Ba(Fe0.5Nb0.5)O3@SiO2 core-shell structures with low dielectric loss over a broad frequency and temperature by aqueous chemical coating approach

To decrease the dielectric loss over a broad temperature and frequency of Ba(Fe0.5Nb0.5)O3 (BFN) ceramics, the core-shell structure of Ba(Fe0.5Nb0.5)O3@SiO2 (BFN@SiO2) particles were successfully prepared by aqueous chemical coating approach, which still remains in the final ceramics. The mechanism of coating BFN with SiO2 is also analyzed. The BFN@SiO2 sample shows good frequency and temperature stability on dielectric constant and the dielectric loss is significantly decreased. The low tan δ is related to the homogeneous fine grains and the insulating grain boundaries of BFN@SiO2 ceramics. The improved temperature stability in BFN@SiO2 ceramics is a competing balance result of the low and high temperature dielectric relaxations. The enhancement resistance of grain boundaries plays a key role to reduce the dielectric loss of the BFN@SiO2 ceramics. The XPS analysis confirms the blocking function of insulating SiO2 shell on loss of the oxygen and matter transfer.