Word: lanthanum
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...spring day in 1950, U.S. scientists perfecting techniques for tracking Soviet atomic tests packed a conventional bomb with radioactive material -- probably lanthanum-140 -- and exploded it in the atmosphere near Los Alamos, New Mexico. No injuries were reported, but the fallout reached populated areas at least 70 miles away...
Muller and his colleague, Johannes Georg Bednorz, tinkered with hundreds of different oxide compounds over the next few years, varying quantities and ingredients like alchemists in search of the philosopher's stone. Finally, in December 1985, they came across a compound of barium, lanthanum, copper and oxygen that seemed promising. When Bednorz tested the compound, he was startled to see signs of super-conductivity at an unprecedented 35 K, by far the highest temperature at which anyone had observed the phenomenon. Could this result be correct? Aware of some hastily made superconductivity claims that later could not be reproduced...
...team tried lanthanum, the rare-earth* component of the IBM compound. Maw-Kuen Wu, head of the team's Alabama unit and a former graduate student of Chu's, replaced the lanthanum with another rare-earth element, yttrium...
...much sought-after goal proved to be elusive. In the early 1970s scientists found an alloy of niobium and germanium that lost all resistance at 23 K. Then, last April, a group at the IBM Zurich Research Laboratory in Switzerland announced development of a compound of barium, lanthanum, copper and oxygen that appeared to begin the transition to superconductivity...
...commercial metals are so scarce as a group of 15 known as the "rare earths." They are so rare, in fact, that there is some question as to whether one of them exists at all. They have tongue-twisting names (praseodymium, gadolinium, cerium, lanthanum, ytterbium, etc.), are found in rare mineral deposits, mostly in India and Brazil. Until recently, the metals had limited uses...