Ferroelectricity at the extreme thickness limit in the archetypal antiferroelectric PbZrO3
Not Available
Maity, Nikhilesh↗
Engineering topics
Ponomareva, Inna
Publications and source records attributed to Ponomareva, Inna.
Enhanced Piezoelectric Response at Nanoscale Vortex Structures in Ferroelectrics
Not Available
42 ENGINEERING↗
Ferrielectricity in the Archetypal Antiferroelectric, PbZrO 3
Antiferroelectric materials, where the transition between antipolar and polar phase is controlled by external electric fields, offer exceptional energy storage capacity with high efficiencies, giant electrocaloric effect, and superb electromechanical response. PbZrO 3 is the first discovered and the archetypal antiferroelectric material. Nonetheless, substantial challenges in processing phase pure PbZrO 3 have limited studies of the undoped composition, hindering understanding of the phase transitions in this material or unraveling the controversial origins of a low-field ferroelectric phase observed in lead zirconate thin films. Here, leveraging highly oriented PbZrO 3 thin films, a room-temperature ferrielectric phase is observed in the absence of external electric fields, with modulations of amplitude and direction of the spontaneous polarization and large anisotropy for critical electric fields required for phase transition. The ferrielectric state observations are qualitatively consistent with theoretical predictions, and correlate with very high dielectric tunability, and ultrahigh strains (up to 1.1%). This work suggests a need for re-evaluation of the fundamental science of antiferroelectricity in this archetypal material.
36 MATERIALS SCIENCE↗
Phase Switching as the Origin of Large Piezoelectric Response in Organic-Inorganic Perovskites: A First-Principles Study
Piezoelectrics are critical functional components of many practical applications such as sensors, ultrasonic transducers, actuators, medical imaging, telecommunications. So far, the best performing piezoelectrics are ferroelectric ceramics, many of which are toxic, heavy, hard, and cost-ineffective. Recently, a groundbreaking discovery of extraordinarily large piezoelectric coefficients in the family of organic-inorganic perovskites gave a hope for a cheaper, environmentally friendly, inexpensive, light-weight and flexible alternative. However, the origin of such response in organic-inorganic ferroelectrics whose spontaneous polarization is an order of magnitude smaller than for inorganic counterparts remains unclear. In this study we employ first-principles simulations to predict that the mechanism associated with large piezoelectric constants is of extrinsic origin and associated with switching between the stable phase and previously overlooked energetically competitive metastable phase that can be stabilized by the external stress. Here, the phase switching changes the polarization direction and, therefore, gives origin to large piezoelectric response, similar to PbZr$_{1-x}$Ti$_x$O$_3$ near morphotropic phase boundary. Existence of such metastable phases is likely to manifest as the dynamical molecular disorder above the Curie temperature and, therefore, could be intrinsic to the entire family of organic-inorganic ferroelectrics with such disorder.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Fundamental Physics of Ferroelectrics 2019
The workshop “Fundamental Physics of Ferroelectrics 2019” took place in January 2019 at USF and hosted around 80 participants (from both US and overseas) 32 of whom were early career professionals (PostDocs and graduate students). This was a 2.5 day workshop with 8 invited presentations, 39 oral presentations, and 27 posters. It brought together experts in the area of ferroelectrics and related materials and allowed for interactions, collaborations and exchange of ideas and progress. The invited speakers were Jorge Iniguez (University of Luxembourg), Manila Songvilay (University of Edinburgh), James Scott (St. Andrews), David Singh (University of Missouri), Philippe Ghosez (Université de Liège), Marin Alexe (University of Warwick), Takeshi Egami (University of Tennessee), Sergey Vakhrushev (Ioffe Physical Technical Institute), and Karin Rabe (Rutgers University). The DOE funding was used (i) to provide awards for junior participants (graduate students and PostDocs): best oral presentations (1st, 2nd and 3rd places) and best poster presentations (1st, 2nd and 3rd places). First places in both categories $\$ $300, second places in both categories $\$ $250 and third places in both categories $\$ $200. Information about the awardees available at the conference website.
36 MATERIALS SCIENCE↗