A Cu-doped green fluorescent material with adjustable afterglow 2+ Its preparation, afterglow adjustment and encryption method

Abstract

The present invention discloses a Cu<supgt;2+< / supgt>-doped green fluorescent material with tunable afterglow achieved by changing the preparation conditions. This material is a novel optical material with a wide emission band (~120 nm) and long afterglow performance (~30 minutes). In addition, with the change of the preparation conditions, the fluorescence emission intensity changes, the defect concentration increases (9.26 times), and the afterglow time extends (~30 minutes), thus realizing the process of tunable afterglow. The afterglow modulation defect engineering strategy in the present invention may further inspire innovative ideas for preparing high-performance optical information storage and high-performance long-afterglow materials with encryption.

Description

Technical Field

[0001] The present invention relates to the field of solid luminescent materials, and particularly to a Cu2+-doped green fluorescent material with adjustable afterglow, and its preparation, afterglow adjustment and encryption method. Background Art

[0002] With the rapid development of the information age, people are increasingly concerned about the pitfalls brought by information security. Storing and encrypting information in a more secure way is an increasingly urgent need. Therefore, materials with optical information storage and anti-counterfeiting properties have received extensive attention. Optical information storage has the advantages of low energy consumption, long lifespan, large capacity, etc., and plays an indispensable role in modern information storage networks. Due to the limitation of two-dimensional spatial resolution, optical discs, digital video discs and Blu-ray discs are facing more and more challenges. In addition, due to the lack of suitable optical storage media, practical applications are still very difficult. Therefore, developing new and advanced optical materials must meet the needs of modern information storage.

[0003] Persistent luminescent phosphors can store light energy in advance and then release persistent afterglow emission. Long afterglow luminescent materials have unique energy storage and controlled photon release characteristics under additional stimulation, thus enabling high-capacity storage in the next-generation information storage system. However, the lack of suitable tunable long afterglow luminescent materials is the bottleneck of this type of storage technology. Currently, the vast majority of long afterglow phosphors used for optical information storage and encryption mostly interpret the "writing" and "reading" of information storage with a single afterglow effect or multicolor effect in the emission band. For example: BaGa2O4:Bi 3+ , Li2CaSiO4:Pr 3+ etc. Therefore, the existing technology needs to be improved. Summary of the Invention

[0004] In view of the above deficiencies of the existing technology, the first object of the present invention is to address the existing limitations in optical information storage and encryption, and propose a Cu 2+ -doped green fluorescent material with adjustable afterglow by changing the preparation conditions, which is expected to be applied to the fields of optical information storage and encryption, aiming to solve the problems raised in the above background art.

[0005] The first aspect of the present invention aims to provide a Cu 2+ -doped green fluorescent material with adjustable afterglow, whose chemical general formula is LiGaO2:xCu 2+ ; wherein, 0.001 ≤ x ≤ 0.03;

[0006] The crystal structure of the Cu 2+ -doped green fluorescent material is based on LiGaO2, and Cu 2+ substitutes the lattice site of Ga in the matrix to form doping, obtaining LiGaO2:Cu2+ Green long afterglow fluorescent material;

[0007] The afterglow is adjustable means that by adjusting the Cu 2+ The concentration of lattice defects in doped green fluorescent materials regulates the afterglow time;

[0008] The Cu 2+ When the doped green fluorescent material is excited by 355-nanometer ultraviolet light, its strongest emission peak is at 540 nanometers, the half-peak width is 120 nanometers, and the afterglow time is between 1 minute and 30 minutes.

[0009] The present invention also provides a Cu with adjustable afterglow 2+ The preparation method of doped green fluorescent material comprises the following steps:

[0010] Step (1), using a compound containing lithium ions, a compound containing gallium ions, and a compound containing copper ions as raw materials, according to the chemical formula LiGaO2:xCu 2+ The molar ratio of lithium, gallium and copper is used to weigh the raw materials; wherein 0.001≤x≤0.03;

[0011] Step (2), mixing and fully grinding the raw materials weighed in step (1), and pre-calcining after grinding to obtain a mixture;

[0012] Step (3), the mixture obtained after pre-sintering in step (2) is naturally cooled to room temperature, fully ground, and then sintered. After the sintering process is completed, it is naturally cooled to room temperature to obtain a LiGaO2:xCu 2+ Long-lasting gallate phosphor.

[0013] Preferably, in step (1), the compound containing lithium ions is any one or more combinations of Li2CO3, LiF2, and LiOH; the compound containing gallium ions is any one or two combinations of Ga2O3 and GaCl3; and the compound containing copper ions is CuO.

[0014] Preferably, the pre-firing in step (2) is carried out in an air atmosphere.

[0015] Preferably, the sintering in step (3) is carried out in an air atmosphere.

[0016] Preferably, in step (3), the sintering temperature is 900-1300° C., and the sintering time is 4-24 hours.

[0017] Preferably, in step (2), the pre-firing temperature is 300-500° C., and the pre-firing time is 4-8 hours.

[0018] The present invention also provides a method for adjusting the afterglow of a Cu 2+ doped green fluorescent material, which adjusts the afterglow time of the product by changing the sintering time described in step (3).

[0019] Preferably, the calcination time is adjusted as follows: when the calcination time is 4 hours, the afterglow time of the product is 0.5 - 1.5 minutes; when the calcination time is 12 hours, the afterglow time of the product is 9 - 11 minutes; when the calcination time is 24 hours, the afterglow time of the product is 25 - 35 minutes.

[0020] The present invention also provides a method for information storage and encryption using the above-mentioned afterglow adjustment method. A number of Cu 2+ doped green fluorescent materials with different afterglow times are prepared according to a preset calcination time; the information to be encrypted is obtained, and the above-mentioned number of Cu 2+ doped green fluorescent materials are used to encode the information to be encrypted to complete information storage and encryption; ultraviolet light in the wavelength range of 355 - 365 nm is used to excite a number of Cu 2+ doped green fluorescent materials, and the afterglow time of each Cu 2+ doped green fluorescent material is recorded, and decoding is performed based on the afterglow time to obtain the information to be encrypted.

[0021] The fluorescent material is excited by ultraviolet light with a wavelength of 355 nm. The phosphor is excited to emit a broad emission peak with a peak position at 540 nm and a long afterglow performance of about 30 minutes. By changing the sintering time, the internal defect structure of the material is affected, thereby achieving the control of the long afterglow performance in the time range of 1 minute - 30 minutes. The length of the afterglow before and after adjustment is different, and this material can realize a new type of optical information storage and encryption.

[0022] Beneficial effects: The present invention proposes a Cu 2+ doped green fluorescent material with adjustable afterglow by changing the preparation conditions. This material is a new type of optical material with a broad emission band (~120 nm) and long afterglow performance (~30 minutes). In addition, with the change of the preparation conditions, the fluorescence emission intensity changes, the defect concentration increases (9.26 times), and the afterglow time extends (~30 minutes), thereby realizing the process of adjustable afterglow. The afterglow modulation defect engineering strategy in the present invention may further inspire innovative ideas for preparing high-performance optical information storage and encryption high-performance long afterglow materials. Description of the Drawings

[0023] Figure 1 It is the excitation and emission spectrum of the phosphor prepared according to Example 1 under 355 nm ultraviolet light excitation;

[0024] Figure 2Diffuse reflection absorption spectrum of the phosphor prepared according to Example 1. The inset shows the relationship between the absorption coefficient and the photon energy;

[0025] Figure 3 Emission spectra of the phosphor prepared according to Example 3 at different times after 10 minutes of ultraviolet excitation;

[0026] Figure 4 Long afterglow decay curves of the phosphors prepared according to Examples 1, 2, and 3;

[0027] Figure 5 、 6 Thermoluminescence spectra of the phosphors prepared according to Examples 1, 2, and 3 under different sintering time conditions;

[0028] Figure 7 Excitation and emission spectra of the phosphors prepared according to Examples 1, 8, 9, and 10 under different temperature and time conditions;

[0029] Figure 8 Excitation and emission spectra of the phosphors prepared according to Examples 1, 2, and 3 under different sintering time conditions;

[0030] Figure 9 Afterglow comparison diagrams of the phosphors prepared according to Examples 1, 2, and 3 under different sintering time conditions taken by a camera;

[0031] Figure 10 X-ray diffraction patterns, refined X-ray diffraction patterns, and lattice constant change diagrams of the phosphors prepared according to Examples 1, 4, 5, 6, and 7. Detailed implementation mode

[0032] The present invention will be analyzed in detail below in conjunction with specific embodiments. The following embodiments are intended to illustrate the present invention, and any improvements and changes made on the basis of the present invention are within the protection scope of the present invention.

[0033] A Cu 2+ -doped green fluorescent material with adjustable afterglow achieved by changing preparation conditions, characterized in that the matrix of the fluorescent material is metal gallate, and the doping components include Cu 2+ . It is characterized in that the molar percentage of the doped Cu 2+ is [0.001, 0.03]. Since the afterglow effect changes with the change of the sintering time, and the emission intensity changes with the change of the sintering temperature. Optical information storage and encryption can be realized by adjusting the preparation of materials by the solid-phase sintering method.

[0034] The preparation method used in the above technical solution adopts the high-temperature solid-phase sintering method, based on the following steps:

[0035] Step (1): Compounds containing lithium ions, compounds containing gallium ions, and compounds containing copper ions are used as raw materials, and weighed according to the stoichiometric ratios of the elements in the chemical formula LiGaO2:xCu 2+ ; where x is the molar percentage of copper ion Cu 2+ doping, and 0.001 ≤ x ≤ 0.03 is taken;

[0036] Step (2): The powders weighed in step (1) are mixed and thoroughly ground. After being ground evenly, they are placed in a crucible and pre-fired in an air atmosphere. The pre-firing temperature is 300 - 500 °C, and the pre-firing time is 4 - 8 hours;

[0037] Step (3): The mixture obtained after pre-firing in step (2) is naturally cooled to room temperature, and then thoroughly and evenly ground again. It is sintered in an air atmosphere. The sintering temperature is 900 - 1300 °C, and the sintering time is 4 - 24 hours. After the sintering process is completed, it is allowed to cool naturally to room temperature to obtain a gallate phosphor with the chemical formula LiGaO2:xCu 2+ with long afterglow performance;

[0038] Furthermore, the compound containing Li ions in step (1) is one or more of Li2CO3 and LiOH; the compound containing gallium ions in step (1) is Ga2O3; the compound containing copper ions in step (1) is CuO.

[0039] Example 1: Preparation of LiGaO2:0.001Cu 2+ phosphor.

[0040] According to the stoichiometric ratios of the elements in the chemical formula LiGaO2:0.001Cu 2+ , 0.1843 g of Na2CO3, 0.4685 g of Ga2O5, and 0.0004 g of CuO are respectively weighed and placed in an agate mortar for thorough and even grinding, and then placed in a crucible. They are pre-fired in an air atmosphere. The pre-firing temperature is 400 °C, and the time is 8 hours. After being naturally cooled to room temperature, they are ground again, and then calcined in an air atmosphere. The calcination temperature is 900 °C, and the time is 4 hours. When the furnace temperature is naturally cooled to room temperature, the target product LiGaO2:0.001Cu 2+ is obtained.

[0041] The fluorescence spectrum of this phosphor is characterized by a fluorescence spectrometer, and the emission peaks generated by copper ions can be detected. The intensity peak position is at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is about 1 minute.

[0042] Example 2: Preparation of LiGaO2:0.001Cu 2+ phosphor

[0043] According to the stoichiometric ratios of the elements in the chemical formula LiGaO₂:0.001Cu 2+ Weigh out Na₂CO₃: 0.1843 g, Ga₂O₅: 0.4685 g, and CuO: 0.0004 g respectively and place them in an agate mortar. After sufficient and uniform grinding, place them in a crucible and pre-burn in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind again and then calcine in an air atmosphere. The calcination temperature is 900 °C and the time is 12 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO₂:0.001Cu is obtained 2+ .

[0044] Characterize the fluorescence spectrum of the phosphor by a fluorescence spectrometer, and the emission peaks generated by copper ions can be detected. The intensity peak is at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is about 10 minutes

[0045] Example 3: Preparation of LiGaO₂:0.001Cu 2+ Phosphor

[0046] According to the stoichiometric ratios of the elements in the chemical formula LiGaO₂:0.001Cu 2+ Weigh out Na₂CO₃: 0.1843 g, Ga₂O₅: 0.4685 g, and CuO: 0.0004 g respectively and place them in an agate mortar. After sufficient and uniform grinding, place them in a crucible and pre-burn in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind again and then calcine in an air atmosphere. The calcination temperature is 900 °C and the time is 24 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO₂:0.001Cu is obtained 2+ .

[0047] By exciting the phosphor with a 355-nm ultraviolet excitation source, the excitation-emission spectra of different Cu doping concentrations of the phosphor can be obtained ( 2+ ). From the diffuse reflection absorption spectrum of the prepared phosphor, the inset shows the relationship between the absorption coefficient and the photon energy, and its band gap reaches 5.79 electron volts ( Figure 1 ). At the same time, the phosphor is energized for 10 min under ultraviolet lamp excitation, and then the emission spectrum composition spectrum is measured at regular intervals after turning off the light source. At the same time, it can be observed that there is a 10-nm blue shift phenomenon while the afterglow decays ( Figure 2 ). The long afterglow decay curves of the three prepared phosphors were tested, and it can be seen that the initial intensity of the afterglow decay curve of the sample with a longer sintering time is higher and the decay rate is slower ( Figure 3 ). Figure 4)。The test of the thermoluminescence curve can explain the phenomenon that the afterglow intensity changes through trap changes. It can be found from the thermoluminescence spectra of the same 900 °C with different sintering times (4 h, 12 h, 24 h) that the trap concentration increases by 9.26 times as the sintering time prolongs. Therefore, the afterglow time is correspondingly prolonged ( Figure 5 ), and then after irradiating the same sample with an ultraviolet lamp for 10 minutes, thermoluminescence tests are carried out at regular intervals (10 s, 30 s, 1 min, 10 min, 30 min). It can be found that as time goes by, the curve gradually decreases, verifying that the internal electrons escape from the traps regularly under the action of temperature and act on the afterglow phenomenon ( Figure 6 ). It is worth mentioning that when the sintering temperature is changed while keeping the material still in the pure phase, the emission intensity of the material will also change to a certain extent ( Figure 7 ). Figure 8 When the sintering temperature is 900 °C, there are also certain differences in the emission intensities at 4 h, 12 h, and 24 h. Using a camera to shoot can more intuitively observe the phenomenon of the afterglow change of the three phosphors within 30 minutes ( Figure 9 ). It can be observed from the X-ray diffraction pattern that the doped phosphor material is the pure phase of LiGaO2, and the diffraction peaks tend to shift to small angles, which is attributed to the substitution of larger-radius copper ions for smaller-radius gallium ion lattice sites, resulting in lattice expansion, and the lattice constant also shows an increasing trend. Refining the X-ray diffraction pattern verifies that the obtained material has good phase purity.

[0048] By characterizing the fluorescence spectrum of the phosphor with a fluorescence spectrometer, the copper ions and the generated emission peaks can be detected. The intensity peak position is at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is about 30 minutes.

[0049] Example 4: Preparation of LiGaO2:0.005Cu 2+ phosphor

[0050] According to the stoichiometric ratios of the elements in the chemical formula LiGaO2:0.005Cu 2+ , weigh 0.1843 g of Na2CO3, 0.4685 g of Ga2O5, and 0.002 g of CuO respectively and place them in an agate mortar for sufficient and uniform grinding, then place them in a crucible, pre-burn in an air atmosphere, the pre-burning temperature is 400 °C, and the time is 8 hours. After natural cooling to room temperature, grind again, and then calcine in an air atmosphere, the calcination temperature is 900 °C, and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO2:0.005Cu is obtained 2+ .

[0051] The fluorescence spectrum of this phosphor was characterized by a fluorescence spectrometer, and copper ions and the generated emission peaks could be detected. The peak intensity was at 540 nm, the full width at half maximum was 120 nm, and the afterglow was about 1 minute.

[0052] Example 5: Preparation of LiGaO2:0.01Cu 2+ Phosphor

[0053] According to the stoichiometric ratios of the elements in the chemical formula LiGaO2:0.01Cu 2+ Weigh 0.1843 g of Na2CO3, 0.4685 g of Ga2O5, and 0.004 g of CuO respectively and place them in an agate mortar for sufficient and uniform grinding. Then place them in a crucible and pre-burn them in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind them again and then calcine them in an air atmosphere. The calcination temperature is 900 °C and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO2:0.01Cu is obtained. 2+ .

[0054] The fluorescence spectrum of this phosphor was characterized by a fluorescence spectrometer, and copper ions and the generated emission peaks could be detected. The peak intensity was at 540 nm, the full width at half maximum was 120 nm, and the afterglow was about 1 minute.

[0055] Example 6: Preparation of LiGaO2:0.02Cu 2+ Phosphor

[0056] According to the stoichiometric ratios of the elements in the chemical formula LiGaO2:0.01Cu 2+ Weigh 0.1843 g of Na2CO3, 0.4685 g of Ga2O5, and 0.008 g of CuO respectively and place them in an agate mortar for sufficient and uniform grinding. Then place them in a crucible and pre-burn them in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind them again and then calcine them in an air atmosphere. The calcination temperature is 900 °C and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO2:0.02Cu is obtained. 2+ .

[0057] The fluorescence spectrum of this phosphor was characterized by a fluorescence spectrometer, and copper ions and the generated emission peaks could be detected. The peak intensity was at 540 nm, the full width at half maximum was 120 nm, and the afterglow was about 1 minute.

[0058] Example 7: Preparation of LiGaO2:0.03Cu 2+ Phosphor

[0059] According to the stoichiometric ratios of the elements in the chemical formula LiGaO2:0.03Cu 2+For the stoichiometric ratios of the elements in [chemical formula], weigh out Na2CO3: 0.1843 g, Ga2O5: 0.4685 g, and CuO: 0.012 g respectively and place them in an agate mortar for sufficient and uniform grinding. Then place them in a crucible and pre-burn in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind again and then calcine in an air atmosphere. The calcination temperature is 900 °C and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO2:0.03Cu is obtained. 2+ 。

[0060] The phosphor is characterized by a fluorescence spectrometer for its fluorescence spectrum. The emission peaks generated by copper ions can be detected. The peak intensity is at 540 nm, the full width at half maximum is 120 nm, and the afterglow is about 1 minute.

[0061] Example 8: Preparation of LiGaO2:0.001Cu 2+ phosphor.

[0062] According to the stoichiometric ratios of the elements in the chemical formula LiGaO2:0.001Cu 2+ weigh out Na2CO3: 0.1843 g, Ga2O5: 0.4685 g, and CuO: 0.0004 g respectively and place them in an agate mortar for sufficient and uniform grinding. Then place them in a crucible and pre-burn in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind again and then calcine in an air atmosphere. The calcination temperature is 1000 °C and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO2:0.001Cu is obtained. 2+ 。

[0063] The phosphor is characterized by a fluorescence spectrometer for its fluorescence spectrum. The emission peaks generated by copper ions can be detected. The peak intensity is at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is about 1 minute.

[0064] Example 9: Preparation of LiGaO2:0.001Cu 2+ phosphor.

[0065] According to the chemical formula LiGaO2:0.001Cu 2+For the stoichiometric ratios of the elements in [LiGaO₂:0.001Cu], weigh out 0.1843 g of Na₂CO₃, 0.4685 g of Ga₂O₅, and 0.0004 g of CuO respectively, and place them in an agate mortar for sufficient and uniform grinding. Then place them in a crucible and pre-burn in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind again and then calcine in an air atmosphere. The calcination temperature is 1200 °C and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO₂:0.001Cu is obtained. 2+ 。

[0066] Characterize the fluorescence spectrum of this phosphor by a fluorescence spectrometer, and the emission peaks generated by copper ions can be detected. The intensity peak is at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is about 1 minute.

[0067] Example 10: Preparation of LiGaO₂:0.001Cu 2+ Phosphor.

[0068] According to the stoichiometric ratios of the elements in the chemical general formula LiGaO₂:0.001Cu 2+ weigh out 0.1843 g of Na₂CO₃, 0.4685 g of Ga₂O₅, and 0.0004 g of CuO respectively, and place them in an agate mortar for sufficient and uniform grinding. Then place them in a crucible and pre-burn in an air atmosphere. The pre-burning temperature is 400 °C and the time is 8 hours. After natural cooling to room temperature, grind again and then calcine in an air atmosphere. The calcination temperature is 1300 °C and the time is 4 hours. When the furnace temperature naturally cools to room temperature, the target product LiGaO₂:0.001Cu is obtained. 2+ 。

[0069] Characterize the fluorescence spectrum of this phosphor by a fluorescence spectrometer, and the emission peaks generated by copper ions can be detected. The intensity peak is at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is about 1 minute.

[0070] Example 11: Method for applying Cu 2+ doped green fluorescent materials for information storage and encryption:

[0071] Prepare one portion of each of the Cu 2+ doped green fluorescent materials with afterglow times of 1, 10, and 30 minutes;

[0072] Agree on the coding rule: The afterglow time less than 5 minutes is recorded as the number 1, the afterglow time greater than 5 but less than 15 minutes is recorded as the number 2, and the afterglow time greater than 15 is recorded as the number 3.

[0073] When the information to be encrypted is the number 123, use 3 portions of Cu 2+Dope a green fluorescent material to encode the information to be encrypted, completing information storage and encryption; when 365-nm ultraviolet light is not applied, the colors of the three materials are the same, and those who do not know the encoding rule cannot know the number 123 stored therein. For those who know the encoding rule, use 365-nm ultraviolet light to excite a number of Cu 2+ doped green fluorescent materials, and record the afterglow time of each Cu 2+ doped green fluorescent material, and decode based on the afterglow time to obtain the digital information of 123 encrypted previously.

[0074] The above embodiments are not limitations on the present invention. The present invention is not limited to the above embodiments. As long as it meets the requirements of the present invention, it falls within the protection scope of the present invention.

Claims

1. A Cu 2+ -doped green fluorescent material, characterized in that, Its chemical general formula is LiGaO2:xCu 2+ ; wherein, 0.001 ≤ x ≤ 0.03; The Cu 2+ The crystal structure of the doped green fluorescent material is based on LiGaO2, and Cu 2+ substitutes the lattice site of Ga in the matrix to form doping, obtaining LiGaO2:Cu 2+ green long afterglow fluorescent material; The adjustable afterglow means that the afterglow time is adjusted by adjusting the lattice defect concentration in the Cu 2+ doped green fluorescent material; The described Cu 2+ When the doped green fluorescent material is excited by 355-nm ultraviolet light, its strongest emission peak is located at 540 nm, the full width at half maximum is 120 nm, and the afterglow duration is from 1 minute to 30 minutes.

2. The preparation method of the Cu 2+ -doped green fluorescent material according to claim 1, characterized in that, It includes the following steps: Step (1): Take compounds containing lithium ions, compounds containing gallium ions, and compounds containing copper ions as raw materials, and weigh the raw materials according to the molar ratio of lithium, gallium, and copper in the chemical general formula LiGaO₂:xCu 2+ where 0.001 ≤ x ≤ 0.03; Step (2): Mix and fully grind the raw materials weighed in step (1), and after grinding evenly, perform pre-sintering to obtain a mixture; Step (3): Naturally cool the mixture obtained after pre-burning in step (2) to room temperature. After sufficiently grinding, perform sintering. After the sintering process ends, wait for it to naturally cool to room temperature to obtain a long-afterglow gallate phosphor with the chemical formula LiGaO₂:xCu 2+ ​ 3. According to the preparation method described in claim 2, characterized in that, In step (1), The compound containing lithium ions is any one or a combination of more than one of Li2CO3, LiF2, and LiOH; The compound containing gallium ions is any one or a combination of two of Ga2O3 and GaCl3; The compound containing copper ions is CuO.

4. According to the preparation method described in claim 2, characterized in that, The pre-sintering in step (2) is pre-sintering in an air atmosphere.

5. According to the preparation method described in claim 2, characterized in that, The sintering in step (3) is sintering in an air atmosphere.

6. According to the preparation method described in claim 2, characterized in that, In step (3), the temperature of the sintering is 900 - 1300 °C, and the time of the sintering is 4 - 24 hours.

7. According to the preparation method described in claim 2, characterized in that, In step (2), the temperature of the pre-sintering is 300 - 500 °C, and the time of the pre-sintering is 4 - 8 hours.

8. A method for adjusting the afterglow of the Cu 2+ -doped green fluorescent material, the Cu 2+ -doped green fluorescent material is obtained according to the preparation method described in claim 2; characterized in that, Adjust the afterglow time of the product by changing the sintering time in step (3).

9. The method for adjusting the afterglow of the Cu 2+ -doped green fluorescent material according to claim 8, characterized in that, Adjust the sintering time in the following manner: When the sintering time is 4 hours, the afterglow time of the product is 0.5 - 1.5 minutes; When the sintering time is 12 hours, the afterglow time of the product is 9 - 11 minutes; When the sintering time is 24 hours, the afterglow time of the product is 25 - 35 minutes.

10. A method for information storage and encryption by applying the afterglow adjustment method described in claim 9, characterized in that, Prepare a number of green fluorescent materials doped with Cu with different afterglow times according to a preset sintering time 2+ ; Obtain the information to be encrypted and use the several Cu 2+ Dope the green fluorescent material to encode the information to be encrypted, and complete information storage and encryption; Ultraviolet light in the wavelength range of 355 to 365 nanometers is used to excite a number of Cu 2+ doped green fluorescent materials, and the afterglow time of each Cu 2+ doped green fluorescent material is recorded, and decoding is performed based on the afterglow time to obtain the information to be encrypted.

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