CN106318381A - A kind of Mn4+ doped hydrogen fluoride nano-red light material and preparation method thereof - Google Patents

Abstract

The invention discloses a Mn<4+>-doped sodium bifluoride red light material and a method for preparing the same. Chemical composition of the Mn<4+>-doped sodium bifluoride red light material is NaHF<2>:Mn<4+>. The Mn<4+>-doped sodium bifluoride red light material is made of raw materials including 15-30 mL of HF (with the concentration of wt 40%), 1*10<-4>-9*10<-4> mol of K<2>MnF<6> solid and 0.01-0.1 mol of NaF. The method includes adding the raw materials into deionized water to obtain liquid with the total volume of 40 mL; carrying out stirring reaction on the liquid at the normal temperature for 0.5-2 hours; carrying out suction filtration on reaction products; naturally drying the reaction products at the normal temperature to obtain white powder. The Mn<4+>-doped sodium bifluoride red light material and the method have the advantages that bright red light can be emitted by the Mn<4+>-doped sodium bifluoride red light material under ultraviolet lamps, the maximum excitation bands of the Mn<4+>-doped sodium bifluoride red light material can be completely matched with spectra of blue light emitted by blue light chips of white light LEDs, and an emission spectrum of the Mn<4+>-doped sodium bifluoride red light material comprises seven red light emission peaks positioned at four locations of 595-643 nm; the Mn<4+>-doped sodium bifluoride red light material can be possibly applied to a white light LED with two fundamental colors, so that color rendering indexes of the white light LED can be increased; the Mn<4+>-doped sodium bifluoride red light material does not contain rare earth, the method is simple, and accordingly the Mn<4+>-doped sodium bifluoride red light material and the method are applicable to industrial production.

Description

A kind of Mn4+ doped hydrogen fluoride nano-red light material and preparation method thereof

technical field

The present invention relates to luminescent materials, in particular to a red light material that can be used in white light LEDs and a preparation method thereof; in particular to a Mn ⁴⁺ doped hydrogen fluoride sodium whose excitation wavelength is in the blue light region and emission wavelength is in the red light region Luminescent material and its preparation method.

Background technique

White light LED is the fourth generation of light source after incandescent lamp and fluorescent lamp, and is recognized as a new light source in the 21st century. Because of its advantages of high efficiency, energy saving, environmental protection, long life and small size, it is widely used in various fields such as lighting, communication and display. It not only provides a perfect backlight solution for manufacturers, but also provides economical and high-quality light sources for general lighting. Today's market-leading white LED products are packaged with yellow phosphor YAG:Ce and blue LEDs. White LEDs are obtained through complementary color matching of yellow and blue. Compared with traditional energy-saving lamps, this type of white LEDs has a lower color rendering index in low color temperature regions. , unable to meet large-scale lighting needs, the reason is that there are only yellow and blue components in the white light, and less red components.

In order to improve the color rendering index of white LEDs composed of yellow phosphor YAG:Ce and blue chips, it is more effective and practical to mix red nitride phosphors into YAG:Ce. Divalent europium-doped nitride systems such as Sr _2‐x‐y Ba _x Ca _y Si ₅ N ₈ :Eu ²⁺ are commonly used in red light materials for dichroic WLEDs that can be commercially applied. High stability, absorption bandwidth, high color purity, high luminous efficiency, and no obvious temperature quenching, which can effectively optimize the color rendering index and color temperature of dichroic WLEDs. The quantum efficiency reaches 80% under 465nm excitation, and the luminous intensity is at 150°C. Only a few percent lower [XQPiao, T.Horikawa, H.Hanzawa, K.Machida, "Characterization and luminescence properties of Sr ₂ Si ₅ N ₈ : Eu ²⁺ phosphor for white light‐emitting‐diodeillumination", Appl.Phys. Lett.88(2006)161908.YQLi, De With G, HTHintzen, "The effect of replacement of Sr by Ca on the structural and luminescence properties of the red‐emitting Sr ₂ Si ₅ N ₈ :Eu ²⁺ LED conversion phosphor", J . Solid State Chem. 181(2008) 515‐524.]. Since the raw materials such as alkaline earth nitride and silicon nitride used to prepare the red light materials of this system are very expensive, and the whole process of mixing and preparation needs to avoid water and oxygen, the price of nitride red light materials is high. The Mn ⁴⁺ doped red light material has aroused great interest because its excitation wavelength in the composite aluminate and composite fluoride is in the near-ultraviolet to blue light region, which is exactly the same as that of semiconductor-based violet light. Matching the electroluminescence wavelength of blue LED, it can effectively absorb the purple light and blue light of the LED chip, and its emission spectrum has a sharp peak in the red light region. The efficiently emitted red light can effectively improve the color rendering index of WLED, and obtain low color temperature and high Color rendering warm white light. The luminescent properties of Mn ⁴⁺ with wide excitation band and narrow emission band are especially beneficial for lighting applications. Therefore, the LED industry expects Mn ⁴⁺ doped red materials to replace commercial nitride red powders with harsh synthesis conditions and scarce raw materials.

The Mn ⁴⁺ doped fluorogermanate red phosphor powder invented by Philips in the 1920s has high luminous efficiency and high color purity [G. Kemeny, CH Haake, "Activator center in magnesium fluorogermanate phosphors", J. Chem. Phys. 33(1960)783.], but the price is expensive (because the raw material contains GeO ₂ ), so the red powder is currently only used in special fluorescent lamps to improve its color rendering index, and its excitation spectrum is in the near ultraviolet region, which is not suitable for the market The dominant blue chip-based LED. Phosphor powder CaAl ₁₂ O ₁₉ :Mn ⁴⁺ can emit red light under the excitation of near-ultraviolet light and blue light. Theoretically, this powder can be potentially applied to LED, but its luminous efficiency still needs to be improved[T.Murata, T.Tanoue, M.Iwasaki, K.Morinaga, T.Hase, "Fluorescence properties of Mn ⁴⁺ inCaAl ₁₂ O ₁₉ compounds as red-emitting phosphor for white LED", J.Lumin.114(2005)207; YXPan, GKLiu, "Enhancement of phosphor efficiency via composition modification", Opt. Lett.33 (2008) 1], recently used anion exchange method to efficiently synthesize and study the red light material K ₂ TiF ₆ :Mn ⁴⁺ , and its light efficiency is as high as 98 %, after K ₂ TiF ₆ :Mn ⁴⁺ and yellow-green phosphor YAG:Ce are co-packaged in the blue LED chip, low color temperature (3088K), high color rendering (CRI=90), and high efficiency (82%) are obtained. Warm white WLED[HMZhu,CCLin,WQLuo,STShu,ZGLiu,YSLiu,JTKong,E.Ma,YGCao,RSLiu,XYChen,"Highly efficient non‐rare‐earth red emitting phosphor for warmwhite light‐emitting diodes", Nat. Commun.5 (2014) 4312.]. Japanese researchers have synthesized a series of Mn ⁴⁺ doped composite fluoride red light materials and studied their luminescent properties, but the synthesis method is more complicated, and the raw materials used are expensive (pure metal), and the concentration of the etching solution used is very high (40% HF aqueous solution), high concentration of KMnO ₄ (prone to non-luminous by-products, such as MnO ₂ ) [S.Adachi, T.Takahashi, "A yellow phosphor K ₂ SiF ₆ activated by Mn ²⁺ ion", J.Appl. Phys.108(2010)063506; R.Kasa, S.Adachi, "Mn‐activated K ₂ ZrF ₆ andNa ₂ ZrF ₆ phosphors: Sharp red and oscillatory blue‐green emissions", J.Appl.Phys.112(2012) 013506.; S. Adachi, T. Takahashi, "Photoluminescence and Raman scattering spectroscopies of Ba SiF ₆ :Mn ⁴⁺ red phosphor", J.Appl.Phys.106(2009)013516.].

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of the prior art, and provide an inorganic red light material for two-primary-color white light LED that can be effectively excited by the blue light of the GaN chip and emit red light, and a preparation method thereof.

The purpose of the present invention is achieved through the following technical solutions:

A Mn ⁴⁺ -doped hydrogen fluoride nano-red light material: the material uses NaHF ₂ as the matrix, Mn ⁴⁺ as the luminescence center, the chemical composition is NaHF ₂ :Mn ⁴⁺ , and the molar doping concentration of Mn ⁴⁺ is NaHF 0.1% to 1.0% of ₂ ; Mn ⁴⁺ partially replaces Na ⁺ and H ⁺ , and forms negative electron holes to keep the charge in the crystal neutral.

Preferably, the molar doping concentration of Mn ⁴⁺ is 0.4%-0.6% of NaHF ₂ .

The hydrogen fluoride nano-red light material is a white powder with uniform light emission, the maximum excitation wavelength is in the blue light region, and the emission wavelength is accompanied by the red light region. Specifically, the product invents bright red light under ultraviolet light. The excitation spectrum of this material consists of three broadbands located at 250nm, 350nm, and 460nm respectively. It consists of 7 sharp peaks located at 593nm, 605nm, 608nm, 616nm, 626nm, 630nm and 642nm, the highest peak is located at 626nm. The color coordinates of the emitted light are located at: x=0.66; y=0.33, very close to the color coordinates of CIE standard red light.

The preparation method of the Mn ⁴⁺ doped hydrogen fluoride nano-red light material: dissolve K ₂ MnF ₆ solid in HF aqueous solution, add NaF solid, add deionized water, stir and react at room temperature for 0.5 to 2 hours, suction filter, Dry naturally at room temperature to obtain the white powder target material; the molar ratio of K ₂ MnF ₆ to NaF is 0.001-0.09:1.

To further realize the object of the present invention, preferably, the mass concentration of the HF solution is 40%.

Preferably, the amount of HF aqueous solution added per 0.01-0.1 mol of NaF is 15-30 mL.

Preferably, the reaction time is 1-2 hours.

Preferably, the deionized water added per 0.01-0.1mol NaF is 10-25mL.

In the present invention, the combination of this material and the developed Mn ⁴⁺ -doped composite fluoride A ₂ XF ₆ :Mn ⁴⁺ (A=K, Na, Cs; X=Si, Ge, Zr, Ti) red light material Different, these red light materials have cations with the same +4 valence as Mn ⁴⁺ in the matrix, such as Si ⁴⁺ , Ge ⁴⁺ , Zr ⁴⁺ , Ti ⁴⁺ , and Mn ⁴⁺ partially replaces the cation site and Red light is emitted, and the preparation of these materials often requires hydrothermal (heat and pressure) conditions. There is no +4-valent cation in the base NaHF ₂ , but NaHF ₂ :Mn ⁴⁺ can emit light, and the luminous efficiency reaches 88%. It can be inferred that Mn ⁴⁺ partially replaces Na ⁺ and H ⁺ , and forms negative electron holes to keep the charges in the crystal neutral. The whole reaction is carried out at room temperature.

Compared with the prior art, the present invention has the following advantages and effects:

(1) Compared with the known tetravalent manganese-doped aluminate, the present invention does not require high-temperature sintering, because the whole process is carried out in the air at normal temperature, and the material is uniformly dispersed due to no sintering; the maximum emission of the present invention Po grows in the region of blue light, so it can absorb blue light more effectively, and because of the narrow peak emission of Mn ⁴⁺ , it makes red light more pure.

(2) Compared with the developed Mn ⁴⁺ -doped composite fluoride A ₂ XF ₆ :Mn ⁴⁺ red light material, the present invention only needs 3 kinds of raw materials: K ₂ MnF ₆ , HF and NaF, and does not require positive four Valence metal raw materials, so the raw materials are simple, and the whole synthesis process is carried out at room temperature, which can be mass-produced.

(3) Because the material does not contain rare earth, the preparation process does not need to avoid water and oxygen, and does not need high-temperature sintering. Therefore, the cost is much lower than that of commercial nitride red powder.

Description of drawings

Figure 1 shows the XRD standard card data of NaHF ₂ :Mn ⁴⁺ (Example 1) and the XRD pattern of the example product.

Fig. 2 EDS (energy spectrum distribution) diagram of NaHF ₂ :Mn ⁴⁺ (Example 1).

Fig. 3 Excitation spectrum (a: monitoring wavelength is 626nm) and emission spectrum (b: excitation wavelength is 460nm) of NaHF ₂ :Mn ⁴⁺ (Example 1).

detailed description

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the protection scope of the present invention is not limited to the range indicated by the embodiments.

Example 1

In a plastic container, dissolve 0.1235g (5×10 ^‐4 mol) K ₂ MnF ₆ solid material in 20mL HF (concentration: wt40%), then add 2.1g (0.05mol) NaF as raw material, add deionized water to make The total volume was 40 mL, stirred and reacted at room temperature for 1.5 hours, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product glows red under a UV light. Its XRD (detected by Bruker D8 Advance X-ray diffractometer) is shown in Figure 1. XRD shows that the product is a pure NaHF ₂ phase, and a small amount of doping with Mn ⁴⁺ has no obvious influence on the phase. As shown in Figure 2, the energy spectrum analysis is measured on the Nova NanoSEM 200. Under the action of the electron beam, the energy spectrum analysis shows elements: Na, F and Mn, and H cannot be displayed because the mass is too small, and the obtained product can be seen The composition is NaHF ₂ :Mn ⁴⁺ . As shown in Figure 3, the luminescence performance of the product was detected at room temperature using a Fluoromax‐4 fluorescence spectrometer (HORIBA Jobin Yvon Inc.). , its largest excitation band (460nm) completely matches the blue light emitted by the GaN blue light chip, and the emission spectrum is composed of 7 peaks at 593nm, 605nm, 608nm, 616nm, 626nm, 630nm and 642nm, the highest peak is at 626nm . The particles of the product are relatively uniform, and its particle size and range distribution are also suitable for the application of coating pipes. The product does not contain rare earth, has a simple preparation method and is suitable for industrial production.

Example 2

In a plastic container, dissolve 0.0988g (4×10 ^‐4 mol) K ₂ MnF ₆ solid material in 30mL HF (concentration: wt40%), then add 0.42g (0.01mol) NaF as raw material, add deionized water to make The total volume was 40 mL, stirred and reacted at room temperature for 0.5 hour, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product glows red under a UV light. The XRD pattern, SEM pattern and fluorescence spectrum of the white powder material are basically the same as those in Figure 1-3.

Example 3

In a plastic container, dissolve 0.1482g (6×10 ^‐4 mol) K ₂ MnF ₆ solid material in 15mL HF (concentration: wt40%), then add 3.36g (0.08mol) NaF as raw material, add deionized water to make The total volume was 40 mL, stirred and reacted at room temperature for 1 hour, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product glows red under a UV light. The XRD pattern, SEM pattern and fluorescence spectrum of the white powder material are basically the same as those in Figure 1-3.

Example 4

In a plastic container, dissolve 0.0247g (1×10 ^‐4 mol) K ₂ MnF ₆ solid material in 18mL HF (concentration: wt40%), then add 2.52g (0.06mol) NaF as raw material, add deionized water to make The total volume was 40 mL, stirred and reacted at room temperature for 2 hours, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product glows red under a UV light. The XRD pattern, SEM pattern and fluorescence spectrum of the white powder material are basically the same as those in Figure 1-3.

Example 5

In a plastic container, dissolve 0.2223g (9×10 ^‐4 mol) K ₂ MnF ₆ solid material in 25mL HF (concentration: wt40%), then add 4.2g (0.1mol) NaF as raw material, add deionized water to make The total volume was 40 mL, stirred and reacted at room temperature for 1.8 hours, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product glows red under a UV light. The XRD pattern, SEM pattern and fluorescence spectrum of the white powder material are basically the same as those in Figure 1-3.

Example 6

In a plastic container, dissolve 0.1235g (5×10 ^‐4 mol) K ₂ MnF ₆ solid material in 25mL HF (concentration: wt40%), then add 2.94g (0.07mol) NaF as raw material, add deionized water to make The total volume was 40 mL, stirred and reacted at room temperature for 1.6 hours, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product glows red under a UV light. The XRD pattern, SEM pattern and fluorescence spectrum of the white powder material are basically the same as those in Figure 1-3.

It can be seen from the above examples that compared with the known tetravalent manganese-doped aluminate, the present invention does not require high-temperature sintering, because the whole process is carried out in the air at normal temperature, and the material is uniformly dispersed in shape due to no sintering; the present invention It is invented that the maximum emission grows in the area of blue light, so it can absorb blue light more effectively, and because of the narrow peak emission of Mn ⁴⁺ , the red light is more pure.

Compared with the developed Mn ⁴⁺ -doped composite fluoride A ₂ XF ₆ :Mn ⁴⁺ red light material, the present invention only needs 3 kinds of raw materials: K ₂ MnF ₆ , HF and NaF, and does not need tetravalent metal raw materials , so the raw materials are simple, and the whole synthesis process is carried out at room temperature, which can be mass-produced.

Because the material does not contain rare earths, the whole preparation process is carried out in the air, without avoiding water and oxygen, and without high-temperature sintering. Therefore, the cost is much lower than that of commercial nitride red powder.

Claims (8)

1. A kind of Mn ⁴⁺ doped hydrogen fluoride nano-red light material, it is characterized in that: this material is with NaHF ₂ as matrix, with Mn ⁴⁺ as luminescent center, chemical composition is NaHF ₂ :Mn ⁴⁺ , Mn ⁴⁺ The molar doping concentration is 0.1% to 1.0% of NaHF ₂ ; Mn ⁴⁺ partially replaces Na ⁺ and H ⁺ , and forms negative electron holes to keep the charges in the crystal neutral. 2. The Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 1, characterized in that: the molar doping concentration of the Mn ⁴⁺ is 0.4%-0.6% of that of NaHF ₂ . 3. The Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 1, characterized in that: the hydrogen fluoride nano-red light material is a white powder with uniform light emission, the maximum excitation wavelength is in the blue light region, and the emission wavelength is in the red light region. Region; the color coordinates of the emitted light are located at: x=0.66, y=0.33, very close to the color coordinates of CIE standard red light. 4. The preparation method of Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 1, characterized in that: K ₂ MnF ₆ solid is dissolved in HF aqueous solution, NaF solid is added, deionized water is added, and stirred at normal temperature React for 0.5-2 hours, filter with suction, and dry naturally at room temperature to obtain the white powder target material; the molar ratio of K ₂ MnF ₆ to NaF is 0.001-0.09:1. 5. The preparation method of Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 4, characterized in that: the mass concentration of the HF solution is 40%. 6. The preparation method of Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 5, characterized in that the amount of HF aqueous solution added per 0.01-0.1 mol of NaF is 15-30 mL. 7. The preparation method of Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 4, characterized in that: the reaction time is 1-2 hours. 8. The preparation method of Mn ⁴⁺ doped hydrogen fluoride nano-red light material according to claim 4, characterized in that: the deionized water added per 0.01-0.1mol NaF is 10-25mL.