A phosphor, its preparation method and application

Abstract

This invention discloses a phosphor, its preparation method, and its application, belonging to the field of white LED lighting technology. It solves the problems in existing technologies where a single phosphor cannot emit white light, two phosphors result in low luminous efficiency of white LED lamps, and the encapsulation process for three phosphors is complex and costly. The phosphor has the chemical composition shown in formula (1): K3YSi 2‑x Hf x O7:yEu 2+ (1), where x is the mole fraction of Hf, 2-x is the mole fraction of Si, and y is the mole fraction of Eu, wherein 0.01≤x<2, 0.001≤y≤0.1. The phosphor of the present invention has the characteristics of high internal quantum efficiency of light emission, and the white LED device prepared from this single phosphor has a high color rendering index. Under the premise of ensuring white light emission and high internal quantum efficiency and color rendering index, the color temperature can be adjusted.

Description

Technical Field

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

[0002] With the continuous development of modern lighting technology, white LEDs, with their superior luminous efficacy, ultra-long lifespan, low power consumption, small size, and high reliability, have successfully replaced traditional lighting solutions such as incandescent and fluorescent lamps, becoming the absolute mainstream lighting product in the market. Their application areas have also rapidly expanded from initial indicator backlighting to various aspects such as indoor general lighting, commercial lighting, industrial lighting, automotive lighting, and display backlighting.

[0003] Currently, the mainstream technical approach for achieving commercial white LEDs is to use blue LED chips (usually based on InGaN material, with an emission wavelength of approximately 450-470nm) to excite a layer of yellow phosphor covering its surface. The most typical and widely used of these is YAG:Ce. 3+ The light-emitting principle is as follows: some of the blue light emitted by the chip mixes with the yellow light emitted after the phosphor is excited, creating the visual perception of white light in the human eye. This technical approach is popular due to its simple structure, high luminous efficiency, relatively controllable manufacturing costs, and high technological maturity. However, this "blue light + yellow light" solution has an inherent and fundamental flaw related to lighting quality: its emission spectrum severely lacks cyan light components in the 450-500nm wavelength range and deep red light components in the 600-680nm wavelength range. Cyan light is crucial for accurately reproducing the colors of objects such as water and glass, while deep red light directly affects the vibrancy of warm-colored objects such as meat, fruit, and skin. This spectral discontinuity directly leads to a generally low color rendering index (CRI) for such lamps. The CRI is a key indicator of a light source's ability to reproduce the true colors of objects; the lower the Ra value, the more severe the color distortion of objects under the light.

[0004] Therefore, developing full-spectrum lighting phosphors based on ultraviolet LED chips is of great significance for promoting the upgrading and development of the lighting industry and advancing the application of full-spectrum lighting. Summary of the Invention

[0005] In view of the above, the present invention aims to provide a phosphor and its preparation method and application, so as to solve at least one of the problems existing in the prior art: (1) the traditional blue light chip plus yellow phosphor scheme has a low color rendering index and distorted lighting color due to the lack of cyan and red light in the spectrum; (2) the preparation process of three-color phosphor is complicated and costly, and cannot be widely used; (3) a single phosphor cannot emit white light and has low internal quantum efficiency.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] The first aspect of the present invention provides a phosphor having a chemical composition as shown in formula (1):

[0008] K3YSi 2-x Hf x O7: yEu 2+ (1)

[0009] Where x is the mole fraction of Hf, 2-x is the mole fraction of Si, and y is the mole fraction of Eu, and 0.01≤x<2, 0.001≤y≤0.1.

[0010] Furthermore, the range of x is 0.1≤x≤0.12, 0.005≤y≤0.02.

[0011] Furthermore, under ultraviolet light excitation, the emission spectrum of the phosphor includes a blue light emission peak and a red light emission peak.

[0012] Furthermore, the phosphor has an internal quantum efficiency of ≥70%.

[0013] The second aspect of the present invention provides a method for preparing the phosphor described in the first aspect, comprising: mixing a K-containing compound, a Y-containing compound, a Si-containing compound, an Hf-containing compound, and an Eu-containing compound, and then heating and sintering them under a reducing atmosphere to obtain the phosphor.

[0014] Furthermore, the reducing atmosphere includes a nitrogen-hydrogen mixture, hydrogen, or carbon monoxide.

[0015] Furthermore, the heating rate is 3-10℃ / min, and sintering is carried out at 1100~1300℃ for 4-8 hours.

[0016] Furthermore, the K-containing compound is potassium carbonate and / or potassium hydroxide.

[0017] Furthermore, the Y-containing compound is yttrium oxide and / or yttrium carbonate.

[0018] Furthermore, the Si-containing compound is silicon dioxide and / or silicic acid.

[0019] Furthermore, the Hf-containing compound is hafnium oxide and / or hafnium hydroxide.

[0020] Furthermore, the Eu-containing compound is europium oxide and / or europium carbonate.

[0021] Furthermore, the molar ratios of the Y-containing compound (calculated as Y), the K-containing compound (calculated as K), the Si-containing compound (calculated as Si), the Hf-containing compound (calculated as Hf), and the Eu-containing compound (calculated as Eu) satisfy the following conditions: K:Y = 3:1, Hf:Y = x, and 0.01 ≤ x < 2, Si:Y = 2 - x, Eu:Y = y, and 0.001 ≤ y ≤ 0.1.

[0022] The third aspect of this invention provides the application of the phosphor described in the first aspect in the preparation of white LED devices.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] (1) This invention modulates the Hf in phosphors 4+ and Si 4+ The mole fraction of Eu regulates 2+ By altering the local crystal field environment at the lattice sites occupied by the phosphor, the phosphor is induced to emit bimodal blue and red light. This bimodal emission effectively fills the cyan and red light regions of the LED lighting spectrum, resulting in good overall continuity of the emission spectrum. This allows a single phosphor to directly emit white light with a high color rendering index (e.g., a color rendering index as high as 90 in Example 2) covering most of the visible light region under ultraviolet chip excitation, with a color temperature of 2000-5000K. This solves the problems of complex processes, high costs, and uneven color caused by multi-powder systems.

[0025] (2) This invention introduces Hf into the phosphor matrix 4+ This enhances the overall lattice rigidity and effectively suppresses Eu. 2 + The non-radiative loss of excited-state energy results in an internal quantum efficiency of up to 83.73% for the phosphor, ensuring high luminous efficacy of the fabricated LED device. Furthermore, the preparation method employs a mature high-temperature solid-state reaction process, with readily available raw materials and a simple process, fully compatible with existing phosphor production lines. It requires no complex or demanding synthesis conditions, possessing extremely low production conversion barriers and cost advantages, facilitating large-scale production and market promotion. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1 and Figure 2 The images show the XRD patterns of the phosphors prepared in Examples 1-10.

[0028] Figure 3 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 3 are shown.

[0029] Figure 4 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 4 are shown.

[0030] Figure 5 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 5 are shown.

[0031] Figure 6 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 6 are shown.

[0032] Figure 7 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 1 are shown.

[0033] Figure 8 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 2 are shown.

[0034] Figure 9 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 7 are shown.

[0035] Figure 10 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 8 are shown.

[0036] Figure 11 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 9 are shown.

[0037] Figure 12 The excitation spectrum (a) and emission spectrum (b) of the phosphor prepared in Example 10 are shown.

[0038] Figure 13 The image shows the internal quantum efficiency of the phosphor prepared in Example 3.

[0039] Figure 14 The image shows the internal quantum efficiency of the phosphor prepared in Example 4.

[0040] Figure 15 The image shows the internal quantum efficiency of the phosphor prepared in Example 5.

[0041] Figure 16 The image shows the internal quantum efficiency of the phosphor prepared in Example 6.

[0042] Figure 17 The image shows the internal quantum efficiency of the phosphor prepared in Example 1.

[0043] Figure 18 The graph shows the internal quantum efficiency of the phosphor prepared in Example 2.

[0044] Figure 19 The image shows the internal quantum efficiency of the phosphor prepared in Example 7.

[0045] Figure 20 The image shows the internal quantum efficiency of the phosphor prepared in Example 8.

[0046] Figure 21 The graph shows the internal quantum efficiency of the phosphor prepared in Example 9.

[0047] Figure 22 The graph shows the internal quantum efficiency of the phosphor prepared in Example 10.

[0048] Figure 23 The image shows the white LED device encapsulated with phosphor prepared in Example 3, along with its test spectrum.

[0049] Figure 24 The image shows the phosphor-encapsulated white LED device and its test spectrum obtained in Example 4.

[0050] Figure 25 The image shows a white LED device encapsulated with phosphor prepared in Example 5, along with its test spectrum.

[0051] Figure 26 The image shows the phosphor-encapsulated white LED device and its test spectrum obtained in Example 6.

[0052] Figure 27 The image shows the white LED device encapsulated with phosphor prepared in Example 1, along with its test spectrum.

[0053] Figure 28 The image shows the white LED device encapsulated with phosphor prepared in Example 2, along with its test spectrum.

[0054] Figure 29 The image shows the phosphor-encapsulated white LED device and its test spectrum obtained in Example 7.

[0055] Figure 30 The image shows the white LED device encapsulated with phosphor prepared in Example 8, along with its test spectrum.

[0056] Figure 31 The image shows the phosphor-encapsulated white LED device and its test spectrum obtained in Example 9.

[0057] Figure 32 The image shows the phosphor-encapsulated white LED device and its test spectrum obtained in Example 10.

[0058] Figure 33 Comparative Example 1 uses YAG:Ce 3+Schematic diagram and test spectrum of a white LED device packaged with phosphor and blue LED chip. Detailed Implementation

[0059] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0060] Because existing single phosphors cannot emit white light, while two phosphors result in a low color rendering index, and three phosphors have complex and costly processes, the first aspect of this invention provides a phosphor having the chemical composition shown in formula (1):

[0061] K3YSi 2-x Hf x O7: yEu 2+ (1)

[0062] Where x is the mole fraction of Hf, 2-x is the mole fraction of Si, and y is the mole fraction of Eu, and 0.01≤x<2, 0.001≤y≤0.1.

[0063] In this invention, by utilizing Hf 4+ Partially replaces Si 4+ (By adjusting the molar fractions of the two components in the phosphor) and utilizing the significant difference in their ionic radii, strain is introduced into the crystal lattice to alter the Eu content. 2+ The local crystal field environment at the luminescent center promotes Eu 2+ Occupying two different lattice sites in the crystal lattice, the phosphor induces the simultaneous generation of blue and red light emission peaks. The emission spectrum of the phosphor can completely cover the visible light region, thereby directly achieving white light emission characteristics with a high color rendering index.

[0064] Furthermore, by adjusting the x-value, the blue / red light intensity ratio can be precisely adjusted, enabling flexible control of the color temperature. Simultaneously, the optimized y-value range ensures Eu... 2+ As a highly efficient light-emitting center, it achieves excellent internal quantum efficiency (IQE), laying the material foundation for manufacturing high-performance, low-cost single-phosphor white LED devices.

[0065] According to some embodiments of the present invention, the value of x is in the range of 0.01 ≤ x < 2.

[0066] In this invention, when x>2, it means Hf 4+ Excessive content can introduce excessive lattice strain, potentially leading to crystal structure instability or even the formation of impurity phases, disrupting the main crystalline structure of the matrix, and thus significantly reducing the internal quantum efficiency. When x < 0.01, it means that Hf 4+Insufficient content of x fails to effectively alter the local crystal field environment of the matrix lattice, resulting in a lack of blue light component in the emission spectrum. This prevents the formation of a balanced full-spectrum emission, leading to a decrease in the color rendering index and a lower color temperature of the LED device. For example, the value of x can be 0.1, 0.11, 0.12, 0.13, 0.15, 0.16, 0.18, 0.2, 0.3, or any combination of two of these values. Preferably, 0.02 ≤ x ≤ 0.3, and more preferably, 0.1 ≤ x ≤ 0.12.

[0067] In this invention, when x satisfies 0.1-0.12, Hf 4+ For Si 4+ The substitution of [substituent name] can more effectively control the crystal field, so that the blue and red light emission peaks generated by Eu2+ can reach an ideal intensity balance. It can stably prepare white phosphors with color temperatures in the range of 2000K to 5000K. In this range, the phosphors have excellent crystallinity and high luminous efficiency, and can achieve an internal quantum efficiency of not less than 70%.

[0068] Furthermore, considering that when y is less than 0.001, Eu 2+ If the doping level is too low, the number of luminescent centers will be insufficient, resulting in weak luminescence intensity of the phosphor, which will be difficult to meet the brightness requirements of practical lighting applications; when y is greater than 0.1, excessively high Eu² will lead to insufficient luminescence intensity. + Doping concentration can cause concentration quenching. Excessive activator ions intensify energy transfer, leading to an increased probability of non-radiative transitions, which in turn reduces the phosphor's luminescence intensity. When 0.001 ≤ y ≤ 0.1, it is possible to ensure a sufficient number of luminescent centers while effectively avoiding concentration quenching, thus maximizing Eu's luminescence intensity. 2+ Ions in K3YSi 2-x Hf x Efficient and stable luminescence is achieved in the O7 matrix. Within this preferred range of y values, Eu... 2+ Ions can uniformly replace K + / Y 3+ The lattice sites are used to achieve charge compensation and benefit from Hf 4+ Replace Si 4+ The introduced lattice strain creates a reasonable energy distribution between the blue and red light emission centers, thereby synergistically achieving full visible light coverage of the emission spectrum and high internal quantum efficiency (≥70%).

[0069] For example, the value of y can be 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.06, 0.08, or 0.1, preferably 0.01 to 0.015.

[0070] According to some embodiments of the present invention, under ultraviolet light excitation, the emission spectrum of the phosphor includes a blue light emission peak and a red light emission peak.

[0071] In this invention, when the structure of the phosphor satisfies the chemical composition shown in formula (1), and the values ​​of x and y are limited as described above, it is possible to achieve the blue and red bimodal emission characteristics of a single phosphor under ultraviolet light excitation.

[0072] It is understood that the wavelength of the ultraviolet light can be 365nm.

[0073] It should be noted that the phosphor emits visible light in the 400-850nm wavelength range.

[0074] According to some specific embodiments of the present invention, the internal quantum efficiency of the phosphor can reach up to 83.73%.

[0075] The second aspect of the present invention provides a method for preparing the phosphor described in the first aspect, comprising: mixing a K-containing compound, a Y-containing compound, a Si-containing compound, an Hf-containing compound, and an Eu-containing compound, and then heating and sintering them under a reducing atmosphere to obtain the phosphor.

[0076] In this invention, the raw materials are mixed and sintered under a reducing atmosphere, which enables the stable trivalent europium (Eu) to be sintered. 3+ ) ions are reduced to divalent europium (Eu) 2+ (Ions) are a necessary condition for achieving efficient luminescence, ensuring the luminescent centers and high-efficiency luminescence performance in the final product.

[0077] Furthermore, this method is simple in process, has low production cost, and is well compatible with traditional phosphor production lines, making it easy to achieve mass production. It has a very promising application prospect in the field of white LED lighting.

[0078] In this invention, the mixing of K-containing compounds, Y-containing compounds, Si-containing compounds, Hf-containing compounds, and Eu-containing compounds can be carried out in an agate mortar. Specifically, the raw materials are thoroughly ground for 20-40 minutes, and then the ground raw materials are transferred to a corundum crucible and heated and sintered in a reduction tube furnace.

[0079] Furthermore, in the method, the product after heating and sintering in the reduction tube furnace is cooled to room temperature and then ground again, and then sieved (3-20µm) to obtain phosphor.

[0080] According to some embodiments of the present invention, in order to enable Eu element to achieve white light emission characteristics in a crystal matrix, it is preferable to react trivalent Eu in Eu-containing compounds under a reducing atmosphere. 3+ Reduced to divalent Eu2+ The reducing atmosphere includes a nitrogen-hydrogen mixture, hydrogen, or carbon monoxide.

[0081] In this invention, by way of example, the nitrogen-hydrogen mixture can specifically be 1-5 vol% hydrogen + 95-99 vol% nitrogen.

[0082] According to some embodiments of the present invention, the heating rate in the reduction tube furnace is 3-10℃ / min, and sintering is carried out at 1100~1300℃ for 4-8 hours.

[0083] In this invention, the appropriate heating rate ensures stable decomposition of raw materials and release of reaction gases, avoids powder splashing, and ensures uniform product morphology. Sintering at 1100~1300℃ for 4-8 hours ensures that the reactants can fully diffuse and react completely to form a pure phase, while allowing the grains to grow to a suitable size. This enables the stable and repeatable preparation of high-crystal quality and high-performance phosphors, avoiding impurities, defects, or decreased luminescence performance caused by improper processes.

[0084] According to some embodiments of the present invention, the K-containing compound is potassium carbonate and / or potassium hydroxide, the Y-containing compound is yttrium oxide and / or yttrium carbonate, the Si-containing compound is silicon dioxide and / or silicic acid, the Hf-containing compound is hafnium oxide and / or hafnium hydroxide, and the Eu-containing compound is europium oxide and / or europium carbonate.

[0085] According to some embodiments of the present invention, the molar ratios of the Y-containing compound (calculated as Y), the K-containing compound (calculated as K), the Si-containing compound (calculated as Si), the Hf-containing compound (calculated as Hf), and the Eu-containing compound (calculated as Eu) satisfy the following conditions: K:Y = 3:1, Hf:Y = x, and 0.01 ≤ x < 2, Si:Y = 2 - x, Eu:Y = y, and 0.001 ≤ y ≤ 0.1. This ensures that during the high-temperature solid-state reaction, each element strictly conforms to the target chemical formula K3YSi. 2-x Hf x O7: yEu 2+ To carry out a stoichiometric reaction, Hf 4+ Precise replacement of Si 4+ The lattice sites of Eu can be used to effectively regulate the crystal structure. 2+The local crystal field environment of the luminescent center induces it to simultaneously occupy two different lattice sites in the crystal lattice that emit blue and red light. This results in phosphors with high crystallinity and phase purity, achieving an ideal intensity balance between blue and red light peaks in the emission spectrum, fully covering the 400-850nm visible light region. Ultimately, a single phosphor can directly emit white light with a high color rendering index (Ra≥90) under ultraviolet chip excitation, with an internal quantum efficiency of over 83%, achieving synergistic optimization of material luminescence performance and phase stability. Preferably, the molar ratios of the Y-containing compound (calculated as Y), K-containing compound (calculated as K), Si-containing compound (calculated as Si), Hf-containing compound (calculated as Hf), and Eu-containing compound (calculated as Eu) satisfy the following conditions: K:Y=3:1, Hf:Y=x, and 0.1≤x<0.12, Si:Y=2-x, Eu:Y=y, and 0.01≤y≤0.015.

[0086] According to some preferred embodiments of the present invention, the molar ratio of the Y-containing compound (calculated as Y), the K-containing compound (calculated as K), the Si-containing compound (calculated as Si), the Hf-containing compound (calculated as Hf), and the Eu-containing compound (calculated as Eu) is 1:3:1.88-1.9:0.1-0.12:0.001-0.015.

[0087] The third aspect of this invention provides the application of the phosphor described in the first aspect in the preparation of white LED devices.

[0088] For example, the method for preparing the white LED device includes: weighing silicone rubber (silicone rubber A and silicone rubber B), then adding a certain proportion of phosphor (the mass ratio of phosphor to silicone rubber is 1:2~4) and mixing evenly. The mixed colloid is coated onto a UV LED chip, kept at 90°C for 1 hour, and then heated to 150°C and kept at 150°C for 4 hours to ensure the silicone rubber is fully cured, thereby obtaining the white LED device.

[0089] In this invention, the white LED device contains the phosphor described in the first aspect, which can achieve a color rendering index of not less than 70 (up to 90 in Example 2), and the color temperature is adjustable within 2000-5000K, preferably between 2038-4940K, and can display warm white light or cool white light characteristics according to actual needs.

[0090] The advantages of the method of the present invention will be illustrated below through examples.

[0091] In the following examples, the crystal structure of the phosphor was tested using an X'Pert PRO X-ray diffractometer.

[0092] Excitation and emission spectra were measured using an Edinburgh (FL1000) fluorescence spectrometer.

[0093] The internal quantum efficiency of luminescence was measured using an Edinburgh (FL1000) fluorescence spectrometer.

[0094] The color rendering index and color temperature of the white LED device were tested using the Far East HAAS-2000.

[0095] The ultraviolet LED chip was purchased from Youjingxi Optoelectronics Factory on Taobao, with an emission wavelength of 365-370nm.

[0096] Organic silicone A and organic silicone B were purchased from a Taobao store selling LED accessories for scientific research. The mass ratio of organic silicone A to organic silicone B is 1:4.

[0097] Example 1

[0098] Potassium carbonate, yttrium oxide, silicon dioxide, hafnium dioxide, and europium oxide were added to an agate mortar in a molar ratio of 3:1:3.8:0.2:0.01 (where the molar ratio of K, Y, Si, Hf, and Eu was 3:1:1.9:0.1:0.01). The mixture was ground thoroughly for 30 minutes to obtain a mixed raw material. This material was then transferred to a corundum crucible and sintered in a reducing tube furnace under a reducing atmosphere. Specifically, the temperature was increased to 1250℃ at a rate of 5℃ / min, and the sintering time was 8 hours. The reducing atmosphere consisted of 5 vol% hydrogen and 95 vol% nitrogen. Finally, the sintered product was ground and sieved to obtain K3YSi. 1.9 Hf 0.1 O7:0.01Eu 2+ Fluorescent powder.

[0099] The phosphor was tested by XRD, as shown below. Figure 1 As shown, K3YSi 1.9 Hf 0.1 O7: 0.01Eu 2+ The main XRD diffraction peaks of the phosphor are still related to K3YSi2O7: 0.01Eu. 2+ To remain consistent indicates that when Hf 4+ For Si 4+ When the substitution ratio is 0.1 (x is 0.1), the crystal structure of the phosphor remains basically unchanged, but some new diffraction peaks also appear, indicating that Hf 4+ The ions successfully entered the crystal lattice and caused partial changes in the crystal structure of the K3YSi2O7 matrix.

[0100] When excited by ultraviolet light at a wavelength of 365 nm, the phosphor exhibits bimodal emission with peak wavelengths at 460 nm and 620 nm, and the emission spectrum covers the visible light band of 400-850 nm. Figure 7 It has the characteristic of emitting white light across the entire spectrum.

[0101] This phosphor also exhibits excellent luminescence properties, with a measured internal quantum efficiency of up to 82.99%. Figure 17 Because this phosphor exhibits white light emission under ultraviolet light excitation, it was packaged with a commercial 365nm ultraviolet chip to form a white light device. Specifically: Organic silicone (organic silicone A and organic silicone B) were weighed, and then the prepared phosphor (the mass ratio of phosphor to organic silicone was 1:4) was added and mixed evenly to obtain a mixed colloid. The mixed colloid was coated onto the ultraviolet LED chip and kept at 90℃ for 1 hour, then heated to 150℃ and kept at 150℃ for 4 hours to ensure the organic silicone was fully cured, thus obtaining a white light LED device. Testing showed that the device had a color rendering index as high as 89.2 and a color temperature of 4940K. Figure 27 It has a good lighting effect.

[0102] Example 2

[0103] Potassium carbonate, yttrium oxide, silicon dioxide, hafnium dioxide, and europium oxide were added to an agate mortar in a molar ratio of 3:1:3.76:0.24:0.01 (where the molar ratio of K, Y, Si, Hf, and Eu was 3:1:1.88:0.12:0.01). The mixture was ground thoroughly for 30 minutes to obtain a mixed raw material. This mixed material was then transferred to a corundum crucible and sintered in a reducing tube furnace under a reducing atmosphere. Specifically, the temperature was increased to 1250℃ at a rate of 5℃ / min, and the sintering time was 8 hours. The reducing atmosphere consisted of 5 vol% hydrogen and 95 vol% nitrogen. Finally, the sintered product was ground and sieved to obtain K3YSi. 1.88 Hf 0.12 O7: 0.01Eu 2+ Fluorescent powder.

[0104] like Figure 8 As shown, when Hf 4+ For Si 4+ When the substitution ratio is increased to 0.12, the proportion of blue light in the emission spectrum of the phosphor in Example 2 decreases, while the proportion of red light increases, exhibiting warm white light emission characteristics. The luminescence internal quantum efficiency of this phosphor is 83.73% ( Figure 18 The phosphor was encapsulated with a 365nm ultraviolet chip to form a white light device (preparation method is the same as in Example 1). The color rendering index of the white light device is as high as 90, and the color temperature is reduced to 3900K. Figure 28 (This) exhibits a warm white light lighting effect.

[0105] Examples 3-10

[0106] Following the method of Example 1, except that the proportions of the raw materials were changed, Hf was prepared separately. 4+ For Si4+ Phosphors with substitution ratios of 0.02, 0.04, 0.06, 0.08, 0.14, 0.16, 0.18, and 0.2, and whose chemical compositions are K3YSi, respectively. 1.98 Hf 0.02 O7: 0.01Eu 2+ 、K3YSi 1.96 Hf 0.04 O7:0.01Eu 2+ K3YSi 1.94 Hf 0.06 O7:0.01Eu 2+ K3YSi 1.92 Hf 0.08 O7: 0.01Eu 2+ K3YSi 1.86 Hf 0.14 O7:0.01Eu 2+ K3YSi 1.84 Hf 0.16 O7:0.01Eu 2+ 、K3YSi 1.82 Hf 0.18 O7:0.01Eu 2+ 、K3YSi 1.8 Hf 0.2 O7:0.01Eu 2+ .

[0107] The luminescence quantum efficiency of the above phosphor was tested, and it was fabricated into an LED device. The color rendering index and color temperature of the device were also tested. The results are shown in Table 1. Figures 3-6 Excitation and emission spectra of phosphors Figures 9-12 Excitation and emission spectra of the phosphor.

[0108] Examples 11-13

[0109] Following the method of Example 1, except that the amount of europium oxide was changed, K3YSi was prepared respectively. 1.9 Hf 0.1 O7: 0.002Eu 2+ K3YSi 1.9 Hf 0.1 O7:0.1 Eu 2+ K3YSi 1.9 Hf 0.1 O7: 0.015Eu 2+ Fluorescent powder.

[0110] Comparative Example 1

[0111] Commercial YAG:Ce3+ Phosphors were packaged with commercial blue LED chips to prepare white LED devices, and the color rendering index and color temperature were tested. The results are shown in Table 1.

[0112] Comparative Example 2

[0113] Following the method of Example 1, except that hafnium dioxide was replaced with an equal amount of zirconium dioxide, K3YSi was prepared. 1.9 Zr 0.1 O7: 0.01Eu 2+ Fluorescent powder.

[0114] The prepared K3YSi 1.9 Zr 0.1 O7: 0.01Eu 2+ The phosphor was used to fabricate an LED device, which was then tested. Under ultraviolet light excitation, it only emitted orange-red light. The results are shown in Table 1.

[0115] Comparative Example 3

[0116] Following the method of Example 1, except that hafnium dioxide was not added, K3YSi2O7: 0.01Eu was prepared. 2+ Phosphor. K3YSi2O7: 0.01Eu 2+ When phosphors were fabricated into LED devices, the results showed that phosphors without Hf doping exhibited only orange-red light emission under ultraviolet light excitation, with no blue light emission peak. The orange-red light emission peak was located at 620 nm.

[0117] Comparative Example 4

[0118] Following the method of Example 1, except that the amount of europium oxide was changed, K3YSi was prepared. 1.9 Hf 0.1 O7:0.2Eu 2+ .

[0119] Due to Eu 2+ If the doping concentration is too high, the phosphor will experience a concentration quenching effect, resulting in no light emission.

[0120] Comparative Example 5

[0121] Following the method of Example 1, except that europium oxide was not added, K3YSi was prepared. 1.9 Hf 0.1 O7, due to K3YSi 1.9 Hf 0.1 O7 is a matrix without luminescent ions and does not emit light.

[0122] Table 1

[0123]

[0124] As shown in Table 1, the K3YSi2O7 in Comparative Example 3 has a content of 0.01 Eu. 2+ The sample only emits orange-red light, and the color temperature of the orange-red light is relatively low. With Hf 4+ As the doping ratio x increases, the proportion of blue light in the emission spectrum of the corresponding sample gradually increases. Since blue light has a higher color temperature, the color temperature of the packaged LED device also shows an increasing trend. When Hf 4+ When the doping ratio x=0.1, the blue light proportion in the emission spectrum of the sample from Example 1 reaches its maximum, and correspondingly, the LED device packaged using the sample from Example 1 also has the highest color temperature. However, with Hf 4+ As the doping ratio x further increases, the proportion of blue light in the emission spectrum of the corresponding example samples begins to gradually decrease, for example, in Example 2, Hf 4+ When the doping ratio x=0.12, the color temperature of the packaged LED device also gradually decreases to 3900K. Therefore, when Hf 4+ The doping ratio x is in the range of 0.02 to 0.1. As x increases, the color temperature gradually increases. 4+ When the doping ratio x exceeds 0.1, the color temperature decreases with increasing x, and the color temperature increases with Hf. 4+ The doping ratio x shows a trend of first increasing and then decreasing.

[0125] Comparative Examples 2 and 3 all emit orange-red light, and their spectra do not contain any blue light components, thus they cannot form white light with a high color rendering index.

[0126] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A fluorescent powder, characterized in that, The phosphor has the chemical composition shown in formula (1): K3YSi 2-x Hf x O7: yEu 2+ (1) Where x is the mole fraction of Hf, 2-x is the mole fraction of Si, and y is the mole fraction of Eu, with 0.08≤x≤0.18 and 0.005≤y≤0.

02.

2. The phosphor according to claim 1, characterized in that, The range of x is 0.1≤x≤0.12, 0.005≤y≤0.

02.

3. The phosphor according to claim 1, characterized in that, Under ultraviolet light excitation, the emission spectrum of the phosphor includes a blue light emission peak and a red light emission peak.

4. The phosphor according to claim 1, characterized in that, The phosphor has an internal quantum efficiency of ≥70%.

5. A method for preparing the phosphor according to any one of claims 1-4, characterized in that, include: The phosphor is obtained by mixing a K-containing compound, a Y-containing compound, a Si-containing compound, an Hf-containing compound, and an Eu-containing compound, and then heating and sintering the mixture under a reducing atmosphere.

6. The preparation method according to claim 5, characterized in that, The reducing atmosphere includes a nitrogen-hydrogen mixture, hydrogen, or carbon monoxide.

7. The preparation method according to claim 5, characterized in that, The heating rate under the reducing atmosphere is 3-10℃ / min, and sintering is carried out at 1100~1300℃ for 4-8 hours.

8. The preparation method according to claim 5, characterized in that, The K-containing compound is potassium carbonate and / or potassium hydroxide; And / or, the Y-containing compound is yttrium oxide and / or yttrium carbonate; And / or, the Si-containing compound is silicon dioxide and / or silicic acid; And / or, the Hf-containing compound is hafnium oxide and / or hafnium hydroxide; And / or, the Eu-containing compound is europium oxide and / or europium carbonate.

9. The preparation method according to any one of claims 5-8, characterized in that, The molar ratios of Y-containing compounds, K-containing compounds, Si-containing compounds, Hf-containing compounds, and Eu-containing compounds (calculated as Y) satisfy the following conditions: K:Y = 3:1, Hf:Y = x, and 0.08 ≤ x ≤ 0.18, Si:Y = 2 - x, Eu:Y = y, and 0.005 ≤ y ≤ 0.

02.

10. The use of the phosphor according to any one of claims 1-4 in the preparation of white LED devices.

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