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Jai Ganesh

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Holmium

Holmium

Gist

Holmium (Ho) is a soft, silvery-white, rare-earth element with atomic number 67, known for having the greatest magnetic strength of any element. It is used in applications requiring strong magnetic fields, such as nuclear reactor control rods and components in high-strength magnets, as well as in lasers, glass coloring, and as a calibration standard for spectrometers.

Holmium (Ho) is a rare earth element with diverse applications, primarily due to its strong magnetic properties and ability to absorb neutrons. It's used in powerful magnets, nuclear reactor control rods, and specialized lasers for medical procedures. It also finds use in coloring glass and cubic zirconia, and as a dopant in certain materials.

Summary

Holmium is a chemical element; it has symbol Ho and atomic number 67. It is a rare-earth element and the eleventh member of the lanthanide series. It is a relatively soft, silvery, fairly corrosion-resistant and malleable metal. Like many other lanthanides, holmium is too reactive to be found in native form, as pure holmium slowly forms a yellowish oxide coating when exposed to air. When isolated, holmium is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily, and also burns in air when heated.

In nature, holmium occurs together with the other rare-earth metals (like thulium). It is a relatively rare lanthanide, making up 1.4 parts per million of the Earth's crust, an abundance similar to tungsten. Holmium was discovered through isolation by Swedish chemist Per Theodor Cleve. It was also independently discovered by Jacques-Louis Soret and Marc Delafontaine, who together observed it spectroscopically in 1878. Its oxide was first isolated from rare-earth ores by Cleve in 1878. The element's name comes from Holmia, the Latin name for the city of Stockholm.

Like many other lanthanides, holmium is found in the minerals monazite and gadolinite and is usually commercially extracted from monazite using ion-exchange techniques. Its compounds in nature and in nearly all of its laboratory chemistry are trivalently oxidized, containing Ho(III) ions. Trivalent holmium ions have fluorescent properties similar to many other rare-earth ions (while yielding their own set of unique emission light lines), and thus are used in the same way as some other rare earths in certain laser and glass-colorant applications.

Holmium has the highest magnetic permeability and magnetic saturation of any element and is thus used for the pole pieces of the strongest static magnets. Because holmium strongly absorbs neutrons, it is also used as a burnable poison in nuclear reactors.

Details

Holmium (Ho) is a chemical element, a rare-earth metal of the lanthanide series of the periodic table.

Holmium is a moderately hard, silvery white metal that is relatively stable in air. It readily reacts with diluted acids but does not react with either diluted or concentrated hydrofluoric acid (HF), due to formation of a protective surface layer of HoF3. Holmium is a very strong paramagnet above 133 K (−140 °C, or −220 °F). At that temperature the metal orders antiferromagnetically, forming a basal plane spiral structure. At 19 K (−254 °C, or −425 °F) the magnetic moments tilt along the c-axis lifting out of the basal plane by some 10°, forming a conical ferrimagnetic structure.

Holmium was discovered spectroscopically (1878) by Swiss chemists Jacques-Louis Soret and Marc Delafontaine and independently (1879) by Swedish chemist Per Teodor Cleve, who separated it chemically from erbium and thulium. Cleve named the element for his native city of Stockholm, its Latinized name being Holmia. Holmium occurs associated with other rare earths in laterite clays and in the minerals xenotime, euxenite, and many others; it also occurs in the products of nuclear fission.

The one naturally occurring isotope, holmium-165, is stable. There are numerous radioactive isotopes (a total of 35, not counting nuclear isomers), ranging from holmium-140 to holmium-175 and having half-lives from 4.1 milliseconds (holmium-141) to 4,570 years (holmium-163). Holmium is one of the least abundant rare earths; its abundance in Earth’s crust is comparable to that of thallium.

The classical methods of separating and purifying the element were fractional crystallization and precipitation, but solvent-solvent extraction and ion-exchange technologies have made available kilogram quantities of highly pure holmium oxide. The metal is produced by metallothermic reduction of the anhydrous fluoride HoF3 with calcium. Only one allotropic (structural) form is known for holmium. The metal adopts a close-packed hexagonal structure with a = 3.5778 Å and c = 5.6178 Å at room temperature.

Holmium and its compounds have limited applications except for research. Holmium has been used as a component of some electronic devices; the ion Ho3+ has been used as a catalyst for ortho-para hydrogen conversion; and the oxide has been used as a special refractory.

Holmium behaves as a typical rare earth. It forms a series of yellow-brown salts, many of which are obtained in solution by dissolving the oxide Ho2O3 in the appropriate acid.

Element Properties

atomic number  :  67
atomic weight  :  164.930328
melting point  :  1,474 °C (2,685 °F)
boiling point  :  2,700 °C (4,892 °F)
specific gravity  :  8.795 (24 °C, or 75 °F)
oxidation state  :  +3.

Additional Information:

Appearance

A bright, silvery metal.

Uses

Holmium can absorb neutrons, so it is used in nuclear reactors to keep a chain reaction under control. Its alloys are used in some magnets.

Biological role

Holmium has no known biological role, and is non-toxic.

Natural abundance

Holmium is found as a minor component of the minerals monazite and bastnaesite. It is extracted from those ores that are processed to extract yttrium. It is obtained by ion exchange and solvent extraction.

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