Curium

Curium was first made in the 60-inch cyclotron at the University of California, Berkeley, by the team of Glenn Seaborg, Ralph James, and Albert Ghiorso in 1944. They bombarded a piece of the newly discovered element plutonium with alpha-particles (two protons and two neutrons, like helium but without the electrons). They then sent the piece to the Metallurgical Laboratory at the University of Chicago where a tiny sample of curium was separated and identified. However, like actinium, the discovery was kept secret until after the end of World War II. The news of the discovery was released to the public in November 1947.

Curium was named after Marie and Pierre Curie, who discovered radium. In the informal naming tradition, it followed the naming example of the lanthanide element gadolinium, which was named after Johan Gadolin, the explorer of rare-earth elements.

Curium is a hard, dense, silvery metal. For an actinide, it has a high melting and boiling point. It has a weak magnetic attraction at ambient conditions until it cools. All known isotopes of curium are radioactive.

Curium is used primarily for scientific research and for making heavier actinides. Isotopes of curium are used in power generation industries such as thermo-electric and thermionic converters.

The metal is used in x-ray spectrometers for quantitative analysis of rock structures and composition on the surface of Mars or other planetary bodies. It can also be used as a power source in medical and spacecraft applications. It is not currently used a nuclear fuel because of low availability and high price.

Curium readily reacts with oxygen forming mostly oxides. It can also form fluorides, chlorides, sulfides, selenides, and tellurides. Most of the compounds are faintly yellow.

Curium has two crystalline forms, one with a hexagonal symmetry. It does not exist in any other form.

Curium has approximately 19 isotopes with half-lives ranging from 15.6 million years to 18.1 years. All isotopes undergo self-sustaining nuclear chain reactions. Curium-250 is unusual as it mostly decays by spontaneous fission.

Curium is a man-made metal produced in nuclear reactors. It is produced in small amounts for research purposes.

It is present as one of the waste products in spent nuclear fuel and is present in nature in some areas historically used for nuclear weapons testing.

Any naturally occurring curium would have decayed away long ago, because even the longest half-life of 15.6 million years is shorter than the age of the Earth. Its past presence as an extinct radionuclide is detectable in its long-lived daughter, uranium-235. It may have been present in Oklo, Gabon, Earth’s natural nuclear fission reactor site.