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Sixth generation (6G) wireless networks operating in terahertz frequency region are significant solutions to the increasing number of telecommunication devices and the demand for faster data transmission. However, few dielectric materials exhibiting an ultralow relative dielectric constant (εr), loss tangent (tanδ), and high mechanical strength are found suited for 6G telecommunication. In this study, we developed lightweight ceramic foams by directly sintering glass hollow spheres. The effects of sintering temperatures on their mechanical performance, and terahertz optical and dielectric properties were systematically investigated. The final compositions of ceramic foams contain glass, cristobalite, quartz, and wollastonite. The crystalline content increases with increasing sintering temperature. The ceramic foams sintered at low temperatures of 700–850°C exhibit a high porosity ranging from 74.6% to 87.3%, ultralow εr ranging from 1.41 to 1.83, and tanδ of ∼0.011 at 0.5 THz, as well as high compressive strength ranging from 10.1 to 27.4 MPa, which could be promising materials for 6G telecommunication. [ABSTRACT FROM AUTHOR]

Hierarchical cellular architectures hold great potential in a vast range of applications due to their superior mechanical properties and multifunctionality. In the present work, hierarchical structures composed of porous struts patterned in the form of quadrangular and triangular honeycombs were fabricated via direct foam writing (DFW) using colloidal particle‐stabilized Al2O3‐MgO‐SiO2 foams as the ink. Hydration process of MgO and subsequent formation of colloidal Mg(OH)2 network endowed the foam ink with viscoelasticity and high storage modulus. The resulting honeycombs with ultrahigh overall porosity (95.3%) and robust compressive strength (2.5 MPa) can be readily fabricated by DFW. The current work exhibits a significant step toward the scalable production of cellular ceramics with hierarchical architecture for various applications, including tissue scaffolds, catalyst supports, thermal insulation, and lightweight structures. [ABSTRACT FROM AUTHOR]

Hierarchical structured porous ceramics have attracted tremendous research interests because of their numerous excellent properties including robust mechanical strength and large surface area. In this work, silicon carbide (SiC)‐based porous ceramics with three levels of pore hierarchy are fabricated from silicon particle‐stabilized foams and a subsequent one‐step calcination after they were embedded with coke. Three‐dimensional (3D) flexible nanofibrous network is adhered and wrapped on cell walls of porous ceramics, which is readily fine‐tuned and tailored by the temperature to provide optimized pore structure. The resultant SiC‐based porous ceramics present a density of 1.03 g/cm3 at a porosity of 72% with a large quantity of hierarchical micro‐ and macropores. This hierarchical structure leads to robust compressive strength (23.52 MPa) and large surface area (64.32 m2/g). The fabrication method is straightforward and sought‐after, providing a facile technical route for advanced hierarchical porous ceramics used in filtration and catalysis fields. [ABSTRACT FROM AUTHOR]