A multimodal dynamic luminescent material, a preparation method and application thereof

Abstract

The application discloses a transition metal element doped multi-modal dynamic photoluminescence material and a preparation method and application thereof. The material is CaGa4O7:xM, wherein M is one of Sc 3+ , Cr 3+ , V 4+ , Mo 4+ , and x is a molar doping ratio of the doping ion relative to Ca 2+ . The material can present yellow color to blue color (M=Sc; V; Mo) or red color to blue color (M=Cr) under excitation of 254 nm ultraviolet light. By adjusting the trap energy level depth of the doping ion, short-time memory (such as Cr, recovery time 1 min) and long-time memory (such as Sc, recovery time 90 min) two dynamic luminescence characteristics can be realized, and the material has excellent performances such as 300-600 K temperature-dependent luminescence regulation, excitation light power density rate regulation and heat quenching resistance. The application is prepared by a high-temperature solid-phase method, raw materials are easy to obtain, rare earth is not relied on, and the cost is low. The application can be applied to time memory type multi-level anti-counterfeiting, intelligent information encryption and other fields, and solves the technical bottlenecks of traditional dynamic luminescence materials, such as rare earth dependence, narrow color gamut, no memory effect and single regulation mode.

Description

Technical Field

[0001] This invention relates to the fields of luminescent materials, information encryption and anti-counterfeiting technology, specifically to a transition metal-doped CaGa4O7 inorganic oxide fluorescent material and its preparation method, as well as the application of this material in the fields of dynamic photoluminescence regulation, time-memory type intelligent anti-counterfeiting, multiple information encryption, and optical sequential logic switch construction. Background Technology

[0002] With the increasing severity of counterfeit goods and information leaks, advanced anti-counterfeiting and information encryption technologies are playing an increasingly prominent strategic role in areas such as intellectual property protection, national defense security, and the authentication of high-value goods. Traditional static luminescent materials (such as long-afterglow phosphors and fluorescent inks with fixed wavelengths) have low security levels because their luminescence color and intensity do not dynamically evolve over time, making them extremely easy to crack through reverse engineering and modern spectral analysis techniques.

[0003] In recent years, dynamic multicolor luminescent materials have become a research hotspot for next-generation advanced anti-counterfeiting and multidimensional encryption technologies due to their ability to respond to external stimuli and exhibit rich color and spectral changes over time. However, most reported inorganic dynamic luminescent materials suffer from the following serious technical defects: (1) High dependence on rare earth elements and high production costs: Most existing inorganic dynamic light-emitting materials use lanthanide rare earth ions (such as Eu). 3+ Dy 3+ 、Tb 3+ Rare earth elements (such as 4f-4f electron transitions) serve as luminescent or trapping centers. However, their reserves are limited, mining and separation are costly, and their luminescent energy levels are relatively fixed due to the relatively small influence of the surrounding lattice field environment, resulting in insufficient concealment of anti-counterfeiting codes.

[0004] (2) Narrow dynamic color gamut and low contrast: The range of color changes is limited, mostly monochromatic gradients, and the visual anti-counterfeiting effect is poor; (3) Single regulation method: It only relies on continuous ultraviolet light irradiation and lacks multi-dimensional regulation methods such as temperature, light power and time memory; (4) Lack of time memory function: The existing dynamic color-changing behavior cannot maintain its internal trap state for a long time or achieve precise time-sharing control after the light source is turned off. In actual anti-counterfeiting applications, it is impossible to achieve on-demand customization of "short-term rapid recovery" and "long-term physical memory" according to the time interval; Therefore, in inorganic matrices, by introducing non-rare earth transition metal ions, precisely constructing and controlling the carrier trap energy level structure, and developing a highly stable dynamic luminescent material that is free from rare earth dependence, exhibits ultra-wide color gamut dynamic evolution, possesses customizable time memory effect, and allows for multi-dimensional synergistic control of "light-temperature-power", is a key technological bottleneck that urgently needs to be addressed in this field. Summary of the Invention

[0005] Purpose of the invention To address the high cost and relatively fixed luminescence energy levels of traditional rare-earth dynamic photoluminescent materials in existing technologies, which pose a risk of being reverse-analyzed by spectroscopic instruments in advanced anti-counterfeiting applications, this invention aims to provide a multimodal dynamic photoluminescent material. This material is not rare-earth dependent, can achieve wide color gamut dynamic luminescence and customizable time memory effects, and possesses multi-dimensional luminescence control capabilities and excellent stability. Another objective of this invention is to provide a simple, low-cost method for preparing the material, suitable for large-scale production. A further objective of this invention is to provide applications for the material, applicable to multi-level anti-counterfeiting, information encryption, optical logic devices, and other fields, meeting the application needs of high-end security fields.

[0006] Technical solution 2.1 Material Composition The multimodal dynamic photoluminescent material provided by this invention has the chemical composition CaGa4O7:xM, wherein: M is Sc 3+ Cr 3+ V 4+ Mo 4+ One or more transition metal ions in the matrix; x is the dopant ion relative to Ca in the matrix. 2+ The molar doping ratio of Sc, where Sc 3+ The optimal molar doping ratio is 2.2%, Cr 3+ The optimal molar doping ratio is 0.7%, V 4+ Mo 4+ Trace doping is used to achieve precise control of the trap energy level.

[0007] The matrix CaGa4O7 is a monoclinic crystal system. This structure has abundant tunable intrinsic defect sites, which can stably accommodate transition metal dopants. After doping, it can still maintain the pure phase crystal structure of CaGa4O7 without the formation of impurity phases, providing an ideal structural basis for the construction of multi-level trap energy levels.

[0008] 2.2 Preparation method This invention uses a high-temperature solid-state reaction method to prepare CaGa4O7:xM materials. The specific steps are as follows: a) Weigh the raw materials according to the stoichiometric ratio: CaCO3 (purity ≥99.99%), Ga2O3 (purity ≥99.99%), ScCl3 (purity ≥99.9%), Cr2O3 (purity ≥99.95%), C2O5V (purity ≥99%), and MoO2 (purity ≥99.9%). The amount of raw materials containing transition metal elements added should be based on the ratio of M to Ca. 2+The atomic ratio x is determined to be between 0.005 and 0.04. b) Place the above raw materials in a mortar and grind manually for 30 minutes to ensure that the raw materials are mixed evenly; c) The ground mixed powder is transferred to an alumina boat and placed in a box furnace (OTF-1700X) for high-temperature reaction. The temperature is increased to 1200 ℃ at a heating rate of 5 ℃ / min and held for 4 h. The temperature control accuracy of the box furnace is ±1 ℃. The reaction process does not require a protective atmosphere and pure phase synthesis is achieved in an air atmosphere.

[0009] d) After the reaction is complete, the furnace is cooled to room temperature to obtain CaGa4O7:xM powder material.

[0010] 2.3 Performance Characteristics a) Crystal structure and morphological characteristics: The doping of transition metals did not change the crystal phase structure of CaGa4O7, and no impurity phases were generated; after doping, the lattice constants a, b, and c decreased slightly, the cell volume shrank, and the transition metal ions preferentially replaced Ca sites; the material exhibited a neat crystal morphology and regular boundaries, and Ca, Ga, O, and the doped transition metal elements were uniformly distributed on the grains; the incorporation of transition metal ions introduced more oxygen vacancies, providing sites for carrier capture.

[0011] b) Dynamic multicolor emission characteristics: Under 254 nm ultraviolet light irradiation, the material exhibits dynamic fluorescence emission across a wide color gamut. Using Sc... 3+ and Cr 3+ Taking doping as an example: In the initial stage (low concentration of trapped carriers), light emission is mainly achieved through the characteristic channels of doped ions (M is Sc). 3+ At that time, yellow light is emitted through the defect recombination center, with the main peak located at 580 nm; M is Cr 3+ Initially, it emits red light through sharp lines, with the main peak at 713 nm; later, as irradiation time accumulates (the concentration of trapped carriers reaches saturation), the luminescence state dynamically shifts and is dominated by the intrinsic blue light channel of the matrix CaGa4O7 (the main peak is at 497 nm). Among them, the highest peak of the yellow emission peak is located in the 550-610 nm range, the highest peak of the red emission peak is located in the 650-750 nm range, and the highest peak of the blue emission peak is located near 497 nm.

[0012] c) Dynamic luminescence mechanism and carrier trapping centers: This dynamic luminescence process is highly correlated with the energy level depth and fill state of the carrier trapping centers. Transition metal ion doping introduces carrier trapping centers at specific depths in the matrix. Thermoluminescence (TL) curve testing and initial rise method analysis after charging with 254 nm ultraviolet light show that the trapping depth of the continuously distributed dopant ion M varies with different dopant ions. M is Sc 3+At this point, deep carrier traps are formed internally, with corresponding trap energy level depths of 0.54-1.10 eV, where the trap depth corresponding to the peak of the TL curve is 0.83 eV; M represents Cr. 3+ When the ultraviolet light continues to excite the device, deep carrier traps are formed inside, with corresponding trap energy level depths of 0.14-0.66 eV, where the trap depth corresponding to the peak of the TL curve is 0.65 eV. As ultraviolet light continues to excite the device, the deep / shallow traps are gradually filled with carriers, blocking energy transfer to the longer wavelength channel, thereby achieving dynamic color change.

[0013] d) Multi-dimensional regulatory capabilities: Temperature regulation and thermal quenching resistance: At 300 K (room temperature), it exhibits normal dynamic emission from yellow (or red) to blue. Within a wide temperature range of 300-600 K, the blue emission channel is gradually suppressed as the temperature increases. When M is Sc 3+ At this time, the blue light channel in the 440-600 K range is completely suppressed, the emission color is locked to pure yellow, and the thermal excitation of the deep trap at high temperature compensates for the non-radiative transition loss, exhibiting high-temperature yellow light enhancement and anti-thermal quenching characteristics; when M is Cr 3+ At this time, blue light above 400 K is completely suppressed, and the emission is locked in red.

[0014] Optical power density modulation: By adjusting the power density of the 254 nm ultraviolet excitation source (0.69 - 6.16 W / m²), 2 It can precisely control the saturation rate and dynamic color change period of the trapped charge carriers; the higher the power density, the faster the color change rate, and the color change time can be significantly shortened from 0.9 s to 0.2 s.

[0015] Temporal memory effect modulation: Customized time-memory functions can be achieved by utilizing the differences in room-temperature carrier release kinetics caused by varying trap depths. After the light source is turned off and allowed to stand still, it is re-excited, where M is Sc. 3+ (Deep trap, electrons cannot escape spontaneously) This manifests as a long-term memory effect, requiring a 90-minute interval between two excitations to recover the complete "yellow to blue" evolution; M is Cr 3+ (Shallow trap, electrons are easily cleared by room temperature thermal disturbance) This manifests as a short-term recoverable effect, and the "red to blue" process can be completely reproduced after an interval of 60 seconds.

[0016] e) Thermoluminescence kinetics and luminescence evolution characteristics: After being charged with 254 nm ultraviolet light, Sc 3+ The thermoluminescence (TL) peak of the doped system is located in a higher temperature region (corresponding to a 0.83 eV deep trap), and its large activation energy effectively blocks the spontaneous escape of charge carriers at room temperature; while Cr 3+The TL peak of the doped system shifts to the low-temperature region (corresponding to a shallow trap of 0.65 eV), and the carriers have an extremely high escape probability at room temperature. This differential distribution of deep and shallow traps not only determines the evolution period and memory time of the emission color, but also directly modulates the fluorescence lifetime and response relaxation characteristics of different emission channels (yellow / red and blue light channels).

[0017] 2.4 Application Directions a) Time-memory type advanced information encryption: By utilizing the unique carrier dynamics difference between long-term memory (90 minutes) and short-term recovery (60 seconds) of materials, customized advanced dynamic cryptographic encoding and decryption with time-sensitive and time-segmented reading can be achieved by controlling the continuous time interval of excitation.

[0018] b) Multi-dimensional and multi-level intelligent anti-counterfeiting labels: Combining the high-contrast dynamic multi-color evolution behavior of materials and the sensitive response of color change rate to excitation light power density, anti-counterfeiting labels that transcend spatial and temporal dimensions can be prepared, greatly increasing the difficulty of counterfeiting.

[0019] c) High-temperature extreme environment optical reading: With the material's unique light emission color locking characteristics and anti-thermal quenching performance in a wide temperature range of 300-600 K, it is suitable for in-situ identification of concealed information in high-temperature extreme industrial or military environments such as aviation and metallurgy.

[0020] d) Optical sequential logic switching devices: Utilizing the coordinated response and nonlinear evolution of materials to multidimensional physical signals such as irradiation time, ambient temperature, and excitation power, they can be used as core functional media to construct multimodal optical logic gates in flexible optoelectronic integrated circuits.

[0021] 3. Beneficial effects Compared with the prior art, the present invention has the following significant advantages: Multimodal control capability: Through various means such as temperature, pulsed ultraviolet light, and dual-wavelength ultraviolet light synergy, precise control of dynamic light emission is achieved, solving the problem of the single dynamic light emission control method of traditional oxides.

[0022] A clear physical mechanism: The correlation between dynamic luminescence and the energy level / concentration of carriers at the trapping center was clarified, providing a theoretical basis for the design and optimization of oxide dynamic luminescent materials.

[0023] Abundant application scenarios: Breaking through the limitation of dynamic light-emitting materials being used only for anti-counterfeiting, it has been extended to fields such as optical sequential logic switches, multiple encryption of information, and flexible optoelectronic devices.

[0024] High security level: Anti-counterfeiting is based on the intrinsic physicochemical properties of the material, and its multi-mode, dynamic optical response is extremely difficult to copy or imitate.

[0025] The preparation process is simple: it is prepared by high-temperature solid-phase reaction, the raw materials are readily available, the process is mature and the cost is low, making it suitable for large-scale production; the material has good cycle stability and environmental adaptability, and is highly practical. Attached Figure Description

[0026] Figure 1 These are the XRD patterns of CaGa4O7:xSc from Examples 1-5.

[0027] Figure 2 The XRD patterns of CaGa4O7:xCr in Examples 6-10 are shown.

[0028] Figure 3 This is a scanning electron microscope image of Example 4, CaGa4O7:0.022Sc.

[0029] Figure 4 This is a scanning electron microscope image of CaGa4O7:0.007Cr from Example 7.

[0030] Figure 5 This is the X-ray photoelectron spectrum of CaGa4O7:0.022Sc in Example 4.

[0031] Figure 6 This is the X-ray photoelectron spectrum of CaGa4O7:0.007Cr in Example 7.

[0032] Figure 7 These are photographs of the dynamic luminescence of the materials in Example 4 (CaGa4O7:0.022Sc), Example 7 (CaGa4O7:0.007Cr), and the comparative CaGa4O7 material under 254 nm ultraviolet light irradiation over time, as well as afterglow photographs after the ultraviolet excitation was stopped.

[0033] Figure 8 This is a graph showing the dynamic emission spectrum of the CaGa4O7:0.022Sc material in Example 4 at 300 K as a function of 254 nm irradiation time (0.1 s-1.0 s, yellow light weakens and blue light strengthens).

[0034] Figure 9 This is a graph showing the dynamic emission spectrum of the CaGa4O7:0.007Cr material in Example 7 at 300 K as a function of 254 nm irradiation time (0.1 s-1.0 s, red light decreases and blue light increases).

[0035] Figure 10 These are photographs of the dynamic luminescence of CaGa4O7:0.04V in Example 11 and CaGa4O7:0.04Mo in Example 12.

[0036] Figure 11This is a graph showing the dynamic emission spectrum of CaGa4O7:0.04V material in Example 11 at 300 K as a function of 254 nm irradiation time (0.1 s-1.0 s, yellow light weakens and blue light strengthens).

[0037] Figure 12 This is a graph showing the dynamic emission spectrum of the CaGa4O7:0.04Mo material in Example 12 at 300 K as a function of 254 nm irradiation time (0.1 s-1.0 s, yellow light weakens and blue light strengthens).

[0038] Figure 13 These are photographs of the dynamic luminescence color of the CaGa4O7:0.022Sc material from Example 4 at different temperatures (300-600 K) as it changes over time.

[0039] Figure 14 These are photographs of the dynamic luminescence color of the CaGa4O7:0.007Cr material in Example 7 changing over time at different temperatures (300-500 K).

[0040] Figure 15 This is a thermoluminescence (TL) curve of the CaGa4O7:0.022Sc material in Example 4 after being charged at different temperatures.

[0041] Figure 16 This is a thermoluminescence (TL) curve of the CaGa4O7:0.007Cr material in Example 7 after being charged at different temperatures.

[0042] Figure 17 These are photographs of the time memory effect of the CaGa4O7:0.022Sc material in Example 4 under different re-excitation intervals.

[0043] Figure 18 These are photographs of the time memory effect of the CaGa4O7:0.007Cr material in Example 7 under different re-excitation intervals.

[0044] Figure 19 This is a comparative bar graph showing the time required for the materials in Example 4 (CaGa4O7:0.022Sc) and Example 7 (CaGa4O7:0.007Cr) to recover their dynamic color change after two re-excitation intervals.

[0045] Figure 20 This is a schematic diagram of a pattern anti-counterfeiting material composed of CaGa4O7:0.022Sc from Example 4, CaGa4O7:0.007Cr from Example 7, and CaGa4O7 from the comparative example.

[0046] Figure 21This is an anti-counterfeiting diagram of a letter pattern composed of materials from Example 4 (CaGa4O7:0.022Sc) and Example 7 (CaGa4O7:0.007Cr).

[0047] Figure 22 This is a demonstration diagram of the application of a programmable multidimensional information encryption matrix prepared based on the materials of Example 4 CaGa4O7:0.022Sc, Example 7 CaGa4O7:0.007Cr, and the comparative CaGa4O7 material. Detailed Implementation

[0048] The present invention will now be described in more detail through embodiments and comparative examples, in conjunction with the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] The specific embodiments 1-12 and comparative examples of this invention are all prepared by high-temperature solid-state synthesis. The raw materials are weighed according to the stoichiometric ratio: CaCO3 (purity ≥99.99%), Ga2O3 (purity ≥99.99%), ScCl3 (purity ≥99.9%), Cr2O3 (purity ≥99.95%), C2O5V (purity ≥99%), and MoO2 (purity ≥99.9%). The amounts used satisfy the condition that x = 0.005-0.024 in CaGa4O7:xM. The amount of raw materials containing transition metal elements is determined according to the ratio of M to Ca. 2+ The atomic ratio was determined; the above raw materials were placed in a mortar and manually ground for 30 min to ensure uniform mixing. Then, the mixed powder was transferred to an alumina boat, placed in a box furnace, and heated to 1200 ℃ at a heating rate of 5 ℃ / min, and held at that temperature for 4 h. All steps were based on the above experimental scheme, the difference being that the different raw material ratios resulted in different x values ​​in CaGa4O7:xM. The material composition and raw material mass of the specific embodiment are shown in Table 1.

[0050] Table 1. Material composition and raw material mass of CaGa4O7:xM in Examples 1-12 and CaGa4O7 in Comparative Examples.

[0051]

[0052] Figure 1 , Figure 2 The X-ray diffraction (XRD) patterns of Examples 1-5 (CaGa4O7:xSc) and Examples 6-10 (CaGa4O7:xCr) are shown respectively. All diffraction peaks in the figures match the CaGa4O7 standard card, and there are no diffraction peaks of impurity phases, proving that the transition metal ions successfully entered the crystal lattice without destroying the matrix structure.

[0053] Figure 3 and Figure 4The images show scanning electron microscope (SEM) images of Examples 4 (CaGa4O7:0.022Sc) and 7 (CaGa4O7:0.007Cr), respectively. As can be seen from the figures, the powder materials synthesized by the high-temperature solid-state method exhibit regular micron-sized particle morphology, good crystallinity, and a relatively uniform particle size distribution. This morphology helps maintain good dispersibility in subsequent tests and applications.

[0054] Figure 5 and Figure 6 The images show detailed high-resolution X-ray photoelectron spectroscopy (XPS) spectra of Examples 4 and 7, respectively. The orbital peaks of Sc and Cr are clearly visible (the peak intensity is weaker due to low content, but still clearly identifiable), corresponding to Sc... 3+ and Cr 3+ The chemical state further confirms the successful doping of transition metal ions. The XPS spectra of other embodiments are similar to those of Examples 4 and 7, and will not be described again.

[0055] Figure 7 The dynamic luminescence and afterglow characteristics of Example 4 (CaGa4O7:0.022Sc), Example 7 (CaGa4O7:0.007Cr), and the comparative example (CaGa4O7) under continuous irradiation with 254 nm ultraviolet light were visually recorded. In the initial stage of irradiation (0.1 s), Example 4 exhibited yellow luminescence, Example 7 exhibited red luminescence, and the comparative example exhibited dark blue luminescence. As the irradiation time was extended to 1.0 s, Examples 4 and 7 completed the dynamic color change evolution of "yellow → blue" and "red → blue," respectively. After excitation was stopped, the materials all exhibited obvious long afterglow luminescence.

[0056] Figure 8 and Figure 9 The above process was precisely quantified by fluorescence spectra that varied with the duration of irradiation under 254 nm excitation light. For Example 4 ( Figure 8 During the 0.1–1.0 s period, the relative intensity of the 580 nm yellow defect emission channel introduced by Sc gradually saturates and weakens, while the 497 nm matrix blue emission peak significantly increases as the traps are filled. For Example 7 ( Figure 9 The relative intensity of the red light emission from the Cr sharp line near 713 nm gradually saturates, while the matrix blue emission peak at 497 nm is significantly enhanced as the traps are filled.

[0057] Figures 10 to 12 The results demonstrate the universality of transition metal systems. Figure 10 The images show the dynamic light emission of Examples 11 (CaGa4O7:0.04V) and 12 (CaGa4O7:0.04Mo), both of which exhibit a visible "yellow to blue" change. Figure 11 and Figure 12The spectral evolution over time further confirms that V and Mo doping also follow the dynamic fluorescence emission pattern of yellow light dominance in the early stage and blue light dominance in the later stage.

[0058] Figure 13 Photographs of the actual luminescence of Example 4 (CaGa4O7:0.022Sc) within the range of 300-600 K are shown, revealing its temperature-dependent luminescence characteristics over a wide temperature range. As the operating temperature increases, the blue light channel is gradually suppressed; when the temperature exceeds 440 K, the blue light is completely blocked, and the emission color is "locked" to yellow, and no significant quenching of the yellow light intensity is observed at higher temperatures (thermal quenching resistance).

[0059] Figure 14 Photographs of the actual luminescence of Example 7 (CaGa4O7:0.007Cr) in the range of 300-500 K are shown. Similarly, the high temperature causes carriers in the shallow traps to escape, suppressing the blue light channel and causing the luminescence to be completely locked in red in the high-temperature region.

[0060] Figure 15 and Figure 16 The figures show the thermoluminescence (TL) curves of Examples 4 (CaGa4O7:0.022Sc) and 7 (CaGa4O7:0.007Cr) after charging at different temperatures. The main TL peak of Example 4 shifts towards the high-temperature region, indicating that its traps have high thermal stability (deep traps); while the main TL peak of Example 7 is located in the lower-temperature region, indicating that the charge carriers in its traps are easily excited by room-temperature thermal energy (shallow traps). This microscopic physical difference between deep and shallow traps is the fundamental reason for the macroscopic long and short-term memory effect.

[0061] Figure 17 The "long-term physical memory effect" of Example 4 was verified. After excitation, the light source was turned off and left to stand for different periods of time. When the interval was less than 30 minutes, the material directly exhibited the final state of blue when it was re-excited. Only when the interval reached 90 minutes did the deep-trapped charge carriers completely and spontaneously empty, restoring the initial "yellow→blue" dynamic process.

[0062] Figure 18 The “short-term recoverable effect” of Example 7 is demonstrated. Since the shallow-trap carriers can escape very easily, the material can completely repeat the initial “red → blue” color change process after being excited again only 60 s (1 min) apart.

[0063] Figure 19 The bar graph visually compares the specific waiting time (90 min and 1 min) required for dynamic color change recovery of the two materials in Example 4 and Example 7, proving that the material of the present invention can successfully achieve a large-scale customization of time memory scale by changing different transition metal doping.

[0064] Figure 20 and Figure 21 Anti-counterfeiting patterns and letter markings prepared using materials from Example 4 (CaGa4O7:0.022Sc), Example 7 (CaGa4O7:0.007Cr), and comparative examples are demonstrated. Under continuous ultraviolet light irradiation, specific areas of the patterns exhibit a high-level dynamic anti-counterfeiting effect, with multiple colors interwoven at different time points and eventually uniformly evolving into blue, greatly enhancing the anti-counterfeiting threshold.

[0065] Figure 22 A programmable multidimensional information encryption matrix constructed based on the material of this invention was demonstrated. This proves that the material exhibits significant multidimensional optical differential response, effectively raising the barrier to product imitation, and its industrial-scale preparation process is mature.

Claims

1. A multimodal dynamic photoluminescent material, characterized in that, a) It has a monoclinic crystal structure of CaGa4O7, and its chemical composition is CaGa4O7:xM, where M is Sc 3+ Cr 3+ V 4+ Mo 4+ One of the transition metal ions in Ca, where x is the dopant ion relative to Ca. 2+ The molar doping ratio is given by x = 0.005-0.04, where Sc is doped. 3+ Preferred x=0.022; Cr doped 3+ Preferred x=0.007; doped with V 4+ and Mo 4+ The preferred value is x=0.04; b) The material, when excited by 254 nm ultraviolet light, when M is Sc 3+ V 4+ Or Mo 4+ When the irradiation time increases, it exhibits a dynamic photoluminescence change from yellow to blue; when M is Cr 3+ As the irradiation time increases, the light exhibits a dynamic photoluminescence change from red to blue. The highest peak of the yellow emission peak is located in the 550-610 nm range, the red emission peak is located in the 650-750 nm range, and the blue emission peak is a broad-spectrum emission peak with the highest peak at 497 nm.

2. The material according to claim 1, characterized in that, The material has continuously distributed carrier trapping centers at different depths depending on the doping element, where M is the Sc 3+ V 4+ Mo 4+ In one of these cases, the trap energy level depth is 0.54–1.10 eV; M is Cr 3+ At that time, the trap energy level depth was 0.14-0.66 eV.

3. The material according to claim 1, characterized in that, The material M is Sc 3+ At 300-420 K, the blue emission channel is gradually suppressed as the temperature increases; above 440 K, blue light is completely suppressed, retaining only yellow emission. When M is Cr 3+ At 300-380 K, as the temperature increases, the blue emission channel is gradually suppressed, and above 400 K, blue light is completely suppressed, leaving only red emission.

4. The material according to claim 1, characterized in that, The material, after being charged with 254 nm ultraviolet light, exhibits significantly different memory effects on the re-excitation interval when doped with different transition metal ions. For example, the material doped with Sc... 3+ and Cr 3+ For example: when M is Sc 3+ When M is Cr, it exhibits a long-term memory effect, requiring an interval of 90 minutes or more between two consecutive excitations to recover the initial yellow-to-blue dynamic luminescence evolution; 3+ When the time interval between two consecutive excitations is 60 s, it exhibits a short-term memory effect, and the initial dynamic emission evolution from red to blue can be completely recovered.

5. A method for preparing a multimodal dynamic photoluminescent material according to any one of claims 1-4, characterized in that, The high-temperature solid-state reaction method includes the following steps: a) Weigh out the following raw materials according to stoichiometric ratios: CaCO3 (purity ≥ 99.99%), Ga2O3 (purity ≥ 99.99%), ScCl3 (purity ≥ 99.9%), Cr2O3 (purity ≥ 99.95%), C2O5V (purity ≥ 99%), and MoO2 (purity ≥ 99.9%). The amount of these raw materials, including doped elements, shall satisfy the condition that x = 0.005-0.04 in CaGa4O7:xM. b) Place the above ingredients in a mortar and grind manually for 30 minutes to ensure even mixing; c) Transfer the mixed powder to an alumina boat, place it in a box furnace, raise the temperature to 1200℃ at a rate of 5℃ / min, and hold for 4 h to carry out a high-temperature solid-phase reaction; d) After cooling the above materials to room temperature, multimodal dynamic photoluminescent material CaGa4O7:xM powder can be obtained.

6. A method for multimodal dynamic luminescence modulation based on any one of the materials claimed in claims 1-5, characterized in that, When the doping element is Sc, the yellow-to-blue dynamic luminescence is maintained at 300 K (room temperature). The blue emission is suppressed at 300-420 K and disappears completely at 440-520 K, leaving only yellow emission. When the doping element is Cr, the red-to-blue dynamic luminescence is maintained at 300 K (room temperature). The blue emission is suppressed at 300-380 K and disappears completely above 400 K, leaving only red emission.

7. The control method according to claim 6, characterized in that, After the carriers are removed by thermal excitation (temperature of 500 K), the dynamic luminescence performance can be reproduced under 254 nm ultraviolet light irradiation, and the above process can be repeated at least ten times.

8. The control method according to claim 6, characterized in that, When M is Sc, after the sample is charged with 254 nm ultraviolet light, it takes 90 min of interval excitation time to recover the dynamic emission phenomenon of yellow light turning into blue light, which shows a long-term memory effect; when M is Cr, it only takes 60 s of interval excitation time to recover the dynamic emission phenomenon of red light turning into blue light, which shows a short-term memory effect.

9. The control method according to claim 6, characterized in that, The power density in the 254 nm ultraviolet light ranges from 0.69 to 6.16 W / m². -2 Within the sample, it was found that the dynamic color change time of the CaGa4O7:Sc sample decreased from 0.9 s to 0.2 s; and the dynamic color change time of the CaGa4O7:Cr sample decreased from 2.0 s to 0.5 s.

10. An application of the material according to any one of claims 1-5, characterized in that, It can be used in time-memory multi-level anti-counterfeiting labels, time-division programmable intelligent information encryption elements, high-temperature environment optical markings, and optical logic switching devices.

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