PbZrO3, and related solid solutions, as (PbZr,Ti)O3 with a small amount of Ti, show antiferroelectric behaviour, but they have also energetically available ferroelectric phases. The main lattice instabilities will be summarized (soft modes of seven different symmetries are present in the antiferroelectric phase of PbZrO3) and contextualized within a model where the coupling among them stabilize the antiferroelectric phase within a crystal which tends towards ferroelectricity. This model is supported by the effect of Ti in the PbZrO3 lattice, creating intermediate polar phases.
Crystals with ~1% of Ti show an intermediate polar phase with small thermal hysteresis. The way it develops across the crystal depends strongly on the defects present in the sample and the heating/cooling velocity. The antiferroelectric phase transition show stronger thermal hysteresis, which indicates its first order character. Regulating the heating/cooling velocity, it is possible to stop both phase transitions during its course within the sample. Raman measurements in different parts of the samples with different phases allowed to discern even different domain orientations in both, the intermediate phase and the antiferroelectric phase, coexisting in the sample.
Stronger cationic substitution of Zr by Ti induce other intermediate phases appear, showing a metastable behaviour hugely dependent of the experimental conditions.