High-performance FeSiAl SMCs for MHz applications enabled by insulating coatings of bioinspired NiZn ferrite nanoparticles

The exponential growth of artificial intelligence (AI) computational power has imposed more stringent demands on developing high-performance electronic components capable of operating efficiently at high frequencies. However, achieving high-frequency operation, enhanced power capacity, and miniaturization simultaneously in soft magnetic composites (SMCs) remains a formidable challenge. Traditional insulation coating approaches to improving the high-frequency performance of SMCs have been limited by difficulties in controlling coating thickness, susceptibility to decomposition during heat treatment, and magnetic dilution effects caused by non-magnetic insulating materials. This study addresses these limitations by introducing a novel biomineralization-inspired strategy to coat FeSiAl powders with NiZn ferrite nanoparticles. Inspired by the biomineralization in natural protein nanocages, we synthesized NiZn ferrite nanoparticles with uniform size distribution, exceptional monodispersity, and superparamagnetism through a confined mineralization strategy. The resulting NiZn ferrite/FeSiAl composites, prepared via mechanical mixing, exhibited an heterogenous insulation coating that significantly enhanced magnetic domain wall mobility and electrical resistivity compared to uncoated FeSiAl SMCs. Consequently, the FeSiAl/NiZn (FSA-NZ) SMCs demonstrated enhanced relative permeability, a high domain-wall resonance frequency, and remarkably low high-frequency power loss (944.8 mW/cm³ at 1 MHz/50 mT). This study bridges the gap between bioinspired materials engineering and high-frequency soft magnetic materials and provides a viable solution to the long-standing challenges in developing high-performance SMCs for MHz applications.