Study On Rare Earth Doped Temperature Sensing Phosphor Based On Fluorescence Intensity Ratio

Temperature is one of the important physical parameters.Temperature play an extremely important role in the fields of production,life and scientific research.Due to the limitations of traditional contact thermometers,it cannot be used in special environments such as strong electric fields,strong magnetic fields,corrosiveness,micro-nano dimensions,and living biological cells.Therefore,a new type of non-contact temperature sensor with anti-interference,high spatial resolution,fast response and the ability to achieve remote measurement has attracted researcher's attention.Various types of non-contact temperature sensing materials are mostly based on the optical properties of the material,and there are multiple ways to achieve fluorescence temperature detection.The fluorescence intensity ratio technology is one of the more accurate methods due to its self-correcting effect.In this thesis,four rare-earth doped light-emitting materials are designed and prepared,and the potential application of these four materials in temperature sensitivity is studied based on the fluorescence intensity ratio characteristics.The main research contents and results of this article are as follows:In the first part,Ba₃La?VO₄?₃: Eu³⁺ phosphor was successfully synthesized by high-temperature solid state reaction method.By changing the doping concentration of Eu³⁺,the emission color can be tunable from green to red.At the same time,it was found that the sample can be used to achieve temperature sensing in two ways.On the one hand,the emission spectrum was used to achieve temperature measurement with intensity ratios of VO43-?400-580 nm?and Eu³⁺?7F0?5D2?,and its maximum sensitivity is SA= 0.0515 K-1 and SR=1.77%K-1@298K.On the other hand,the peak position of excitation spectrum can be used to measure the temperature.As the temperature increases,the position of the V5+?O2-charge transfer band gradually shifts to longer wavelengths,and its absolute sensitivity and relative sensitivity are SA=0.0614 nm K-1 and SR=0.01923% K-1@298 K,respectively.The results show that Eu³⁺ activated Ba₃La?VO₄?₃ phosphor has potential application value in color-tunable luminescent materials and non-contact optical temperature measurement.In the second part,Sr8 Mg La?PO4?7: 0.3Tb3+,Eu³⁺ phosphors were successfully synthesized by high-temperature solid state reaction method.Due to the energy transfer of Tb3+?Eu³⁺,the emission color of Sr8 Mg La?PO4?7: 0.3Tb3+,x Eu³⁺ phosphor can be tunable from green to red.Using Dexter-Reisfeld formula,it was determined that the Tb3+?Eu³⁺ energy transfer mechanism is an electric quadrupole-quadrupole mechanisms.The temperature sensing can be realized by two approachess: the intensity ratio of the emission spectrum and the fluorescence lifetime.The intensity ratio of the emission spectrum is achieved using the integrated intensity ratio?I616/ I544?between the Eu³⁺?5D0?7F2?transition at 616 nm and the Tb3+?5D4?7F5?transition at 544 nm,and its maximum relative sensitivity The SR is 1.3% K-1@573 K.The fluorescence lifetime temperature sensitivity is obtained by fitting the fluorescence lifetime of Tb3+ ions at 544 nm at different temperatures,and the obtained the sensitivity SR is 0.7% K-1?573 K?.The results show that Sr8 Mg La?PO4?7: Tb3+,Eu³⁺ phosphors can be used in color-tunable luminescent materials and fluorescent temperature-sensitive fields.In the third part,Pr3+ activated Sr Mo O4 phosphor were successfully synthesized by high-temperature solid state reaction method.The results show that the samples have different quenching concentrations at different wavelengths,such as 601 nm quenching concentration is 0.5%,and 647 nm quenching concentration is 3%.This is due to the occurrence of multi-phonon relaxation and cross relaxation in Pr3+ ions.The dependence of fluorescence characteristics on temperature is discussed in detail,and it was found that the sample also has two temperature sensing methods: Based on the intensity ratio of the emission spectrum,the maximum absolute sensitivity and relative sensitivity are SA=0.348% K-1@298 K,SR=0.45% K-1@423 K The sensitivity obtained from the excitation spectrum intensity ratio is SA= 4.52% K-1@298K,SR=0.98% K-1@298K.These results indicate that Pr3+ activated Sr Mo O4 phosphors have potential application value in non-contact optical temperature measurement.In the fourth part,Lu2 Mo O6: Eu³⁺ phosphor was successfully synthesized by high-temperature solid state reaction method.The sample has a broad-band excitation spectrum from 250 nm to 440 nm and a red emission spectrum.Under the excitation of 365 nm,its emission center is at 610 nm,corresponding to the 5D0?7F2 transition of Eu³⁺ ion.A warm white light composite material can be obtained by mixing a commercial green phosphor,a blue phosphor,and a prepared red phosphor.The white light emitted by the material under 365 nm excitation has a color temperature of 4271 K and a color rendering index?CRI?of 78.Temperature sensing was achieved by using Eu³⁺ temperature quenching in the emission spectrum and intensity ratios at different wavelength positions of the charge transfer band in the excitation spectrum.The relative sensitivity obtained by Eu³⁺ temperature quenching in the emission spectrum is SR=4.35%@298K,and the different wavelength intensity ratios of the charge transfer band in the excitation spectrum achieve sensitivity SR=2.56% K-1@423K.All the results show that Lu2 Mo O6: Eu³⁺ fluorescent material has its potential application value in the field of white LED and temperature sensing.The four materials have different characteristics based on the field of intensity ratio temperature sensing.Ba₃La?VO₄?₃: Eu³⁺ phosphor can achieve maximum sensitivity at 298 K,while Sr8 Mg La?PO4?7: 0.3Tb3+,Eu³⁺ phosphor has maximum sensitivity at 573 K,Sr Mo O4: Pr3+ has low sensitivity but can achieve dual-mode temperature sensing of excitation and emission spectra.Lu2 Mo O6: Eu³⁺ has the highest sensitivity but its temperature probe peaks partially overlap,which is unfavorable for signal monitoring.