JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Wuyang Song,Youjun Lu,Chuyun Wang,Jiahao Xu,Xiang Liu,Bo Ma,Yanmin Wang,Bo Wu
The cell structures and mechanical properties (i.e., hardness, Young's modulus , shear modulus , and Poisson's ratio) of (Hf 0.2 Zr 0.2 Ti 0.2 Nb 0.2 Ta 0.2 )C (HEC) and (Hf 0.2 Zr 0.2 Ti 0.2 Nb 0.2 Ta 0.2 )N (HEN) high-entropy ceramics were simulated by special quasi-random structure (SQS) and general random structure (GRS) with atomic occupation preference based on the first-principles density functional theory. The results show that compared to SQS, the cell structure constructed by GRS is more realistic, which is verified via scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive spectroscopy. The mechanical properties simulated by GRS were also determined by microhardness and dynamic elastic modulus testers. The hardness, Young's modulus，shear modulus and Poisson's ratio predicted by GRS are 23.07 GPa, 449.71 GPa, 183.28 and 0.227 for HEC and 22.96 GPa, 413.71 GPa, 162.47 and 0.241 for HEN, which are in a reasonable agreement with the measured results (i.e., 22.05 ± 0.32 GPa, 433 ± 12 GPa, 172 ± 18 GPa, 0.21 for HEC and 22.12 ± 0.13 GPa, 372 ± 23 GPa, 158 ± 11 GPa, 0.23 for HEN). This work can provide a promising reference for preparing high-entropy non-oxide ceramics via the prediction.
研究领域:
材料科学
·
计算材料学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2023
·
IF 10.9
Pingsheng Lai,Xuan Ge,Caijuan Shi,Jianqiang Li,Fan Yang,Wenquan Lu,Jianguo Li,Qiaodan Hu
Despite its significance in both fundamental science and industrial applications, the glass-forming transition in the Al 2 O 3 -Y 2 O 3 (AY) refractory system is not yet fully understood due to the elusive structure evolution upon cooling. Here, atomic-scale structural changes in AY-bearing melts with different compositions and temperatures are tracked by employing in situ high-energy synchrotron X-ray diffraction and empirical potential structure refinement simulation. We find that the glass-forming abilities (GFA) of AY-bearing melts are intriguingly correlated with the dependence of melt structure on temperature. In the case of the Al 2 O 3 and Y 3 Al 5 O 12 (YAG), the observed large structural changes from superheating to undercooling melt (i.e., higher temperature susceptibility) correspond to a low GFA. Conversely, the 74Al 2 O 3 –26Y 2 O 3 (AY26) melt, with the smallest temperature susceptibility, exhibits the highest GFA. Simulation models illustrate that the temperature susceptibility of melt is associated with its atomic arrangement, especially the stability of cation-cation pairs. A balanced network (in AY26 melt), where the unsteady OAl 3 tri-clusters are minimized and steady apex-to-apex connections between adjacent network units are abundant, contributes to stabilizing cationic interactions. This, in turn, fosters the formation of large-sized Al-O-Al rings, which topologically facilitates the subsequent glass-forming transition. Our findings provide new structural insight into the GFA of AY-bearing melts and may expand to other unconventional glass-forming systems to accelerate glassy materials design.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Energy
·
2023
·
IF 9.3
Yuhang Gao,Xu Zhang,Chaogang Ban,Ran Feng,Jixiang Hou,Jiazhi Meng,Guo Yang,Chunlang Gao,Lu Xia,Peijie Ma,Kaiwen Wang,Xianlin Qu
A typical photocatalytic H 2 O 2 production reaction primarily comprises three processes: photoabsorption, electron–hole separation and transfer, and surface oxygen reduction reaction. Previous researches have focused on revealing the origin of the facet effect in photocatalysis. However, an comprehensive understanding of the structure–activity relationship for facet effect at atomic scale remains limited. Herein, we provide fundamental insights into photocatalytic H 2 O 2 production performance of three types of TiO 2 with predominantly exposed (101), (100), or (001) facets. The TiO 2 nanosheets with exposed (001) facet exhibit the highest H 2 O 2 yield rate of 649.2 μmol g -1 h -1 , which is 29.2 and 5.2 times higher than those of TiO 2 with (101) facet and (100) facet, respectively. Band alignment, charge carrier behavior and surface reaction are studied systematically and correlated with unique surface atom arrangement. Even with narrowed light-response range, short charge carrier lifetime, inferior charge separation, and inconspicuous specific surface area, the (001) facet exposed TiO 2 still performs best. The experimental results and density functional theory (DFT) calculations reveal that the under-coordinated Ti atoms on (001) surface serve as active sites and have strong interaction with oxygen molecule, while the Ti atoms on (101) and (100) surface can hardly adsorb and activate oxygen molecule. Hence, we suggest that the significantly lowered barrier for oxygen molecule adsorption and activation results from intrinsic surface sites rather than band-alignment and charge carrier behavior plays the principal role in this case. This work may provide semiquantitative insights into the origin of facet effect in photocatalysis.
研究领域:
材料科学
·
化学
·
催化
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Mingming Li,Yue Gong,Jiaqiang Wen,Zhengda Li,Yanjie Wang,Tao He
The development of advanced photoactive materials has aroused widespread interest, but is severely plagued by the inherent narrow photo-responsive range and rapid recombination of electrons and holes. In this study, the unconventional BiOBr nanosheets decorated with Bi 0 and oxygen vacancies (OVs) are successfully synthesized through a facial one-pot hydrothermal method, followed by heat treatment. Cetyltrimethylammonium bromide and mannitol contribute to the selective exposure of (001) and (010) facets, respectively. The absence of the outermost Br atoms facilitates the simultaneous generation of OVs and Bi 0 on the surface during heating, forming the Schottky junction. The synergy of SPR in the Bi 0 metal, OVs and Schottky junction can effectively enhance the light absorption and charge separation. This work proposes and verifies a feasible approach to construct defects in-situ by regulating the crystal facets and manipulating the surface atomic arrangement and coordination.
研究领域:
材料科学
·
光化学
·
纳米技术
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Environmental Science & Engineering
·
2021
·Vol. 15
·期 5
·1-9
·
IF 4.357
Hu Guowen,Zhang Zeqi,Zhang Xuan,Li Tianrong
The magnetic nanoparticles that are easy to recycle have tremendous potential as a suitable catalyst for environmental toxic dye pollutant degradation. Rationally engineering shapes and tailoring the size of nanocatalysts are regarded as an effective manner for enhancing performances. Herein, we successfully synthesized three kinds of MnFe 2 O 4 NPs with distinctive sizes and shapes as catalysts for reductive degradation of methylene blue, rhodamine 6G, rhodamine B, and methylene orange. It was found that the catalytic activities were dependent on the size and shape of the MnFe 2 O 4 NPs and highly related to the surface-to-volume ratio and atom arrangements. Besides, all these nanocatalysts exhibit selectivity to different organic dyes, which is beneficial for their practical application in dye pollutant treatment. Furthermore, the MnFe 2 O 4 NPs could be readily recovered by a magnet and reused more than ten times without appreciable loss of activity. The size and shape effects of MnFe 2 O 4 nanoparticles demonstrated in this work not only accelerate further understanding the nature of nanocatalysts but also contribute to the precise design of nanoparticles catalyst for pollutant degradation.
研究领域:
环境科学
·
纳米技术
·
催化
·
污染物降解
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）