Electrical ageing of carbon nanotube composite cathode layers

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 -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, δJ/δt, estimated for untreated and EA samples, indicated that the magnitude of δJ/δt 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.