A cyan fluorescent material, a preparation method and application thereof

Abstract

This invention relates to the field of fluorescent materials technology, specifically disclosing a cyan fluorescent material, its preparation method, and its applications. The chemical formula of the cyan fluorescent material is Ca. 9‑y Zn y Y(PO4)7:xEu 2+ Wherein, 0.005≤x≤0.04; 0.5≤y≤2. This invention utilizes Eu, which possesses specific luminescent properties. 2+ Doping is performed, and Eu is adjusted. 2+ The matrix coordination environment and doping amount are used to effectively control the wavelength and bandwidth of the emission spectrum of fluorescent materials, giving them a wide emission half-width, excellent thermal stability and high internal quantum efficiency. This effectively fills the cyan gap in full-spectrum white light illumination and allows them to combine with flexible polymer substrates, enabling high-definition and low-dose real-time imaging of irregular curved objects.

Description

Technical Field

[0001] This invention relates to the field of fluorescent materials technology, and in particular to a cyan fluorescent material, its preparation method, and its application. Background Technology

[0002] Rare earth luminescent materials play an extremely important role in fields such as lighting, display, sensing, biomedical probes, and radiation detection due to their unique optical transition characteristics.

[0003] In the lighting field, light-emitting diodes (LEDs), as the fourth generation of lighting sources, are widely used due to their advantages such as energy saving, environmental protection, and promotion of sustainable development. Among them, phosphor-converted LED (PC-LED) is currently the most widely used form. Traditional white PC-LEDs typically use blue LED chips (InGaN) to excite yellow phosphors. However, due to the inconsistency in aging characteristics between blue LED chips and phosphors, the white light produced by this "yellow + blue" combination is unstable. Furthermore, the lack of red light components results in a low color rendering index (Ra < 75), limiting its application in many high-quality lighting applications. Ultraviolet (UV) excitation energy is higher than blue light and does not participate in white light recombination, which to some extent expands the selection range of fluorescent materials, allowing for adjustment of various optical parameters of the produced white light. Therefore, using UV LED chips to excite blue, green, and red (RGB) phosphor materials is the future development trend for white LEDs. However, currently available commercial RGB phosphor combinations exhibit a significant "cyan gap" between 480-520nm, failing to meet the needs of full-spectrum lighting. Currently, the main commercial cyan fluorescent materials on the market have their luminescent centers at 495nm, but the peak width at half maximum (WHM) is relatively narrow, which limits their ability to fill the wide-band cyan spectrum and improve the color rendering index of the entire spectrum.

[0004] Furthermore, luminescent materials also occupy an important position in radiation detection technology. Since Röntgen discovered X-rays in 1895 and observed the fluorescence of zinc sulfide, inorganic scintillators (such as CaWO4 crystals) have been widely used in medical imaging diagnostics, nuclear safety inspection, high-energy physics experiments, homeland security monitoring, and non-destructive testing. In recent years, with the miniaturization and precision of electronic devices, new challenges have arisen for the non-destructive testing of irregular curved surfaces such as flexible circuit boards and bent data cables. Traditional X-ray detectors are often rigid and have limited spatial resolution (approximately 5 lp / mm), making it difficult to meet the real-time imaging requirements of high resolution and curved surface fit.

[0005] In summary, providing a cyan fluorescent material that can overcome the bottleneck of the "cyan gap" in full-spectrum white LEDs and meet the requirements of flexible high-resolution X-ray imaging is of great significance. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the first objective of the present invention is to provide a cyan fluorescent material. The second objective of the present invention is to provide a method for preparing such a cyan fluorescent material. The third objective of the present invention is to provide applications comprising such a cyan fluorescent material.

[0007] The inventive concept of this invention is: by utilizing Eu 2+ By leveraging the 5d-4f broadband transition characteristics and combining them with a crystal matrix that provides a rich coordination environment, a highly efficient cyan fluorescent material with a wide half-width, high internal quantum efficiency, and excellent thermal stability has been developed. This material effectively fills the cyan gap in full-spectrum white light illumination and can also be combined with a flexible polymer substrate to achieve high-resolution and low-dose real-time imaging of irregular curved objects.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a cyan fluorescent material, wherein the chemical formula of the cyan fluorescent material is Ca. 9- y Zn y Y(PO4)7:xEu 2+ Where 0.005≤x≤0.04; 0.5≤y≤2.

[0009] Eu 2+ The luminescence transition mode is a 4f-5d transition, which is highly sensitive to its coordination environment and typically exhibits broadband emission. This invention utilizes Eu, which possesses specific luminescence properties... 2+ Doping is performed, and Eu is adjusted. 2+ The matrix coordination environment and doping amount are used to effectively control the wavelength and bandwidth of the emission spectrum of fluorescent materials, giving them a wide emission half-width, excellent thermal stability and high internal quantum efficiency. This effectively fills the cyan gap in full-spectrum white light illumination and allows them to combine with flexible polymer substrates, enabling high-definition and low-dose real-time imaging of irregular curved objects.

[0010] Preferably, in the cyan fluorescent material, 0.008 ≤ x ≤ 0.035; more preferably, in the cyan fluorescent material, 0.01 ≤ x ≤ 0.032; even more preferably, in the cyan fluorescent material, 0.013 ≤ x ≤ 0.028; and even more preferably, in the cyan fluorescent material, 0.015 ≤ x ≤ 0.025.

[0011] In some embodiments of the present invention, in the cyan fluorescent material, x is any value of 0.005, 0.007, 0.008, 0.009, 0.012, 0.017, 0.02, 0.022, 0.025, 0.029, 0.033, 0.035, 0.038, 0.04 or a range of values ​​formed by any two of these.

[0012] This invention adjusts Eu 2+ The molar ratio of doped cyan phosphors increases the luminescence intensity of the cyan phosphors. At x=2, the luminescence intensity of the cyan phosphors is highest, and concentration quenching does not occur.

[0013] Preferably, in the cyan fluorescent material, 0.7 ≤ y ≤ 1.8; more preferably, in the cyan fluorescent material, 0.8 ≤ y ≤ 1.6; and even more preferably, in the cyan fluorescent material, 1 ≤ y ≤ 1.5.

[0014] Preferably, under ultraviolet light excitation, the cyan fluorescent material emits a spectrum of 480-520 nm. The cyan fluorescent material of this invention effectively fills the cyan gap of 480-520 nm in full-spectrum illumination.

[0015] Preferably, under ultraviolet light excitation, the emission peak center of the emission spectrum of the cyan fluorescent material is located between 490 and 500 nm; more preferably, under ultraviolet light excitation, the emission peak center of the emission spectrum of the cyan fluorescent material is located between 492 and 498 nm; even more preferably, under ultraviolet light excitation, the emission peak center of the emission spectrum of the cyan fluorescent material is located between 494 and 496 nm.

[0016] Preferably, the half-width at half-maximum (WHM) of the emission spectrum of the cyan fluorescent material is ≥100 nm; more preferably, the WHM of the emission spectrum of the cyan fluorescent material is ≥110 nm; even more preferably, the WHM of the emission spectrum of the cyan fluorescent material is ≥120 nm; and even more preferably, the WHM of the emission spectrum of the cyan fluorescent material is 130 nm to 150 nm.

[0017] Preferably, under ultraviolet light excitation, the internal quantum efficiency of the cyan fluorescent material is ≥80%; more preferably, under ultraviolet light excitation, the internal quantum efficiency of the cyan fluorescent material is ≥83%; even more preferably, under ultraviolet light excitation, the internal quantum efficiency of the cyan fluorescent material is ≥85%; and even more preferably, under ultraviolet light excitation, the internal quantum efficiency of the cyan fluorescent material is 85%~95%.

[0018] Preferably, the wavelength of the ultraviolet light excitation is 250nm~450nm; more preferably, the wavelength of the ultraviolet light excitation is 270nm~430nm; and even more preferably, the wavelength of the ultraviolet light excitation is 300nm~400nm.

[0019] Preferably, under ultraviolet light excitation, the cyan fluorescent material retains ≥80% of its luminescence intensity at a working temperature of 420K. The luminescence intensity retention rate is the ratio of the luminescence intensity of the cyan fluorescent material at 420K to its luminescence intensity at 300K.

[0020] In a second aspect, the present invention provides a method for preparing the cyan fluorescent material described in the first aspect, comprising the following steps: mixing a calcium source, a yttrium source, a zinc source, a europium source, and a phosphate source in a stoichiometric ratio to obtain a mixture; and subjecting the mixture to a high-temperature solid-phase reaction under a reducing atmosphere to obtain the cyan fluorescent material.

[0021] Preferably, the purity of the calcium source, yttrium source, zinc source, europium source, and phosphate source is not less than 99.5%.

[0022] Preferably, the calcium source includes at least one of calcium carbonate (CaCO3), calcium oxide, and calcium nitrate.

[0023] Preferably, the yttrium source includes at least one of yttrium oxide (Y₂O₃), yttrium fluoride, and yttrium vanadate.

[0024] Preferably, the zinc source includes at least one of zinc oxide (ZnO) and zinc silicate.

[0025] Preferably, the europium source includes at least one of europium oxide (Eu2O3) and europium nitrate.

[0026] Preferably, the phosphoric acid source includes at least one of ammonium dihydrogen phosphate (NH4H2PO4) and calcium hydrogen phosphate.

[0027] Preferably, the reducing atmosphere is one or a mixture of several of the following: carbon powder reducing atmosphere, hydrogen reducing atmosphere, carbon monoxide reducing atmosphere, and ammonia reducing atmosphere.

[0028] Preferably, the temperature of the high-temperature solid-phase reaction is 1200~1500℃; more preferably, the temperature of the high-temperature solid-phase reaction is 1230~1440℃; even more preferably, the temperature of the high-temperature solid-phase reaction is 1250~1400℃; and even more preferably, the temperature of the high-temperature solid-phase reaction is 1260~1350℃.

[0029] Preferably, the high-temperature solid-phase reaction time is 2-6 hours; more preferably, the high-temperature solid-phase reaction time is 2.5-5.5 hours; even more preferably, the high-temperature solid-phase reaction time is 3-5 hours; and even more preferably, the high-temperature solid-phase reaction time is 3.5-4.5 hours.

[0030] Thirdly, the present invention provides a white LED device, the white LED device comprising the cyan fluorescent material, red fluorescent material, green fluorescent material, blue fluorescent material and ultraviolet LED chip described in the first aspect.

[0031] Preferably, the mass ratio of the cyan fluorescent material, red fluorescent material, green fluorescent material, and blue fluorescent material is (0.5~1):(0.8~1.2):(0.8~1.2):(0.8~1.2); more preferably, the mass ratio of the cyan fluorescent material, red fluorescent material, green fluorescent material, and blue fluorescent material is (0.6~0.9):(0.8~1.2):(0.8~1.2):(0.8~1.2); even more preferably, the mass ratio of the cyan fluorescent material, red fluorescent material, green fluorescent material, and blue fluorescent material is (0.65~0.85):(0.8~1.2):(0.8~1.2):(0.8~1.2).

[0032] Preferably, the emission wavelength of the ultraviolet LED chip is 250nm~450nm; more preferably, the wavelength of the ultraviolet light excitation is 270nm~430nm; and even more preferably, the wavelength of the ultraviolet light excitation is 300nm~400nm.

[0033] Preferably, the white LED device is prepared by a method comprising the following steps: mixing the cyan fluorescent material described in the first aspect with green fluorescent material, blue fluorescent material and red fluorescent material to obtain a mixed fluorescent material; mixing the mixed fluorescent material with ultraviolet light curing adhesive (UV adhesive) and coating it onto the surface of an ultraviolet LED chip and then encapsulating it to obtain the white LED device.

[0034] Preferably, the color rendering index (Ra) of the white LED device is ≥95; more preferably, the color rendering index of the white LED device is ≥95.5; even more preferably, the color rendering index of the white LED device is 95.5~98.

[0035] Preferably, the correlated color temperature (CCT) of the white LED device is 5000~6000K; more preferably, the correlated color temperature of the white LED device is 5010~5095K; even more preferably, the correlated color temperature of the white LED device is 5020~5090K; and even more preferably, the correlated color temperature of the white LED device is 5040~5085K.

[0036] Preferably, the white LED device retains ≥70% of its luminous intensity at an operating temperature of 420K; more preferably, the white LED device retains ≥71% of its luminous intensity at an operating temperature of 420K; even more preferably, the white LED device retains ≥72% of its luminous intensity at an operating temperature of 420K; and even more preferably, the white LED device retains 73%~75% of its luminous intensity at an operating temperature of 420K. Wherein, the luminous intensity retention rate is the ratio of the luminous intensity of the white LED device at an operating temperature of 420K to its luminous intensity at an operating temperature of 300K.

[0037] The white LED device prepared using the cyan fluorescent material of this invention has a high color rendering index and correlated color temperature, and excellent thermal stability, which ensures the luminous stability of the device under long-term and high-power operation, and greatly meets the needs of high-quality full-spectrum lighting.

[0038] Fourthly, the present invention provides a flexible light-emitting film, wherein the materials for preparing the flexible light-emitting film include the cyan fluorescent material and the polymer described in the first aspect.

[0039] Preferably, the polymer comprises at least one of polydimethylsiloxane (PDMS), polyimide (PI), polyethylene terephthalate (PET), polyvinyl alcohol (PVA), and polyethylene naphthalate (PEN).

[0040] Preferably, the ratio of the cyan fluorescent material to the polymer is 1:(5~15); more preferably, the ratio of the cyan fluorescent material to the polymer is 1:(7~13); and even more preferably, the ratio of the cyan fluorescent material to the polymer is 1:(8~12).

[0041] Preferably, the transmittance of the flexible light-emitting film is >80%; more preferably, the transmittance of the flexible light-emitting film is >85%; even more preferably, the transmittance of the flexible light-emitting film is >90%; and even more preferably, the transmittance of the flexible light-emitting film is 90%~99%. Transmittance refers to the percentage of luminous flux transmitted through the film to the incident luminous flux in the visible light band (380~780 nm).

[0042] Preferably, the flexible light-emitting film is prepared by the following method: the cyan fluorescent material described in the first aspect is mixed with a polymer to obtain a mixture, the mixture is coated on a substrate, cured at high temperature to form a film, and the flexible light-emitting film is obtained after demolding.

[0043] Preferably, the high-temperature curing temperature is 70~90℃; more preferably, the high-temperature curing temperature is 72~88℃; and even more preferably, the high-temperature curing temperature is 75~85℃.

[0044] Preferably, the high-temperature curing temperature is 5-15 min; more preferably, the high-temperature curing temperature is 6-13 min; and even more preferably, the high-temperature curing temperature is 8-12 min.

[0045] Preferably, the X-ray imaging spatial resolution of the flexible light-emitting film is ≥7 lp / mm; more preferably, the X-ray imaging spatial resolution of the flexible light-emitting film is ≥7.1 lp / mm; even more preferably, the X-ray imaging spatial resolution of the flexible light-emitting film is ≥7.2 lp / mm; and even more preferably, the X-ray imaging spatial resolution of the flexible light-emitting film is 7.2~7.8 lp / mm.

[0046] Preferably, the X-ray detection limit of the flexible light-emitting film is ≤230 nGy / s; more preferably, the X-ray detection limit of the flexible light-emitting film is ≤220 nGy / s; and even more preferably, the X-ray detection limit of the flexible light-emitting film is 205~220 nGy / s.

[0047] The flexible luminescent thin film prepared using the cyan fluorescent material of this invention overcomes the shortcomings of traditional single-crystal scintillators, such as inflexibility and poor device fabrication. It can be perfectly conformally bonded to complex curved surfaces such as curved data cables, springs, and chips, exhibiting excellent flexibility and fabrication capabilities. Imaging after X-ray detection on complex curved surfaces shows no deformation or distortion, demonstrating advantages such as low detection limits and high spatial resolution. It has broad industrialization prospects in the fields of flexible electronic devices, medical imaging, and precision industrial non-destructive testing.

[0048] Fifthly, the present invention provides the application of the white LED device described in the third aspect in the field of lighting or the flexible light-emitting film described in the fourth aspect in the fields of flexible electronic devices, medical imaging or non-destructive testing.

[0049] The beneficial effects of this invention are: 1. This invention utilizes Eu, which has specific luminescent properties. 2+ Doping is performed, and Eu is adjusted. 2+The matrix coordination environment and doping amount are used to effectively control the wavelength and bandwidth of the emission spectrum of the fluorescent material, so that the cyan fluorescent material has a wide emission half-width (≥100nm), excellent thermal stability (luminescence intensity retention rate ≥80% at operating temperature of 420K) and high internal quantum efficiency (≥80%). It can effectively fill the cyan gap in full-spectrum white light illumination, and can also be combined with flexible polymer substrates to realize high-definition and low-dose real-time imaging of irregular curved objects.

[0050] 2. The white LED device prepared using the cyan fluorescent material of the present invention has a high color rendering index (Ra≥95) and correlated color temperature (5000~6000K), and has excellent thermal stability (luminous intensity retention rate ≥70% at operating temperature of 420K), which ensures the luminous stability of the device under long-term and high-power operation, and greatly meets the needs of high-quality full-spectrum lighting.

[0051] 3. The flexible luminescent film prepared using the cyan fluorescent material of this invention overcomes the shortcomings of traditional single-crystal scintillators, such as inflexibility and poor device processability. It can be perfectly conformally bonded to complex curved surfaces, such as curved data cables, exhibiting excellent flexibility and processability. When bonded to complex curved surfaces and subjected to X-ray detection, no deformation or distortion is observed in the imaging, demonstrating advantages such as low detection limit and high spatial resolution. It has broad industrialization prospects in the fields of flexible electronic devices, medical imaging, and precision industrial non-destructive testing. Attached Figure Description

[0052] Figure 1 The X-ray diffraction (XRD) patterns of the cyan phosphors in Examples 1-5 are shown. Figure 2 The normalized excitation and emission spectra of the cyan phosphor in Example 3 are shown. Figure 3 The graph shows the luminescence intensity of the cyan phosphor in Example 3 under different operating temperature conditions. Figure 4 The spectrum diagrams are of the white LED devices in Example 6 and Comparative Example 1; Figure 5 This is the chromaticity coordinate diagram of the white LED device in Example 6; Figure 6 The images show actual photos of the purple doll illuminated by the white LED devices of Example 6 and Comparative Example 1, respectively. Figure 7 The graph shows the luminous intensity of the white LED device in Example 6 under different operating temperature conditions. Figure 8 Photographs of the flexible luminescent film of Example 7 after it has been bent and laid flat, and then irradiated with natural light and ultraviolet light. Figure 9 To illustrate the bonding of the flexible light-emitting film of Example 7 to springs and chips with different structures, here are physical images under natural light and X-ray images. Figure 10 The image is an X-ray image of the flexible light-emitting thin film X-ray line pair card of Example 7; Figure 11 The radiation emission spectra of the flexible light-emitting thin film of Example 7 under ionizing radiation excitation at different dose rates are shown. Figure 12 The graph shows the linear relationship between the radiative emission intensity of the flexible luminescent film and the X-ray dose rate. Detailed Implementation

[0053] To enable those skilled in the art to more clearly understand this application, the present invention will be further described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. In the description of the present invention, it should be noted that unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments used that do not specify the manufacturer are all commercially available conventional products.

[0054] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without certain specific details. In some embodiments, materials, methods, and means well known to those skilled in the art are not described in detail to highlight the spirit of the invention. Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising of" will be understood to include the stated elements or components without excluding other elements or other components.

[0055] The blue phosphor used in the embodiments of this invention is BaMgAl 10 O 17 Eu 2+ (BAM: Eu) 2+ The green phosphor is Y3Al5O 12 Ce 3+ (YAG: Ce) 3+ The red phosphor is CaAlSiN3:Eu 2+ (CASN: Eu) 2+ Purchased from Guangzhou Ruijing Information Technology Co., Ltd. The polydimethylsiloxane used in the embodiments of the present invention is Dow Corning SYLGARD 184, purchased from Guangzhou Ruijing Information Technology Co., Ltd.

[0056] The flexible light-emitting film in this embodiment of the invention has a light transmittance of 90%.

[0057] In this embodiment of the invention, the room temperature is 22~28℃.

[0058] Example 1 This embodiment provides a cyan phosphor, the chemical formula of which is Ca. 7.5 Zn 1.5 Y(PO4)7:xEu 2+ Where x = 0.005.

[0059] The preparation method of cyan phosphor is as follows: S1: Prepare the synthesis raw materials CaCO3, Y2O3, NH4H2PO4, ZnO and Eu2O3; S2: Weigh the synthetic raw materials from step S1 according to the stoichiometric ratio (i.e., the molar ratio of Ca, Zn, Y, PO4, and Eu in CaCO3, ZnO, Y2O3, NH4H2PO4, and Eu2O3 is 7.5:1.5:1:7:0.005). Mix the raw materials evenly in an agate mortar and grind them thoroughly for 20 minutes. Then place them in a corundum crucible and calcine them at 1300℃ for 4 hours in a muffle furnace under a carbon powder reducing atmosphere (heating rate of 10℃ / min below 1000℃, and 5℃ / min above 1000℃). After calcination, cool to room temperature, remove, and grind into a fine powder to obtain the cyan fluorescent powder Ca. 7.5 Zn 1.5 Y(PO4)7: 0.005Eu 2+ .

[0060] Example 2 This embodiment provides a cyan phosphor, the chemical formula of which is Ca. 7.5 Zn 1.5 Y(PO4)7:xEu 2+ Where x = 0.01.

[0061] The preparation method of cyan phosphor is as follows: S1: Prepare the synthesis raw materials CaCO3, Y2O3, NH4H2PO4, ZnO and Eu2O3; S2: Weigh the synthetic raw materials from step S1 according to the stoichiometric ratio (i.e., the molar ratio of Ca, Zn, Y, PO4, and Eu in CaCO3, ZnO, Y2O3, NH4H2PO4, and Eu2O3 is 7.5:1.5:1:7:0.01). Mix the raw materials evenly in an agate mortar and grind them thoroughly for 20 minutes. Then place them in a corundum crucible and calcine them at 1300℃ for 4 hours in a muffle furnace under a carbon powder reducing atmosphere (heating rate of 10℃ / min below 1000℃, and 5℃ / min above 1000℃). After calcination, cool to room temperature, remove, and grind into a fine powder to obtain the cyan fluorescent powder Ca. 7.5 Zn 1.5 Y(PO4)7: 0.01Eu 2+ .

[0062] Example 3 This embodiment provides a cyan phosphor, the chemical formula of which is Ca. 7.5 Zn 1.5 Y(PO4)7:xEu 2+ Where x = 0.02.

[0063] The preparation method of cyan phosphor is as follows: S1: Prepare the synthesis raw materials CaCO3, Y2O3, NH4H2PO4, ZnO and Eu2O3; S2: Weigh the synthetic raw materials from step S1 according to the stoichiometric ratio (i.e., the molar ratio of Ca, Zn, Y, PO4, and Eu in CaCO3, ZnO, Y2O3, NH4H2PO4, and Eu2O3 is 7.5:1.5:1:7:0.02). Mix the raw materials evenly in an agate mortar, grind thoroughly for 20 minutes, and then place them in a corundum crucible. Then, under a carbon powder reducing atmosphere, calcine at 1300℃ for 4 hours in a muffle furnace (heating rate of 10℃ / min below 1000℃, and 5℃ / min above 1000℃). After calcination, cool to room temperature, remove, and grind into a fine powder to obtain the cyan fluorescent powder Ca. 7.5 Zn 1.5 Y(PO4)7: 0.02Eu 2+ .

[0064] Example 4 This embodiment provides a cyan phosphor, the chemical formula of which is Ca. 7.5 Zn 1.5 Y(PO4)7:xEu 2+ Where x = 0.03.

[0065] The preparation method of cyan phosphor is as follows: S1: Prepare the synthesis raw materials CaCO3, Y2O3, NH4H2PO4, ZnO and Eu2O3; S2: Weigh the synthetic raw materials from step S1 according to the stoichiometric ratio (i.e., the molar ratio of Ca, Zn, Y, PO4, and Eu in CaCO3, ZnO, Y2O3, NH4H2PO4, and Eu2O3 is 7.5:1.5:1:7:0.03). Mix the raw materials evenly in an agate mortar, grind thoroughly for 20 minutes, and then place them in a corundum crucible. Then, under a carbon powder reducing atmosphere, calcine at 1300℃ for 4 hours in a muffle furnace (heating rate of 10℃ / min below 1000℃, and 5℃ / min above 1000℃). After calcination, cool to room temperature, remove, and grind into a fine powder to obtain the cyan fluorescent powder Ca. 7.5 Zn 1.5 Y(PO4)7: 0.03Eu 2+ .

[0066] Example 5 This embodiment provides a cyan phosphor, the chemical formula of which is Ca. 7.5 Zn 1.5 Y(PO4)7:xEu 2+ Where x = 0.04.

[0067] The preparation method of cyan phosphor is as follows: S1: Prepare the synthesis raw materials CaCO3, Y2O3, NH4H2PO4, ZnO and Eu2O3; S2: Weigh the synthetic raw materials from step S1 according to the stoichiometric ratio (i.e., the molar ratio of Ca, Zn, Y, PO4, and Eu in CaCO3, ZnO, Y2O3, NH4H2PO4, and Eu2O3 is 7.5:1.5:1:7:0.04). Mix the raw materials evenly in an agate mortar, grind thoroughly for 20 minutes, and then place them in a corundum crucible. Then, under a carbon powder reducing atmosphere, calcine at 1300℃ for 4 hours in a muffle furnace (heating rate of 10℃ / min below 1000℃, and 5℃ / min above 1000℃). After calcination, cool to room temperature, remove, and grind into a fine powder to obtain the cyan fluorescent powder Ca. 7.5 Zn 1.5 Y(PO4)7: 0.04Eu 2+ .

[0068] Example 6 This embodiment provides a white LED device. The cyan phosphor prepared in Example 3 is mixed with commercially available red phosphor, green phosphor and blue phosphor in a mass ratio of 0.8:1:1:1 to obtain a mixed powder. The mixed powder is then mixed evenly with UV adhesive, coated on the surface of a 365nm ultraviolet LED chip and then encapsulated to obtain a white LED device.

[0069] Example 7 This embodiment provides a flexible light-emitting film. The cyan phosphor prepared in Example 3 is mixed with polydimethylsiloxane at a mass ratio of 1:10. The mixture is then evenly coated in a petri dish and heated at 80°C for 10 minutes before demolding to obtain the flexible light-emitting film.

[0070] Comparative Example 1 This comparative example provides a white LED device, which differs from Example 6 in that it does not contain cyan phosphor, but is otherwise the same as Example 6.

[0071] Performance testing I. Testing of Cyan Phosphor 1. Figure 1 The images show the X-ray diffraction (XRD) patterns of the cyan phosphors used in Examples 1-5. Figure 1 It can be seen that the diffraction angles and peak shapes of all diffraction peaks of the cyan phosphors in Examples 1-5 are basically consistent with the XRD patterns simulated based on the crystal structure of β-Ca3(PO4)2. Figure 1 This indicates that the cyan phosphor crystals in Examples 1-5 have sufficient growth time, resulting in high crystallinity and powder purity.

[0072] 2. Figure 2 This is the normalized excitation and emission spectrum of the cyan phosphor in Example 3. Figure 2 It can be seen that the emission spectrum of this cyan phosphor shows a broadband pattern centered at 495 nm, and the full width at half maximum (FWHM) of the emission spectrum is about 130 nm.

[0073] 3. The luminescence intensity of the cyan phosphor in Example 3 was tested under different operating temperature conditions (300K~480K) at an excitation wavelength of 365nm. The luminescence intensity graphs of the cyan phosphor under different operating temperature conditions were obtained. The test results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the cyan phosphor in Example 3 has excellent thermal stability. At an operating temperature of 400K, its luminescence intensity can still maintain 80.3% of that at an operating temperature of 300K (room temperature), which can ensure the luminescence stability of the device under long-term and high-power operation.

[0074] 4. The cyan phosphor of Example 3 was measured at room temperature using the integrating sphere absolute method. By recording the integrated intensities of the excitation light and the emission light, the ratio of the number of emitted photons to the number of absorbed excitation photons was calculated, and thus the internal quantum efficiency of the cyan phosphor of Example 3 was calculated. After testing, the internal quantum efficiency of the cyan phosphor of Example 3 was 85.13%.

[0075] II. Testing of white LED devices 1. Figure 4 is the spectral diagram of the white LED devices of Example 6 and Comparative Example 1. Figure 4 In it, a is Comparative Example 1 and b is Example 6. Figure 4 In it, BAM:Eu 2+ is the blue phosphor; CZYP:Eu 2+ is the cyan phosphor Ca 7.5 Zn 1.5 Y(PO4)7:0.02Eu 2+ ; YAG:Ce 3+ is the green phosphor; CaSN:Eu 2+ is the red phosphor. It can be seen from Figure 4 that Comparative Example 1 (conventional RGB-LED) without adding cyan phosphor has an obvious "cyan valley" between 480 and 520 nm. The spectrum of the white LED device (Example 6) after adding the cyan phosphor of Example 3 is perfectly filled in the 480 - 520 nm band. In addition, compared with Comparative Example 1, the special color rendering indices R5 (light blue-green) and R6 (light blue) of the white LED device of Example 6 are significantly improved, and the general color rendering index is as high as 96.0.

[0076] 2. The CIE analysis was carried out on the white LED device of Example 6, and the obtained chromaticity coordinate diagram (CIE coordinate diagram) is as Figure 5 shown. It can be seen from Figure 5 that the CIE chromaticity coordinates of the white LED device of Example 6 are (0.33, 0.31), extremely close to the ideal coordinates of pure white light, and the correlated color temperature is 5077 K, indicating its great application value in the field of high-quality full-spectrum healthy lighting.

[0077] 3. Figure 6 are the physical pictures of irradiating a purple doll with the white LED devices of Example 6 and Comparative Example 1 respectively. Figure 6 In it, a is Comparative Example 1 and b is Example 6. It can be seen from Figure 6 that compared with Comparative Example 1, the color rendering degree after irradiation by the device of Example 6 is extremely high, and the hue offset amount for the blue-violet color system is almost zero, and the visual perception is highly close to natural sunlight.

[0078] 4. The luminous intensity of the white LED device in Example 6 was tested under different operating temperature conditions (300K~480K) with an excitation wavelength of 365nm. The luminous intensity graphs of the white LED device under different operating temperature conditions were obtained. The test results are as follows: Figure 7 As shown. By Figure 7 It can be seen that the white LED device of Example 6 has excellent thermal stability. At an operating temperature of 400K, its luminous intensity can still maintain 73.3% of that at an operating temperature of 300K (room temperature).

[0079] III. Testing of Flexible Light-Emitting Thin Films 1. Figure 8 The flexible light-emitting film of Example 7 was bent ( Figure 8 (Above image) and tile ( Figure 8 (See image below), then in natural light ( Figure 8 (Left image) and ultraviolet light ( Figure 8 (Right side image) A photograph of the actual object under illumination. (By...) Figure 8 It can be seen that the flexible luminescent film has good flexibility under natural light and can be easily bent without breaking. Under ultraviolet light, the film emits a bright and uniform cyan-green fluorescence, proving that the cyan phosphor is well dispersed in the flexible polymer matrix.

[0080] 2. Figure 9 To illustrate the application of the flexible light-emitting film of Example 7 to springs and chips with different structures, a photograph of the actual product under natural light is provided. Figure 9 (The image above) and X-ray imaging ( Figure 9 (See the image below). Figure 9 As can be seen, the flexible light-emitting film of Example 7 possesses excellent flexibility, enabling it to perfectly conform to the curved and uneven surface of the test object (spring and chip). Under X-ray source excitation, the structure of the spring and chip encapsulated inside the film exhibits a clear, high-contrast black and white latent image, and the image is not distorted.

[0081] 3. Further testing of the flexible light-emitting film of Example 7 was conducted using standard line-to-card tests. Figure 10 This is an image of the flexible light-emitting thin film X-ray line pair card from Example 7. (The image is from...) Figure 10 It is known that the X-ray imaging spatial resolution of this flexible light-emitting film is as high as 7 lp / mm or more, which can meet the non-destructive testing requirements of precision micro electronic components.

[0082] 4. Figure 11 The following are the radiative emission spectra of the flexible luminescent thin film of Example 7 under ionizing radiation excitation at different dose rates. Based on these spectra, the linear relationship between the radiative emission intensity of the flexible luminescent thin film and the X-ray dose rate was calculated, and the results are as follows: Figure 12 As shown. By Figure 12It can be seen that at 115.6 nGy s -1 Up to 5.33 μGy s -1 Within the specified range, the radiative emission intensity of the thin film exhibits a good linear relationship with the X-ray dose rate, indicating that the flexible luminescent thin film of Example 7 is beneficial for obtaining good X-ray imaging contrast.

[0083] In summary, the cyan phosphor prepared in this embodiment of the invention exhibits excellent luminescent properties and can perfectly fill cyan gaps. The cyan phosphor of this embodiment achieves an external-internal quantum efficiency of up to 85.13% under 365nm excitation, and its emission spectrum has a full width at half maximum (FWHM) of approximately 130 nm. When applied to white LED devices, it significantly improves the color rendering index (CRI) to 96 and optimizes the correlated color temperature to 5077 K, greatly satisfying the demand for high-quality full-spectrum illumination. Furthermore, when the cyan phosphor of this embodiment is applied to flexible light-emitting films, it can conformally fit onto complex curved surfaces such as curved data cables, springs, and chips, easily bending without breaking. Imaging after X-ray detection shows no deformation or distortion. The spatial resolution of the prepared flexible film is above 7 lp / mm, significantly superior to traditional rigid X-ray detectors (approximately 5 lp / mm). Meanwhile, the flexible light-emitting film exhibits a good linear relationship with the X-ray dose rate, with a detection limit as low as 217.34 nGy / s, which is about 44 times lower than the requirements of conventional medical diagnosis, thus achieving high signal-to-noise ratio imaging under low radiation dose. The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A cyan fluorescent material, characterized in that, The chemical formula of the cyan fluorescent material is Ca. 9-y Zn y Y(PO4)7:xEu 2+ Where 0.005≤x≤0.04; 0.5≤y≤2.

2. The cyan fluorescent material according to claim 1, characterized in that, Under ultraviolet light excitation, the cyan fluorescent material possesses at least one of the following properties: (1) The emission spectrum is 480~520nm: (2) The full width at half maximum (FWHM) of the emission spectrum is ≥100 nm; (3) The center of the emission peak in the emission spectrum is located between 490 and 500 nm; (4) Internal quantum efficiency ≥ 80%; (5) The luminescence intensity retention rate is ≥80% at a working temperature of 420K; the luminescence intensity retention rate is the ratio of the luminescence intensity of the cyan fluorescent material at a working temperature of 420K to the luminescence intensity at a working temperature of 300K.

3. The method for preparing the cyan fluorescent material according to claim 1 or 2, characterized in that, Includes the following steps: Calcium source, yttrium source, zinc source, europium source and phosphate source are mixed evenly according to stoichiometric ratio to obtain a mixture; the mixture is subjected to a high-temperature solid-phase reaction under a reducing atmosphere to obtain the cyan fluorescent material.

4. The method for preparing the cyan fluorescent material according to claim 3, characterized in that, The calcium source includes at least one of calcium carbonate, calcium oxide, and calcium nitrate. And / or, the yttrium source includes at least one of yttrium oxide, yttrium fluoride, and yttrium vanadate; And / or, the zinc source includes at least one of zinc oxide and zinc silicate; And / or, the europium source includes at least one of europium oxide and europium nitrate; And / or, the phosphoric acid source includes at least one of ammonium dihydrogen phosphate and calcium hydrogen phosphate.

5. The method for preparing the cyan fluorescent material according to claim 3, characterized in that, The temperature of the high-temperature solid-phase reaction is 1200~1500℃; And / or, the high-temperature solid-phase reaction time is 2~6h.

6. A white LED device, characterized in that, The white LED device includes the cyan fluorescent material, red fluorescent material, green fluorescent material, blue fluorescent material, and ultraviolet LED chip as described in claim 1 or 2.

7. The white LED device according to claim 6, characterized in that, The white LED device has at least one of the following properties: (1) Color rendering index ≥ 95; (2) The correlated color temperature is 5000~6000K; (3) The luminous intensity retention rate is ≥70% at a working temperature of 420K; the luminous intensity retention rate is the ratio of the luminous intensity of the white LED device at a working temperature of 420K to the luminous intensity at a working temperature of 300K.

8. A flexible light-emitting thin film, characterized in that, The materials used to prepare the flexible light-emitting thin film include the cyan fluorescent material and polymer as described in claim 1 or 2.

9. The flexible light-emitting thin film according to claim 8, characterized in that, The X-ray imaging spatial resolution of the flexible light-emitting film is ≥7 lp / mm; And / or, the X-ray detection limit of the flexible light-emitting film is ≤230 nGy / s.

10. The application of the white LED device according to claim 6 or 7 in the field of lighting, or the application of the flexible light-emitting film according to claim 8 or 9 in the fields of flexible electronic devices, medical imaging, or non-destructive testing.

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