Preparation Of Nanophosphors And Fabrication Of In-situ Carbon Nanotubes Field Emission Display

The field emission display (FED) is the fourth generation display, following the light emission display (LED). The carbon nanotubes(CNTs) is the ideal material for fabrication of the field emission cathode (FEC). Screen-printing is an effective method to make the large-area FEC at a low cost. The nanophosphors will not only satisfy the special requirements of CNTs-FED, but also improve its quality.In this work, the ZnGa₂O₄ phosphor was prepared by chemical co-precipitation method and ZnGa₂O₄:Eu³⁺ phosphor was prepared by solid-phase reaction. The phosphors were characterized by SEM, TEM and XRD, and their luminescent properties were investigated qualitatively. The CNTs film cathodes were prepared by screen-printing method. The effects of ultrasonication time, plasm, screen mesh size, grinding and high-temperature treatment on the morphology of CNTs film were investigated by SEM measurement. The anodes were prepared with the commercial phosphors. The apparatus to in-situ test the luminescent properties of CNTs-FED was designed and assembled by ourselves.The results of SEM and TEM measurements show that the particle sizes and the morphology of ZnGa₂O₄ phosphors prepared by chemical method are different, if the molar ratio of the raw materials ZnO and Ga₂O₃ is changed. The analysis results about XRD patterns indicate that the main phase in the products is ZnGa₂O₄, under the molar ratio of ZnO and Ga₂O₃ at both 1:2 and 2:1. The qualitative measurements of their luminescent properties show that when the molar ratio of ZnO and Ga₂O₃ is 1:2, the phosphor emits weak green color, but when the molar ratio is 2:1, the phosphor is nonluminescence. The results of SEM measurement show that the morphology of the ZnGa₂O₄:Eu³⁺ phosphor prepared by solid-phase reaction is not regular. The Eu³⁺-doped ZnGa₂O₄ phosphor emits red color.The results of SEM measurement show that the surface of the CNTs films presents some regular grid distribution in the SEM images of low magnification. The distribution of the CNTs is better with the increasing ultrasonication time. The tips per unit area on the CNTs films were increased obviously, if the raw CNTs were grinded beforehand. The CNTs in the films are more uniform and well-dispersed, if the plasm was added, compared with those without plasm added. After calcining for 2h at 450℃, the CNTs films without the plasm added became much clearer than before. Only being calcined for 2h at 430℃, many CNTs can be seen in the film which was prepared with the plasm added.The above results will play an active role in promoting the development of CNTs-FED.