ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Wen She,Han Bi,Zhiwei Wen,Qinghe Liu,Xuebing Zhao,Jie Zhang,Renchao Che
A tunable response frequency is highly desirable for practical applications of microwave absorption materials but remains a great challenge. Here, hollow lightweight polydopamine@α-MnO2 microspindles were facilely synthesized with the tunable absorption frequency governed by the aspect ratio. The size of the hard template is a key factor to achieve the unique shape; the polymer layer with uniform thickness plays an important role in obtaining spindles with homogeneous size. With the aspect ratio increasing, the maximum reflection loss, as well as the absorption bandwidth (<−10 dB), increases and then decreases; meanwhile, the microwave absorption band shifts to the low frequency. The optimized aspect ratio of the cavity about the hollow polydopamine@α-MnO2 microspindles is ∼2.8. With 3 mm thickness at 9.7 GHz, the strongest reflection reaches −21.8 dB, and the width of the absorbing band (<−10 dB) is as wide as 3.3 GHz. Via electron holography, it is confirmed that strong charge accumulates around the interface between the polydopamine and α-MnO2 layers, which mainly contributes to the dielectric polarization absorption. This study proposes a reliable strategy to tune the absorption frequency via different aspect ratio polymer@α-MnO2 microspindles.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NANOTECHNOLOGY
·
2020
·Vol. 31
·期 19
·194001
·
IF 3.551
Bo Wang,Xin Huang,Xiao-Nan Zhou,Qiang Zhi,Liu-Cheng Hao,Zi-Xuan Li,Shan Zhao,Bao-Qiang Hou,Jian-Feng Yang,Kozo Ishizaki
One-dimensional Si3N4 nanostructures are desirable for constructing nanoscale electric and optoelectronic devices due to their peculiar morphologies. Herein, a facile and environmentally friendly catalyst-free method is proposed to synthesize ultra-long single crystal α-Si3N4 nanobelts via carbothermal nitridation of carbon nanotubes at 1750 °C. The obtained α-Si3N4 nanobelts with a flat surface (thickness of ∼150 nm, length of several millimeters) exhibited an extremely high aspect ratio, perfect crystal structure, and high specific surface area of 7.34–10.09 m2 g−1. In addition, the width was increased from approximately 80 nm to 8 μm by increasing the holding time from 1 to 3 h. The nanobelt formation was governed by the vapor–solid (VS) reaction between SiO vapor, N2 and carbon nanotubes, and the vapor–vapor reaction between SiO, CO and N2. The former was responsible for the initial nucleation and successive base-growth of α-Si3N4 nanotubes. The latter additionally contributed to the nanorod and subsequent proto-nanobelt formation and to the growth of the nanobelts. During high-temperature annealing at 1750 °C, the original Si3N4 nanotubes gradually transformed into nanorods, and, finally, nanobelts with stable shapes as a result of surface energy minimization.
研究领域:
材料科学
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纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INORGANIC CHEMISTRY COMMUNICATIONS
·
2021
·
IF 2.495
Yuyue Guo,Yangfei Hu,Xiaojiong Luo,Shudong Lin,Jiwen Hu,Yuan Liu
The modified polyol method for the production of high aspect ratio silver nanowires (AgNWs) has received significant attention from many researchers due to its convenience and simplicity. Poly(vinylpyrrolidone) (PVP) is generally used as a template and capping agent in this method to stabilize the nanowires. However, the influence of different PVP molecules on the growth mechanism of AgNWs is not well understood. Given this, we designed a series of orthogonal experiments to obtain nanowires with an aspect ratio of 2500 and investigated the influence of PVP on the growing process leading to AgNWs. According to the results and previous studies, we proposed that relatively long PVP chains are apt to bond strongly with Ag atoms through their numerous carbonyl groups and thus promote the formation of long AgNWs. While promoting the growth in the AgNW's length, this mechanism of action restricts the growth of the diameter, thus leading to the formation of thin AgNWs with high aspect ratios as the final products.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
POLYMER COMPOSITES
·
2024
·
IF 4.8
Zhengjia Ji,Shenqi Wang,Wanyue Luo,Hao Wu,Xiaolei Li,Hongyun Jin,Shuen Hou
The development and design of fillers aid in improving the tribological performances of friction materials. Herein, the effects of the aspect ratio of mullite whisker on the tribological properties were studied. Mullite whiskers were prepared by the sol–gel process and the aspect ratio of the whisker was controlled by introducing aluminum fluoride (AlF 3 ). The aspect ratio increased significantly at first and then decreased with increasing the contents of AlF 3 . The experimental results show that higher aspect ratio whiskers stabilized the friction coefficient while increased the wear rate. In addition, the composite with mullite whisker grown in excessive AlF 3 (20%) resulted in a higher friction coefficient compared to adding inadequate AlF 3 (10%). The Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) results indicated that higher aspect ratio of whisker was more likely to fall off from matrix which sequentially being compacted and formed contact plateaus during the friction process. In conclusion, it was found that abrasive wear and adhesive wear were the dominant wear mechanism. Highlights The aspect ratio of mullite whisker was controlled within the range of 6 ~ 21. The tribological properties of whiskers reinforced composites were studied. The morphology of the mullite whisker affects the friction stability. The flaky mullite whisker can improve wear resistance of the composites.
研究领域:
材料科学
·
摩擦学
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Baolin Xia,Ruohan Shi,Wei Wang,Weijun Peng,Yijun Cao,Yukun Huang,Guixia Fan
A substantial stockpile of phosphogypsum (PG) not just consumes land resources, but also poses environmental contamination risks. Herein, the conversion of PG into high-value α-hemihydrate gypsum (α-HH) whisker by the atmospheric pressure salt solution method with simple process, high efficiency and low energy consumption was investigated. Sodium nitrate was found to accelerate the conversion of PG into α-HH, and sorbitol could modify the α-HH into rod-like morphology with high aspect ratios . The α-HH whiskers with an average length of 96.28 µm and an average aspect ratio of 25.47 were prepared within 1.5 h under the optimal parameters of 80 ℃, sodium nitrate-30 wt%, PG-12 wt%, and sorbitol-1 wt%. The modulation mechanism was that hydroxyl groups in sorbitol formed strong hydrogen bonds with the sulfate groups on the lateral of the crystals, which promoted the growth of α-HH along the c-axis. Moreover, the filtrate could be effectively recycled by adding salt medium and crystallization modifier. Such technique provides a theoretical basis for the high-value utilization of PG.
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
NANOTECHNOLOGY
·
2020
·Vol. 32
·期 10
·105710
·
IF 3.551
Lu Zhang,Fuliang Jiang,Bisheng Wu,Chencheng Lv,Minghua Wu
Silver nanowires (AgNWs), appear as an extremely promising candidate for the next generation of flexible transparent conductive electrodes (FTCEs). However, the performance of AgNWs-FTCEs was severely limited by the aspect ratio of AgNWs, while it was still a big challenge to fabricate AgNWs with high aspect ratio nowadays. To improve the aspect ratio of AgNWs, bromide ion (Br−), cupric ion (Cu2+) and polyvinylpyrrolidone (PVP, Mw ≈ 1300 000) which are beneficial for the synthesis of high aspect ratio AgNWs, were introduced in this article. The high quality and uniform AgNWs with the average diameter of 77.6 nm and the aspect ratio above 2000 were fabricated via a one-step solvothermal method. The effects of reaction time, molar ratio of AgNO3 to PVP and the concentration of CuBr2 on the aspect ratio of AgNWs were discussed. The mechanism of the synthesis of high aspect ratio AgNWs was explored. After that, the prepared AgNWs were spin-coated on the surface of PET film, the FTCEs based on the ultra-high aspect ratio AgNWs without any post-treatments exhibits relatively high transmittance, low haze and low sheet resistance, and the AgNWs have little effect on the optical performance of pristine PET film. The outstanding performance of the prepared FTCEs indicated that the ultra-high aspect ratio AgNWs are ideal materials in the application of FTCEs, and the method of fabricating AgNWs could provide a direction to the high aspect ratio AgNWs.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NANOTECHNOLOGY
·
2020
·Vol. 31
·期 14
·145601
·
IF 3.551
Rui Li,Xinyan Li,Ping-An Yang,Haibo Ruan
High-performance iron nanowires have attracted wide attention from researchers due to their 'controllable' arrangement distribution by magnetic fields. In this paper, a simple magnetic field assisted in situ reduction method was proposed to synthesize Fe NWs with high aspect ratio, small-diameter, and good dispersion. A detailed parametric study determining the relationship among the final morphologies of the products and magnetic field, injection sequence of sodium borohydride that was injected into ferrous sulfate heptahydrate, reactant concentration, and injection rate is presented. The as-synthesized Fe NWs were analyzed by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and vibrating sample magnetometry. A plausible mechanism for the formation of high-aspect-ratio Fe NWs is proposed. The SEM images showed the dependence of the NWs morphology and aspect ratio on synthesis parameters. Magnetic field and injection sequence showed considerable influences on the synthesis of high-aspect-ratio Fe NWs. In the absence of magnetic field or with the changes in injection sequence, only the Fe flakes were obtained. The NWs diameter decreased, and the aspect ratio increased with the increase in injection rate. The FeSO4·7H2O and NaBH4 concentration considerably influenced the aspect ratio of the product, which increased first, decreased, and then increased again with the increase in FeSO4·7H2O concentration. Meanwhile, the product aspect ratio increased and then became saturated with the increase in NaBH4 concentration Thus, an optimum synthesis process was obtained, with the average aspect ratio of 350, and the average diameter of 60 nm. The results reported in this paper provide a basis for optimizing the growth of Fe NWs by magnetic field-assisted method.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SYNTHETIC METALS
·
2022
·
IF 4
Baili Chen,Zhen Lei,Mingshi Zhao,Pengchao Si
Silver nanowire (AgNWs) with a fine diameter (< 20 nm) and large aspect ratio (>1000) is one of the requirements for good optoelectronic properties of a transparent conductive film . Herein we report a facile and high yield modified polyol synthesis of AgNWs with average diameters of ∼ 17 nm, aspect ratios up to 2600. And the synthesized AgNWs were applied in flexible transparent conductive films (TCF). Some crucial factors, such as illumination, solvent, and stirring impacting the diameter, and yield of AgNWs were discussed in detail. Illumination is the main factor that impact the yield of AgNWs. The probable growth mechanism of AgNWs was proposed. The sheet resistance of the AgNWs was 92 Ω/sq and the transmittance and haze were 90 % and 1.74 %, respectively.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CELLULOSE
·
2023
·Vol. 30
·期 9
·5607-5622
·
IF 5.7
Zhang Kecan,Li Jing,He Liang,Zhou Huajing,Guan Qingqing,Chen Keli,Shan Shaoyun,Hu Tianding
Cellulose nano/microfibres (CNFs/CMFs) with high aspect ratio were essential for mechanical strength and flexibility properties. In this study, the tobacco stem was employed as raw material for delignification with soda-oxygen (SO). By comparison with the caustic soda-anthraquinone (SAQ) treatment, based on process performance including pulp yield, residual lignin and fibre characteristics, the two-stage delignification process with total alkali 15% was selected for further preparing CNFs/CMFs with ultrasonication. Results showed that the aspect ratio of highly homogeneous CNFs/CMFs could achieve as ultra-high as 17,645. FTIR and XRD results showed that hemicellulose and lignin in CNFs/CMFs were widely removed, and the crystallinity was about 62%. TGA results exhibited that the degradation temperature was significantly enhanced to 330.2 °C. Finally, the CNF/CMF-based film was prepared and its folding endurance, tensile breaking strength, and burst strength could achieve 136, 61.28 N m/g, 278 kPa m 2 /g. The production of CNFs/CMFs from underutilized tobacco stems provided the potential to add value for industrial waste.
研究领域:
材料科学
·
生物质利用
✓ 已验证
产品关联
DOI
高影响因子
SENSORS
·
2018
·Vol. 18
·期 10
·3458
·
IF 2.475
Chao Zhuang,Yifan Xu,Ningsheng Xu,Jinxiu Wen,Huanjun Chen,Shaozhi Deng
Plasmonic gold nanorods play important roles in nowadays state-of-the-art plasmonic sensing techniques. Most of the previous studies and applications focused on gold nanorods with relatively small aspect ratios, where the plasmon wavelengths are smaller than 900 nm. Gold nanorods with large aspect ratios are predicted to exhibit high refractive-index sensitivity (Langmir 2008, 24, 5233–5237), which therefore should be promising for the development of high-performance plasmonic chemical- and bio-sensors. In this study, we developed gold nanorods with aspect ratios over 7.9, which exhibit plasmon resonances around 1064 nm. The refractive index (RI) sensitivity of these nanorods have been evaluated by varying their dielectric environment, whereby a sensitivity as high as 473 nm/RIU (refractive index unit) can be obtained. Furthermore, we have demonstrated the large-aspect-ratio nanorods as efficient substrate for surface enhanced Raman spectroscopy (SERS), where an enhancement factor (EF) as high as 9.47 × 108was measured using 4-methylbenzenethiol (4-MBT) as probe molecule. Finally, a type of flexible SERS substrate is developed by conjugating the gold nanorods with the polystyrene (PS) polymer. The results obtained in our study can benefit the development of plasmonic sensing techniques utilized in the near-infrared spectral region.Keywords:large aspect ratios;gold nanorods;refractive index sensitivities;SERS;plasmonic sensing
研究领域:
纳米技术
·
光学
·
化学传感器
·
生物医学工程
✓ 已验证
DOI
PubMed
高影响因子
ACS Sustainable Chemistry & Engineering
·
2024
·
IF 7.1
Guangrui Ma,Wenqi Yin,Zhijun Shi,Yan Xu,Guang Yang
Carboxymethylation-modified cellulose nanofibrils (CMCNF) were prepared from bamboo fibers through a pretreatment process using a ternary deep eutectic solvent (DES) system consisting of chloroacetic acid, urea, and choline chloride. Grinding treatment was also employed. The properties of the resulting CMCNF were characterized using various analytical instruments including a fiber image analyzer, field-emission scanning electron microscope, X-ray diffractometer, and atomic force microscope. The results indicated that ternary DES pretreatment has the capability to carboxymethylate-modify the raw fiber material while maintaining the crystalline structure of cellulose. Additionally, it induced a wetting and swelling effect on the fibers, leading to the successful disruption of strong hydrogen bonds and the rapid production of cellulose nanofibrils during mechanical treatment. The carboxymethylation alteration enhanced the ability of the resultant CNF to disperse and increased the stability of the suspension. Furthermore, extending the duration of DES pretreatment enhances the process of fiber fibrillation and diminishes fiber polymerization. The CMCNF produced exhibited a high aspect ratio, with diameters ranging from 10 to 50 nm and lengths extending to a few micrometers. This study presents a novel approach and concept for producing carboxymethylated nanofibrillated cellulose. It also introduces a straightforward, environmentally friendly, and effective method for mass production of bamboo pulp nanofibrillated cellulose. This advancement is anticipated to enhance the processing and utilization of bamboo fiber resources, thereby contributing to an increased overall value.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2017
·
IF 3.454
Fei Zuo,Fan Meng,Dong-Tao Lin,Jun-Jie Yu,Hong-Jian Wang,Shen Xu,Wei-Ming Guo,Carmen Cerecedo,Víctor Valcárcel,Hua-Tay Lin
A novel composite of 12 mol% CeO 2 -stablized tetragonal ZrO 2 reinforced with Al 2 O 3 whiskers (designated as Ce-TZP/A w ) has been prepared and studied in this work. The objective of this investigation was to systematically study the influence of whisker-aspect-ratio on the densification behaviors, microstructure evolution, and mechanical properties of Ce-TZP/A w composite. Results showed that the sintered density of composite increased and the grain growth tended to diminish with the decrease in whisker aspect radio. Both the fracture toughness and flexural strength reached maximum values of 475 ± 12 MPa and 11.4 ± 0.2 MPa m 1/2 , respectively at a whisker aspect ratio of about 12. It was also observed that the fracture toughness, flexural strength and tetragonal to monoclinic ZrO 2 transformation of the dual-phase composite exhibited similar variation trend as a function of the whisker-aspect-ratio, which suggested that the stress-induced phase transformation should be the main toughening and strengthening mechanism in the Ce-TZP/A w composite.
研究领域:
材料科学
·
力学
✓ 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）