A ratiometric temperature sensing method based on Sm ion / Tb ion luminescence

Abstract

A ratiometric temperature sensing method based on Sm / Tb ion luminescence belongs to the field of fluorescence temperature sensing. This invention addresses the problem that conventional fluorescence intensity ratio temperature sensing technology cannot be applied to higher temperature regions due to the thermal quenching effect of fluorescence, which causes both fluorescence beams to attenuate at higher temperatures. The method involves: 1. Preparation of temperature-sensitive materials; 2. Determination of the functional relationship between the fluorescence intensity ratio A / B and temperature; 3. Detection of ambient temperature. This invention is used for ratiometric temperature sensing based on Sm / Tb ion luminescence.

Description

Technical Field

[0001] The invention belongs to the field of fluorescence temperature sensing. Background Art

[0002] The importance of temperature is self-evident, and it plays a key role in daily life, industrial production, crop growth and other scenarios. Among the many temperature measurement methods, fluorescence temperature sensing has unique application prospects due to its non-contact characteristics. Rare earth-doped luminescent materials have tunable luminescence bands and excitation strategies, so they are often used for fluorescence temperature detection. Among them, the fluorescence intensity ratio temperature sensing method is particularly attractive due to its strong anti-interference and detection portability. The core idea of this method is to construct a functional relationship and a calibration curve between the ratio of two beams of fluorescence from the same luminescence center or different luminescence centers and the temperature, and to infer the temperature by actually measuring the ratio of the two beams of fluorescence.

[0003] Relative sensitivity is a core parameter of fluorescence intensity ratio temperature sensing methods. To achieve higher relative sensitivity, the following strategy is typically adopted: as temperature rises, the intensity of one fluorescence beam increases monotonically, while the intensity of the other decreases monotonically. This way, the intensities of the two fluorescence beams exhibit opposite variations, typically resulting in higher relative sensitivity. However, this technique currently has drawbacks: fluorescence typically decreases with increasing temperature, an effect known as fluorescence quenching. Therefore, while two fluorescence beams with different temperature responses can be found in a lower temperature range (such as near room temperature), at higher temperatures (500K to 800K), both fluorescence beams inevitably experience severe quenching, resulting in suboptimal relative sensitivity. Furthermore, this intensity quenching further leads to a poor signal-to-noise ratio. Summary of the Invention

[0004] The present invention aims to solve the problem that the existing fluorescence thermal quenching effect causes both beams of fluorescence to attenuate in higher temperature zones, making the traditional fluorescence intensity ratio temperature sensing technology unable to be applied to higher temperature zones, and further provides a ratio temperature sensing method based on Sm ion / Tb ion luminescence.

[0005] A ratiometric temperature sensing method based on Sm ion / Tb ion luminescence is carried out in the following steps:

[0006] 1. Preparation of temperature-sensitive materials:

[0007] Preparation of Tb 3+ and Sm 3+ Doped CaWO4 to obtain temperature-sensitive materials;

[0008] 2. Determination of the functional relationship between the fluorescence intensity ratio A / B and temperature:

[0009] The temperature sensitive material is excited by laser with a wavelength of 405nm, and the emission spectrum of the temperature sensitive material at different calibration temperatures is recorded by spectrometer; the emission spectrum of Tb is recorded. 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red fluorescence band at the central wavelength of the ion is located at 648nm and is integrated, which is recorded as the fluorescence intensity B. The ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated. A fluorescence intensity ratio A / B is obtained at each calibration temperature. After processing, a fitting curve is obtained. According to the fitting curve, the functional relationship between the fluorescence intensity ratio A / B and temperature is obtained:

[0010] A / B = -0.06173 + 4.91 × 10 -4 ×T-1.29×10 -6 ×T 2 +1.13×10 -9 ×T 3 , where T is the absolute temperature;

[0011] 3. Ambient temperature detection:

[0012] The temperature sensitive material is placed in the test environment, and then the temperature sensitive material is excited by a laser with a wavelength of 405nm. The emission spectrum of the temperature sensitive material is collected by a spectrometer, and the Tb 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red light fluorescence band with the central wavelength of the ion at 648nm is integrated; the ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated, and the ratio A / B is substituted into the functional relationship obtained in step 2. T is calculated as the ambient temperature, and the ratio temperature sensing method based on the luminescence of Sm ions / Tb ions is completed.

[0013] The beneficial effects of the present invention are:

[0014] Conventional fluorescence intensity ratio temperature sensing methods are not applicable to higher temperature ranges (500K-800K) because both fluorescence beams involved will experience severe thermal quenching. The present invention overcomes this limitation and has the following advantages:

[0015] 1. Sm involved in the present invention 3+ The red light of the quartz crystal only shows very weak attenuation as the temperature rises, and can still maintain 80% of the room temperature even at 803K, which has a strong anti-thermal quenching effect; the Tb 3+ The green light gradually increases with increasing temperature, up to 76 times. This ensures an excellent signal-to-noise ratio between the two fluorescence beams. Conventional fluorescence intensity ratio temperature measurement, however, is inapplicable because the two fluorescence beams decay to almost zero at 803K.

[0016] 2. Tb involved in the present invention 3+ Green light and Sm 3+ The red light has different temperature response, Tb 3+ The green light of the ion at 545nm increases rapidly with temperature to ensure excellent relative sensitivity, so Tb 3+ Green light and Sm 3+ The intensity ratio of the red light can reflect the temperature change in time, which ensures good relative sensitivity. Together with the excellent signal-to-noise ratio, the Sm-based 3+ / Tb 3+ The temperature resolution of the luminescence ratio temperature sensing method is still better than 1K at 803K.

[0017] 3. The applicable temperature range of the present invention is 303K to 803K, and it can be used in a wider temperature range.

[0018] Figures in the specification

[0019] Figure 1 This is the XRD diffraction result of the temperature-sensitive material prepared in step 1 of Example 1;

[0020] Figure 2 The emission spectrum of the temperature-sensitive material prepared in step 1 of Example 1 in the range of 303K to 803K, with an excitation wavelength of 405nm and a temperature variation interval of 50K;

[0021] Figure 3 The intensity ratio variation of 545nm green light and 648nm red light of the temperature-sensitive material prepared in step 1 of Example 1 in the range of 303K to 803K, with a temperature variation interval of 50K;

[0022] Figure 4 For Example 1 based on Sm 3+ / Tb 3+ The variation of relative sensitivity of the luminescence ratio temperature sensing method in the range of 303K to 803K;

[0023] Figure 5 For Example 1 based on Sm 3+ / Tb 3+ Variation of temperature resolution of luminescence ratio temperature sensing method in the range of 303K to 803K. DETAILED DESCRIPTION

[0024] Specific embodiment 1: This embodiment is a ratio temperature sensing method based on Sm ion / Tb ion luminescence, which is carried out in the following steps:

[0025] 1. Preparation of temperature-sensitive materials:

[0026] Preparation of Tb 3+ and Sm 3+ Doped CaWO4 to obtain temperature-sensitive materials;

[0027] 2. Determination of the functional relationship between the fluorescence intensity ratio A / B and temperature:

[0028] The temperature sensitive material is excited by laser with a wavelength of 405nm, and the emission spectrum of the temperature sensitive material at different calibration temperatures is recorded by spectrometer; the emission spectrum of Tb is recorded. 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red fluorescence band at the central wavelength of the ion is located at 648nm and is integrated, which is recorded as the fluorescence intensity B. The ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated. A fluorescence intensity ratio A / B is obtained at each calibration temperature. After processing, a fitting curve is obtained. According to the fitting curve, the functional relationship between the fluorescence intensity ratio A / B and temperature is obtained:

[0029] A / B = -0.06173 + 4.91 × 10 -4 ×T-1.29×10 -6 ×T 2 +1.13×10 -9 ×T 3 , where T is the absolute temperature;

[0030] 3. Ambient temperature detection:

[0031] The temperature sensitive material is placed in the test environment, and then the temperature sensitive material is excited by a laser with a wavelength of 405nm. The emission spectrum of the temperature sensitive material is collected by a spectrometer, and the Tb 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red light fluorescence band with the central wavelength of the ion at 648nm is integrated; the ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated, and the ratio A / B is substituted into the functional relationship obtained in step 2. T is calculated as the ambient temperature, and the ratio temperature sensing method based on the luminescence of Sm ions / Tb ions is completed.

[0032] The beneficial effects of this embodiment are:

[0033] Conventional fluorescence intensity ratio temperature sensing methods are not applicable to higher temperature ranges (500K-800K) because both fluorescence beams involved will experience severe thermal quenching. This embodiment overcomes this limitation and has the following advantages:

[0034] 1. Sm involved in this embodiment 3+The red light of the quartz crystal only shows very weak attenuation as the temperature rises, and can still maintain 80% of the room temperature even at 803K, which has a strong resistance to thermal quenching effect; the Tb 3+ The green light gradually increases with increasing temperature, up to 76 times. This ensures an excellent signal-to-noise ratio between the two fluorescence beams. Conventional fluorescence intensity ratio temperature measurement, however, is inapplicable because the two fluorescence beams decay to almost zero at 803K.

[0035] 2. Tb involved in this embodiment 3+ Green light and Sm 3+ The red light has different temperature responses, Tb 3+ The green light of the ion at 545nm increases rapidly with temperature to ensure excellent relative sensitivity, so Tb 3+ Green light and Sm 3+ The intensity ratio of the red light can reflect the temperature change in time, which ensures good relative sensitivity. Together with the excellent signal-to-noise ratio, the Sm-based 3+ / Tb 3+ The temperature resolution of the luminescence ratio temperature sensing method is still better than 1K at 803K.

[0036] 3. The applicable temperature range of this embodiment is 303K to 803K, and it can be used in a wider temperature range.

[0037] Specific embodiment 2: This embodiment differs from the specific embodiment 1 in that: Tb in step 1 3+ and Sm 3+ Tb in doped CaWO4 3+ The molar percentage of ions is 10%; the Tb 3+ and Sm 3+ Sm in doped CaWO4 3+ The molar percentage of ions is 1.5%. Other aspects are the same as those in the first embodiment.

[0038] Specific embodiment 3: This embodiment differs from either specific embodiment 1 or 2 in that: Tb in step 1 3+ and Sm 3+ The doped CaWO4 is prepared by a high-temperature solid-phase method. Other aspects are the same as those of the first or second embodiment.

[0039] Specific embodiment 4: This embodiment differs from any one of the specific embodiments 1 to 3 in that: Tb in step 1 3+ and Sm 3+ The doping of CaWO4 is specifically carried out in the following steps:

[0040] 1. Weigh CaO, WO3, Sm2O3 and Tb4O7 as raw materials according to the stoichiometric ratio, then put the raw materials into an agate crucible and grind them evenly to obtain a mixture;

[0041] 2. The mixture is heated to 770K~780K at a heating rate of 4K / min~6K / min, and kept at 770K~780K for 0.5h~1.5h. Then, the mixture is heated to 1500K~1600K at a heating rate of 4K / min~6K / min, and kept at 1500K~1600K for 5h~10h to obtain Tb 3+ and Sm 3+ Doped CaWO4. Other aspects are the same as those in the first to third embodiments.

[0042] Specific embodiment 5: This embodiment differs from any one of specific embodiments 1 to 4 in that: Tb in step 1 3+ and Sm 3+ The crystal phase of the doped CaWO4 is tetragonal. Other aspects are the same as those of the first to fourth embodiments.

[0043] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the particle size of the temperature-sensitive material in step 1 is 1 micron to 10 microns. Other aspects are the same as specific embodiments 1 to 5.

[0044] Specific embodiment 7: This embodiment differs from one of specific embodiments 1 to 6 in that, in step 2, a temperature-sensitive material is heated using a hot and cold stage to achieve different calibration temperatures. The different calibration temperatures range from 303K to 803K, and the temperature interval between adjacent calibration temperatures is 50K. Other aspects are the same as specific embodiments 1 to 6.

[0045] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that each calibration temperature in step 2 is kept warm for 3 minutes. Other aspects are the same as specific embodiments 1 to 7.

[0046] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that: Tb in step 2 and step 3 3+ The green light at 545nm comes from Tb 3+ of 5 D4→ 7 F5 jump, Sm 3+ The red light at 648 nm comes from Sm 3+ of 4 G5 / 2→ 6 H 9 / 2 Other aspects are the same as those of the first to eighth embodiments.

[0047] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the fitting curve is obtained after processing using the least squares method in step 2. The rest is the same as specific embodiments 1 to 9.

[0048] The following examples are used to verify the beneficial effects of the present invention:

[0049] Example 1:

[0050] A ratiometric temperature sensing method based on Sm ion / Tb ion luminescence is carried out in the following steps:

[0051] 1. Preparation of temperature-sensitive materials:

[0052] Preparation of Tb 3+ and Sm 3+ Doped CaWO4 to obtain temperature-sensitive materials;

[0053] 2. Determination of the functional relationship between the fluorescence intensity ratio A / B and temperature:

[0054] The temperature sensitive material was excited by a laser with a power of 100 mW and a wavelength of 405 nm, and the emission spectrum of the temperature sensitive material at different calibration temperatures was recorded by a spectrometer; the Tb 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red fluorescence band at the ion center wavelength of 648nm is integrated and recorded as fluorescence intensity B. The ratio of fluorescence intensity A to fluorescence intensity B is calculated, A / B. A fluorescence intensity ratio A / B is obtained at each calibration temperature. The fitting curve is obtained after processing using the least squares principle. According to the fitting curve, the functional relationship between the fluorescence intensity ratio A / B and temperature is obtained:

[0055] A / B = -0.06173 + 4.91 × 10 -4 ×T-1.29×10 -6 ×T 2 +1.13×10 -9 ×T 3 , where T is the absolute temperature;

[0056] 3. Ambient temperature detection:

[0057] The temperature sensitive material is placed in the test environment, and then the temperature sensitive material is excited by a laser with a power of 100 mW and a wavelength of 405 nm. The emission spectrum of the temperature sensitive material is collected by a spectrometer, and the Tb 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+The red light fluorescence band with the central wavelength of the ion at 648nm is integrated; the ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated, and the ratio A / B is substituted into the functional relationship obtained in step 2. T is calculated as the ambient temperature, and the ratio temperature sensing method based on the luminescence of Sm ions / Tb ions is completed.

[0058] Tb described in step 1 3+ and Sm 3+ Tb in doped CaWO4 3+ The molar percentage of ions is 10%; the Tb 3+ and Sm 3+ Sm in doped CaWO4 3+ The molar percentage of ions is 1.5%.

[0059] Tb described in step 1 3+ and Sm 3+ Doped CaWO4 is prepared by a high-temperature solid-phase method as follows:

[0060] 1. Weigh CaO, WO3, Sm2O3 and Tb4O7 as raw materials according to the stoichiometric ratio, then put the raw materials into an agate crucible and grind them evenly to obtain a mixture;

[0061] Second, the mixture is heated to 773K at a heating rate of 5K / min, and kept at 773K for 1h. Then, the mixture is heated to 1523K at a heating rate of 5K / min, and kept at 1523K for 8h to obtain Tb 3+ and Sm 3+ Doped CaWO4.

[0062] Tb described in step 1 3+ and Sm 3+ The crystal phase of doped CaWO4 is tetragonal.

[0063] The average particle size of the temperature sensitive material in step 1 is 5 microns.

[0064] In step 2, the temperature-sensitive material is heated using a hot and cold stage to achieve different calibration temperatures. The range of different calibration temperatures is 303K to 803K, and the temperature interval between adjacent calibration temperatures is 50K. Each calibration temperature is kept warm for 3 minutes.

[0065] Tb in step 2 and step 3 3+ The green light at 545nm comes from Tb 3+ of 5 D4→ 7 F5 jump, Sm 3+ The red light at 648 nm comes from Sm 3+of 4 G5 / 2→ 6 H 9 / 2 jump.

[0066] Figure 1 The XRD diffraction results of the temperature-sensitive material prepared in step 1 of Example 1 are shown. It can be seen that the diffraction peaks of the sample correspond to the standard peak positions, indicating that Tb 3+ and Sm 3+ Doped CaWO4 was successfully prepared and has a tetragonal crystal structure.

[0067] Figure 2 The emission spectrum of the temperature sensitive material prepared in step 1 of Example 1 in the range of 303K to 803K, with an excitation wavelength of 405nm and a temperature interval of 50K. As can be seen from the figure, under the excitation of 405nm laser, CaWO4:10%Tb 3+ ,1.5%Sm 3+ The emission spectrum of phosphor in the temperature range of 303K to 803K mainly consists of two parts: the first part is the emission peak at 545nm, which comes from Tb 3+ of 5 D4→ 7 The second part is the three emission peaks at 562nm, 602nm and 648nm, respectively, from Sm 3+ of 4 G 5 / 2 → 6 H 5 / 2 、 4 G 5 / 2 → 6 H 7 / 2 and 4 G5 / 2→ 6 H 9 / 2 As the temperature rises, the green light at 545nm increases sharply to 76 times the initial value, while the red light at 648nm only experiences a slight thermal quenching, and even at 803K it can still maintain 80% of the room temperature.

[0068] Figure 3 The intensity ratio of 545nm green light to 648nm red light of the temperature sensitive material prepared in step 1 of Example 1 varies in the range of 303K to 803K, with a temperature variation interval of 50K. At each temperature, the intensity ratio of Tb 3+ The green light intensity of the ion at 545 nm is integrated and recorded as A. 3+ The red light intensity of the ion at 648nm is integrated and recorded as B. By dividing these two intensities, the corresponding fluorescence intensity ratio A / B can be obtained. The change pattern of these ratios with temperature is as follows Figure 3 As shown, the temperature information can be inferred by monitoring this ratio.

[0069] Figure 4 For Example 1 based on Sm 3+ / Tb 3+ The variation of the relative sensitivity of the luminescence ratio temperature sensing method in the range of 303K to 803K; the relative sensitivity of this method is the highest at 473K, reaching 1.67%K. -1 At the same time, the relative sensitivity in the high temperature range of 500K~803K is better than 0.5%K -1 The traditional use of Er 3+ of 2 H 11 / 2 → 4 I 15 / 2 and 4 S 3 / 2 → 4 I 15 / 2 The relative sensitivity of the fluorescence intensity ratio temperature measurement method of the transition is only 0.15% K at 803 K. -1 , and Er 3+ of 2 H 11 / 2 → 4 I 15 / 2 and 4 S 3 / 2 → 4 I 15 / 2 The intensity of the transition at 803K is almost undetectable and therefore no longer applicable. This embodiment effectively solves this defect.

[0070] Figure 5 For Example 1 based on Sm 3+ / Tb 3+ The variation of temperature resolution of the luminescence ratio temperature sensing method in the range of 303K to 803K. 3+ / Tb 3+ The temperature resolution of the luminescence ratio temperature sensing method is better than 1K in the high temperature range of 500K to 803K (the resolution is less than 1K).

Claims

1. A ratiometric temperature sensing method based on Sm ion / Tb ion luminescence, characterized in that It is carried out in the following steps:

1. Preparation of temperature-sensitive materials: Preparation of Tb 3+ and Sm 3+ Doped CaWO4 to obtain temperature-sensitive materials; The Tb 3+ and Sm 3+ Tb in doped CaWO4 3+ The molar percentage of ions is 10%; the Tb 3+ and Sm 3+ Sm in doped CaWO4 3+ The molar percentage of ions is 1.5%; 2. Determination of the functional relationship between the fluorescence intensity ratio A / B and temperature: The temperature sensitive material is excited by a laser with a wavelength of 405nm, and the emission spectrum of the temperature sensitive material at different calibration temperatures is recorded by a spectrometer. The range of different calibration temperatures is 303K~803K; the Tb 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red fluorescence band at the central wavelength of the ion is located at 648nm and is integrated, which is recorded as the fluorescence intensity B. The ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated. A fluorescence intensity ratio A / B is obtained at each calibration temperature. After processing, a fitting curve is obtained. According to the fitting curve, the functional relationship between the fluorescence intensity ratio A / B and temperature is obtained: A / B = -0.06173 + 4.91 × 10 -4 ×T-1.29×10 -6 ×T 2 +1.13×10 -9 ×T 3 , where T is the absolute temperature; 3. Ambient temperature detection: The temperature sensitive material is placed in the test environment, and then the temperature sensitive material is excited by a laser with a wavelength of 405nm. The emission spectrum of the temperature sensitive material is collected by a spectrometer, and the Tb 3+ The green fluorescence band with the central wavelength of the ion at 545nm is integrated and recorded as the fluorescence intensity A; record Sm 3+ The red light fluorescence band with the central wavelength of the ion at 648nm is integrated; the ratio A / B of the fluorescence intensity A to the fluorescence intensity B is calculated, and the ratio A / B is substituted into the functional relationship obtained in step 2. T is calculated as the ambient temperature, and the ratio temperature sensing method based on the luminescence of Sm ions / Tb ions is completed.

2. A temperature sensing method based on the ratio of Sm ion / Tb ion luminescence according to claim 1, characterized in that Tb described in step 1 3+ and Sm 3+ Doped CaWO4 was prepared by a high-temperature solid-phase method.

3. A temperature sensing method based on the ratio of Sm ion / Tb ion luminescence according to claim 2, characterized in that Tb described in step 1 3+ and Sm 3+ The doping of CaWO4 is specifically carried out in the following steps:

1. Weigh CaO, WO3, Sm2O3 and Tb4O7 as raw materials according to the stoichiometric ratio, then put the raw materials into an agate crucible and grind them evenly to obtain a mixture; 2. The mixture is heated to 770K~780K at a heating rate of 4K / min~6K / min, and kept at 770K~780K for 0.5h~1.5h. Then, the mixture is heated to 1500K~1600K at a heating rate of 4K / min~6K / min, and kept at 1500K~1600K for 5h~10h to obtain Tb 3+ and Sm 3+ Doped CaWO4.

4. A temperature sensing method based on the ratio of Sm ion / Tb ion luminescence according to claim 3, characterized in that Tb described in step 1 3+ and Sm 3+ The crystal phase of doped CaWO4 is tetragonal.

5. The method of temperature sensing based on the ratio of Sm ion / Tb ion luminescence according to claim 1, characterized in that The particle size of the temperature sensitive material described in step 1 is 1 micron to 10 microns.

6. The method of temperature sensing based on the ratio of Sm ion / Tb ion luminescence according to claim 1, characterized in that In step 2, the temperature sensitive material is heated by a hot and cold stage to achieve different calibration temperatures, and the temperature interval between adjacent calibration temperatures is 50K.

7. A temperature sensing method based on the ratio of Sm ion / Tb ion luminescence according to claim 6, characterized in that In step 2, keep each calibration temperature for 3 minutes.

8. The method of temperature sensing based on the ratio of Sm ion / Tb ion luminescence according to claim 1, characterized in that Tb in step 2 and step 3 3+ The green light at 545nm comes from Tb 3+ of 5 D4→ 7 F5 jump, Sm 3+ The red light at 648 nm comes from Sm 3+ of 4 G5 / 2→ 6 H 9 / 2 jump.

9. The method of temperature sensing based on the ratio of Sm ion / Tb ion luminescence according to claim 1, characterized in that In step 2, the fitting curve is obtained by processing using the least squares method.

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