阅读说明：本技术 一种基于高机械化合成含稀土光电功能铝酸盐的新途径 (Novel approach for synthesizing rare earth-containing photoelectric functional aluminate based on high mechanization ) 是由 王金淑 蔡永丰 胡鹏 宋宁宁 杨韵斐 周文元 周帆 刘乐奇 刘赫雄 张强 胡志凯 于 2021-08-27 设计创作，主要内容包括：一种基于高机械化合成含稀土光电功能铝酸盐的新途径,属于无机光电功能材料的制备领域。本发明基于高压消解-冷冻干燥-高温煅烧三步骤,将原料铝源、稀土氧化物和其他原料按比例称量,并混合适量去离子水加入到高压消解罐的聚四氟乙烯内衬中。经过高压消解和冷冻干燥过程,无需后处理直接得到均匀性良好的超细含稀土铝酸盐前驱体。随后,通过管式炉高温煅烧过程,可获得用于电子发射领域和光功能材料领域的含稀土光电功能铝酸盐。该工艺机械化程度高,所有工程量均由设备完成,最大程度的强化了产品的质量控制。同时高压消解过程使高密度差的原料充分混合均匀,消除了传统水洗微溶物流失和热干燥前驱体分布不均匀的现象。(A new approach for synthesizing rare earth-containing aluminate with photoelectric function based on high mechanization belongs to the field of preparation of inorganic photoelectric functional materials. The method is based on three steps of high-pressure digestion, freeze drying and high-temperature calcination, and comprises the steps of weighing raw materials of an aluminum source, a rare earth oxide and other raw materials in proportion, mixing with a proper amount of deionized water, and adding into a polytetrafluoroethylene lining of a high-pressure digestion tank. After high-pressure digestion and freeze drying, the superfine rare-earth-containing aluminate precursor with good uniformity can be directly obtained without post-treatment. Then, the rare earth-containing photoelectric functional aluminate used in the field of electron emission and the field of light functional materials can be obtained through a tubular furnace high-temperature calcination process. The process has high degree of mechanization, all the engineering quantities are completed by equipment, and the quality control of products is strengthened to the greatest extent. Meanwhile, the high-pressure digestion process enables the raw materials with high density difference to be fully and uniformly mixed, and the phenomena of slightly soluble material flow in the traditional washing process and uneven distribution of hot drying precursors are eliminated.)

1. The high-mechanization preparation method of the aluminate with the rare earth photoelectric function is characterized by comprising the following steps:

step A: weighing an aluminum source, a rare earth oxide and carbonate or hydroxide of alkaline earth metal as raw materials in proportion, mixing the raw materials with deionized water, adding the mixture into a polytetrafluoroethylene lining, and then putting the polytetrafluoroethylene lining into a high-pressure digestion tank;

and B: heating the high-pressure digestion tank for 24 hours at the temperature of 180 ℃ plus 200 ℃ by using a blast oven or a homogeneous phase reactor, naturally cooling and taking out after the heat preservation is finished, and transferring the high-pressure digestion tank into a polytetrafluoroethylene beaker;

and C: freezing the liquid phase raw material mixture subjected to high-pressure digestion and a polytetrafluoroethylene beaker together by using liquid nitrogen, putting the frozen solid phase raw material mixture into a freeze dryer which is cooled to the temperature of between 70 ℃ below zero and 80 ℃ below zero in advance to perform a low-temperature vacuum drying process for more than 12 hours, and taking out the solid phase raw material mixture after complete drying to obtain a powder raw material mixture containing the rare earth photoelectric function aluminate without further treatment;

step D: the powder raw material mixture containing the rare earth photoelectric function aluminate is put into a vertical high-temperature tube furnace under nitrogen atmosphere (99.99 percent) to be sintered to 1400-1600 ℃, and is insulated for 1 to 10 hours, and is taken out and ground after being cooled, thus obtaining the rare earth photoelectric function aluminate.

2. The highly mechanized preparation method of rare earth-containing photoelectric function aluminate according to claim 1, wherein in step A, the aluminum source is selected from aluminum hydroxide, aluminum oxide, aluminum nitrate, etc.; the proportions of the raw materials follow the following principles. Al in aluminum source₂O₃The content of (A) is 15-25 mol% of the whole raw material; of rare earth oxidesThe content of the alkaline earth metal carbonate or hydroxide accounts for 1-20 mol% of the whole raw material, and the balance is the alkaline earth metal carbonate or hydroxide.

3. The highly mechanized preparation method of rare earth-containing photoelectric functional aluminate according to claim 1, wherein in the step A, the pressure of the high-pressure digestion tank is 6MPa during the reaction.

4. The highly mechanized preparation method of aluminate with rare earth photoelectric function according to claim 1, wherein in the step B, if the high pressure digestion reaction is carried out by using an air-blast drying oven, the normal temperature stirring is carried out for 24 hours in advance; if a homogeneous reactor is used, the high-pressure digestion reaction is directly carried out without a stirring process.

5. The method for preparing the rare earth-containing photoelectric functional aluminate in a highly mechanized manner according to claim 1, wherein in the step B, the lining of the high-pressure digestion tank and the beaker are made of polytetrafluoroethylene products which are produced under the same quality standard, so as to eliminate the influence of impurities in external equipment on the experiment to the maximum extent.

6. The highly mechanized preparation method of aluminate with rare earth photoelectric function according to claim 1, wherein in step C, because of poor thermal conductivity of polytetrafluoroethylene and high density difference between rare earth oxide and other raw materials, the freezing step adopts a combined process of contact freezing and non-contact freezing of raw material mixture and liquid nitrogen, that is, liquid nitrogen is present inside and outside the polytetrafluoroethylene beaker, the liquid nitrogen in the polytetrafluoroethylene beaker is directly contacted and frozen with the liquid raw material mixture after high pressure digestion, and simultaneously the liquid nitrogen outside the polytetrafluoroethylene beaker is non-contact frozen with the liquid raw material mixture after high pressure digestion.

Technical Field

The invention relates to a high-mechanization preparation method of rare earth-containing aluminate with photoelectric function, belonging to the technical field of preparation of inorganic photoelectric functional materials.

Background

The rare-earth-containing aluminate with high added value is widely applied to the fields of electron emission and optical functional materials, and the interchange between the optical functional aluminate material and the electrical functional aluminate material can be realized by adjusting the components and the preparation process, so that the preparation methods of the two materials have great similarity. At present, the application of rare-earth aluminate in electron emission materials mainly refers to scandium-containing aluminate and scandium-containing yttrium aluminate used in scandium-containing cathodes, and the light-function rare-earth aluminate-containing materials are mainly applied to aspects of LED devices, afterglow luminescence, biological imaging, display and development and the like. The wide application leads the preparation method of the aluminate containing the rare earth photoelectric function to be comprehensively developed.

The method which is most commonly used in the industry at present is a high-temperature solid-phase method, the method has the greatest advantages of rapidness and low price, but the component uniformity of the precursor and the repeatability of the product can not be ensured frequently, and the method is a problem which needs to be solved for the rare-earth-containing aluminate with high added value. Therefore, sol-gel method, hydrothermal method, combustion method, precipitation method and other preparation methods have appeared. However, besides the hydrothermal method, the other methods have complicated steps or harsh reaction conditions, are easy to encounter difficulties in the industrial process, and have not been applied well in the actual production. In the hydrothermal method, water is used as a solvent and a mineralizer, is a medium for transferring pressure, and can promote the dissolution-reprecipitation process of the rare-earth aluminate-containing raw material under certain pressure, so that the morphology, the granularity and the aggregation form of a precursor are improved.

The invention is different from the traditional hydrothermal/digestion method, provides a high-mechanization preparation method of rare earth-containing photoelectric function aluminate based on high-pressure digestion, and the rare earth-containing photoelectric function aluminate is obtained by three steps of high-pressure digestion, freeze drying and high-temperature calcination. Compared with other preparation methods containing rare earth aluminate, the process has high degree of mechanization, all the engineering quantities are completed by equipment, and the quality control of the product is enhanced to the greatest extent. Has very great application prospect in the industrial production of rare-earth aluminate with high added value.

Disclosure of Invention

The invention provides a highly mechanized preparation method of rare earth-containing aluminate with photoelectric function, which is realized by the following steps:

step A: weighing an aluminum source, a rare earth oxide and carbonate or hydroxide of alkaline earth metal as raw materials in proportion, mixing the raw materials with deionized water, adding the mixture into a polytetrafluoroethylene lining, and then putting the polytetrafluoroethylene lining into a high-pressure digestion tank;

and B: heating the high-pressure digestion tank for 24 hours at the temperature of 180 ℃ plus 200 ℃ by using a blast oven or a homogeneous phase reactor, naturally cooling and taking out after the heat preservation is finished, and transferring the high-pressure digestion tank into a polytetrafluoroethylene beaker;

and C: freezing the liquid phase raw material mixture subjected to high-pressure digestion and a polytetrafluoroethylene beaker together by using liquid nitrogen, putting the frozen solid phase raw material mixture into a freeze dryer which is cooled to the temperature of between 70 ℃ below zero and 80 ℃ below zero in advance to perform a low-temperature vacuum drying process for more than 12 hours, and taking out the solid phase raw material mixture after complete drying to obtain a powder raw material mixture containing the rare earth photoelectric function aluminate without further treatment;

step D: the powder raw material mixture containing the rare earth photoelectric function aluminate is put into a vertical high-temperature tube furnace under nitrogen atmosphere (99.99 percent) to be sintered to 1400-1600 ℃, and is insulated for 1 to 10 hours, and is taken out and ground after being cooled, thus obtaining the rare earth photoelectric function aluminate.

In step a of the above invention, the aluminum source is selected from aluminum hydroxide, aluminum oxide, aluminum nitrate, etc.; the proportions of the raw materials follow the following principles. Al in aluminum source₂O₃The content of (A) is 15-25 mol% of the whole raw material; the content of rare earth oxide is 1-20 mol% of the whole raw material, and the rest is carbonate or hydroxide of alkaline earth metal.

In step A of the above invention, the pressure of the high-pressure digestion tank (as shown in FIG. 2) during the reaction is 6MPa, not usually 3 MPa.

In the step B of the present invention, when the high-pressure digestion reaction is carried out using the forced air drying oven, the stirring at room temperature needs to be carried out for 24 hours in advance. If a homogeneous reactor is used, the high-pressure digestion reaction is directly carried out without a stirring process.

In the step B of the invention, the lining of the high-pressure digestion tank and the beaker are made of polytetrafluoroethylene products (as shown in fig. 2) produced under the same quality standard, so as to eliminate the influence of impurities in external equipment on the experiment to the maximum extent.

In the step C of the invention, because the polytetrafluoroethylene has poor thermal conductivity and the rare earth oxide and other raw materials have high density difference, the freezing step adopts the process of the combined action of contact freezing and non-contact freezing of the raw material mixture and liquid nitrogen, namely, the liquid nitrogen is arranged inside and outside the polytetrafluoroethylene beaker, the liquid nitrogen in the polytetrafluoroethylene beaker is directly contacted and frozen with the liquid-phase raw material mixture after high-pressure digestion, and simultaneously, the liquid nitrogen outside the polytetrafluoroethylene beaker is non-contacted and frozen with the liquid-phase raw material mixture after high-pressure digestion.

The invention synthesizes the aluminate containing the rare earth photoelectric function by using a new high-mechanization way, and the prepared precursor containing the rare earth aluminate has uniform components, uniform distribution of rare earth oxide (as shown in figure 3) and no obvious agglomeration phenomenon.

As shown in FIG. 4, the Sc-W cathode composed of the rare earth aluminate-containing material prepared in example 1 has a good electron emission ability. As shown in fig. 5, the rare earth-containing luminescent materials prepared in examples 2 and 3 have good optical properties under ultraviolet excitation, wherein example 2 is orange yellow, and example 3 is orange red. A plurality of embodiments show that the new way of the invention can prepare the aluminate containing the rare earth photoelectric function with good performance, has high mechanization degree and is suitable for large-scale, batch and industrial production.

Drawings

FIG. 1 is a flow chart of an experiment related to the present invention

FIG. 2 is a high pressure digestion tank shell, polytetrafluoroethylene inner liner and polytetrafluoroethylene beaker used in the present invention.

FIG. 3 is a scanning electron microscope picture and an element distribution diagram of a sample of example 2

Fig. 4 is a graph showing the electron emission of a scandium-tungsten cathode composed of rare earth aluminate prepared in example 1.

FIG. 5 is color images of rare earth-containing optical materials prepared in examples 2 and 3 under different light sources.

The specific implementation mode is as follows:

the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

The pressure of the high-pressure digestion tank (shown in FIG. 2) during the reaction was 6 MPa.

Example 1

0.4681g of aluminum hydroxide, 0.5172g of scandium oxide, 3.7858g of barium hydroxide octahydrate and 0.2223g of calcium hydroxide are weighed by an analytical balance, the above substances are mixed with a proper amount of deionized water, stirred for 24 hours and then added into a polytetrafluoroethylene lining, and then the polytetrafluoroethylene lining is placed into a high-pressure digestion tank. And (3) heating the high-pressure digestion tank for 24 hours at 200 ℃ by using a blast oven, naturally cooling and taking out after the heat preservation is finished, and transferring the high-pressure digestion tank into a polytetrafluoroethylene beaker. Freezing the liquid phase raw material mixture subjected to high-pressure digestion and a polytetrafluoroethylene beaker together by using liquid nitrogen, and putting the frozen solid phase raw material mixture into a freeze dryer which is cooled to-76 ℃ in advance to perform a low-temperature vacuum drying process for 13 hours. After the mixture is completely dried, the mixture is taken out and can be obtained without further treatment. And (3) putting the powder raw material mixture into a vertical high-temperature tubular furnace in a nitrogen atmosphere (99.99%) to be sintered to 1500 ℃, preserving the heat for 1 hour, cooling, taking out and grinding to obtain the rare earth-containing photoelectric functional aluminate.

Example 2

0.7802g of aluminum hydroxide, 0.0176g of europium oxide, 4.7322g of barium hydroxide octahydrate and 0.1852g of calcium hydroxide are weighed by an analytical balance, the materials are mixed with a proper amount of deionized water, stirred for 24 hours and then added into a polytetrafluoroethylene lining, and the polytetrafluoroethylene lining is placed into a high-pressure digestion tank. And (3) heating the high-pressure digestion tank for 24 hours at 200 ℃ by using a blast oven, taking out after the heat preservation is finished and naturally cooling, and transferring the high-pressure digestion tank to a polytetrafluoroethylene beaker. And (3) freezing the liquid phase raw material mixture subjected to high-pressure digestion and a polytetrafluoroethylene beaker together by using liquid nitrogen, and putting the frozen solid phase raw material mixture into a freeze dryer which is cooled to-73 ℃ in advance to perform a low-temperature vacuum drying process for 12.5 hours. After the mixture is completely dried, the mixture is taken out and can be obtained without further treatment. And putting the powder raw material mixture into a vertical high-temperature tubular furnace in a nitrogen atmosphere (99.99 percent), sintering to 1500 ℃, preserving the heat for 10 hours, cooling, taking out and grinding to obtain the rare earth-containing photoelectric functional aluminate.

Example 3

0.5098g of alumina, 0.8619g of scandia, 0.0704g of europium oxide, 3.9468g of barium carbonate and 0.5004g of calcium carbonate are weighed by an analytical balance, the materials are mixed with a proper amount of deionized water and then added into a polytetrafluoroethylene lining, and the polytetrafluoroethylene lining is placed into a high-pressure digestion tank. And (3) keeping the temperature of the high-pressure digestion tank for 24 hours at 180 ℃ by using a blast oven, taking out after the heat preservation is finished and naturally cooling, and transferring the high-pressure digestion tank to a polytetrafluoroethylene beaker. Freezing the liquid phase raw material mixture subjected to high pressure digestion and a polytetrafluoroethylene beaker together by using liquid nitrogen, and putting the frozen solid phase raw material mixture into a freeze dryer which is cooled to-78 ℃ in advance to perform a low-temperature vacuum drying process for 15 hours. After the mixture is completely dried, the mixture is taken out and can be obtained without further treatment. And putting the powder raw material mixture into a vertical high-temperature tubular furnace in a nitrogen atmosphere (99.99 percent), sintering to 1500 ℃, preserving the heat for 10 hours, cooling, taking out and grinding to obtain the rare earth-containing photoelectric functional aluminate.