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Temperature Sensing Properties Of Rare Earth Doped Materials Based On Erbium Ion In Wide Wavelength Range

Posted on:2022-04-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z H FengFull Text:PDF
GTID:1520307151974669Subject:Theoretical Physics
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With the development of microelectronics,optoelectronics,nanomedicine and other fields,non-contact temperature sensors have attracted more and more attention due to their high spatial resolution,wide temperature measurement range and high sensitivity.Especially,the fluorescence intensity ratio(FIR)technology has been considered as an effective strategy for non-contact optical temperature measurement.The temperature characteristic of FIR of the thermal coupled levels(2H11/2 and 4S3/2)in different Er3+ions doped materials was considered as an interesting research hotspot for the strong luminescence intensity and high temperature sensing sensitivity.However,how to break the limit of the temperature sensitivity because of the small energy gap of thermal coupled levels,and widen the luminescence wavelength interval of sensing signals and the wavelength region for temperature sensing are still big challenges.In this paper,systematic researches concentrating on above problems were carried out.Firstly,the thermal excitation process and FIR temperature sensing performance of 2H11/2 and 4F9/2levels with large energy gap(>2000 cm-1)were studied in Er3+/Yb3+:PLZT by the temperature dependent rate equation theory.Secondly,the multifunctional NaYF4:Er3+nanoparticles were developed,which can achieve efficient temperature sensing performance in visible and near infrared regions.At last,based on the energy transfer between Er3+and Eu3+ions,the broadband multi-color temperature sensing is realized in Er3+/Eu3+:NaYF4 nanoparticles.The research results are presented as follows:1.The optical radiation characteristics and upconversion luminescence mechanism were studied via absorption and upconversion spectrum of Er3+/Yb3+doped PLZT transparent ceramic.The luminescence decay curve of 1535 nm was fitted theoretically based on rate equations to obtain the forward and backward energy transfer probabilities between Er3+and Yb3+ions.The temperature-dependent upconversion luminescence of Er3+/Yb3+doped PLZT transparent ceramic under 980 nm excitation were studied,the thermal coupled levels group of 2H11/2,4S3/2 and 4F9/2 was proved with the intermediate transition level 4S3/2by temperature dependent rate equation theory.The temperature sensing characteristics of FIR of 2H11/2to 4S3/2 and 2H11/2to 4F9/2 were studied,the maximum absolute sensitivity and relative sensitivity of them were obtained as 19.10×10-4 K-1 and 6.1%K-1,respectively.2.The luminescence characteristics of stark splitting levels of 4S3/2and 4F9/2 levels were analyzed based on upconversion spectrum of Er3+/Yb3+doped PLZT transparent ceramics.The temperature dependent luminescence intensities of Stark splitting levels of 4S3/2and4F9/2 levels were studied by thermal quenching mechanisms.The temperature sensing properties of the FIR of 2H11/2 to stark splitting levels of 4S3/2or 4F9/2 were studied,and the maximum absolute sensitivity and relative sensitivity were obtained as 142.4×10-4K-1 and 2.21%K-1,respectively.3.NaYF4:Er3+nanoparticles were prepared by coprecipitation method.The temperature dependent upconversion spectra of NaYF4:Er3+nanoparticles with different Er3+doping concentrations were measured and the temperature sensing characteristics of the FIR of 2H11/2to 4S3/2 were studied.The maximum absolute sensitivity and relative sensitivity were obtained as 75.70×10-4 K-1 and 2.96%K-1,respectively.Meanwhile,the relative sensitivity is greater than 2.0%K-1 in the temperature range from 148K to248K,which shows great low temperature sensing performance in visible region.Moreover,the NaYF4:Er3+nanoparticles present better temperature sensing performance with the suitable low excitation power(0.5421 W),smaller particle size or lower co-doped Yb3+ion concentration.4.The temperature dependent near-infrared spectra of NaYF4:Er3+nanoparticles under517 nm excitation were measured.The temperature characteristics of near-infrared intensities of 837 nm(4S3/2-4I13/2)and 980 nm(4I11/2-4I15/2)were analyzed,which were used to establish the theoretical model of temperature dependent FIR of 980 nm to 837nm.Based on that,the maximum absolute sensitivity and relative sensitivity of near-infrared emission of NaYF4:2.0 mol%Er3+nanoparticles were obtained as 1914×10-4K-1 and 2.10%K-1,respectively.The relative sensitivity is greater than 2.0%K-1 in the biosensing temperature range from 270 K to 320 K,which shows great low temperature sensing performance in near-infrared region.5.β-NaYF4:Er3+/Eu3+nanoparticles were prepared by coprecipitation method.The characteristics of photoluminescence of samples under the 377 nm excitation were studied to confirm the energy transfer process from Er3+to Eu3+ions combined with the results of Eu3+doping concentration dependent fluorescence lifetimes of 541 nm.The temperature sensing properties of FIRs of emissions intensities of red,orange,yellow and green were studied based on the temperature dependent fluorescence spectra of NaYF4:Er3+/Eu3+nanoparticles.The maximum absolute sensitivity and relative sensitivity were obtained as 103.9×10-4 K-1 and 1.85%K-1,respectively.
Keywords/Search Tags:Temperature sensing, Fluorescence intensity ratio, Er3+ions, NaYF4nanoparticles, PLZT transparent ceramics
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