Enhanced field emission from carbon nanotubes with a thin layer of low work function barium strontium oxide surface coating

2007 ◽  
Vol 25 (6) ◽  
pp. 1785 ◽  
Author(s):  
Feng Jin ◽  
Yan Liu ◽  
Christopher M. Day ◽  
Scott A. Little
Keyword(s):  
Carbon Nanotubes ◽  
Thin Layer ◽  
Work Function ◽  
Field Emission ◽  
Surface Coating ◽  
Oxide Surface ◽  
Strontium Oxide ◽  
Barium Strontium

A New Thermionic Cathode Based on Carbon Nanotubes with a Thin Layer of Low Work Function Barium Strontium Oxide Surface Coating

2008 ◽  
Vol 1142 ◽  
Author(s):  
Feng Jin ◽  
Yan Liu ◽  
Scott A Little ◽  
Chris M Day
Keyword(s):  
Work Function ◽  
Current Density ◽  
Enhancement Factor ◽  
Thermionic Emission ◽  
Field Enhancement ◽  
Oxide Coating ◽  
Emission Current Density ◽  
Emission Current ◽  
Strontium Oxide ◽  
Barium Strontium

ABSTRACTWe have created a thermionic cathode structure that consists of a thin tungsten ribbon; carbon nanotubes (CNTs) on the ribbon surface; and a thin layer of low work function barium strontium oxide coating on the CNTs. This oxide coated CNT cathode was designed to combine the benefits from the high field enhancement factor from CNTs and the low work function from the emissive oxide coating. The field emission and thermionic emission properties of the cathode have been characterized. A field enhancement factor of 266 and a work function of 1.9 eV were obtained. At 1221 K, a thermionic emission current density of 1.22A/cm2 in an electric field of 1.1 V/μm was obtained, which is four orders of magnitude greater than the emission current density from the uncoated CNT cathode at the same temperature. The high emission current density at such a modest temperature is among the best ever reported for an oxide cathode.

SPECTRA OF RADIATION EMITTED FROM OPEN-ENDED AND CLOSED CARBON NANOTUBES EXPOSED TO MICROWAVE FIELDS

2013 ◽  
Vol 12 (04) ◽  
pp. 1350028 ◽  
Author(s):  
B. CAVNESS ◽  
N. McGARA ◽  
S. WILLIAMS
Keyword(s):  
Carbon Nanotubes ◽  
Ultraviolet Radiation ◽  
Work Function ◽  
Field Emission ◽  
Chemically Treated ◽  
Lower Work Function

We performed experiments in which both open-ended and closed carbon nanotubes were exposed to 2.46 GHz microwaves over the course of several irradiation and cooling cycles at a pressure of ~ 10-6 torr. The spectra of the radiation emitted from the nanotubes indicate that the intensity of the emitted radiation with wavelengths of 650–1000 nm increased during the irradiation cycles. However, the intensity of the radiation emitted from untreated nanotubes increased substantially more than the intensity of the radiation emitted from nanotubes that had been chemically treated in order to open nanotube ends. As open-ended nanotubes have a lower work function than closed nanotubes, and as nanotube ends are known to open as they are heated, our results suggest that the mechanism responsible for the emission of infrared, visible and ultraviolet radiation from carbon nanotubes exposed to microwaves is field emission-induced luminescence.

Enhancement of Electron Emission Properties of Carbon Nanotubes by the Decoration with Low Work Function Metal Oxide Nanoparticles

2020 ◽  
Vol 20 (10) ◽  
pp. 6463-6468 ◽  
Author(s):  
Mohammad M. H. Raza ◽  
Sunny Khan ◽  
Mohd Sadiq ◽  
Mohammad Zulfequar ◽  
Mushahid Husain ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Work Function ◽  
Field Emission ◽  
Electron Emission ◽  
Enhancement Factor ◽  
Metal Oxide Nanoparticles ◽  
Field Enhancement ◽  
Field Enhancement Factor ◽  
Oxide Nanoparticles ◽  
Emission Properties

In the present report, the properties of the field emission devices of carbon nanotubes (CNTs) were remarkably improved by decorating their surface with magnesium oxide nanoparticles (MgO NPs). The MgO NPs were attached effectively on the surface of CNTs via thermal evaporation. The Raman spectra confirm the graphitic order of as-grown pristine CNTs with RBM (radial breathing mode), D band and G band peaks at the 282 cm−1, 1347 cm−1 and 1594 cm−1 respectively. The peak at 471 cm−1 indicates successful attachment of MgO NPs to the CNTs. The enhanced field emission properties of CNTs were mainly attributed to the MgO NPs which increased the field enhancement factor and the density of emission sites. The decreased work function and increased field enhancement factor were responsible for the improved FE properties of the CNTs. Our results indicate that the MgO decorated CNTs can be used as an effective field emitter for various electron emission devices. The turn-on field decrease from 1.6 V/μm to 1.3 V/μm and the maximum current density increases from 1.581 to 3.678 mA/cm2 after the decoration of CNTs with MgO NPs. The value of field enhancement factor (β) also increases from 2.814×103 to 9.823×103.

Barium strontium oxide coated carbon nanotubes as field emitters

2007 ◽  
Vol 90 (14) ◽  
pp. 143114 ◽  
Author(s):  
Feng Jin ◽  
Yan Liu ◽  
Christopher M. Day
Keyword(s):  
Carbon Nanotubes ◽  
Strontium Oxide ◽  
Field Emitters ◽  
Barium Strontium ◽  
Coated Carbon
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