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29 results on '"Zhang Zhengjun"'

8. Tailoring plasmonic properties of Ag-SiO2 nanorods and their surface-enhanced Raman scattering activities.

Author

Zou, Sumeng, Wang, Yanfeng, Ning, Shuai, Liu, Yuehua, Xie, Zheng, Zhao, Dongliang, Ling, Yunhan, Wang, Weipeng, and Zhang, Zhengjun

Subjects
SURFACE enhanced Raman effect, RAMAN scattering, NANORODS, NANOPARTICLES, CHEMICAL detectors, METAL nanoparticles
Abstract

Due to a wide range of applications, plasmonic properties of metal nanoparticles have been widely explored, while the understanding of plasmonic behaviors of dielectric-metal composites is still limited. Herein, as a proof of concept, the relationship between compositions and plasmonic behaviors of Ag-SiO2 composites was investigated considering their extensive utilization as SERS substrates. Ag-SiO2 nanorods with regulated compositions were fabricated via glancing angle co-deposition. By increasing Ag relative deposition rate, structure of Ag-SiO2 nanorods evolves from Ag nanoparticles embedded into SiO2 matrix to quasi-one-dimensional Ag structure, inducing plasmon resonance changes over a wide range and corresponding SERS activity variations. Plasmonic resonance resulted from individual Ag nanoparticle, coupling effect of Ag nanoparticles, and quasi-one-dimensional Ag nanorods can be observed successively as Ag content increases in Ag-SiO2 nanorods. Meanwhile, SERS performance of Ag-SiO2 corresponds well with their plasmon behaviors and the maximum SERS signal was obtained from Ag-SiO2 composites with quasi-one-dimensional Ag structure. With the optimization of plasmon and SERS performance of Ag-SiO2 nanorods, we demonstrated the potential use of Ag-SiO2 nanorods in real applications as SERS chemical sensors for the detection of melamine. [ABSTRACT FROM AUTHOR]

Published
2020
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12. Anisotropic and mutable magnetization in Kondo lattice CeSb 2

Author

Zhang, Yun, primary, Zhu, Xiegang, additional, Hu, Bingfeng, additional, Tan, Shiyong, additional, Xie, Donghua, additional, Feng, Wei, additional, Qin, Liu, additional, Zhang, Wen, additional, Liu, Yu, additional, Song, Haifeng, additional, Luo, Lizhu, additional, Zhang, Zhengjun, additional, and Lai, Xinchun, additional

Published
2017
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14. Film growth of pillars of multi-walled carbon nanotubes

Author

Liu Jingguo, Zhang Zhengjun, and Zhao Ye

Subjects
Nanostructure, Scanning electron microscope, chemistry.chemical_element, Nanotechnology, Chemical vapor deposition, Carbon nanotube, Condensed Matter Physics, Catalysis, law.invention, chemistry.chemical_compound, Ferrocene, chemistry, Chemical engineering, Transmission electron microscopy, law, General Materials Science, Carbon
Abstract

Using ferrocene as the catalyst and xylene as the precursor, films of multi-walled carbon nanotubes (CNTs) that are well aligned can be synthesized on flat substrates by chemical vapour deposition. Here we report that, by controlling the growth speed of CNTs at specific catalyst/carbon ratios, vertically aligned pillars of densely packed nanotubes with uniform diameters (within 10?30??m) and lengths of up to 0.3?0.4?mm can be fabricated on a large scale on planar SiO2 substrates, forming a continuous film. The growth mechanism of the pillars was also investigated by observing the growth of CNTs at different growth stages.

Published
2003
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15. Room temperature ferromagnetism in un-doped amorphous HfO 2 nano-helix arrays

Author

Zhang Zhengjun, LI Zhengcao, Zhan Peng, Wang Wei-Peng, Xie Zheng, and Xie Qian

Subjects
Photoluminescence, Nanostructure, Materials science, Condensed matter physics, Ferromagnetism, Magnetism, Doping, General Physics and Astronomy, Nanotechnology, Thin film, Atmospheric temperature range, Amorphous solid
Abstract

Amorphous HfO2 nano-helix arrays with different screw pitches were fabricated by the glancing angle deposition technique. Room temperature ferromagnetism was achieved in this undoped amorphous HfO2 nanostructure, which is attributed to singly charged oxygen vacancies. The different magnetic behavior and photoluminescence in flat film and nano-helix arrays originate from the distinction of defect components. This study could facilitate the understanding of ferromagnetism origin in undoped HfO2, it also suggests a possible way to alter the intrinsic defects in amorphous HfO2.

Published
2015
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28. Optical and dielectric properties of a nanostructured NbO2 thin film prepared by thermal oxidation.

Author

Zhao, Ye, Zhang, Zhengjun, and Lin, Yuanhua

Subjects
THIN films, SOLID state electronics, THICK films, RAMAN effect
Abstract

Nanostructured NbO2 films have been prepared on Si (001) substrates by thermally oxidizing a spiral niobium coil in a vacuum of the order of 10-2 Torr. The film consists of single-crystalline NbO2 nanoslices (several tens of nanometres thick) that are aligned with each other. When excited with 512 nm light, the NbO2 film showed room-temperature photoluminescence around 700 and 825 nm. It also exhibits, interestingly, excellent dielectric properties in the frequency range from 1 kHz to 10 MHz. It has a dielectric constant comparable to that of SiO2 and Si3N4, is independent of the frequency applied, and has a dielectric loss of less than 1% in the measured frequency range, making NbO2 a potential material for applications into MOS devices. The Raman spectrum of the NbO2 phase, for the first time, is also reported. [ABSTRACT FROM AUTHOR]

Published
2004
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