Effect Of Intrinsic Defects And Mixed Alkali Effect On Properties Of Ion-doped Luminescent Glass

Photonic glass has a wide range of applications in the fields of white light emitting diodes?LED?,optoelectronic devices,temperature senors,optical sensors,solar cells,optical fiber communication,biological imaging and so on.It has played a tremendous role in promoting the research and development of information technology and biotechnology,and occupies an important position in the research of optics and materials.In recent years,with the rapid development of LED,people put forward higher requirements for optical materials,optical materials broadband luminescence research has become a top priority.In this paper,novel fluorosilicate?FS?photonic glasses based on SiO2-KF-ZnF2 are reported which exhibit an intense near-ultraviolet?NUV?photoluminescence?PL?at 350 nm when excited upon deep-ultraviolet?DUV?light centered at 260 nm.That the strong NUV PL,with the internal quantum efficiency as high as 85%,is the unique feature of the studied FS glasses has been confirmed by a thorough comparison of a wide range of glasses including silica,silicate,borate,phosphate,germanate,tellurite,fluorosilicate,fluoroborate,fluorogermanate and fluoride glasses.The NUV emission is attributed to intrinsic defects in the FS glasses,and the possible origin of the intrinsic defects is suggested.The effects of intrinsic-defects-sensitized PL of Mn²⁺and rare-earth ions doped FS glasses are illustrated for the first time,and the sensitization mechanism discussed.Our results demonstrate that defects,when properly controlled and understood,can be an enriching factor endowing photonic glasses with a number of new and advantageous functions.Engineering borate glass structure by simple compositional modification is essential to meet the particular demands from both industrial and photonic research communities.In this part,we demonstrate how the mixing of Li2O with Na2O,K2O or Cs2O influences the relative abundance of 3-and 4-coordinated borons in the glass network,as exhibited by nuclear magnetic resonance?NMR?,Fourier transform infrared spectrum?FTIR?and Raman spectra.A systematic study is given of the alkali mixing effect on the glass properties including:glass transition temperature,microhardness,density,refractive index,and the near-infrared photoluminescence properties?e.g.,bandwidth and lifetime?of Er³⁺which has been barely studied in mixed alkali borate glasses.It is interesting to note that the glass transition temperature,refractive index and emission lifetime of Er³⁺manifest mixed alkali effect,in sharp contrast to microhardness,density and emission bandwidth which vary monotonically upon the alkali mixing.The possible causes for the differences are discussed in the light of the compositional dependence of boron species and nonbridging oxygen upon alkali mixing.Ti⁴⁺and Er³⁺were selected as the luminescence centers for research respectively.The influence of glass structure on the luminescence performance of Ti⁴⁺or Er³⁺doped alkali borate photonic glass was explained from the perspective of the change of glass network structure with the composition of mixed alkali.