| 释义 |
rare earth
noun
1. : any of a group of very similar oxides of metals or a mixture of such oxides that occur together often associated with thorium in widely distributed but relatively scarce minerals (as monazite, bastnaesite, xenotime, gadolinite) and that are separated only with difficulty (as by fractional crystallization or by ion exchange)
2. or rare-earth element or rare-earth metal : any of the series of metallic elements whose oxides are the rare earths, which include the fourteen elements following lanthanum through lutetium with atomic numbers 58 through 71, usually lanthanum itself, and according to some yttrium and even scandium, which are chiefly trivalent, and which except for lanthanum, lutetium, yttrium, and scandium form paramagnetic salts in many cases colored — symbol RE; compare cerium metal, lanthanide, periodic table, yttrium metal; element table |