Research And Application On Optical Properties Of Transition Metal And Rare Earth Ion Doped Luminescent Materials

Temperature is closely related to our production and daily life.In the development of various industries,temperature control is also an indispensable part.Therefore,finding a temperature detection method with high sensitivity is currently the focus of researchers’exploration.Non-contact optical temperature sensing methods based on the luminescent properties of materials,such as fluorescence lifetime and fluorescence intensity ratio thermometry,have the advantages of real-time,sensitivity,and accuracy,which can avoid the effects of test objects and environments,reduce errors caused by non-temperature factors interference,and have been attracting great attention.However,non-contact optical temperature measurement methods still have some limitations.Different matrix materials have a significant impact on the luminescent properties of activator ions,requiring the selection of appropriate matrix materials to optimize the luminescent properties and improve the fluorescence intensity.For fluorescence lifetime thermometry,it is necessary to select a suitable emission center to improve the temperature measurement sensitivity.For fluorescence intensity ratio thermometry,it is necessary to avoid the influence of thermal coupling energy levels on temperature measurement sensitivity.Currently,research on fluorescence temperature measurement materials is mostly limited to the experimental stage and needs further exploration to apply them practically in the field of temperature detection.To address these issues,this study selects appropriate matrices to prepare fluorescent materials,optimizes experimental parameters to enhance the luminescent intensity of the materials,and conducts in-depth research and discussion on the luminescent and temperature sensing properties of the materials.The aim is to obtain fluorescent materials with higher temperature measurement sensitivity and utilize them to design practical temperature sensing systems.A series of Mn⁴⁺-doped Sr Al₁₂O₁₉ phosphors were prepared using a high-temperature solid-state method.The effects of Mn⁴⁺doping concentration,sintering temperature,and B₂O₃ co-doping ratio on the luminescent properties of the phosphors were analyzed systematically using a controlled variable method,and the optimal luminescent material was obtained based on the above analysis.The phase structure of the prepared fluorescent material was determined through crystal cell structure and XRD analysis.The Mn⁴⁺energy transfer mechanism was determined through the critical quenching concentration of Mn⁴⁺.By using diffuse reflectance absorption spectra,emission spectra,low-temperature and variable-temperature spectra,Tanabe-Sugano diagrams,and positional coordinate diagrams,the level transitions of Mn⁴⁺and the fluorescence quenching mechanism were comprehensively analyzed.The potential application value of this material in temperature sensing was clarified.Finally,under the excitation of a 405 nm laser,the fluorescence lifetime of Mn⁴⁺decreased significantly with increasing temperature.By measuring the fluorescence peak lifetime produced by the ²E_g→⁴A_2g level transition of Mn⁴⁺at 658 nm,a maximum relative temperature sensitivity of 7.86%K^-1 was obtained at 373 K.Y₃Al_5-xGa_xO₁₂:Eu³⁺（x=0～5）luminescent materials were synthesized by high-temperature solid-phase method,and the influence of Ga³⁺doping on the structural parameters and diffraction peak positions was studied through lattice structure analysis and XRD characterization.The luminescent properties of the materials under 405 nm laser excitation were investigated,and it was confirmed that most of the Eu³⁺ions occupied the inversion symmetry positions and successfully replaced the Y³⁺ions located at the D₂ point.Furthermore,it was found that the increase of the Ga/Al doping ratio would cause the distortion of the coordination polyhedron of Eu³⁺,leading to changes in non-radiative transitions and resulting in the first increase and then decrease of Eu³⁺luminescence intensity.Based on this,a mixed material of Sr Al₁₂O₁₉:0.1 mol%Mn⁴⁺/Y₃Al_5-xGa_xO₁₂:1mol%Eu³⁺was synthesized,and it was found that the fluorescence intensities generated by the ⁵D₀→⁷F₁ transition of Eu³⁺and the ²E→⁴A₂ transition of Mn⁴⁺had different temperature dependencies.Therefore,a method based on the fluorescence intensity ratio of non-thermal coupling energy level was proposed for temperature measurement,and the maximum relative temperature sensitivity of 4.15%K^-1 was obtained at 373 K,which was higher than most known temperature measurement methods based on thermal coupling energy levels,breaking the limitation of thermal coupling energy levels and improving the sensitivity of temperature measurement.The prepared fluorescent material was used for real-time temperature measurement.An optical system was designed to collect the fluorescence decay signal generated by the405 nm laser excitation of Sr Al₁₂O₁₉:0.1 mol%Mn⁴⁺material and output the signal.An optoelectronic detection circuit was established to convert and amplify the fluorescence signal into a potential signal for subsequent calculation and processing.The optimal fluorescence lifetime calculation method was determined by comparative analysis.A data acquisition and processing system was designed to convert the potential signal output by the optoelectronic detection circuit into a digital signal and perform data processing.By extracting the fluorescence decay data,the fluorescence lifetime was calculated and the relationship between fluorescence lifetime and temperature was established to calculate the temperature.The three subsystems were combined to form a fluorescence lifetime temperature sensing system,which realized real-time temperature measurement in the temperature range of 30～100℃with an absolute error within±2℃.