Ytterbium
Ytterbium is a soft, silvery lanthanide metal (symbol Yb, atomic number 70) used in specialty alloys, lasers and precision instruments; it occurs in rare-earth minerals and as several stable isotopes.
Overview
Ytterbium is a chemical element with the symbol Yb and atomic number 70. It belongs to the group of elements known as the lanthanides, often called rare-earth elements. As a metallic element it is typically soft and silver in appearance and is classified among the rare earth elements. For a general introduction to chemical elements see this overview.
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Physical and chemical characteristics
Ytterbium behaves like other lanthanides in many respects: it forms metallic bonds, conducts electricity, and most commonly exhibits a +3 oxidation state in compounds, with +2 also observed under some conditions. Its metallic form is relatively soft and malleable, and it oxidizes slowly in air. The element's electron shell structure and chemical behavior place it among the heavier members of the lanthanide series.
Occurrence and isotopes
In nature Yb is not found free but is dispersed through various rare-earth minerals such as gadolinite, monazite and xenotime. Commercial production separates it from other lanthanides in ore processing operations that exploit small differences in solubility and complexation. Natural ytterbium consists of a mixture of several stable isotopes; researchers and technicians often reference its isotopic composition when discussing nuclear properties and analytical applications (natural occurrence, stable isotopes, isotope details).
History and naming
The element's name derives from a locality historically associated with its discovery and classification among rare-earth substances. Its story is tied to the 19th-century era of mineral discovery and the gradual separation of closely related lanthanide elements, a process that relied on improvements in analytical chemistry and separation techniques.
Uses and applications
Ytterbium finds use in a range of specialized applications. Small additions can improve mechanical properties when alloyed with other metals, so it is sometimes incorporated into stainless steels and specialty alloys to refine grain structure and modify properties (steel and alloy use). Ytterbium-doped materials are important in photonics: certain solid-state lasers and fiber amplifiers use Yb ions as the active lasing medium, valued for efficient energy conversion and suitable emission wavelengths (laser applications).
Significance and safety
Although not a commodity metal like iron or copper, ytterbium is valuable for niche technologies in optics, metrology and materials science. Handling the element requires standard precautions for reactive metals and for powders or compounds that can be inhaled or ingested; industrial processes follow regulations for rare-earth materials and chemical safety.
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History
Ytterbium was discovered in 1878 by the Swiss chemist Jean Charles Galissard de Marignac. He examined gadolinite more closely and tried to separate the insoluble erbium from the other mineral components by decomposing nitrates in hot water. In doing so, he discovered that the crystals obtained did not consist uniformly of red erbium nitrate, but that other colourless crystals remained. The measured absorption spectrum showed that these must be crystals of a previously unknown element. He named this element ytterbium after the place where the gadolinite was found in Ytterby (Sweden) and because of its similarity to yttrium. A separation of the two elements was achieved in another experiment by adding hyposulphurous acid to a solution of the chlorides.
In 1907, the Frenchman Georges Urbain, the Austrian Carl Auer von Welsbach and the American Charles James independently recognized that the ytterbium found by Marignac was not a pure element but a mixture of two elements. They were able to separate this mixture into the now pure ytterbium and lutetium. Carl Auer von Welsbach named the elements aldebaranium (after the star Aldebaran) and cassiopeium, while Urbain specified neoytterbium and lutetium as the names. In 1909, it was determined by the International Atomic Weight Committee, consisting of Frank Wigglesworth Clarke, Wilhelm Ostwald, Thomas Edward Thorpe, and Georges Urbain, that Urbain was entitled to the discovery of lutetium, and thus the names he determined would stand. However, the old name of Marignac was retained for the ytterbium.
Elemental ytterbium was first obtained in 1936 by Wilhelm Klemm and Heinrich Bommer. They obtained the metal by reduction of ytterbium(III) chloride with potassium at 250 °C. Furthermore, they determined the crystal structure and the magnetic properties of the metal.
Extraction and presentation
The extraction of ytterbium is complicated and lengthy, mainly due to the difficult separation of the lanthanides. The starting minerals such as monazite or xenotime are first digested with acids or alkalis and brought into solution. The separation of ytterbium from the other lanthanides is then possible by various methods, with separation by ion exchange being the most technically important method for ytterbium, as well as for other rare lanthanides. In this process, the solution containing the rare earths is applied to a suitable resin to which the individual lanthanide ions bind to varying degrees. They are then dissolved from the resin in a separation column with the aid of complexing agents such as EDTA, DTPA or HEDTA, and the separation of the individual lanthanides is thus achieved by the different strength of binding to the resin.
Chemical separation is possible via different reactions of ytterbium, lutetium and thulium acetate with sodium amalgam. Ytterbium forms an amalgam, while the lutetium and thulium compounds do not react.
Metallic ytterbium can be obtained by electrolysis of a melt of ytterbium(III) fluoride and ytterbium(III) chloride, with alkali or alkaline earth metal halides for melting point reduction, and liquid cadmium or zinc as cathode. Besides, it can also be prepared by metallothermic reduction of ytterbium(III) fluoride with calcium, or ytterbium(III) oxide with lanthanum or cerium. If the latter reaction is carried out in a vacuum, ytterbium distills off and can thus be separated from other lanthanides.
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AlegsaOnline.com Ytterbium Leandro Alegsa
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