Study On The Preparation And Luminescence Properties Of Rare Earth And Transition Metal Ions Doped Borosilicate Glasses

Rare-earth doped light-emitting materials are commonly used in the field of white lighting,and white LEDs prepared in the form of chips plus fluorescent materials have the advantages of energy saving and environmental protection.Currently,white light devices consisting of blue chips and yellow phosphor(YAG:Ce³⁺)have been widely commercialized,but they still have the disadvantages of high color temperature,low color rendering index,and uneven phosphor distribution.Rare earth-doped luminescent glass has the advantages of low cost,easy plasticity,excellent physical and chemical properties,etc.The use of luminescent glass instead of phosphor to prepare the white LED can well avoid the above problems.The transition metal Mn⁴⁺ions are often used as activators for red light materials,which can be used as LEDs for plant growth due to the large overlap between the red light range of the material and the absorption spectral range of green plants.Ca O-B₂O₃-2Si O₂（noted as CBS）was used as the substrate,and Eu²⁺,Eu³⁺,Ce³⁺,and Mn⁴⁺ions were used as activators in a single-doped and co-doped The light-emitting glasses with different emission wavelengths were prepared by the melt-cooling method,and the structural properties and luminescence information of these light-emitting glasses were analyzed to conclude that they can be used in white LEDs and LED plant growth lamps.The specific experimental work is as follows:（1）TheCa O-B₂O₃-2Si O₂:Ce³⁺,Ca O-B₂O₃-2Si O₂:Eu²⁺and Ca O-B₂O₃-2Si O₂:Ce³⁺,Eu²⁺（denoted as CG,EG,and CEG respectively）luminescent glasses were prepared by high-temperature melting method under a carbon reduction atmosphere.The structural and luminescent properties of the prepared glasses were analyzed by XRD,DSC,FTIR,excitation and emission spectra,transmittance curves,fluorescence lifetimes,and color coordinates.The results show that the CG glass has the strongest emitted light under the light excitation at 350 nm,the central wavelength of the emitted light is around 400 nm,and the intensity of the emitted light shows a trend of increasing and then decreasing with the increase of the doping amount and reaches the maximum intensity when the doping amount is 0.5 mol%;the EG glass has the central wavelength of the emitted light around 460 nm under the light excitation at 400 nm,and at 0.3 mol%,the luminescence intensity was at its maximum.Finally,under the premise of fixing Ce³⁺ions,the doping amount of Eu²⁺ions was changed to obtain co-doped CEG glasses with an emission wavelength of470 nm under light excitation at 345 nm.Calculations and actual data obtained confirmed the feasibility of co-doping and the existence of energy transfer from Ce³⁺to Eu²⁺.（2）Ca O-B₂O₃-2Si O₂:Eu³⁺（denoted as EUG）luminescent glasses were prepared by the high-temperature melting method.Under near-UV excitation at 394 nm,the glass emits linear red light at 613 nm（corresponding to the ⁵D₀→⁷F₂transition）.This can be applied to white LEDs prepared from YAG.The addition of this glass to the device increases its missing red light component,which in turn improves the original high color temperature and low color rendering of YAG.The results show that in the Eu³⁺ion gradient of this experiment,the luminous intensity reaches its maximum and best effect when the doping amount is 0.7 mol%and shows a high and wide transmission spectrum in both transmission and absorption spectra.Finally,the non-radiative jump type of Eu³⁺ions in EUG glass was calculated to be a dipole-dipole interaction.（3）Ca O-B₂O₃-2Si O₂:Mn⁴⁺（noted as MG）luminescent glasses were prepared by the high-temperature melting method.Under the excitation of 415 nm light,the MG glass emits a broadband red light at 630 nm with strong emission in the range of550-750 nm,which has a large overlap with the absorption spectrum of chlorophyll in green plants,and therefore the glass can be used as a choice for the broadband red light component required for LED plant grow lights.Experimentally it was obtained that the luminous intensity of the glass reached its maximum at an ion doping level of0.4 mol%.Finally,the color coordinates also show that the emitted light is in the red position,indicating that the red glass has been successfully prepared and can be used in plant growth LEDs.In conclusion,in this paper,Ca O-B₂O₃-2Si O₂was used as the matrix glass in which different colored luminescent glasses doped with Eu²⁺,Eu³⁺,Ce³⁺,and Mn⁴⁺were realized in a single or double-doping manner,respectively.Based on the luminescent properties of these glasses and the overlap with the absorption spectra of plant pigments,it has been demonstrated that these luminescent glasses can be well used in white LEDs and LED plant growth lamps,laying a solid foundation for the development of functional LED lamps.