Improvement of magnetoelectric properties of 1-3-type PVDF-based flexible composite films based on size effect

Flexible CoFe₂O₄/polyvinylidene fluoride (CFO/PVDF) composite films were fabricated via a casting technique using CFO particles synthesized hydrothermally with varying holding times. The effects of CFO particle size on phase composition, microstructure, mechanical behavior, and magnetoelectric properties of the films were systematically investigated. The CFO particles were uniformly dispersed within the PVDF matrix. As particle size increased, the composite surface became smoother and more continuous. With a 2 h holding time, corresponding to a CFO size of 7.48 × 0.59 μm, the film exhibited the highest magnetodielectric coefficient (5.22%) and a magnetoelectric coupling coefficient of − 8.98 V/(cm Oe). In contrast, CFO/PVDF-1 h films, containing CFO particles sized 5.37 × 0.50 μm, achieved maximum tensile strength (497.39 N/mm²) and elongation at break (23.40%), indicating superior mechanical performance. These findings highlight the critical role of CFO particle size in tuning the functional properties of the composite films. The CFO/PVDF composites demonstrate both enhanced magnetoelectric coupling and mechanical robustness, suggesting their potential for application in flexible electronics and multifunctional sensing devices.