The Synthesis And Properties Of Three Phosphors With Self-reduction Or Self-activation

The research of luminescent materials is an important work in the new generation of semiconductor solid lighting technology.But in theory,luminescence mechanism is not yet entirely clear when the luminescence materials are excited by the electron beam and vacuum ultraviolet?VUV?light.Thus,developing more efficient luminescence materials and explaining the ambiguities fundamental processes in physics is a question which cannot be avoided.In this paper,several phosphors were successfully synthesized by high temperature solid phase method.O n one hand,the thesis is aimed at developing luminescence materials with excellent properties and exploring their potential application;on the other hand,the thesis studies the relationship of composition,structure,property,and luminescence performance in special phenomena,such as the self-reduction,self-activating luminescence.The detailed research content is as follows:1?The first part,we studied the self-reduction of Eu ions in two different compounds synthesized in air atmosphere,including Mg₃Ca₃?PO₄?₄ and Ba₂AlB₄O₉Cl.1)The mixed-valence Eu-doped Mg₃Ca₃?PO₄?₄ by solid-state reaction in the air atmosphere.The luminescence measurements indicated that the obtained phosphors exhibit a broad bluish-green fluorescence of Eu²⁺and a sharp orange-red emission of Eu³⁺excited by 395 nm.The abnormal reduction mechanism could be explained by a charge compensation model.A tunable luminescence was realized based on the reduction of Eu³⁺to Eu²⁺changed along with increasing the sintering time.The reduction of Eu³⁺to Eu²⁺in Mg₃Ca₃?PO₄?₄ host was effected by the oxygen vacancy defects when the samples sintered in different atmosphere and sintered for different lengths of time,and the oxygen vacancies which act as the electron traps were investigated with thermoluminescence.All of the results almost indicated the oxygen vacancy could weaken the reduction of Eu³⁺to Eu²⁺.2)The other compound that shown self-reduction of Eu is Ba₂AlB₄O₉Cl synthesized in air atmosphere by solid state reaction.A seires of samples doped with different concertration of Eu shown different luminescence properties,because of different ratio of Eu²⁺/Eu³⁺in host.All of the samples shown a broad band in 390-500nm range attributable to 5d-4f transition of Eu²⁺,and the characteristic emission peaks of Eu³⁺in 550-750 nm range.The self-reduction was explained by charge compensation model.2?The second part,a self-activated novel luminescence material Mg₂BiPO₆ was successfully synthesized by high temperature solid reaction.The luminescence properties of Mg₂BiPO₆ were researched by UV\VUV\C L spectra.The emission spectrum excited by 277 nm is a broad band in the range 350-700 nm,which almost covers the entire visible area,and the CIE is?0.2949,0.3755?which is very close to the ideal white light?0.333,0.333?.After a small amount of large ionic Ca²⁺/Sr²⁺/Ba²⁺replaced Mg²⁺,the intensity of emission was increased obviously,because the interval of luminescence center Bi ions increased.Excited by the low voltage electron beam,the sample shows a good and stable luminous performance,which indicates a potential application prospects in FED.