AskDefine | Define holmium

Dictionary Definition

holmium n : a trivalent metallic element of the rare earth group; occurs together with yttrium; forms highly magnetic compounds [syn: Ho, atomic number 67]

User Contributed Dictionary

see Holmium

English

Etymology

Holmia (Stockholm), the hometown of Per Teodor Cleve, one of the discoverers of holmium.

Noun

  1. a metallic chemical element (symbol Ho) with an atomic number of 67.

Related terms

Translations

External links

For etymology and more information refer to: http://elements.vanderkrogt.net/elem/ho.html (A lot of the translations were taken from that site with permission from the author)

Estonian

Noun

  1. holmium

Finnish

Noun

  1. holmium

Extensive Definition

Holmium () is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite.

Notable characteristics

A trivalent metallic rare earth element, holmium has the highest magnetic moment (10.6µB) of any naturally-occurring element and possesses other unusual magnetic properties. When combined with yttrium, it forms highly magnetic compounds.
Holmium is a relatively soft and malleable element that is fairly corrosion-resistant and stable in dry air at standard temperature and pressure. In moist air and at higher temperatures, however, it quickly oxidizes, forming a yellowish oxide. In pure form, holmium possesses a metallic, bright silvery luster. Holmium oxide has some fairly dramatic color changes depending on the lighting conditions. In daylight, it is a tannish yellow color. Under trichromatic light, it is a fiery orange red, almost indistinguishable from the way erbium oxide looks under this same lighting. This has to do with the sharp emission bands of the phosphors, and the absorption bands of both oxides.

Applications

Because of its magnetic properties, holmium has been used to create the strongest artificially-generated magnetic fields when placed within high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator). Since it can absorb nuclear fission-bred neutrons, the element is also used in nuclear control rods. Other commercial applications of the element include;
  • Holmium oxide is used as a yellow or red glass coloring.
  • Holmium containing glass has been used as a calibration standard for UV/visible spectrophotometers
  • Holmium is one of the colorants used for cubic zirconia, for use in jewelry, providing a dichroic color in peach or yellow, depending on the lighting source.
  • Holmium may be used as the active ion in some solid state lasers
Few other uses have been identified for this element.

History

Holmium (Holmia, Latin name for Stockholm) was discovered by Marc Delafontaine and Jacques-Louis Soret in 1878 who noticed the aberrant spectrographic absorption bands of the then-unknown element (they called it "Element X"). Later in 1878, Per Teodor Cleve independently discovered the element while he was working on erbia earth (erbium oxide).
Using the method developed by Carl Gustaf Mosander, Cleve first removed all of the known contaminants from erbia. The result of that effort was two new materials, one brown and one green. He named the brown substance holmia (after the Latin name for Cleve's home town, Stockholm) and the green one thulia. Holmia was later found to be the holmium oxide and thulia was thulium oxide.
Holmium (as the oxide) would not be obtained reasonably pure until the 20th century, and would not become commercially available in high purity until the late 1950's. The Lindsay Chemical Division of American Potash and Chemical Corporation was one of the first producers, using the newly-developed ion-exchange technology to purify holmium as isolated from monazite, in which it was present in trace amounts. In 1960, one pound of 99% holmium oxide was priced at US $105, and the 99.9% grade cost US $125, which were the same prices as were charged for the comparable oxides of gadolinium, dysprosium, and erbium. One of the early applications was in the form of a glass called a "holmium oxide plate" which was used (by 1965) as a calibration standard for UV/visible spectroscopy.

Occurrence

Like all other rare earths, holmium is not naturally found as a free element. It does occur combined with other elements in the minerals gadolinite, monazite, and in other rare-earth minerals. It is commercially extracted via ion-exchange from monazite sand (0.05% holmium) but is still difficult to separate from other rare earths. The element has been isolated through the reduction of its anhydrous chloride or fluoride with metallic calcium. Its estimated abundance in the Earth's crust is 1.3 milligrams per kilogram. Holmium obeys the Oddo-Harkins rule: as an odd-numbered element, it is less abundant than its immediate even numbered neighbors, dysprosium and erbium. However, it is the most abundant of the odd-numbered heavy lanthanides. The principal current source are some of the ion-adsorption clays of southern China. Some of these have a rare earth composition similar to that found in xenotime or gadolinite. Yttrium makes up about two-thirds of the total by weight; holmium is around 1.5%. The original ores themselves are very lean, maybe only 0.1% total lanthanide, but are easily extracted.

Isotopes

Natural holmium contains one stable isotope, holmium 165. Some synthetic radioactive isotopes are known, the most stable one is holmium 163, with a half life of 4570 years. All other radioisotopes have half lives not greater than 1.117 days, and most have half lives under 3 hours.

Precautions

The element, as with other rare earths, appears to have a low degree of acute toxicity. Holmium plays no biological role in humans but may be able to stimulate metabolism.

References

External links

holmium in Arabic: هولميوم
holmium in Bengali: হলমিয়াম
holmium in Belarusian: Гольмій
holmium in Bosnian: Holmijum
holmium in Catalan: Holmi
holmium in Czech: Holmium
holmium in Corsican: Olmiu
holmium in Danish: Holmium
holmium in German: Holmium
holmium in Estonian: Holmium
holmium in Modern Greek (1453-): Όλμιο
holmium in Spanish: Holmio
holmium in Esperanto: Holmio
holmium in Basque: Holmio
holmium in Persian: هولمیوم
holmium in French: Holmium
holmium in Friulian: Olmi
holmium in Manx: Holmium
holmium in Galician: Holmio
holmium in Korean: 홀뮴
holmium in Armenian: Հոլմիում
holmium in Croatian: Holmij
holmium in Ido: Holmio
holmium in Indonesian: Holmium
holmium in Italian: Olmio
holmium in Hebrew: הולמיום
holmium in Javanese: Holmium
holmium in Latin: Holmium
holmium in Latvian: Holmijs
holmium in Luxembourgish: Holmium
holmium in Lithuanian: Holmis
holmium in Lojban: jinmrxolmi
holmium in Hungarian: Holmium
holmium in Malayalam: ഹോമിയം
holmium in Marathi: होल्मियम
holmium in Dutch: Holmium
holmium in Japanese: ホルミウム
holmium in Norwegian: Holmium
holmium in Norwegian Nynorsk: Holmium
holmium in Occitan (post 1500): Òlmi
holmium in Polish: Holm (pierwiastek)
holmium in Portuguese: Hólmio
holmium in Russian: Гольмий
holmium in Sicilian: Olmiu
holmium in Slovak: Holmium
holmium in Slovenian: Holmij
holmium in Serbian: Холмијум
holmium in Serbo-Croatian: Holmijum
holmium in Finnish: Holmium
holmium in Swedish: Holmium
holmium in Thai: โฮลเมียม
holmium in Vietnamese: Holmi
holmium in Turkish: Holmiyum
holmium in Ukrainian: Гольмій
holmium in Chinese: 钬
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