Cold sintering co-firing of (Ca,Bi)(Mo,V)O4–PTFE composites in a single step

Abstract

Because of large differences in the processing temperature windows between ceramics and polymers, the single-step co-sintering of microwave dielectric ceramic–polymer substrates remains challenging. In this work, a dense (Ca0.65Bi0.35)(Mo0.65V0.35)O4 (CBMVO) ceramic was first prepared through cold sintering at 150°C, under a uniaxial pressure of 300 MPa for 60 min with Li2MoO4 (LMO) as a transient low-temperature solvent. Cold-sintered CBMVO–5 wt% LMO ceramic shows excellent microwave dielectric properties: εr ∼ 11.4, Q × f ∼ 7070 GHz, τf ∼ −7.4 ppm/°C. Moreover, the optimized cold sintering process enabled the preparation of a layered co-sintered (2–2 type) CBMVO–polytetrafluoroethylene composite, which maintained excellent microwave dielectric properties and showed a good heterogeneous interface bonding. The proposed cold sintering co-firing of ceramic–polymer composites in a single step shows great potential for application in the seamless integration between ceramics and polymer substrates.