Preparation For Carbon Nanotube Film And Study On Field Emission Properties

Carbon nanotubes(CNTs)are widely studied all over the world due to their unique structure and excellent properties.Firstly,Fe(NO₃)₃,Ni(NO₃)₃and Co(NO₃)₃ are used as precursors of the catalysts,carbon nanotubes are prepared by CVD in 820℃.A few of carbon nanotubes are grown on the different templates(quartz,Si,Ti,AAO).Then a new type CNT paste was prepared and the craft to manufacture the cathode was also summarized. Experimental results show that the paste has an excellent emission performance when the metal powders weight fraction is about 5%while that of CNT is 10%.CNT can be separated much more uniformly when added some surfactants.The cathode is fabricated with screen printing technique.After the cathode film is sintered,its resistivity and adherence versus the weight(ratio)of each ingredient in the slurry,as well as the process of manufacturing the cathode film,is analyzed.A reasonable heating process and silk screen aperture is made certain.The cathode emitting uniform is improved through the enhancement of its electric conductivity and CNT uniformity.The turn-on field of the cathode is about 2.5V/μm,the emitting current is 5.6μA when the electric field reaches to 3.3V/μm,and its fluctuation is less than 5%.The CNT slurry is expected to be used as the cathode of field emission display, highlight lamp devices and as the back light source for liquid crystal display.Secondly,field emission display of carbon nanotube includes triode structure and diode structure.The latter drive voltage is high and its modulating voltage scope is wide,so the resolvent is found by studying the flat gate structure.Experiment indicates that the problem of minishing gate voltage and its modulating voltage scope can be solved by increasing anode voltage,shortening the distance between cathode and anode and the aged gate. Finally,CNT cathodes have been made by using screen-printing.Conglutinated CNTs were separated after being ablated by laser.The spacing between CNTs increased,screen effect minished.Experiment results show that the field emission properties of CNT film are highly improved,relevant turn-on voltage was reduced and field enhancement factor(β)was enhanced.From Raman spectra of MWNTs film dealed with laser energy,the defects on CNT surface were increased with the laser energy added,which became new field emission dots.Compared with diode structure the flat gate structure demonstrated better field emission performance.So the laser ablation is a kind of effective method that could enhance CNT field emission properties,and has the utility value in the research of CNTs cathode material.At the same time,the flat gate structure has super foreground in the structure design of CNT field emission flat display.