A self-activated deep red near-infrared fluorescent powder and a preparation method and application thereof

Abstract

The application discloses a self-activation type deep red near-infrared fluorescent powder and a preparation method and application thereof; the chemical general formula is LiZnNbO4:xA, wherein 0<=x<=0.1, and A is one of Na, Pr, Tm, Sm, Dy, Tb, Er and Ho elements; the deep red-near-infrared fluorescent powder is prepared by taking raw materials according to the stoichiometric ratio of the chemical general formula LiZnNbO4:xA, grinding and uniformly mixing, heating in a corundum crucible, and obtaining a product, and then crushing, grinding, grading, screening and washing the product to obtain the deep red-near-infrared fluorescent powder. The application provides the deep red-near-infrared fluorescent powder which has the advantages of simple preparation method, easy operation, low cost, high environmental protection, stable chemical performance, good luminous efficiency and high ultraviolet excitation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of luminescent materials, in particular to a self-activated deep red near-infrared fluorescent powder and a preparation method and application thereof. BACKGROUND

[0002] Luminescent materials are essential materials in modern technology, and play a key role in display lighting, safety identification, optical anti-counterfeiting, optical sensors, waveguides and optoelectronic devices. Most inorganic luminescent materials achieve luminescence through various activated ions, such as rare earth ions and transition metal ions. The rich energy level transitions of rare earth ions and the crystal field theory of transition metal ions allow the emission of photons from ultraviolet to visible light to infrared band, which provides significant advantages in lighting and anti-counterfeiting applications. In particular, the compatibility of deep red-near infrared light with biological tissues has become increasingly important in daily life. It not only promotes the circulation and metabolism of the human body, improves overall function, but also significantly promotes the growth and development of plants. Under the influence of modern climate change and the increasing emphasis on energy saving and emission reduction, global agricultural production is moving towards a more intensive and standardized path. Therefore, indoor plant cultivation (IPC) has become an important part of facility agriculture. However, traditional IPC methods are plagued by problems such as spectral mismatch, excessive energy consumption and environmental pollution. In order to effectively solve the above problems, fluorescent conversion light-emitting diodes (pc-leds) gradually come into the public eye due to their adjustable spectrum, energy-saving characteristics and environmental benefits of indoor plant cultivation lighting. Generally speaking, blue light (400-500 nm), red light (600-700 nm) and far-red light (700-780 nm) are essential energy sources for most plant cultivation. These lights are converted by plant pigments such as chlorophyll A, chlorophyll B and photogreen pigment b into chemical energy required for plant growth. Therefore, as a key component of pc-leds for plant lighting, fluorescent powder must meet the strict requirements of its spectral composition and luminescent properties. Previous studies often use Mn 4+ activated fluorides or oxides to prepare plant lighting pc-leds, as their wide absorption band and far-red light emission (620-800 nm) match well with the light required for plant growth. For example: K2TiF6:Mn 4+ , K2SiF6:Mn 4+ , Cs2SiF6:Mn 4+ , and various oxides such as Ba2MgGe2O7:Mn 4+ , Ba2GdNbO6:Mn 4+ , Li2MgTiO4:Mn 4+ , SrLaScO4:Mn 4+ , Ca2YSbO6:Mn 4+Li2SnO3:Mn 4+ Li2SnO3:Mn 4+ However, due to the sensitivity of the 3d 4+ electronic configuration of Mn 3 to the crystal field environment required to achieve the desired emission wavelength range, the selection and design of the material are limited. In addition, Mn 4+ also has biological toxicity and can pollute the environment, resulting in that these Mn 4+ activated fluorescent powders are not suitable for some fields with high safety.

[0003] Self-activated inorganic luminescent materials can achieve photoluminescence without the need for doping activating ions, and the luminescence behavior is usually related to their own properties. Since it is not necessary to dope any rare earth ions or transition metal ions, it has the advantages of simplicity and low cost in preparation process and economic cost. Recently, our team invented a new type of inorganic self-activated luminescent material LiZnNbO4, which can exhibit broadband deep red-near infrared photon emission centered at 711 nm under the excitation of near ultraviolet light without the need for doping any activating ions. In addition, in order to further improve the luminescence intensity, we also doped non-activating ions and a series of rare earth ions without activating agent to significantly improve the luminescence intensity of the material. Notably, the deep red-near infrared emission of the series of fluorescent powders synthesized by us is consistent with the absorption range of the photosensitive pigment (Pr and Pfr) of plants, which makes the fluorescent powders prepared by us have great potential in plant growth lighting. SUMMARY

[0004] The first object of the present application is to provide a self-activated deep red-near infrared fluorescent powder which can be efficiently excited by ultraviolet light, has a simple preparation method, is easy to operate, has low cost, is environmentally friendly, has stable chemical properties, and has good luminescent efficiency.

[0005] In order to achieve the above technical effects, the present application is realized by the following technical scheme: a self-activated deep red-near infrared fluorescent powder, characterized in that: its chemical general formula is LiZnNbO4:xA, wherein 0≤x≤0.1, and A is one of Na, Pr, Tm, Sm, Dy, Tb, Er, and Ho elements.

[0006] Further, the excitation wavelength range of the deep red-near infrared fluorescent powder is 230-375 nm; and the wavelength range of the emission spectrum of the deep red-near infrared fluorescent powder is 650-900 nm.

[0007] The second object of the present application is to provide a preparation method of a self-activated deep red-near infrared fluorescent powder, characterized in that it comprises the following steps:

[0008] S1, the stoichiometric ratio of the chemical formula LiZnNbO4:xA is taken according to the corresponding chemical raw materials, the weighed raw materials are placed in the agate mortar, then alcohol is added until the powder raw materials are submerged, after being fully mixed and ground, a pre-sintered raw material mixture is obtained;

[0009] S2, the collected pre-sintered raw material mixture is transferred to an Al2O3 corundum crucible, and then placed in a muffle furnace and heated to 1000-1300 DEG C at a heating rate of 3-10 DEG C / min for 2-6h; when the reaction is completed, and the muffle furnace temperature is naturally cooled to room temperature, a calcined product is obtained;

[0010] S3, the obtained calcined product is crushed, ground, graded, and screened to obtain the required deep red-near infrared fluorescent powder.

[0011] Further, in S1, the raw materials are one or more of lithium, zinc, and niobium carbonates or oxides.

[0012] Further, in S2, the calcination temperature in the muffle furnace is specifically 1100 DEG C, and the calcination time is specifically 4h.

[0013] The third object of the application is to provide an application of a self-activated deep red-near infrared fluorescent powder, characterized in that the deep red-near infrared fluorescent powder is applied in plant lighting.

[0014] Further, the application of the deep red-near infrared fluorescent powder in plant lighting is specifically to prepare an ultraviolet LED chip containing the deep red-near infrared fluorescent powder and having a light emitting wavelength of 300-400nm.

[0015] Further, the LED chip is an InGaN or GaN semiconductor chip.

[0016] The beneficial effects of the application are:

[0017] 1, the deep red-near infrared fluorescent powder (LiZnNbO4:xA) in the application can be efficiently excited by ultraviolet light, and converted into near-infrared light in the range of 650-900nm, and can realize efficient broadband deep red-near infrared emission under 330nm ultraviolet light excitation, and the emission intensity can be adjusted, a series of deep red-near infrared fluorescent powder materials are prepared by doping different ions, the luminous intensity of the fluorescent powder is significantly improved, the luminous behavior of the fluorescent powder is effectively optimized, and the application potential is further improved.

[0018] 2, The material obtained by the application can be used to prepare a self-activated deep red-near infrared light source, and the fluorescent powder can realize deep red-near infrared light without doping any activated luminescent ions, which expands the types and research of fluorescent powder conversion type near infrared LED; and avoids the drawbacks of expensive and narrow spectral range of commonly used activators rare earth ions, and becomes a new way to efficiently produce deep red-near infrared light.

[0019] 3, The high-temperature solid-phase method is adopted in the application, the preparation method is simple, green, pollution-free and low in cost, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed for the description of the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 The XRD of the deep red-near infrared fluorescent material prepared in Example 1 of the application is compared with the standard card;

[0022] Figure 2 The excitation and emission spectrum of the fluorescent powder sample prepared in Example 1 of the application is shown, the left curve detection wavelength is 711nm, and the right curve excitation wavelength is 330nm;

[0023] Figure 3 The emission spectrum of the fluorescent powder sample prepared in Example 2 of the application under different Na + doping concentrations;

[0024] Figure 4 The fluorescence spectrum of the deep red-near infrared fluorescent material prepared in Example 1 and Examples 3-9 of the application under 330nm excitation. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0026] Example 1

[0027] The deep red-near infrared fluorescent powder described in this embodiment comprises a compound with a composition formula of LiZnNbO4.

[0028] According to the stoichiometric ratio of the chemical formula LiZnNbO4, Li2CO3, ZnO and Nb2O5 are accurately weighed and mixed to obtain a mixture; the mixture is ground and uniformly mixed, and then calcined at 1100°C for 4h, and after cooling, a calcined product is obtained; after processing such as crushing, grinding, grading, washing and screening, a deep red-near infrared fluorescent powder sample is obtained.

[0029] The obtained deep red-near infrared fluorescent powder sample is subjected to excitation test, and the results show that the emission peak position of the near infrared fluorescent powder is at 711nm under 330nm excitation.

[0030] Example 2

[0031] The deep red-near infrared fluorescent powder described in this example contains a compound with a composition formula of LiZnNbO4:xNa + , wherein x=0, 0.02, 0.04, 0.06, 0.08 and 0.10.

[0032] The preparation method of the deep red-near infrared fluorescent powder described in this example is the same as that of Example 1, and the only difference is that according to the stoichiometric ratio of the chemical formula LiZnNbO4:xNa + , Li2CO3, ZnO, Nb2O5 and Na2CO3 raw materials are weighed and mixed, and the obtained product after calcination is subjected to processing such as crushing, grinding, grading, washing and screening, and a deep red-near infrared fluorescent powder sample is obtained.

[0033] Example 3

[0034] The deep red-near infrared fluorescent powder described in this example contains a compound with a composition formula of LiZnNbO4:0.005Pr 3+ .

[0035] The preparation method of the deep red-near infrared fluorescent powder described in this example is the same as that of Example 1, and the only difference is that according to the stoichiometric ratio of the chemical formula LiZnNbO4:0.005Pr 3+ , Li2CO3, ZnO, Nb2O5 and Pr2O3 raw materials are weighed and mixed.

[0036] Example 4

[0037] The deep red-near infrared fluorescent powder described in this example contains a compound with a composition formula of LiZnNbO4:0.005Tm 3+ .

[0038] The preparation method of the deep red-near infrared fluorescent powder described in this example is the same as that of Example 1, and the only difference is that according to the stoichiometric ratio of the chemical formula LiZnNbO4:0.005Tm 3+Li2CO3, ZnO, Nb2O5 and Tm2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4: 0.005Sm.

[0039] Example 5

[0040] The deep red-near infrared fluorescent powder described in this embodiment contains a compound with a composition formula of LiZnNbO4: 0.005Sm 3+ .

[0041] The preparation method of the deep red-near infrared fluorescent powder described in this embodiment is the same as that of Example 1, and the only difference is that Li2CO3, ZnO, Nb2O5 and Sm2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4: 0.005Sm 3+ .

[0042] Example 6

[0043] The deep red-near infrared fluorescent powder described in this embodiment contains a compound with a composition formula of LiZnNbO4: 0.005Dy 3+ .

[0044] The preparation method of the deep red-near infrared fluorescent powder described in this embodiment is the same as that of Example 1, and the only difference is that Li2CO3, ZnO, Nb2O5 and Dy2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4: 0.005Dy 3+ .

[0045] Example 7

[0046] The deep red-near infrared fluorescent powder described in this embodiment contains a compound with a composition formula of LiZnNbO4: 0.005Tb 3+ .

[0047] The preparation method of the deep red-near infrared fluorescent powder described in this embodiment is the same as that of Example 1, and the only difference is that Li2CO3, ZnO, Nb2O5 and Tb2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4: 0.005Tb 3+ .

[0048] Example 8

[0049] The deep red-near infrared fluorescent powder described in this embodiment contains a compound with a composition formula of LiZnNbO4: 0.005Er 3+ .

[0050] The preparation method of the deep red-near infrared fluorescent powder described in this embodiment is the same as that of Example 1, and the only difference is that Li2CO3, ZnO, Nb2O5 and Tb2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4: 0.005Tb 3+Li2CO3, ZnO, Nb2O5 and Er2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4:0.005Er.

[0051] Example 9

[0052] The deep red-near infrared fluorescent powder described in this example contains a compound with a composition formula of LiZnNbO4:0.005Ho 3+ .

[0053] The preparation method of the deep red-near infrared fluorescent powder described in this example is the same as that of Example 1, and the only difference is that Li2CO3, ZnO, Nb2O5 and Ho2O3 raw materials are weighed according to the stoichiometric ratio of the chemical formula LiZnNbO4:0.005Ho 3+ .

[0054] The deep red-near infrared fluorescent powder sample obtained in Example 1 is tested, and the photoluminescence spectrum is shown in the attached Figure 1 figure. The results show that the deep red-near infrared fluorescent powder sample can be effectively excited in the range of 230-375 nm, and the emission spectrum is wide-band emission, covering the emission range of 650-900 nm, and the emission peak position is at 711 nm. Figure 2 The deep red-near infrared fluorescent powder sample obtained in Example 2 is also tested for photoluminescence spectrum, as shown in the attached

[0055] figure. The emission characteristics of all materials are the same as those of Example 1, but the luminescence of all LiZnNbO4:xNa + samples is stronger than that of the LiZnNbO4 sample in Example 1, among which the near-infrared luminescence of the LiZnNbO4:0.04Na + sample at 711 nm is enhanced by about 5.7 times. Figure 3 The photoluminescence spectrum test of the deep red-near infrared fluorescent powder samples obtained in Examples 3-9 is shown in the attached

[0056] figure. The emission characteristics of all materials are the same as those of Example 1, but the luminescence of all samples in Examples 3-9 is also stronger than that of the LiZnNbO4 sample in Example 1, among which the near-infrared luminescence of the LiZnNbO4:0.04Na + sample at 711 nm is enhanced by about 41.5 times. Figure 4

[0057] ​Since red (600-700 nm) and far-red (700-780 nm) light is essential energy for most plant cultivation. These lights are converted to chemical energy by plants through chlorophyll A, chlorophyll B, phaeophytin b and other plant pigments, which are required for their growth. All the phosphors prepared in our examples can be combined with UV LED chips to produce 650 nm-900 nm far-red-near-infrared broadband light, which just overlaps the absorption spectrum required for plant photomorphogenesis. Therefore, the self-activated luminescence method proposed in this study is a new way to develop new far-red-near-infrared phosphors, which has great prospects for the development of pc-LEDs for plant lighting and opens up a new window for the preparation of far-red-near-infrared phosphors.

Claims

1. A self-activated deep red near-infrared fluorescent powder, characterized in that: The chemical general formula is LiZnNbO4:xA, wherein 0 2.The self-activated deep red near-infrared fluorescent powder according to claim 1, characterized in that: The excitation wavelength range of the deep red near-infrared fluorescent powder is 230-375 nm; the wavelength range of the emission spectrum of the deep red near-infrared fluorescent powder is 650-900 nm.

3. The preparation method of the self-activated deep red near-infrared fluorescent powder according to claim 1, characterized in that, The method comprises the following steps: S1, the corresponding chemical raw materials are weighed according to the stoichiometric ratio of the chemical general formula LiZnNbO4:xA, the weighed raw materials are placed in an agate mortar, then alcohol is added until the powder raw materials are submerged, and after being fully mixed and ground, a pre-sintering raw material mixture is obtained; S2, the collected pre-sintering raw material mixture is transferred to an Al2O3 corundum crucible, and then placed in a muffle furnace and heated to 1000-1300 ℃ at a heating rate of 3-10 ℃ / min for calcination for 2-6 h; when the reaction is completed and the temperature of the muffle furnace is naturally cooled to room temperature, a calcined product is obtained; S3, the obtained calcined product is crushed, ground, classified, and screened to obtain the self-activated deep red near-infrared fluorescent powder.

4. The preparation method of the self-activated deep red near-infrared fluorescent powder according to claim 3, characterized in that: In S2, the calcination temperature in the muffle furnace is specifically 1100 ℃, and the calcination time is specifically 4 h.

5. Application of the self-activated deep red near-infrared fluorescent powder according to claim 1 in plant lighting.

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