Minerals
·
2022
·Vol. 12
·期 8
·994
·
IF 2.818
Qiuyu Zeng,Jun Xie,Wei Zhou,Jinbo Zhu,Liangliang Liu,Jianqiang Yin,Wenliang Zhu
The distortion process of kaolinite annealed from 25 °C to 550 °C for different holding times can be characterized using a thermogravimetric/differential scanning calorimeter (TG/DSC) for thermal analysis, X-ray diffraction (XRD) for establishing the crystal structure, the Fourier transform infrared spectrum (FTIR) for identifying the functional groups, and a scanning electron microscope (SEM) for establishing the microstructure. Dehydroxylation is the main reaction during annealing from 25 °C to 550 °C and leads to kaolinite crystal distortion. A stable crystal structure during distortion was obtained by optimizing the bulk phase with quantum chemistry. Then, the crystal structure was studied by using ab initio multiple scattering calculations for X-ray absorption of the fine structure (XAFS). The results of X-ray absorption near the edge structures (XANES) determined that peak shifts and intensity phases slightly increased. The crystal structure distortion of kaolinite during annealing can be explained by the experimental and simulation results. This work provides theoretical support for identifying kaolinite with different degrees of distortion and has the potential for further developments in coal gangue separation.Keywords:coal and gangue;kaolinite;distortion;multiple scattering computation
研究领域:
矿物学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER ENGINEERING AND SCIENCE
·
2024
·
IF 3.2
Peng Zhu,Chundi Pan,Jianxin Liu,Luyao Feng,Huapeng Zhang,Ning Ma,Fang-Chang Tsai
During the use, storage, or cleaning of polyetherimide (PEI) solutions, undesired white films often appear. In this study, equivalent experiments of PEI solutions involving room temperature evaporation and solvent exchange with water are conducted to simulate their air exposure and water washing processes, respectively. Specifically, we focus on investigating the phenomenon and mechanism of white appearance in their films from room temperature evaporation with a cellular-like porous structure and solvent exchange films that exhibit a finger-like porous structure. Results obtained from FE-SEM, UV–Vis spectroscopy, and Datacolor reflectance spectrophotometer indicate that both types of porous structures exhibit long-range disorderliness, leading to multiple scattering of incident light and high reflectance across the visible light spectrum resulting in a white appearance. Furthermore, due to different structures caused by phase separation, mechanical properties of solvent exchange films are significantly inferior compared with those of films from room temperature evaporation. Finally, we verify the universality of these mechanisms for white film formation in PEI through experiments using PS and PMMA. This study provides insights into efficient utilization of polymer solutions and offers new strategies for biomimetic preparation of white films. Highlights White cellular-like porous films were prepared by solvent evaporation method. White finger-like porous films were produced through solvent exchange by water. Multiple scattering caused by above porous structures led to white appearance. Finger-like porous films with nanosphere as the basic scatter unit had a luster. Universality of both white formation mechanisms was verified by PMMA and PS.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2022
·Vol. 32
·期 44
·2201927
·
IF 19.924
Sixiang Zhao,Han Zhu,Jicun Lu,Ming Li,Liancheng Zhao,Lei Zhou,Liming Gao
Chirality generated by the co-assembly of plasmonic nanoparticles (NPs) and chiral photonic crystals has attracted broad interest owing to its strong optical activities. However, it is difficult to understand the physical mechanism of the unique chiral responses, for surface-plasmon-mediated circular dichroism (SP-CD) is a hybrid response generated from chiral plasmonic–photonic systems. This study aims to investigate how chirality is generated by this system and the relationship between SP-CD and plasmonic–photonic couplings. Here, quasi-continuous plasmon bands are designed to interact with the different photonic bandgaps of cellulose nanocrystals (CNCs). In spectroscopy and simulation, characteristic SP-CD shape lines derived from the extinction dispersion of plasmonic NPs for circularly polarized light in the CNCs are observed. It is demonstrated that this plasmonic chirality is determined by the coupling states and originates from a multiple scattering combination of plasmonic NPs under a chiral excitation field. A novel transfer-matrix method is established to perform numerical analysis of this complex multiple scattering efficiently. This study is expected to offer a deep insight into chiral plasmonic–photonic systems.
研究领域:
光学
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材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2024
·
IF 6.3
Chuanxin Yang,Ronghui Han,Xiaoyu Guo,Shufen Zhang,Bingtao Tang,Yuang Zhang
Passive radiative cooling technology has received extensive attention as an environmentally friendly cooling solution. However, existing radiative coolers often suffer from complexities in preparation and high costs, limiting their practical applications. Here, a novel porous structure with randomly distributed microspheres is fabricated in a low-cost and simple method known as solvent volatilization-induced phase separation, employing polyvinylidene fluoride (PVDF) and monodispersed SiO 2 microspheres. Utilizing the regulation of parameters such as the size of the pores and microspheres, controllable multi-scattering of light by the microstructures is achieved. The porous PVDF/SiO 2 film, with an average solar reflectance of 93.8% and an average atmospheric window emissivity of 0.958, is self-supporting and exhibits excellent flexibility and mechanical strength. When applied to closed and windowed models, the porous PVDF/SiO 2 film effectively lowers the internal temperatures by an average of 7.0 °C and 4.6 °C in summer, respectively, and by an average of 6.7 °C and 4.4 °C in spring. This work provides a viable strategy for achieving efficient radiative cooling and improving building energy management in a simple, cost-effective, and scalable manner.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Weidong Zhang,Yuan Zheng,Xue Zhang,Qing Zhu,Lili Tian,Hongjing Wu,Hongxia Yan,Shuhua Qi
Graphene nanoplatelets (GNPs) based materials are promising and low-cost absorbers. To develop new varieties of these absorbers, two kinds of GNPs/ZnO nanocomposites (GNPs/ZnO nanorod arrays and GNPs/ZnO nanoneedles) were synthesized in this paper, and the microwave absorption performance (MAP) together with the relevant mechanism were investigated based on the different microstructures, followed by the discussion of the growth mechanism of ZnO nanorod and nanoneedle. The result reveals that GNPs/ZnO nanorod arrays have strong reflection loss (RL) up to −44.8 dB, and effective attenuation bandwidth (RL˂-10 dB) of 4.65 GHz. While, GNPs/ZnO nanoneedles possess effective attenuation bandwidth of 6.7 GHz that covered entire X-band, and the superb RL was −15.3 dB. According to the detail analysis, we found that the pathways of attenuation EM wave are the same, and the differences between each other are responsible for the different intensity of interface polarization and multiple-scattering, due to the different microstructures.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）