Effect of silica shell layer on the microstructural characteristics and dielectric properties of (Ba，Sr，Cu)TiO₃ ceramics

To explore the effect of concentration of silica shell on the structure and dielectric properties of barium strontium copper titanate ceramics, barium strontium copper titanate (BSCT) ceramic materials were prepared using the solid-state reaction method. The influence of varying silica (SiO₂) content on the crystal phase structure and dielectric properties of the BSCT ceramics were investigated. The XRD patterns showed that, compared with pure BSCT, the diffraction peaks of the BSCT@SiO₂ composite ceramics shifted to the right. This shift indicates that the incorporation of SiO₂ decreased the average ionic radius within the crystal lattice. Consequently, a more compact crystal structure was formed, contributing to an increase in the density of the ceramic material. The dielectric analysis demonstrated that SiO₂ content significantly impacts the electrical properties of the BSCT@SiO₂ ceramics. At low frequencies, the dielectric constant and loss decreased rapidly with increasing frequency due to the contributions of ionic conductivity, space charge polarization, and interfacial polarization. The ceramic with a SiO₂ content of 7.5% exhibited a higher dielectric constant and lower low frequency dielectric loss. This change primarily originates from alterations in the microstructure of the ceramic. Finite element analysis further suggests that optimizing the uniformity of the ceramic microstructure is crucial for achieving high-performance ceramics.