Cerium is a silvery metal, belonging to the lanthanide group. It resembles iron in color and luster, but is soft, and both malleable and ductile. Cerium has the third-longest liquid range of any element: 2648 C° (795 °C to 3443 °C) or 4766 F° (1463 °F to 6229 °F). (Only thorium and neptunium have longer liquid ranges.)
Cerium is especially interesting because of its variable electronic structure. The energy of the inner 4f level is nearly the same as that of the outer or valence electrons, and only small energy is required to change the relative occupancy of these electronic levels. This gives rise to dual valency states. For example, a volume change of about 10% occurs when cerium is subjected to high pressures or low temperatures. It appears that the valence changes from about 3 to 4 when it is cooled or compressed. The low temperature behavior of cerium is complex. Four allotropic modifications are thought to exist: cerium at room temperature and at atmospheric pressure is known as γ-cerium. Upon cooling to –16 °C, γ-cerium changes to β-cerium. The remaining γ-cerium starts to change to α-cerium when cooled to –172 °C, and the transformation is complete at –269 °C. α-cerium has a density of 8.16; δ-cerium exists above 726 °C. At atmospheric pressure, liquid cerium is more dense than its solid form at the melting point.Read More: Cerium price
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