Piezoelectrics are materials that linearly deform in response to an applied electric field. As a fundamental prerequisite, piezoelectric materials must have a noncentrosymmetric crystal structure. For more than a century, this has remained a major obstacle for finding piezoelectric materials. We circumvented this limitation by breaking the crystallographic symmetry and inducing large and sustainable piezoelectric effects in centrosymmetric materials by the electric field–induced rearrangement of oxygen vacancies. Our results show the generation of extraordinarily large piezoelectric responses [with piezoelectric strain coefficients ( d 33 ) of ~200,000 picometers per volt at millihertz frequencies] in cubic fluorite gadolinium-doped CeO 2− x films, which are two orders of magnitude larger than the responses observed in the presently best-known lead-based piezoelectric relaxor–ferroelectric oxide at kilohertz frequencies. These findings provide opportunities to design piezoelectric materials from environmentally friendly centrosymmetric ones.

Self-assembly of supramolecular biomaterials such as proteins or peptides has revealed great potential for their use in various applications ranging from scaffolds for cell culture to light-emitting diodes and piezoelectric transducers. Many of these applications require controlled growth of individual objects in the configuration allowing simple transfer to the desired device. In this work, we grew millimeter-long diphenylalanine (FF) self-assembled microtubes with high aspect ratio via evaporation-driven crystallization of nonsaturated FF solutions, making use of the Marangoni flow in the drying droplets. The growth mechanism was investigated by measuring the microtube length as a function of time. Jerky (steplike) growth behavior was observed and explained by a self-activated process in which additional activation energy is provided through condensation. The calculated growth rate due to the diffusion-controlled process is in agreement with the experimentally measured values. The grown microtubes were successfully transferred to metallized patterned substrates, and their specific conductivity and piezoelectric properties were evaluated as a function of the applied voltage and frequency. A number of piezoelectric resonances were observed and attributed to different vibrational modes excited by the piezoelectric effect inherent to the FF structure.

Electrostriction is a property of all the dielectric materials where an applied electric field induces a mechanical deformation proportional to the square of the electric field. The magnitude of the effect is usually minuscule. However, recent discoveries of symmetry-breaking phenomena at interfaces opens up the possibility to extend the electrostrictive response to a broader family of dielectric materials. 1,2 Here, we engineer the electrostrictive effect by epitaxially depositing alternating layers of

No abstract

No abstract