Preparation And Luminescence Properties Of Several Typical Rare-earth Phosphors For White LED

Under the promotion of global energy reduction and the concept of low-carbon economy, the light source of high energy saving has attracted widespread interest. Light Emitting Diode has been widely used in many lighting fields such as urban landscape lighting, the back light of LCD display, general lighting in interior and exterior et al due to its high efficiency, energy-saving (only 1/8 percent of filament lamp), long service life (for 100 thousand hours), mercury pollution-free, little volume and so on, so it has been considered the fourth generation illuminating source to replace the classical incandescent lamp and fluorescent lamp. Up to now, the most mature method for achieving white LED is phosphor conversion, and the illumination performance of the phosphor powder plays a key role in the performance of white LED. Therefore, it is important to obtain phosphor powder with stably chemical property and excellent illumination performance. In this paper, fine Y2O3: Eu3+ and YAG powders were prepared through a hydrothermal method and plasma method, respectively, then the structure, morphology, properties of the products were characterized and researched. The main tasks are as follows:(1) Preparation of fine structure Y2O3:Eu3+ powders by hydrothermal process.Metal nitrates were used as precursors and sodium citrate as crystal modifier to prepare powders via a facile hydrothermal method. Various structures of hexagonal Y(OH)3 powders were obtained successfully under hydrothermal condition. Y2O3 microstructures with similar morphologies were obtained after thermal treatment of the as-prepared Y(OH)3 microstructures at 1000℃for 2 h. TEM,SEM,XRD and IR were employed to characterize the as-obtained products. The effects of reaction temperature, variety of solvent, different concentrations of sodium citrate, different concentrations of sodium hydroxide and reaction time on the morphology and structure of Y(OH)3 were investigated systematically. The formation mechanism has been studied through systematic analysis of the reaction time. And the fluorescence properties of different structures Y2O3:Eu3+ powders were tested by Fluorescence spectrophotometer LS55 under room temperature. This approach is a sample method and without eliminating pollutants, which is regarded as a green and facile route to prepare rare-earth compounds.(2) Preparation of fine spherical YAG powders by the RF plasma process.On the basis of the study of our team, we adopt the solution of metal nitrates as precursors to synthesize YAG powders in an atmosphere of Ar. Various grain size of YAG powders were obtained through adjusting the experiment condition, such as the concentrations of the solution, the flow of carrier gas et al, which is important for the industrialization of YAG powders.