Highly Reliable BaTiO3‐Polyphenylene Oxide Nanocomposite Dielectrics via Cold Sintering

Abstract In the design of the ceramic capacitor, high capacitance, temperature stability, and high operating voltage must be balanced against the failure mechanisms of degradation. Cold sintering is used to develop dense BaTiO 3 – poly (p‐phenylene oxide) (PPO) nanocomposites with PPO throughout the grain boundary microstructure. To obtain the desired PPO distribution, a process is introduced that distributes the polymers on the BaTiO 3 powders prior to the cold sintering process. With the cold sintering enabled by a Ba(OH) 2 ·8H 2 O transient phase, theoretical densities ≈95% could be obtained at a sintering temperature ≈225 °C with up to 15 vol% PPO content. The rationale is to influence the local electric field distribution within the dielectric, to maximize resistivity (10 13 –10 14 Ω cm) and degradation resistance, minimize temperature dependence of permittivity, and minimize the field dependent permittivity. All these properties are investigated as a function of the volume fraction of PPO. The magnitude of the permittivity follows a logarithmic mixing law: 1460 to 680 for the nanocomposite with 5 to 15 vol% PPO content, respectively, at room temperature. The BaTiO 3 ‐PPO composite dielectrics are contrasted under accelerated lifetime testing conditions, noting superior resistance toward degradation kinetics, indicating an important breakthrough opportunity towards the development of high reliability dielectrics.