Study On Near Infrared Emission And Temperature Sensitive Properties Of Rare Earth Luminescent Materials

Temperature is one of the most basic and important physical parameters,and it affects all aspects of daily life,industrial production and scientific research.Therefore,the accurate measurement of temperature has very important practical significance in scientific research,industry,military and other fields.During temperature measurement,traditional thermometers need to be in contact with the measurement object.These thermometers have considerable limitations in some extreme environments.Moreover,with the continuous advancement of science and technology,traditional temperature measurement technology can no longer meet the temperature measurement requirements of high-tech fields such as nanomaterials and biological cells.In this case,luminescence-based temperature measurement technology has gradually become a research hotspot because of its advantages such as non-contact and fast response.Currently,the key materials used for luminescence temperature sensing include phosphors,organic dye molecules,quantum dots,nanomaterials,and glass ceramics.Compared with other luminescent temperature sensing materials?such as phosphors and glass ceramics?,rare earth luminescent materials have low absorption energy,high emission quantum yield,diverse energy transfer processes,adjustable topology,and sensitivity to temperature changes in the luminescent center.And other advantages have aroused widespread concern of scientific researchers.With the deepening of research,researchers have found that near-infrared rare earth luminescent materials have unparalleled advantages in the fields of biological imaging,fluorescent probes,drug transport,and light-emitting microscopes.Temperature sensing based on near-infrared luminescence has become a research hotspot in temperature measurement in the biomedical field in recent years.In this paper,Yb³⁺ single-doped KLa₅O₅?VO₄?₂ phosphor was successfully prepared by high-temperature solid-phase method.The crystal structure characteristics,near-infrared characteristics and energy transfer mechanism of the sample were studied,and the energy transfer efficiency was theoretically calculated.A series of rare earth organic complexes were synthesized by solvothermal method using 4,6-tris?4-carboxyphenyl?-1,3,5-triazine as ligand.The elemental composition and molecular formula of a series of samples were calculated and analyzed,and the emission characteristics in the visible region and the near-infrared emission characteristics were studied.For the rare earth organic complex materials in the visible region,a variety of mechanisms including fluorescence intensity,fluorescence lifetime,and fluorescence intensity ratio have been used to achieve high-sensitivity temperature sensing.The temperature detection of the second biological window in the physiological temperature range of the near-infrared rare earth organic complex material was realized by using the fluorescence intensity ratio.The main research contents and results are as follows:Yb³⁺ single-doped KLa₅O₅?VO₄?₂ phosphor was successfully prepared by a high-temperature solid-phase method.The crystal structure parameters of KLa₅O₅?VO₄?₂ after Yb³⁺ doping were studied by XRD refining.Yb³⁺ doping did not change the matrix crystal structure.Calculated from the ultraviolet diffuse reflectance spectrum,the sample band gap is 3.8 e V,which is larger than 1.12 e V of the silicon solar cell.The energy transfer mechanism in the system was explored through the fluorescence excitation emission spectrum of the matrix.Based on the theory of Yb³⁺ excitation emission intensity as a function of concentration,the energy transfer efficiency was calculated to be 23.4% at a doping concentration of 7%.The experimental results show that the 2F5/2?2F7/2 energy level of Yb³⁺ can be efficiently sensitized by the V-O broadband charge transport state and emit near-infrared photons at 980 nm.A series of bright,highly temperature-sensitive rare earth organic complexes Tb-TCTZ,Eu-TCTZ and Tb0.99Eu0.01-TCTZ were successfully synthesized by solvothermal method.The elemental composition and molecular formula of a series of samples were calculated and analyzed by C,H,O,N element analysis technology and ICP-MS technology,and the correctness of the speculative molecular formula and the target combination were proved by XRD,Fourier infrared,and thermal weight loss analysis technology Consistency of structures.Studies on the fluorescence characteristics of a series of samples found that the TCTZ ligand has a strong broad absorption at 340 nm in the near-ultraviolet region,which can effectively sensitize rare earth ions.body.The temperature sensing of Tb-TCTZ samples in the temperature range of 303?403 K was used to calculate the maximum relative sensitivity of Tb-TCTZ samples of 5.36 %K^-1 and 1.69 %K^-1.Using the fluorescence intensity ratio mechanism to study the temperature sensing characteristics of Tb0.99Eu0.01-TCTZ in the temperature range of 303?403 K,the maximum relative sensitivity of the sample at 403 K was calculated to be 3.22 %K^-1.And Tb0.99Eu0.01-TCTZ luminescence gradually changes from yellow-green to orange-red as temperature changes,indicating that it has great application potential in the field of temperature visualization.The rare earth organic complexes Nd-TCTZ,Yb-TCTZ and Nd0.25Yb0.75-TCTZ with excellent near infrared emission and high temperature sensitivity were successfully synthesized by solvothermal method.Under the excitation of 808 nm near-infrared laser,based on the fluorescence intensity ratio of Yb³⁺ and Nd³⁺,the temperature detection of the second biological transparent window in the physiological temperature range?293?353 K?was realized.It is calculated that the relative sensitivity Sr reaches 1.02 %K^-1 at 293 K,and the sample has high repeatability.