A temperature sensing method based on luminescence intensity ratio of rare earth Dy and CaWO4 matrix

Abstract

The application belongs to the technical field of temperature detection, and discloses a temperature sensing method based on rare earth Dy and CaWO4 matrix luminescence intensity ratio. The steps include constant temperature measurement of transition luminescence intensity, calculation of intensity ratio, measurement of multi-stage temperature transition luminescence intensity and calculation of intensity ratio, and curve fitting. The temperature sensing method based on rare earth Dy and CaWO4 matrix luminescence intensity ratio has super-high absolute and relative sensitivity of temperature sensing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of temperature detection, and particularly relates to a temperature sensing method based on a luminescence intensity ratio of rare earth Dy and CaWO4 matrix. BACKGROUND

[0002] Temperature is one of the physical quantities most contacted in people's daily life, and represents the cold and hot degree of an object. The temperature of human daily life, the survival and reproduction of animals and plants, and the surrounding environment are closely related. The accurate measurement of temperature is also highly required in the fields of electronic devices, aerospace, environmental monitoring, scientific research and industrial production. With the rapid development of science and technology, the accurate measurement of temperature with rapid response, high sensitivity and high spatial resolution is increasingly important. The fluorescence temperature detection technology has the advantages of non-contact, strong anti-interference ability, high sensitivity and spatial resolution, and rapid response, because it uses optical parameters responding to temperature. The ratio type fluorescence temperature detection technology can eliminate data distortion caused by equipment factors such as light bleaching, fluorescence probe load and retention, and fluorescence loss and excitation light source power fluctuation in the measurement process, and has the advantages of fluorescence detection self-calibration. The rare earth Dy 3+ ion can be excited by ultraviolet light to produce efficient blue and yellow light emission, and has a wide application in fluorescence temperature detection. At present, the ratio type temperature detection method based on Dy 3+ luminescence is the mainstream technology, which uses the intensity ratio of two blue light emissions generated by the transition of the 3+ thermally coupled energy level 4 I 15 / 2 and 4 F 9 / 2 to the ground state 6 H 15 / 2 to the ground state 4 I 15 / 2 and 4 F 9 / 2 particles satisfy the Boltzmann distribution, so the blue light intensity (denoted as I 4 I 15 / 2 generated by the transition of the 6 H 15 / 2 energy level to the ground state energy level 4 I 15 / 2 → 6 H 15 / 2 and the blue light intensity (denoted as I B1 ) generated by the transition of the 4 F 9 / 2 energy level to the ground state energy level 6 H 15 / 2 ( 4 F 9 / 2 → 6 H 15 / 2 ) satisfy the following relationship: B2The ratio of the two satisfies the following relationship:

[0003]

[0004] In the above equation, ΔE represents the thermally coupled energy level. 4 I 15 / 2 and 4 F 9 / 2 The 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 emission frequency. For example, in Dy 3+ Y4Al2O9 doped [1] Dy 3+ Doped BaYF5 [2] Dy 3+ GdVO4 doping [3] Dy 3+ Gd2Ti2O7 doped [4] Dy 3+ doped Y2SiO5 [5] Dy 3+ Doped CaWO4 [6] and Dy 3+ YNbO4 doped [7] In phosphors such as [specific phosphors], Dy-based [phosphors] were achieved under ultraviolet light excitation. 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 The ratio of blue emission intensity during the transition (R = I) B1 / I B2 Temperature sensing based on Dy. 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 To the ground state energy level respectively 6 H 15 / 2 and metastable energy levels 6 H 13 / 2 Leap ( 4 I 15 / 2 / 4 F 9 / 2 → 6 H 15 / 2 and 4 I 15 / 2 / 4 F 9 / 2 → 6 H 13 / 2 The ratio of blue to yellow light intensity produced also has a quantitative relationship with temperature and can be used for temperature detection. [8] In addition, there are reports using data from Dy 3+The intensity ratio of the fluorescence from the non-thermal coupled energy level transition to the temperature is used for temperature sensing. For example, the intensity ratio of the blue luminescence from the transition of Dy 3+ Dy 3+4 I 15 / 2 → 6 H 15 / 2 transition to the temperature is used for temperature sensing 4 F 9 / 2 → 6 H 11 / 2 transition to the temperature is used for temperature sensing [2] ; the intensity ratio of the blue luminescence from the transition of Dy 3+ doped CaWO4 phosphor is also found to be proportional to the temperature 3+4 G 11 / 2 → 6 H 15 / 2 transition to the temperature is used for temperature sensing 4 F 9 / 2 → 6 H 15 / 2 transition to the temperature is used for temperature sensing [6] . In addition to the intensity ratio of the luminescence from the transition of Dy 3+ , the intensity ratio of the luminescence from the transition of Dy 3 + doped Gd2Ti2O7 phosphor is also found to be proportional to the temperature 3+4 F 9 / 2 → 6 H 15 / 2 transition to the temperature is used for temperature sensing [4] .

[0005] According to the definition of sensitivity, the absolute sensitivity of temperature sensing is The relative sensitivity of temperature sensing is For the temperature sensing strategy based on the transition of Dy 3+ thermal coupled energy level 4 I 15 / 2 and 4 F 9 / 2 , the absolute sensitivity S a and the relative sensitivity S r of temperature sensing can be obtained according to formula (1) as follows:

[0006]

[0007]

[0008] It can be seen from formula (2) that the absolute sensitivity S adepends on the energy difference ΔE of the thermally coupled energy levels and the fluorescence intensity ratio R. Dy 3+ thermally coupled energy levels 4 I 15 / 2 and 4 F 9 / 2 The energy difference ΔE is a constant value, and the influence of different matrix materials on ΔE is also small, so the absolute sensitivity S a is mainly related to the fluorescence intensity ratio R. The reported temperature sensing scheme based on Dy 3+ thermally coupled energy levels 4 I 15 / 2 and 4 F 9 / 2 to the ground state 6 H 15 / 2 The two blue light intensity ratio R = I B1 / I B2 generated by the energy level transition has a maximum absolute sensitivity S a , which is low, all of which do not exceed 40*10 -4 K -1 . For example, Dy 3+ doped Y4Al2O9 fluorescent powder S a has a maximum value of 31*10 -4 K -1 at 873K, Dy 3+ doped BaYF5 fluorescent powder has a maximum absolute sensitivity of 6.6*10 -4 K -1 at 773K, Dy 3 + doped GdVO4 fluorescent powder has a maximum value of S a of 39*10 -4 K -1 at 473K, Dy 3+ doped Gd2Ti2O7 fluorescent powder has a maximum absolute sensitivity of 39*10 -4 K -1 at 443K, Dy 3+ doped Y2SiO5 fluorescent powder has a maximum value of S a of 27*10 -4 K -1 at 1039K, Dy 3+ doped CaWO4 fluorescent powder has a maximum absolute sensitivity of 10.6*10 -4 K -1 at 638K, Dy 3+ doped YNbO4 fluorescent powder has a maximum absolute sensitivity of 33*10 -4 K -1 at 700K. As can be seen from formula (1), the absolute sensitivity S rIt is only related to the energy difference E between the thermally coupled energy levels. Because Dy 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 The energy difference ΔE remains essentially constant, therefore almost all Dy 3+ The maximum relative sensitivity of doped phosphors is generally low, not exceeding 2% K. -1 .

[0009] For the current Dy-based 3+ Ratio-type temperature sensing technology based on non-thermally coupled energy level transitions has an absolute temperature sensing sensitivity S. a and relative sensitivity S r It's still not high. For example, Dy 3+ Dy-based doped BaYF5 phosphor 3+ The temperature sensing strategy based on the ratio of blue to red luminescence intensity exhibits a maximum absolute sensitivity of 34.88 × 10⁻⁶ at 687 K. -4 %K -1 It exhibits a maximum relative sensitivity of 1.60% K at 293 K. -1 Dy 3+ Dy-based CaWO4 phosphors 3+ The temperature sensing strategy based on the ratio of ultraviolet to blue emission intensity achieved a maximum relative sensitivity of 1.71% K at 450 K. -1 For Dy 3+ Matrix trap luminescence and Dy-based luminescence in Gd2Ti2O7 doped phosphors 3+ The temperature sensing strategy based on the intensity ratio of blue light emission has a maximum relative sensitivity of only 1.127% K at 443 K. -1 .

[0010] From the absolute sensitivity S of temperature sensing a Definition As can be seen, to effectively improve S a This requires a large range of variation in the fluorescence intensity ratio R with temperature T. As can be seen from the aforementioned research status, currently Dy 3+ The limited range of variation of the fluorescence intensity ratio R in doped phosphors leads to a decrease in absolute sensitivity S. a It remains low. And the relative sensitivity of the temperature sensor, S... r Definition As can be seen, to obtain a higher S r This requires not only a large range of variation in the fluorescence intensity ratio R with temperature T, but also a relatively small value for the fluorescence intensity ratio R. As can be seen from the aforementioned research status, currently Dy 3+In doped phosphors, the range of fluorescence intensity ratio R with temperature and the magnitude of R are often mutually exclusive, leading to a difference in relative sensitivity S. r Lower. Summary of the Invention

[0011] To overcome the shortcomings of existing technologies, this invention provides a temperature sensing method based on the luminescence intensity ratio of rare-earth Dy and CaWO4 matrices, using 259nm light to excite Dy. 3+ Doping with CaWO4 phosphor, by controlling the WO4 in the CaWO4 matrix 2- Effective activation of functional groups and WO4 2- Group towards Dy 3+ The efficient energy transfer was achieved based on the quantitative relationship between the intensity ratio of rare-earth Dy and CaWO4 matrix luminescence and temperature, realizing the efficient energy transfer of Dy. 3+ A novel ratiometric temperature sensing method doped with CaWO4 phosphor exhibits ultra-high absolute and relative temperature sensing sensitivity.

[0012] The above-mentioned objective of this invention is achieved through the following technical solution: a temperature sensing method based on the luminescence intensity ratio of rare earth Dy and CaWO4 matrix, comprising the following steps:

[0013] S1. Using wavelength λ ex =259nm light-excited Dy 3+ CaWO4 phosphor was used to measure the photoluminescence spectrum of WO4 at a certain temperature, with the center wavelength located at 410 nm. 2- blue luminescence intensity of the group And the corresponding Dy with a center wavelength of 455nm 3+4 I 15 / 2 → 6 H 15 / 2 Blue luminescence intensity I during transition B1 The center wavelength located at 480nm corresponds to Dy 3+4 F 9 / 2 → 6 H 15 / 2 Blue luminescence intensity I during transition B2 Or, the center wavelength located at 575nm corresponds to Dy. 3+4 F 9 / 2 → 6 H 13 / 2 The yellow luminescence intensity I of the transition Y ;

[0014] S2. Calculation steps: Dy at temperature S1 3+ and WO4 2- The ratio of the intensity of light emitted by the functional groups, i.e. or

[0015] S3. Change Dy 3+ Doping CaWO4 fluorescent powder, repeating the above steps S1 and S2, the luminescence intensity ratio or the relationship curve with temperature T;

[0016] S4. Using empirical formula

[0017]

[0018] Fitting the curve obtained in step S3, where a, b and c are fitting constants, to obtain the quantitative relationship between the luminescence intensity ratio of Dy 3+ and CaWO4 matrix and temperature.

[0019] Further, the temperature range measured in step S1 is any value in the range of 300-475K.

[0020] Further, the temperature change range in step S3 is between 300-475K.

[0021] The present application is based on the characteristics of the temperature measurement technology of rare earth Dy and CaWO4 matrix luminescence intensity ratio to achieve high sensing sensitivity as follows:

[0022] a, In the present application, Dy 3+ The excitation light wavelength of the doped CaWO4 fluorescent powder is 259nm, which can effectively excite WO4 2- group in CaWO4 matrix, so as to obtain the luminescence of WO4 2- group;

[0023] b, In the present application, through the effective energy transfer from WO4 2- group to Dy 3+ , the luminescence of WO4 2- group and Dy 3+ with large opposite change trend with temperature increase is obtained;

[0024] c, The fluorescent ratio type temperature sensing technology of the present application is based on the luminescence intensity ratio of Dy 3+ doped CaWO4 fluorescent powder, Dy 3+ blue or yellow luminescence and WO4 2- group blue luminescence intensity ratio R and temperature T presents a specific quantitative relationship

[0025] d, The present application is based on the ratio type temperature sensing technology of rare earth Dy and CaWO4 matrix luminescence intensity, which has ultra-high temperature sensing absolute sensitivity S a and relative sensitivity S r , and the absolute sensitivity S aand relative sensitivity S r The calculation formula is

[0026]

[0027]

[0028] The beneficial effects of the present application compared with the prior art are: the present application can effectively excite the WO4 3+ group in the CaWO4 matrix by 259nm ultraviolet light excitation, and can effectively excite the WO4 2- group and energy transfer from the WO4 2- group to Dy 3+ , and can obtain blue light from the WO4 2- group and blue and yellow light from Dy 3+ . Due to the effective energy transfer from the WO4 2- group to Dy 3+ , the luminescence intensity from the WO4 2- group and Dy 3+ presents completely opposite change trends with temperature increasing, so the intensity ratio of the luminescence of the WO4 2- group and Dy 3+ has a large change interval with temperature. In addition, by selecting the appropriate waveband of Dy 3+ luminescence, a smaller fluorescence intensity ratio R can also be obtained. Therefore, the present application is based on the temperature sensing new method of luminescence intensity ratio of rare earth Dy and CaWO4 matrix, and has ultra-high absolute and relative sensitivity of temperature sensing. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be further described below in combination with the drawings and specific embodiments.

[0030] Fig. 1 is the excitation spectrum of Dy 3+ doped CaWO4 fluorescent powder (monitoring wavelength λ em = 575nm) (Fig. a), the room temperature photoluminescence spectrum of Dy ex doped CaWO4 fluorescent powder under the excitation of wavelength λ 3+ = 259 and 352nm (Fig. b), the photoluminescence spectrum of Dy 3+ doped CaWO4 fluorescent powder at different temperatures (excitation wavelength λ ex = 259nm) (Fig. c), and the energy level structure and luminescence mechanism of Dy 3+ doped CaWO4 fluorescent powder (Fig. d);

[0031] Figure 2 Fig. 2 is the luminescence spectrum of Dy 3+ doped CaWO4 fluorescent powder at λ exDy under light excitation at λ = 259 nm 3+ Blue luminescence intensity (I B1 ) and CaWO4 host luminescence intensity Temperature dependence curve (Fig. a), Dy 3+ Ratio of blue luminescence intensity and CaWO4 host luminescence intensity Temperature dependence curve (Fig. b) and absolute and relative temperature sensitivity curves (Fig. c);

[0032] Figure 3 Dy of Example 2 of the present invention 3+ CaWO4 doped phosphor under light excitation at λ = 259 nm ex Dy under light excitation at λ = 259 nm 3+ Blue luminescence intensity (I B2 ) and CaWO4 host luminescence intensity Temperature dependence curve (Fig. a), Dy 3+ Ratio of blue luminescence intensity and CaWO4 host luminescence intensity Temperature dependence curve (Fig. b) and absolute and relative temperature sensitivity curves (Fig. c);

[0033] Figure 4 Dy of Example 3 of the present invention 3+ CaWO4 doped phosphor under light excitation at λ = 259 nm ex Dy under light excitation at λ = 259 nm 3+ Yellow luminescence intensity (I Y ) and CaWO4 host luminescence intensity Temperature dependence curve (Fig. a), Dy 3+ Ratio of yellow luminescence intensity and CaWO4 host luminescence intensity Temperature dependence curve (Fig. b) and absolute and relative temperature sensitivity curves (Fig. c);

[0034] Figure 5 Dy of Comparative Example 1 of the present invention 3+ CaWO4 doped phosphor under light excitation at λ = 259 nm ex Dy under light excitation at λ = 259 nm 3+ Two blue luminescence intensities (I B1 and I B2 ) temperature dependence curve (Fig. a), Dy 3+ Ratio of the two blue luminescence intensities (R = I B1 / I B2 ) temperature dependence curve (Fig. b) and absolute and relative temperature sensitivity curves (Fig. c);

[0035] Figure 6 Dy of Comparative Example 2 of the present invention 3+Doped CaWO4 phosphor in λ ex The variable-temperature photoluminescence spectrum under 259 nm light excitation (Figure a), Dy 3+ Two blue luminescence intensities (I B1 and I B2 The curve of Dy versus temperature (Figure b) 3+ The ratio of the two blue light emission intensities (R = I) B1 / I B2 The curves showing the change of temperature with temperature (Figure c), and the absolute and relative temperature sensitivity curves (Figure d). Detailed Implementation

[0036] 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.

[0037] 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). Certain amounts of Na2WO4·2H2O and CaCl2·H2O powders were dissolved in deionized water to prepare 0.5 mol / L Na2WO4 and CaCl2 aqueous solutions, respectively. A certain amount of Dy2O3 powder was dissolved in excess nitric acid to prepare a 0.01 mol / L Dy(NO3)3 aqueous 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. A white precipitate was obtained, which was then centrifuged, washed, dried, sintered at 1523 K for 3 h, cooled, and ground to obtain 3 mol% Dy2O3. 3+ Doped CaWO4 phosphor. Dy was measured using a HITA HIF-4600 fluorescence spectrometer. 3+ The excitation and photoluminescence spectra of the CaWO4-doped phosphor were analyzed using a DMU-450 heating stage to control the Dy emission. 3+ Temperature at which CaWO4 phosphor is doped.

[0038] from Figure 1a The Dy shown 3+ The excitation spectrum of the CaWO4-doped phosphor shows that when the monitoring wavelength λ... em In Dy 3+ At the yellow emission peak at 575 nm, a relatively broad excitation band and multiple excitation peaks appeared in the 200–450 nm wavelength range. Among them, the excitation band with a central wavelength at 259 nm originated from WO4 in the CaWO4 matrix. 2-The excitation of the group, with excitation peaks centered at 327, 352, 367, and 369 nm, respectively, originates from Dy 3+6 H 15 / 2 → 4 M 17 / 2 , 6 P 7 / 2 , 4 I 11 / 2 and 4 F 7 / 2 The excited transition of Dy. 3+ The yellow light emission can come from Dy 3+ Direct excitation can also be achieved through WO4 in the CaWO4 matrix. 2- Group towards Dy 3+ Energy transfer is achieved.

[0039] from Figure 1b The Dy shown 3+ Doped CaWO4 phosphor in λ ex The room-temperature photoluminescence spectra under excitation by 259 and 352 nm light show that, under ultraviolet light excitation at 259 and 352 nm, Dy 3+ Strong blue and yellow emission peaks with center wavelengths at 480 and 575 nm were observed in the CaWO4 phosphor within the 450–700 nm wavelength range, corresponding to Dy 3+4 F 9 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 13 / 2 Emission transitions. Weak blue and red emission peaks were also observed at the center wavelengths of 455 and 663 nm, corresponding to Dy, respectively. 3+4 I 15 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 11 / 2 Emission transition. Furthermore, it is related to the excitation wavelength λ. ex The emission spectrum of λ = 352nm is different, and the excitation wavelength λ ex The emission spectrum at 259 nm also shows a broad emission band at the center wavelength of 410 nm, corresponding to WO4 in the CaWO4 matrix. 2- The light emission of the radical indicates that WO4 can be simultaneously obtained under 259 nm wavelength light excitation. 2- Groups and Dy 3+ The light emitted.

[0040] from Figure 1c The Dy shown 3+Doped CaWO4 phosphor in λ ex The temperature-dependent photoluminescence spectrum excited by 259 nm light shows that temperature changes do not alter the position of the phosphor's emission wavelength, but they significantly affect the emission intensity of each wavelength. 3+ WO4 in CaWO4 phosphor 2- Groups and Dy 3+ The luminescence of Dy varies with temperature, which means that Dy 3+ The luminescence properties of CaWO4 doped phosphors are closely related to temperature.

[0041] from Figure 1d The Dy shown 3+ The energy level structure and luminescence mechanism of the doped CaWO4 phosphor show that, at λ... ex Under light excitation at 327, 352, 367 or 369 nm, Dy 3+ From the ground state 6 H 15 / 2 The energy level is excited to the corresponding higher-order excited state energy level, and then relaxes nonradiatively to the thermally coupled energy level. 4 I 15 / 2 and 4 F 9 / 2 and towards lower energy levels 6 H 15 / 2 , 6 H 13 / 2 and 6 H 11 / 2 Radiative transitions resulted in the emission of blue, yellow, and red light with center wavelengths of 455, 480, 575, and 663 nm, respectively. Furthermore, WO4 in the CaWO4 matrix was excited by 259 nm light. 2- Groups can also be excited from the ground state to the excited state; WO4 in the excited state 2- The group transitions to the ground state and emits blue light with a central wavelength of 410 nm, and also transfers energy to Dy through energy transfer. 3+ This also caused Dy 3+ Light emission.

[0042] Example 1

[0043] from Figure 2 Dy shown in a 3+ Dy doped CaWO4 phosphor under 259nm light excitation 3+4 I 15 / 2 → 6 H 15 / 2 The blue luminescence intensity (I) produced by the transition B1 ) and WO4 2- Luminous intensity of the radical As can be seen from the change with temperature, Dy 3+Blue luminescence intensity I B1 and WO4 2- Group luminescence intensity The trend of change is opposite as temperature increases, among which It decreases rapidly with increasing temperature, exhibiting a temperature quenching phenomenon, while I B1 As temperature increases, the intensity gradually increases, exhibiting an inverse temperature quenching phenomenon. This opposite trend in luminescence intensity with temperature means that the ratio of the two changes significantly with temperature, which contributes to improving temperature sensing sensitivity. From Figure 2 b shows Dy 3+ The ratio of the luminescence intensity of the CaWO4 matrix to the luminescence intensity The curve showing the change with temperature indicates that as the temperature increases from 300K to 475K, the strength ratio... The value increased significantly from 0.0039 to 0.3640. Furthermore, the intensity ratio... The change with temperature T can be fitted using formula (4), and the fitting result is: Indicates that based on Dy 3+ Blue glow and WO4 2- The intensity ratio of the light emitted by the functional group It exhibits excellent temperature sensing characteristics. Figure 2 c is the strength ratio calculated according to formulas (5) and (6). Temperature sensing absolute sensitivity S a and relative sensitivity S r As can be seen from the figure, the absolute sensitivity S a The value gradually increases with increasing temperature, reaching a maximum of 42.52 * 10 at 475 K. -4 K -1 Relative sensitivity S r The value gradually decreases as the temperature increases, reaching a maximum of 21.03% K at 300 K. -1 .

[0044] Example 2

[0045] from Figure 3 Dy shown in a 3+ Dy doped CaWO4 phosphor under 259nm light excitation 3+4 F 9 / 2 → 6 H 15 / 2 The blue luminescence intensity (I) produced by the transition B2 ) and WO4 2- Luminous intensity of the radical As can be seen from the change with temperature, Dy 3+ Blue luminescence intensity I B2 and WO4 2- Luminous intensity of the radical The opposite trend is also observed as temperature increases, among which It decreases rapidly with increasing temperature, while I B2 The intensity gradually increases with increasing temperature. This inverse relationship between luminescence intensity and temperature also implies that the ratio of the two changes significantly with temperature. Figure 3 b shows Dy 3+ The ratio of the luminescence intensity of the CaWO4 matrix to the luminescence intensity The curve showing the change with temperature indicates that as the temperature increases from 300K to 475K, the strength ratio... The intensity ratio increased significantly, from 0.3954 to 2.5581. The change with temperature T can also be fitted using formula (4), and the fitting result is: Indicates that based on Dy 3+ Blue glow and WO4 2- The intensity ratio of the light emitted by the functional group It also exhibits excellent temperature sensing characteristics. Figure 3 c is the strength ratio calculated according to formulas (5) and (6). Temperature sensing absolute sensitivity S a and relative sensitivity S r As can be seen from the figure, the absolute sensitivity S a The value gradually decreases as the temperature increases, reaching a maximum of 161.53 * 10 at 300 K. -4 K -1 Relative sensitivity S r The value gradually decreases as the temperature increases, reaching a maximum of 3.97% K at 300 K. -1 .

[0046] Example 3

[0047] from Figure 4 Dy shown in a 3+ Dy doped CaWO4 phosphor under 259nm light excitation 3+4 F 9 / 2 → 6 H 13 / 2 The yellow luminescence intensity (I) produced by the transition Y ) and WO4 2- Luminous intensity of the radical As can be seen from the change with temperature, Dy 3+ Yellow luminescence intensity I Y and WO4 2- Luminous intensity of the radical The opposite trend is also observed as temperature increases, among which It decreases rapidly with increasing temperature, while I YThe intensity increases rapidly with rising temperature. This inverse trend in luminescence intensity with temperature also implies that the ratio of the two changes significantly with temperature. From Figure 4 b shows Dy 3+ The ratio of the luminescence intensity of the CaWO4 matrix to the luminescence intensity The curve showing the change with temperature indicates that as the temperature increases from 300K to 475K, the strength ratio... The largest change was from 1.1436 to 7.6840. Intensity ratio The change with temperature T can also be fitted using formula (4), and the fitting result is: Indicates that based on Dy 3+ Yellow glow and WO4 2- The intensity ratio of the light emitted by the functional group It also exhibits excellent temperature sensing characteristics. Figure 4 c is the strength ratio calculated according to formulas (5) and (6). Temperature sensing absolute sensitivity S a and relative sensitivity S r As can be seen from the figure, the absolute sensitivity S a The value gradually decreases as the temperature increases, reaching a maximum of 449.52*10 at 300K. -4 K -1 Relative sensitivity S r The value gradually decreases as the temperature increases, reaching a maximum of 3.83% K at 300 K. -1 .

[0048] Comparative Example 1

[0049] To compare the Dy under 259nm light excitation of the present invention 3+ Temperature sensing technology based on the ratio of CaWO4 matrix to Dy luminescence intensity using CaWO4-doped phosphors. We employ Dy... 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 Towards the ground state respectively 6 H 15 / 2 A temperature sensing strategy for the ratio of blue emission intensity during energy level transitions is compared. Figure 5 a's Dy 3+ Dy doped CaWO4 phosphor under 259nm light excitation 3+4 I 15 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 15 / 2 The two blue luminescence intensities (I) produced by the transitionB1 and I B2 As can be seen from the change with temperature, Dy 3+ Two blue luminescence intensities I B1 and I B2 Both increase with increasing temperature. From Figure 5 b shows Dy 3+ The ratio of the two blue light emission intensities (R=I) B1 / I B2 The curve showing the change in strength with temperature indicates that as the temperature increases from 300K to 475K, the strength ratio R = I... B1 / I B2 The value increased very little, from 0.0098 to 0.1423. Strong contrast: R = I B1 / I B2 The change with temperature T can be fitted using formula (1), and the fitting result is: Indicates that based on Dy 3+ The ratio of the two blue light emission intensities also exhibits good temperature sensing characteristics. Figure 5 c is the strength ratio R = I calculated according to formulas (2) and (3). B1 / I B2 Temperature sensing absolute sensitivity S a and relative sensitivity S r As can be seen from the figure, the absolute sensitivity S a The value gradually increases with increasing temperature, reaching a maximum of 10.13 * 10 at 475 K. -4 K -1 Relative sensitivity S r The K value gradually decreases as the temperature increases, reaching a maximum of 1.78% K at 300 K. -1 .

[0050] Comparing Examples 1-3 and Comparative Example 1, it can be seen that in Comparative Example 1, the strength ratio R = I increases with increasing temperature. B1 / I B2 The change was the smallest, while in Example 3, the intensity ratio increased with increasing temperature. The change in temperature is the largest, therefore the absolute sensitivity of temperature sensing in Examples 1-3 of the present invention is superior to that in Comparative Example 1, where Example 3 is based on intensity ratio. The maximum absolute sensitivity of the strategy was improved by approximately 45 times compared to Comparative Example 1. Meanwhile, due to the increased intensity with increasing temperature in Example 1... The change is large, and the intensity is greater than that. The numerical values ​​are also relatively small, therefore the relative sensitivity of temperature sensing in Examples 1-3 of the present invention is better than that in Comparative Example 1, where the intensity ratio-based sensitivity of Example 1 is superior. The maximum absolute sensitivity of the strategy is approximately 12 times higher than that of Comparative Example 1. This indicates that the temperature sensing technology of the present invention based on the luminescence intensity ratio of rare-earth Dy and CaWO4 matrix is ​​superior to the traditional Dy-based technology. 3+ The temperature measurement technology with two blue light intensity ratios has better temperature sensing characteristics.

[0051] Comparative Example 2

[0052] To compare the Dy under 259nm light excitation of the present invention 3+ Based on temperature sensing technology using the ratio of CaWO4 matrix to Dy luminescence intensity, we employed 352nm photoexcitation of Dy phosphor. 3+ The temperature sensing behavior of CaWO4-doped phosphor was studied and compared. Figure 6 Dy shown in a 3+ Doped CaWO4 phosphor in λ ex The variable-temperature photoluminescence spectrum excited by 352nm light shows that no light emission from the CaWO4 matrix was observed near the center wavelength of 410nm. Therefore, the 352nm excitation light is not suitable for the ratiometric temperature sensing technology of Examples 1-3 of this invention, and only the traditional Dy-based method can be used. 3+ Thermally Coupled Energy Level 4 I 15 / 2 and 4 F 9 / 2 Towards the ground state 6 H 15 / 2 Temperature is sensed by comparing the intensity of two blue luminescence particles during an energy level transition. Figure 6 b shows Dy 3+ Dy doped CaWO4 phosphor under 352nm light excitation 3+4 I 15 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 15 / 2 The two blue luminescence intensities (I) produced by the transition B1 and I B2 As can be seen from the change with temperature, Dy 3+ Two blue luminescence intensities I B1 and I B2 The changes show opposite trends as temperature increases, where I B2 It gradually decreases as temperature increases, while I B1 It increases slowly with increasing temperature. From Figure 6 c shows Dy 3+ The ratio of the two blue light emission intensities (R=I) B1 / I B2The curve showing the change in strength with temperature indicates that as the temperature increases from 300K to 475K, the strength ratio R = I... B1 / I B2 The change from 0.0188 to 0.1090 is much smaller than that in Examples 1-3 of this invention. The strength ratio R = I B1 / I B2 The change with temperature T can also be fitted using formula (1), and the fitting result is: This indicates that under 352nm light excitation, Dy-based 3+ The ratio of the two blue light emission intensities also exhibits good temperature sensing characteristics. Figure 6 d is the absolute sensitivity of the temperature sensor calculated according to formulas (2) and (3). a and relative sensitivity S r Curve. The absolute sensitivity S can be seen from the graph. a The value gradually increases with increasing temperature, reaching a maximum of 7.15*10 at 475K. -4 K -1 Relative sensitivity S r The K value gradually decreases as the temperature increases, reaching a maximum of 1.65% K at 300 K. -1 .

[0053] Comparing Examples 1-3 and Comparative Example 2, it can be seen that in Comparative Example 2, the strength ratio R = I increases with increasing temperature. B1 / I B2 The change in temperature is also minimal; therefore, the absolute and relative sensitivity of temperature sensing in Embodiments 1-3 of the present invention are superior to that in Comparative Example 2, where the intensity ratio is the most significant factor. The maximum absolute sensitivity of the strategy was improved by approximately 63 times compared to control example 2, based on the intensity ratio. The maximum relative sensitivity of the strategy is improved by approximately 13 times compared to Comparative Example 2. Furthermore, both Comparative Examples 1 and 2 also show that, although both are based on Dy... 3+ The temperature measurement strategy based on the ratio of the two blue emission intensities, but using λ ex The absolute and relative sensitivity of temperature sensing excited by 259nm light is also superior to that of λ. ex The case of excitation with 352nm light indicates that the present invention uses 259nm light to excite Dy. 3+ Doped CaWO4 phosphors exhibit optimal temperature detection characteristics.

[0054] 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.

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Claims

1. A temperature sensing method based on the luminescence intensity ratio of rare earth Dy and CaWO4 matrices, characterized in that, Includes the following steps: S1. Using wavelength λ ex =259nm light-excited Dy 3+ CaWO4 phosphor was used to measure the photoluminescence spectrum of WO4 at a certain temperature, with the center wavelength located at 410 nm. 2- The blue emission intensity of the group and the corresponding Dy with a center wavelength of 455nm 3+ 4 I 15 / 2 → 6 H 15 / 2 Blue luminescence intensity I during transition B1 The center wavelength located at 480nm corresponds to Dy 3+4 F 9 / 2 → 6 H 15 / 2 Blue luminescence intensity I during transition B2 Or, the center wavelength located at 575nm corresponds to Dy. 3+4 F 9 / 2 → 6 H 13 / 2 The yellow luminescence intensity I of the transition Y ; By analyzing WO4 in the CaWO4 matrix 2- Effective activation of functional groups and WO4 2- Group towards Dy 3+ The efficient energy transfer was achieved by Dy 3+ Ratio-type temperature sensing using CaWO4-doped phosphor; obtaining WO4 phosphors exhibiting significantly opposite trends with increasing temperature. 2- Groups and Dy 3+ Glowing light; S2. Calculation steps: Dy at temperature S1 3+ and WO4 2- The ratio of the intensity of light emitted by the functional groups, i.e. or S3. Change Dy 3+ By repeating steps S1 and S2 at the temperature of the CaWO4 phosphor doping, the luminescence intensity ratio can be obtained. or The curve showing the relationship between temperature T; S4. Use empirical formulas The curve obtained in step S3 is fitted, where a, b, and c are fitting constants, to obtain the curve based on Dy. 3+ Quantitative relationship between the luminescence intensity ratio of CaWO4 matrix and temperature.

2. The temperature sensing method based on the luminescence intensity ratio of rare earth Dy and CaWO4 matrix according to claim 1, characterized in that, In step 1, the measured temperature range is any value between 300-475K.

3. The temperature sensing method based on the luminescence intensity ratio of rare earth Dy and CaWO4 matrix according to claim 1, characterized in that, The temperature change range in step S3 is between 300-475K.

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