Investigation On Fluorescence Temperature Sensing Performance Of Fluorescent Material Based On Dual-Emission Center

As one of the most basic thermodynamic physical quantities,temperature is the most fundamental parameter in all materials and any type of research.Due to the defects and shortcomings of traditional contact thermometers,such as long measurement time,low measurement accuracy and large structure size,the non-contact temperature measurement methods based on the optical properties of luminescent materials,as a kind of promising temperature measurement approachs,have been widely concerned and studied.Among all the non-contact optical temperature sensing methods,the temperature measurement method based on the fluorescence intensity ratio technology can overcome the dependence on detection conditions such as probe concentration,material uniformity,and excitation source power,reduce measurement errors and improve detection accuracy.It has become a hotspot in the research of non-contact optical temperature sensors.In this paper,three new fluorescent materials with dual-emission center were developed and their luminescence characteristics and fluorescence temperature sensing performance were systematically investigated.LaAlO₃:Eu²⁺/Eu³⁺phosphors were synthesized by high temperature solid state reaction.Their crystal structure,luminescent properties and temperature dependent luminescent properties were studied by X-ray diffraction data,X-ray photoelectron spectroscopy,fluorescence spectra and temperature-dependent photoluminescence spectra.The Eu²⁺/Eu³⁺coexisting LaAlO₃ phosphor has excellent optical temperature sensitive performance.The maximum absolute temperature sensitivity and relative temperature sensitivity reach 0.014 K^-1 and 1.193%K^-1,respectively.At the same time,the two signal peaks monitored are well separated,providing good signal discrimination.La_1-yGd_yAlO₃:0.03Eu（y=0.2-0.8）phosphors were prepared by high temperature solid phase reaction method.The normal thermal quenching behavior of Eu²⁺ion and the abnormal thermal quenching phenomenon of Eu³⁺ion in La_1-yGd_yAlO₃:0.03Eu phosphors were explained by the configuration coordinate model and energy transfer process.The temperature sensitivity of phosphor increases with the increase of Gd³⁺concentration when the temperature sensing performance of phosphor is studied by using the fluorescence intensity ratio temperature measurement technology.When the concentration of Gd³⁺ion is 0.8,the maximum absolute temperature sensitivity and relative temperature sensitivity can reach 0.084 K^-1 and 3.233%K^-1.In addition,the obvious separation of emission peaks of Eu²⁺ion and Eu³⁺ion also provides good signal discrimination for temperature measurement.The single-phase Ce³⁺,Eu²⁺co-doped LiSr₄（BO₃）₃ phosphors were synthesized by high temperature solid state reaction process.The crystal structure,luminescent properties and temperature sensing performance of LiSr₄（BO₃）₃:Ce³⁺,Eu²⁺samples were systematically investigated.The existence of two different crystallographic positions of Sr²⁺ion in the LiSr₄（BO₃）₃ host makes the emission bands of Ce³⁺ion and Eu²⁺ion asymmetric.The temperature-sensitive properties of the phosphors were further studied by analyzing the temperature-dependent luminescence spectra of LiSr₄（BO₃）₃:0.06Ce³⁺,0.04Eu²⁺.The maximum absolute sensitivity and relative sensitivity are 0.056 K^-1 and 4.016%K^-1,respectively.In addition,the emission peaks of Ce³⁺ion and Eu²⁺ion are clearly separated,providing good signal recognition ability.The research results on the temperature sensing performance of the three fluorescent materials show that they have high temperature sensitivity and good signal discrimination,and can be used as excellent temperature sensing materials for non-contact optical temperature measurement.