镨 is the third member of the lanthanide element in the periodic table of the chemical element. The abundance in the earth's crust is 9.5ppm, which is only lower than 铈 , 钇 , 镧, 钪 . It is the fifth largest rich element in rare earth. Like his name, he is a simple and rare family member of the rare earth family.
In the history of the discovery of rare earth elements, strontium and barium were simultaneously discovered. In 1841, the Swedish chemist CG Mosander, who had discovered cockroaches, discovered a new "element" from the "soil", which is very similar in nature to 镧, and named it "Didymium" (Didymium, Greek means "twin", but it is not a single element, but a bismuth compound. It took another 40 years, who had invented the thorium cerium Qidengshazhao Austrian Welsbach (CFAuer Von Welsbach), is also in the invention Qidengshazhao 1885, succeeded in "Pr-Nd" This "even The twins performed a separation procedure to separate the green strontium salt and the rose strontium salt, confirming that they are two new elements. One is called "Praseodymium", which comes from the Greek word prason, meaning green compounds, because the strontium salt solution will show bright green onion; the other element will be called "Neodymium". The successful separation of the "conjoined twins" allowed them to display their talents from then on.
As the rare earth element praseodymium larger amount, a large part is in the form of misch metal are utilized, such as purifying modifier metal material, chemical catalysts, rare earths in agriculture and the like. Niobium is the most similar and most difficult to separate pair of elements in rare earths. It is difficult to separate them by chemical methods. Industrial production usually uses extraction and ion exchange. If they are used in the form of enrichment, they can make full use of their commonality and the price is cheaper than the single element product. Niobium alloy (base metal) has become a stand-alone product that can be used both as a permanent magnet material and as a non-ferrous metal alloy modification additive. The preparation of a petroleum cracking catalyst by adding a Y-type zeolite molecular sieve in the form of a ruthenium-rich concentrate can improve the activity, selectivity and stability of the catalyst. As a plastic modification additive, the addition of cerium-rich concentrate to polytetrafluoroethylene (PTFE) can significantly improve the wear resistance of PTFE.
Rare earth permanent magnet materials are the most popular applications for rare earths today.性能 The performance of æ°¸ç£ alone as a permanent magnet material is not outstanding, but he is an excellent synergistic element that can improve magnetic performance. Whether it is the first generation of rare-earth magnets, samarium cobalt permanent magnet alloys (SmCo5), the third generation of rare-earth magnets or Neodymium-iron-boron (Nd2Fe17B), adding an appropriate amount of praseodymium can effectively enhance and improve the performance of permanent magnet material. For example, adding a part of Pr to SmCo5 to replace Sm can increase the magnetic energy product of the permanent magnet material. The ratio of the two is generally 80% Sm-20%Pr. If too much is added, the coercive force and stability of the material will be lowered. In the third generation rare earth permanent magnet material NdFeB, the addition of niobium can improve the coercivity of the material. In Germany, Japan and other countries, when producing high coercivity NdFeB magnets, some niobium is added. The amount of strontium added is 5% to 8%, up to 10%, which can replace 1/3 of cockroaches. Magnetic materials have high requirements on the quality of tantalum, and at least the equivalent quality of tantalum should be achieved. The addition of niobium also improves the anti-oxidation properties (air corrosion resistance) and mechanical properties of magnets, and has been widely used in various electronic devices and motors. In addition, the addition of Pr in the new rare earth bonded permanent magnet material (Sm) 2Fe17N9 of NdFeB can also improve the performance, which will further expand the application of niobium. Therefore, with the development of the application of permanent magnet materials, the amount and price of antimony continue to rise, and it has become a "new darling" in rare earth products.
Tantalum can also be used to grind and polish materials. It is well known that pure bismuth-based polishing powder is usually light yellow, which is a high-quality polishing material for optical glass, and has replaced iron oxide red powder which has low polishing efficiency and pollutes the production environment. However, it has been found that cerium oxide has little effect on polishing, but cerium has good polishing properties. The cerium-containing rare earth polishing powder will be reddish brown, also known as "red powder", but this red color is not iron oxide red, but the color of the rare earth polishing powder is deepened by the inclusion of cerium oxide.镨 is also made of a new grinding material to make a corundum- containing grinding wheel. Compared with white corundum, efficiency and durability can be increased by more than 30% when grinding carbon structural steel, stainless steel and superalloy. In order to reduce the cost, in the past, the sputum enrichment was used as the raw material, so it was called the 镨钕 corundum grinding wheel.
镨 The use of 光纤 in the field of optical fiber is also becoming more and more extensive. The erbium-doped fiber amplifier (PDFA), which has amplifying in the 1300~1360nm spectral region, has been developed, and the technology is becoming more and more mature. With its excellent performance and price ratio, PDFA has great practical significance for the construction and transformation of the 1550nm CATV system fiber-optic cable TV in China. PDFA will fundamentally change the existing 1550nm CATV network structure, making the 1310nm CATV system an ideal alternative to the 1550nm system in HFC system retrofit.
The strontium salt (oxalic acid or carbonate) is burned at a high temperature to form a brown-black oxide Pr6O11, which is composed of a combination of four PrO 2 and one Pr 2 O 3 , indicating that the ruthenium has a strong positive tetravalent value. tendency. Adding cerium oxide to zirconium silicate will be bright yellow and can be used as a ceramic pigment - yttrium yellow. Yttrium yellow (ZrO 2 -Pr 6 O 11 -SiO 2 ) is considered to be the best yellow ceramic colorant and remains stable up to 1000 ° C and can be used in a one-shot or re-sintering process.镨 enters the zirconium silicate lattice, accounting for about 5% of the material composition. It is widely used in architectural ceramics and daily-use ceramics. It can be used as a glaze pigment alone or as a glaze with ceramic glaze. Its color is bright and bright, its color is pure, and it can be as deep as the amount of strontium. Amber yellow, light to white and yellow, used to replace the traditional vanadium tin yellow and vanadium zirconium yellow, can overcome the original brown tone, used to make sanitary and architectural ceramics, the color is high and clean. It can be used to make unique imitation ivory arts and crafts and daily-use ceramics. The color is beautiful and exquisite, which is favored by the ceramic industry. China, Italy and Spain, as major producers of architectural tiles, have a large consumer market for yttrium. By mixing yttrium oxide with other elements, it is also possible to formulate ceramic pigments such as zirconium, vanadium green, zirconium, vanadium and orange. By adjusting the ratio of cerium oxide to vanadium pentoxide, it is also possible to produce a ceramic color tone between yellow and sky blue. Adding CeO 2 to the yellow can form a slightly reddish yellow color. The global use of cerium oxide for the use of ceramic pigments based on yttrium is estimated at thousands of tons.
It is also used as a glass colorant, rich in color, and has a large potential market. It can produce "green" glass products with bright green and green color, which can be used to make green filters or art glass. The bright green color of the enamel is seen in the world-famous crystal glass of Venice and the Czech Republic. Cerium oxide and cerium oxide are added to the glass and can be used as a goggle glass for electric welding. Cerium sulfide is also expected to become a practical green plastic colorant.
praseodymium | Element symbol Pr | English name Praseodymium | Atomic number 59 | ||||||
Relative atomic mass (12C = 12.0000) 140.90765 | |||||||||
Discovered age | 1885 | Discovering people | Baron Auer von Welsbach (Austria, Vienna) | ||||||
original child Knot Structure | Atomic radius (?): 2.67 | Ion radius (?): 1.013 | |||||||
Covalent radius (?): 1.65 | Oxidation state: 3,4 | ||||||||
Atomic volume cm 3 / mol: 20.8 | |||||||||
Electronic configuration: 1s2 2s2p6 3s2p6d10 4s2p6d10f3 5s2p6 6s2 | |||||||||
Physical properties | Status: Soft silver white metal | Melting point (°C): 931 | Boiling point (°C): 3512 | ||||||
Specific heat (J/gK): 0.19 | Density (g/cc, 300K): 6.77 | ||||||||
Heat of fusion (KJ/mol): 6.89 | Evaporation heat (KJ/mol): 296.8 | ||||||||
Conductivity (106/cm Ω): 0.0148 | Thermal conductivity (W/cm K ): 0.125 | ||||||||
Geology data | Abundance | In sea water (ppm).: | |||||||
Crust (ppm.): 9.5 | Atlantic surface: 4 × 10 - 7 | Deep in the Atlantic: 7 × 10 - 7 | |||||||
Atmosphere (ppm) / volume: | Pacific surface: 4.4 × 10 - 7 | Deep in the Pacific: 10 × 10 - 7 | |||||||
Health Object number according to | Human body content (ppm): | ||||||||
In the organ: very low | |||||||||
Human (70Kg) total body mass (mg): very low. | |||||||||
Daily intake / mg: unknown | |||||||||
mine Production Capital source | Industrial minerals: | Main producing area | |||||||
Mixed (fluorocarbon 铈 + monazite) | Baiyun Obo Mine, Baotou, Inner Mongolia Autonomous Region, China | ||||||||
Bastnaesite CeLaFCO 3 (light rare earth) | US Mount Pace Mine (California) | ||||||||
China's Sichuan Suining, Shandong Weishan | |||||||||
Monazite (CeLaTh)PO 4 (light rare earth) | Australia's Verde Mountain, East Coast Coastal Sand Mine | ||||||||
South West Coastal Sands, China Guangdong and Taiwanese seaside sands | |||||||||
Rare earth apatite | Kola Peninsula, Russia | ||||||||
Niobium perovskite Ce | Russia's Tomtor Carbonate weathering crust rare earth deposit | ||||||||
Ionic ore (rich in yttrium europium) | China's Jiangxi Xunwu, Guangdong Pingyuan | ||||||||
Distribution Pr % | Baotou mixed type mine | Sichuan fluorocarbon antimony ore | Zhongyu Fuyu Ion Type Mine | Guangdong Nanshanhai Monazite | |||||
5-6 | 4-5 | 6-8 | 5-6 | ||||||
Application field | Metal, alloy | Steel and non-ferrous metal modifiers, permanent magnet materials | |||||||
Mixed oxide | Petroleum cracking catalyst, agricultural rare earth, assisted dyeing aid | ||||||||
Single oxide | Ceramic and glass colorants, optical fibers, polishing powders, plastic pigments, | ||||||||
Organic compound | Chemical catalysts, stabilizers and modifiers; feed additives |
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