Study On The Preparation And Properties Of Silicate Glasses Based On Rare Earth Ions As Luminescent Centers

Light emitting diode?LED?has been widely used in lighting,decoration,display and other fields due to its advantages of energy-saving,long lifetime,and environmental friendly,and so on.At present,the commercial white LED is mainly composed of blue LED chip,YAG:Ce phosphor,and epoxy resin as encapsulation material.While this kind of LED device has some disadvantages,e.g.,non-uniform phosphor coating,difficult heat dissipation,easy aging of epoxy resin.Luminescent glasses can be used in the preparation of LED device and have some merits over traditional phosphors,such as high thermal stability of glass,easy to process into the desired shape,and can be made into a suitable shape to directly packaged with LED chip without using epoxy resin.In addition,the preparation process of luminescent glass is simple and the cost is low.Based on this background,herein we investigate the silicate luminescent glasses with the rare earth ions as luminescent center.A series of Pr³⁺,Tm³⁺,Tb³⁺,Dy³⁺,Mn⁴⁺singly and codoped silicate luminescence glasses were prepared by high temperature melt quenching technique.The as-obtained glasses were investigated using X-ray diffraction?XRD?,the Fourier transform infrared spectra,absorption spectra,emission and excitation spectra,and color coordinates.The main research contents and results are listed as following:The Pr/Tm doped silicate luminescent glasses were prepared.We mainly explore the effects of silicate glass matrix composition,crystalline phase in glass and Tm³⁺ions on the luminescence of Pr³⁺.It is found that the luminescence performance of Pr³⁺ions can be adjusted by changing the glass matrix composition.The CaF₂ crystal is formed in the melt quenching process.The CaO and Al₂O₃ in the composition can inhibit the formation of CaF₂ crystal,and the introduction of Na₂O is beneficial to the formation of CaF₂ crystal.The energy transfer can be observed between Pr³⁺ions and the energy transfer process can be enhanced by CaF₂ crystal.The luminescence of Pr³⁺ions can be also regulated by changing the concentrations of Tm³⁺ions.The Tb/Dy doped silicate luminescent glasses were studied.We mainly focus on the influence of the introduction of P₂O₅ on the luminescence properties of Tb³⁺and Dy³⁺ions.The results show that the Ca₃?PO₄?₂ and CaZn₂?PO₄?₂ crystals are formed in the glass matrix with the introduction of P₂O₅ and the emission of Tb³⁺ions at 489 and 544nm can be enhanced.The emission peak intensity ratio of Dy³⁺ions at 482 and 576 nm is changed with the variation of P₂O₅ content.The Dy/Mn doped silicate luminescent glasses were examined.We mainly investigate the effects of glass structure,the crystal type,and the forming methods?casting and sheet compressing?on the luminescence of Dy³⁺.The influence of the Mn⁴⁺on the emission of Dy³⁺is also considered.The results show that the Na₂Ca₃Al₂?PO₄?₂?SiO₄?₂ crystals can be formed in silicate glass prepared by casting method,which can affect the luminescent properties of Dy³⁺ions.The variation of Mn⁴⁺ions concentrations can also change the luminescence properties of Dy³⁺ions.The Tm/Dy doped silicate luminescent glasses were preapred.We mainly discussed the influence of the substitution of CaO with BaO in glass composition on the luminescence properties of Tm³⁺and Dy³⁺ions.In addition,the effect of Tm³⁺ions on the luminescence properties of Dy³⁺ions is also examined.It is found that the absorption band in UV light region of glass matrix becomes narrower with the introduction of BaO,and the emissions of Dy³⁺ions at 454 nm is enhanced,but the luminescence of Tm³⁺ion is not changed obviously.The energy transfer from Tm³⁺to Dy³⁺exists,and this energy transfer phenomenon exhibits obvious change in the glass samples containing BaO.The as-developed luminescence glasses here possess superior performance and show the tunable luminescence behavior,which can be used as light conversion materials for LED and have potential application prospect.