The Preparation And Investigation Of Er³⁺-doped Tellurite Bismuth Glass Ceramics

With Infrared laser materials attracted extensive attention in recent years owing to their important application in many fields,such as remote sensing,environmental monitoring,pump sources and laser medical surgery,etc.Glass ceramic?GC?,combining the strong crystal field of nanocrystals and excellent fiber-drawing ability of glass matrix,breaking through the bondage of traditional composite materials and opening up a new research direction for new mid-infrared fluorescence laser materials,is considered as a promising medium for rare earth doped fiber to produce intense mid-infrared emission.In other words,the glass ceramics do not need to be integrated and encapsulated to realize device assembly,which greatly reduce the cost and time of production process.This paper aims at preparing Er³⁺ doped TeO₂-Nb₂O₅-Bi₂O₃ tellurite glass-ceramic materials,mainly studies 2.7?m band in Er³⁺ ions infrared laser luminous performance in the host material.The research content of this paper can be divided into the following aspects:1.The eutectic region and phase separation region of the formation region of TeO₂-Bi₂O₃-Nb₂O₅ glass system were derived by thermodynamic method.The calculated glass formation region was verified by the point-by-point method.The overlap degree of the theoretical glass region and experimental glass region is large,so the glass formation region of the more reliable and perfect TeO₂-Bi₂O₃-Nb₂O₅ glass system is obtained.This indicates that the thermodynamic method can be used to predict the low eutectic point and the glass-forming region of the ternary silicate glass system.The glass forming region is affected by both thermodynamic factors and kinetic factors.Therefore,there are some errors in predicting the glass forming region by thermodynamics method.Some objective analysis is made on these errors.2.The crystallization kinetics of the rare earth Er³⁺doped TeO₂-Bi₂O₃-Nb₂O₅ glass system was studied by DSC differential thermal analysis under non-isothermal conditions.The nucleation and growth process of the crystal in the glass were investigated.The results show that The Bi_3.20Te_0.80O_6.40 crystal is a three-dimensional growth mode and the nucleation and growth process of the glass-ceramic is a diffusion mechanism,which belongs to the diffusion-controlled crystallization behavior.Transparent silicate glass-ceramics containing different rare earth ions Er³⁺doping concentration were prepared by two-step heat treatment.The results of X-ray diffraction and transmission electron microscopy confirmed that Bi_3.20Te_0.80O_6.40 nanocrystals were formed in the matrix glass.And the Er³⁺part enters the microcrystalline structure.It is indicated that the Bi_3.20Te_0.80O_6.40 crystal is in a three-dimensional growth mode and the nucleation of the microcrystalline glass-ceramic and the growth process as a diffusion mechanism are diffusion-controlled crystallization behavior.3.The mid-infrared luminescence properties of Er³⁺in nanocrystals were studied by fluorescence spectroscopy.The effects of heat treatment and rare earth ion doping concentration on luminescence properties were discussed.With the increase of crystallinity,the fluorescence intensity of Er³⁺:2.7?m in silicate glass-ceramics is obviously enhanced,the up-conversion luminescence and near-infrared luminescence are also enhanced,and the fluorescence of ⁴I_11/2 and ⁴I_13/2 levels Life expectancy also shows an increasing trend.The doping concentration of rare earth ion Er³⁺has a significant effect on the luminescence properties of glass-ceramics.With the increase of Er³⁺-doped concentration in glass-ceramics,the luminescence intensity of the glass-ceramic system increases first and then decreases.This is because the rare earth doping concentration is too high,resulting in fluorescence quenching.