A temperature sensing method based on the ratio of excitation and emission

Abstract

The present application belongs to the technical field of temperature detection, and discloses a ratio type temperature sensing method based on excitation and emission. 3+ The present application realizes synchronous acquisition of visible light emission and excitation light 1.5 times frequency peak of Dy 3+ in the doped CaWO4 fluorescent powder without adding optical filters in the spectral test, realizes the 1.5 times frequency peak of Dy in the doped CaWO4 fluorescent powder without adding optical filters in the spectral test, realizes the 1.5 times frequency peak of Dy The present application not only has high temperature detection sensitivity, but also has simple and convenient test process, high measurement accuracy, low cost and easy acquisition of the adopted 778nm excitation light source.

Description

Technical Field

[0001] This invention belongs to the field of temperature detection technology, specifically relating to a ratiometric temperature sensing method based on excitation and emission. Background Technology

[0002] Temperature is a key parameter that determines chemical reactions, biological functions, and various physical phenomena. Compared to contact temperature measurement techniques, measuring local temperatures on a small scale, such as temperature changes in microcircuits and intracellular fluids, as well as measuring the temperature of inaccessible objects such as high-voltage power plants, coal mines, volcanoes, and corrosive environments, requires new temperature sensing methods based on remote, non-contact detection principles.

[0003] Existing reports are based on Dy 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 Ratio-type temperature sensing technology based on transitions originates from two thermally coupled energy levels transitioning to the ground state energy level. 6 H 15 / 2 The intensity ratio of the two blue lights emitted during the transition changes only to a limited extent with temperature, resulting in a small constant C and thus a low absolute sensitivity S. a The temperature is usually not high, so there is an urgent need to develop a ratiometric optical temperature sensor based on new technical principles.

[0004] In the process of fluorescence testing, in order to eliminate the influence of the excitation frequency-doubled light generated by the frequency doubling effect on the emission spectrum of the sample, an optical filter is generally added between the excitation end, i.e., the excitation light and the test sample. The purpose is to allow only the excitation light to pass through while filtering out the excitation frequency-doubled light. Therefore, it is necessary to select a filter of appropriate specifications according to the wavelength of the excitation light used and the fluorescence test band.

[0005] Due to Dy 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 The energy level difference ΔE is small, which will cause Dy 3+ The two blue light emission bands overlap, resulting in the Dy-based 3+ In the blue light intensity ratio temperature measurement technology, it is difficult to accurately measure the luminous intensities B1 and B2 of the two blue lights, resulting in a large error in the luminous intensity ratio R = B1 / B2, which affects the accuracy of temperature sensing.

[0006] In addition, existing reports of Dy 3+ Excitation light is usually ultraviolet light. However, ultraviolet light, as a short-wavelength excitation light, is difficult to achieve Dy 3+ Effective stimulation. Summary of the Invention

[0007] In order to overcome the previous rare earth-based Dy 3+ To address the shortcomings of traditional blue light intensity ratio (BRI) temperature sensing techniques, such as low sensitivity, complex operation, low measurement accuracy, and high cost of excitation sources, this invention provides a ratiometric temperature sensing method based on excitation and emission, which uses 778nm light to excite Dy without the need for filters. 3+ Doping with CaWO4 phosphor yields Dy 3+ Thermally Coupled Energy Level 4 I 15 / 2 / 4 F 9 / 2 To the ground state 6 H 15 / 2 and metastable state 6 H 13 / 2 The emission of blue and yellow visible light from energy level transitions, as well as 1.5 harmonic light originating from the excitation light, is transmitted through Dy 3+ The quantitative relationship between the ratio of visible light intensity to excitation frequency-doubled light intensity and temperature was established, realizing a rare-earth-based Dy 3+ A novel ratiometric temperature detection method using doped luminescent materials is proposed. This method not only boasts high temperature sensing sensitivity but also high measurement accuracy, simple operation, and readily available excitation light source.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution: a ratiometric temperature sensing method based on excitation and emission, the specific steps of which are as follows:

[0009] S1. Measure Dy at a certain temperature without using a filter. 3+ The emission spectrum of CaWO4-doped phosphor in the 425–625 nm wavelength range, where the excitation wavelength is λ. ex =778nm;

[0010] S2. Calculate Dy in the 425–625 nm wavelength range at the temperature described in S1. 3+ Thermally Coupled Energy Level 4 I 15 / 2 / 4 F 9 / 2 To the ground state 6 H 15 / 2 and metastable state 6 H 13 / 2 The ratio of the sum of the intensities of the two blue and two yellow light rays during the energy level transition (B1+B2+Y1+Y2) to the intensity of the 1.5 harmonic excitation peak (EX) with a center wavelength of 518.7nm is R=(B1+B2+Y1+Y2) / EX;

[0011] S3. Change Dy 3+ By repeating steps S1 and S2 at the temperature of doped CaWO4 phosphor, the relationship curve between intensity ratio R = (B1 + B2 + Y1 + Y2) / EX and temperature T is obtained.

[0012] S4. Use empirical formulas Fit the curve obtained in step S3 to obtain the curve based on Dy. 3+ Dy doped CaWO4 phosphor 3+ The quantitative relationship between the ratio of light emission intensity to excitation light intensity and temperature.

[0013] The advantages of this invention compared to existing technologies are: this invention eliminates the need for filters during spectral testing, achieving Dy 3+ Dy doped CaWO4 phosphor 3+ The simultaneous acquisition of visible light emission and the 1.5 harmonic peak of excitation light; in this invention, Dy 3+ The excitation wavelength of the CaWO4-doped phosphor is near-infrared light at 778 nm. Not only is the excitation source readily available, but the center wavelength of the 1.5 harmonic peak of the excitation light is located at 518.7 nm, which is similar to that of Dy. 3+ The fluorescence emission peaks do not overlap; the ratiometric fluorescence thermometry of this invention is based on Dy 3+ Thermally Coupled Energy Level 4 I 15 / 2 / 4 F 9 / 2 To the ground state 6 H 15 / 2 and metastable state 6 H 13 / 2 The ratio of the intensities of the two blue and two yellow emitted light from the energy level transition (B1+B2+Y1+Y2) to the intensity of the 1.5th harmonic peak (EX) of the excitation light with a center wavelength of 518.7 nm exhibits a specific quantitative relationship with temperature T. The present invention provides a filterless Dy excitation at 778 nm. 3+ The CaWO4 phosphor-doped temperature sensing technology is based on the ratio of light emission intensity to excitation light intensity, which has high temperature detection sensitivity. In addition, the present invention not only has high temperature detection sensitivity, but also has a simple and convenient testing process, does not require the addition of filters, and has high measurement accuracy. The 778nm excitation light source used is low cost and readily available. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0015] Figure 1 For Dy 3+ Room temperature excitation spectrum of CaWO4-doped phosphor (monitoring wavelength λ) em =575nm)(Figure a), Dy at different excitation wavelengths with a filter 3+ Emission spectrum of CaWO4-doped phosphor (spectrum normalized at 575 nm) (Figure b), and Dy at different monitoring wavelengths.3+ Room temperature excitation spectrum of CaWO4 doped phosphor (Figure c);

[0016] Figure 2 Dy without filter 3+ Temperature-dependent photoluminescence spectrum of CaWO4-doped phosphor (excitation wavelength λ) ex =778nm)(Figure a), Dy 3+ The curves showing the changes in the luminous intensities of the two blue and two yellow light sources (B1, B2, Y1, and Y2) and the intensity of the excitation frequency-doubled light (EX) as a function of temperature (Figure b). 3+ The curves showing the variation of the ratio of luminous intensity to excitation frequency-doubled light intensity (R=(B1+B2+Y1+Y2) / EX) with temperature (Fig. c), and the corresponding absolute sensitivity curve of temperature sensing (Fig. d);

[0017] Figure 3 Dy for different excitation wavelengths 3+ A comparison of the photoluminescence spectra of CaWO4-doped phosphor with and without a filter (Figure a), and the Dy values ​​at different excitation wavelengths without a filter. 3+ Temperature-dependent emission spectra of CaWO4-doped phosphor (Figures bd);

[0018] Figure 4 When there is no filter, the excitation wavelength λ ex =778nm excitation Dy 3+ Dy doped CaWO4 phosphor 3+ The curves showing the changes in the ratios of light emission intensity and excitation frequency-doubled light intensity (B1 / EX, B2 / EX, (B1+B2) / EX and (Y1+Y2) / EX) with temperature (Fig. a), and the corresponding absolute sensitivity curves for temperature sensing (Fig. b).

[0019] Figure 5 When there is no filter, the excitation wavelength λ ex =778nm excitation Dy 3+ Dy doped CaWO4 phosphor 3+ The curves showing the change of the two blue light intensity ratios (R=B1 / B2) with temperature (Figure a), and the corresponding absolute sensitivity curve of the temperature sensor (Figure b);

[0020] Figure 6 When there is a filter, Dy 3+ Temperature-dependent emission spectrum of CaWO4-doped phosphor (excitation wavelength λ) ex =778nm)(Figure a), Dy 3+ The curves showing the change in the intensity of two blue light emission sources (B1 and B2) as a function of temperature (Figure b), Dy 3+The curves showing the change of the two blue light intensity ratios (R=B1 / B2) with temperature (Figure c), and the corresponding absolute sensitivity curve of the temperature sensor (Figure d); Detailed Implementation

[0021] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0022] Dy in this patent application 3+ CaWO4-doped phosphor was prepared by a co-precipitation method using Na₂WO₄·2H₂O (4N), CaCl₂·2H₂O (4N), and Dy₂O₃ (5N). First, Na₂WO₄·2H₂O and CaCl₂·H₂O powders were dissolved in deionized water to prepare 0.5 mol / L Na₂WO₄ and CaCl₂ solutions, respectively. Dy₂O₃ powder was dissolved in excess nitric acid to prepare a 0.01 mol / L Dy(NO₃)₃ solution. 2 mL of Na₂WO₄ solution, 1.94 mL of CaCl₂ solution, and 3 mL of Dy(NO₃)₃ solution were mixed and stirred thoroughly, resulting in a white precipitate. The reaction product was then centrifuged, washed, dried, and sintered at 1523 K for 3 h. After cooling, it was ground to obtain 3 mol% Dy₂O₃. 3+ CaWO4 phosphor was used as a dopant. The Dy value was measured using a HITAHI F-4600 fluorescence spectrometer. 3+ The excitation and emission spectra of the CaWO4-doped phosphor were obtained, with the phosphor temperature controlled via a DMU-450 heating stage. The presence or absence of an overtone peak in the spectrum was controlled by placing or not placing a 455nm high-pass filter between the excitation end (xenon lamp exit slit) and the sample stage of the HITAHI F-4600 fluorescence spectrometer.

[0023] from Figure 1 Dy shown in a 3+ The excitation spectrum of the CaWO4-doped phosphor shows that when the monitoring wavelength λ... em Set in Dy 3+ When the yellow light emission peak is at 575 nm, four relatively strong excitation peaks with center wavelengths of 326, 352, 366, and 388 nm appear in the 300–425 nm band, and four relatively weak excitation peaks with center wavelengths of 654, 706, 734, and 778 nm appear in the 600–850 nm band. Figure 1 b gives the case where a 455nm high-pass filter is placed, Dy 3+The room-temperature emission spectrum of the CaWO4-doped phosphor shows that, under excitation at 352, 654, 706, 734, and 778 nm, strong blue and yellow emission peaks are observed at the center wavelengths of 485 and 575 nm, respectively, corresponding to Dy 3+ of 4 F 9 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 13 / 2 Transition. Furthermore, faint blue and yellow emission peaks appeared at the center wavelengths of 455 and 540 nm, respectively, corresponding to Dy... 3+ of 4 I 15 / 2 → 6 H 15 / 2 and 4 I 15 / 2 → 6 H 13 / 2 Transition. Furthermore, it can be observed that changes in the excitation light wavelength affect Dy. 3+ The blue and yellow light emission wavelengths are unaffected, and the intensity ratio of blue to yellow light is almost unaffected. From Figure 1 c shows Dy 3+ The room-temperature excitation spectra of the CaWO4-doped phosphor at different monitoring wavelengths show that, for Dy 3+ The four most prominent emission peaks (λ) em =455, 479, 488 and 575 nm), multiple identical excitation peaks appeared in the 600-850 nm excitation band, with center wavelengths at 654, 706, 734 and 778 nm, respectively, indicating that both red light and near-infrared light can effectively excite Dy. 3+ Doped with CaWO4 phosphor.

[0024] Example 1

[0025] Figure 2 The present invention provides a filterless Dy 3+ Optical temperature sensing characteristics of CaWO4-doped phosphor under 778 nm light excitation. Figure 2 As shown in Figure a, the temperature-varying spectrum of the phosphor without a filter reveals that, except for the observations at the center wavelengths of 455, 485, 540, and 575 nm corresponding to Dy... 3+The spectrum exhibits blue and yellow emission peaks, with an additional emission peak at the central wavelength of 518.7 nm, originating from the excitation light. During spectral testing, without a 455 nm high-pass filter, the 778 nm excitation light emitted from the xenon lamp after spectral dispersion, along with its 389 nm second-harmonic light, interact to produce 1.5 harmonic light (wavelength 518.7 nm). This 518.7 nm 1.5 harmonic light, due to reflection from the phosphor, enters the spectrometer's entrance along with the phosphor's emitted light and is collected by the detector, thus appearing in the measured spectrum. However, when a 455 nm high-pass filter is placed at the excitation end, the 389 nm second-harmonic excitation light is filtered out, therefore the 1.5 harmonic light with a wavelength of 518.7 nm (e.g., ...) will not appear. Figure 1 (As shown in b). With increasing phosphor temperature, the positions of the emission peaks did not change significantly, but their intensities changed accordingly. From... Figure 2 As shown in Figure b, the intensity curves of each emission peak as a function of temperature can be seen, corresponding to Dy 3+4 I 15 / 2 → 6 H 15 / 2 / 6 H 13 / 2 The intensity of the two emission peaks (B1 and Y1) at the center wavelengths of the transition, located at 455 and 540 nm, gradually increases with increasing temperature, while the intensity corresponding to Dy... 3+4 F 9 / 2 → 6 H 15 / 2 / 6 H 13 / 2 The intensity of the two emission peaks (B2 and Y2) with center wavelengths of 485 and 575 nm gradually decreases with increasing temperature, and the intensity of the excitation frequency doubling light (EX) with center wavelength of 518.7 nm also gradually decreases with increasing temperature. Figure 2 c gives Dy 3+ The graph shows the relationship between the ratio of the total visible light intensity (B1+B2+Y1+Y2) to the intensity of the excitation frequency-doubled light (EX) and temperature T. The change of the intensity ratio R with temperature T can be expressed by an empirical formula.

[0026]

[0027] A fitting was performed, where a, b, and c are fitting constants. The result of curve fitting according to formula (1) is R = -13.71*exp(-T / 1496.34) + 14.85, indicating that Dy 3+ The ratio of emission intensity to excitation intensity exhibits excellent temperature sensing characteristics. From formula (1), we can obtain the results of this invention based on Dy... 3+ The absolute sensitivity S of temperature sensing using a ratiometric temperature measurement method based on the ratio of emission intensity to excitation intensity. a for:

[0028]

[0029] Figure 2 d is the value calculated based on Dy according to formula (2). 3+ The absolute sensitivity of temperature sensing based on the ratio of emission intensity to excitation intensity (R = (B1 + B2 + Y1 + Y2) / EX) is S. a The curve, as shown in the figure, reveals the absolute sensitivity S. a The value gradually decreases as the temperature increases, reaching a maximum of 0.0075K at 300K. -1 .

[0030] Comparative Example 1

[0031] To compare the Dy excitation at 778nm without a filter in this invention 3+ In our ratiometric temperature sensing technology using CaWO4-doped phosphor, we employ excitation light of other wavelengths to measure Dy 3+ Excitation was performed using CaWO4-doped phosphor. Figure 1 For the excitation spectrum of c, we selected the other three strongest excitation wavelengths, namely λ. ex =654, 706 and 734nm. Figure 3 a gives the excitation wavelength λ ex =Dy at 654, 706, 734 and 778nm 3+ A comparison of the emission spectra of CaWO4-doped phosphors with and without filters. As shown in the figure, at the same excitation wavelength, the spectral intensity without a filter is stronger than that with a filter. Although the 455nm high-pass filter allows excitation light at 654, 706, 734, and 778nm to pass through, there is still approximately a 10% intensity attenuation. On the other hand, the second harmonics of the 654, 706, 734, and 778nm excitation light at 327, 353, 367, and 389nm are almost completely absorbed by the 455nm high-pass filter, and all four second harmonics can excite Dy. 3+ Light-emitting ( Figure 1 a) Therefore, under the same excitation conditions, the intensity of the excitation light incident on the phosphor is weaker with a filter than without, resulting in a weaker spectral intensity with a filter compared to without. Furthermore, besides the difference in spectral intensity, from... Figure 3 Furthermore, it can be observed that the spectrum without a filter has one more emission peak than the spectrum with a filter. For λ... ex When using four excitation wavelengths (654, ​​706, 734, and 778 nm) without a filter, additional emission peaks appeared at 436, 470, 490, and 518.7 nm, respectively. The emission peaks at 470 and 490 nm are related to Dy. 3+ The fluorescence peaks overlap. With Figure 2The reason for the 518.7 nm 1.5 harmonic excitation light in a is similar; the emission peaks at 436, 470, and 490 nm also originate from the 1.5 harmonic light produced by the combined action of their respective excitation lights and their second harmonic lights. From Figure 2 b-2d without filter λ ex Dy at three excitation wavelengths of 654, 706 and 734 nm 3+ The temperature-varying emission spectrum of the CaWO4-doped phosphor shows that, compared with... Figure 2 Similarly, as the temperature increases, the peak position of the spectrum does not change significantly, Dy 3+ The emission intensities of the two blue and two yellow light sources in the 440–500 nm and 560–600 nm wavelength bands show opposite trends with temperature, but the intensity change of the excitation light from the 1.5 harmonic light is different. Figure 2 a is different. When λ ex =654nm ( Figure 3 b) The intensity of the 1.5 harmonic light (wavelength at 436nm) hardly changes with temperature; when λ ex =706 and 734nm ( Figure 3 c and 3d), 1.5 harmonic light (wavelengths at 470 and 490 nm respectively) due to Dy 3+ The fluorescence emission peaks overlap, making it impossible to directly obtain the variation of light intensity with temperature.

[0032] Due to λ ex The excitation wavelengths of 654, 706, and 734 nm cannot be used to obtain the temperature variation of the 1.5 harmonic excitation light intensity, and therefore cannot be used to obtain Dy. 3+ The quantitative relationship between the ratio of emission intensity to excitation light intensity and temperature, and its ratiometric temperature sensing characteristics. Comparing Example 1 and Comparative Example 1, it can be seen that the rare-earth Dy... 3+ The ratiometric temperature sensing technology based on the excitation and emission of doped luminescent materials requires an excitation wavelength of 778 nm to achieve Dy 3+ The fluorescence emission peak and the 1.5 harmonic excitation peak do not overlap at all, thus enabling accurate calculation of Dy. 3+ The light emission intensity value and excitation intensity value enable the present invention to have higher measurement accuracy.

[0033] Comparative Example 2

[0034] To compare the Dy excitation at 778nm without a filter in this invention 3+ Doped CaWO4 phosphor based on Dy 3+ We also employed different strategies for analyzing temperature sensing characteristics using a ratio of the sum of visible light emission intensity (B1+B2+Y1+Y2) to the intensity of excitation frequency-doubled light (EX). Figure 4 a is based on Figure 2 b. Data calculations without a filter at the excitation wavelength λ ex =778nm Dy 3+ Dy doped CaWO4 phosphor 3+ Curves showing the variation of the ratio of luminous intensity to excitation frequency-doubled light intensity (R=B1 / EX, R=B2 / EX, R=(B1+B2) / EX and R=(Y1+Y2) / EX) with temperature. As can be seen from the figure, the change of intensity ratio R with temperature T can be fitted by the empirical formula (1). The fitting results are R=B1 / EX=0.022*exp(T / 235.06)-0.06, R=B2 / EX=-1.33*exp(-T / 292.37)+1.37, R=(B1+B2) / EX=96.58*exp(T / 57732.30)-96.16 and R=(Y1+Y2) / EX=-8.48*exp(-T / 1110.79)+9.18, indicating that the four emission and excitation intensity ratio strategies R=B1 / EX, R=B2 / EX, R=(B1+B2) / EX and R=(Y1+Y2) / EX also exhibit excellent temperature sensing characteristics. Figure 4 b is the absolute sensitivity S of the temperature sensor calculated according to formula (2). a The curve shows that the ratio strategy R = (Y1 + Y2) / EX has the best sensitivity, reaching a maximum value of 0.0058K at 300K. -1 .

[0035] Comparing Example 1 and Comparative Example 2, it can be seen that the Dy of Example 1 of the present invention 3+ The strategy of emitting intensity and excitation intensity ratio (R = (B1 + B2 + Y1 + Y2) / EX) has better temperature sensing characteristics than other strategies.

[0036] Comparative Example 3

[0037] To compare the Dy excitation at 778nm without a filter in this invention 3+ Doped CaWO4 phosphor based on Dy 3+ In a ratio-based temperature sensing technique where luminous intensity is proportional to excitation light intensity, we investigated the traditional Dy-based... 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 Towards the ground state respectively 6 H 15 / 2 Temperature sensing behavior of the ratio of two blue light emission intensities generated by energy level transitions. Figure 5 a is based on Figure 2 b. Data calculations without a filter at the excitation wavelength λex =778nm excitation Dy 3+ Dy doped CaWO4 phosphor 3+ The graph shows the variation of the intensity ratio of two blue lights (R = B1 / B2) with temperature. The graph demonstrates that the change in intensity ratio R with temperature T can be expressed using traditional theoretical formulas. Perform a fitting, where ΔE is Dy 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 The energy difference is given by k, where k is 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 fitting result is R = B1 / B2 = 2.25 * exp(-1485.89 / T), indicating that R = B1 / B2 also exhibits excellent temperature sensing characteristics. Figure 5 b is based on the formula The calculated absolute sensitivity S of the corresponding temperature sensor a The curve, as shown in the figure, reveals the absolute sensitivity S. a The value gradually increases with increasing temperature, reaching a maximum of 0.0008K at 650K. -1 .

[0038] Comparing Example 1 and Comparative Example 3, it can be seen that Example 1 of the present invention is based on Dy 3+ The ratio of emission intensity to excitation intensity for temperature sensing has increased the maximum absolute sensitivity by approximately 10 times, indicating that the filterless excitation of Dy at 778 nm using the temperature sensing technique described in Example 1 of this invention... 3+ Doped CaWO4 phosphor based on Dy 3+ Compared to traditional fluorescence emission intensity ratio technology based on thermally coupled energy levels, the emission intensity to excitation intensity ratio-based temperature sensing technology has superior temperature sensing characteristics.

[0039] Comparative Example 4

[0040] To compare the Dy excitation at 778nm without a filter in this invention 3+ Doped CaWO4 phosphor based on Dy 3+ Using a ratio-based temperature sensing technique that considers the emission intensity to the excitation intensity, we investigated the effect of Dy excitation at 778 nm with the addition of a filter. 3+ Ratio-type temperature sensing behavior of CaWO4-doped phosphor. From Figure 6 Figure a shows the Dy excitation at 778nm when a filter is added. 3+ The temperature-varying spectrum of the CaWO4-doped phosphor shows that, compared with... Figure 2 The temperature-varying spectrum of a without a filter is similar, with observations of Dy at the center wavelengths of 455, 485, 540, and 575 nm. 3+The blue and yellow emission peaks, and Dy 3+ The intensities of the two blue lights and two yellow lights show opposite trends with temperature, but... Figure 2 The difference is that the 1.5 harmonic peak of the excitation light did not appear at 518.7 nm, because the second harmonic of the excitation light was absorbed by the filter. From Figure 6 b shows Dy 3+ The two blue light emission intensity curves as a function of temperature show that, corresponding to Dy 3+4 I 15 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 15 / 2 The intensity of the two blue light emission peaks (B1 and B2) at the center wavelengths of the transition, located at 455 and 485 nm, shows opposite trends as the temperature increases. Figure 6 c gives Dy 3+ The graph shows the relationship between the ratio of the two blue light emission intensities (R = B1 / B2) and temperature T. The change in the intensity ratio R with temperature T can be expressed by a traditional theoretical formula. The fitting result is R = 3.16*exp(-1596.78 / T), indicating that R = B1 / B2 also exhibits excellent temperature sensing characteristics when there is a filter. Figure 6 d is based on the formula The calculated absolute sensitivity S of the temperature sensor a As can be seen from the figure, the absolute sensing sensitivity S a The value gradually increases with increasing temperature, reaching a maximum of 0.001K at 650K. -1 .

[0041] Comparing Example 1 and Comparative Example 4, it can be seen that with a filter, the 1.5 harmonic peak of the excitation light cannot be obtained, thus preventing the achievement of the Dy-based method in Example 1 of this invention. 3+ A ratio-based temperature sensing technique for emission intensity to excitation intensity. Furthermore, compared to the traditional Dy-based technique used in Comparative Example 4 with a filter... 3+ The fluorescence emission intensity ratio technique of thermally coupled energy levels, as described in Embodiment 1 of this invention, is based on Dy... 3+ The ratio of emission intensity to excitation intensity for temperature sensing has increased the maximum absolute sensitivity by approximately 8 times, indicating that the filterless excitation at 778 nm using the Dy temperature sensing technique employed in Example 1 of this invention... 3+ Doped CaWO4 phosphor based on Dy 3+ The ratio of emission intensity to excitation intensity for temperature sensing technology has superior temperature sensing characteristics.

[0042] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A ratiometric temperature sensing method based on excitation and emission, characterized in that, The specific steps are as follows: S1. Measure the excitation wavelength l without using a filter. ex When excited at 778 nm, Dy at a certain temperature 3+ Fluorescence spectra of CaWO4-doped phosphors in the 425–625 nm wavelength range, including Dy 3+ The blue and yellow light emission peaks generated by the excitation, as well as the 1.5 harmonic excitation peak from the 778 nm excitation light; S2. Calculate Dy in the 425~625 nm wavelength range at the temperature described in S1. 3+ Thermally Coupled Energy Level 4 I 15 / 2 / 4 F 9 / 2 To the ground state 6 H 15 / 2 and metastable state 6 H 13 / 2 The ratio of the sum of the intensities of the two blue and two yellow light rays during the energy level transition (B1+B2+Y1+Y2) to the intensity of the 1.5 harmonic excitation peak (EX) with a center wavelength of 518.7nm is R=(B1+B2+Y1+Y2) / EX; S3. Change Dy 3+ By repeating steps S1 and S2 at the temperature of CaWO4 phosphor doping, the relationship curve between intensity ratio R=(B1+B2+Y1+Y2) / EX and temperature T is obtained. S4. Use empirical formulas Fit the curve obtained in step S3 to obtain the curve based on Dy. 3+ Dy doped CaWO4 phosphor 3+ The quantitative relationship between the ratio of light emission intensity to excitation light intensity and temperature.

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