Multiphase ceramic and preparation method and application thereof
The preparation of Cr3+ and Er3+ co-doped α-Al2O3/β-CaTa2O6 multiphase ceramics by glass-controlled crystallization method solves the problems of low sensitivity and narrow temperature measurement range of fluorescent materials at high temperatures, and achieves a wide temperature range and high sensitivity multi-parameter fluorescence thermometry effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-07
AI Technical Summary
Existing fluorescent materials have low sensitivity and narrow temperature measurement range at high temperatures. Traditional multiphase ceramic preparation processes are complex and it is difficult to achieve a non-porous and uniform structure, which cannot meet the requirements of wide temperature range and high sensitivity for multi-parameter fluorescence temperature measurement.
xα-Al2O3/(100-x)β-CaTa2O6:yCr2O3,zEr2O3 multiphase ceramics were prepared by a fully controllable glass crystallization method. A uniform polycrystalline structure was prepared under normal pressure by controlled heat treatment. Multi-parameter fluorescence thermometry was achieved by utilizing the fluorescence properties of Cr3+ and Er3+ ions.
High-sensitivity and high-resolution fluorescence thermometry was achieved in the range from room temperature to 573 K, with relative sensitivities all above 0.85% K⁻¹, a maximum relative sensitivity of 3.28% K⁻¹, and a temperature resolution of ~0.1 K.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of inorganic fluorescent materials, specifically to a multiphase ceramic with multiple parameters, high sensitivity and high resolution over a wide temperature range, its preparation method and application. Technical Background
[0002] Temperature is one of the fundamental physical quantities in thermodynamics, and its accurate measurement is of great significance in industrial production, biomedicine, and scientific research. Traditional temperature measurement techniques suffer from problems such as destructive measurement, limited temperature range, and insufficient accuracy, making it difficult to simultaneously achieve wide temperature range, high sensitivity, and non-destructive real-time temperature measurement. Fluorescence thermometry, however, effectively overcomes the shortcomings of traditional temperature measurement techniques due to its fast response, high sensitivity, and strong environmental adaptability. Its principle is based on the temperature-sensitive properties of fluorescent materials, such as fluorescence peak intensity, peak width, intensity ratio, and fluorescence lifetime. Among these, the temperature measurement method based on the fluorescence intensity ratio of thermally coupled energy levels is the most widely studied, but this method has limitations: overlapping fluorescence peaks lead to insufficient spectral resolution; and relative sensitivity decreases significantly at high temperatures. Therefore, obtaining greater sensitivity over a wide temperature range, especially at high temperatures, remains a challenge for the practical application of fluorescence thermometry.
[0003] Thermometry based on the fluorescence intensity ratio of non-thermally coupled energy levels can effectively reduce spectral overlap and improve spectral resolution by utilizing the thermosensitive properties of independent emission peaks. Furthermore, when one emission peak undergoes significant thermal quenching while the other remains stable or even intensifies, the resulting fluorescence intensity ratio changes dramatically with temperature, effectively enhancing thermometric sensitivity. However, fluorescent materials based on a single luminescent center rarely provide two non-thermally coupled fluorescence peaks with different thermosensitive fluorescence characteristics, and energy transfer between multiple luminescent centers easily leads to fluorescence quenching, making it impossible to obtain independent thermosensitive fluorescence signals. Therefore, from the perspective of thermosensitive fluorescent materials, designing and fabricating fluorescent materials with multiple independent luminescent centers is crucial for obtaining wide-temperature-range, high-sensitivity multi-parameter fluorescence thermometry.
[0004] Compared to quantum dots, organic fluorescent materials, rare-earth or transition metal ion-doped nanoparticles, glass, and glass-ceramics, ceramics with excellent thermal stability are more suitable for high-temperature detection. Multiphase ceramics obtained by combining two high-performance crystalline phases can provide multiple luminescent ion doping sites, offering an excellent doping matrix for wide-temperature-range, high-sensitivity multi-parameter fluorescence thermometry. However, traditional methods for preparing multiphase ceramics are complex, demanding on raw materials, prone to defects during molding, typically requiring high-temperature, high-pressure sintering, and often resulting in difficulty in completely eliminating pores and uneven grain size and distribution. Completely controllable crystallization of glass offers an alternative solution for ceramic preparation. Glass possesses tunable composition, excellent molding properties, and shape complexity. Through glass composition optimization and controlled crystallization, fine and uniform microstructures can be obtained, achieving pore-free or extremely low-porosity dense microstructures under ambient pressure. Therefore, it is necessary to provide a method for preparing multiphase ceramics through completely controllable glass crystallization that can effectively utilize the fluorescence properties of multiple functional crystalline phases to achieve wide-temperature-range, high-sensitivity multi-parameter fluorescence thermometry. Summary of the Invention
[0005] To address the issues of low high-temperature sensitivity and narrow temperature measurement range in existing fluorescent materials, this invention provides a multiphase ceramic, its preparation method, and its applications. The chemical formula of this multiphase ceramic is: x α-Al₂O₃ / (100- x β-CaTa2O6: y Cr2O3, z Er₂O₃, 51≤ x ≤59 mol%, 0< y ≤0.8 mol%, 0< z ≤2.0 mol%, prepared by a fully controllable glass crystallization method, with Cr simultaneously excited in the temperature range from room temperature to 573 K. 3+ and Er 3+ Different fluorescence temperature response characteristics of two doped ions can be obtained, realizing multi-parameter, high-sensitivity and high-resolution fluorescence thermometry in a wide temperature range.
[0006] The objective of this invention is achieved by at least one of the following technical solutions.
[0007] A multiphase ceramic, characterized in that its chemical formula is x α-Al₂O₃ / (100- x β-CaTa2O6: y Cr2O3, z Er₂O₃, where 51≤ x ≤59 mol%, 0< y ≤0.8 mol%, 0< z ≤2.0 mol%.
[0008] The method for preparing a multiphase ceramic, which employs a fully controllable glass crystallization method, includes the following steps: 1) Weigh the calcium source, tantalum source, aluminum source, chromium source and erbium source raw materials according to the stoichiometric ratio, and mix the raw materials evenly to obtain a powdered glass mixture; 2) Place the powdered glass mixture obtained in step 1) into a mold and press it into shape to obtain a sheet-like glass mixture; 3) Place the sheet glass mixture obtained in step 2) into a muffle furnace for pre-sintering to obtain a block glass mixture; 4) The block glass mixture obtained in step 3) is used to prepare a glass precursor by pneumatic suspension method; 5) The glass precursor obtained in step 4) is placed in a muffle furnace for heat treatment to obtain multiphase ceramic.
[0009] Furthermore, the calcium source is one of calcium oxide, carbonate, or hydroxide; the tantalum source is tantalum oxide; the aluminum source is one of aluminum oxide or hydroxide; the chromium source is trivalent chromium oxide; and the erbium source is erbium oxide.
[0010] Furthermore, the method for preparing a multiphase ceramic is characterized in that, in step 5), the heat treatment temperature is 1300-1400 ℃, the holding time is 2-10 h, and then it is slowly cooled to room temperature.
[0011] The application of the aforementioned multiphase ceramic in the field of fluorescence thermometry.
[0012] Furthermore, utilizing the aforementioned multiphase ceramic to bond Er 3+ and Cr 3+ The fluorescence intensity ratio is used for temperature detection. Further, the specific steps include: 1) Obtaining the temperature function: The multiphase ceramic was excited using a 375 nm light source. Fluorescence spectra in the 500-850 nm wavelength range were collected every 25 K from room temperature to 573 K. The Er... 3+ At 522 nm and 548 nm, Cr 3+ At 645 nm and 694 nm, Er 3+ At 522 nm and Cr 3+ At 694 nm, Cr 3+ At 645 nm and Er 3+ The fluorescence intensity ratio at 548 nm was fitted as a function of temperature to obtain the function of fluorescence intensity ratio changing with temperature. 2) Evaluation of temperature measurement performance: The composite ceramic is coupled with an optical fiber and placed in the test environment or on the surface of the object to be tested, and Er is measured. 3+ and Cr 3+The fluorescence intensity ratio described in step 1) is calculated and then substituted into the above-mentioned fitted temperature function to obtain the temperature of the environment or object to be tested.
[0013] Furthermore, the applicable temperature range for the multiphase ceramic is from room temperature to 573 K. Among these, the 55α-Al₂O₃ / 45β-CaTa₂O₆:0.4Cr₂O₃ and 0.5Er₂O₃ samples heat-treated at 1300 °C for 2 h exhibit negative thermal quenching characteristics within this temperature range, with relative sensitivities all around 0.85% K. -1 The maximum relative sensitivity is 3.28% K. -1 Temperature resolution can reach ~0.1 K.
[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1) The fluorescent thermosensitive material provided by this invention is a Cr 3+ Er 3+ An ion-co-doped α-Al₂O₃ / β-CaTa₂O₆ bicrystalline composite ceramic was prepared using a fully controllable glass crystallization method. This method allows for preparation under ambient pressure through a controlled heat treatment process, avoiding the extreme conditions of high temperature and high pressure required by traditional ceramic powder sintering, and also circumventing the two major challenges of porosity elimination and uniform grain growth. The average grain sizes of the α-Al₂O₃ and β-CaTa₂O₆ phases in this composite ceramic are 0.20 μm and 0.31 μm, respectively, and they are uniformly distributed and free of pores. Its bicrystalline structure provides diverse doping sites for activating ions. α-Al₂O₃ is a high-temperature stable corundum phase, while Al₂O₃... 3+ The site can be Cr 3+ Ion-occupied; β-CaTa₂O₆ is a high-temperature stable orthorhombic phase, Ca 2+ The site can be Er 3+ Ion occupation.
[0015] 2) Cr in this multiphase ceramic 3+ and Er 3+ The ions can be simultaneously excited by 375 nm near-ultraviolet light, emitting red and green light respectively, effectively reducing spectral overlap. Cr... 3+ Er 3+ Thermally coupled energy levels of ions (645 nm and 694 nm, 522 nm and 548 nm) and Cr 3+ and Er 3+Multi-parameter fluorescence thermometry is achieved by using the fluorescence intensity ratios of non-thermally coupled ion energy levels (522 nm and 694 nm, 645 nm and 548 nm). Its advantage lies in dividing the wide temperature range from room temperature to 573 K into different temperature segments based on the temperature range with higher relative sensitivity. Using the fluorescence intensity ratio corresponding to higher relative sensitivity within different operating temperature segments effectively improves the relative sensitivity across the entire temperature range. Specifically, the 55α-Al₂O₃ / 45β-CaTa₂O₆:0.4Cr₂O₃, 0.5Er₂O₃ samples heat-treated at 1300 ℃ for 2 h exhibited negative thermal quenching characteristics within the temperature range of room temperature to 573 K, effectively improving high-temperature spectral resolution, with relative sensitivities all around 0.85% K. -1 The maximum relative sensitivity is 3.28% K. -1 Temperature resolution can reach ~0.1 K. Attached Figure Description
[0016] Figures 1-6 The XRD patterns of the multiphase ceramics prepared in Examples 1-6 are shown below.
[0017] Figure 7 The images shown are TEM images and high-resolution TEM images of the multiphase ceramics prepared in Example 3, respectively.
[0018] Figure 8 The room temperature excitation and emission spectra of the multiphase ceramic prepared in Example 3 are shown.
[0019] Figure 9 The room temperature excitation and emission spectra of the multiphase ceramic prepared in Comparative Example 4 are shown.
[0020] Figure 10 The room temperature excitation and emission spectra of the multiphase ceramic prepared in Comparative Example 7 are shown.
[0021] Figures 11-16 The images show the temperature-varying emission spectra (a) and normalized temperature-varying emission spectra (b) of the multiphase ceramics prepared in Examples 1-6, respectively.
[0022] Figure 17 The integral intensity of fluorescence in the multiphase ceramics prepared in Examples 1-6 varies with temperature.
[0023] Figures 18-23 The figures shown are fitting diagrams of the multi-parameter fluorescence intensity ratios of the multiphase ceramics prepared in Examples 1-6, respectively.
[0024] Figures 24-29 The figures show the relative sensitivity curves of the multiphase ceramics prepared in Examples 1-6, respectively.
[0025] Figure 30 Temperature resolution curves for the multiphase ceramics prepared in Example 3.
[0026] Figure 31 The image shows the XRD pattern of the multiphase ceramic prepared in Example 7.
[0027] Figure 32 The room temperature emission spectrum of the multiphase ceramic prepared in Example 7 is shown.
[0028] Figure 33 The XRD pattern of the multiphase ceramic prepared in Example 8.
[0029] Figure 34 The room temperature emission spectrum of the multiphase ceramic prepared in Example 8.
[0030] Figure 35 The XRD pattern of the sample prepared for Comparative Example 1.
[0031] Figure 36 The room temperature emission spectrum of the sample prepared in Comparative Example 1 is shown.
[0032] Figures 37-42 The XRD patterns of the multiphase ceramics prepared in Comparative Examples 2-7 are shown.
[0033] Figure 43 and Figure 44 The temperature-varying emission spectra of the multiphase ceramics prepared in Comparative Example 4 and Comparative Example 7 are shown, respectively.
[0034] Figure 45 and Figure 46 The figures show the fitting plots of the single-parameter fluorescence intensity ratios of the multiphase ceramics prepared in Comparative Example 4 and Comparative Example 7, respectively.
[0035] Figure 47 and Figure 48 The relative sensitivity curves are for the multiphase ceramics prepared in Comparative Example 4 and Comparative Example 7, respectively.
[0036] Figure 49 The XRD pattern of the sample prepared for Comparative Example 8.
[0037] Figure 50 The room temperature emission spectrum of the sample prepared in Comparative Example 8 is shown. Detailed Implementation
[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.
[0039] Examples 1-6 preparation x α-Al₂O₃ / (100- xβ-CaTa2O6: y Cr2O3, z Er2O3 multiphase ceramics, the specific steps are as follows: 1) Weigh the calcium source, tantalum source, aluminum source, chromium source and erbium source raw materials according to the stoichiometric ratio shown in Table 1, place the raw materials in an agate mortar and mix them evenly to obtain a powdered glass mixture; 2) Place the powdered glass mixture obtained in step 1) into a mold and press it into shape to obtain a sheet-like glass mixture; 3) The sheet glass mixture obtained in step 2) is placed in a muffle furnace and pre-sintered at 1000 °C for 6 h to obtain a block glass mixture; 4) The block glass mixture obtained in step 3) is used to prepare a glass precursor by pneumatic suspension method; 5) Place the glass precursor obtained in step 4) in a muffle furnace and heat treat it at 1300 °C for 2 h, then slowly cool it to room temperature.
[0040] like Figure 1-6 As shown, XRD tests confirmed that only β-CaTa2O6 and α-Al2O3 precipitated in the samples heat-treated at 1300 ℃ for 2 h, indicating that Cr was obtained after heat treatment. 3+ and Er 3+ Co-doped α-Al₂O₃ / β-CaTa₂O₆ multiphase ceramics. For example... Figure 7 The TEM image shown is taken from the sample of Example 3. The comparison of the lattice fringes proves that the dark gray area is the β-CaTa2O6 crystal phase and the light gray area is the α-Al2O3 crystal phase. The two crystal phases are evenly distributed, with average grain sizes of 0.31 μm and 0.20 μm, respectively.
[0041] Room temperature steady-state fluorescence spectra (e.g.) Figure 8 As shown in the figure, under near-ultraviolet light excitation at 375 nm, Er 3+ and Cr 3+ The emission spectrum of the ion-co-doped multiphase ceramics exhibits three emission bands at 522 nm, 548 nm, and 694 nm. The first two emission bands are attributed to Er. 3+ Thermally Coupled Excited State of Ions 4 S 3 / 2 and 2 H 11 / 2 to ground state 4 I 15 / 2 The transition, the latter launch belt belongs to Cr 3+ Excited state of ions 2 E to ground state 4 The transition to A2. Among them, Cr 3+ The position and shape of the fluorescence peak are related to Cr 3+ Doped corundum single crystals or ceramics are similar, due to Cr3+ The near-infrared emission of ions is greatly influenced by the matrix crystal field, and this result further illustrates that in Cr... 3+ and Er 3+ The red emission peak in ion-co-doped multiphase ceramics originates from Cr. 3+ Ion-doped α-Al₂O₃. Cr 3+ and Er 3+ The fluorescence peaks of the ions showed virtually no overlap, effectively improving spectral resolution. Cr was monitored separately. 3+ and Er 3+ The emission of ions, its excitation spectrum and Cr 3+ Single doping (Comparative Example 4) or Er 3+ Excitation spectra of single-doped (Comparative Example 7) multiphase ceramics (respectively) Figure 9 and 10 Consistent with Cr indicates that 3+ and Er 3+ Ion co-doping has virtually no impact on the crystal field environment of the two activating ions.
[0042] Cr 3+ and Er 3+ Temperature-varying emission spectra and normalized temperature-varying emission spectra of ion-co-doped multiphase ceramics from room temperature to 573 K are as follows: Figure 11-16 As shown, a broad peak at 645 nm gradually appears with increasing temperature, which is attributed to Cr. 3+ Excited state of ions 4 T2 to ground state 4 The A2 transition, and 2 The E excited state is a pair of thermally coupled energy levels. Figure 17 The fluorescence integrated intensity of samples from Examples 1-6 varies with temperature. Samples from Examples 1, 2, and 3 all exhibit negative thermal quenching, meaning they are located at Er(522 nm). 3+ ion 4 S 3 / 2 The emission intensity of the energy level increases with increasing temperature, and Er is located at 548 nm. 3+ ion 2 H 11 / 2 The energy level emission intensity decreases with increasing temperature, particularly at Cr at 645 nm. 3+ ion 4 The emission intensity of the T2 energy level gradually increases with increasing temperature, and the Cr at 694 nm... 3+ ion 2 The emission intensity of the E level gradually decreases with increasing temperature. Generally, increasing temperature leads to an increased probability of nonradiative transitions in materials, which typically exhibit fluorescent thermal quenching characteristics. However, this system exhibits negative thermal quenching characteristics, which may be related to the enhanced emission of higher energy levels due to thermal activation between thermally coupled energy levels, and may also be related to the E level emission intensity.3+ Non-equivalent substitution of Ca 2+ This is related to the defects produced. The negative thermal quenching property can significantly improve spectral resolution at high temperatures, which is of great significance for improving high-temperature sensitivity and temperature resolution.
[0043] The opposite trends in fluorescence intensity between the two energy levels with temperature are beneficial for improving relative sensitivity. Peaks 1, 2, 3, and 4 represent Er, respectively. 3+ of 4 S 3 / 2 → 4 I 15 / 2 , 2 H 11 / 2 → 4 I 15 / 2 and Cr 3+ of 4 T2→ 4 A2, 2 E→ 4 A2 emission peak. The fluorescence intensity ratio of the thermally coupled energy levels was analyzed using an exponential function. I 1 / I 2. I 3 / I 4) Fitting the temperature variation, using a polynomial function to measure the fluorescence intensity ratio of the non-thermally coupled energy levels ( I 1 / I 4. I 3 / I 2) Fitting the data as it changes with temperature, the fitting results are as follows: Figure 18-23 As shown. The calculated relative sensitivity is as follows. Figure 24-29 As shown, the maximum relative sensitivity was obtained using four fluorescence intensity ratios. S r The values and corresponding temperatures are shown in Table 2. Among them, the multiphase ceramic sample prepared in Example 3 exhibited a relative sensitivity of 0.85% K in the temperature range from room temperature to 573 K. -1 The maximum relative sensitivity is 3.28% K. -1 ,like Figure 30 As shown, the temperature resolution can reach ~0.1 K. Using Cr... 3+ and Er 3+ The advantage of the four fluorescence intensity ratio modes for two activated ions in thermometry is that the wide temperature range from room temperature to 573 K can be divided into different temperature segments based on the temperature range with higher relative sensitivity. Within each operating temperature segment, the fluorescence intensity ratio corresponding to higher relative sensitivity is used, effectively improving the relative sensitivity across the entire temperature range. Specifically, for Example 3, within the temperature range of 308-348 K, the following mode is used... I 3 / I4. Fluorescence intensity ratio thermometry exhibits high relative sensitivity, ranging from 2.93% to 2.30% K. -1 Within the temperature range of 348-416 K, the following is adopted: I 3 / I 2. Fluorescence intensity measurement exhibits high relative sensitivity, ranging from 3.28% to 1.62% K. -1 Within the temperature range of 416-573 K, the following is adopted: I 3 / I 4. Fluorescence intensity ratio thermometry exhibits high relative sensitivity, ranging from 1.62% to 0.85% K. -1 .
[0044] Table 1. Raw material ratios (molar percentage) for Examples 1-6
[0045] Table 2. Maximum relative sensitivity and corresponding temperature for multi-parameter fluorescence intensity ratio thermometry of multiphase ceramics obtained in Examples 1-6.
[0046] Example 7
[0047] The glass precursor composition in this embodiment is the same as that in Example 3, and the sample preparation method is largely the same as in Example 3, except that the heat treatment temperature is 1400 °C. XRD results show (as...) Figure 31 As shown in the figure, the sample heat-treated at 1400 °C for 2 h precipitated only two crystalline phases: β-CaTa₂O₆ and α-Al₂O₃. The room-temperature fluorescence spectrum of the sample in this example is compared (e.g., ...). Figure 32 The room temperature fluorescence spectra of the sample in Example 3 (as shown) and the sample in Example 3 (as shown) Figure 8 As shown in the figure, there is no significant change in the fluorescence spectra of the two, indicating that Cr can still be obtained when the heat treatment temperature is increased to 1400 ℃. 3+ and Er 3+ The ceramic is co-doped with α-Al2O3 / β-CaTa2O6 and its spectral characteristics remain basically unchanged.
[0048] Example 8
[0049] The glass precursor composition in this embodiment is the same as that in Example 3, and the sample preparation method is largely the same as in Example 3, except that the heat treatment time is 10 h. XRD results show (e.g.) Figure 33 As shown in the figure, the sample heat-treated at 1300 °C for 10 h precipitated only two crystalline phases: β-CaTa₂O₆ and α-Al₂O₃. This is in contrast to the example shown. Figure 34 The room temperature fluorescence spectra of the sample in Example 3 (as shown) and the sample in Example 3 (as shown) Figure 8As shown in the figure, increasing the heat treatment time from 2 h to 10 h has no significant effect on the fluorescence spectrum of the sample, indicating that Cr can still be obtained when the heat treatment holding time is increased to 10 h. 3+ and Er 3+ The ceramic is co-doped with α-Al2O3 / β-CaTa2O6 and its spectral characteristics remain basically unchanged.
[0050] Comparative Example 1 The glass precursor composition of this comparative example is the same as that of Example 3, and the sample preparation method is largely the same as that of Example 3, except that the heat treatment temperatures are 900, 1000, 1100, and 1200 °C, respectively. According to XRD (e.g., Figure 35 As shown in the figure, the sample heat-treated at 900 ℃ only precipitated cubic α-CaTa2O6 crystals; with increasing heat treatment temperature, the content of cubic α-CaTa2O6 decreased, while the content of orthorhombic β-CaTa2O6 gradually increased; when the heat treatment temperature was 1200 ℃, the diffraction peaks of α-Al2O3 crystals were relatively weak, indicating that α-Al2O3 was not completely precipitated. From the room temperature emission spectrum (as shown in the figure), it can be seen that... Figure 36 As shown in the figure, the fluorescence peaks of the samples heat-treated at 900, 1000, and 1100 °C are extremely weak and broad, indicating a complex coordination environment, possibly existing in the glass phase. The fluorescence peak intensity of the sample heat-treated at 1200 °C increases, the peak width is narrower, and a double peak appears at 684 nm and 694 nm. This is related to the Cr in different Al2O3 crystal phases. 3+ A comparison of emission spectra reveals that the fluorescence peak at 684 nm likely originates from θ-Al₂O₃, while the peak at 694 nm is attributed to α-Al₂O₃. Heat treatment at 1200 °C cannot completely transform the aluminous glassy phase in the sample into the α-Al₂O₃ crystalline phase. Therefore, heat treatment at 900-1200 °C cannot yield Cr. 3+ and Er 3+ Co-doped α-Al₂O₃ / β-CaTa₂O₆ multiphase ceramics, and the obtained sample contains Cr 3+ The luminescence is extremely weak and cannot be used for fluorescence thermometry. Only when the heat treatment temperature is further increased to 1300-1400℃ can the aluminum-rich phase be completely transformed into α-Al₂O₃ precipitation, yielding Cr. 3+ and Er 3+ Co-doped α-Al₂O₃ / β-CaTa₂O₆ multiphase ceramics, Cr 3+ The fluorescence intensity is significantly increased, making it effectively detectable by the detector.
[0051] Comparative Examples 2-7 The raw material formulations for Comparative Examples 2-7 are shown in Table 3, where Comparative Examples 2-6 contain Cr. 3+ Single-doped sample, Comparative Example 7 is Er 3+The single-doped sample was prepared using the same method as in Example 1. Figure 37-42 As shown, Comparative Examples 2-7 precipitated only β-CaTa₂O₆ and α-Al₂O₃ crystalline phases after heat treatment at 1300 °C for 2 h. The room-temperature fluorescence spectra of Comparative Examples 4 and 7 are shown below. Figure 9 and 10 As shown, Cr 3+ and Er 3+ The characteristic fluorescence peak of ions. Due to Cr 3+ Single doping Er 3+ Single-doped samples all exhibit fluorescence peaks from only one activated ion; therefore, temperature measurement can only be performed using the fluorescence intensity ratio of a single ion, for example: Er. 3+ ion 4 S 3 / 2 and 2 H 11 / 2 The ratio of thermally coupled energy level fluorescence intensity and Cr 3+ ion 4 T2 and 2 The fluorescence intensity ratio of the thermally coupled energy levels. The temperature-dependent fluorescence spectra of Comparative Example 4 and Comparative Example 7 are as follows: Figure 43 and 44 As shown, using Er 3+ ion 4 S 3 / 2 and 2 H 11 / 2 The ratio of thermally coupled energy level fluorescence intensity and Cr 3+ ion 4 T2 and 2 The temperature function obtained by fitting the fluorescence intensity ratio of the E-thermal coupling energy level is as follows: Figure 45 and 46 As shown, the relative sensitivity is as follows Figure 47 and 48 As shown. The relative sensitivity obtained from the fluorescence intensity ratio of thermally coupled energy levels is related to temperature (…). T ) and energy level difference (Δ E The relationship is S r =Δ E / k T 2 The higher the temperature, the lower the relative sensitivity. The relative sensitivities of the multiphase ceramic samples obtained in Comparative Example 4 and Comparative Example 7 at 573 K were 0.79% K, respectively. -1 and 0.33% K -1 Therefore, with Cr 3+ and Er 3+ Compared with co-doped multiphase ceramics, the relative sensitivity of single-doped multiphase ceramic samples gradually decreases with increasing temperature, making it impossible to achieve the goal of having high relative sensitivity across the entire temperature range from room temperature to 573 K.
[0052] Table 3 Raw material ratios (molar percentage) for Comparative Examples 2-7
[0053] Comparative Example 8 The glass precursor composition of this comparative example is the same as that of Comparative Example 7, and the sample preparation method is roughly the same as that of Comparative Example 7, except that the heat treatment temperature is 900 ℃ and the holding time is 10 h. XRD (as shown) Figure 49 The results (as shown) indicate that the sample heat-treated at this temperature precipitates cubic α-CaTa₂O₆ crystals. The room-temperature fluorescence spectrum of this sample (as shown) Figure 50 (As shown) Er 3+ of 4 S 3 / 2 and 2 H 11 / 2 The energy level splitting is not obvious, indicating that Er 3+ The sample was in a highly disordered environment, and the two fluorescence peaks overlapped significantly, resulting in insufficient spectral resolution. Furthermore, similar to Comparative Example 7, this comparative example's sample contained only Er... 3+ The fluorescence peak of a single ion, when used for temperature measurement based on the fluorescence intensity ratio of its thermally coupled energy levels, results in relatively low sensitivity at high temperatures. Therefore, with Cr... 3+ and Er 3+ Compared with co-doped multiphase ceramics, Er 3+ Single-doped cubic α-CaTa2O6 glass-ceramics cannot achieve a target with high relative sensitivity across the entire temperature range from room temperature to 573 K.
Claims
1. A multiphase ceramic, characterized in that, Its chemical formula is x α-Al₂O₃ / (100- x β-CaTa2O6: y Cr2O3, z Er₂O₃, where 51≤ x ≤59 mol%, 0< y ≤0.8 mol%, 0< z ≤2.0 mol%.
2. The method for preparing a multiphase ceramic according to claim 1, characterized in that, The glass was prepared using a fully controllable crystallization method, including the following steps: 1) Weigh the calcium source, tantalum source, aluminum source, chromium source and erbium source raw materials according to the stoichiometric ratio, and mix the raw materials evenly to obtain a powdered glass mixture; 2) Place the powdered glass mixture obtained in step 1) into a mold and press it into shape to obtain a sheet-like glass mixture; 3) Place the sheet glass mixture obtained in step 2) into a muffle furnace for pre-sintering to obtain a block glass mixture; 4) The block glass mixture obtained in step 3) is used to prepare a glass precursor by pneumatic suspension method; 5) The glass precursor obtained in step 4) is placed in a muffle furnace for heat treatment to obtain multiphase ceramic.
3. The method for preparing a multiphase ceramic according to claim 2, characterized in that, Step 5) The heat treatment temperature is 1300-1400 ℃, the holding time is 2-10 h, and then it is slowly cooled to room temperature.
4. The method for preparing a multiphase ceramic according to claim 2, characterized in that, The calcium source is one of calcium oxide, carbonate, or hydroxide; the tantalum source is tantalum oxide; the aluminum source is one of aluminum oxide or hydroxide; the chromium source is trivalent chromium oxide; and the erbium source is erbium oxide.
5. The application of a multiphase ceramic according to any one of claims 1 to 4 in the field of fluorescence thermometry.
6. The application according to claim 5, characterized in that, Using the aforementioned multiphase ceramic to bond Er 3+ and Cr 3+ The fluorescence intensity ratio is used for temperature detection.
7. The application according to claim 6, characterized in that, The specific steps include: 1) Obtaining the temperature function: The multiphase ceramic was excited using a 375 nm light source. Fluorescence spectra in the 500-850 nm band were collected every 25 K within the temperature range of room temperature to 573 K. The Er... 3+ At 522 nm and 548 nm, Cr 3+ At 645 nm and 694 nm, Er 3+ At 522 nm and Cr 3+ At 694 nm, Cr 3+ At 645 nm and Er 3+ The four fluorescence intensity ratios at 548 nm were fitted with a function of temperature to obtain the four fluorescence intensity ratios as a function of temperature. 2) Evaluation of temperature measurement performance: The composite ceramic is coupled with an optical fiber and placed in the test environment or on the surface of the object to be tested. Excitation is performed at 375 nm to measure Er. 3+ and Cr 3+ The fluorescence intensity ratios of the four sets mentioned in step 1) are calculated and substituted into the four fitted temperature functions to obtain the temperature of the environment or object to be tested.
8. The application according to claim 7, characterized in that, The specific method for obtaining the temperature of the environment or object to be tested is as follows: the wide temperature range from room temperature to 573 K is divided into different temperature segments according to the temperature range where the relative sensitivity is located. The four fitted temperature functions mentioned above are substituted to obtain four temperature values with similar values. Within the temperature segment where the four temperature values are located, the temperature value corresponding to the fluorescence intensity ratio with the highest relative sensitivity is the final temperature of the environment or object to be tested.