Impact of PTFE particle size in designing BaTiO₃ dielectric composites under the cold sintering process

Abstract

The Cold Sintering Process (CSP) can provide opportunities to fabricate high-performance BaTiO3 dielectric composites with polymer materials that are typically difficult to impossible to co-process under a conventional sintering process. Therefore, we investigated the preparation process of BaTiO3 sintered body by CSP and integrated a well-dispersed intergranular polymer phase. In this study, we focused on preparing BaTiO3 and Polytetrafluoroethylene (PTFE) composites. We considered the importance of the particle size of the PTFE phase, and correlated the impact on the composite dielectric properties. Through fitting a general-mixing-law to the dielectric properties as a function of volume fraction, we could deduce more homogeneous composites obtained in using the 200 nm PTFE powders. In addition, the temperature dependent dielectric properties and field dependent conductivity of the composites was investigated. It was found that with the good dispersion of the PTFE can suppress the leakage current density in the dielectric composites.

BaTiO3-based composites provide new opportunities enabled by the cold sintering process

“…It was found that these materials could be sintered at low temperatures to an overall high density of ∼94% to 98% Recently, Nunokawa et al showed that with better mixing and dispersion of finer PTFE particles, BaTiO 3 PTFE composites with similar properties to the PPO composites could be realized. 32) The uniformity of the polymer is extremely important for obtaining a higher breakdown strength and time-dependent degradation resistance properties: like all mechanical or electric breakdown phenomena the fields can always find the weak points and therefore control the breakdown strength.…”

In situ observation of the multistep process of cold sintering

“…[33][34][35] Additionally, an undeniable advantage that cold sintering has over other novel sintering techniques 36 is that cold sintering can be used to process hard and soft materials together in one step in order to produce novel interfaces that improve properties like breakdown strength and device reliability. 9,37 Advances in cold sintering science will be accelerated by the ability to measure and monitor, in real-time, the evolution of complex interfaces and dissolution/precipitation interactions. 38 Currently, progress in these areas is complicated by processing materials in opaque dies.…”