Synthesis, Properties Of Novel Phosphorescence Materials

With the development of national economics and the advancement of technology,the demands of luminescent materials are also increasing,luminescent materials canbe applied not only to emergency lighting,display,and other traditional field,but alsohigh energy-ray detection,optical fiber thermometer,the non-destructive detection ofceramic works,the ultra-high density optical storage and display,and other hightechnology areas also have potential application.In recent years,great achievementsof the luminescent materials of PDP,FED and LED flat panel display have been made.As the information becoming a pillar industry,the status and role of the luminescentmaterials goes without saying.The aluminate phosphors occupy an important positionin the PDP phosphors,and the host of the green and blue PDP phosphors is almostaluminate.Currently,aluminate phosphors have been synthesized by high-temperaturesolid-state reaction above 1400℃,and as-obtained phosphors have somedisadvatages,such as large particle size,serious aggregation.So,looking for a suitablehost is a trend of luminescent material research in future.Therefore,the work starts from two aspects:new host and new luminescentmaterials.Firstly,an improved process of green Zn₂SiO₄:Mn²⁺,known as an importantgreen luminescent materials,is studied in details.At lower temperature (1000℃),Zn₂SiO₄:Mn²⁺ was obtained via dipping progress with high pure phase,good disperse,good shape and small size.The main research interest of our thesis is focused on newluminescent materials.Following this idea,we develop some luminescent materials,as follows,MgSiO₃:Eu²⁺ and luminescent glass:MgO·SiO₂·B₂O₃:Eu²⁺,ZnO·SiO₂·B₂O₃:Eu²⁺.Based on the synthesis of these luminescent materials,relations between composition,structure and properties are analyzed and discussed.The MgSiO₃:Eu²⁺ phosphors have wide excitation spectrum of 254nm～400nm,and a wide range of potential applications can be expected.The MgSiO₃:Eu²⁺ phosphors can be used as blue-emitting materials,because the main peak of emissionspectrum is located at 440nm which fits the demand of blue-emitting materials.Thisluminescent materials have some characteristics,such as good chemical stability,high luminescent intensity,wide excitation spectrum (254nm-400nm),simple preparationprocess and low cost.The study of structure and spectral properties of the MgO-SiO₂-B₂O₃:Eu²⁺ glass shows that,under the ultraviolet irradiation,as the concentration of doped Eu²⁺increasing,the emission of MgO·SiO₂·B₂O₃:Eu²⁺ appears concentration quenching,and the wavelength of the emission spectrum is changed from 440 nm to 505 run.Theexcitation spectrum shows similar change,and the excitation spectrum is changedfrom 330 nm to 440 nm as the concentration of doped Eu²⁺ increasing.We proposethat there should be two sites A and B of doped Eu²⁺in the MgO·SiO₂·B₂O₃:Eu²⁺ glass.Eu²⁺ in site A emits high brightness,has a quick concentration quenching,andits main peak of emission spectra locates at 440 nm.But Eu in site B emits lowbrightness,has relatively slow concentration quenching,and its main peak ofemission spectra locates at 500 nm.Therefore,at low concentration of Eu²⁺(<1.0%),the emission spectra with a main peak of 440 nm are mainly attributed to the emissionof Site A;meanwhile,at the higher concentration of Eu²⁺(>1.0%),the emissionspectra with a main peak of 500 nm are mainly due to the emission of Site B.Theexcitation spectra also support above proposal.At low concentration of doped Eu²⁺,the excitation spectra mainly assigned to site A show a wide broadband with mainpeak of about 300nm.At high concentrations,another excitation broad peak locatingat 440 nm appears which can be assigned to Site B.When the concentration ofMgO increases in the glass,emission spectra shift from 440 nm to 463 nm because ofthe change of the network structure of the glass.Under the UV light(220 nm～400nm),the luminescent glass,ZnO·SiO₂·B₂O₃:Eu²⁺,can be excited well.The emission spectra show a broadband locating at 450 nm.