Rare earth doped tunable visible-near infrared dual-emission fluorescent powder and preparation method thereof

Abstract

The present invention discloses a rare earth doped adjustable visible-near infrared dual emission phosphor and a preparation method thereof. The chemical formula of the dual emission phosphor is Sr 5.82 Eu 0.18 Ge 2(1‑x) O7Cl6, where 0≤ x ≤0.12, based on halogen oxides and rare earth Eu 2+ As an activator. The raw materials are weighed according to the stoichiometric ratio, ground, placed in a sintering furnace, introduced into a reducing atmosphere, and sintered by a high-temperature solid-phase method to obtain a sintered body. The sintered body is ground to obtain a rare earth-doped adjustable visible-near-infrared dual-emission phosphor. This preparation method can change the intensity ratio of visible light and near-infrared light by adjusting the content of germanium, thereby accurately controlling the luminescent color and achieving white light and broadband near-infrared emission phenomena at the same time. The preparation method of the phosphor of the present invention is simple, low-cost, and the material is non-toxic, non-polluting, and non-radioactive, suitable for a wide range of applications.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid-state luminescent materials, and relates to a rare earth doped adjustable visible-near infrared dual-emission fluorescent powder and a preparation method thereof. BACKGROUND

[0002] Light is an indispensable element for plant growth, which provides energy for plants through photosynthesis. Traditional outdoor planting relies on sunlight, but the instability of natural light limits the uniform growth of plants. Artificial light sources, especially LED plant growth lamps, provide consistent light conditions for plants with their stability and adjustability. The Emerson effect indicates that plants can absorb more light through their photosensitive pigment P fr absorb about 730 nm of deep red light to near-infrared light, thereby accelerating photomorphogenesis and growth. White light LED lamps can provide photosynthetically active radiation of 400-700 nm wavelengths required by plants, especially blue and red light which are crucial for photosynthesis; but the spectrum of standard white light LED lamps often does not contain this key wavelength. Therefore, developing a new type of fluorescent powder that can supplement broadband near-infrared radiation while providing white light is of great significance to improve plant lighting effects.

[0003] In the research of fluorescent powder, it has always been a technical challenge to achieve broadband visible-near infrared dual-emission. At present, most studies are achieved by introducing two kinds of active ions into a single matrix. For example, Chen et al. successfully realized the dual-emission of blue-green (470 nm) and deep red (718 nm) in the Sr2LaGaO5 matrix through the co-doping of Bi 3+ and Mn 4+ , which meets the needs of plant growth for specific light sources. Similarly, Nag et al. used the co-doping technology of Cr 3+ and Bi 3+ to emit warm white light and broadband near-infrared light (1000 nm) at the same time in the Cs2Ag 0.6 Na 0.4 InCl6 double perovskite matrix, which provides a new technical means for fruit freshness detection. Although ion co-doping technology can achieve spectral adjustability, its synthesis conditions are often relatively complex and difficult. SUMMARY

[0004] The purpose of the present application is to provide a rare earth doped adjustable visible-near infrared dual-emission fluorescent powder, which realizes white light and broadband near-infrared dual-emission at the same time in a single component fluorescent material.

[0005] Another purpose of the present application is to provide a preparation method of the above-mentioned dual-emission fluorescent powder.

[0006] To achieve the above object, the technical scheme adopted by the present application is: a rare earth doped adjustable visible-near infrared double emission fluorescent powder, taking halogen oxide as a matrix, taking rare earth Eu 2+ As an activator, the chemical formula of the double emission fluorescent powder is Sr 5.82 Eu 0.18 Ge 2(1-x) O7Cl6, wherein 0≤ x ≤0.12.

[0007] Another technical scheme adopted by the present application is: a preparation method of the above double emission fluorescent powder, which is carried out according to the following steps:

[0008] 1) According to the stoichiometric ratio of the chemical formula Sr 5.82 Eu 0.18 Ge 2(1-x) O7Cl6, strontium carbonate, germanium oxide, strontium chloride and europium oxide are weighed respectively, put into an agate mortar, mixed uniformly, alcohol is added, mixed and ground to obtain a raw material mixture;

[0009] 1g of the mixed raw material needs 5mL of alcohol.

[0010] 2) The raw material mixture is placed in a sintering furnace, a reducing atmosphere is introduced, and a high-temperature solid phase method is adopted, first the furnace temperature is raised from room temperature to 200℃ for 30min, then the furnace temperature is raised to 850-950℃ at a rate of 2.5℃ / min, the furnace temperature is kept at 850-950℃ for 6-8h, then the furnace temperature is lowered to 500℃ at a rate of 2.5℃ / min, and finally the furnace is cooled to room temperature, the sintered body is ground, and the rare earth doped adjustable visible-near infrared double emission fluorescent powder is prepared.

[0011] The reducing atmosphere is composed of 15% H2 (hydrogen) and 85% Ar (argon) by volume percentage.

[0012] The high-temperature solid phase sintering involves heating the powdered raw materials at high temperature, and the sintering method of step 2) can promote the chemical reaction and physical combination between materials, thereby forming a dense solid material.

[0013] The double emission fluorescent powder has a wide excitation range, covering 290nm to 500nm, realizing full waveband response from ultraviolet to green light, and reaching a peak under 450nm blue light excitation. The double emission fluorescent powder also has a wide emission range (500-1100nm), and can produce visible light around 530nm and wideband (half peak width of 210nm) near infrared region around 740nm under the excitation of 450nm blue light, showing a significant double peak emission phenomenon.

[0014] The rare earth element europium (Eu 2+) has become a research focus in the field of luminescent materials due to its unique 4f-5d electron transition characteristics and excellent luminescence efficiency in the visible and near-infrared regions. 2+ The luminescence properties of ions are strongly dependent on their coordination environment and the crystal field in which they are located, which makes it possible to adjust their luminescence properties through crystal field engineering. Chloride oxide as a matrix has the advantages of excellent optical transmittance, chemical stability, and easy synthesis and processing, making it an ideal choice for phosphor research. At the same time, the electron cloud expansion effect brought about by the introduction of chloride ions not only increases the probability of long-wavelength emission of phosphors, but also 2+ Under the action of the activator, the spectral characteristics of the phosphor can be significantly adjusted. Therefore, the present invention adopts the chloride oxide matrix to achieve Eu 2+ As a single activator, it produces visible light and near-infrared light dual emission, thus bringing new breakthroughs to plant growth lighting LEDs.

[0015] The preparation method of the present invention finely controls Sr 5.82 Eu 0.18 Ge 2(1-x) The content of germanium in O7Cl6 phosphor is cleverly introduced into germanium vacancies, achieving the dual emission characteristics of visible light and broadband near-infrared in a single component phosphor. By reducing the content of germanium, the Eu 2+ The coordination environment of the ions causes a change in the lattice site occupancy ratio, thereby optimizing the ratio of visible light to near-infrared light emission intensity, and thus precisely controlling the luminescence color. This change in the lattice site occupancy ratio is directly related to the Eu 2+ The electronic structure and luminescence properties of ions. The introduction of germanium vacancies for Eu 2+ ions provide new electron transition paths, allowing Eu at specific lattice sites to 2+ The ions are more easily excited, thereby enhancing the ratio of visible light intensity to near-infrared light intensity while reducing the germanium content. Through this innovative lattice engineering strategy, the present invention expands the potential of this phosphor in white light lighting and near-infrared applications, providing new ideas for the design of new high-efficiency, multifunctional fluorescent materials, and is expected to play an important role in solid-state lighting technology.

[0016] The present invention uses a simple, low-cost, high-temperature solid-phase method to prepare dual-emission phosphors, which have the advantages of high yield and no agglomeration of powder particles. The dual-emission phosphors achieve both visible light and broadband near-infrared emission in a single-component fluorescent material.

[0017] To simplify the synthesis process and improve the performance of the phosphor, the present invention uses a single activator to achieve dual emission of visible light and broadband near-infrared light in a single component. The resulting dual-emission phosphor is non-toxic, pollution-free, and non-radioactive, making it suitable for a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is an X-ray diffraction (XRD) pattern of the dual-emitting phosphor prepared in Embodiment 1-5 of the present application.

[0019] Figure 2 is an excitation spectrum diagram of the dual-emitting phosphor prepared in Embodiment 2 of the present application.

[0020] Figure 3 is an emission spectrum diagram of the dual-emitting phosphor prepared in Embodiments 1-5 of the present application.

[0021] Figure 4 is a visible-near infrared light emission intensity relationship diagram of the dual-emitting phosphor prepared in Embodiments 1-5 of the present application. DETAILED DESCRIPTION

[0022] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Embodiment 1

[0024] According to the stoichiometric ratio in the chemical formula Sr 5.82 Eu 0.18 Ge2O7Cl6, x 0.2498 g of SrCO3, 0.1256 g of GeO2, 0.2853 g of SrCl2 and 0.0190 g of Eu2O3 were weighed out; they were placed in an agate mortar, an appropriate amount of alcohol was added, and they were thoroughly ground and mixed until uniform, then they were transferred to a corundum crucible, the corundum crucible was placed in a sintering furnace, a mixed gas atmosphere composed of 15% H2 and 85% Ar by volume was introduced into the sintering furnace, the temperature in the sintering furnace was first increased from room temperature to 200°C over 30 min, then the temperature was increased to 900°C at a rate of 2.5°C / min, the temperature was maintained at 900°C for 6 h, then the temperature in the furnace was decreased to 500°C at a rate of 2.5°C / min, and then it was naturally cooled to room temperature to obtain a sintered body, the sintered body was thoroughly ground, and a rare earth-doped adjustable visible-near infrared dual-emitting phosphor Sr 5.82 Eu 0.18 Ge2O7Cl6.

[0025] Embodiment 2

[0026] According to the stoichiometric ratio in the chemical formula Sr 5.82 Eu 0.18 Ge 1.94 O7Cl6, xSrCl2, and 0.0190 g of Eu2O3 in a volume ratio of 0.2498:0.1218:0.2853:0.0190 were weighed into a agate mortar, and an appropriate amount of alcohol was added, and the mixture was ground thoroughly and uniformly, and then was transferred into a corundum crucible, and the corundum crucible was placed into a sintering furnace, and a mixed gas atmosphere composed of 15% H2and 85% Ar by volume was introduced into the sintering furnace. The temperature in the sintering furnace was first increased from room temperature to 200°C over 30 min, and then the temperature in the furnace was increased to 900°C at a rate of 2.5°C / min, and after being kept at 900°C for 6 h, the temperature in the furnace was decreased to 500°C at a rate of 2.5°C / min, and then the sintered body was obtained by natural cooling to room temperature. The sintered body was ground thoroughly to obtain the rare earth doped adjustable visible-near infrared dual-emission phosphor Sr 5.82 Eu 0.18 Ge 1.94 O7Cl6.

[0027] The excitation spectrum of the dual-emission phosphor prepared in Example 2 is shown in FIG. 2. Figure 2 .

[0028] Example 3

[0029] According to the stoichiometric ratio of the chemical formula Sr 5.82 Eu 0.18 Ge 1.88 O7Cl6( x = 0.06), 0.2498 g of SrCO3, 0.1180 g of GeO2, 0.2853 g of SrCl2, and 0.0190 g of Eu2O3 were weighed, respectively, into an agate mortar, and an appropriate amount of alcohol was added, and the mixture was ground thoroughly and uniformly, and then was transferred into a corundum crucible, and the corundum crucible was placed into a sintering furnace, and a mixed gas atmosphere composed of 15% H2and 85% Ar by volume was introduced into the sintering furnace. The temperature in the sintering furnace was first increased from room temperature to 200°C over 30 min, and then the temperature in the furnace was increased to 900°C at a rate of 2.5°C / min, and after being kept at 900°C for 6 h, the temperature in the furnace was decreased to 500°C at a rate of 2.5°C / min, and then the sintered body was obtained by natural cooling to room temperature. The sintered body was ground thoroughly to obtain the rare earth doped adjustable visible-near infrared dual-emission phosphor Sr 5.82 Eu 0.18 Ge 1.88 O7Cl6.

[0030] Example 4

[0031] According to the stoichiometric ratio of the chemical formula Sr 5.82 Eu 0.18 Ge 1.82 O7Cl6( x=0.09), 0.2498g of SrCO3, 0.1142g of GeO2, 0.2853g of SrCl2, and 0.0190g of Eu2O3 were weighed and placed in an agate mortar. An appropriate amount of alcohol was added, and the mixture was thoroughly ground and mixed. The mixture was then transferred to a corundum crucible, which was placed in a sintering furnace. A mixed atmosphere consisting of 15% H2 and 85% Ar by volume was introduced into the sintering furnace. The temperature in the sintering furnace was first raised from room temperature to 200°C over 30 minutes, then raised to 900°C at a heating rate of 2.5°C / min. After maintaining the temperature at 900°C for 6 hours, the temperature was then lowered to 500°C at a cooling rate of 2.5°C / min. The mixture was then naturally cooled to room temperature to obtain a sintered body. The sintered body was thoroughly ground to produce a rare earth doped tunable visible-near-infrared dual-emission phosphor, Sr 5.82 Eu 0.18 Ge 1.82 O7Cl6.

[0032] Example 5

[0033] According to the chemical formula Sr 5.82 Eu 0.18 Ge 1.76 O7Cl6( x =0.12), 0.2498g of SrCO3, 0.1105g of GeO2, 0.2853g of SrCl2, and 0.0190g of Eu2O3 were weighed and placed in an agate mortar. An appropriate amount of alcohol was added, and the mixture was thoroughly ground and mixed. The mixture was then transferred to a corundum crucible, which was placed in a sintering furnace. A mixed atmosphere consisting of 15% H2 and 85% Ar by volume was introduced into the sintering furnace. The temperature in the sintering furnace was first raised from room temperature to 200°C over 30 minutes, then raised to 900°C at a heating rate of 2.5°C / min. After maintaining the temperature at 900°C for 6 hours, the temperature was then lowered to 500°C at a cooling rate of 2.5°C / min. The mixture was then naturally cooled to room temperature to obtain a sintered body. The sintered body was thoroughly ground to produce a rare earth doped tunable visible-near-infrared dual-emission phosphor Sr 5.82 Eu 0.18 Ge 1.76 O7Cl6.

[0034] Figure 1 is the X-ray diffraction (XRD) pattern of the dual-emission phosphor prepared in Examples 1 to 5. Figure 1 It can be seen that the diffraction peaks of the samples prepared in Examples 1 to 5 have a good correspondence with the calculated XRD spectra, and there are no identifiable trace impurity peaks, indicating that the samples of Examples 1 to 5 were successfully synthesized.

[0035] The emission spectrum of the dual-emission fluorescent powder prepared in Examples 1-5 is shown in Figure 3 . Figure 3 It is shown that, under blue light excitation at 450 nm, the dual-emission fluorescent powder exhibits a dual-peak emission with a peak at about 530 nm (visible light) and about 740 nm (near-infrared light).

[0036] The visible-near-infrared light intensity relationship diagram of the dual-emission fluorescent powder prepared in Examples 1-5 is shown in Figure 4 . It can be clearly observed that, as the Ge Figure 4 ion concentration decreases, the relative intensity of visible light and near-infrared light gradually increases. 4+ ​

Claims

1. A rare earth doped tunable visible-near-infrared dual-emission phosphor, characterized in that: The dual-emission phosphor uses halogen oxide as the matrix and rare earth Eu 2+ As an activator, its chemical formula is Sr 5.82 Eu 0.18 Ge 2(1-x) O7Cl6, where 0≤ x ≤0.

12.

2. The rare earth doped tunable visible-near-infrared dual-emission phosphor according to claim 1, characterized in that: This dual-emission phosphor produces dual-peak emission in the visible light and near-infrared regions under the excitation of 450nm blue light.

3. A method for preparing the rare earth doped tunable visible-near-infrared dual-emission phosphor according to claim 1, characterized in that: The preparation method is carried out according to the following steps: 1) According to the chemical formula Sr 5.82 Eu 0.18 Ge 2(1-x) Strontium carbonate, germanium oxide, strontium chloride and europium oxide are weighed and mixed in a stoichiometric ratio of 07Cl6 to obtain a mixed raw material, alcohol is added, and the mixture is ground to obtain a raw material mixture; 2) The raw material mixture is placed in a sintering furnace and introduced into a reducing atmosphere. The furnace temperature is first raised from room temperature to 200°C over 30 minutes, then raised to 850-950°C at a heating rate of 2.5°C / min, and maintained at 850-950°C for 6-8 hours. The furnace temperature is then lowered to 500°C at a cooling rate of 2.5°C / min, and finally cooled to room temperature with the furnace. The sintered body is ground to obtain a rare earth-doped tunable visible-near-infrared dual-emission phosphor.

4. The method for preparing the rare earth doped tunable visible-near-infrared dual-emission phosphor according to claim 3, characterized in that: In step 1), 5 mL of alcohol is required for 1 g of the mixed raw material.

5. The method for preparing the rare earth doped tunable visible-near-infrared dual-emission phosphor according to claim 3, characterized in that: In the step 2), the reducing atmosphere is composed of 15% H2 and 85% Ar by volume.

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