Research On Optical Temperature Behavior Of Novel Rare Earth Doped Fluorescent Materials Based On FIR Technique

As we all know,the accurate measurement of temperature has non-negligible significance in the fields of medical surgery,military defense,aerospace materials and many other fields.The non-contact optical temperature detection mode has been regarded as an ideal research point in the field of temperature detection in recent years due to its insurmountable characteristics of traditional temperature measurement modes.Among them,the fluorescence intensity ratio（FIR）technology based on the thermal coupling energy level of the same rare earth ions and the FIR technology between transition metal ions and rare earth ions have attracted the attention of researchers.The focus of this thesis is to improve the sensitivity of FIR technology.The screened matrix materials are molybdate,tungstate and tantalate.And the doping ions are Er³⁺,Ho³⁺,Tm³⁺,Yb³⁺,Eu³⁺and Mn⁴⁺.A series of up-conversion and down-conversion fluorescent materials for luminescence and temperature sensing were synthesized by the traditional high-temperature solid-phase method,and the structures,luminescence and temperature detection properties of the as-synthesized materials were characterized.The main research content of this thesis includes the following parts:A series of single-phase LiYbMo₂O₈:Ln³⁺（Ln=Er/Ho/Tm）,LiYbW₂O₈:Ln³⁺（Ln=Er/Ho）,and LiLuW₂O₈:Yb³⁺,Er³⁺up-conversion fluorescent materials were prepared by traditional high-temperature solid-phase method by selecting LiYbMo₂O₈,LiYbW₂O₈,and LiLuW₂O₈ as matrices.A near-infrared pump excitation light source of 980 nm was used to study the structure,luminescence properties,energy transfer mechanism,and temperature sensing properties of the samples.The maximum relative sensitivities of LiYbMo₂O₈:Ln³⁺（Ln=Er/Ho/Tm）up-conversion fluorescent materials can reach the highest 1.16%K^-1,0.25%K^-1,0.51%K^-1 in the range of 300-500 K,respectively.The maximum relative sensitivities of LiYbW₂O₈:Er³⁺and LiYbW₂O₈:Ho³⁺fluorescent materials are 1.62%K^-1,and 0.70%K^-1,respectively.The relative sensitivity of LiLuW₂O₈:Yb³⁺,Er³⁺is as high as1.41%K^-1.The above results all indicate that the as-synthesized up-conversion fluorescent materials have the possibility of being applied in the field of temperature sensing.Sr₂ScTaO₆:Eu³⁺,Sr₂ScTaO₆:Mn⁴⁺,and Sr₂ScTaO₆:Mn⁴⁺,Eu³⁺down-conversion fluorescent materials were synthesized by high-temperature solid-phase method.The structural properties,luminescence properties,and temperature sensing properties were investigated.The spectral characteristics of Sr₂ScTaO₆:Mn⁴⁺,Eu³⁺fluorescent material mainly prove that there is no energy transfer between Mn⁴⁺and Eu³⁺ions.The emission of Eu³⁺ions is used as the reference signal,the emission of Mn⁴⁺ions is used as the temperature sensing signal,and the temperature detection of the Sr₂ScTaO₆:Mn⁴⁺,Eu³⁺fluorescent material is realized by using the FIR law,and the best relative sensitivity of this material is 3.66%K^-1,which proves that the temperature sensing characteristics of the Sr₂ScTaO₆:Mn⁴⁺,Eu³⁺fluorescent material has superior temperature sensing properties.