Residual Gas Adsorption and Desorption in the Field Emission of Titanium-Coated Carbon Nanotubes

Abstract

Titanium (Ti)-coated multiwall carbon nanotubes (CNTs) emitters based on the magnetron sputtering process are demonstrated, and the influences of modification to CNTs on the residual gas adsorption, gas desorption, and their field emission characteristic are discussed. Experimental results show that Ti nanoparticles are easily adsorbed on the surface of CNTs due to the “defects” produced by Ar+ irradiation pretreatment. X-ray photoelectron spectroscopy (XPS) characterization showed that Ti nanoparticles contribute to the adsorption of ambient molecules by changing the chemical bonding between C, Ti, and O. Field emission of CNTs coated with Ti nanoparticles agree well with the Fowler–Nordheim theory. The deviation of emission current under constant voltage is 6.3% and 8.6% for Ti-CNTs and pristine CNTs, respectively. The mass spectrometry analysis illustrated that Ti-coated CNTs have a better adsorption capacity at room temperature, as well as a lower outgassing effect than pristine CNTs after degassing in the process of field emission.

Enhanced field emission stability of vertically aligned carbon nanotubes through anchoring for X-ray imaging applications

“…60 Secondly, the surface of the CNT emitters can also adsorb a large number of gas molecules, which will be continuously released during the field emission, causing an increase in the vacuum level. 61 Thirdly, the emission electrons are accelerated by the electric field and hit the metal anode, causing the metal particles in the anode to be sputtered out and hit the CNT. 62 This damage mechanism has not been fully understood yet and requires in-depth exploration.…”

Advances of nanotechnologies for hydraulic fracturing of coal seam gas reservoirs: potential applications and some limitations in Australia

“…Quartz, calcite, pyrite, kaolinite and other clays are typically present in different proportions (e.g. Zhang et al 2019), resulting in high anisotropy in strength and high sensitivity to stress of the formations, compounded by differences in methane adsorption capacities of different clay minerals (Wang et al 2020).…”

“…Although, so far, little effort has been targeted specifically to applying nanotechnologies to the fraccing of coal seams, studies conducted in adjacent research fields may provide useful insights. For example, since the adsorption of nanoparticles on different rock types is not only controlled by the flow rate but is also strongly influenced by the presence of clay minerals (Omurlu et al 2016;Zhou et al 2017), titanium nanoparticles can be used as coatings on carbon nanotubes to influence residual gas adsorption/desorption (Zhang et al 2019).…”

Applications of Vacuum Measurement Technology in China’s Space Programs

“…Efforts have also been made for the measurement of total pressure in LIP. Since 2013, we have carried out theoretical and experimental research on carbon nanotube (CNT) cathode ionization gauge cooperated with Lanzhou University, Wenzhou University, and Bern University of Switzerland [13][14][15][16][17][18][19][20][21][22]. First, we established a three-dimensional physical model of CNT ionization gauge and used SIMION software to simulate the influence of electrode voltage, gate structure, and physical transmittance, etc.…”

“…Second, preparation process of CNTs with enhanced performance was developed: uniform and vertical multiwall CNTs were prepared by anodic alumina template method and deposition catalyst method to improve field emission performance [14,15]; free distribution CNTs were directly grew and prepared by oxidation-reduction method to improve emission current density and stability [16,17]. Third, a series of CNT cathode ionization gauges, such as Bayard-Alpert type, separation type, and spherical oscillator type, have been developed based on the abovementioned works [18][19][20][21][22] as shown in Figure 1. Among them, the separation-type CNT cathode ionization gauge has reached the best level reported at present.…”