Confirmed ferroelectric performance of Ba(Fe0.5Nb0.5)O3@SiO2 core-shell heterostructure with lower dielectric loss

- The core-shell structured Ba(Fe0.5Nb0.5)O3@SiO2 were successfully prepared.
- The dielectric loss decreased significantly with coating SiO2 layer.
- The ferroelectricity of BFN ceramics were further confirmed.
- The insulating grain boundary plays a key role to the decrease of dielectric loss.

The ferroelectric performance of Ba(Fe0.5Nb0.5)O3 (BFN) ceramics is still controversial due to their large leakage loss. In this paper, we prepared core-shell structured Ba(Fe0.5Nb0.5)O3@SiO2 particles via a wet chemistry coating method, and the core-shell structures still remain in the sinterred ceramics. Compared with pure BFN ceramic, BFN@SiO2 composite ceramic shows dramatically suppressed dielectric loss and ac conductivity, especially measurable hysteresis loop. Through further analysis in detail, the ferroelectricity of BFN ceramics can be confirmed due to the decreased leakage loss. In addition, the internal relaxation behavior of BFN@SiO2 samples is still consistent with pure BFN ceramics, and the impedance complex plane analysis indicated that the insulating grain boundary (or internal barrier) plays a key role to the dielectric loss decrease of the BFN ceramics.