Research On Non-contact Rare Earth Fluorescence Intensity Ratio Temperature Sensor

In recent years,luminescent materials doped with rare earth ions have been applied in the field of temperature sensing.A temperature sensor based on rare earth up-conversion luminescence can characterize the measured temperature by the peak shape,peak position,peak width,polarization,lifetime,and fluorescence intensity ratio of the emission peak.Among them,temperature sensors based on fluorescence intensity ratio technology are less affected by measurement conditions,pump power fluctuations,and fluorescence detection losses,and have the advantages of fast response speed,high sensitivity,and high accuracy.Therefore,temperature sensors based on fluorescence intensity ratio technology have attracted great interest.Temperature measurement sensitivity of fluorescence intensity ratio technology based on thermal coupling energy level is affected by energy level difference（ΔE）Limitations.In order to break this limitation and further expand its application scope.There are two strategies that can be used to improve sensitivity.Firstly,fluorescence intensity ratio technology based on non-thermally coupled levels（NTCL）of a single activated ion can achieve higher sensitivity.Another is the fluorescence intensity ratio technology based on dual activation centers,which can also achieve high sensitivity temperature measurement.Therefore,this article designs and develops temperature sensors based on the non-thermally coupled levels of single activated ions and the fluorescence intensity ratio technology of dual activated centers.The main research content is as follows:（1）Research on up-conversion luminescence and temperature sensing characteristics of single activated Ion Ho³⁺doped fluorescent materials.BaMoO₄:Ho³⁺/Yb³⁺up-conversion luminescent material was successfully prepared using high-temperature solid-state method.Under the excitation of 980 nm laser,green light at 543 nm,red light at 660 nm,and infrared light emission at 755 nm were achieved.The temperature sensing optical properties of BaMoO₄:Ho³⁺/Yb³⁺phosphors were studied using non thermally coupled energy level fluorescence intensity ratio technology in the temperature range of 303-573 K.Its maximum absolute sensitivity is1.23×10^-2 K^-1.（2）Research of up-conversion luminescence and temperature sensing properties of single activated ion Tm³⁺-doped fluorescent materials.And its up-conversion luminescence intensity was enhanced by doping Gd³⁺in the up-conversion luminescence system.Thus CaWO₄:Tm³⁺/Yb³⁺/Gd³⁺fluorescent materials were designed and developed to achieve typical radioluminescence of Tm³⁺ions at 475 nm,655 nm and 755 nm under the excitation of 980 nm laser,and the intensity of up-conversion luminescence was enhanced with the doping of Gd³⁺.The non-thermally coupled level base temperature sensing characterization showed a maximum absolute sensitivity of 0.110 K^-1.CaWO₄:Tm³⁺/Yb³⁺/Gd³⁺is a very excellent temperature measurement material for temperature sensor development.（3）Research on temperature measurement system using fluorescence intensity ratio technology based on dual activation centers.CaWO₄:Tm³⁺/Yb³⁺/Gd³⁺/RE³⁺(RE³⁺=Er³⁺,Ho³⁺)fluorescent materials were prepared using a high-temperature solid-state method.Emphasis was placed on studying its temperature sensing characteristics.In the temperature range of 303-573 K,the maximum absolute sensitivity of the Tm³⁺/Er³⁺co doped system is 0.094 K^-1,while the maximum absolute sensitivity of the Tm³⁺/Ho³⁺co doped system is 0.103 K^-1.Finally,the temperature gyration curve of the phosphor sample is measured,which proves the stability and repeatability of the sample temperature measurement.It is a very good temperature measurement material and can be used for non-contact thermometers.