Anti-Ferroelectric Ceramics for High Energy Density Capacitors

Abstract

With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE) display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

Keywords: anti-ferroelectric; bulk ceramics; capacitor; energy storage.

Figure 1

Figure represents the typical polarization versus electric field (P-E) hysteresis loops and energy storage characteristics of the four classes of solid dielectric materials namely (a) linear; (b) ferroelectric; (c) relaxor ferroelectric; (d) anti-ferroelectric (demonstration only; not to scale).

Figure 2

Graphical representation of the mechanism and various switching directions associated with different crystallographic structures under (a) ferroelectric; (b) ferroelastic domain rotation, respectively.

Figure 3

Graphical representation for the technique of physical confinement to increase the energy storage density in anti-ferroelectric materials. (a) Displays how the hysteresis loop changes to yield enhanced recoverable energy under uniaxial compressive stress while (b) displays P-E hysteresis loops for (Pb_0.96La_0.04)(Zr_0.90Ti_0.10)O₃ material under compressive loading [88].

Figure 4

Graphical representation of anti-ferroelectric ceramics’ cross-sectional view of (a) completely electroded ceramic; (b) half electroded ceramic (green is electrode (hatched), purple is ceramic); and (c) P-E hysteresis loops for of Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_1−yTi_y]_0.98O₃ material under induced self-confinement. Data adapted from [47].

Figure 5

The effect of internal clamping at a microscopic level due to glass incorporation, in anti-ferroelectric material for (a) pure ceramic; (b) ceramic with glass incorporation; (c) pure ceramic under electric field; and (d) glass-ceramic composite under electric field and their domain behavior; (e) P-E hysteresis loops for Pb_0.97La_0.02(Zr_0.56Sn_0.35Ti_0.09)O₃ glass ceramic composite [60].

Figure 6

P-E hysteresis loops of the Nb modified 95/5 PbZrTiO₃ bulk ceramics, obtained as a function of hydrostatic pressure at the temperatures of (a) 25 °C; (b) 125 °C. Data adapted from [108].

Figure 7

Energy storage density of Nb modified 95/5 PbZrTiO₃ bulk ceramics as a function of operating temperature and applied hydrostatic pressure. Data adapted from [108].