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Flexible Field Emitter for X-ray Generation by Implanting CNTs into Nickel Foil.

Sun B, Wang Y, Ding G - Nanoscale Res Lett (2016)

Bottom Line: By embedding CNT roots into Ni foil using polymer matrix as transfer media, effective direct contact between Ni and CNTs was achieved.As a result, our novel emitter shows relatively good field emission properties such as low turn-on field and good stability.The gray shadow that appears on the sensitive film after being exposed to the radiation confirms the successful generation of X-ray.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory of Micro/Nano Fabrication Technology, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.

ABSTRACT
This paper reports a novel implanting micromachining technology. By using this method, for the first time, we could implant nano-scale materials into milli-scale metal substrates at room temperature. Ni-based flexible carbon nanotube (CNT) field emitters were fabricated by the novel micromachining method. By embedding CNT roots into Ni foil using polymer matrix as transfer media, effective direct contact between Ni and CNTs was achieved. As a result, our novel emitter shows relatively good field emission properties such as low turn-on field and good stability. Moreover, the emitter was highly flexible with preservation of the field emission properties. The excellent field emission characteristics attributed to the direct contact and the strong interactions between CNTs and the substrate. To check the practical application of the novel emitter, a simple X-ray imaging system was set up by modifying a traditional tube. The gray shadow that appears on the sensitive film after being exposed to the radiation confirms the successful generation of X-ray.

No MeSH data available.


Emission current vs. applied voltage curves of the Ni foil. The inset represents the F-N plots derived from the curves of current vs. electric fields
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Fig7: Emission current vs. applied voltage curves of the Ni foil. The inset represents the F-N plots derived from the curves of current vs. electric fields

Mentions: Field emission of CNT arrays on the Ni foil emitter was carried out in a vacuum chamber. An aging process was carried out with an applied voltage of 550 V for 12 h before the test. During the aging process, arcing occurred occasionally. Since CNTs of greater heights contribute to higher field emission current, thermal runaway is more serious at longer CNTs. As a result, longer CNTs became short and vertically standing CNTs with more uniform heights remained on the Ni substrate after the aging process. The emission current vs. applied electric voltage were repeatedly measured (in Fig. 7), and the I-V curves remained almost constant at the repeated field emission tests. The emission current increases monotonically with the applied field. The turn-on field, which is defined as an electric field required to get an emission current of 10 μA, was 1.64 V/μm. We simply consider the area of the hole on the mica spacer as the field emission area, as the mica sheet was closely attached to the field emitter. The area S = π*(Ø/2)2 = 0.071 cm2. With the applied field of 3.13 V/μm, the field emission current of 0.57 mA and the current density of 8.03 mA/cm2 was achieved. In Fig. 7, the emission current curve seems to show a “linear” relation with the applied field from 400 to 450 V. The phenomenon was caused by the current-limiting resistor which shared the voltage of the field emitter in the circuit. The corresponding Fowler-Nordheim (F-N) plot for the flexible emitter is shown in the inset of Fig. 7. All dots on the curve fit a single straight line well, which implies that the field emission process follows the F-N mechanism.Fig. 7


Flexible Field Emitter for X-ray Generation by Implanting CNTs into Nickel Foil.

Sun B, Wang Y, Ding G - Nanoscale Res Lett (2016)

Emission current vs. applied voltage curves of the Ni foil. The inset represents the F-N plots derived from the curves of current vs. electric fields
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940312&req=5

Fig7: Emission current vs. applied voltage curves of the Ni foil. The inset represents the F-N plots derived from the curves of current vs. electric fields
Mentions: Field emission of CNT arrays on the Ni foil emitter was carried out in a vacuum chamber. An aging process was carried out with an applied voltage of 550 V for 12 h before the test. During the aging process, arcing occurred occasionally. Since CNTs of greater heights contribute to higher field emission current, thermal runaway is more serious at longer CNTs. As a result, longer CNTs became short and vertically standing CNTs with more uniform heights remained on the Ni substrate after the aging process. The emission current vs. applied electric voltage were repeatedly measured (in Fig. 7), and the I-V curves remained almost constant at the repeated field emission tests. The emission current increases monotonically with the applied field. The turn-on field, which is defined as an electric field required to get an emission current of 10 μA, was 1.64 V/μm. We simply consider the area of the hole on the mica spacer as the field emission area, as the mica sheet was closely attached to the field emitter. The area S = π*(Ø/2)2 = 0.071 cm2. With the applied field of 3.13 V/μm, the field emission current of 0.57 mA and the current density of 8.03 mA/cm2 was achieved. In Fig. 7, the emission current curve seems to show a “linear” relation with the applied field from 400 to 450 V. The phenomenon was caused by the current-limiting resistor which shared the voltage of the field emitter in the circuit. The corresponding Fowler-Nordheim (F-N) plot for the flexible emitter is shown in the inset of Fig. 7. All dots on the curve fit a single straight line well, which implies that the field emission process follows the F-N mechanism.Fig. 7

Bottom Line: By embedding CNT roots into Ni foil using polymer matrix as transfer media, effective direct contact between Ni and CNTs was achieved.As a result, our novel emitter shows relatively good field emission properties such as low turn-on field and good stability.The gray shadow that appears on the sensitive film after being exposed to the radiation confirms the successful generation of X-ray.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory of Micro/Nano Fabrication Technology, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.

ABSTRACT
This paper reports a novel implanting micromachining technology. By using this method, for the first time, we could implant nano-scale materials into milli-scale metal substrates at room temperature. Ni-based flexible carbon nanotube (CNT) field emitters were fabricated by the novel micromachining method. By embedding CNT roots into Ni foil using polymer matrix as transfer media, effective direct contact between Ni and CNTs was achieved. As a result, our novel emitter shows relatively good field emission properties such as low turn-on field and good stability. Moreover, the emitter was highly flexible with preservation of the field emission properties. The excellent field emission characteristics attributed to the direct contact and the strong interactions between CNTs and the substrate. To check the practical application of the novel emitter, a simple X-ray imaging system was set up by modifying a traditional tube. The gray shadow that appears on the sensitive film after being exposed to the radiation confirms the successful generation of X-ray.

No MeSH data available.