Application and production technology of rare earth nanomaterials

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The earth element itself is rich in electronic structure, showing many characteristics of light, electricity and magnetism. After nanoscaling, the rare earth has many characteristics, such as small size effect, high specific surface effect, quantum effect, very strong light, electricity, magnetic properties, superconductivity, high chemical activity and so on. It can greatly improve the performance and function of the material, and develop a lot of new materials. In the fields of optical materials, luminescent materials, crystal materials, magnetic materials, battery materials, electronic ceramics, engineering ceramics, catalysts and other high-tech fields, it will play an important role. ?

The field of research and application at present

1. rare earth luminescent materials: rare earth nano phosphors (color TV powder, lamp powder), the luminous efficiency is increased, will greatly reduce the amount of rare earth. The main use of Y2O3, Eu2O3, Tb4O7, CeO2, Gd2O3. A new candidate for high definition color TV. ?

2. nano superconducting material: YBCO superconductor, special film material prepared by Y2O3, has stable performance, high strength and easy to process. It is close to the practical stage and has a broad prospect. ?

3. rare earth nano magnetic materials: used for magnetic memory, magnetic fluid, giant magnetoresistance and so on, the performance is greatly improved, making the device become high-performance and miniaturization. Such as oxide giant magnetoresistance target (REMnO3, etc.). ?

4. rare earth high performance ceramics: electronic ceramics (electronic sensors, PTC materials, microwave materials, capacitors and thermistors) prepared by superfine or nanoscale Y2O3, La2O3, Nd2O3, Sm2O3 and so on. The electrical properties, thermal properties and stability have been greatly improved. It is an important aspect of the upgrading of electronic materials. Such as nano Y2O3 and ZrO2 in lower temperature sintered ceramics, it has strong strength and toughness. It is used for wear resistant devices such as bearings and cutting tools. The performance of multilayer capacitors and microwave devices made with nano Nd2O3 and Sm2O3 is greatly improved. ?

5. rare earth nano catalyst: in many chemical reactions, the use of rare earth catalyst, if the use of rare earth nano catalyst, catalytic activity and catalytic efficiency will be greatly improved. The present CeO2 nano powder has the advantages of high activity, low price and long life in automobile exhaust purifier. It has replaced most precious metals and used thousands of tons per year. ?

6. rare earth ultraviolet absorber: nano CeO2 powder absorbs ultraviolet rays very strongly, used for sunscreen cosmetics, sunscreen fiber, automobile glass and so on. ?

7. rare earth precision polishing: CeO2 has better polishing effect on glass and so on. Nano CeO2 has high polishing precision, and has been used in liquid crystal display, silicon single chip, glass storage and so on. In a word, the application of rare earth nanomaterials has just begun, and is concentrated in the field of high-tech materials with high value-added, wide application, great potential and good business prospects. ?

Preparation technology

At present, nanomaterials have attracted much attention both in production and application. Nanoscale technology has made progress in our country. In the powder materials such as nano SiO2, TiO2, Al2O3, ZnO2 and Fe2O3, industrial production or trial production has been successfully carried out. But the existing production process, high production cost is its fatal weakness, which will affect the application of nanomaterials, so it should be constantly improved.

Because of the special electronic structure and large atomic radius of rare earth elements, the chemical properties of rare earth elements are very different from those of other elements. Therefore, the preparation methods and post-processing techniques of rare earth oxides are different from those of other elements. The main research methods are:?

1. precipitation method: including oxalic acid precipitation, carbonate precipitation, hydroxide precipitation, homogeneous precipitation, complex precipitation and so on. The biggest feature of the method is that the solution is fast nucleated, easy to control and simple to produce high purity products. But it is difficult to filter and be easily reunion. ?

2. hydrothermal method: under the condition of high temperature and high pressure, the hydrolysis reaction of ions is accelerated and intensified, and the dispersed nanocrystalline nuclei are formed. The method can obtain nano powder with uniform dispersion and narrow particle size distribution, but requires high temperature and high pressure equipment, and the equipment is expensive and the operation is not safe. ?

3. gel method is an important method to prepare inorganic materials, and occupies a considerable position in inorganic synthesis. At low temperature, organometallic compounds or organic complexes are formed by the reaction of polymerization or hydrolysis to form a sol and form a gel under certain conditions. Further heat treatment can be used to obtain a larger and better dispersible ultrafine nanometer powder than the surface. This method can be carried out under mild conditions, the powder obtained is larger than the surface and good dispersion, but the reaction time is long, it takes several days to complete, and it is difficult to meet the requirements of industrialization. ?

4. solid phase method: high temperature decomposition by solid compound or intermediate solid reaction. Such as nitric acid rare earth and oxalic acid, solid phase mixed ball milling, forming the intermediate of rare earth oxalate, then decomposing at high temperature, and get ultrafine powder. The method has the advantages of high reaction efficiency, simple equipment and easy operation, but the shape of the powder is irregular and the uniformity is poor. ?

These methods are not unique, nor are they entirely applicable to industrialization. There are many preparation methods, such as organic microemulsion, alcohol salt solution and so on. ?

Progress in Industrial Development

Industrial production is often not a single method, but a combination of several methods, which can achieve high quality, low cost and safe and efficient products required by commercialization. Guangdong Huizhou rier Chemical Technology Co., Ltd. has made progress in the development of rare earth nanomaterials recently. After a variety of methods and numerous experiments, the microwave gel method, which is suitable for industrial production, is found. The greatest advantage of this technique is that the gel reaction of the original 10 days is shortened to 1 days.