Five rare-earth metals (dysprosium, neodymium, terbium, europium and yttrium), for example, possess unique magnetic, catalytic and luminescent properties that make wind turbines, solar panels, electric vehicles and efficient lighting possible.
Small doses of dysprosium or terbium, for instance, make batteries operate better at high temperatures a must for electric cars.At least some of this exuberance is not quite rational, reckons Merrill McHenry, a metals analyst.
They brought a case at the World Trade Organisation alleging that China was unfairly restricting its exports of tungsten, molybdenum and 17 "rare earths", obscure elements such as terbium and europium, used in the manufacture of many high-tech goods including fluorescent lights.
A total of 36 (excluding nuclear isomers) radioactive isotopes of terbium have been identified.
Together with another lanthanide gadolinium terbium was used by Geoffrey Green and coworkers in 1990 to build a dual-stage room-temperature magnetic refrigerator prototype, with gadolinium as a high-temperature stage and terbium as a low-temperature stage.
Yttria, the first rare earth to be discovered, turned out to be a mixture of oxides from which, over a span of more than a century, nine elements yttrium, scandium (atomic number 21), and the heavy lanthanide metals from terbium (atomic number 65) to lutetium (atomic number 71)—were separated.
CeO2 (where Ce is tetravalent) is the normal stable oxide form, while the oxides of praseodymium and terbium have the Pr6O11 and Tb4O7 stoichiometries containing both the tetra- and the trivalent states i.e., 4PrO2∙Pr2O3 and 2TbO2∙Tb2O3, respectively.
The element was discovered in 1842 as an oxide by Carl Gustaf Mosander, who originally called it terbia; in the confusion arising from the similarity in the properties of the rare-earth elements, the names of two, terbium and erbium, became interchanged (c. 1860).
The only tetrahalides known are the RF4 phases, where R = cerium, praseodymium, and terbium.
The low value of 25 μΩ-cm is for divalent fcc ytterbium metal, while the two largest values, gadolinium (131 μΩ-cm) and terbium (115 μΩ-cm), are due to a magnetic contribution to the electrical resistivity that occurs near the magnetic ordering temperature of a material.
Along with praseodymium and terbium, cerium is different from the other rare earths in that it forms compounds in which its oxidation state is +4; it is the only rare earth that exhibits a +4 oxidation state in solution.
