image: (Hf(1-x)/4Zr(1-x)/4Nb(1-x)/4Ta(1-x)/4Cox)C (x=0.14, 0.18, and 0.20) ceramics were successfully synthesized with a single-phase high-entropy carbide exhibiting a rock salt structure under conditions ≥1800oC. The dielectric property tests show that, with increasing cobalt content, the complex permittivity and complex permeability of (Hf(1-x)/4Zr(1-x)/4Nb(1-x)/4Ta(1-x)/4Cox)C (x=0.14, 0.18, and 0.20) ceramics gradually decreased. The (Hf0.215Zr0.215Nb0.215Ta0.215Co0.140)C high-entropy ceramic exhibits the highest dielectric constant and permeability along with moderate conductivity, achieving an optimal balance between polarization relaxation, conduction loss, and magnetic loss. Therefore, among the studied materials, this ceramic exhibited the best microwave absorption performance, with an RLmin of -37.95 dB at a thickness of 3.10 mm.
Credit: Journal of Advanced Ceramics, Tsinghua University Press
With the advent of the 5G era and the comprehensive integration of wireless communication technologies and electronic devices, the pivotal role of electromagnetic waves in both civilian and military applications has become increasingly prominent. However, the widespread use of electromagnetic technology has also led to significant negative effects, including threats to the performance of sensitive equipment, potential impacts on human health, risks to information security, and issues of electromagnetic pollution. In this context, researchers have developed various countermeasures. Among these, electromagnetic wave absorbing materials, which effectively convert electromagnetic energy into thermal energy to attenuate electromagnetic waves, have emerged as a viable solution to electromagnetic interference problems, naturally becoming a focal point of recent research.
Among numerous candidate materials, ceramics are widely recognized as ideal microwave absorbers due to their unique structural characteristics, stable performance in high-temperature environments, and cost-controllable fabrication processes. Notably, the excellent dielectric loss properties of ceramic materials provide crucial design principles for developing high-performance microwave absorbers. Recent research trends indicate that combining different materials to leverage their synergistic effects can effectively enhance the wave-absorbing capabilities of ceramics. Nevertheless, the performance limitations of single-component ceramics persist, directly driving research into multiphase composite structures and the introduction of secondary phases. In the forefront of materials research, high-entropy ceramics, as representatives of new materials, have garnered widespread attention due to their highly tunable compositions and the "cocktail effect." To further push the boundaries of their performance, a highly promising strategy involves introducing magnetic elements into the high-entropy ceramic matrix.
Recently, Associate Professor Bin Du from the Lightweight Composites Team of Guangzhou University, China, reported the latest research results on boosting microwave attenuation in high-entropy carbide ceramics via magnetic Co incorporation and microstructural engineering. In this work, the (Hf(1-x)/4Zr(1-x)/4Nb(1-x)/4Ta(1-x)/4Cox)C (x=0.14, 0.18, and 0.20) high-entropy ceramic powders were successfully synthesized using the polymer-derived method. Research has found that the irregular morphology of these high-entropy ceramic powders and the voids between particles enhance the attenuation of electromagnetic waves within the material. The introduction of cobalt increases lattice defects and heterojunction interfaces in the ceramic matrix, thereby further enhancing interfacial polarization and dipole polarization reactions. And the (Hf0.215Zr0.215Nb0.215Ta0.215Co0.140)C ceramic prepared exhibited excellent reflection loss (RL) of -37.95 dB at 14.01 GHz with a thickness of 3.10 mm.
The research team published their findings on September 26, 2025 in the Journal of Advanced Ceramic.
“The study found that (Hf(1-x)/4Zr(1-x)/4Nb(1-x)/4Ta(1-x)/4Cox)C (x=0.14, 0.18, and 0.20) ceramics were successfully synthesized with a single-phase high-entropy carbide exhibiting a rock salt structure under conditions ≥1800oC. Additionally, we conducted structural simulations based on first-principles calculations. The simulation results showed an FCC structure consistent with the XRD data while revealing significant local lattice distortion phenomena.” Bin Du, Associate Professor at the School of Physics and Materials Engineering, Guangzhou University, and a expert in the fields of ceramic aerogels and wave-absorbing properties by precursor transformation method, and medium/high entropy ceramics and properties by precursor transformation method, said, “All samples exhibited irregularly shaped nanocrystalline particles with noticeable gaps after heat treatment. The lattice spacing values measured from HRTEM images were slightly larger than those calculated from XRD results, which is attributed to the presence of local lattice strain. Moreover, the lattice strain was sufficient to alter the local lattice parameters, causing lattice distortion, consistent with the results obtained from computational simulations.”
“The dielectric property tests show that, with increasing cobalt content, the complex permittivity and complex permeability of (Hf(1-x)/4Zr(1-x)/4Nb(1-x)/4Ta(1-x)/4Cox)C (x=0.14, 0.18, and 0.20) ceramics gradually decreased.” Bin Du said, “The (Hf0.215Zr0.215Nb0.215Ta0.215Co0.140)C high-entropy ceramic exhibits the highest dielectric constant and permeability along with moderate conductivity, achieving an optimal balance between polarization relaxation, conduction loss, and magnetic loss. Therefore, among the studied materials, this ceramic exhibited the best microwave absorption performance, with an RLmin of -37.95 dB at a thickness of 3.10 mm.”
“In this study, (Hf(1-X)/4Zr(1-X)/4Nb(1-X)/4Ta(1-X)/4CoX)C (X=0.14, 0.18, and 0.20) high-entropy ceramic powders were successfully synthesized via a PDC route at 1700°C-1900°C. Phase composition analysis, microstructural characterization, and XPS results confirmed the formation of a single-phase rock-salt structure in all compositions. The substitution of Co not only stabilized the single-phase structure but also introduced magnetic loss characteristics into the ceramic system. Among the compositions studied, (Hf0.215Zr0.215Nb0.215Ta0.215Co0.140)C ceramic prepared at 1700°C exhibited the best microwave absorption performance, with an RLmin of -37.95 dB at a thickness of 3.10 mm. The enhanced absorption was attributed to the synergistic contribution of multiple mechanisms: interfacial polarization, dipole relaxation, conduction loss, and magnetic loss (such as eddy current and natural resonance). This work reveals the application prospects of cobalt-doped high-entropy carbides as lightweight and efficient microwave-absorbing materials. These findings provide key insights into the composition-structure-property relationships and loss mechanisms, offering guidance for the design of high-entropy ceramics for electromagnetic wave attenuation.” said Bin Du.
About Author
Bin Du, Guangzhou University, Associate Professor, School of Physics and Materials Science, Guangzhou, China. 2024, selected for World's Top 2% Scientists 2024, serves as an editorial board member of Journal of Advanced Ceramics. He is mainly engaged in the research of ceramic aerogel and wave-absorbing properties by precursor transformation method, and medium/high entropy ceramics and properties by precursor transformation method. In recent years, he has presided over a number of projects of National Natural Science Foundation of China (NSFC), Guangdong Province Natural Science Foundation, etc. He has published more than 50 SCI papers in international journals, and has been authorized two invention patents.
Tao Zhang, Guangzhou University, School of Physics and Materials Science, Professor/BoD. 2023 and 2024 in the top 2% of the world's top scientists list. He has published more than 200 papers and co-authored two monographs in English. He has been in charge of a number of National Natural Science Foundation of China (NSFC) projects, Guangdong Natural Science Foundation of China (GDNSFC) projects, National Key Research and Development Program (NKRDP) sub-projects, and University-Enterprise Collaboration Program (UECP) projects.
About Journal of Advanced Ceramics
Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2024 IF is 16.6, ranking in Top 1 (1/33, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508
Journal
Journal of Advanced Ceramics
Article Title
Boosting microwave attenuation in high-entropy carbide ceramics via magnetic Co incorporation and microstructural engineering
Article Publication Date
26-Sep-2025