The rising service temperature of aero-engine hot-section components makes calcium magnesium aluminum silicate (CMAS) corrosion a key failure mechanism for thermal/environmental barrier coatings (T/EBCs). The novel Gd2O3-Yb2O3-Y2O3 co-stabilized ZrO2 (GYYZO) ceramic is promising due to its good thermophysical properties. However, its CMAS corrosion resistance at 1500 degrees C needs improvement. In this work, a PS-PVDfabricated Si-HfO2/Yb2Si2O7/GYYZO coating system was enhanced via Al deposition and vacuum heat treatment. Firstly, the as-sprayed coating was annealed at 1300 degrees C to heal microcracks. Subsequently, a 3-4 mu m thick aluminum film was deposited on the GYYZO layer surface via direct current pulsed magnetron sputtering. Finally, vacuum heat treatment (400 degrees C/2.5 h + 660 degrees C/2 h + 808 degrees C/1.5 h + 980 degrees C/1 h) was conducted to promote the formation of a dense Al2O3 barrier layer. A comparative study at 1500 degrees C revealed that CMAS rapidly penetrated the unmodified GYYZO coating along grain boundaries, causing blistering and cracking in the Yb2Si2O7 layer and accelerating failure. Conversely, the Al-modified GYYZO coating formed a dense Al2O3 barrier in situ, effectively suppressing CMAS penetration and slowing corrosion kinetics, thus maintaining structural integrity after 1 h.
Yellow laser sources in the range of 570-590 nm have many important applications in frontier fields such as flow cytometry, sodium guide star, and ophthalmic surgery. Yellow laser output from blue laser diode-pumped Dy3+-doped crystals is a promising technology with advantages of high efficiency, compactness, and high power stability. However, Dy3+-doped laser crystals mainly focused on low-phonon-energy fluorides, while the high-phonon-energy oxides were rarely studied. Herein, high-quality Dy3+-doped and Dy3+, Tb3+ co-doped Y2SiO5 (YSO) crystals were grown by the optical floating zone method. The yellow emission and energy transfer processes in Dy:YSO and Dy,Tb:YSO crystals were investigated. Compared with Dy:YSO, the absorption cross-section of Dy,Tb:YSO at 450 nm increases from 1.75 & times;10-21 cm2 to 2.21 & times;10-21 cm2, and the yellow emission cross-section at 574 nm increases from 3.45 & times;10-21 cm2 to 4.32 & times;10-21 cm2. In addition, the co-doped Tb3+ ions act as deactivator ions and the energy transfer efficiency from 6H13/2 level of Dy3+ to 7F4 level of Tb3+ is 50.7%. As a result, the lifetime of Dy3+ lower level is greatly shortened to 202.9 & micro;s, which is favorable for population inversion and yellow laser output. These results indicate that Dy,Tb:YSO crystal is a promising yellow laser gain medium.
Colloidal quantum dots(QDs)are promising emissive materials for optoelectronic devices owing to their tunable emission wavelength,high color purity,and solution processability.Quantum-dot light-emitting diodes(QLEDs),an important complementary technology to organic light-emitting diodes,have demonstrated considerable potential in display applications.However,the inherent toxicity of conventional Cd-and Pb-based QDs has driven the development of heavy-metal-free QDs systems.Currently,heavy-metal-free blue QLEDs still lag significantly behind their red and green counterparts in device efficiency and operational stability,representing a critical bottleneck to their practical application.To address this issue,ZnSeTe QDs have attracted significant research interest due to their tunable bandgap and excellent blue emission properties.In this work,a comprehensive review of ZnSeTe QDs is provided.Firstly,their nucleation and growth mechanisms,as well as typical synthesis methods are introduced,and the key factors affecting their optical properties are discussed.On this basis,various performance optimization strategies,including band engineering,surface etching,shell passivation,and ligand regulation,are systematically summarized.Furthermore,electroluminescence mechanisms of QLEDs and recent progress on the application of ZnSeTe QDs in blue-emitting devices are reviewed.Finally,the current challenges,such as low emission efficiency,limited device lifetime,and charge injection imbalance,are discussed,and potential future development directions are proposed.
Aqueous zinc-ion batteries hold considerable promise for grid-scale energy storage, capitalizing on their intrinsic safety and low cost. However, the practical deployment of these batteries is severely hampered by the uncontrollable growth of zinc dendrites on the anode during repeated plating/stripping cycles. As the substrate for zinc deposition, the interfacial properties of the current collector have a decisive impact on the zinc deposition behavior. performance. The results demonstrate that annealing treatment induces significant crystallographic reconstruction of the copper current collector, resulting in a preferred orientation dominated by the Cu(111) crystal plane and effectively reducing the dislocation density and surface defects. Theoretical calculations reveal that the Cu(111) facet provides both a low diffusion barrier for zinc adatoms and the lowest interfacial energy with the Zn(002) plane. This synergistic thermodynamic and kinetic regulation promotes uniform and epitaxial zinc deposition, effectively suppressing dendrite formation and guiding the preferential growth of a (002)-textured zinc layer. Consequently, the modified current collector achieves exceptional plating/stripping reversibility, supporting a prolonged cycle life of over 4000 cycles with an average Coulombic efficiency of 99.9%. When applied to the aqueous zinc-iodine full battery with a zinc-free anode, it maintains a capacity retention rate of over 82% after 700 cycles at a current density of 3 A & centerdot;g(-1). This work provides fundamental insights and a practical strategy for the design of high-performance current collectors through crystallographic and interfacial engineering.
With the growing demand for efficient and environmental-friendly energy storage systems, zinc-air batteries have emerged as highly promising energy storage devices due to their high energy density, low cost, and environmental friendliness. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which suffer from sluggish kinetics, are critical factors limiting battery performance. Therefore, the development of high-performance and low-cost bifunctional oxygen electrocatalysts is of great significance. In this work, Fe single atoms/clusters anchored graphene hybrid catalysts (Fe-N/Gra) were prepared via a ball-milling assisted pyrolysis method. A series of Fe-N/Gra catalysts were obtained by adjusting the mass ratio of the metal phthalocyanine precursor to graphene, and their bifunctional oxygen electrocatalytic performances were systematically investigated. The results demonstrate that the loading amount of different metal phthalocyanine precursors exerts a significant influence on the catalytic performance of the catalysts. When the loading amount of iron phthalocyanine was 0.02 g, the resulting Fe-N/Gra-0.02 catalyst exhibited the optimal bifunctional catalytic activity for ORR and OER. The ORR half-wave potential reached as high as 0.911 V, and the OER overpotential was 610 mV at a current density of 10 mA & centerdot;cm(-2). The rechargeable zinc-air batteries assembled with this catalyst as the air electrode achieved a maximum power density of 315 mW & centerdot;cm(-2) and could sustain stable discharge for 210 h at 10 mA & centerdot;cm(-2). The excellent bifunctional oxygen catalytic activity of Fe-N/Gra-0.02 is mainly attributed to the atomically dispersed Fe-N-x active sites and the high electrical conductivity of graphene support. In addition, the agglomeration of active sites in the catalysts with excessive loading amounts is detrimental to the manifestation of their high-efficiency catalytic activity. This work provides an experimental basis for the controllable preparation of high-performance non-noble metal bifunctional oxygen catalysts and their practical applications in rechargeable zinc-air batteries.
