Effects of Sc2O3 and MgO additions on the dielectric properties of BaTiO3-based X8R materials

In the present study, dielectric formulations compatible with the base-metal electrode process, using a host material (BaTiO3 + 0.05 mol% MnCO3 + 1.37 mol% BaSiO3) with 0.3-0.6 mol% Sc2O3 and 0-2.0 mol% MgO, were examined. The addition of Sc2O3 and MgO led to the formation of a grain core-shell structure and therefore gave rise to temperature-stable dielectric properties, while the TEM and EDS results revealed the chemical inhomogeneity of the Sc3+ ions across the grains. The Sc2O3 content played an important role in the reducing the dielectric constant (K), improving the electrical resistivity, and flattening the TCC curve of the ceramics by inhibiting grain growth. Meanwhile, the existence of MgO was proven to enhance the densification, affect the room-temperature electrical resistivity, reduce the tanδ value, and improve the TCC value at - 55 °C. The optimum formulation derived in the present study involved adding 0.45 mol% Sc2O3 and 1.0 mol% MgO to the host material. This yielded the following dielectric properties: K = 1,744, tanδ = 0.58%, TCC = - 3.9% (- 55 °C) and - 8.5% (150 °C), and electrical resistivity = 2.8 × 1012 Ω cm (25 °C) and 1.7 × 1011 Ω cm (150 °C). These dielectric properties satisfied the requirements of the EIA-X8R specification, thus validating the material's potential for application to commercial capacitors.