Preparation And Field Emission Properties Of Carbon Nanotube Composites

Carbon nanotubes (CNTs) have attracted great attention in material science technology for their unique structure, fantastic properties and widely potential application. An inherent small tip radius, a high aspect ratio, combined with chemical inertness and long lifetime make CNTs the very promising cathode material for field emission display. Extensive researchers have studied on the syntheses and field emission property of aligned CNTs film with chemical vapor deposition (CVD) method, but there have many important issues in the CNTs film, such as some CNTs can easily pull off from the substrate for the infirm van der Waals Force between the CNTs and substrate and CNTs were wrapped by catalyst at the top which make the field emission poor. To solve these problems, CNTs composite is one of the alternative choices. In this paper, two kinds of carbon nanotube composite for field-emission are synthesized and the field emission properties are studied. The main contents in this paper are as follows:1. Aligned CNTs film had been grown by chemical vapor deposition (CVD) method, CNTs grown on sodium chloride (NaCl) were studied. Then the methods of diluted nitric acid (HNO3) disposal and air oxidation are used to purify CNTs. Also, the dispersion of CNTs in water is studied, and the CNTs are dispersed very well with surfactant mixtures by ultrasonic agitation.2. Carbon nanotubes/silicon dioxide composite (CNTs/SiO2) is synthesized by sol-gel method and the field emission property is studied. The results show that the turn-on field and the field at 1 mA/cm2 of the composite are extremely low, which indicate that the field emission property is fine. After special surface treatment with diluted HF solution, the field emission of CNTs/SiO2 composite is improved. Based on the results, we conclude that CNTs/SiO2 composite is promising for the application in field emission displays.3. To develop the ideal flexible cathode material, Carbon nanotubes/rubber composite is synthesized by using physical mixing method. The composite is flexible and easy to make the required size and the required form. The field emission property of CNTs/rubber composite makes it suitable for applications in electrically and mechanically stable flexible display devices and sensors.