CN102002362A - Fluorescent powder for white light LED, preparation method and application thereof - Google Patents

Abstract

The invention relates to LED fluorescent powder, and a preparation method and application thereof. The LED fluorescent powder is characterized in that the chemical general formula is RE3-xNbO7:xEu3+, wherein RE is one or more of Y, La and Gd, and x is less than or equal to 1.00 and more than or equal to 0.10. The preparation method comprises the following steps: (1) weighing corresponding raw materials in mol ratio of the chemical general formula RE3-xNbO7:xEu3+, porphyrizing and uniformly mixing; (2) calcining the mixed materials in step (1) in a muffle furnace at high temperature, wherein the calcining temperature of the mixed materials is 1000-1600 DEG C, and the calcining time is 3-24 hours; and (3) carrying out post treatment on the calcined product in step (2). The fluorescent powder can be effectively activated by near ultraviolet light and blue light to glow, and the fluorescent powder can be well matched with near ultraviolet light and blue light LED chips. The fluorescent powder has stable physical/chemical properties, does not react with oxygen, water, carbon dioxide and the like in the environment and has the advantages of heat resistance, no toxicity and no public nuisance. The preparation method is simple and easy to operate and realizes the direct calcination in the air, thereby having good application prospects.

Description

Phosphor powder for white light LED, preparation method and application thereof

technical field

The invention belongs to the technical field of rare earth luminescent materials, and in particular relates to a red fluorescent powder for white LEDs and a preparation method and application thereof.

Background technique

Light-emitting diode (light-emitting diode) is a new type of solid-state lighting electric light source, which has the advantages of high efficiency, energy saving, green environmental protection, long life, small size, impact resistance, fast luminous response and low working voltage. And other fields have already been widely used, and now white light LED has begun to launch a strong challenge to the stable position of incandescent lamps and fluorescent lamps in the lighting field, and is expected to gradually replace them, thus presenting a huge market prospect.

There are two main ways for white LEDs to produce white light: the first is to combine red, green, and blue LEDs to produce white light; the second is to use LEDs to excite light conversion phosphors and mix them to form white light. There are two ways to achieve this scheme, wherein the more mature method is to match blue LED chips with YAG:Ce yellow phosphor to achieve white light emission (US Patent 5998925), but due to the lack of red light, the compounded white light is cold white light, so this scheme still needs to add Appropriate red phosphors are used to improve the color rendering index. Another solution is to combine near-violet LED chips (390-410nm) with red/green/blue tricolor phosphors. Red phosphors play a pivotal role.

At present, the chips used for white LED lighting are mainly 390-410nm near-ultraviolet chips and 465nm blue chips. However, the effective excitation range of existing red phosphors is mostly in the short-wave UV region, and the excitation efficiency under near-ultraviolet and blue light is low. Therefore, it is particularly important to develop efficient and stable red phosphors for near-ultraviolet and blue LEDs. At present, there is still a lack of red phosphors with excellent performance that can be excited by near-ultraviolet or blue LED chips in the market, especially red phosphors that can be excited by both near-ultraviolet and blue LEDs are still in the research stage.

Among the reports of red phosphors used in white LEDs, those that can meet the application requirements in both luminous intensity and stability are rare. For example: Some people try to apply Y ₂ O ₂ S:Eu ³⁺ to the WLED field. However, the current commercial red phosphor Y ₂ O ₂ S:Eu ³⁺ has many shortcomings: low luminous efficiency under near-ultraviolet light excitation, The chemical properties are unstable, easy to decompose, and the service life is short. The precipitation of sulfur will cause corrosive effects on the chip, resulting in the failure of the entire device. Several main types of red phosphors that are expected to be used in white LEDs in literature and patent reports include: Ca ₃ (VO ₄ ) ₂ :Eu ³⁺ , YVO ₄ :Eu ³⁺ , Y ₂ O ₃ :Eu ³⁺ , Bi ³⁺ , CaO:Eu ³⁺ , CaMoO ₄ :Eu ³⁺ , (Gd, Y, Eu) ₂ (MoO ₄ ) ₃ :Sm ³⁺ , (Sr, Ca)S:Eu ²⁺ , Ca ₅ (SiO ₄ ) ₂ Cl ₂ :Eu ²⁺ , Sr ₂ Si ₅ N ₈ :Eu ²⁺ , etc. Among them, rare earth-activated nitrogen oxides have been paid attention to because of their high stability and good luminous efficiency, such as: Sr ₂ Si ₅ N ₈ :Eu ²⁺ , SrSi ₂ O ₂ N ₂ :Eu ²⁺ , but the matrix synthesis of such materials requires It is completed under high temperature (1600-1700°C) and high nitrogen or ammonia pressure (10atm), which has very strict requirements on production equipment.

At present, there are few literature reports and patents on the red phosphor powder for white light LED with Eu ³⁺ as the active ion and niobate as the matrix. Tae-Keun Park et al. studied the effect of high concentration of Bi ³⁺ on the photoluminescence properties of RNbO ₄ :Eu ³⁺ (R=La, Y, Gd) (Journal of the Korean Physical Society, 2008, 52: 431 ↑434); Zhou Liya et al studied the effect of Eu ³⁺ concentration on the emission spectrum of LaNb _0.70 V _0.30 O ₄ :Eu ³⁺ , and proved that the incorporation of V ⁵⁺ broadens the excitation band to the long-wave direction (Journal of Alloys and Compounds 2010, 495: 268-271). Invention patents CN1239673C and CN1331982C both relate to phosphors for white light LEDs based on niobate.

Contents of the invention

The purpose of the present invention is to provide a fluorescent powder for white LEDs that has stable chemical properties, good luminous effect, ideal color purity, and can be effectively excited by near ultraviolet light and blue light to emit red light.

Another object of the present invention is to provide a preparation method of the above-mentioned red phosphor. The preparation method of the fluorescent powder is simple, easy to operate, pollution-free and low in cost.

Another object of the present invention is the application of the phosphor powder of the present invention in white LED electric light sources.

To achieve the above object, the present invention is achieved through the following technical solutions:

Using stable RE _3-x NbO ₇ as the matrix and Eu ³⁺ as the active ion, its chemical composition formula is RE _3-x NbO ₇ :xEu ³⁺ , where RE is one or both of Y, La, and Gd More than one species, 0.10≤x≤1.00.

The preparation method of the fluorescent powder involved in the present invention is as follows:

(1) Accurately weigh the raw materials according to the molar ratio required by the chemical composition formula RE _3-x NbO ₇ :xEu ³⁺ (where RE is one or more of Y, La, Gd, 0.10≤x≤1.00) , grind to make it evenly mixed;

(2) Put the mixed material obtained in step (1) into the air atmosphere of the muffle furnace for high-temperature roasting, the roasting temperature of the mixed material is 1000-1600°C, and the roasting time is 3-24 hours;

(3) subjecting the calcined product obtained in step (2) to a post-treatment process to obtain the red phosphor;

The raw materials Nb, Y, La, Gd and Eu described in the present invention are simple substances, or their oxides, or their corresponding salts.

In the step (1) of the present invention, a reaction flux can be added, and the reaction flux is one or more of Li halides, sulfates, diboron trioxide or boric acid.

In the step (1) of the present invention, relative to the total weight of the fluorescent powder to be synthesized, the fluxing agent is added in an amount of 0.001-10 wt%.

In the step (2) of the present invention, the high-temperature roasting can be divided into one time or more than two times; the roasting temperature of each time is 1000-1600° C., and the roasting time is 3-24 hours.

In the step (3) of the present invention, the post-treatment process includes crushing, jet milling, impurity removal, drying and classification. The impurity removal process includes pickling, alkali washing or water washing. The classification process includes gravity sedimentation method, sieving method, hydraulic classification method or air flow classification method.

The application of the present invention to the white LED electric light source is to prepare the electric light source containing the phosphor powder prepared by the present invention and near ultraviolet or blue LED.

The phosphor powder synthesized by the present invention has the characteristics of wide excitation wavelength range, good luminous effect, and stable physical and chemical properties. It can be effectively excited by near ultraviolet light and blue light to emit red light, so it can be coated on blue LED to prepare a new type of White LED light sources can also be matched with near-ultraviolet LEDs, mixed with phosphors of other colors to prepare white or colored LED light sources, showing a wide range of application prospects, especially in the application of white LED lighting technology.

Features of the present invention:

(1) The present invention uses RE _3-x NO ₇ niobate as the substrate and Eu ³⁺ as the excitation center (wherein RE is one or more of Y, La, Gd, 0.10≤x≤1.00) , a phosphor powder that can be effectively excited by near-ultraviolet light and blue light to emit red light is prepared. This powder can be well matched with near-ultraviolet light and blue light LED chips. It is a new type of high-efficiency red phosphor powder for white LEDs.

(2) The red fluorescent powder of the present invention has stable physical and chemical properties, does not react with oxygen, water, carbon dioxide, etc. in the environment, is heat-resistant, non-toxic, and pollution-free.

(3) The preparation method of the red phosphor powder of the present invention is simple and easy to operate, does not use special gas protection, and is directly roasted in the air, and has a good application prospect.

Description of drawings

Fig. 1 is the excitation spectrum (left side) under 612nm monitoring of Y _1.5 NbO ₇ : _1.5 Eu ³⁺ prepared in Example 1 and the emission spectrum (right side) respectively under 395nm excitation, as shown in the figure, the fluorescence The powder can be effectively excited by near-ultraviolet light, blue light and green light in the range of 350-550nm to emit red light with a main peak wavelength at around 612nm, among which near-ultraviolet light has a higher excitation intensity and the red color is of high purity.

Fig. 2 is the excitation spectrum (left side) under 612nm monitoring of Gd _1.8 NbO ₇ : _1.2 Eu ³⁺ prepared in Example 2 and the emission spectrum (right side) respectively under 395nm and 465nm excitation, as shown in the figure, The phosphor can be effectively excited by near-ultraviolet light, blue light and green light in the range of 350-550nm to emit red light with a main peak wavelength at about 612nm, wherein the near-ultraviolet light has higher excitation intensity and the red color is of high purity.

Fig. 3 is the excitation spectrum (left side) under 612nm monitoring of La _1.5 NbO ₇ : _1.5 Eu ³⁺ prepared in Example 3 and the emission spectrum (right side) respectively under 395nm and 465nm excitation, as shown in the figure, The phosphor can be effectively excited by near-ultraviolet light, blue light and green light in the range of 350-550nm to emit red light with a main peak wavelength at about 612nm, wherein the near-ultraviolet light has higher excitation intensity and the red color is of high purity.

Detailed ways

The invention will be further illustrated by the following examples.

Example 1: Preparation example of Y _1.5 NbO ₇ : _1.5 Eu ³⁺ phosphor

Weigh respectively 1.3969 grams of Y ₂ O ₃ (99.999%), 1.0962 grams of Nb ₂ O ₅ (99.999%), 2.1771 grams of Eu ₂ O ₃ (99.999%), 0.4000 grams of LiCl (analytical pure), wherein LiCl is used as a reaction flux , grind and mix evenly in an agate mortar, put it into an alumina crucible, bake at 1200°C for 8 hours in an air atmosphere, cool to room temperature with the furnace, wash with water to remove impurities, dry, and grind to obtain Y _1.5 in the present invention. NbO ₇ : _1.5 Eu ³⁺ red phosphor. Its excitation and emission spectra are shown in Fig. 1.

Example 2: Preparation Example of Gd _1.8 NbO ₇ : _1.2 Eu ³⁺ Phosphor Powder

Weigh 2.2966 grams of Gd ₂ O ₃ (99.999%), 0.93558 grams of Nb ₂ O ₅ (99.999%), 1.4864 grams of Eu ₂ O ₃ (99.999%), and 0.4000 grams of LiCl (analytical pure), wherein LiCl is used as a reaction flux , grind and mix evenly in an agate mortar, put it into an alumina crucible, bake at 1200°C for 8 hours in an air atmosphere, cool to room temperature with the furnace, wash with water to remove impurities, dry, and grind to obtain Gd _1.8 in the present invention. NbO ₇ : ₁₂ Eu ³⁺ red phosphor. Its excitation and emission spectra are shown in Fig. 2.

Example 3: Preparation example of La _1.5 NbO ₇ : _1.5 Eu ³⁺ phosphor

Weigh 1.7936 grams of La ₂ O ₃ (99.999%), 0.9756 grams of Nb ₂ O ₅ (99.999%), 1.9374 grams of Eu ₂ O ₃ (99.999%), and 0.4000 grams of LiCl (analytical pure), wherein LiCl is used as a reaction flux , grind and mix evenly in an agate mortar, put it into an alumina crucible, bake at 1200°C for 8 hours in an air atmosphere, cool to room temperature with the furnace, wash with water to remove impurities, dry, and grind to obtain Gd _1.8 in the present invention. NbO ₇ : _1.2 Eu ³⁺ red phosphor. Its excitation and emission spectra are shown in Fig. 3.

Claims (8)

1. a LED fluorescent material and preparation method and application is characterized in that its chemical constitution general formula is:

RE _3-xNbO ₇:xEu ³⁺

Wherein, RE is Y, La, one or more among the Gd, 0.10≤x≤1.00.

2. the preparation method of the described fluorescent material of claim 1 is characterized in that:

(1) according to chemical constitution formula RE _3-xNbO ₇: xEu ³⁺Mol ratio take by weighing and answer raw material, porphyrize mixes;

(2) mixture that step (1) is obtained is put into the retort furnace high-temperature roasting, and the maturing temperature of mixture is 1000-1600 ℃, and roasting time is 3-24 hour;

(3) product of roasting that obtains in the step (2) is passed through last handling process again, promptly obtain this fluorescent material.

3. preparation method according to claim 2 is characterized in that described Nb, Y, La, Gd, Eu are simple substance, perhaps its oxide compound, perhaps its corresponding salt.

4. preparation method according to claim 2 is characterized in that in step (1) adding reaction flux, and described reaction flux is one or more in halogenide, vitriol, boron trioxide or the boric acid of Li.

5. preparation method according to claim 4 is characterized in that the gross weight with respect to want synthetic fluorescent material, and the add-on of fusing assistant is 0.001～10wt%.

6. preparation method according to claim 2 is characterized in that in the described step (2), and more than high-temperature roasting can be divided into once or twice, each maturing temperature 1000-1600 ℃, roasting time was 3-24 hour.

7. preparation method according to claim 2, in the described step of its feature (3), last handling process comprises fragmentation, removal of impurities, dries and sieves.

8. the application of the described fluorescent material of claim 1 is characterized in that being prepared into electric light source with containing prepared fluorescent material of the present invention and near ultraviolet or blue-ray LED.

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