CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Rubin Zeng,Zhongjie Shen,Haigang Zhang,Yuxiang Cheng,Qinfeng Liang,Haifeng Liu
High-temperature sintering and solid-state reaction within the intricate Fe 2 O 3 /CaO system are pivotal factors influencing material characteristics. The current work focused on the sintering and reaction behavior of Fe 2 O 3 /CaO particles at high temperatures with a multiscale study of in-situ high-temperature stage microscopy (HTSM) and molecular dynamics (MD). The laws governing atomic migration and the evolution of crystal structure during the sintering process were simulated at the nanoscale. The results elucidated that a heightened heating rate fosters particle shrinkage and concomitant reduction in surface area. The sintering activation energy ( E sin ) exhibited an increment proportional to the linear shrinkage of the particles. Furthermore, an augmented potential barrier in advanced stages impeded subsequent sintering behavior. Augmented temperature promoted the particle shrinkage and sintering neck formation, culminating in pore closure and a diminution in the free surface. However, this promotional effect attenuated with escalating temperatures. Particle shrinkage and sintering neck formation are contingent upon atomic migration and diffusion, with the growth of sintering necks primarily reliant on atom diffusion along the surface of the sintering necks. The atomic diffusion activation energy was determined to be 49.5 kJ/mol within the temperature range of 1073–1473 K. Within the Fe 2 O 3 /CaO system, the preferential generation of Ca 2 Fe 2 O 5 (C2F) over CaFe 2 O 4 (CF) was found, leading to a decrease in the atomic diffusion barrier and an enhancement of the diffusivity, with the latter dominating in later stages. The highest mobility of O 2– , Fe 3+ , and Ca 2+ was discerned in CF, and the sintering shrinkage of the particles predominantly hinges on the generation of CF.
研究领域:
材料科学
·
计算化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2017
·Vol. 47
·期 2
·1705-1712
·
IF 1.579
Han Jing,Wang Yan,Tan Shihai,Guo Fu
Electromigration is a major reliability problem in composite solder joints. Due to the anisotropy of the β -Sn crystal structure, the Sn grain orientations present in the solder matrix dominate the principal failure mechanism in solder joints under electric current stressing. In this work, the Cu 6 Sn 5 growth behavior in Cu 6 Sn 5 -reinforced composite solder joints with three different Sn grain orientations was investigated at current density of 10 4 A/cm 2 at room temperature. Micron-sized Cu particles were added to Sn-3.5Ag solder at 2% volume fraction using an in situ method. After current stressing for 528 h, the polarity effect in the composite solder joint was greatest for an angle ( θ ) between the c -axis and electron flow direction of 30°, resulting in higher growth rate of Cu 6 Sn 5 in the solder matrix compared with composite solder joints with θ of 60° or 90°. There were no noticeable changes in the composite solder joint with θ of 90°. The growth behavior of Cu 6 Sn 5 , Cu atomic motion, and Cu diffusivity in the composite solder joints with different Sn grain orientations were analyzed in detail.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2021
·Vol. 12
·期 1
·1-8
·
IF 14.919
Zhang Hui,Xu Tao,Yu Kaihao,Wang Wen,He Longbing,Sun Litao
Atomic diffusion has been recognized as a particularly powerful tool in the synthesis of heterostructures. However, controlled atomic diffusion is very difficult to achieve in the fabrication of individual nanostructures. Here, an electrically driven in situ solid-solid diffusion reaction inside a TEM is reported for the controlled fabrication of two different hetero-nanostructures in the Ag-Te system. Remarkably, the morphology and structure of the as-formed heterostructures are strongly dependent on the path of atomic diffusion. Our experiments revealed that the surface diffusion of Te atoms to Ag nanowires leads to a core-shell structure, while the bulk diffusion of Ag atoms give rise to a Ag 2 Te-Te segmented heterostructure. Heat released by Joule heating caused the surface diffusion process to be replaced by bulk diffusion and thereby determined the structure of the final product. Our experimental results provide an insight into solid-state diffusion reactions under an electric field and also propose a new process for the fabrication of complex nanostructures.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Peng Wei,Hao Bai,Yiwen Liu,Lei Zhuang,Hulei Yu,Yanhui Chu
Achieving superior calcium-magnesium-aluminum-silicate (CMAS) corrosion resistance of high-entropy rare-earth monosilicates (HEREMs) is of great significance to their aerospace use as environmental barrier coating materials. Here, we report the exploration of HEREMs with improved CMAS corrosion resistance through multicomponent synergistic effects. Specifically, bulk HEREMs samples with seven content ratios of rare-earth elements (HEREM- x ) were fabricated, and their CMAS corrosion resistance at 1673 K was systematically investigated. The best CMAS corrosion resistance is found to be achieved in the as-fabricated bulk HEREM-0.1 samples with the formation of the densest apatite protective layer. Further studies show that the dense apatite layer originates from the multicomponent synergistic effects, which increase the stability of the apatite structure and decrease the atomic diffusion rate of rare-earth elements in the CMAS melt.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2024
·
IF 5.2
Yuchuan Feng,Penghui Wang,Nana Wang,Xin Guo,Suxia Ma
Reactive force field molecular dynamics (ReaxFF MD) simulation and experiments were employed to deeply reveal the sintering mechanism of Fe2O3 particles during iron-based chemical looping combustion. The sintering process of Fe2O3 particles was simulated at different temperatures (973–1273 K). The results showed that the temperature increase has limited effect on the structure of Fe2O3 particles and slightly increases the atomic irregularity. The sintering process of Fe2O3 particles can be divided into three stages: the proximity phase, rapid formation, and slow growth of the sintering neck. The temperature increase significantly promotes the sintering process of Fe2O3 particles. The mean-square displacement and Arrhenius equations were used to study the atomic diffusion properties of Fe2O3 particles. The diffusion activation energy of surface atoms is lower than that of inner atoms, implying that the surface atoms have stronger diffusion ability. With the increase of temperature, more Fe atoms diffuse toward the interface of Fe2O3 particles. Increasing the temperature can accelerate the diffusion and enrichment of surface atoms, especially Fe, toward the sintering neck region, resulting in more serious sintering of Fe2O3 particles. ReaxFF MD simulation is in good agreement with the experimental results. Inhibiting the atomic diffusion is the key to improving the antisintering ability of Fe2O3 oxygen carriers.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-10
·
IF 14.7
Zhang Wencong,Li Fan,Li Yi,Song Anran,Yang Kun,Wu Dongchang,Shang Wen,Yao Zhenpeng,Gao Wenpei,Deng Tao,Wu Jianbo
Intermetallic phases with atomic ordering are highly active and stable in catalysts. However, understanding the atomistic mechanisms of disorder-to-order phase transition, particularly in multi-component systems, remains challenging. Here, we investigate the atom diffusion and phase transition within Pd@Pt-Co cubic nanoparticles during annealing, using in-situ electron microscopy and ex-situ atomic resolution element analysis. We reveal that initial outward diffusing Pd partially substitutes Pt, forming a (Pt, Pd)-Co ternary system in the surface region, enabling the phase transition at a low temperature of 400 °C, followed by shape-preserved inward propagation of the ordered phase. At higher temperatures, excessive interdiffusion across the interface changes the stoichiometric ratio, diminishing the atomic ordering, leading to obvious change in morphology. Calculations indicate that the Pd-substitute in (Pt, Pd)-Co system leads to a significantly lower phase transition temperature compared to that of Pt-Co alloy and thus a lower activation energy for atomic diffusion. These insights into atomistic behavior are crucial for future design of multi-component systems.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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