Materials with high electrostrictive response – BioWings
Structural optimization of CeO2 for enhanced electrostriction response
Electrostriction is the electromechanical response of dielectrics upon the application of external electric field. Materials with high electrostrictive response are widely used in sensing and actuating applications. Among various materials investigated, defective ceria based materials are of particular interest due to the high electrostriction coefficient (Me~10-18 m2 V-2), facile integration on silicon and biocompatibility. Understanding the underlying mechanisms is crucial for further optimizing the electromechanical performance of this class of materials.
The effect of crystallography direction
To date, only out-of-plane electrostriction coefficient has been measured, where the electric fields is applied in the out of plane direction. In this context, researchers from DTU Energy analysed the longitudinal and shear deformations in the in-plane directions for (100), (110) and (111) oriented Gd doped CeO2 (CGO) thin films epitaxially grown on various substrates. A systematic crystal distortion for different crystallographic directions reveal that, structural amplification along (100) direction of electrostriction by one order of magnitude.
The effect of order/disorder
Within disordered CGO, there are various energetically competitive configurations available. This would facilitate the atom rearrangements under external field and therefore large electrostrictive response can be expected. By controlling deposition temperature, oxygen partial pressure, film thickness, etc, CGO thin films with different degrees of disorder have been fabricated. The aim is to shed light on the effects of disorder on the macroscopic electrostrictive response.
Such fascinating concepts have already raised many interesting results in upcoming papers showing superior electromechanical performances.
1. S. Santucci, H. Zhang, S. Sanna, N. Pryds, V. Esposito, submitted.