Questions about Scandium
Short answers, pulled from the story.
What is scandium and what is it used for?
Scandium is a silvery-white metallic element with symbol Sc and atomic number 21, classified as a rare-earth element alongside yttrium and the lanthanides. Its main industrial application is in aluminium-scandium alloys, which are used in aerospace components, Russian military aircraft including the MiG-21 and MiG-29, and consumer products such as baseball bats, bicycle frames, and firearms made by Smith and Wesson. It is also used in metal-halide lamps, dental lasers, and as a tracing agent in oil refineries.
Who discovered scandium and when?
Lars Fredrik Nilson discovered scandium in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia, and prepared 2 grams of scandium oxide of high purity. He named the element after the Latin word Scandia for Scandinavia. His discovery confirmed a prediction Dmitri Mendeleev had made in 1869 for an undiscovered element he called ekaboron; Per Teodor Cleve recognized the match and notified Mendeleev.
Why is scandium so rare and expensive despite being abundant in the Earth's crust?
Scandium is present at 18 to 25 parts per million in Earth's crust, comparable to cobalt, but it is distributed sparsely across many minerals rather than concentrated in rich ore deposits. In 2003, only three mines worldwide produced scandium, all as a byproduct of extracting other elements. The price of scandium ingot was $107 to $134 per gram between 2015 and 2019, and global scandium oxide production remains at only 15 to 20 tonnes per year.
When was metallic scandium first produced and how?
Metallic scandium was first produced in 1937 by electrolysis of a eutectic mixture of potassium, lithium, and scandium chlorides at temperatures of 700 to 800 degrees Celsius. The first pound of 99% pure scandium metal was not produced until 1960. To produce metallic scandium, scandium oxide is converted to scandium fluoride and then reduced with metallic calcium.
What are the isotopes of scandium and which is stable?
Scandium has only one stable isotope, 45Sc, which occurs exclusively in nature. Known isotopes range from 37Sc to 63Sc; the most stable radioisotopes are 46Sc with a half-life of 83.76 days and 47Sc with a half-life of 3.3492 days. The radioactive isotope 46Sc is used in oil refineries as a tracing agent, and the 12.4 keV nuclear transition of 45Sc has been studied as a potential timekeeping reference with theoretical precision up to three orders of magnitude better than caesium clocks.
How does scandium strengthen aluminium alloys?
Adding 0.1% to 0.5% scandium to aluminium limits grain growth in the heat zone of welded components, produces smaller crystals than other aluminium alloys, and reduces precipitate-free zones at grain boundaries. The resulting alloy is described as strong as titanium, light as aluminium, and hard as some ceramics. Recent developments also incorporate zirconium and erbium shells around the precipitate to reduce coarsening and lower the overall scandium content needed.