form hybrid vibrations.

The hybrid vibrations result in a softer, low-energy shear, which makes it easier for the macroscopic regions of polarization to rotate. That means a larger mechanical response when an electric field is applied.

Manley said, the point of this study is the interaction of these Nano regions with the average lattice which enables a larger mechanical response from a smaller field.