Studies On The Preparation And Luminescence Properties Of Rare Earth Doped Germanate Glass Ceramics Containing Fluoride Nanocrystals

Oxyfluoride glass ceramics have the advantages of good chemical,thermal and mechanical stability of oxide glass,low phonon energy of fluoride and high solubility of rare earth ions.Therefore,rare earth ion doped oxyfluoride glass ceramics have become a kind of luminescent materials with high luminescent efficiency and excellent physical and chemical properties.In this paper,based on oxyfluoride germanate glasses,the effects of different glass components and heat treatment conditions on the crystallization were studied.Therefore,rare earth ion doped oxyfluoride glass ceramics with different fluoride crystalline phases were prepared.The thermal properties of glass ceramics and the controlled precipitation of fluoride were studied by DTA,XRD and TEM.The optical properties and scintillation properties of glass ceramics were studied by transmission spectrum,fluorescence spectrum,fluorescence lifetime and X-ray excitation spectrum.Tb³⁺doped transparent oxyfluoride germanate glass ceramics containing CaF₂nanocrystals were prepared.The results show that the crystalline size of CaF₂ is between 16 and 20 nm,and the transmittance of glass ceramics is still over 80%in the visible range.Compared with the precursor glass,the luminescence intensity of glass ceramics has been significantly improved,and the maximum integral intensity of XEL spectrum reaches 50%of that of BGO crystal.It is a potential glass ceramics scintillator material.Eu³⁺doped transparent oxyfluoride germanate glass ceramics containing CaF₂nanocrystals were prepared.The results show that the crystalline size of CaF₂precipitated in the glasses is between 13-19 nm,and the glass ceramics still keep a high transparency while enhancing the luminescence of Eu³⁺and emit bright red light under X-ray excitation.It is a potential glass ceramics scintillating material.Eu³⁺doped transparent oxyfluoride germanate glass ceramics containing LaF₃nanocrystals were prepared.The results show that the crystalline size of LaF₃ is between 22-33 nm,and the transmittance of glass ceramics is still more than 70%in the visible range.After crystallization,the ultraviolet and X-ray excitated luminescence intensities of the glass ceramics have been significantly improved,and the maximum integrated intensity of XEL spectrum reaches 20%of that of BGO crystal.It is a potential red-light glass ceramics scintillator material.Tb³⁺doped transparent oxyfluoride germanate glass ceramics containing LaF₃nanocrystals were prepared.The results show that the crystalline size of LaF₃ is between 16-21 nm,and the glass ceramics still have a high transparency.After crystallization,the ultraviolet and X-ray excitated luminescence intensities of glass ceramics have been significantly improved,and the maximum integrated intensity of XEL spectrum reaches 40%of that of BGO crystal.It is a potential glass ceramics scintillator material.Ce³⁺doped transparent oxyfluoride germanosilicate glass ceramics containing Ba₂LaF₇ nanocrystals were prepared.In CO reduction atmosphere,Ce mainly exists in glass as Ce³⁺.In glass ceramics,the crystalline size of Ba₂LaF₇ is between 18-30nm,which makes it keep a high transparency.Under the excitation of 345 nm ultraviolet light,Ce³⁺exhibits its characteristic broadband blue light emission,and the luminescence intensity is significantly enhanced after heat treatment.The results show that the glass ceramics have potential application prospects in the field of Blu-light LED materials.