Abstract
The paper reports new results on links “characteristics of heterophase structures − energy-storage parameters − unit-cell parameters behavior” in lead-free perovskite-type ferroelectric (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3-xGd2O3 ceramic (0 ≤ x ≤ 0.05). Heterophase structures, that contain large two-phase regions (tetragonal and rhombohedral) and thin interlayers (rhombohedral), are analyzed within the framework of a model at variations of volume fractions of specific non-180° domain types in the morphotropic phases. Complete stress relief in the heterophase structures at optimum volume fractions of the specific domain types in the tetragonal phase and interlayer is considered when interpreting the phase content, the difference between the maximum and remnant polarizations (Pmax− Pr determined from a hysteresis loop), as well as the coercive field Ec of materials at 0 ≤ x ≤ 0.05. The largest Pmax− Pr and smallest Ec values are achieved at x = 0.04, and for this composition, a unique equality of the volume fractions of certain domain types and the rhombohedral phase is described for the first time. The energy-storage parameters are discussed in the context of non-monotonic behavior of some unit-cell parameters of the ferroelectric phases at 0 ≤ x ≤ 0.05 and room temperature. The results shed light on the features of the coexistence of the morphotropic phases which influence characteristics of the hysteresis loop and contribute to improving a set of energy-storage parameters in advanced ferroelectric solid solutions.
Funding
1. Southern Federal University - 176/22-D