CN100347267C - Garnet type gadolinium aluminate based fluorescent powder and method for making same - Google Patents

Abstract

A garnet-type gadolinium aluminate-based phosphor and a preparation method thereof, the chemical expression of the phosphor is Gd _3(1-x) Al ₅ O ₁₂ : RE _x or Gd ₃ Al _5(1-x) O ₁₂ : RE _x , where RE is rare earth elements such as Eu, Pr, Ce, Tb, RE can be one or more of rare earth elements, X is the molar weight of doping, 0.01<x<0.1, and its preparation method is according to Stoichiometric ratio Dissolve aluminum nitrate and rare earth oxides in concentrated nitric acid in a container, add an appropriate amount of citric acid to the mixed solution at an amount of 1 to 2 times the molar ratio of citric acid to metal ions, and adjust the pH value of the solution to 3~ 7. Stir and heat at 70-80°C until transparent gel, pre-calcine at 400-500°C, and then calcined at 900-1300°C for more than 1.5 hours. The phosphor powder prepared by the present invention has high color purity, high luminous intensity, The particle size distribution is uniform (the range is 40-100nm), the process is simple and easy, and the raw materials are cheap and easy to obtain.

Description

Garnet-type gadolinium aluminate-based fluorescent powder and preparation method thereof

technical field

The invention belongs to the field of luminescent powder preparation, and in particular relates to a rare earth activated garnet-type gadolinium aluminate-based fluorescent powder and a preparation method.

Background technique

Garnet-type gadolinium aluminate (Gd ₃ Al ₅ O ₁₂ , referred to as GAG) has excellent optical properties, mechanical properties and stable physical and chemical properties, and its application as a new optical matrix material is attracting people's attention. GAG belongs to the tetragonal crystal system, with fast growth rate, relatively small inner core, ideal distribution coefficient for dopants, and large absorption coefficient. Its crystal is an ideal solid-state laser matrix material. The powder doped with other ions (mainly rare earth element ions and transition metal ions) in GAG emits visible light under the excitation of ultraviolet and vacuum ultraviolet light, X-rays and high-energy particles, and is expected to be used in cathode ray tubes (CRT), field Launch flat panel display (FED), plasma flat panel display and other fields to improve device resolution.

As a new material, there is no direct research on the preparation technology of GAG powder, only research on the preparation of GdAlO ₃ (referred to as GAP) and Y ₃ Al ₅ O ₁₂ (referred to as YAG) powder. JWM Verweij et al. synthesized GAP (GdAlO ₃ ) powder (Chemical Physics Letters 239 (1995) 51-55) by solid reaction method, uniformly mixed Gd ₂ O ₃ and Al ₂ O ₃ powders, and heated at a high temperature above 1450°C Carry out heat treatment. This method has a simple process _and is easy to produce _in batches. The disadvantage is that the heat treatment temperature is high, and impurities are easily introduced during the ball milling process _. GAM) and Gd ₃ Al ₅ O ₁₂ (abbreviated as GAG). In recent years, wet chemical methods have been successfully applied to Y ₃ Al ₅ O ₁₂ powder synthesis. Such as "Method for preparing YAG powder" invented by IKEGAMI TAKAYASU et al. "(Patent No. JP200127071.4), using yttrium carbonate and dawsonite as raw materials to make a solution containing carbonate and sulfide ions, forming a precipitate by adjusting the pH value of the solution, and heat-treating the precipitate to obtain a particle size of 40 -400nm single-phase YAG powder. People such as Liu Qian, Luo Lan (application number 310107829.3) use the nitrate aqueous solution of Gd and Al as raw material, take citric acid as gelling agent and spontaneous combustion fuel, and the gel obtained is in Calcined at 800-1300°C to obtain GAP powder with a particle size in the range of 40-100nm.

Contents of the invention

The phosphor powder chemical expression prepared by the present invention is as follows:

Gd _3(1-x) Al ₅ O ₁₂ :RE _x or Gd ₃ Al _5(1-x) O ₁₂ :RE _x

In the formula, RE is a rare earth element (RE is mainly Eu, Pr, Ce, Tb) and other elements, RE can be one or more of rare earth elements), X is the molar weight of doping, 0.01<x<0.1, X=0 When it is pure Gd ₃ Al ₅ O ₁₂ .

The invention adopts the combination of sol-gel process and combustion synthesis process, and prepares phosphor body through the method of complexation and redox reaction between metal nitrate and citric acid.

The preparation process of the present invention is as follows: Aluminum nitrate (Al(NO ₃ ) ₃ 9H ₂ O) and one of the rare earth oxides such as Gd ₂ O ₃ , Eu ₂ O ₃ , Pr ₆ O ₁₁ , and CeO ₂ are mixed according to the stoichiometric ratio. One or more species are dissolved in a container with concentrated nitric acid, and the molar ratio of citric acid to metal ions is 1-2 times, and an appropriate amount of citric acid is added to the mixed solution to adjust the pH value of the solution to 3-7. Place the container containing the mixed solution on a magnetic stirrer, stir and heat at 70-80°C to obtain a transparent gel. Put the gel into a box furnace for pre-calcination at 400-500°C to obtain gray-black precursor powder. The precursor powder is calcined at a temperature of 900-1300° C. for more than 1.5 hours to obtain a light pink final product.

The fluorescent powder prepared by the invention has high color purity, high luminous intensity, uniform particle size distribution (with a range of 40-100nm), simple and easy process, and cheap and easy-to-obtain raw materials.

Description of drawings

Fig. 1 is the fluorescence spectrum of the GAG:Eu nanopowder prepared according to Example 1 under the excitation of ultraviolet light, the abscissa is the wavelength (nm), and the ordinate is the luminous intensity.

Fig. 2 is the fluorescence spectrum of the GAG:Pr nanopowder prepared according to Example 2 under ultraviolet excitation, the abscissa is the wavelength (nm), and the ordinate is the luminous intensity.

Fig. 3 is the fluorescence spectrum of the GAG:Eu, Ce nanopowder prepared according to Example 3 under the excitation of ultraviolet light, the abscissa is the wavelength (nm), and the ordinate is the luminous intensity.

Fig. 4 is the fluorescence spectrum of the GAG:Tb nanopowder prepared according to Example 4 under the excitation of ultraviolet light, the abscissa is the wavelength (nm), and the ordinate is the luminous intensity.

Detailed ways

The present invention will be further described in conjunction with the following examples.

Example 1:

Take 18.75g of aluminum nitrate (Al(NO ₃ ) ₃ 9H ₂ O), 5.439g of gadolinium oxide (Gd ₂ O ₃ ), 0.1056g of europium oxide (Eu ₂ O ₃ ), 33.4g of citric acid, and a sufficient amount of concentrated nitric acid , dissolved in deionized water, stirred to form a homogeneous solution and adjusted to a pH of 7. The beaker containing the solution was placed on a magnetic stirrer, heated to 70°C and kept stirring, and a sol was formed after several hours. Continue stirring and heating until a clear gel forms. Put the gel into a box furnace and heat it to 400 °C to form a gray-black precursor powder. The precursor powder was then calcined at 900° C. for 1.5 hours to obtain a pale pink final product of Gd ₃ Al ₅ O ₁₂ :Eu (5% molGd). Fig. 1 is the fluorescence spectrum of Gd ₃ Al ₅ O ₁₂ :Eu ³⁺ nanopowder excited by ultraviolet light, which shows that the luminescent ion Eu ³⁺ enters the GAG lattice in solid solution form, and emits red fluorescence under the excitation of ultraviolet light (254nm).

Example 2:

Take 18.75g aluminum nitrate (Al(NO ₃ ) ₃ 9H ₂ O), 5.439g gadolinium oxide (Gd ₂ O ₃ ), 0.1016g praseodymium oxide (Pr ₆ O ₁₁ ), 33.4g citric acid, and a sufficient amount of concentrated nitric acid , dissolved in deionized water, stirred to form a homogeneous solution and adjusted to a pH of 3. The beaker containing the solution was placed on a magnetic stirrer, heated to 75°C and kept stirring, and a sol was formed after several hours. Continue stirring to form a transparent gel. Put the gel into a box furnace and heat it to 450°C to form a gray-black precursor powder, and then calcined at 1300°C for 2 hours to finally obtain a light pink final product of Gd ₃ Al ₅ O ₁₂ :Pr (5% molGd). Figure 2 is the fluorescence spectrum of Gd ₃ Al ₅ O ₁₂ :Pr ³⁺ nanopowder excited by ultraviolet light, which shows that the luminescent ion Pr enters the GAG lattice in the form of solid solution, and emits red fluorescence under the excitation of ultraviolet light (254nm).

Example 3:

Take 18.75g of aluminum nitrate (Al(NO ₃ ) ₃ 9H ₂ O), 5.493g of gadolinium oxide (Gd ₂ O ₃ ), 0.1056g of europium oxide (Eu ₂ O ₃ ), 0.0103g of cerium oxide (CeO ₂ ), 33.4g Dissolve citric acid and a sufficient amount of concentrated nitric acid in deionized water, stir to form a uniform solution and adjust the pH value of the solution to 5. The beaker containing the solution was placed on a magnetic stirrer, heated to 80°C and kept stirring, and a sol was formed after several hours. Continue stirring to form a transparent gel. Put the gel into a box furnace and heat it to 450°C to form a gray-black precursor powder. After calcination at 1200°C for 1.5 hours, the final product of Gd ₃ Al ₅ O ₁₂ :Eu, Ce light pink is finally obtained. Fig. 3 is the fluorescence spectrum of Gd ₃ Al ₅ O ₁₂ :Eu, Ce nanopowder excited by ultraviolet light.

Example 4:

Take 18.75g of aluminum nitrate (Al(NO ₃ ) ₃ 9H ₂ O), 5.493g of gadolinium oxide (Gd ₂ O ₃ ), 0.1121g of terbium oxide (Tb ₄ O ₇ ), 33.4g of citric acid, and a sufficient amount of concentrated nitric acid , dissolved in deionized water, stirred to form a homogeneous solution and adjusted to a pH of 4. The beaker containing the solution was placed on a magnetic stirrer, heated to 70°C and kept stirring, and a sol was formed after several hours. Continue stirring to form a transparent gel. Put the gel into a box furnace and heat it to 500°C to form a gray-black precursor powder, and then calcined at 1000°C for 2 hours to finally obtain a light pink final product of Gd ₃ Al ₅ O ₁₂ :Tb. Fig. 4 is the fluorescence spectrum of Gd ₃ Al ₅ O ₁₂ :Tb nanopowder under the excitation of ultraviolet light, which shows that the luminescent ion Tb has solid-dissolved into the GAG lattice, and emits green fluorescence under the excitation of ultraviolet light (254nm).

The stoichiometry of table each embodiment and main parameter contrast example Al(NO ₃ ) ₃ 9H ₂ O Gd ₂ O ₃ Eu ₂ O ₃ Pr ₆ O _{11 CeO2} Tb ₄ O ₇ citric acid pH crystal phase Luminous color 1 18.75 5.439 0.1056 0 0 0 33.4 7 GAG red 2 18.75 5.439 0 0.1016 0 0 33.4 3 GAG red 3 18.75 5.439 0.1056 0 0.0103 0 33.4 5 GAG red 4 18.75 5.439 0 0 0 0.1121 33.4 4 GAG green

Claims (5)

1. A garnet-type gadolinium aluminate-based phosphor, characterized in that the chemical composition formula is: Gd _3(1-x) Al ₅ O ₁₂ :RE _x or Gd ₃ Al _5(1-x) O ₁₂ :RE _x In the formula, RE is a rare earth element, X is the molar weight of doping, and 0.01<x<0.1. 2. The phosphor according to claim 1, wherein the rare earth element is one or more of Eu, Pr, Ce, Tb. 3. The fluorescent powder according to claim 1 or 2, characterized in that the particle size of the powder is 40-100nm. 4. The method for preparing phosphor powder according to claim 1, including sol-forming, gelling, pre-calcining, calcining and other processes, characterized by the combination of sol-gel and combustion synthesis. 5. The method for preparing fluorescent powder according to claim 4, characterized in that aluminum nitrate and rare earth oxides are dissolved in the container with concentrated nitric acid according to the stoichiometric ratio, and the molar ratio of citric acid to metal ions is 1 to 2 times Add citric acid to the mixed solution, adjust the pH value of the solution to 3-7, stir and heat at 70-80°C until transparent gel, pre-calcine at 400-500°C, and then calcined at 900-1300°C for 1.5 hours or more.

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