Application of rubidium lithium titanium germanate as fluorescent material

Abstract

The invention provides application of rubidium lithium titanium germanate as a fluorescent material. The chemical formula of the fluorescent material rubidium lithium titanium germanate provided by the invention is Rb4Li2TiOGe4O12, lead-containing components with strong toxicity are prevented from being introduced into the fluorescent material, and expensive rare earth ions do not need to be doped; the fluorescent material is prepared by adopting a solid-phase synthesis method and a fluxing agent method, and the preparation method of the fluorescent material is simple and easy for large-scale production and popularization. The fluorescent material can be effectively excited by ultraviolet light with the wavelength near 264 nm, shows strong blue light emission near 481 nm, and is high in luminous efficiency; the fluorescent material has high thermal stability and long fluorescence lifetime; the fluorescent material can be used for manufacturing luminescent devices and applied to the fields of illumination, liquid crystal display backlight and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent materials, and in particular to the use of rubidium lithium titanate germanate as a fluorescent material. Background Art

[0002] Light emitting diodes (LEDs) have the characteristics of energy saving and environmental protection, long working life, small size, fast response and good impact resistance. They are widely used in general lighting and flat panel display backlight fields and are considered to be the fourth generation of lighting sources that are expected to replace traditional lighting. Therefore, researchers from various countries have developed LED phosphors of different systems such as aluminates, silicates, germanates, phosphates, vanadates and oxynitrides based on the needs of LED applications in different fields. Since most substances do not emit fluorescence intrinsically, they need to be doped with transition metals or rare earth ions to produce fluorescence. Currently, commercial LED fluorescent materials include yellow-emitting YAG:Ce 3 + , red light K2SiF6:Mn 4+ , blue light BaMg2Al 16 O 27 :Eu 2+ wait.

[0003] In recent years, self-luminescent materials, that is, materials that emit fluorescence without the need for activating doped ions, have attracted widespread attention from researchers. They are low-cost and do not require expensive rare earth ions. For example, the popular perovskite material CsBX3 (B is Pb 2+ , Sn 2+ ; X is Cl - , Br - , I - ), but this type of material contains the toxic element Pb, and Sn 2+ Therefore, the development of new fluorescent materials that do not contain heavy metal elements such as lead is a hot topic and has important practical value. It has broad application prospects in the manufacture of display devices, light-emitting and lighting devices. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides the use of rubidium lithium titanate germanate as a fluorescent material. When excited by ultraviolet light at a wavelength of approximately 264 nm, the fluorescent material exhibits strong cyan-blue emission near 481 nm with high luminous efficiency. The fluorescent material also exhibits high thermal stability (with a heat-resistant temperature range of 80K-400K) and a long fluorescence lifetime (on the order of 3.16 ms).

[0005] The present invention specifically provides the following technical solutions:

[0006] The present invention provides a use of rubidium lithium titanate germanate as a fluorescent material.

[0007] According to an embodiment of the present invention, the rubidium lithium titanate germanate is used as a lead-free self-excited inorganic fluorescent material.

[0008] According to an embodiment of the present invention, the rubidium lithium titanate germanate does not contain the element Pb.

[0009] According to an embodiment of the present invention, the rubidium lithium titanate germanate does not contain dopant ions.

[0010] According to an embodiment of the present invention, the chemical formula of the rubidium lithium titanium germanate is Rb4Li2TiOGe4O 12 (RLTG).

[0011] According to an embodiment of the present invention, the crystal of rubidium lithium titanate germanate belongs to the tetragonal system and the space group is P4nc.

[0012] According to an embodiment of the present invention, the molecular weight of the rubidium lithium titanate germanate is 902.02 g / mol; the unit cell parameters are

[0013] According to an embodiment of the present invention, the rubidium lithium titanate germanate is a polycrystalline powder structure or a large-scale crystal structure.

[0014] According to an embodiment of the present invention, the rubidium lithium titanate germanate can be prepared by methods known in the art.

[0015] According to an embodiment of the present invention, the polycrystalline powder structure of rubidium lithium titanate germanate is prepared, for example, by the following method:

[0016] The Rb-containing compound, the Li-containing compound, the Ti-containing compound and the Ge-containing compound are ground and mixed, pre-fired at 500-600° C. for more than 24 hours, cooled to room temperature, ground and mixed again, and then sintered at 700-850° C. for more than 12 hours.

[0017] According to an embodiment of the present invention, the Rb-containing compound is one or more of Rb oxide, Rb hydroxide, Rb carbonate, Rb halide, Rb nitrate or Rb oxalate; the Li-containing compound is one or more of Li oxide, Li hydroxide, Li carbonate, Li halide, Li nitrate or Li oxalate; the Ti-containing compound is one or more of Ti oxide, Ti hydroxide, Ti halide, Ti nitrate or Ti oxalate; the Ge-containing compound is one or more of Ge oxide, Ge hydroxide, Ge halide, Ge nitrate or Ge oxalate.

[0018] According to an embodiment of the present invention, the molar ratio of Rb, Li, Ti and Ge elements in the Rb-containing compound, the Li-containing compound, the Ti-containing compound and the Ge-containing compound is 4:2:1:4.

[0019] According to an embodiment of the present invention, the Rb-containing compound, the Li-containing compound, the Ti-containing compound and the Ge-containing compound are ground and mixed, heated to 500-600°C at a heating rate of 10-50°C / h and pre-fired for more than 24 hours, cooled to room temperature and then ground and mixed again, and then heated to 700-850°C at a heating rate of 10-50°C / h and sintered for more than 12 hours.

[0020] According to an embodiment of the present invention, the large-scale crystal structure of rubidium lithium titanate germanate is prepared, for example, by the following method:

[0021] (1) grinding and mixing a Rb-containing compound, a Li-containing compound, a Ti-containing compound, a Ge-containing compound, and a flux to obtain a raw material; or grinding and mixing the polycrystalline powder structure of rubidium lithium titanate germanate prepared above and a flux to obtain a raw material;

[0022] (2) melting the raw materials and heating them to 700-950°C, stirring at a constant temperature to obtain a melt;

[0023] (3) Cool the melt and introduce a seed crystal at a temperature 2 to 10°C above the melt saturation point. Cool the melt at a rate of 0.1 to 5°C / day and rotate the crystal at a speed of 15 to 50 r / min to start crystal growth. After the crystal growth is completed, lift the crystal from the liquid surface and anneal it to room temperature at a cooling rate of no more than 100°C / h.

[0024] According to an embodiment of the present invention, the flux includes one or more of RbF, LiF and MoO3.

[0025] According to an embodiment of the present invention, the molar ratio of the flux to the Ti element in the Ti-containing compound is 2-5:1.

[0026] According to an embodiment of the present invention, the Rb-containing compound is one or more of Rb oxide, Rb hydroxide, Rb carbonate, Rb halide, Rb nitrate or Rb oxalate; the Li-containing compound is one or more of Li oxide, Li hydroxide, Li carbonate, Li halide, Li nitrate or Li oxalate; the Ti-containing compound is one or more of Ti oxide, Ti hydroxide, Ti halide, Ti nitrate or Ti oxalate; the Ge-containing compound is one or more of Ge oxide, Ge hydroxide, Ge halide, Ge nitrate or Ge oxalate.

[0027] According to an embodiment of the present invention, the molar ratio of Rb, Li, Ti and Ge elements in the Rb-containing compound, the Li-containing compound, the Ti-containing compound and the Ge-containing compound is 4:2:1:4.

[0028] According to an embodiment of the present invention, the emission peak of the fluorescent material under the excitation of ultraviolet light with a wavelength of approximately 264 nm is located at 481 nm.

[0029] According to an embodiment of the present invention, the fluorescent material exhibits strong cyan-blue light emission near 481nm and has high luminous efficiency. The fluorescent material has high thermal stability and long fluorescence lifetime, a heat-resistant temperature range of 80K-400K, and a fluorescence lifetime of the order of 3.16ms.

[0030] According to an embodiment of the present invention, the fluorescent material can emit fluorescence by itself without activating doping ions.

[0031] The present invention also provides a light-emitting device, which includes a fluorescent material, and the fluorescent material includes rubidium lithium titanate germanate.

[0032] According to an embodiment of the present invention, the chemical formula of the rubidium lithium titanium germanate is Rb4Li2TiOGe4O 12 .

[0033] According to an embodiment of the present invention, the rubidium lithium titanate germanate is defined as described above.

[0034] Beneficial effects of the present invention:

[0035] The present invention provides a use of rubidium lithium titanate germanate as a fluorescent material. The chemical formula of the fluorescent material rubidium lithium titanate germanate provided by the present invention is Rb4Li2TiOGe4O 12 The fluorescent material avoids the introduction of highly toxic lead components and does not require doping with expensive rare earth ions. It is prepared using a solid-phase synthesis method and a flux method, making the preparation of the fluorescent material simple and easy to mass-produce. The fluorescent material can be effectively excited by ultraviolet light with a wavelength near 264 nm, exhibiting strong cyan-blue emission near 481 nm with high luminous efficiency. It also has high thermal stability and a long fluorescence lifetime. The fluorescent material can be used to manufacture light-emitting devices and in applications such as lighting and liquid crystal display backlighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The Rb4Li2TiOGe4O provided by the present invention is shown 12 Schematic diagram of the crystal structure of fluorescent materials.

[0037] Figure 2The Rb4Li2TiOGe4O provided by the present invention is shown 12 Excitation and emission spectra of fluorescent materials.

[0038] Figure 3 The Rb4Li2TiOGe4O provided by the present invention is shown 12 Temperature-dependent emission spectra of fluorescent materials.

[0039] Figure 4 The Rb4Li2TiOGe4O provided by the present invention is shown 12 Fluorescence lifetime test chart of fluorescent materials. DETAILED DESCRIPTION

[0040] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0042] Example 1

[0043] Preparation of lead-free self-excited inorganic fluorescent material Rb4Li2TiOGe4O by solid phase reaction method 12 Solid phase powder, the reaction equation is 2Rb2CO3+Li2CO3+TiO2+4GeO2=Rb4Li2TiOGe4O 12 ; The feeding ratio of the above four reaction raw materials is Rb2CO3 (4.619g, 0.02mol), Li2CO3 (0.739g, 0.01mol), TiO2 (0.799g, 0.01mol), and GeO2 (4.186g, 0.04mol).

[0044] Lead-free self-excited inorganic fluorescent material Rb4Li2TiOGe4O 12 The specific preparation steps are as follows: four reaction raw materials are weighed according to the above dosages, the reaction raw materials are placed in a mortar, ground and mixed, then placed in a platinum crucible, placed in a muffle furnace, heated to 500°C at a rate of 50°C / h for pre-sintering, kept warm for 24 hours and then cooled, after cooling to room temperature, the sample is taken out and ground and mixed again, then placed in a muffle furnace, heated to 750°C at a rate of 50°C / h and sintered for 12 hours, and after cooling, a sample with a chemical formula of Rb4Li2TiOGe4O is obtained. 12 of polycrystalline powder.

[0045] Example 2

[0046] Preparation of lead-free self-excited inorganic fluorescent material Rb4Li2TiOGe4O by flux method 12 The method comprises the following steps: using LiF as a flux, weighing 902.172 g of Rb4Li2TiOGe4O prepared in Example 1 at a solute to solvent molar ratio of 1:3, 12 Polycrystalline powder (1 mol) and 77.818 g of LiF (3 mol) were ground and mixed in a mortar, melted in batches, and loaded into a Φ80 mm × 80 mm crucible. The crucible was placed in a vertical crystal growth furnace, heated to 850°C, stirred at a constant temperature for 48 hours, and then cooled to 5°C above the saturation point. A seed crystal was introduced and the temperature was cooled at a rate of 0.5°C / day with a rotation speed of 10 r / min to start crystal growth. After the crystal growth was completed, the seed crystal rod was lifted and the crystal was lifted out of the liquid surface. The temperature was then cooled to room temperature at a rate of 20°C / h to obtain transparent Rb4Li2TiOGe4O 12 Large size crystals.

[0047] Example 3

[0048] Rb4Li2TiOGe4O prepared in Example 2 12 Large-size crystals were tested, and their excitation and emission spectra are shown in Figure 2 .Depend on Figure 2 It can be seen that the fluorescent material can be effectively excited by ultraviolet light with a wavelength of about 264 nm, and the emission spectrum reaches an intensity peak at 481 nm, emitting cyan-blue light.

[0049] Rb4Li2TiOGe4O prepared in Example 2 12 Large-size crystals were tested, and their temperature-dependent emission spectra are shown in Figure 3 .Depend on Figure 3 It can be seen that when the temperature changes in the range of 80K to 400K, the fluorescent materials all have strong fluorescence, and the emission peak position does not shift, and have stable luminescence.

[0050] Rb4Li2TiOGe4O prepared in Example 2 12 Large-size crystals were tested, and the fluorescence lifetime test diagram is shown in Figure 4 .Depend on Figure 4 It can be seen that the fluorescent material has a very long fluorescence lifetime, which can reach 3.16 milliseconds, and is very beneficial for application.

[0051] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. Use of rubidium lithium titanate germanate as a fluorescent material.

2. The use according to claim 1, wherein The rubidium lithium titanate germanate is used as a lead-free self-excited inorganic fluorescent material.

3. The use according to claim 1 or 2, wherein The chemical formula of the rubidium lithium titanium germanate is Rb4Li2TiOGe4O 12 .

4. The use according to any one of claims 1 to 3, wherein The crystal of the rubidium lithium titanate germanate belongs to the tetragonal system and has a space group of P4nc.

5. The use according to any one of claims 1 to 4, wherein The rubidium lithium titanate germanate is a polycrystalline powder structure or a large-size crystal structure.

6. The use according to any one of claims 1 to 5, wherein The emission peak of the fluorescent material under the excitation of ultraviolet light with a wavelength of approximately 264 nm is located at 481 nm.

7. The use according to any one of claims 1 to 6, wherein The fluorescence lifetime of the fluorescent material is on the order of 3.16 ms.

8. The use according to any one of claims 1 to 7, wherein The heat-resistant temperature range of the fluorescent material is 80K-400K.

9. A light emitting device, wherein: The light emitting device includes a fluorescent material, and the fluorescent material includes rubidium lithium titanate germanate.

10. The light emitting device according to claim 9, wherein The chemical formula of the rubidium lithium titanium germanate is Rb4Li2TiOGe4O 12 .

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