The rare earth element itself has a rich electronic structure and exhibits many optical, electrical and magnetic properties. After nano-roughing, it exhibits many characteristics, such as small size effect, high specific surface effect, quantum effect, strong light, electricity, magnetic properties, superconductivity, high chemical activity, etc., which can greatly improve the performance and function of materials. , developed many new materials. It will play an important role in high-tech fields such as optical materials, luminescent materials, crystalline materials, magnetic materials, battery materials, electronic ceramics, engineering ceramics, and catalysts. 

Current research and application areas

1. Rare earth luminescent materials: rare earth nano phosphors (color powder, lamp powder), luminous efficiency is improved, which will greatly reduce the amount of rare earth. Mainly used Y2O3, Eu2O3, Tb4O7, CeO2, Gd2O3. New candidate materials for high definition color TVs. 

2. Nano-superconducting materials: YBCO superconductors prepared by Y2O3, special film materials, stable performance, high strength, easy processing, close to practical stage, broad prospects. 

3. Rare earth nano magnetic materials: used for magnetic memory, magnetic fluid, giant magnetoresistance, etc., the performance is greatly improved, so that the device becomes high performance and miniaturization. Such as oxide giant magnetoresistance target (REMnO3, etc.).
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4. Rare-earth high-performance ceramics: electronic ceramics (electronic sensors, PTC materials, microwave materials, capacitors, thermistors, etc.) prepared using ultrafine or nano-sized Y2O3, La2O3, Nd2O3, Sm2O3, etc., electrical properties, thermal properties, Stability has improved a lot and is an important aspect of electronic material upgrades. For example, nano-Y2O3 and ZrO2 sintered ceramics at lower temperature have strong strength and toughness, and are used for wear-resistant devices such as bearings and tools. The performance of multilayer capacitors and microwave devices made of nano-Nd2O3 and Sm2O3 is greatly improved. 

5. Rare earth nanocatalysts: In many chemical reactions, rare earth catalysts are used. If rare earth nanocatalysts are used, catalytic activity and catalytic efficiency will be greatly improved. The current CeO2 nanopowder has the advantages of high activity, low price and long service life in the automobile exhaust gas purifier, and replaces most precious metals, and uses thousands of tons per year.

6. Rare-earth UV absorber: Nano-CeO2 powder is very strong for UV absorption, used in sunscreen cosmetics, sunscreen fiber, automotive glass, etc.

7. Rare-earth precision polishing: CeO2 has a good polishing effect on glass. Nano-CeO2 has high polishing precision and has been used in liquid crystal display, silicon single wafer, glass storage and the like. In short, the application of rare earth nanomaterials has just begun, and it is concentrated in the field of high-tech new materials, with high added value, wide application, great potential, and very promising business prospects. 

Preparation technique

At present, nanomaterials have attracted the attention of all countries, both in production and in application. China's nanotechnology has made continuous progress. In the nano-sized SiO2, TiO2, Al2O3, ZnO2, Fe2O3 and other powder materials, industrial production or trial production has been successfully carried out, but the existing production process, high production cost is fatal. The weakness will affect the promotion and application of nanomaterials, so we must continue to improve.

Due to the special electronic structure and large atomic radius of rare earth elements, the chemical properties are quite different from those of other elements. Therefore, the preparation methods and post-treatment techniques of rare earth nano-oxides are different from other elements. The main research methods are:

1. Precipitation method: including oxalic acid precipitation, carbonic acid precipitation, hydroxide precipitation, homogeneous precipitation, complex precipitation and the like. The biggest feature of this method is that the solution nucleation is fast, easy to control, and the equipment is simple, and a high-purity product can be obtained. But difficult to filter, easy to reunite.

2. Hydrothermal method: Under the condition of high temperature and high pressure, accelerate and strengthen the hydrolysis reaction of ions and form dispersed nanocrystalline core. The method can obtain nano powder with uniform dispersion and narrow particle size distribution, but requires high temperature and high pressure equipment, expensive equipment and unsafe operation.

3. Gel method: It is an important method for preparing inorganic materials and occupies a considerable position in inorganic synthesis. At low temperatures, organometallic compounds or organic complexes form a sol by polymerization or hydrolysis, forming a gel under certain conditions, and further heat-treating to obtain ultra-fine nano-powders with larger specific surface and better dispersion. The method can be carried out under mild conditions, and the obtained powder is larger than the surface and has good dispersibility, but the reaction time is long, and it takes several days to complete, and it is difficult to meet the industrialization requirement.

4. Solid phase method: pyrolysis is carried out by solid compound or intermediate solid phase reaction. For example, rare earth nitrate and oxalic acid, solid phase mixing ball milling, forming an intermediate of rare earth oxalate, and then pyrolysis, to obtain ultrafine powder. The method has high reaction efficiency, simple equipment and easy operation, but the obtained powder has irregular shape and poor uniformity. 

These methods are not unique and may not be fully applicable to industrialization. There are also many preparation methods such as an organic microemulsion method, an alkoxide hydrolysis method, and the like.

Progress in industrial development

Industrialized production often does not use a single method, but complements each other and combines several methods to achieve the high quality, low cost and safe and efficient process required for commercialization. Guangdong Huizhou Ruier Chemical Technology Co., Ltd. has recently made progress in industrialization of rare earth nanomaterials. Through a variety of methods of exploration and numerous experiments, we have found a method suitable for industrial production - microwave gel method, the biggest advantage of this technology is: the original gel reaction of about 10 days, shortened to 1 day, so production efficiency It has been improved by 10 times, the cost has been greatly reduced, and the product quality is good, the surface is larger than the surface, and the user has a good response. The price is 30% lower than that of the US and Japanese products. It is very internationally competitive and reaches the international advanced level. 

Recently, the industrial test by precipitation method is mainly carried out by precipitation with ammonia water and ammonia carbonate, and dehydration with organic solvent and surface treatment. The method is simple in process and low in cost, but the product quality is not good, and there is still some agglomeration, which needs further improvement. improve. 

China is a large country of rare earth resources, the development and application of rare earth nanomaterials, opening up new ways for the effective utilization of rare earth resources, expanding the application range of rare earths, promoting the development of new functional materials, increasing the export of high value-added products, and improving the ability to earn foreign exchange. It has important practical significance to turn resource advantages into economic advantages.