A ratiometric temperature detection method based on rare earth Dy-Er energy transfer

Abstract

The present invention belongs to the field of temperature detection technology and discloses a ratio-type temperature detection method based on rare earth Dy-Er energy transfer. The steps include measuring luminous intensity, calculating luminous intensity ratio, obtaining the relationship curve between luminous intensity ratio and temperature, fitting with formula, and finally obtaining a quantitative relationship. 3+ Xiang Er 3+ Effective energy transfer to achieve Er 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 The regulation of population, through 2 H 11 / 2 and 4 S 3 / 2 Energy level to ground state 4 I 15 / 2 The quantitative relationship between the ratio of the two green upconversion luminescence intensities produced by the energy level transition and the temperature has realized a method based on Dy 3+ ‑Er 3+ A new energy transfer ratio-type temperature measurement technology is proposed. This method not only has a low-cost and easy-to-obtain excitation light source, but also has a high temperature detection sensitivity.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature detection, and in particular relates to a ratiometric temperature detection method based on rare earth Dy-Er energy transfer. Background Art

[0002] Temperature is a very important thermodynamic state parameter in the fields of physics, chemistry, biology and engineering technology. It is extremely important to accurately control and measure the temperature with fast response, high sensitivity and high spatial resolution. Compared with traditional contact temperature measurement technologies such as thermocouples and resistance thermometers, non-contact temperature measurement technology can achieve high sensitivity and high spatial resolution real-time temperature measurement of biological cells, biochemical processes, micro-nanoelectronic devices or fast-moving systems. Among the many non-contact temperature detection technologies, the fluorescence temperature detection technology based on the temperature response characteristics of optical parameters has attracted widespread attention due to its strong anti-interference ability, high sensitivity and spatial resolution and rapid response. In particular, the fluorescence intensity ratio temperature measurement scheme based on the thermal coupling energy level of rare earth ions can eliminate the interference of non-temperature factors such as fluorescence loss, excitation light source power fluctuations and the number of luminescence centers during the measurement process, and has the advantages of self-calibration characteristics of fluorescence temperature detection. Many rare earth ions have thermal coupling energy levels and can be used in fluorescence intensity ratio temperature measurement technology. Among them, the most studied and applied is the rare earth Er. 3+ ions, whose thermally coupled energy levels 2 H 11 / 2 and 4 S 3 / 2 The energy level difference is about 750cm -1 , can produce green and infrared light emissions under ultraviolet, visible and infrared light excitation.

[0003] Based on rare earth Er 3+ The method of temperature detection by ion luminescence mainly uses the Er 3+ Two thermally coupled energy levels 2 H 11 / 2 and 4 S 3 / 2 Ground state 4 I 15 / 2 The quantitative relationship between the ratio of the two green light emission intensities (respectively denoted as G1 and G2) emitted by the transition with a central wavelength of about 525 / 550nm and temperature. 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 The number of particles satisfies the Boltzmann distribution, so 2 H 11 / 2 and 4 S 3 / 2 To the ground state4 I 15 / 2 The intensity ratio R (= G1 / G2) of the two green lights produced by the energy level transition can be expressed as:

[0004]

[0005] Where ΔE is the thermal coupling energy level 2 H 11 / 2 and 4 S 3 / 2 The energy difference of the temperature sensor is k, the Boltzmann constant, T is the absolute temperature, and C is a constant related to the emission frequency, energy level degeneracy, and emission frequency. The absolute temperature sensing sensitivity S of the temperature sensor a and relative temperature sensing sensitivity S r Can be expressed as:

[0006]

[0007] A large number of studies have reported on the rare earth Er-based 3+ The temperature sensing characteristics of the ratio of two green light intensities, such as in Er 3+ Fluoride-doped glass [1,2] , oxide ceramics [3] and fluoride phosphors [4] Er was observed in 3+ The quantitative relationship between the intensity ratio of the two green lights and the temperature is discussed. 3+ Temperature sensing behavior of ion G1 / G2 intensity ratio. 3+ Different matrix materials have different crystal field environments, which will affect Er 3+ Thermally coupled energy level pairs 2 H 11 / 2 and 4 S 3 / 2 The energy level difference causes Er 3+ Different matrix materials have different temperature sensing properties.

[0008] According to the different wavelengths of the excitation light source, Er 3+ The two green light generation mechanisms can be divided into down-conversion luminescence and up-conversion luminescence. Under the excitation of short-wavelength light sources such as ultraviolet and blue light, Er 3+ It can be directly excited from the ground state energy level to a high energy level, and then relax from the high energy level to a low thermal coupling energy level without radiation. 2 H 11 / 2 and 4 S 3 / 2 , then through 2 H 11 / 2 and 4 S 3 / 2 To the ground state 4 I 15 / 2The radiative transition of the energy level produces two green down-conversion luminescence. 3+ Can be 379nm [5] and 406nm [1] UV light and 488nm [6] Blue light excitation based on Er 3+ Temperature sensing characteristics of ion G1 / G2 intensity ratio. 3+ It can also be excited by 532nm green light to achieve thermal coupling energy level 2 H 11 / 2 and 4 S 3 / 2 The distribution of 4 I 13 / 2 The central wavelength of the radiation transition is around 800 / 850nm, and the two infrared down-conversion luminescence intensity ratios are used to detect temperature. [7] In addition, under the excitation of long-wavelength light sources such as infrared lasers, Er 3+ Ability to achieve thermally coupled energy levels through ground state absorption and excited state absorption 2 H 11 / 2 and 4 S 3 / 2 The population of 4 I 15 / 2 Energy level radiative transition produces two green upconversion luminescence. For example, at 800nm [2] 、980nm [3] and 1540nm [4] Under infrared laser excitation, Er 3+ Two green up-conversion luminescences with central wavelengths of about 525 / 550nm are emitted, and temperature sensing based on the intensity ratio of the two green up-conversion luminescences is realized.

[0009] In order to improve Er 3+ The luminous efficiency of Er 3+ Temperature sensing characteristics of the two green light intensity ratios, for Er 3+ Energy transfer is a very effective means. For example, co-doping with other ions such as rare earth ions Yb 3+[8] Or transition metal ions Mo 6+[9] etc., or use a suitable matrix material such as ZnO

[10] etc., can be right 3+ Energy transfer to regulate thermal coupling energy levels 2 H 11 / 2 and 4 S 3 / 2 The population of 3+ Temperature sensing behavior of the ratio of two green upconverted luminescence intensities.

[0010] From formulas (2) and (3), we can see that the absolute temperature sensing sensitivity S based on fluorescence intensity ratio temperature measurement technology is a and relative temperature sensing sensitivity S r It is related to the energy level difference ΔE between the two thermal coupling energy levels of the rare earth ion used. The larger the ΔE, the greater the absolute sensitivity S a The larger the relative sensitivity S r The smaller the ΔE, the smaller the relative sensitivity S r The larger the absolute sensitivity S a Therefore, the absolute temperature sensor sensitivity S a and relative temperature sensing sensitivity S r Often it is impossible to take both into account. 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 The energy level difference ΔE between them is about 750 cm -1 , Er 3+ Different effects of doping matrix materials on Er 3+ The limited change of the crystal field environment leads to the 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 The energy level difference ΔE does not change much, so based on Er 3+ The temperature sensing sensitivity of the two green light intensity ratios has not been significantly improved, and the existing reported absolute temperature sensing sensitivity S a The maximum value does not exceed 0.01K -1 At present, Er is transferred through energy 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 Although the temperature sensing properties of the two green light intensity ratios can be improved by regulating the population of 3+ In doped ZnO phosphors, the defect levels of the ZnO matrix can 3+ Thermal coupling level 2 H 11 / 2 The energy transfer causes the population change, based on Er 3+ Absolute sensitivity S of temperature sensing of the ratio of two green light intensities of doped ZnO phosphor a The maximum value can reach 0.024K at 493K -1 Although this is the only reported 3+ The green light intensity ratio temperature measurement technology has the highest absolute sensitivity, but there is still room for further improvement in sensitivity.

[0011] In addition, the existing reports of Er 3+ There are two mechanisms for the generation of green light, Er 3+ The 800, 980 or 1530nm excitation light sources required for green upconversion luminescence are all lasers. Lasers are not only expensive, but also have a high excitation intensity that can cause severe heating effects, limiting the accuracy of temperature detection. 3+ The green down-conversion luminescence mechanism, the currently reported 379, 406, 488 and 532nm excitation light sources are all short-wavelength excitation light, and some excitation light even needs to be laser, which makes the cost of these short-wavelength light sources relatively high. Summary of the invention

[0012] In order to overcome the previous rare earth Er 3+ In order to solve the problems of high excitation light source cost and low temperature measurement sensitivity in the two green light intensity ratio temperature measurement technologies, the present invention provides a ratio temperature detection method based on rare earth Dy-Er energy transfer, which uses Dy under 734nm light excitation to detect the temperature of the sample. 3+ Xiang Er 3+ Effective energy transfer to achieve Er 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 The regulation of population, through 2 H 11 / 2 and 4 S 3 / 2 Energy level to ground state 4 I 15 / 2 The quantitative relationship between the ratio of the two green upconversion luminescence intensities produced by the energy level transition and the temperature has realized a method based on Dy 3+ -Er 3+ A new energy transfer ratio-type temperature measurement technology is proposed. This method not only has a low-cost and easy-to-obtain excitation light source, but also has a high temperature detection sensitivity.

[0013] The above object of the present invention is achieved through the following technical solution: a ratiometric temperature detection method based on rare earth Dy-Er energy transfer, the steps comprising:

[0014] S1.Measure Dy at a certain temperature 3+ -Er 3+ Co-doped CaWO 4 The up-conversion luminescence intensity G1 and G2 of the phosphor in the two green light bands of 500-525nm and 525-560nm, where the excitation light wavelength is λ ex =734nm, Dy 3+ and Er 3+ The molar concentration ratio is 1:2;

[0015] S2. Calculate the ratio of the two green up-conversion luminescence G1 and G2 at a certain temperature in step S1, ie, R = G1 / G2;

[0016] S3. Change Dy 3+ -Er 3+ Co-doped CaWO 4 The temperature of the phosphor is repeated in steps S1 and S2 to obtain a relationship curve between the luminous intensity ratio R=G1 / G2 and the temperature T;

[0017] S4. Using formula The curve obtained in step S3 is fitted to obtain the 3+ -Er 3+ Co-doped CaWO 4 The quantitative relationship between the ratio of the two green upconversion luminescence intensities of the phosphor and the temperature. 3+ of 2 H 11 / 2 and 4 S 3 / 2能级 To the ground state 4 I 15 / 2 The ratio of the two green light intensities produced by the energy level transition, ΔE is the thermal coupling energy level 2 H 11 / 2 and 4 S 3 / 2 energy difference, k is the Boltzmann constant, T is the absolute temperature, and C is a constant related to the emission light frequency, energy level degeneracy and luminescence frequency, where ΔE and C can be obtained by curve fitting.

[0018] The present invention is based on Dy 3+ -Er 3+ Co-doped CaWO 4 The green up-conversion luminescence intensity of the phosphor achieves high temperature sensing sensitivity. The characteristics of the temperature measurement technology are as follows:

[0019] a. The present invention uses rare earth Dy 3+ and Er 3+ Co-doping to achieve Dy 3+ Xiang Er 3+ The effective energy transfer of Er 3 + Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 of the Buju;

[0020] b. Dy in the present invention 3+ -Er 3+ Co-doped CaWO 4 The excitation wavelength of the phosphor is 734nm, and this wavelength of excitation light can be obtained by splitting an ordinary low-power xenon lamp;

[0021] c. Dy in the present invention 3+ -Er 3+ Co-doped CaWO 4 Dy of phosphor 3+ and Er 3+ The molar concentration ratio is 1:2;

[0022] d. The ratiometric fluorescence temperature measurement technology of the present invention is based on the rare earth Er 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 To the ground state 4 I 15 / 2 The intensity ratio of the two green upconversion luminescences generated by the energy level transition R = G1 / G2 shows a specific quantitative relationship with the temperature T.

[0023] e. The present invention is based on Dy 3+ -Er 3+ Energy transfer ratio temperature measurement technology has high absolute and relative sensitivity of temperature detection.

[0024] Compared with the prior art, the present invention has the following beneficial effects: by co-doping rare earth Dy 3+ ions, using Dy 3+ ion 4 F 9 / 2 Energy Levels and Er 3+ ion 4 F 7 / 2 Energy level matching to achieve Dy 3+ Xiang Er 3+ Effective energy transfer and regulation of Er 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 The population of 3+ Temperature sensing absolute sensitivity S of the two green light intensity ratios a Maximum up to 0.043K -1 Therefore, the present invention is based on rare earth Dy 3+ -Er 3+ The energy transfer method can effectively improve the temperature sensing characteristics; the present invention uses 734nm infrared light as the excitation light source, which not only has a weak heating effect of the light source, but also only requires an ordinary low-power xenon lamp to obtain the wavelength light source, so the present invention also has the characteristics of low cost and easy availability of the excitation light source; the rare earth Dy 3+ and Er 3+ Dy in co-doped luminescent materials 3+ and Er 3+The molar concentration ratio is 1:2, achieving Dy 3+ Xiang Er 3+ Optimal energy transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] Figure 1 For different 3+ -Er 3+ Concentration ratio of Dy 3+ -Er 3+ Co-doped CaWO 4 Room temperature photoluminescence spectrum of phosphor (excitation wavelength λ ex =352nm) (Fig. a), and an enlarged view in the wavelength range of 510-570nm (Fig. b);

[0027] Figure 2 For different 3+ -Er 3+ Concentration ratio of Dy 3+ -Er 3+ Co-doped CaWO 4 Excitation spectrum of phosphor (monitoring wavelength λ em =575nm);

[0028] Figure 3 For different 3+ -Er 3+ Concentration ratio of Dy 3+ -Er 3+ Co-doped CaWO 4 Room temperature photoluminescence spectrum of phosphor (excitation wavelength λ ex =734nm);

[0029] Figure 4 Dy at different excitation wavelengths 3+ -Er 3+ Co-doped CaWO 4 Room temperature photoluminescence spectrum of the phosphor (Dy-Er concentration ratio is 1:2);

[0030] Figure 5 Dy in the embodiment of the present invention 3+ -Er 3+ Co-doped CaWO 4 Phosphor(Dy 3+ -Er 3+ The photoluminescence spectra of the samples (excitation wavelength λ) at different temperatures (concentration ratio 1:2) ex =734nm)(Fig. a), Er 3+Two green upconversion luminescence intensities (G1 and G2) versus temperature (Fig. b), Er 3+ The ratio of the two green upconversion luminescence intensities (G1 / G2) varies with temperature (Figure c), as well as the absolute and relative sensitivity of temperature (Figure d);

[0031] Figure 6 Dy of Comparative Example 1 of the present invention 3+ -Er 3+ Co-doped CaWO 4 Phosphor(Dy 3+ -Er 3+ The photoluminescence spectra of the samples (excitation wavelength λ) at different temperatures (concentration ratio 1:2) ex =352nm);

[0032] Figure 7 Dy of Comparative Example 2 of the present invention 3+ -Er 3+ Co-doped CaWO 4 Phosphor(Dy 3+ -Er 3+ The photoluminescence spectra of the samples (excitation wavelength λ) at different temperatures (concentration ratio 1:2) ex =980nm) (Figure a), Er 3+ Two green upconversion luminescence intensities (G1 and G2) versus temperature (Fig. b), Er 3+ The ratio of the two green upconversion luminescence intensities (G1 / G2) varies with temperature (Figure c), as well as the absolute and relative sensitivity of temperature (Figure d);

[0033] Figure 8 Dy of Comparative Example 3 of the present invention 3+ -Er 3+ Co-doped CaWO 4 Phosphor(Dy 3+ -Er 3+ The concentration ratio is 1:2, and the excitation wavelength is λ ex =352nm) in Dy 3+ Two blue luminous intensity (B1 and B2) variation with temperature (Figure a), Dy 3+ The two blue luminous intensity ratios (B1 / B2) are plotted against temperature (Fig. b), and the absolute and relative sensitivity to temperature (Fig. c);

[0034] Fig. 9 is Er of Comparative Example 4 of the present invention 3+ Doped CaWO 4 Photoluminescence spectra of phosphors at different temperatures (excitation wavelength λ ex =980nm) (Figure a), Er3+ The variation curves of two green upconversion luminescence intensities (G1 and G2) with temperature (Fig. b), Er 3+ The variation curve of the ratio of the two green upconversion luminescence intensities (G1 / G2) with temperature (Figure c), as well as the absolute and relative sensitivity curves of temperature (Figure d). DETAILED DESCRIPTION

[0035] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0036] Example 1

[0037] The Dy in this patent application 3+ -Er 3+ Co-doped CaWO 4 The phosphor was prepared by coprecipitation method, and the raw materials used were Na 2 WO 4 ·2H 2 O(4N), CaCl 2 ·2H 2 O(4N), Dy 2 O 3 (5N) and Er 2 O 3 (5N). First, Na 2 WO 4 ·2H 2 O and CaCl 2 ·H 2 O powder was dissolved in deionized water to prepare 0.5 mol / L Na 2 WO 4 and CaCl 2 Aqueous solution, Dy 2 O 3 and Er 2 O 3 The powder was dissolved in excess nitric acid to prepare 0.01 mol / L Dy(NO 3 ) 3 and Er(NO 3 ) 3 Then 2mL of Na 2 WO 4 Solution, 1.94 mL CaCl 2 Solution, 1mL Dy(NO 3 ) 3 solution and 2mL Er(NO 3 ) 3The solutions were mixed and stirred thoroughly, and the white precipitate obtained by the reaction was washed by centrifugation, dried, sintered at 1523K for 3h, and ground after cooling to obtain 1mol% Dy 3+ and 2 mol% Er 3+ Co-doped CaWO 4 Phosphor (1Dy2Er). Dy can be prepared by changing the amount of each reaction solution. 3+ / Er 3+ Dy with concentration ratios of 1:0, 1:1, 1:3, 1:4, 1:10 and 0:2 3+ -Er 3+ Co-doped CaWO 4 Phosphors (denoted as 1Dy0Er, 1Dy1Er, 1Dy3Er, 1Dy4Er, 1Dy10Er and 0Dy2Er). Dy 3+ -Er 3+ Co-doped CaWO 4 The excitation spectrum and emission spectrum of the phosphor are characterized, and the temperature of the phosphor in the variable temperature emission spectrum is measured and controlled using a DMU-450 heating stage.

[0038] from Figure 1 The Dy shown in a 3+ -Er 3+ Co-doped CaWO 4 The photoluminescence spectrum of the phosphor at room temperature shows that under the excitation of 352nm ultraviolet light, the undoped Er 3+ Dy 3+ Doped CaWO 4 The phosphor (1Dy0Er) emits strong blue and yellow light in the 440-500nm and 560-600nm bands, respectively, corresponding to Dy 3+ of 4 F 9 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 13 / 2 For co-doped Er 3+ Dy 3+ -Er 3+ Co-doped CaWO 4 Phosphor(1Dy2Er), Dy 3+ The luminescence peak position did not change significantly, but the luminescence intensity decreased. Figure 1 The enlarged luminescence spectrum of the 510-570 nm band shown in b shows that the undoped Er 3+ Dy 3+ Doped CaWO4 The phosphor (1Dy0Er) has a weak luminescence peak at the central wavelength of 540nm, corresponding to Dy 3+ of 4 I 15 / 2 → 6 H 13 / 2 Transition, when co-doped with Er 3+ After that, Dy at 540nm 3+ The luminescence peak of Er disappeared, and two groups of green luminescence peaks appeared in the two bands of 515-540nm and 540-560nm, corresponding to Er 3+ of 2 H 11 / 2 → 4 I 15 / 2 and 4 S 3 / 2 → 4 I 15 / 2 Transition, indicating that Dy 3+ -Er 3+ Co-doped CaWO 4 Dy exists in phosphors 3+ Xiang Er 3+ energy transfer.

[0039] from Figure 2 Dy 3+ -Er 3+ Co-doped CaWO 4 The excitation spectrum of the phosphor (1Dy2Er) shows that when the monitoring wavelength λ em When the yellow light emission peak is 575nm, multiple excitation peaks appear in the 600-850nm band, located at 654, 706, 734 and 778nm respectively. This shows that red light and near-infrared light can effectively excite Dy 3+ -Er 3+ Co-doped CaWO 4 The phosphor produces up-conversion luminescence.

[0040] from Figure 3 The different Dy 3+ -Er 3+ Concentration ratio of Dy 3+ -Er 3+ Co-doped CaWO 4 The luminescence spectrum of the phosphor shows that under the excitation of 734nm near-infrared light, Er 3+ The change of doping concentration does not change the emission band of the phosphor, but has a significant effect on its green light intensity. 3+ and Er 3+ The strongest Er 3+ Green upconversion luminescence. 3+and Er 3+ The concentration ratio of 1:2 has the best Dy 3+ Xiang Er 3+ energy transfer efficiency.

[0041] from Figure 4 Dy at excitation wavelengths of 654, 706, 734, and 778 nm as shown 3+ -Er 3+ Co-doped CaWO 4 The luminescence spectrum of the phosphor shows that the change of the excitation wavelength does not change the luminescence band of the phosphor, but it does change the luminescence band of the Er 3+ Green light intensity also has a significant effect, with the strongest Er at an excitation wavelength of 734 nm. 3+ Green upconversion luminescence. This indicates that the phosphor has the best Dy under 734nm light excitation. 3+ Xiang Er 3+ energy transfer efficiency.

[0042] Figure 5 The Dy 3+ -Er 3+ Co-doped CaWO 4 Optical temperature sensing properties of phosphor (1Dy2Er) under 734nm infrared light excitation. Figure 5 The up-conversion luminescence spectra of the phosphor shown in a at different temperatures show that with the increase of temperature, the luminescence peak position of the phosphor does not change significantly, but the luminescence intensity changes. 3+ The up-conversion luminescence intensity of blue and yellow in the two bands of 440-500nm and 560-600nm gradually decreases with the increase of temperature, while Er 3+ The two green upconversion luminescences in the 515-540nm and 540-560nm bands show different changing patterns. Figure 5 The Er shown in b 3+ The two green up-conversion luminescence intensity G1 and G1 change with temperature. It can be seen that as the temperature gradually increases, Er 3+ The two green up-conversion luminescence intensities G1 and G2 show opposite change trends. Figure 5 The relationship between the two green up-conversion luminescence intensity ratios (R = G1 / G2) and the temperature T is given in c, where the variation of R = G1 / G2 with temperature can be fitted by formula (1), and the fitting result is R = 171*exp(-1862.45 / T), indicating that the green up-conversion luminescence intensity ratio based on Er 3+ The intensity ratio of the two green upconversion luminescences exhibits excellent temperature sensing properties. Figure 5 d is the absolute temperature sensing sensitivity S based on the ratio of the two green upconversion luminescence intensities (G1 / G2) calculated according to formulas (2) and (3):a and relative temperature sensing sensitivity S r As can be seen from the figure, the absolute temperature sensor sensitivity S a It gradually increases with the increase of temperature and reaches a maximum value of 0.043K at 650K -1 . Relative temperature sensing sensitivity S r It decreases gradually with increasing temperature and reaches a maximum value of 0.021K at 300K. -1 .

[0043] Comparative Example 1

[0044] In order to compare the Dy 3+ -Er 3+ Co-doped CaWO 4 The ratiometric temperature sensing technology of phosphors uses light sources of other wavelengths to measure Dy 3+ -Er 3+ Co-doped CaWO 4 The phosphor is excited. 3+ The best excitation wavelength is 352nm ultraviolet light, so 352nm ultraviolet light is used to excite the phosphor and study its optical temperature sensing properties. Figure 6 The excitation wavelength λ is given by ex =Dy at 352nm 3+ -Er 3+ Co-doped CaWO 4 Photoluminescence spectra of phosphor (1Dy2Er) at different temperatures. As can be seen from the figure, with the increase of temperature, the luminescence peak position of phosphor does not change significantly. 3+ The blue and yellow upconversion luminescence intensities in the 440-500nm and 560-600nm bands gradually decrease with increasing temperature. 3+ The light, Er 3+ The green luminescence intensity is weak, and coupled with the temperature quenching effect, no obvious temperature-dependent change of Er is observed. 3+ Green light emission, so it is impossible to obtain Er-based 3+ The ratiometric temperature sensing characteristics of the two green light intensity ratios. 3+ -Er 3+ The new energy transfer ratio temperature measurement technology requires an excitation light wavelength that cannot be Dy 3+ The best excitation wavelength is 352nm ultraviolet light.

[0045] Comparative Example 2

[0046] In order to compare the Dy 3+ -Er 3+ Co-doped CaWO4 The ratiometric temperature sensing technology of phosphors uses light sources of other wavelengths to measure Dy 3+ -Er 3+ Co-doped CaWO 4 The phosphor is excited. 3+ The best excitation wavelength is 980nm infrared laser. 980nm laser is used to excite the phosphor and study its optical temperature sensing properties. Figure 7 The Dy 3+ -Er 3+ Co-doped CaWO 4 The temperature-dependent upconversion luminescence spectrum of the phosphor (1Dy2Er) shows that no Dy 3+ The luminescence of Er was only observed in the 510-580nm band. 3+ The green upconversion luminescence of the phosphor is shown in Figure 1. As the temperature increases, the luminescence peak of the phosphor does not change significantly, but the upconversion luminescence intensity changes. Figure 7 The Er shown in b 3+ From the temperature variation curves of the two green up-conversion luminescence intensities G1 and G2 in the 510-540nm and 540-580nm bands, it can be seen that the green up-conversion luminescence intensity G2 shows temperature quenching, while the other green up-conversion luminescence intensity G1 shows a trend of first increasing and then decreasing with increasing temperature. Figure 7 The relationship between the two green up-conversion luminescence intensity ratios (G1 / G2) and the temperature T is given in c, where the variation of R=G1 / G2 with temperature can be fitted by formula (1), and the fitting result is R=14.37*exp(-935.28 / T), indicating that under the excitation of 980nm infrared laser, Dy 3+ -Er 3+ Co-doped CaWO 4 Phosphor based on Er 3+ The intensity ratio of the two green lights also exhibits excellent temperature sensing properties. Figure 7 d is the absolute sensitivity S of the temperature sensor calculated according to formulas (2) and (3) a and relative sensitivity S r Curve. It can be seen from the figure that the absolute temperature sensor sensitivity S a As the temperature increases, it first increases and then decreases, reaching a maximum value of 0.0083K ​​at 468K -1 . Relative temperature sensing sensitivity S r It gradually decreases with increasing temperature and reaches a maximum value of 0.0104K at 300K. -1 .

[0047] By comparing the embodiment and comparative example 2, it can be seen that the maximum absolute sensitivity of the temperature measurement technology using 734nm light excitation in the embodiment of the present invention is increased by 6 times, and the maximum relative sensitivity is also increased by 2 times. 3+ -Er 3+ Co-doped CaWO 4 The new ratiometric temperature measurement technology for phosphors has higher temperature detection sensitivity than traditional 980nm light excitation.

[0048] Comparative Example 3

[0049] In order to compare the Dy 3+ -Er 3+ Co-doped CaWO 4 Phosphor based on Er 3+ Thermal coupling level 2 H 11 / 2 and 4 S 3 / 2 Ground state 4 I 15 / 2 The temperature sensing technology of the ratio of the two green luminescence intensities of energy level transition is based on the Dy 3+ Thermal coupling level 4 I 15 / 2 and 4 F 9 / 2 Ground state 6 H 15 / 2 The temperature sensing behavior of the two blue luminescence intensity ratios of the energy level transition is compared. 3+ -Er 3+ Co-doped CaWO 4 The up-conversion luminescence spectrum of the phosphor (1Dy2Er) is shown in Figure 5 a, from Figure 8 The spectrum of Dy shown in a 3+ From the temperature variation curves of the two blue up-conversion luminescence intensities B1 and B2 in the 440-466nm and 466-500nm bands, it can be seen that the blue up-conversion luminescence intensity B2 exhibits temperature quenching, while the other blue up-conversion luminescence intensity B1 exhibits reverse temperature quenching. Figure 8 The relationship between the two blue up-conversion luminescence intensity ratios (B1 / B2) and the temperature T is shown in Fig. 2, where the change of R=B1 / B2 with temperature can also be fitted by formula (1), and the fitting result is R=2.186*exp(-1237.355 / T), indicating that under the excitation of 734nm infrared light, Dy 3+ -Er 3+ Co-doped CaWO 4 Phosphor based on Dy 3+The fluorescence intensity ratio also shows excellent temperature sensing properties. Figure 8 c is the absolute sensitivity S of the temperature sensor calculated according to formulas (2) and (3) a and relative sensitivity S r Curve. It can be seen from the figure that the absolute temperature sensor sensitivity S a As the temperature increases, it first increases and then decreases, reaching a maximum value of 0.00096K at 619K -1 . Relative temperature sensing sensitivity S r It gradually decreases with increasing temperature and reaches a maximum value of 0.0137K at 300K. -1 .

[0050] Comparative Example 3 shows that the embodiment of the present invention is based on Er 3+ The maximum absolute sensitivity of the temperature measurement technology of the ratio of two green luminous intensity is increased by about 45 times, and the maximum relative sensitivity is also increased by about 2 times. 3+ -Er 3+ Co-doped CaWO 4 Er-based phosphors 3+ The temperature measurement technology based on the ratio of two green light intensities is different from that based on Dy 3+ The temperature measurement technology of two blue light intensity ratios has higher temperature detection sensitivity.

[0051] Comparative Example 4

[0052] In order to compare the Dy 3+ -Er 3+ Co-doped CaWO 4 Dy-based phosphors 3+ -Er 3+ The ratiometric temperature measurement technique of energy transfer was used to prepare undoped Dy 3+ Er 3+ Doped CaWO 4 Phosphor (0Dy2Er), in the absence of Dy 3+ -Er 3+ Energy transfer case study on Er 3+ Temperature sensing characteristics of two green light intensity contrasts. 3+ The best excitation wavelength is 980nm infrared laser, so this comparative example uses 980nm laser as the excitation light source. Fig. 9 The Er is excited by 980nm laser. 3+ Doped CaWO 4 The temperature-dependent up-conversion luminescence spectrum of the phosphor (0Dy2Er) shows that Er 3+Two green upconversion luminescences were obtained in the 510-540nm and 540-580nm bands, and as the temperature increased, the green luminescence peak position did not change significantly, but the luminescence intensity did change. Fig. 9 From the temperature variation curves of the two green up-conversion luminescence intensities G1 and G2 shown in b, it can be seen that the green up-conversion luminescence intensity G2 shows a temperature quenching phenomenon, while the other green up-conversion luminescence intensity G1 shows a trend of first increasing, then decreasing, and then increasing as the temperature rises. Fig. 9 The relationship between the green upconversion luminescence intensity ratio (G1 / G2) and the temperature T is given in c, where the change of R = G1 / G2 with temperature can be fitted by formula (1), and the fitting result is R = 21.59*exp(-1080.54 / T), indicating that under the excitation of 980nm infrared laser, Er 3+ Doped CaWO 4 Er of phosphor 3+ The two green light intensity ratios also exhibit excellent temperature sensing properties. Fig. 9 d is the absolute sensitivity S of the temperature sensor calculated according to formulas (2) and (3) a and relative sensitivity S r As can be seen from the figure, the absolute temperature sensor sensitivity S a As the temperature increases, it first increases and then decreases, reaching a maximum value of 0.0108K at 540K -1 . Relative temperature sensing sensitivity S r It decreases gradually with increasing temperature and reaches a maximum value of 0.012K at 300K. -1 .

[0053] Compared with the undoped Dy 3+ Dy does not exist 3+ -Er 3+ Energy transfer, co-doped Dy in the embodiment of the present invention 3+ With Dy 3+ -Er 3+ In the case of energy transfer, based on Er 3+ The maximum absolute sensitivity of the temperature measurement technology of the ratio of two green luminous intensity is increased by 4 times, and the maximum relative sensitivity is also increased by 2 times. 3+ -Er 3+ Co-doped CaWO 4 Dy-based phosphors 3+ -Er 3+ The ratiometric temperature measurement technology with energy transfer has higher temperature detection sensitivity than the temperature measurement technology without energy transfer.

[0054] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

[0055] References:

[0056] [1]P. Haro-González, SF León-Luis, S. González-Pérez, IR Martín, Analysis of Er 3+ and Ho 3+ Codoped Fluoroindate Glasses as Wide Range Temperature Sensor,Mater.Res.Bull.,46(2011)1051-1054.

[0057] [2]SF León-Luis,URRodríguez-Mendoza,E.Lalla,V.Lavín,Temperaturesensor based on the Er 3+ green upconverted emission in a fluorotellurite glass,Sensors and ActuatorsB:Chemical,158(2011)208-213.

[0058] [3]P.Du,LHLuo,WPLi,QYYue,HBChen,Optical temperature sensorbased on upconversion emission in Er-doped ferroelectric0.5Ba(Zr 0.2 Ti 0.8 ) 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 ceramic,Appl.Phys.Lett.,104(2014)4.

[0059] [4]XFWang,CSLiu,XHYan,Optical temperature sensing of hexagonalNa 0.82 Ca0.08 Er 0.16 Y 0.853 F 4 phosphor,RSCAdvances,4(2014)24170-24175.

[0060] [5]G.Z.Sui,X.P.Li,L.H.Cheng,J.S.Zhang,J.S.Sun,H.Y.Zhong,Y.Tian,S.B.Fu,B.J.Chen,Laser Cooling with Optical Temperature Sensing in Er 3+ -DopedTellurite-Germanate Glasses,Appl.Phys.B-Lasers Opt.,110(2013)471-476.

[0061] [6]S.F.León-Luis,U.R.Rodríguez-Mendoza,P.Haro-González,I.R.Martín,V.Lavín,Role of the host matrix on the thermal sensitivity of Er 3+ luminescencein optical temperature sensors,Sensors and Actuators B:Chemical,174(2012)176-186.

[0062] [7]P.Haro-González,I.R.Martín,L.L.Martín,S.F.León-Luis,C.Pérez-Rodríguez,V.Lavín,Characterization of Er 3+ and Nd 3+ doped Strontium Barium Niobateglass ceramic as temperature sensors,OpticalMaterials,33(2011)742-745.

[0063] [8]B.Dong,D.P.Liu,X.J.Wang,T.Yang,S.M.Miao,C.R.Li,Optical thermometrythrough infrared excited green upconversion emissions in Er 3+ -Yb 3+ codopedAl 2 O 3 ,Appl.Phys.Lett.,90(2007)3.

[0064] [9]B.S.Cao,Y.Y.He,Z.Q.Feng,Y.S.Li,B.Dong,Optical Temperature SensingBehavior of Enhanced Green Upconversion Emissions from Er-Mo:Yb 2 Ti 2 O 7 Nanophosphor,Sensors andActuators B:Chemical,159(2011)8-11.

[0065]

[10] S.Senapati,K.Kar Nanda,Ultrahigh-sensitive optical temperaturesensing based on quasi-thermalized green emissions from Er:ZnO,Physicalchemistry chemicalphysics,19(2017)2346-2352.

Claims

1. A ratiometric temperature detection method based on rare earth Dy-Er energy transfer, characterized in that the steps include: S1.Measure Dy at a certain temperature 3+ -Er 3+ The up-conversion luminescence intensity G1 and G2 of the co-doped CaWO4 phosphor in the two green light bands of 500-525nm and 525-560nm, where the excitation light wavelength is λ ex =734nm, Dy 3+ and Er 3+ The molar concentration ratio is 1:2; S2. Calculate the ratio of the up-conversion luminous intensity G1 and G2 of the two green light bands at a certain temperature in step S1, that is, R = G1 / G2; S3. Change Dy 3+ -Er 3+ The temperature of the co-doped CaWO4 phosphor is repeated, steps S1 and S2 are repeated to obtain a relationship curve between the luminous intensity ratio R=G1 / G2 and the temperature T; S4. Using formula The curve obtained in step S3 is fitted to obtain the 3+ -Er 3+ Quantitative relationship between the ratio of the two green upconversion luminescence intensities of co-doped CaWO4 phosphors and temperature; where R is Er 3+ of 2 H 11 / 2 and 4 S 3 / 2 Energy level to ground state 4 I 15 / 2 The ratio of the two green light intensities produced by the energy level transition, ΔE is the thermal coupling energy level 2 H 11 / 2 and 4 S 3 / 2 energy difference, k is the Boltzmann constant, T is the absolute temperature, and C is a constant related to the emission frequency, energy level degeneracy and luminescence frequency.

Images