Tb-doped fluorescent powder for optical temperature measurement as well as preparation method and application of Tb-doped fluorescent powder

Abstract

The invention discloses Tb-doped fluorescent powder for optical temperature measurement and a preparation method and application thereof, and belongs to the technical field of luminescent materials, the molecular formula of the fluorescent powder is Na2Ca2Sc2Si3O12: xTb < 3 + >, and x is equal to 0.12-15%. The preparation method comprises the following steps: weighing the raw materials according to the stoichiometric ratio, mixing and grinding, heating and preheating the obtained powder, quickly heating and calcining, and crushing and grinding after calcining to obtain the Tb-doped fluorescent powder for optical temperature measurement. The obtained fluorescent powder is wide in temperature measurement range, light emitting color can be regulated and controlled, and the fluorescent powder has good optical temperature measurement performance within the ultra-wide range of 120K-720K.

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent materials, and in particular relates to a Tb-doped phosphor for optical temperature measurement, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, extensive research has been devoted to developing luminescent materials for non-contact, high-precision temperature measurement. Optical temperature measurement technology not only offers advantages such as low loss, wide application, high sensitivity, and superior safety, but also plays a vital role in scientific research, biomedicine, industrial production, and other fields. Currently, scientific research requires precise temperature measurement in extreme conditions such as corrosive media, extremely cold environments, high-temperature and high-pressure environments, and high-radiation fields. Consequently, optical temperature measurement technology has garnered widespread attention and research. Among various optical temperature measurement techniques, fluorescence intensity ratio (FIR) technology demonstrates high accuracy, good repeatability, and is unaffected by environmental conditions and resolution. FIR technology can be used in thermally coupled levels (TCLs). Under specific conditions, a phosphor is excited using two distinct emission peaks with varying temperature sensitivities, resulting in a fluorescence ratio that varies with temperature.

[0003] Chen et al. prepared Ca3Sc2Si3O by a high-temperature solid-phase method. 12 :Ce 3+ , Tb 3+ , among which studies have shown that Tb 3+ It not only enhances the photoluminescence of phosphors, but also reduces the thermal quenching of phosphors. Feng et al. synthesized submicron Ca3Sc2Si3O by the Sol-gel method at a lower temperature. 12 :Ce 3+ , Tb 3+ , and studied its phase, photoluminescence, and thermal quenching properties. However, the optical properties of this system are not studied thoroughly enough. 3+ It is a common rare earth ion. 5 D4→ 7 F J The emission is located in the green region of ultraviolet excitation, and the luminescence center emits green light at around 540nm-550nm, which can also be observed in the spectrum. 5 D3→ 7 F J The blue emission of the phosphor can be adjusted from green to near cyan by using this emission law. This can be achieved by changing the Tb 3+ The emission color and the correlated color temperature (CCT) of the radiation can be controlled, making Tb 3+Ion doping makes it possible to emit white light or even multi-color light.

[0004] Tb 3+ The blue and green luminescence of ions has aroused people's interest in the research of ratiometric non-contact optical thermometry. Due to the influence of experimental conditions, the reliability of single-band luminescence thermometers is questionable. 5 D3 and 5 Double emission bands of the D4 excited state of Tb 3+ Ions can improve the accuracy of temperature measurements because they avoid temperature readings biased by spectral overlap, as reported for [NEt4]2[(Ph4Ge4O8)2(Ln4)(NO3)6(EtOH)2(MeCN)2]·n(CH3CN):Eu / Tb, Sr = 0.87% K at 330 K. -1 , Tb 3+ Doped 50GeO2-35TeO2-15SrF2 glass, Sr = 0.95% K at 523K -1 , CaWO4:3%Tb 3+ , at 353K, Sr reaches 1.50%K -1 Although people are interested in Tb 3+ There are many studies on high-temperature optical temperature measurement with ion doping, but there are problems such as poor stability and narrow temperature measurement range.

[0005] In addition, the high sensitivity of phosphors to X-rays has also become a widely studied topic. Under X-ray irradiation, phosphors emit ultraviolet and visible light and are widely used in non-destructive testing, biomedical imaging, nuclear physics and other fields. Fan, Sun and others successfully prepared Lu2SiO5:Ce 3+ ,Gd2O5S:Pr 3+ 、LuAG:Ce 3+ ,Mg 2+ X-ray scintillators such as fluorescein and cyanine have been commercially applied. Research on X-ray scintillators has achieved significant results in recent years, but there is still a need to develop phosphors with high stability and radiation resistance. Currently, most optical temperature sensors are realized under ultraviolet or visible light excitation, but there is little research on phosphors that can achieve optical temperature measurement using X-ray excitation.

[0006] Therefore, how to provide a phosphor that can realize optical temperature measurement by using X-ray excitation is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention proposes a Tb-doped phosphor for optical temperature measurement, a preparation method and an application thereof.

[0008] To achieve the above objectives, the present invention provides the following technical solutions:

[0009] A Tb-doped phosphor for optical temperature measurement, with the molecular formula being Na2Ca2Sc2Si3O 12 :xTb 3+ , wherein x represents the doping amount (calculated in terms of the amount of substance), and x = 0.12-15%. Preferably, x = 0.12, 1, 1.5, 2, 3, 5, 10, 12 or 15%.

[0010] Beneficial effect: The present invention adopts high temperature solid phase method to prepare Tb with different concentrations. 3+ The ion-doped NCSSO powder was optically measured, and the phase of the prepared components was detected by XRD. The results showed that the prepared phosphors were all single-phase. 3+ The effect of increasing the content on photoluminescence, the study found that 5 D4 to 7 F J The intensity of Tb 3+ The content of Tb increases with the increase of 3+ In addition, due to the cross relaxation process, as the concentration increases 5 D3 to 7 F J The emission of Tb decreases, and the color coordinates move from the blue area to the green area. 3+ The content can change the luminescent color, making it possible to adjust the light-emitting diode to the ideal emission color. In addition, the emission spectrum of each doping concentration under X-ray excitation was studied, and it was found that due to the different excitation mechanisms, it is more conducive to X-ray excitation. 5 D4→ 7 Finally, NCSSO:12mol%Tb was studied under the excitation of X-rays. 3+ The optical temperature sensing performance of the phosphor is shown in Figure 2. The phosphor exhibits an excellent relative sensitivity Sr optical temperature measurement parameter at 120K, which is as high as 4.21%K. -1 , and the temperature measurement range is relatively wide from 120K to 720K. In summary, the phosphor provided by the present invention has potential application value in the fields of LED lighting and optical temperature sensing.

[0011] A method for preparing a Tb-doped phosphor for optical temperature measurement comprises the following steps:

[0012] The raw materials are weighed according to the stoichiometric ratio, mixed and ground, and the obtained powder is preheated and then rapidly heated and calcined. After the calcination, the powder is crushed and ground to obtain the Tb-doped phosphor for optical temperature measurement.

[0013] Preferably, the raw materials include sodium salt, calcium salt, Sc2O3, SiO2 and Tb4O7.

[0014] Preferably, the sodium salt is Na2CO3.

[0015] Preferably, the calcium salt is CaCO3.

[0016] Preferably, the preheating temperature is 600° C. and the preheating time is 2 hours.

[0017] Preferably, the calcination temperature is 1300° C. and the calcination time is 6 hours.

[0018] The invention discloses an application of a Tb-doped phosphor for optical temperature measurement in a temperature sensor.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] The present invention adopts high temperature solid phase method to synthesize the new luminescent material Na2Ca2Sc2Si3O 12 :xTb 3+ (NCSSO: x Tb 3+ ) phosphor, resulting in a phosphor with a wide temperature measurement range and controllable luminescence color. Furthermore, by varying the concentration, the emission spectrum, chromaticity coordinates, and color purity of the phosphor were observed. X-ray excited fluorescence (XEL) was discussed and studied, and the temperature sensing performance was investigated using the ratio between the emission peaks of 5D4→7F5 and 5D4→7F6. Ultimately, the phosphor obtained by this invention exhibits excellent optical temperature measurement performance over an ultra-wide range of 120K-720K. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0022] Figure 1 NCSSO obtained in Example 9: 0.12% Tb 3+ The X-ray powder diffraction patterns of the phosphor and NCSSO obtained in Comparative Example 1 are similar to those of Ca3Sc2Si3O 12 Standard card (PDF#97-002-7389);

[0023] Figure 2 (a) is the NCSSO:xTb obtained in Example 1 and Examples 3-8 excited at 277nm 3+ Emission spectrum; (b) NCSSO: xTb obtained in Example 1 and Example 3-8 detected at 545nm 3+ Excitation spectrum;

[0024] Figure 3 The main transition of the phosphor obtained by the present invention and NCSSO: xTb 3+ Cross-relaxation mechanism of phosphors;

[0025] Figure 4 (a) shows the dependence of the relative intensity of the 545nm peak of the phosphors obtained in Example 1 and Examples 3-8 on the concentration, where the red line is the G / B ratio and the black line is the Tb 3+ Function of concentration (λexc=277nm); (b) NCSSO:xTb obtained in Example 3+ log(I / Tb 3+ ) and log(xTb 3+ ) linear fitting and functional relationship between;

[0026] Figure 5 (a) is the NCSSO:xTb obtained in Example 1 and Examples 3-8 3+ CIE (x, y) coordinates of phosphor and Tb 3+ concentration; (b) is the CCT value of the sample under 277nm excitation;

[0027] Figure 6 (a) is NCSSO:xTb excited at 277nm 3+ Emission spectrum; (b) NCSSO:xTb under X-ray excitation 3+ fluorescence spectra of fluorescence;

[0028] Figure 7 (a) is NCSSO obtained in Example 7: 12% Tb 3+ Temperature dependence of phosphor under X-ray excitation; (b) NCSSO obtained in Example 7: 12% Tb 3+ Under the continuous excitation of X-rays, the phosphor 5 D4→ 7 F5 and 5 D4→ 7 The relationship between F6 emission; (c) NCSSO obtained in Example 7: 12% Tb 3+ Temperature dependence of phosphor; (d) NCSSO: 12% Tb obtained in Example 7 3+ Absolute sensitivity (Sa) and relative sensitivity (Sr) of phosphor temperature measurement. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0032] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3°C.

[0033] Example 1

[0034] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+ The method of preparing a series of phosphors (x=1%) comprises the following steps:

[0035] The raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) were accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.0025 (molar ratio, the same below), placed in an agate mortar, and added with an appropriate amount of alcohol and fully ground for 30 minutes until mixed evenly. The evenly ground powder was transferred to a corundum crucible, and then placed in a muffle furnace, heated to 600℃ in an air atmosphere for preheating for two hours, and then quickly heated to 1300℃ and calcined for 6 hours. After natural cooling, a white block sintered sample was obtained. The sample was crushed and ground with an agate mortar to obtain Na2Ca2Sc2Si3O 12 :Tb 3+ Phosphor, denoted as NCSSO: 1% Tb 3+ Phosphor.

[0036] Example 2

[0037] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+The method for preparing the (x=1.5%) series phosphor powder is different from that of Example 1 only in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.00375 to obtain Na2Ca2Sc2Si3O 12 : 1.5Tb 3+ Phosphor, denoted as NCSSO: 1.5% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0038] Example 3

[0039] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+ The method for preparing the (x=2%) series phosphor powder is different from that of Example 1 only in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.005 to obtain Na2Ca2Sc2Si3O 12 :2Tb 3+ Phosphor, denoted as NCSSO: 2% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0040] Example 4

[0041] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+ The method for preparing the (x=3%) series phosphor powder is different from that of Example 1 only in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.0075 to obtain Na2Ca2Sc2Si3O 12 :3Tb 3+ Phosphor, denoted as NCSSO: 3% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0042] Example 5

[0043] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb3+ The method for preparing the (x=5%) series phosphor powder is different from that of Example 1 in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.0125 to obtain Na2Ca2Sc2Si3O 12 :5Tb 3+ Phosphor, denoted as NCSSO: 5% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0044] Example 6

[0045] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+ The method for preparing the (x=10%) series phosphor powder is different from that of Example 1 in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.025 to obtain Na2Ca2Sc2Si3O 12 :10Tb 3+ Phosphor, denoted as NCSSO: 10% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0046] Example 7

[0047] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+ The method for preparing the (x=12%) series phosphor powder is different from that of Example 1 in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.03 to obtain Na2Ca2Sc2Si3O 12 :12Tb 3+ Phosphor, denoted as NCSSO: 12% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0048] Example 8

[0049] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb3+ The method for preparing the (x=15%) series phosphor powder is different from that of Example 1 only in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.0375 to obtain Na2Ca2Sc2Si3O 12 :15Tb 3+ Phosphor, denoted as NCSSO: 15% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0050] Example 9

[0051] A high temperature solid phase method for synthesizing Na2Ca2Sc2Si3O 12 :xTb 3+ The method for preparing a series of phosphors (x=0.12%) is different from that of Example 1 in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), SiO2 (99.99%) and Tb4O7 (99.99%) are accurately weighed according to the stoichiometric ratio of 1:2:1:1.5:0.0003 to obtain Na2Ca2Sc2Si3O 12 : 0.12Tb 3+ Phosphor, denoted as NCSSO: 0.12% Tb 3+ The remaining process steps and parameters are the same as those in Example 1.

[0052] Comparative Example 1

[0053] A method for preparing NCSSO phosphor differs from Example 1 only in that the raw materials Na2CO3 (99.99%), CaCO3 (99.99%), Sc2O3 (99.99%), and SiO2 (99.99%) are precisely weighed according to the stoichiometric ratio of 1:2:1:1.5 to obtain NCSSO. The remaining process steps and parameters are the same as those in Example 1.

[0054] Technical effect:

[0055] 1. Detection method

[0056] (1) The NCSSO obtained in Example 9 was measured using a Rigaku Ultima IV X-ray diffractometer: 0.12 Tb 3+ XRD of the phosphor and the NCSSO obtained in Comparative Example 1 was measured using a Cu-Kα radiation source with a scanning range of 10° to 80° and a scanning rate of 5°·min -1 .

[0057] (2) The PL of the samples was measured using a HITACHI F-7000 fluorescence spectrometer. The excitation light source was a Xe lamp with a spectral resolution of 0.2 nm.

[0058] (3) The samples were irradiated and XEL was measured using an LTTL3DS thermoelectroluminescence spectrometer (Guangzhou Redi Aison Technology Co., Ltd.). The irradiation source was an X-ray tube with an operating voltage of 50 kV, a current of 80 μA (adjustable), and a dose rate of approximately 0.033 Gy·s. -1 The measurable spectral range is 300nm~1000nm, the spectral resolution is 1nm, and the sample ambient temperature can be set between 120K~770K.

[0059] 2. Test results

[0060] XRD analysis

[0061] NCSSO obtained in Example 9: 0.12% Tb 3+ The X-ray powder diffraction patterns of the phosphor and the NCSSO obtained in Comparative Example 1 are as follows: Figure 1 As shown, with Ca3Sc2Si3O 12 As shown in the figure, the number and position of X-ray diffraction peaks of different samples are basically consistent with those of the standard card. 3+ When the doping concentration increases to 12%, no stray phase appears, indicating that the synthesized sample belongs to Ca3Sc2Si3O 12 The single-phase system has an Ia-3d crystal structure and lattice parameter values ​​of A=12.220nm, B=12.220nm and C=12.220nm.

[0062] Photoluminescence analysis

[0063] The PLE excitation spectra and PL emission spectra of the phosphors obtained in Examples 1-8 were obtained at room temperature. Figure 2 Part (a) describes the PLE excitation spectrum detected at 545 nm, where four broad absorption bands are observed, namely Tb 3+ from 7 F6 ground state to 4f 8 →4f 7 5d 1 (277nm), 5 H7 (325nm), 5 L9+ 5 G5 (354nm), 5 G6+ 5D3 (375nm), which indicates that the material has strong absorption ability for ultraviolet to visible light. The broad excitation band observed at 250nm-300nm is located in the strong UV ultraviolet band, which is attributed to the spin-allowed 4f 8 →4f 7 5d 1 Transition, not O2-Tb 3+ Charge transfer (CT) transition, because the charge transfer (CT) band energy level is about 60000cm -1 , than Tb 3+ The 5D state is much higher.

[0064] Figure 2 Part (b) describes the emission spectrum obtained under 277 nm excitation, where 5 D4→ 7 F J The bands are 5 D4→ 7 F6 (486nm), 5 D4→ 7 F5 (545nm), 5 D4→ 7 F4 (585nm), 5 D4→ 7 F3 (624nm) is Tb 3+ In addition, 388nm, 419nm, and 486nm correspond to Tb 3+ of 5 D3→ 7 F6, 5 D3→ 7 F5, 5 D3→ 7 F4 jump. 5 D3→ 7 F J and 5 D4→ 7 F J The intensity of the emission can be changed by adjusting the doping concentration. In general, the strongest emission peak is mainly caused by 5 D4→ 7 F6 (electric dipole character, ED electric dipole characteristic) and 5 D4→ 7 F5 (magnetic dipole character, MD magnetic dipole characteristics) named them blue (B) and green (G) emission. In addition, with the increase of doping concentration 5 D4→ 7 F JThe emission intensity increases continuously until 12 mol% where concentration quenching occurs due to excessive concentration. 5 D3→ 7 F J The emission intensity continues to decrease.

[0065] Figure 3 is determined by the excitation and emission spectra (see Figure 2 Tb in NCSSO phosphor constructed in parts (a) and (b) 3+ Schematic diagram of cross-relaxation mechanism and energy level. It can be seen that when the sample is excited at 277nm, due to the 4f 8 →4f 7 5d 1 Under the influence of the crystal field, electrons from Tb 3+ of 7 The F6 ground state transition occurs, and then the electron is transferred to 5 D3 or 5 D4 state. Figure 2 Part (b) shows that as Tb 3+ The increase in concentration, 5 The emission intensity of the D3 state gradually decreases. This result is attributed to the energy gap 5 D3- 5 D4 and 7 F2- 7 F6, because 5 D3 and 5 The energy gap between D4 levels is about 6000 cm -1 , very close 7 F2 and 7 The energy gap between F6, according to Tb 3+ ( 5 D3)+Tb 3+ ( 7 F6)→Tb 3+ ( 5 D4)+Tb 3+ ( 7 F2) quasi-resonance occurs, resulting in more frequent cross-relaxation CR processes, and the energy is increased from 5 D3 state transfers to 5 D4 state. Therefore, as the doping concentration increases, 5 D3→ 7 F J The efficiency of radiative transitions is reduced, which helps 5 D3→ 7 F J quenching of the transition, thereby reducing 5 The luminous intensity of the D3 state is enhanced. At the same time, due to the improvement of non-radiative efficiency, 5 Luminescence intensity of D4 state.

[0066] In order to further study the Tb 3+ The energy transfer mechanism between ions was calculated using the Dexter model to determine the luminescence intensity (I) and the relationship between Tb 3+ The relationship between doping concentration (x) is shown in formula (1):

[0067]

[0068] Among them, x Tb3+ is the ion doping concentration, I is the relative intensity of the emission peak, Q is the parameter for a specific type of electric multipole interaction, and A is a fitting parameter. When Q = 3, an interaction occurs; when Q is 6, it indicates a dipole-dipole interaction; when Q is 8, it indicates a dipole-quadrupole interaction; and finally, a quadrupole-quadrupole interaction is indicated by Q = 10.

[0069] exist Figure 4 In part (b) of the figure, the slope of the linear fit is -1.40, which corresponds to a value of -Q / 3. Therefore, it can be inferred that the value of Q is 4.2, which is between 3 and 6, indicating that Tb 3+ The blue emission quenching mechanism of doped NCSSO is mainly due to electron exchange and dipole-dipole interaction. 3+ Similar situations have also occurred in phosphors.

[0070] Among them, Ca2Al2SiO7:Tb 3+ Phosphor powder is derived from TIAN X, YIN X, WU F, et al.Adual-mode optical thermometry ofCa2Al2SiO7:Tb 3+ / K + Phosphors based on the redshift of f-dtransition adsorption edge[J]. Ceramics International, 2025, 51(4):4828-37.

[0071] G / B is Tb 3+ The emission ratio, usually taken as Tb 3+ A measure of the symmetry of local sites in the coordination sphere, used to describe the characteristics of covalent / ionic bonds. Figure 4Table 1 shows the G / B values ​​of samples with different doping concentrations. It can be observed that the G / B value increases with the increase of doping concentration, from 1.99 (1 mol%) to 2.36 (12 mol%) and then decreases to 2.30 (15 mol%). It can be seen that when the doping concentration is high, the G / B ratio remains almost unchanged. According to Gupta et al., the G / B value is also higher when the concentration is higher, which is attributed to the donor atoms and Tb occupying the low symmetry coordination center. 3+ The high covalency between ions. At the same time, the G / B ratio is low at low concentrations, probably because it is less than 5% mol 5 D3→ 7 F J The emission intensity is moderate, and the overall intensity of blue light is strong. This finding indicates that the sample promotes 5 Deactivation process of D3 state.

[0072] Table 1. Photometric parameters: G / B ratio, CIE (x, y) chromaticity coordinates, color purity, and CCT value

[0073]

[0074] From the emission spectrum, the photometric parameters CIE 1931 (x, y) chromaticity coordinates, correlated color temperature (CCT) and color purity (CP) value can be calculated. Figure 5 Part (a) shows the collection of NCSSO:xTb at room temperature 3+ (x = 1, 2, 3, 5, 10, 12 and 15%) CIE coordinates. Figure 5 In part (a), we can see that by increasing the doping concentration, the CIE coordinates move from the blue region to the green region. This discovery makes it possible to adjust the emission color. The correlated color temperature (CCT) value is calculated using the McCamy formula:

[0075] CCT=-437n 3 +3601n 2 -6861n+5514.31 (2)

[0076] in

[0077] like Figure 5 As shown in part (b), as Tb 3+ As a function of the concentration in terms of excitation, a significant decrease in the CCT value can be observed from 1 mol% to 2 mol%. This is because 5 D3 and 5 There is a competitive relationship between the D4 state horizontal emission, among which, 5 D3→ 7 F JThe emission shifts the CIE coordinates to the blue region. This discovery of NCSSO:xTb 3+ Phosphors have potential applications in white light LEDs. Furthermore, compounds with CCT values ​​above 5000K are well-suited for commercial rare earth compound applications in cool white light and for improving overall display brightness. Van Hoof et al. reported that compounds with higher CCT values ​​(8000K or above) could also be used to treat Alzheimer's disease.

[0078] 2.3. X-ray fluorescence analysis

[0079] X-rays were used instead of ultraviolet light to excite the samples and observe their luminescence characteristics. The XEL characteristics of the NCSSO:xTb (x=1, 2, 3, 5, 10, 12 and 15%) series phosphors obtained in Examples 1 and 3-7 were as follows: Figure 6 As shown in part (b), the XEL and PL of the sample under 277nm excitation are basically consistent, and the peak shape is almost the same, which indicates that the radiation recombination pathways in response to X-ray and ultraviolet excitation are consistent. 3+ As the concentration of ions increases, the luminescence intensity also increases. When the concentration reaches 12 mol%, the luminescence intensity is the strongest. As the doping concentration increases further, concentration quenching occurs. From this result, it can be seen that NCSSO: xTb 3+ Phosphors are very sensitive to X-rays. It can be observed that the concentration quenching intensity of XEL is stronger than that of PL. This is attributed to the different excitation mechanisms of light and X-rays. Light can directly excite the luminescent center, while X-rays excite the lattice. In addition, from the comparison between XEL and PL, it can be seen that the concentration quenching intensity of XEL is stronger than that of PL. 5 D3→ 7 F J and 5 D4→ 7 F6, 5 D4→ 7 F4 and 5 D4→ 7 The emission intensity of these F3 energy level transitions is much smaller than 5 D4→ 7 F5 is compared to PL. This is attributed to the fact that the heavy element Tb in the sample absorbs X-ray photons, generating a large number of high-energy electrons and deep holes through the photoelectric effect and Compton scattering mechanism. These electrons quickly thermalize and generate secondary electrons, thereby generating a large number of electron-hole pairs. Subsequently, the luminescence center passes through Tb 3+ ions capture the energy of these electron-hole pairs, which then 5 The D4 level radiatively relaxes to the ground state, further enhancing 5 D4→ 7The intensity of F5. Therefore, XEL performance depends largely on PL performance. NCSSO phosphors have strong X-ray excited fluorescence, which has potential application value in the field of X-ray imaging.

[0080] 2.4 Optical Temperature Sensor

[0081] For NCSSO obtained in Example 7: 12Tb 3+ phosphors, Figure 7 Part (a) shows that as the temperature increases from 120K to 720K, 5 D4→ 7 F J The characteristic transition increases monotonically, and Tb 3+ The center of gravity of the launch has not changed; it is still 5 D4→ 7 F5 is the main transition. In addition, 5 D3→ 7 F J The fact that the FIR parameter can be used as an optical temperature sensor over a wide range of temperatures from low to high temperatures is due to the enhanced cross-relaxation CR mechanism at high concentrations.

[0082] Because the irradiated luminescence parameters of the emission center (spectral shift, bandwidth, intensity, etc.) are affected by temperature, the thermal behavior of these parameters can affect the spectrum in a non-invasive or semi-invasive manner. Therefore, the present invention uses the relative change in the intensity ratio of two independent energy level transitions to avoid the influence of excitation light source and detector errors.

[0083] The following formula (3) can be used to 5 D4→ 7 F5 and 5 D4→ 7 The ratio of fluorescence intensity at F6 is fitted:

[0084]

[0085] Where A is a constant, B is a pre-exponential constant, and ΔE is the non-radiative channel constant. 5 Activation energy of D4 energy level, K B is the Boltzmann constant (K B =1.380649*10 -23 ), T is the thermodynamic temperature.

[0086] like Figure 7 As shown in part (b), it can be seen that as the temperature increases 5 D4→ 7 F5 and 5 D4→ 7 The fluorescence intensity of F6 continued to increase, and5 D4→ 7 The fluorescence intensity growth rate of F5 transition is 5 D4→ 7 F6 is faster, which means that the FIR ratio increases linearly with increasing temperature. Figure 7 As shown in part (c), using FIR and T -1 Assemble the vertical and horizontal coordinates respectively, and determine the coefficient R after fitting 2 =0.997, indicating that the fitting effect is good.

[0087] In addition, absolute sensitivity (Sa) and relative sensitivity (Sr) are important parameters for evaluating the practical application of phosphors as optical temperature sensors. Absolute sensitivity is defined as the rate of change of the FIR with temperature, while relative sensitivity reflects the rate of change of the FIR response to temperature changes. They are obtained according to the following equations (4) and (5).

[0088]

[0089] According to formula (4) and formula (5), the absolute sensitivity and relative sensitivity of the sample are obtained. The results are as follows: Figure 7 As shown in part (d), in the temperature range of 120K to 720K, the absolute sensitivity and relative sensitivity of the sample decrease with increasing temperature. Sa and Sr both show their maximum values ​​at 120K, Sa-max = 0.157K. -1 , Sr-max=4.21%K -1 These results, compared with other doped phosphors listed in Table 2, indicate that the samples have good temperature and high thermal sensitivity performance.

[0090] Table 2. Comparison of Sa and Sr parameters

[0091]

[0092]

[0093] Note: Ca2Al2SiO7:Tb 3+ ,Eu 3+ From HUFangfang,Z.Zhao,F.Chi,X.Wei,M.Yin, Structural characterization and temperature-dependent luminescence of CaF2:Tb 3 + / Eu 3+ glass ceramics,J.Rare Earths,(2017)536-541.

[0094] CaF₂:Tb 3+ ,Eu 3+ From J.Deng, Z.Wang, W.Zhou, M.Yu, J.Min, X.Jiang, Z.Xue, C.Ma, Z.Cheng, G.Luo, Energy transfer of Tb 3+ →Eu 3+ in Ca₂Al₂SiO₇ phosphors with multicolor tunable and optical temperature sensing properties, Ceram.Int., 49(2023)14478 - 14486.

[0095] CaWO₄:Tb 3+ From Z.Zhang, F.Li, Y.Yang, Z.Wang, P.Li, R.Zhang, H.Suo, L.Li, Tb 3 + -based multi-mode optical ratiometric thermometry, Phys.Chem.Chem.phys., (2023)9158 - 9167.

[0096] Sr₈MgCe(PO₄)₇:Tb 3+ From Y.Li, Y.Zhou, X.Li, H.Wu, W.Wang, Energy transfer and the anti-thermal quenching behavior of Sr₈MgCe(PO₄)₇:Tb 3+ for temperature sensing, Spectrochim.Acta, Part A, 252(2021)119548.

[0097] Y₂O₃:Tb 3+ ,Eu 3+ From L.Peng, Q.Meng, W.Sun, Size dependent optical temperature sensing properties of Y₂O₃:Tb 3+ ,Eu 3+ nanophosphors, RSC Adv., 9(2019)2581 - 2590.

[0098] TeO2-ZnF2-PbO-Nb2O5 from B.Klimesz, R.Lisiecki, W.Ryba-Romanowski, Thermosensitive Tm 3+ / Yb 3+ co-doped oxyfluorotellurite glasses-spectroscopic and temperature sensor properties, J. Alloys. Compd., 823 (2020) 153753.

[0099] Sr3MoO6:Eu 3+ ,Tb 3+ FromDVMPaiva,SKJakka,MASSilva,JPCDNascimento,MPFGraa,ASBSombra,MJSoares,SEMazzetto,P.Fechine,K.Pavani,Investigation on luminescence based optical temperature sensingbehavior of Sr3MoO6:Eu 3+ / Tb 3+ ,Optik,246(2021)167825-.

[0100] Y2Ge2O7:Tb 3+ FromDETdos Santos,A.Torquato,IVBarbosa,JFCarvalho,LJQMaia,RCdSantana,Temperature dependent photoluminescence properties of a Y2Ge2O7:Tb 3+ phosphors.A dual band ratiometric luminescent thermometer,J.Alloys.Chem.,1010(2025)177444.

[0101] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A Tb-doped phosphor for optical temperature measurement, characterized in that: The molecular formula is Na2Ca2Sc2Si3O 12 :xTb 3+ , wherein x=0.12-15%.

2. The method for preparing a Tb-doped phosphor for optical temperature measurement according to claim 1, wherein: The following steps are involved: The raw materials are weighed according to the stoichiometric ratio, mixed and ground, and the obtained powder is preheated and then rapidly heated and calcined. After the calcination, the powder is crushed and ground to obtain the Tb-doped phosphor for optical temperature measurement.

3. The method for preparing a Tb-doped phosphor for optical temperature measurement according to claim 1, wherein: The raw materials include sodium salt, calcium salt, Sc2O3, SiO2 and Tb4O7.

4. The method for preparing a Tb-doped phosphor for optical temperature measurement according to claim 1, wherein: The sodium salt is Na2CO3.

5. The method for preparing a Tb-doped phosphor for optical temperature measurement according to claim 1, wherein: The calcium salt is CaCO3.

6. The method for preparing a Tb-doped phosphor for optical temperature measurement according to claim 1, characterized in that: The preheating temperature is 600° C. and the preheating time is 2 hours.

7. The method for preparing a Tb-doped phosphor for optical temperature measurement according to claim 1, characterized in that: The calcination temperature is 1300° C. and the calcination time is 6 hours.

8. Use of the Tb-doped phosphor for optical temperature measurement according to claim 1 in a temperature sensor.

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