KNN-based transparent ceramic for high-sensitivity optical temperature measurement as well as preparation method and application of KNN-based transparent ceramic

Abstract

The invention discloses a high-sensitivity KNN-based transparent ceramic for optical temperature measurement and a preparation method and application thereof. The chemical composition of the ceramic is (1-x) K0. 5Na0. 5NbO3-xCaTiO3: yPr, wherein x is equal to 0.1 to 0.3, and y is equal to 0.05 percent to 3 percent. The ceramic sample provided by the invention is excited by a 332-360nm ultraviolet light source to generate blue light at the wavelength of 560nm (3P0 to 3H5) and red light at the wavelength of 610nm (1D2 to 3H4). The fluorescence intensity ratio (3P0-3H5 / 1D2-3H4) of the two emission peaks and the temperature show an exponential function relationship, the temperature can be calibrated, the temperature-sensitive performance is good, and CIE color coordinates change obviously along with the temperature. In addition, the ceramic also has relatively high light transmittance, the light transmittance in a visible region can reach 64%, and the light transmittance in a near-infrared region can reach 73%.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescence temperature sensing, and particularly relates to a KNN-based transparent ceramic for high-sensitivity optical temperature measurement, a preparation method thereof, and an application thereof. Background Art

[0002] The accurate measurement of temperature plays a crucial role in many fields such as industrial production, the electronics industry, scientific research, aerospace, and national defense construction. Among numerous temperature measurement technologies, the optical temperature measurement technology based on the fluorescence intensity ratio (FIR) in phosphor materials has received extensive attention due to its advantages such as non-contact measurement, fast response, high spatial resolution, and temperature resolution, which is helpful for temperature detection in harsh environments or fast-moving objects, and thus has rapidly become a research hotspot in the field of temperature detection.

[0003] The KNN-based transparent ceramic devices prepared by pressing show excellent performance, high Curie temperature, good ferroelectric and piezoelectric properties, and exhibit broad potential in optoelectronic functional materials. Traditional research on temperature measurement materials mainly focuses on the thermal coupling energy level pairs (TCLs) of rare earth ions, such as Nd 3+ of 4 F 7 / 2 and 4 F 3 / 2 energy levels. In these systems, since the overall changes in the upper and lower levels are opposite as the temperature increases, it is challenging to enhance both the absolute sensitivity and the relative sensitivity simultaneously. However, the requirements for high detection sensitivity, spatial resolution, and fast response in extreme environments impose extremely high demands on non-contact temperature sensors. Therefore, there is still a large room for improvement in the non-contact temperature sensors prepared by the existing technologies. Summary of the Invention

[0004] To solve the drawbacks and deficiencies of the existing technologies, the primary object of the present invention is to provide a KNN-based transparent ceramic for high-sensitivity optical temperature measurement.

[0005] Another object of the present invention is to provide a preparation method of a KNN-based transparent ceramic for high-sensitivity optical temperature measurement.

[0006] Another object of the present invention is to provide an application of the above-mentioned KNN-based transparent ceramic for high-sensitivity optical temperature measurement.

[0007] The objects of the present invention are achieved by the following technical solutions:

[0008] A KNN-based transparent ceramic for high-sensitivity optical temperature measurement, whose chemical composition is (1-x)K 0.5 Na 0.5 NbO3-xCaTiO3:yPr, where x = 0.1 - 0.3 and y = 0.05% - 3%.

[0009] Preferably, x = 0.3 and y = 0.1%.

[0010] A preparation method of a KNN-based transparent ceramic for high-sensitivity optical temperature measurement, comprising the following steps:

[0011] (1) Weigh the raw materials according to the chemical composition, then mix the raw materials and perform ball milling. After the ball milling is completed, filter out the mixture in the ball milling tank and dry it;

[0012] (2) Calcinate the dried slurry at 800 - 900 °C for 2 - 6 h;

[0013] (3) Ball mill or grind the calcined powder again. After completion, dry and screen the powder, and then put it into a tablet pressing mold for preliminary tablet pressing and forming;

[0014] (4) Adopt cold isostatic pressing to press the preliminarily formed sample again to make the ceramic sheet more dense;

[0015] (5) Sinter the pressed material at 1180 - 1240 °C for 2 - 4 h, and then cool it with the furnace to obtain the KNN-based transparent ceramic for high-sensitivity optical temperature measurement.

[0016] Preferably, in step (1), the raw materials are high-purity K2CO3 (purity ≥ 99.5%), Na2CO3 (purity ≥ 99.8%), Nb2O5 (purity ≥ 99.5%), CaCO3 (purity ≥ 99%), TiO2 (purity ≥ 99.8%) and Pr6O 11 (purity ≥ 99.9%).

[0017] Preferably, the ball milling in step (1) means putting the mixed raw material powder into a ball milling tank, adding anhydrous ethanol and agate beads with the same mass as the mixed powder, and finally putting the ball milling tank into a planetary ball mill to ball mill the mixture; the ball milling time is 6 - 24 h (more preferably 12 h); the ball milling speed is preferably 250 r / min.

[0018] Preferably, the drying in step (1) is drying at 70 - 120 °C for 2 - 4 h, more preferably drying at 80 °C for 3 h.

[0019] Preferably, the calcination in step (2) is calcination at 850 °C for 4 h.

[0020] Preferably, the ball milling time in step (3) is 6 - 24 h (more preferably 12 h); the ball milling speed is preferably 250 r / min.

[0021] Preferably, the drying in step (3) is drying at 70 - 120 °C for 2 - 4 h, more preferably drying at 80 °C for 3 h; the sieving means sieving through a 120-mesh sieve.

[0022] Preferably, in step (4), it is pressed again under a pressure of 200 MPa, and the pressure holding time is preferably 15 min.

[0023] Preferably, the heating rate during the sintering in step (5) is 10 °C / min.

[0024] Preferably, the sintering in step (5) is carried out at 1220 °C for 2 h.

[0025] The present invention also provides an application of the above-mentioned KNN-based transparent ceramic for high-sensitivity optical temperature measurement in temperature sensing.

[0026] In the said application, the fluorescence temperature measurement material is excited by ultraviolet light of 332 - 360 nm, and the ratio of the emission peak intensity at ~560 nm and the emission peak intensity at ~610 nm of the material is measured, which is the calibrated temperature.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1) The fluorescence ceramic sample of the present invention generates blue luminescence located at ~560 nm ( 3 P0→ 3 H5) and red luminescence located at ~610 nm ( 1 D2→ 3 H4) under the excitation of a 332 - 360 nm ultraviolet light source. In the range of 300 - 500 K, the fluorescence intensity ratio ( 3 P0→ 3 H5 / 1 D2→ 3 H4) of the material has an exponential function relationship with temperature, can be used to calibrate temperature, and the positions of these two emission peaks are relatively wide apart, having excellent signal discrimination.

[0029] 2) The fluorescence temperature measurement ceramic has both high light transmittance and certain relaxor ferroelectricity. Under the combined action of two structures that are extremely sensitive to temperature, namely polar nano microdomains and valence interval charge transfer states, a high optical temperature measurement sensitivity is obtained. In the range of 300 - 460 K, the absolute sensitivity can reach 0.104 K -1 , and the relative sensitivity can reach 2.69% K -1 ~3.75% K -1 , and the CIE coordinates change significantly with temperature, having ultra-high signal resolution and great application potential in the field of optical temperature measurement. Description of the Drawings

[0030] Figure 1 It is the XRD pattern of the fluorescence temperature measurement ceramic prepared in Example 1 of the present invention;

[0031] Figure 2 SEM image of the fluorescence temperature - measuring ceramic (y = 0.01) prepared in Example 1 of the present invention;

[0032] Figure 3 Transmission spectrum of the fluorescence temperature - measuring ceramic prepared in Example 1 of the present invention. In the figure, 0.175CT represents the ceramic sample prepared when y = 0, and 0.001Pr, 0.005Pr, 0.01Pr, 0.03Pr represent the ceramic samples prepared when y = 0.001, y = 0.005, y = 0.01, and y = 0.03 respectively;

[0033] Figure 4 Excitation and emission spectra of the fluorescence temperature - measuring ceramic prepared in Example 1 of the present invention. Among them, (a) is the excitation spectrum measured at 610 nm for the ceramic, and (b) is the emission spectrum measured under the excitation of 332 nm for the ceramic. In the figure, 0.175CT represents the ceramic sample prepared when y = 0, and 0.001, 0.005, 0.01, 0.03 represent the ceramic samples prepared when y = 0.001, y = 0.005, y = 0.01, and y = 0.03 respectively;

[0034] Figure 5 Emission spectra of the fluorescence ceramic temperature - measuring ceramic (y = 0.01) prepared in Example 1 of the present invention at different temperatures;

[0035] Figure 6 Spectrum of experimental and fitting data of the fluorescence intensity ratio of the fluorescence temperature - measuring material prepared in Example 1 of the present invention (y = 0.01);

[0036] Figure 7 Relative (absolute) temperature sensitivity spectrum of the fluorescence temperature - measuring ceramic prepared in Example 1 of the present invention (y = 0.01);

[0037] Figure 8 XRD spectrum of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention;

[0038] Figure 9 SEM image of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention (y = 0.001);

[0039] Figure 10 Transmission spectrum of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention. In the figure, 0.3CT represents the ceramic sample prepared when y = 0, and 0.001Pr, 0.005Pr, 0.01Pr, 0.03Pr represent the ceramic samples prepared when y = 0.001, y = 0.005, y = 0.01, and y = 0.03 respectively;

[0040] Figure 11This is the excitation and emission spectra of the fluorescence temperature - measuring ceramics prepared in Example 2 of the present invention. Among them, (a) is the excitation spectrum measured at 610 nm for the ceramics, and (b) is the emission spectrum measured under 360 nm excitation for the ceramics; in the figure, 0.3CT represents the ceramic sample prepared when y = 0, and 0.001, 0.005, 0.01, and 0.03 respectively represent the ceramic samples prepared when y = 0.001, y = 0.005, y = 0.01, and y = 0.03.

[0041] Figure 12 This is the emission spectrum of the fluorescence temperature - measuring ceramics prepared in Example 2 of the present invention at different temperatures (y = 0.001).

[0042] Figure 13 This is the experimental and fitting data spectrum of the fluorescence intensity ratio of the fluorescence temperature - measuring material prepared in Example 2 of the present invention (y = 0.001).

[0043] Figure 14 This is the relative (absolute) temperature sensitivity spectrum of the fluorescence temperature - measuring ceramics prepared in Example 2 of the present invention (y = 0.001). Detailed implementation mode

[0044] The present invention will be further described in detail below in conjunction with examples and drawings, but the implementation modes of the present invention are not limited thereto. The raw materials involved in the present invention can be directly purchased from the market. For the process parameters not specifically noted, conventional techniques can be referred to.

[0045] Example 1

[0046] A rapid preparation method for high - sensitivity optical temperature - measuring KNN transparent ceramics includes the following steps:

[0047] (1) Weigh the drug powders of K2CO3 (99.5%), Na2CO3 (99.8%), Nb2O5 (99.5%), CaCO3 (99%), TiO2 (99.8%), and Pr6O 0.5 Na 0.5 (99.9%) according to the molar ratio of 0.825K 11 Na

[0048] (2) In a light - shielded environment, put the mixed powders into a ball - milling jar, add an appropriate amount of anhydrous ethanol and agate beads. Finally, put the ball - milling jar into a planetary ball mill to ball - mill the mixture at a speed of 250 r / min for 12 h.

[0049] (3) After ball - milling, sieve the mixture in the ball - milling jar and then put it into an oven to dry at 80 °C for 3 h.

[0050] (4) Put the dried powder into an alumina crucible and heat it in a conventional muffle furnace at a rate of 10 °C per minute to 850 °C, keep it for calcination for 4 h, and perform pre-calcination.

[0051] (5) Take out the pre-calcined sample, repeat steps (2)–(3) for secondary ball milling and drying, put the obtained powder into an agate mortar for grinding, and sieve the ground powder through a 120-mesh sieve.

[0052] (6) Press the sieved powder into a disc shape with a diameter of 10 mm using a dry press.

[0053] (7) Press the preliminarily pressed sample more tightly by a cold isostatic press. The pressure applied by the press to the powder is 200 MPa, and the pressure holding time is 15 min.

[0054] (8) Put the sample into a muffle furnace and heat it at a heating rate of 10 °C / min to 1200 °C, keep it for 2 h, and then cool it naturally to obtain the required ceramic sample 0.825K 0.5 Na 0.5 NbO3-0.175CaTiO3-0.01Pr.

[0055] (9) Referring to the above steps (1)–(8), change y in the chemical composition described in step (1) to 0, 0.001, 0.005, and 0.03 respectively, and keep the other parameters unchanged, and prepare ceramic samples 0.825K 0.5 Na 0.5 NbO3-0.175CaTiO3, 0.825K 0.5 Na 0.5 NbO3-0.175CaTiO3-0.001Pr, 0.825K 0.5 Na 0.5 NbO3-0.175CaTiO3-0.005Pr, 0.825K 0.5 Na 0.5 NbO3-0.175CaTiO3-0.03Pr.

[0056] Figure 1 This is the XRD pattern of the fluorescence temperature-measuring ceramic prepared in Example 1 of the present invention. It can be seen from the figure that the XRD peak positions indicate that a small amount of Pr doping does not form a new phase, and all are pseudo-cubic phases;

[0057] Figure 2 This is the SEM image of the fluorescence temperature-measuring ceramic (y = 0.01) prepared in Example 1 of the present invention. It can be seen from the particle size distribution that the average particle size of the ceramic is in the sub-micron structure and has a high density, which is beneficial to the light transmittance of the ceramic;

[0058] Figure 3 This is the transmission spectrum of the fluorescence temperature - measuring ceramic prepared in Example 1 of the present invention. In the figure, 0.175CT represents the ceramic sample prepared when y = 0, and 0.001Pr, 0.005Pr, 0.01Pr, and 0.03Pr respectively represent the ceramic samples prepared when y = 0.001, y = 0.005, y = 0.01, and y = 0.03. It can be seen from the figure that the light transmittance of the ceramic sample in the visible light region (780 nm) can reach up to about 50%, and the transmittance in the near - infrared region (1336 nm) can reach up to about 76%.

[0059] Figure 4 This is the excitation and emission spectrum of the fluorescence temperature - measuring ceramic prepared in Example 1 of the present invention. Among them, (a) is the excitation spectrum measured at 610 nm for the ceramic, and there are two main excitation peaks in the figure, with the peak intensity of 332 nm being the highest; (b) is the emission spectrum measured under the excitation of 332 nm for the ceramic, and there are two emission peaks in the spectrum 3 P0→ 3 H5, 1 D2→ 3 H4;

[0060] Figure 5 This is the emission spectrum of the fluorescence ceramic temperature - measuring ceramic (y = 0.01) prepared in Example 1 of the present invention at different temperatures. It can be seen from the figure that as the temperature increases, 1 D2→ 3 the emission peak intensity of H4 drops rapidly, 3 P0→ 3 the emission peak of H5 drops slowly, indicating that 1 D2→ 3 the emission peak of H4 is very sensitive to temperature;

[0061] Figure 6 This is the experimental and fitting data spectrum of the fluorescence intensity ratio of the fluorescence temperature - measuring material prepared in Example 1 of the present invention (y = 0.01); It can be seen from the figure that the experimental data is in good agreement with the fitting curve;

[0062] Figure 7 This is the relative (absolute) temperature sensitivity spectrum of the fluorescence temperature - measuring ceramic prepared in Example 1 of the present invention (y = 0.01); It can be seen from the figure that the relative sensitivity reaches the highest value of 2.69% K at about 360 K -1 .

[0063] Example 2

[0064] A rapid preparation method for a high - sensitivity optical temperature - measuring KNN transparent ceramic, comprising the following steps:

[0065] (1) According to 0.7K 0.5 Na0.5 Weigh the drugs K2CO3 (99.5%), Na2CO3 (99.8%), Nb2O5 (99.5%), CaCO3 (99%), TiO2 (99.8%) and Pr6O 11 (99.9%) powders according to the molar ratio of NbO3 - 0.3CaTiO3 - 0.001Pr, and mix the weighed powders together.

[0066] (2) Under a light - shielded environment, put the mixed powders into a ball - milling jar, add anhydrous ethanol and agate beads with the same mass as the mixed powders. Finally, put the ball - milling jar into a planetary ball mill to ball - mill the mixture at a rotation speed of 250 r / min for 12 h.

[0067] (3) After the ball - milling is completed, screen the mixture in the ball - milling jar and then put it into an oven to dry at 80 °C for 3 h.

[0068] (4) Put the dried powder into an alumina crucible, and use a conventional muffle furnace to heat it at a rate of 10 °C per minute to 850 °C, and keep it calcined for 4 h for pre - calcination.

[0069] (5) Take out the pre - calcined sample, repeat steps (2) - (3) for secondary ball - milling and drying, put the obtained powder into an agate mortar for grinding, and screen the ground powder through a 120 - mesh sieve.

[0070] (6) Press the sieved powder into a disc with a diameter of 10 mm using a dry press.

[0071] (7) Press the preliminarily pressed sample more tightly through a cold isostatic press. The pressure applied by the press to the powder is 200 MPa, and the pressure - holding time is 15 min.

[0072] (8) Put the sample into a muffle furnace and heat it at a heating rate of 10 °C / min to 1220 °C, keep it for 2 h, and then cool it naturally to obtain the required ceramic sample 0.7K 0.5 Na 0.5 NbO3 - 0.3CaTiO3 - 0.001Pr.

[0073] (9) Refer to steps (1) - (8) above, change y in the chemical composition described in step (1) to 0, 0.005, 0.01 and 0.03 respectively, keep the other parameters unchanged, and prepare ceramic samples 0.7K 0.5 Na 0.5 NbO3 - 0.3CaTiO3, 0.7K 0.5 Na 0.5 NbO3 - 0.3CaTiO3 - 0.005Pr, 0.7K 0.5 Na 0.5NbO3 - 0.3CaTiO3 - 0.01Pr, 0.7K 0.5 Na 0.5 NbO3 - 0.3CaTiO3 - 0.03Pr.

[0074] Figure 8 XRD spectrum of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention; as can be seen from the figure, the XRD peak positions indicate that a small amount of Pr doping does not form a new phase, and all are pseudo - cubic phases;

[0075] Figure 9 SEM image of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention (y = 0.001); it can be seen from the particle size distribution that the average particle size of the ceramic is in the sub - micron structure and has a high density, which is beneficial to the light - transmission performance of the ceramic;

[0076] Figure 10 Transmission spectrum of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention. In the figure, 0.3CT represents the ceramic sample prepared when y = 0, and 0.001Pr, 0.005Pr, 0.01Pr, 0.03Pr represent the ceramic samples prepared when y = 0.001, y = 0.005, y = 0.01, and y = 0.03 respectively; as can be seen from the figure, the light - transmittance of the ceramic sample in the visible light region (780 nm) can reach up to about 50%, and the transmittance in the near - infrared region (1336 nm) can reach up to about 78%;

[0077] Figure 11 Excitation and emission spectra of the fluorescence temperature - measuring ceramic prepared in Example 2 of the present invention. Among them, (a) is the excitation spectrum measured at 610 nm for the ceramic, and there are two main excitation peaks in the figure, and the peak intensity of 360 nm is the highest; (b) is the emission spectrum measured under the excitation of 360 nm for the ceramic, and there are two emission peaks in the spectrum, 3 P0→ 3 H5, 1 D2→ 3 H4;

[0078] Figure 12 Emission spectra of the fluorescence ceramic temperature - measuring ceramic prepared in Example 2 of the present invention at different temperatures (y = 0.001); as can be seen from the figure, as the temperature increases, 1 D2→ 3 the intensity of the H4 emission peak drops rapidly, 3 P0→ 3 the H5 emission peak drops slowly, indicating that 1 D2→ 3 the H4 emission peak is very sensitive to temperature;

[0079] Figure 13Experimental and fitting data spectrogram of the fluorescence intensity ratio of the fluorescence temperature measurement material prepared in Example 2 of the present invention (y = 0.001); as can be seen from the figure, the experimental data and the fitting curve are in good agreement in the range of 300 - 460K;

[0080] Figure 14 Relative (absolute) temperature sensitivity spectrogram of the fluorescence temperature measurement ceramic prepared in Example 2 of the present invention (y = 0.001), as can be seen from the figure, the relative sensitivity reaches the highest value of 3.75%K at about 300K -1 .

[0081] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A KNN-based transparent ceramic for high-sensitivity optical temperature measurement, characterized in that, Its chemical composition is (1-x)K 0.5 Na 0.5 NbO3-xCaTiO3:yPr, where x = 0.1 - 0.3 and y = 0.05% - 3%.

2. The KNN-based transparent ceramic for high-sensitivity optical temperature measurement according to claim 1, characterized in that, Where x = 0.3 and y = 0.1%.

3. The preparation method of a KNN-based transparent ceramic for high-sensitivity optical temperature measurement according to claim 1 or 2, characterized in that, It includes the following steps: (1) Weigh the raw materials according to the chemical composition, then mix the raw materials and carry out ball milling. After the ball milling is completed, filter out the mixture in the ball milling tank and then dry it; (2) Calcinate the dried slurry at 800 - 900 °C for 2 - 6 h; (3) Ball mill or grind the calcined powder again. After completion, dry and sieve the powder, and then put it into a tablet pressing mold for preliminary tablet pressing and forming; (4) Adopt cold isostatic pressing to re-press the preliminarily pressed sample; (5) Sinter the pressed material at 1180 - 1240 °C for 2 - 4 h, and then cool it with the furnace to obtain the KNN-based transparent ceramic for high-sensitivity optical temperature measurement.

4. The preparation method according to claim 3, characterized in that, The raw materials described in step (1) are high-purity K2CO3, Na2CO3, Nb2O5, CaCO3, TiO2 and Pr6O 11 .

5. The preparation method according to claim 3, wherein The ball milling in step (1) means putting the mixed raw material powder into a ball milling tank, adding anhydrous ethanol and agate beads, and finally putting the ball milling tank into a planetary ball mill to ball mill the mixture; the ball milling time is 6 - 24 h; The drying in step (1) is drying at 70 - 120 °C for 2 - 4 h.

6. The preparation method according to claim 3, characterized in that, The calcination in step (2) is calcination at 850 °C for 4 h.

7. The preparation method according to claim 3, characterized in that, The ball milling time in step (3) is 6 - 24 h; The drying in step (3) is drying at 70 - 120 °C for 2 - 4 h.

8. The preparation method according to claim 3, characterized in that, In step (4), it is re-pressed under a pressure of 200 MPa.

9. The preparation method according to claim 3, characterized in that, The heating rate during sintering in step (5) is 10 °C / min; The sintering in step (5) is sintering at 1220 °C for 2 h.

10. Application of the KNN-based transparent ceramic for high-sensitivity optical temperature measurement according to claim 1 or 2 in temperature sensing.

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