Study On The Luminescence Enhancement And Application Of BaYbF₅ Glass Ceramics Doped With Rare Earth Ions

Rare-earth doped up-conversion luminescent materials have very important potential applications in many fields of application,such as military laser guidance and civilian white light illumination and so on,which has become a hot topic in the field of materials research.The oxyfluoride glass ceramic have the advantages of excellent mechanical stability of the oxide glass matrix and low phonon energy provided by fluoride nanocrystallites,and are a rare matrix material which can bu used for up-conversion luminescence.For many years,researchers have tried to improve the up-conversion luminescence efficiency of rare earth ions doped into matrix materials,focusing on the discovery of a matrix with lower phonon energy or gain energy transfer efficiency of crystal structure.Ytterbium has a special energy level in lanthanide elements.When it is nixed into the matrix,it can enhance the up-conversion luminescence of other rare earth ions by energy transfer as a sensitizer.Even some rare earth ions?such as thulium,terbium,etc.?can not achieve up-conversion luminescence without Ytterbium ions.Therefore,increasing the concentration of Ytterbium will produce a gain for the up-conversion luminescence of other rare earth elements.More importantly,the concentration of Ytterbium also has a great influence on the properties of materials in the application of rare earth doped luminescent ion matrix.In this thesis,glass samples were prepared by high temperature melting.The main application of rare earth ion doped BaYbF5 glass ceramic is discussed.and the advantages of BaYbF₅ glass ceramic in the enhancement of up-conversion luminescence were analyzed,and the influence of high concentration of Ytterbium ions on its application was also studied.?1?The preparation and characterization of BaYbF₅ glass ceramic were carried out.The applications of BaYbF₅:Er³⁺?Tm³⁺glass ceramic in white LED were studied.In addition to the enhancement of sensitization,under the excitation of 980 nm laser,the white color temperature can be adjusted by changing the ratio of the two activator ions,and the up-converted white light with cold color temperature can be obtained.?2?The thermal conversion of BaYbF₅:Tm³⁺glass ceramic,the thermal coupling level of Tm³⁺:³ F_2,3,³H₄ performance,thermal coupling energy level Tm³⁺:¹ G_4?a?,?b?thermal performance.The maximum temperature sensitivity of Tm³⁺:³F_2,3,³H₄ at 573K is4.35×10^-4K^-1,and Tm³⁺who use temperature-measured of thermal coupling level Tm³⁺:³F_2,3,³H₄ has considerable advantages in up-conversion optical temperature measurement when it is doped with BaYbF₅ glass ceramic compared with other materials.Secondly,the influence of energy transfer mechanism on temperature measurement sensitivity under the influence of the concentration of Yb³⁺is explored according to the thermal sensitivity of Tm³⁺:¹G₄?a?,?b?.?3?The enhancement of up-conversion luminescence by BaYbF₅ glass ceramics at808nm excitation and the further enhancement of up-conversion luminescence by plasma resonance were investigated.Nd ³⁺and Er ³⁺co-doped BaYbF₅ glass ceramic were prepared.Under the excitation of 808 nm laser,Yb³⁺,as a microcrystalline component,existed in the glass-ceramics became the bridge of energy transfer between Nd ³⁺and Er ³⁺,which breaking the barrier of microcrystalline itself to energy transfer and greatly enhanced the energy transfer efficiency;Au nanoparticles have an enhanced effect on the up-conversion luminescence of Er³⁺due to their plasma resonance.The spectral analysis shows that Au NPs have a strong sensitization effect on Er:⁴I_11/21/2 due to energy matching.