Materials
with strong magnetic property that can provide excellent microwave
absorption performance are highly desirable, especially if their dielectric
and magnetic properties can be easily modulated, which make minimal
thickness and ultrawide bandwidth become achievable. The magnetic
properties of ferromagnetic (FM) and antiferromagnetic (AFM) composite
materials are closely related to their ratio of composition, size,
morphology, and structure. AFM–FM composites have become a
popular alternative for microwave absorption; however, the controllable
design and preparation need to be urgently optimized. Here, we have
successfully prepared a series of platelike NiO–Ni composites
and demonstrated the potential of such composites for microwave absorption.
Strong magnetic coupling was found from NiO–Ni nanoparticles
by electron holography, which makes NiO–Ni composites a highly
efficient microwave absorber (strong reflection loss: −61.5
dB and broad bandwidth: 11.2 GHz, reflection loss < −10
dB). Our findings are helpful to develop a strong microwave absorber
based on magnetic coupling
