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Lanthanum metal
Lanthanum alloy
la alloy
Lanthanum particle
Lanthanum 99.99%
la 99.99
Lanthanum is a kind of rare earth element, the chemical symbol is La, atomic number is 57, atomic weight is 138.90547, element name comes from Greek, meaning "hidden". Silver gray luster, soft texture, density 6.162g/cm3, melting point 920ºC, boiling point 3464ºC (atmospheric pressure), active chemical properties, exposed to the air quickly lost metal luster to produce a layer of blue oxide film, but it can not protect the metal, and then further oxidation to white oxide powder. It can act slowly with cold water, easily dissolves in acid, and can react with a variety of non-metals. The metal lanthanum is usually stored in mineral oil or noble gases. Lanthanum, which is found in 0.00183% of the Earth's crust, is second only to cerium among rare earth elements. There are two natural isotopes of lanthanum: lanthanum-139 and radioactive lanthanum-138
Element Name: Lanthanum (lan)
CAS No. : 7439-91-0 [3]
Element symbol: La
Element English name: Lanthanum
Number of protons in nucleus, number of electrons in nucleus, nuclear charge: 57
Proton relative mass: 57.399
Owning period: 6
Number of family: IIIB
Atomic weight of element: 138.90547
Element type: Metal
Atomic volume: 20.73cm3/mol
Element content in the Sun: 0.002ppm
Element content in seawater: Pacific Surface: 0.0000026ppm
Crust content: 32ppm
Peripheral electron configuration: 5d16s2
Electron configuration: 2,8,18,18,9,2
Electron shell: K-L-M-N-O-P
Crystal structure: the cell is hexagonal.
Cell parameters: a = 377.2 pm; b = 377.2 pm; c = 1214.4pm; α = 90°; β = 90°; Gamma is equal to 120 degrees
Mohs Hardness: 2.5
The propagation rate of sound in it: 2475m/s
Ionization energy (kJ/mol)
M-M + 538.1
M+ - M2+ 1067
M2+ - M3+ 1850
M3+ - M4+ 4819
M4+ - M5+ 6400
M5+ - M6+ 7600
M6+ - M7+ 9600
M7+ - M8+ 11000
M8+ - M9+ 12400
M9+ - M10+ 15900
Physical properties edit broadcast
lanthanum
lanthanum
Lanthanum metal is a silver - white metal, soft and easy to cut. Fresh section is silver-gray, easily oxidized in the air. There are three crystal types, α type, hexagonal system, β type, face-centered cubic accumulation, stable existence at 350ºC, density =6.19g/cm³; γ type, > Stable existence at 868ºC, density =5.98g/cm³. Avoid contact with acids, oxides, halogens and sulfur. Exposure to heat, open flame, oxidant and other substances may cause combustion hazard. Generally sealed in solid paraffin or immersed in kerosene is vulnerable to inorganic acid attack.
Chemical properties editor
The metal lanthanum is chemically active and soluble in dilute acids. It is easy to oxidize in the air, and the fresh surface darkens rapidly when it meets the air. Heat can burn, forming oxides and nitrides. It is heated in hydrogen to form hydrides, which react strongly in hot water and give off hydrogen. Lanthanum is found in monazite and fluocerite. Lanthanum can react directly with carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, halogen, etc. Lanthanum compounds are diamagnetism. High purity lanthanum oxide can be used to manufacture precision lenses. Lanthanum nickel alloy can be used as hydrogen storage materials. Lanthanum hexaboride is widely used as high power electron emission cathode.
Storage method editor broadcast
Add to an airtight storage container and store in a cool, dry place. Ensure good ventilation in the workshop. Keep away from fire and water sources and avoid contact with moisture.
Do not store with oxides and acidic substances. Must be kept in paraffin or mineral oil.
Composite method edit broadcast
1. Generally, lanthanum chloride hydrate is reduced with calcium metal after dehydration, or anhydrous lanthanum chloride is melted and electrolyzed [2].
2. 70g LaCl3 and 18.5g Ca are thoroughly mixed and shaken in an inert atmosphere into the tantalum crucible or pressed into a cylinder by a power press into the tantalum crucible, which is equipped with a punched tantalum lid for ventilation and placed in a closed MgO crucible [d=2(in,in=0.0254m). h=7(in,in=0.0254m)]. It is then placed in a quartz tube [d=2.25(in,in=0.0254m)] with one end of the tube fusible and the other end polished into a 55/50 tapered joint. The quartz tube is sealed in a vacuum system with paraffin wax. Fill Ar (after the purification of hot uranium metal) to P=1atm, with 6kW induction furnace heating to 550~600ºC, so that the reaction occurs (tantalum crucible temperature suddenly rises as evidence). After 5min, the temperature reached 1000ºC, and the resulting rare earth metals were completely agglomerated after maintaining for 13min. Cool to room temperature and soak the tantalum crucible with water to remove CaCl2 and Ca, leaving the molten rare earth metals at the bottom (1%-3% Ca).
3. Electrolytically melt the mixture of 50g KOH + 20g NaOH + 8g H2O + 10g La2O3 in a 100mL nickel crucible. The nickel crucible was placed in an electric furnace of 300W, and the temperature was measured by a glass thermometer equipped with a metal hoop head. The thick platinum wire was used as the anode to dip slightly under the liquid level of the molten material, and the crucible was used as the cathode, with a voltage of 4V. The temperature was controlled at 300ºC until the clear melt was obtained. 5min later, when the temperature reached 310ºC, precipitation began to appear in the clear melt. When the reaction exothermic heat was observed, the heating was stopped and the temperature dropped to 290ºC for 20min. After that, the molten substance was gently poured out and the crystal was obtained. Better crystals can be formed when the molten substance is reheated at 260~280ºC for 2.5h. The product is washed with dilute acetic acid.
Purpose editing broadcast
1. Lanthanum metal shells are used in the production of nickel-metal hydride batteries, which is one of the most important applications of lanthanum.
2, mainly used in the manufacture of special alloy precision optical glass, high refraction optical fiberboard, suitable for cameras, cameras, microscope lenses and advanced optical instruments prism. Ceramic capacitors, piezoelectric ceramics additives and lanthanum bromide oxide powder, which are X-ray luminescent materials, are also used. Extracted from cerium lanthanum ore or obtained by burning lanthanum carbonate or lanthanum nitrate. It can also be made by the decomposition of lanthanum oxalate by heating.
3, used as a catalyst for a variety of reactions, such as doping cadmium oxide catalyzed carbon monoxide oxidation reaction, doping palladium catalyzed carbon monoxide hydrogenation to methane reaction. Lanthanum oxide impregnated with lithium oxide or zirconia (1%) can be used to make ferrite magnets. It is a very effective selective catalyst for oxidative coupling of methane to ethane and ethylene. It is used to improve the temperature dependence and dielectric properties of barium (BaTiO3) and strontium titanate (SrTiO3) ferroelectrics, and to manufacture fiber optical devices and optical glasses.
4. Lanthanum-138, which is radioactive and has a half-life of 1.1×1011 years, has been used to treat cancer.
The lanthanide series editor
lanthanide elements are the general name of 15 chemical elements with atomic numbers from 57 to 71 in group of periodic series. These include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, all members of the rare earth elements. Lanthanides are usually silvery glossy metals that are soft, malleable, and paramagnetic. The lanthanides are relatively reactive in their chemical properties. The newly cut shiny metal darkens rapidly in the air, forming an oxide film on the surface. It is not tight and will be further oxidized. The metal is heated to 200~400ºC to form oxides. Metals react slowly with cold water, react violently with hot water, produce hydrogen, soluble in acids, not alkali. Metals burn violently in halogens above 200 ° C, form nitrides above 1000 ° C, slowly absorb hydrogen at room temperature, and rapidly form hydrides at 300 ° C. The lanthanides are strong reducing agents that are more active than aluminum and at 150~180ºC. The lanthanide outermost shell (6s) has the same number of electrons, 2. While lanthanum nucleus has 57 charges, from lanthanum to lutetium, nuclear charge increases to 71, making atomic radius and ionic radius gradually shrink, this phenomenon is called lanthanide shrinkage. Due to lanthanide shrinkage, the properties of the compounds of these 15 elements are very similar. Oxides and hydroxides have low solubility and strong alkalinity in water; chlorides, nitrates and sulfates are easily soluble in water; oxalates, fluoride, carbonate and phosphates are insoluble in water.
Lanthanum block
Rare earth lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc) and yttrium (Y), a total of 17 elements. The English name is Rare Earth. Rare earth metals are generally soft, malleable, malleable, powdery and highly reactive at high temperatures. This group of metals has strong chemical activity, and has a strong affinity for hydrogen, carbon, nitrogen, oxygen, sulfur, phosphorus and halogen. It is easy to be oxidized in the air. The surface of heavy rare earth and scandium and yttrium is easy to form an oxide protective layer at room temperature. Rare earth elements can be divided into light rare earth and heavy rare earth, mainly in the form of rare earth oxides. China, Russia, the United States and Australia lead the world in rare earth reserves. Rare earth is mainly used in petroleum, chemical industry, metallurgy, textile, ceramic glass, permanent magnet materials and other fields, known as "industrial monosodium glutamate", "industrial vitamin" and "the mother of new materials", is a precious strategic metal resources.
Known as the "vitamin of industry", rare earth elements have irreplaceable excellent magnetic, optical and electrical properties, which play a huge role in improving product performance, increasing product varieties and increasing production efficiency. Because of heavy rare earth effect, less dosage, has become to improve the product structure, improve the technology content, promote the important elements of the technical progress in the sector, has been widely applied to metallurgy, military, petrochemical industry, glass ceramic, agriculture and new materials, etc.
Rare earth has been used in the field of metallurgy for more than 30 years. At present, relatively mature technologies and processes have been formed. The application of rare earth in steel and non-ferrous metals is a large and extensive field with broad prospects. The addition of rare earth metals, fluoride and silicide to steel can play the role of refining, desulphurizing, neutralizing harmful impurities with low melting point, and improve the workability of steel. Rare earth ferrosilicon alloy and rare earth silicon magnesium alloy are used as spheroidizing agents to produce rare earth nodular cast iron. Because this kind of nodular cast iron is especially suitable for the production of complex nodular iron parts with special requirements, it is widely used in automobile, tractor, diesel engine and other machinery manufacturing industry. Rare earth metals added to magnesium, aluminum, copper, zinc, nickel and other non-ferrous alloys can improve the physical and chemical properties of the alloys, and improve the mechanical properties of the alloys at room temperature and high temperature.
Military field
Due to its excellent photoelectromagnetic and other physical properties, rare earth can be combined with other materials to form a wide variety of new materials with different properties, which can greatly improve the quality and performance of other products. Therefore, it is called "industrial gold". First of all, the addition of rare earths can greatly improve the tactical performance of steel, aluminum alloy, magnesium alloy and titanium alloy used in the manufacture of tanks, aircraft and missiles. In addition, rare earth can also be used as electronic, laser, nuclear industry, superconductivity and many other high-tech lubricants. Once rare earth technology is used in the military, it will inevitably bring about a leap in military science and technology. In a sense, the overwhelming control of the US military in several post-Cold war local wars, and its ability to openly kill its enemies with impunity, is due to its superior rare earth technology.
Petrochemical industry
Rare earth can be used to make molecular sieve catalyst in the field of petrochemical industry. It has the advantages of high activity, good selectivity and strong anti-heavy metal poisoning ability, so it replaces aluminum silicate catalyst in petroleum catalytic cracking process. In the process of synthetic ammonia production, the treated gas volume of rare earth nitrate as cocatalyst is 1.5 times larger than that of nickel-Al catalyst. In the process of synthesis of butadiene rubber and isoamyl rubber, rare earth naphthenate - triisobutyl aluminum catalyst was used to obtain the product performance, which has the advantages of less adhesive hanging equipment, stable operation and short post-treatment process. Complex rare earth oxide can also be used as a catalyst for cleaning the tail gas of internal combustion engine, cerium naphthenate can also be used as a paint dryer.
Glass ceramics
The amount of rare earth used in glass and ceramic industry has been increasing by 25% on average since 1988, and reached about 1600 tons in 1998. Rare earth glass ceramics are not only the traditional basic materials in industry and life, but also the main members in high-tech field. Rare earth oxides or processed rare earth concentrate can be widely used as polishing powder for optical glass, eye lenses, picture tubes, oscilloscope tubes, plate glass, plastic and metal tableware. In the process of the melted glass, can use ceria on iron has a strong oxidation, reduce the iron content in the glass, to achieve the purpose of removal of green in the glass. The addition of rare earth oxides can produce different uses of optical glass and special glass, including infrared, ultraviolet absorption glass, acid and heat resistant glass, X-ray resistant glass; Rare earth is added in the glazes and enamels, can reduce fragmentation of glaze, and can make the products presents a different color and luster, is widely used in ceramic industry.
agriculture
The results showed that rare earth elements can increase the chlorophyll content of plants, enhance photosynthesis, promote root development, and increase the uptake of nutrients by roots. Rare earth also can promote seed germination, improve seed germination rate, promote seedling growth. In addition to the above main effects, but also to make some crops to enhance the ability of disease resistance, cold resistance, drought resistance. A large number of studies have also shown that the use of proper concentration of rare earth elements can promote the absorption, conversion and utilization of nutrients by plants. Spraying rare earth can increase Vc content, total sugar content and sugar-acid ratio of apple and citrus fruits, and promote fruit coloring and early maturation. In addition, it can inhibit respiration intensity and decrease decay rate during storage.
New material field
Rare earth ndfeb permanent magnet material, with high remanence, high coercivity and high magnetic energy product, is widely used in electronics and aerospace industry and drive wind turbines (especially suitable for offshore power plants); Garnet ferrite single crystal and polycrystal formed by pure rare earth oxide and ferric oxide can be used in microwave and electronics industry; Yttrium aluminum garnet and neodymium glass made of high purity neodymium oxide can be used as solid laser materials; Rare earth hexaboride can be used to make cathode materials for electron emission. Lanthanum nickel metal is a newly developed hydrogen storage material in 1970s. Lanthanum chromate is a high temperature thermoelectric material; At present, all countries in the world use barium yttrium cu-oxygen modified barium base oxide to make superconducting materials, which can be obtained in the liquid nitrogen temperature zone, so that the development of superconducting materials has made a breakthrough. In addition, rare earth is also widely used in the form of phosphor, enhanced screen phosphor, three primary color phosphor, photocopying lamp powder and other lighting sources (but due to the high cost caused by the rising price of rare earth, so the application in lighting is gradually reduced), projection TV tablet computer and other electronic products; In agriculture, applying trace amount of rare earth nitrate to field crops can increase the yield by 5~10%. In light textile industry, rare earth chloride is also widely used in tanning fur, fur dyeing, wool dyeing and carpet dyeing. Rare earths are used in catalytic converters in cars that turn major pollutants into non-toxic compounds when the engine exhausts them.
Other applications
Rare earth elements are also used in a variety of digital products, including audio-visual, photographic and communication digital equipment, to meet the requirements of smaller, faster, lighter, longer service life, energy saving and other requirements. At the same time, it has been applied to green energy, medical care, water purification, transportation and other fields.
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