CN107163934B

CN107163934B - Quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder and preparation method thereof

Info

Publication number: CN107163934B
Application number: CN201710627850.8A
Authority: CN
Inventors: 廖金生; 王祺; 温和瑞; 陈景林; 傅俊祥
Original assignee: Buddhist Tzu Chi General Hospital
Current assignee: Buddhist Tzu Chi General Hospital
Priority date: 2017-07-28
Filing date: 2017-07-28
Publication date: 2020-03-31
Anticipated expiration: 2037-07-28
Also published as: CN107163934A

Abstract

Hair brushThe fluorescent powder can emit red luminescence with the wavelength of 662nm after being excited by excitation light sources such as ultraviolet light or blue light and the like, and has a chemical formula of LiAl_4‑xO₆F:xMn⁴⁺Wherein x is more than or equal to 0.002 and less than or equal to 0.04. The preparation method comprises the following steps: and mixing and grinding lithium fluoride, aluminum oxide and manganese carbonate, putting the mixture into a muffle furnace for roasting, and grinding to obtain the red fluorescent powder of the lithium aluminum fluoride. The invention has the obvious advantages that the raw materials are wide in source and easy to obtain; the required equipment requirement is simple, the manufacturing method is simple, and the cost is low; the synthesized target product has good chemical stability and high luminous efficiency.

Description

Quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder and preparation method thereof

Technical Field

The invention relates to the field of red fluorescent materials, in particular to Mn⁴⁺An ion-doped fluorine-aluminum oxide lithium red fluorescent material and a preparation method thereof.

Background

With the development of the world economy and society, environmental protection and energy shortage problems have been increasingly noticed, and mankind has studied many methods to protect the environment and reduce energy consumption. In the lighting industry, the white light LED has the advantages of small volume, low power consumption, long service life, environmental protection, energy conservation and the like compared with the traditional incandescent lamp, fluorescent lamp and the like. Under the same brightness condition, the power consumption of the LED lamp is only one tenth of that of the incandescent lamp, and the service life of the LED lamp is 100 times that of the incandescent lamp. The LED light source has no infrared radiation, no secondary pollution caused by mercury vapor overflowing due to the broken fluorescent lamp tube and the like. LEDs are also recognized as a significant innovation in the 21 st century illumination source.

At present, the commercial white light LED utilizes a blue light LED chip (InGaN) and yellow fluorescent powder (YAG: Ce) which can be effectively excited by blue light³⁺) In combination with the generation, the method has the disadvantage that the light emission in the red spectrum region is weak, which directly results in the higher color temperature (usually at 4500-. To solve this problem, the method can be used inA red phosphor (which can be excited by blue light) is introduced into a commercial white LED, or an ultraviolet LED chip is used to excite a red-green-blue three-primary-color mixed phosphor to prepare another white LED. In both solutions, there is a need to develop efficient red fluorescent materials that can be excited by ultraviolet or blue light.

Recently Eu²⁺Red fluorescent materials such as doped nitrides, oxynitrides, silicates, aluminates, etc. are reported successively. Among them, nitrides or oxynitrides have exceptionally excellent spectral properties, and quantum efficiencies of more than 70% are considered as potential phosphors. However, synthesis of these materials typically requires relatively harsh conditions, such as CaAlSiN₃:Eu²⁺The synthesis is required to be carried out at 1800 ℃ under a nitrogen atmosphere at 5 atm. The high temperature and high pressure have high requirements on equipment, and the active ions are rare earth ions with higher price.

Mn⁴⁺Belonging to the outer layer of electron as 3d³The electronic structure is transition metal ion, and the ion has the spectral characteristics of a broad spectrum excitation peak and a narrow-band red light emission peak. This Mn⁴⁺The ion-doped red fluorescent powder can be used for preparing a red LED. Mn⁴⁺Research on ion-doped red phosphor has been focused and reported, such as Mn⁴⁺Ion-doped aluminate phosphor (CaMg)₂Al₁₆O₂₇:Mn⁴⁺、CaAl₂O₄:Mn⁴⁺、Sr₄Al₁₄O₂₅:Mn⁴⁺And GdAlO₃:Mn⁴⁺Etc.), Mn⁴⁺Ion-doped fluoride phosphor (K)₂TiF₆:Mn⁴⁺、K₂SiF₆:Mn⁴⁺、BaSiF₆:Mn⁴⁺Etc.). Mn has been reported so far⁴⁺The practical applicability of ion-doped red phosphor in white light LEDs is not ideal, so that the research on novel Mn is carried out to obtain the red phosphor with low cost and high luminous efficiency⁴⁺The ion-doped red fluorescent material has special significance.

Disclosure of Invention

The invention aims to provide quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder which has absorption in ultraviolet and blue light spectral regions and red fluorescence covering 625-750nm and having a luminescence center at 662nm under the excitation of light in the ultraviolet to blue light regions.

The invention also aims to provide a preparation method of the quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder. The novel quadrivalent manganese ion doped fluorine-alumina lithium red fluorescent material is prepared by using low-cost quadrivalent manganese ions as active ions and adopting a high-temperature solid phase method under mild conditions and in air atmosphere.

The technical scheme of the invention is as follows:

quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder, the crystal structure of which is a cubic crystal system and the chemical formula of which is LiAl_4-xO₆F:xMn⁴⁺Wherein x is more than or equal to 0.002 and less than or equal to 0.04.

A preparation method of quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder comprises the following steps:

step (1): weighing raw materials, accurately weighing a lithium-containing compound raw material, an aluminum-containing compound raw material, a manganese-containing compound raw material and a fluorine-containing compound raw material respectively according to the element molar ratio of Li to Al to F to Mn of 1 (4-x) to 1 to x, wherein x is more than or equal to 0.002 and less than or equal to 0.04;

step (2): grinding and uniformly mixing the raw materials weighed in the step (1), firing for 5-8 hours at the temperature of 700-900 ℃, and then cooling to room temperature to obtain the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Mn of (2)⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium.

In the step (1), the lithium-containing compound raw material is any one of oxide, fluoride, carbonate, oxalate, acetate and nitrate.

In the step (1), the manganese-containing compound raw material is any one of carbonate, oxalate, acetate and nitrate.

In the step (1), the fluorine-containing compound raw material is one of lithium fluoride or aluminum fluoride.

In the step (1), the aluminum-containing compound raw material is any one of oxide, fluoride, carbonate, oxalate, acetate and nitrate.

The firing of step (2) is carried out in an air atmosphere.

The novel quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent material has good thermal stability, high fluorescence intensity and good color rendering property, and is a red fluorescent material which has excellent performance and can be used for warm white LEDs. The fluorescent powder prepared by the invention can absorb in ultraviolet and blue light spectral regions, has red fluorescence covering 625-750nm range and having a luminescence center at 662nm under the excitation of light in the ultraviolet to blue light region, and can be applied to the fields of fluorescent lamps, solid-state LEDs, displays and the like. The red fluorescent material taking the lithium fluoroaluminate as the matrix is prepared in the air by adopting a high-temperature solid phase method, the preparation method is simple and easy to implement, high-temperature and high-pressure conditions are not required, and a proper heating and temperature rising process is adopted to obtain the tetravalent manganese ion doped lithium fluoroaluminate red fluorescent material for the warm white LED with excellent performance.

Drawings

FIG. 1 shows a novel Mn prepared in example 1 of the present invention⁴⁺Ion-doped lithium fluoroaluminate (LiAl)_3.992O₆F:0.008Mn⁴ ⁺) Excitation spectrum of red fluorescent material at 662nm of emission wavelength.

FIG. 2 shows a novel Mn prepared in example 1 of the present invention⁴⁺Ion-doped lithium fluoroaluminate (LiAl)_3.992O₆F:0.008Mn⁴ ⁺) Emission spectrum of red fluorescent material at excitation wavelength of 280 nm.

FIG. 3 shows a novel Mn prepared in example 1 of the present invention⁴⁺Ion-doped lithium fluoroaluminate (LiAl)_3.992O₆F:0.008Mn⁴ ⁺) Emission spectrum of red fluorescent material at 365nm of excitation wavelength.

FIG. 4 shows a novel Mn prepared in example 1 of the present invention⁴⁺Ion-doped lithium fluoroaluminate (LiAl)_3.992O₆F:0.008Mn⁴ ⁺) Emission spectrum of red fluorescent material at 453nm of excitation wavelength.

FIG. 5 shows a novel Mn prepared in example 1 of the present invention⁴⁺Different manganese ions of the ion-doped lithium aluminum fluoride oxide red fluorescent material under the excitation wavelength of 453nmEmission spectrum of the sub-doping concentration.

FIG. 6 shows a novel Mn prepared in example 1 of the present invention⁴⁺Ion-doped lithium fluoroaluminate (LiAl)_3.992O₆F:0.008Mn⁴ ⁺) The fluorescence attenuation curve of the red fluorescent material has an excitation wavelength of 453nm and a monitoring wavelength of 662 nm.

Detailed Description

Example 1: selecting a lithium-containing compound raw material, an aluminum-containing compound raw material, a fluorine-containing compound raw material and a manganese-containing compound raw material as initial raw materials, accurately weighing the raw materials according to the element molar ratio of Li to Al to F to Mn of 1 (4-x) to 1 to x, wherein x is 0.002, 0.004, 0.008, 0.016, 0.024, 0.032 and 0.04 respectively; respectively weighing three raw materials of lithium fluoride, alumina and manganese carbonate, and controlling the total weight of the mixture to be 20 g; after ball milling and uniform mixing, 20 g of the mixture is put into a corundum crucible, and then the crucible is put into a high-temperature electric furnace; accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 750 ℃ for 7 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺Ion-doped fluorine-aluminum oxide lithium red fluorescent material; x-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of the fluorine-aluminum oxide lithium; the novel quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent material LiAl prepared by the embodiment_4-xO₆F:xMn⁴⁺(x is 0.008) in the range of 200-550 nm, 280nm, 365nm and 453nm excitation peaks exist respectively (shown in figure 1), wherein the excitation peak at 280 or 365nm is matched with a current commercial (near) ultraviolet chip, and the excitation peak at 453nm is matched with a current commercial blue chip; the novel quadrivalent manganese ion doped lithium aluminum fluoride red fluorescent material can generate red fluorescence with peak positions located at 662nm under the excitation of 280nm, 365nm and 453nm, and covers a 625-750nm spectral region (see fig. 2, 3 and 4 respectively). FIG. 5 shows a new quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent material LiAl with an excitation wavelength of 453nm_4-xO₆F:xMn⁴⁺(x is more than or equal to 0.002 and less than or equal to 0.04) in different manganese ion doping concentrations.According to FIG. 5, it can be seen that the new quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent material LiAl_4-xO₆F:xMn⁴⁺When the doping concentration of the manganese ions is about 0.008, the luminous intensity is the best. FIG. 6 shows a new quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent material LiAl_4-xO₆F:xMn⁴⁺(x is 0.08), the excitation wavelength is 453nm, the monitoring wavelength is 662nm, the life curve conforms to the double-exponential decay equation, the fitting degree can reach 99.9%, and the fluorescence life is 0.46ms respectively.

Example 2: lithium fluoride, aluminum carbonate and manganese carbonate are selected as starting raw materials, three raw materials are accurately weighed according to the element molar ratio R, Al, F, Mn and Mn of 1 (4-x) to 1: x, wherein x is respectively 0.002, 0.004, 0.008, 0.016, 0.024, 0.032 and 0.04. The total weight of the mixture is controlled to be about 20 g. After being ball-milled and uniformly mixed, 20 g of the mixture is put into a corundum crucible, and then the corundum crucible is put into a high-temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 750 ℃ for 7 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of the lithium aluminum fluoride oxide. The spectral properties of the phosphor were similar to those of example 1.

Example 3: lithium fluoride, aluminum oxide and manganese acetate are selected as starting raw materials, and the three raw materials are accurately weighed according to the element molar ratio of Li to Al to F to Mn of 1 (4-x) to 1 to x, wherein x is more than or equal to 0.002 and less than or equal to 0.04. The total weight of the mixture is controlled to be about 20 g. After being ball-milled and uniformly mixed, 20 g of the mixture is put into a corundum crucible, and then the corundum crucible is put into a high-temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 750 ℃ for 7 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis shows that the prepared red fluorescenceThe material is a pure phase of lithium fluoroaluminate. The spectral properties of the phosphor were similar to those of example 1.

Example 4: lithium fluoride, aluminum nitrate and manganese nitrate are selected as initial raw materials, and three raw materials are accurately weighed according to the element molar ratio of Li to Al to F to Mn of 1 (4-x) to 1 to x, wherein x is more than or equal to 0.002 and less than or equal to 0.04. The total weight of the mixture is controlled to be about 20 g. After being ball-milled and uniformly mixed, 20 g of the mixture is put into a corundum crucible, and then the corundum crucible is put into a high-temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 750 ℃ for 7 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of the lithium aluminum fluoride oxide. The spectral properties of the phosphor were similar to those of example 1.

Example 5: lithium fluoride, aluminum oxide and manganese oxide are selected as initial raw materials, and the three raw materials are accurately weighed according to the element molar ratio of Li to Al to F to Mn of 1 (4-x) to 1 to x, wherein x is more than or equal to 0.002 and less than or equal to 0.04. The total weight of the mixture is controlled to be about 20 g. After being ball-milled and uniformly mixed, 20 g of the mixture is put into a corundum crucible, and then the corundum crucible is put into a high-temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 750 ℃ for 7 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of the lithium aluminum fluoride oxide. The spectral properties of the phosphor were similar to those of example 1.

Example 6: lithium fluoride, aluminum oxide and manganese carbonate are selected as initial raw materials, three raw materials are accurately weighed according to the element molar ratio R, Al, F, Mn and Mn of 1 (4-x) to 1: x, wherein x is respectively 0.002, 0.004, 0.008, 0.016, 0.024, 0.032 and 0.04. The total weight of the mixture is controlled to be about 20 g. After ball milling and uniformly mixing 20 g of mixture, putting the mixture into a corundum crucible, and then putting the corundum crucible into the corundum crucibleIn a high temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 700 ℃ for 8 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of the lithium aluminum fluoride oxide. The spectral properties of the phosphor were similar to those of example 1.

Example 7: lithium fluoride, aluminum oxide and manganese carbonate are selected as initial raw materials, three raw materials are accurately weighed according to the element molar ratio R, Al, F, Mn and Mn of 1 (4-x) to 1: x, wherein x is respectively 0.002, 0.004, 0.008, 0.016, 0.024, 0.032 and 0.04. The total weight of the mixture is controlled to be about 20 g. After being ball-milled and uniformly mixed, 20 g of the mixture is put into a corundum crucible, and then the corundum crucible is put into a high-temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 800 ℃ for 6 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of the lithium aluminum fluoride oxide. The spectral properties of the phosphor were similar to those of example 1.

Example 8: lithium fluoride, aluminum oxide and manganese carbonate are selected as initial raw materials, three raw materials are accurately weighed according to the element molar ratio R, Al, F, Mn and Mn of 1 (4-x) to 1: x, wherein x is respectively 0.002, 0.004, 0.008, 0.016, 0.024, 0.032 and 0.04. The total weight of the mixture is controlled to be about 20 g. After being ball-milled and uniformly mixed, 20 g of the mixture is put into a corundum crucible, and then the corundum crucible is put into a high-temperature electric furnace. Accurately controlling the heating rate, controlling the decomposition reaction speed of the compound raw materials, preventing the mixture from overflowing from the crucible, calcining the mixture at 900 ℃ for 5 hours, cooling the mixture to room temperature (25 ℃) along with the furnace, and obtaining the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Novel Mn of⁴⁺The red fluorescent material is made of fluorine-doped aluminum oxide lithium. X-ray diffraction analysis showed the red color producedThe fluorescent material is a pure phase of lithium fluoroaluminate. The spectral properties of the phosphor were similar to those of example 1.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above examples, for example, the lithium-containing compound may also be carbonate, phosphate (hydrogen) salt, acetate, nitrate, oxide, oxalate, etc., the aluminum-containing compound may also be phosphate (hydrogen) salt, acetate, oxalate, etc., the manganese-containing compound may also be phosphate (hydrogen) salt, oxalate, chloride, etc., any other changes, substitutions, modifications, combinations, simplifications, etc. without departing from the spirit and principle of the present invention should be equivalent replacement ways, and besides the above manganese ion-doped lithium fluoroaluminate red fluorescent material, other alkali metal fluoroaluminate red fluorescent materials such as sodium fluoroaluminate, potassium fluoroaluminate, cesium fluoroaluminate, etc. are within the protection scope of the present invention.

Claims

1. A quadrivalent manganese ion doped fluorine aluminum oxide lithium red fluorescent powder is characterized in that: the crystal structure is cubic crystal system and the chemical molecular formula is LiAl_4-xO₆F:xMn⁴⁺Wherein x is more than or equal to 0.002 and less than or equal to 0.04; has absorption in the ultraviolet and blue spectral regions, and has red fluorescence covering the interval of 625-750nm and the luminescence center at 662nm under the excitation of light in the ultraviolet to blue region.

2. The method for preparing the tetravalent manganese ion doped lithium aluminum fluoride red fluorescent powder of claim 1, which is characterized by comprising the following steps of:

step (1): weighing raw materials, accurately weighing a lithium-containing compound raw material, an aluminum-containing compound raw material, a manganese-containing compound raw material and a fluorine-containing compound raw material respectively according to the element molar ratio Li to Al to F to Mn =1 (4-x) to 1 to x, wherein x is more than or equal to 0.002 and less than or equal to 0.04;

3. The method of claim 2, wherein the method comprises the following steps: the lithium-containing compound raw material in the step (1) is any one of oxide, fluoride, carbonate, oxalate, acetate and nitrate.

4. The method of claim 2, wherein the method comprises the following steps: in the step (1), the manganese-containing compound raw material is any one of carbonate, oxalate, acetate and nitrate.

5. The method of claim 2, wherein the method comprises the following steps: the fluorine-containing compound raw material in the step (1) is one of lithium fluoride or aluminum fluoride.

6. The method of claim 2, wherein the method comprises the following steps: the aluminum-containing compound raw material in the step (1) is any one of oxide, fluoride, carbonate, oxalate, acetate and nitrate.

7. The method of claim 2, wherein the method comprises the following steps: the firing of step (2) is carried out in an air atmosphere.

8. The method of tetravalent manganese ion doped lithium aluminum fluoride red phosphor of claim 2, which is implemented by the following steps: selecting a lithium-containing compound raw material, an aluminum-containing compound raw material, a fluorine-containing compound raw material and a manganese-containing compound raw material as initial raw materials, and accurately weighing the raw materials according to the element molar ratio of Li to Al to F to Mn =1 (4-x) to 1 to x, wherein x is 0.002, 0.004 and 0 respectively.008, 0.016, 0.024, 0.032, 0.04; respectively weighing three raw materials of lithium fluoride, alumina and manganese carbonate, and controlling the total weight of the mixture to be 20 g; after ball milling and uniform mixing, 20 g of the mixture is put into a corundum crucible, and then the crucible is put into a high-temperature electric furnace; calcining the mixture at 750 ℃ for 7 hours, and cooling the mixture to room temperature along with the furnace to obtain the LiAl with the chemical composition_4-xO₆F:xMn⁴⁺Mn of (2)⁴⁺Ion-doped fluorine-aluminum oxide lithium red fluorescent material;

x-ray diffraction analysis shows that the prepared red fluorescent material is a pure phase of lithium aluminum fluoride oxide, and 280nm, 365nm and 453nm excitation peaks exist in the range of 200-550 nm respectively, wherein the excitation peak at 280 or 365nm is matched with a commercial ultraviolet chip, and the excitation peak at 453nm is matched with a commercial blue chip; under the excitation of 280nm, 365nm and 453nm, red fluorescence with the peak position located at 662nm can be generated, and the spectral region of 625-750nm is covered.