Abstract

In this study, we developed polymer-ceramic composites based on diglycidyl ether bisphenol A (DGEBA) epoxy resin reinforced with spinel ferrites, CoFe?O? (CFO) and MgFe?O? (MFO), aiming for advanced dielectric applications. The curing process was optimized using branched polyethyleneimine (BPEI) as a hardener, achieving an optimal 4:1 DGEBA: BPEI ratio at 100 °C for 1 h. Structural and morphological characterizations were performed using XRD, vibrating sample magnetometry (VSM), FTIR and SEM. Dielectric properties were investigated through impedance spectroscopy in the radiofrequency range (1–10 MHz) at temperatures from 100 to 200 °C, while microwave properties were analyzed in the X-band (8.2–12.4 GHz). All analyzed samples exhibited behavior that could be described by two R-CPE circuits. The composites were also evaluated in the microwave region, specifically in the X-band, where two absorption peaks were observed at around 11 and 11.9 GHz for the MFO10, MFO20, and CFO10 samples. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.