CN102295930A - Hydro-thermal preparation method of yttrium borate europium-doped spherical phosphor powder - Google Patents

Abstract

The invention discloses a hydrothermal preparation method of spherical fluorescent powder doped with yttrium borate and europium. Soluble yttrium salts, europium salts and boric acid were dissolved in deionized water respectively to obtain yttrium ions, europium ions and boric acid concentrations of 0.01 to 1.0 mol/liter. : Mix in a ratio of 1:20 and stir. Add organic morphology inducing reagent malonic acid, the ratio of its molar number to the sum of molar numbers of yttrium ions and europium ions is 3:2, then stir, and adjust the pH of the solution to 8-10 with lye. The prepared solution is transferred into a 100mL reaction kettle for hydrothermal reaction, the hydrothermal temperature is 160-240° C., and the hydrothermal time is 6-48 hours. After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical yttrium borate-doped europium fluorescent powder. The spherical phosphor is composed of secondary lamellar small particles, which is more conducive to the transfer of energy in the entire luminescent system, so that the fluorescent luminous intensity thereof is obviously improved.

Description

A kind of hydrothermal preparation method of yttrium borate-doped europium spherical fluorescent powder

technical field

The invention relates to a preparation method of yttrium borate-doped europium-shaped fluorescent powder, in particular to a hydrothermal preparation method of yttrium borate-doped europium-shaped fluorescent powder.

Background technique

Rare earth borates have become an important aspect in the research of luminescent materials due to their stable physical and chemical properties, relatively low synthesis temperature and excellent luminescent properties. YBO ₃ :Eu ³⁺ is a highly efficient red fluorescent material, and its excitation spectrum in the vacuum ultraviolet (VUV) band has an excitation peak of 140-170nm [Yang Zhi et al. Chemical Journal of Chinese Universities 21 (2000): 1339- 1343]. The fluorescent powder can utilize the received ultraviolet excitation energy with higher efficiency, so its luminous efficiency is better than that of the traditional Y ₂ O ₃ :Eu ³⁺ phosphor [He Ling, Synthesis of red rare earth borate phosphor and its Luminescent Properties Research, Ph.D. Dissertation]. Therefore, YBO ₃ :Eu ³⁺ becomes an ideal red phosphor for plasma flat panel display (PDP).

Factors such as the micro-nano-scale structure, size, and morphology of materials have an important impact on their performance and practical applications. How to control the shape, size and structure of materials is the frontier and focus of current material research [Murry Cet al. J Am Chem Soc 115(1993): 8706-8715]. In order to improve the fluorescence efficiency of YBO ₃ :Eu ³⁺ , it is very important to control its morphology, purity and particle size during the synthesis process. So far, a number of YBO ₃ :Eu ³⁺ phosphors with special morphology have been synthesized, including drum shape, rod shape, spherical shape formed by layer stacking, cake shape, flower ball shape and spherical shape. Compared with other shapes, spherical YBO ₃ : Eu ³⁺ phosphor has higher fluorescence efficiency [Byung Woo Jeoung, Preparation of SphericalPhosphor (Y, Gd) BO ₃ : Eu by Polymeric-Aerosol Pyrolysis J.Electrochem. Soc151, (2004): 213-216]. However, the size and shape of the secondary particles that make up the macroscopic spherical shape also have a non-negligible influence on the luminous intensity and efficiency of the phosphor. In terms of the crystallization characteristics of borate, it is very easy to undergo anisotropic growth to form a two-dimensional sheet structure. The larger the area of the sheet is, the uniformity and intensity of the material's luminescence will be affected. Different from spherical phosphors prepared by other methods, the inducing reagent used in this paper is malonic acid, and the obtained phosphor particles are composed of smaller secondary lamellar particles. As far as the fluorescent powder prepared by the reagent is concerned, its surface is more detailed and close to a spherical shape.

The methods for preparing rare earth borates mainly include solid-phase reaction method, sol-gel method, spray pyrolysis method, combustion method and hydrothermal method, etc. Among them, the hydrothermal method has mild reaction conditions, low reaction temperature, and no obvious crystal defects in the product. , the system is stable and the reaction condition parameters are easier to control.

Contents of the invention

The object of the present invention is to provide a hydrothermal preparation method of yttrium borate-doped europium-doped spherical fluorescent powder, using soluble yttrium salt, soluble europium salt and boric acid as raw materials, utilizing soluble alkali to promote the generation of borate crystals, in boric acid During the formation of salt crystals, the special molecular structure of the organic morphology-inducing reagent is used to induce the formation of complexes between yttrium ions and europium ions, thereby changing the crystallographic orientation and generating yttrium borate doped with europium composed of fine secondary lamellar particles. Spherical phosphor.

The steps of the technical solution adopted in the present invention are as follows:

1) Dissolve soluble yttrium salt, soluble europium salt and boric acid in deionized water respectively, the molar concentrations of yttrium ion, europium ion and boric acid are respectively 0.01-1.0 mol/liter, and stir to obtain a uniform solution;

2) above-mentioned three kinds of solutions are mixed in the ratio of yttrium ion, europium ion and boric acid molar concentration 19:1:20;

3) Stir the mixed solution of step 2);

4) Add malonic acid to the mixed solution in step 3) as an organic morphology-inducing reagent, the ratio of the moles of malonic acid added to the sum of the moles of yttrium ions and europium ions is 3:2, and after the pH of the solution is stabilized Use lye to adjust the pH of the solution to 8-10;

5) Transfer the solution of step 4) into a 100mL reactor for hydrothermal reaction, the hydrothermal temperature is 160-240°C, and the hydrothermal time is 6-48 hours;

6) After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical yttrium borate-doped europium fluorescent powder.

The soluble yttrium salt is nitrate, chloride and acetate of yttrium; the soluble europium salt is nitrate, chloride and acetate of europium.

Described alkali is ammonia water, and concentration is 2.0 mol/liter.

The beneficial effects that the present invention has are:

The present invention adopts a simple and mild hydrothermal synthesis method, which uses soluble yttrium salt, soluble europium salt, boric acid and soluble alkali as raw materials, and introduces an organic morphology inducer malonic acid to synthesize a compound with good dispersibility. Yttrium borate-doped europium spherical phosphor. The spherical phosphor is composed of secondary lamellar small particles. Compared with the phosphor prepared without the introduction of organic morphology-inducing reagents, the spherical surface is more compact due to the smaller size of the secondary particles and weakened anisotropic growth. Fine and compact, closer to a spherical shape. The regular spherical structure is more conducive to the transfer of energy in the entire luminescent system, so that the fluorescence intensity is also significantly improved, which has certain practical value.

Description of drawings

Fig. 1 is the XRD spectrum of the product obtained in Example 1.

Fig. 2 is the EDS collection of illustrative plates of the product obtained in embodiment 1

Fig. 3 is the electron micrograph of the product obtained in embodiment 1.

Fig. 4 is a comparison chart of the fluorescence spectra of the products obtained in Comparative Example and Example 1.

Figure 5 is an electron micrograph of the product obtained in Example 2.

Figure 6 is an electron micrograph of the product obtained in Example 3.

Detailed ways

Comparative example 1:

Dissolve 0.7280g of yttrium nitrate hexahydrate in 19.0mL of deionized water, then dissolve 0.0446g of europium nitrate hexahydrate in 1.0mL of deionized water, and then dissolve 0.1200g of boric acid in 20.0mL of deionized water. Stir to obtain a uniform solution, the concentration of yttrium ion, europium ion and boric acid is 0.1 mol/liter, the above three solutions are mixed, in the mixed solution, the ratio of the molar concentration of yttrium ion, europium ion and boric acid is 19:1:20. Beat for 15 minutes using an electric mixer. Afterwards, the pH of the solution was adjusted to 9.0 with 2.0 mol/L ammonia water. The above solution was transferred into a 100mL reactor for hydrothermal reaction, the hydrothermal temperature was 220°C, and the hydrothermal time was 24 hours. After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical yttrium borate-doped europium fluorescent powder.

Example 1:

Dissolve 0.7280g of yttrium nitrate hexahydrate in 19.0mL of deionized water, then dissolve 0.0446g of europium nitrate hexahydrate in 1.0mL of deionized water, and then dissolve 0.1200g of boric acid in 20.0mL of deionized water. Stir to obtain a uniform solution, the concentration of yttrium ion, europium ion and boric acid is 0.1 mol/liter, the above three solutions are mixed, in the mixed solution, the ratio of the molar concentration of yttrium ion, europium ion and boric acid is 19:1:20. Beat for 15 minutes using an electric mixer. Then add 0.3100 g of malonic acid, and then adjust the pH of the solution to 9.0 with 2.0 mol/liter of ammonia water. The above solution was transferred into a 100mL reactor for hydrothermal reaction, the hydrothermal temperature was 220°C, and the hydrothermal time was 24 hours. After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical yttrium borate-doped europium fluorescent powder. Fig. 1 is the XRD pattern of this product, and this pattern matches with yttrium borate standard XRD data (JCPDS No 16-0277), and the crystal structure of explanation product is identical with yttrium borate. Figure 2 is the energy spectrum of the phosphor, it can be seen that europium ions have indeed been incorporated into the product, and the ratio of the number of yttrium europium ions is consistent with the amount added in the reaction. Fig. 3 is a SEM photo of the product, from which it can be seen that the obtained phosphor powder is spherical, the diameter of the sphere is about 5 microns, and the sphere is composed of finer lamellar particles. It can be seen from the fluorescence spectrum comparison chart in FIG. 4 that the fluorescence intensity of the fluorescent powder obtained in Example 1 at room temperature is significantly better than that of the comparative example, and the intensity is enhanced by 2 to 3 times.

Example 2:

Dissolve 7.2800g of yttrium nitrate hexahydrate in 19.0mL of deionized water, then dissolve 0.4460g of europium nitrate hexahydrate in 1.0mL of deionized water, and then dissolve 1.2000g of boric acid in 20.0mL of deionized water. Stir to obtain a uniform solution, the concentration of yttrium ion, europium ion and boric acid is 1.0 mol/liter, the above three solutions are mixed, in the mixed solution, the ratio of the molar concentration of yttrium ion, europium ion and boric acid is 19:1:20. Stir for 15 minutes using a magnetic stirrer. Then add 3.1000 g of malonic acid, and after stirring for 15 minutes, adjust the pH of the solution to 10.0 with 2.0 mol/liter of ammonia water. The obtained solution was moved into a 100ml reaction kettle, and put into a furnace. The hydrothermal temperature was 160° C., and the hydrothermal time was 48 hours. After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical borate phosphor. Fig. 5 is the SEM photo of the product, it can be seen from the figure that the phosphor powder obtained is spherical, and the sphere is composed of finer lamellar particles, which is similar in appearance to the phosphor powder prepared in Example 1.

Example 3:

Dissolve 0.0728g of yttrium nitrate hexahydrate in 19.0mL of deionized water, then dissolve 0.0045g of europium nitrate hexahydrate in 1.0mL of deionized water, and then dissolve 0.0120g of boric acid in 20.0mL of deionized water. Stir to obtain a uniform solution, the concentrations of yttrium ion, europium ion and boric acid are all 0.01 mol/L, and the above three solutions are mixed and stirred for 15 minutes with a magnetic stirrer. Then add 0.0310 g of malonic acid, and after stirring for 15 minutes, adjust the pH of the solution to 8.0 with 2.0 mol/liter of ammonia water. The obtained solution was moved into a 100ml reaction kettle, and put into a furnace. The hydrothermal temperature was 240° C., and the hydrothermal time was 6 hours. After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical borate phosphor. Fig. 6 is the SEM photograph of the product, it can be seen from the figure that the phosphor powder obtained is spherical, and the sphere is also composed of finer lamellar particles, which is similar to the phosphor powder prepared in Example 1.

Claims (3)

1. a hydrothermal preparation method of yttrium borate-doped europium-doped spherical phosphor, is characterized in that the steps of the method are as follows: 1) Dissolve soluble yttrium salt, soluble europium salt and boric acid in deionized water respectively, the molar concentrations of yttrium ion, europium ion and boric acid are respectively 0.01-1.0 mol/liter, and stir to obtain a uniform solution; 2) above-mentioned three kinds of solutions are mixed in the ratio of yttrium ion, europium ion and boric acid molar concentration 19:1:20; 3) Stir the mixed solution of step 2); 4) Add malonic acid to the mixed solution in step 3) as an organic morphology-inducing reagent, the ratio of the moles of malonic acid added to the sum of the moles of yttrium ions and europium ions is 3:2, and after the pH of the solution is stabilized Use lye to adjust the pH of the solution to 8-10; 5) Transfer the solution of step 4) into a 100mL reactor for hydrothermal reaction, the hydrothermal temperature is 160-240°C, and the hydrothermal time is 6-48 hours; 6) After the hydrothermal reaction, the obtained product is centrifuged and dried to obtain spherical yttrium borate-doped europium fluorescent powder. 2. the hydrothermal preparation method of a kind of yttrium borate-doped europium-doped spherical fluorescent powder according to claim 1, is characterized in that: described soluble yttrium salt is the nitrate of yttrium, chloride salt, acetate; Soluble Europium salts are nitrates, chlorides, and acetates of europium. 3 . The hydrothermal preparation method of a spherical fluorescent powder doped with yttrium borate and europium according to claim 1 , wherein the alkali is ammonia water with a concentration of 2.0 mol/liter. 4 .

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