Fabrication Of Niobium Upconversion Luminescence Material By Containerless Method

Many researchers have studied upconversion materials for its application in solar cells,solid storage,etc.Nanoscale powders of fluoride and oxyfluoride are the typical upconversion materials and is limited in the practical application for their toxicity,poor mechanical properties.The heavy-metal oxide glass obtained efficient luminescence and good mechanical properties which is hard to be fabricated by the traditional method for their low glass-forming ability.Containerless method obtain the features that rapid coolingand restrain the contact nucleation.Containerless method can be carried out to enable heavy-metal oxide to vitrify in bulk glass form.In the study,the aerodynamic levitation method,a kind of containerless processing technologies,wasfirst introduced to fabricate the upconversion niobium pentoxide bulk glass coped with Er³⁺/Yb³⁺.The structure,thermal stability and luminescent properties of the samples were investigated systemically by XRD,differential scanning calorimetry,and upconversion spectra under 980 nm laser levitation.The structure behavior was investigated by Raman spectra.The effect of the addition of ZrO2 in the glass was studied.Results showed that the sample with 15mol% ZrO2 obtained the most efficient upconversion luminescence and good thermal stability.The addition of ZrO2 affected the structure behavior and the phonon density.The effect of La₂O₃ content and the temperature of heat treatment on the upconversion luminescence of Niobium Pentoxide glass was investigated.The results showed that the network structure was changed by the addition of La₂O₃.The sample obtained the best thermal stability and upconversion luminescence with 10 mol% La₂O₃.The upconversion luminescence intensity didn’t increase or decrease with the increase of the heat treatment temperature.The sample heated at lower temperature or crystallized obviously obtained stronger upconversion luminescence.The concentration of rare earth elements was optimized and the results showed that The sample with 1mol% Er³⁺/Yb³⁺ obtained the strongest upconversion emissions.The logI-logP plot of green emission indicated that the green emissions saturated at high pump power excitation,deviating from the low-power regime.The Niobium Pentoxide codoped with Er³⁺/Yb³⁺ bulk glasses were applied in the DSSC.The study indicated that containerless method could fabricate the Niobium Pentoxide upconversion luminescence glass with the rapid cooling.The upconversion luminescence properties was improved by the optimization of the components and the rare earth ions.The upconversion materials could be applied for the DSSC and provided a new method to improve the solar cell efficiency.