CN101270283A - Gadolinium oxide lutetium phosphor and preparation method thereof - Google Patents

Abstract

The invention discloses a gadolinium oxide lutetium fluorescent powder and a preparation method thereof. The fluorescent powder is a solid solution of Eu ³⁺ doped Gd ₂ O ₃ and Lu ₂ O ₃ , and has a cubic crystal structure. The phosphor powder is prepared by solid-phase sintering method, with high-purity Lu ₂ O ₃ , Gd ₂ O ₃ , Eu ₂ O ₃ powders, accurately weighed, then uniformly mixed, calcined in a muffle furnace with a normal atmosphere, and finally cooled After cooling, a cubic phase Eu ³⁺ doped gadolinium lutetium oxide phosphor can be obtained. The phosphor emits red light under ultraviolet light excitation or x-ray excitation, and can be used in CRT, PDP, LED, FED phosphor and x-ray scintillation materials.

Description

Gadolinium oxide lutetium phosphor and preparation method thereof

technical field

The invention relates to a functional material and its preparation technology, in particular to a fluorescent powder luminescent material and its preparation method.

Background technique

Rare earth ion Eu ³⁺ doped cubic Gd ₂ O ₃ is a very important luminescent and scintillation material. As early as 1964, Bril and Wanmaker studied its luminescent properties, and in recent years it has received widespread attention as a phosphor and thin film material. As a high-efficiency red phosphor, it has important application prospects in plasma imaging, high-definition television, projection television, flat panel display and other fields. As a scintillator, Gd ₂ O ₃ :Eu is a ceramic scintillator with excellent comprehensive performance, which will have a very important application prospect in the fields of high-resolution X-CT, X-ray security inspection imaging equipment and CCD coupled large-area X-ray imaging. Gd ₂ O ₃ has high density (7.64g/cm ³ ) and high effective atomic number (Zeff=64), so its ability to absorb X-rays and γ-rays is very strong, which is between Lu ₂ O ₃ and LuAG (Lu ₃ Al ₅ O ₁₂ ), much higher than Y ₂ O ₃ :Eu and (Y,Gd) ₂ O ₃ :Eu, also higher than Gd ₂ O ₂ S:Pr; the luminous efficiency of Gd ₂ O ₃ :Eu is very High, _its scintillation light output in thin film _state is 18465±5000ph./MeV, which is equivalent to Lu ₂ O ₃ :Eu; The main wavelength of UFC (Gd ₂ O ₂ S:Pr) is at 510nm, the efficiency of the photodiode is only 40% to 50%, and the light detection effect is poor; the afterglow of Gd ₂ O ₃ :Eu is 10-3 when excited by X-rays for 10ms (0.1%), afterglow time can be reduced by adding Tb ³⁺ plasma. In addition, Gd ₂ O ₃ has stable chemical properties and good mechanical properties.

Due to the low price of Gd ₂ O ₃ :Eu raw materials, excellent luminescent performance, and promising market prospects, however, due to the structural phase transition of Gd ₂ O ₃ at 1250°C, Gd ₂ O ₃ has a body-centered cubic structure (C-type) at low temperatures, and high It transforms into a monoclinic structure (type B) at 1250°C, and only the cubic phase Gd ₂ O ₃ :Eu has high luminous efficiency, so a lower temperature is required to obtain the cubic phase Gd ₂ O ₃ :Eu phosphor , and the lower synthesis temperature makes it poor in crystallinity and low in luminous intensity. In order to overcome the phase transition of Gd ₂ O ₃ and synthesize phosphor materials with high luminous intensity at higher temperatures, only Gd ₂ O ₃ is prepared as a precursor for calcination or adding appropriate dopants to inhibit the phase transition. The precursor method increases the synthesis process and increases the cost, and the chemical methods usually used will increase the environmental pollution.

Lu ₂ O ₃ :Eu is another very potential red fluorescent material with excellent performance. However, the raw material of Lu ₂ O ₃ is expensive, and the price remains high, which hinders its market application. However, Lu ₂ O ₃ and cubic Gd ₂ O ₃ have the same crystal structure, and the properties of the compounds formed by rare earth elements are similar, so the study of the solid solution formed by the two is expected to obtain a comprehensive solution with superior luminescence performance and low price. Phosphor material with excellent performance.

Contents of the invention

In the present invention, on the basis of comprehensively considering the performance and price of Lu ₂ O ₃ :Eu and cubic Gd ₂ O ₃ :Eu, the special features of the two substances are brought into play to form a new fluorescent material of gadolinium oxide lutetium solid solution. The purpose of the invention is to Provided are a fluorescent powder material and a preparation method thereof.

The technical scheme that the present invention solves its technical problem adopts is:

1) Gadolinium oxide lutetium phosphor:

The phosphor is a solid solution of Eu ³⁺ doped Gd ₂ O ₃ and Lu ₂ O ₃ , the chemical composition is Gd _2(1-xy) Lu _2x Eu _2y O ₃ , where 0.3≤x≤0.9, 0.01≤y≤ 0.15; the crystal structure of the material is a cubic vacancy fluorite structure, and the space group is Ia3.

Add 0.001wt% to 1wt% of Nd ³⁺ , Tb ³⁺ , and Pr ³⁺ into the Gd _2(1-xy) Lu _2x Eu _2y O ₃ .

2) Preparation method of gadolinium oxide lutetium phosphor:

Phosphor powder is prepared by solid phase sintering method, using Lu ₂ O ₃ , Gd ₂ O ₃ and Eu ₂ O ₃ powders as starting materials, and the chemical composition is Gd _2(1-xy) Lu _2x Eu _2y O ₃ , where 0.3≤x≤0.9, 0.01≤y≤0.15 After weighing, mix evenly, then calcinate in a muffle furnace with a normal atmosphere, and finally cool down to room temperature to obtain Eu ³⁺ doped gadolinium lutetium oxide fluorescence with a cubic phase pink.

The accurately weighed raw materials are mixed in a ball mill for 10-24 hours.

The calcination temperature in the muffle furnace is between 1300°C and 1700°C, and the optimum calcination temperature is 1600°C.

Gadolinium oxide lutetium fluorescent powder of the present invention and preparation method thereof have the following characteristics:

1. The phosphor material of gadolinium oxide lutetium is a solid solution, and its chemical composition can be easily adjusted within a certain range, so as to facilitate the adjustment of the relevant luminous properties of the fluorescent material, such as luminous intensity, decay time, afterglow, etc.

2. In view of the huge difference between the market prices of Gd ₂ O ₃ and Lu ₂ O ₃ , on the premise of satisfying the application, the proportion of Gd ₂ O ₃ can be increased as much as possible when preparing the phosphor, so as to reduce the cost of materials.

3. All components of gadolinium oxide lutetium phosphor materials are rare earth oxides, and the synthesis process adopted is solid-phase synthesis. The materials and processes are environmentally friendly and have development potential.

4. The luminous wavelength of gadolinium oxide lutetium phosphor is at 611nm, the overall light is red, the luminous intensity is higher than that of Lu ₂ O ₃ :Eu and Gd ₂ O ₃ :Eu, and the luminous performance is good

5. Compared with Gd ₂ O ₃ :Eu, gadolinium oxide lutetium phosphor has higher density, high absorption and detection ability for x-rays, and has advantages in the application of x-ray detection materials.

Therefore, the gadolinium oxide lutetium phosphor material obtained in the present invention emits red light under ultraviolet light excitation or x-ray excitation, can be used in CRT, PDP, LED, FED phosphor, and is especially suitable for use as x-ray scintillation detection material.

Description of drawings

Fig. 1 is an x-ray diffraction pattern of a solid-phase reaction product using Lu ₂ O ₃ and Gd ₂ O ₃ as raw materials.

Figure 2 is the ultraviolet excitation luminescence spectra of gadolinium oxide lutetium phosphors containing different Eu ³⁺ .

Figure 3 is the effect of Lu/Re on the luminous intensity of gadolinium lutetium oxide doped with 5at% Eu ³⁺ .

Fig. 4 shows the effect of Eu ³⁺ doping amount on the luminous intensity of gadolinium oxide lutetium with Lu content of 30at%.

Detailed ways

Gadolinium oxide lutetium phosphor is a solid solution of Eu ³⁺ doped Gd ₂ O ₃ and Lu ₂ O ₃ , its chemical composition can be expressed as Gd _2(1-xy) Lu _2x Eu _2y O ₃ , where 0.3≤x≤0.98 , 0.01≤y≤0.15, high-purity Lu ₂ O ₃ , Gd ₂ O ₃ , Eu ₂ O ₃ powders are used as starting materials when synthesizing phosphor materials, and the ratio is made according to this stoichiometric ratio, in order to improve the luminescence of the material Performance (including afterglow characteristics, luminous intensity and decay time, etc.), add 0.001wt% ~ 1wt% of Nd ³⁺ , Tb ³⁺ , Pr ³⁺ when batching, use these rare earth ions to suppress the generation of afterglow, or accelerate Luminous attenuation, of course, if such ions are increased, the luminous intensity of the gadolinium oxide lutetium phosphor will decrease.

After accurate batching, put the mixed raw materials into the ball mill, and mix the materials for 10-24 hours. Increase the mixing time to make the raw materials mix evenly, so that the solid-phase reaction of the raw materials is easier and the various components can fully react.

The method of solid phase sintering is used to prepare phosphor powder. Put the mixed raw materials into an alumina crucible, or in platinum, and calcined in a muffle furnace with a common atmosphere. The calcining temperature is 1300°C-1700°C, the optimum calcining temperature is 1600°C, and the holding time is 2-20 hours. , the optimal holding time is 5 hours. The specific holding time is closely related to the initial raw material, mainly determined by the particle size and specific surface area of the initial raw material. After the calcined raw materials are cooled down, the Eu ³⁺ doped gadolinium lutetium oxide phosphor with cubic phase can be obtained. The cooling process can be controlled by program or by natural cooling.

The X-ray diffraction of the synthesized gadolinium oxide lutetium phosphor shows that the crystal structure of the material is a cubic vacancy fluorite structure, and the space group is Ia3, which is not a new crystal structure. It is Gd ₂ O ₃ and Lu ₂ O The solid solution formed by ₃ has the same structure as the low-temperature cubic phase of Gd ₂ O ₃ and Lu ₂ O ₃ , the difference is only in the lattice parameters. The results of x-ray phase analysis show simultaneously that when the content of Lu ₂ O ₃ is lower than 30 at%, the synthetic product is a mixture of cubic phase and monoclinic phase, which is not the gadolinium oxide lutetium solid solution of the present invention, but when Lu ₂ O ₃ When the content exceeds 30 at%, the synthetic product is a solid solution of gadolinium oxide lutetium, and the result is shown in Figure 1.

The ultraviolet excitation and emission spectrum of Eu ³⁺ doped gadolinium oxide lutetium is shown in Figure 2. Under the excitation of 263nm ultraviolet light, the main wavelength of gadolinium oxide lutetium is in the red band of 611nm, and the luminous intensity of gadolinium oxide lutetium varies with Lu The content in it changes regularly. The influence of Lu/Re on the luminous intensity of gadolinium oxide lutetium doped with 5at% Eu ³⁺ is shown in Figure 3. Re is the total rare earth in the solid solution, including Gd, Lu and Eu, It can be seen that with the increase of the ratio of Lu/Re, that is, the increase of Lu content, the general trend of the total luminous intensity is decreasing.

Eu ³⁺ is the active ion for the luminescence of gadolinium oxide lutetium, which has a great influence on the luminescence of the material. Figure 4 shows the effect of the doping amount of Eu ³⁺ on the luminous intensity of gadolinium lutetium oxide with a Lu content of 30at%. It can be seen that with the increase of Eu ³⁺ , the luminous intensity first increases and then decreases, and the turning point is around ~7%.

Example 1:

Prepare gadolinium oxide lutetium phosphor, its chemical composition can be expressed as Gd _1.3 Lu _0.6 Eu _0.1 O ₃ , high-purity Lu ₂ O ₃ , Gd ₂ O ₃ , Eu ₂ O ₃ powders are used as starting materials for the synthesis of phosphor materials , The raw material comes from Ganzhou, Jiangxi, which is an adsorption type rare earth ore with a purity of 99.99%. The ratio is made according to this stoichiometric ratio. After accurate batching, put the mixed raw materials into the ball mill, and mix the materials for 24 hours. Using the method of solid-state sintering, put the mixed raw materials into an alumina crucible and calcinate in a muffle furnace with a normal atmosphere. The calcining temperature is 1300°C and the holding time is 10 hours. After the calcined raw material is cooled down, the Eu ³⁺ -doped gadolinium lutetium oxide phosphor with cubic phase can be obtained, which is naturally cooled. X-ray diffraction was performed on the synthesized gadolinium oxide lutetium phosphor, and the results showed that the crystal structure of the material was a vacant fluorite structure of the cubic crystal system, and the space group was Ia3, and its ultraviolet excitation and emission spectrum was shown in Figure 2. Under light excitation, the dominant wavelength of gadolinium oxide lutetium is located in the red band of 611nm.

Example 2:

Prepare gadolinium oxide lutetium phosphor, its chemical composition can be expressed as Gd _0.98 Lu _1.0 Eu _0.02 O ₃ , high-purity Lu ₂ O ₃ , Gd ₂ O ₃ , Eu ₂ O ₃ powders are used as starting materials when synthesizing phosphor materials , The raw material comes from Ganzhou, Jiangxi, which is an adsorption type rare earth ore with a purity of 99.99%. The ratio is made according to this stoichiometric ratio. After accurate batching, the mixed raw materials were loaded into a ball mill and mixed for 10 hours. Using the method of solid phase sintering, put the mixed raw materials into an alumina crucible and calcinate in a muffle furnace with a normal atmosphere. The calcining temperature is 1600°C and the holding time is 10 hours. After the calcined raw material is cooled down, the Eu ³⁺ -doped gadolinium lutetium oxide phosphor with cubic phase can be obtained, which is naturally cooled. X-ray diffraction was performed on the synthesized gadolinium oxide lutetium phosphor, and the results showed that the crystal structure of the material was a vacant fluorite structure of the cubic crystal system, and the space group was Ia3, and its ultraviolet excitation and emission spectrum was shown in Figure 2. Under light excitation, the dominant wavelength of gadolinium oxide lutetium is located in the red band of 611nm.

Example 3:

Prepare gadolinium oxide lutetium phosphor, its chemical composition can be expressed as Gd _1.1 Lu _0.6 Eu _0.3 O ₃ , high-purity Lu ₂ O ₃ , Gd ₂ O ₃ , Eu ₂ O ₃ powders are used as starting materials for the synthesis of phosphor materials , The raw material comes from Ganzhou, Jiangxi, which is an adsorption type rare earth ore with a purity of 99.99%. The ratio is made according to this stoichiometric ratio. After accurate batching, the mixed raw materials are loaded into a ball mill and mixed for 20 hours. Using the method of solid-phase sintering, put the mixed raw materials into an alumina crucible and calcinate in a muffle furnace with a normal atmosphere. The calcining temperature is 1700°C and the holding time is 10 hours. After the calcined raw material is cooled down, the Eu ³⁺ -doped gadolinium lutetium oxide phosphor with cubic phase can be obtained, which is naturally cooled. The X-ray diffraction of the synthesized gadolinium oxide lutetium phosphor shows that the crystal structure of the material is a cubic vacancy fluorite structure, and the space group is ^Ia3 . The comparison of materials is shown in Figure 4.

Example 4:

To prepare gadolinium oxide lutetium phosphor, its chemical composition can be expressed as Gd _0.1 Lu _1.8 Eu _0.1 O ₃ , and high-purity Lu ₂ O ₃ , Gd ₂ O 3 , Eu ₂ O ₃ powders are used as starting materials when synthesizing phosphor materials. According to this stoichiometric ratio, the raw material comes from Ganzhou, Jiangxi Province, which is an adsorption type rare earth ore with a purity of 99.99%. In order to improve the luminous performance of the material, 0.001wt% of Pr ³⁺ is added to suppress the afterglow. . After accurate batching, put the mixed raw materials into the ball mill, and mix the materials for 24 hours. Using the method of solid phase sintering, put the mixed raw materials into a platinum crucible and calcinate them in a muffle furnace with an ordinary atmosphere. The calcining temperature is 1500°C and the holding time is 5 hours. After the calcined raw materials are cooled down, they can be obtained Eu ³⁺ doped gadolinium lutetium oxide phosphor with cubic phase.

The X-ray diffraction of the synthesized gadolinium oxide lutetium phosphor shows that the crystal structure of the material is a cubic vacancy fluorite structure, the space group is Ia3, and it is a solid solution formed by Gd ₂ O ₃ and Lu ₂ O ₃ , Gd The ultraviolet excitation and emission spectrum of _0.1 Lu _1.8 Eu _0.1 O ₃ is shown in Figure 2. Under the excitation of 263nm ultraviolet light, the main wavelength of emission of gadolinium lutetium oxide is located in the red band of 611nm.

Claims (5)

1, a kind of gadolinium lutetium oxide fluorescent powder is characterized in that: this fluorescent material is Eu ³⁺Adulterated Gd ₂O ₃With Lu ₂O ₃Sosoloid, chemical constitution is Gd _{2 (1-x-y)}Lu _2xEu _2yO ₃, 0.3≤x≤0.9,0.01≤y≤0.15 wherein; The crystalline structure of this material is the vacant fluorite structure of isometric system, and spacer is Ia3.

2, a kind of gadolinium lutetium oxide fluorescent powder according to claim 1 is characterized in that: described Gd _{2 (1-x-y)}Lu _2xEu _2yO ₃In add the Nd of 0.001wt%～1wt% again ³⁺, Tb ³⁺, Pr ³⁺

3, be used for the preparation method of the described a kind of gadolinium lutetium oxide fluorescent powder of claim 1, it is characterized in that: prepare the method that fluorescent material adopts solid state sintering, adopt Lu ₂O ₃, Gd ₂O ₃And Eu ₂O ₃Powder is a starting raw material, is Gd by chemical constitution _{2 (1-x-y)}Lu _2xEu _2yO ₃, wherein after 0.3≤x≤0.9,0.01≤y≤0.15 weighing, uniform mixing is calcined in the retort furnace of common atmosphere then, drops to the normal temperature cooling at last, obtains the Eu with cube phase ³⁺Adulterated gadolinium lutetium oxide fluorescent powder.

4, the preparation method of a kind of gadolinium lutetium oxide fluorescent powder according to claim 3 is characterized in that: weighing is raw material batch mixing 10～24 hours in ball mill accurately.

5, the preparation method of a kind of gadolinium lutetium oxide fluorescent powder according to claim 3 is characterized in that: the incinerating temperature is at 1300 ℃～1700 ℃ in retort furnace, and optimum calcinating temperature is 1600 ℃.

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