CN110791291A

CN110791291A - Synthesis method of phosphosilicate white light emitting fluorescent powder

Info

Publication number: CN110791291A
Application number: CN201910934689.8A
Authority: CN
Inventors: 莫福旺; 汤泉; 姜微; 凌俞; 岑雨涓; 梁海彪; 吴铭辉; 沈车
Original assignee: Hezhou University
Current assignee: Hezhou University
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2020-02-14

Abstract

The invention provides a method for synthesizing phosphosilicate white light-emitting fluorescent powder, which comprises the steps of firstly weighing corresponding oxides, carbonates, phosphates and fluorides, mixing the weighed substances, uniformly grinding the substances in an agate mortar, then placing the ground substances in a corundum crucible, placing the corundum crucible in a muffle furnace, presintering the corundum crucible for 4 hours at 600 ℃ under the air condition, cooling the corundum crucible to room temperature, taking out the corundum crucible, placing the corundum crucible in a 20% H atmosphere, grinding the corundum crucible, and finally placing the corundum crucible in a kiln₂+80％N₂Roasting for 3-4 hours at the temperature of 1000-1100 ℃ in the atmosphere, naturally cooling to room temperature, taking out and grinding uniformly to obtain white powder. The white light emitting fluorescent powder prepared by the method overcomes the defects of poor color rendering property and narrow excitation wavelength of the traditional fluorescent powder, and utilizes single substrate co-doped Ce³⁺/Mn²⁺The method prepares the phosphosilicate white light emitting fluorescent powder in a wide ultraviolet excitation range through energy transfer among ions.

Description

Synthesis method of phosphosilicate white light emitting fluorescent powder

Technical Field

The invention belongs to the field of powder material synthesis, and particularly relates to a method for synthesizing fluorescent powder by a reducing atmosphere high-temperature solid-phase reaction.

Background

The LED green lighting source can directly convert electric energy into light energy, greatly improves the efficiency, has great advantage in the aspect of saving a large amount of electric energy, and is more and more popular among people. To realize the popularization of LED lighting, research and development of fluorescent conversion materials are important. The matching of the chip and the fluorescent material is an important factor influencing the electrical and optical properties of the product and the stability of the device. For the selection of the fluorescent material, the excitation spectrum, the emission spectrum, the light-induced conversion efficiency, the particle size distribution, the light attenuation and other aspects of the fluorescent material are comprehensively considered, and the characteristic requirements of the product are also considered, so that the suitable material and the suitable using amount are found, and the various aspects of the performance of the white light LED product are improved. Most white light LED devices today combine the LED blue light chip into Y₃Al₅O₁₂:Ce³⁺The fluorescent powder is obtained by combining an ultraviolet/near ultraviolet LED chip and red, green and blue three-primary-color fluorescent powder, in the method of combining the blue light chip and the YAG yellow fluorescent powder, the luminous property of the blue chip depends on current, and when the current fluctuates, the blue light of the LED and the yellow light of the fluorescent powder cannot be matched at the same time, so that the white light quality is influenced. For a three-primary-color white LED, the light color and the light emitting efficiency of the device are seriously affected by the maldistribution caused by the difference of the size, density, thermal characteristics and structure of the phosphors of each color. Therefore, the method for synthesizing the single matrix composite oxide matrix with different coordination lattice positions, enabling the rare earth active ions to occupy different lattice positions through the combination of different rare earth ions, realizing red-green-blue three-primary-color luminescence, realizing the continuous adjustment of the color of emitted light, and covering the whole visible light wave band has important significance for preparing the white light LED device with high efficiency and stable performance.

Halophosphate AB₃Re(PO₄)₃X (A and B are respectively monovalent and divalent alkaline earth ions, and Re is trivalent rare earth ion) belongs to a tetrahedral rigid structure, has good chemical and thermal stability, and has potential as a good luminescent material matrix. When the matrix is doped with different alkaline earth metal ions B²⁺When oxygen atoms and halogen atoms are coordinated with rare earth ions in the matrix, i.e. there are chemical bonds of Re-O-B and Re-X-B, the alkaline earth metal B passing through Re³⁺,O^2-,X^-Pair of indirect charge transfer Re³⁺The effect is realized, and along with the difference of the radius and the electronegativity of the doped ions, the electron cloud among the covalent bonds shifts through the co-doping of the luminescent ions and the adjustment of the matrix structure, so that the control of the luminescent color and the color temperature adjustment are realized. Meanwhile, on the basis of constructing a matrix with a special structure, a specific coordination environment and a local microenvironment given to rare earth ions by the matrix are utilized, and the construction of energy transfer among rare earth is utilized to adjust a light-emitting process and regulate excitation and emission of a light-emitting material.

Therefore, combining the above factors, Na is synthesized by high temperature solid phase reaction₂Sr_4.85Gd_2.95(PO₄)₅(SiO₄)F₂:xCe³ ⁺,yMn²⁺(x, y tunable) single matrix white light emitting phosphor (Na)₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂Hereinafter abbreviated as NSGPSF), the transition from single light emission to white light emission is realized through energy transfer of doped luminescent ions and fine adjustment of a matrix structure.

Disclosure of Invention

The invention aims to overcome the defects of insufficient pink component, easy light color drift and short excitation range of the existing fluorescent powder, and provides a method for preparing phosphosilicate white light emitting fluorescent powder by using a high-temperature solid phase method.

In order to achieve the purpose of the invention, the invention provides a synthesis method of phosphosilicate white light emitting fluorescent powder, which is characterized by comprising the following steps:

1. a method for synthesizing phosphosilicate white light emitting fluorescent powder is characterized by comprising the following steps:

a. weighing a certain amount of analytically pure Na₂CO₃、Sr₂CO₃、Gd₂O₃、NH₄H₂PO₄、SiO₂、SrF₂、CeO₂、MnCO₃The medicine is evenly mixed in an agate mortar and ground for a certain time30 min; putting the uniformly ground sample into a corundum crucible, putting the crucible into a muffle furnace, and presintering for 4 hours at 600 ℃ in an air atmosphere to perform precursor treatment to obtain a precursor mixed oxide;

b. and taking out the precursor mixed oxide, and putting the precursor mixed oxide into an agate mortar for uniformly grinding again for 10 minutes. And placing the ground precursor into a corundum crucible, placing the corundum crucible into a tubular furnace, reacting for 3-4 h at 1000-1100 ℃ in a reducing atmosphere, cooling to room temperature, taking out and grinding uniformly to obtain the phosphosilicate white light emitting fluorescent powder.

Preferably, the amount of analytically pure Na described in step a₂CO₃、Sr₂CO₃、Gd₂O₃、NH₄H₂PO₄、SiO₂、SrF₂、CeO₂、MnCO₃The mass ratio of (A) to (B) is as follows: 0.1060: (0.5684-0.5905): 0.5347: 0.5752: 0.0601: 0.1256: (0-0.0086): (0-0.0172).

Preferably, the precursor treatment is carried out in the step a by pre-baking at 600 ℃ for 4 hours, and the heating system is 10min → 450 ℃ → 20min → 450 ℃ → 15min → 600 ℃ → 240min → 600 ℃ → 600 → finish.

Preferably, the reducing atmosphere in step b is 20% H₂+80％N₂And (4) reducing atmosphere.

A method for synthesizing phosphosilicate white light emitting fluorescent powder is characterized in that the phosphosilicate white light emitting fluorescent powder is white powder.

The invention has the beneficial effects that: the white light emitting fluorescent powder prepared by the method overcomes the defects of poor color rendering property and narrow excitation wavelength of the traditional fluorescent powder, and co-doped Ce is utilized³⁺/Mn²⁺The method prepares the phosphosilicate white light emitting fluorescent powder in a wide ultraviolet excitation range through energy transfer among ions. When the ultraviolet light of 300nm is used as the excitation wavelength to irradiate Na₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂:0.05Ce³⁺,xMn²⁺In the case of a phosphor, the emission spectrum is obtained with 398nm and 560nm as the centerTwo bands with larger intensity difference are respectively attributed to Ce³⁺5d → 4f and Mn²⁺The transition light emission of 4T1(4G) → 6A1(6S) of Ce³⁺As a sensitizer, the energy of ultraviolet light in the ground state is absorbed to the excited state and then efficiently transferred to the activator Mn²⁺4T of₁Energy level. Without changing Ce³⁺Doping content of Mn to gradually increase Mn²⁺In the process of doping content, Mn is increased²⁺Emission intensity of (1), and corresponding attenuation of Ce³⁺The intensity of the emission peak is gradually reduced from the rise to the fall of the spectrum and the integration of the light color, so that the CIE value of the fluorescent powder gradually approaches to the standard white light.

Drawings

FIG. 1 is Na₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂Single doping of Ce³⁺Single doping of Mn²⁺Excitation and emission spectra of the phosphor.

FIG. 2 is Na₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂:Ce³⁺,Mn²⁺XRD pattern of (a).

FIG. 3 is Na₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂:0.05Ce³⁺,xMn²⁺The emission spectrum of (a).

FIG. 4 is Na₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂:0.05Ce³⁺,xMn²⁺The CIE diagram of (a).

Detailed Description

The following examples are only a part of the present invention, and not all of them. While the embodiments of the present invention described and illustrated herein are generally susceptible to being arranged and designed in a variety of different configurations, the detailed description of the embodiments of the invention provided below is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention, and all other embodiments that can be derived by one skilled in the art based on the embodiments of the present invention without making an inventive contribution fall within the scope of the present invention.

Examples 1 to 4

Weighing the medicines according to the raw material proportion in the table 1, uniformly mixing the medicines in an agate mortar, and grinding for 30 min; putting the uniformly ground sample into a corundum crucible, putting the crucible into a muffle furnace, pre-burning for 4 hours at 600 ℃ in an air atmosphere condition to perform precursor treatment, wherein the heating system is 10min → 450 ℃ → 20min → 450 ℃ → 15min → 600 ℃ → 240min → 600 ℃ → end to obtain a precursor mixed oxide; and taking out the precursor mixed oxide, and putting the precursor mixed oxide into an agate mortar for uniformly grinding again for 10 minutes. And (2) placing the ground precursor into a corundum crucible, placing the corundum crucible into a tubular furnace, reacting for 4 hours at 1000 ℃ in a reducing atmosphere, (wherein the temperature is 1000-1100 ℃, the reaction time is 3-4 hours, for comparison, the temperature is uniformly 1000 ℃ and the reaction time is 4 hours in the examples 1-4), cooling to room temperature, taking out, and grinding uniformly to obtain the phosphosilicate white light emitting fluorescent powder.

TABLE 1 raw material ratio

The samples of examples 1 and 2 were placed in the solid sample cell of a Hitachi F2500 fluorometer and tested for fluorescence properties after flattening. Single doping of Ce³⁺The excitation wavelength of the sample of (1) is 274nm and the emission wavelength is 398 nm; single doping of Mn²⁺The excitation wavelength of the sample is 274nm, the reflection wavelength is 560nm, and the excitation spectrum and the emission spectrum of the single-doped sample can be obtained by respectively testing. As shown in FIG. 1, emission peaks at 398nm and 560nm correspond to Ce, respectively³⁺And Mn²⁺5d → 4f and⁴T₁(⁴G)→⁶A₁(⁶s) transition emission. In the excitation spectrum, the excitation spectra of two ions overlap.

XRD tests are respectively carried out on the samples of the embodiments 1-4, the 2 theta angle range of scanning is set to be 10-70 degrees, and the scanning step length is 10 degrees/min. The data obtained from the test were compared to the standard spectra using the MDI Jade 5.0 software. The influence of different doping amounts on the crystal structure was tested, and the XRD patterns of samples with different doping amounts are shown in FIG. 2.

As can be seen from FIG. 2, the prepared single-doped Ce³⁺Single doping of Mn²⁺Double doping of Ce³⁺,Mn²⁺XRD pattern of the sample (A) and Ca of hexagonal system₄La₆(SiO₄)₆(OH)₂Matching, cell parameter parameters of the crystal

Z＝1，

Ce³⁺Substituted Gd³⁺Lattice site of (C), Mn²⁺Substituted Sr²⁺The lattice site of (1).

Single doping of Ce³⁺The phosphor emits blue light with the strongest peak at 398nm under the excitation of 274nm ultraviolet light, which corresponds to Ce³⁺The 5d → 4f transition, and the strongest position of the excitation spectrum at 200-360nm is at 274nm under the monitoring of 398nm emission. Corresponding to Ce³⁺The 4f → 5d transition. In the single doping of Mn²⁺Has a broad excitation band with the strongest peak at 274nm, and belongs to Mn²⁺-O^2-The single doping of Mn under the excitation of 274nm wavelength²⁺The emission of the phosphor at 560nm belongs to Mn²⁺Is/are as follows⁴T₁(⁴G)→⁶A₁(⁶S) transition emission, which is yellow-orange light emission. The 400-500nm emission peak belongs to the matrix emission peak. Compared with the singly doped Mn²⁺Sample of (2) double-doped with Ce³⁺The excitation spectrum of the sample is then broadened.

Examples 5 to 13

Weighing the medicines according to the raw material proportion in the table 2, uniformly mixing the medicines in an agate mortar, and grinding for 30 min; putting the uniformly ground sample into a corundum crucible, putting the crucible into a muffle furnace, pre-burning for 4 hours at 600 ℃ in an air atmosphere condition to perform precursor treatment, wherein the heating system is 10min → 450 ℃ → 20min → 450 ℃ → 15min → 600 ℃ → 240min → 600 ℃ → end to obtain a precursor mixed oxide; and taking out the precursor mixed oxide, and putting the precursor mixed oxide into an agate mortar for uniformly grinding again for 10 minutes. And (2) placing the ground precursor into a corundum crucible, placing the corundum crucible into a tubular furnace, reacting for 4 hours at 1000 ℃ in a reducing atmosphere (wherein the temperature is 1000-1100 ℃, the reaction time is 3-4 hours, for comparison, the temperature is uniformly 1000 ℃ and the reaction time is 4 hours in examples 1-4), cooling to room temperature, taking out, and grinding uniformly to obtain the phosphosilicate white light emitting fluorescent powder.

TABLE 2 raw material proportions

Prepared Ce³⁺,Mn²⁺Codoped fluorescent powder, and the emission spectrum, Na, of the codoped fluorescent powder is tested by taking 300nm as excitation wavelength₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂:0.05Ce³⁺,xMn²⁺The emission spectrum of (a) is shown in fig. 3. Importing the obtained fluorescence emission spectrum data into CIE value calculation software, calculating CIE value of the fluorescent powder as shown in table 3, referring to the data in table 3, importing the data into GoCIE software₂Sr₅Gd₃(PO₄)₅(SiO₄)F₂:0.05Ce³⁺,xMn²⁺The CIE diagram of (a) is shown in fig. 4.

TABLE 3 CIE values of the phosphors

As can be seen from FIG. 3, it was found that Ce passes through³⁺→Mn²⁺The chromaticity of the sample gradually approaches to white light, for Ce³⁺，Mn²⁺The co-doped sample has an excitation peak compared with that of single doped Mn²⁺The excitation peak of the sample is broadened, the excitation wavelength range is widened, the original peak excitation is changed into broad-peak excitation, the strongest excitation peak is shifted from 274nm to 300nm, and the broadening range is 250-350 nm. This range is in accordance with Ce³⁺Is excited and is also suitableMn²⁺Excitation is performed. As can be seen from Table 3 and FIG. 4, Mn is accompanied by Mn²⁺The doping amount is increased, and the colorimetric values of the sample are gradually close to the colorimetric values (0.333 ) of the standard white light, which shows that under the excitation of 300nm ultraviolet light, the fluorescent powder emitting white light can be prepared through co-doping.

Claims

a. weighing a certain amount of analytically pure Na₂CO₃、Sr₂CO₃、Gd₂O₃、NH₄H₂PO₄、SiO₂、SrF₂、CeO₂、MnCO₃Uniformly mixing the medicines in an agate mortar, and grinding for 30 min; putting the uniformly ground sample into a corundum crucible, putting the crucible into a muffle furnace, and presintering for 4 hours at 600 ℃ in an air atmosphere to perform precursor treatment to obtain a precursor mixed oxide;

2. The method of claim 1, wherein the amount of analytically pure Na in step a is selected from the group consisting of Na₂CO₃、Sr₂CO₃、Gd₂O₃、NH₄H₂PO₄、SiO₂、SrF₂、CeO₂、MnCO₃The mass ratio of (A) to (B) is as follows: 0.1060: (0.5684-0.5905): 0.5347: 0.5752: 0.0601: 0.1256: (0-0.0086): (0-0.0172).

3. The method for synthesizing phosphosilicate white-light-emitting phosphor according to claim 1, wherein the pre-baking at 600 ℃ for 4 hours in step a is performed with precursor treatment under a heating schedule of 10min → 450 ℃ → 20min → 450 ℃ → 15min → 600 ℃ → 240min → 600 ℃ → ends.

4. The method of claim 1, wherein the reducing atmosphere in step b is 20% H₂+80％N₂And (4) reducing atmosphere.

5. The method of claim 1, wherein the phosphor is a white powder.