Influence On Photoluminescence Through Non-equivalence Substitution In Phosphors

White light-emitting diodes,holding great advantages of low energy expenditure,high quantum efficiency,excellent color quality,and high display rendering,becomes an important field in science and technology.AC-LED is a new type of device that can be directly driven by the alternating current of city power.Thus,studies of phosphors for white LEDs have been paid great attention to.According to these conditions,two phosphors are systematically studied,namely,BaSi3Al2O4N4:Ce3+,Tb3+and Sr3.96Eu0.04Al14O25-3/2xNx.This paper is divided into 4 chapters.For the first chapter,we make a brief introduction on the development and history of lighting technology.Based on the background and knowledge above,our ideas for experiments are taken into action.In the second chapter we seek to find the energy transfer mechanism of BaSi3A12O4N4:Ce3+,Tb3+phosphors.It is found that Ce3+can significantly enhance the luminescence intensity of Tb3+.Test results including excitation spectra,emission spectra and decay curves all show strong evidence of the energy transfer between Ce3+ and Tb3+.The result shows that the energy transfer efficiency of the phosphors can be very high.We found that the mechanism of energy transfer is dipole-quadrupole interactions.Chapter three gives an introduction on Sr3.96Eu0.04Al14O25-3/2xNx phosphors,including crystal structure,long afteglow luminescence properties and thermal luminescence.By increasing the incorporation of N3-and reducing the proportion of O2-in the crystal,the long afterglow luminescecnce is successfully achieved,and greatly enhance the intensity of green emitting located at 494 nm is also realized.Since the substitution of N3-for O2-is not equivalent,this leads to the appearance of oxygen vacancies in the crystal and thus creates more defects.The EPR data prove that there are less oxygen vacancies trapped with single electron,while XPS data show more oxygen vacancies with no electron trapped are created.All these results prove that the proposed mechanism of long afterglow is correct.The chapter four is a brief summary.We point out what we miss in the research,and put up some constructive suggestions for the research further.