Aeneral

Cer [t͡seːr] (also called Zer or Cerium) is a chemical element with the element symbol Ce and the atomic number 58. In the periodic table, it is in the group of lanthanides and thus also belongs to the metals of rare earths.Cer 1803 was discovered by Jöns Jacob Berzelius and Wilhelm von Hisinger and at the same time by Martin Heinrich Klaproth and named after the dwarf planet Ceres. Carl Gustav Mosander 1825 succeeded in rendering the element possible by reducing the chloride with sodium. In nature, cerium occurs in association with other lanthanides in so-called ceriterden, such as in allanite (Ca, Ce, La, Y) 2 (Al, Fe). ³ (SiO4) ³ (OH), in the monazite (Ce,

La, Th, Nd, Y) PO4 as well as in bastnasite (Ce, La, Y) CO³F.

Recovery

After a complex separation of the cerium companion, the oxide is reacted with hydrogen fluoride to Cerfluorid. It is then reduced to cerium with calcium to form calcium fluoride. The separation of remaining calcium residues and impurities takes place in an additional remelting in vacuo.

Features

The silvery white shiny metal is the second most reactive element of the lanthanoids after europium. Superficial damage to the protective yellow oxide layer ignites the metal. Above 150 ° C it burns with a violent glow to form ceria. It reacts with water to form cerium hydroxide.

Cerium occurs in compounds as a trivalent colorless or tetravalent yellow to orange cation.

Under the influence of heat, it is strongly attacked by ethanol and water. It is also heavily attacked in alkalis to form cerium hydroxides. In acids, it is dissolved into salts.
Since the chemical properties of rare earths are similar, metallic cerium is rarely used in pure form, but in the mixture in which it is obtained in the production of the rare earth minerals, the so-called mischmetal.

Cerium, like all lanthanides, is slightly toxic. Metallic cerium can ignite from 65 ° C. As a finely divided metal, it can heat up in the air without energy and finally ignite. Among other things, the ignition readiness depends very much on the particle size and the degree of distribution. Cerial fires must not be extinguished with water as gaseous hydrogen evolves.

Usage

In metallurgy, cerium is used as an additive for aluminum alloys and high-temperature-resistant iron-based alloys. It supports the separation of sulfur and oxygen in the melting process. The iron-mischmetal alloy Cereisen serves as the starting material for flints for use in lighters and for generating sparks on roller coasters and in movie scenes (accident scenes). Cereisen in the composition 70% cerium and 30% iron, also known as Auermetall, was registered for a patent by Karl Auer von Welsbach in 1903. A modification found worldwide distribution as a flint for lighters.

Small additions of (more or less pure) cerium compounds impart certain properties to other materials:

1. Ceria (CeO 2) is used to stabilize the alumina ceramic catalyst support for automotive exhaust catalysts.
2. Part of some special lenses, for example UV filters and windshields, and dehumidifiers in glass manufacturing
3. For coloring enamel
4. Ceria is used as a polishing agent in glass processing
5. Cerium-doped fluorescent dyes (phosphors) in picture tubes and white LEDs
6. as doping in mantles
7. Self-cleaning ovens contain a cerium-containing coating
8. Cerium (IV) sulfate as oxidizing agent in Quantitative Analysis (Cerimetry)
9. as a contrast agent at nuclear resonance
10. as a phosphor in gas discharge tubes
11. added to the regeneration of soot particle filters dissolved in the fuel
12. as part of non-precious metal-containing bonding alloys in dental technology (ceramics)
13. as an oxidant for organic syntheses with CAN (cerium ammonium nitrate), (NH4) ²Ce (NO³) 6

Please follow and like us: