CN1952039A - Sialon fluorescent powder for white light LED and electric light sources manufactured therefrom - Google Patents

Abstract

The invention relates to a sialon phosphor used for white light LEDs, the chemical formula of which is (M _1-x/v Na _x ) _m/v Si _12-m-n Al _m+n O _n N _16-n : Re _y , where M is one or more of Ca, Li, Mg, Y, La, Nd, Lu; v is the valence of M; Re is the rare earth luminescent element Eu, Ce, Dy, Tb, Pr, Sm, Yb One or more of them; 0.005≤x≤2.0; 0.5≤m≤4.0; 0≤n≤3.0; 0.0005≤y≤0.5. The invention also provides a preparation method of the fluorescent powder. The white light LED can be produced by combining the phosphor powder of the present invention with the blue light LED.

Description

A kind of sialon phosphor used for white light LED and electric light source made therefrom

technical field

The invention belongs to the field of semiconductors, and in particular relates to a fluorescent powder, a preparation method thereof, and a white LED electric light source containing the fluorescent powder.

Background technique

White light-emitting diodes (LEDs) have the characteristics of longer life, smaller volume, higher luminous efficiency, and lower energy consumption than currently used illuminators. Therefore, white LEDs are considered to be an alternative lighting source in some fields, such as household fluorescent lamps, liquid crystal display devices or backlights for billboard screens, and the like.

Currently the easiest way to manufacture white LEDs is by combining InGaN-based blue LEDs with a wavelength of 450nm and yttrium aluminum garnet YAG:Ce phosphors. The white light LED is performed by performing the following steps: first, the blue LED emits blue light, and the YAG:Ce fluorescent material absorbs a part of the blue light and converts it into yellow-green fluorescence; then the blue light and the yellow-green fluorescence are mixed to form white light. However, this white light has only a portion of the visible spectrum, resulting in a lower color rendering index. At the same time, the tone of this white light is cooler, mainly because the YAG:Ce fluorescent material contains less red components. In order to obtain a warmer white LED, it is necessary to mix YAG:Ce with another red phosphor, but at the same time, the luminous efficiency of the obtained white LED decreases, which affects the actual use effect. In order to achieve warm white lighting with high luminous efficiency, it is necessary to research and develop a new type of phosphor that can be effectively excited by wavelengths in the ultraviolet-blue range and emit yellow or orange-yellow fluorescence. Although the currently reported europium-doped silicate M2SiO4:Eu (M=Ca, Sr, Ba) can emit yellow fluorescence, the phosphor cannot be effectively excited by blue LEDs, and its thermal stability is poor, which affects the Luminous efficiency and service life of white LEDs.

Contents of the invention

technical problem to be solved

The technical problem to be solved by the present invention is to provide a sialon phosphor used for white light LEDs and an electric light source made thereof, so as to overcome the insufficient thermal stability of the existing yellow phosphor and the low efficiency under blue light excitation. shortcoming.

Technical solutions

One of the technical solutions of the present invention is to provide a sialon phosphor for white LED, (M _1-x/v Na _x ) _m/v Si _12-mn Al _{m+n On} N _16-n :Re _y , where M is one or more of Ca, Li, Mg, Y, La, Nd, Lu; v is the valence of M; Re is the rare earth luminescent element Eu, Ce, Dy, Tb, Pr, Sm, One or more of Yb; 0.005≤x≤2.0; 0.5≤m≤4.0; 0≤n≤3.0; 0.0005≤y≤0.5.

The second technical solution of the present invention is to provide a method for preparing the phosphor powder described in claim 1, the steps comprising:

(1) Use M-containing oxides, nitrides, fluorides or salts, Re-containing nitrides or oxides as raw materials, and mix uniformly through grinding according to the raw material ratio expressed by the chemical formula;

(2) Carrying out high-temperature calcination of the obtained mixture in high-pressure nitrogen;

(3) The phosphor powder of the present invention is obtained by subjecting the calcined product to a post-treatment process.

One of the preferred schemes of the above-mentioned phosphor powder preparation method is that in the step (2), the temperature of the high-temperature calcination is 1500-2000° C., and the calcination time is 0.5-60 hours.

The second preferred solution of the above phosphor powder preparation method is that the calcination of the step (2) is repeated several times.

The third preferred solution of the above phosphor preparation method is that in the step (2), the nitrogen pressure is 1-20 atmospheres.

The fourth preferred solution of the above phosphor powder preparation method is that in the step (3), the post-treatment process is sequentially pulverized and washed to remove impurities. Said pulverization is manual pulverization in a mortar, or pulverization by airflow, or pulverization by ball mill. The steps of washing and removing impurities include pickling, water washing and drying in sequence.

A further preferred version of the above-mentioned phosphor powder preparation method is that said pickling solution is a mixed acid solution of (sulfuric acid+hydrofluoric acid): deionized water=1: (15-20) (volume ratio), wherein sulfuric acid: Hydrofluoric acid=1:2～2:1, pickling time is 0.5～2 hours; said water washing is carried out until the pH value is neutral; said drying conditions are 80～120° C. and 2～12 hours.

The third technical solution of the present invention is to provide a white LED electric light source manufactured by combining the fluorescent powder described in claim 1 with a 430-480nm blue LED.

Its realization is as follows: said white LED electric light source is a light emitting device, including a light emitting diode as a light emitting element, and said phosphor containing oxynitride sialon phosphor as one of the technical solutions. Among them, the wavelength emitted by the light-emitting diode includes blue light of 430-480nm, while the oxynitride sialon phosphor absorbs the blue light emitted by the light-emitting diode and emits yellow light or orange-yellow fluorescence with a wavelength of 550-610nm. After mixing, it produces white light.

The fluorescent powder mentioned in one of the technical solutions of the present invention can also be matched with ultraviolet or near-ultraviolet LEDs, and then mixed with other green and red fluorescent powders to prepare white LED electric light sources with high color rendering index.

Beneficial effect

In the present invention, by doping rare-earth luminescent elements in heat-resistant oxynitride sialon and partially replacing other metal elements with Na to improve the luminous intensity, a kind of white light LED electric light source that can be used for white LED is synthesized under high-pressure nitrogen and high temperature. Manufactured yellow or orange-yellow phosphors.

The oxynitride phosphor powder for white LEDs provided by the invention can be excited by ultraviolet LEDs or blue LEDs, and has high thermal stability, excellent luminous performance, high luminous efficiency and long service life.

The oxynitride fluorescent powder provided by the invention has the characteristics of being effectively excited by wavelengths in the ultraviolet-blue range and emitting yellow or orange-yellow fluorescence, and realizes warm white light illumination with high luminous efficiency. It overcomes that the existing europium-doped silicate M ₂ SiO ₄ :Eu (M=Ca, Sr, Ba) phosphor cannot be effectively excited by blue LEDs, and has poor thermal stability, which affects the luminous efficiency and service life of white LEDs Shortcomings.

Description of drawings

Fig. 1 is the emission spectrum of the white LED of Example 12.

Fig. 2 is the emission spectrum and excitation spectrum of embodiment 1.

Fig. 3 is the emission spectrum and excitation spectrum of embodiment 2.

Fig. 4 is the emission spectrum and excitation spectrum of embodiment 3.

Figure 5 is the emission spectrum and excitation spectrum of Example 4.

Figure 6 is the emission spectrum and excitation spectrum of Example 5.

Figure 7 is the emission spectrum and excitation spectrum of Example 9.

FIG. 8 is the emission spectrum and excitation spectrum of Example 11.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

For the experimental methods without specific conditions indicated in the following examples, generally follow the conventional conditions reported in the literature, or follow the conditions suggested by the manufacturer.

Example 1: Synthesis of (Ca _0.75 Na _0.5 ) _0.75 Si ₉ Al ₃ O _1.5 N _14.5 :Eu _0.10

CaCO ₃ : 8.0562 g

Na ₂ CO ₃ : 3.1628 g

Eu ₂ O ₃ : 1.5754 g

Si ₃ N ₄ : 66.8364 grams

Al ₂ O ₃ : 4.0579 grams

AlN: 16.3113 grams

After the above raw materials are ground evenly in agate, they are put into a corundum crucible, and calcined at 1700°C under a nitrogen pressure of 10 atmospheres for 3 hours, taken out after cooling, pulverized by a ball mill, and sieved. (Sulfuric acid+hydrofluoric acid): mixed acid solution of deionized water=1:15 (volume ratio), wherein sulfuric acid: hydrofluoric acid=1:2 (volume ratio), pickling time is 0.5 hour; It is equal to 7; the finally filtered powder is dried at 120° C. for 2 hours to obtain a yellow phosphor powder, which emits fluorescence at 580 nm under the excitation of 254-500 nm light.

Embodiment 2: Synthesis of Li _0.5 Na _0.5 Si _9.5 Al _2.5 O _1.5 N _14.5 :Eu _0.05

Li ₂ CO ₃ : 2.6739 g

_{Na2CO3 :} 4.2369 g

Eu ₂ O ₃ : 0.6754 g

Si ₃ N ₄ : 70.8825 grams

Al ₂ O ₃ : 9.5132 grams

AlN: 12.0181 grams

Grind the above raw materials evenly in agate, put them into a corundum crucible, and calcinate them at 1500°C under nitrogen with a pressure of 1 atmosphere. The calcining time is 60 hours. After cooling, take them out, grind them manually in a mortar, and sieve , (sulfuric acid+hydrofluoric acid): mixed acid solution of deionized water=1:18 (volume ratio), wherein sulfuric acid: hydrofluoric acid=1:1 (volume ratio), pickling time is 1 hour; It is approximately equal to 7; the finally filtered powder is dried at 80° C. for 12 hours to obtain a yellow phosphor powder, which emits fluorescence at 568 nm under the excitation of 254-500 nm light.

Example 3: Synthesis of Na ₂ Si ₈ Al ₄ O ₂ N ₁₄ :Eu _0.05

Na ₂ CO ₃ : 13.9748 g

Eu ₂ O ₃ : 4.3672 grams

Si ₃ N ₄ : 56.6955 grams

Al ₂ O ₃ : 5.1523 grams

AlN: 20.7102 grams

Grind the above raw materials evenly in agate, put them into a corundum crucible, and calcinate at 2000°C under nitrogen with a pressure of 20 atmospheres. The calcining time is 0.5 hours. Repeat the calcining after cooling for a total of three times, take it out, and use airflow crushing Sieve, (sulfuric acid+hydrofluoric acid): mixed acid solution of deionized water=1:20 (volume ratio), wherein sulfuric acid: hydrofluoric acid=1:2 (volume ratio), pickling time is 1 hour; The pH value is approximately equal to 7; the finally filtered powder is dried at 100°C for 8 hours to obtain a yellow phosphor powder, which emits fluorescence at 560nm when excited by 254-500nm light.

Example 4: Synthesis of (Y _0.667 Na _0.5 ) _0.5 Si _9.5 Al _2.5 O ₁ N ₁₅ :Eu _0.05

Y ₂ O ₃ : 5.7698 g

Na ₂ CO ₃ : 2.1011 g

Eu ₂ O ₃ : 0.4744 g

Si ₃ N ₄ : 70.3001 grams

Al ₂ O ₃ : 9.4350 g

AlN: 11.9193 grams

Grind the above raw materials evenly in agate, put them into a corundum crucible, and calcinate at 1700°C under nitrogen with a pressure of 18 atmospheres for 2 hours, take it out after cooling, crush and sieve, (sulfuric acid + hydrofluoric Acid): mixed acid solution of deionized water=1:(15～20) (volume ratio), wherein sulfuric acid: hydrofluoric acid=1:1 (volume ratio), pickling time is 1 hour; wash with water until the pH value is approximately equal to 7. Finally, the powder obtained by filtering is dried at 100°C for 10 hours to obtain a yellow phosphor powder, which emits fluorescence at 583 nm under the excitation of 254-500 nm light.

Example 5: Synthesis of Na ₂ Si ₈ Al ₄ O ₂ N ₁₄ :Ce _0.10

Na ₂ CO ₃ : 12.1773 g

_CeO2 : 4.3734 g

Si ₃ N ₄ : 57.3075 grams

Al ₂ O ₃ : 5.2079 grams

AlN: 20.9338 grams

Grind the above raw materials evenly in agate, put them into a corundum crucible, and calcinate at 1500°C under nitrogen with a pressure of 20 atmospheres for 8 hours, take out after cooling, crush and sieve, (sulfuric acid + hydrogen fluoride Acid): mixed acid solution of deionized water=1:20 (volume ratio), wherein sulfuric acid:hydrofluoric acid=2:1 (volume ratio), pickling time is 2 hours; wash with water until the pH value is approximately equal to 7; finally filter The obtained powder was dried at 100° C. for 10 hours to obtain a yellow phosphor powder, which emitted 480 nm fluorescence when excited by 400 nm light.

Examples 6-11: According to the chemical formula composition of each example in Table 1 and the corresponding raw materials, the preparation process is the same as that of Example 1, and the luminescence characteristics of the obtained phosphor are shown in Table 1.

The chemical formulas and luminescent properties of Table 1 Examples 6-13

Example Chemical formula Excitation peak nm Fluorescence 6 (Lu _0.667 Na _0.5 ) _0.5 Si _9.5 Al _2.5 ON ₁₅ :Eu _0.05 412 Yellow, 584nm 7 (Ca _0.75 Li _0.25 Na _0.25 ) _0.75 Si ₉ Al ₃ O _1.5 N _14.5 :Eu _0.10 425 Yellow, 574nm 8 (Ca _0.75 Na _0.5 ) _0.75 Si ₉ Al ₃ O _1.5 N _14.5 : Ce _0.10 386 Blue, 500nm 9 (Ca _0.75 Na _0.5 ) _0.75 Si ₉ Al ₃ O _1.5 N _14.5 :Tb _0.10 254 Green, 545nm 10 (Ca _0.75 Na _0.5 ) _0.75 Si ₉ Al ₃ O _1.5 N _14.5 :Pr _0.05 254 Red, 615nm 11 (Ca _0.75 Na _0.5 ) _0.75 Si ₉ Al ₃ O _1.5 N _14.5 :Sm _0.05 415 Red, 602nm

Example 12: Manufacture of white light LED lighting device

Mix the fluorescent powder and epoxy resin that the embodiment of the present invention 1 makes with the ratio of 2: 1 by weight, the obtained mixture is coated on the chip of commercially available blue light LED (light emission wavelength is 450nm), after 150 ℃ and 0.5 hours of drying to obtain a white LED electric light source, and its emission spectrum is shown in Figure 1.

Examples 13-22:

The phosphor powders prepared in Examples 2-11 of the present invention were used to replace the phosphor powders in Example 12, and the rest of the method was the same as in Example 12 to prepare a white LED lighting device.

Claims (10)

1. A sialon phosphor for white light LED, its chemical formula is: (M _1-x/v Na _x ) _m/v Si _12-mn Al _m+n O _n N _16-n : Re _y , where M is one of Ca, Li, Mg, Y, La, Nd, Lu One or more kinds; v is the valence number of M; Re is one or more of rare earth luminescent elements Eu, Ce, Dy, Tb, Pr, Sm, Yb; 0.005≤x≤2.0; 0.5≤m≤4.0; 0≤n≤3.0; 0.0005≤y≤0.5. 2. A method for preparing the fluorescent powder according to claim 1, the steps comprising: (1) Use M-containing oxides, nitrides, fluorides or salts, Re-containing nitrides or oxides as raw materials, and mix uniformly through grinding according to the raw material ratio expressed by the chemical formula; (2) Carrying out high-temperature calcination of the obtained mixture in high-pressure nitrogen; (3) The phosphor powder of the present invention is obtained by subjecting the calcined product to a post-treatment process. 3 . The method for preparing phosphor powder according to claim 2 , characterized in that: in the step (2), the temperature of high-temperature calcination is 1500-2000° C., and the calcination time is 0.5-60 hours. 4. The method for preparing phosphor according to claim 2 or 3, characterized in that the calcination in step (2) is repeated several times. 5. The method for preparing phosphor powder according to claim 2, characterized in that: in the step (2), the nitrogen pressure is 1-20 atmospheres. 6 . The method for preparing phosphor powder according to claim 2 , characterized in that: in the step (3), the post-treatment process is successively crushing and washing to remove impurities. 6 . 7. The method for preparing phosphor powder according to claim 6, characterized in that: said pulverization is manual pulverization in a mortar, or using jet pulverization, or using ball mill pulverization. 8. The method for preparing fluorescent powder according to claim 6, characterized in that: the step of washing and removing impurities includes pickling, water washing and drying in sequence. 9. the preparation method of fluorescent powder according to claim 8 is characterized in that: described pickling solution is (sulfuric acid+hydrofluoric acid): deionized water=1: (15～20) (volume ratio) Mixed acid solution, wherein sulfuric acid:hydrofluoric acid=1:2～2:1, pickling time is 0.5～2 hours; described washing is carried out to pH value neutrality; Described drying condition is 80～120 ℃ and 2 to 12 hours. 10. A white LED electric light source manufactured by combining the fluorescent powder described in claim 1 with a 430-480 nm blue LED.

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