| 单词 |
praseodymium |
| 释义 |
praseodymium Chem.|preɪziːəˈdɪmɪəm|
[mod.L., f. G. praseodym (C. A. von Welsbach 1885, in Monatshefte f. Chem. VI. 490), f. Gr. πράσιος leek-green (f. πράσον leek) + G. di)dym didymium: see -ium. Named in allusion to the colour of its salts and its isolation, with neodymium, from the supposed element didymium.]
A metallic element, similar to iron in appearance, which is a typical lanthanide and forms leek-green compounds in which it has a valency of three (rarely four), some of which are used to impart a yellow colour to glasses and ceramics. Atomic number 59; symbol Pr.
1885[see neodymium]. 1905Gooch & Walker Outl. Inorg. Chem. xix. 493 For more than fifty years the elementary character of didymium was accepted, until Auer von Welsbach, by a most laborious process of fractional precipitation of the double nitrate of didymium and ammonium, succeeded in isolating two distinctly different double nitrates..from which were prepared two different series of salts, of different elements, which were now named praseodymium and neodymium. 1922T. M. Lowry Inorg. Chem. xxxiv. 672 Praseodymium also resembles cerium in forming a dioxide, PrO2, when the nitrate is heated with potassium nitrate at 450°. 1950Thorpe's Dict. Appl. Chem. (ed. 4) X. 183/2 All cerium⁓bearing minerals contain some praseodymium, e.g. cerite from Arendal (Switzerland) contains up to 8% of Pr2O3, monazite sand from Brazil, 5·5–6·2%. 1971J. F. Liptrot Mod. Inorg. Chem. xxvi. 438 Lanthanum, cerium, praseodymium, neodymium and gadolinium may be obtained by reduction of their trichlorides with calcium at about 1000°C. 1974Encycl. Brit. Micropædia VIII. 179/2 Praseodymium is about one-third as abundant as lead and about a thousand times more plentiful than gold in the igneous rocks of the Earth's crust...Natural praseodymium is all stable isotope praseodymium-141. |
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