Lanthanum is a chemical element, its chemical symbol is La, and its atomic number is 57. It belongs to the lanthanum family. It is the most active metal among the rare earth metals and is easily oxidized in the air. Lanthanum accounts for about 25% of the total rare earth in monazite ore. Soft silvery white metal, malleable. It can interact with water. Soluble in dilute acids. Easy to oxidize in air; Heating can burn to form oxides and nitrides. Heating in hydrogen produces hydrides. It is the second most abundant element among rare earth elements and is often found in monazite and fluorocarbon strontium lanthanite together with other rare earth elements. It is one of the radioactive products of uranium, thorium or plutonium fission. It can endow the glass with special refractive properties and make the glass have higher refractive index. The preparation of lanthanum is generally made by dehydration of hydrated lanthanum chloride and reduction with metal calcium, or by melting anhydrous lanthanum chloride and electrolysis. Used to make expensive camera lenses. LA, which is radioactive and has a half-life of 1.1×1011 years, has been tried to treat cancer.
Lanthanum oxide can be used to make glass; Lanthanum hexaboride can be used as cathode material for electron tubes. Lanthanum is used to prepare samarium, europium and ytterbium by thermal reduction of oxide metals.
A binary alloy consisting of the rare earth metals Ce and La. Commonly used chemical composition of cerium lanthanum alloy: 54% ~ 60%Ce, 0.1% ~ 0.3%Si, <0.5%Fe, trace C, residual La. This kind of alloy has good ductility and low evapotranspiration temperature, so it is often used in glow discharge voltage stabilizer tube. Evapotranspiration is on the cathode surface to reduce the work escaping from the cathode surface.
Nickel is one of only four elements that are ferromagnetic at room temperature. The magnetic strength of nickel-containing aluminum-nickel-cobalt alloy permanent magnets is between those containing iron and rare earth magnets. Nickel's place in the modern world is largely due to its alloys. About 60% of the world's nickel production is used in the production of various nickel steels (especially stainless steel). Other common alloys, and some newer superalloys, make up almost all the rest of the world's nickel. Chemical uses, used to make compounds, account for less than 3% of nickel production. As a compound, nickel has several specific uses in chemical manufacturing, such as as a catalyst for hydrogenation reactions. Nickel is an important nutrient for some microbial and plant enzymes that use nickel as their active site.
