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With the advent of the 5G era, while enjoying the convenience of information in our daily lives, we also face the challenge of dealing with increased and more complex electromagnetic (EM) radiation issues. Therefore, finding EM wave absorbing materials for the operating frequency range (2–18 GHz) of most electronic products has become an important aspect of ensuring human health and environmental safety. In this study, a variety of elements were incorporated into (WZrNbTaM)C powders by calculation and design, where M is Ni, Cr, or Ti. Phase and microstructural analysis demonstrated the successful preparation of a single‐phase solid solution with uniform elements distribution. The magnetic properties of the powders containing Ni and Cr elements exhibited significant improvement. Further analysis revealed that both the impedance matching and EM wave attenuation capabilities of (WZrNbTaCr)C and (WZrNbTaNi)C were enhanced, thereby improving their absorption performance. Compared to (WZrNbTaTi)C, (WZrNbTaCr)C and (WZrNbTaNi)C exhibit a significant improvement in minimum reflection loss (RL), with an increase of 27.1% and 37.2%, reaching −45.21 and −48.79 dB, respectively. The maximum effective absorption bandwidth (EAB) has also increased by 22.9% and 48.6%, reaching 3.44 and 4.16 GHz, respectively. It is noteworthy that (WZrNbTaCr)C and (WZrNbTaNi)C achieved these excellent absorption properties while maintaining a matching thickness of 1.07 and 1.17 mm. This lightweight and thin performance meets the requirements for use in special scenarios while ensuring the outstanding absorption performance. [ABSTRACT FROM AUTHOR]

Bi2O3 is a promising sintering additive for YSZ that not only decreases its sintering temperature but also increases its ionic conductivity. However, Bi2O3 preferably grows into large-sized rods. Moreover, the addition of Bi2O3 induces phase instability of YSZ and the precipitation of monoclinic ZrO2, which is unfavorable for the electrical property. In order to precisely control the morphology and size of Bi2O3, a microemulsion method was introduced. Spherical Bi2O3 nanoparticles were obtained from the formation of microemulsion bubbles at the water–oil interface due to the interaction between the two surfactants. Nanosized Bi2O3–YSZ composite powders with good mixing uniformity dramatically decreased the sintering temperature of YSZ to 1000 °C. Y2O3-stabilized Bi2O3 (YSB)–YSZ composite powders were also fabricated, which did not affect the phase of YSZ but decreased its sintering temperature. Meanwhile, the oxygen vacancy concentration further increased to 64.9% of the total oxygen with the addition of 5 mol% YSB. In addition, its ionic conductivity reached 0.027 S·cm−1 at 800 °C, one order of magnitude higher than that of YSZ. This work provides a new strategy to simultaneously decrease the sintering temperature, stabilize the phase and increase the conductivity of YSZ electrolytes. [ABSTRACT FROM AUTHOR]

Bismuth oxide (Bi2O3) is a promising additive to decrease the sintering temperature of yttria‐stabilized zirconia (YSZ)‐based electrolyte for solid oxide fuel cell application. However, Bi2O3 tends to grow into large column bars (>50 µm) in a chemical coprecipitation method, which dramatically limits the mixing uniformity of Bi2O3 and YSZ, even much worse than that of mechanical mixing. In this study, the reaction temperature was increased from room temperature to 90°C to increase the number of nucleation during the violate reaction between Bi3+ solution and YSZ suspension in NaOH. On this basis, the violence of the reaction was further moderated by adding half of NaOH first, then YSZ powders and the other half of an NaOH solution. The size of Bi2O3 was further decreased to sub‐micrometer and Bi2O3 was homogeneously mixed with YSZ particles, even when its addition amount was as large as 20 mol%. These composite powders effectively promoted the sintering behavior of YSZ. The sintering temperature of YSZ was decreased to 900 and 1000°C with 10 and 5 mol% Bi2O3 doping, respectively. Increasing the doping ratio induced severe volatilization of Bi2O3 and pore formation. Raising the sintering temperature (no more than 1200°C) enhanced the doping effect of Bi2O3 into the YSZ lattice but induced instability in the YSZ crystal structure. [ABSTRACT FROM AUTHOR]

Low melting point and high ionic conductivity of γ‐Bi2O3 make it a promising additive to decrease the sintering and operation temperatures of yttria stabilized zirconia (YSZ)‐based electrolyte for solid oxide fuel cell application. Herein, γ‐Bi2O3/YSZ composite powders with good uniformity and precise control of morphology and phase were successfully synthesized via a low cost chemical precipitation method. Both the concentration of NaOH solution and the reactant adding sequence affect the morphology and synthesis of γ‐Bi2O3/YSZ composite powders. When the concentration of NaOH was in the range of 1.25–1.875 M, tetrahedron γ‐Bi2O3/YSZ powders were synthesized. While, cubic structural γ‐Bi2O3/YSZ powders were obtained when adding Bi3+ and YSZ suspension into 1.5 M NaOH solution. The addition of YSZ facilitates the fabrication of γ‐Bi2O3 and widens its process window to a higher NaOH concentration. Thus synthesized γ‐Bi2O3/YSZ composite powders effectively decrease the sintering temperature of YSZ to 1050°C due to the uniform distribution of γ‐Bi2O3 inside YSZ powders. This work provides a facile method to fabricate γ‐Bi2O3/YSZ composite powder with controlled morphology and phase, which will promote the mass production of low cost YSZ‐based electrolyte for SOFC applications. [ABSTRACT FROM AUTHOR]

The corrosion resistance of Ti 3 AlC 2 is an indispensable characteristic in its practical applications, and the focus of this study is to optimize its mechanical and corrosion properties by introducing metal ions at the M-sites of Ti 3 AlC 2. Utilizing Ti/Al/C/Zr/Mo/Cr powders, (Ti 0.8 X 0.2) 3 AlC 2 solid solutions were synthesized via reactive hot pressing, with XRD and SEM analyses confirming the formation of MAX phases. Results revealed varying degrees of influence on the properties of Ti 3 AlC 2 due to different doping elements. Among these, Zr-doped samples exhibited superior mechanical properties, boasting excellent hardness (511 Hv), flexural strength (386.57 MPa), and fracture toughness (10.24 MPa m1/2). Additionally, all (Ti 0.8 X 0.2) 3 AlC 2 samples formed n-type semiconductor passive layers in 3.5% NaCl solution, demonstrating outstanding corrosion resistance. Further investigation revealed that the enhancement in mechanical properties stems from solid solution strengthening and lattice distortion induced by different metallic elements. Meanwhile, the corrosion resistance is primarily attributed to alterations in electron distribution resulting from doping elements. These stable materials could find applications in electroplating wastewater treatment, where materials with excellent mechanical properties and corrosion resistance are required. It is anticipated that further modifications of MAX phase materials through doping will meet these additional requirements. [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]