Chemical properties of lanthanum powder



Lanthanum is a metallic rare earth element with chemical symbol La, atomic number 57 and atomic weight 138.90547. The element name comes from Greek and originally means "hidden". Silver gray luster, relatively soft texture, density 6.162g/cm3, melting point 920 ℃, boiling point 3464 ℃ (atmospheric pressure), chemical properties active, exposed to air quickly loses metal luster and forms a blue oxide film, but it does not protect the metal, which further oxidizes to form white oxide powder. It can react slowly with cold water, is easily soluble in acids, and can react with various non-metallic substances. Lanthanum metal is generally stored in mineral oil or rare gases. The content of lanthanum in the crust is 0.00183%, second only to cerium in rare earth elements. Lanthanum has two natural isotopes: lanthanum-139 and radioactive lanthanum-138.



Lanthanum metal has active chemical properties and is easily soluble in dilute acids. Easy to oxidize in the air, fresh surfaces quickly darken when exposed to air; Heating can burn, producing oxides and nitrides. Heating in hydrogen gas generates hydrides, which react strongly in hot water and release hydrogen gas. Lanthanum exists in monazite sand and bastnaesite. Lanthanum can directly react with carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, halogens, etc; Lanthanum compounds are diamagnetism. High purity lanthanum oxide can be used to manufacture precision lenses; Lanthanum nickel alloy can be used as a hydrogen storage material, and lanthanum hexaborate is widely used as a high-power electron emission cathode.

essential information

Element name: Lanthanum (l á n)



CAS number: 7439-91-0



Element symbol: La



English name of element: Lanthanum



Number of protons inside the nucleus, number of electrons outside the nucleus, and number of nuclear charges: 57



Proton relative mass: 57.399



Period: 6



Number of Families: 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



Content in the crust: 32ppm



Peripheral electronic layout: 5d16s2



Extranuclear electron arrangement: 2, 8, 18, 18, 9, 2



Electronic layer: K-L-M-N-O-P



Crystal structure: The crystal cell is hexagonal.



Cell parameter: a=377.2pm; b=377.2pm； c=1214.4pm； α= 90°； β= 90°； γ= 120°



Mohs hardness: 2.5



The propagation speed of sound in it: 2475m/s





The Function and Application of Lanthanum Powder



1. Metal lanthanum shells are used in the production of nickel hydrogen batteries, which is one of the main applications of lanthanum.



2. It is mainly used to manufacture special alloy precision optical glass and high refraction optical fiberboard, suitable for camera, camera, microscope lens, prism of optical instrument, etc. We also used the manufacturing of ceramic capacitors, piezoelectric ceramic dopants, and X-ray luminescent materials such as lanthanum bromide powder. Extracted from lanthanum phosphate cerium ore or obtained by burning lanthanum carbonate or nitrate. It can also be obtained by heating and decomposing the oxalate of lanthanum.



3. Used as a catalyst for various reactions, such as catalytic oxidation of carbon monoxide when doped with cadmium oxide, and catalytic hydrogenation of carbon monoxide to methane when doped with palladium. Lanthanum oxide infiltrated with lithium oxide or zirconia (1%) can be used to manufacture ferrite magnets. It is a highly effective selective catalyst for the oxidative coupling of methane to produce ethane and ethylene. It is used to improve the temperature dependence and dielectric properties of barium titanate (BaTiO3) and strontium titanate (SrTiO3) ferroelectrics, and to manufacture fiber optic devices and optical glass.



Storage method:

Store in a sealed container in a cool, dry place. Ensure that the workplace has good ventilation facilities. Keep away from sources of fire and water, and avoid contact with moisture. Do not store with oxides or acidic substances. Must be stored in paraffin or mineral oil.