Research On Non-contact Temperature Sensor Based On Fluorescence Intensity Ratio Technology

In recent years,rare earth doped fluorescent materials have been widely used in the field of optical temperature measurement.The fluorescence intensity ratio（FIR）based temperature measurement technology is a commonly used method for fluorescence temperature measurement,as it can avoid the impact of pump power fluctuations and optical signal detection bias.The thermal quenching effect of RE³⁺ions will make it difficult to detect fluorescence signals at high temperatures.Therefore,it is necessary to develop new temperature measuring materials or strategies to overcome luminescence thermal quenching,enhance signal discrimination ability,and achieve high luminescence efficiency at high temperatures.In recent years,the phenomenon of activation ion luminescence thermal enhancement based on negative thermal expansion（NTE）effect of the substrate has been discovered and attracted widespread attention.In this paper,Zn₃Mo₂O₉material with negative thermal expansion effect is used as the substrate to design a fluorescence upconversion luminescence system and study its temperature sensing characteristics,providing theoretical support for the development of fluorescence temperature sensors and opening up research directions.The main research content is as follows:（1）The Yb³⁺/RE³⁺（RE=Er/Ho）codoped Zn₃Mo₂O₉phosphor samples were synthesized by high-temperature solid-state reaction method.Upconversion luminescence thermal enhancement was observed under 980 nm excitation,and the abnormal thermal enhancement of UC was mainly attributed to the negative thermal expansion characteristics of Zn₃Mo₂O₉matrix.Based on FIR temperature measurement technology,the temperature sensing characteristics of Zn₃Mo₂O₉:Yb³⁺/Er³⁺and Zn₃Mo₂O₉:Yb³⁺/Ho³⁺phosphor samples were thoroughly studied.The FIR temperature measurement sensitivity of Zn₃Mo₂O₉:10%Yb³⁺/1.5%Er³⁺phosphor sample based on Er³⁺ion thermal coupling energy level reaches a maximum value of0.0060 K^-1at 496 K.In addition,the Zn₃Mo₂O₉:10%Yb³⁺/1.5%Ho³⁺fluorescent powder sample achieved a maximum temperature sensitivity of 0.0119 K^-1at 393 K.It can be seen that Yb³⁺/RE³⁺codoped Zn₃Mo₂O₉fluorescent powder is a highly sensitive optical temperature measurement material,which can be used to develop non-contact thermal enhanced ratio optical temperature sensors.（2）10%Yb³⁺/1.5%Er³⁺/x%Tm³⁺（x=0.5,1.0,1.5,2.0）codoped Zn₃Mo₂O₉fluorescent powder samples were synthesized by high-temperature solid-state method.Based on FIR temperature measurement technology,in-depth research was conducted on the UC temperature sensing characteristics of Zn₃Mo₂O₉:10%Yb³⁺/1.5%Er³⁺/x%Tm³⁺phosphors.The experimental results show that the FIR based on the non thermally coupled energy levels of Er³⁺(⁴S_3/2)and Tm³⁺（³H₄）achieves a maximum sensitivity of 0.0172 K^-1at a temperature of 513 K.It can be seen that this fluorescent powder is a highly sensitive optical temperature measurement material,which can be used to develop non-contact thermal enhanced ratio optical temperature sensors.（3）10%Yb³⁺/1.5%Ho³⁺/x%Tm³⁺（x=0.5,1.0,1.5,2.0）codoped Zn₃Mo₂O₉fluorescent powder samples were synthesized by high-temperature solid-state method.Based on FIR temperature measurement technology,in-depth research was conducted on the temperature sensing characteristics of Zn₃Mo₂O₉:10%Yb³⁺/1.5%Ho³⁺/x%Tm³⁺fluorescent powder samples.The experimental results show that the maximum sensitivity of FIR based on the non thermally coupled energy levels of Ho³⁺（⁵F₅）and Tm³⁺（³H₄）is 0.0221 K^-1at a temperature of 413 K.It can be seen that this fluorescent powder is a highly sensitive optical temperature measurement material,which can be used to develop non-contact thermal enhanced ratio optical temperature sensors.