Progress in Natural Science: Materials International最新文献

Macrosegregation and shrinkage porosity in large steel ingots are key factors restricting the homogenization of large cast and forged parts. Due to the complex mechanisms of their formation, they have always been challenging issues in the research on solidification control of large steel ingots. The purpose of this review is to systematically revisit the research progress on the mechanisms of macrosegregation and shrinkage porosity formation in large steel ingots, focusing on the mechanisms of formation of 'A' type segregation, positive segregation at the top, and negative segregation at the bottom, and their impact on the quality of steel ingots. At the same time, the conditions and influencing factors for the formation of shrinkage porosity are analyzed in detail, and the interaction between macrosegregation and shrinkage porosity during the solidification process of steel ingots is discussed. Based on existing research results and challenges, prospects for future research directions are proposed, emphasizing the development of high-precision numerical simulation techniques and experimental research methods to deeply understand the internal mechanisms of segregation and porosity formation, providing a scientific basis for formulating effective control strategies.

Interface modification of zinc (Zn) metal anode with conductive three-dimensional (3D) structure is widely utilized in zinc ion batteries. However, the uniformity of zinc nucleation on surface microstructure is rarely investigated which exacerbates the tip effect and raises unstable risk. Herein, a strategy via the initial copper (Cu) alloying and following sulfurization treatment is reported to accomplish boosted uniform nucleation of zinc on the modified layer with dense microstructures. This epitaxial sulfide phase not only improves the wetting area to revitalize the microstructural surface, but also forms a bifunctional zincophilic Cu₂S/CuZn alloy interface layer, which combines the merits of guided local ions diffusion and improved zinc nucleation environment. As a result, a homogeneous growth of zinc on the 3D structural substrate can be realized, and cycling stability of the achieved Cu₂S/CuZn electrode with a practical capacity of 1 ​mAh cm⁻² under 1 ​mA ​cm⁻² or amplified current density of 10 ​mA ​cm⁻² is significantly enhanced. This work provides an epitaxial strategy in constructing a bifunctional zincophilic interface layer for boosting zinc nucleation, and offers a new perspective on the modification of 3D surface structure for stabilization of zinc anode.

The carbides and pores play a critical role in the cracking tendencies of nickel-based single-crystal superalloys during deformation. In the present study, the deformation mechanism and local strain evolution behavior around carbides and pores were studied through in-situ tensile deformation experiments. The findings indicate that multiple slip systems are easily activated during tensile deformation in single-crystal alloys. Furthermore, the strain localization in carbides is influenced by their morphology, with rod-like and flake-like carbides demonstrating an increased likelihood of cracking during deformation. The strain localization adjacent to pores is markedly more intense, rendering these areas particularly susceptible to cracking. Our work therefore offers a theoretical foundation for enhancing the mechanical properties of nickel-based single-crystal superalloys by controlling carbide morphology and pore formation.

The ultra-high nickel-layered cathodes (Ni ​≥ ​90 ​%) has garnered significant attention due to its high specific capacity. However, the widespread application of ultra-high nickel-layered cathodes still suffers limitation by structural instability and poor rate performance. Herein, a crystal-face-induced strategy is proposed to enhance rate and cycling performances of the electrode by constructing rapid Li⁺ diffusion channel and reducing internal grain boundaries of secondary particles. The crystal-face-induced strategy facilitates the growth of {010} lattice plane. Highly exposed {010} planes provide wide-open and unobstructed channels for Li⁺ deintercalation/intercalation, enhances the electrode diffusion kinetics, and thus improves the electrode rate performance. In addition, this strategy promotes the primary particle growth, reduces the grain boundaries of secondary particles and mitigates the electrode/electrolyte interface side reactions, enhancing the structural stability and cycling life of the electrode. Accordingly, the modified sample achieved a reversible specific capacity of 198.3 ​mAh g⁻¹ at 1 ​C (1 ​C ​= ​180 ​mA ​g⁻¹) and maintained a capacity retention rate of 88.5 % after 100 cycles, higher than that of the original sample (73.6 %, 146 ​mAh g⁻¹). At the high rate of 5 ​C, it can maintain a high specific capacity of 178 ​mAh g⁻¹ (capacity retention rate of 99 %) after 150 cycles. This work is a leap in ultra-high nickel-layered cathodes development and provides insights into the design of electrode materials for other batteries.

Li-rich Mn-based materials provide higher capacity than commercial NCM layered materials due to the synergistic redox effect of cations and anions. However, lattice straining and structural collapse caused by the irreversible oxygen release at high voltage range during cycling, which results in severe capacity and voltage decay. Herein, a synergistic strategy of surface-induced spinel structure and F doping is provided to improve the structural stability. The surface spinel structure helps to reduce the structural collapse caused by electrolyte corrosion on the cathode and effectively inhibits voltage decay resulted from structural evolution. The stronger Mn-F bonds are formed by F doping to inhibit migration of transition metal (TM) and induce the uniform deposition of LiF to form the thinner and more stable CEI on the cathode. Accordingly, the designed cathode (LMNO-NF) shows remarkable cycling performance with the capacity retention of 86.68 ​% and voltage retention of 96.6 ​% for 200 cycles at 1C, higher than pristine material (68.76 ​% and 85.75 ​%). Therefore, this simple dual-modification strategy of one-step synthesis is promising for solving the structural evolution and voltage decay of Li-rich Mn-based cathode materials effectively, achieving further commercialization.

High-entropy alloy nanoparticles (HEA-NPs) have recently sparked great interest in materials science. Their solid-solution states, derived from distinct HEA configurations, make them promising candidates for catalysts with exceptional activity, stability, and tunable performance. However, a comprehensive understanding of the underlying mechanisms governing their electrocatalytic behavior is still lacking, hindering the rational design of HEA electrocatalysts. This review summarizes the fundamental knowledge of HEA-NPs, including the structure-activity correlations of HEA-NPs, diverse synthesis strategies, and applications in electrochemical catalysis. The design strategies for guiding improvements in tunable performance were highlighted. The article concludes with insights, perspectives, and future directions, encapsulating the state-of-the-art knowledge and paving the way for further exploration in this dynamic field.

The utilization of carbon dioxide is critical to realize the objective of "carbon peak and neutrality". Among various carbon dioxide exploitation approaches, catalytic hydrogenation of carbon dioxide is a significant method to selectively convert the CO₂ into methanol and other valuable chemicals. Among these products, methanol is a crucial chemical feedstock that can be utilized as a platform molecule for the synthesis of chemicals and fuels as well as a fuel for internal combustion engines and fuel cells, causing particular interest. Nowadays, Catalytic hydrogenation of carbon dioxide into methanol has shifted its focus on the creation of low-cost, environmentally friendly, and efficient catalysts. Inspired of this, we have concluded the mechanism of catalytic hydrogenation of carbon dioxide, and reviewed the research progress of multiple heterogeneous catalysts with high catalytic application prospect, especially the supported catalysts.

The study on the uniformity of electrical performance of large wafer-scale Hf_0.5Zr_0.5O₂ (HZO) ferroelectric capacitors is still lacking yet now. In this work, TiN/HZO/TiN metal-ferroelectric-metal (MFM) devices on 12-inch silicon wafers have been fabricated by thermal atomic layer deposition. The correlation of thickness uniformity with device-to-device variation of electrical properties and yield of the 12-inch MFM system was investigated. It was found that the uniformity of ferroelectric properties is closely related to the variation of HZO thickness of the MFM system, the concentration of oxygen vacancies in the micro-region of the HZO film, and the ferroelectric phase micro-distribution on 12-inch Si wafer. This work provides some important information for the performance optimization of HfO₂-based ferroelectric random access memories.

In the present study, the operational lifetime of a solid oxide fuel (SOFC) short stack is predicted by investigating the performance degradation of both the short stack and its cells throughout 1000 ​h at 800 ​°C. The short stack and integral cell voltages are continuously measured during the long-term test, with electrochemical impedance spectroscopy (EIS) conducted every 200 ​h. The short stack voltage decreased rapidly for the initial 200–300 ​h and afterwards, it decreased at a slow rate due to the increase in the Ohmic and polarization resistances in the same manner. Scanning electron microscopy results show that there is no delamination or cracking among constituent layers of the short-stack cells. The single degradation effects of the Ni coarsening in the anode, cation migration and surface segregation in cathode and oxide scale growth in metallic interconnect mesh are successfully integrated into a comprehensive lifetime prediction model. The experimentally measured voltage degradation data of the short stack fits well with the developed mathematical model and allows the successful prediction of the lifetime up to 50,000 ​h.

Coal mining and washing is accompanied by the production of large amounts of coal gangue, which exerts a notable influence on the natural environment. However, as a form of solid waste, coal gangue exhibits a wide range of potential applications in the field of recycling. Nowadays, ’the utilization rate and quality of coal gangue are inadequate, and the disposal capacity and scale of coal gangue obviously cannot meet the current global low-carbon environmental protection requirements. The paper presents an overview of the present state of coal gangue production and utilization, and investigates the environmental impact caused by the practice of stacking coal gangue. We emphasize the current research status of gangue in various high-value application fields, including environmental materials, agricultural production, construction materials, recovery and extraction of valuable elements, and energy generation. It highlights the significance of pre-treatment methods like activation, modification, and innocuousness for the comprehensive utilization of gangue. Additionally, we briefly introduce and discusses the future directions of research and development in this area. Nevertheless, with regard to the environmental impact of secondary contamination and the efficiency of gangue utilization, there remain numerous obstacles and unresolved matters that merit further investigation. It is believed that this review can offer valuable insights into the utilization of gangue development methods, and expedite the successful implementation and practical application of large-scale treatment and disposal of solid waste.