Antiferroelectric materials for cooling and high power electronic applications

The unique electric field dependent dielectric and polarization properties make antiferroelectric materials potential candidates for high energy density capacitors, high power snubbers, and electrocaloric coolants. Despite their uniqueness, there is only one lead-based antiferroelectric high energy density capacitor on the market and the reason for this is the lack of understanding of the mechanisms and relations between the antiferroelectric coupling strength and externally applied electric field. The antiferroelectric coupling strength describes the interactions between the antiparallel sublattice polarizations and defines the properties of the electric field-induced phase transition and the polar state of antiferroelectric under the applied electric field. The properties of the field-induced phase transition govern the increase of the dielectric response with the electric field and energy storage properties. On the other hand, the polar state of antiferroelectric defines the dipolar entropy and consequently the origin of the inverse electrocaloric effect. In this proposal, we aim to investigate the relations between the functional properties of antiferroelectrics and antiferroelectric coupling strength. The results of the proposal will reveal the fundamental understanding of the origin of the inverse electrocaloric effect as well as the unique dielectric response. We will investigate the functional properties of the antiferroelectrics and their relation to the nature of the electric field-induced phase transition. By applying an external electric field, a first-order phase transition can be driven towards a second-order phase transition, i.e. critical point, where functional properties such as dielectric, piezoelectric, and electrocaloric coefficient diverge. Hence, if the system is operating in the vicinity of the critical point the electric field induced tunability of dielectric constant, energy storage and electrocaloric properties should be enhanced. Successful implementation of the project will provide a fundamental understanding of the underlying physical mechanisms responsible for the unique functional properties of antiferroelectrics, which is essential for developing new antiferroelectric materials that are needed for the emerging new green technologies