Microstructural Origin of the High-Energy Storage Performance in Epitaxial Lead-Free Ba(Zr(0.2)Ti(0.8))O(3) Thick Films

In our previous work, epitaxial Ba(Zr(0.2)Ti(0.8))O(3) thick films (~1–2 μm) showed an excellent energy storage performance with a large recyclable energy density (~58 J/cc) and a high energy efficiency (~92%), which was attributed to a nanoscale entangled heterophase polydomain structure. Here, we propose a detailed analysis of the structure–property relationship in these film materials, using an annealing process to illustrate the effect of nanodomain entanglement on the energy storage performance. It is revealed that an annealing-induced stress relaxation led to the segregation of the nanodomains (via detailed XRD analyses), and a degraded energy storage performance (via polarization-electric field analysis). These results confirm that a nanophase entanglement is an origin of the high-energy storage performance in the Ba(Zr(0.2)Ti(0.8))O(3) thick films.