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The most stable oxide of samarium is the sesquioxide Sm 2 O 3. Like many samarium compounds, it exists in several crystalline phases. The trigonal form is obtained by slow cooling from the melt. The melting point of Sm 2 O 3 is high (2345 °C), so it is usually melted not by direct heating, but with induction heating, through a radio-frequency ...
Cerium content in the soil varies between 2 and 150 ppm, with an average of 50 ppm; seawater contains 1.5 parts per trillion of cerium. [38] Cerium occurs in various minerals, but the most important commercial sources are the minerals of the monazite and bastnäsite groups, where it makes up about half of the lanthanide content.
Certain types of rare earth ores also contain radioactive thorium or uranium, which is often removed using acid. For this reason, development of the sector faces health and environmental ...
Some of the bastnäsites contain OH − instead of F − and receive the name of hydroxylbastnasite. Most bastnäsite is bastnäsite-(Ce), and cerium is by far the most common of the rare earths in this class of minerals. Bastnäsite and the phosphate mineral monazite are the two largest sources of cerium and other rare-earth elements.
The USGS study team has located a sizable area of rocks in the center of an extinct volcano containing light rare-earth elements including cerium and neodymium. It has mapped 1.3 million metric tons of desirable rock, or about ten years of supply at current demand levels. The Pentagon has estimated its value at about $7.4 billion. [186]
Cerium(III) sulfate is one of the few salts whose solubility in water decreases with rising temperature. [12] Ceric ammonium nitrate. Due to ligand-to-metal charge transfer, aqueous cerium(IV) ions are orange-yellow. [13] Aqueous cerium(IV) is metastable in water [14] and is a strong oxidizing agent that oxidizes hydrochloric acid to give ...
The CuTi 2 structure of the lanthanum, cerium and praseodymium diiodides along with HP-NdI 2 contain 4 4 nets of metal and iodine atoms with short metal-metal bonds (393-386 La-Pr). [10] these compounds should be considered to be two-dimensional metals (two-dimensional in the same way that graphite is). The salt-like dihalides include those of ...
Cerium(IV) oxide, also known as ceric oxide, ceric dioxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare-earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO 2. It is an important commercial product and an intermediate in the purification of the element from the ores.