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20 results on '"Wei, Jumeng"'

13. The mechanism and surface engineering of carbon encapsulate defects-rich molybdenum phosphide for the hydrogen evolution reaction in alkaline media

Author

Liu, Bitao, primary, Wang, Jun, additional, Mou, Dedan, additional, Fu, Junchao, additional, Chen, Wenbo, additional, Fu, Zhijian, additional, Qiang, Qinping, additional, Peng, Lingling, additional, Zhao, Lei, additional, Wei, Jumeng, additional, Qiu, Jianbei, additional, and Ma, Chonggeng, additional

Published
2021
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15. SrZn2(PO4)2–TiO2 composite microwave dielectric ceramics with wide tunability range for temperature coefficient of resonant frequency

Author

Zhenzhen Hui, Ding Zhijie, Zhifu Liu, Wei Jumeng, Yu Guo, Junhua Chen, Teng Guo, and Xiangju Ye

Subjects
010302 applied physics, Materials science, Composite number, Analytical chemistry, Sintering, 02 engineering and technology, Dielectric, Crystal structure, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, visual_art, 0103 physical sciences, visual_art.visual_art_medium, Relative density, Ceramic, Electrical and Electronic Engineering, 0210 nano-technology, Temperature coefficient, Microwave
Abstract

A phosphate based composite ceramics system, (1 − x)SrZn2(PO4)2–xTiO2 (0 ≤ x ≤ 0.5), was prepared by the solid-state reaction method, and the relations between the phase composition, crystal structure and microwave dielectric properties were investigated. The results show that only two phases of SrZn2(PO4)2 and TiO2 can be obtained in the whole range of x value, and high relative density can be archived for all compositions as suitable sintering temperatures were applied. In the variation process of phase composition ratio, lower increase of dielectric constant value (

Published
2017

16. Fabrication of ZrO2/rGO nanocomposites by flash sintering under AC electric fields.

Author

Su, Xinghua, Fu, Mengying, An, Gai, Jiao, Zhihua, Tian, Qiang, and Wei, Jumeng

Subjects
ELECTRIC fields, NANOCOMPOSITE materials, GRAPHENE oxide, SINTERING, ALTERNATING currents
Abstract

Ceramic matrix nanocomposites containing graphene possess superior mechanical properties. However, these nanocomposites are very difficult to be prepared using the conventional methods due to severe grain growth and simultaneous degradation of the graphene at high sintering temperatures and long dwell time. Herein, the dense ZrO2/rGO (reduced graphene oxide) nanocomposites are successfully fabricated by flash sintering of the green compacts consisting of ZrO2 nanoparticles and graphene oxide (GO) at 893–951℃ in merely 5 seconds under the alternating current (AC) electric fields of 130–150 V cm−1. The GO can be in situ thermal reduced during the flash sintering. The as‐prepared ZrO2/rGO nanocomposites exhibit excellent mechanical properties. This study presents a green and simple approach to fabricate the dense ceramic matrix nanocomposites reinforced with graphene at low temperatures in a short time. [ABSTRACT FROM AUTHOR]

Published
2021
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17. Simple synthesis of lithium-doped sulfated titania nanoparticles and their high visible light photocatalytic activity under negative bias electrostatic field

Author

Yu Guo, Xiangju Ye, Zhengfa Zhou, Ding Zhijie, Junhua Chen, Teng Guo, Wei Jumeng, and Weibing Xu

Subjects
Materials science, business.industry, General Chemical Engineering, Doping, Analytical chemistry, chemistry.chemical_element, Nanoparticle, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, 0104 chemical sciences, chemistry.chemical_compound, Semiconductor, chemistry, X-ray photoelectron spectroscopy, Photocatalysis, Lithium, 0210 nano-technology, business, Methylene blue, Visible spectrum
Abstract

Li-doped TiO2/SO42− nanoparticles was successfully synthesized via a simple calcinination process in a vacuum environment using Ti(SO4)2 and LiBr as precursors, and were characterized by TEM, XRD, IR, DLS, XPS and UV-vis (DRS). Li doping can reduce the diameters of TiO2 nanoparticles and affect the surface chemical forms and structures. The as-prepared photocatalysts with different LiBr contents exhibited a notably enhanced degradation efficiency for methylene blue, and exhibited the highest photocatalytic activity under UV light when the molar doping ratio of Li was 0.0125. Moreover, the most photocatalytically efficient sample also showed much higher activity for eliminating methylene blue under visible light (380 < λ < 700 nm) by applying a negative bias than P25 and the control samples without applying a negative bias. The introduced negative bias electrostatic fields could not only render TiO2 responsive to visible light, but was also able to increase the lifetime of the photo-excited charges in the doped semiconductor. This provides a facile, fast and universal method to rapidly degrade organic materials based on the Franz–Keldysh effect and the synergetic effects of the electrostatic force.

Published
2016

20. Temperature sensing behavior in Yb3+-Tb3+ and Eu3+ doped Ca2Gd8(SiO4)6O2 phosphors based on upconversion and downshifting luminescence.

Author

Wei, Jumeng, Wei, Huan, Ji, Xingyang, Ren, Shiming, Dai, Haitao, Cheng, Lijun, and Zhang, Jia

Subjects
PHOSPHORS, DETECTORS, TEMPERATURE, LUMINESCENCE, PHYSICS instruments
Abstract

To develop new phosphor materials for optical temperature sensing application, a series of Yb3+-Tb3+ and Eu3+ doped Ca2Gd8(SiO4)6O2 (CGS) phosphors were designed by solid-state reaction method. Upon 980 nm excitation, the green emission of Tb3+ was observed in the CGS:0.8Yb3+, xTb3+ (0.08 ≤ x ≤ 1.2) phosphors, which could be mainly owing to the cooperative energy transfer from Yb3+ to Tb3+. The corresponding upconversion (UC) luminescence mechanism was studied by using the dependence of UC emission intensity on excitation powder. The temperature-dependence indicates that the ratio of the Tb3+ emission intensities of I5D4 and I5D3 changes with temperature, which shows a linear relationship. The high absolute sensitivity was achieved to be about 0.431 K−1. Upon 463 nm excitation, the Eu3+ 5D0,1-7FJ transitions were found in the Eu3+-activated CGS. The investigation on temperature-dependence reveals that with increasing temperature the intensities of 5D0-7FJ transitions decrease but those of 5D1-7FJ transitions increase gradually, owing to the thermally coupled 5D0 and 5D1 levels. The fluorescence lifetime based temperature sensing properties was studied in this sample. [ABSTRACT FROM AUTHOR]

Published
2018
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