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A novel class of high-entropy pyrochlore compounds with multiple elements at the A and B site positions (A2B2O7) was successfully obtained. Powders with (La1/7Sm1/7Nd1/7Pr1/7Y1/7Gd1/7Yb1/7)2(Sn1/3Hf1/3Zr1/3)2O7 nominal composition were fabricated from pure metal oxides obtained through a reaction of metal nitrates (for site A) and metal chlorides (for site B) with sodium hydroxide during the solid-state displacement reaction (SSDR). The phase evolution was analyzed using XRD method. During the thermal treatment of ten individual metal oxides, the single pyrochlore phase was created. The present study showed that the highdensity (98%TD) ceramics with a hardness of 8.1GPa was successfully obtained after pressureless sintering at 1650 °C for 4 h. Results of the Raman study and the Rietveld structural refinement showed that sintered highentropy ceramics is characterized by a single-phase pyrochlore structure, which was investigated in detail.

Complex liquid–solid reactions occur during brazing. A deep understanding of brazing liquid evolution is therefore of important concern for the bonding between filler and substrates. The joining of gas‐pressure‐sintered silicon nitride (Si3N4) ceramic to oxygen‐free copper (OFC) foil was prepared using Ag–Cu–TiH2 filler at 875°C for 0.5 h. The effect of the Ag:Cu ratio on the interfacial microstructure and peeling strength of the joints was analyzed. The reaction of brazing liquid with Si3N4 ceramic includes reactions with both the β‐Si3N4 and the grain boundary phases (Y–Si–Mg–O–N). The resulting interfacial reaction products include TiN, Ti5Si3, and potential Cu3Ti3O. Based on the phase composition and three‐dimensional morphology of the interfacial reaction products in the Si3N4 ceramic/OFC foil joints, a model for the evolution of the brazing liquid as the reaction proceeds was proposed. Peeling test results indicated that the peeling strength of the joints rises unilaterally with the increase of the Ag:Cu ratio in the filler until reaching the peak value of 24.3 N/mm at the maximum Ag:Cu ratio of 90:10. The mechanisms of the joint peeling fracture were discussed in detail. [ABSTRACT FROM AUTHOR]

Thermal insulation materials must exhibit superior mechanical properties alongside exceptional thermal insulation conductivity. However, traditional porous ceramics often struggle to meet these dual requirements simultaneously. In high-entropy materials, the phonon scattering induced by lattice distortion effects can significantly reduce the thermal conductivity of ceramics, thus opening new avenues for the design of novel thermal insulation materials. Inspired by the high-entropy effect, this study employed solid-state reaction methods to synthesize (Ce0.2Zr0.2Ti0.2Sn0.2Ca0.2)O2−δ (CZTSC) high-entropy ceramics at various temperatures, investigating their phase constituents, microstructural characteristics, and mechanical properties, while exploring the optimal sintering temperature. Additionally, a pore-forming agent method was utilized to fabricate monophasic CZTSC porous ceramics with different porosities at 1400 °C. Specifically, when the pore-forming agent content was 20 wt%, the sample exhibited an apparent porosity of 42.82%, with a low thermal conductivity of 0.57 W·m− 1·K− 1, a low thermal diffusivity of 0.406 mm2·s− 1, and a relatively high compressive strength of 32.49 MPa. The current investigation underscores the promising prospects of porous CZTSC ceramics in the field of thermal insulation. [ABSTRACT FROM AUTHOR]

Traditional carbon materials suffer from weak adsorption of lithium polysulfides and excessive consumption of electrolyte. A simple and feasible molten salt method is applied for constructing an active nanocrystalline TiC shell on the surface of porous carbon. The highly active TiC nanoshells endow the core–shell composite with efficient chemical–physical synergistic adsorption, which can effectively confine and convert polysulfides, thereby improving the electrochemical performance of lithium–sulfur batteries. The lithium–sulfur batteries assembled with modified separator deliver a high initial discharge specific capacity of 1396 mAh g−1 at a discharge rate of 0.5 C and a high capacity retention of 747.1 mAh g−1 after 500 cycles, with a high coulombic efficiency of 98% during cycling. Besides, this molten salt method can be applied to modify the porous carbon materials of various composite sulfur cathodes such as graphene, carbon nanotubes, and 3D nonwoven carbon fabrics. [ABSTRACT FROM AUTHOR]

In order to enhance the interfacial bonding between aluminum and β-Si3N4 whiskers in Al matrix composites (AMCs), Ni coating was deposited on the surface of β-Si3N4 whiskers using an electroless plating method. The interfacial test results showed that Ni coating was successfully deposited on the surface of β-Si3N4 whiskers and the whiskers were well bonded with Al matrix without pores. In addition, the whiskers were homogeneously dispersed in the Al matrix. The effect of Ni-coated β-Si3N4 whiskers on the mechanical properties of composites was investigated in detail. Densification and the mechanical performance of AMCs reinforced by Ni coated β-Si3N4 whiskers (NSAMCs) were improved comparing to that of AMCs reinforced by uncoated β-Si3N4 whiskers (USAMCs). The maximum value of tensile strength and bending strength reached up to 290 MPa and 487 MPa, when the Ni content was 0.9 vol.% and the β-Si3N4 whiskers content was 20 wt.%, respectively. However, excessive Ni content weakened the strengthening effect. Medium Ni coating on β-Si3N4 whiskers significantly optimized the interface and improved the performance of the composites. [ABSTRACT FROM AUTHOR]