Theory of Antiferroelectric Crystals

TLDR

An antiferroelectric state features spontaneously polarized ion lines that are antiparallel to neighboring lines. The study investigates the dielectric constant across the antiferroelectric Curie point for both first‑ and second‑order transitions. The study finds that in simple cubic lattices the antiferroelectric state is more stable than the ferroelectric state, that the dielectric constant need not be high and is continuous across a second‑order Curie point, that the state is not piezoelectric, that the thermal anomaly at the Curie point mirrors that of ferroelectrics, and that a C/(T+θ) susceptibility variation does not signal antiferroelectricity.

Abstract

An antiferroelectric state is defined as one in which lines of ions in the crystal are spontaneously polarized, but with neighboring lines polarized in antiparallel directions. In simple cubic lattices the antiferroelectric state is likely to be more stable than the ferroelectric state. The dielectric constant above and below the antiferroelectric curie point is investigated for both first- and second-order transitions. In either case the dielectric constant need not be very high; but if the transition is second order, $\ensuremath{\epsilon}$ is continuous across the Curie point. The antiferroelectric state will not be piezoelectric. The thermal anomaly near the Curie point will be of the same nature and magnitude as in ferroelectrics. A susceptibility variation of the form $\frac{C}{(T+\ensuremath{\theta})}$ as found in strontium titanate is not indicative of antiferroelectricity, unlike the corresponding situation in antiferromagnetism.