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Currently, materials that absorb electromagnetic waves (EMW) are being increasingly studied and used. In particular, numerous attempts have been made to improve the performance of EMW-absorbing ceramics, but little attention was paid to the effect of doping on their relevant properties. In this work, Ti 3 AlC 2 , a typical MAX-phase ceramic, was doped with different elements (Zr, Mo, Cr, Fe and Ni) at the M site via a pressure-free reactive sintering. Phase and microstructure analysis show that the doped Ti 3 AlC 2 samples possess high purities and typical layered structures. It was noticed that (Ti 0.8 Zr 0.2) 3 AlC 2 demonstrates the lowest reflection loss (−48.0 dB at the thickness of 1.62 mm) and a maximum effective absorption bandwidth of 3.9 GHz. Elemental doping has been proved to alter the dielectric and magnetic properties of Ti 3 AlC 2 , and the boosted EMW absorption performance was found to be originated from the improved impedance matching. Here, we systematically investigated the influence of different dopants on the EMW absorption characteristics of Ti 3 AlC 2 , which provides significant insights for the future design of novel EMW-absorbing materials. [ABSTRACT FROM AUTHOR]

• High-entropy carbides powders were synthesized by carbothermal reduction method. • The solid-solution elements have a great influence on EMW absorption capability. • The intrinsic characteristics make the high-entropy carbides promising EMW absorbing materials. The electromagnetic wave absorption performance of high-entropy transition metal carbides, including (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2)C, (Ti 0.2 Zr 0.2 Mo 0.2 Nb 0.2 Ta 0.2)C and (Ti 0.2 Zr 0.2 Cr 0.2 Nb 0.2 Ta 0.2)C, was investigated in the frequency from 2 GHz to 18 GHz. The electromagnetic parameter measurement and subsequent electromagnetic wave absorption evaluation showed that the high-entropy transition metal carbides possessed good electromagnetic wave absorbing properties, which had a great relation to the solid-solution elements. The (Ti 0.2 Zr 0.2 Mo 0.2 Nb 0.2 Ta 0.2)C with a 1.50 mm thickness displayed a minimal reflection loss of -32.1 dB, and the effective absorption bandwidth (<-10 dB) was in the frequency range of 13–18 GHz. Intriguingly, the minimum reflection loss reached -36.6 dB at the thickness of 2.50 mm. The electromagnetic wave absorption performance was mainly associated with conductivity loss and dipole polarization, which originated from intrinsic conductivity of the high-entropy carbides and lattice distortion resulting from solid solution of multiple elements, respectively. The experimental results show that the high-entropy transition metal carbides may be promising structural-functional integrated ceramics in wide applications. The single-phase high-entropy transition metal carbide powders without complex structure and multi phases design present excellent EMW absorption properties, including minute reflection loss and broad absorption bandwidth. [Display omitted] [ABSTRACT FROM AUTHOR]

Presently, there is a growing interest in exploring materials for absorbing electromagnetic waves (EMW). MAX materials stand out as potential absorbers. However, limited attention has been given to understanding the impact of doping on their intrinsic properties. This study innovatively introduces magnetic metallic elements (Fe, Ni) and transition metallic elements (Mo, Zr, W, Ta) simultaneously into the M site of Ti 3 AlC 2 , forming novel ternary MAX phase ceramics. Phase and microstructural analyses indicate the successful preparation of a single solid solution with uniformly distributed elements. Notably, Ti 2.7 Fe 0.1 Mo 0.2 AlC 2 exhibits the lowest reflection loss at − 33.9 dB. Ti 2.7 Ni 0.1 Ta 0.2 AlC 2 demonstrates the widest absorption bandwidth of 5.10 GHz. Importantly, the matching thicknesses for Ti 2.7 Fe 0.1 Mo 0.2 AlC 2 and Ti 2.7 Ni 0.1 Ta 0.2 AlC 2 are 2.5 mm and 1.97 mm, respectively. This indicates that the material achieves excellent microwave absorption performance while maintaining a lightweight and thin structure, making it suitable for various specific requirements. We systematically investigated the influence of different doping elements on the microwave absorption properties of Ti 3 AlC 2 , with a particular emphasis on the simultaneous introduction of magnetic metallic and transition metallic elements. This dual incorporation has significantly enhanced both dielectric and magnetic losses, offering crucial insights for the design of future innovative microwave absorption materials. [Display omitted] • The Ti 3 AlC 2 ceramics at the M site doping were prepared using a simple reactive sintering technique. • The metal element doping has great influence on electromagnetic parameters and EMW absorption performance. • The impact of doping metallic elements on the phase and microstructure evolution was investigated. • The electromagnetic wave absorption mechanism was systematically examined. [ABSTRACT FROM AUTHOR]

With the continuous development of microwave technology, the electromagnetic (EM) environment we face is becoming increasingly complex. EM wave absorbing materials, which convert EM wave energy into other forms of energy such as thermal energy, have attracted much attention in EM shielding technology for reducing and isolating EM interference. Finding absorbing materials with both strong and wideband absorption performance in 2–18 GHz is particularly important. In this paper, (Zr 0.2 Ti 0.2 Hf 0.2 Ta 0.2 Cr 0.2)C, (Zr 0.2 Ti 0.2 Hf 0.2 Ta 0.2 Ni 0.2)C, (Zr 0.2 Ti 0.2 Hf 0.2 Nb 0.2 Cr 0.2)C and (Zr 0.2 Ti 0.2 Hf 0.2 Nb 0.2 Ni 0.2)C high-entropy carbide powders were prepared through calculation and design, and their properties were compared with TaC and NbC. According to the analysis of phase composition, microstructure, and EM wave absorption performance, the prepared high-entropy carbides have formed single-phase solid solutions, and their absorption performance has been improved. It can be noted that (Zr 0.2 Ti 0.2 Hf 0.2 Nb 0.2 Ni 0.2)C has the minimum reflection loss (RL) of − 42.61 dB, and it has the maximum effective absorption bandwidth (E AB) of 3.60 GHz at the thickness of 1.00 mm. Through the analysis of EM parameters, it was found that high-entropy carbides with different compositions changed the dielectric loss, magnetic loss, and their coupling effect. This provides important insights for designing absorbing materials with ultra-thin and good conductivity. [Display omitted] • High-entropy carbide powders containing magnetic elements were successfully prepared. • The electromagnetic wave absorption performance of high-entropy carbides is improved compared to that of metal carbides. • (Zr 0.2 Ti 0.2 Hf 0.2 Nb 0.2 Ni 0.2)C exhibits excellent EM wave absorption performance, with the minimum reflection loss of − 42.61 dB at 5.25 mm, and the maximum effective absorption bandwidth of 3.6 GHz at the ultra-thin thickness of 1.00 mm. [ABSTRACT FROM AUTHOR]