Metal-oxide material generates electromechanical stress an order of magnitude above existing materials.The ability to develop a mechanical stress in response to the application of an external electric field has many uses, and characteristic materials are classified as either piezoelectric or electrostrictive. Modern inorganic piezoelectric devices are used for a wide variety of applications from inexpensive speakers and headphones, to sophisticated sonar transducers. Over the last several decades, these materials have become highly reliable and technologically mature, but the magnitude of the mechanical stress they can generate in response to an input electric signal has reached an upper limit.This innovative technology applies Gadolinium-doped Cerium Oxide (Gd-doped CeO2) to piezoelectric and electrostrictive devices and will enable high-performance electromechanical materials with output capabilities an order of magnitude above existing solutions, in excess of 500 MPa. This could facilitate the next generation of many consumer and industrial electronic devices.
- Wide range of personal electronic devices
- Industrial and fine electronics specifically powerful acoustic transducers
- Generate large displacement and large stress simultaneously
- Sensitive and tunable properties
In piezoelectric devices, stress develops due to the deformation of a non-centrosymmetric lattice under the application of an electric field. In commercial electrostrictors, or materials with centrosymmetric lattices and very large dielectric constants, an external electric field distorts the unit cells of the lattice, rendering them locally non-centrosymmetric. In both cases, the electromechanical stress develops due to a small displacement of atoms within each unit cell. Increasing the magnitude of the response would lead to more powerful actuators, and permit a decrease in the operating voltage; therefore, the search for novel mechanisms of electromechanical response in solids remains an important objective for both fundamental and applied science.
We have demonstrated that Gd-doped CeO2, specifically Ce0.8Gd0.2O1.9, can generate stress an order of magnitude greater than the best electromechanically active materials. The large stress develops in response to the rearrangement of cerium-oxygen vacancy pairs and their local environment. This effect is expected to be two-fold; i) an applied electric field results in strain and stress directly, and ii) application of the external electric field affects the elastic modulus of Ce0.8Gd0.2O1.9 by suppressing the chemical strain effect. This is a fundamentally different mechanism than materials currently in use. In this view, Gd-doped CeO2 is representative of a new family of high-performance electromechanical materials.