Constructing a 3D interlinked network with magnetic/dielectric loss and electron/phonon co-transfer in MgO@Ni@C and MgO@Ni@CNT foams for low loads and prominent thermal/electromagnetic performance

Abstract

Currently, most existing electronic packaging materials are not efficient enough to be widely utilized due to their high load and incompatibility between heat conductivity (HC) and electromagnetic wave absorption properties (EMWAPs). In response to this, the present study adopts a one-step combustion method to develop MgO@Ni@C and MgO@Ni@CNT foams as advanced multifunctional fillers. The hybrid foams are porous and magnetic, which is related to in-situ generated gas bubbles. By modulating the Ni2+ molar content (φ), combustion temperature (Tc), and C types, the products can achieve a low load with a simultaneous enhancement in HC and EMWAPs. Our results show that the MgO@Ni@C foams formed at φ = 30 mol% and Tc = 800 °C exhibit exceptional HC and EMWAPs (HC = 3.83 W/m⋅K, EABW/d (the ratio of effective absorption bandwidth to thickness) = 5.48 GHz/mm, RLmin = − 59.75 dB, and load = 30 wt%). The MgO@Ni@CNT foams with a dual 3D interlinked network bear a high HC (3.94 W/m⋅K, 5 wt% load) and a large EABW/d (4.0 GHz/mm, 20 wt% load). The increased HC is related to low phonon-scattering, prolonged mean free paths, and continuous phonon/electron co-transfer paths resulting from low defects, small SBET, moderate Ni0, and 3D interlinked network. The improved EMWAPs are credited to high attenuation and matching performance caused by ferromagnetic/exchange resonances, various polarizations, and multiple scattering. Notably, the comprehensive properties of MgO@Ni@C and MgO@Ni@CNT foams are superior to those of other previously reported fillers, suggesting that they can be extensively applied as multifunctional materials in electronic devices.