Structure Property Relationship in BaTiO3–Na0.5Bi0.5TiO3–Nb2O5–NiO X8R System
A novel BaTiO3–Na0.5Bi0.5TiO3–Nb2O5–NiO (BT‐NBT‐Nb‐Ni) system that meets the X8R specification (−55°C–150°C, ΔC/C≤±15%) of multilayer ceramic capacitors (MLCCs) was fabricated, with a maximum dielectric constant of 2350 at room temperature (25°C). Core–shell microstructure was observed by transmission electron microscopy (TEM), accounting for the good dielectric temperature stability. The role of Ni on the formation of core–shell structure and phase structure, and the subsequent relationship between structure and dielectric/ionic conduction properties were investigated. It was observed that the addition of Ni could adjust the ratio of core/shell, and significantly reduces the dielectric loss over the studied temperature range. A new Ba11(Ni, Ti)28O66+x phase with a 10‐layer close‐packed structure was identified by X‐ray diffraction (XRD), serving as a source of oxygen vacancies for ionic conduction in addition to Ba(Ni,Ti)O3. Furthermore, the impedance spectroscopy measurements demonstrated the remarkable impact of these Ni‐induced oxygen vacancies on both the grain and grain‐boundary conductivities.
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Document Type: Research Article
Publication date: May 1, 2015