Microwave Attenuation Research Articles

2D patterned magnetic composite sheets for polarization-insensitive and wide-angle microwave attenuation

Magnetic composite sheets loaded with carbonyl iron powders (CIP) are widely used due to their high-efficiency microwave attenuation at very thin thickness because of their outstanding permeability and magnetic loss. However, their performance varies dramatically at various incident angles and polarization modes, namely transverse electric (TE) and transverse magnetic (TM) modes. In this study, it is demonstrated that two-dimensional (2D) patterning could offer an effective solution for achieving wide-angle performance in both TE and TM modes. Different shapes of the 2D patterns (circles, hexagons, and cross-holes) are investigated and their dimensions are optimized through full-wave simulation. The consistent results with the experiment reveal that these 2D patterns with optimized dimensions could improve TM mode performance significantly to above 20 dB attenuation for an oblique incident angle up to about 40°, thanks to the resulted field resonance revealed by simulation. Due to the improved TM mode performance, the patterned composite sheet could exhibit almost identical high-efficiency attenuation in both modes, becoming polarization-insensitive. The performance improvement also comes with a ∼16% reduction in weight. Given these merits and the ease of fabrication, the low-profile and robust 2D patterned magnetic composite sheets could attract great attenuation in practical applications for wide-angle and polarization-insensitive microwave attenuation.

Toward high performance microwave absorber by implanting La0.8CoO3 nanoparticles on rGO

The advent of “intelligent era” brings our life more convenience, but the electromagnetic radiation surrounding us not only greatly threatens human health, also makes information leakage and hidden trouble to national defense security. Hence, it is very urgent to develop novel electromagnetic wave absorption materials with lightweight, strong absorption, tunable absorption frequency and broad band absorption. Herein, a novel electromagnetic wave absorber is obtained by constructing La0.8CoO3-rGO nanocomposite, where La0.8CoO3 nanoparticles are anchored on graphene nanosheets by the electrostatic interaction between GO and La0.8CoO3. The effect of hybridization ratio of La0.8CoO3 and rGO on microwave absorption properties is carefully studied. The optimal reflection loss of La0.8CoO3-rGO nanocomposite can reach -62.34 dB with the maximum effective bandwidth of 6.08 GHz, presenting 48.78% and 245.45% increment compared to bare La0.8CoO3 nanoparticles, respectively. The effective absorption bandwidth covers a broad electromagnetic wave absorption band from Ku band to the C band by tailoring thickness of the absorbers from 2.4 mm to 4.4 mm. The fascinating electromagnetic wave absorption performance is attributed to the synergy effect of La0.8CoO3 and rGO, which integrates magnetic and dielectric loss caused by resonance, conductance, relaxation, and scattering loss. This result confirms that La0.8CoO3-rGO nanocomposite is potential candidates toward high-efficiency microwave absorbers and provides a valuable pathway for designing high-performance microwave attenuation materials in the future.

Enhanced microwave absorption of g-C3N4/poly(vinylidene difluoride)/carbon black composites

The two-dimensional (2D) nanostructures have been widely applied as microwave absorption materials due to their unique structural features towards electromagnetic wave absorption. Herein, we have prepared graphitic carbon nitride (g-C3N4) nanosheets with a facile synthesis process, and then it was composited with a minimal amount of polyvinylidene difluoride (PVDF) and carbon black (CB) to enhance the microwave attenuation of g-C3N4 and to present an eco-friendly and cost-effective microwave absorbing material (MAM) as g-C3N4/PVDF/CB. The designed g-C3N4/PVDF/CB composite delivers a maximum return loss of −30.93 dB at 11.44 GHz, corresponding to an absorption efficiency of over 99.92%, with an average return loss of −17.29 dB. However, the dielectric performances were also elucidated with independent contributions of dielectric constant, tangent loss, and conductivity towards the microwave absorption performances. The integration of absorption medium PVDF and conductive medium CB to g-C3N4 offers the excellent absorption ability of g-C3N4/PVDF/CB. Hence, in the exploration of new MAM, g-C3N4/PVDF/CB may be an attractive microwave-absorbing material with strong dielectric parameters and excellent absorption effects.

Ambient Synthesis of Metal–Organic Framework-Derived Bimetallic Layered Double Hydroxide Nanosheets by the Composition Inheritance Strategy for Efficient Microwave Attenuation Applications

Ambient Synthesis of Metal–Organic Framework-Derived Bimetallic Layered Double Hydroxide Nanosheets by the Composition Inheritance Strategy for Efficient Microwave Attenuation Applications

Fe3O4 incorporated geopolymer nanocomposites for microwave absorption: Role of size, structure, and dispersion

The demand for sustainable construction materials with outstanding microwave absorbing properties is essential to provide comprehensive protection against the harmful effects of electromagnetic (EM) radiation. Herein, a series of Fe3O4-based materials with similar shapes, including Fe3O4 nanospheres with average sizes of 10 nm (Fe3O4-10) and 400 nm (Fe3O4-400) and hollow Fe3O4 nanospheres with an average size of 400 nm (H-Fe3O4-400), were synthesized. SiO2 was coated on the surface of Fe3O4-based materials. Geopolymer (GP) nanocomposites containing different Fe3O4-based materials were prepared. The roles of the size, structure, and dispersion of Fe3O4-based materials on the microwave absorption and compression properties of GP nanocomposites were comprehensively explored. Owing to the hollow structure and heterointerface formed, GP nanocomposites containing H-Fe3O4-400 displayed outstanding microwave absorption performance with a minimum reflection loss (RLmin) of −39.3 dB at 2.2 mm and an effective absorption bandwidth (EAB) of 4.8 GHz. More importantly, radar cross section (RCS) simulation was conducted to demonstrate the outstanding microwave attenuation capability of H-Fe3O4-400/GP nanocomposites in a real service environment. The results showed that the performance of GP nanocomposites was more competitive than that of other similar microwave absorbing construction materials. Furthermore, the compression tests showed that the introduction of H-Fe3O4-400 decreased the compressive strength of the GP nanocomposites from 37.87 to 31.62 MPa, while the presence of SiO2 enhanced interfacial load transfer, increasing the compressive strength to 37.16 MPa. The overall results validated that the as-prepared GP nanocomposites can be a potential candidate for use in construction areas where microwave absorption is essential.

Controllable synthesis of diamond/graphite composite films with tunable dielectric properties for microwave attenuation

Diamond/graphite composite films with tunable dielectric properties were prepared by microwave plasma chemical vapor deposition. The effect of methane flow rate on the morphology, phase composition, electric conductivity and dielectric properties of the films were investigated. The results showed that the grain structure of the film transformed from spherical shape to needle-like structures with the flow rate of methane increased from 1.5 sccm to 3.0 sccm. Meanwhile, the sp3/sp2 ratio decreased from 1.77 to 1.04 and the graphitization degree of sp2-bonded carbon was enhanced. Furthermore, the electric conductivity was improved from 0.01 S/m to 63.04 S/m and the average dielectric loss tangent in the range of 75–110 GHz was significantly increased from 0.09 to 1.31 with the increasing of methane flow rate. The results demonstrated that methane flow rate play an important role in governing dielectric properties of diamond/graphite composite films. Moreover, the possible microwave attenuation mechanism was explored. The dominating attenuation mechanism of the film changed from polarization loss to conductive loss with the increase of methane flow rate. The microwave attenuation ability of the film was enhanced with the synergistic increase of both conductive loss and polarization loss.

Facile hydrothermal process achieving 1T/2H phase tailoring of MoS2 nanosheets for efficient microwave absorption

Electromagnetic pollution is becoming a serious concern. Electromagnetic wave absorbers with light weight, high efficiency and broadband are desirable for electromagnetic protection. Recently, 1T/2H hybrid molybdenum disulfide nanosheets attracted great attention due to the enhanced microwave attenuation driven from fabrication of 1T/2H metal-semiconductor heterojunctions. However, the easy and controllable 1T/2H phase tailoring remains a challenge because of the difficulty in accurately controlling the two-phase ratio and the complicated process. In this study, a facile hydrothermal process is proposed to acquire the 1T/2H MoS2 nanosheets with different 1T contents. The high-resolution TEM images reveal the MoS2 nanosheets are composed of 1T/2H nano-heterojunctions with the 1T and 2H nanodomains arranged alternatively. Without compositing with conductive matters, the MoS2 nanosheets exhibit excellent microwave absorption performance with a maximum reflection loss of −27 dB and an effective absorption bandwidth of ∼4.16 GHz (at 2.3 mm thickness). It benefits from the increased conductivity of the MoS2 nanosheets, abundant 1T/2H phase boundaries and lattice defects, and improved impedance matching induced by the embedding of the 1T phase in the 2H matrix. This work demonstrates the feasibility of the proposed facile hydrothermal process in achieving 1T/2H phase regulation, providing an effective method to tailor the properties of MoS2 nanosheets for various applications.

Mechanical, dielectric, and microwave absorption properties of rGO nanosheets and ZnO filled ZnAl2O4 composites with broad bandwidth and strong absorption

Reduced graphene oxide (rGO) nanosheets and ZnO filled ZnAl2O4 composites (rGO/ZnO/ZnAl2O4 composites) were fabricated by hot-pressing sintering process in-situ reactions for the purpose of microwave absorption applications. The effects of ZnO and rGO content on the mechanical, dielectric and microwave absorption properties were systemically investigated. The results show that the porosity and microhardness increase with increasing the absorbent content, while the flexural strength presents an opposite trend. In addition, the dielectric properties present an overall increase trend with increasing the absorbent content. Because of the favorable impedance matching and the optimal microwave attenuation, the rGO/ZnO/ZnAl2O4 composite with 1 vol% rGO and 8 vol% ZnO demonstrates minimum reflection loss of –44.5 dB at 10.1 GHz and effective absorption bandwidth of 3.8 GHz in 8.2–11.8 GHz and 12.2–12.4 GHz as the thickness is 2.2 mm. The synergistic effects of interfacial polarization, dipole polarization, conductance loss, and multiple scattering result in the outstanding microwave absorption properties for the investigated rGO/ZnO/ZnAl2O4 composite, which indicates their potential candidates for the microwave absorbing materials with broad bandwidth and strong absorption.

Single and double-layered Tri-band Microwave absorbing materials

Absorbers at microwave frequencies with multiple frequency-band response are particularly important for use in military for stealth technology. Specially, ferrite based absorbing materials are significant for electromagnetic shielding and signal attenuation. The enhancement of reflection loss of ferrites along with carbonaceous materials are even more beneficial. Recently double-layer absorbers have extensively studied to meet the requirements of advanced absorbing materials in multiple frequency-band response. It still remains a challenge how to determine the type and thickness to couple the impedance-matching-layer to the absorption-layers for a double-layer absorber. We applied hydrothermal method to prepare Fe3O4 nanoparticle and combine them with either graphene oxide (GO) or reduced graphene oxide (rGO) to prepare a composite of specific quality to obtain Fe3O4@GO and Fe3O4@rGO nanocomposite. We studied microwave attenuation capabilities of single and double-layer absorbers containing these two materials. We have demonstrated that with a thin impedance matching layer as a first layer and an absorbing layer behind this layer for the double-layered absorber has much higher reflection loss (RL) than a single-layer. The Fe3O4@rGO composite as a single-layer absorber shows the best microwave absorption performance with RL close to −30 dB in all three microwave bands (X, Ku and K bands). The use of a double-layer structure as Fe3O4@GO as impedance matching layer and Fe3O4@rGO as absorbing layer exhibits the best absorption of −50 dB. This is much larger than the single-layered absorbers at all three frequency-bands. Such a performance is superior to many reported ferrite-based carbonaceous composites. Therefore, a double-layer absorber is best suited to coat the whole body of the aircraft or missiles to evade satellite detection, a preparation towards new-generation weapons for future warfare. Before performing the absorption studies we have characterized the ferrites, GO and rGO materials with various microstructural and magnetic characterizations.

Construction of Nb2CTx/α-MnO2 composites by electrostatic self-assembly for controllable impedance matching and enhanced electromagnetic absorption

Nb2CTx/α-MnO2 composites have been constructed by the deposition of α-MnO2 nanowires on the surface of the layered Nb2CTx matrix through an electrostatic self-assembly strategy. The increase of α-MnO2 content can lead to an improvement of permittivity and a shift of the reflection peak towards low frequency at a fixed thickness. Theory analysis speculates that the synergistic effect of lattice defect and electron hopping of Mn4+-O-Mn3+ chains in α-MnO2 nanowires as well as heterogeneous interfaces between Nb2CTx and α-MnO2 are predominant accounts for the enhancement of permittivity. The effective complementary of impedance matching and microwave attenuation can be responsible for the displacement of the reflection peak towards low frequency and a wide-frequency absorption. Accordingly, Nb2CTx/α-MnO2 composites exhibit an optimal reflection loss of -24.7 dB and an absorption bandwidth of 5 GHz at a thin matching thickness of 1.8 mm, which are better than those of most Nb2CTx-based absorbents.

Investigation of microwave attenuation and shielding performance of PTFE/Fe2O3/OPEFB composites at X-band frequency

This study explored the microwave attenuation and shielding properties of PTFE/Fe2O3/OPEFB composites in the X-band frequency range. Fe2O3 nanoparticles were incorporated into the PTFE/OPEFB matrix using a powder-dry mixing technique. The composites were characterized using XRD and FESEM, and attenuation performance was evaluated using a VNA. The results indicated that the addition of Fe2O3 nanoparticles improved microwave attenuation and shielding properties, with the composite containing 15 wt% Fe2O3 exhibiting the highest attenuation of 16.02 dB. The homogeneous dispersion of Fe2O3 nanoparticles was confirmed through FESEM analysis, and XRD analysis confirmed the presence of Fe2O3 nanoparticles in the composites. The study concludes that PTFE/ Fe2O3/OPEFB composites have potential for electromagnetic interference shielding applications in aerospace, telecommunications, and electronics industries.

Nano structural engineering of Ba-substituted Sr-hexaferrites for viable microwave absorbance and magnetic data storage

This work focuses on optimization of magnetic attributes of Sr hexaferrites using Ba as a substituent at Sr-site, for viable utilization in magnetic data storage devices and as microwave attenuation media. In this context, a series of Sr1-xBaxFe12O19 samples was prepared using a facile hydrothermal route. X-ray diffraction confirmed the hexagonal structure with space group P63/mmc. The morphological analysis revealed that the samples had hexagonal nanorod-like morphology which was quite suitable for microwave-absorbing devices and data storage. The analysis demonstrated that the particle sizes were decreased while the width of particles increased with increasing Ba contents. The dielectric parameters were suitably tuned as a function of frequency and Ba contents. The saturation magnetization, coercivity, remanent magnetization, and squareness ratio of all the sample compositions showed an increasing behavior with Ba contents, revealing that the prepared samples were favorable for use as microwave absorbers, data storage devices, and magnetic recording media.

Strengthened microwave absorption properties of polymer-derived carbon-rich SiCN (Ni3Si) ceramic fibers pyrolyzed at low temperature

In this study, carbon-rich SiCN (Ni3Si) ceramic fibers (CSCF) were prepared through electrospinning and low-temperature (700–1000 °C) polymer derivation, and the effect of pyrolysis temperature on carbon content, carbon graphitization degree, dielectric properties and microwave (MW) absorption properties of fibers was explored. The results show that increasing pyrolysis temperature is conducive to the graphitization of carbon in fibers, but it also reduces the content of polyvinylpyrrolidone (PVP) derived carbon in the material. The synergistic relationship between the carbon content and carbon graphitization degree of CSCF obtained by pyrolysis at 800 °C was the best, benefiting from which its impedance matching ability is properly cooperated with the MW attenuation and its widest effective absorption bandwidth (EABW) can achieve 4.6 GHz at a thickness of 1.9 mm. Compared with SiCN-based composite ceramic fibers obtained by pyrolysis at high temperature (more than 1000 °C), the ceramic fiber prepared in this study had a significantly improved EABW even at a reduced introduction amount of metal element. In addition, the as-synthesized fiber precursor (FP) has high flexibility, based on which the macro-morphology of the material can be tailored more easily, to obtain the devices made of ceramic fibers with various complex shapes. The experimental ideas and conclusions of this work are of great significance for expanding the application of SiCN ceramic based composites in the field of MW absorption in the future.

Polyvinylpyrrolidone induced uniform coating of nickel nanoparticles on carbon nanotubes for efficient microwave absorption

The impedance matching performance of carbon nanotubes (CNTs) can be effectively enhanced by developing a uniform magnetic impedance matching layer, which can take on critical significance in achieving the desirable microwave absorption (MA) performance. To obtain a uniform coating of Nickel (Ni) nanoparticles on CNTs, several methods have been developed (e.g., the γ-irradiation technique, electroless deposition, as well as microwave welding method). However, the intricate and complicated conditions of the above-mentioned methods limit their wide application. Therefore, controlling the distribution of Ni nanoparticles with the aid of a concise and effective method remains a great challenge. Herein, in view of the uniform dispersion effect of polyvinylpyrrolidone (PVP) on CNTs and its complexation with Ni ions, uniform coating of Ni nanoparticles on CNTs is well developed after it is introduced in the hydrothermal process. The prepared Ni/CNTs composites exhibited excellent MA performance in comparison with those of reported Ni/CNTs composites for the ideal impedance matching performance and microwave attenuation ability. When the filler content was only 15 wt%, the minimum reflection loss (RLmin) reached −39.5 dB, and the effective bandwidth (EB) with RL < -10 dB reached 5.2 GHz at the thickness of 1.15 mm. A scalable strategy of regulating the distribution of Ni nanoparticles and preparing a lightweight microwave absorber based on CNTs was developed in this study, which can serve as a vital guideline for preparing novel MA composite materials.

Coal gasification fine slag doped with Fe3O4: High-performance electromagnetic-wave absorbers

The pursuit of electromagnetic absorbers with high-performance characteristics has led to a growing appreciation for easily prepared and environmentally friendly methods. In this study, heterostructured multi-interface Fe3O4@Coal gasification fine slag (CGFS) composites were directly prepared via coprecipitation of Fe3O4 nanoparticles (NPs) and untreated coal gasification fine slag. The composite material was subjected to analysis of its magnetic properties, crystal structure, composition, electromagnetic parameters, and morphology, resulting in the determination that the material achieved a minimal reflection loss (RLmin) of –28.10 dB at 10.00 GHz at a thickness of 2.7 mm (Fe3O4@FS-1). Broadband microwave attenuation covers 4.00 GHz at a thickness of 1.7 mm (Fe3O4@FS-2). The exceptional performance of Fe3O4@CGFS composites in absorbing electromagnetic waves (EMWs) is attributed to a combination of factors, including appropriate impedance matching, dielectric and magnetic losses, and a multi-interface design, resulting in a synergistic effect. The CST simulation clearly indicated that the Fe3O4@FS-1 composite is capable of significantly reducing the radar cross-section value under realistic conditions. The corrosion resistance test results show that the Fe3O4@CGFS composites has good chemical stability. Overall, the high graphite residual carbon content in CGFS provides a foundation for reducing the preparation conditions of EMW absorbers while maintaining superior electromagnetic-wave absorption and dielectric losses, thereby expanding the high-value utilization of CGFS.

Hollow Co/NC@MnO2 polyhedrons with enhanced synergistic effect for high-efficiency microwave absorption

High-efficiency microwave absorbents with lightweight characteristics possess prospective applications in electromagnetic radiation protection, but still face huge challenges. Herein, hollow Co/NC@MnO2 (H–Co/NC@MnO2) polyhedrons with hierarchical structure and enhanced synergistic effect are successfully fabricated via the collaborative steps of etching-pyrolysis-hydrothermal reaction. Specifically, hollow engineering of Co/NC with heteroatoms endow the polyhedrons with lightweight characteristics, dipolar polarization and magnetic loss, hierarchical MnO2 nanosheets with oxygen vacancies grant dielectric loss and multiple scattering, and the dielectric-magnetic synergistic effect between Co/NC and MnO2 promote impedance matching and strengthen interfacial polarization. Benefiting from the above mentioned advantages, the H–Co/NC@MnO2 polyhedrons exhibit high-efficiency microwave attenuation at a low filler loading of 20 wt%. The optimal reflection loss reaches −54.7 dB and the effective absorption bandwidth ranges from 11.8 GHz to 18 GHz (6.2 GHz) with a thickness of only 2.1 mm. These findings provide us a promising strategy in developing high-efficiency and lightweight microwave absorbents for practical applications.

Combination strategy of large interlayer spacing and active basal planes for regulating the microwave absorption performance of MoS2/MWCNT composites at thin absorber level

Recently, molybdenum disulfide (MoS2)/carbon has become a promising candidate for efficient microwave absorption. However, it is still challenging to simultaneously optimize the synergy of impedance matching and loss capability at the level of a thin absorber. Here, a new adjustment strategy is proposed by changing the concentration of precursor l-cysteine for MoS2/multi-walled carbon nanotubes (MWCNT) composites to unlock the basal plane of MoS2 and expand the interlayer spacing from 0.62 nm to 0.99 nm, leading to improved packing of MoS2 nanosheets and more active sites. Therefore, the tailored MoS2 nanosheets exhibit abundant sulfur-vacancies, lattice-oxygen, more metallic 1T-phase, and higher surface area. Such sulfur-vacancies and lattice-oxygen promote the electronic asymmetric distribution at the solid-air interface of MoS2 crystals and induce stronger microwave attenuation through interface/dipole polarization, which is further verified by first-principles calculations. In addition, the expansion of the interlayer spacing induces more MoS2 to deposit on the MWCNT surface and increases the roughness, improving the impedance matching and multiple scattering. Overall, the advantage of this adjustment method is that while optimizing impedance matching at the thin absorber level, composite still maintains a high attenuation capacity, which means enhancing the attenuation performance of MoS2 itself offsets the weakening of the composite's attenuation ability caused by the decrease in the relative content of MWCNT components. Most importantly, adjusting impedance matching and attenuation ability can be easily implemented by separate control of l-cysteine content. As a result, the MoS2/MWCNT composites achieve a minimum reflection loss value of −49.38 dB and an effective absorption bandwidth of 4.64 GHz at a thickness of only 1.7 mm. This work provides a new vision for the fabrication of thin MoS2-carbon absorbers.

Broadband asymmetric transmission in quasiperiodic-metamaterials based on high entropy alloys ribbon

The new paradigm was introduced for achieving excellent electromagnetic (EM) waves absorption through multi-layer superimposed quasiperiodic-metamaterials, which were generated in rotary high entropy alloys ribbon. With the help of asymmetry, the designed anisotropic metamaterials with excellent absorption (ReflectionLoss≤−10dB) covered from 3.8 GHz to 18 GHz on the scale of sub-wavelength. High entropy alloys ribbon increased soft magnetic properties that design cascaded configuration metamaterials displayed distinct phase differences with increased rotation angle, which significantly focus on microwave attenuation. Meanwhile, the direction of the wave vector accompanied by rotation can realize polarized conversion, from linear polarizer to circular polarizer which is demonstrated in simulation, highly desirable in controlling EM waves and shrinking the size of traditional absorbing coating. Our study provides a fresh perspective to developing high-performance absorbers by combining soft magnetic and irregular phase patterns as possible as need for complex EM waves manipulations, arbitrary phase encoding, and vortex field.

Hierarchical and Orderly Surface Conductive Networks in Yolk-Shell Fe3 O4 @C@Co/N-Doped C Microspheres for Enhanced Microwave Absorption.

Constructing the adjustable surface conductive networks is an innovation that can achieve a balance between enhanced attenuation and impedance mismatch according to the microwave absorption mechanism. However, the traditional design strategies remain significant challenges in terms of rational selection and controlled growth of conductive components. Herein, a hierarchical construction strategy and quantitative construction technique are employed to introduce conductive metal-organic frameworks (MOFs) derivatives in the classic yolk-shell structure composed of electromagnetic components and the cavity for remarkable optimized performance. Specifically, the surface conductive networks obtained by carbonized ZIF-67 quantitative construction, together with the Fe3 O4 magnetic core and dielectric carbon layer linked by the cavity, achieve the cooperative enhancement of impedance matching optimization and synergistic attenuation in the Fe3 O4 @C@Co/N-Doped C (FCCNC) absorber. This interesting design is further verified by experimental results and simulation calculations. The products FCCNC-2 yield a distinguished minimum reflection loss of -66.39dB and an exceptional effective absorption bandwidthof 6.49GHz, indicating that moderate conduction excited via hierarchical and quantitative design can maximize the absorption capability. Furthermore, the proposed versatile methodology of surface assembly paves a new avenue to maximize beneficial conduction effect and manipulate microwave attenuation in MOFs derivatives.

The heterointerface of graphene in-situ growth for enhanced microwave attenuation properties in La-doped SiBCN ceramics

The electromagnetic wave (EMW) absorbing materials are widely applied to attenuate the useless and harmful EMW generated from wireless communication and 5G networks, which could protect the human health and electronic device safety. In this study, La-doped SiBCN ceramics with broadband EMW absorption capability were prepared via generating abundance of heterointerfaces, as graphene were in-situ grown by La2O3 catalyzing. The graphene in-situ formed in the ceramics can be attributed to the La atom decreasing the potential energy of the free carbon ring nucleation from −760.9 Ha to −8984.3 Ha. Consequently, the electrical conductivity of the SiBCN ceramics improved from 12.360 S/m to 18.025 S/m, the minimum reflection loss (RLmin) obtained was −26.48 dB at 7.2 GHz and the effective absorption bandwidth (EAB) was 6.32 GHz (11.68–18.00 GHz) at a thickness of 1.7 mm. At 700 °C, the RLmin and EAB values reached −43.18 dB and 4.2 GHz, respectively. The enhanced EMW absorbing capability can be attributed to the rationally tailor the heterointerfaces to improve the polarization loss and conduction loss of the SiBCN ceramics. The interfaces between graphene and amorphous phases generate built-in electric fields and space chare regions to strengthen the interface polarization, while the electrons migrating rapidly in the graphene and other crystals improved the electrical conductivity. The positive effect of heterointerfaces regulation of graphene in-situ growth improved the dielectric loss capacity of the SiBCN ceramics; therefore, this study provides a feasible method to enhance the EMW absorption capability of polymer-derived ceramics.