Scandium

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.

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