Light converting material, method for its preparation and use thereof

Abstract

The application discloses a light conversion material and a preparation method and application thereof. The light conversion material has a composition shown in formula (1): Li a Sr b M c Gd d RE e Nb f A g O h :mMn 4+ (1); wherein M is selected from one or more of Ca and Ba, RE is selected from one or more of La and Y, and A is selected from one or more of Ta, V and P; 0.001<=a<=0.009, 0.3<=b<=2.2, 0<=c<=1.8, 0.3<=d<=0.8, 0.1<=e<=0.6, 0.3<=f<=1.2, 0<=g<=0.6, 4<=h<=8, 0.001<=m<=0.007. The light conversion material can convert ultraviolet light and green light into red light.

Description

Technical Field

[0001] This invention relates to a light conversion material, its preparation method, and its uses. Background Technology

[0002] Plant growth requires sunlight, and different wavelengths of light have a significant impact on plant growth. Blue-violet light (wavelength range 400–480 nm) can be absorbed by chlorophyll and carotenoids, promoting stem and leaf growth. Red-orange light (wavelength range 600–700 nm) can be absorbed by chlorophyll, promoting fruit growth. Yellow-green light (wavelength range 500–600 nm) contributes almost nothing to plant photosynthesis. Near-ultraviolet light (wavelength range 315–400 nm), except for wavelengths around 360 nm which are beneficial for fruit coloring, can cause plants to become shorter and leaves to thicken. Ultraviolet light (wavelength range 290–315 nm) is harmful to most plants and can accelerate the aging and deterioration of agricultural films. Therefore, the key is to convert the green and ultraviolet light in sunlight, which are neither beneficial nor harmful to plant growth, into blue-violet and red-orange light, which are beneficial for photosynthesis.

[0003] CN118516115A discloses a red light conversion agent with the chemical formula Ln2MN. (1-x) O6:xMn 4+ Wherein, 0.1% ≤ x ≤ 1.0%, Ln is at least one of La and Gd, M is at least one of Li and Mg, and N is at least one of Nb, Sb, and Al. This red light conversion agent exhibits poor hygrothermal stability and UV aging resistance, and its strongest emission peak wavelength is 715 nm, which is closer to the infrared spectrum and has a low matching degree with the absorption band of chlorophyll a.

[0004] CN105001860A discloses a red phosphor with the following general chemical formula: A a M b R c D d E e B f Al4O x :Mn 4 + yWherein, A is at least one monovalent element from Li, Na, K, Rb, and CS; M is at least one divalent element from Ca, Sr, Ba, Mg, Zn, Cd, Ni, and Pb; R is at least one trivalent element from Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Bi; D is at least one from Sc, Ca, In, P, V, Nb, Ta, Si, Ge, Sn, Sb, Zr, Hf, Ti, and Cr; E is at least one from F, Cl, Br, and N; B is boron; Al is aluminum; O is oxygen; and Mn is oxygen. 4+ It is tetravalent manganese. This red phosphor can convert near-ultraviolet and blue light into red light.

[0005] CN118667540A discloses a near-infrared phosphor, comprising (A... a D d M m R r Q q E e G g Inorganic compounds, wherein the inorganic compounds have a similarity to Ca3Ga2Ge3O 12 It exhibits the same cubic garnet structure; wherein element A includes one or two of Ca, Sr, Ba, Bi, La, and Ga; element D includes one or two of Al, Ga, In, and Sc; element M includes one or two of Li, Mg, and Zn; element R includes one or two of Zr, Hf, Sn, Ti, Ta, and Nb; element E is selected from one or two of Si and Ge; element G is selected from one or two of O, N, and F; and element Q is selected from one or two of Mn, Eu, Cr, and Ni. This phosphor can absorb light in the 400–550 nm and 600–800 nm wavelength ranges and emit near-infrared light in the 1470–1602 nm wavelength range. Summary of the Invention

[0006] In view of this, one object of the present invention is to provide a light conversion material capable of converting ultraviolet and green light into red light. Furthermore, the light conversion material exhibits excellent hydrothermal stability and resistance to ultraviolet aging. Furthermore, the light conversion material possesses high luminous intensity. Another object of the present invention is to provide a method for preparing the light conversion material. A further object of the present invention is to provide uses for the above-described light conversion material.

[0007] The present invention achieves the above objectives through the following technical solutions.

[0008] On the one hand, the present invention provides a light conversion material having the composition shown in formula (1):

[0009] Li aSr b M c Gd d RE e Nb f A g O h :mMn 4+ (1);

[0010] Wherein, M is selected from one or more of Ca and Ba, RE is selected from one or more of La and Y, and A is selected from one or more of Ta, V, and P; 0.001≤a≤0.009, 0.3≤b≤2.2, 0≤c≤1.8, 0.3≤d≤0.8, 0.1≤e≤0.6, 0.3≤f≤1.2, 0≤g≤0.6, 4≤h≤8, and 0.001≤m≤0.007;

[0011] Where a, b, c, d, e, f, g, h and m represent the molar number or atomic number of each element.

[0012] According to the light conversion material of the present invention, preferably, 0.5≤c≤1.5, b+c=2.

[0013] According to the light conversion material of the present invention, preferably, 0.1≤g≤0.5, f+g=0.996, d+e=1.

[0014] According to the light conversion material of the present invention, preferably, 0.003≤a≤0.007, 0.4≤d≤0.7, 0.2≤e≤0.5, 5≤h≤7, and 0.003≤m≤0.006.

[0015] In the light conversion material according to the present invention, preferably, M is Ca, RE is La, and A is P.

[0016] According to the light conversion material of the present invention, preferably, the light conversion material has one of the following chemical compositions:

[0017] Li 0.004 Sr2Gd 0.6 La 0.4 Nb 0.996 O6:0.004Mn 4+ ;

[0018] Li 0.004 Sr 0.8 Ca 1.2 Gd 0.6 La 0.4 Nb 0.996 O6:0.004Mn 4+ ;

[0019] Li 0.004 Sr0.8 Ca 1.2 Gd 0.6 La 0.4 Nb 0.5976 P 0.3984 O6:0.004Mn 4+ .

[0020] According to the light conversion material of the present invention, preferably, the light conversion material has an Sr2GdNbO6 crystal structure.

[0021] On the other hand, the present invention provides a method for preparing the above-mentioned light conversion material, comprising the following steps:

[0022] The raw materials obtained according to the composition of the light conversion material are calcined at 1200-1500℃ to obtain the light conversion material.

[0023] According to the preparation method of the present invention, preferably, no co-solvent is used in the preparation process.

[0024] In another aspect, the present invention provides the use of the above-mentioned light conversion material in converting ultraviolet light in the 300-380nm band and / or green light in the 480-550nm band into red light in the 650-750nm band.

[0025] The light conversion material of this invention can convert ultraviolet and green light into red light, and exhibits excellent hydrothermal stability and resistance to ultraviolet aging. Furthermore, the light conversion material of this invention possesses high luminous intensity. This invention discovers that avoiding the use of co-solvents such as boric acid during the preparation process helps to improve the luminous intensity, hydrothermal stability, and resistance to ultraviolet aging of the light conversion material. Attached Figure Description

[0026] Figure 1 The images show the XRD patterns of the light conversion materials of Example 4 and Comparative Example 1.

[0027] Figure 2 The emission spectra of the light conversion materials of the examples and comparative examples under ultraviolet light excitation at their corresponding strongest excitation wavelength are shown.

[0028] Figure 3 The excitation spectra of the light conversion materials of the examples and comparative examples under the monitoring of their corresponding emission peak wavelengths are shown.

[0029] Figure 4 This is a graph showing the trend of the emission peak intensity of the light conversion material in Example 4 as a function of the number of days of wet heat treatment.

[0030] Figure 5 This is a graph showing the trend of the emission peak intensity of the light conversion material in Example 4 as a function of the number of days of QUV aging treatment. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] <Light Conversion Materials>

[0033] The light conversion material of the present invention has the composition shown in formula (1):

[0034] Li a Sr b M c Gd d RE e Nb f A g O h :mMn 4+ (1).

[0035] Li represents lithium. a represents the molar or atomic number of Li. 0.001≤a≤0.009; preferably, 0.003≤a≤0.007; more preferably, 0.004≤a≤0.005.

[0036] Sr represents strontium. b represents the molar or atomic number of Sr. 0.3 ≤ b ≤ 2.2. In some embodiments, 1.8 ≤ b ≤ 2. In other embodiments, 0.8 ≤ b ≤ 1.

[0037] M is selected from one or more of Ca and Ba. Preferably, M is Ca. c represents the molar or atomic number of M. 0 ≤ c ≤ 1.8; preferably, 0.5 ≤ c ≤ 1.5; more preferably, 1 ≤ c ≤ 1.2. In some embodiments, b + c = 2.

[0038] Gd represents the rare earth element gadolinium. d represents the molar or atomic number of Gd. 0.3≤d≤0.8; preferably, 0.4≤d≤0.7; more preferably, 0.5≤d≤0.6.

[0039] RE is selected from one or more of La and Y. Preferably, RE is La. 0.1≤e≤0.6; preferably, 0.2≤e≤0.5; more preferably, 0.3≤e≤0.4. In some embodiments, d+e=1.

[0040] Nb represents the transition metal element niobium. f represents the molar or atomic number of Nb. 0.3 ≤ f ≤ 1.2. In some embodiments, 0.8 ≤ f ≤ 1.0; preferably, 0.9 ≤ f ≤ 0.996. In other embodiments, 0.5 ≤ f ≤ 0.65; preferably, 0.55 ≤ f ≤ 0.5976.

[0041] A is selected from one or more of Ta, V, and P. Preferably, A is P. g represents the molar or atomic number of A. 0 ≤ g ≤ 0.6; preferably, 0.1 ≤ g ≤ 0.5; more preferably, 0.3 ≤ g ≤ 0.3984. In some embodiments, f + g = 0.996.

[0042] O represents oxygen. h represents the molar or atomic number of O. 4 ≤ h ≤ 8; preferably, 5 ≤ h ≤ 7; more preferably, 6 ≤ h ≤ 6.5.

[0043] Mn represents manganese. m represents the molar or atomic number of Mn. 0.001≤m≤0.007; preferably, 0.003≤m≤0.006; more preferably, 0.004≤m≤0.005. In some embodiments, f+g+m=1.

[0044] According to one embodiment of the present invention, the light conversion material has one of the following compositions:

[0045] Li 0.004 Sr2Gd 0.6 La 0.4 Nb 0.996 O6:0.004Mn 4+ ;

[0046] Li 0.004 Sr 0.8 Ca 1.2 Gd 0.6 La 0.4 Nb 0.996 O6:0.004Mn 4+ ;

[0047] Li 0.004 Sr 0.8 Ca 1.2 Gd 0.6 La 0.4 Nb 0.5976 P 0.3984 O6:0.004Mn 4+ .

[0048] The composition and content of the above elements help to improve the luminescence intensity, damp heat stability and UV aging resistance of light conversion materials.

[0049] The light conversion material of the present invention has an Sr2GdNbO6 crystal structure.

[0050] The light-converting material of this invention exhibits a peak emission intensity of 650–690 nm when excited by ultraviolet light, its corresponding strongest excitation wavelength. In some embodiments, it is 670–685 nm. The light-converting material of this invention shows a high degree of matching with the absorption band of chlorophyll a.

[0051] <Preparation Methods of Light Conversion Materials>

[0052] The method for preparing the light conversion material of the present invention includes the following steps: calcining the raw materials obtained according to the composition of the light conversion material at 1200-1500°C to obtain the light conversion material. In some embodiments, the raw materials and a fluxing agent are calcined at 1200-1500°C to obtain the light conversion material. Examples of fluxing agents include, but are not limited to, H3BO3. The amount of flux can be 1-10% of the mass of the raw materials; preferably 3-6%.

[0053] Before calcination, the raw materials can be mixed and then ground or ball-milled. A co-solvent can be added during the grinding or ball-milling process.

[0054] The calcination temperature is 1200–1500℃; preferably 1300–1400℃. The calcination time can be 6–15 hours; preferably 7–10 hours. Calcination can be carried out in an air atmosphere. Calcination can be carried out in a muffle furnace.

[0055] The Li source can be Li₂CO₃. The Sr source can be SrCO₃. The Gd source can be Gd₂O₃. The La source can be La₂O₃. The Nb source can be Nb₂O₅. The Mn source can be MnO₂. The Ca source can be CaCO₃. The P source can be (NH₄)₂HPO₄. Preferably, no flux is used in the preparation process.

[0056] Applications of light conversion materials

[0057] The light conversion material of the present invention can convert ultraviolet light in the 300-380 nm wavelength range and green light in the 480-550 nm wavelength range into red light in the 650-750 nm wavelength range. Therefore, the present invention provides the use of the above-mentioned light conversion material in converting ultraviolet light in the 300-380 nm wavelength range and / or green light in the 480-550 nm wavelength range into red light in the 650-750 nm wavelength range.

[0058] The light conversion material of the present invention can convert ultraviolet and green light into red light that is beneficial to plants, and the light conversion material of the present invention can be applied to agricultural films.

[0059] Examples 1-4 and Comparative Example 1

[0060] Using Li₂CO₃ as the Li source, SrCO₃ as the Sr source, Gd₂O₃ as the Gd source, La₂O₃ as the La source, Nb₂O₅ as the Nb source, MnO₂ as the Mn source, CaCO₃ as the Ca source, and (NH₄)₂HPO₄ as the P source, the raw materials were prepared according to the chemical composition of the light conversion material shown in Table 1.

[0061] Place the raw material in an agate mortar and grind for 30 minutes. If H3BO3 is used as a co-solvent, add H3BO3 to the agate mortar and grind it together with the raw material to obtain the ground raw material.

[0062] The ground raw material was calcined in a muffle furnace at 1400°C for 8 hours in an air atmosphere, and then naturally cooled to 25°C to obtain the light conversion material.

[0063] The chemical composition of the light conversion material and the amount of H3BO3 used are shown in Table 1.

[0064] Table 1

[0065] Serial Number Chemical composition of light conversion materials <![CDATA[Dosage of H3BO3]]> Example 1 <![CDATA[Li 0.004 Sr2Gd 0.6 The 0.4 Nb 0.996 O6:0.004Mn 4+ ]]> 4% of raw material quality Example 2 <![CDATA[Li 0.004 Sr2Gd 0.6 The 0.4 Nb 0.996 O6:0.004Mn 4+ ]]> — Example 3 <![CDATA[Li 0.004 Sr. 0.8 That 1.2 Gd 0.6 to 0.4 Nb 0.996 O6:0.004Mn 4+ ]]> — Example 4 <![CDATA[Li 0.004 Sr. 0.8 That 1.2 Gd 0.6 to 0.4 Nb 0.5976 P 0.3984 O6:0.004Mn 4+ ]]> — Comparative Example 1 <![CDATA[Li 0.004 Sr2GdNb 0.996 O6:0.004Mn 4+ ]]> 4% of raw material quality

[0066] Note: "—" indicates that H3BO3 is not used.

[0067] Experimental Example

[0068] XRD: Figure 1 The images show the XRD patterns of the light conversion materials of Example 4 and Comparative Example 1. Figure 1 It is known that the light conversion material of the present invention has a double perovskite crystal structure of Sr2GdNbO6.

[0069] Emission spectrum: Figure 2 The images show the emission spectra of the light conversion materials of the Examples and Comparative Examples under excitation by ultraviolet light at their respective strongest excitation wavelengths. Specifically, the strongest excitation wavelength of the light conversion material in Example 1 is 347 nm, in Example 2 it is 344 nm, in Example 3 it is 312 nm, in Example 4 it is 310 nm, and in Comparative Example 1 it is 345 nm. Figure 2 It can be seen that the emission spectra of Examples 1 to 4 gradually converge from two peaks (667nm, 684nm) to a single peak (684nm), and the luminescence intensity gradually increases. The luminescence intensity of the light conversion material in Example 4 is 22 times that of Comparative Example 1.

[0070] Excitation spectrum: Figure 3 The images show the excitation spectra of the light conversion materials of the examples and comparative examples under monitoring at their corresponding emission peak wavelengths. Specifically, the emission peak wavelength of the light conversion material in Example 1 is 667 nm, the emission peak wavelength of the light conversion material in Example 2 is 685 nm, the emission peak wavelength of the light conversion material in Example 3 is 684 nm, the emission peak wavelength of the light conversion material in Example 4 is 684 nm, and the emission peak wavelength of the light conversion material in Comparative Example 1 is 667 nm. Figure 3It is known that the excitation regions of the light conversion material of the present invention are the violet light region and the green light region. From Example 1 to Example 4, the excitation peak in the green light region undergoes a red shift, gradually approaching 510 nm; the excitation peak in the violet light region gradually changes from two peaks (315 nm, 345 nm) to one peak (310 nm).

[0071] Humidity and Heat Stability: The light conversion material was subjected to humidity and heat treatment at 85°C and 80% humidity. The emission spectra of the light conversion material of Example 4 before and after humidity and heat treatment were tested under the condition of using ultraviolet light with the strongest excitation wavelength of 310 nm as the excitation light. The ratio (I) of the emission peak intensity of the light conversion material after different humidity and heat treatment times to the emission peak intensity of the light conversion material before humidity and heat treatment was calculated. Figure 4 As shown. By Figure 4 It can be seen that the light conversion material of Example 4 still maintains an I value of 93.25% after 6 days of damp heat treatment, which shows good damp heat stability.

[0072] UV aging resistance: The light conversion material was subjected to UV aging treatment by irradiation with 340nm UV light. The emission spectrum of the light conversion material of Example 4 before and after aging treatment was tested under the condition of using the strongest excitation wavelength of 310nm UV light as the excitation light. The ratio (P) of the emission peak intensity of the light conversion material after different aging times to the emission peak intensity of the light conversion material before aging treatment was calculated. Figure 5 As shown. By Figure 5 It can be seen that the light conversion material of Example 4 still maintains a P value of 95.89% after 9 days of QUV aging treatment, which shows that it has good UV aging resistance.

[0073] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A light-converting material, characterized in that The light conversion material has a composition shown in formula (1): Li a Sr b M c Gd d RE e Nb f A g O h :mMn 4+ (1); Wherein, M is Ca, RE is La, A is P; 0.003≤a≤0.007, 0.8≤b≤1, 0.5≤c≤1.5, b+c=2, 0.4≤d≤0.7, 0.2≤e≤0.5, 0.3≤f≤1.2, 0<g≤0.6, 5≤h≤7, 0.003≤m≤0.006; Wherein, a, b, c, d, e, f, g, h and m respectively represent the mole fraction or atomic fraction of each element; The light conversion material has a Sr2GdNbO6 crystal structure.

2. The light converting material of claim 1, wherein, 0.1≤g≤0.5, f+g=0.996, d+e=1.

3. The light converting material of claim 1, wherein, The light conversion material has a chemical composition shown as follows: Li 0.004 Sr 0.8 Ca 1.2 Gd 0.6 La 0.4 Nb 0.5976 P 0.3984 O6: 0.004Mn 4+ .

4. The method of producing a light-converting material according to any one of claims 1 to 3, characterized in that The method comprises the following steps: The raw material obtained according to the composition of the light conversion material is calcined at 1200-1500℃ to obtain the light conversion material.

5. The preparation method according to claim 4, characterized in that, No fluxing agent is used in the preparation process.

6. Use of the light conversion material according to any one of claims 1-3 in converting ultraviolet light in the 300-380 nm wave band and / or green light in the 480-550 nm wave band into red light in the 650-750 nm wave band.

Images