Dielectric properties and microstructure of BaTiO3-PTFE composites via cold sintering process

• Published in: Japanese Journal of Applied Physics Vol. 63; no. 8; pp. 08SP02 - 17
• Main Authors: Nunokawa, Takashi, Takashima, Kenji, Mizuno, Kotaro, Randall, Clive A.
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.08.2024; Japanese Journal of Applied Physics
• Subjects: Barium hydroxide; Barium titanates; BaTiO; Chemical reactions; Cold; Cold pressing; Cold sintering; cold sintering process; Composite materials; composites; Decomposition reactions; dielectric material; Dielectric properties; Electrical resistivity; Grain boundaries; Low temperature resistance; Metal powders; Metallurgical constituents; Microstructure; Phases; Polytetrafluoroethylene; Reliability; Sintering; Sintering (powder metallurgy); Thickness
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/ad6776

The cold sintering process is capable of densifying ceramics and metal powders with other phases into composite materials without inducing chemical reactions between the constituent phases or causing the decomposition of any phases. In this study, we considered the co-sintering of BaTiO3 powders with polytetrafluoroethylene (PTFE) in the grain boundaries. We examined the microstructure and dielectric properties of these composites with different volume fractions of PTFE. The composites were highly dispersive from microstructure and general mixing laws, due to using fine PTFE. Transmission electron microscopy studies demonstrated that the thickness of the PTFE in the grain boundaries was determined with different volume fractions of PTFE. The cold-sintered BaTiO3 composites had high volume resistivity (>1011 Ω·cm), enhancing the resistivity of the cold-sintered pure BaTiO3 using Ba(OH)2·8H2O transient phase. Reliability tests, such as breakdown strength, and Jt curves, were conducted, and the reliability was improved by using fine powders of PTFE with controlled mixing.