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Template:Elementbox header Template:Elementbox series Template:Elementbox periodblock Template:Elementbox appearance img Template:Elementbox atomicmass gpm Template:Elementbox econfig Template:Elementbox epershell Template:Elementbox section physicalprop Template:Elementbox phase Template:Elementbox density gpcm3nrt Template:Elementbox densityliq gpcm3mp Template:Elementbox meltingpoint Template:Elementbox boilingpoint Template:Elementbox heatfusion kjpmol Template:Elementbox heatvaporiz kjpmol Template:Elementbox heatcapacity jpmolkat25 Template:Elementbox vaporpressure katpa Template:Elementbox section atomicprop Template:Elementbox crystalstruct Template:Elementbox oxistates Template:Elementbox electroneg pauling Template:Elementbox ionizationenergies4 Template:Elementbox atomicradius pm Template:Elementbox atomicradiuscalc pm Template:Elementbox covalentradius pm Template:Elementbox section miscellaneous Template:Elementbox magnetic Template:Elementbox eresist ohmm Template:Elementbox thermalcond wpmkat300k Template:Elementbox thermalexpansion umpmk Template:Elementbox youngsmodulus gpa Template:Elementbox shearmodulus gpa Template:Elementbox bulkmodulus gpa Template:Elementbox poissonratio Template:Elementbox vickershardness mpa Template:Elementbox brinellhardness mpa Template:Elementbox cas number Template:Elementbox isotopes begin |- ! style="text-align:right;" | Lu | style="text-align:center;" | syn | style="text-align:right;" | 1.37 y | ε | style="text-align:right;" | Yb |- ! style="text-align:right;" | Lu | style="text-align:center;" | syn | style="text-align:right;" | 3.31 y | ε | style="text-align:right;" | Yb Template:Elementbox isotopes stable |- ! style="text-align:right;" | Lu | style="text-align:right;" | 2.59% | style="text-align:right;" | 3.78×10y | β | style="text-align:right;" | Hf Template:Elementbox isotopes end Template:Elementbox footer

Lutetium (Template:PronEng) is a chemical element with the symbol Lu and atomic number 71. A silvery-white rare metal, lutetium is the heaviest member of the rare-earth group. Its radioactive isotope is used in nuclear technology to determine the age of meteorites. lutetium usually occurs in association with yttrium and is sometimes used in metal alloys and as a catalyst in various processes. A strict correlation between periodic table blocks and chemical series for neutral atoms would describe lutetium as a transition metal because it is in the d-block, but it is a lanthanide according to IUPAC.

Nonsense

Elemental lutetium has a close-packed hexagonal crystal structure. There are two natural isotopes of lutetium; Lu and Lu. Lu has a half-life of 2.2E10 years. There are 14 artificial isotopes; the first was created independently by G. Urban in 1907 and C. A. Von Welsbach in 1908.

Notable characteristics and applications

Lutetium is a silvery white corrosion-resistant trivalent metal that is relatively stable in air. Lutetium is the heaviest and hardest of the rare earth elements. Lutetium has the highest melting point of any lanthanide, probably related to the lanthanide contraction.

This element is very expensive to obtain in useful quantities and therefore it has very few commercial uses. However, stable lutetium can be used as catalysts in petroleum cracking in refineries and can also be used in alkylation, hydrogenation, and polymerization applications.

Lutetium-176 (Lu) has been used to date the age of meteorites.

Lutetium aluminium garnet (Al₅Lu₃O₁₂) has been proposed for use as a lens material in high refractive index immersion lithography.

Lutetium-177 (Lu), when bound to Octreotate (a somatostatin analogue), is used experimentally in targeted radionuclide therapy for neuroendocrine tumours.

Cerium-doped lutetium oxyorthosilicate (LSO) is currently the preferred compound for detectors in positron emission tomography (PET.)

History

Lutetium (Latin Lutetia meaning Paris) was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach and American chemist Charles James. All of these men found lutetium as an impurity in the mineral ytterbia which was thought by Swiss chemist Jean Charles Galissard de Marignac (and most others) to consist entirely of the element ytterbium.

The separation of lutetium from Marignac's ytterbium was first described by Urbain and the naming honor therefore went to him. He chose the names neoytterbium (new ytterbium) and lutecium for the new element but neoytterbium was eventually reverted back to ytterbium and in 1949 the spelling of element 71 was changed to lutetium.

Welsbach proposed the names cassiopium for element 71 (after the constellation Cassiopeia) and aldebaranium for the new name of ytterbium but these naming proposals where rejected (although many German scientists in the 1950s called the element 71 cassiopium).

Occurrence

Found with almost all other rare-earth metals but never by itself, lutetium is very difficult to separate from other elements. Consequently, it is also one of the most expensive metals, costing about six times as much as gold.

The principal commercially viable ore of lutetium is the rare earth phosphate mineral monazite: (Ce, La, etc.) PO₄ which contains 0.003% of the element. Pure lutetium metal has only relatively recently been isolated and is very difficult to prepare (thus it is one of the most rare and expensive of the rare earth metals). It is separated from other rare earth elements by ion exchange and then obtained in the elemental form by reduction of anhydrous LuCl₃ or LuF₃ by either an alkali metal or alkaline earth metal.

Isotopes

Naturally occurring lutetium is composed of 1 stable isotope Lu (97.41% natural abundance) and 1 long-lived beta-radioactive isotope Lu with a half-life of 3.78×10 years (2.59% natural abundance). The last one is used in the radiometric dating (see Lutetium-hafnium dating). 33 radioisotopes have been characterized, with the most stable being naturally occurring Lu, and artificial isotopes Lu with a half-life of 3.31 years, and Lu with a half-life of 1.37 years. All of the remaining radioactive isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than a half an hour. This element also has 18 meta states, with the most stable being Lu (T_½=160.4 days), Lu (T_½=142 days) and Lu (T_½=23.1 minutes).

The known isotopes of lutetium range in atomic weight from 149.973 (Lu) to 183.961 (Lu). The primary decay mode before the most abundant stable isotope, Lu, is electron capture (with some alpha and positron emission), and the primary mode after is beta emission. The primary decay products before Lu are element 70 (ytterbium) isotopes and the primary products after are element 72 (hafnium) isotopes.

Applications

Lutetium is very expensive (upwards of $100 per gram) to obtain on useful quantities and therefore it has very few commercial uses. Some commercial applications include:

• Use as a pure beta emitter, using lutetium which has been exposed to neutron activation. A tiny amount of lutetium is added as a dopant to gadolinium gallium garnet (GGG), which is used in magnetic bubble memory devices.
• Use as a catalyst in the petroleum industry, or in organic light-emitting diodes (OLEDs).
• Research into possible uses for targeted radiotherapy for the development of new cancer therapies.
• Cerium-doped lutetium orthosilicate (Lu₂SiO₅:Ce), known as LSO, is a scintillator used mainly for Positron Emission Tomography.

Compounds

Fluoride: LuF₃, Chloride: LuCl₃, Bromide: LuBr₃, Iodide: LuI₃, Oxide: Lu₂O₃, Sulfide: Lu₂S₃, Nitride: LuN

Intermetalic compounds:

• Lutetium aluminium garnet

See also lutetium compounds.

Precautions

Like other rare-earth metals lutetium is regarded as having a low degree of toxicity but it and especially its compounds should be handled with care nonetheless. Metal dust of this element is a fire and explosion hazard. Lutetium plays no biological role in the human body but is thought to help stimulate metabolism.

References

• Guide to the Elements - Revised Edition, Albert Stwertka, (Oxford University Press; 1998) ISBN 0-19-508083-1
• Los Alamos National Laboratory's Chemistry Division: Periodic Table - Lutetium

1. Parker, Sybil P., ed. Dictionary of Scientific and Technical Terms. 3rd ed. New York: McGraw-Hill, 1984.
2. American Heritage. The American Heritage Science Dictionary. Boston: Houghton Mifflin, 2005.
3. IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004) (online draft of an updated version of the "Red Book" IR 3-6)
4. Considine, Douglas M., ed. Van Nostrad's Scientific Encyclopedia. 5th ed. Toronto: Litton Educational Publishing, 1976.
5. Thompson CJ. Instrumentation. In: Wahl RL,ed. Principles and Practice of Positron Emission Tomography. Philadelphia: Lippincott Williams and Wilkins, 2002:51.
6. Separation of Rare Earth Elements

External links

• WebElements.com - Lutetium (also used as a reference)
• It's Elemental - Lutetium
• pure Lutetium >99,9% picture in the element collection from Heinrich Pniok

• Chemical elements
• Lanthanides
• Transition metals