Synthesis And Temperature Sensing Of Near Infrared Luminescent Lanthanide Materials

Temperature is one of the most important physical quantities in thermodynamics.As the development of scientific study,the measurement of temperature in extreme environments such as biological tissues is of great significance and a challenging subject.The thermometer based on fluorescence temperature sensor can satisfy the thermometry necessities of non-contact,miniaturization,high spatial resolution and fast response real-time detection.In this work,varieties of rare earth organic complexes were prepared by solvothermal method.The crystal structure of the coordination compound was refined and characterized.The luminescence feature is studied.The temperature sensing is achieved via using the fluorescence intensity ratio in a certain temperature range.The temperature sensing capability of sample is studied by utilizing the relvative sensitivity?SR?,the resolution??T?and repeatability?R?as parameters.The main researches and results are threefold:Multiform lanthanide organic complexes(Ln-PDC,Ln=Eu,Tb,Gd,Eu_xTb_2-x,Gd_1.5Nd_0.4Yb_0.1,PDC=3,5-Pyridinedicarboxylic Acid)were synthesized by using different rare earth ions(Eu³⁺/Tb³⁺,Gd³⁺/Nd³⁺/Yb³⁺)as luminescent centers and H₂PDC is ligand.The single crystal structure of Eu-PDC is analyzed and refined.The structural characterization of other samples illustrates that they are isomorphic with Eu-PDC.Luminescence characteristics and energy transfer process of Ln-PDC are studied.Fluorescence intensity ratio of different emission peaks(Tb³⁺@542 nm/Eu³⁺@611 nm;Nd³⁺@1052 nm/Yb³⁺@1005 nm)as luminescence parameter is used to realize temperature sensing within a certain temperature range.The result shows that Eu_0.05Tb_1.95-PDC and Gd_1.45Nd_0.40Yb_0.15-PDC have excellent temperature sensing property.The crystal structure of Nd-PDC and Nd_1.43Yb_0.57-PDC is different from that of Eu-PDC is illustrated by powder XRD.Besides,the emission spectrum has two splitting peaks?1054,1065 nm?of Nd-PDC in the range of 1025-1095 nm under excited 808 nm laser.In the range of 298-368 K,the temperature dependence test shows that fluorescence intensity ratio I₁₀₆₅/I₁₀₅₄ has a desirable linear relationship of temperature,and achieved luminescence temperature sensing in the second biological transparent window.Specially,the temperature resolution?T of this sample is less than 0.07 K in the range of physiological temperature.Similarly,the binuclear complex Nd_1.43Yb_0.57-PDC is used for temperature sensing in 298-368 K.The luminescence parameter is intensity ratio Yb³⁺@1005 nm/Nd³⁺@1065 nm.The result shows that two materials can realize the temperature sensing based on near-infrared excitation-emission.The lanthanide organic complexes Nd-BPDC and Nd_0.70Yb_0.30-BPDC were synthesized by the ligand of 2,2'-Bipyridine-5,5'-dicarboxylic acid?H₂BPDC?.The luminescence characteristics and internal energy transfer process are investigated.Under excited 808 nm laser,utilizing the intensity ratio(I_Nd/I_Yb)as luminescence parameter,the temperature sensing of Nd_0.70Yb_1.30-BPDC in the range of physiological temperature?298-348 K?is realized.The results show that Nd_0.70Yb_1.30-BPDC has potential application in the field of biological temperature measurement.