Study On Upconversion Luminescence Properties Of YOF:Er³⁺/Yb³⁺/Tm³⁺ Nanocrystals

Rare earth elements are known as vitamins in contemporary industry because of their low dosage and large effect.As a matrix,oxyfluoride has the characteristics of low phonon energy,high up-conversion luminescence efficiency and wide temperature measurement range.Oxyfluorides combine the advantages of oxides and fluorides.In this paper,the upconversion luminescence properties,temperature sensitivity,preparation conditions and application of YOF:Er³⁺/Yb³⁺/Tm³⁺in white LEDs are studied.First,the precursor YF₃ was prepared using an optimized hydrothermal method.Then,YF₃ was placed in a calciner for calcination,and we found that pure phase YOF nanocrystals were obtained when calcined at 700°C for 2 h.The crystal structure and morphology of YOF:Er³⁺/Yb³⁺nanocrystals were characterized by XRD and SEM.The YOF:Er³⁺/Yb³⁺was excited by a 980 nm laser.In this way,we investigate the effect of Er³⁺/Tm³⁺/Yb³⁺doping concentration on the up-conversion luminescence properties of YOF:Er³⁺/Tm³⁺/Yb³⁺.At the same time,the mechanism of upconversion luminescence of red,green and blue light generated by Er³⁺,Tm³⁺doped YOF is explored.The equivalent Er³⁺/Yb³⁺doping ratios Y₂O₃,YOF,Y₆O₅F₈ were prepared.Under the same test conditions,YOF:Er³⁺/Yb³⁺had the highest upconversion luminescence efficiency and good monochromaticity.Secondly,YF₃:Er³⁺/Yb³⁺with different Yb³⁺doping concentrations were prepared.Firstly,the effect of Yb³⁺doping concentration on the fluorescence peak ratio of red and green light was investigated.The study found that as the concentration of Yb³⁺ions increases,the peak ratio of red-green fluorescence increases.Temperature sensing characteristics were then studied between 290 K and 550 K.In the temperature sensing calculation between the two thermal coupling levels,we find that as the temperature T increases,the temperature sensitivity S increases,reaching a maximum at 634.6 K.After this temperature,the temperature sensitivity follows.The decline.When calculating the temperature sensitivity between two non-thermally coupled energy levels,we found that the initial temperature sensitivity decreases with increasing temperature,reaches the lowest point around 450 K,and continues to heat up,and the temperature sensitivity S will follow The temperature rises and rises.We prepared YOF:Tm³⁺/Yb³⁺with different thulium ion concentrations and measured the upconversion luminescence spectrum.The ratio of Tm³⁺optimal doping concentration of YOF:Tm³⁺/10Yb³⁺was 0.2%.At the same time,the power curve is used to explore the up-conversion luminescence process of YOF:Tm³⁺/Yb³⁺.On this basis,the effects of the concentration changes of Er³⁺and Yb³⁺on the color change of YOF:Er³⁺/Yb³⁺/Tm³⁺were investigated.According to the influence of the intensity ratio of the three primary colors on the color,it is found that the color coordinates of YOF:0.6%Er³⁺/25,30%Yb³⁺/0.2%Tm³⁺nanocrystals are in the center of white light.By analyzing the effects of different powers,different temperatures on the chromaticity of white light,and combining the power curves,the conditions required to analyze the color stability of white light samples to maintain luminescence are constant temperature and constant power.