Research On Non-Contact Temperature Sensor Based On Rare Earth Luminescence

As a commonly used physical quantity,temperature can quantitatively express the degree of hot and cold of objects.Temperature measurement plays an important role in industrial production.Among them,non-contact temperature measurement is widely used in some special occasions,such as high electromagnetic field,strong corrosive environment.Rare earth doped up conversion luminescent materials have become important materials in the field of non-contact temperature measurement due to their excellent luminescent properties,non toxicity and low cost.Based on the quantitative relationship between fluorescence intensity ratio and temperature,the non-contact temperature measurement technology has the advantages of high resolution,high sensitivity and not affected by the fluctuation of stimulated luminescence intensity.It is an important subject to develop and design new rare earth temperature measuring materials.In this paper,the temperature sensing properties of Gd₂O₃doped with Er³⁺,Pr³⁺and Nd³⁺were studied in order to obtain new high sensitivity temperature measurement materials.A series of Gd₂O₃:Er³⁺/Yb³⁺and Gd₂O₃:Er³⁺/Yb³⁺/Li⁺phosphors were synthesized by sol-gel method.The experimental results show that the up-conversion luminescence of Gd₂O₃:Er³⁺/Yb³⁺is enhanced by adding Li⁺.The temperature sensing properties of Er³⁺ions are studied by using the FIR technique of thermal coupled and non thermal coupled energy levels.The results show that the sensitivity of Er³⁺based on non-thermal coupling fluorescence intensity ratio is higher.The maximum sensitivity of Gd₂O₃:Er³⁺/Yb³⁺/Li⁺phosphor is 0.02 K^-1.The up-conversion luminescence and temperature sensing properties of Gd₂O₃:Pr³⁺/Yb³⁺and Gd₂O₃:Pr³⁺/Yb^3+/Li⁺phosphors excited by 980 nm infrared light were studied.It is found that Li⁺doping can enhance the up-conversion emission intensity of Gd₂O₃:Pr³⁺/Yb³⁺samples.The maximum sensitivity of Gd₂O₃:0.25 mol%Pr³⁺/2 mol%Yb³⁺is 0.004 K^-1at 543 K.Finally,the up-conversion luminescence and temperature sensing properties of Gd₂O₃:Nd³⁺/Yb³⁺and Y₂O₃:Nd³⁺/Yb³⁺phosphors were studied.The results show that the up-conversion luminescence intensity is the strongest when the concentration of Nd³⁺and Yb³⁺in Gd₂O₃and Y₂O₃is 0.5 mol%and 5 mol%,respectively.The up-conversion emission intensity of Gd₂O₃:Nd³⁺/Yb³⁺is stronger than that of Y₂O₃:Nd³⁺/Yb³⁺under the same conditions.The relationship between the fluorescence intensity ratio of the two phosphors based on the non thermal coupling energy level and the temperature T from 303 K to 573 K was studied.The highest sensitivity was0.00165 K^-1and 0.016 K^-1,respectively.