CN105199729A - A kind of NaSrPO4:xEu3+ red fluorescent powder for LED and preparation method thereof - Google Patents

Abstract

The invention discloses a NaSrPO ₄ :xEu ³⁺ red fluorescent powder for LED and a preparation method thereof, belonging to the technical field of luminescent material preparation. The present invention adopts a two-step method (that is, a method combining hydrothermal method and solid-phase method), using (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ as raw materials , to prepare NaSr ₂ Nb ₅ O ₁₅ :xEu ³⁺ red fluorescent powder for LEDs. The method has the advantages of simple and easy-to-obtain raw materials, simple operation, short preparation period, no pollution, and is suitable for industrialized large-scale production. The NaSrPO ₄ :xEu ³⁺ red phosphor powder prepared by the present invention has high purity, good crystallization performance, uniform particle size and good dispersibility, the average particle size is 2-4 μm, the emission wavelength coverage range is 580-700 nm, and the red light color purity Up to 91.3%.

Description

A kind of NaSrPO4:xEu3+ red fluorescent powder for LED and preparation method thereof

technical field

The invention belongs to the technical field of preparation of luminescent materials, and relates to a preparation method of red fluorescent powder, in particular to a preparation method of NaSrPO ₄ :xEu ³⁺ red fluorescent powder for LED.

Background technique

As a new generation of lighting source, LED is widely used in lighting, display and automobile manufacturing due to its low power consumption, no pollution, long service life and many other advantages. LED phosphors can be divided into silicate-based, phosphate-based, borate-based, aluminate-based, etc. according to their matrix. Phosphate matrix materials are a hot topic in current material research. They have the functions of easy crystallization, low synthesis temperature, high conversion efficiency, stable physical and chemical properties, and can withstand high-power electron beam and high-energy ray irradiation. They have broad applications in the field of lighting. prospect.

The traditional synthesis methods of phosphate include solid phase method, hydrothermal synthesis method, chemical deposition method and so on. The preparation of phosphate by solid phase method, due to the high reaction temperature, the particles are easy to agglomerate, the particle size distribution is uneven, it is difficult to obtain spherical particles with regular shape, and there are easy to exist impurity phases, which weakens the luminous efficiency of phosphors. Due to the low reaction temperature of the hydrothermal method, the product prepared in a short reaction time has low phase purity and contains impurities such as various raw materials or intermediate products, which affect the luminescence performance of the phosphor, and prolonging the reaction time greatly reduces the preparation efficiency.

Therefore, it is of great significance to provide a simple and fast method for preparing a phosphate-based phosphor with high purity, uniform particle size distribution, good particle sphericity, and excellent luminescent performance.

Contents of the invention

In order to overcome the above-mentioned defects in the prior art, the object of the present invention is to provide a NaSrPO ₄ :xEu ³⁺ red fluorescent powder for LEDs and a preparation method thereof, which is simple to operate and environmentally friendly; the prepared NaSrPO ₄ :xEu ^{3 +} The red phosphor has high purity, uniform particle size, good crystallization performance and excellent luminous performance.

The present invention is realized through the following technical solutions:

The invention discloses a preparation method of NaSrPO ₄ :xEu ³⁺ red fluorescent powder for LED, which comprises the following steps:

1) According to the molar ratio of (1.3～2):1:(1.1～1.3):(0.01～0.025), (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ as raw materials;

2) Take (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ , add deionized water and stir well to obtain an emulsion, and adjust the pH value of the emulsion to 8-12;

3) Add deionized water to the emulsion prepared in step 2), keep it warm at 150-200°C for 3-16 hours, take it out after cooling and centrifuge, collect the precipitate, wash and dry it to obtain SrHPO ₄ powder;

4) Mix the SrHPO ₄ powder with C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ and grind it evenly to obtain a mixed powder;

5) Put the mixed powder in a box-type resistance furnace, keep it warm at 600-850°C for 3-10 hours, take it out after cooling with the furnace, and grind it to prepare NaSrPO ₄ :xEu ³⁺ red phosphor, where x=0.02～ 0.05.

Step 2) The mass of deionized water added is 3-6 times of the total mass of (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ .

Step 2) is to adjust the pH value of the emulsion with a NaOH solution with a mass fraction of 63% to 69%.

Step 3) is to pour the emulsion into the hydrothermal kettle, and add deionized water into the hydrothermal kettle according to the filling ratio of 60% to 80%.

Step 5) the sintering system in the box-type resistance furnace is as follows:

Raise the temperature to 150-200°C at a rate of 2°C/min, then to 200-600°C at a rate of 3°C/min, and finally to 600-850°C at a rate of 5°C/min, and keep warm for 3-10 hours.

The grinding described in steps 4) and 5) is grinding in an agate mortar for 20-40 minutes.

The invention also discloses the red fluorescent powder for LED prepared by the above method, the chemical composition of the red fluorescent powder is: NaSrPO ₄ :xEu ³⁺ , where x=0.02-0.05.

The average particle diameter of the red fluorescent powder is 2-4 μm, the emission wavelength coverage range is 580-700 nm, and the red light color purity reaches 91.3%.

Compared with the prior art, the present invention has the following beneficial technical effects:

The present invention adopts a two-step method (that is, a method combining hydrothermal method and solid phase method), using (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ as raw materials , to prepare NaSr ₂ Nb ₅ O ₁₅ :xEu ³⁺ red phosphor powder for LEDs. The method has the advantages of simple and easy-to-obtain raw materials, simple operation, short preparation cycle, no pollution, and is suitable for industrialized large-scale production.

The NaSrPO ₄ :xEu ³⁺ (wherein x=0.02～0.05) red phosphor powder prepared by the present invention is tested and analyzed by XRD, SEM and fluorescence spectrophotometer, it can be seen that the NaSrPO ₄ prepared by the two-step method of the present invention: xEu ³⁺ (where x=0.02~0.05) phosphor has high purity, good crystallization performance, uniform particle size and good dispersion, with an average particle size of 2~4μm, emission wavelength coverage of 580~700nm, and red light color purity as high as 91.3%.

Description of drawings

Fig. 1 is the SEM picture of the NaSrPO ₄ :xEu ³⁺ fluorescent powder that embodiment 1 makes;

Fig. 2 is the emission spectrogram of the NaSrPO ₄ :xEu ³⁺ fluorescent powder that embodiment 2 makes;

Fig. 3 is a CIE diagram of the NaSrPO ₄ :xEu ³⁺ phosphor prepared in Example 3.

Detailed ways

The present invention is described in further detail below in conjunction with accompanying drawing:

Example 1

1) According to the molar ratio of 1.5:1:1.2:0.02, weigh an appropriate amount of (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na, and Eu ₂ O ₃ as raw materials;

2) Put the weighed (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ in a beaker, add an appropriate amount (3 times the mass of the mixed powder) deionized water into the beaker and stir well to obtain an emulsified Liquid, select 69wt% NaOH solution, add drop by drop to adjust the pH value of the emulsion to 8;

3) Pour the emulsion obtained in step 2 into a hydrothermal kettle, add an appropriate amount of deionized water into the hydrothermal kettle according to the filling ratio of 60%, keep it at 180°C for 12 hours, take it out after cooling in the furnace, and centrifuge to collect the precipitate Thing, cleaning, drying, obtain SrHPO ₄ powder;

4) Mix the SrHPO ₄ powder obtained in step 3 with the weighed C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ in step 1 and grind them;

5) Put the mixture powder obtained in step 4 in a box-type resistance furnace, raise the temperature to 200°C at a rate of 2°C/min, then raise the temperature to 600°C at a rate of 3°C/min, and finally raise the temperature to 800°C at a rate of 5°C/min ℃, keep it at 800℃ for 6 hours, take it out after cooling in the furnace, and grind to obtain NaSrPO ₄ :xEu ³⁺ red phosphor, where x=0.04).

Referring to Figure 1, it is the SEM image of the NaSrPO ₄ :xEu ³⁺ phosphor prepared in this example. It can be seen from the figure that the particle size of the sample prepared in Example 1 is 1.75um-3um, and the shape is regular , uniform particle size distribution.

Example 2

1) According to the molar ratio of 1.3:1:1.1:0.015, weigh an appropriate amount of (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na, and Eu ₂ O ₃ as raw materials;

2) Put the weighed (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ in a beaker, add an appropriate amount (5 times the mass of the mixed powder) deionized water into the beaker and stir well to obtain an emulsified Liquid, select 69wt% NaOH solution, add drop by drop to adjust the pH value of the emulsion to 10;

3) Pour the emulsion obtained in step 2 into a hydrothermal kettle, add an appropriate amount of deionized water into the hydrothermal kettle according to the filling ratio of 75%, keep it warm at 160°C for 6 hours, take it out after cooling in the furnace, and centrifuge to collect the precipitate Thing, cleaning, drying, obtain SrHPO ₄ powder;

4) Mix the SrHPO ₄ powder obtained in step 3 with the weighed C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ in step 1 and grind them;

5) Put the mixture powder obtained in step 4 in a box-type resistance furnace, raise the temperature to 150°C at a rate of 2°C/min, then raise the temperature to 200°C at a rate of 3°C/min, and finally raise the temperature to 700°C at a rate of 5°C/min ℃, keep it at 700℃ for 9 hours, take it out after cooling in the furnace, and grind to obtain NaSrPO ₄ :xEu ³⁺ red phosphor, where x=0.03.

Referring to Fig. 2, the emission spectrogram of the NaSrPO ₄ :xEu ³⁺ fluorescent powder prepared in this embodiment, as can be seen from the figure, the sample prepared in Example 2 is excited by near-ultraviolet light with a wavelength of 380nm, mainly The emission peak is located at 615nm, which corresponds to the characteristic transition of ⁵ D ₀ → ⁷ F ₂ of Eu ³⁺ . Although there are emission peaks at other positions, their relative intensities are relatively low. It shows that the prepared sample mainly emits red light with a wavelength of 615nm under the excitation of near-ultraviolet light with a wavelength of 380nm.

Example 3

1) According to the molar ratio of 1.9:1:1.3:0.025, weigh appropriate amount of (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na, Eu ₂ O ₃ as raw materials;

2) Put the weighed (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ in a beaker, add an appropriate amount (6 times the mass of the mixed powder) deionized water into the beaker and stir well to obtain an emulsified Liquid, select 69wt% NaOH solution, add drop by drop to adjust the pH value of the emulsion to 11;

3) Pour the emulsion obtained in step 2 into a hydrothermal kettle, add an appropriate amount of deionized water into the hydrothermal kettle according to the filling ratio of 80%, keep it at 150°C for 9 hours, take it out after cooling with the furnace, and centrifuge to collect the precipitate Thing, cleaning, drying, obtain SrHPO ₄ powder;

4) Mix the SrHPO ₄ powder obtained in step 3 with the weighed C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ in step 1 and grind them;

5) Put the mixture powder obtained in step 4 in a box-type resistance furnace, raise the temperature to 180°C at a rate of 2°C/min, then raise the temperature to 400°C at a rate of 3°C/min, and finally raise the temperature to 750°C at a rate of 5°C/min ℃, keep it at 750℃ for 10 hours, take it out after cooling in the furnace, and grind to obtain NaSrPO ₄ :xEu ³⁺ red phosphor, where x=0.05.

Referring to Fig. 3, it is the CIE diagram of the NaSrPO ₄ :xEu ³⁺ phosphor prepared in this example, as can be seen from the figure, the sample prepared in Example 3 emits The color coordinates of red light are located at (0.6138, 0.3569), which is close to the standard red light point, and its color temperature reaches 1150k, which indicates that the prepared sample can emit relatively pure warm red light under the excitation of near-ultraviolet light with a wavelength of 380nm, and can be used in White LEDs for enhanced color temperature.

Example 4

1) According to the molar ratio of 2:1:1.3:0.01, weigh appropriate amount of (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na, Eu ₂ O ₃ as raw materials;

2) Put the weighed (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ in a beaker, add an appropriate amount (3 times the mass of the mixed powder) deionized water into the beaker and stir well to obtain an emulsified Liquid, select 69wt% NaOH solution, add drop by drop to adjust the pH value of the emulsion to 9;

3) Pour the emulsion obtained in step 2 into a hydrothermal kettle, add an appropriate amount of deionized water into the hydrothermal kettle according to the filling ratio of 75%, keep it warm at 200°C for 16 hours, take it out after cooling with the furnace, and centrifuge to collect the precipitate Thing, cleaning, drying, obtain SrHPO ₄ powder;

4) Mix the SrHPO ₄ powder obtained in step 3 with the weighed C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ in step 1 and grind them;

5) Put the mixture powder obtained in step 4 in a box-type resistance furnace, raise the temperature to 160°C at a rate of 2°C/min, then raise the temperature to 500°C at a rate of 3°C/min, and finally raise the temperature to 600°C at a rate of 5°C/min ℃, keep it at 600℃ for 10 hours, take it out after cooling in the furnace, and grind to obtain NaSrPO ₄ :xEu ³⁺ red phosphor, where x=0.02.

Example 5

1) According to the molar ratio of 1.8:1:1.3:0.015, weigh an appropriate amount of (NH ₄ ) ₂ HPO ₄ , Sr(NO ₃ ) ₂ , C ₂ H ₃ O ₂ Na, and Eu ₂ O ₃ as raw materials;

2) Put the weighed (NH ₄ ) ₂ HPO ₄ and Sr(NO ₃ ) ₂ in a beaker, add an appropriate amount (4 times the mass of the mixed powder) deionized water into the beaker and stir well to obtain an emulsified Liquid, select 69wt% NaOH solution, add drop by drop to adjust the pH value of the emulsion to 12;

3) Pour the emulsion obtained in step 2 into a hydrothermal kettle, add an appropriate amount of deionized water into the hydrothermal kettle according to the filling ratio of 80%, keep it at 160°C for 3 hours, take it out after cooling in the furnace, and centrifuge to collect the precipitate Thing, cleaning, drying, obtain SrHPO ₄ powder;

4) Mix the SrHPO ₄ powder obtained in step 3 with the weighed C ₂ H ₃ O ₂ Na and Eu ₂ O ₃ in step 1 and grind them;

5) Put the mixture powder obtained in step 4 in a box-type resistance furnace, raise the temperature to 150°C at a rate of 2°C/min, then raise the temperature to 350°C at a rate of 3°C/min, and finally raise the temperature to 850°C at a rate of 5°C/min ℃, heat preservation at 850°C for 3 hours, take it out after cooling in the furnace, and grind to obtain NaSrPO ₄ :xEu ³⁺ red phosphor, where x=0.03.

Claims (8)

1. a LED NaSrPO ₄: xEu ³⁺the preparation method of red fluorescence powder, is characterized in that, comprises the following steps:

1) by (1.3 ~ 2): 1:(1.1 ~ 1.3): the mol ratio of (0.01 ~ 0.025), get (NH respectively ₄) ₂hPO ₄, Sr (NO ₃) ₂, C ₂h ₃o ₂na and Eu ₂o ₃as raw material;

2) (NH is got ₄) ₂hPO ₄with Sr (NO ₃) ₂, add deionized water and stir, obtained emulsion, regulates pH value to 8 ~ 12 of emulsion;

3) to step 2) add deionized water in obtained emulsion, at 150 ~ 200 DEG C, be incubated 3 ~ 16h, take out centrifugal after cooling, collecting precipitation thing, through cleaning, dry, obtained SrHPO ₄powder;

4) by SrHPO ₄powder and C ₂h ₃o ₂na, Eu ₂o ₃after mixing, grinding evenly, obtained mixed powder;

5) mixed powder is placed in chamber type electric resistance furnace, at 600 ~ 850 DEG C, is incubated 3 ~ 10h, takes out after furnace cooling, grinding, obtained NaSrPO ₄: xEu ³⁺red fluorescence powder, wherein x=0.02 ~ 0.05.

2. a kind of LED NaSrPO according to claim 1 ₄: xEu ³⁺the preparation method of red fluorescence powder, is characterized in that, step 2) add the quality of deionized water for (NH ₄) ₂hPO ₄with Sr (NO ₃) ₂3 ~ 6 times of total mass.

3. a kind of LED NaSrPO according to claim 1 ₄: xEu ³⁺the preparation method of red fluorescence powder, is characterized in that, step 2) be the pH value regulating emulsion by the NaOH solution that massfraction is 63% ~ 69%.

4. a kind of LED NaSrPO according to claim 1 ₄: xEu ³⁺the preparation method of red fluorescence powder, is characterized in that, step 3) be that emulsion is poured in water heating kettle, be 60% ~ 80% in water heating kettle, add deionized water by packing ratio.

5. a kind of LED NaSrPO according to claim 1 ₄: xEu ³⁺the preparation method of red fluorescence powder, is characterized in that, step 5) sintering schedule in chamber type electric resistance furnace is as follows:

With 2 DEG C/min ramp to 150 ~ 200 DEG C, then with 3 DEG C/min ramp to 200 ~ 600 DEG C, finally with 5 DEG C/min ramp to 600 ~ 850 DEG C, insulation 3 ~ 10h.

6. a kind of LED NaSrPO according to claim 1 ₄: xEu ³⁺the preparation method of red fluorescence powder, is characterized in that, step 4) and 5) described in grinding be in agate mortar grind 20 ~ 40min.

7. adopt the LED red fluorescence powder that the method in claim 1 ~ 6 described in any one is obtained, it is characterized in that, the chemical constitution of this red fluorescence powder is: NaSrPO ₄: xEu ³⁺, wherein, x=0.02 ~ 0.05.

8. LED red fluorescence powder according to claim 7, is characterized in that, the median size of the powder of described red fluorescence powder is 2 ~ 4 μm, and emission wavelength coverage is 580 ~ 700nm, and red light color purity reaches 91.3%.