Study On Optical Temperature Sensing Materials Of Pr³⁺ Activite And Pr³⁺,Tb³⁺ Co-activite NaGd(MoO₄)₂

Temperature is an important physical quantity that cannot be avoided in the study of both the macro and micro worlds,and the measurement of temperature is also the crucial to technological breakthroughs in manufacturing,medical health,national defense science and technology and other fields.In a multitude of means of temperature measurement,non-contact temperature sensing methods have gradually received attention,so temperature measurement methods based on fluorescence intensity ratio have developed strongly in recent years.The most common fluorescence intensity specific type temperature sensing material usually selects a pair of thermal coupling energy levels with obvious differences in luminescence intensity and thermal quenching trend at different temperatures on the rare earth luminescence center,and then measures and calculates the dependence between the fluorescence intensity ratio and temperature of the two,ultimately attain the objective of temperature sensing.However,materials that rely on thermally coupled energy levels for temperature sensing have a natural defect,that is,the two energy levels are located in close proximity,and the relative sensitivity of the material is not enough to continue to improve.In order to surmount the anterior defective,this paper will synthesize Pr³⁺activated and Pr³⁺,Tb³⁺co-activated NaGd(MoO₄)₂ temperature sensing phosphors,using Pr³⁺pair of non-thermally coupled energy level fluorescence intensity ratio and Pr³⁺,Tb³⁺fluorescence intensity ratio to characterize temperature,and study in detail the optical temperature sensing properties of the two materials.The general elements of this dissertation includes the hereinafter 4points:(1)By controlling the addition of the chelating agent sodium citrate(Cit^3-/Re³⁺=0,0.5,1,2)with different morphologies of Pr³⁺activated NaGd(MoO₄)₂luminescent materials and Pr³⁺,Tb³⁺co-activated NaGd(MoO₄)₂ luminescent materials were prepared by hydrothermal method,and the crystal structure and morphology of the luminescent materials were represented by X-ray diffractometer and FE-SEM,and the XRD consequences indicated that the materials obtained in this experiment presented a body-centrocentric quadrangular structure.FE-SEM showed that different chelating agent dosages affected the topography of the sample and analyzed the reasons for the alter in the morphology of the sample.(2)The variable temperature emission spectrum of the NaGd(MoO₄)₂:1%Pr³⁺(Cit^3-/Re³⁺=0,0.5,1,2)luminescent material was measured in the thermal scope of293-483 K,and its optical temperature sensing properties were further studied on this basis.By comparing the ratio of the fluorescence intensity value of the emission peak at490 nm(~3P₀-~3H₄)and 651.5 nm(~3P₀-~3F₂)and the fluorescence intensity value of the emission peak at 605 nm(~1D₂-~3H₄),respectively,this paper can obtain the evolutionary relationship of the fluorescence intensity ratio at different temperatures,and the mutual printing of the two sets of data can improve the accuracy and achieve self-calibration.In addition,the results of this paper show that the relative sensitivity of Pr³⁺activated NaGd(MoO₄)₂ samples at the same temperature increases as the rising of complexing agent consumption in the low temperature range,but decreases as the rising of complexing agent consumption in the high temperature region.This result is due to the addition of chelating agents that alter the microenvironment of the rare earth luminescent center.(3)The variable temperature emission spectrum of The Pr³⁺,Tb³⁺co-activated NaGd(MoO₄)₂ luminescent material was measured in a temperature range of 298-483K.The results show that as the rising of temperature,the fluorescence intensity ratio(FIR)value of the material increases significantly.With the increase in the amount of sodium citrate added,the maximum relative sensitivity of the samples in this group was also improved,because the addition of chelating agents changed the luminescent microenvironment of Pr³⁺,Tb³⁺as the center of luminescence,and then changed the shape of their spectral lines.The research data confirmed that cit^3-/Re³⁺=2 obtained the maximum value of 3.2%K^-1 of the relative sensitivity of this group of experiments at434.2 K,which is higher than other co-activated molybdenum hydrochloride materials and is an excellent temperature sensing material.In addition,the luminous color of the sample changes from green to red in the temperature scope of 298-483 K,which is convenient for the naked eye to directly observe the temperature change.(4)The repeatability of phosphor FIR temperature measurements is important for practical applications of optical temperature sensing materials.In this paper,the Temperature cycle test of Pr³⁺activated NaGd(MoO₄)₂ luminescent material and Pr³⁺,Tb³⁺co-activated NaGd(MoO₄)₂ luminescent materials was carried out,and the test results showed that the experimental phosphor FIR temperature measurement was reproducible and had high practical application value.The results of this paper confirm that the Pr³⁺activated NaGd(MoO₄)₂ and Pr³⁺,Tb³⁺co-activated NaGd(MoO₄)₂ light-emitting materials have excellent temperature sensing functions.In this paper,the amount of different chelating agents is controlled in the experiment,which not only makes the morphology difference,but also significantly improves the optical temperature measurement performance of the material.The research results of this paper point out a new direction for the selection and preparation of FIR-type optical temperature sensing materials.