Appearance and Characteristics
Harmful effects:
Thulium is considered to be non-toxic.
Characteristics:
Thulium is a bright, soft, malleable, silvery-gray metal. It is a rare earth metal and is one of the least abundant. The metal tarnishes slowly in dry air to form the oxide and reacts with water to form the hydroxide and hydrogen gas. Tm3+ ions emit a strong blue luminescence when excited. When present in compounds, thulium exists usually in the trivalent state, Tm3+. It forms compounds – mostly green in color – with oxygen and the halogens.
Uses of Thulium
Radioactive isotope 170Tm is produced by bombarding thulium in a nuclear reactor. It has a half-life of 128 days and is used as a portable source of x-rays.
Thulium is used to dope yttrium aluminum garnets (YAG) used in lasers.
Thulium is also used in alloys with other rare earth metals.
Thulium is used in euro banknotes for its blue fluorescence under UV light to defeat counterfeiters.