CN102517000A - Alkaline earth nitride fluorescent powder and preparation method thereof - Google Patents

Abstract

The invention provides alkaline earth nitride fluorescent powder and a preparation method thereof. A chemical general formula is xM3N2-aSi3N4-bMY2:mR, wherein M is one kind or several kinds of Mg, Ca, Sr and Ba; Y is one kind or several kinds of F, Cl and Br; R represents one kind or several kinds of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm and Yb selecting from rare earth elements; and a parameter range is 0.3<x<1, 0.1<a<2, 0<b<0.1, and 0.005<m<0.5. Products of the alkaline earth nitride fluorescent powder is prepared by adopting a direct high temperature solid-state reaction method, and the nitride fluorescent powder with a specific luminous center R and base elements with different percentage values is obtained. The fluorescent powder has good luminance performance in a visible light spectrum range, and when the fluorescent powder is excited by using light with wavelength ranging from 250 to 550 nm, an emission spectrum with the wavelength ranging from 500 to 750 nm can be obtained.

Description

A kind of alkaline earth nitride phosphor and preparation method thereof

technical field

The present invention relates to the technical field of luminescent materials, and in particular provides a nitride phosphor powder and a preparation method thereof, which are binary or multi-element alloys of high-purity MSi (M is Mg, Ca, Sr, Ba and other alkaline earth metals) and the chemical formula is MY ₂ (Y is F, Cl, Br) halides as raw materials, Si ₃ N ₄ (or Si powder), rare earth element sources take simple substances or oxides or alloys as raw materials, through high-temperature solid-state sintering method, prepared with A nitride luminescent material with excellent luminescent properties.

Background technique

Nowadays, semiconductor light-emitting (LED) is widely used day by day, and it is more and more likely to replace the traditional period in the energy-saving lighting and display industry. Its basic luminescence principle is to use short-wavelength light emitted by GaN-based blue light or ultraviolet chips to excite one or more phosphors encapsulated inside the LED, so as to convert and emit light of the required color. The white light LED (WLED) uses the light emitted and the remaining blue light to synthesize to achieve the purpose of emitting white light.

Current phosphors are mainly based on sulfides, oxides or oxysulfides, and a small amount of transition metal ions or rare earth ions are doped in these matrices as luminescent centers. The disadvantages of these compounds are poor chemical stability, especially low comprehensive luminous efficiency and easy temperature quenching, and poor practicability. With the development of society, it has become more and more difficult for them to adapt to the material requirements of white light diode lighting and modern plasma and field emission display technology.

Studies have pointed out that among all compounds, nitrides have the strongest covalent bonding, and their luminous intensity and color rendering performance are obviously better than the current commercial oxide and sulfide phosphors. However, according to the current international and domestic research reports on nitride phosphors, the development of nitride phosphors is currently restricted by factors such as relatively high synthesis conditions and relatively high costs. Therefore, it is very important to explore a simple and convenient method for preparing high-efficiency nitride phosphors. At present, there is no detailed application description about the alloy method to obtain nitride luminescent materials.

Contents of the invention

The purpose of the present invention is to solve the problems of relatively high synthesis conditions and high cost of the existing nitride phosphors, provide a nitride luminescent material and a preparation method thereof, and obtain a nitride luminescent material with excellent luminescent performance.

The general chemical formula of the nitride luminescent material of the present invention is: xM ₃ N ₂ •aSi ₃ N ₄ •bMY ₂ :mR, wherein, M is one or more of Mg, Ca, Sr, Ba; Y is F, One or more of Cl, Br; R represents one or more of rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm, Yb; where 0.3<x <1,0.1<a<2, 0<b<0.1, 0.005<m<0.5. The excitation wavelength is between 250-550nm, the main peak wavelength of the excitation light is 400nm, the emission wavelength is between 500-750nm, and the main peak wavelength of the emission light is between 550-670nm; the specific wavelength position and parameters m (luminescent center content) and x , a, b ratio (matrix element ratio) selection.

This is an alkaline-earth silicon-based oxynitride phosphor, so it contains Si and N elements. In addition, the alkaline-earth element M can be one or more of Mg, Ca, Sr, and Ba. The source of alkaline earth elements of the present invention is high-purity MSi (M is a binary or multi-element alloy material whose purity is higher than 99.5% of alkaline earth metals such as Mg, Ca, Sr, Ba, etc.), and the chemical formula is MY ₂ (Y is F, Cl, Br) halide, the silicon source is taken from Si powder or Si ₃ N ₄ powder, the rare earth element is selected as the activator, and its source is rare earth element simple substance or oxide or alloy, among which MY ₂ is the raw material and the fusion phase agent , after grinding and tableting (optional), a kind of nitride luminescent material containing rare earth ions xM ₃ N ₂ •aSi ₃ N ₄ •bMY ₂ :mR(M is Mg, Ca, Sr, Ba and other alkaline earth metals), the nitride luminescent material obtained by this method has excellent luminescent performance.

The following are the specific process steps:

(1) The raw material is MSi alloy, ɑ-Si ₃ N ₄ , alkaline earth metal halide MY ₂ and R ₂ O ₃ powder, and the purity is less than 99.5%. Its preparation method is as follows: According to the general formula xM ₃ N ₂ •aSi ₃ N ₄ •bMY ₂ :mEu ²⁺ the molar ratio is, MSi:Si ₃ N ₄ :MY ₂ :R ₂ O ₃ =(3x-b): (ax): b:m/2, fully ground into a powder in a vacuum glove box, after mixing evenly, drying, and tableting (optional); then load the flake sample in a graphite furnace, Under the protection of N ₂ at ~10 atmospheres, the temperature is raised to 1200-1500°C for sintering for 1-12 hours, and then cooled with the furnace.

(2) The raw materials are MSi alloy, ɑ-Si ₃ N ₄ , alkaline earth metal halide MY ₂ , RSi alloy, and the purity is not less than 99.5%. Its preparation method is as follows: According to the general formula xM ₃ N ₂ •aSi ₃ N ₄ •bMY ₂ :mR, the molar ratio is, MSi:Si ₃ N ₄ :MY ₂ :RSi=(3x-bm):(axm/3) : b:m, fully ground into a powder, after mixing evenly, drying, tableting (optional); then load the sheet sample in a graphite furnace, under the protection of N ₂ at 1 to 10 atmospheres, Raise the temperature to 1200-1500°C and sinter for 1-10 hours, then cool with the furnace.

(3) The raw materials are MSi alloy, ɑ-Si ₃ N ₄ , alkaline earth metal halide MY ₂ , R simple substance, and the purity is not less than 99.5%. Its preparation method is as follows: According to the general formula xM ₃ N ₂ •aSi ₃ N ₄ •bMY ₂ :mR, the molar ratio is, MSi:Si ₃ N ₄ :MY ₂ :R=(3x-b):(ax):b :m, fully ground into a powder, after mixing evenly, drying, and pressing into tablets (optional); then load the flake samples in a graphite _furnace , and heat up to Sinter at 1200-1500°C for 1-10 hours, then cool with the furnace.

The advantages of the present invention are:

1. For the first time, the phosphor powder with xM ₃ N ₂ •aSi ₃ N ₄ •bMY ₂ :mR matrix was prepared, and it has excellent luminescence performance. The excitation wavelength is between 250-550nm, the main peak wavelength of excitation light is 400, and It is located between 500-750nm, and the main peak wavelength of the emitted light is located between 550-670nm.

2. What is particularly innovative is that its preparation raw materials are MSi series alloys with stable physical and chemical properties in the air. M is a binary or multi-element substitution composed of Ca or (and) Sr and other alkaline earth metals. The luminescent center element can be Choose its simple substance or oxide or alloy form as the rare earth ion doping body.

3. The preparation method can adopt the method of direct high-temperature solid-phase synthesis, and the process is simple and easy to operate.

4. The nitride has stable physical and chemical properties and long service life.

Description of drawings

FIG. 1 is the emission spectrum of the nitride phosphor obtained in Example 1 provided by the present invention when the excitation wavelength is 397 nm.

FIG. 2 is the excitation spectrum of the nitride phosphor obtained in Example 1 provided by the present invention when the monitoring wavelength is 609 nm.

FIG. 3 is the emission spectrum of the nitride phosphor obtained in Example 3 provided by the present invention when the excitation wavelength is 397 nm.

FIG. 4 is the excitation spectrum of the nitride phosphor obtained in Example 3 provided by the present invention when the monitoring wavelength is 621 nm.

Detailed ways

The following are examples and implementations of the present invention, just to illustrate the nitride phosphor and its preparation method involved in the present invention, but the present invention is not limited to the implementation steps and implementations.

Example 1

Select the batching point m=0.02, put CaSi alloy with a purity of not less than 99.5% (molar ratio 1:1), α-Si ₃ N ₄ powder, Eu ₂ O ₃ molar ratio 196:101:2, in the In a mortar, use n-hexane as the dispersion medium, fully grind until uniform, dry, and press into tablets. Then load it in a graphite furnace, under the protection of _N2 atmosphere at 5 atmospheres, heat up to 1400°C for sintering for 4 hours and then cool with the furnace. The final specific expression of the obtained nitride is 0.653Ca ₃ N ₂ •1.667Si ₃ N ₄ :0.04Eu ²⁺ . The position of the main emission peak of the prepared nitride material is at 609nm.

Example 2

Select the batching point m=0.02, put the CaSi alloy with a purity of not less than 99.5% (the molar ratio is 1:1), α-Si ₃ N ₄ powder, and EuSi with a molar ratio of 49:25:1, and put them in the mortar , with n-hexane as the dispersion medium, fully ground until uniform, and dried. Then load it in a graphite furnace, and carry out powder sintering under the protection of N ₂ atmosphere at 5 atmospheres, heat up to 1400°C for 4 hours and then cool down with the furnace. The final specific expression of the obtained nitride is 0.653Ca ₃ N ₂ •1.667Si ₃ N ₄ :0.04Eu ²⁺ . The position of the main emission peak of the prepared nitride material is at 610nm.

Example 3

Select the batching point m=0.02, put the SrSi alloy with a purity of not less than 99.5% (the molar ratio is 1:1), α-Si ₃ N ₄ powder, and EuSi with a molar ratio of 49:25:1, and put them in the mortar , with n-hexane as the dispersion medium, fully ground until uniform, dried, and pressed into tablets. Then load it in a graphite furnace, under the protection of _N2 atmosphere at 5 atmospheres, heat up to 1400°C for sintering for 4 hours and then cool with the furnace. The final specific expression of the obtained nitride is 0.653Sr ₃ N ₂ •1.667Si ₃ N ₄ :0.04Eu ²⁺ . The position of the main emission peak of the prepared nitride material is at 621nm.

Example 4

Select the batching point m=0.02, mix SrSi alloy with a purity of not less than 99.5% (molar ratio is 1:1), SrF ₂ , α-Si ₃ N ₄ powder, and EuSi in a molar ratio of 192:4:101:4, Put it in a mortar, use n-hexane as the dispersion medium, fully grind until uniform, dry, and press into tablets. Then load it in a graphite furnace, under the protection of _N2 atmosphere at 5 atmospheres, heat up to 1400°C for sintering for 4 hours and then cool with the furnace. The final specific expression of the obtained nitride is 0.639Sr ₃ N ₂ •1.667Si ₃ N ₄ :0.040SrF ₂ :0.04Eu ²⁺ . The position of the main emission peak of the prepared nitride material is at 620nm.

Claims (7)

1. alkaline earths Nitride phosphor, it is characterized in that: chemical general formula does

xM ₃N ₂·aSi ₃N ₄·bMY ₂:mR

Wherein, M is wherein one or more of Mg, Ca, Sr, Ba; Y is one or more among F, Cl, the Br; The R representative is selected from one or more among rare-earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm, the Yb; Wherein 0.3 < x < 1,0.1 < a < 2,0 <b < 0.1,0.005 < m < 0.5.

2. a method of making the described alkaline earths Nitride phosphor of claim 1 is characterized in that

(1), Ca, Mg, Sr, Ba, get its simple substance or binary, ternary alloy or its halogenide are raw material, Si powder or Si are taken from the silicon source ₃N ₄It is raw material that powder, rare earths material are got its simple substance, oxide compound or its alloy, takes by weighing corresponding said raw material according to the composition and the stoichiometry of the chemical general formula of the said alkaline earths Nitride phosphor of claim 1;

(2), the mode of the said raw material of step 1 through hand lapping or ball milling mixed;

(3), the described mixture of step 2 is carried out high temperature sintering in graphite furnace under high pressure nitrogen; Pass through last handling process again, can prepare the Nitride phosphor that the present invention relates to.

3. according to the method for manufacture of the said alkaline earths Nitride phosphor of claim 2, it is characterized in that: in said step (3), sintered form is powder sintering or compressing tablet sintering processing.

4. according to the method for manufacture of the said alkaline earths Nitride phosphor of claim 2; It is characterized in that: in said step (3); Can selectivity carry out one or many presintering, purpose makes raw material reach low pressure nitriding and nitrogenize in advance, and pre-sintering temperature is 500～1000 ℃.

5. according to the method for manufacture of the said alkaline earths Nitride phosphor of claim 2, it is characterized in that: in said step (3), the heat preservation sintering temperature is 1100 ℃～1800 ℃.

6. according to the method for manufacture of the said alkaline earths Nitride phosphor of claim 2, it is characterized in that: in said step (3), sintering time is 1～12 hour.

7. according to the method for manufacture of the said alkaline earths Nitride phosphor of claim 2, it is characterized in that: in said step (3), nitrogen pressure is 0.1～1MPa.

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