Appearance and Characteristics
Harmful effects:
Gadolinium is considered to be moderately toxic.
Characteristics:
Gadolinium is a bright, soft, silvery-white metal that is both ductile and malleable.
It is one of the rare earth metals. It does not react in dry air but will tarnish to a flaky white oxide in moist air that does not protect it from further oxidation. The metal reacts slowly with water and is soluble in dilute acid. It produces colorless salts. When present in compounds, gadolinium exists mostly in the trivalent state (Gd3+). At room temperature the metal is paramagnetic, but it becomes ferromagnetic (strongly attracted by a magnet) when cooled. The Curie point of gadolinium is 17 oC. The 157Gd isotope has the highest thermal neutron capture cross-section of any known stable element.Uses of Gadolinium
Gadolinium is used in alloys of iron and chromium to improve resistance to high temperatures and oxidation. Gadolinium is used to make gadolinium yttrium garnets which have microwave applications. Gadolinium compounds are used as green phosphors in color television picture tubes. Because of its magnetic properties, gadolinium is also used in intravenous radiocontrast agents in magnetic resonance imaging (MRI).
Arc-melted alloys of gadolinium, silicon, and germanium demonstrate a strong magnetocaloric effect at room temperatures (where its temperature increases when it enters a magnetic field and decreases when it leaves the magnetic field) making it useful in the field of room temperature magnetic refrigeration.