Holmium

Name: Holmium
Symbol: Ho
Atomic Number: 67
Mass fraction of the earth’s shell: 1 x 10−4
Melting Point: 1474 °C
Boiling Point: 2695 °C
Electrical Conductivity: 1,24· 106 A·V−1·m−1

Name: Holmium
Symbol: Ho
Atomic Number: 67
Mass fraction of the earth’s shell: 1 x 10−4
Melting Point: 1474 °C
Boiling Point: 2695 °C
Electrical Conductivity: 1,24· 106 A·V−1·m−1

HISTORY

Jacques Louis Soret
Jacques-Louis Soret

In 1878, a year before Edison invented the light bulb, the Swiss chemists Marc Delafontaine and Jacques-Louis Soret noticed the deviating absorption lines of a new element. They initially named it Element X. One year later, the Swedish chemist Per Theodor Cleve isolated the same element as a yellow oxide from impure erbium. To do this, Cleve separated all the known impurities, and then isolated the rest.

Thirty-two years later, the Swedish chemist Holmberg succeeded in obtaining pure holmium oxide. The name of the element comes from Holmia, the Latin name for Stockholm.

CHARACTERISTICS & EXTRACTION

The pure element occurs in nature exclusively as the isotope 165Ho. The ductile heavy metal reacts in moist air. If it comes into contact with water, hydrogen and holmium hydroxide are formed. After the holmium companions have been separated, holmium fluoride is formed from the oxide with the addition of hydrogen fluoride. Together with calcium, metallic holmium is formed with the formation of calcium fluoride. Remelting in a vacuum removes the last calcium residues.

Holmium is also used in the production of catalysts and glass polishes.

Pole shoes made of holmium generate the strongest magnetic fields and are found in high-performance magnets. Thin-film alloys of holmium-iron, holmium-nickel, and holmium-cobalt are needed to produce magnetic bubble storage. Other applications include control rods in breeder reactors and microwave components in medical technology. In photometers, holmium oxide imparts a yellow colour to the glass.