CN107936961B - A kind of high radiation efficiency Mn4+ activated fluoroaluminate red phosphor and preparation method thereof - Google Patents

Abstract

Translated fromChinese

本发明公开了一种高辐射效率的Mn⁴⁺激活氟铝酸盐红色荧光粉及其制备方法。该高辐射效率的Mn⁴⁺激活氟铝酸盐红色荧光粉的化学组成为Rb₃Al_1‑xF₆:xMn⁴⁺，其中，0.001≤x≤0.15。本发明高辐射效率的Mn⁴⁺激活氟铝酸盐红色荧光粉能被紫外光或蓝光有效激发，发射位于600‑650 nm的窄带红光，色纯度高，量子效率为58.6%，适合于暖白光LED应用。本发明采用共沉淀法制备所述高辐射效率的Mn⁴⁺激活氟铝酸盐红色荧光粉，该制备方法简单，周期短，产率高，适于工业大规模生产。

The invention discloses a Mn⁴⁺ activated fluoroaluminate red fluorescent powder with high radiation efficiency and a preparation method thereof. The chemical composition of the high radiation efficiency Mn⁴⁺ activated fluoroaluminate red phosphor is Rb₃ Al_1-x F₆ :xMn⁴⁺ , where 0.001≤x≤0.15. The high radiation efficiency Mn⁴⁺ activated fluoroaluminate red fluorescent powder of the present invention can be effectively excited by ultraviolet light or blue light, emits narrow-band red light at 600-650 nm, has high color purity, and has a quantum efficiency of 58.6%, which is suitable for warm White LED applications. The present invention adopts the co-precipitation method to prepare the Mn⁴⁺ activated fluoroaluminate red phosphor with high radiation efficiency, the preparation method is simple, the cycle is short, the yield is high, and it is suitable for industrial large-scale production.

Description

Mn with high radiation efficiency4+Activated fluoroaluminate red fluorescent powder and preparation method thereof

Technical Field

The invention relates to the technical field of preparation of red fluorescent powder for white light LEDs, in particular to Mn⁴⁺Activated fluoroaluminate red fluorescent powder and a preparation method thereof.

Technical Field

White light diodes (WLEDs) have become the fourth generation of illumination light sources due to their advantages of high light efficiency, low power consumption, long lifetime, small size, and the like, and are widely used in many fields such as illumination, backlight display, and the like. At present, the main realization mode of commercial white light LED is to adopt a GaN-based blue light LED chip to excite yellow fluorescent powder Y₃Al₅O₁₂:Ce³⁺(YAG:Ce³⁺) White light is obtained by mixing the light of the blue and the yellow. However, since YAG is Ce³⁺The red light component in the phosphor is insufficient, which results in higher color temperature of the obtained white light (>4500K) Low color rendering index (<80) And the color reducibility is poor, so that the application of the color-reducing agent in the aspects of indoor or medical illumination and the like is limited. In order to solve the problem, a proper red light material is added into the white light LED device to complement the red light component of the white light LED device, so that the color rendering index and the color temperature can be effectively improved. At present, the red fluorescent powder for white light LED with better performance is mainly a nitride material doped with rare earth ions, such as CaAlSiN₃:Eu²⁺，MSiN₂:Eu²⁺(M ═ Ca, Sr, Ba, Mg) and M₂Si₅N₈:Eu²⁺(M ═ Ca, Sr, Ba), and the like. The nitride red light materials can effectively reduce the color temperature of a white light LED device and improve the color rendering index. However, this class of materials exhibits broadband emission, with a substantial portion of the emission spectrum in the deep red, where the human eye is insensitive (>650nm) region, the lumen efficiency of the white LED device is greatly reduced. In addition, the nitride red phosphor is generally required to be prepared under high temperature and high pressure conditions, which are harsh and high in production cost. Therefore, there is still a need to develop a high-efficiency red phosphor with narrow-band red light emission, simple preparation method, mild conditions and low cost to improve the device efficiency and light color quality of the white LED.

Transition metal Mn⁴⁺Ion-doped fluorides have excellent luminescence properties: the red fluorescent powder has broadband absorption in ultraviolet and blue light regions and strong narrow-band emission near 630nm, and is considered as an ideal red fluorescent powder for a white light LED. In 1968, U.S. patent (U.S. patent,1971,3576756) disclosed K₂SiF₆:Mn⁴⁺， K₂TiF₆:Mn⁴⁺Red light fluorescent powder. Further, in 2010, K was assigned by GE, Setler et al, USA₂TiF₆: Mn⁴⁺And (Sr, Ca)₃(Al,Si)O₄(F,O):Ce³⁺The combination of the fluorescent powder and the blue light chip successfully develops the warm white LED with the luminous efficiency higher than 80lm/W, the color temperature of 3088K and the color rendering index of 90. This one-fruit causes Mn⁴⁺Doped fluoride Red powder A₂XF₆(A＝Na,K,Rb,Cs；X＝Ge，Si，Ti，Zr),AMNF₆(M ═ Mg, Zn, Ba, Sr, Ca; N ═ Al, Ga, In) (U.S. patent,2010,7847309; CN 102827601A) was studied hot. However, the preparation method of the material is to dissolve the raw materials in a large amount of high-concentration hydrofluoric acid, and then heat, volatilize and co-crystallize to obtain the product. In the preparation process, a large amount of toxic HF aqueous solution is consumed, and meanwhile, the reaction process is difficult to control, the yield is low, and the method is not suitable for industrial production. Chinese patent CN103275711A invented BaTiF prepared by hydrothermal method₆:Mn⁴⁺The red light material is prepared by reaction at 180 ℃ by using hydrofluoric acid as a solvent. Compared with the foregoingThe above method, which uses a reduced amount of hydrofluoric acid, but has Mn⁴⁺The valence state change is easy to occur under high temperature and high pressure, the luminous efficiency is low, and the method is still not suitable for industrial large-scale production. Currently, Mn having high luminous efficiency and excellent chemical stability⁴⁺Doped fluoride red materials are still deficient, so that it is necessary to continuously search for new red materials.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide Mn⁴⁺Ion-doped fluoroaluminate red fluorescent powder, in particular to Mn with high radiation efficiency⁴⁺Activating the fluoaluminate red fluorescent powder. The Mn of high radiation efficiency⁴⁺The activated fluoroaluminate red fluorescent powder is in an octahedral granular shape, has a smooth surface and high crystallinity, can be efficiently excited by ultraviolet light and blue light to generate efficient narrow-band red light emission, is suitable for improving the color rendering performance of the conventional white light LED and promotes the application of the white light LED in the fields of illumination and display.

The invention also aims to provide the Mn with high radiation efficiency⁴⁺A preparation method of activated fluoroaluminate red fluorescent powder. The invention adopts a coprecipitation method to prepare the Mn with high radiation efficiency⁴⁺The preparation method is simple, short in period and high in yield, and is suitable for industrial large-scale production.

The purpose of the invention is realized by the following scheme.

Mn with high radiation efficiency⁴⁺The chemical composition of the activated fluoroaluminate red fluorescent powder is Rb₃Al_1-xF₆:xMn⁴⁺Wherein x is 0.001-0.15, preferably 0.001-0.1; wherein the Mn of high radiation efficiency⁴⁺Activating fluoroaluminate red phosphor to Rb₃AlF₆As a matrix, Mn⁴⁺Partial substitution of Al as a luminescent central ion³⁺Lattice site, Mn⁴⁺The doping molar concentration is more than or equal to 0.001 and less than or equal to 0.15.

Further, the Mn of high radiation efficiency⁴⁺The activated fluoroaluminate red fluorescent powder can be excited by ultraviolet light and blue light with wave bands of 300-500 nmThe light is effectively excited, high-brightness narrow-band red light emission is generated in the wave band range of 600-650 nm, and the quantum efficiency is 58.6%.

Mn with high radiation efficiency⁴⁺Activated fluoroaluminate red phosphor and commercial yellow phosphor Y₃Al₅O₁₂:Ce³⁺(YAG:Ce³⁺) And the blue light GaN chip is combined to obtain the warm white LED device with low color temperature, high color rendering index and high lumen efficiency.

Preparing Mn with high radiation efficiency according to any one of the above⁴⁺The method for activating the fluoroaluminate red fluorescent powder comprises the following steps:

(1) dissolving an Al source in an HF aqueous solution, stirring until the Al source is completely dissolved, adding an Rb source, continuously stirring, and carrying out reaction heat release to obtain a white turbid solution;

(2) adding the Mn compound into the white turbid solution, continuously stirring, and immediately cooling to obtain a yellow precipitate;

(3) carrying out centrifugal washing and drying on the yellow precipitate by adopting an organic solvent to obtain the Mn with high radiation efficiency⁴⁺Activating the fluoaluminate red fluorescent powder.

Further, in the step (1), the Al source is Al₂O₃Or Al (OH)₃Preferably Al (OH)₃。

Further, in the step (1), the Rb source is RbF or Rb₂CO₃Preferably, RbF.

Further, in the step (1), the Al source and the Rb source are added according to the molar ratio of Al to Rb of 1: 6-1: 13, preferably 1: 8-1: 11.

Further, in the step (1), the concentration of the HF aqueous solution is 20-49 wt%, preferably 30-49 wt%.

Further, in the step (1), the material-liquid ratio of the Al source to the HF aqueous solution is 0.04-0.25 g/mL.

Further, in the step (2), the compound of Mn is K₂MnF₆。

In the step (2), the Mn compound and the Al source are added in a molar ratio of Mn to Al of 0.01:100 to 15:100, preferably 0.5:100 to 5: 100.

Further, in the step (2), the rapid cooling is carried out to 2-5 ℃.

Further, in the steps (1) and (2), the continuous stirring time is 20-40 min.

Further, in the step (3), the organic solvent is acetone or absolute ethyl alcohol, so as to remove residual acid liquor on the surface, preferably acetone.

Further, in the step (3), the number of times of centrifugal washing is 2-4.

Further, in the step (3), the drying temperature is 50-100 ℃, and preferably 60-80 ℃.

Further, in the step (3), the drying time is 5-15 hours, preferably 7-10 hours.

Compared with the prior art, the invention has the following advantages and effects:

(1) the red fluorescent powder can be effectively excited by ultraviolet light or blue light, emits narrow-band red light at 600-650 nm, has 58.6 percent of quantum efficiency and high color purity, and is suitable for warm white LED application;

(2) the red phosphor and the commercial yellow phosphor Y of the invention₃Al₅O₁₂:Ce³⁺(YAG:Ce³⁺) The blue light GaN chip is packaged in a combined manner to obtain a warm white LED device with low color temperature, high color rendering index and high lumen efficiency, and the warm white LED device has wide application prospect in the fields of illumination and backlight source display;

(3) the preparation method is simple, low in temperature, controllable in conditions, short in period, high in yield, easy to popularize and operate and suitable for industrial production.

Drawings

FIG. 1 is Rb as prepared in example 4₃AlF₆:0.1％Mn⁴⁺XRD spectrogram of red phosphor;

FIG. 2 is Rb prepared in example 4₃AlF₆:0.1％Mn⁴⁺The appearance of the red fluorescent powder represents an SEM spectrogram;

FIG. 3 is Rb obtained in example 4₃AlF₆:0.1％Mn⁴⁺Excitation and emission spectrograms of red phosphor;

FIG. 4 is sample Rb prepared in example 6₃AlF₆:3％Mn⁴⁺Quantum efficiency graph of red phosphor;

FIG. 5 is Rb in example 7₃AlF₆:3％Mn⁴⁺Red phosphor and YAG Ce³⁺An electroluminescence spectrogram of a WLED constructed by combining yellow powder and blue light GaN chips.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to specific embodiments and drawings, but the embodiments and the scope of the present invention are not limited thereto.

Example 1

Rb₃AlF₆:0.1％Mn⁴⁺Preparation of red phosphor

0.510g of Al₂O₃Dissolving in 4mL of hydrofluoric acid aqueous solution with the mass fraction of 20 wt.%, stirring until the solution is completely dissolved, adding 3.134g of RbF, stirring uniformly, and adding 0.001g K₂MnF₆Stirring the powder at room temperature for 30min, cooling to 2 deg.C to obtain light yellow precipitate, centrifuging with acetone for 3 times, and oven drying at 70 deg.C for 10 hr to obtain Rb₃AlF₆:0.1％Mn⁴⁺And (4) red fluorescent powder.

Example 2

Rb₃AlF₆:0.1％Mn⁴⁺Preparation of red phosphor

0.390g of Al (OH)₃Dissolving in 4mL of hydrofluoric acid aqueous solution with the mass fraction of 30 wt.%, stirring until the hydrofluoric acid aqueous solution is completely dissolved, then adding 3.134g of RbF, stirring uniformly, and then adding 0.001g K₂MnF₆Stirring the powder at room temperature for 30min, cooling to 2 deg.C to obtain light yellow precipitate, centrifuging with acetone for 2 times, and oven drying at 70 deg.C for 10 hr to obtain Rb₃AlF₆:0.1％Mn⁴⁺And (4) red fluorescent powder.

Example 3

Rb₃AlF₆:0.1％Mn⁴⁺Preparation of red phosphor

0.390g of Al (OH)₃Dissolving in 8mL hydrofluoric acid water solution with the mass fraction of 49 wt.%, stirring until the solution is completely dissolved, and adding 6.930g Rb₂CO₃Stirring, adding 0.001g K₂MnF₆Stirring the powder at room temperature for 30min, cooling to 2 deg.C to obtain light yellow precipitate, centrifuging with acetone for 3 times, and oven drying at 70 deg.C for 10 hr to obtain Rb₃AlF₆:0.1％Mn⁴⁺And (4) red fluorescent powder.

Example 4

Rb₃AlF₆:0.1％Mn⁴⁺Preparation of red phosphor

0.390g of Al (OH)₃Dissolving in 4mL hydrofluoric acid water solution with the mass fraction of 49 wt.%, stirring until the hydrofluoric acid water solution is completely dissolved, adding 5.746g RbF, stirring uniformly, and adding 0.001g K₂MnF₆Stirring the powder at room temperature for 30min, cooling to 2 deg.C to obtain light yellow precipitate, centrifuging with acetone for 3 times, and oven drying at 70 deg.C for 10 hr to obtain Rb₃AlF₆:0.1％Mn⁴⁺And (4) red fluorescent powder.

FIG. 1 is an XRD spectrum of the prepared phosphor, and as can be seen from FIG. 1, XRD diffraction peaks of the prepared phosphor are consistent with those of standard card JCPDS No.52-1361, which indicates that the prepared sample is pure phase;

prepared Rb₃AlF₆:0.1％Mn⁴⁺The appearance characterization SEM spectrogram of the red fluorescent powder is shown in figure 2, and as can be seen from figure 2, the prepared fluorescent powder is in an octahedral granular shape, has a smooth surface and high crystallinity.

FIG. 3 is the Rb prepared₃AlF₆:0.1％Mn⁴⁺The excitation and emission spectra of the red phosphor are shown in FIG. 3. the excitation spectrum of the prepared phosphor consists of two broad bands of 360nm and 466nm, wherein the strongest excitation band is at 466 nm; the narrow-band emission spectrum is at 600-650 nm, with the strongest emission at 628 nm.

Example 5

Rb₃AlF₆:0.1％Mn⁴⁺Preparation of red phosphor

0.390g of Al (OH)₃Dissolved in 4mL of a solutionAdding 49 wt.% hydrofluoric acid aqueous solution, stirring to dissolve completely, adding 6.790g RbF, stirring, and adding 0.001g K₂MnF₆Stirring the powder at room temperature for 30min, cooling to 2 deg.C to obtain light yellow precipitate, centrifuging with acetone for 4 times, and oven drying at 70 deg.C for 10 hr to obtain Rb₃AlF₆:0.1％Mn⁴⁺And (4) red fluorescent powder.

Example 6

According to the synthesis scheme of example 4, starting material K was varied₂MnF₆In different amounts, to prepare different Mn⁴⁺Doping concentration of Rb₃Al_1-xF₆:xMn⁴⁺The red phosphor was prepared under the same conditions as in Table 1 below.

TABLE 1 Rb₃Al_1-x F₆:xMn⁴⁺Raw material dosage for preparing red fluorescent powder

By measuring samples 1-6 in Table 1, it was found that sample Rb₃AlF₆:3％Mn⁴⁺Exhibits the strongest luminescence.

FIG. 4 is sample Rb₃AlF₆:3％Mn⁴⁺FIG. 4 shows the fluorescence quantum efficiency of the phosphor, and sample Rb₃AlF₆:3％Mn⁴⁺The fluorescence quantum efficiency of (a) was 58.6%.

Example 7

Rb₃AlF₆:3.0％Mn⁴⁺Red phosphor packaged LED

0.15g of (A + B) paste, 0.015g of YAG: Ce³⁺Yellow phosphor and 0.038g Rb₃AlF₆:3％Mn⁴⁺Mixing red phosphor powder, coating on blue light GaN chip, drying at 60 deg.C for 30min in vacuum drying oven, and transferring to ovenDrying at 120 deg.C for 4 hr.

FIG. 5 shows the electroluminescence spectrum of a packaged LED device under a drive current of 20mA, the color temperature is 3255K, the display index is 90.1, the lumen efficiency is 157.42lm/W, the color coordinates are (0.4203,0.3986), the device falls in a warm white light region, and the device has extremely high commercial application value.

The above examples are only preferred embodiments of the present invention, which are intended to be illustrative and not limiting, and those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention.

Claims (9)

1. Mn with high radiation efficiency⁴⁺Preparation method of activated fluoroaluminate red fluorescent powder, and Mn⁴⁺The chemical composition of the activated fluoroaluminate red fluorescent powder is as follows: rb₃Al_1-xF₆:xMn⁴⁺Wherein x is more than or equal to 0.001 and less than or equal to 0.15, and is characterized by comprising the following steps:

(1) dissolving an Al source in an HF aqueous solution, stirring until the Al source is completely dissolved, adding an Rb source, and continuously stirring to obtain a white turbid solution;

(2) adding the Mn compound into the white turbid solution, continuously stirring, and immediately cooling to obtain a yellow precipitate;

(3) carrying out centrifugal washing and drying on the yellow precipitate by adopting an organic solvent to obtain the Mn with high radiation efficiency⁴⁺Activating the fluoaluminate red fluorescent powder.

2. The method according to claim 1, wherein the Mn is one having a high radiation efficiency⁴⁺The activated fluoroaluminate red fluorescent powder can be effectively excited by ultraviolet light and blue light with wave bands of 300-500 nm, high-brightness narrow-band red light emission is generated within the wave band range of 600-650 nm, and the quantum efficiency is 58.6%.

3. The production method according to claim 1, wherein in the step (1), the Al source is Al₂O₃Or Al (OH)₃(ii) a The above-mentionedThe Rb source is RbF or Rb₂CO₃(ii) a The Al source and the Rb source are added according to the molar ratio of Al to Rb of 1: 6-1: 13.

4. The preparation method according to claim 1, wherein in the step (1), the mass concentration of the HF aqueous solution is 20-49 wt%; the material-liquid ratio of the Al source to the HF aqueous solution is 0.04-0.25 g/mL.

5. The method according to claim 1, wherein in the step (2), the compound of Mn is K₂MnF₆(ii) a The Mn compound and the Al source are added according to the molar ratio of Mn to Al of 0.01: 100-15: 100.

6. The method according to claim 1, wherein in the step (2), the cooling is performed to 2 to 5 ℃.

7. The preparation method according to claim 1, wherein in the steps (1) and (2), the stirring is continued for 20-40 min.

8. The production method according to claim 1, wherein in the step (3), the organic solvent is acetone or absolute ethyl alcohol; the centrifugal washing frequency is 2-4 times.

9. The method according to any one of claims 1 to 8, wherein in the step (3), the drying is performed at 50 to 100 ℃ for 5 to 15 hours.

Images