CN113444521B

CN113444521B - Red fluorescent powder and light-emitting device with same

Info

Publication number: CN113444521B
Application number: CN202110290128.6A
Authority: CN
Inventors: 刘荣辉; 罗林; 刘元红; 秦少伟; 陈观通; 邵冷冷
Original assignee: Grirem Advanced Materials Co Ltd; Grirem Hi Tech Co Ltd
Current assignee: Grirem Advanced Materials Co Ltd; Grirem Hi Tech Co Ltd
Priority date: 2020-03-24
Filing date: 2021-03-16
Publication date: 2022-05-10
Anticipated expiration: 2041-03-16
Also published as: CN113444521A

Abstract

The invention provides red fluorescent powder and a light-emitting device with the same. The phosphor at least comprises an M element, an A element, a D element and an R element, wherein the M element comprises one or two of Ca, Sr, Ba and Mg, and also comprises one or two of Na and K; the element A comprises Al or Al and Ga, and also comprises one or two of Sc, Y, Lu and La; the D element is one or two selected from O, N and F, and must contain O; the R element is one or two of Mn, Ce and Eu, and must contain Mn; the phosphor has a structure similar to Sr₄Al₁₄O₂₅The same crystal structure. Due to Sc³⁺Has a larger ionic radius than Al³⁺Large ionic radius and doped with Sc³⁺The ions can relieve Mn⁴⁺Lattice distortion caused by ion doping and improvement of Mn⁴⁺Thereby enhancing Mn⁴⁺The light emission intensity of (1). The red fluorescent powder has strong absorption in an ultraviolet-blue light region, and can emit strong narrow-band red light under the excitation of ultraviolet-blue light.

Description

Red fluorescent powder and light-emitting device with same

Technical Field

The invention relates to the field of fluorescent materials, in particular to red fluorescent powder and a light-emitting device with the same.

Background

The white light LED is used as a fourth generation light source, and has the characteristics of high luminous efficiency, long service life, good stability, small volume, environmental friendliness and the like, so that the white light LED is widely applied to the fields of illumination and display. White LEDs have a market share of about 80% in the field of liquid crystal display backlights, and have become the main choice for display backlights.

At present, the mainstream realization mode of the white light LED for display is that a blue light chip is matched with red and green fluorescent powder with narrower half wave width. The color purity and half-wave width of the phosphor become key factors affecting the color gamut coverage of the display. At present, the commercial fluorescent powder systems in the backlight source field are nitrogen oxide green fluorescent powder and fluoride red fluorescent powder. Wherein the red phosphor plays a key role in the display gamut of the device.

With the advancement of semiconductor illumination technology and the pursuit of higher illumination quality by human beings, liquid crystal displays are being developed toward higher color reproduction and wide color gamut display in the display field. In order to improve the color gamut coverage of the liquid crystal display, the emission wavelength of the red phosphor is required to be longer, and the color coordinate is required to be closer to the deep red region. In the field of illumination, white light LED light sources have been developed from the initial pure pursuit of "high color rendering and high brightness" to the achievement of "high quality" considering performance parameters of light sources such as safety, health, color reduction, saturation, spectrum continuity and the like, and even the pursuit of full-spectrum healthy illumination similar to sunlight, and the development of efficient far-red fluorescent powder matched with the white light LED light sources is urgently needed. Fluoride red has been successfully used for wide color gamut display and high-efficiency full-spectrum illumination, but the poor weather resistance of the fluorescent powder of the system becomes a big bottleneck preventing the wide application of the fluorescent powder, and the Mn at the luminescent center in the fluoride red fluorescent powder⁴⁺In a stable crystal field environment and its special 3d³The electronic structure makes it difficult to directly regulate and control the emission wavelength of the fluoride system fluorescent powder to move towards the long wave direction. The south China university invents a novel aluminate red fluorescent powder, the emission wavelength of which is 652nm, the color coordinate is x which is 0.722, and y which is 0.278. Compared with the current commercial fluoride system, the aluminate red fluorescent powder has higher emission wavelengthLong, the color coordinate is also closer to the deep red region. Reference may be made in particular to patent document CN 102732250A. Chen Lei et al report that the current light-emitting efficiency of the phosphor is very low, refer to non-patent Materials Research Bulletin 60(2014) 604-. The excitation intensity of the system in a blue light region can be improved by the Cao Yongpi et al through a Na/Mn codoping mode, and the luminescence can be enhanced, and the specific reference can be made to the publication No. CN 105602556A.

However, the luminous intensity of the aluminate red phosphor reported in the above patent or literature is still low, and cannot meet the practical application requirements, thereby limiting further applications in the liquid crystal display field and high-quality illumination field.

Disclosure of Invention

The invention mainly aims to provide red fluorescent powder and a light-emitting device with the same, and solves the problems of low luminous efficiency of the red fluorescent powder and low luminous color gamut of the light-emitting device through technical breakthrough.

In order to achieve the above object, in one aspect of the present invention, a red phosphor is provided, which has a composition including at least an M element, an a element, a D element, and an R element, wherein the M element includes one or two of Ca, Sr, Ba, and Mg; the element A comprises Al or Al and Ga, and also comprises one or two of Sc, Y, Lu and La; the D element is one or two selected from O, N and F, and must contain O; the R element comprises one or two of Mn, Ce and Eu, and must contain Mn; the phosphor has a structure similar to Sr₄Al₁₄O₂₅The same crystal structure. When the element A is Al and Ga, compared with the element A which is Al, the raw material of the Ga source has certain fluxing property in the sintering process, so that the material has better crystal morphology, and higher luminous intensity is brought.

Further, the M element also contains one or two of Na and K. Na (Na)⁺Or K⁺Or Na⁺And K⁺The incorporation of (A) is advantageous for maintaining the charge balance of the system, Na⁺-Mn⁴⁺Bond substituted Sr²⁺-Al³⁺Bond, change Mn⁴⁺The crystal field strength of the crystal solves the problem of Mn⁴⁺Occupying Al³⁺The position is such that the charge imbalance of the system causes the problem of low luminous intensity, and the luminous intensity is remarkably enhanced.

Further, the composition formula of the fluorescent powder is M₄A_x-aD_yaR, wherein the parameters a, x and y satisfy the following conditions: a is more than 0.001 and less than or equal to 1, x is more than or equal to 12 and less than or equal to 16, and y is more than or equal to 24 and less than or equal to 26, and the proportion is satisfied to obtain a purer crystal structure.

Further, the element M is Sr, the element A comprises Al, and also comprises Sc and/or Lu, the element D is O, and the element R is Mn.

Furthermore, the mole percentage of Sc element in the element A is n, and n is more than or equal to 0.01 percent and less than or equal to 35 percent.

The red luminescent material of the invention has the structure of₄Al₁₄O₂₅The same crystal structure. Sr (strontium)₄Al₁₄O₂₅:Mn⁴⁺The system has an octahedral structure with a spatial point group of pma (51). Sr₄Al₁₄O₂₅The three-dimensional network structure is formed by a layer of octahedron (AlO)₆) And two layers of tetrahedrons (AlO)₄) Composition of in Sr₄Al₁₄O₂₅In the middle, there are two Sr lattice sites, six Al lattice sites and eight O lattice sites, Mn⁴⁺Occupies octahedron (AlO)₆) And medium Al lattice site. Mn preferred for the red phosphor of the present invention⁴⁺The activated red fluorescent powder has strong absorption at 400nm-480nm, is particularly suitable for being excited by a blue chip, emits red light with a main peak position at 650nm +/-1 nm, has a narrow half-peak width of about 20nm, and meets the requirements of being excited by blue light and emitting red light in a narrow band.

In red phosphor, due to Mn⁴⁺The ionic radius is less than Al³⁺When Mn is present⁴⁺As substituted Al³⁺Lattice sites cause cell shrinkage, and the lattice distortion caused by such cell shrinkage affects Mn⁴⁺Stability and luminescence properties of (A). When Sc, Y, Lu and La elements are doped, Sc³⁺、Y³⁺、Lu³⁺、La³⁺All of the ionic radii of (A) to (B) are larger than that of Al³⁺Small, so that when one or two of them are substituted for Al³⁺When the lattice position is located, the unit cell will be obtainedSwelling, to a certain extent, relieves the stress caused by Mn⁴⁺Lattice distortion caused by substitution can effectively improve Mn⁴⁺Localized environment in the matrix, thereby enhancing Mn⁴⁺The red fluorescent powder with higher luminous intensity is obtained. Due to the sequence of the ionic radius of Al³⁺＜Sc³⁺＜Lu³⁺＜Y³⁺＜La³⁺Thus, relatively speaking, Sc³⁺Radius closest to Al³⁺Second is Lu³⁺Therefore, the two elements are easier to be dissolved into the crystal lattice in a solid solution way, so that the crystal cell is expanded, and the Mn is reduced⁴⁺Substituted Al³⁺The lattice sites bring about the contraction of the unit cell without causing the inverse expansion of the lattice due to the larger difference in ionic radius and the distortion of the lattice. And the introduction of Sc element is beneficial to the material to obtain a better crystal morphology, and the material has crystal grains with high dispersity and larger size.

Therefore, the element a is preferably Al or Sc. But Sc³⁺The substitution is more than 35%, the crystal structure is changed, and less than 0.01% does not play a role in enhancing luminescence.

The excitation spectrum peak wavelength of the fluorescent powder is 250-500 nm, and the emission wavelength is in a range of 625-670 nm.

The preparation method of the material comprises the steps of accurately weighing oxides, carbonates, nitrates and the like of the M element, the A element, the D element and the R element as raw materials, weighing the raw materials according to respective molecular formulas, and fully mixing and grinding the raw materials in a mortar for 20-100min to obtain a mixture. Heating to 1200-1400 ℃ under the atmosphere conditions of air atmosphere or air/nitrogen and the like, and preserving the heat for 2-10 h. And cooling the furnace to obtain a sintered product, taking out the sintered product, crushing, washing, sieving and drying to obtain the fluorescent powder.

According to another aspect of the present application, there is provided a light emitting device including a phosphor including the above-described red phosphor and an excitation light source.

Further, the phosphor also comprises other phosphors, and the other phosphors comprise (Y, Gd, Lu, Tb)₃(Al,Ga)₅O₁₂:Ce³⁺、β-SiAlON:Eu²⁺、La₃Si₆N₁₁:Ce³⁺、(Ba,Sr)Si₂O₂N₂:Eu²⁺One or more of (a).

The narrow-band red fluorescent powder is combined and packaged with one or more colors of fluorescent powder such as yellow fluorescent powder, green fluorescent powder, yellow-green fluorescent powder, cyan fluorescent powder and the like, and white light emission can be obtained under the excitation of a blue light chip. (Y, Gd, Lu, Tb)₃(Al,Ga)₅O₁₂:Ce³⁺Is yellow or yellow-green phosphor, beta-SiAlON: Eu²⁺Is yellow-green phosphor, La₃Si₆N₁₁:Ce³⁺Is yellow phosphor, (Ba, Sr) Si₂O₂N₂:Eu²⁺Cyan phosphor or cyan-green phosphor.

Compared with the prior art that fluoride red powder and beta-SiAlON are Eu²⁺Green phosphor combination packaged light emitting device, phosphor of the present application and other phosphors, e.g. (Y, Gd, Lu, Tb)₃(Al,Ga)₅O₁₂:Ce³⁺、β-SiAlON:Eu²⁺、La₃Si₆N₁₁:Ce³⁺、(Ba,Sr)Si₂O₂N₂:Eu²⁺The combined use can ensure that the light-emitting device emits white light with high luminous efficiency, high color rendering and low color temperature, and meets the practical application requirements in the fields of wide color gamut display and high-quality illumination.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.

FIG. 1 is an XRD diffraction pattern of phosphors prepared in comparative example, example 1, example 2 and example 3 of the present invention;

FIG. 2 shows excitation spectra of phosphors prepared in comparative example, example 1, example 2 and example 3 of the present invention;

FIG. 3 shows emission spectra of phosphors prepared in comparative example, example 1, example 2 and example 3 of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

Comparative example

According to Sr₄Al_13.99O₂₅0.01Mn in a stoichiometric ratio, accurately weighing SrCO₃(99.9％),Al₂O₃(99.9％),MnCO₃(99.9%) and put in a mortar to be fully mixed and ground for 30min to obtain a mixture. And raising the temperature of the mixture to 1200 ℃ at a heating rate of 10 ℃/min under an air atmosphere, and then preserving the heat at 1200 ℃ for 6 h. And naturally cooling the furnace temperature to room temperature to obtain a sintered product, taking out the sintered product, crushing, washing, sieving and drying to obtain the comparative example fluorescent powder, wherein the relative emission intensity of the comparative example fluorescent powder is 100. Carrying out X-ray scanning on the fluorescent powder to obtain a graph 1, wherein a target material is a Co target, the scanning Bragg angle is 20-80 degrees, and the scanning speed is 5 degrees/min; the fluorescent powder is subjected to fluorescence spectrum test, and an excitation spectrum is obtained with the excitation monitoring wavelength of 650nm and is shown in figure 2. The excitation wavelength was 450nm and the resulting emission spectrum is shown in FIG. 3.

Example 1

According to (Sr)_3.9Na_0.1)(Al_13.93Sc_0.06)O₂₅0.01Mn in a stoichiometric ratio, accurately weighing SrCO₃(99.9％),Al₂O₃(99.9％),Sc₂O₃(99.9％),MnCO₃(99.9％)，Na₂CO₃(99.9%) and put in a mortar to be fully mixed and ground for 30min to obtain a mixture. And (3) heating the mixture to 900 ℃ at the heating rate of 10 ℃/min under the air atmosphere, preserving the heat for 1h, then heating to 1250 ℃, and preserving the heat for 5 h. And (3) naturally cooling the furnace temperature to room temperature to obtain a sintered product, taking out the sintered product, crushing, washing, sieving and drying to obtain the fluorescent powder of the embodiment 1, wherein the relative emission intensity of the fluorescent powder is 197. Carrying out X-ray scanning on the fluorescent powder to obtain a graph 1, wherein a target material is a Co target, the scanning Bragg angle is 20-80 degrees, and the scanning speed is 5 degrees/min; the fluorescent powder is subjected to fluorescenceAnd (3) performing optical spectrum test, wherein the excitation monitoring wavelength is 650nm, and the obtained excitation spectrum is shown in figure 2. The excitation wavelength was 450nm and the resulting emission spectrum is shown in FIG. 3.

Example 2

According to (Sr)_3.9Na_0.4)(Al_13.93Sc_0.06)O₂₅0.01Mn in a stoichiometric ratio, accurately weighing SrCO₃(99.9％),Al₂O₃(99.9％),Sc₂O₃(99.9％),MnCO₃(99.9％)，Na₂CO₃(99.9%) and put in a mortar to be fully mixed and ground for 30min to obtain a mixture. And (3) heating the mixture to 900 ℃ at the heating rate of 10 ℃/min under the air atmosphere, preserving the heat for 1h, then heating to 1200 ℃, and preserving the heat for 4 h. And (3) naturally cooling the furnace temperature to room temperature to obtain a sintered product, taking out the sintered product, crushing, washing, sieving and drying to obtain the fluorescent powder of the embodiment 2, wherein the relative emission intensity of the fluorescent powder is 200. Carrying out X-ray scanning on the fluorescent powder to obtain a graph 1, wherein a target material is a Co target, the scanning Bragg angle is 20-80 degrees, and the scanning speed is 5 degrees/min; the fluorescent powder was subjected to fluorescence spectrum test, and the excitation spectrum was obtained at a monitoring wavelength of 650nm and shown in FIG. 2. The excitation wavelength was 450nm and the resulting emission spectrum is shown in FIG. 3.

Example 3

According to (Sr)_3.4Na_0.6)(Al_13.93Sc_0.06)O₂₅0.01Mn in a stoichiometric ratio, accurately weighing SrCO₃(99.9％),Al₂O₃(99.9％),Sc₂O₃(99.9％),MnCO₃(99.9％)，Na₂CO₃(99.9%) and put in a mortar to be fully mixed and ground for 30min to obtain a mixture. Heating the mixture to 900 ℃ at a heating rate of 10 ℃/min under an air atmosphere, preserving heat for 1h, then heating to 1350 ℃, and preserving heat for 5 h. And (3) naturally cooling the furnace temperature to room temperature to obtain a sintered product, taking out the sintered product, crushing, washing, sieving and drying to obtain the fluorescent powder of the embodiment 3, wherein the relative emission intensity of the fluorescent powder is 244. Carrying out X-ray scanning on the fluorescent powder to obtain a graph 1, wherein a target material is a Co target, the scanning Bragg angle is 20-80 degrees, and the scanning speed is 5 degrees/min; to the sameThe fluorescent powder is subjected to fluorescence spectrum test, and the excitation spectrum obtained by monitoring the wavelength at 650nm is shown in figure 2. The excitation wavelength was 450nm and the resulting emission spectrum is shown in FIG. 3.

Examples 4 to 40

According to the stoichiometric proportion of the fluorescent powder in the tables 1-5, the corresponding raw materials of the hydrochloride and the oxide are accurately weighed and are placed in a mortar to be fully mixed and ground to obtain a mixture. Heating the mixture to 1200-1400 ℃ in air atmosphere, and keeping the temperature for 2-10 h. And obtaining a sintered product after the furnace temperature is naturally reduced to the room temperature, taking out the sintered product, crushing, washing, sieving and drying the sintered product, obtaining the fluorescent powder corresponding to the embodiments 4-40 according to corresponding sintering parameters, and performing a fluorescence spectrum test on the fluorescent powder, wherein the monitoring wavelength is 650nm, the emission monitoring wavelength is 450nm, and the luminous intensity is specifically shown in tables 1-5.

The composition and luminescence of the raw materials in comparative example and examples 1 to 40 are shown in tables 1 to 5 below.

TABLE 1 examples 1-10

Table 2 examples 11 to 22

TABLE 3 examples 23 to 28

TABLE 4 examples 29 to 36

TABLE 5 examples 37-40

Since numerous limitations are included, no undue redundancy is to be inferred, and equivalents, modifications, and equivalents in the patent claims should be included within the scope and boundaries of the present invention.

As shown in FIG. 1, the XRD diffraction pattern of the invention is shown, and Sr is arranged at the lowest part₄Al₁₄O₂₅Standard card (PDF # 74-1810). The diffraction patterns of example 1, example 2 and example 3 were as described above. As can be seen from the figure, the main phase of the sample prepared by the invention is Sr₄Al₁₄O₂₅. As can be seen from the above description, the above-described embodiments of the present invention achieve the following technical effects:

as can be seen from Table 1, Mn is associated with the luminescence center in a certain range for the red phosphor⁴⁺Increasing the luminous intensity gradually over the optimum Mn⁴⁺Concentration, the concentration quenching luminescence intensity is gradually reduced due to the increase of luminescence center ions; from examples 1 to 10, over Na⁺Ions and Sc³⁺The luminous intensity of the light-emitting diode can be increased by 48 to 100 percent by ion codoping; in addition, the lattice distortion degree can be improved by Y, Lu and La except Sc element, so that the luminous intensity is increased, the Sc element has the best addition effect, and the luminous intensity is increased most.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims

1. A red phosphor is characterized in that the composition of the phosphor at least comprises M element, A element, D element and R element, whereinThe M element comprises one or two of Ca, Sr, Ba and Mg; the element A comprises Al or Al and Ga, and also comprises one or two of Sc, Y, Lu and La; the D element is one or two selected from O, N and F, and must contain O; the R element comprises one or two of Mn, Ce and Eu, and must contain Mn; the composition formula of the fluorescent powder is M₄A_x-aD_yaR, wherein the parameters a, x and y satisfy the following conditions: a is more than 0.001 and less than or equal to 1, x is more than or equal to 12 and less than or equal to 16, and y is more than or equal to 24 and less than or equal to 26; the phosphor has a structure similar to Sr₄Al ₁₄O₂₅The same crystal structure.

2. A red phosphor according to claim 1, wherein the M element further contains one or both of Na and K.

3. The red phosphor of claim 2, wherein the M element contains Na, wherein Na is present in an amount of b in a molar ratio of 2.5% to 25%.

4. The red phosphor of claim 1, wherein the M element is Sr, the A element comprises Al, and further comprises Sc and/or Lu, the D element is O, and the R element is Mn.

5. A red phosphor according to claim 4, wherein the element A is Al or Sc.

6. The red phosphor of claim 5, wherein the mole percentage of Sc element in A element is n, and n is 0.01% to 35%.

7. A light-emitting device comprising a phosphor and an excitation light source, wherein the phosphor comprises the red phosphor according to any one of claims 1 to 6.

8. The light-emitting device of claim 7, wherein the phosphor further comprises additional phosphorA light powder, the other fluorescent powder comprises (Y, Gd, Lu, Tb)₃(Al,Ga)₅O₁₂:Ce³⁺、β-SiAlON:Eu²⁺、La₃Si₆N₁₁:Ce³⁺、(Ba,Sr)Si₂O₂N₂:Eu²⁺One or more of (a).