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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]

Abstract: In this paper, YVO4:Yb3+,Er3+ nanoparticles have been successfully prepared via a facile hydrothermal technique in the presence of citric acid as a complexing agent followed by a subsequent heat treatment process. The nanostructures, morphologies and upconversion luminescent properties of the as-prepared YVO4:Yb3+,Er3+ upconverting nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescent (PL) spectra. XRD results indicate that all the diffraction peaks of samples can be well indexed to the tetragonal phase of YVO4. TEM images demonstrate that the samples synthesized hydrothermally consist of granular-like nanoparticles ranging in size from about 30 to 50nm. After being calcined at 500–800°C for 2h, the grain sizes of nanoparticles increase slightly. Additionally, the as-prepared nanoparticles show bright green luminescence corresponding to the 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of Er3+ ions under the excitation of a 980nm diode laser, which might find potential applications in fields such as phosphor powders, infrared detection and display devices. [Copyright &y& Elsevier]

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]

Morphology of transition metal oxide largely affects its electrochemical energy storage properties. This also applies to its composites. In this paper, NiFe 2 O 4 /Graphene nanosheets composites (NFO/GNSs) are successfully prepared by a facile hydrothermal method. NiFe 2 O 4 (NFO) in the sample exhibits a unique nanosheet morphology, vertically arranging on the graphene nanosheets (GNSs). Microscopically, NFO nanosheets interpenetrate on the surface of graphene to form a continuous network structure. The sample exhibits excellent specific capacitance and rate performance. It is worth mentioning that the specific capacitance increases to 140% after 5000 cycles, showing superior cycle stability. This may be due to the conductive network formed by NFO nanosheets and GNSs. Excellent electrochemical performance indicates excellent application prospects of materials in supercapacitor electrodes. Image 1 • Unique NiFe 2 O 4 nanosheets structure with graphene nanosheets was successfully prepared by a hydrothermal method. • NiFe 2 O 4 nanosheets/graphene performed a better specific capacitance, arriving at 464.15 F/g at current density of 1 A/g. • The network structure formed between NiFe 2 O 4 nanosheets and graphene nanosheets provides excellent cycle performance. [ABSTRACT FROM AUTHOR]