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- Zhan, Zhaoyao, 1983, et al.
(author)
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Pore-free bubbling delamination of chemical vapor deposited graphene from copper foils
- 2015
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In: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 3:33, s. 8634-8641
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Journal article (peer-reviewed)abstract
- The electrolytic bubbling-assisted transfer of graphene from metal catalysts in chemical vapor deposition provides a high efficiency, low cost and environmental benign alternative to the traditional chemical etching method. Despite its high potential, the yield of bubbling delamination is yet low, mainly due to the induced pores in the graphene after the transfer. It is found that water and protons transported through the poly(methyl methacrylate) (PMMA) supporting layer play a critical role in pore formation. Once water and protons reach the PMMA-graphene interface before delamination is finished, the protons permeate the graphene and form trapped hydrogen bubbles between the graphene and the metal. The built-up gas pressure inside the bubbles is high enough to crack the PMMA/graphene sheet, thereby creating pores in the graphene. An optimized PMMA layer not only reduces trapped hydrogen bubble generation, but it is also mechanically stronger preventing cracking. This contributes significantly to the pore-free electrolytic bubbling-assisted delamination of graphene.
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| 3. |
- Zhang, Bing, 1982, et al.
(author)
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Metallic 3-D Printed Antennas for Millimeter- and Submillimeter Wave Applications
- 2016
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In: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 6:4, s. 592-600
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Journal article (peer-reviewed)abstract
- This paper presents a study to use the metallic three dimensional (3-D) printing technology for antenna implementations up to 325 GHz. Two different printing technologies and materials are used, namely binder jetting/sintering on 316L stainless steel and selective laser melting (SLM) on Cu-15Sn. Phases, microstructure, and surface roughness are investigated on different materials. Balancing between the cost and performance, the manually polished Cu-15Sn is selected to develop a series of conical horn antennas at the E-(60-90 GHz), D-(110-170 GHz), and H-band (220-325 GHz). Good agreement is observed between the simulated and measured antenna performance. The antennas' impedance bandwidth (vertical bar S-11 vertical bar < -20 dB) cover the whole operational band, with in-band gain of > 22.5, > 22, and > 21.5 dBi for the E-, D-, and H-band antennas, respectively. Compared with the traditional injection molding and micromachining for metallic horn antenna implementation, the 3-D printed metallic horn antenna features environmental friendliness, low cost, and short turn-around time. Compared with the nonmetallic 3-D printed antennas, they feature process simplicity and mechanical robustness. It proves great potential of the metallic 3-D printing technology for both industrial mass production and prototyping.
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