Electrical ageing of carbon nanotube composite cathode layers

Abstract

Effect of electrical ageing (EA) on the field emission parameters of thin multiwall carbon nanotube composite (t-MWCNTs-composite) was studied. Initially, t-MWCNTs were mixed with α-terpineol and ethyl cellulose and subjected to three roll milling process to obtain t-MWCNTs-composite. Following this, the composite was screen printed on a conducting substrate, annealed for 10 min and employed to the electrical ageing process for a period of 6 h. The ageing, on each cathode layer, was repeated for five times and J– E characteristics have been collected before and after each ageing attempt. The analysis revealed that, the magnitude of threshold turn-on-field gradually increased from its virgin value of 1.223 to 1.968 V µm − 1 and corresponding mean field enhancement factor, γ m, gradually decreased from 2700 ± 210 to 1940 ± 30 with a sequential increase in the ageing attempts. The degradation rate, δ J/δ t, estimated for untreated and EA samples, indicated that the magnitude of δ J/δ t reached to an equilibrium value of ~ 0.785 μA cm − 2 min − 1 , which shows a stable emission state of the emitters. To investigate the effect of EA on the physical state of the emitters, a few virgin and all EA samples were subjected to scanning electron microscopy, micro Raman spectroscopy and X-ray photoelectron spectroscopy. The details of the analysis are presented.