The Study On The Preparation And Coating Of The PDP Phosphors

With the development of the science and people's requirements, the plasmadisplay panels (PDPs) draw our eyes, and more and more PDPs enter into thepeople's families. But the phosphors that are applied to the PDPs still have somedisadvantages though the PDPs have some advantages. For example, the phosphors'luminescent efficiency will descend if they are exposed to the wet air such as someplaces in the humid south, because the high humidity will erode the phosphors andaffect the life-span of the phosphors, as a result, the development of the PDPs will bedeferred. This paper mostly studied the question. Generally the inorganic materialcoating the phosphors surface will isolate the phosphors from the environment,reduce the its influence on the phosphors, and prolong the life-span of the phosphors.The paper chose the Al2O3 and SiO2 to coat the phosphors, because coating the Al2O3and SiO2 can be easily carried out, and they have great photic, electrical andwater-resistant performances and are fit for coating the phosphors that are susceptibleto the water.The phosphors of the aluminate base are a kind of PDPs materials that havegreat luminescent performances. A series of BaMgAl12O19:Mn green phosphors wereprepared through the high temperature-solid method on the base of the preparation ofBaMgAl12O19:Mn. Their luminescent performances were studied, and the bestproportions of materials were fixed. And more, the green phosphors ofBaMgAl12O19:Mn and blue BaMgAl10O17:Eu were all coated with the Al2O3, SiO2and Al2O3-SiO2 compound through the sol-gel method, and then the coatedphosphors were studied through their FT-IR, XRD and SEM.The green phosphors of BaMgAl12O19:Mn doped with Mg, Sr respectively anddoped with them together were prepared through the high temperature-solid method,Their relative luminescence intensity and CIE were surveyed, and the bestproportions of materials were fixed for every doped phosphors. And the excited andemit spectrum were surveyed. They have an excitation band from 120nm-210nm ifthey are excited with the 120nm-300nm VUV, and the peak is highest in 147nm.Excited with 147nm, the phosphor of BaMgAl12O19:Mn emits green light that islocated at 519nm. So it is proved that they are all good PDPs phosphors.The paper mainly studied the phosphors'coating. Firstly, the green phosphors ofBaMgAl12O19:Mn were coated with the Al2O3, SiO2 and Al2O3-SiO2 compoundthrough the sol-gel method respectively. In the experiment of coating Al2O3, the ratioof mass of Al2O3 to the phosphors was 10%. It can be seen from the SEM of theuncoated and coated phosphors that the latter's surface were coarser and there was afilm of Al2O3 particles. Had analyzed the FT-IR and XRD spectrums of the coatedand uncoated phosphors, it was proved that there was a film of amorphous Al2O3 onthe phosphors'surface. The coating can resist the phosphors'contacts with theenvironment to reduce the environmental influence on the phosphors, and thelife-time of the phosphors will be lengthened. By the way, the Al2O3 coatingmechanism was discussed. In the experiment of coating SiO2, the XRD peaks of thecoated phosphors after baked in the 1200°C　included the peaks of the uncoatedphosphors and that of the crystal of SiO2, which proved that the film of amorphousSiO2 formed on the surface of the phosphors. Through SEM, it was obvious that thecoated phosphors'surface wase coarser and there was a film of Al2O3 particles.Finally, the phosphors also were coated with Al2O3-SiO2 compound. Had analyzedthe FT-IR, XRD and SEM of the coated and uncoated phosphors, it was proved thatthere was a film of Al2O3-SiO2 compound on the phosphors'surface after coating.And the coating mechanism of the Al2O3-SiO2 film was discussed.