Inorganic luminescent material and method for producing the same

Abstract

The present invention discloses an inorganic light-emitting material and a preparation method thereof. The general formula of the light-emitting material provided by the present invention is Zn x Mg 1‑ x AM 10 O 17 :yCr 3+ ; wherein, 0 ≤ x ≤ 1, 0 < y ≤ 0.06; A is selected from one or more of the elements Ca, Sr or Ba; M is selected from one or more of the elements Al, Ga, Sc or Y; in this application, Cr 3+ is a luminescence activation ion. By regulating the matrix elements Zn, Mg, A, and M, the emission is mainly high-efficiency far red light with a peak of about 680 nm to 780 nm. The light-emitting material of the present invention has high light conversion efficiency, good thermal stability and chemical stability, and can be used for plant light supplementation. The far red light emitted by it can optimize the plant morphological structure through light signal regulation, and at the same time improve the light energy utilization efficiency, and is suitable for the light supplementation cultivation of high-value crops.

Description

Technical Field

[0001] This invention relates to the field of inorganic functional materials technology, and in particular to an inorganic luminescent material and its preparation method. Background Technology

[0002] In modern agricultural production, artificial lighting technology is one of the core technologies for achieving high-quality development of precision agriculture and facility agriculture. The photosynthetic system and photoreceptors of crops are highly selective for specific spectra. Among them, far-red light with wavelengths of 700nm~750nm has irreplaceable physiological functions in regulating plant photomorphogenesis, breaking photoinhibition, improving photosynthetic efficiency, optimizing plant shape, and shortening the growth cycle.

[0003] Light conversion materials can efficiently convert a portion of broadband excitation light into far-red light beneficial to plant growth, making them core materials for improving the light energy utilization rate and optimizing light formulation in supplemental lighting systems. However, current light conversion materials suitable for plant supplemental lighting suffer from three major technological shortcomings:

[0004] Most materials emit red light primarily in the 600nm~670nm range, lacking efficient and stable far-red light emission around 700nm. Furthermore, existing materials exhibit poor thermal and chemical stability, easily leading to luminescence degradation and short lifespan under high temperature, high humidity, and long-term high-intensity light exposure, failing to meet the requirements for long-term stable applications. Additionally, most materials involve complex preparation processes and high raw material costs, hindering large-scale promotion and application.

[0005] Therefore, developing a novel light conversion material that can efficiently emit far-red light from a target under excitation by multiple types of light sources, has high spectral matching, excellent stability, and a simple preparation process is of great application value for constructing an efficient and stable plant supplemental lighting system and promoting the development of precision agriculture. Summary of the Invention

[0006] In view of this, this application provides an inorganic luminescent material and its preparation method. The material exhibits strong and stable far-red light emission at about 700 nm, and also has high light conversion efficiency, excellent thermal stability and chemical stability. At the same time, the preparation method of the inorganic luminescent material of this application is simple and has low raw material cost, making it suitable for large-scale industrial production.

[0007] This application provides an inorganic luminescent material as shown in formula (I):

[0008] Zn x Mg 1-x AM 10 O 17 :yCr 3+ Formula (I);

[0009] Where 0≤x≤1, 0 <y≤0.06;

[0010] A is selected from one or more of the elements Ca, Sr, and Ba;

[0011] M is selected from one or more of the elements Al, Ga, Sc, and Y.

[0012] In some specific implementations, A is selected from one or both of Ba and Sr; M is selected from one or both of Al and Ga.

[0013] In some specific implementations, 0.01 <y≤0.06。

[0014] In some specific implementations, the structure is shown in equations (I-1) to (I-6):

[0015] ZnBaAl 10 O 17 0.02Cr 3+ Formula (I-1); ZnBaAl8Ga2O 17 0.02Cr 3+ Formula (I-2);

[0016] ZnBaAl5Ga5O 17 0.04Cr 3+ Formula (I-3); MgBaAl8Ga2O 17 0.02Cr 3+ Formula (I-4);

[0017] Zn 0.5 Mg 0.5 BaAl 10 O 17 0.06Cr 3+ Equation (I-5); ZnBa 0.8 Sr 0.2 Al 10 O 17 0.04Cr 3+ Formula (I-6).

[0018] Furthermore, this application also provides a method for preparing the above-mentioned inorganic luminescent material, comprising the following steps:

[0019] 1) Mix Zn-containing compounds, Mg-containing compounds, A-containing compounds, M-containing compounds and chromium-containing compounds uniformly according to the molar ratio of each element in the material shown in formula (I) to obtain a precursor;

[0020] 2) The precursor obtained in step 1) is sintered to obtain an inorganic luminescent material.

[0021] In some specific implementation manners, in step 1), the Zn-containing compound is selected from one or more of zinc oxide, zinc carbonate, zinc nitrate, zinc acetate or zinc hydroxide;

[0022] The Mg-containing compound is selected from one or more of magnesium oxide, magnesium carbonate, magnesium nitrate, magnesium acetate or magnesium hydroxide;

[0023] The compound containing element A is selected from one or more of the oxide, carbonate, nitrate or hydroxide containing element A;

[0024] The compound containing element M is selected from one or more of the oxide, carbonate, nitrate or hydroxide containing element M;

[0025] The chromium-containing compound is selected from one or more of chromium oxide, chromium nitrate, ammonium chromate or chromium halide.

[0026] In some specific implementation manners, in step 2), the sintering temperature is 1000 °C to 1400 °C;

[0027] The sintering time is 2 h to 10 h;

[0028] The heating rate of the sintering is 2 °C / min to 8 °C / min.

[0029] Furthermore, the present application also provides a far-red light plant supplementary lighting luminescent material, including the above inorganic luminescent material.

[0030] In some specific implementation manners, the mass percentage of the inorganic luminescent material is 20 wt% to 100 wt%.

[0031] In some specific implementation manners, the far-red light plant supplementary lighting luminescent material further includes: alumina.

[0032] The inorganic luminescent material provided by the present application, the general formula of this luminescent material is Zn x Mg 1-x AM 10 O 17 :yCr 3+ ; wherein, 0 ≤ x ≤ 1, 0 < y ≤ 0.06; A is selected from one or more of the elements Ca, Sr or Ba; M is selected from one or more of the elements Al, Ga, Sc or Y; Cr in the present application 3+As a luminescent activator ion, by regulating the matrix elements Zn, Mg, A, and M, it emits mainly high-efficiency far-red light with a peak wavelength of approximately 680nm~780nm. The luminescent material of this application has high light conversion efficiency, good thermal and chemical stability, and can be used for supplemental lighting of plants. The far-red light emitted by it can optimize the morphological structure of plants through light signal regulation, while improving light energy utilization efficiency, making it suitable for supplemental lighting cultivation of high-value crops. Attached Figure Description

[0033] Figure 1 The X-ray diffraction pattern (XRD) and standard card pattern of the inorganic luminescent material provided in Example 1 are shown.

[0034] Figure 2 This is the excitation spectrum of the inorganic luminescent material provided in Example 1 at a monitoring wavelength of 700 nm;

[0035] Figure 3 This is the emission spectrum of the inorganic luminescent material provided in Example 1 under 395 nm blue light excitation;

[0036] Figure 4 This is the emission spectrum of the inorganic luminescent material provided in Example 2 at 25°C~150°C;

[0037] Figure 5 This is a comparison diagram of the emission spectrum of the inorganic luminescent material provided in Example 3 and its absorption spectrum with that of plant pigments;

[0038] Figure 6 This is the emission spectrum of the inorganic luminescent material provided in Comparative Example 1. Detailed Implementation

[0039] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0040] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0041] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0042] This application provides an inorganic luminescent material as shown in formula (I):

[0043] Zn x Mg 1-x AM 10 O 17 :yCr 3+ Formula (I);

[0044] Where 0≤x≤1, 0 <y≤0.06;

[0045] A is selected from one or more of the elements Ca, Sr, or Ba;

[0046] M is selected from one or more of the elements Al, Ga, Sc, or Y.

[0047] For the atomic ratio of elements in formula (I), it is preferred that 0.01 < y ≤ 0.06, and more preferably x = 0, x = 0.5 or x = 1, y = 0.02, y = 0.04 or y = 0.06.

[0048] In formula (I) of this application, A is selected from one or more of elements Ca, Sr or Ba, preferably one or two of elements Ba and Sr; M is selected from one or more of elements Al, Ga, Sc and Y, preferably one or two of elements Al or Ga.

[0049] In the embodiments of this application, the inorganic luminescent material has the structures of formulas (I-1) to (I-6):

[0050] ZnBaAl 10 O 17 0.02Cr 3+ Formula (I-1); ZnBaAl8Ga2O 17 0.02Cr 3+ Formula (I-2);

[0051] ZnBaAl5Ga5O 17 0.04Cr 3+ Formula (I-3); MgBaAl8Ga2O 17 0.02Cr 3+ Formula (I-4);

[0052] Zn 0.5 Mg 0.5 BaAl 10 O 17 0.06Cr 3+ Equation (I-5); ZnBa 0.8 Sr 0.2 Al 10 O 17 0.04Cr 3+ Formula (I-6).

[0053] The inorganic luminescent material described in this application is mainly characterized by efficient and stable broadband far-red light emission that matches the physiological needs of plants. Specifically, the inorganic luminescent material has a wide absorption range in the ultraviolet to green light band and emits far-red light in the range of 680nm to 780nm, with an emission peak of about 700nm.

[0054] Furthermore, this application also provides a method for preparing the above-mentioned inorganic luminescent material, comprising the following steps:

[0055] 1) Mix Zn-containing compounds, Mg-containing compounds, A-containing compounds, M-containing compounds and chromium-containing compounds uniformly according to the molar ratio of each element in the material shown in formula (I) to obtain a precursor;

[0056] 2) The precursor obtained in step 1) is sintered to obtain an inorganic luminescent material.

[0057] This application first mixes a Zn-containing compound, a Mg-containing compound, an A-containing compound, a M-containing compound, and a chromium-containing compound evenly to obtain a precursor. This application does not have specific restrictions on the mixing method of the above raw materials. Grinding can be done by mortar and pestle or by mixing machine, with grinding by mortar and pestle being preferred.

[0058] In some specific implementations, the zinc-containing compound is selected from one or more of zinc oxide, zinc carbonate, zinc nitrate, zinc acetate, or zinc hydroxide, preferably zinc oxide; the magnesium-containing compound is selected from one or more of magnesium oxide, magnesium carbonate, magnesium nitrate, magnesium acetate, or magnesium hydroxide, preferably magnesium oxide; the compound containing element A is selected from one or more of oxides, carbonates, nitrates, or hydroxides containing element A, preferably one or two of barium carbonate and strontium carbonate; the compound containing element M is selected from one or more of oxides, carbonates, nitrates, or hydroxides containing element M, preferably one or two of aluminum oxide and gallium oxide; the chromium-containing compound is selected from one or more of chromium oxide, chromium nitrate, ammonium chromate, or chromium halides, preferably chromium oxide, more preferably chromium trioxide. This application does not specifically limit the source of the above raw materials; commercially available products with analytical grade (AR) purity can be used.

[0059] In this application, the molar ratio of the zinc-containing compound, Mg-containing compound, A-containing compound, M-containing compound, and chromium-containing compound may be, in some specific implementations, as follows:

[0060] 1:0:1:10:0.02, 0:1:1:10:0.02, 0.5:0.5:1:10:0.06 and 1:0:1:10:0.04.

[0061] This application sinters a precursor to obtain an inorganic light-emitting material. In a typical implementation, the specific steps include: placing the precursor in a crucible, sintering it under an atmosphere, and grinding it evenly to room temperature after cooling to obtain the inorganic light-emitting material.

[0062] In some specific implementations, the sintering atmosphere can be air, nitrogen or argon; the sintering temperature is 1000 °C to 1400 °C, preferably 1200 °C to 1350 °C, more preferably 1280 °C, 1300 °C, 1320 °C or 1350 °C; the sintering time is 2 h to 10 h, preferably 4 h to 8 h, more preferably 6 h or 8 h; the heating rate of the sintering is 2 °C / min to 8 °C / min, preferably 3 °C / min to 7 °C / min, more preferably 5 °C / min.

[0063] Furthermore, this application also provides a far-red light plant supplementary lighting luminescent material, including the above-mentioned inorganic light-emitting material.

[0064] In some specific implementations, the mass percentage of the inorganic light-emitting material is 20 wt% to 100 wt%. In some specific implementations, the far-red light plant supplementary lighting luminescent material further includes: alumina.

[0065] The inorganic light-emitting material provided by this application has a general formula of Zn x Mg 1-x AM 10 O 17 :yCr 3+ ; where 0 ≤ x ≤ 1, 0 < y ≤ 0.06; A is selected from one or more of the elements Ca, Sr or Ba; M is selected from one or more of the elements Al, Ga, Sc or Y; in this application, Cr 3+ is a luminescence activation ion, and by regulating the matrix Zn, Mg, A, M elements, it emits mainly high-efficiency far-red light with a peak of about 680 nm to 780 nm; the luminescent material of this application has high light conversion efficiency, good thermal stability and chemical stability, can be used for plant supplementary lighting, and the far-red light emitted by it can optimize the plant morphological structure through light signal regulation, while improving the light energy utilization efficiency, and is suitable for the supplementary lighting cultivation of high-value crops.

[0066] Experimental results show that the inorganic light-emitting material provided by this application can exhibit a strong emission with a peak of about 700 nm in the far-red light region and is suitable for the supplementary lighting cultivation of plants.

[0067] The following further elaborates this application in combination with examples. The protection scope of this application is not limited by the following examples.

[0068] Example 1

[0069] Zinc oxide (AR), barium carbonate (AR), aluminum oxide (AR), and chromium trioxide (AR) were weighed out as raw materials in a molar ratio of 1:1:10:0.02. The weighed raw materials were placed in an agate mortar and thoroughly ground until homogeneous. The homogeneous powder was then transferred to an alumina crucible and placed in a muffle furnace. The furnace was heated to 1350℃ at a heating rate of 5℃ / min under air atmosphere and sintered at this temperature for 8 hours. After sintering, the sample was allowed to cool naturally to room temperature in the furnace, removed, and ground again to obtain a light red inorganic powder, which is the inorganic luminescent material ZnBaAl. 10 O 17 0.02Cr 3+ .

[0070] like Figure 1 As shown, X-ray powder diffraction analysis was performed on the material obtained in Example 1 and compared with the standard card (ICSD-155525). The results showed that the synthesized sample was a pure phase and no obvious impurity phase peaks were observed. Figure 2 The excitation spectrum of the sample is shown, which shows that it has a broad and strong absorption in the ultraviolet to visible light band of 300nm~650nm. Figure 3 The emission spectrum of the sample was measured under 395nm blue light excitation. It shows a strong emission peak centered at 700nm in the far-red region and a wide emission band, indicating that the material can effectively convert ultraviolet-visible light into far-red light that is beneficial to plant growth.

[0071] Example 2

[0072] Zinc oxide (AR), barium carbonate (AR), aluminum oxide (AR), gallium oxide (AR), and chromium trioxide (AR) were weighed out as raw materials in a molar ratio of 1:1:8:2:0.02. The weighed raw materials were placed in an agate mortar and thoroughly ground and mixed. The mixed powder was then transferred to an alumina crucible and placed in a muffle furnace. The furnace was heated to 1300℃ at a heating rate of 5℃ / min under air atmosphere and sintered at this temperature for 6 hours. After sintering, the sample was allowed to cool naturally to room temperature in the furnace, removed, and ground again to obtain a light pink inorganic powder, which is the inorganic luminescent material ZnBaAl8Ga2O. 17 0.02Cr 3+ .

[0073] X-ray diffraction analysis was performed on the material obtained in Example 2, and the sample was found to be pure phase ZnBaAl8Ga2O. 17 The structure shows no obvious impurity peaks. Figure 4 ZnBaAl8Ga2O was demonstrated 17 0.02Cr 3+The material exhibits emission spectra at different temperatures, maintaining significant luminescence intensity in the far-red region of approximately 650 nm to 850 nm, demonstrating good thermal stability and suitability for high-temperature light conversion applications.

[0074] Example 3

[0075] Zinc oxide (AR), barium carbonate (AR), aluminum oxide (AR), gallium oxide (AR), and chromium trioxide (AR) were weighed out as raw materials in a molar ratio of 1:1:5:5:0.04. The weighed raw materials were placed in an agate mortar and ground until uniformly mixed. The resulting powder was placed in an alumina crucible and sintered in a muffle furnace at 1320℃ for 6 hours at a rate of 5℃ / min to obtain the inorganic luminescent material ZnBaAl5Ga5O. 17 0.04Cr 3+ .

[0076] X-ray diffraction analysis of the material in Example 3 showed that it was a pure phase structure. The excitation spectrum exhibited broad absorption in the ultraviolet-visible region of 300 nm to 600 nm. Under 410 nm excitation, the emission spectrum showed a strong emission band centered at 720 nm in the far-red region. Figure 5 The comparison between the emission spectrum of the material and the absorption spectrum of plant pigments is shown. The two have significant overlap in the far-red light band, indicating that the material can efficiently convert the blue-violet and green light bands in the solar spectrum into far-red light radiation that can be used by plant photosynthesis, which helps to improve the efficiency of light energy utilization.

[0077] Example 4

[0078] Magnesium oxide (AR), barium carbonate (AR), aluminum oxide (AR), gallium oxide (AR), and chromium trioxide (AR) were weighed out as raw materials in a molar ratio of 1:1:8:2:0.04. The weighed raw materials were placed in an agate mortar and ground until uniformly mixed. The resulting powder was placed in an alumina crucible and sintered in a muffle furnace at 1280℃ for 6 hours at a rate of 5℃ / min to obtain the inorganic luminescent material MgBaAl8Ga2O. 17 0.02Cr 3+ .

[0079] The XRD results of the material obtained in Example 4 are similar to those of the above samples, and its absorption and emission spectrum ranges are the same as those in Example 3.

[0080] Example 5

[0081] Zinc oxide (AR), magnesium oxide (AR), barium carbonate (AR), aluminum oxide (AR), and chromium trioxide (AR) were weighed out as raw materials, with a molar ratio of 0.5:0.5:1:10:0.06. The weighed raw materials were then placed in an agate mortar and ground until uniformly mixed. The resulting sample powder was placed in an alumina crucible and sintered in a muffle furnace at 1300℃ for 6 hours at a rate of 5℃ / min to obtain the inorganic near-infrared fluorescent material Zn. 0.5 Mg 0.5 BaAl 10 O 17 0.06Cr 3+ The XRD results and fluorescence spectral properties of the material obtained in this embodiment are similar to those of the aforementioned aluminate system.

[0082] Example 6

[0083] Zinc oxide (AR), barium carbonate (AR), strontium carbonate (AR), aluminum oxide (AR), and chromium trioxide (AR) were weighed out as raw materials in a molar ratio of 1:0.8:0.2:10:0.04. The weighed raw materials were then placed in an agate mortar and ground until uniformly mixed. The resulting powder was placed in an alumina crucible and sintered in a muffle furnace at 1280℃ for 6 hours at a rate of 5℃ / min to obtain the inorganic near-infrared fluorescent material ZnBa. 0.8 Sr 0.2 Al 10 O 17 0.04Cr 3+ The XRD results and fluorescence spectral properties of the material obtained in this embodiment are similar to those of the aforementioned aluminate system.

[0084] Comparative Example 1

[0085] The difference between this comparative example and Example 1 is that Cr 3+ The molar amount of the substance is 0.18 mol, and the other raw materials and preparation methods are exactly the same.

[0086] Figure 6 This is the emission spectrum of the inorganic luminescent material prepared in this comparative example. When Cr... 3+ When the doping amount reaches 0.18 mol, the luminescence intensity gradually decreases to 30% of the original value, and the spectrum changes, making it unsuitable for supplemental lighting of plants.

[0087] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and application concept of this application, should be included within the scope of protection of this application.

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