A Developed Approach for Synthesizing Novel Fe₃O₄/FeO/BaCl₂ Composites with Broadband and High-Efficiency Microwave Absorption Performance

Designing high-performance microwave absorbing materials that are thin and exhibit strong absorption capabilities across a wide frequency range is critical for mitigating electromagnetic pollution through a simple, highly adaptable, and cost-effective approach. However, achieving these three targets remains a significant challenge. In this research a simple approach suitable for large-scale production of microwave absorbing materials, namely, Fe₃O₄/FeO/BaCl₂ composites, is proposed, which includes the processes of chemical coprecipitation and calcination. The above approach can adjust the mass ratio of Fe₃O₄/FeO while prompt the formation of BaCl₂ with mesoporous structure on the surface of Fe₃O₄/FeO, meeting the need for desirable microwave absorbing performance. Subsequently, the impacts of varying mass ratios of the Fe₃O₄/FeO/BaCl₂ composites on microstructures, magnetic properties, and microwave absorption properties were examined. Based on this investigation, a mass ratio close to 3.5:5.5:1 was determined to be optimal. At this ratio, the Fe₃O₄/FeO/BaCl₂ composites realize an effective absorption bandwidth of 6.70 GHz at only 1.16 mm thickness, covering the whole Ku-band, and the maximum reflection loss can be close to −46.8 dB at 1.4 mm. The robust microwave absorption performance of Fe₃O₄/FeO/BaCl₂ composites can be attributed to heterostructured multi-interface structural design, the comprehensive effects of multiple reflections and dielectric/magnetic losses induced by BaCl₂ with mesoporous structure as well as the aggregated Fe₃O₄/FeO particles. This work may offer insights into designing and preparing effective microwave absorption materials.