A predicted element
Scandium is a light silvery metal with a yellowish tinge. Although it is quite a rare element, it is contained in many minerals. By its properties scandium is close to magnesium, calcium, aluminum, iron and rare earth elements, so it often replaces them in minerals. Around 100 minerals are known in which scandium may be found. There are only two specifically scandium minerals: thortveitite (Sc, Y)₂Si₂O₇ and sterrettite Sc(PO₄)•2H₂O.
How scandium was discovered
The existence of scandium was predicted by Dmitry Mendeleev in 1869, when a gap between calcium (the 20th element) and titanium (the 22nd element) was found in the Periodic Table. Mendeleev proposed to call the new element “ekaboron”. In 1879, the Swedish chemist Lars Fredrik Nilson, by using the spectrometry method, discovered a new element in the mineral euxenite, which contained various rare elements. The scientist named this element in honor of Scandinavia. However, Nilson was only able to obtain a small amount of scandium oxide, and metallic scandium was not obtained until 1937. Very little scandium is contained in the Earth’s crust, so producing it is a complex and laborious process.
Where scandium is used
The main field of application of scandium is making alloys and ceramics. Small additives of scandium (fractions of a percent) significantly increase the strength of magnesium and aluminum alloys, and raise the resistance of chromium and nichrome to oxidation. Ceramics with scandium oxide additives can withstand high temperatures and thermal shock. Steel alloyed with scandium is extremely strong and can be used for long periods of time at high temperatures.
Aluminum-scandium alloys have found an application in the aerospace industry, for example in parts for the Russian military aircraft MiG-21 and MiG-29.
Scandium oxide is used in supercomputers with a high speed of data exchange. Scandium compounds may be used in the manufacturer of lasers, solar batteries and MHD generators. Composites of scandium and wolfram, chromium and molybdenum are used for making X-ray mirrors.
Scandium oxide is also used in high-intensity lighting elements, and adding scandium iodide to the atmosphere of mercury-vapor lamps makes their light appear more natural.