Thermal-barrier coatings rely on ceramic layers that limit heat flow to metal components. A team studying (Gd_1−xSm_x)TaO₄ (GST-x) found that the conventional Klemens-Abeles parameter peaks near x = 0.5. However, room-temperature lattice thermal conductivity is lowest at x = 0.8. From GST-0 to GST-0.8, mean sound velocity fell by about 20%, while conductivity dropped by nearly one-third. Ultrasonic measurements and first-principles calculations linked most of the decline to acoustic softening. Comparison with GST-1 also suggests additional point-defect scattering from Gd/Sm site mixing. The findings could help coating designers choose rare-earth tantalate compositions with lower thermal conductivity.

With the continuous advancement of industrialization, high-precision actuators are increasingly being applied in fields requiring high accuracy, such as aerospace, smart vehicles, and robotics. However, the current mainstream actuator materials on the market are lead-containing ceramics primarily composed of lead zirconate titanate (PZT). During the manufacturing process, these ceramics produce lead and lead oxide, both of which are highly harmful to the environment and human health. Therefore, the development of lead-free ceramics capable of serving as high-precision actuator materials is urgently needed. As the most widely studied lead-free system, perovskites have rightfully become the most extensively investigated lead-free material family. Among them, barium titanate (BaTiO₃)-based lead-free ceramics, one of the most promising systems, have attracted widespread research due to their excellent stability and favorable electro-strain properties. However, although phase boundary engineering, the construction of polar nanoregions (PNRs), and defect engineering have partially improved the strain hysteresis of ceramic materials, these advances still fall short of meeting the demands of high-precision actuators.

Plastic waste should not be viewed as a uniform refuse stream, but as a heterogeneous carbon reservoir whose recycling pathway is dictated by polymer composition, contamination level and degradation history. Here, we outline a graded recycling framework that prioritizes carbon retention rather than technology-driven conversion. Clean and separable plastic streams should first undergo physical recycling to preserve polymer backbones and avoid unnecessary bond cleavage. Mixed, aged or contaminated fractions are better suited to selective chemical routes, including solvolysis, hydrogenolysis, catalytic depolymerization, electrified pyrolysis and gasification, which can reconstruct carbon into monomers, hydrocarbons, syngas or platform chemicals. Biological recycling is most effective for oxygenated intermediates generated through pretreatment. Integrating sorting, safety control and life-cycle assessment, this physical–chemical–biological hierarchy matches each plastic carbon stream with its most valuable and sustainable conversion pathway.

Ultra-high temperature ceramics (UHTCs) are critical to thermal protection systems for hypersonic vehicles, yet their oxidation behavior above 2000 ℃ remains poorly understood because conventional testing methods have limited applicability. Researchers at Donghua University, China, have developed a novel ultra-fast heating method (100 ℃/s, >2000 ℃) to evaluate the cyclic oxidation behavior of multi-principal component diboride (MEB) ceramics at 2300 ℃. Among the compositions studied, (Zr_1/4Hf_1/4Ta_1/4Ti_1/4)B₂ exhibited the best performance, forming a dense oxide scale just 99 mm thick that remained intact after five thermal cycles. The team revealed that beyond configurational entropy, the functional element Ti plays a dual role—densifying the outer oxide layer at high temperatures and inducing a stress-relieving porous needle-like Ta₂O₅ network during cooling. This work establishes a convenient and efficient testing protocol and provides a “structural-functional element synergy” design principle for reusable thermal protection materials.

This review summarizes recent progress in microwave-driven catalytic conversion of waste plastics. It covers the synergy between microwave dielectric heating and catalysis, depolymerization pathways of various plastics, catalyst design and structure-activity relationships, and effects of reaction parameters on product distribution. Key challenges are discussed, including unclear mechanisms, catalyst deactivation, and scale-up difficulties. Future directions are proposed, such as multi-scale mechanistic studies, development of stable catalysts, and continuous-flow reactor design.