Ytterbium

Ytterbium

Ytterbium is a chemical element with symbol Yb and atomic number 70. It is the fourteenth and penultimate element in the lanthanide series, or last element in the f-block, which is the basis of the relative stability of the +2 oxidation state. However, like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble ytterbium compounds form complexes with nine water molecules. Because of its closed-shell electron configuration, its density and melting and boiling points differ from those of the other lanthanides.

In 1878, the Swiss chemist Jean Charles Galissard de Marignac separated in the rare earth "erbia" another independent component, which he called "ytterbia", for Ytterby, the village in Sweden near where he found the new component of erbium. He suspected that ytterbia was a compound of a new element that he called "ytterbium" (in total, four elements were named after the village, the others being yttrium, terbium and erbium). In 1907, the new earth "lutecia" was separated from ytterbia, from which the element "lutecium" (now lutetium) was extracted by Georges Urbain, Carl Auer von Welsbach, and Charles James. After some discussion, Marignac's name "ytterbium" was retained. A relatively pure sample of the metal was obtained only in 1953. At present, ytterbium is mainly used as a dopant of stainless steel or active laser media, and less often as a gamma ray source.

Natural ytterbium is a mixture of seven stable isotopes, which altogether are present at concentrations of 3 parts per million. This element is mined in China, the United States, Brazil, and India in form of the minerals monazite, euxenite, and xenotime. The ytterbium concentration is low, because the element is found among many other rare earth elements; moreover, it is among the least abundant ones. Once extracted and prepared, ytterbium is somewhat hazardous as an eye and skin irritant. The metal is a fire and explosion hazard.

Occurrence


Ytterbium is found with other rare earth elements in several rare minerals. It is most often recovered commercially from monazite sand (0.03% ytterbium). The element is also found in euxenite and xenotime. The main mining areas are China, the United States, Brazil, India, Sri Lanka, and Australia; and reserves of ytterbium are estimated as one million tonnes. Ytterbium is normally difficult to separate from other rare earths, but ion-exchange and solvent extraction techniques developed in the mid- to late 20th century have simplified separation. Known compounds of ytterbium are rare and have not yet been well characterized. The abundance of ytterbium in the Earth's crust is about 3 mg/kg.

As an even-numbered lanthanide, in accordance with the Oddo-Harkins rule, ytterbium is significantly more abundant than its immediate neighbors, thulium and lutetium, which occur in the same concentrate at levels of about 0.5% each. The world production of ytterbium is only about 50 tonnes per year, reflecting the fact that ytterbium has few commercial applications. Microscopic traces of ytterbium are used as a dopant in the Yb:YAG laser, a solid-state laser in which ytterbium is the element that undergoes stimulated emission of electromagnetic radiation.

Symbol		Yb
Atomic Number		70
Atomic Weight		173.04
Oxidation States		+2, +3
Electronegativity, Pauling		1.27
State at RT		Solid, Metal
Melting Point, K		1097
Boiling Point, K		1466

Appearance and Characteristics

Harmful effects:

Ytterbium is considered to be moderately toxic.

Characteristics:

• Ytterbium is a bright, soft, silvery-white metal that is both ductile and malleable.
• It is a one of the rare earth metals.
• The metal tarnishes quickly in air and reacts slowly with water.
• It dissolves rapidly in mineral acids.

Uses of Ytterbium

• Isotope 160Yb is radioactive and is used in portable x-ray machines that need no electricity.
• Under very high physical stress Ytterbium’s electrical resistance increases by an order of magnitude. It is therefore used in stress gauges to monitor ground deformations caused by earthquakes or underground explosions.
• Ytterbium is used in alloys and is added to stainless steel to improve grain refinement and strength.
• Ytterbium fiber laser amplifiers are used in marking and engraving.
• Ytterbium compounds are also used as catalysts in the organic chemical industry.