Metal–Organic Framework‐Manipulated Dielectric Genes Inside Silicon Carbonitride toward Tunable Electromagnetic Wave Absorption

Abstract Heterointerface engineering for different identifiable length scales has emerged as a key research area for obtaining materials capable of high‐performance electromagnetic wave absorption; however, achieving controllable architectural and compositional complexity in nanomaterials with environmental and thermal stabilities remains challenging. Herein, metal‐containing silicon carbonitride (SiCN/M) nanocomposite ceramics with multiphase heterointerfaces were in situ synthesized via coordination crosslinking, catalytic graphitization, and phase separation processes using trace amounts of metal–organic frameworks (MOFs). The results reveal that the regulation of dielectric genes by MOFs can yield considerable lattice strain and abundant lattice defects, contributing to strong interfacial and dipole polarizations. The as‐prepared SiCN/M ceramics demonstrate excellent microwave absorption performance: the minimum reflection loss (RL min ) is −72.6 dB at a thickness of only 1.5 mm and −54.1 dB at an ultralow frequency of 3.56 GHz for the SiCN/Fe ceramics and the RL min is −55.1 dB with a broad bandwidth of 3.4 GHz at an ultralow thickness of 1.2 mm for the SiCN/CoFe ceramic. The results are expected to provide guidance for the design of future dielectric microwave absorption materials based on heterointerface engineering while offering a paradigm for developing MOF‐modified SiCN nanocomposite ceramics with desirable properties.