Novel ternary core-shell structure with microwave absorption properties and low infrared emissivity

Abstract

The development of functional materials with dual characteristics of microwave absorption and low infrared emissivity is vital for protection against magnetic-wave contamination. Currently, both microwave protection and infrared protection technologies are developing rapidly, but simultaneous integration of both has not been extensively investigated. Herein, a new ternary core-shell CoFe2O4@SiO2@ZAO composite dual-functional material was designed and fabricated. The process consisted of coating CoFe2O4 microspheres with ZAO based on SiO2 middle layer prepared through hydrolysis and sol-gel methods. The introduction of ZAO and SiO2 was found conducive to dielectric loss and impedance matching, thereby improving wave absorption. The nano-flower ZAO coating provided low infrared emissivity with a lamellar structure and high carrier concentration in the resulting ternary structure. The rise in ZAO content first enhanced the wave absorption of CoFe2O4@SiO2@ZAO and then decreased while the infrared emissivity declined. Among prepared samples, CoFe2O4@SiO2@ZAO exhibited a minimum reflection loss (RLmin) of −59.31 dB at 10.96 GHz, conducive to effective absorption bandwidth (EAB) of 4 GHz at 2 mm thickness with an infrared emissivity of 0.71 in 8–14 μm waveband. In sum, the novel CoFe2O4@SiO2@ZAO core-shell structure showed attractive properties in terms of compatibility of wave absorption and infrared emissivity, promising for future syntheses of dual-functional materials with improved performance.