Fluorescent powder based on ultraviolet light excited near-white light, preparation method and application thereof

Abstract

The invention relates to fluorescent powder based on ultraviolet excitation near-white light, in particular to Sm < 3 + > doped Sr9La (VO4) 7, the chemical formula is Sr9La (1-x) Smx (VO4) 7, x is larger than 0 and smaller than or equal to 0.25, the fluorescent powder can achieve near-white light emission under ultraviolet excitation, the emission color is adjustable along with the temperature, visual non-contact temperature measurement can be achieved through color change within the range of 298-573 K, and sensitivity is high. A high-temperature solid-phase method is adopted for preparation, the process is simple, raw materials are easy to obtain, and the purity requirement is easy to meet.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials, specifically relating to a phosphor based on ultraviolet light excitation of near-white light, its preparation method, and its application. Background Technology

[0002] In modern industrial testing and extreme environment monitoring, the demand for non-contact temperature measurement technology is increasingly urgent. Among these technologies, optical temperature measurement has become a research hotspot due to its advantages such as resistance to electromagnetic interference, high spatial resolution, and real-time response. The core of this technology lies in the temperature-sensitive properties of fluorescent materials, that is, quantifying temperature by analyzing changes in fluorescence intensity ratio, lifetime, or peak position. Rare-earth ion-doped fluorescent materials, due to their unique... 4f Electron transition characteristics have become a key research subject in this field.

[0003] Sm 3+ As an important rare earth activating ion, its electronic configuration is 4f 5 It can occur under stimulation. 4 G 5 / 2 → 6 H J Characteristic transitions such as (J=5 / 2, 7 / 2, 9 / 2) produce orange-red emission peaks around 567 nm, 601 nm, and 646 nm. The intensity of these emission peaks is extremely sensitive to temperature changes; as temperature increases, lattice vibrations intensify, leading to an increased probability of non-radiative transitions. The characteristic emission intensity exhibits a regular decay, and the decay rate differs among different transition channels. This characteristic allows for high-precision temperature sensing through multi-band intensity ratios. Simultaneously, Sm... 3+ It can maintain characteristic emission over a wide temperature range, which makes it possible to expand the temperature measurement range.

[0004] Vanadate matrices are widely used in the field of fluorescent materials due to their excellent optical properties and chemical stability. Their molecular structure contains VO4... 3- The group possesses a broad ultraviolet absorption band (200-400 nm), enabling efficient absorption of ultraviolet light energy through charge transfer transitions and transferring the energy to doped rare-earth ions, thus achieving effective sensitization of activated ions. Although there are reports of high-sensitivity thermometers based on vanadate phosphors, such as YVO4 and GdVO4, their research scope has not yet extended to the realization of visualization applications.

[0005] Sr9La(VO4)7, as a novel vanadate compound, possesses a unique trigonal crystal structure, with La in the lattice... 3+ Ionic radius and Sm 3+With high ionic radius matching, it is suitable for controlling luminescence performance through doping. Its band gap is approximately 3.8 eV, enabling effective absorption of ultraviolet light. It maintains structural stability even at high temperatures, demonstrating potential as a matrix material for optical thermometry. Currently, Sm... 3+ The optimal doping concentration, energy transfer mechanism, and temperature sensing mechanism in Sr9La(VO4)7 remain unclear. Therefore, the development of Sm-based... 3+ Exploring the application of near-white light-emitting phosphors doped with Sr9La(VO4)7 in visual optical thermometry is of great theoretical and practical significance for enriching the rare earth-doped vanadate material system and improving optical thermometry performance. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention aims to provide a phosphor based on ultraviolet light excitation for near-white light emission, which can be used for high-sensitivity visual temperature measurement to meet the increasingly urgent need for non-contact temperature measurement technology.

[0007] To achieve the above-mentioned objectives, the technical solution disclosed in this invention is as follows: A phosphor based on ultraviolet light excitation to produce near-white light, wherein the phosphor is Sm 3+ Doped Sr9La(VO4)7, with the chemical formula Sr9La 1-x Sm x (VO4)7, where x satisfies 0<x≤0.25.

[0008] In one of the schemes, x is further 0.01, 0.05, 0.10, 0.15, 0.20, or 0.25.

[0009] In one embodiment, the phosphor exhibits full-spectrum emission under ultraviolet light excitation, covering the 400-700nm visible region.

[0010] In one embodiment, the phosphor, when excited by light at a wavelength of 373 nm, exhibits tunable emission characteristics ranging from green to near-white light.

[0011] In one embodiment, the characteristic emission peak of the phosphor is Sm 3+ of 4 G 5 / 2 → 6 H 5 / 2 Transition emission peak (567 nm) 4 G 5 / 2 → 6 H 7 / 2 The transition emission peak (601 nm) and 4 G 5 / 2 → 6 H 9 / 2Transition emission peak (646 nm).

[0012] In one embodiment, the phosphor has the chemical formula Sr9La. 0.9 Sm 0.1 (VO4)7, under ultraviolet light excitation, its VO4 3- With Sm 3+ The emission intensity ratio changes systematically with temperature.

[0013] This invention also discloses a method for preparing the phosphor, which is prepared in air using a high-temperature solid-state method, comprising the following steps: (1) According to the chemical formula Sr9La 1-x Sm x The stoichiometric ratios of each element in (VO4)7 were determined. Compounds containing Sr, La, Sm, and V were weighed as raw materials, with each raw material having a purity ≥99.9%. (2) Mix and grind the raw materials weighed in step (1) evenly to obtain a mixed powder; (3) The mixed powder obtained in step (2) is calcined in a high-temperature furnace at a temperature of 900-1100 ℃ for 2-4 h. (4) After cooling to room temperature, grind to obtain the phosphor.

[0014] In one of the schemes, in step (1), the Sr-containing compound is SrCO3; the La-containing compound is La2O3; the Sm-containing compound is Sm2O3; and the V-containing compound is NH4VO3.

[0015] In one of the solutions, the specific preparation steps of the phosphor are as follows: (1) Raw material selection: Weigh raw materials with a purity ≥99.9% according to stoichiometric ratio: Sr-containing compounds (SrCO3), La-containing compounds (La2O3), Sm-containing compounds (Sm2O3), and V-containing compounds (NH4VO3); (2) Mixing and grinding: Put the above raw materials into an agate mortar and grind for about 30 minutes until they are evenly mixed; (3) Calcination treatment: The uniformly ground raw materials are loaded into a corundum crucible, placed in a muffle furnace, and heated to 1000 ℃ at a rate of 5 ℃ / min, and held for 3 h; (4) Cooling and grinding: After cooling naturally to room temperature, remove and grind again to obtain Sr9La. 1-x Sm x (VO4)7 fluorescent powder.

[0016] The present invention also discloses the application of the phosphor in the field of optical temperature measurement.

[0017] In one of the solutions, the application specifically involves the phosphor's emission color under 365 nm ultraviolet light changing from near-white to orange-red as the temperature increases within a detection temperature range of 298-573 K, thus enabling visualization of non-contact optical temperature measurement.

[0018] The beneficial technical effects of this invention are as follows: The phosphor of this invention is Sm 3+ Doped with Sr9La(VO4)7, it can achieve near-white light emission under ultraviolet excitation, and the emission color is adjustable with temperature. In the range of 298-573 K, it can achieve visual non-contact temperature measurement through color change, with high sensitivity. Its preparation adopts a high-temperature solid-state method, which is simple in process, uses readily available raw materials, and easily meets the purity requirements. Attached Figure Description

[0019] Figure 1 For Sr9La 1-x Sm x (VO4)7 where x represents the XRD patterns of four phosphor materials at values ​​of 0, 0.01, 0.1, and 0.25.

[0020] Figure 2 Sr9La in Example 1 0.9 Sm 0.1 (VO4)7's refined XRD image.

[0021] Figure 3 Sr9La in Example 1 0.9 Sm 0.1 Scanning electron microscope image of (VO4)7.

[0022] Figure 4 To excite Sr9La under 373 nm wavelength light 1-x Sm x (VO4)7, where x represents the emission spectra at values ​​of 0.01, 0.05, 0.1, 0.15, 0.2, and 0.25.

[0023] Figure 5 Sr9La photoexcitation at 373 nm wavelength 1-x Sm x (VO4)7, where x are the chromaticity coordinates at values ​​of 0.01, 0.05, 0.1, 0.15, 0.2 and 0.25 respectively.

[0024] Figure 6 Sr9La in Example 1 0.9 Sm 0.1 3D variable-temperature emission spectrum of (VO4)7.

[0025] Figure 7 Sr9La in Example 1 0.9 Sm 0.1 The curve of the normalized integral intensity of (VO4)7 emission as a function of temperature.

[0026] Figure 8 Sr9La in Example 1 0.9 Sm 0.1 (VO4)7 contains VO4 3- and Sm 3+ A graph showing the relationship between the normalized emission intensity of the luminescent center and temperature.

[0027] Figure 9 Sr9La in Example 1 0.9 Sm 0.1 (VO4)7 is based on VO4 3- and Sm 3+ Fitted curve of the ratio of luminous intensity of the luminous center.

[0028] Figure 10 Sr9La in Example 1 0.9 Sm 0.1 (VO4)7 achieves both absolute and relative sensitivity in optical temperature measurement.

[0029] Figure 11 Sr9La in Example 1 0.9 Sm 0.1 (VO4)7 enables the visualization display of the thermometer. Detailed Implementation

[0030] Although the invention has been described to a certain extent, it is apparent that appropriate variations can be made to the various conditions without departing from the spirit and scope of the invention. It is understood that the invention is not limited to the described embodiments, but falls within the scope of the claims, which include equivalent substitutions for each of the elements.

[0031] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0032] Example 1

[0033] According to the chemical formula Sr9La 0.9 Sm 0.1The stoichiometric ratios of each element in (VO4)7 were determined by weighing 1.32867 g SrCO3, 0.14663 g La2O3, 0.81893 g NH4VO3, and 0.01744 g Sm2O3 (all with a purity ≥ 99.9%) and grinding them thoroughly in an agate mortar for 30 min. After thorough grinding, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000 ℃ for 3 h at a heating rate of 5 ℃ per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. The chemical composition of the product is: Sr9La 0.9 Sm 0.1 (VO4)7.

[0034] Example 2

[0035] According to the chemical formula Sr9La 0.99 Sm 0.01 The stoichiometric ratios of each element in (VO4)7 were determined by weighing 1.32867 g SrCO3, 0.16129 g La2O3, 0.81893 g NH4VO3, and 0.00174 g Sm2O3 (all with a purity ≥ 99.9%) and grinding them thoroughly in an agate mortar for 30 min. After thorough grinding, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000℃ for 3 h at a heating rate of 5℃ per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. The chemical composition of the product is: Sr9La 0.99 Sm 0.01 (VO4)7.

[0036] Example 3

[0037] According to the chemical formula Sr9La 0.95 Sm 0.05 The stoichiometric ratios of each element in (VO4)7 were determined by weighing 1.32867 g SrCO3, 0.15477 g La2O3, 0.81893 g NH4VO3, and 0.00872 g Sm2O3 (all with a purity ≥ 99.9%) and grinding them thoroughly in an agate mortar for 30 min. After thorough grinding, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000℃ for 3 h at a heating rate of 5℃ per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. The chemical composition of the product is: Sr9La 0.95 Sm 0.05 (VO4)7.

[0038] Example 4

[0039] According to the chemical formula Sr9La 0.85 Sm 0.15The stoichiometric ratios of each element in (VO4)7 were determined by weighing 1.32867 g SrCO3, 0.13848 g La2O3, 0.81893 g NH4VO3, and 0.02615 g Sm2O3 (all with a purity ≥ 99.9%) and grinding them thoroughly in an agate mortar for 30 min. After thorough grinding, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000 ℃ for 3 h at a heating rate of 5 ℃ per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. The chemical composition of the product is: Sr9La 0.85 Sm 0.15 (VO4)7.

[0040] Example 5

[0041] According to the chemical formula Sr9La 0.8 Sm 0.2 The stoichiometric ratios of each element in (VO4)7 were determined by weighing 1.32867 g SrCO3, 0.13034 g La2O3, 0.81893 g NH4VO3, and 0.03487 g Sm2O3 (all with a purity ≥ 99.9%) and grinding them thoroughly in an agate mortar for 30 minutes. After thorough grinding, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000 °C for 3 hours at a heating rate of 5 °C per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. The chemical composition of the product is: Sr9La 0.8 Sm 0.2 (VO4)7.

[0042] Example 6

[0043] According to the chemical formula Sr9La 0.75 Sm 0.25 The stoichiometric ratios of each element in (VO4)7 were determined by weighing 1.32867 g SrCO3, 0.12219 g La2O3, 0.81893 g NH4VO3, and 0.04359 g Sm2O3 (all with a purity ≥ 99.9%) and grinding them thoroughly in an agate mortar for 30 minutes. After thorough grinding, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000 °C for 3 hours at a heating rate of 5 °C per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. The chemical composition of the product is: Sr9La 0.75 Sm 0.25 (VO4)7.

[0044] Comparative Example 1

[0045] According to the stoichiometric ratio of each element in the chemical formula Sr9La(VO4)7, 1.32867 g of SrCO3, 0.16292 g of La2O3, and 0.81893 g of NH4VO3 with a purity ≥99.9% were weighed and placed in an agate mortar and ground thoroughly for 30 min. After thorough grinding and homogenization, the samples were placed in a corundum crucible and calcined in a muffle furnace at 1000 ℃ for 3 h at a heating rate of 5 ℃ per minute. After natural cooling to room temperature, the samples were removed, ground, and the product was obtained. Its chemical composition expression is: Sr9La(VO4)7.

[0046] Performance testing: 1-Phase Analysis Four phosphors from Examples 1, 2, and 6, and Comparative Example 1, were tested using a Bruker D8 Advance X-ray diffractometer. The test conditions were: Cu Kα radiation, scanning range 10–90°, and scanning speed 5° / min. The results are as follows: Figure 1 As shown, all diffraction peaks are highly matched with the PDF#29-1318 standard card, which corresponds to pure-phase Sr3(VO4)2 material, indicating that Sr9La 1- x Sm x (VO4)7 phosphor has the same phase structure as pure-phase Sr3(VO4)2, and Sm 3+ The doping of ions did not affect the phase structure of the matrix lattice. From the principle of valence conservation, Sm... 3+ Ions may replace La in the matrix 3+ Site. Furthermore, Sm can be determined by calculating the percentage of ionic radius. 3+ Replace La 3+ Site.

[0047] To further investigate the microscopic variations in lattice parameters, the crystal structure of the sample from Example 1 was refined using GSAS refinement software based on the raw XRD data, as shown in the figure. Figure 2 As shown. During the refinement process, the crystal structure of Comparative Example 1 was used as the initial model, and parameters such as lattice parameters, atomic coordinates, and temperature factors were iteratively optimized. The spectra include experimental diffraction curves, calculated fitting curves, and residual curves. The refinement results show that the fitting curves are in high agreement with the experimental curves, the residual curves fluctuate little, and the reliability factors (such as Rwp and Rp) after refinement are all at low levels (usually Rwp < 10%), proving that the crystal structure model used is accurate.

[0048] 2-morphological structure

[0049] The microstructure of Example 1 was observed using a Zeiss LEO SUPRA 55 FE-SEM field emission scanning electron microscope. Figure 3As shown, the sample exhibits a clear agglomeration state, consisting of a large number of irregularly shaped particles. The particles are mostly irregular geometric shapes such as spherical or blocky, with slightly rough surfaces and some areas showing uneven or porous structures. The overall microscopic morphology is relatively loose.

[0050] 3-Photoluminescence emission spectrum

[0051] The photoluminescence emission spectra of samples from Examples 1-6 were measured using a Hitachi F-4700 spectrophotometer, such as... Figure 4 As shown. Excitation wavelength λ ex =373nm (near ultraviolet region), all samples showed Sm in the 400-720 nm range. 3+ The characteristic emission peaks of the ions correspond to, respectively 4 G 5 / 2 → 6 H 5 / 2 (567 nm) 4 G 5 / 2 → 6 H 7 / 2 (601 nm, main emission peak) 4 G 5 / 2 → 6 H 9 / 2 (646nm) transition. With Sm 3+ As the doping concentration x increases from 0.01 to 0.1, the intensity of the main emission peak gradually increases; when x > 0.1, the intensity of the main emission peak gradually decreases, exhibiting a concentration quenching effect. Specifically, the main emission peak intensity reaches its maximum value when x = 0.1 (Example 1), proving that this doping concentration is the optimal concentration and can achieve the best luminescence performance.

[0052] 4-CIE

[0053] The chromatic coordinates of Comparative Example 1 and Examples 1-6 samples under 373 nm excitation were calculated using emission spectra. The chromatic coordinates of Example 1 were (0.323, 0.397). The chromatic coordinates of samples with different doping concentrations were plotted on the 1931 CIE chromaticity diagram, and the results are shown below. Figure 5 As shown in the figure. Each point in the figure corresponds to a different Sm. 3+ Chromaticity coordinates of the doped sample. As x increases from 0 to 0.25, the prepared phosphor exhibits tunable emission characteristics, with the emission color gradually changing from green to near white.

[0054] 5- Thermal stability

[0055] To further investigate thermal quenching behavior, the temperature-dependent photoluminescence emission spectrum of Example 1 was tested using an Edinburgh FLS1000 in the temperature range of 298-573 K, with a temperature interval of 25 K. The results are as follows: Figure 6As shown, due to the thermal quenching effect, the integrated intensity of the photoluminescence emission spectrum changes significantly with temperature. Figure 7 As shown, in Example 1, the photoluminescence emission integral intensity at 423 K decreased to 24.2% of the initial value of 298 K. More significantly, within a certain temperature range in the high-temperature stage (above 498 K), the thermal quenching effect failed, achieving anti-thermal quenching performance (the emission integral intensity increased by 2.5% in the range of 498-573 K).

[0056] To better analyze the thermal quenching resistance behavior of the two luminescent centers, Figure 8 VO4 is given 3- With Sm 3+ The photoluminescence emission intensity of the luminescent center. Clearly, in Example 1, VO4... 3- The emission of the group exhibits a normal thermal quenching effect, decreasing to 14.5% of the initial emission intensity at 298 K at 423 K; while Sm 3+ Its emission performance is superior, maintaining 51.7% of the emission intensity at 298 K at 423 K, and exhibiting resistance to thermal quenching in the temperature range of 473-573 K. Specifically, Sm 3+ The emission intensity increased by 14.6% from 473 K to 573 K, ultimately making the emission intensity at 573 K much higher than at 423 K, equivalent to 65.2% of the initial emission intensity at 298 K.

[0057] 6-Sensitivity and Visualization of Thermometers

[0058] Because the temperature responses of the two luminescent centers are different, Example 1 is applied to a luminous intensity ratio (LIR) thermometer, such as... Figure 9 As shown, as the temperature increases from 298 K to 573 K, the experimentally measured LIR ( / The value increased from 1.714 to 49.410. The goodness of fit was high (R = 0.99874), indicating a high degree of agreement between the experimental data and the fitted curve. The performance of the optical thermometer is measured by its absolute sensitivity (S0). a ) and relative sensitivity (S r To evaluate, such as Figure 10 As shown, S a It reaches a maximum value of 0.664 K at 573 K. -1 And S r It reaches a maximum value of 1.7% at 457 K. -1 To visualize the thermometer, Figure 11The image shows physical images of Example 1 at different temperatures ranging from 298 to 523 K. It can be clearly seen that the sample emits near-white light under 365 nm ultraviolet light at room temperature, and the color changes from near-white to orange-red as the temperature increases. These results indicate that the phosphor of Example 1, with its extremely high temperature sensitivity, can be used to realize a visual non-contact optical thermometer.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A phosphor based on ultraviolet light excitation to produce near-white light, characterized in that, The phosphor is Sm 3+ Doped Sr9La(VO4)7, with the chemical formula Sr9La 1-x Sm x (VO4)7, where x satisfies 0<x≤0.

25.

2. The phosphor according to claim 1, characterized in that, x is 0.01, 0.05, 0.10, 0.15, 0.20 or 0.

25.

3. The phosphor according to claim 1, characterized in that, The phosphor exhibits full-spectrum emission under ultraviolet light excitation, covering the 400-700 nm visible region.

4. The phosphor according to claim 1, characterized in that, The phosphor exhibits tunable emission characteristics ranging from green to near-white light when excited by light at a wavelength of 373 nm.

5. The phosphor according to claim 1, characterized in that, The characteristic emission peak of the phosphor is Sm 3+ of 4 G 5 / 2 → 6 H 5 / 2 The transition emission peak corresponds to a center wavelength of 567 nm. 4 G 5 / 2 → 6 H 7 / 2 The transition emission peak corresponds to a center wavelength of 601 nm, and 4 G 5 / 2 → 6 H 9 / 2 The transition emission peak corresponds to a center wavelength of 646 nm.

6. The phosphor according to claim 1, characterized in that, The phosphor has the chemical formula Sr9La. 0.9 Sm 0.1 (VO4)7, under ultraviolet light excitation, its VO4 3- With Sm 3+ The emission intensity ratio changes systematically with temperature.

7. A method for preparing the phosphor according to any one of claims 1-6, characterized in that, Prepared in air using a high-temperature solid-state method, comprising the following steps: (1) According to the chemical formula Sr9La 1-x Sm x The stoichiometric ratios of each element in (VO4)7 were determined. Compounds containing Sr, La, Sm, and V were weighed as raw materials, with each raw material having a purity ≥99.9%. (2) Mix and grind the raw materials weighed in step (1) evenly to obtain a mixed powder; (3) The mixed powder obtained in step (2) is calcined in a high-temperature furnace at a temperature of 900-1100 ℃ for 2-4 h. (4) After cooling to room temperature, grind to obtain the phosphor.

8. The preparation method according to claim 7, characterized in that, In step (1), the Sr-containing compound is SrCO3; the La-containing compound is La2O3; the Sm-containing compound is Sm2O3; and the V-containing compound is NH4VO3.

9. The application of the phosphor according to any one of claims 1-6 in the field of optical thermometry.

10. The application according to claim 9, characterized in that, Within a detection temperature range of 298-573 K, the emission color of the phosphor under 365 nm ultraviolet light changes from near-white light to orange-red light as the temperature increases, thus realizing the visualization of non-contact optical temperature measurement.

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