SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4288-1
The high-temperature oxidation resistance of Cr2AlC MAX phase ceramics is severely compromised by rapid Al depletion and the formation of a brittle sub-surface Cr7C3 layer. This study elucidates how trace Y2O3 doping (0.25 and 0.5 wt.%) modulates the oxidation behavior of Cr2AlC at 1100 °C. The incorporation of 0.5 wt.% Y2O3 significantly suppresses the parabolic rate constant compared to undoped counterparts. This kinetic suppression is attributed to the Reactive Element Effect (REE), where Y3+ segregation at α-Al2O3 grain boundaries inhibits outward Al3+ diffusion, shifting the scale growth mechanism to inward oxygen diffusion control. Consequently, this retarded Al consumption prevents the decomposition of the Cr2AlC substrate into Cr7C3. While undoped specimens fail due to volume contraction and Kirkendall voiding associated with the Cr7C3 interlayer, specimens with the most effective doping content within the investigated range maintain a stable, atomically sharp α-Al2O3/Cr2AlC interface devoid of voids and decomposition products. The superior adhesion of this interface is attributed to three synergistic factors: the elimination of volumetric mismatch induced by phase transformation, the mechanical interlocking provided by Y-rich oxide pegs, and the intrinsically higher interfacial bonding strength of the α-Al2O3/Cr2AlC system as confirmed by DFT calculations. These findings provide a mechanistic framework for designing oxidation-resistant MAX phase ceramics via reactive element doping.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4381-5
Bismuth telluride (Bi2Te3)-based alloys remain the benchmark for low-temperature thermoelectric applications, yet their conversion efficiency is limited by the trade-off between electrical and thermal transport. This study introduces a pseudo grain boundary engineering strategy to simultaneously enhance the average figure of merit (ZT) in p-type (Bi,Sb)2Te3 (BST) materials. By incorporating Ag-based compounds, the carrier concentration is optimized via substitution of Ag+ ions, while the introduction of secondary phases at grain boundaries effectively suppresses lattice thermal conductivity. The approach yields a peak ZT of 1.35 at 393 K and an average ZT of 1.25 across 303–483 K, representing a significant improvement over pristine BST. Compared to prior reports, this work achieves superior average ZT while maintaining high electrical conductivity, addressing the longstanding bottleneck of thermal conductivity reduction without compromising carrier mobility. The findings underscore the efficacy of pseudo grain boundary engineering in advancing Bi2Te3-based thermoelectrics for solid-state cooling and power generation.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(25)60581-0
Lignin-derived oxygenated aromatics, particularly phenols and aromatic ethers, are promising feedstocks for synthesizing high-density, high-heat-sink aviation fuels via alkylation-hydrogenation processes. This study systematically evaluates the catalytic performance of various zeolites (Hβ, HZSM-5, MCM-41, and HUSY) in the alkylation of phenol with cyclohexanol. Characterization demonstrates that HUSY zeolite exhibits superior catalytic activity due to its favorable pore architecture and well-balanced acid site distribution, which synergistically facilitate molecular diffusion and catalytic transformations. To further enhance catalytic properties, HUSY was modified with citric acid at various concentrations and compared with NaOH and oxalic acid treatments. Results reveal that citric acid treatment preserves crystallinity while modulating acidity and pore structure. All modified zeolites enhance phenol alkylation activity. Notably, HUSY-0.5M, exhibiting the highest medium-strong acid to total acid ratio, achieves superior performance: 80.4% phenol conversion and 99.6% selectivity for alkylation products. The catalyst also shows high activity for various lignin-derived compounds (p-cresol, anisole, guaiacol), demonstrating broad applicability. This work provides a new strategy for valorizing lignin-derived phenols into high-value fuel precursors through alkylation.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3779-1
Comprehensive mechanical properties, including hardness (H), elastic modulus (E), fracture toughness (KC), and wear resistance, are essential for oxide ceramics used in demanding environments. This work employs nanoindentation to evaluate these properties for RE3TaO7 (RE=La, Sm, Eu, Gd, Dy, Lu) and identifies the optimal calculation method for KC in brittle oxide ceramics. The ratio of indentation crack length to half-diagonal (l/α) is a key parameter: Eq. (3) is suitable when l/α < 1, while Eq. (4) applies when l/α > 1. The indentation energy method is invalid for brittle ceramics due to crack formation at high loads. RE3TaO7 oxides exhibit H of 5.8–14.9 GPa, E of 127.5–247.8 GPa, and KC of 1.0–2.0 MPa·m1/2, surpassing RE2Zr2O7 (KC 1.0–1.5 MPa·m1/2). Wear resistance, indicated by MDP, ranges from 0.55 to 0.67, outperforming RE2Zr2O7. The superior fracture toughness is attributed to weberite structure with crack deflection and tortuous propagation, contrasted with pyrochlore's straight cracks. These findings provide accurate nanoindentation-based methods for assessing mechanical properties of brittle oxide ceramics, facilitating material discovery and optimization for thermal barrier coatings and other high-temperature applications.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202505104
This study investigated the synergistic remediation of aged oil-contaminated soil collected from an oil well in Yanchang, northern Shaanxi, China, with an initial total petroleum hydrocarbon (TPH) concentration of 17.1 g·kg⁻¹, exceeding the second-class land use screening value (4,500 mg·kg⁻¹) by approximately 3.8-fold. Indigenous high-efficiency degrading strains were screened and a microbial consortium was constructed. Pot experiments were conducted to compare the TPH degradation efficiencies and soil property changes under plant, microbial, and combined plant-microbial remediation. The consortium MC-5 (SDB1:SDB2:SDB3:SDB4 = 1:1:0:3) exhibited the highest TPH degradation rate of 83.46% in liquid culture. In soil, combined remediation with ryegrass (Lolium perenne) achieved a TPH degradation rate of 60.93%, significantly higher than the control (CK) by 54.26 percentage points. The consortium also degraded recalcitrant resins and asphaltenes by 49.44%. The microbial consortium played a dominant role, contributing 63%–69% to TPH removal, whereas plant contribution was only 2%–12%, primarily in the later stage. Addition of rhamnolipid biosurfactant enhanced the combined remediation, increasing TPH degradation by 7.05 percentage points compared to non-amended treatments. These findings provide insights into the mechanisms of plant-microbial synergy and offer theoretical and practical guidance for bioremediation of petroleum-contaminated soils.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4115-9
The advancement of extreme-condition equipment, such as hypersonic vehicles and next-generation gas turbine engines, imposes stringent requirements on thermal barrier materials, particularly high fracture toughness and low thermal conductivity. However, these properties are often mutually exclusive in oxide ceramics due to their intrinsic ionic and covalent bonding. Conventional strategies to reduce thermal conductivity, such as introducing point defects or porosity, typically degrade mechanical properties, while toughening methods like second-phase or phase transformation toughening can adversely affect thermal transport. Rare earth tantalates and niobates, which exhibit ferroelastic phase transitions, offer promise for ultra-high-temperature applications (>1500°C) due to their unique domain structures that enhance toughness. Yet, weak grain boundary bonding limits the full potential of ferroelastic toughening. Li et al. proposed a high-density dislocation engineering strategy to overcome this trade-off. By introducing dislocations with densities of 10^8–10^10 mm^-2 into (YTaO4)1-x/(Y3TaO7)x (x=0.1–0.6) composite ceramics via spark plasma sintering and subsequent heat treatment, they achieved significant reductions in thermal conductivity through phonon scattering while simultaneously enhancing fracture toughness via crack deflection and energy dissipation. This work successfully decouples thermal and mechanical performance, offering a new paradigm for microstructural design in thermal protection materials.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4221-y
The advancement of 5G/6G communications and hypersonic vehicle technology imposes stringent requirements on electromagnetic wave absorbing materials, demanding efficient low-frequency (C-band, 4–8 GHz) response and stable performance above 500°C in oxidizing environments. Traditional absorbers face inherent contradictions: carbon-based composites suffer oxidation, magnetic materials lose function above Curie temperature, and ceramics like SiOC exhibit poor low-frequency absorption due to single dielectric loss. Zeng et al. (Adv Mater, 2026) propose a nitrogen-induced evolution from Fe nanoparticles to Fe single atoms within SiOC ceramic fibers. Through electrospinning of polycarbosilane, PVP, and iron(III) acetylacetonate, followed by curing at 200°C and pyrolysis at 1000°C with dicyandiamide as nitrogen source, they achieve Fe-N4 single-atom coordination. EXAFS confirms Fe-N peak at ~1.5 Å and absence of Fe-Fe peak at ~2.2 Å, ruling out clusters. This design leverages strong Fe-N covalent bonds and unique electronic structure, retaining magnetic contribution to low-frequency response while preventing nanoparticle agglomeration and oxidation. The work achieves synergistic breakthrough in low-frequency absorption and high-temperature stability, pioneering design for extreme environments.