Study On Optical Temperature Sensing Properties Of Pr³⁺,Tm³⁺Co-doped And Sm³⁺,Tm³⁺Co-doped Gd₂Ti₂O₇ Phosphors

Temperature is a state parameter that describes the degree of hot and cold of an object.In production life precise control and accurate measurement of temperature is necessary in many situations.Therefore,researchers have paid much attention to optical temperature sensing materials that can measure temperature accurately.Existing studies demonstrate the numerous,irreplaceable benefits of temperature sensing materials based on the Fluorescence Intensity Ratio(FIR)of rare earth ions,including non-contact,quick response times,and high temperature resolution.Existing reports mainly focus on Thermally Coupled Energy Levels(TCL)optical temperature sensing materials,such as Er3+,Eu3+,Tm3+and other rare-earth ion-doped optical temperature sensing materials,have received a great deal of attention.However,the distance between the thermally coupled energy levels is between 200-2000 cm-1,which is an inherent property of the ion itself and cannot be further expanded,which makes the luminous wavelengths of the two thermally coupled energy levels very close to each other and easily overlap,which is detrimental to the temperature measurement accuracy of FIR;the luminescence colors of the two energy levels are relatively close to each other,and the temperature change cannot be estimated by the luminescence color of the material;more importantly,due to the temperature measurement mechanism of thermally coupled energy levels,the relative sensitivity of light-emitting materials is limited by the spacing of energy levels,which is difficult to further improve.Therefore,Non-Thermally Coupled Energy Levels(NTCL)temperature sensing materials have gradually become a research hotspot.This research utilized Pr3+,Tm3+co-doped and Sm3+,Tm3+co-doped Gd2Ti2O7 phosphors to thoroughly examine the optical temperature sensing properties of two non-thermally coupled energy-level temperature sensing materials.Four major sections make up the research material of paper.(1)Hydrothermal preparation of Gd2Ti2O7:Pr3+,Tm3+phosphors employing urea as precipitant.X-ray diffractometry(XRD)and field emission scanning electron microscopy(FE-SEM)were used to examine and describe the structure and morphology of materials.Under excitation at 361 nm,the temperature-dependent emission spectrum of Gd2Ti2O7:x%Pr3+,1%Tm3+(x=0.1,0.3,0.5,1)phosphor were made in the temperature range of 293 to 403 K.It can be observed that there was an emission peak of Pr3+at 614.5 nm(1D2-3H4),an emission peak of Tm3+at 458 nm(1D2-3F4).Furthermore,it was clear how the luminescence thermal quenching trends of Pr3+and Tm3+differ.As a result,temperature had a big impact on the FIR of Pr3+to Tm3+,and it gets bigger as the temperature rises.The maximum relative sensitivity of Gd2Ti2O7:x%Pr3+,1%Tm3+(x=0.1,0.3,0.5,1)phosphor was 2.3%K-1(298.2 K,0.1%Pr3+,1%Tm3+),as the calculations for fitting show.(2)The hydrothermal method was used to obtain Sm3+,Tm3+co-doped Gd2TiO7 phosphors,using urea as the precipitant.XRD and FE-SEM were used to evaluate and describe the shape and structure of samples.By observing the optical temperature-dependent emission spectra of Gd2Ti2O7:x%Sm3+,1%Tm3+samples(x=0.1,0.3,0.5,1),it was learned that the luminescence intensity of the three emission peaks 4G5/2-6H5/2,4G5/2-6H7/2,4G5/2-6H9/2 for Sm3+and the emission peak 1D2-3F4 decreased with increasing temperature.And the luminescence thermal quenching trend of Tm3+was more obvious compared to that of Sm3+,so the FIR of Sm3+to Tm3+can come to indicate the temperature.Experimental calculations showed that the relative sensitivity of Gd2Ti2O7:0.1%Sm3+,1%Tm3+had a maximum value of 3.1%K-1 at 297.7 K.For inorganic materials,this was a fantastic value.The results of this paper show that Pr3+,Tm3+co-doped and Sm3+,Tm3+co-doped Gd2Ti2O7 have excellent temperature sensing properties,and have certain application potential in FIR type optical temperature sensing.The research results of this paper are innovative in the material design and preparation methods of titanate system optical temperature sensing materials,and provide a reference for the innovation and performance improvement of optical temperature sensing materials.