The rare earth elements have rich electron structures and present many properties of light, electricity and magnetism.  After the nano-crystallization of rare earth, the new features of the rare earth, such as the effect of small size, effect of high surface area, quantum effect, extremely strong light, electricity and magnetism, super conductivity and high chemical activity, etc., can greatly improve the performances and functions of the materials and can be developed more new materials.  The rare earth will play a vital role in the high-tech fields of optical materials, luminescent materials, crystal materials, magnetic materials, battery materials, electronic ceramics, engineering ceramics and catalysts, etc.

1. Current field of research, development and application

1) Rare-earth luminescent materials: rare earth nano phosphor (color powder and phosphor), improves the luminescent efficiency and reduce the consumption of rare earth significantly.  The main elements used include Y2O3, Eu2O3, Tb4O7, CeO2 and Gd2O3. These materials are the new candidate materials for the color TV wit high definition.

2) Nano superconductive materials: the super conductor of YBCO and the special thin-film materials made of Y2O3 are easy to be processes with stable performance and high strength.  The development of such materials is to the stage of actual use with broad prospects.

3) Rare-earth nano magnetic materials: these materials used in the magnetic storage devices, magnetic fluid and colossal magneto-resistance can improve their performance and make the apparatus with high performance and miniaturized, such as the oxide target with colossal magneto-resistance (REMnO3, etc.).

4) Rare-earth ceramics with high performances: the electrical property, thermal property and stability of the electric ceramics (electronic sensor, PTC materials, microwave materials, capacitors and thermal resistors, etc.) prepared and made of superfine or nano Y2O3, La2O3, Nd2O3 and Sm2O3, etc., have been improved greatly, which is the important aspect of the upgrade of the electric materials.  For example, the ceramics sintered with the nano Y2O and ZrO2 under the relatively low temperature have strong strength and toughness and are applied as the wear-resisting instruments, such as bearing and knives, etc.  The performance of the muti-layer capacitors and microwave instruments mad of Nd2O3 and Sm2O3 has been improved significantly.

5) Rare-earth nano catalysts: the rare earth catalysts are used in many chemical reactions.  Using the rare-earth nano catalysts can improve the catalytic activity and efficiency substantially.  The currently used CeO2 nano powder on the purifier of the vehicles exhaust has replaced most of the expensive metals with the advantages of high activity, low price and long useful life and the consumption of such materials has reached thousands tons annually.

6) Rare-earth ultraviolet-light absorber: due to the strong absorption of ultraviolet light by the nano CeO2 powder, it is extensively used in the sunscreen cosmetics, sunscreen fiber and vehicle glass, etc.

7) Rare-earth precise polishing: CeO2 has good polishing effects on the glass.  With the higher polisher precision, the nano CeO2 has been applied in the liquid-crystal displays, silicon single crystal wafer and glass storage devices, etc.  As a whole, the application of rare-earth nona materials is started right now and concentrated in the areas of high-tech new materials with broad application, giant potential and prosperous future.

2. Manufacturing technology

Nowadays, both the production and application of the nano materials has aroused the attentions of all the countries.  The nano technology in our country has made progress consecutively.  The powder materials of nano SiO2, TiO2, Al2O3, ZnO2 and Fe2O3 have been put into industrialized production or trial production successfully. However, the current production technology and cost, as the fatal weakness will influence the promotion and application of nano materials.  Therefore, for the nano materials, the improvement and rectifications are needed.

Due to the special electron structures and larger atomic radiuses of the rare earth elements, and big difference of the chemical properties of the rare earth elements from those of other elements, the manufacturing method and technology of post-treatment of rare earth nano oxides are different from the other elements. The main research methods include:

1) The method of precipitation: including the methods of oxalic acid precipitation, carbonate precipitation, hydroxide precipitation, homogeneous precipitation and complexion precipitation, etc.  The largest features of the precipitation method consist of fast nucleation of solution, easy control, simply device and the products with high purity can be manufactured. For the weakness, it is difficult to filer and it is easy to be agglomerated.

2) Hydrothermal method: under the condition of high temperature and high pressure, accelerate and strengthen the hydrolysis reaction of ions and then form the scattered nano nucleuses.  With this method, the nano powder scattered evenly with narrow distribution of particle size.  However, in this method, the high-temperature and high-pressure facilities required are expensive and unsafe to operate.

3) Gel method: this is an important method in manufacturing the inorganic materials, enjoying a special position in the inorganic synthesis.  Under low temperature, the organic metal compounds or organic complexes will form sol through the polymeric reaction or hydrolysis reaction and then form gel under certain conditions.  With further thermal treatment, the ultrafine nano powder better scattered with lager surface will be got.  The method can also be used under the warm condition, in which the powder got will be scattered much better and the surface will be much larger.  However, the reaction will be kept for several days, which can not satisfy the requirements of industrialization.

4) Solid-phase method: this method refers to decompose under high temperature through solid compound or intermediate solid-phase reaction.  For example, mixing the rare earth nitrates and oxalic acid and then conducting the ball milling, the intermediates of rare earth oxalate are formed.  After the decomposition under high temperature, the super fine powder is produced.  This method has many advantages: high reaction efficiency, easy to operate and simple facilities.  However, the form of the powder is irregular and lacks of homogeneity

All these method are not the unique methods and not completely suitable for the industrialization. There are many other manufacturing methods, such as organic micro-emulsion method and alkoxide hydrolysis method, etc.

4. Progress of the industrialized development

Industrialized production does not refer to adopt the some method individually, but use several methods together to make the best of all the methods to meet the commercialized requirements of high quality of products, low cost and safe and high-efficient process.  The Riel Chemical Technology Co., Ltd in Huizhou of Guangdong Province got the industrialized progress in the development of rare-earth nano materials recently.  Through the exploration and numerous tests of several method, it finds out the method that is relatively appropriate for the industrialized production-microwave gel method, which has many advantages, such as the ten days of gel reaction shrunk to one day, which improves the productive efficiency for ten times, significant reducing the cost, high quality of the products, and the larger specific surface. After the trail of the customers, the feedbacks and responses are good.  In addition, the price is 30% lower than the products of America and Japan.  Therefore, the products have strong international compatibility and reached the international advanced level.

The recent industrial tests of precipitation method are mainly used the ammonium hydroxide and ammonium carbonate for precipitation, and the organic solvents for dehydration and surface treatment.  This method is easy and the cost is low. But the quality of the products is not good with part agglomeration.  Therefore, this method is needed to be improved further.

Our country is a large of rare earth resources.  The development and application of rare-earth nano materials has paved the new paths for the effective usage of rare-earth resources, expanded the application rage of rare earth, driven the development of the new functional materials, increased the export of the products with high added value and enhanced the capability for earning foreign exchange.  In addition, it has important actual significance of transforming the resources advantages into economic advantages.