Microstructure and dielectric properties of BaTiO3 ceramic doped with yttrium, magnesium, gallium and silicon for AC capacitor application

• Y-Mg-Ga-Si co-doped BaTiO3 ceramics with core-shell structure were prepared.
• Y3+, Mg2+, and Ga3+ dissolved in the lattice BaTiO3 replacing Ba2+ site or Ti4+ site.
• Y3+ and Ga3+ tended to remain close to the grain boundaries as a shell maker.
• Y-Mg-Ga-Si co-doped BaTiO3 ceramics show high AC breakdown voltage and low tanδ.

The microstructures and dielectric properties of Y-Mg-Ga-Si co-doped barium titanate ceramics were investigated. Y3+ dissolved in the lattice of BaTiO3 replacing both Ba2+ site and Ti4+ site, and Mg2+ replaced Ti4+ site. The replacements of Y3+ and Mg2+ inhibit the grain growth, cause tetragonal-to-pseudocubic phase transition, reduce the dielectric loss, and flatten the temperature dependence of capacitance curve. The incorporation of Ga3+ can improve sintering and increase permittivity. Y3+ and Ga3+ tended to remain close to the grain boundaries, and play an important role as a shell maker in the formation of the core–shell structure in the co-doped BaTiO3 ceramics. Excellent dielectric properties: ϵr = ∼2487, tanδ = ∼0.7% (at 1 kHz), ΔC/C25 < ∼6.56% (from −55 °C to 125 °C) and alternating current breakdown voltage E < ∼4.02 kV/mm can be achieved in the BaTiO3–0.02Y2O3–0.03MgO–0.01Ga2O3–0.005SiO2 ceramics sintered at 1380 °C. This material has a potential application in alternating current multilayer ceramic capacitor.

Core–shell structure can be obtained in BaTiO3 ceramics co-doped with Y–Mg-Ga-Si. Y-Mg-Ga-Si co-dopant can obviously reduce dielectric loss, improve AC breakdown voltage and flatten temperature dependence of capacitance curve.Figure optionsDownload as PowerPoint slide