Preparation And Temperature Sensing Properties Of Ca₂Sb₂O₇ Fluorescent Materials

In recent years,optical temperature measurement based on fluorescence intensity ratio has been favored for its advantages of wide range and high accuracy.Among them,the introduction of two light-emitting centers with different temperature response in the substrate has become the main research direction of optical temperature measurement.Therefore,it is very important to select appropriate substrate materials and doping ions to improve the sensitivity.Based on this point,orthogonal Ca₂Sb₂O₇ was selected as the matrix material to study the luminescence properties and fluorescence temperature characteristics with different doping different ions.The main contents are illustrated as follows:（1）By introducing Bi³⁺and Eu³⁺,Ca₂Sb₂O₇:Bi³⁺,Eu³⁺fluorescent materials were designed and synthesized.Under 330 nm excitation,a wide blue emission band at 440nm and a narrow red emission band at 613nm are produced simultaneously.Based on the energy transfer between Bi³⁺and Eu³⁺ions,the luminescence color of phosphor can be tunable from blue to pink.According to the different thermal quenching mechanism of Bi³⁺and Eu³⁺ions,the optical temperature measurement performance of Ca₂Sb₂O₇:Bi³⁺,Eu³⁺materials was investigated.The maximum absolute sensitivity was 0.2773 K^-1（523 K）,and the maximum relative sensitivity was 2.37%K^-1（448 K）.During the heating process,the phosphor color changed from purple to orange-red.Because of its excellent optical properties,this material has a potential application prospect in the field of fluorescence temperature measurement and thermal discoloration.（2）By optimizing the experimental parameters,the intrinsic luminescence of Ca₂Sb₂O₇ matrix was significantly enhanced,and then the Ca₂Sb₂O₇:Eu³⁺fluorescence material was prepared by doping Eu³⁺ions.Based on the energy transfer between the substrate and Eu³⁺,the phosphor color can be tunable from blue to orange-red.The reverse thermal quenching of Eu³⁺ion was observed during the temperature changing process,and the reverse thermal quenching degree decreased gradually with the increase of Eu³⁺doping content.According to the different thermal quenching behavior between the substrate and Eu³⁺,the optical temperature measurement performance of Ca₂Sb₂O₇:Eu³⁺material is investigated.The maximum absolute sensitivity is 0.3031 K^-1（463 K）,and the maximum relative sensitivity is3.369%K^-1（382 K）.In addition,the effective combination of the phosphor and PDMS film shows good acid and alkali resistance.The results show that the prepared fluorescent materials have potential application prospects in fluorescence temperature measurement and various complex conditions of LED devices.（3）In order to further optimize and improve the performance of fluorescence temperature measurement,Ca₂Sb₂O₇:Eu³⁺,Mn⁴⁺phosphors were synthesized from Eu³⁺and Mn⁴⁺phosphors with different luminescence characteristics.Dual wavelength emission of Eu³⁺and Mn⁴⁺is achieved at 310 nm and 393 nm,and the energy transfer process of Eu³⁺→Mn⁴⁺is discussed.During the heating process,Eu³⁺ion exhibits reverse thermal quenching behavior at 310 nm,while Mn⁴⁺ion exhibits strong thermal quenching behavior.According to the different thermal quenching mechanisms of Eu³⁺and Mn⁴⁺,the optical thermometry properties of Ca₂Sb₂O₇:Eu³⁺,Mn⁴⁺were investigated under dual-wavelength excitation.The maximum absolute sensitivity was 0.0401 K^-1（383 K）and maximum relative sensitivity was 4.072%K^-1（305 K）.The results show that the fluorescence material has potential application prospect in fluorescence temperature measurement,and provides an effective strategy for realizing high resolution,high precision and high sensitivity dual-wavelength excited fluorescence temperature measurement.