Fluorescent temperature measuring material applied to multicolor anti-counterfeiting and preparation method thereof

Abstract

The application belongs to the field of rare earth (RE) up-conversion and down-conversion fluorescence temperature measurement sensing applied to anti-counterfeiting, and relates to a fluorescence temperature measurement material applied to multicolor anti-counterfeiting and a preparation method thereof. CsCl, NaCl, BiCl3 and RECl3·6H2O powders are weighed and mixed, wherein RE is Ho or Yb, and the mixed powders are mixed with an analytical pure HCL solution, the mixed solution is put into a teflon-lined autoclave, and the solution is reacted at a certain temperature, and after the reaction, colorless transparent crystal particles are observed through centrifugation and drying. The Cs2NaBiCl6 doped fluorescent powder prepared by the application has a thermal enhancement characteristic. The application belongs to the technical field of rare earth fluorescence temperature measurement sensors, and results show that the application is a multicolor light emitting and high sensitivity optical temperature measurement material, and is a multifunctional material that can be applied to anti-counterfeiting and fluorescence thermometers.

Description

Technical Field

[0001] This invention belongs to the field of rare earth (RE) up-conversion and down-conversion fluorescence thermometry sensing for anti-counterfeiting applications, specifically a fluorescence thermometry material and its preparation method for multi-color anti-counterfeiting. Background Technology

[0002] Counterfeit products are increasingly rampant and widespread worldwide, infiltrating every corner of daily life and causing serious losses and threats to national economies, corporate interests, and human lives. However, the most traditional and popular anti-counterfeiting patterns on the market, such as watermarks and QR codes, are easily copied and ineffective due to outdated technology and limited material availability. Fluorescent materials, due to their excellent information-hiding capabilities, have become one of the most popular anti-counterfeiting materials. However, common fluorescent anti-counterfeiting materials are easily imitated and replaced under ultraviolet or near-infrared light excitation, and their preparation process is often complex and cumbersome, limited by large and immobile testing tools. These problems require innovative solutions. This prompts us to invest more effort in designing multi-modal anti-counterfeiting measures to further improve security and ensure data and information security. Summary of the Invention

[0003] This invention provides an up-conversion and down-conversion fluorescent thermometric material and its preparation method for multi-color anti-counterfeiting applications. Based on the principle of up-conversion fluorescence, this material emits fluorescence of a specific wavelength when excited by a laser, and the fluorescence intensity is closely related to temperature. Therefore, by measuring the change in fluorescence intensity, the temperature change information of the sample can be obtained.

[0004] On the other hand, a method for preparing fluorescent thermometric materials for multi-color anti-counterfeiting is also provided.

[0005] The technical solution of this invention is as follows:

[0006] A method for preparing a fluorescent thermometric material for multi-color anti-counterfeiting applications, comprising: weighing CsCl, NaCl, BiCl3, and RECl3·6H2O powders, wherein RE is Ho and / or Yb, with Ho as a single dopant or a mixture of Ho and Yb as a dopant, and in the case of mixed doping, satisfying Cs2NaBi 1-z Cl6: z = x, y, xHo 3+ yYb 3+ x = 0.2, 0.4, 0.6, 0.8, y = 0.1, 0.2, 0.3, 0.4, 0.5; When single-doped, it satisfies Cs₂NaBi 1-x Cl6: Yb is zero, xHo 3+ , x=0.2, 0.4, 0.6, 0.8;

[0007] Each component was prepared into a mixed solution at a ratio of 1 mmol to 6 ml of hydrochloric acid solution;

[0008] The mixed solution was placed in a Teflon-lined autoclave for reaction, and Ho was obtained after centrifugation and drying. 3+ Single doping or Ho 3+ / Yb 3+ Co-doped Cs2NaBiCl6 phosphor.

[0009] Furthermore, after the mixed solution was placed in a Teflon-lined autoclave, it was reacted at 170°C for 12 hours. After centrifugation, it was washed three times with ethanol. The washed product was then dried at 60°C for 5 hours to obtain crystalline particles.

[0010] Furthermore, when Ho is doped alone, RE = Ho, and x = 0.2, the mass ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is 0.3308:0.0574:0.2478:0.0745.

[0011] When x = 0.4, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is: 0.3250:0.0564:0.1826: 0.1465;

[0013] When x = 0.6, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is: 0.3194:0.0554:0.1197: 0.2159;

[0015] When x = 0.8, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is: 0.3141g: 0.0545g: 0.0588g: 0.2831;

[0017] When Ho / Yb is co-doped, based on xHo 3+ When x = 0.4, and RE = Yb, y = 0.1, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3218:0.0559:0.1507:0.1450:0.0370;

[0018] When RE = Yb and y = 0.2, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3188:0.0553:0.1194:0.1437:0.0733;

[0019] When RE = Yb and y = 0.3, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3157:0.0548:0.0887:0.1423:0.1090;

[0020] When RE = Yb and y = 0.4, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3127:0.0543:0.0586:0.140:0.1440;

[0021] When RE = Yb and y = 0.5, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3098:0.0538:0.0290:0.1396:0.1783.

[0022] A fluorescent thermometric material for multi-color anti-counterfeiting applications, wherein the thermometric material is a Cs₂NaBiCl₆ phosphor single-doped or mixed-doped with Ho and Yb, wherein when mixed-doped, it satisfies the Cs₂NaBi 1-z Cl6: z = x, y, xHo 3+ yYb 3+ x = 0.2, 0.4, 0.6, 0.8, y = 0.1, 0.2, 0.3, 0.4, 0.5; When single-doped, it satisfies Cs₂NaBi 1-x Cl6: Yb is zero, xHo 3+ , x=0.2, 0.4, 0.6, 0.8.

[0023] The beneficial effects of this invention include:

[0024] The material has the following characteristics: (1) multi-color luminescence; (2) thermal enhancement; (3) easy to prepare and use, and applicable to various anti-counterfeiting fields.

[0025] A new technology material was proposed to address the issue that ordinary fluorescent anti-counterfeiting materials are easily imitated and replaced under ultraviolet or near-infrared excitation; Ho 3+ / Yb 3+ Single-doped and co-doped Cs₂NaBiCl₆ phosphors are thermally enhanced fluorescent thermometric materials used in multi-color anti-counterfeiting applications, suitable for both anti-counterfeiting and information encryption. The fluorescence intensity ratio technology based on rare-earth ion energy levels offers advantages such as rapid response, high sensitivity, and spatial resolution, thus rapidly becoming a research hotspot in the field of temperature detection. Compared to traditional fluorescent anti-counterfeiting materials, rare-earth-doped up- and down-conversion anti-counterfeiting materials possess broad development potential in the anti-counterfeiting field due to their excellent luminescent properties, low toxicity, high tunability, and good confidentiality.

[0026] Addressing the issue that traditional and popular anti-counterfeiting patterns, such as watermarks and QR codes, are easily copied and ineffective due to outdated technology and limited materials, this paper proposes a novel approach to anti-counterfeiting in the visible light region. Through a well-designed experiment, this approach effectively solves the problem of easy copying and unsatisfactory results associated with traditional anti-counterfeiting methods. Specifically, it utilizes a single-doped Ho... 3+ Optical properties of this fluorescent anti-counterfeiting material were tested under 980nm excitation (xHo). 3+ , x=0.2, 0.4, 0.6, 0.8), Figure 7 (a) Cs2NaBiCl6: 60% Ho 3+ The up-conversion emission spectra of the sample under excitation at 365, 452 and 980 nm, respectively. Figure 7 (b) shows the CIE coordinates of the sample under excitation at 365, 452, and 980 nm. From the figure, we can clearly see that the sample exhibits orange color under 365 nm excitation, red color under 452 nm excitation, and green color under 980 nm excitation. Co-doped Ho 3+ Optical property tests and temperature sensing property tests were conducted on this fluorescent anti-counterfeiting material. Figure 8 (a) Cs2NaBiCl6: 40% Ho 3+ / 10%Yb 3+ The up-conversion emission spectra of the sample under excitation at 452 and 980 nm, respectively. Figure 8 (b) shows the CIE coordinates of the sample under excitation at 452 nm and 980 nm. It is clear from the figure that the sample appears yellow under 452 nm excitation and green under 980 nm excitation. Temperature sensing characteristics experiments were conducted on this fluorescent thermometric material (at 40% Yb). 3+ As a sensitizer, doping with 40% Ho activator 3+ ), Figure 9 (a) is Cs2NaBiCl6:40% Ho 3+ / 40%Yb 3+ 3D mapping of the sample with downconversion band projection in the temperature range of 293 to 573 K. At the same pump power, Ho... 3+ Ion intensity near 464 nm 5 F1 / 5 G6→ 5 I8), intensity near 491nm ( 5 F3→ 5 I8), intensity near 546nm ( 5 F4 / 5 S2→ 5 I8) and around 658nm ( 5 F5 → 5The emission intensity of I8)Yb3+ increases with increasing temperature. Studies have shown that Cs2NaBiCl6:40%Ho 3+ / 40%Yb 3+ The sample exhibited a phenomenon of enhanced luminescence and thermal activity. Figure 9 (b) is Cs2NaBiCl6:40% Ho 3+ / 40%Yb 3+ Normalized spectra of the sample in the temperature range of 293 to 573 K. Figure 10 (a)-(f) is Cs2NaBiCl6:40% Ho 3+ / 40%Yb 3+ LIR, S from 293 to 573K A S R picture. Attached Figure Description

[0027] Figure 1 This is a flowchart of the solvothermal method for preparing materials provided in an embodiment of the present invention;

[0028] Figure 2 This is a flowchart of the up-conversion and down-conversion spectra of Cs2NaBiCl6 phosphor provided in an embodiment of the present invention;

[0029] Figure 3 XRD pattern of Cs2NaBiCl6: (a) xHo 3+ (b) 0.4Ho 3+ / y%Yb 3+ ;

[0030] Figure 4 Rietveld refinement plot of Cs2NaBiCl6: (a) 0.6Ho 3+ (b) 0.4Ho 3+ / 0.1Yb 3+ ;

[0031] Figure 5 Schematic diagram of the crystal structure of Cs2NaBiCl6;

[0032] Figure 6 (a) SEM structure of Cs₂NaBiCl₆; (b)-(e) are schematic diagrams of EDS elemental distribution: 0.4Ho 3+ / 0.2Yb 3+ ;

[0033] Figure 7 (a) Cs2NaBiCl6: 0.6Ho 3+ (a) Up-conversion emission spectra of the sample at 980, 365, and 452 nm excitation; (b) Cs₂NaBiCl₆: 0.6Ho 3+CIE coordinates of the sample under excitation at 365, 452 and 980 nm;

[0034] Figure 8 (a) Cs₂NaBiCl₆: 0.4Ho 3+ / 0.1Yb 3+ (a) Up-conversion emission spectra of the sample under excitation at 980 nm and 452 nm, respectively; (b) CIE coordinates of the sample under excitation at 980 nm and 452 nm, respectively;

[0035] Figure 9 (a) Cs₂NaBiCl₆: 0.4Ho 3+ / 0.4Yb 3+ (a) 3D mapping of the downconversion emission peak versus temperature band projection at 293-573 K; (b) Cs₂NaBiCl₆: 0.4Ho 3+ / 0.4Yb 3+ Normalized curves of phosphor at 464nm, 491nm, 546nm, and 658nm as a function of temperature in the range of 293-573K;

[0036] Figure 10 (a)-(h) is Cs2NaBiCl6:0.4Ho 3+ / 0.4Yb 3+ LIR, SA, and SR plots at 273-573 K. (a)-(b) represent temperature sensing based on thermally coupled energy levels; (c)-(h) represent temperature sensing based on non-thermally coupled energy levels.

[0037] Figure 11 Cs2NaBiCl6:0.6Ho 3+ Anti-counterfeiting patterns prepared from samples. Among them, (a) is Cs₂NaBiCl₆: 0.6Ho 3+ (a) Sample powder; (b)-(c) Pattern template; (d)-(g) Pattern "stars" prepared on black cardboard, showing orange, dark red and light green under laser excitation at 365nm, 452nm and 980nm; (h) Pattern "bird" and "branch" prepared on black cardboard, colored patterns under laser excitation at 365nm, 452nm and 980nm. Detailed Implementation

[0038] The invention will now be further described with reference to the accompanying drawings and schematic diagrams of experimental phenomena.

[0039] A method for preparing a fluorescent thermometric material for multi-color anti-counterfeiting applications, comprising: weighing CsCl, NaCl, BiCl3, and RECl3·6H2O powders, wherein RE is Ho and / or Yb, with Ho as a single dopant or a mixture of Ho and Yb as a dopant, and in the case of mixed doping, satisfying Cs2NaBi1-z Cl6: z = x, y, xHo 3+ yYb 3+ x = 0.2, 0.4, 0.6, 0.8, y = 0.1, 0.2, 0.3, 0.4, 0.5; When single-doped, it satisfies Cs₂NaBi 1-x Cl6: Yb is zero, xHo 3+ x = 0.2, 0.4, 0.6, 0.8; it should be noted that Ho here 3+ and Yb 3+ The molar content refers to that of Ho, which is based on Bi. 3+ When the total molar amount of Bi is taken as 1, for x = 0.2, 0.4, 0.6, 0.8, Bi is 1-x. Similarly, Yb 3+ When the total molar amount of Bi is taken as 1, y = 0.1, 0.2, 0.3, 0.4, 0.5;

[0040] Each component was prepared into a mixed solution at a ratio of 1 mmol to 6 ml of hydrochloric acid solution;

[0041] The mixed solution was placed in a Teflon-lined autoclave for reaction, and Ho was obtained after centrifugation and drying. 3+ Single doping or Ho 3+ / Yb 3+ Co-doped Cs2NaBiCl6 phosphor.

[0042] After the mixed solution was placed in a Teflon-lined autoclave, it was reacted at 170°C for 12 hours. After centrifugation, it was washed three times with ethanol. The washed product was then further dried at 60°C for 5 hours to obtain crystalline particles.

[0043] When Ho is added as the sole dopant, RE = Ho, and x = 0.2, the mass ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is 0.3308:0.0574:0.2478:0.0745.

[0044] When x = 0.4, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is: 0.3250:0.0564:0.1826: 0.1465;

[0046] When x = 0.6, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is: 0.3194:0.0554:0.1197: 0.2159;

[0048] When x = 0.8, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O is: 0.3141g: 0.0545g: 0.0588g: 0.2831;

[0050] When Ho / Yb is co-doped, based on Ho 3+ When x = 0.4, and RE = Yb, y = 0.1, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3218:0.0559:0.1507:0.1450:0.0370;

[0051] When RE = Yb and y = 0.2, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3188:0.0553:0.1194:0.1437:0.0733;

[0052] When RE = Yb and y = 0.3, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3157:0.0548:0.0887:0.1423:0.1090;

[0053] When RE = Yb and y = 0.4, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3127:0.0543:0.0586:0.140:0.1440;

[0054] When RE = Yb and y = 0.5, the ratio of CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O is: 0.3098:0.0538:0.0290:0.1396:0.1783.

[0055] Figure 1 Ho was synthesized by solvothermal method 3+ / Yb 3+ Flowchart of single-doped and co-doped Cs₂NaBiCl₆ phosphors. The experimental raw materials were high-purity CsCl, NaCl, BiCl₃, HoCl₃·6H₂O, and YbCl₃·6H₂O powders, weighed according to their molar ratios, and mixed with an appropriate amount of hydrochloric acid to prepare a solution. The mixed solution was placed in an autoclave with a Teflon liner and reacted at 170℃ for 12 h. After centrifugation, the solution was washed three times with ethanol, and crystalline particles were observed. The product was then further dried at 60℃ for 5 h. Finally, HoCl₂ was obtained. 3+ / Yb 3+ Single-doped and co-doped Cs2NaBiCl6 phosphors were studied, and their structure, temperature and optical properties were further investigated. Figure 2This is a flowchart of the experimental procedure for sensing the up-conversion temperature of Cs₂NaBiCl₆ phosphor. The main components are a 980nm diode laser, a xenon lamp, a λ500 spectrometer, a photon counter, and a computer. XRD and SEM characterization of Cs₂NaBiCl₆ shows its class... Space group, regular octahedral structure, is an excellent material for preparing phosphors; the temperature sensing characteristics of the prepared material can be controlled with an accuracy of 0.1℃;

[0056] This invention involves uniformly mixing liquid raw materials that require element incorporation; and then sintering and drying them to produce usable materials. The temperature must be strictly controlled, as this will directly affect the performance of the final synthesized material.

[0057] In this embodiment, CsCl, NaCl, BiCl3, HoCl3·6H2O and YbCl3·6H2O were weighed at 1 mol / g and mixed with hydrochloric acid in a high-pressure reactor with a Teflon liner. The amounts of each component are shown in Table 1 and Table 2.

[0058] Table 1 (Single-doped xHo) 3+ )

[0059]

[0060] Table 2 (Co-doped with 0.4 Ho) 3+ / yYb 3+ )

[0061]

[0062] The obtained product was measured using an X-ray diffractometer (Rigaku Ultima IV) to determine the experimentally prepared Ho. 3+ / Yb 3+ The phosphors are Cs₂NaBiCl₆ phosphors with single-doped and co-doped varieties. The radiation source is Cu-Kα rays with a wavelength of λ = 0.15406 nm and a 2θ angle range of 10-90° (2θ degrees). Figure 3 (a) and (b) show Ho 3+ / Yb 3+ XRD patterns of single-doped and co-doped Cs₂NaBiCl₆ phosphors. It can be seen that the diffraction peaks of the samples correspond one-to-one with those of the Cs₂NaBiCl₆ standard card (PDF#77-1831), and the peaks are sharp, indicating that the samples have good crystallinity and that the resulting samples are pure phases. 3+ / Yb 3+Ions have been completely doped into the Cs₂NaBiCl₆ matrix lattice. Refinement of the XRD patterns using GsasII software allows for estimation of approximate values ​​between the structural model and the actual structure based on power intensity distribution measurements. This is because many unavoidable errors occur in experiments, and the properties of crystal materials vary. Refinement, i.e., adjusting various parameters, can alter the peak size, shape, and position of the reference curve. By comparing the reference curve with the experimental curve, errors can be calculated, thus obtaining the desired experimental results. Figure 4 In (a, b), Cs2NaBiCl6:60% Ho is shown. 3+ And Cs2NaBiCl6:40%Ho 3+ / 10%Yb 3+ The XRD Rietveld refinement results of the samples were presented. The experiments also investigated in detail the measurement, calculation, Bragg position, and differences between the experimental and calculated diffraction patterns. The suggested theoretical adjustments are consistent with the analytical results, where small differences in intensity scaling close to zero can be observed, as shown by the line (Obs Calc). This was achieved by adjusting 60% Ho... 3+ and 40% Ho 3+ / 10%Yb 3+ The sample was refined using Rietveld refinement to obtain lattice parameters such as cell volume.

[0063] Crystal data from an open crystallography database were used as the initial model for structure refinement. The calculated values ​​of the refinement results showed a high correlation with the actual theoretical values. Space group, cell parameters, unit cell volume, and feasibility factor are given in Table 3.

[0064] Table 3

[0065]

[0066] Based on the parameters of the XRD Rietveld refinement results, Cs2NaBiCl6 belongs to... The space group is octahedral, and the refined results were imported into VESTA software to plot the unit cell structure of the sample, as shown below. Figure 5 Cs + Bi 3+ Na + Both Cl- are located at the characteristic position. A query reveals that Ho... 3+ / Yb 3+ The ionic radius is And Bi 3+ The ionic radius is According to crystal chemistry, Ho is used here. 3+ For example, Ho 3+ The ionic radius is Ho3+ with Bi 3+ The ionic radii differ by 12.52%. Based on the principle that ionic radii with the same valence state are similar, this invention suggests that when the ionic radii differ by less than 30%, Ho... 3+ It can better occupy Bi 3+ lattice sites.

[0067] The morphology of the samples was recorded using a JEOL scanning electron microscope (FE-SEM, Quanta 450, FEI). Figure 6 (a)-(e) is Ho 3+ / Yb 3+ SEM images and EDS elemental distribution maps of co-doped Cs2NaBiCl6 phosphors reveal that the sample consists of smooth crystalline particles that have reached the micrometer scale, and the elements are evenly distributed.

[0068] The converted emission spectra were recorded using an Omni-K500 spectrometer (Zolix, China) under excitation by a 980nm laser (MDL-III-980-2W, China) and a xenon lamp (Gloria-X150A 150W) at 365nm and 452nm, respectively. Temperature sensing characteristics were measured using a TAP-02 high-temperature controller to control the sample temperature, within the range of 293K–573K. The temperature control accuracy was 0.1℃.

[0069] Figure 9 (a) is Cs2NaBiCl6:40% Ho 3+ / 40%Yb 3+ 3D mapping of the sample with downconversion band projection in the temperature range of 293 to 573 K. At the same pump power, Ho... 3+ Ion intensity near 464 nm 5 F1 / 5 G6→ 5 I8), intensity near 491nm ( 5 F3→ 5 I8), intensity near 546nm ( 5 F4 / 5 S2→ 5 I8) and around 658nm ( 5 F5 → 5 I8)Yb 3+ The emission intensity increases with increasing temperature. Studies have shown that Cs₂NaBiCl₆:40%Ho 3+ / 40%Yb 3+ The sample exhibited a phenomenon of enhanced luminescence and thermal activity. Figure 9 (b) is Cs2NaBiCl6:40% Ho 3+ / 40%Yb 3+Normalized spectra of the sample in the temperature range of 293 to 573 K.

[0070] Figure 10 (a)-(b) are Cs2NaBiCl6:40% Ho 3+ / 40%Yb 3+ In the range of 293 to 573 K, based on thermal coupling and (c)-(h) non-thermal coupling energy LIR, S A S R Figure. The LIR values ​​all increase with increasing temperature, where I... 658 nm / I 546 nm The maximum relative sensitivity of 5.089% K is achieved at 293 K. -1 In conclusion, Cs₂NaBiCl₆ phosphor is a promising multicolor anti-counterfeiting material that can be used in the development of anti-counterfeiting labels and information encryption.

[0071] Figure 11 Cs2NaBiCl6:60%Ho 3+ Anti-counterfeiting patterns prepared from the samples. Among them, (a) is Cs₂NaBiCl₆: 60% Ho 3+ (a) Sample powder; (b)-(c) Pattern template; (d)-(g) Pattern "stars" prepared on black cardboard, showing orange, dark red and light green under laser excitation at 365nm, 452nm and 980nm; (h) Pattern "bird" and "branch" prepared on black cardboard, colored patterns under laser excitation at 365nm, 452nm and 980nm.

Claims

1. The application of a multi-color anti-counterfeiting fluorescent material as a fluorescent thermometric material, characterized in that, The preparation method of this material includes: weighing CsCl, NaCl, BiCl3, and RECl3·6H2O powders, wherein RE is Ho and Yb, satisfying Cs2NaBi 1-z Cl6: z = x + y, x + y < 1, xHo 3+ yYb 3+ x = 0.2, 0.4, 0.6, 0.8, y = 0.1, 0.2, 0.3, 0.4, 0.5; and prepare a mixed solution by mixing with hydrochloric acid solution; The mixed solution was placed in a Teflon-lined autoclave for reaction, and Ho was obtained after centrifugation and drying. 3+ Single doping or Ho 3 + / Yb 3+ Co-doped Cs2NaBiCl6 phosphor.

2. The application according to claim 1, characterized in that, After the mixed solution was placed in a Teflon-lined autoclave, it was reacted at 170°C for 12 hours. After centrifugation, it was washed three times with ethanol. The washed product was then further dried at 60°C for 5 hours to obtain crystalline particles.

3. The application according to claim 1, characterized in that, When x=0.4 and y=0.1, the CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O ratio is: 0.3218：0.0559：0.1507：0.1450：0.0370； When y=0.2, the CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O ratio is: 0.3188：0.0553：0.1194：0.1437：0.0733； When y=0.3, the CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O ratio is: 0.3157：0.0548：0.0887：0.1423：0.1090； When y=0.4, the CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O ratio is: 0.3127：0.0543：0.0586：0.140：0.1440； When y=0.5, the CsCl:NaCl:BiCl3:HoCl3·6H2O:YbCl3·6H2O ratio is: 0.3098：0.0538：0.0290：0.1396： 0.1783。 4. The application according to claim 1, characterized in that, The total amount of each component was mixed at a ratio of 1 mmol to 6 ml of hydrochloric acid solution.

Images