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

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 decomposition of any phases. In this study, we considered the co-sintering of BaTiO3 powders with polytetrafluoroethylene (PTFE) in the grain boundaries. We examined 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 J-t curves, were conducted, the reliability improved by using fine powders of PTFE with controlled mixing.