Ferrielectric lead zirconate

Lead zirconate (PbZrO3) was the first material identified as antiferroelectric, shortly after the concept of antiferroelectricity was proposed in the 1950s. Not only that, it is considered the prototypical antiferroelectric perovskite. Yet, many experimental works on this compound hint at uncompensated dipoles in this compound, which would correspond to a ferrielectric phase. We build one of the simplest ferrielectric phases one can imagine for PbZrO3, and, to our surprise, first-principles calculations reveal this phase to be more stable than the usual antiferroelectric phase! By studying the phase stability as a function of temperature, we find that the ferrielectric phase could even be the most stable at ambient conditions. There might even be other phases with more complex (uncompensated) dipole arrangements that show an even greater stability.