Temperature Sensing Properties Based On Fluorescence Emission

Temperature is an important thermodynamic parameter in many fields such as physics,chemistry,biology,medicine and industrial technology.People have developed various temperature measurement techniques based on changes in parameters such as volume,pressure,voltage,and resistance.However,with the progress of society,in special environments such as strong corrosiveness,high flammable gas concentration,and strong magnetic fields,the requirements for non-contact remote temperature measurement technology are getting higher and higher.For example,integrated optoelectronic devices require a thermometer that has a fast response speed and is resistant to strong electromagnetic field environments.In this case,most common temperature detection technologies are not applicable,so new non-contact temperature measurement technologies are getting more and more attention.Optical-based temperature sensing is one of the most promising non-contact temperature sensing technologies developed in recent years.It relies on the analysis of changes in spectral characteristic parameters caused by temperature changes to achieve thermal sensing.It has non-destructive,high-precision,and fast response.It has the advantages of not being interfered by environmental electromagnetic signals.In addition,it can also detect the temperature of nanometer scale and large area.This thesis is based on the principle of fluorescence emission,using high-temperature solid-phase method to prepare and study several new non-contact temperature sensing materials,and analyze their temperature sensing characteristics and potential application value.A series of Na₃ScB₂O₆:Ce³⁺phosphors were synthesized by high temperature solid phase method.The X-ray diffraction spectrum proved that Ce³⁺doped into the matrix and did not produce impurity phases.The emission and excitation spectra of Ce³⁺ion in Na₃ScB₂O₆ matrix show that the emission intensity of the sample increases with the increase of Ce³⁺doping concentration,and the optimal doping molar concentration is 1%;the transition situation corresponding to the spectrum is analyzed.The fluorescence decay curve of the sample was measured,and the fluorescence lifetime was obtained according to the fitting formula.By measuring and analyzing variable temperature spectra,the relationship between fluorescence integral intensity and temperature is obtained,and the mathematical relationship between them is obtained by curve fitting;the best sensitivity for temperature measurement of Na₃ScB₂O₆:0.01Ce³⁺phosphor is calculated to be 1.03%K^-1.The results show that Na₃ScB₂O₆:0.01Ce³⁺phosphor is a potential fluorescent temperature measurement material,which is expected to be applied in the field of fluorescent temperature measurement.A series of Na₃ScB₂O₆:Ce³⁺,Mn²⁺phosphors were prepared by high-temperature solid-phase method.X-ray diffraction spectra showed that Ce³⁺and Mn²⁺were successfully doped into the matrix without producing impurity phases.The emission and excitation spectra of Ce³⁺and Mn²⁺ions in Na₃ScB₂O₆ matrix were studied.The results show that when Ce³⁺and Mn²⁺are co-doped,the best doping concentration of Mn²⁺is 9%when the Ce³⁺doping concentration is 1%.By comparing the excitation spectra of Mn²⁺with the emission spectra of Ce³⁺,the changes in the emission spectra when Ce³⁺and different concentrations of Mn²⁺are co-doped and the changes in the fluorescence lifetime of Ce³⁺at different Mn²⁺doping concentrations,it can be proved that there are resonant energy transfer of Ce³⁺-Mn²⁺in Na₃ScB₂O₆:Ce³⁺,Mn²⁺.The study of variable temperature spectroscopy shows that the best sensitivity and resolution of Na₃ScB₂O₆:0.01Ce³⁺,0.09Mn²⁺phosphors as a fluorescent temperature measurement material at 473K are 1.13%K^-1 and 0.007K,respectively.And the material is in the repeated temperature rising-cooling process,it can maintain good sensitivity stability in both.The Ce³⁺and Mn²⁺co-doped dual-emission Na Mg BO₃:Ce³⁺,Mn²⁺phosphors were prepared by high temperature solid phase method.The crystal structure,morphology,photoluminescence,energy transfer mechanism,and temperature-related sensing properties are systematically studied.The morphology of the sample was measured by SEM and element analysis was carried out to confirm the uniformity of the sample’s element distribution.The phosphor exhibits strong dual broadband emission.The blue emission at 475 nm is attributed to the d-f transition of Ce³⁺,and the infrared emission at 710 nm is attributed to the ⁴T_1g（G）-⁶A_1g（S）transition of Mn²⁺.By comparing the excitation spectrum of Mn²⁺with the emission spectrum of Ce³⁺,the change of the emission spectrum when Ce³⁺is co-doped with different concentrations of Mn²⁺,and the fluorescence lifetime of Ce³⁺at different Mn²⁺doping concentrations,it can be proved that there are resonant energy transfer of Ce³⁺-Mn²⁺in Na Mg BO₃:Ce³⁺,Mn²⁺phosphors.Energy transfer occurs between Ce³⁺-Mn²⁺ions through exchange interaction.The critical distance for concentration quenching is calculated to be Rc=13.09?,and when the doping concentration of Mn²⁺ions is 6%,the fluorescence is the pink luminous intensity is the highest.The fluorescence intensity ratio technique is used to analyze the luminescence of samples in the temperature range of 298K-473K,and fitting is performed,and the best sensitivity and resolution of Na Mg BO₃:0.01Ce³⁺,0.06Mn²⁺phosphors as fluorescent temperature measurement materials at 473K are 0.69%K^-1 and 0.01K.The Na Mg BO₃:0.01Ce³⁺,0.06Mn²⁺phosphor exhibited good sensitivity stability during the eight-time rise-fall temperature process.The Na Mg BO₃:0.01Ce³⁺,0.06Mn²⁺phosphors prepared based on the above properties have been explored for integrated optoelectronic device temperature measurement,wound healing and optical temperature sensing,and provided guidance for the development of the same type of fluorescent temperature measurement materials.