Microstructure effects on the energy storage density in BiFeO3-based ferroelectric ceramics

Lead-free BiFeO3-BaTiO3-Bi(Mg2/3Nb1/3)O-3 (BFBT-BMN) ceramics with different grain sizes were fabricated by using a conventional solid-state reaction. The high-energy ball milling technique was utilized to obtain the fine-grained ceramics. The grain size reduction lowers the remanent polarization (P-r) and enhances the dielectric breakdown strength (E-b) leading to a drastic increase of the recoverable energy storage density (W-re). For the fine-grained BFBT-BMN ceramics, W-re greatly increases by 8 times from 0.16 J/cm(3) to 1.27 J/cm(3), compared to the coarse-grained BFBT-BMN ceramics. Transmission electron microscopy (TEM) and piezo-response force microscopy (PFM) measurements revealed the occurrence of the polar nanoregions (PNRs) in the fine-grained BFBT-BMN ceramics. The dynamic and weakly correlated PNRs structure is responsible for the enhancement of recoverable energy storage density in the fined-grained BFBT-BMN ceramics. This work indicates that the grain size reduction is an effective way to modify the energy storage properties of BiFeO3-based ferroelectric ceramics.

Automated summary

Lead-free BiFeO3-BaTiO3-Bi(Mg2/3Nb1/3)O-3 (BFBT-BMN) ceramics with different grain sizes were fabricated using high-energy ball milling technique. The reduction in grain size leads to an increase in recoverable energy storage density and the presence of polar nanoregions, enhancing the energy storage properties of the ceramics. Transmission electron microscopy revealed the dynamic and weakly correlated polar nanoregions structure in the fine-grained ceramics, contributing to the significant enhancement of energy storage density.