CN103468256A - Fluorescent powder for white-light LED (light-emitting diode) applicable to ultraviolet light and blue light excitation and preparation method thereof - Google Patents

Abstract

The invention relates to a fluorescent powder for white LEDs suitable for excitation by ultraviolet light and blue light and a preparation method thereof. The chemical formula of the phosphor is: M ₈ Al _8-2a Mg _a Si _4+a O ₂₈ :xN ²⁺ ; wherein, M is one or more of Mg, Ca, Sr or Ba; 0<a<4 ; N is Eu, 0.001≤x≤0.10. The invention also provides a method for preparing the fluorescent powder. The reactants are weighed according to the stoichiometric ratio of the chemical formula, mixed evenly; and then fired at 1200-1350° C. for 2-5 hours in a reducing atmosphere to obtain the fluorescent powder. The fluorescent powder has a wide excitation spectrum, an excitation wavelength of 200-500nm, and an emission wavelength of 450nm-700nm, so it is suitable for excitation of ultraviolet light and blue light LEDs, and can be used to prepare white light LEDs with high color rendering index. The manufacturing method of the fluorescent powder is simple and feasible, easy to operate, easy to mass produce, pollution-free and low in cost.

Description

A kind of fluorescent powder for white light LED suitable for ultraviolet light and blue light excitation and preparation method thereof

technical field

The invention relates to a fluorescent powder, in particular to a fluorescent powder for white LEDs suitable for excitation by ultraviolet light and blue light and a preparation method thereof.

Background technique

Due to its energy-saving and environmental protection, long service life, small size, impact resistance and other excellent performances, as well as its huge potential in terms of energy saving and life, white LEDs have shown broad market application value and prospects. White LED devices are more efficient in converting electrical energy than other traditional light sources, which help reduce greenhouse gas emissions, thereby providing us with a cleaner environment. At present, white light LEDs have been applied in many fields such as liquid crystal display backlights, indicator lights, indoor and outdoor lighting, etc. Therefore, white LED is the most promising emerging product in the LED industry, and will become the fourth-generation solid-state lighting source in the 21st century, which has extensive and far-reaching significance for energy saving, environmental protection, and improving people's quality of life.

At present, there are three main schemes for realizing white light LED. One solution is to use yellow-emitting Y ₃ Al ₅ O ₁₂ :Ce ³⁺ (YAG:Ce ³⁺ ) as a phosphor, and coat it on a blue-emitting InGaN chip to form a commercial white LED. The second scheme is to use ultraviolet light-emitting InGaN tube core and phosphor powder that can be effectively excited by ultraviolet light to emit red, green and blue three primary colors to form a white light LED. The third scheme is a white LED prepared by using a single-matrix white light-emitting phosphor. Although the above three schemes can realize white light LEDs, there are few phosphors that can match blue light LEDs, especially phosphors that can be effectively excited by blue light. To prepare white light LEDs with high color rendering index, such phosphors are necessary. indispensable.

Contents of the invention

The invention aims to solve the technical problems in the prior art, and provides a fluorescent powder for white LEDs suitable for excitation by ultraviolet light and blue light and a preparation method thereof.

In order to solve the problems of the technologies described above, the technical solution of the present invention is specifically as follows:

A fluorescent powder for white LEDs suitable for excitation by ultraviolet light and blue light, the chemical formula of which is: M ₈ Al _8-2a Mg _a Si _4+a O ₂₈ :xEu ²⁺ ; wherein, M is Mg, Ca, Sr or Ba One or more of them; 0<a<4; 0.001≤x≤0.10.

A method for preparing phosphor powder for white light LEDs suitable for excitation by ultraviolet light and blue light, the preparation method comprising the following steps:

(1) According to the stoichiometric ratio of chemical formula M ₈ Al _8-2a Mg _a Si _4+a O ₂₈ :xEu ²⁺ , weigh one or more alkaline earth metal compounds, aluminum compounds, silicon compounds and europium compounds, grind and mix Uniform, to obtain the reactant precursor;

The alkaline earth metal compound is an oxide, hydroxide or carbonate of one of Mg, Ca, Sr and Ba; the europium compound is an oxide, carbonate or hydroxide of europium;

(2) Calcining the reactant precursor obtained in step (1) at 1200-1350° C. for 2-5 hours in a reducing atmosphere to obtain phosphor;

(3) After grinding and dispersing the phosphor powder obtained in step (2), a phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light is obtained.

In the above technical solution, the aluminum compound in step (1) is aluminum oxide, and the silicon compound is silicon dioxide.

In the above technical solution, a co-solvent may also be added to the reactant precursor in step (1), and the amount of the co-solvent added is less than 10% of the weight of the reactant precursor.

In the above technical solution, the co-solvent is boric acid, ammonium fluoride, ammonium bifluoride or aluminum fluoride.

In the above technical solution, the reducing atmosphere described in step (2) is a CO reducing atmosphere, or a reducing atmosphere mixed with _H2 and _N2 , and the volume ratio of _H2 and _N2 is 1% to 20%: 99% ~80%.

The advantages of the present invention are:

1. The fluorescent powder provided by the present invention emits yellow-green light under the excitation of ultraviolet light and blue light.

2. The phosphor powder provided by the present invention does not contain sulfur and has stable performance.

3. The phosphor powder provided by the present invention has a wide excitation spectrum. The phosphor powder has an excitation wavelength of 200-500nm and an emission wavelength of 450nm-700nm, so it is suitable for ultraviolet light and blue light LED excitation (see Figures 4 and 5). It is used to prepare white LED with high color rendering index.

4. The phosphor manufacturing method provided by the present invention is simple, feasible, easy to operate, easy to mass produce, non-polluting, and low in cost.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the XRD spectrogram of the fluorescent powder Ca _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 3;

Fig. 2 is the excitation spectrum of the fluorescent powder Ca _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 3;

Fig. 3 is the emission spectrogram of the fluorescent powder Ca _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 3;

Fig. 4 is the excitation spectrum of the fluorescent powder Ca _7.12 Sr _0.8 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 4;

Fig. 5 is the emission spectrogram of the fluorescent powder Ca _7.12 Sr _0.8 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 4;

Fig. 6 is the excitation spectrum of the fluorescent powder Ca _7.52 Mg _0.4 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 5;

FIG. 7 is an emission spectrum diagram of the fluorescent powder Ca _7.52 Mg _0.4 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ prepared in Example 5.

Detailed ways

Example 1

Weigh 0.5945 grams of CaCO ₃ , 0.0302 grams of MgO, 0.2294 grams of Al ₂ O ₃ , 0.2253 grams of SiO ₂ , and 0.106 grams of Eu ₂ O ₃ , thoroughly grind and mix them, put them into a corundum crucible, and then put the corundum crucible into a high-temperature furnace Calcined at 1300°C for 4 hours in a mixed reducing atmosphere of 5% H ₂ and 95% N ₂ , took it out after natural cooling, and after grinding and dispersing, a phosphor powder for white LEDs suitable for ultraviolet light and blue light excitation was obtained, and its composition was Ca _7.92 MgAl ₃ Si ₅ O ₂₈ :0.01 Eu ²⁺ .

Example 2

Weigh 0.5945 grams of CaCO ₃ , 0.0604 grams of MgO, 0.1529 grams of Al ₂ O ₃ , 0.2704 grams of SiO ₂ , and 0.106 grams of Eu ₂ O ₃ , thoroughly grind and mix them, put them into a corundum crucible, and then put the corundum crucible into a high-temperature furnace Calcined at 1300°C for 4 hours in a mixed reducing atmosphere of 10% H ₂ and 90% N ₂ , took it out after natural cooling, and after grinding and dispersing, a phosphor powder for white LEDs suitable for ultraviolet light and blue light excitation was obtained, and its composition was Ca _7.92 Mg ₄ Al ₄ Si ₆ O ₂₈ : 0.01 Eu ²⁺ .

Example 3

Weigh 0.5945 grams of CaCO ₃ , 0.0906 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , and 0.106 grams of Eu ₂ O ₃ , grind and mix them thoroughly, put them into a corundum crucible, and then put the corundum crucible into a high-temperature furnace Calcined at 1300°C for 4 hours in a mixed atmosphere of 20% H ₂ and 80% N ₂ , took it out after natural cooling, and after grinding and dispersing, a phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light was obtained, and its composition was Ca _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ . Attached Figure 1 is the XRD pattern of the phosphor powder prepared in this example, which can illustrate the successful preparation of Ca _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ . Accompanying drawing 2 and 3 are respectively the excitation and emission spectrograms of the fluorescent powder prepared in this embodiment, which illustrate that the fluorescent powder prepared in this embodiment has a wider excitation spectrum, with an excitation wavelength of 200-500nm and an emission wavelength of 450nm-700nm. Therefore suitable for UV and blue LED excitation.

Example 4

Weigh 0.2993 grams _of CaO, 0.0886 grams of SrCO ₃ , 0.0906 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , and 0.106 grams of Eu ₂ O 3 . Put it in a high-temperature furnace and bake it in a CO reducing atmosphere at 1350°C for 5 hours, take it out when it is cooled to 1000°C, and grind and disperse it to obtain a phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light. Its composition is Ca _7.12 Sr _0.8 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ . Accompanying drawing 4 and 5 are respectively the excitation and emission spectrograms of the fluorescent powder prepared in this embodiment, which illustrate that the fluorescent powder prepared in this embodiment has a wider excitation spectrum, the excitation wavelength is 200-500nm, and the emission wavelength is 450nm-700nm. Therefore suitable for UV and blue LED excitation.

Example 5

Weigh 0.8357 grams of Ca(OH) ₂ , 0.1027 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , and 0.106 grams of Eu ₂ O ₃ . Baked in a high-temperature furnace at 1300°C in a CO reducing atmosphere for 2 hours, took it out when cooled to 1000°C, and after grinding and dispersing, a phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light was obtained, the composition of which was Ca _7.52 Mg _0.4 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ . Accompanying drawing 6 and 7 are respectively the excitation and emission spectrograms of the fluorescent powder prepared in this embodiment, which illustrate that the fluorescent powder prepared in this embodiment has a wider excitation spectrum, the excitation wavelength is 200-500nm, and the emission wavelength is 450nm-700nm. Therefore suitable for UV and blue LED excitation.

Example 6

Weigh 0.5345 grams of CaCO _{3 ,} 0.1184 grams of BaCO ₃ , 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , 0.0906 grams of MgO, 0.106 grams of Eu ₂ O ₃ , and 0.0111 grams of NH ₄ F. Put the corundum crucible into a high-temperature furnace and bake it in a CO reducing atmosphere at 1200°C for 4 hours, take it out after natural cooling, grind and disperse, and obtain a phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light. Its composition is Ca _7.12 Ba _0.8 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ .

Example 7

Weigh 0.5945 grams of CaCO ₃ , 0.0906 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO _{2 ,} 0.106 grams of Eu ₂ O ₃ , and 0.0185 grams of H ₃ BO ₃ . Put the corundum crucible in a high-temperature furnace and bake it at 1300°C for 4 hours in a mixed reducing atmosphere of 5% _H2 and 95% _N2 , take it out after natural cooling, grind and disperse, and obtain a white light LED suitable for ultraviolet light and blue light excitation. Phosphor powder, the composition of which is Ca _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ .

Example 8

Weigh 0.8768 grams of SrCO ₃ , 0.0906 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , 0.106 grams of Eu ₂ O ₃ , and 0.0733 grams of NH ₄ HF ₂ . Put the corundum crucible into a high-temperature furnace and bake it at 1250°C for 4 hours in a mixed reducing atmosphere of 20% H ₂ and 80% N ₂ , take it out after natural cooling, grind and disperse, and obtain a white light LED suitable for excitation by ultraviolet light and blue light Phosphor powder is used, the composition of which is Sr _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ .

Example 9

Weigh 1.172 grams of BaCO ₃ , 0.0906 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO _{2 ,} 0.106 grams of Eu ₂ O ₃ , and 0.0352 grams of aluminum fluoride. The crucible was put into a high-temperature furnace and baked at 1200°C for 5 hours in a mixed reducing atmosphere of 1% _H2 and 99% _N2 . After natural cooling, it was taken out. After grinding and dispersing, a fluorescent light for white LEDs suitable for excitation by ultraviolet light and blue light was obtained. Powder, its composition is Ba _7.92 Mg ₃ AlSi ₇ O ₂₈ :0.01Eu ²⁺ .

Example 10

Weigh 0.5344 grams of CaCO _{3 ,} 0.0443 grams of SrCO ₃ , 0.052 grams of BaCO ₃ , 0.0906 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , and 0.106 grams of Eu ₂ O ₃ . , then put the corundum crucible into a high-temperature furnace in a mixed reducing atmosphere of 20% H ₂ and 80% N ₂ and bake at 1350°C for 2 hours, take it out after natural cooling, grind and disperse, and obtain a kind of Phosphor powder for white LED, its composition is Ca _7.12 Sr _0.4 Ba _0.4 Mg ₃ AlSi ₇ O ₂₈ :0.1Eu ²⁺ .

Example 11

Weigh 0.5098 grams of CaCO ₃ , 0.0443 grams of SrCO ₃ , 0.052 grams of BaCO ₃ , 0.1027 grams of MgO, 0.0765 grams of Al ₂ O ₃ , 0.3154 grams of SiO ₂ , and 0.0106 grams of Eu ₂ O ₃ . , then put the corundum crucible into a high-temperature furnace and bake it at 1350°C for 2 hours in a mixed atmosphere of 20% H ₂ and 80% N ₂ , take it out after natural cooling, grind and disperse, and obtain a white light suitable for excitation by ultraviolet light and blue light Phosphor powder for LED, its composition is Ca _6.792 Sr _0.4 Ba _0.4 Mg _3.4 AlSi ₇ O ₂₈ :0.001Eu ²⁺ .

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (6)

1. A phosphor powder for white light LEDs suitable for ultraviolet light and blue light excitation, characterized in that its chemical formula is: M ₈ Al _8-2a Mg _a Si _4+a O ₂₈ :xEu ²⁺ ; wherein, M is Mg One or more of , Ca, Sr or Ba; 0<a<4; 0.001≤x≤0.10. 2. The preparation method of phosphor powder suitable for white light LEDs excited by ultraviolet light and blue light according to claim 1, characterized in that the preparation method comprises the following steps: (1) According to the stoichiometric ratio of chemical formula M ₈ Al _8-2a Mg _a Si _4+a O ₂₈ :xEu ²⁺ , weigh one or more alkaline earth metal compounds, aluminum compounds, silicon compounds and europium compounds, grind and mix Uniform, to obtain the reactant precursor; The alkaline earth metal compound is an oxide, hydroxide or carbonate of one of Mg, Ca, Sr and Ba; the europium compound is an oxide, carbonate or hydroxide of europium; (2) Calcining the reactant precursor obtained in step (1) at 1200-1350° C. for 2-5 hours in a reducing atmosphere to obtain phosphor; (3) After grinding and dispersing the phosphor powder obtained in step (2), a phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light is obtained. 3. The preparation method of phosphor powder for white LEDs suitable for ultraviolet light and blue light excitation according to claim 2, characterized in that the aluminum compound described in step (1) is aluminum oxide, and the silicon The compound is silicon dioxide. 4. The method for preparing phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light according to claim 2, characterized in that the reactant precursor in step (1) can also be added, and the amount of co-solvent added is less than that of the reaction 10% of the weight of the precursor. 5 . The method for preparing phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light according to claim 4 , wherein the co-solvent is boric acid, ammonium fluoride, ammonium bifluoride or aluminum fluoride. 6. The method for preparing phosphor powder for white LEDs suitable for excitation by ultraviolet light and blue light according to any one of claims 1-5, characterized in that the reducing atmosphere described in step (2) is a CO reducing atmosphere, Or a reducing atmosphere in which H ₂ and N ₂ are mixed, and the volume ratio of H ₂ and N ₂ is 1%-20%: 99%-80%.

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